Chromosomal distribution of constitutive heterochromatin in eight species of mahseers (Family: Cyprinidae) from India

Abstract

<span style="font-size:9.0pt;font-family:" times="" new="" roman";mso-bidi-font-family:="" mangal"="" lang="EN-GB">The chromosomal distributions of constitutive heterochromatin were analyzed in 8 species of mahseer, namely, <i>Tor</i> <i>chelynoides</i> (McClelland), <i>T. khudree</i> (Sykes), <i>T. mosal</i> <i>mahanadicus</i> (David), <i>T. mussullah</i> (Sykes), <i>T. putitora</i> (Hamilton), <i>T. progeneius</i> (McClelland), <i>T. tor</i> (Hamilton) and <i>Neolissochilus hexagonolepis</i> (McClelland) using C-banding technique. The constitutive heterochromatin bands were observed on several pairs of chromosomes with maximum numbers in <i>T. progeneius</i> (11 pairs), followed by <i>T. putitora</i> (7 pairs), <i>T. mosal</i> <i>mahanadicus</i> (4), <i>T. khudree</i> (3), <i>T. mussullah</i> (3), <i>N. hexagonolepis </i>(3), <i>T. chelynoides</i> (3) and <i>T. tor</i> (2). In all species, the C-bands were observed mainly on p arm with few on centromeric region of chromosomes. This seems to be the characteristic feature for characterization of these species. The presence of similar chromosome numbers (2n=100) with diverse karyotypes in the mahseer species suggests evolution among the species through pericentric inversions and/or heterochromatin processes. The number and location of the heterochromatic bands were found species-specific and thus useful for the cytotaxonomy of these species. The findings of the present study can also help to understand the evolutionary relationships among the mahseer species.

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