Paper

Identification of the sex chromosomes of the medaka, Oryzias latipes, by fluorescence in situ hybridization
M. Matsuda^a, C. Matsuda^a, S. Hamaguchi^b, M. Sakaizumi<sup>b

a</sup>Graduate School of Science and Technology;
^bDepartment of Environmental Science, Faculty of Science, Niigata University, Ikarashi, Niigata (Japan)

Address of Corresponding Author

Cytogenet Cell Genet 1998;82:257-262 (DOI: 10.1159/000015113)

  Abstract.

In the medaka, Oryzias latipes, which does not have cytologically recognizable sex chromosomes, the sex is genetically determined and the mechanism of sex determination (XX/XY) can be revealed by genetic crosses using a particular pigment gene. In a previous study, we isolated a sex-linked DNA marker (SL1) using the genomic differences between inbred strains of medaka. In the present paper, we further isolated another sex-linked clone (pHO5.110). The pHO5.110-related sequences were tightly linked to sex in O. latipes. We designated the locus of the pHO5.110-related sequence on sex chromosomes of medaka as Sex-Linked 2 (SL2). Southern blot analyses suggested that the pHO5.110-related sequence was tandemly repetitive in the medaka genome. Using the clone as a probe for FISH analysis, strong hybridization signals were obtained in a couple of chromosomes that formed one of two large submetacentric chromosome pairs. The pHO5.110-related sequences were repetitive in the genomes of other species of Oryzias (O. curvinotus, O. luzonensis and O. mekongensis) that are karyologically related to O. latipes (all are members of the so-called biarmed group). By contrast, the sequences were not detected as repetitive in other Oryzias species. Hence, it is thought that pHO5.110-related sequences were amplified in the genome of a common ancestor of the biarmed group.

  Author Contacts

Request reprints from Dr. Masaru Matsuda (present address):Laboratory of Reproductive Biology, National Institute for Basic Biology,Okazaki 444-8585 (Japan); telephone: +81-564-55-7553; fax: +81-564-55-7556;e-mail: matsuda@nibb.ac.jp

  Article Information

Received: Received 20 May 1998;
revision accepted 24 July 1998.
Number of Print Pages : 6
Number of Figures : 6, Number of Tables : 0, Number of References : 20