Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chromosomes, Insect”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,261 records · Page 70Linked to original sources
PubMed1995

The transposable element mariner can excise in non-drosophilid insects.

Plasmid-based excision assays performed in embryos of two non-drosophilid species using the mariner transposable element from Drosophila mauritiana resulted in empty excision sites identical to those observed after the excision of mariner from D. mauritiana chromosomes. In the presence of the autonomous mariner element Mos1, excision products were recovered from D. melanogaster, D. mauritiana and the blowfly Lucilia cuprina. When a hsp82 heat shock promoter-Mos1 construct was used to supply mariner transposase, excision products were also recovered from the Queensland fruitfly Bactrocera tryoni. Analysis of DNA sequences at empty excision sites led us to hypothesise that the mariner excision/repair process involves the formation of a heteroduplex at the excision breakpoint. The success of these assays suggests that they will provide a valuable tool for assessing the ability of mariner and mariner-like elements to function in non-drosophilid insects and for investigating the basic mechanisms of mariner excision and repair.

Animals↗
PubMed1997

IMP-L3, A 20-hydroxyecdysone-responsive gene encodes Drosophila lactate dehydrogenase: structural characterization and developmental studies.

IMP-L3, a gene isolated as a potential mediator of imaginal disc morphogenesis in Drosophila melanogaster, encodes lactate dehydrogenase (LDH). The predicted amino acid sequence of IMP-L3 is 58-61% identical to those of human LDHs. In cultured imaginal discs, IMP-L3 transcript levels and LDH enzyme activity increase in response to the steroid hormone, 20-hydroxyecdysone. In embryos, IMP-L3 transcript and LDH activity appear in developing somatic muscles by late stage 13, well before the onset of muscular contraction. High levels of transcript and LDH activity persist throughout embryogenesis and throughout larval development. The gene has been localized by in situ hybridization and deficiency mapping to 65A7-65B2 on the third chromosome. LDH activity is reduced to approximately 50% of wild type in animals heterozygous for a deficiency that removes the 65A-B region. Embryos deficient for the 65A-b region lack LDH activity. We conclude that IMP-L3 is the only gene that encodes LDH in Drosophila.

Amino Acid Sequence↗
PubMed1995

Immunological studies on the developmental and chromosomal distribution of ecdysteroid receptor protein in Chironomus tentans.

Antisera were raised against different domains of a putative ecdysteroid receptor (cEcRH) of Chironomus tentans. All the antisera reacted with a 68,000 dalton protein exhibiting DNA binding properties. Additionally, we were able to demonstrate that the antisera immunoprecipitate protein which binds a radioactively labeled ecdysteroid (Ec), i.e., [3H]ponasterone A, with high specificity. These properties indicate that the antisera recognize specifically an endogenous ecdysteroid receptor protein (cEcR) in C. tentans cells and thus are suitable for the following quantitative and qualitative immunological and immunohistochemical investigations. The cellular level of cEcR varies during development, and it is particularly low in oligopausing larvae. In polytene chromosomes of prepupal salivary glands, cEcR is located at approximately 50 transcriptionally active loci. These loci include both early ecdysteroid (Ec)-inducible puff sites, such as the locus containing the gene coding for the homolog of the E75 protein in Drosophila melanogaster, as well as late Ec-inducible puff-sites. The latter group comprises a locus of a gene specifying the homolog of the D. melanogaster ultraspiracle protein. However, loci of genes coding for salivary gland secretory proteins (e.g., Balbiani ring forming chromosome regions) do not specifically react with the antisera. Thus, the developmental regulation of these genes is not directly controlled by Ec. Polytene chromosomes of oligopausing larvae show hardly any loci that contain cEcR. The few detected correspond, with few exceptions, to the most potent cEcR binding sites found in prepupae.

Amino Acid Sequence↗
PubMed2001

Mechanism of the fluorescent light induced suppression of Curly phenotype in Drosophila melanogaster.

A dominant mutation Curly (Cy), frequently used as a marker on the second chromosome in Drosophila melanogaster, was previously shown to be suppressed by several factors, including larval crowding, low temperature, and fluorescent light. While the first two factors affect this mutation only partially, fluorescent tube exposed flies exhibit an almost completely suppressed (wild type) phenotype. This suppressive effect is the result of a combination of the electric field and light, both factors being produced by common fluorescent tubes. In this study, experiments were carried out to clarify the basic mechanism of this unique phenomenon. Two fluorescent tube sensitive stages of Drosophila development were found in the second half of embryonic development and first half of the pupal stage. Riboflavin, which is administered to Drosophila larvae with yeast, and decomposed by light, seems to play a key role in this phenomenon. In a medium lacking riboflavin caused by light exposure, Cy expression is inhibited by the action of electric field. Positive results of experiments with lithium ions, which block the opening of Ca(2+) channels, support the hypothesis that electromagnetic fields may alter ion currents during ontogenic development of Drosophila, and thus influence, expression of the Cy gene. Also, fluorescent light induces an overexpression of a specific protein in the imaginal wing disc of Cy pupae.

