Chromosome Study of Some Ethiopian Anuran Amphibians
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Date
2008-06
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Addis Ababa University
Abstract
Eight families consisting of 24 genera and 63 species of amphibians have been recorded
in Ethiopia, and out of these 40% are endemic. Little is dealt about the ecology and
behaviour of amphibians, and karyotypes of amphibians in Ethiopia had not been
studied prior to this study. Chromosome numbers and karyotypes are reported for eight
species of anuran amphibians belonging to five genera, collected from various
geographical locations in Ethiopia. Chromosome preparations were made from
intestinal epithelial cells after pre-treatment with colchicin. Air-dried slide preparation
was made by splashing techniques after treating the cells with 0.075 M KCL hypotonic
solution for about 25 - 30 minutes followed by several rounds of centrifugation in
fixative (3 methanol: 1 acetic acid). Chromosome characteristics were determined from
mitotic metaphase chromosome spreads following chromosome staining with Giemsa in
phosphate buffer (pH = 6.8). The result showed that four species: Ptychadena anchietae
(Bocage 1867), Ptychadena neumanni (Ahl 1924), Ptychadena cooperi (Parker 1930),
Hyperolius; have 2n = 24; two species Bufo, Bufo garmani Meek 1897, and B. regularis
Reuss 1834, have 2n = 20; one species of Rana; Rana angolensis Bocage 1866 has 2n =
26; and a species of Xenopus, Xenopus clivii Peracca 1898 has 2n = 36. All species
under the study are dominantly bimodal karyotype, i.e., composed of distinctly large
and small chromosomes, except Xenopus clivii that varies in a gradual manner with
most of sm and st chromosomes of the set. In the present study, different species of a
given genera have very similar karyotype so that it is impossible to differentiate the
species only on the basis of their karyotype.
Key word: Asymmetrical; Chromosome;Cytogenetic; Karyotype;and Symmetrical.
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Keywords
Asymmetrical; Chromosome;Cytogenetic; Karyotype;and Symmetrical.