Astylus variegatus (Coleoptera, Melyridae): Cytogenetic study of a population exposed to agrochemical products
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Data
2007-01-01
Autores
Schneider, Marielle Cristina [UNESP]
Carraro, Bianca Pierina
Cella, Doralice Maria [UNESP]
Matiello, Rodrigo Rodrigues
Artoni, Roberto Ferreira
Almeida, Mara Cristina
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Genética
Resumo
In this work we describe the cytogenetic analyses performed in specimens of Astylus variegatus (Germar, 1824) collected in two localities: one area of natural vegetation and one of agricultural crops, where agrochemical products were used. Astylus variegatus had karyotypes with 2n(male) = 16+Xy p and 2n (female) = 16+XXp, with exclusively metacentric chromosomes. Pachytene spermatocytes showed synapsed autosomal bivalents and non-associated sex chromosomes. In diplotene, the autosomal bivalents exhibited one or two terminal chiasmata and the Xy p had a typical parachute configuration. In meiotic cells of some specimens, an extra chromosome, interpreted as a B chromosome, was observed. C-banding showed constitutive heterochromatin in the pericentromeric region of all chromosomes, with the exception of the y p. Silver nitrate staining revealed one nucleolus organizer region (NOR) on the terminal region of the short arm of the second autosome pair. Silver staining of meiotic cells confirmed the NOR pattern detected in mitotic cells and revealed an argentophilous material on the Xy p. A cytogenetic comparison between the two populations of A. variegatus showed a statistically significant divergence (chi2 = 117.10; df = 1) in the number of aneuploid cells and a higher frequency of B chromosome in the population exposed to agrochemicals.
Descrição
Palavras-chave
B chromosome, constitutive heterochromatin, karyotype, meiosis, Ag-NORs
Como citar
Genetics and Molecular Biology. Sociedade Brasileira de Genética, v. 30, n. 3, p. 640-645, 2007.