Animals↗
PubMed1994

Genetic and molecular analyses of mutations involved in Drosophila raf signal transduction.

We have identified dominant mutations that suppress the lethality associated with an R217-->L mutation in the GTP.Ras binding region (CR1) of the Drosophila raf (D-raf) serine/threonine kinase. Four intragenic and seven extragenic suppressors were recovered. Each of the four intragenic mutations contains one compensatory amino acid change located in either the CR1 or the kinase domain of D-raf. The seven extragenic suppressors represent at least four genetic loci whose effects strongly suggest that they participate in both the sevenless and Drosophila EGF receptor (DER) signaling pathways. One of these mutations, Su(D-raf)34B, is an allele of D-mek which encodes the known signaling molecule MAPK kinase (MEK). A D83V mutation in D-MEK is identified and shown to be sufficient to confer the dominant activity of Su(D-raf)34B.

Amino Acid Sequence↗
PubMed1995

malvolio, the Drosophila homologue of mouse NRAMP-1 (Bcg), is expressed in macrophages and in the nervous system and is required for normal taste behaviour.

We report the sequence, expression pattern and mutant phenotype of malvolio (mvl), the Drosophila homologue of mammalian natural resistance-associated macrophage proteins (NRAMPs). In the mouse, this novel transporter is encoded by Bcg, a dominant gene that confers natural resistance to intracellular parasites. mvl was identified in a screen for mutants that affect taste behaviour. We show that loss-of-function as well as insertional mutants in mvl display defects in taste behaviour with no alterations in the physiology of the sensory neurons. Activity of the reporter enzyme beta-galactosidase, that reflects the expression pattern of mvl, is seen in mature sensory neurons and in macrophages. The conceptual translation of the mvl cDNA shows a striking similarity (65% identity) with human NRAMP with almost complete identity in a conserved consensus motif found in a number of ATP-coupled transporters. Based on its phenotype and expression pattern as well as its structural similarities to NRAMPs and a nitrate transporter in Aspergillus nidulans, we discuss a possible role for MVL in nitrite/nitrate transport and its implications.

Amino Acid Sequence↗
PubMed1997

A novel KH-domain protein mediates cell adhesion processes in Drosophila.

Adhesion of cells to one another and to extracellular matrices has major roles in morphogenetic processes during development. One important family of cell adhesion receptors are the integrins, which in Drosophila have crucial functions in at least two adhesion-mediated developmental events: embryonic muscle attachment and adhesion of the wing epithelia. We have cloned and characterized a gene (struthio) that is expressed in embryonic mesodermal and muscle cells, including cardioblasts, and epidermal muscle attachment sites in a pattern that is reminiscent of the expression pattern of the PS integrins. Maternal and zygotic transcripts are produced by this gene and encode similar proteins with two alternative carboxy tails. Both proteins contain identical KH domains, a protein sequence motif that is found in numerous proteins that interact with RNA. The struthio protein is highly homologous in a region including the KH domain to the mouse quaking and C. elegans gld-1 proteins, two developmentally important genes. Somatic homozygous clones of an embryonic lethal mutation in this gene (stru1A122) cause wing blisters and flight impairment, phenotypes which are associated with PS integrin subunit mutations. Thus, the struthio gene encodes a putative RNA-binding protein that appears to regulate some aspects of Drosophila integrin functioning.

Amino Acid Sequence↗
PubMed1994

Chromosome locations of human EMX and OTX genes.

We have determined the chromosomal localization of four human homeobox-containing genes, EMX1, EMX2, OTX1, and OTX2, related to Drosophila genes expressed in the developing head of the fly. Murine homologs of these genes are expressed in specific nested domains in the developing rostral brain of midgestation embryos. DNAs from a panel of 19 rodent-human hybrids, each carrying one or a few human chromosomes such that most human chromosome regions were represented, were tested for the presence of the four gene loci by filter hybridization to radiolabeled probes. Regional chromosomal localization was determined by similarly testing DNAs from hybrid mapping panels for each of the candidate chromosomes. Finally, fluorescence in situ hybridization of cosmid clones for these loci refined the locations, two of which were in the vicinity of previously mapped orphan homeobox genes and two of which were near each other. OTX2, the earliest and most widely expressed gene, maps to chromosome region 14q21-q22; the OTX1 locus maps to 2p13; EMX2 maps to 10q26.1; and EMX1, the most narrowly and lately expressed, maps to 2p14-p13. Thus, these homeobox-containing genes involved in brain development are not linked to any of the four HOX clusters on 7p15-p14, 17q21-q22, 12q12-q13, and 2q31. However, the OTX1 and EMX1 loci may be closely linked on or near 2p13, prompting speculation that a clustered gene structure could have functional significance, as is presumably the case for the HOX clusters.

