Constitutive heterochromatin variation in two species of rattus with apparently similar karyotypes
✍ Scribed by T. Sharma; I. K. Gadi
- Publisher
- Springer Netherlands
- Year
- 1977
- Tongue
- English
- Weight
- 357 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0016-6707
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✦ Synopsis
Rattus blanfordi and R. cutchicus medius both have a chromosome complement of 2n = 36 and all chromosomes except the submetacentric Y of R. blanfordi are acrocentric. The apparently similar karyotypes of the two species, however, show variations in the nature and quantity of C-band-positive constitutive heterochromatin (C-heterochromatin) as revealed by C-and G-banding and Hoechst 33258 fluorescence. R. blanfordi with large-sized X and Y chromosomes and conspicuously larger centromeric heterochromatin in all the autosomes as compared to that of R. cutchicus medius has much more C-heterochromatin in its genome than the latter. The variation in the quantity of C-heterochromatin has been accomplished without altering the morphology of the acrocentric chromosomes unlike other mammals in which variations have been reported to result generally in the addition or deletion of a totally heterochromatic second arm.