Differential transcript expression of selected gene batteries in two clonal strains of the self-fertilizing fish, Kryptolebias marmoratus.

The hermaphroditic fish, Kryptolebias marmoratus is known as a unique vertebrate that reproduces by internal self-fertilization, resulting in genetic homogeneity. In this study, we characterized two strains, PAN-RS (13 and 20 days after hatching, dah) and DAN (20 dah), that show different growth rates and morphometric parameters. In the same period (20 dah), the PAN-RS strain showed significantly faster growth rate than the DAN strain in all the parameters measured in this study. In the case of the 13 dah of PAN-RS strain, they showed similar morphometries and growth rate with the DAN strain (20 dah). To investigate why they showed different growth rates in both strains, we analyzed the transcript profile of several genes, such as growth-, hypothalamic-pituitary-gonadal axis-, vitellogenesis-, steroidogenesis-, and sex-related gene for both strains. Based on our results, the different growth rates with several reproduction parameters would be associated with transcript profiles of some gene batteries as the first trigger for the related protein expression in both strains. In addition, this study would provide a better understanding of the physiology and endocrinology in K. marmoratus, particularly, of the transcriptional regulation of growth- and reproduction-related genes with clonal difference.