Characterization of lethal Drosophila melanogaster alpha-actinin mutants.

We have partially characterized four Drosophila melanogaster alpha-actinin gene mutants, I(1)2Cb1, I(1)2Cb2, I(1)2Cb4, and I(1)2Cb5. We demonstrate that in each case the mutation is caused by a chromosomal rearrangement that precludes normal protein synthesis. In the absence of alpha-actinin, flies complete embryogenesis and develop into flaccid larvae that die within approximately 24 hr.

Functional nonequivalence of Drosophila actin isoforms.

We show that different Drosophila actin isoforms are not interchangeable. We sequenced the six genes that encode conventional Drosophila actins and found that they specify amino acid replacements in 27 of 376 positions. To test the significance of these changes we used directed mutagenesis to introduce 10 such conversions, independently, into the Act88F flight muscle-specific actin gene.

A family of Drosophila genes encoding quaking-related maxi-KH domains.

We recently identified a Drosophila gene, wings held out (who), that specifies a STAR (signal transduction and RNA activation) protein expressed within mesoderm and muscles. Genetic evidence suggests that WHO regulates muscle development and function in response to steroid hormone titer. who is related to the mouse quacking gene, essential for embryogenesis and neural myelination, and gld-1, a nematode tumor suppressor gene necessary for oocyte differentiation, both of which contain RNA binding "maxi-KH" domains presumed to link RNA metabolism to cell signaling.

A Drosophila muscle-specific gene related to the mouse quaking locus.

We have characterized a novel muscle-specific gene of Drosophila melanogaster, defined by enhancer trap strain 24B of Brand and Perrimon (1993). We show that transcripts of the gene accumulate within presumptive mesoderm and persist within developing muscles, strongly suggesting that the encoded protein is involved in muscle cell determination and differentiation. cDNA sequences reveal that the Drosophila protein is similar to quaking (64% identity over 210 amino acids), a protein essential for mouse embryogenesis, and gld-1 (53% identity over 162 amino acids) a germ-line-specific tumor suppressing protein of the nematode, Caenorhabditis elegans.

Green fluorescent protein/beta-galactosidase double reporters for visualizing Drosophila gene expression patterns.

We characterized 120 novel yeast Ga14-targeted enhancer trap lines in Drosophila using upstream activating sequence (UAS) reporter plasmids incorporating newly constructed fusions of Aequorea victoria green fluorescent protein (GFP) and Escherichia coli beta-galactosidase genes. Direct comparisons of GFP epifluorescence and beta-galactosidase staining revealed that both proteins function comparably to their unconjugated counterparts within a wide variety of Drosophila tissues. Generally, both reporters accumulated in similar patterns within individual lines, but in some tissues, e.