2012 Fiscal Year Final Research Report

Functional analysis of an insect sex determining gene found inSaccoglossus kowalevskii genome.

Research Project

Project/Area Number	23657154
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Evolutionary biology
Research Institution	The University of Tokyo
Principal Investigator	SUZUKI Masataka 東京大学, 大学院・新領域創成科学研究科, 准教授 (30360572)
Project Period (FY)	2011 – 2012
Keywords	性決定 / 性分化 / 選択的スプライシング / ギボシムシ / 進化
Research Abstract	We have found a gene (here after, depicted as Sktra) in Saccoglossus kowalevskii genome that is closely similar to a tra gene which is known to act as a central role in insect sex determination and determined its full-length cDNA sequence and its exon/intron structure. RT-PCR analyses demonstrated that, differ from the insect tra gene, no sex-specific splicing variants were observed in Sktra transcripts. The expression level of Sktra mRNA in testes is 9-fold higher than in ovaries. This result raises the possibility that Sktra is involved in sexual differentiation of S. kowalevskii. Splicing assays using insect culture cells revealed that Sktra can induce female-specific splicing of Drosophila dsx minigene pre-mRNA when co-transfected together with Sktra-2 cDNA. This result strongly suggests that the splicing activity specifically identified in insect Tra proteins is conserved in SkTra protein. We provide the world’s first evidence that demonstrates functional conservation of tra gene found in deuterostomes.