text:
Why is it advised that infants are fed mother's milk?
I have heard that mother's milk is preferred over other baby foods, because it contains immunoglobulins (secretory IgA), and other essential nutrients.
But why is mother's milk so special? Any mammalian milk, such as the widely available cow's milk, should presumably have a similar composition as human milk? What makes mother's milk in specific so healthy?
Could the mere act of breastfeeding, in itself, lend to some beneficial outcome?

I think I read a comment on the parenting stack exchange about this topic, and it spoke on the benefits of mother and child bonding.

Was there a neuroendocrinological basis given for substantiating the bonding hypothesis ?

Just taking the immunoglobulins alone, I would ask you this: do you think cows have immunoglobulins likely to match the needs of a human infant as precisely as the human child's own mother (same pathogens, same environment, etc.) or that a cow's immunoglobulins are more likely a better match for that cow's own offspring? This goes across the board for all mammals in all differing locations (i.e. a mother's milk in Malaysia will have a different antibody composition than one in, say, Canada.

Anecdotal evidence (n=1): My 3yo daughter caught chickenpox and we have a 5 month old baby too. They are often close together and touch a lot. Baby is breastfed by mother who had chickenpox already (so she has antibodies). Baby is breastfed and didn't catch the (highly infectious) chickenpox.

@TomášKafka: you seem to be into something. WebMD endorses your anecdotal evidence: http://www.webmd.com/vaccines/tc/chickenpox-varicella-what-happens (2nd bullet point).

@fredsbend I think you're just simplifying to the point of basically attacking a strawman. It's been observed that some antibodies (and other immune system-related "stuff") are passed to the child in milk, and some of them survive the infant's digestive system. Some is the key word, of course - it's nowhere near 100% effective, and it still depends on the baby's own immune system. The kid just gets a headstart on the markers, giving it a much better chance of coping with the infection - provided the mother is also exposed to the same infection (whether she gets sick or not).

@TomášKafka When I was two or three years old my brother (older by three years) caught chickenpox at school. My mother had already had it but my father and I hadn't had it yet. My brother had a bit of a temperature and a lot of spots. My dad became very sick with a fever and a lot of spots. Because I was so young I only got a few spots and no temperature. Neither my brother nor I were protected by my mother having chickenpox before we were born. It's more likely that your baby got it but showed no symptoms.

@anongoodnurse Adding to the issue of immunoglobulins; pasteurization (which is performed basically on all milk sold to consumers) will decrease the amount of immunoglobulins quite a bit. So even if immunoglobulins from cow's milk would be useful, they are mostly lost in pasteurized milk. Related, Chantry et al. (2009, J Acquir Immune Defic Syndr.) is studying the effect of flash-heat pasteurization on immunoglobulins in human breast milk, since flash-heating is used as a way to reduce vertical HIV transmission.

Well, I can't say necessarily mother's milk. It is possible for a woman to feed the child that is not born by her. And I can't say that mother's milk in this case gives an advantage over other woman's milk.

The phrase "Breast is best" is a hotly debated one (source: The Guardian and personal communications with many folks). The reason why we don't want to feed infants cow's milk is, however, anything but debated, because
Cow's milk does not provide enough:

Vitamin E
Iron
Essential fatty acids

And because it contains too much:

Protein
Sodium
Potassium (source: NIH's MedLine)
Further, mother's milk is generally free of pathogens, cow's milk may not be (source: Australian Unity). However note that, unfortunately, HIV can hitchhike within the maternal white blood cells to the infant (Quintanilla, 1996)

There are many benefits to mother and infant of breast milk. These benefits are, however, typically compared to the benefits over formula. No study will compare the benefits of mother's milk over cow's milk, simply because infants should never be fed cow's milk.
The benefits of breast milk for the infant are the following:

Breast milk a nearly perfect mix of vitamins, protein, and fat, all provided in an easily digestible form, as compared to formula;
Breastfeeding lowers baby's risk of having asthma or allergies;
Plus, babies who are breastfed exclusively for the first 6 months, without any formula, have fewer ear infections, respiratory illnesses, and bouts of diarrhea. They also have fewer hospitalizations and trips to the doctor (source: WebMD).
Breast milk contains a variety of growth factors, including EGF, BDNF and GDNF that may promote vascularization and neural development (Ballard & Morrow, 2014).

There are a host of immunoprotective factors present in breast milk. These proteins offer protection against diarrhoea, food allergies and infections. The immunoprotective components of human milk include, but are not limited to:

Lactoferrin : binds to iron, thus rendering it unavailable to viruses, fungi and bacteria, which is an effective means of inhibiting their growth (Ballard & Morrow, 2014);
Lysozymes: destroy viruses and bacteria by disrupting their integrity (source: NIH's MedLine);
Secretory IgA: immunoglobulins that destroy viruses and bacteria. Secretory IgA is believed to survive the harsh conditions of the intestines, especially in infants and is therefore active in the intestines of the baby. IgA can bind to pathological viruses and block their receptors necessary to invade the epithelial cells lining the intestinal wall. It also clumps bacteria together through cross-linking, which may affect their dispersion. Bacterial cell membranes, like shown in Salmonella, may be disrupted by IgA binding (Mantis et al., 2011). As mentioned by anongoodnurse in the comments; because mother and baby share the same habitat and hence encounter the same pathogens, the antibodies produced by the mother will be more beneficial to the baby than any other mammal on earth;
Human milk contains a variety of chemokines and cytokines that can cross the intestinal barrier, where they communicate with baby's cells to influence immune activity. Many cytokines and chemokines have multiple functions, and milk-borne cytokines may be grouped broadly into those that enhance inflammation or defend against infection, and those that reduce inflammation (Ballard & Morrow, 2014);
Bifidus factor: promotes the growth of beneficial bacteria in the gut and limits the growth of disease-causing bacteria (source: NIH's MedLine).
A variety of immune cells, including macrophages, T cells, stem cells, and lymphocytes. In early lactation, the breastfed infant may consume as many as 1010 maternal leukocytes per day. They can differentiate into dendritic cells that stimulate infant T-cell activity (Ballard & Morrow, 2014).
Breast milk changes in composition according to the infant's needs, something cow's milk can never accomplish; The first fluid produced by mothers after delivery is colostrum, which is distinct in volume, appearance and composition. Colostrum is produced in low quantities in the first few days postpartum and is rich in immunologic components such as secretory IgA, lactoferrin, leukocytes, as well as developmental factors such as epidermal growth factor. It contains relatively low concentrations of lactose, indicating its primary functions to be immunologic and trophic rather than nutritional. Levels of sodium, chloride and magnesium are higher and levels of potassium and calcium are lower in colostrum than later milk (Ballard & Morrow, 2014).

For more complete reviews on the immunochemistry of breast milk, please refer to Ballard & Morrow (2014) and Mantis et al. (2011)
The mother also benefits:

Breastfeeding burns extra calories, so it can help mothers to lose pregnancy weight faster;
Breast feeding releases the hormone oxytocin, which helps the uterus return to its pre-pregnancy size and may reduce uterine bleeding after birth;
Breastfeeding lowers the risk of breast and ovarian cancer. It may lower the risk of osteoporosis;
Breastfeeding has been linked to higher IQ scores in later childhood in some studies (source: WebMD);
During lactation, menstruation ceases, offering a form of contraception;
Mothers who breastfeed are less likely to develop breast cancer later in life;
Breastfeeding is more economical than formula feeding;
Hormones released during breast-feeding create feelings of warmth and calm in the mother (source: NIH's MedLine).

In terms of bonding:

Skin-to-skin contact during breastfeeding, and eye contact all help a baby bond with the mother and feel secure.
Oxytocin release is known to promote the bonding with bubba. A newly born person can cause dramatic changes in the life of mommie (and daddy!), and a steady release of oxytocin promotes the bonding and love of mommie for the bubba (source: WebMD).

References
- Ballard & Morrow, Pediatr Clin North Am (2013); 60(1): 49–74
- Mantis et al., Mucosal Immunology (2011) 4: 03–611
- Quintanilla, Nurs Times, (1996); 92(31): 35-7

I think this answer is very good; I'm not likely to top it for scope. The only thing I would add is more about antibodies and other contributors to immune function. (If you're interested, I left a comment under the question.) Here's another open source NIH paper that goes into more detail. +1

It should also be noted that (various levels and kinds) of milk allergy are rather common in infants, so for an interesting portion of the population, cow milk simply isn't a substitute even when combined with a formula. Often the mother has to avoid milk products as well, since enough of the protein makes it to the breast milk. And many formulas contain cow milk as well, so you're stuck with the very expensive ones tailored for infants with allergy.

+1 for a good and complete answer for the benefits of mothers milk. However as you stated yourself the issue is hotly debated. It would be nice to also add some disadvantages of breast-feeding. One example: producing milk is an energy-consuming process that slows down the recovery of the mother after giving birth. (Sorry no reference).

@RHA while it's an interesting subject, I think that's outside the scope of a question that's about whether milk from other mammals wouldn't be as good as breastmilk.

@RHA (sorry, deleted the first comment to rephrase) except for the "Breastfeeding is more economical than formula feeding", I find this answer to be mostly focused on human vs animal milk. True, some points are independent of what sort of milk it is and relate to breastfeeding specifically (and wouldn't apply to pumping, for example), but other than that, I seem to be reading the answer different than you are.

@RHA A working brain is also very energy-consuming. Should that be included in its disadvantages? // Child bearing by healthy women does not customarily require immediate "recovery" and it's completely not a given that stopping breast-feeding will have any positive clinical effect on the mother's "recovery". Not using up what your body wants to give away might in fact be determental to the overall health.

Actually, menstruation ceases when breastfeeding for some time. The woman will be fertile despite breastfeeding after a while. http://www.llli.org/nb/nbsepoct06p196.html

The point on pathogen transmission via milk is not really correct as you yourself have contradicted the point with the HIV example. There are many other pathogens that can be transmitted via milk. The issue with animal milk is that it may be difficult to check if the animal was infected.

I think the central point that would emerge from the entire picture is that the milk composition of a species is evolved such that it improves the fitness of that species. Buffalo milk has high fat and proteins compared to cow's milk but buffalo also produces lesser offspring (and a higher gestation period). A nutrient rich milk will ensure the calf's health/development and survival. So, in short, the milk composition is optimized according to the dietary/health requirements of the corresponding species.

