Persistent meiotic association of a rare B chromosome and an autosomal segment inAtractomorpha similis (Orthoptera: Acridoidea)

Autor: G. B. Peters
Rok vydání: 1984
Předmět:
Zdroj: Genetica. 63:129-137
ISSN: 1573-6857
0016-6707
Popis: Supernumerary chromosomes have been reported in many species particularly in the Orthoptera. Although it is assumed that these chromosomes are ultimately derived from elements of the standard karyotype, in no case recorded is there convincing evidence of even partial homology between true supernumeraries and other chromosomes. In the present paper, a very rare B chromosome in the grasshopperAtractomorpha similis is reported. It associates specifically and persistently with a large segment on Autosome 5 (A5). Associations were seen in 29 out of 288 meiocytes scored, and persisted to Anaphase I. At least four of the 29 associations appear to be of a genuinely chiasmate nature, implying some degree of homology. The A5 segment is itself supernumerary, occurring in 8% of individuals scored. Supernumerary segment polymorphism is extremely common in this species, as is germ line polysomy for Autosome 9. In the light of these pecularities, a possible mode of derivation, involving Autosome 9, is proposed for the B chromosome in question. Supernumeraries of the closely related speciesA. australis are also discussed insofar as they suggest the occurrence of seemingly diverse modes of B chromosome derivation within the genusAtractomorpha.
Databáze: OpenAIRE
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