Biomedical subjects

R G Rowan

Publications and source records attributed to R G Rowan.

4 recordsLinked to original sources

PubMed1991

Rates of DNA change and phylogeny from the DNA sequences of the alcohol dehydrogenase gene for five closely related species of Hawaiian Drosophila.

The sequence of 1.6 kb of DNA surrounding the alcohol dehydrogenase (Adh) gene from five species of the Planitibia subgroup of the Hawaiian picture-winged Drosophila, with estimated divergence times of 0.4-5.1 Myr, has been determined. The gene trees which were found by using the sequence divergence from different regions of the sequences are generally in accord with the phylogeny proposed for these species when chromosomal inversions and island of origin are used. One of the species (D. picticornis) appears to be more distant from the other species in this group than they are from a member of the Grimshawi group (D. affinidisjuncta) which is chromosomally more distant. Two of the species (D. differens and D. plantibia) show heterogeneity in the nucleotide changes in the Adh coding region, heterogeneity which is interpreted to be due to a gene conversion or recombination after hybridization between the two species. The minimal rate of nucleotide substitution of synonymous nucleotides and of nontranscribed nucleotides downstream from the coding region is estimated as 1.5 x 10(-8) and 1.1 x 10(-8) substitutions/nucleotide/year, respectively. This rate is two to three times the maximal rate estimated for mammalian synonymous substitutions.

Alcohol Dehydrogenase↗

PubMed1986

Developmentally regulated RNA transcripts coding for alcohol dehydrogenase in Drosophila affinidisjuncta.

The organization of the gene coding for alcohol dehydrogenase (Adh) in Drosophila affinidisjuncta has been determined by physically mapping Adh RNA transcripts to cloned genomic DNA. Two distinct transcript types accumulate with developmental specificity. Because only a single genomic Adh locus is detected in D. affinidisjuncta, and since all Adh transcripts appear to be identical except at their termini, the two Adh RNA types are products of the same gene. One type of transcript, abundant in adults, contains a small 5' terminal exon that is completely lacking in the other type of transcript, which accumulates in larvae. This 5' end difference suggests that the D. affinidisjuncta Adh gene, like the homologous gene from the distantly related species D. melanogaster, is expressed from two promoters. According to the transcription map, these D. affinidisjuncta promoters are separated by approximately 560 base pairs of genomic DNA sequence. D. affinidisjuncta Adh transcripts also resemble D. melanogaster Adh transcripts in both their overall organization and their developmental distribution. Multiple 3' ends are responsible for the size heterogeneity of both types of D. affinidisjuncta Adh RNA, and some of these also appear with stage specificity.

Alcohol Dehydrogenase↗

PubMed1986

Two alternative transcripts coding for alcohol dehydrogenase accumulate with different developmental specificities in different species of picture-winged Drosophila.

Two alternate transcripts of the single copy Alcohol dehydrogenase (Adh) gene accumulate with developmental specificity in all of 12 species of Hawaiian picture-winged Drosophila which have been examined. Relative to the paradigm species D. affinidisjuncta, the Adh transcript normally restricted to larvae is found to accumulate in both larval and adult tissues in D. formella. The other Adh transcript, which normally accumulates only in adults, accumulates in third-instar D. prostopalpis larvae as well. In species hybrids, the D. formella phenotype shows additive inheritance. These observations document the existence of a novel type of genetic variability. Furthermore, such variants suggest specific properties for the biological systems that regulate ADH expression in Drosophila, and they should facilitate further experimental investigations.

Alcohol Dehydrogenase↗

PubMedDate not supplied

Nucleotide sequence of the genomic region encoding alcohol dehydrogenase in Drosophila affinidisjuncta.

The DNA sequence of a 3886-bp genomic region containing the alcohol dehydrogenase (Adh) gene from Drosophila affinidisjuncta, and the RNA sequences of the D. affinidisjuncta Adh transcripts, are presented. These data support the conclusion that two Adh promoters generate distinct, developmentally regulated Adh transcripts. Correlations between these sequences and the transcription map are discussed. Comparisons between these and equivalent data from D. melanogaster are also presented. We note the following observations: (1) Except at the extreme 3' end, the two genes are identically organized. (2) Drosophila Adh protein accumulates amino acid replacements at the rate of approximately 0.5 per million years. (3) Among the non-protein-coding DNA sequences, putative homologies occur in the two promoter regions.

Alcohol Dehydrogenase↗