@WYSIWYG - that's the debate. Nutritional value can be artificially reproduced. It's the immunological factors that are species and even individual specific. That's the point.

Aw, the bonding bit was nice. Quite scary how busy life, might then interfere and disrupt these potential bonding opportunities...

Lysozyme degrades bacterial cell walls, it does not affect viruses.

To further emphasize colostrum, infant have very weak immune systems early on and the supplimentation by the breastmilk is very helpful.

I think it would be better to cite this regarding HIV transmission: https://www.advancesinpediatrics.org/article/S0065-3101(07)00015-1/fulltext#sec4.5.6

The contents of milk differ between species. For your example, cow's milk:

Infants fed WCM [Whole Cow's Milk] have low intakes of iron, linoleic acid, and vitamin E, and excessive intakes of sodium, potassium, and protein

Calves have different nutrition needs from human babies. Infants who receive cow's milk instead of breastmilk often suffer from iron deficiency (anemia).
As for antibodies, human babies will benefit the most from antibodies that help against diseases infecting humans, which are not the same as those infecting cows.

Calves have different nutrition needs from human babies. You hit the exact point, IMO. It applies for every species.


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Why doesn't RNA polymerase just rotate?
I read A little help understanding DNA supercoiling , Understanding DNA supercoiling , and Why does underwinding create topological strain of DNA? , but there's still something I don't get. Transcription creates positive supercoils ahead of the RNA polymerase and negative supercoils behind it, and according to my TA's, this causes enough mechanical strain to sometimes even stop transcription from occurring. Why doesn't the polymerase just rotate around the DNA to relieve the strain?
The video below is helpful to communicate what the question is asking. The model I was taught is that the polymerase proceeds on a linear path, not a helical path, and thus the transcription bubble forces positive supercoils ahead and negative behind. The video shows this with a pen in place of the polymerase and a shoelace in place of the DNA; displacement of the pen tightens coils downstream and loosens them upstream. The way this seems to depart from reality is the desk or backdrop in the video, which keeps the pen from spinning, and the air, which offers no friction or thermal energy. In real life, the polymerase isn't a pen and the DNA isn't sitting on a desk and the surrounding medium is aqueous and of course the whole thing is at a smaller physical scale such that heat is experienced differently. But why doesn't the pen (polymerase) just spin?
https://www.youtube.com/watch?v=J4YlcD59-yw
P.S. I also looked at Does RNA polymerase move around DNA or does DNA rotate beneath the polymerase?, but I'm not sure what to take from that thread. Some answers disagree and others only mention unwinding, which afaik is a much lesser source of strain compared to the lack of rotation.

Comments are not for extended discussion; this conversation has been moved to chat.

Consider that:

RNA polymerase (RNAP) is a large complex (~400 kDa in bacteria); inertia and drag would hinder its rotation.
RNAP is attached to its RNA transcript, which becomes increasingly large as transcription proceeds thus increasing inertia and drag. Additionally, if RNAP were to begin to rotate around DNA, the transcript could begin to wrap around the DNA.
The RNA transcript is often bound by proteins/ribonucleoproteins, including ribosomes in prokaryotes (which undergo cotranscriptional translation), further increasing the complex’s size and making it more difficult to rotate.

These ideas are discussed in the original paper which proposes the “twin transcriptional loop” or “twin supercoiled domain” model to explain the observation of transcriptionally coupled DNA supercoiling:
Liu LF, Wang JC. 1987. Supercoiling of the DNA template during transcription. Proc Natl Acad Sci USA 84(20):7024–7027.
For this model to work, the torque required to supercoil DNA, which would cause rotation of the RNAP complex, must be overcome by the frictional torque opposing rotation of said complex. A mathematical treatment in this paper estimates that RNAP itself with a modestly sized transcript and a single ribosome bound would not be sufficient to introduce significant supercoiling in dilute aqueous solution.
However, they estimate that a larger transcript with 20 ribosomes attached would have sufficient frictional torque opposing RNAP rotation to cause some supercoiling of DNA. Furthermore, the authors recognize that this model in dilute aqueous solution is not representative of actual conditions within a cell, where the presence of other macromolecules could impede RNAP rotation much more significantly than water alone.
Additionally, RNAP itself, the RNA transcript or the proteins which bind it may be physically anchored to some cellular structure during transcription. For example:

RNAP can be bound to DNA outside of the transcription bubble through some intermediary regulatory protein
Ribosomes translating extracellular or membrane-bound proteins are attached to the cell membrane in prokaryotes.

Such physical anchoring of the transcription complex would certainly prevent its rotation around the DNA helix.

It is perhaps also important to point out that cells have topoisomerases which relieve the superhelical strain generated by transcription (among other processes). If the torque on RNAP caused by supercoiling is negated by these topoisomerases, there isn’t really another force which would cause RNAP to rotate. Nevertheless, supercoiling as a result of transcription does occur in vivo and has important implications on genomic structure and gene regulation. See the following paper for a review:
Ma J, Wang MD. 2016. DNA supercoiling during transcription. Biophys Rev 8(Suppl 1):75–87.

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text:
What chemical conversions are involved , and what's the name for the process, when the muscles use lactate as an energy source?
I understand that muscles do anaerobic metabolism, specifically, "lactic acid fermentation", which I understand produces lactate. I'm not asking about that process.
What chemical conversions are involved , and what's the name for the process, when the muscles use lactate as an energy source?
I'm aware that it can happen as    This paper, is tellingly and usefully titled, "Lactate as a fuel for mitochondrial respiration"   (though I only have the abstract)
And aside from that paper i've also heard

"lactate produced during exercise can be reused as fuel by the muscles
  by turning it into glucose".

But I'm interested in what chemical conversions are involved

Have you read about Cori's cycle? Not sure if it answers your question, but it is relevant to lactate transport and clearance.

@SatwikPasani You can post that as an answer and i'll add my elaboration as an end note.  And if it's wrong hopefully somebody will comment or post a better answer..   actually just needs a formula but should be easier to find now..

@SatwikPasani thanks.  My elaboration Looking at https://en.wikipedia.org/wiki/Cori_cycle shows https://en.wikipedia.org/wiki/Gluconeogenesis   it looks like Gluconeogenesis in the liver converts lactate to glucose. So the muscles wouldn't be fuelled by lactate(the article was unclear to suggest so). Muscles are fuelled by Glucose (not lactate) and they'd do aerobic and anaerobic metabolism..  I'm not expert though but that seems correct. But now I see more where lactate fits in.. The liver takes it in and converts it to glucose which can go back into the muscle.

Just mended the broken link.

I'm answering this as a comment because I think the question is too trivial to survive long and @SatwikPasani is not reading the question or the paper in taking about the Cori cycle. The answer is Lactate -> Pyruvate -> AcetylCoA. This can happen to the extent that the particular muscle in question has mitochondria and can obtain oxygen from the blood. This is not anaerobic metabolism, but the quote and the paper say nothing about it being anaerobic metabolism. The point of the paper is that most of the energy is from glycolysis but some can be obtained by lactate oxidation.

@David  Thanks, I didn't say it was anaerobic metabolism and I know the paper didn't say it was.   Regarding that formula you gave.. Lactate -> Pyruvate -> AcetylCoA   Does that all take place in the muscle, and what is the name for that process?  (If some takes place in the liver and some in the muscle, then it sounds  like the cori cycle though you suggest it isn't that)

@barlop — The reference you cite says it takes place in the muscle. There is no distinct name for the — as people didn't think it occured there was no reason to name it.

@David Is there a wikipedia page on it? I'd like to be able to google about it without just picking up that paper or the Cori cycle which you say isn't it. Also I only have the abstract of that paper not the full paper. I see the abstract says it produces lactate and excretes lactate.. I don't see the abstract saying it converts the lactate.. can you quote where it says that?  is it this " skeletal muscle has a large capacity for lactate oxidation" ?

@David so basically it looks lke cutting edge stuff that you get something like the Cori cycle in muscle.. Lactate dehydrogenase doing a reverse reaction of Lactate to Pyruvate,  in muscle itself.. whereas (that study aside), it's thought to be or was thought to be, particular to the liver

I'd read  of lactate being recycled and used as fuel for the muscles.. but that might've meant recycled by the liver.. and to glucose..eg as said lactate produced during exercise can be “recycled” into glucose and used as fuel by the muscles
Read more at http://running.competitor.com/2014/01/training/six-lies-you-were-taught-about-lactic-acid_29432/6#ZygL5Uh57rWIdzTV.99   But this one is in the muscle itself which is a different reaction.. I see.

@David and importantly, that formula you gave is not in the abstract.. can you give any screenshot of the paper with that formula?

It is not cutting edge, it is backwater. It is not like the Cori cycle in muscle. The Cori cycle is a confusing term for the flow of metabolites from muscle to liver to blood to muscle, without involving the mitochondrion or oxidation. I did not give you a formula, I gave you the names of intermediates in a conversion. A map may give you the route from Glasgow to London and London to Dover, but if you want to go from Manchester to York then you have to buy a map and work it out yourself. The map is the major metabolic pathways in a text or on Kegg. Finally, why do you care about this?

@David i'm curious.. I get curious sometimes.

OK, but it would help us help you if you told us the real reason. I deduce from the other lists you follow that you are computing professional, i.e. not a biological science student. Now your interest could be personal medical or home brewing, but it could also be that you are interested in using computer methods to model pathways. If it were the latter I would tell you you have to buy and study a biochemistry text to do it properly. If you have a specific goal one could give different advice. But if you think you can dabble without learning the language, I can't help.

