COMPARISON OF THE STRUCTURE AND EXPRESSION OF ODD-SKIPPED AND 2 RELATED GENES THAT ENCODE A NEW FAMILY OF ZINC-FINGER PROTEINS IN DROSOPHILA

The odd-skipped (odd) gene, which was identified on the basis of a pai r-rule segmentation phenotype in mutant embryos, is initially expresse d in the Drosophila embryo in seven pair-rule stripes, but later exhib its a segment polarity-like pattern for which no phenotypic correlate is apparent. We have molecularly characterized two embryonically expre ssed odd-cognate genes, sob and bowel (bowl), that encode proteins wit h highly conserved C2H2 zinc fingers. While the Sob and Bowl proteins each contain five tandem fingers, the Odd protein lacks a fifth (C-ter minal) finger and is also less conserved among the four common fingers . Reminiscent of many segmentation gene paralogues, the closely linked odd and sob genes are expressed during embryogenesis in similar strip ed patterns; in contrast, the less-tightly linked bowl gene is express ed in a distinctly different pattern at the termini of the early embry o. Although our results indicate that odd and sob are more likely than bowl to share overlapping developmental roles, some functional diverg ence between the Odd and Sob proteins is suggested by the absence of h omology outside the zinc fingers, and also by amino acid substitutions in the Odd zinc fingers at positions that appear to be constrained in Sob and Bowl.