Animals↗
PubMed1996

Cloning of a human homolog of the Drosophila enhancer of zeste gene (EZH2) that maps to chromosome 21q22.2.

To identify genes that map on human chromosome 21 (HC21) and that may contribute to the phenotype of Down syndrome (DS), exon trapping was applied to cosmid DNA from an HC21-specific library LL21NCO2-Q. More than 550 potential exons were cloned and partially characterized. One of these, hmc23b04 (GenBank X88270) showed strong homology to the Drosophila Enhancer of zeste protein (GenBank U00180) from amino acid 665 to 694 (p = 7.6 x 10(-11). We have cloned the full-length cDNA for this human homolog of the Drosophila E(z) gene (termed EZH2) and mapped it to within YACs 64f11 and 809b11 between markers D21S65 and ERG on human chromosome 21q22.2. Sequence analysis indicates that EZH2 encodes a 746-amino-acid polypeptide that shows 60.5% identity to the Drosophila E(z) protein and contains a trithorax-like domain and a DNA-binding motif. Northern blot analysis revealed that EZH2 is expressed in several tissues. Alternatively spliced mRNA species have been observed. The Drosophila E(z) protein is a member of the polycomb group genes that maintain homeotic gene repression and are thought to control gene expression by regulating chromatin. The strong sequence conservation suggests a possible function of EZH2 in regulation of gene transcription and chromatin structure; it may therefore contribute to certain phenotypes of Down syndrome by altered regulation of its target genes.

Alternative Splicing↗
PubMed1994

Genes encoding actin-related proteins of Drosophila melanogaster.

Recently, several laboratories have described proteins of yeasts, mammals and Drosophila melanogaster that are 35 to 55% identical to conventional actins, but, as yet, little is known about their functions. We have initiated a systematic study by using degenerate oligonucleotides specifying two highly conserved nucleotide-binding peptides of actin, in conjunction with polymerase chain reaction techniques, to isolate Drosophila genes that encode actin-related proteins. Here we summarize the isolation of four such genes and compare the sequences of the proteins that they encode. Computer searches of databases revealed that three of the encoded proteins are homologs of yeast or mammalian actin-related proteins, implying that the corresponding proteins participate in functions common to many cell types. The fourth gene encodes a novel protein that, apparently is expressed within testes. The four genes are located within the 14D, 53D, 66B and 87C subdivisions of polytene chromosomes.

Actins↗
PubMed1995

Molecular characterization of an 18 kb segment of DNA puff C4 of Bradysia hygida (Diptera, sciaridae).

The data presented here are an extension of the molecular characterization of DNA puff C4 of Bradysia hygida. A cDNA related to a gene amplified in this puff and expressed when puff C4 expands was cloned and sequenced. Analysis of the amino acid sequence deduced from the open reading frame present in the cDNA indicate that the encoded protein is secreted and comprises mostly alpha-helical coiled-coil. An 18 kb genomic segment containing the transcription unit of this gene was also cloned and the structure and expression of the 1.4 kb mRNA was determined. Quantitative slot blot hybridization of DNA complementary to the transcription unit shows that this gene is amplified about 21 times in the salivary gland, confirming data previously obtained. Fragments upstream of the 5' end, and beyond the 3' end, of the gene transcription unit were also analysed and shown to be amplified at least eight and five times, respectively. Based on these data we discuss how amplification could occur at DNA puffs.

Amino Acid Sequence↗
PubMed2003

A proposed role for the Polycomb group protein dRING in meiotic sister-chromatid cohesion.

ORD protein is required for accurate chromosome segregation during male and female meiosis in Drosophila melanogaster. Null ord mutations result in random segregation of sister chromatids during both meiotic divisions because cohesion is completely abolished prior to kinetochore capture of microtubules during meiosis I. Previous analyses of mutant ord alleles have led us to propose that the C-terminal half of the ORD protein mediates protein-protein interactions that are essential for sister-chromatid cohesion. To identify proteins that interact with ORD, we conducted a yeast two-hybrid screen using an ORD bait and isolated dRING, a core subunit of the Drosophila Polycomb repressive complex 1. We show that a missense mutation in ORD completely ablates the two-hybrid interaction with dRING and prevents nuclear retention of the mutant ORD protein in male meiotic cells. Using affinity-purified antibodies generated against full-length recombinant dRING, we demonstrate that dRING protein is expressed in the male and female gonads and colocalizes extensively with ORD on the chromatin of primary spermatocytes during G2 of meiosis. Our results suggest a novel role for the Polycomb group protein dRING and are consistent with the model that interaction of dRING and ORD is required to promote the proper segregation of meiotic chromosomes.