@David I'm not doing a model, and your comments were very helpful in answering the question.. Thanks

I see you've already got an answer in the comments, so this is rather a collection (with more proper formulation) of comments. As is known, lactate is produced by muscles (generally) during exercise due to absence of oxygen. However, the lactate produced can be used again in following two ways:

Conversion of lactate to glucose in the liver via a process known as Cori's cycle. Basically, the lactate produced from the muscles is released into the bloodstream, through which it reaches liver. There, it is converted back to glucose and again released into the bloodstream, through which muscles can use it again as fuel. The basic cycle looks like:

Conversion of lactate to pyruvate is the one you are concerned about. However, this process does not have a special name, because this reaction can be catalyzed both in forward and reverse direction. In the absence of oxygen, an enzyme lactate dehydrogenase convertes pyruvate into lactate, consuming 2 H+ during the process. However, when the envrionment is rich in oxygen, or the concentration of lactate is high, the same enzyme converts lactate into pyruvate, producing 2 H+ in the process. The reaction can be shown as: $$\ce{CH_3COCOO^- + NADH + H^+ \leftrightharpoons CH_3CH(OH)COO^- + NAD^+}$$
Thus, when the concentration of lactate increases, the enzyme lactate dehydrogenase catalyzes the (above) reaction in the reverse direction. After this, the pyruvate produced can be used in the TCA cycle.

PS: there have been studies which now suggest that indeed lactate, not glucose, is the primary energy source of neurons. As per the lactate-shuttle hypothesis, the glial cells neighboruing neurons convert glucose into lactate, which is then used by the neurons. This fits with the observation that the extracellular fluid immediately surrounding the neurons is richer in lactate as compared with blood and cerebrospinal fluid, as shown in microdialysis studies. These studies suggest that glucose is not the actual primary energy source of neurons.
EDIT: As you see, the first reaction in both the cases is $\ce{lactate \rightarrow pyruvate}$. However, the main difference arises after this reaction. In muscle cells, this pyruvate is used in Krebs cycle, for which the first enzyme is pyruvate dehydrogenase converting pyruvate to acetyl-coA. However, in gluconeogenesis i.e. formation of new glucose molecule (a part of Cori's cycle), the first step is conversion of pyruvate to oxaloacetate, and is catalyzed by the enzyme pyruvate carboxylase. Thus, although the first step in both processes is the same, the end product is quite different.
References:

Lactic Acid - Wikipedia
Lactate Dehydrogenase - Wikipedia
Cori's Cycle - Wikipedia

Thanks. What's your view re what david says about that paper, which is that it's saying that the formula he gave "Lactate -> Pyruvate -> AcetylCoA."  is according to that paper, a reaction that happens in the muscle itself

according to that cori cycle image you've given, which i've seen verified elsewhere too.. it's as you say,  lactate to pyruvate to glucose..  in the liver. So why do you say "lactate to glucose" as one point, and "conversion of lactate to pyruvate" as a separate point..  Isn't lactate to pyruvate just half of that "pyruvate to glucose" reaction.. Also, why do you think that "lactate to pyruvate" is more relevant than "pyruvate to glucose"?

So there's 3 words here then..  Lactate->Glucose is Gluconeogenesis.    So what's the word for the in between reactions of A)Lactate to Pyruvate (the reverse of lactic acid fermentation)   and B)Pyruvate to glucose(the reverse of Glycolysis). (And yeah I understand your image I see the reverse reactions occur in the liver).

Secondly, David wrote in one comment  "the answer is Lactate -> Pyruvate -> AcetylCoA  "  and  another "The reference you cite says it takes place in the muscle. There is no distinct name for the — as people didn't think it occured there was no reason to name it. "    <-- So am I interpreting David's comment correctly there, that he's saying that that process with that formula occurs in the muscle?  And that it's according to that recent study and thus being a recent discovery it has no name.

(note, also I think David isn't talking about the Cori cycle, and the liver eg he said it occurs in the muscle, and he thought that one commenter was
"not reading the question or the paper in taking about the Cori cycle"  ).  I think the Cori cycle is relevant but it's also relevant that there may be this other scenario that David brings up of a process with that formula David gave, occurring purely in the muscle, not the liver.

So Lactate to Pyruvate (reverse lactic acid fermentation), occurs in the muscle.  Would Pyruvate to Glucose(reverse Glycolysis), also occur in the muscle?

Ah, looking at your edit,  so reverse Glycolysis doesn't occur in the muscle.  But reverse lactic acid fermentation does?

Note-  You wrote that David referred to Gluconeogenesis in comment.. David didn't refer to gluconeogenesis and he wasn't talking about the cori cycle.  I was the first and only person to mention Gluconeogenesis  in comments in the context of the cori cycle.  From what I understand.. Gluconeogenesis is  the right term in the case of the liver, but not for the muscle. Also on a related note and in correction to an earlier comment of mine, I have just found out that the pyruvate->glucose reaction in the liver is not reverse glycolysis 'cos the enzymes and pathway is different.

@barlop 1) no gluconeogenesis is mostly restricted to liver and kidney 2) yes "reverse" or "forward" lactic acid formation occurs in muscles, depending on presence of O2 and concentration of reacrants/products 3) seems I got confused with so many comments :P yup the pathway is quite different, but some enzymes involved here are also part of glycolysis. Now, lets delete these comments now ;)

Seems as if the downvoter did not even have a reason for their action this time :/

On a related note,  I have improved my question..(partly in the hope of dissuading any close voters) 'cos it looked a bit like the question was almost answering itself to an extent.  Your answer still applies and doesn't change as a result of that update...

Would you say that After Lactate is converted to Pyruvate, then that Pyruvate could be used for either aerobic metabolism or anaerobic metabolism? And that similarly, (with the other process, so), when Glucose is converted to Pyruvate, then that Pyruvate could be used to fuel either aerobic metabolism, or anaerobic metabolism?

@barlop yup, you're correct. Once pyruvate is formed, then it totally depends on environment where it would be used. As a matter of fact, glycolysis doesn't change; only the reactions following pyruvate production depend on O2 availability.

Thanks David And Homosapien..
HomoSapien has posted an answer which i've accepted.
I have included here a useful diagram showing the conversion of Lactate to Pyruvate to AcetylCoA, and a description how it relates to the question.
As has been mentioned there are two different processes not to be confused. There's the Cori Cycle aka Lactic Acid Cycle, where which involves the liver, blood and muscle. Liver converting  Lactate->Pyruvate->Glucose (that process in the liver is called Gluconeogenesis).    Glucose travels to the muscle..  Muscle performs Glucose->Pyruvate->Lactate  , lactate travels to the liver and in that cycle.  so there Lactate is very indirectly fuelling an anaerobic metabolism in the muscle.    Also note that(I understand from speaking to a biochemist), that when the Pyruvate is converted into Glucose it's technically not the reverse of Glycolysis since different enzymes are used and it's a different pathway.  I see that the conversion of pyruvate to lactate is a reverse of lactic acid fermentation, as the same enzyme, LDH, is used
The other process, which is quite interesting and less spoken about in popular articles,  is one which occurs entirely within the muscle. It's what David explained was Lactate -> Pyruvate -> AcetylCoA   There is no conversion to Glucose there.  And as Bryan has pointed out to me, The lactate metabolism they are talking about in that paper isn't really anything special - all of the reactions except lactate->pyruvate, are exactly the same reactions from standard glucose aerobic metabolism.  That  - Lactate->Pyruvate->Acetyl Coa is the one the paper is talking about. A  main point to make there is that the Lactate->Pyruvate conversion  is performed by the enzyme LDH which can work both ways, and in doing lactate->pyruvate, it is doing the reverse of "lactic acid fermentation". The other part, Pyruvate->AcetylCoA is what happens in aerobic metabolism.
I found a really good picture in that paper which helps explain things related to the answer of my question in regards to the process where muscle converts lactate to pyruvate as fuel for aerobic respiration... (I suppose it could potentially fuel anaerobic metabolism rather than aerobic)
So the picture shows the cell and the mitochondria within it.

The paper itself is titled "Lactate as a fuel for mitochondrial respiration"
We see in that picture the Glycogen which will be converted into Glucose, is converted into Pyruvate (Glycolysis), and some Pyruvate is converted into Lactate by LDH (Lactic Acid Fermentation).  But some Pyruvate can be fed into the Mitochondria which would fuel mitochondrial respiration.  The way that Lactate would fuel mitochrondrial respiration, would be lactate converted to Pyruvate by LDH, and that pyruvate would then go into the mitochondria to fuel aerobic respiration.
So when  this page for example, (to quote what I know to be an accurate part of that article), says "lactate produced during exercise can be 'recycled' into glucose and used as fuel by the muscles"  It's referring to the cori cycle, since it mentions lactate converting to glucose.  Whereas in contrast, that paper, is talking about a process within purely within the muscle. Also the cori cycle is about pyruvate being used for anaerobic metabolism(anaerobic metabolism occurs in the cytoplasm)  and the paper mentions about pyruvate being used for aerobic respiration(a reaction in the mitochondria).

I think that after Lactate is converted to Pyruvate, then that Pyruvate could be used for either aerobic metabolism or anaerobic m And that similarly, (with the other process, so),when Glucose is converted to Pyruvate, then that Pyruvate could be used to fuel either aerobic m, or anaerobic m.  (that is the case though the title of the paper and the concept of the cori cycle don't suggest that, as teh paper is distinguishing itself from the cori cycle by speaking of aerobic, and the cori cycle as a continual cycle is speaking only of anaerobic) I aim to update my answer to make that more clear.

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text:
confusion regarding degrees of flexion and a goniometer
I have read
https://en.wikipedia.org/wiki/Anatomical_terms_of_motion#Flexion_and_extension
"Flexion ... decreases the angle...Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts"
I am clear on the directions of flexion and extension

So all agree on direction, but if I look up degrees of flexion, for example

and videos showing usage of a goniometer to measure shoulder flexion, which echo that picture, so 180 degrees is the arm up, and 0 degrees is the arm down.
What I don't quite understand, is that flexion according to wikipedia, should decrease the angle.  Whereas looking at the degrees in that diagram, and in videos of usage of a goniometer, the more flexion you have, the higher the degree.
I can think of two possible resolutions
A) that wikipedia has missed out that in fact, for the case of the arm,  flexion increases the angle. Whereas for bending movement, it decreases it.
or
B) the planes that describe degree of flexion, are different to the ones shown on a goniometer, perhaps, one field uses a gynometer, the other uses a measure with the angles going the other direction
I'm guessing that it's "A" , that wikipedia is misleading and in the case of the "shoulder"(the arm movement considered shoulder flexion and extension), flexion doesn't decrease the angle, it increases it(though wikipedia doesn't say that). But i'd be interested if that can be confirmed.

