C-HETEROCHROMATIN DURING SYNAPSIS AND RECOMBINATION IN GREY COCKROACH NAUPHOETA CINEREA SPERMATOGENESIS
O. S. Kornienko,1 A. M. Gusachenko, L. V. Vysotskaya
Department of Cytology and Genetics, Novosibirsk State University;
1 e-mail: olfa@mail.ru
The behaviour of large distal C-heterochromatic blocks in spermatogenesis of grey cockroach Nauphoeta cinerea was investigated by light and electron
microscopy. Heterochromatic blocks of some autosomes are involved into nonhomologous association with formation of chromocenter in early meiotic prophase I.
Fluorescent in situ hybridization with ribosomal DNA-probe revealed the signal on only two pairs of middle chromosomes, which did not participate in the
chromocenter formation, therefore appearance of ectopic contacts was not caused by the nucleolus formation. The analysis showed that heterochromatin in the
chromocenter was eliminated spatially and functionally from main meiotic events. Heterochromatin does not participate in the bouquet formation, initiation of
homologous pairing, and recombination events. Heterochromatic polymorphism results in asymmetric synaptonemal complexes with different degree of synaptic
adjustment. Meiotic axis of sex univalent (XO - sex male determination) is split in different regions irrespective of heterochromatin localization.
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