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At least 235 records · Page 13Linked to original sources
PubMed1996

UVB irradiation upregulation of the Drosophila 1731 retrotransposon LTR requires the same short sequence of U3 region in a human epithelial cell line as in Drosophila cells.

Phylogenetic analysis of the retrotransposon and retrovirus suggests an evolutionary relationship between them and indicates that transactivation of the long terminal repeat (LTR)-containing retroelements could be ubiquitous. Using constructs expressing a reporter gene under the control of the entire or deleted LTR of 1731, which is a retrotransposable element of Drosophila melanogaster, we were able to show that the UVB-irradiation activation of the 1731-LTR requires the same short sequence of U3 region in a human epithelial cell line as in Schneider's Drosophila cell line (S2). This sequence is similar to the binding sequence of the members of the nuclear factor-kappa B (NF-kappa B)/rel family. In addition, human colonic carcinoma cells (HT29), in response to UVB-irradiation, produce some extracellular factor(s) that activates the 1731-LTR in nonirradiated cells.

Animals↗
PubMed1988

Drosophila S virus, a hereditary reolike virus, probable agent of the morphological S character in Drosophila simulans.

Isometric reolike virions were found in all the examined Drosophila simulans flies from two strains (SimES-st and Israel-st) presenting the S phenotype, a maternally inherited morphological trait (abnormalities of bristles). Normal flies of both strains appeared virus-free. Virions were found in the cytoplasm of male and female gonads and epidermal cells, including the bristle-forming cells, which appeared disorganized. Steps of virogenesis were described. A positive correlation was demonstrated between expressivity of the S phenotype and degree of viral infection. This hereditary reolike virus seems to be responsible for the S character of D. simulans and was named DSV (Drosophila S virus).

Animals↗
PubMed1990

Evolutionary implications of duplications and Balbiani rings in Drosophila. A study of Drosophila serrata.

Drosophila serrata, a species of subgroup montium, exhibits in its salivary-gland chromosomes a high number of inverted tandem duplications and a well-formed Balbiani ring. A photographic map, the duplications, and the Balbiani ring of this species are presented. Also presented are the most prominent puffs during normal larval development and after ecdysone treatment, as well as intercalary heterochromatin regions of the above chromosomes. These data are discussed and compared with those of Drosophila auraria, another species of subgroup montium. All the inverted tandem duplications found in both species are homozygous and are not accompanied by other types of chromosomal rearrangements. These results argue in favor of the relatively old origin of these structures. The similarity of the structure and the developmental profile of the Balbiani ring 1 in both species may indicate a necessary role served by the Balbiani ring 1 and hence its selection during evolution.

Animals↗
PubMed1991

No character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana.

To test whether character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana exists, the degree of sexual isolation was measured between their sympatric and allopatric populations. Although the isolation indices vary in different crosses, the average isolation index for sympatric populations is very close to that for allopatric populations. This shows no difference in the degree of sexual isolation between sympatric and allopatric populations of D. bipectinata and D. malerkotliana. Thus there is no evidence for the existence of character displacement for sexual isolation between these two closely related sympatric species.

Animals↗
PubMed2002

Ectopic expression of Drosophila ELAV and human HuD in Drosophila wing disc cells reveals functional distinctions and similarities.

Drosophila ELAV and human HuD are two neuronal RNA binding proteins that show remarkable sequence homology, yet differ in their respective documented roles in post-transcriptional regulation. ELAV regulates neural-specific alternative splicing of specific transcripts, and HuD stabilizes specific mRNAs that are otherwise unstable due to AU-rich elements (AREs) in their 3' untranslated region (UTR). AREs are major determinants of transcript stability in mammalian cells. The role of each of these proteins was investigated and compared, by ectopically expressing them in Drosophila imaginal wing disc cells, which lack endogenous expression of either protein. The effect of the ectopic expression of ELAV and HuD was assessed on two sets of green fluorescent protein reporter transgenes, which were all driven with a broadly expressing promoter. Each set consisted of three reporter transgenes: (1) with an uninterrupted open reading frame (ORF); (2) with a constitutively spliced intron inserted into the ORF; and (3) with the intron nASI whose splicing is regulated in neurons by ELAV, inserted into the ORF. The two sets differed from each other only in their 3'UTR: Heat-shock-protein-70Ab (Hsp70Ab) trailer with ARE-like characteristics or Actin 5C (Act5C) trailer. Our results show that: (1) both ectopically expressed ELAV and HuD can enhance expression of transgenes with the Hsp70Ab 3'UTR, but not of transgenes with Act5C 3'UTR; (2) this enhancement is accompanied by an increase in mRNA level; (3) only ELAV can induce neural-specific splicing of nASI; and (4) although HuD is localized primarily to the cytoplasm, ELAV is localized to both the cytoplasm and the nucleus.

