Sex specific chromosome polymorphisms in the common Indian Krait,Bungarus caeruleus Schneider (Ophidia,Elapidae) |
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Authors: | Lalji Singh S P Ray-Chaudhuri K Majumdar I F Purdom K W Jones |
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Institution: | (1) Institute of Animal Genetics, University of Edinburgh, West Mains Road, EH9 3JN Edinburgh, Scotland;(2) Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, 700019 Calcutta, India |
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Abstract: | Chromosome analyses of common Indian Krait, B. caeuleus from three geographical regions of India have revealed variable diploid numbers of 43, 44 and 45 in different female individuals but a constant diploid number of 44 in the males. C-banding and in situ hybridization studies, using radio labelled W sex chromosome specific satellite DNA as a probe, have shown that C-banding and sex chromosome associated satellite DNA's are exclusively localised in the W chromosome. The W chromosome is involved in reciprocal translocations either with a medium sized macroautosome or with a microchromosome resulting in a multiple sex chromosome constitution of Z1Z1Z2Z2 /Z1Z2W type. In some female individuals dissociation of the W has resulted in multiple W chromosomes, W1 and W2. These polymorphisms are uniquely confined to the female sex only. A predominance of polymorphic females, involving particularly the translocation of a medium sized macrochromosome, in all three geeographical regions and the restriction of the females having the original chromosome constitution (ZW) to one geographical region suggests that polymorphic individuals have adaptive flexibility and higher fecundity. |
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