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Effects of extra chromosome segments on chiasma distribution in Xyleus angulatus (Orthoptera: Romaleidae)

Maria José de Souza; Maria Helena N. Lobo Silva Filha

Departamento de Genética - CCB, Universidade Federal de Pernambuco, 50739 Recife, Pernambuco, Brasil

ABSTRACT

In a study of 36 male Xyleus angulatus specimens, large C band blocks were mainly found in the pericentromeric region of all chromosomes. Narrow C-positive bands were also detected in the interstitial areas of three large chromosome pairs. Extra heterochromatin segments (El IS) were detected in three medium sized chromosome pairs (M5, M6 and M7) and in a small chromosome (S 11) of one population. In another population, the EI IS plus extra euchromatin segments (El IS/EES) were detected in pair S 10. Meiotic analysis of specimens of the latter population showed a decrease in mean chiasma frequency per cell and also changes in intra and interchromosomal chiasma distribution.

Keywords: Extra chromosome; Chiasma; Xyleus angulatus; Orthoptera.

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