have also shown that biliverdin is present in the blue-green blood of many marine fish, the blood of tobacco hornworm, the wings of moth and butterfly, the serum and eggs of frogs, and the placenta of dogs. With dogs this can lead, in extremely rare cases, to the birth of puppies with green fur; however, the green color fades out soon after birth. In the garfish (Belone belone) and related species, the bones are bright green because of biliverdin. Biliverdin is also present in the green blood, muscles, bones, and mucosal lining of skinks of the genus Prasinohaema, found in New Guinea. It is uncertain whether this presence of biliverdin is an ecological or physiological adaptation of any kind. It has been suggested that accumulation of biliverdin might deter harmful infection by Plasmodium malaria parasites, although no statistically significant correlation has been established. The Cambodian frog, Chiromantis samkosensis, also exhibits this characteristic along with turquoise bones. In fluorescence imaging In a complex with reengineered bacterial phytochrome, biliverdin has been employed as an IR-emitting chromophore for in vivo imaging. In contrast to fluorescent proteins which form their chromophore through posttranslational modifications of the polypeptide chain, phytochromes bind an external ligand (in this case, biliverdin), and successful imaging of the first bacteriophytochrome-based probe required addition of the exogenous biliverdin. Recent studies demonstrated that bacteriophytochrome-based fluorescent proteins with high affinity to biliverdin can be imaged in vivo utilizing endogenous ligand only and, thus, with the same ease as the conventional fluorescent proteins. Advent of the second and further generations of the biliverdin-binding bacteriophytochrome-based probes should broaden the possibilities for the non-invasive in vivo imaging. A new class of fluorescent protein was evolved from a cyanobacterial (Trichodesmium erythraeum) phycobiliprotein, α-allophycocyanin, and named small ultra red fluorescent protein (smURFP) in 2016. smURFP autocatalytically self-incorporates the chromophore biliverdin without the need of an external protein, known as a lyase. Jellyfish- and coral-derived fluorescent proteins require oxygen and produce a stoichiometric amount of hydrogen peroxide upon chromophore formation. smURFP does not require oxygen or produce hydrogen peroxide and uses the chromophore biliverdin. smURFP has a large extinction coefficient (180,000 M−1 cm−1) and has a modest quantum yield (0.20), which makes it comparable biophysical brightness to eGFP and about 2-fold brighter than most red or far-red fluorescent proteins derived from coral. smURFP spectral properties are similar to the organic dye Cy5. See also Bilirubin Heme Stercobilin Tetrapyrrole Urobilin