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1.
Chromosomal homologies among the four palearctic Drosophila obscura group species D. ambigua, D. tristis, D. obscura, and D. subsilvestris and the "trans-palearctic" species D. bifasciata were established by in situ hybridization using the 5C actin gene of D. melanogaster as a probe. In all species two labeling sites were detected in each of chromosomal elements C and E and one in each of chromosomal elements A and D. In addition one labeling site was detected on element B for the species D. subsilvestris and D. bifasciata. The conservative distribution pattern of the genes of the actin multigene family, the similarities of the locations of the actin genes in the chromosomes of the five species studied, together with the concordant evidence of synteny of visible and other genetic markers as well as the similarities in banding patterns, all agree with the conclusion that the chromosomal elements have retained their essential identity throughout the evolution of these species. Using in situ hybridization detailed information of some homologous regions of chromosomes can also be established. 相似文献
2.
Conserved Alternative Splicing Patterns and Splicing Signals in the Drosophila Sodium Channel Gene Para 总被引:3,自引:1,他引:3
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We cloned genomic DNA corresponding to the Drosophila virilis homologue of para, a gene encoding a sodium channel α-subunit, and obtained many partial cDNA clones from embryos and adults. Para protein has been well conserved, and the optional elements at six different sites of alternative splicing in D. melanogaster are present in D. virilis, in addition to one new optional exon. Among 31 different splice-types observed in D. virilis, the stage-specific pattern of alternative splicing seen in D. melanogaster is also conserved. Comparison of genomic DNA sequence revealed three aspects that vary between alternatively and constitutively used exon sequences. Sixteen short blocks (10-75 bp), the only recognizably conserved intron sequence, were disproportionately associated with alternatively used splice sites. Silent site substitutions were found much less frequently in alternative than constitutive exon elements, and the degree of match to the Drosophila splice site consensus tended to be lower at less frequently selected alternative splice junctions. This study shows that the developmentally regulated variability of para products is highly conserved and therefore likely to be of functional significance and suggests that a variety of different sequence-dependent mechanisms may regulate this pattern of alternative splicing. 相似文献
3.
In Drosophila melanogaster, the apparently unrelated genes anon-66Da, RpL14, and anon-66Db (from telomere to centromere) are located on a 5547 bp genomic fragment on chromosome arm 3L at cytological position 66D8. The three genes are tightly linked, and flanked by two relatively large genes with unknown function. We have taken a comparative genomic approach to investigate the evolutionary history of the three genes. To this end we isolated a Drosophila virilis 7.3 kb genomic fragment which is homologous to a 5.5 kb genomic region of D. melanogaster. Both fragments map to Muller's element D, namely to section 66D in D. melanogaster and to section 32E in D. virilis, and harbor the genes anon-66Da, RpL14, and anon-66Db. We demonstrate that the three genes exhibit a high conservation of gene topography in general and in detail. While most introns and intergenic regions reveal sequence divergences, there are, however, a number of interspersed conserved sequence motifs. In particular, two introns of the RpL14 gene contain a short, highly conserved 60 nt long sequence located at corresponding positions. This sequence represents a novel Drosophila small nucleolar RNA, which is homologous to human U49. Whereas DNA flanking the three genes shows no significant interspecies homologies, the 3'-flanking region in D. virilis contains sequences from the transposable element Penelope. The Penelope family of transposable elements has been shown to promote chromosomal rearrangements in the D. virilis species group. The presence of Penelope sequences in the D. virilis 7.3 kb genomic fragment may be indicative for a transposon-induced event of transposition which did not yet scramble the order of the three genes but led to the breakdown of sequence identity of the flanking DNA. 相似文献
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Recent results indicate that the rate of chromosomal rearrangement in the genus Drosophila is the highest found so far in any eukaryote. This conclusion is based chiefly on the comparative mapping analysis of a single chromosomal element (Muller's element E) in two species, D. melanogaster and D. repleta, representing the two farthest lineages within the genus (the Sophophora and Drosophila subgenera, respectively). We have extended the analysis to two other chromosomal elements (Muller's elements A and D) and tested for differences in rate of evolution among chromosomes. With this purpose, detailed physical maps of chromosomes X and 4 of D. repleta were constructed by in situ hybridization of 145 DNA probes (gene clones, cosmids, and P1 phages) and their gene arrangements compared with those of the homologous chromosomes X and 3L of D. melanogaster. Both chromosomal elements have been extensively reshuffled over their entire length. The number of paracentric inversions fixed has been estimated as 118 +/- 17 for element A and 56 +/- 8 for element D. Comparison with previous data for elements E and B shows that there are fourfold differences in evolution rate among chromosomal elements, with chromosome X exhibiting the highest rate of rearrangement. Combining all results, we estimated that 393 paracentric inversions have been fixed in the whole genome since the divergence between D. repleta and D. melanogaster. This amounts to an average rate of 0.053 disruptions/Mb/myr, corroborating the high rate of rearrangement in the genus Drosophila. 相似文献
7.
