Est6, Est, Est-D
Gene model reviewed during 5.46
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Est-6 using the Feature Mapper tool.
Est-6 transcripts are detected in all developmental stages, but are expressed at very high levels in adult males.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Est-6 in GBrowse 2
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
Source for identity of: Est-6 CG6917
Allelic variation in Est-6 is expressed in electrophoretic mobility (complicated by heterogeneity for m(Est-6) on chromosome 3), thermal stability and level of activity. The same alleles have been designated differently by different authors. The allele records attempt to define the equivalences. Some use electrophoretic mobility relative to that of Est-6S = 1.00 in designating alleles. Relative mobility estimates vary within and among gels; also relations between mobilities on starch and acrylamide are nonlinear; consequently, similar but not identical estimates may not represent real differences.
In a sample of 79 genes with multiple introns, 33 showed significant heterogeneity in G+C content among introns of the same gene and significant positive correspondence between the intron and the third codon position G+C content within genes. These results are consistent with selection adding against preferred codons at the start of genes.
Upstream regions of Est-6 (1,150bp) and Dpse\Est-5B (5,100bp and 1,224bp) genes confer different expression patterns on a reporter gene. Common sites of expression are the third antennal segment, maxillary palps and adult salivary glands. Deletion analysis reveals the genes have a different organisation of regulatory elements that control expression in conserved tissue locations. Results suggest that the conservation of the expression pattern of genes that evolved from a common ancestor is not necessarily accompanied by an evolutionary preservation of the corresponding cis-regulatory elements.
Ancestral activities in the haemolymph and ejaculatory bulb are directed by conserved sequences close to the transcription initiation site. The more recently acquired site of activity, the anterior ejaculatory duct, is directed by more distal sequences lying both 5' and 3' of the coding region. The 3' sequences appear to lie within the transcription unit of the adjacent Est-P gene.
The effects of mutations of the four N-linked glycosylation sites is investigated. the effects of the mutation on aspects of Est-6 biochemistry and reproductive biology.
Chromosome homologies of Muller's element D (J chromosome in the Paleartic species and XR chromosome arm in Nearctic species) and of element E (O chromosome in the Paleartic species and 2 chromosome in Nearctic species) have been confirmed by single copy probes in the species of the obscura group and in D.melanogaster.
Substantial heritable variation for larval and pupal Est-6 activity is detected among 17 third chromosome isoallelic lines extracted from a single natural population. Weak correlations between larval and pupal activity and between larval and adult female activity are found, with effectively negligible associations between larval and adult male activities and between pupal and either adult measure. There is a largely independent genetic control of variation in the four measures. A comparison of the nucleotide polymorphisms associated with the activity variation likewise indicates distinct genetic bases for the variation in the four measures.
Esterase-6 has been identified, on the basis of a partial N-terminal sequence, as one of the proteins recognised by anti-Horse Radish Peroxidase antibodies.
Patterns of Est-6 expression are broadly similar in D.melanogaster, D.simulans and D.mauritiana. The major differences are in newly eclosed female activities and in 5 day adults. The genetic basis of the observed quantitative differences between Dsim\Est-6, Dmau\Est-6 and Est-6 is assayed using germ line transformation and analysis reveals interspecific differences are due to cis- and trans-inherited factors contained within the transferred DNA.
Flies show a positive correlation between male reproductive activity and the activity of Est-6 in the male reproductive system.
Deletion mutant Ecol\lacZ fusions generated in vitro allow definition of four independently acting Est-6 regulatory regions in the 1132bp 5' to the translation initiation codon. These regions are responsible for expression in the ejaculatory duct, salivary glands, ejaculatory bulb and respiratory system, antennae and maxillary palps.
Site directed in vitro mutagenesis of position 187 suggests the residue interacts directly with the substrate alkyl group and this interaction is fully realised in the transition state.
Pattern of allele frequency has been studied for seven loci, Aph-3, Est-6, Adh, Fdh, Aldox-1, Gpdh and Mdh1, in wild Indian populations of D.melanogaster : the allelic frequency patterns do not agree with those from temperate region populations.
Extent of genetic variation at esterase-encoding loci in D.melanogaster, D.takahashii, D.nepalensis, D.malerkotliana, D.bipectinata and D.ananassae has been studied: all loci depict Fast/Slow migration on starch gel diallele variation patterns.
Comparison of CpG distribution in the coding region of 121 genes from six species supports the mCpG mutational hotspot explanation of CpG suppression in methylated species at position II-III and III-I.
No difference in allele fixed in lines selected over 700 generations for high (negative) and low (positive) geotaxis.
Protein product identified as EST6 isozyme.
Tests of natural selection on Est-6 alleles demonstrate that a temperature- dependent heterozygote advantage may contribute to maintenance of the Est-6 polymorphism: heterozygotes of each sex produced more progeny at 18oC than 25oC.
Male derived Est-6 is initially transferred into the females reproductive tract but is translocated within minutes of the beginning of mating into the haemolymph. Seminal-fluid Est-6 is detected by Western blot analysis in mated female haemolymph for as long as 4 days after mating. Results suggest that the enzyme remains in females for a period long enough to account for many of its behavioural and physiological effects.
Allelic frequencies have been determined between European and African populations. African populations show a greater genetic diversity, as measured by the number of alleles found. Within each geographic group there is a homogeneity of allele frequencies.
The structural gene for the nonspecific carboxylesterase, (EST-6). One of the ten positively migrating esterases demonstrable with α-naphthyl acetate and Fast Blue BB after starch gel electrophoresis of homogenates. Molecular weight determinations on purified enzyme indicate that the active enzyme is a 62,000 to 65,000 dalton glycoprotein monomer (Mane et al., 1983). Substrate specificities to different esters explored by Danford and Beardmore (1979). Specific EST-6 activity during development shows a prominent transient peak during second larval instar and shows a male-specific rise in activity beginning 36-48 hr after eclosion; males reach level double that of females (Sheehan, Richmond and Cochrane, 1979); similar high levels found in male-like triploid intersexes (Aronshtam and Kuzin, 1974) and X/X;tra/tra (Johnson, 1964). High concentrations of EST-6 found in ejaculatory duct; at mating, male level depleted and female level enhanced; transfer of activity from male to Est-60 female detected early during copulation, prior to the transfer of sperm, indicating that EST-6 is a component of seminal fluid (Richmond, Gilbert, Sheehan et al., 1980). Enzyme levels in flies carrying different X chromosomes from natural populations in combination with constant autosomal complement vary suggesting X-linked modifiers (Tepper et al., 1981). In D.melanogaster X D.simulans hybrid males that carry a D.melanogaster X chromosome, the level of the D.melanogaster enzyme is reduced compared to that of the D.simulans enzyme; hybrid females have equivalent activities of the two enzymes (Korochkin et al., 1974). Electrophoretic mobility reduced modestly from 1.10 to 1.08 for Est-6F and from 1.0 to 0.98 for Est-6S by m(Est-6) on the third chromosome (Cochrane and Richmond, 1979a).
Wright, Aug. 1961.