For A), it depends on how you define the angle. If 180 is directed at the floor, then it is correct. The problem is that with the shoulder "increase" and "decrease" are ambiguous, and you have to define your planes of reference explicitly.

@kmm well there's no question what planes we are talking about. One plane is the frontal plane, the other plane is the plane made by the arm straight out in front going all the way up and all the way down at angles between 0 and 180. Sagittal plane. Both wikipedia and that picture and the goniometer are using the same planes.  One could say there is a difference depending on which you define as zero and which as 180,but  clearly a goniometer uses a standard convention of goniometers.. what standard convention is wikipedia using? What other texts measure shoulder flexion the way wikipedia does?

There are two criteria to differ between flexion and extension:
1) Decreasing or increasing the angle between the involved bones. By this criteria, it should be clear that flexion means bending of the elbows and knees and lateral bending of the spine (the neck and torso) toward the bent side.
2. The anterior/posterior direction of the movement. All anterior (ventral) movements in the neck or torso part of the spine, shoulder, elbow, wrist, fingers, hip, ankle and toes are called flexion and all posterior (dorsal) movements (except in the knee) are called extension.
You should not use the both criteria at the same time, because they can contradict each other.
There are some specifics:

In the wrist, you can have palmar flexion, dorsiflexion (extension), ulnar flexion (abduction) and radial flexion (adduction) (Teachmeanatomy).
In the ankle, you can have plantar flexion, dorsiflexion (extension), inversion (inward rotation, adduction) and eversion (outward rotation, abduction). (ScienceDirect).
In the shoulder and hip, raising a limb to the same side as the limb is, is abduction (lateral extension) and raising it to the opposite side is adduction.
Moving the thumb toward the palm (in the same plane as palm) is flexion (adduction) and moving it away from it is extension (abduction).

You can read about flexion and extension and other movements here: Types of Body Movements (BCcampus)

Flexion and extension are movements that take place within the
  sagittal plane and involve anterior or posterior movements of the body
  or limbs. For the vertebral column, flexion (anterior flexion) is an
  anterior (forward) bending of the neck or body, while extension
  involves a posterior-directed motion, such as straightening from a
  flexed position or bending backward. Lateral flexion is the bending of
  the neck or body toward the right or left side.
In the limbs, flexion decreases the angle between the bones (bending
  of the joint), while extension increases the angle and straightens the
  joint. For the upper limb, all anterior-going motions are flexion
  and all posterior-going motions are extension. These include
  anterior-posterior movements of the arm at the shoulder, the forearm
  at the elbow, the hand at the wrist, and the fingers at the
  metacarpophalangeal and interphalangeal joints. For the thumb,
  extension moves the thumb away from the palm of the hand, within the
  same plane as the palm, while flexion brings the thumb back against
  the index finger or into the palm. These motions take place at the
  first carpometacarpal joint. In the lower limb, bringing the thigh
  forward and upward is flexion at the hip joint, while any
  posterior-going motion of the thigh is extension. Note that
  extension of the thigh beyond the anatomical (standing) position is
  greatly limited by the ligaments that support the hip joint. Knee
  flexion is the bending of the knee to bring the foot toward the
  posterior thigh, and extension is the straightening of the knee.
  Flexion and extension movements are seen at the hinge, condyloid,
  saddle, and ball-and-socket joints of the limbs (see Figure 1).

Now, to answer the question about the goniometer.

Again, the confusion about interpretation of this goniometer arises from two different criteria about flexion. The one mentioned in the Wikipedia and other anatomical articles says that in flexion the angle between the involved bones decreases. When you raise your arm, this criteria does not aply because the angle between the bones (humerus/scapula) in the shoulder joint does not really change (unlike in the elbow, for example), so here the criteria that all anterior movements are considered flexion applies. When you have an arm straight down, there is no flexion, so it's considered zero degrees and when it's straight up, it's considered 180 degrees, so the angle is increasing, but this is not an angle between the arm and other bones or the body but between the starting and ending position of the arm.

you write "During raising the arm, the angle is closing"  <-- the angle between what and what? between arm and torso?  I suppose you could say the angle is closing/reducing whether the arm is near fully down or fully up, depending on whether 0 is at the top or at the bottom

@barlop, I have changed the last part about goniometer. In this case, you should not think about any "body" angles, but just about goniometer angles.

So in the case of criteria 1 (bending flexion), flexion decreases the angle, and in the case of criteria 2, (direction of movement flexion), flexion increases the angle?

@barlop By criteria 1, flexion decreases the angle between the actual bones (like in the elbow or knee). But when you raise your arm, in the shoulder joint, there is no real change in angle between the humerus and scapula, so this criteria simply does not work here, so the criteria 2 (any anterior movement is flexion) applies. Now, even if by criteria 2, the "theoretical" or goniometric angle increases when you raise your arm, you can't generalize this for other movements. For example, when you bend your neck forward, by criteria 2 this is flexion...continued...

Looking from the front, the angle between the spinal vertebra decreases, but looking from the back it increases. You just need to know, which criteria applies to a particular joint and be aware that the angle that decreases can be real, physical (by crieria 1) or arbitrary by criteria 2 (forward movement is flexion). By criteria 1, flexion always decresaes the angle between the bones, and by criteria 2, it depends on the joint.

When you say that in the case of the neck, that it depends which way you look at it  and that front the front flexion decreases the angle, is that because when you look from the front you are looking at the angle between the chin and the spine with 0 at the bottom, (that angle decreases towards 0 with flexion).  But when you say that when you look from the back it increases with flexion, is that because you are looking at the angle between the top of the head and the spine with 0 at the top?  (cntd)

(cntd) It doesn't seem to me to be a front/back distinction because you can view from the front that with flexion the angle between the top of the head and the spine increases with neck flexion

@barlop OK, what I said about the neck was probably not necessary. Forward bending of the neck is considered flexion and backward bending extension.

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text:
Why is it said that bacteria have no membrane-bound organelles, when they often have one or more flagella?
Why is it said that bacteria have no membrane-bound organelles, when they often have one or more flagella?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386205/  "Cilia and flagella .. are membrane-bounded organelles with unique membrane,"
Also, there is a biological motor (I don't know whether it's considered part of a flagellum or considered to be outside the flagellum, driving it?), but the motor surely has parts, e.g. a flagellum motor -like some mechanical motors, has a part, a "stator".  And surely these parts have membranes.
I understand there's one bacterium discovered, that does have a membrane-bound organelle mentioned here "There is at least one species of bacteria that has a clearly membrane-bound structure inside it called an acidocalcisome (I think that's how it's spelled). This organelle was.. discovered.. this is obviously a minor (albeit important for that bacterium) exception to the rule...that prokaryotes lack membrane-bound organelles."
Note- Alcamo's Fundamentals of Microbiology: Body Systems p124  this link from google books mentions other cases of membrane-bound organelles in bacteria including a discover as early as 1994. here
But putting aside the bacteria that have been discovered to contain membrane-bound organelles and going back to before those discoveries.. The texts that describe bacteria as having a flagellum, say that they don't have membrane-bound organelles. Why is this?
I suppose an answer might be that when people say that a bacterium contains no membrane-bound organelles, they mean except for any flagellum that it has.  They're referring to the main body of the bacterium, like one might refer to the torso of a human.

Let us continue this discussion in chat.

Explanation of my edits to the question. 1. Some words in biology are of Latin origin and if they end in -um in the singular generally form their plural with -a. Hence bacterium / bacteria, flagellum / flagella. 2. When a noun such as membrane is being used as part of a compound adjective such as 'membrane-bound' (describing organelle) it is hyphenated to avoid initial confusion when reading. This may appear pedantic, but clear communication of ideas is important in science, and if nobody points this out, people remain ignorant.

This question is unclear. Your question is underpinned by a question like"what are the differences between bacterial and eukaryotic flagella?". The literal question being asked "The texts that describe bacteria as having a flagellum, say that they don't have membrane-bound organelles. Why is this?" is subjective since each text may have different reasons and qualifiers.

The question boils down to 'what is an organelle'. I remember a heated yet interesting discussion in the past in the chat room about this topic. I think the lead was this question. But it's closed. Perhaps OP ('you') can edit the question to make it more clear. I'll vote to close but I'm happy to re-vote to re-open it again once edited.

@AliceD  the question you link to shows no research whatsoever. My question is far more specific and researched and is asking about a very specific contradiction.  It is possible to write a general question what is an organelle and to research it well, but there would be other questions within that. My question is very specific and asks about a specific contradiction

@James The question of "what are the differences between bacterial and eukaryotic flagella" may be a big question that doesn't answer specifically the question here.. Though it's possible that an answer to such a question might cover my the question of membranes in relation to the flagella - outside it and inside it,   it's possible that it might not cover that detail.  BTW can you offer any insight into my comment question on  Gerardo's answer?

