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At least 1,207 records · Page 67Linked to original sources
PubMed2006

Binding of doa kinase to specific loci in polytene chromosomes of Drosophila melanogaster.

OBJECTIVES: Highly conserved LAMMER kinases belong to the family of dual-specific proteins phosphorylating enzymes with homologues in yeast, plants, Drosophila and mammals. SR proteins, several members of which are components of the spliceosomal complex and have been implicated in the control of alternative splicing, were identified among first targets of LAMMER kinases. The Drosophila locus Darkener of apricot (Doa) encodes best known representative of the LAMMER family of kinases, which is essential for embryonic and postembryonic development, neurogenesis, differentiation of photoreceptors, and sex determination. METHODS: DOA kinase was detected on squash preparations of polythene chromosomes using anti-DOA antibodies in combination with indirect immunofluorescence. RESULTS: Here we provide evidence for active chromosomal presence of DOA kinase in Drosophila salivary glands, and increased abundance of DOA at eleven specific loci of polythene chromosomes where it can be involved in on-site control of splicing process. Many genes that may be found at the loci with increased abundance fall into three major groups based on their known functions. First group contains genes that code for transcription factors, RNA-binding proteins or chromatin modifying enzymes. Second group of genes encode proteins which belong to proteasomal components, lipid enzymes, stress-sensitive ER proteins and caspases which are all early/proximal components of apoptotic process. Third group of genes comprises of tRNA coding genes or genes of tRNA synthases (ligases), all involved in protein synthesis. Some of the encoded protein products are confirmed or potential substrates of DOA kinase activity. CONCLUSIONS: Data indicate that genes encoding proteins involved in closely related pathways are concentrated at certain loci to achieve more efficient regulation of their expression as exemplified from distribution of DOA protein on Drosophila polythene chromosomes.

Animals↗
PubMed1994

Putative Drosophila pheromone-binding proteins expressed in a subregion of the olfactory system.

Four genes expressed in the olfactory system of Drosophila melanogaster have been identified by subtractive hybridization. Two of these genes, OS-E and OS-F, are related to genes encoding moth pheromone-binding proteins. The OS-E and OS-F genes are tightly linked and are expressed in a subregion of the antenna (the primary olfactory organ). A protein sequence analysis suggests the possibility that pheromone-binding proteins are members of a larger class of proteins, extending beyond the olfactory system. The predicted product of a third gene, OS-D, shares features common to vertebrate odorant-binding proteins, but has a primary structure unlike odorant-binding proteins. The fourth gene, OS-C, encodes a novel 13-kDa protein that contains a putative nuclear import sequence and an acid-rich region. The expression patterns of these genes differ within the antenna; their transcript distributions support the notion of specialized roles for different olfactory sensilla. The functions of the OS gene products have not been demonstrated; however, the potential identification of pheromone-binding proteins in Drosophila, a species with well characterized genetics, may offer a means of analyzing the function of these molecules that is not available in other systems.

Amino Acid Sequence↗
PubMed1997

Physical mapping of the 5 Mb D9S196-D9S180 interval harboring the basal cell nevus syndrome gene and localization of six genes in this region.

The basal cell nevus syndrome (Gorlin syndrome) is characterized by multiple basal cell carcinomas and diverse developmental defects. The gene responsible for this syndrome has been mapped previously to a 2 cM interval between D9S196 and D9S 180 at 9q22.3, and very recently mutations of a candidate gene in this region--the human homolog of the Drosophila patched gene have been identified. We report here on physical mapping studies integrating a contig of yeast artificial chromosomes and bacterial artificial chromosomes with a long-range map spanning approximately 5 Mb between the recombination-determined flanking markers. Six genes have been mapped to this interval.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

Genomic imprinting in the mealybugs.

The coccid insects (Hemiptera; Sternorrhyncha; Aphidiformes; Coccoidea; Pseudococcidae) are well suited to study not only the mechanisms of genomic imprinting but also facultative heterochromatization, a phenomenon well exemplified by inactivation of the X chromosome in female mammals. Coccids show sex-specific heterochromatization of an entire set of chromosomes and transcriptional silencing of all the paternally contributed chromosomes in males. Thus, genomic imprinting and the resultant differential regulation operate on 50% of the genome in contrast to the single X chromosome in female mammals. A significant insight into the phenomenon of genomic imprinting has come from very elegant cytological analysis of the coccid system. Recently, efforts have been made to dissect out at the molecular level the phenomenon of genomic imprinting in these insects. The present review summarizes both of these aspects. In light of the accruing experimental evidence for chromatin-based differences in the maternal and paternal genomes, it appears that the mealybug system may provide evidence for stable maintenance of chromatin code not only through mitosis but also through meiosis.

Animals↗
PubMed2002

Permanent translocation heterozygosity in dioecious Baccharis coridifolia DC. (Asteraceae).

