Segregation of the univalent X chromosome in the wide-footed treehopper Enchenopa latipes (Say 1824)

Abstract

In metaphase I, autosomal bivalents align on the metaphase plate, while naturally-occurring univalent sex chromosomes can display a number of different behaviours depending on cellular conditions. Here we describe the behaviour of the univalent X chromosome in the wide-footed treehopper Enchenopa latipes (Say 1824). We confirm the chromosome number and sex determination method for this species, and that males possess a univalent X chromosome. We show that the univalent X chromosome forms a bipolar attachment to the spindle in metaphase I, and then segregates intact toward one spindle pole in late anaphase I (long after autosomes have initiated poleward movement). Movement of the univalent toward one pole is associated with loss of microtubule connections toward the opposite spindle pole.