In the beginning was the fat

So you are an imaging scientist. Probably you master an in vivo imaging system (CCD) and spend most of your working time in a lonely dark room collecting some spare photons coming out from a bioluminescent mouse, or frog, or zebrafish, or tobacco plant. Get out! Viviani and colleagues from the Sao Carlos University made some promenades during summer nights to collect adults and larvae of Aspisoma lineatum (Brazilian fireflies). Then they made some in vivo imaging with fireflies, just to discover that bioluminescence was not only a characteristic of adult lanterns. They found that also in larvae, a weak luminescence was associated with the fat body, hypothesizing that the origin of photocytes was from the fat body. Intriguingly, another group (Oba et al.) recently found that firefly luciferase displays fatty acid CoA activity, suggesting that originally luminescence was a side-product of a metabolic activity. So, in the beginning was the fat. This discovery opens other questions: light-emission is useful in adults for reproduction. What is the role of light-productions in larvae?

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Viviani, V., Okawachi, F., Scorsato, V., & Abdalla, F. (2008). CCD imaging of basal bioluminescence in larval fireflies: clues on the anatomic origin and evolution of bioluminescence Photochemical & Photobiological Sciences, 7 (4) DOI: 10.1039/b718016k

OBA, Y., SATO, M., OJIKA, M., & INOUYE, S. (2005). Enzymatic and Genetic Characterization of Firefly Luciferase and Drosophila CG6178 as a Fatty Acyl-CoA Synthetase Bioscience, Biotechnology, and Biochemistry, 69 (4), 819-828 DOI: 10.1271/bbb.69.819