The karyotype of Baccharis coridifolia DC., a dioecious diploid species consists of 16 chromosomes with median (m) and 2 with submedian centromeric positions (sm) (2n = 18). Meiotic analyses of 219 male plants belonging to 12 populations showed across a wide geographical range one quadrivalent and seven bivalents in all of them. The quadrivalent involves the four biggest m chromosomes and probably constitutes a sex multivalent carrying in tight linkage the sex genes and provides a mechanism whereby permanent translocation heterozygosity is maintained. In metaphase I alternate orientation of the quadrivalent was predominant (85.71%). Fourteen megaspore mother cells were analyzed and did not show the quadrivalent. A model for the origin and maintenance of the sexual translocation system is presented. It is assumed that there are two non-allelic factors M and n; M would be a dominant female suppresor and n a recessive male-suppresor. The excess of male plants observed in several populations at different localities might result from heterotic effects of some gene complexes carried by the translocation. This excess probably ensures a good supply of pollen for the vagaries of insect pollination at flowering time.

Asteraceae↗
PubMed1996

Genetic evidence for repression of somatic P element movements in Drosophila melanogaster consistent with a role for the KP element.

The P family of transposable elements in Drosophila melanogaster has, since its introduction into D. melanogaster populations in this century, diversified into a number of internally deleted forms. One of these, the KP element, is abundant in the genomes of flies from populations from Asia, Europe and Africa. There is some evidence that this sequence can act as a repressor of transposition. We have studied a mutation, signed(very weak) (snVW), in which a KP element is one of two P elements inserted into the 5' exon of the X-linked singed gene. These elements can be mobilized by a trans-acting dominant mutation, Mo, with a maternal effect, on the second chromosome. The rate of somatic reversion of snvw induced by Mo is reduced threefold if the mother herself possesses snvw on her X chromosomes. This implies that snvw may be responsible for a form of repression of P element movement. The cause of this effect may be related to transcription of the KP element in snvw. However, an effect of other genomic P elements in the repression of somatic reversion of snvw cannot be entirely excluded.

Animals↗
PubMed2002

Identification and characterization of Nek6 protein kinase, a potential human homolog of NIMA histone H3 kinase.

In Aspergillus nidulans, the kinase activity of NIMA (never in mitosis, gene A) is critical for the initiation of mitosis. NIMA regulates mitotic chromatin condensation through phosphorylation of histone H3 at serine 10. In the present study, we identified human Nek6 (hNek6), a member of the mammalian NIMA-related kinases. The predicted hNek6 protein is comprised of 338 amino acids. Northern blot analysis revealed that hNek6 transcripts are ubiquitously expressed with the highest expression found in the heart and skeletal muscle. Lower cell cycle-dependent expression of hNek6 transcripts was observed in the early G1 phase. GFP-fused hNek6 protein showed both nuclear and cytoplasmic localizations in HeLa cells. Fluorescence in situ hybridization using full-length hNek6 cDNA as a probe showed that the hNek6 gene is localized to human chromosome 9q33-34, a region at which the loss of heterozygosity is associated with transitional cell carcinomas. Importantly, recombinant hNek6 protein produced in insect cells effectively phosphorylated histones H1 and H3, but not casein. Thus, these results suggest that, unlike other mammalian NIMA-related kinases, Nek6 is a mitotic histone kinase which regulates chromatin condensation in mammalian cells.

Amino Acid Sequence↗
PubMed2004

Two whitebacked planthopper resistance genes in rice share the same loci with those for brown planthopper resistance.

The whitebacked planthopper (WBPH), Sogatella furcifera, and brown planthopper (BPH) Nilaparvata lugens Stål are important sucking insects of rice (Oryza sativa L.) crops throughout the world. Rice 'B5', which has derived its resistance genes from the wild rice O. officinalis Wall ex Watt, is a line that is highly resistant to both WBPH and BPH. Previously, two resistance genes against BPH, Qbp1, and Qbp2 in 'B5' had been mapped onto chromosome 3 and chromosome 4, respectively. In this study, we employed a mapping population composed of 187 recombinant inbred lines (RILs), produced from a cross between 'B5' and susceptible variety 'Minghui63', to locate the WBPH and BPH resistance genes. A RFLP survey of the bulked extremes from the RIL population identified two genomic regions, one on chromosome 3 and the other on chromosome 4, likely containing the resistance genes to planthoppers. QTL analysis of the RILs further confirmed that two WBPH resistance genes were mapped on the same loci as Qbp1 and Qbp2, using a linkage map with 242 molecular markers distributed on 12 rice chromosomes. Of the two WBPH resistance genes, one designated Wbph7(t) was located within a 1.1-cM region between R1925 and G1318 on chromosome 3, the other designated Wbph8(t) was within a 0.3-cM region flanked by R288 and S11182 on chromosome 4. A two-way analysis of variance showed that two loci acted independently with each other in determining WBPH resistance. The results have significant implications in studying the interactions between sucking insects and plants and in breeding programs of resistance to rice planthoppers.