Animals↗
PubMed1998

Repetitive arrays containing a housekeeping gene have altered polytene chromosome morphology in Drosophila.

Much of our understanding of gene and chromatin organization has been developed from observation of polytene chromosomes. We describe an experimental approach using transgenes that has allowed us to observe local changes in polytene morphology. A composite P transposon that contains a fusion between the regulatory region of Prat, a purine synthesis gene, and brown (bw), an eye pigment reporter, was transformed into the 65A10 polytene band and subjected to P-transposase mutagenesis. Arrays of up to 320 kb at 65A10 were recovered by selection for increased pigment, and pigment levels were found to be proportional to numbers of copies. In polytene chromosomes, the original transformant was found to split 65A10 into two thin bands separated by an interband. With increases in copy number, the interband became progressively denser, eventually forming a dark, amorphous, deformable structure unlike any previously reported. The persistence of Prat expression in development, together with the cytological appearance of these large arrays, suggest that the state of the Prat promoter is affecting polytene structure. Because this unique structure is distinct from bands, interbands, puffs, and the chromocenter, which comprise polytene chromosomes, we suggest that it is composed of an altered form of chromatin.

Animals↗
PubMed1997

Antisense suppression of the putative ribosomal protein S3A gene disrupts ovarian development in Drosophila melanogaster.

The Drosophila melanogaster homologue of the Anopheles gambiae C3 cDNA has been isolated and characterized by sequence analysis. The encoded protein was localized by immunochemical and immunocytochemical methods. The Drosophila C3 protein is highly similar to homologues of disputed function, which have previously been identified in fungi, plants and animals. The protein is ubiquitous and localized in the cytoplasm. Cell fractionation followed by detection with a specific antibody preparation shows that the protein is associated with the 40S ribosomal subunit. The C3 gene is located in section 101F of chromosome 4. Antisense transgenic analysis shows that this gene is essential for oogenesis. The most prominent phenotype resulting from antisense depletion of C3 RNA is disappearance of the follicular cells of the ovary (where the concentration of C3 protein is normally high) and abnormalities of the associated germline derivatives, leading to failure of egg production.

Amino Acid Sequence↗
PubMed1997

Cloning, mapping and mutational analysis of the S-adenosylmethionine decarboxylase gene in Drosophila melanogaster.

S-adenosylmethionine decarboxylase is a key enzyme in the synthesis of polyamines. These small cationic molecules are required for growth and development in all organisms. A wealth of biological processes, including synthesis of DNA and protein and condensation of chromatin, involve polyamines. Inhibition of polyamine synthesis has been proposed for treatment of cancer but this requires more knowledge about the in vivo function of polyamines. We report here the cloning of the S-adenosylmethionine decarboxylase gene from Drosophila melanogaster and the analysis of corresponding mutants. The mutant phenotypes are similar to those previously described for ribosomal protein genes (Minutes) and rRNA genes (bobbed). This work elucidates the in vivo consequences of impaired polyamine synthesis with respect to the development of a whole animal.

Adenosylmethionine Decarboxylase↗
PubMed2005

Cytogenetic analysis of experimental hybrids in species of Triatominae (Hemiptera-Reduviidae).

A cytogenetic analysis was performed in experimental hybrids between species of Chagas disease transmitting bugs with remarkable differences in the amount and distribution of heterochromatin. Using C-banding technique, we identified the parental species chromosomes and analysed the meiotic behaviour in the male hybrids between Triatoma platensis and T. infestans, T. platensis and T. delpontei, and T. infestans and T. rubrovaria. The two former hybrids have an entirely normal meiotic behaviour despite the extensive differences in C-banded karyotypes observed in the parental species, indicating that heterochromatin differences between homeologous chromosomes are not a barrier that influences meiotic synapsis and recombination. On the contrary, the experimental hybrids between T. infestans and T. rubrovaria show failures in pairing of homeologous chromosomes that lead to the production of abnormal spermatids and hybrid sterility. Our data suggest that karyotypic repatterning within triatomines has involved at least two different pathways. Among closely related species, chromosomal changes have largely involved addition or deletion of heterochromatic regions. In more distant species, chromosomal rearrangements (i.e. inversions and translocations) have also arisen. Hybridisation data also allow to hypothesize about the origin and divergence of this taxonomic group, as well as the mechanisms that maintain species isolation.

Animals↗