First, this is of some relevance..
https://www.karger.com/Book/Home/258738  says "The traditional view of biology divides living organisms into two major groups, the eukaryotes and the prokaryotes, the former having membrane-bound organelles, the latter lacking them. However, recent research has revealed that this view is blatantly in error. "  (so that is a link confirming one of the things the question said).
Though, a knowledgeable biologist I spoke to said while indeed, that above mentioned distinction between prokaryotes and eukaryotes, is mistaken, there are still distinctions, a genetic distinction(nowadays the distinction would be genetic), and also observable distinction that prokaryotes don't have a nucleus and eukaryotes do. So the terms prokaryotes and eukaryotes are still relevant and not in error.
It may be that texts that say "membrane bound organelles" may mean "membrane bound organelles within the cytoplasm" But it seems even so, as I mention below, a bacteria's flagellum doesn't have a membrane.
Now, to elaborate in answer to the question itself -
I have spoken to a biophysicist familiar with microbiology, that seems pretty knowledgeable.. and he gave an answer that went straight to the point.
He said that the bacterial flagellum has no membrane, and none of its intricate internal components have any membranes.
As to what holds them together(given that it's not a membrane) - all the flagella stuff is protein, held together with protein-protein interactions, the same stuff that holds all protein complexes together, such as salt bridges, hydrophobic effect, etc.
Also the question mentions this

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386205/ "Cilia and
  flagella .. are membrane-bounded organelles with unique membrane,"

It appears the above statement is wrong or misleading, see
https://www.ncbi.nlm.nih.gov/pubmed/7378551
"The term flagella is ambiguous. It refers to bacterial structures composed of flagellin protein and to eukaryotic structures composed of microtubule proteins and ATPase (tubulin and dynein). The fact that cilia are nearly identical to eukaryotic flagella and have nothing in common with prokaryotic flagella is not apparent from the terminology. It is proposed that the 30-year old suggestion of Smagina and reiterated by Kuznicki and others, be adopted: that cilia and eukaryotic flagella be called "undulipodia." The term flagella ought to be restricted to prokaryotic organelles, bacterial flagella and spirochaete axial filaments: solid structures composed of flagellin which protrude through the plasma membrane and lack intrinsic motility throughout their length. Undulipodia are defined as intrinsically motile intracellular structures showing a 9-fold symmetry in the pattern of arrangement of 24 nm diameter microtubules. They are limited to eukaryotes, members of the protoctist, animal and plant kingdoms."
The knowledgable biologist I spoke to then said that the distinction between eukaryotes and prokaryotes nowadays is done mainly by genetics. Nevertheless, (as mentioned), an observable distinction between eukaryotes and prokaryotes is that eukaryotes have a nucelus and prokaryotes do not have a nucleus. Furthermore, if any prokaryote was ever discovered to have a nucelus, then it'd require a reorganization of phylogenetic trees. Also, while phylogenetic trees use the term eukaryote, they don't tend to use the term prokaryote, though the term prokaryote is still relevant, and there is an organization called the  ICSP(International Committee on Systematics of Prokaryotes), that deal with the naming of groups of prokaryotes.
Also, while it's not entirely clear to me if there was at any time a shift from observable characteristics, to genetic characteristics, in determining the difference between eukaryotes and prokaryotes,  this page mentions something about the origin of the terms prokaryote and eukaryote. And I understand from the knowledgable biologist I spoke to that nowadays the distinction is genetic or mainly genetic. http://www.madsci.org/posts/archives/2000-04/956011333.Gb.r.html
added
I have spoken to another microbiologist.  He thought that the term prokaryotes is not useful, it doesn't have an evolutionary basis.. And at least the term eukaryotes, cells with a nucleus, the cells may be quite related.. Whereas prokaryotes  - cells without a nucleus - is defining something partly by what it's not, and it doesn't group organisms phylogenetically/evolutionarily.   Prokaryote refers to bacteria and archaea, both generally unicellular. But archaea are evolutionarily and biochemically more similar to us(eukaryotes) than they are to bacteria. There's no valid reason to lump them with bacteria.  Not evolutionarily or biologically.   The most recent development is that eukaryotes likely evolved from archaea.  Some newer models show the eukarya lineage as rooted in the archaean lineage.  All of them show that they're more close than either is to bacteria though That's universally agreed Phylogenetically and also cytologically.  The three domains of life are Bacteria, archaea, and eukarya. Eukaryotes still make sense as a grouping as they are a group of organisms more similar to themselves than to bacteria or archaea.  And indeed they are identified genetically.

There are some interesting topics here for discussion, particularly in the discussion with the microbiologist on how prokaryotes is often an unhelpful term for describing evolutionary distance.  The key point is ...the bacterial flagellum has no membrane, and none of its intricate internal components have any membranes. This is already in @GerardoFurtado's succinct answer.

@James I notice Gerardo wrote "It's clear that prokaryotic flagellum is just a protein-made structure that crosses the membrane and grows outside it, "  So what is a membrane made of then that distinguishes it from just protein, is a membrane..protein+fatty acid?   Or is the definition more abstract like is it something that surrounds something, so e.g. in a sense the body has a membrane that is skin?


text:
Why does dissociation of carbonic acid cause a decrease in pH?
When a molecule of carbonic acid (H2CO3) dissociates, the two products are a bicarbonate ion (HCO3-) and a hydrogen ion/proton (H+). Because of the addition of a hydrogen ion, this process causes a decrease in the pH of the blood, and if someone breathes too slowly and doesn't quickly remove CO2 from their body, respiratory acidosis will take place.
However, why is it the case that the addition of this hydrogen ion lowers pH? While this might sound like a stupid question, it's also the case that the dissociation of carbonic acid produces a bicarbonate ion, which is a weak base. Therefore, the dissociation produces both an acid and a base in a 1:1 ratio. Therefore, the concentration of hydrogen ions relative to bicarbonate ions doesn't actually change. Given this fact, wouldn't there be no change in pH at all?
I read a paper on carbon dioxide transport which addressed some of my other questions but didn't touch on this precise point.

I've voted to close (migrate to chemistry). They may close it as well if they have a similar homework policy

@DeNovo This question doesn't concern any homework I have (my class only briefly mentioned the buffering system). Everything I ask (at least to this point) on the Bio Stackexchange concerns my personal understanding of these topics.

@Korvexius sorry, I know it's confusing, but here we consider "homework" to be the work, in the general sense, that you should do before asking a question. It's not specific to school assignments.

Any acid that releases a proton when it dissociates in water will also produce a conjugate base. We can conceptualize this as $\ce{HA <=> H+ + A-} $. In this particular example, $\ce{HCO3-}$ is $\ce{A-}$.  The strength of the acid is determined by the extent to which the acid, $\ce{HA}$, dissociates. This can be expressed using the equilibrium constant for this reaction, which has a particular name, $\ce{K_a = \frac{[H^+][A^-]}{[HA]}}$, (where $\ce{[X]}$ is the concentration of $\ce{X}$ at equilibrium). The larger $\ce{K_a}$ is, the further the reaction moves to the right (or, as it is often expressed, the smaller the $\ce{pK_a}$, which is $\mathrm{-log_{10}}$ $\ce{K_a}$).
Here, the addition of any $\ce{HA}$ will produce $\ce{H^+}$ and $\ce{A^-}$ in an aqueous solution (the blood), and decrease the $\ce{pH}$. $\ce{A^-}$ is only a base insomuch as it can form $\ce{HA}$ by combining with $\ce{H^+}$. This can occur if you add (or, as occurs in the kidney, reabsorb) $\ce{A^-}$ with some counter ion other than a proton. Then you can drive the equilibrium to to the left, towards $\ce{HA}$, decreasing $\ce{[H^+]}$. Otherwise, $\ce{A^-}$ derived from $\ce{HA}$ will not drive the equilibrium one way or the other. $\ce{H^+}$ will still dissociate as determined by the $\ce{K_a}$.

Bicarbonate will make the mudium basic ONLY WHEN it is bonded with some cathium that came from a strong base.
E.g. NaHCO3 is a basic salt because NaOH is a stronger base than H2CO3 is an acid. That way Na+ will stay completely dissociated while HCO3- and water will become H2CO3 and OH-.
H2CO3 is considered an acid because it ionizes in H+ and HCO3-. Some of the HCO3- will bond with water and form OH- and H2CO3 again. This is an equilibrium. But If we have only one HCO3- that didn't yet bonded to water and formed H2CO3 again, we will have more H+ in the medium, and it will be acid. In fact, there is a constant called Ka that measures how much HCO3- and H2CO3 are in a solution in a given time.


text:
Molds associated with Aflatoxin?
I've been reading how some molds may be carcinogenic. In particular, molds associated with the fungus metabolite, Aflatoxin.
Are the types of mold that produce this toxin, present in buildings/showers/domestic environments, or do they only grow on food-stuffs?

I've made a few linguistic changes. Also fungus is singular, fungi plural. Correct this in answer too.

Strictly speaking the common bread mould Rhizopus sp. does not produce aflatoxin.
The fungus Aspergillus flavus which belongs to the class Ascomycetes secretes aflatoxin. It attacks cereal grains , legumes, tree nuts. The fungi are green in colour and 'mould' like in appearance.
The fungus attacks the food stuffs and storage grains. So under favourable conditions it may grow in your store room if it finds food for its growth. Also Aspergillus can grow at temperatures as high as 48°C and even at low temperatures like 5-8°C.
Edit: On being asked for sources I include some which strongly support my claim
1. For suitable conditions of growth of the fungi visit https://en.m.wikipedia.org/wiki/Aspergillus_flavus and read under the Environment heading.
2. Visit https://bioweb.uwlax.edu/bio203/s2013/ernst_ale2/habitat.htm and read from " Aspergillus flavus is omnipresent " upto " Aspergillus may also grow on or inside walls in homes, especially if the house is damp or has been damaged by flooding. "
3.https://www.moldbacteria.com/mold-types.html this site provides a list of different fungi found in our homes. Here you can find Aspergillus flavus to grow in flower pot soil. Moreover other species of Aspergillus are found in kitchens and bathrooms.

So it is impossible for it to grow on walls?

I presume it cannot grow directly on walls unless it gets nutrition and moisture for its growth. Now if there is a damp wall the fundi may find some organic matter and may grow on it.

Sorry in the third line it is fungi

Including reliable citations within your answer to back-up your claims, is essential. Please consider adding the sources of the information you used, into your answer, as soon as you're able to. Thank you :)

For suitable conditions for the growth of the fungi see https://en.m.wikipedia.org/wiki/Aspergillus_flavus and read under the Environment heading, next visit https://bioweb.uwlax.edu/bio203/s2013/ernst_ale2/habitat.htm and read from " Aspergillus flavus is omnipresent.....  " upto "Aspergillus may also grow on or inside walls in homes, especially if the house is damp or has been
                                                   damaged by flooding. "

I have included some sources, check the answer for them.

This confuses me, showers are "damp". Does it or does it not grow in showers? Assuming there is no food in the bathroom.

also the reference is a student project. Some of its references are "mold removing sites" which I dont consider unbiased. I cant find any info on where and how it grows from the references in this student project. Let me know if you find something.

I will try to include more sources as soon as I find them. Moreover you can  think about this simple logic, the metal mouthpiece if your shower can hold water for a far less time than the cracks in walls or old air conditioners can , so naturally the fungi has more chances to grow in cracks of walls than in your shower.

https://www.moldbacteria.com/mold-types.html this site provides a list of different fungi found in your home. Here you can find Aspergillus flavus to grow in flower pot soil. Moreover other species of Aspergillus are found in kitchens and bathrooms.

