Preliminary cytogenetic study and report of ZZ/ZW sex chromosomes in the bullfrog, Hoplobatrachus tigerinus (Anura, Amphibia) from high altitude area of Jammu and Kashmir, India

Abstract

Cytogenetic study of the Indian Bullfrog, Hoplobatrachus tigerinus was carried out using both conventional staining and banding methods, from Jammu and Kashmir. Karyotypes prepared by conventional staining in both male and female specimens showed diploid chromosome number as 2n = 26 and fundamental arm number as NF = 52. Karyotypes of both the sexes comprised of 13 pairs of biarmed chromosomes divided into two groups: first group of five pairs of larger metacentric or submetacentric chromosomes and second group of eight pairs of smaller metacentric or submetacentric chromosomes. Pair number 2, 3, and 4 among the first group and 8 and 9 among the second group were submetacentric chromosomes. All the other chromosomes in both the groups were metacentric. Meiotic stages observed were leptotene, diakinesis, metaphase-I and metaphase- II, from testicular cells of males. C-banding analysis of the species showed presence of centromeric C-bands in all the chromosomes of both male and female karyotypes. Female karyotype showed presence of completely heterochromatic homologue of the pair no. 8, which represented ZZ/ZW sex chromosome system in the species. NOR-banding showed presence of a pair of nucleolar organizer regions on the long arm of 6th pair in both the sexes.