Animals↗
PubMed1994

Dosage compensation in Drosophila: the X-chromosomal binding of MSL-1 and MLE is dependent on Sxl activity.

In Drosophila, dosage compensation, i.e. the equalization of levels of X-linked gene products in the two sexes, is achieved by the hypertranscription of most X-linked genes in males relative to females. The products of at least four genes, collectively termed male-specific lethal (msl) genes, are required for this process and, at least in the case of three of them, mediate this function through an association with the X chromosome in males. We have studied some of the parameters that affect the association of the msl-1 gene product and found that its presence is dependent on the wild-type function of the other three genes, leading to the conclusion that these gene products contribute to the formation of a multi-subunit complex. Furthermore, the X-chromosomal association of the msl-1 and mle gene products is negatively correlated with the level of function of the master regulatory gene Sxl and can assume either a mosaic or a uniform distribution in the tissues of mutant XX individuals. Surprisingly, we also found that the association of these two msl gene products with the two X chromosomes in females of certain mutant genotypes does not result in the hypertranscription of X-linked genes or in any apparent reduction in viability.

Animals↗
PubMed2000

Spatial differences in patterns of modification: selection on hairy in Drosophila melanogaster wings.

Artificial selection was carried out for over 45 generations to enhance and suppress expression of the mutation hairy on the Drosophila melanogaster wing. Whole chromosome mapping of X-linked and autosomal modifiers of sense organ number displayed regional differences in magnitude and direction of their effects. Regional specificity of modifier effects was also seen in some interchromosomal interactions. Scanning electron microscopy allowed precise measurement of sense organ size and position along the L3 longitudinal wing vein. Sense organ size varied in a predictable fashion along the proximal-distal axis, and the dorsal pattern differed from the ventral pattern. The high and low selection lines differed most in the proximal portion of the L3 vein. Extra sense organs in the High line were often associated with vein fragments at locations predicted from ancestral vein patterns. Thus, regional specificity of polygenic or quantitative trait locus modifier effects was identified in several different parts of the wing.

Animals↗
PubMed1999

A peritrophin-like protein expressed in the embryonic tracheae of Drosophila melanogaster.

We have cloned and sequenced a cDNA from Drosophila melanogaster that encodes a protein homologous to the peritrophins, a family of chitin-binding proteins from the peritrophic matrix of insects. Unexpectedly, the gene, Gasp, is expressed in the embryonic tracheae. We suggest that this family of proteins may be present in other tissues than the peritrophic matrix, particularly where nutrient or gas exchange are important, and/or where invasion by parasites or viruses is possible. We have also mapped two similar genes that had been sequenced by the Berkeley Drosophila Genome Project, and find that these three very similar genes are not clustered, but are located on three different chromosomes.

Amino Acid Sequence↗
PubMed1995

Functional haplodiploidy: a mechanism for the spread of insecticide resistance in an important international insect pest.

The coffee berry borer, Hypothenemus hampei, is the most important insect pest of coffee worldwide and has an unusual life history that ensures a high degree of inbreeding. Individual females lay a predominantly female brood within individual coffee berries and because males are flightless there is almost entirely full sib mating. We investigated the genetics associated with this interesting life history after the important discovery of resistance to the cyclodiene type insecticide endosulfan. Both the inheritance of the resistance phenotype and the resistance-associated point mutation in the gamma-aminobutyric acid receptor gene Rdl were examined. Consistent with haplodiploidy, males failed to express and transmit paternally derived resistance alleles. Furthermore, while cytological examination revealed that males are diploid, one set of chromosomes was condensed, and probably nonfunctional, in the somatic cells of all males examined. Moreover, although two sets of chromosomes were present in primary spermatocytes, the chromosomes failed to pair before the single meiotic division, and only one set was packaged in sperm. Thus, the coffee berry borer is "functionally" haplodiploid. Its genetics and life history may therefore represent an interesting intermediate step in the evolution of true haplodiploidy. The influence of this breeding system on the spread of insecticide resistance is discussed.

Alleles↗
PubMed1992

Isolation of a Drosophila gene encoding glutathione S-transferase.