3' Untranslated Regions↗
PubMed1990

[The effect of sterol metabolism in a model ecological system Drosophila-yeasts on the crossing-over in Drosophila].

The absence of sterols available for metabolism causes the death of Drosophila larva. Addition of suboptimal cholesterol doses to this medium allows the portion of larvae to survive. Sterol-deficient diet at the preimaginal stages leads to suppression of both spontaneous and high-temperature induced crossingover in Drosophila females. Two possible explanations for dependence of recombination process on sterol metabolism are suggested: 1) the shortage of precursor for ecdisons biosynthesis was the cause of discordance of meiotic events; 2) suppression of crossingover occurs, due to alteration of cell membrans' structure.

Animals↗
PubMed1993

[Drosophila beta-heterochromatin: molecular organization and function. Cloning and molecular biological analysis of the lambda 20 DNA fragment from Drosophila melanogaster beta-heterochromatin].

To isolate the DNA sequences specific for the pericentric heterochromatin of Drosophila we used two CREST-autoimmune sera which bind in the Western-blot analysis the nuclear antigens of 30 kDa, 43 kDa and 45 kDa molecular weight. Cloning of the DNA fragments associated with these CREST-specific proteins of Drosophila resulted in obtaining 8 clones. One of them, lambda 20, hybridized mainly to the chromomcenter of polytene chromosomes. The further analysis indicated that the lambda 20 DNA might belong to the proximal beta-heterochromatin of the polytene chromosomes of D. melanogaster.

Animals↗
PubMed1998

Accumulation of transposable elements in the heterochromatin and on the Y chromosome of Drosophila simulans and Drosophila melanogaster.

The elements of the transposon families G, copia, mdg 1, 412, and gypsy that are located in the heterochromatin and on the Y chromosome have been identified by the Southern blotting technique in Drosophila simulans and D. melanogaster populations. Within species, the abundance of such elements differs between transposon families. Between species, the abundance in the heterochromatin and on the Y chromosome of the elements of the same family can differ greatly suggesting that differences within a species are unrelated to structural features of elements. By shedding some new light on the mechanism of accumulation of transposable elements in the heterochromatin, these data appear relevant to the understanding of the long-term interaction between transposable elements and the host genome.

Animals↗
PubMed1994

Regulatory and coding regions of the segmentation gene hunchback are functionally conserved between Drosophila virilis and Drosophila melanogaster.

The segmentation gene hunchback (hb) is involved in setting up the anterior-posterior axis of the Drosophila embryo. It is expressed maternally and zygotically and it plays a key role in integrating the effects of the anterior and posterior maternal systems. The hb gene from D. virilis has previously been cloned and was shown to be well conserved in its coding region, but less so in its upstream region which shows a more patchy pattern of conserved and diverged sequences. This work deals with the functional conservation of hb between the two species. We have mapped two additional regulatory elements for the expression of hb in the early embryo, namely the enhancer for the maternal expression and the enhancer region for the late blastoderm expression. Fragments containing these two elements, the previously identified bicoid dependent element for the early blastoderm expression of hb and the coding region were taken from D. virilis and tested in the D. melanogaster background. We find that all enhancer elements as well as the coding region are functionally conserved between the two species. Comparison of the upstream sequences that include the enhancer region for the late blastoderm expression reveal seven highly conserved blocks. Some of these contain consensus binding sites for transregulatory factors that are likely to control the respective expression domains.

Amino Acid Sequence↗
PubMed1998

The pore-forming and cytoplasmic domains of the neurogenic gene product, BIG BRAIN, are conserved between Drosophila virilis and Drosophila melanogaster.

