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PubMedDate not supplied

[Genetic structure of mobile elements of the "Penelope" family in closely related Drosophila species].

Genomic libraries were obtained from species belonging to the "virilis" group of Drosophila. Several copies of Penelope elements were isolated from these libraries by using a D. virilis Penelope clone as a probe. The elements were sequenced, and their structure was determined. The geographical distribution of this family of mobile elements in closely related species of the group was studied in detail. Cytological localization of the elements was also carried out. The high variability observed between different copies of Penelope is probably due to recombination between individual copies. The role of these elements in the evolution of closely related species is discussed.

Animals↗
PubMedDate not supplied

[Description of the new species Anopheles artemievi sp.n. (Diptera, Culicidae)].

The paper describes the new species Anopheles artemievi belonging to a complex of the species maculipennis that may play an important role in the transmission of malaria in both the Fergana area and the Fergana valley. In terms of the morphological signs of imagoes, larvae, and the composition of the egg exochorion, the new species is the twin of An. sacharovi Favre and An. mihrtinius Shingarev. According to the pattern of polytene chromosomal disks, the described type is identical to An. maculipennis Meigen. The structure of the second internal transcribed spacer (ITS2) of a cluster of ribosomal genes in An. artemievi is species-specific and, in its nucleotide composition, differs from that in related species. The sequence of ITS2 in the new species has been registered at the GeneBank under No. AJ849886 and it is 419 p.n. The length of ITS2 in An. maculipennis and A. martinius is equal to 422 p.n. (AY238435) and 447 p.n. (AJ849885), respectively. The sequences of ITS in An. artemievi and An. maculipennis are 91% homologous; those in An. artemievi and An. martinius are 87% homologous. The nucleotide composition of ITS2 in An. artemievi differs from that in An. maculipennis in three deletions, 1 insertion, and 18 point substitutions and from that in An. martinius in 12 insertions, 2 deletions, and 40 point substitutions. The standard-type series is as follows: Kyrghyzstan, Batkensk Region, Leileksky district, Alga settlement, a cowshed, 1 male-holotype, l female-allotype. The paratypes are 2 males, 6 females.

Animals↗
PubMed2005

[The M/SAR elements of the bithorax complex in Drosophila melanogaster].

The bithorax (BX) complex of Drosophila is a complex polygenic region with a multifactorial system of regulation. One of the levels of the regulatory system of the BX complex is its association with the nuclear skeleton structures through a specific interaction of the M/SAR DNA with the nuclear matrix proteins. In the present work, M/SAR elements were mapped on the molecular-genetic map of the region. All of the elements examined were found to colocalize with regulatory elements and form clusters that restrict/bracket the genetically active domains. All M/SAR DNA revealed was shown to bins specifically to the purified Drosophila melanogaster lamin.

Animals↗
PubMed1987

Cytotaxonomy of the Simulium sanctipauli sub-complex in Liberia.

Larvae of the Simulium sanctipauli sub-complex from three of the main rivers of Liberia, the Lofa, the St. Paul and the Farmington were examined. All larvae were identified as S. sanctipauli (sensu Vajime and Dunbar, 1975) but as S. soubrense using the new definition of Post (1986). It therefore appears that S. soubrense (sensu Post) and not S. sanctipauli is the main man-biting species of the S. sanctipauli sub-complex in Liberia. Larval populations from the three rivers were genetically distinct. Those from the Lofa and St. Paul were most closely related, but the double inversion 1L-B.C. which was in Hardy-Weinberg equilibrium in the Lofa at a frequency of 0.578 was absent in the St. Paul. An abrupt genetical change was observed between the populations of the St. Paul and Farmington, which are only about 30 to 40 km away from each other. The inversion 2L-D, which was fixed and present in more than 90% of specimens from the Lofa and St. Paul respectively, was practically absent in the Farmington. Of further interest was the sex-linkage of inversion 3L-5 in the Lofa and the St. Paul. This inversion was autosomal and rare in the Farmington.

Animals↗
PubMed1995

[Interaction between genes Mos and mwh expressed in somatic cells of Drosophila melanogaster].

Gene Mosaic (Mos) of chromosome 3 of Drosophila melanogaster was located by means of dominant markers Ly, Sb, and Dr. This gene was shown to be located between Ly and Sb in the centromeric region (45-50 map units). An analysis of interaction between Mos and mwh genes in cis and trans-heterozygotes showed a significant effect of the Mos gene on mutability (recombinogenesis) of chromosome mwh in somatic cells. In the cis heterozygote mwh Mos/++, the frequency of small mutant clones on wings of flies increased. In mwh/Mos heterozygotes, the Mos gene caused a significant reduction of dorsocentral and scutellar bristles (78% in mwh/Mos, 85% in mwh +/+ Mos, and 98% in mwh Mos/mwh +).