We have isolated a Drosophila gene, DmGST-2, that encodes glutathione S-transferase, a homo- or heterodimeric enzyme thought to be involved in detoxification of xenobiotics, including known carcinogens. The encoded protein has a primary sequence that is more similar to mammalian placental and nematode GSTs than that of a previously described Drosophila GST gene, herein referred to as DmGST-1. We provide a physical map of the gene and show that it specifies at least two mRNAs, measuring 1.9 and 1.6 kb, which differ only in the lengths of their 3' untranslated regions. Both of the mRNAs are present during all developmental stages. In situ hybridization of the DmGST-2 gene to larval polytene chromosomes places it within the 53F subdivision of chromosome 2, and Southern blotting to chromosomal DNA indicates that the gene has no close relatives within the Drosophila genome. Our results make possible molecular genetic approaches for further elaborating the function of glutathione S-transferases in insect development and physiology, in the metabolism of plant toxins, and in conferring insecticide resistance.

Amino Acid Sequence↗
PubMed1995

Expression of msl-2 causes assembly of dosage compensation regulators on the X chromosomes and female lethality in Drosophila.

Male-specific lethal-2 (msl-2) is a RING finger protein that is required for X chromosome dosage compensation in Drosophila males. Consistent with the formation of a dosage compensation protein complex, msl-2 colocalizes with the other MSL proteins on the male X chromosome and coimmunoprecipitates with msl-1 from male larval extracts. Ectopic expression of msl-2 in females results in the appearance of the other MSL dosage compensation regulators on the female X chromosomes and decreased female viability. We suggest that msl-2 RNA is the primary target of SxI regulation in the dosage compensation pathway and present a speculative model for the regulation of two distinct modes of dosage compensation by SxI.

Amino Acid Sequence↗
PubMed1994

DNA-based methods for the identification of insect vectors.

Many insect vectors are members of complexes composed of morphologically identical sibling species. The identification of individual species, a requirement of epidemiological studies and control programmes, has traditionally relied upon techniques such as chromosomal analysis or isoenzyme typing. Owing to the limitations of these techniques, the last few years have seen many developments in DNA-based technologies for identification. DNA-based protocols have advantages over the other techniques utilized, in that they may identify all insect stages of both sexes using alcohol-preserved, dried, fresh or frozen specimens. The methods ultimately rely upon either DNA probe hybridization or the polymerase chain reaction (PCR). This review describes a number of approaches taken towards the development of these techniques. The aim of these approaches, whether directed or random, is to produce a methodology that is cheap, accurate and easy to use. In this review, the DNA-based techniques developed for the identification of Anopheles gambiae complex mosquitoes are used to illustrate the power of these methods, although, as the review demonstrates, the technology is directly applicable to many other mosquito or insect vectors. In addition, the methods discussed may be utilized for generating additional epidemiological data, such as identification of parasites within the vector or origin of the bloodmeal. A comprehensive survey of the probe systems available for the identification of insect vectors and the disease-causing organisms they transmit to the human population is therefore included. Given further advances in this technology, it may be anticipated that DNA-based approaches to identification may eventually supersede more traditional methodologies in the fields of tropical medicine and parasitology.

Animals↗
PubMed2003

Paucity of genes on the Drosophila X chromosome showing male-biased expression.

Sex chromosomes are primary determinants of sexual dimorphism in many organisms. These chromosomes are thought to arise via the divergence of an ancestral autosome pair and are almost certainly influenced by differing selection in males and females. Exploring how sex chromosomes differ from autosomes is highly amenable to genomic analysis. We examined global gene expression in Drosophila melanogaster and report a dramatic underrepresentation of X-chromosome genes showing high relative expression in males. Using comparative genomics, we find that these same X-chromosome genes are exceptionally poorly conserved in the mosquito Anopheles gambiae. These data indicate that the X chromosome is a disfavored location for genes selectively expressed in males.

Animals↗
PubMed1994

Archetypal organization of the amphioxus Hox gene cluster.

Organization into gene clusters is an essential and diagnostic feature of Hox genes. Insect and nematode genomes possess single Hox gene clusters (split in Drosophila); in mammals, there are 38 Hox genes in four clusters on different chromosomes. A collinear relationship between chromosomal position, activation time and anterior expression limit of vertebrate Hox genes suggests that clustering may be important for precise spatiotemporal gene regulation and hence embryonic patterning. Hox genes have a wide phylogenetic distribution within the metazoa, and are implicated in the control of regionalization along the anteroposterior body axis. It has been suggested that changes in Hox gene number and genomic organization played a role in metazoan body-plan evolution, but identifying significant changes is difficult because Hox gene organization is known from only very few and widely divergent taxa (principally insects, nematodes and vertebrates). Here we analyse the complexity and organization of Hox genes in a cephalochordate, amphioxus, the taxon thought to be the sister group of the vertebrates. We find that the amphioxus genome has only one Hox gene cluster. It has similar genomic organization to the four mammalian Hox clusters, and contains homologues of at least the first ten paralogous groups of vertebrate Hox genes in a collinear array. Remarkably, this organization is compatible with that inferred for a direct ancestor of the vertebrates; we conclude that amphioxus is a living representative of a critical intermediate stage in Hox cluster evolution.

Amino Acid Sequence↗