Analysis of structural rearrangements of Lepidoptera chromosomes using the centrifugation spreading technique

A centrifugation spreading technique (CST) was used to analyse 12 sex chromosome mutant female lines of the Mediterranean flour moth, Ephestia kuehniella. The method permitted visualization of the long synaptonemal complexes of microspread pachytene nuclei in the electron microscope. In four lines, T(W;Z)1-4, a stable translocation of a Z chromosome segment on the W chromosome was confirmed. In the other lines, designated ASF (abnormal segregating females), unexpected phenotypes segregated in atypical ratios. A quadrivalent with both sex chromosomes and an autosome bivalent was observed in females of the ASF-3 line, indicating that part of the Z chromosome was translocated on to one of the autosomes. In seven ASF lines, an additional fragment of the Z chromosome was found to be responsible for the segregation of unexpected phenotypes. It was shown that CST is useful for the study of chromosome aberrations in species with extremely small metaphase chromosomes. (author). 9 refs, 1 fig., 1 tab