ALTERED PATTERNS OF GENE-EXPRESSION IN TRIBOLIUM SEGMENTATION MUTANTS

Embryos homozygous for the godzilla, laws, or kraken mutations of Trib olium castaneum have characteristic defects in segmentation. Here, we examine the expression of Tribolium genes homologous io Drosophila seg mentation genes in these mutants io define similarities and difference s in the process of segmentation in the two insects. The godzilla muta tion disrupts segmentation and alters the expression of Even-skipped ( Eve) throughout the germ band. godzilla, therefore, acts at an easy st ep in the segmentation gene hierarchy; the evidence suggests it could be the Tribolium homologue of the eve gene. The jaws mutation causes d eletion of mosi of the abdomen; this defect appears to be correlated w ith the failure of Eve io resolve into a striped pattern of expression , jaws also causes homeotic transformations in the thorax and the firs t abdominal segment; this transformation is accompanied by ectopic exp ression of the homeotic gene maxillopedia in the transformed segments. The kraken mutant disrupts patterning within each segment and, like D rosophila segment polarity mutants, disrupts the maintenance of the no rmal expression domain of Engrailed. This analysis suggests that late sages of segmentation are similar in Tribolium and Drosophila, althoug h there are clear differences in early steps of segmentation in the tw o insects. (C) 1998 Wiley-Liss, Inc.