Animals↗
PubMed1994

Structure, expression and duplication of genes which encode phosphoglyceromutase of Drosophila melanogaster.

We report here the isolation and characterization of genes from Drosophila that encode the glycolytic enzyme phosphoglyceromutase (PGLYM). Two genomic regions have been isolated that have potential to encode PGLYM. Their cytogenetic localizations have been determined by in situ hybridization to salivary gland chromosomes. One gene, Pglym78, is found at 78A/B and the other, Pglym87, at 87B4,5 of the Drosophila polytene map. Pglym78 transcription follows a developmental pattern similar to other glycolytic genes in Drosophila, i.e., substantial maternal transcript deposited during oogenesis; a decline in abundance in the first half of embryogenesis; a subsequent increase in the second half of embryogenesis which continues throughout larval life; a decline in pupae and a second increase to a plateau in adults. This transcript has been mapped by cDNA and genomic sequence comparison, RNase protection, and primer extension. Using similar analyses transcripts of Pglym87 could not be detected. Pglym78 has two introns which interrupt the coding region, while the Pglym87 gene lacks introns. This and other features support a model of retrotransposition mediated gene duplication for the origin of Pglym87. The apparent absence of a complete, intact coding frame and transcript suggest that Pglym87 is a pseudogene. However, retention of reading frame and codon bias suggests that Pglym87 may retain coding function, or may have been inactivated recently, substantially after the time of duplication, or that the molecular evolution of Pglym87 is unusual. Similarities of the unusual molecular evolution of Pglym87 and other proposed pseudogenes are discussed.

Amino Acid Sequence↗
PubMed1996

Developmental timing and tissue specificity of heterochromatin-mediated silencing.

Heterochromatic position-effect variegation (PEV) describes the mosaic phenotype of a euchromatic gene placed next to heterochromatin. Heterochromatin-mediated silencing has been studied extensively in Drosophila, but the lack of a ubiquitous reporter gene detectable at any stage has prevented a direct developmental characterization of this phenomenon. Current models attribute variegation to the establishment of a heritable silent state in a subset of the cells and invoke differences in the timing of silencing to explain differences in the patch size of various mosaic patterns. In order to follow the course of heterochromatic silencing directly, we have generated Drosophila lines variegating for a lacZ reporter that can be induced in virtually all cells at any developmental stage. Our data indicate that silencing begins in embryogenesis and persists in both somatic and germline lineages. A heterogeneity in the extent of silencing is also revealed; silencing is suppressed in differentiated tissues but remains widespread in larval imaginal discs containing precursor cells for adult structures. Using eye development as an example, we propose that the mosaic phenotype is determined during differentiation by a variegated relaxation in heterochromatic silencing. Though unpredicted by prevailing models, this mechanism is evident in other analogous systems.

Animals↗
PubMed1997

Mutations in the human homologue of the Drosophila segment polarity gene patched (PTCH) in sporadic basal cell carcinomas of the skin and primitive neuroectodermal tumors of the central nervous system.

The human homologue of the Drosophila segment polarity gene patched (PTCH) has recently been identified as the tumor suppressor gene responsible for the nevoid basal cell carcinoma (BCC) syndrome (H. Hahn et al., Cell, 85: 841-851, 1996; R. L. Johnson et al., Science (Washington DC), 272: 1668-1671, 1996). In addition to multiple BCCs, patients with nevoid BCC syndrome have a predisposition for the development of primitive neuroectodermal tumors (PNETs) of the central nervous system. We have analyzed 9 sporadic BCCs and 37 PNETs for mutation and expression of the PTCH gene. PTCH mutations were found in 3 BCCs (33.3%) and in 5 PNETs (14%), including 1 of 5 cerebral PNETs, 2 of 15 medulloblastomas, and 2 of 17 desmoplastic medulloblastomas. The sequence changes in six of these tumors (four PNETs, two BCCs) were mutations predicted to result in truncated proteins. Missense mutations were detected in one PNET and one BCC each. In addition, novel sequence polymorphisms were found in exon 2, intron 5, intron 10, and intron 14 of PTCH. Reverse transcription-PCR analysis revealed increased PTCH expression levels compared to nonneoplastic brain tissue and normal skin in the majority of PNETs and BCCs investigated. Our data suggest that genetic alterations of PTCH are not only of significance in hereditary and sporadic BCCs but are also involved in the molecular pathogenesis of a subset of sporadic central nervous system PNETs.

