On the nature of meiotic associations involving heterochromatic ends in grasshoppers

Abstract

The nature of "terminal" associations between three heterochromatic short (S) bivalents of Schistocerca gregaria, and a heterochromatic and a euchromatic segment of an M7 bivalent of Euchorthippus pulvinatus has been investigated using a silver-staining technique that visualizes a core-like structure that extends through each homologous chromosome and forms cross-shaped configurations at chiasmata. It is concluded that most of these associations, about 99% in Schistocerca and 98% in Euchorthippus, are chiasmate. The problems concerning the nature of terminal associations involving heterochromatic ends in grasshoppers are discussed.Key words: silver-stained cores, chiasma, terminal association, heterochromatin, grasshoppers.