Study On The Expression Of Dmrt Gene In The Different Stages And Tissues Of (Plecoglossus Altivelis)

The ayu (Plecoglossus altivelis; sweetfish) is a popular migratory fish and one of the mosteconomically important freshwater fish in southeastern China and Japan due to both its perceivednutrition and taste. Belonging to the class Osteichthyes, suborder Salmonoidei, and familyPlecoglossidae, the ayu is also well-known for its comparatively fast reproduction cycles. Pairedwith the consumer preference for the fish’s superior flavor and faint smell. Owing to the femalesreproduce more quickly and adult male and female ayu display a sexual size dimorphism, so thatthe sales price of female ayu is nearly double that of a male. Given the consumer preference forfemales and the rise in the fishes popularity in Asia, finding a way to understand the sex-differentiation mechanism of ayu may prove worthwhile. Hence, in this study we analyzed thegonad transcriptome to identify the members of the sex-related double-sex and Mab-3-relatedtranscription factor (Dmrt) gene family.In our study, we cloned the full-length cDNA of ayu (Plecoglossus altivelis) Dmrt1andDmrt5. Sequence analyses showed Dmrt1and Dmrt5both contained a integrated open readingframe (ORF). The amino acid analyses showed the ayu Dmrt1clustered with that of Oncorhynchusmykiss and the homology can reached81.5%, and the ayu Dmrt5clustered with that of Danio rerioand the homology can reached84%. The phylogenetic tree revealed that the ayu Dmrt1and Dmrt5clustered with the other fishes and stayed away with human and mouse. Fluorescence-basedquantitative reverse transcription PCR (qRT-PCR) also revealed the Dmrt1was predominantlyexpressed in the testis. At the larva stages, Dmrt1mRNA expression level was highest during52–64days post hatching (dph) and at the gastrula stage during embryonic development. Dmrt5,meanwhile, was specifically expressed in the ovary and was highly expressed in the female braintissue, but not the male brain. During the larval stages, Dmrt5expression remained high before day34, and then fluctuated while generally decreasing. During embryonic development, Dmrt5expression increased gradually and peaked at the hatching stage. The fluorescence in situhybridization (FISH) of Dmrt5in embryo, sperm and ovum stages showed that Dmrt5expressed atmetencephalon at blastula stage, and it only detected in ovum. Moreover, Dmrt5expressed inventral fin and no Dmrt1mRNA was detected in fin of adult female ayu. The result of comparisonthe Dmrt5expression in unclear-sex-ayu fin ray and the results of paraffin section showed that theDmrt5only expressed in the ventral fin of female. So, whether the Dmrt5expressed in ventral fincan be regarded to the method of sex-determination.