Thats still not a research reference. Thanks alot for looking tho! This material has been to some help, and I can keep look from these places myself aswell. Its hard to dig for stuff like this without any academic traning in biology.
Let me know if you find somthing more rigorous btw!!


text:
What is the Gaidukov Phenomenon in algae?
Apparently the Gaidukov Phenomenon occurs in algae so as to enable the algae to absorb the maximum light for photosynthesis. How does this happen?

This may be helpful. http://www.pnas.org/content/20/5/251.full.pdf

@Mesentery Thanks a lot!! Obviously this was of great help!!

You should provide a better background, and briefly explain the Gaidukov Phenomenon.


text:
Why would a human female have a sexual display despite male biased operational sex ratio?
why would a human female have a sexual display despite male-biased operational sex ratio?
In human society there is a male-biased sex ratio, due to female child rearing, which results from anisogamy. Human females sometimes expend great amounts of energy and resources performing display acts and doing things to attempt to improve their apparent quality to males. Human males tend to be eager, despite a certain level of socially imposed monogamy, and many males will mate with a low quality female. Why do human women do sexual display behaviors, when there are so many eager males to choose from?

Your question is not clear. Can you please add some more details to clarify it?

@WYSIWYG did my edits clarify enough/at all?

@WYSIWYG What is unclear about this question? Seems perfectly clear to me. Although I think more recent research would question the basic premise of human operational sex ratios being purely male biased, but I think we've agreed in meta not to oppose questions based on incorrect premises (and likely a good answer would address that possibility).

Okay.. I understood the question but I guess what you are talking about is a recent phenomenon and is not likely to be shaped primarily by evolution.

Because it is not just about mating and sex. Evolutionary it is also about care and bringing the offspring through life together.

Sexual arms race.
There is a fine and internally consistent theory that this strategy by females evolved to oppose the strategy of infanticide by males.  Males of many species including primates and possibly humans can increase their own genetic fitness by killing infants that are not their own.  This frees up attention and physical resources of the female to instead have the baby of the infanticidal male.  Lions are famous for this.  But this is in opposition to the genetic fitness interest of the female, who just invested a bunch of efforts gestating and rearing an infant who was then killed.
My favorite writer on this is Sarah Hrdy.  From the Wikipedia article on this\

This is where the idea of sexual counter-strategies comes into play.
  Hrdy theorized that by mating with as many males as possible,
  particularly males who are not part of the colony, mothers are able to
  successfully protect their young, as males were unlikely to kill an
  infant if there was the slightest chance that it might be their own.

This explains why women have the sexual displays referred to in the OP.  Other aspects of female human biology match.  Humans keep big breasts so they always look like they are lactating (compared to other animals) - to keep males guessing.  There is no external sign to indicate when a human is ovulating.  Females of other species are receptive and mate when they are ovulating - humans can mate any time.
A strategy of keep the guys guessing.  If one time he had sex with a given female, probably he shouldn't kill the kid.  Maybe it is his?
An interesting (& extremely arguable!) corollary to this is the premise that human culture in its entirety is the male countermeasure to this prehistoric female defense against infanticide: that male dominated culture is a method to ensure paternity.


text:
What is protein folding and how is it relevant to disease?
I am trying to understand what is protein folding and how it could help cure some diseases.
When reading articles about it, it looks like the goal is to find perfect folds for proteins because some diseases are due to proteins that don't fold correctly. I don't understand why do we need to find them in the first place?  Don't correctly folded proteins already exist in the body of people who aren't affected by those diseases? Why do we need to manually find those structures instead of simply "reading" the structure of the correctly folded proteins in the body of non affected people?
In the end, is the goal to find the best structure or to find the folding proecess ? Or both ?
Thank you!

Please try to make the title of your questions as specific as you can. "Questions about" should never be included. They are all questions, so this is superfluous. Your question is about protein folding, so say what it is you want to know about. I have done this for you. If it is not your question then modify it.

@David Can't understand what you meant by "If it is not your question then modify it" ?

I mean, if the title does not reflect what you want to ask, then change it so that it is. I have interpreted it from the content of your question, but it is your question so you should improve the title if you are not happy with it.

@David Oh ok ! Thank you for the edit ! Yes I should pay more attention to that.

Protein folding is a complex thing. There are huge computer algorithms and huge mainframes which are trying to predict the final 3D structure of a protein.
Knowing the tertiary and the quaternary structure of a protein, allows us to understand why diseases happen. In many cases a mutation of the gene provokes an aberrant protein folding. When the protein is misfolded, it is not able to do its function. This particular condition is called "Proteopathy".
http://link.springer.com/article/10.1385%2FMN%3A21%3A1-2%3A083
If you know the structure of a protein, you are able to design or improve drugs which can directly influence the protein structure and/or function, for example antibody therapies against cancer (Cetuximab-->against EGFR, in colorectal cancer; it is a drug which was very much improved when computers prediction/simulations are used).
https://en.wikipedia.org/wiki/Cetuximab
It is hard to find out a protein's structure - for some proteins it can require years!
So you first go from the sequence of the healthy people, then you sequence their genomes, and you use this as reference for the people with certain diseases. You might find eventually some mutation is in certain loci in the genomes of people with a certain disease. Then you can study the protein structures, so you can design some new drugs which might tackle this protein. If the protein is misfolded, like the tau protein in the neurodegenerative diseases, then is good to study the structure of this misfolded protein so you can design some drugs for these protein too.
So in the end the structure is extremely important, but often times you have to study many stages of the protein folding process to understand the possible final structure that one protein might have in the body and/or in a certain disease.
I hope this can help!

I think you mean neurodegenerative not neurovegetative.

Cetuximab and nearly all other monoclonal antibodies on the market today were designed the old-fashioned way - by immunizing animals (mice in this case), screening their naturally-produced antibodies, and either humanizing it for direct use (older mAbs, like this one) or having it undergo affinity maturation via several different formats, including applying knowledge of drug/target structures (only the most recent mAbs in development). Unless you can accurately describe this in your answer, I'd just take that whole section out, because it implies the drug was designed, when in fact it was not.

Thank you for your comment, please check this link https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2803018/

An article, Protein Misfolding and Degenerative Diseases, covers this question, and although it focuses on a single type of disease, this is of great importance.
To summarize, there is the potential for misfolding in proteins because of the small differences in energy between different alternative folded states, and because during synthesis some proteins expose to the solvent regions that are hidden in the folded protein and if exposed would make the protein unstable. (These latter require other proteins to help them fold.)  Thus, it is not difficult to envisage circumstances in which misfolding occurs, with concommitant loss of function and harmful consequences. The particular current interest in this is because certain neurodegenerative diseases involve misfolding of proteins. Indeed, in Alzheimers and other diseases the amyloid protein folds into an alternative structure to normal.
Although it may be a little advanced, the 10th November 2016 issue of Nature has a series of reviews on this topic, which are free to view. One by Riek and Elsberg deals particularly with the alternative structure.


text:
Kinetics of allosteric regulation
I have found a diagram similar to the following one in my biology textbook. The diagram describes allosteric regulation.

However, I do not quite understand why the maximum reaction rate $V_{max}$ is still reached, even though I thought this is only possible for a competitive inhibition.
I think that the diagram should look something like this where the maximum reaction rate is not reached.

Is there simply an error in the diagram or have I misunderstood something here?

My textbook states clearly that $V_{max}$ remains the same in a case of competitive inhibition but is is lower in case of non-competitive inhibition under which, according to my textbook, you can count allosteric inhibition. Also I see diagrams like this everywhere where $V_{max}$ is lower for a non-competitive inhibition

Your text-book is incorrect in saying that allosteric inhibition is not competitive. I do not know what your text book actually says (and do not care). The curves usually show the negative effector not reaching the maximum rate because a very high concentration would be needed to achieve this (and in any case the curves only reach this at infinite concentration). I have added my own answer to the question I cited (as I had been meaning to do for a while because of the confusion these terms cause). Look at my diagram carefully and you will see why allosteric negative effectors are competitive.

To clarify. The diagram in your textbook is probably correct, if idealized, but I cannot be sure as I presume you have redrawn in it from the spelling mistake "inhibtor".

Ok, so after watching this video on Khan Academy and reading your answer to the other question, I got it clear that allosteric inhibition can be competitive. So in the diagram in my textbook I have a competitive allosteric inhibition, right?

Yes, I have redrawn it, but took caution to have it be exactly the same. I apparently messed up the spelling, though, sorry.

Easy to make typos in figures. As for your question, I would never use the "term competitive allosteric inhibition" for the reasons I give in my answer. Don't learn terms by rote to parrot back to someone. Think about what is happening and describe it clearly.

Yeah, you are right, but in general I'm right with saying that allosteric inhibition can be a form of non-competitive inhibition but it does not have to be and could also be a form of competitive inhibition, right?

So in conclusion, allosteric inhibition can be both competitive and non-competitive. Right?

Wrong. As far as the other answers to the question go, and in terms of the kinetics and my diagram, I cannot see how there could be a negative allosteric effector that acted in a non-competitive manner.


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Do Alicyclobacilli produce carbon dioxide?
Do Alicyclobacilli, especially guaiacol producing ones, still produce carbon dioxide? Alicyclobacillus spp. are well known spoilage organisms in the fruit juice industry. Apparently there is no "blowing up" of the packaging (often caused by carbon dioxide production) which makes it difficult to visibly detect a potential contamination. Thus the question, do Alicyclobacilli produce carbon dioxide at all?

Alicyclobacilli are strictly aerobic and thus take up oxygen and secrete carbon dioxide, as opposed to the (facultative) anaerobic yeasts and bacilli that usually cause spoilage. So yes, alicyclobacilli produce CO2. But why doesn't the packaging swell? Compare the number of gas molecules in the simplest reactions for aerobic and anaerobic metabolism:
Aerobic metabolism: $C_6H_{12}O_6 + \underline{6 O_2} \Rightarrow \underline{6 CO_2} + 6 H_2O + 38 ATP$
Anaerobic metabolism: $C_6H_{12}O_6 \Rightarrow 2 Ethanol + \underline{2 CO_2} + 2 ATP$
Aerobes take in as much gas molecules as they excrete, while anaerobes (the ones producing ethanol at least) only make gas.


