Zur Funktion des W-Chromatins bei Ephestia kuehniella (Lepidoptera)

Abstract

In female somatic nuclei, the W-chromosome forms a heterochromatic body, the so-called W-chromatin. This is absent in male nuclei. After a γ-ray treatment several mutations of W have been obtained. They influence the behavior of the W-chromatin in somatic nuclei. These mutations can be classified in three groups. The first group comprises five W-fusions. In females of these strains the W or a part of it is coupled to an autosome. During meiosis, these fusions pair with the Z and the homologous autosomes. The W-fusions disturb the normal formation of W-chromatin. Several smaller bodies are observed instead of a single W-chromocenter. The second type of mutation is a translocation between W and an autosome. Pairing in meiosis occurs only with the homologue autosome. It appears in 50% of males and 50% of females. In somatic nuclei it produces many very small particles of W-chromatin. The third type of mutation is represented by eight fragments of W. During meiosis, they form supernumerary fragment-chromosomes. In somatic nuclei, these are present as chromocenters similar to W-chromatin. W-fragments apppear approximately in one half of both sexes. By crossing, animals carrying up to four W-fragments could be produced. This heterochromatin additional to W-chromatin does not perceptibly influence either sex determination and fertility or quantitative characters such as duration of development, weight or diameter of eye facets.