Abstracts (first author)
Transcriptome analysis of predator- and prey-induced phenotypic plasticity in the Hokkaido Salamander (Hynobius retardatus)
Larvae of the Hokkaido salamander (Hynobius retardatus) exhibit two distinct morphs, "attack morphs" and "defense morphs", as a result of inducible phenotypic response to preys and predators, respectively. The existence of preys, Rana pirica tadpoles, leads to the induction of attack morphs, which have broad heads likely suitable for catching tadpoles. The existence of predators, dragonfly larvae (Aeshna nigroflava), induces them to become defense morphs, which have enlarged external gills and high tails suitable for avoiding the predatory attacks. However, molecular mechanisms underlying this phenotypic plasticity have yet to be elucidated. To reveal the developmental and physiological mechanisms of this phenotypic plasticity, we carried out de novo transcriptome analysis of the Hokkaido salamanders. First, we collected eggs in the wild and then hatched them in laboratory. The larvae were exposed to either predators or preys to induce different morphs. Morph induction was completed about 7 days after the start of exposure. RNAs were extracted from 4 tissues (brain, head, external gill and tail) and 3 time points (0 hour, 12 hours, and 7 days after the exposure onset) and sequenced. Obtained reads and contigs of treatment samples were compared with those of control samples (i.e. no exposure) to identify differentially expressed genes. Approximately 2,000 genes were identified as differentially expressed genes at each time point and in each tissue. These genes include hormone related functional genes, such as COL2A1, HBA2, and NR2C1. RNA processing/splicing was found as an enriched functions in the Gene Ontology database, suggesting that the phenotypic plasticity of Hokkaido salamanders may be linked to regulation of alternative splicing.