| Budget Amount *help |
¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
Using a male-determining factor-congenic strain of the Japanese medaka, Oryzias latipes, we screened a genomic DNA library and isolated two sex-linked DNA clones, SL-5 and SL-110. The nucleotide sequences were completely determined. SL-5 was a single-copy sequnece 1.7 kb in size. SL-110 was a repetitive sequence 498 b in length.
We designed PCR primer sets at both ends of these clones. Length of the PCR product using the SL-5 primer sets was different between two inbred strains, Hd-rR and HNI.The PCR product using SL-110 primer sets gave different cleavage patterns between these strains when degested by Hae III.
Segregation of a total of four loci, which included two DNA loci (SL-5 and SL-110), a pigment-pattern locus (r) and a male-determining factor (y), were examined using backcrosses of Hd-rR and HNI.No recombinant progeny were obtained from F1 males of the reciprocal crosses. By contrast, many recombinant progeny (>25%) were obtained from F1 females between SL-5 and SL-110.
These results indicates that marked difference in recombination rate exists between XY nales and XX females. Such recombination restriction in XY males may have allowed the establishment of the orange-red male and white female strain, d-rR.In order to elucidate the mechanism of recombination restriction, segregation analyzes of sex-reversed fish are in progress.
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