PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Chromosomes, Insect”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

[Genetic and somatic effects of ionizing radiation in humans and animals (comparative aspect)].

Genetic effects of ionizing radiation in the progeny of exposed parents could be conventionally subdivided on three main types. 1. Severe developmental disorders (fetus death, stillbirth, early postnatal mortality, malformation, hereditary disease, sterility). These effects are known to be caused by so called "gross" mutations (genomic, chromosomal, those of essential genes) with dominant harmful effects. Although found in rodents, insects, fishes they have not been found in humans. The proposal is made that the higher reproductive potency of a species the higher its tolerance for defective organisms. Due to strong selection against severe defects at the earliest stage of pregnancy, this genetic effect of radiation is likely to be difficult to detect in people. 2. Increased cancer risk manifested as elevated incidence of spontaneous tumors and increased sensitivity to carcinogenic agents. 3. Decreased fitness (non-carcinogenic negative health effects). These two last types of radiation genetic effects are presumably due to instability and functional inferiority of cell genome in the progeny of irradiated parents. The genetic background of these effects is suggested to be the load of induced minor mutations in regulatory genes (mini-, microsatelite loci) or/and epigenomic rearrangements of DNA in parental germ cells transmitted to progeny. These radiation genetic effects are much more obvious in animals as compared to humans. Apparently, they are difficult to find in humans because of their essential dependence on promotive (life style) factors, which are impossible to control in the offspring of irradiated people. A comparison of somatic (in irradiated organisms) and genetic (in the progeny of irradiated parents) effects of radiation provide evidence on the phenomenological as well as pathogenic similarity.

Animals↗
PubMedDate not supplied

[Cytogenetic activity of the harmful insect chemosterilant, dimatif, on mouse bone marrow cells].

The new insects' chemosterilant, dimatyph, (diethylene-imide amidothiophosphorous acid) induced a significant increase of chromosomal aberrations in the mouse bone marrow cells after a single per os treatment in doses of 100.0, 10.0, 1.0, 0.1 mg/kg. An extremely high mutagenic activity of dimatyph (maximal cytogenetic effect 33.6%, minimal effective dose 1.0 mg/kg) does not permit a widespread use of this substance as a pesticide.

Animals↗
PubMed2002

A cluster of candidate odorant receptors from the malaria vector mosquito, Anopheles gambiae.

Olfaction is critical to the host preference selection behavior of many disease-transmitting insects, including the mosquito Anopheles gambiae sensu stricto (hereafter A. gambiae), one of the major vectors for human malaria. In order to more fully understand the molecular biology of olfaction in this insect, we have previously identified several members member of a family of candidate odorant receptor proteins from A. gambiae (AgORs). Here we report the cloning and characterization of an additional AgOR gene, denoted as AgOr5, which shows significant similarity to putative odorant receptors in A. gambiae and Drosophila melanogaster and which is selectively expressed in olfactory organs. AgOr5 is tightly clustered within the A. gambiae genome to two other highly homologous candidate odorant receptors, suggesting that these genes are derived from a common ancestor. Analysis of the developmental expression within members of this AgOR gene cluster reveals considerable variation between these AgORs as compared to candidate odorant receptors from D. melanogaster.

Amino Acid Sequence↗
PubMed1998

Targeting of MOF, a putative histone acetyl transferase, to the X chromosome of Drosophila melanogaster.

Dosage compensation ensures that males with a single X chromosome have the same amount of most X-linked gene products as females with two X chromosomes. In Drosophila, this equalization is achieved by a twofold enhancement of the level of transcription of the X in males relative to each X chromosome in females. The products of at least five genes, maleless (mle), male-specific lethal 1, 2, and 3 (msl-1, msl-2, msl-3) and males absent on the first (mof), are necessary for dosage compensation. The proteins produced by these genes form a complex that is preferentially associated with numerous sites on the X chromosome in somatic cells of males but not of females. Binding of the dosage compensation complex to the X chromosome is correlated with a significant increase in the presence of a specific histone isoform, histone 4 acetylated at lysine 16, on this chromosome. Experimental results and sequence analysis suggest that the mof gene encodes an acetyl transferase that plays a direct role in the specific histone acetylation associated with dosage compensation. Recently, RNA transcripts encoded by at least two different genes have also been found associated with the X chromosome in males. We have studied the role played by the various components of the complex in the targeting of MOF to the X chromosome. To this end, we have used indirect cytoimmunofluorescence to monitor the binding of these components in males carrying complete or partial loss-of-function mutations as well as in XX individuals in which formation of the dosage compensation complex has been induced by genetic means.