The Drosophila BIG BRAIN (BIB) protein functions critically in the determination of neuroblasts in the embryonic ectoderm and many other cell types. BIB is a member of the MIP family of transmembrane channel proteins. The conserved channel domain of BIB is flanked by amino- and carboxy-terminal cytoplasmic domains of unique sequence, which comprise over two-thirds of the protein. To determine whether the cytoplasmic domains of BIB are important for BIB function, we have cloned and sequenced the bib gene of D. virilis and compared it with that of D. melanogaster. Here we report that the channel domain and both cytoplasmic domains are highly conserved between the two species. The conservation of the cytoplasmic domains indicates that they are critical to BIB function. bib transcripts are found in similar patterns in both species, indicating that the developmental function(s) of BIB have also been conserved.

Amino Acid Sequence↗
PubMed1999

Nucleotide variation at the runt locus in Drosophila melanogaster and Drosophila simulans.

Intra- and interspecific nucleotide variation for the major developmental gene runt in Drosophila was studied in D. melanogaster and D. simulans. The 1.5-kb protein-coding region and the 0.4-kb intron of the runt gene were sequenced for 11 alleles in each species. The D. melanogaster alleles originated from east Africa. Estimated parameters of intraspecific variation in D. melanogaster (exons: theta = 0.018, pi = 0.018; intron: theta = 0.014, pi = 0.014) and D. simulans (exons: theta = 0.007, pi = 0.005; intron: theta = 0.008, pi = 0.005) were below average for other X-linked genes, while divergence between species (exons: D = 0.094; intron: D = 0.069) fell within the normal range for both silent and replacement changes. This estimate for runt, along with published values for three other genes in regions of normal recombination, show east African D. melanogaster to be roughly twice as polymorphic as D. simulans. The majority of nucleotide variation, silent and replacement, in both species was found to be selectively neutral using various statistical tests (HKA, McDonald-Kreitman, Tajima, and Fu and Li tests). Monte Carlo simulations of the coalescent process significantly rejected a Wright-Fisher model with respect to an amino acid polymorphism and the distribution of polymorphic sites among the D. simulans lines. This indicated an old lineage and may reflect ancestral population substructuring in D. simulans.

Alleles↗
PubMed1965

INTERFERENCE BETWEEN "SEX-RATIO" AGENTS OF DROSOPHILA WILLISTONI AND DROSOPHILA NEBULOSA.

Interference between two "sex-ratio" agents-that is, treponemalike spirochetes-of different origin, one from Drosophila willistoni and the other from D. nebulosa, was demonstrated by experiments in vivo and in vitro. When the two sex-ratio agents were combined in females of the Oregon-R strain of D. melanogaster, expression of the sex-ratio condition was temporarily interrupted. Several lines of evidence indicate that a substance produced by the sex-ratio agent of D. nebulosa may kill or incapacitate the sex-ratio agent of D. willistoni.

Animals↗
PubMed2005

Comparison of the oxidative phosphorylation (OXPHOS) nuclear genes in the genomes of Drosophila melanogaster, Drosophila pseudoobscura and Anopheles gambiae.

BACKGROUND: In eukaryotic cells, oxidative phosphorylation (OXPHOS) uses the products of both nuclear and mitochondrial genes to generate cellular ATP. Interspecies comparative analysis of these genes, which appear to be under strong functional constraints, may shed light on the evolutionary mechanisms that act on a set of genes correlated by function and subcellular localization of their products. RESULTS: We have identified and annotated the Drosophila melanogaster, D. pseudoobscura and Anopheles gambiae orthologs of 78 nuclear genes encoding mitochondrial proteins involved in oxidative phosphorylation by a comparative analysis of their genomic sequences and organization. We have also identified 47 genes in these three dipteran species each of which shares significant sequence homology with one of the above-mentioned OXPHOS orthologs, and which are likely to have originated by duplication during evolution. Gene structure and intron length are essentially conserved in the three species, although gain or loss of introns is common in A. gambiae. In most tissues of D. melanogaster and A. gambiae the expression level of the duplicate gene is much lower than that of the original gene, and in D. melanogaster at least, its expression is almost always strongly testis-biased, in contrast to the soma-biased expression of the parent gene. CONCLUSIONS: Quickly achieving an expression pattern different from the parent genes may be required for new OXPHOS gene duplicates to be maintained in the genome. This may be a general evolutionary mechanism for originating phenotypic changes that could lead to species differentiation.

Animals↗
PubMed2000

Associations between female remating behavior, oogenesis and oviposition in Drosophila melanogaster and Drosophila pseudoobscura.

