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The B-isochromosome of Metaleptea brevicornis adspersa (Arididae) found in northern corrientes (Argentina)

María Cristina Pastor^I; Claudio JuanI Bidau^II

^IDepartamento de Genética, Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, Félix de Azara 1552, 3300 Posadas (Misiones), Argentina. Send correspondence to M.C.P.
^IIResearch Associate (CONICET)

ABSTRACT

Bidau (Caryologia 38: 165-177, 1986a) described the structure and meiotic behaviour of a large metacentric B chromosome with unusual characteristics from two populations of Metaleptea brevicornis adspersa from the localities of Otamendi and Ing. Maschwitz (Buenos Aires Province). We found the same B chromosome in one male among 45 individuals (11 females and 34 males) collected from Ituzaingó (Corrientes Province). Its meiotic behaviour was similar, including its ability to induce'a significant increase in the production of abnormal sperm, although its capacity to induce a generalised increase in chiasma frequency of the carrier had not been previously detected. Application of differential staining techniques with fluorochromes (Hoechst 33258 and Quinacrine) confirmed the isochromosomal condition of the extra element. The fording of this B chromosome at a distance of nearly 1000 km from the site of its original identification, suggests antiquity of the polymorphism and/or reproductive interaction and genetic flow between the populations.

Keywords: B-isochromosome;Metaleptea brevicornis adspersa.

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