Teleost fish as unique models facilitate better understanding of gene functions

June, 15th
Versione stampabile

Venue: Edificio Povo 1, via Sommarive nr. 5, Povo (Tn) - Room A212
 At 9.00 a.m.

  • Hayato Yokoi - Graduate School of Agricoltural Science, Tohoku University, Sendai, Japan

Teleost fish experienced an extra round of whole genome duplication after diverged from the tetrapod lineage. Duplicated genes underwent evolutionary diversification in a lineage specific manner, so gene repertoire might be different among species, making orthological characterization difficult. Understanding correct orthology is critical, when comparing gene functions between species and when using teleost fish as model system to investigate vertebrate biology. Evolution of Fgfr1, Sox9 and Aldh1a gene families exemplifies how gene functions can diversify among teleost species. First, loss-of-function phenotype of fgf8 and fgfr1 is similar in zebrafish, suggesting that Fgf8 signal is mediated by Fgfr1. Comparative analysis using another fish model medaka indicated the diverged function of them between species. Second, Sox9 is a transcription factor involved in many developmental processes, and teleost fish have duplicated paralogs, sox9a and sox9b. Functional analysis using zebrafish mutants showed that ancestral functions were partitioned between the two sox9s. The partitioning pattern, however, is diverged among zebrafish, medaka and stickleback, reflecting their phylogenetic relationship. Finally, Aldh1a genes encode retinoic acid (RA) synthesizing enzymes. Gene number varies among species, as rodents have four Aldh1a genes whereas medaka has only one ortholog, aldh1a2. Synteny analysis and expression analysis showed the evolutionary gene-loss and potential compensating examples. Given the highly diversified gene functions among teleosts, using multiple teleosts species might provide us with a more complete picture of biological phenomena.

Latter part, I’d like to introduce our recent research toward flatfish metamorphosis, an enigmatic and dynamic morphogenesis.