PERICENTRIC CHROMATIN POLYMORPHISM IN POL YTENE CHROMOSOMES OF OVARIAN TROPHOCYTES IN NATURAL-POPULATIONS OF MALARIA MOSQUITO ANOPHELES MESSEAE FALL

Pericentric heterochromatin polymorphism in chromosome 2 of ovarian tr ophocytes was studied in three natural populations of the malaria mosq uito Anopheles messeae Fall. It is shown that pericentric heterochroma tin blocks occur in four different variants whose sizes are at the 1 : 2 : 3 : 4 ratio (single, double, triple, and quadruple blocks). Mosqu itoes with homo- and heterozygous variants of these blocks were identi fied. By analyzing frequency distribution of different size variants, interpopulation differences in this parameter were revealed. Mosquitoe s with double heterochromatin blocks prevailed in the southern populat ion, whereas those with triple blocks were more abundant in the northe rn population.