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High altitude rail travel
This question is primarily about human performance. I do know about hypoxia, hence this question.
I'm busy designing a fictional region, currently in the 1930's. I have a railway line that climbs to 15,000ft (4670m) in order to traverse a mountain range. The line was build in the 1900's, with the climb being gradual at 1:100 gradient. The town on the Eastern side is at around 5,000ft. the town in the west is at about 7,000 ft. Distance by rail is about 800km, (about 10 to 14 hour journey) with about 20 to 40km spent at 15,000ft. Using real-world data,
I only have a basic understanding of the human body, and would like to ask the following questions:
1.) With 1900's to 1930's attitudes, would it be "safe" / "wise" to send passenger trains over that pass?
2.) How would this altitude affect the drivers / firemen on the steam-engine's footplate?
3.) From a biological point of view, how do I make this journey more comfortable?
4.) Any other point which I might have missed.

The train connection (from mainland China) to Tibet is very similar to what you are describing - with exception for the time it was built. Looking into the details of that will probably give you a lot of useful information: https://en.wikipedia.org/wiki/Qinghai-Tibet_railway

For something with similar elevation changes, see the Pike's Peak Cog Railway https://www.cograilway.com/  Probablly millions of tourists rode it without any major ill effects.

People have used other modes of transport in that time without any significant health problem. Why do you think a train journey would be any different?

@WYSIWYG The train journey climbs to altitudes above 12,000ft (4,000m aprx), for several hours. In modern aviation law, oxygen is mandatory above that altitude if unpressurized. Some people (the elderly, smokers) could have reduced lung function. The high altitude may cause them illness or worse. I estimate that about 50% (if not more) of the people traveling will be affected by the altitude in some way or another.

@WYSIWYG (... continuation) I'm mainly worried about the fireman who needs to exert physical effort at this altitude. It would be bad for business if the firemen drop dead during the journey...


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What does "PDPN+ cells" means?
Are they podoplanin positive cells (cells that tested positive for podoplanin)?
"...though it has been shown that podoplanin (PDPN+) cells analogous to mouse FRCs are found in human secondary lymphoid organs..." (https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2005046)
"Although rare, the few SFTPB+ observed in HLOs resemble AECII cells seen in the adult human lung, and PDPN+ cells resembled the elongated AECI cells in the human lung" "Few PDPN+ cells also showed elongated, squamous morphology seen in the adult lung." (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370217/).
Thank you.

Can you please provide some context (for e.g. excerpt from the article/book which uses this term, with proper link)?

Yes, sure: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370217/

James. We generally appreciate if a question is self sufficient. It is good that you provided a link but it would be even better if you could paste the exact sentence/paragraph that uses the term that you want to know. Use quotes or mark with a ">" in the beginning to indicate text that you have copied and pasted.

In this context, that nomenclature means "cells which express PDPN"


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Surviving only on another's exhales?
While reading this - Surviving under water in air bubble - this question came to me:
How long can an adult person survive on breathing in only exhales of another adult person? Can this be even calculated by not relying on rough approximations or there are too many variables?
In order CPR (mouth to mouth breathing part) to be effective, logic says that exhaled "air" is not poisonous to bring a fatal blow, but for how long?

Ok, I'll bite. Now, I'm going to assume that in this scenario, Alice and Bob are stuck underwater. Alice has a SCUBA tank filled with compressed air (not pure O2) and though she won't share it with Bob, she magnanimously agrees to share her exhaled breaths with him.
Exhaled air contains 13.6–16.0% oxygen and 4.0–5.3% carbon dioxide in addition to other gasses which we'll ignore here. The real question here is: can you survive on that?

13.6–16.0% oxygen is 66%-80% of the amount of oxygen in normal air (which is ~20.1% O2). If we assume that the air pressure of the exhalation is the same as the air pressure at sea level, then the amount of oxygen available to Bob is roughly equivalent to being at an altitude of 2000 - 3500 meters above sea level, which is certainly survivable.
The CO2 is likely to be a bigger problem. CO2 is toxic and, in sufficient quantities, can case asphyxiation even in the presence of sufficient O2. Amounts above 1% can cause drowsiness, headaches, and mild narcosis while higher levels lead to dizziness, confusion, and unconsciousness.
It looks like you need amounts around 7%-10% for death, so Bob will probably survive in the short term, he definitely won't be happy and he won't be doing much. According to wikipedia's page on Hypercapnia, the time one can expect to perform useful activity varies greatly based on the exact amount of CO2:

1 week at 4%,
8 hours at 4.5%,
4 hours at 5%, and
1 hour at 5.5%

If Alice and Bob are just relaxing and waiting for rescue, it's likely that the CO2 in her exhalations will be on the low end of that range and Bob will likely be able to survive (albeit in great distress) for a significant period. If they were exerting themselves, however, Bob wouldn't do well at all.

so is it safe to assume that ~ after 30min Bob would feel really bad due to CO2 levels and ~ after 3+ hours he would have huge difficulties to survive coz he could forget how to breathe?

I think that would be a reasonable assumption, though keep in mind that I'm making a lot of assumptions here and you should not use this advice to make any medical (or SCUBA diving) decisions. Also, it's not that Bob would forget how to breathe, though, just that as CO2 toxicity gets worse he will become more and more impaired

Alice could probably keep Bob alive for longer by increasing her dead space ventilation.


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Which cells are prefered by the HIV virus to establish an infection?
We always read that HIV infects CD4 cells, macrophages, and dendritic cells. However, is it a common event for HIV to infect non-immune cells within a host? If not, why?
And also if not, why are immune cells the main target of HIV? I could not find information on Google or Google Scholar on this topic. I imagine it doesn't have to do solely with the presence of the expression of co-receptors such as CD4, CCR5, CXCR-4, DC-SIGN etc that attract the virus only to immune cells.
I would like a more complete explanation than this obvious one. For instance, what advantages are provided for the virus to prefer infecting immune cells over non-immune cells?

I guess that by infecting immune cells the virus is further improving its chances of survival.

I find it fascinating that HIV spreads during the latency period (aprox. 8-10 years) within lymph nodes, killing more than 1 billion immune cells per day. It is ironic that one would expect that lymph nodes are one of the most secure places within the body as they are patrolled by immune cells. However, it turns out that HIV is safe there. I find this fascinating. It's like the Trojan Horse story, except at a microscopic level and in real life.


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Storage of bacteria
Why are strains of bacteria stored when they are inactive (frozen)? What is the problem with storing growing cultures for long periods?

Growing cultures require human care, among other things. Frozen ones require only electricity.

Aside from the comment that frozen cells require less manual maintenance and expense (which is a big plus), active cultures can rearrange/recombine plasmids causing mutations and deletions (especially in the case of toxic inserts). For example, see this article:
Peijnenburg AA, Bron S, Venema G. 1987. Structural plasmid instability in recombination- and repair-deficient strains of Bacillus subtilis. Plasmid 17(2):167-170.

And this is very important. To make experiments comparable and reproducible, you want to be sure you are using the same strain.

Although a bacterial culture on a petri dish, slope or stab culture is in a closed environment and may start healthy, over time, the number of viable cells will decrease to zero as nutrients are being used up. The goal of preserving the cultures in a frozen state is to slow their metabolism and, in relation to that, their death rate so that when the culture is revisited, some of the cells are still viable and available for culturing. The reasons the cells die can be numerous, but in every instance are based on the inherent chemistry of the cells and their environment.  If the deleterious chemical reactions can be slowed or halted, then the overall culture will remain viable for a longer period of time.
As a general rule, the viable storage period of bacteria increases as the storage temperature decreases. Once the temperature is below the freezing point, however, cryoprotectants are essential to reduce cell damage caused by the freezing process.
In addition to the other comments and answers, cryopreservation tubes tend to be much smaller and take up far less space than an agar plate or stab cultures.
Here a table that shows approximate storage spans at different conditions:

Sources:
OPS DIagnostics
Thermo Fisher - Storing Bacterial Samples for Optimal Viability


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Very high 260/230 absorbance ratio of an RNA sample
After my most recent RNA extraction, the RNA samples had very high 260/230 absorbance ratios, (ranging from 5 to 25).
I've never gotten numbers like this and I know the ratio is supposed to be ~2 in general.
What could be the reason for such a high 260/230 absorbance?

http://www.scientistsolutions.com/t11627-high+260_230+ratio+for+dna.html suggests that high ratios are caused by high salt concentrations in your sample?

Thanks for the link, but in my experience salt contamination would cause a low 260/230 ratio, as salts absorb at 230 nm.

Gergana is right about the effects of the Guanidine isothiocyanate, but not the details there of.  Guanidine isothiocyanate absorbs strongly at 260 and NOT 230 (guanidine hcl is the one that absorbs strongly at 230).  As such if your RNA is highly contaminated with guanidine isothiocyanate, which is used in at least one buffer in just about every RNA prep kit, your 260/230 is going to be much larger then 2 (also the "concentration" will be artificially high.  So if you are getting a 260/230 of 25 and have a "concentration" of "1000 ng/µL" you may actually have less then 200 ng/µL of RNA and a ton of Guanidine isothiocyanate throwing everything off.)

The 260/230 ratio gives you idea about the contaminants in your sample. Guanidine isothiocyanate, which is usually used for RNA isolation, absorbs at 230nm, so that might be what you see. But another explanation might be that your sample is very dilute (how much RNA did you get?), so that your A260 is also very low. Then it would be difficult to accurately measure A230, which will result in overestimated 260/230 ratios.

The RNA concentration was not lower than usual (1000 ng/µL), but in the future I'll keep this possibility in mind.


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How can I view modENCODE data faster?
I am trying to view several data tracks in the modENCODE GBrowse genomic browser. However, the site is so slow, it is practically unworkable. Is there a faster way to explore the data?

I have no experience with this, but apparently you can download it: http://www.modencode.org/publications/faq/#How_do_I_access_modENCODE_data.3F

Download the data and parse locally..

Options:

You can always download the data (as @WYSIWYG has suggested in the comment).
Transfer the data to Galaxy
Convert and export the selection of your choice.