Acetyltransferases↗
PubMed2005

Molecular characterization and chromosomal localization of female-specific genes from the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae).

We report here the molecular characterization of the female-specific FST (female-specific transcript) genes from the Mediterranean fruit fly (medfly) Ceratitis capitata. A genomic clone was isolated, containing a sequence coding for FST. Nucleotide analysis of the clone showed that the gene contains a putative unique intron located in the region encoding the signal peptide. Southern blotting and in situ hybridization analysis on polytene chromosomes suggested the presence of additional genes similar to FST in the genome of the medfly. A novel cDNA clone was isolated from an accessory gland cDNA library, encoding a product that shares 98% identity with the hypothetical translational product of the previously isolated FST cDNA. The novel cDNA was therefore named FST2. The analysis of mitotic and polytene chromosomes by in situ hybridization showed that FST genes map on the left arm of the 4th chromosome of C. capitata.

Animals↗
PubMed2000

Molecular population genetics of X-linked genes in Drosophila pseudoobscura.

This article presents a nucleotide sequence analysis of 500 bp determined in each of five X-linked genes, runt, sisterlessA, period, esterase 5, and Heat-shock protein 83, in 40 Drosophila pseudoobscura strains collected from two populations. Estimates of the neutral migration parameter for the five loci show that gene flow among D. pseudoobscura populations is sufficient to homogenize inversion frequencies across the range of the species. Nucleotide diversity at each locus fails to reject a neutral model of molecular evolution. The sample of 40 chromosomes included six Sex-ratio inversions, a series of three nonoverlapping inversions that are associated with a strong meiotic drive phenotype. The selection driven by the Sex-ratio meiotic drive element has not fixed variation across the X chromosome of D. pseudoobscura because, while significant linkage disequilibrium was observed within the sisterlessA, period, and esterase 5 genes, we did not find evidence for nonrandom association among loci. The Sex-ratio chromosome was estimated to be 25,000 years old based on the decomposition of linkage disequilibrium between esterase 5 and Heat-shock protein 83 or 1 million years old based on the net divergence of esterase 5 between Standard and Sex-ratio chromosomes. Genetic diversity was depressed within esterase 5 within Sex-ratio chromosomes, while the four other genes failed to show a reduction in heterozygosity in the Sex-ratio background. The reduced heterogeneity in esterase 5 is due either to its location near one of the Sex-ratio inversion breakpoints or that it is closely linked to a gene or genes responsible for the Sex-ratio meiotic drive system.

Animals↗
PubMed1994

Molecular analysis of a candidate gene for the reproductive isolation between sibling species of Drosophila.

The X-linked gene Hmr in Drosophila melanogaster, when mutated, rescues otherwise inviable interspecific hybrids from crosses between D. melanogaster and any of its three most closely related species D. simulans, D. mauritiana and D. sechellia. DNA from the site of a breakpoint at the putative locus of the gene has been cloned, and results of transcription and sequence analyses are presented. Three distinct mRNAs are transcribed from this locus, two of which are abundantly expressed throughout life. A third transcript, which is larger but rarer, appears to be disrupted by at least one of the two known mutations of Hmr. The gene encodes a mitochondrial ADP/ATP translocator protein, which plays an essential role in maintaining metabolic energy. Analysis of several cDNAs suggested that the rescue of hybrids may be dependent on mutations in the variable 3' end region of this gene, affecting the level and/or the stability of the largest messenger RNA.