An association between female remating behavior, oogenesis and oviposition was examined in Drosophila melanogaster and Drosophila pseudoobscura to investigate mechanisms that elicit remating. Females receptive to remating oviposited more eggs in both species; however, the species differed in the association between remating behavior and the number and distribution of oocyte stages. We found no differences in the number of either developing eggs of different stages or mature eggs between female D. pseudoobscura that were either receptive or nonreceptive to remating. In contrast, D. melanogaster females that are receptive to remating had significantly more mature eggs in the ovaries than nonreceptive females. Nonremating females had a significantly greater number of immature, vitellogenic oocytes. These results suggest that factors associated with oogenesis are related to female remating behavior in D. melanogaster but not in D. pseudoobscura. We discuss these results in conjunction with other evidence on the role male ejaculatory components play in mediating female remating behavior.

Journal Article↗
PubMed2000

Characterization of defects in adult germline development and oogenesis of sterile and rescued female hybrids in crosses between Drosophila simulans and Drosophila melanogaster.

Crosses between Drosophila melanogaster and D. simulans normally result in progeny that are either inviable or sterile. Recent discovery of strains that rescue these inviability and sterility phenotypes has made it possible to study the developmental basis of reproductive isolation between these two species in greater detail. By producing both rescued and unrescued hybrids and examining the protein product staining patterns of genes known to be involved in early germline development and gametogenesis, we have found that in crosses between D. simulans and D. melanogaster, hybrid female sterility results from the improper control of primordial germline proliferation, germline stem cell maintenance, and cystoblast formation and differentiation during early oogenesis. Rescued hybrid females are fertile, yet they generally have lower amounts of adult germline from the outset and show a premature degeneration of adult germline cells with age. In addition, older rescued hybrid females also exhibit mutant egg phenotypes associated with defects in dorso-ventral patterning which may result from the improper partitioning of cytoplasmic factors during early oogenesis that could stem from the early defect. Although a variety of germline and oogenic defects are described for the hybrid females, all of them can potentially result from the same underlying primary defect. Hybrid males from these same crosses, on the other hand, have no detectable germline in adult reproductive tissues, even when hybrid sterility rescue strains are used, indicating that male sterility and female sterility stem from distinctly different developmental defects.

Animals↗
PubMed1991

Developmental stability in hybrids between the sibling species pair, Drosophila melanogaster and Drosophila simulans.

Drosophila melanogaster and its sibling species D.simulans were hybridized in the laboratory to test the hypothesis that developmental homeostasis in hybrids between two species having no prior gene flow would be significantly reduced. Developmental stability was assessed by measuring fluctuating asymmetry for three bilateral traits: sternopleural chaetae, wing length, and fronto-orbital plus frontal chaetae. Male F1 hybrids showed no decrease in developmental stability compared to males of parental species. Female hybrids showed significant fluctuating asymmetry compared to other flies. The results are discussed with respect to ideas about coadaptation and gene flow based upon previous studies of hybrid developmental stability.

Animals↗
PubMed1993

Nucleotide divergence of the rp49 gene region between Drosophila melanogaster and two species of the Obscura group of Drosophila.

A 2.1-kb SstI fragment including the rp49 gene and the 3' end of the delta-serendipity gene has been cloned and sequenced in Drosophila pseudoobscura. rp49 maps at region 62 on the tip of chromosome II of this species. Both the coding and flanking regions have been aligned and compared with those of D. subobscura. There is no evidence for heterogeneity in the rate of silent substitution between the rp49 coding region and the rate of substitutions in flanking regions, the overall silent divergence per site being 0.19. Noncoding regions also differ between both species by different insertions/deletions, some of which are related to repeated sequences. The rp49 region of D. pseudoobscura shows a strong codon bias similar to those of D. subobscura and D. melanogaster. Comparison of the rates of silent (Ks) and nonsilent (Ka) substitutions of the rp49 gene and other genes completely sequenced in D. pseudoobscura and D. melanogaster confirms previous results indicating that rp49 is evolving slowly both at silent and nonsilent sites. According to the data for the rp49 region, D. pseudoobscura and D. subobscura lineages would have diverged some 9 Myr ago, if one assumes a divergence time of 30 Myr for the melanogaster and obscura groups.

Amino Acid Sequence↗