Cytogenetics of the South American Akodont rodents (Cricetidae) X. Akodon mollis: a species with XY females and B chromosomes
✍ Scribed by L. Lobato; G. Cantos; B. Araujol; N. O. Bianchi; S. Merani
- Publisher
- Springer Netherlands
- Year
- 1982
- Tongue
- English
- Weight
- 971 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0016-6707
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✦ Synopsis
The morphology, G-and C-banding pattern of the Akodon mollis chromosome complement is analysed. Over a total of 14 males and 10 females studied, 8 males and 7 females had a modal chromosome number of 22, while 6 males and 3 females showed a modal number of 23 chromosomes. In the animals with 23 chromosomes the odd element was considered a B chromosome on the basis of: (a) its small size, (b) the lack of an homologous chromosome and the subsequent formation of univalents at diakinesis and metaphase I from testes, (c) the weak or null genetic action as evidenced by the lack of any obvious variation in the phenotype of carriers.
Four females exhibited a sex-pair dimorphism indistinguishable from that observed in males, The G-banding analysis showed homology between the pattern found in the Y chromosome and that detected in the short arm of the X. The ~tudy of C-band distribution showed that several autosome pairs and the X chromosomes had small masses of centromeric heterochromatin. On the other hand, the Y and B chromosomes were C-band negative. The Y-like chromosome in females with dimorphism of the sex pair was also C-band negative. Accordingly these females were considered to be XY and not Xx (the x being an extensively deleted X chromosome).