Polytene chromosomes of Drosophila virilis were treated with AluI and HaeIII restriction endonucleases. Both enzymes were capable of extensively digesting chromosomal DNA, with the exception of some regions that contain repetitive DNAs. Moreover, a comparison was made between our data and the data already obtained with the same enzymes in D. melanogaster. On this basis, AluI digestion showed that the 5S RNA genes of D. virilis and D. melanogaster have different base composition, while digestion with HaeIII revealed resistance of the histone genes in D. virilis, contrary to what was previously found in D. melanogaster. 相似文献
8.
Components Acting in Localization of Bicoid mRNA Are Conserved among Drosophila Species 总被引:1,自引:1,他引:0
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Substantial insights into basic strategies for embryonic body patterning have been obtained from genetic analyses of Drosophila melanogaster. This knowledge has been used in evolutionary comparisons to ask if genes and functions are conserved. To begin to ask how highly conserved are the mechanisms of mRNA localization, a process crucial to Drosophila body patterning, we have focused on the localization of bcd mRNA to the anterior pole of the embryo. Here we consider two components involved in that process: the exuperantia (exu) gene, required for an early step in localization; and the cis-acting signal that directs bcd mRNA localization. First, we use the cloned D. melanogaster exu gene to identify the exu genes from Drosophila virilis and Drosophila pseudoobscura and to isolate them for comparisons at the structural and functional levels. Surprisingly, D. pseudoobscura has two closely related exu genes, while D. melanogaster and D. virilis have only one each. When expressed in D. melanogaster ovaries, the D. virilis exu gene and one of the D. pseudoobscura exu genes can substitute for the endogenous exu gene in supporting localization of bcd mRNA, demonstrating that function is conserved. Second, we reevaluate the ability of the D. pseudoobscura bcd mRNA localization signal to function in D. melanogaster. In contrast to a previous report, we find that function is retained. Thus, among these Drosophila species there is substantial conservation of components acting in mRNA localization, and presumably the mechanisms underlying this process. 相似文献
9.
The Drosophila virilis dopa decarboxylase gene is developmentally regulated when integrated into Drosophila melanogaster. 总被引:12,自引:1,他引:11
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The dopa decarboxylase gene (Ddc) has been isolated from Drosophila virilis and introduced into the germ-line of Drosophila melanogaster by P-element mediated transformation. The integrated gene is induced at the correct stages during development with apparently normal tissue specificity, indicating that cis-acting elements required for regulation are functionally conserved between the two species. A comparison of the DNA sequences from the 5' flanking regions reveals a cluster of small (8-16 bp) conserved sequence elements within 150 bp upstream of the RNA startpoint, a region required for normal expression of the D. melanogaster Ddc gene. 相似文献
10.