Source: http://modencode.oicr.on.ca/fgb2/gbrowse/fly/


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What is dental health like in animals?
Do animals suffer from tooth decay, such as cavities? Is it to the same extent as in humans, or do animal teeth decay more or less? If teeth decay in animals as well, are there natural strategies animals use to heal it? And, lastly, how do animals take care of their teeth?

If this is in comparison to humans, the animals are more or less free from the two common dental diseases by which teeth are lost in humans. These are dental caries (dental decay)  and periodontal disease (gum disease).
Common to both the diseases is the biofilm which forms on the teeth known as dental plaque.
If the plaque is colonised by acidogenic (acid producing) micro organisms cavities are produced in the presence of refined carbohydrates.
The gum disease is produced by bacterial toxins from the plaque causing inflammation of the surrounding gum resulting in loss of supporting structures of the tooth including bone resulting in loosening and loss of teeth.
In animals in the wild, plaque accumulation is effectively controlled by the coarse unprocessed diet which has a very good scrubbing effect. Besides wild animals are not exposed to refined carbohydrates like sugars.
Hence wild animals do not have these two diseases. However domesticated animals on human diet are prone to similar diseases.
In wild animals severe attrition (wear) and fracture of teeth are more common.
Wild animals will not survive long without adequate number of functional teeth.

Human tooth decay is mostly from eating foods high in sugar.  So animals don't generally get cavities.  (Except for humans' pets.)  But animals can have other tooth problems.  For example, elephants grind down their molars from eating so much plant material.  Fortunately for them, they have a supply of new molars that come in regularly.  Unfortunately for them, that supply is limited.  When an elephant runs out of molars, it dies of starvation.  Another example is plaque on dogs' teeth, which can lead to gum disease just like in humans.

Outside mammals animals just let bad teeth fall out and replace them as part of a continuous cycle of losing and replacing teeth, they don't keep teeth long enough for it to be an issue. Mammals are... weird, they only get the two sets. I would go further but Ram's answer covers how this question applies to mammals quite well. Although I should mention humans have relatively thin enamel out diets are rather low demanding in no small part due to the invention of fire.


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Why do F- bacteria still exist?
When an F+ bacteria conjugates with an F-, it makes the other bactaria F+ too. So on the long run, all bactaria should be F+.
Is there any mechanism that converts F- to F+? Could it be degeneration of F plasmid?

So an easy way to convert a cell from F+ to F- is to divide it without correctly replicating the plasmid and transferring it to a daughter cell, leaving you with one F+ and one F-. The cells that are F- now have a selective pressure advantage over the F+ cells, as they now don't require the energy to produce a plasmid when they divide. If that advantage is enough to overcome the frequency of conjugation, you'll end up having a population of F- cells.


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Why is pollen used as a dietary supplement?
Sporopollenin is the hardest biological substance and can't be degraded by any know enzyme (my school textbook). Then why is pollen used as a dietary supplement if it can't be digested?
Also, pollen depends on nutrients from the plant itself either before or after pollination (before if pollen leaves anther at 3 celled stage and after if it leaves anther at 2 celled stage). Then how would it be rich in nutrients?

But at some sites called as "germ pores" , sporopollenin is absent, so the enzymes may enter it via this, and the digested products may exit via this.

Do you have any citations that suggest that pollen supplements are indeed rich in nutrients or have any beneficial value? All of the evidence I am aware of is that pollen is used as a dietary supplement because people are willing to buy it at a price greater than the cost of producing it. There doesn't have to be any benefit to something sold as a dietary supplement.

Bee pollen contains high concentrations of reducing sugars, essential amino acids and unsaturated/saturated fatty acids. It contains minerals such as Zn, Cu, Fe, and high K/Na ratio and significant quantities of several vitamins. Note that the composition of it varies greatly depending on their botanical type and the techniques used by industries. It is basically the collection of pollen grains from flowers made by worker honey bees with nectar and salivary substances.[Source 1](Page 1)  [Source 2]

[Source 1](Page 4)
The claimed benefits of bee pollen are based on biological and therapeutic activities. The main components are phenolic acid derivatives and polyphenolic compounds. They are known to possess properties such as anti-oxidant, anti-aging, anti-carcinogen, anti-inflammatory, anti-atherosclerosis, cardio-protective and improved endothelial functions. However, it is unknown that treatments with such products are effective or not and how to minimise the health risks.[Source 1](Page 5) [Source 4]  [Source 5]  [Source 6]
Different studies were conducted in mice on the nutritional effects of bee pollen. It improved food digestion and also improved reproduction rates. Chickens fed with bee pollen had a better development of the small intestine. This suggested that bee pollen helped in early development of the digestive system. Bee pollen is also taken as a supplementation by athletes for improvement of performance. Controlled experiments indicated that no positive benefits were obtained. However, the number of training missed due to respiratory tract infection was lower in the bee pollen treated group.[Source 1](Page 5)

Pollen digestion:
Doubts have been raised, whether the tough shell of pollen can be breached and digested by humans. It was discovered in animal experiments that pollen did not retain its content after leaving thedigestive tract. This gave rise to the hypothesis that the nutritional content of pollen was released by the digestive juices in animals (Schmidt & Schmidt, 1984; Roulston & Cane, 2000). In humans it was once shown that pollen was absorbed in the digestive tract (Jorde & Linskens, 1974) or that it was partly digested, (Franchi et al., 1997) whereas there were differences in the degree of digestion of poppy and hazelnut pollen, with an average degree of digestibility of 15% for carbohydrates and 53% for proteins.
In this case it has been hypothesized that pollen was insufficiently digested and that cracking would improve the digestibility and bioavailability (Rimpler, 2003). Different companies offer cracked bee pollen, claiming that this product is better digested. On the other hand, there are many studies in humans with whole bee pollen showing that a part of the bee pollen content is digested and is bioavailable. However maceration of pollen for several hours in water or other liquids is recommended in order to improve digestibility, this method is used also for other heavy digestible grain products.[Source 1](Page 3 & 4)

Flower pollen:
Non-bee pollen are called flower pollen. Extensive health relevant research has been conducted on pollen prepartions from non-bee pollen. It is marketed under names such as Cernitron, Cernitol, etc. It is known to decrease prostrate hyperteophy in rats, but there was no relevant changes in blood levels of LH, FSH, testosterone or dihydro-testosterone.

In patients with prostatic adenoma the improvement was in nycturie, important decreases in the residue post-urinate and in long term treatment, also decrease in the diameter antero-posterior of prostate. The urinary debit did not suffer any changes. The effect on the other symptoms usual in the hyperthrophie benign of prostate was not of statistical significance (Bruneton, 1999).[Source 1](Page 7)

For industrial benefit:

Improved bioavailability is important in the pharmaceutical industry in that it reduces costs and increases the effectiveness of drugs. Previous studies have shown that this enhancement is possible using exines from pollens and plant spores. In one example the ingestion of ethyl ester derivative of EPA (eicosapentaenoic acid) encapsulated in sporopollenin microcapsules from L. clavatum spores improved the bioavailability of EPA in the bloodstream. In these trials, six volunteers ingested 4.6 g of fish oil containing 20% of the EPA ester, both alone, and encapsulated, as a 50% fat content powder, respectively. The bioavailability of the active was defined by area under curve (AUC (area under curve) 0–24 h). The mean AUC 0–24 of EPA from ethyl ester with exine was remarkably 10-fold higher than the corresponding for ethyl ester without exine encapsulation.
In other unpublished studies involving human volunteers, ingesting a lipophilic active, the enhancement of bioavailability has been very similar. The mechanism by which such enhanced bioavailability is achieved is intriguing and some preliminary experiments have been undertaken to explore possible explanations. Recent in vitro studies (unpublished studies) revealed that the exine shells exhibited gut mucosal adhesion properties. In addition, in vivo experiments on mouse microtone sections of intestinal walls of mice fed with exines showed the exines to lie between the gut villi. The unique morphology of exine shell surfaces probably evolved to help pollen particles to become attached to insects and thereby aid the process of pollination. It is possible therefore that this same morphology could help the exine’s adherence to and close association with the gut wall leading to an increase in the period of contact between the encapsulated drug and the biological surface, thereby enhancing its absorption and bioavailability.[Source 3]

Hazardous components of pollen:

Trace amounts of hepatotoxic pyrrolizidine alkaloids were found in pollen of Echium vulgare, E. plantagineum, Senecio jacobaea, S. ovatus, and Eupatorium cannabinum (Boppre et al., 2008).  In Middle and Northern Europe these pollens are not among the main pollen grains gathered by bees, however in Southern Europe the two Echium plants are more  diffused and are gathered by bees in larger amounts (Campos et al., 1994; Serra Bonvehi, 1997). [Source 1] (Page 5)

Therefore, it should undergo tests to approve it's purity as allergies can be caused.
References:
1 : Future of bee pollen(Research gate)
2 : Pollen composition and standardisation of analytical methods(Research gate)
3 : Hollow pollen shells to enhance drug delivery(NCBI)
4 : Bee pollen: chemical composition and therapeutic application(NCBI)
5 : Biological activities of commercial bee pollens: antimicrobial, antimutagenic, antioxidant and anti-inflammatory(NCBI)
6 : Biological and therapeutic properties of bee pollen: a review(NCBI)

I am skeptical about the broad claims about health effects to say the least. I will have a look on the journal article in question tomorrow, but this is a ten year old review which seems to have not been cited. This is usually not a very good sign.

@Chris The page says that it has 21 citations and 90 references.

It is also in a journal that only existed for two years. It's pretty hard for a journal to generate any positive reputation in that little time. Also one of the authors appears to be affiliated with a company in Switzerland that I wasn't able to find any information about, but there is no conflict of interest disclosure in the paper, which is quite troubling.

As I said, I will look at it tomorrow when I have journal access. This is not possible from home. But it smells a bit funny to me.

@BryanKrause Still, such an article can be cited. But it is even not listed in the Pubmed.

@Chris It simply isn't in a journal indexed by pubmed. Google scholar shows that it has been cited 45 times (though some could be duplicates or not real citations), but I don't necessarily take that as a measure of quality.  Paging through the citing articles many of them are in fairly red-flag journals, as well.