RNA-Seq analysis of the bioluminescent and non-bioluminescent species of Elateridae (Coleoptera): Comparison to others photogenic and non-photogenic tissues of Elateroidea species

Abstract

Bioluminescence in the superfamily Elateroidea is produced by specific light organs distributed in different parts of the body depending on the life stage and family. Whereas the luciferin-luciferase system is well known, the molecular control of bioluminescence, the biosynthetic route of luciferin, and the molecular differentiation of photogenic tissue in Elateridae remain enigmatic. With the aim to improve the knowledge about these questions, we performed the RNA-Seq analysis of lanterns and fat body of the Brazilian click beetle larvae: Pyrearinus fragilis (luminescent) and Conoderus sp. (non-luminescent) and compared the gene products contents and their abundance among these tissues. For the first time, we showed that the fat body of luminescent click beetle displays luminescence. We also analyzed some gene products expression patterns in lantern and fat body of Elateridae. Several of them, which are potentially involved with bioluminescence and its control are also found in the transcriptional profile of the firefly Aspisoma lineatum (Lampyridae) and the railroad worm Phrixothrix hirtus (Phengodidae). These gene products were observed in both lanterns and fat body of elaterid species, however with low abundance in the fat body. The results indicate that in Elateridae, the bioluminescent tissue also originated from the fat body. In P. fragilis, we observed two luciferase/luciferase-like enzymes with high abundance, one in the lantern and a different one in the fat body, indicating the possibility of two distinct isoenzymes involved in the bioluminescence in the lantern and fat body of Elateridae species, such as observed in fireflies.