The drosophilid Zaprionus indianus due to its economical importance as an insect pest in Brazil deserves more investigation into its genetics. Its mitotic karyotype and a line-drawing map of its polytene chromosomes are already available. This paper presents a photomap of Z. indianus polytene chromosomes, which was used as the reference map for identification of sections marked by in situ hybridization with gene probes. Hybridization signals for Hsp70 and Hsr-omega were detected, respectively, in sections 34B and 32C of chromosome V of Z. indianus, which indicates its homology to the chromosomal arm 3R of Drosophila melanogaster and, therefore, to Muller's element E. The main signal for Hsp83 gene probe hybridization was in section 17C of Z. indianus chromosome III, suggesting its homology to arm 3L of D. melanogaster and to element D of Muller. The Ubi probe hybridized in sections 10C of chromosome II and 17A of chromosome III. Probably the 17A is the polyubiquitin locus, with homology to arm 3L of D. melanogaster and to the mullerian D element, as suggested also by Hsp83 gene location. The Br-C gene was mapped in section 1D, near the tip of the X chromosome, indicating its homology to the X chromosome of D. melanogaster and to mullerian element A. The Dpp gene probe hybridized mainly in the section 32A of chromosome V and, at lower frequencies to other sections, although no signal was observed as expected in the correspondent mullerian B element. This result led to the suggestion of a rearrangement including the Dpp locus in Z. indianus, the secondary signals possibly pointing to related genes of the TGF-beta family. In conclusion, the results indicate that chromosomes X, III, V of Z. indianus are respectively correspondents to elements A, D, and E of Muller. At least chromosome V of Z. indianus seems to share synteny with the 3R arm of D. melanogaster, as indicated by the relative positions of Hsp70 and Hsr-omega, although the Dpp gene indicates a disruption of synteny in its distal region. 相似文献
11.
Structural and functional conservation of the Drosophila doublesex splicing enhancer repeat elements. 总被引:2,自引:0,他引:2
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We have compared the RNA sequences and secondary structures of the Drosophila melanogaster and Drosophila virilis doublesex (dsx) splicing enhancers. The sequences of the two splicing enhancers are highly divergent except for the presence of nearly identical 13-nt repeat elements (six in D. melanogaster and four in D. virilis) and a stretch of nucleotides at the 5' and 3' ends of the enhancers. In vitro RNA structure probing of the two enhancers revealed that the 13-nt repeats are predominantly single-stranded. Thus, both the primary sequences and single-stranded nature of the repeats are conserved between the two species. The significance of the primary sequence conservation was demonstrated by showing that the two enhancers are functionally interchangeable in Tra-/Tra2-dependent in vitro splicing. In addition, inhibition of splicing enhancer activity by antisense oligonucleotides complementary to the repeats demonstrated the importance of the conserved single-stranded structure of the repeats. In vitro binding studies revealed that Tra2 interacts with each of the D. melanogaster repeat elements, except for repeat 2, with affinities that are indistinguishable, whereas Tra binds nonspecifically to the enhancer. Taken together, these observations indicate that the organization of sequences within the dsx splicing enhancers of D. melanogaster and D. virilis results in a structure in which each of the repeat elements is single-stranded and therefore accessible for specific recognition by the RNA-binding domain of Tra2. 相似文献
12.
