Vertebrate Sex Chromosomes
Guest Editor: Nobuo Takagi, Sapporo

Evolution of sex chromosomes

Cytogenetic studies of Hynobiidae (Urodela)
XVIII. A ZZ/ZW sex-determining mechanism in a hynobiid salamander species, Hynobius tokyoensis Tago
M. Kuro-o^a,b, C. Ikebe^c, Y. Izumisawa^b, Y. Fujinuki^b, K. Sasaki^b, K. Saso^b, K. Akaba^d, S. Kohno<sup>b

a</sup>Department of Biofunctional Science, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki; Departments of Biology,
^bFaculty of Science and
^cSchool of Pharmaceutical Sciences, Toho University, Funabashi, and
^dThe Prefectural Motegi High School, Haga (Japan)

Address of Corresponding Author

Cytogenet Genome Res 2002;99:194-199 (DOI: 10.1159/000071593)

  Abstract.

The karyotype of Hynobius tokyoensis (2n = 56) was analyzed using three kinds of banding methods to determine the morphological differentiation of the sex chromosomes of this species. Salamanders and egg sacs were collected from seven localities around Tokyo, Japan. Of 28 chromosome pairs, microchromosome No. 21 was identified as a ZZ/ZW-type sex chromosome. The Z chromosome was acrocentric, whereas the W chromosome was submetacentric, with a heterochromatic, elongated short arm. Interestingly, the W chromosome is of three distinct types, W^A, W^B, and W^C, based on R-banding and Ag-NOR patterns. W^A was detected in five populations from southern habitats, whereas W^B and W^C were detected in one population each from northern habitats. W^A, W^B, and W^C were all found to carry Ag-NORs on their heterochromatic short arms. Considering the karyotypes of other species belonging to the same genus, we discuss the evolution of the sex chromosomes of H. tokyoensis.   

Copyright © 2003 S. Karger AG, Basel

  Author Contacts

Request reprints from Dr. M. Kuro-o, Department of Biofunctional Science
Faculty of Agriculture and Life Science, Hirosaki University
3 Bunkyo-cho, Hirosaki, Aomori 036-8561 (Japan)
telephone: +81-172-39-3591; fax: +81-172-39-3750
e-mail: kuroo@mb.infoaomori.ne.jp.

  Article Information

This paper is dedicated to the memory of the late Dr. Susumu Ohno. Y.I.'s current address is Gene Analysis Section, Center for Molecular Biology and Cytogenetics, SRL, Inc., Tachikawa, Tokyo. Y.F.'s current address is Clinical Development, Nikken-Chemicals, Saitama, Saitama. K.A.'s current address is Motegi 1734-5, Motegi, Haga, Tochigi (Japan).

Received 30 September 2002;
revision accepted 28 February 2003.
Number of Print Pages : 6
Number of Figures : 4, Number of Tables : 2, Number of References : 45