Karyotype, heterochromatin content and meiotic features ofPoecilocera picta (Orthoptera, Acrididae)

Autor: Prasad Koduru, J. R. Grace, M. K. Rao
Rok vydání: 1985
Předmět:
Zdroj: Genetica. 67:31-37
ISSN: 1573-6857
0016-6707
DOI: 10.1007/bf02424458
Popis: Cytological study of three distinctly separated populations ofPoecilocera picta revealed a chromosome number of 2N = 18 + XO/ XX. Except for the hemizygosity of a procentric heterochromatic block in the M6 pair of the Bangalore population, the basic karyotype of the three populations is markedly similar. The autosomal karyotype formula is 2Lt + 4Mt + 1 Mst + 2S st and the telocentric X chromosome is the longest of the complement. All bivalents at pachytene carried procentric heterochromatic blocks. The M4 is the nucleolus organiser with the NOR region situated interstitially but proximal to the centromere. About 11 µm (4%) of the total (290 µm) autosomal pachytene complement is heterochromatic; a major portion of it is contributed by the S9 pair which is mostly heterochromatic. Chiasmata are localized proximally and distally and in the S9 pair their formation is confined to the short procentric euchromatic segment of the long arm. Female meiosis did not reveal any chromomere pattern at pachytene and, unlike in the male, the sex bivalent in the female is indistinguishable from the autosomal bivalents. G- and C-banding patterns in males showed procentric bands in all the chromosomes. In addition there are eight telomeric and two interstitial bands which are C negative. The S9 pair showed only two bands. The G-banding pattern of the sex chromosome in meiosis showed only a centric band while the heterochromatic body of the facultatively heterochromatic X remained G negative.
Databáze: OpenAIRE
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