Adolescent↗
PubMed1997

[Molecular analysis of certain derivatives of mutants with the unstable white-starka allele].

Molecular analysis of several mutations of the white locus was performed. The mutations were obtained as a result of mutagenesis in the unstable white-starka locus described previously. A large insert (approximately 15 kb in length) downstream of the first exon of the white gene was shown to be partly excised. Simultaneous excisions of various regions from the natural regulatory region of the white locus were also observed. Restriction enzyme analysis showed that the observed mutations and reversions resulted from large deletions from the regulatory gene region. Southern and Northern blot hybridization showed the presence of unknown regulatory regions within and outside the insert.

ATP-Binding Cassette Transporters↗
PubMed1998

[Molecular analysis of a double hyperunstable system y(2ns)sc(me)].

Molecular analysis of hyperunstable mutations in the adjacent yellow and scute loci was performed in a Drosophila melanogaster strain y2ns scme obtained earlier. The y2ns scme combination originated from the original y+ns mutation associated with the insertion into the regulatory region of the yellow gene of a chimeric sequence flanked by deletion copies of the P element. The new combination of mutations resulted from an inversion between P-element copies located in the adjacent yellow and scute loci. The inversion was flanked by two P-element copies at one side and one copy at the other side. All three P-element copies had various internal deletions and, therefore, could not code for active transposase. An introduction of the delta (2-3) gene for transposase induced mutagenesis in the y2ns scme strain. Most mutations observed were associated with either excision of a single P-element copy or reinversion resulting from the recombination between the ends of P elements located in the yellow and scute genes. Genetic analysis showed that the alleles resulting from the recombination at a high frequency reverted to the original state.

Alleles↗
PubMed1998

Environment-influenced expression of polygene mutations isolated from a natural population of Drosophila melanogaster.

Quantitative trait loci (QTLs) affecting sternopleural bristle number in Drosophila melanogaster have been mapped using phenotypic markers and progeny testing. The loci were found on four of the third chromosomes isolated from a natural population. All four loci showed large effects at the standard 25 degrees C culture temperature, but they responded in different ways when developmental temperature was lowered or raised. These data support the hypothesis that genotype x environment interactions have important influences on polygene expression, and some loci might be silent, or phenotypically neutral, under some conditions but play a large phenotypic role under others. Thus, a full cataloging of the loci contributing to mutational variance for QTLs cannot be done at just a single, controlled environmental condition.

Animals↗
PubMed2002

[The "image" of the regulatory gene in experiments with Drosophila].

The mutants referred to as facultative dominant lethals were selected in the progeny of gamma-irradiated Drosophila males. The mutant males were viable and fertile, though their crosses with females of the yellow line yielded no daughters. The mutations obtained differed from the common mutations by (1) extremely varying penetrance of F1 hybrids from crosses with various lines; (2) the uncertain relationships between the mutant and normal alleles; (3) the different expression in somatic and germ cells; (4) the dependence of the expression on the sex of the parent carrying the donor mutations; (5) the mass morphosis formation and (6) the frequent reversal to the norm. These mutations are assigned to the regulatory group and their specific expression (see above) can be helpful in identifying regulatory gene mutations. We assume that the specific expression of the mutations studied is related to specific properties of the regulatory genes. These properties are as follows: (1) only one out of two homologous regulatory genes located on one homolog is in an active state, (2) in the haploid chromosome set the regulatory gene is represented by several alleles (cys-alleles); (3) only one allele ensures the regulatory gene activity.

Alleles↗
PubMed2001

Identification of X chromosomal restriction fragment length polymorphism markers and their use in a gene localization study in Drosophila virilis and D. littoralis.

We have identified six restriction fragment length polymorphism (RFLP) markers based on unique gene sequences on the X chromosome of Drosophila virilis and D. littoralis. The markers were localized by in situ hybridization on larval polytene chromosomes, and the conjugation of the X chromosomes of the two species was studied in salivary glands of interspecific hybrid female larvae. The gene arrangement of D. virilis and D. littoralis appeared to be very different at the proximal end of the X chromosome preventing recombination between RFLP markers located in this area. Simple quantitative trait loci (QTL) analysis showed that five of our marker genes (including nonA and Dmca1A, previously found to affect male courtship song in D. melanogaster) are linked with a gene(s) having a major effect on species differences in the male courtship song between D. virilis and D. littoralis. This shows that the song gene(s) may be located inside a large X-chromosomal inversion in D. littoralis (as previously suggested), but that it may also be located on an area between this inversion and the centromere, close to nonA and Dmca1A. Localization of this gene or gene complex will be continued with the aid of our newly identified RFLP markers by making interspecific crosses between D. virilis group species with more similar X chromosomes.

