THE ACTIN GENE FAMILY IN THE ORIENTAL FRUIT-FLY BACTROCERA-DORSALIS -MUSCLE-SPECIFIC ACTINS

The actin protein is a critical protein in eurkaryotic cells. Four act in genes, constituting what appear to be a set of muscle specific acti n genes, have been isolated from the genome of the oriental fruit fly Bactrocera dorsalis. DNA sequences have been determined for the coding as well as 3' and 5' flanking regions for each of these genes. These genes have also been characterized in terms of RNA expression patterns , and comparisons have been made to actin genes from other species. Co nsistent with other actins, there is a high degree of amino acid seque nce conservation in the coding regions of these genes. However, even w ithin the coding regions codon usage patterns in the oriental fruit fl y are quite different from some other well characterized species. In a ddition, the DNA sequences in the intermediate 3' and 5' flanking regi ons exhibit virtually no detectable sequence homology both within and between species. In terms of introns, three of the four actin genes fr om the oriental fruit fly described here have a single intervening seq uence. Two of these genes share the same intron position with the two muscle specific actin genes act79B and act88F from Drosophila melanoga ster and with one muscle specific actin gene CcA1 from the Mediterrane an fruit fly, Ceratitis capitata. Another gene from the oriental fruit fly shares the same intron position as the muscle specific actin gene act57B from D. melanogaster, Such conservation of intron positioning between species is highly unusual among previously characterized actin genes. Using unique sequences found in the 3' untranslated regions, g ene specific probes have also been constructed. These have been used t o detect the expression patterns of individual genes in a temporal and spatial manner. Each of the four genes examined here show differentia l patterns of expression. The patterns indicate that all four genes ar e most likely to encode muscle specific actins.