A 9.6 kb intervening sequence in D. virilis rDNA, and sequence homology in rDNA interruptions of diverse species of Drosophila and other diptera. 总被引:19,自引:0,他引:19
A large proportion of the 28S ribosomal RNA genes in Drosophila virilis are interrupted by a DNA sequence 9.6 kilobase pairs long. As regards both its presence and its position in the 28S gene (about two thirds of the way in), the D. virilis rDNA intervening sequence is similar to that found in D. melanogaster rDNA, but lengths differ markedly between the two species. Degrees of nucleotide sequence homology have been detected bewteen rDNA interruptions of the two species. This homology extends to putative rDNA intervening sequences in diverse higher diptera (other Drosophila species, the house fly and the flesh fly), but hybridization of cloned D. melanogaster and D. virilis rDNA interruption segments to DNA of several lower diptera has been negative. As is the case with melanogaster rDNA interruptions, segments of the virilis rDNA intervening sequence hybridize with non-rDNA components of the virilis genome, and interspecific homology may involve these non-rDNA sequences as well as rDNA interruptions. There is, however, evidence from buoyant density fractionation of DNA that the distributions of interruption-related sequences are distinct in D. melanogaster and D. virilis genomes. Moreover, thermal denaturation studies have indicated differing extents of homology between hybridizable sequences in D. virilis DNA and different segments of the D. melanogaster rDNA intervening sequence. We infer from our studies that rDNA intervening sequences are prevalent among higher diptera; that in the course of the evolution of these organisms, elements of the intervening sequences have been moderately to highly conserved; and that this conservation extends in at least two distantly related species of Drosophila to similar sequences found elsewhere in the genomes. 相似文献
13.
(dC-dA)n.(dG-dT)n sequences have evolutionarily conserved chromosomal locations in Drosophila with implications for roles in chromosome structure and function. 总被引:21,自引:2,他引:19
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In situ hybridization of (dC-dA)n.(dG-dT)n to the polytene chromosomes of Drosophila melanogaster reveals a clearly non-random distribution of chromosomal sites for this sequence. Sites are distributed over most euchromatic regions but the density of sites along the X chromosome is significantly higher than the density over the autosomes. All autosomes show approximately equal levels of hybridization except chromosome 4 which has no detectable stretches of (dC-dA)n.(dG-dT)n. Another striking feature is the lack of hybridization of the beta-heterochromatin of the chromocenter. The specific sites are conserved between different strains of D. melanogaster. The same overall chromosomal pattern of hybridization is seen for the other Drosophila species studied, including D. simulans, a sibling species with a much lower content of middle repetitive DNA, and D. virilis, a distantly related species. The evolutionary conservation of the distribution of (dC-dA)n.(dG-dT)n suggests that these sequences are of functional importance. The distribution patterns seen for D. pseudoobscura and D. miranda raise interesting speculations about function. In these species a chromosome equivalent to an autosomal arm of D. melanogaster has been translocated onto the X chromosome and acquired dosage compensation. In each species the new arm of the X also has a higher density of (dC-dA)n.(dG-dT)n similar to that seen on other X chromosomes. In addition to correlations with dosage compensation, the depletion of (dC-dA)n.(dG-dT)n in beta-heterochromatin and chromosome 4 may also be related to the fact that these regions do not normally undergo meiotic recombination. 相似文献
14.
Drosophila melanogaster DPKQDFMRFamide was isolated and its expression reported. Distribution of DPKQDFMRFamide immunoreactivity is now described in Drosophila virilis. DPKQDFMRFamide antibody stained a cell in the subesophageal ganglion in embryo. DPKQDFMRFamide antibody stained cells in the superior protocerebrum, subesophageal ganglion, thoracic ganglia, and an abdominal ganglion in larva, pupa, and adult. DPKQDFMRFamide antibody stained an additional pair of cells in the optic lobe and a cell in the lateral protocerebrum in adult. Structure identity and similar distribution of DPKQDFMRFamide in D. virilis and D. melanogaster, two distantly related Drosophila species, suggests an important and conserved activity for the peptide. 相似文献
15.
The phylogenetic distribution of transposable families, P, gypsy, hobo, I, and mariner has been analyzed in 33 species of
11 groups of neotropical Drosophila and a Drosophilidae species Zygotrica vittimaculosa, using squash blot and dot blot. Genomic
DNA of almost all neotropical species tested hybridized with gypsy probe and some species showed a particularly strong hybridization
signal, as D. gaucha, D. virilis, and species of flavopilosa group. The hobo element was restricted to melanogaster group
and some strains of D. willistoni. Only D. simulans DNA showed hybridization to mariner probe in all species tested and D.
simulans and D. melanogaster showed hybridization with I element probe. P element homologous sequence was present in D. melanogaster
and all species and strains of the willistoni and saltans groups tested. The presence of at least one P-homologous sequence
was detected in Drosophila mediopunctata. This one was the only P-bearing species of all six tested from the tripunctata group.
