Genetic control of early structural development
Edward B. Lewis, Christiane Nusslein-Volhard and Eric F. Wieschaus fly (Drosophila) embryos.
In the late 1970s much was known about the various stages of embryonic development, but the control of these stages was poorly understood. Christianne Nusslein-Volhard and Eric F. Wieschaus wanted to find the genes that cause a fertilised egg to transform into a segmented embryo. Each embryo segment goes on to form specific parts of the offspring’s body, so this is a vital stage in early embryo formation.
Nusslein-Volhard and Wieschaus conducted their work in fruit fly embryos because of their rapid development. They randomly mutated fruit fly genes and monitored the effects. After a year of this work, the pair had identified 15 genes that when mutated, affected the segmentation of fruit fly embryos. By analysing the results of mutations, the researchers were able to determine the function of each gene and when it is most important; for instance, some genes affected the definition of an embryo’s head and tail ends, while others took action later in development, affecting specific segments.
Edward B. Lewis also studied fruit flies. He was interested in the mutation that caused fruit flies to develop two sets of wings, instead of their usual one. In the late 1970s he discovered the HOX gene complex, which controls the development of embryonic segments into different parts of the body, and whose malfunction was responsible for the fruit flies with too many wings.
It has since been shown that very similar genes to those identified by Lewis, Nusslein-Volhard and Wieschaus perform the same functions in other animals, including humans. Mutations in these genes are now known to cause many of the congenital malformations affecting humans.
Last edited: 11 November 2014 12:33
Edward B. Lewis, Christiane Nusslein-Volhard na Eric F. Wieschaus kudhibiti urithi wa maendeleo ya mapema ya muundo (Drosophila) viini. Katika miaka ya 1970, mambo mengi yalijulikana kuhusu hatua mbalimbali za maendeleo ya kiinitete, lakini udhibiti wa hatua hizi haukueleweka vizuri. Christianne Nusslein-Volhard na Eric F. Wieschaus walitaka kupata jeni zinazosababisha yai lililotengenezwa kuwa kiinitete kilichotengenezwa kwa sehemu. Kila sehemu ya kiinitete huendelea kufanyiza sehemu hususa za mwili wa mtoto, kwa hiyo hii ni hatua muhimu katika kuanzishwa kwa kiinitete mapema. Nusslein-Volhard na Wieschaus walifanya kazi yao katika viini-tete vya nzi wa matunda kwa sababu ya ukuzi wao wa haraka. Walifanya mabadiliko ya chembe za urithi za nzi wa matunda kwa nasibu na kufuatilia matokeo yake. Baada ya mwaka mmoja wa kazi hiyo, waligundua jeni 15 ambazo zinapobadilika, huathiri mgawanyiko wa viini vya nzi wa matunda. Kwa kuchambua matokeo ya mabadiliko, watafiti waliweza kuamua kazi ya kila jeni na wakati ni muhimu zaidi; kwa mfano, baadhi ya jeni kuathiri ufafanuzi wa kichwa cha kiinitete na mkia mwisho, wakati wengine alichukua hatua baadaye katika maendeleo, kuathiri sehemu maalum. Edward B. Lewis pia alichunguza nzi wa matunda. Alipendezwa na mabadiliko ya chembe za urithi yaliyomfanya nzi wa matunda awe na mabawa mawili badala ya moja ya kawaida. Katika miaka ya 1970, aligundua jeni la HOX, ambalo linadhibiti maendeleo ya sehemu za kiinitete katika sehemu tofauti za mwili, na ambayo kazi yake mbaya ilikuwa na jukumu la kuunda nzi wa matunda na mabawa mengi. Tangu wakati huo, imethibitishwa kwamba jeni zinazofanana sana na zile zilizotambuliwa na Lewis, Nusslein-Volhard na Wieschaus hufanya kazi sawa katika wanyama wengine, ikiwa ni pamoja na wanadamu. Sasa inajulikana kwamba mabadiliko katika chembe hizo za urithi husababisha kasoro nyingi za kuzaliwa ambazo huathiri wanadamu. Mhariri wa mwisho: 11 Novemba 2014 12:33