CHIASMA STUDIES IN STRUCTURAL HYBRIDS. X. FURTHER STUDIES IN ACRIDA LATA

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Abstract
In 98.2% of the MI [metaphase I] cells of a translocation heterozygote of A. lata Motschulsky (2n = 22 + X), 1 chiasma was formed in one of the interstitial segment. In 96.1% of the cells, the distal unequal segments were separated equationally at AI [anaphase I]. Frequencies of chiasmata at diplotene and MI were compared using a heteromorphic bivalent in which partner chromosomes were different for a block of heterochromatin and a special trivalent in a so-called centric fusion heterozygote. Chiasmata at these 2 stages were equally frequent, showing that no reduction in number of chiasmata was accompanied by the process of terminalization from diplotene to MI in the present material.