Figure 2
Determination of genotypic and phenotypic sex by body color, genomic DNA PCR, and the secondary sexual characteristics of dorsal and anal fins. (A,B) Genotypes of white and orange-red body color of 60-dph Hd-rRII1 medaka reared under white LED (A) and green LED (B). A primer set designed for the conserved region of dmy, a sex determination gene on the Y chromosome, and dmrt1, an orthologue of dmy located on an autosome, were used for PCR analysis. Fin clips of adult males and females were used as positive controls. DW; distilled water for negative control. MW; molecular weight marker. (C) Genotypic female (white body color) showing female-specific fin types under green LED irradiation. An uncut dorsal fin (arrow) and a round-shaped anal fin (dotted line) are secondary sexual characteristics of females. (D) Genotypic male (orange-red body color) showing male-specific fin types under green LED irradiation. A deeply cut dorsal fin (arrow) and a parallelogram-shaped anal fin (dotted line) are secondary characteristics of males. (E) Genotypic female (white body color) showing secondary characteristics of males, i.e. a deeply cut dorsal fin (arrow) and a parallelogram-shaped anal fin (dotted line). (F–H) External observation of the gonads of green LED-irradiated medaka (C–E). Dotted lines show ovary (F) and testes (G,H). (I–K) Histological observation of gonads of green LED-treated medaka (C–E). Perinucleolar oocytes (arrows in I) in ovaries and spermatogenic cells (arrows in J) were observed. Spermatogenic cells (arrows) including spermatozoa (arrowheads) were observed in female-to-male sex-reversed medaka testes (K). Scale bars = 2 mm (C–H), 40 μm (I–K).