Animals↗
PubMed1988

The structure of the gene for cecropin B, an antibacterial immune protein from Hyalophora cecropia.

Pupae of the moth Hyalophora cecropia respond to an injection of live bacteria by the production of a potent antibacterial activity. The broad-spectrum property of this activity is due chiefly to two small proteins, cecropins A and B. Sequences of the proteins showed them to be homologous and to contain 37 and 35 amino acid residues respectively. The subsequent isolation of two cDNA clones for cecropin B showed that this protein is made as a prepro molecule composed of 62 amino acid residues. We have now prepared a genomic bank and studied four genomic clones for cecropin B. The coding regions were found in two neighbouring BglII fragments, one 0.79 kb and another varying in size from 3.1 kb to 4.9 kb for different clones. One transcriptional unit for preprocecropin B was sequenced and found to be 1035 bp long with a single intron, 514 bp in size. A conserved, insect specific cap site, ATCATTC, was identified by S1 mapping and primer extension experiments. Indications were found for the presence of multigene families and multicopy genes.

Animals↗
PubMed2002

A bacterial artificial chromosome-based genetic linkage map of the nematode Pristionchus pacificus.

To understand the evolution of developmental processes, nonmodel organisms in the nematodes, insects, and vertebrates are compared with established model systems. Often, these comparisons suffer from the inability to apply sophisticated technologies to these nonmodel species. In the nematode Pristionchus pacificus, cellular and genetic analyses are used to compare vulva development to that of Caenorhabditis elegans. However, substantial changes in gene function between P. pacificus and C. elegans limit the use of candidate gene approaches in studying P. pacificus mutations. To facilitate map-based cloning of mutations in P. pacificus, we constructed a BAC-based genetic linkage map. A BAC library of 13,440 clones was generated and completely end sequenced. By comparing BAC end and EST sequences between the "wild-type" strain P. pacificus var. California and the polymorphic strain P. pacificus var. Washington, 133 single-stranded conformational polymorphisms were identified. These markers were tested on a meiotic mapping panel of 46 randomly picked F(2) animals after a cross of the two strains, providing the first genetic linkage map of P. pacificus. A mapping strategy using two selected markers per chromosome was devised and the efficiency of this approach was illustrated by the mapping of the Ppa-unc-1/Twitchin gene.

Animals↗
PubMed2005

Multilocus analysis of introgression between two sympatric sister species of Drosophila: Drosophila yakuba and D. santomea.

Drosophila yakuba is widely distributed in sub-Saharan Africa, while D. santomea is endemic to the volcanic island of São Tomé in the Atlantic Ocean, 280 km west of Gabon. On São Tomé, D. yakuba is found mainly in open lowland forests, and D. santomea is restricted to the wet misty forests at higher elevations. At intermediate elevations, the species form a hybrid zone where hybrids occur at a frequency of approximately 1%. To determine the extent of gene flow between these species we studied polymorphism and divergence patterns in 29 regions distributed throughout the genome, including mtDNA and three genes on the Y chromosome. This multilocus approach, together with the comparison to the two allopatric species D. mauritiana and D. sechellia, allowed us to distinguish between forces that should affect all genes and forces that should act on some genes (e.g., introgression). Our results show that D. yakuba mtDNA has replaced that of D. santomea and that there is also significant introgression for two nuclear genes, yellow and salr. The majority of genes, however, has remained distinct. These two species therefore do not form a "hybrid swarm" in which much of the genome shows substantial introgression while disruptive selection maintains distinctness for only a few traits (e.g., pigmentation and male genitalia).

Animals↗
PubMed1964

CULTURE OF INSECT SALIVARY GLANDS IN A CHEMICALLY DEFINED MEDIUM.

A method for culturing the salivary glands of Sciara coprophila in a chemically defined medium has been developed. During a 24-hour period, the polytene chromosomes from six larval stages undergo normal developmental mental changes, including puff formation, puff condensation, and DNA synthesis.

Animals↗