Four different pairs of primers homologous to segments of the canonical sequence of D. melanogaster's P were used to amplify
specific sequences from D. mediopunctata DNA, showing the occurrence of seemingly well-conserved P-homologous sequences.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
The mobile element ZAM, recently identified in Drosophila melanogaster, is similar in structure and coding potential to vertebrate
retroviruses. In this paper, we analyze the insertional and structural polymorphism of this element and show that members
of this family appear to have a long evolutionary history in the genome of Drosophila. It is present in all the species of
the D. melanogaster subgroup and in more distantly related species like D. takahashii, D. ananassae, or D. virilis but in
a lower copy number or with a lower homology. Two categories of strains have been previously identified in D. melanogaster:
strains with a high copy number of ZAM and strains with a low copy number. Here, we show that ZAM is at least in a low copy
number in each tested strain of the species analyzed. The study of ZAM's genomic distribution by FISH mapping analysis to
salivary gland polytene chromosomes or on mitotic chromosomes indicates that most of the insertion sites of ZAM elements are
associated with the constitutive heterochromatin regardless of the ZAM copy number. In addition, our results suggest that
multiple ZAM elements are present at the insertion sites visualized by in situ experiments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
Distribution and conservation of sequences homologous to the 1731 retrotransposon in Drosophila 总被引:3,自引:1,他引:2
Montchamp-Moreau C; Ronsseray S; Jacques M; Lehmann M; Anxolabehere D 《Molecular biology and evolution》1993,10(4):791-803
The distribution of 1731 retrotransposon-hybridizing sequences in the
family Drosophilidae has been studied using a 1731 probe from Drosophila
melanogaster. Squash blot and Southern blot analyses of 42 species reveal
that the 1731 sequences are widespread within both the Sophophora and
Drosophila subgenera and are also present in the genera Scaptomyza and
Zaprionus. Hence the 1731 retrotransposon family appears to have a long
evolutionary history in the Drosophilidae genome. Differences of
hybridization signal intensity suggested that the 1731 sequence is well
conserved only in the three species most closely related to D. melanogaster
(D. simulans, D. mauritiana, and D. sechellia). A survey of insertion sites
in numerous different populations of the previous four species by in situ
hybridization to polytene chromosomes has shown in all cases both
chromocentric hybridizations and a low number of sites (0-5) on the
chromosomal arms. This number of sites is among the lowest observed in D.
melanogaster and D. simulans when 1731 is compared with other
retrotransposon families. In addition, we have observed species-specific
patterns of the chromocentric hybridization signal, suggesting rapid
modifications of the beta-heterochromatin components since the radiation of
the melanogaster subgroup.
相似文献
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Berloco M Fanti L Sheen F Levis RW Pimpinelli S 《Cytogenetic and genome research》2005,110(1-4):124-133
Drosophila melanogaster telomeres contain arrays of two non-LTR retrotransposons called HeT-A and TART. Previous studies have shown that HeT-A- and TART-like sequences are also located at non-telomeric sites in the Y chromosome heterochromatin. By in situ hybridization experiments, we mapped TART sequences in the h16 region of the long arm close to the centromere of the Y chromosome of D. melanogaster. HeT-A sequences were localized in two different regions on the Y chromosome, one very close to the centromere in the short arm (h18-h19) and the other in the long arm (h13-h14). To assess a possible heterochromatic location of TART and HeT-A elements in other Drosophila species, we performed in situ hybridization experiments, using both TART and HeT-A probes, on mitotic and polytene chromosomes of D. simulans, D. sechellia, D. mauritiana, D. yakuba and D. teissieri. We found that TART and HeT-A probes hybridize at specific heterochromatic regions of the Y chromosome in all Drosophila species that we analyzed. 相似文献