Amino Acid Sequence↗
PubMed1999

Molecular cloning of a SALL1-related pseudogene and mapping to chromosome Xp11.2.

SALL1 and SALL2 have been identified as two human homologs of the region-specific homeotic gene spalt (sal) of Drosophila, which encodes a zinc finger protein of characteristic structure. SALL1 has recently been found to be mutated in patients with Townes-Brocks syndrome (TBS, OMIM No. 107480). Here we report the isolation and mapping of another sal-like human gene, named SALL1P, on chromosome Xp11.2. This intronless gene closely resembles SALL1 but displays several mutations, suggesting that SALL1P represents a sal-related pseudogene. The high similarity of SALL1P to SALL1 is of considerable importance for mutation analysis of SALL1 in TBS.

Abnormalities, Multiple↗
PubMed1995

FISH analysis of the telomere sequences of bulldog ants (Myrmecia: formicidae).

Chromosomes from several species of ants from the genus Myrmecia were hybridized with deoxyoligomer probes of either (T2AG2)7, the putative insect telomere repeat sequence, or (T2AG3)7, the vertebrate telomere repeat sequence. While both sequences hybridized over a range of stringency conditions, (T2AG2)n was clearly the predominant sequence at the termini of the Myrmecia chromosomes. No interstitial sites of either sequence were detected. The genus Myrmecia has a wide range of karyotypes, with chromosome numbers ranging from 2n=2-84. It has been hypothesized that the ancestral karyotype was 2n=4 and karyotype evolution proceeded with an increase in chromosome number. In the absence of detectable interstitial sites of telomere sequence, it is interesting to speculate on the origin of the new telomeres as the chromosome numbers increased.

Animals↗
PubMed1995

[Genetics of unstable alleles of X-chromosome genes isolated during the outburst of the yellow mutation in 1982-1991 in the natural population of Drosophila melanogaster in Umani].

In 1982, a local increase of frequency of mutation yellow-2, which lasted for a decade, occurred in a population of Drosophila melanogaster from Uman' (Ukraine). Genetic properties (phenotypic difference, mutability, and peculiarities of complementation) of alleles yellow-2, isolated from the population during the mutation outburst, and of their revertants, were studied. Allelic diversity, which reflected molecular differences in allele structure, was shown to appear. In addition to mutation yellow, isolated in 1990 from the Uman' population, mutational properties of other sex-linked genes (dusky, miniature, rudimentary, singed, and vermilion) isolated from natural populations in 1986 to 1990, were analyzed. Based on these data, the conclusion was drawn that the presence of unstable alleles in populations is not a sufficient condition for mutation outbursts. Comparative analysis of properties of the alleles, obtained in different periods of the outburst, continues.

Alleles↗
PubMed2000

Cloning and heterologous expression of Dalpha4, a Drosophila neuronal nicotinic acetylcholine receptor subunit: identification of an alternative exon influencing the efficiency of subunit assembly.

A neuronal nicotinic acetylcholine receptor (nAChR) subunit, Dalpha4, has been identified and cloned from the fruit fly Drosophila melanogaster, together with several alternatively spliced transcripts. Intron-exon boundaries within the gene encoding Dalpha4 (nAcRalpha-80B) have been identified by comparison of cDNA and genomic sequence data. The influence of amino acids encoded by alternatively spliced exons upon nicotinic radioligand binding and subunit-subunit co-assembly has been examined by heterologous expression in Drosophila S2 cells. The efficiency of subunit assembly has been shown to be influenced by amino acids surrounding the highly conserved 15 amino acid cysteine-loop motif within the N-terminal extracellular domain of the nAChR Dalpha4 subunit. Extensive use has been made of publicly available data determined by the Berkeley Drosophila Genome Project (BDGP). This includes expressed sequence tag (EST) data as well as whole-embryo in situ hybridisation and polytene chromosome in situ hybridisation data. BDGP in situ hybridisation data suggests that the Dalpha4 mRNA is expressed within Drosophila brain and ventral nerve cord and demonstrates that the gene encoding this nAChR subunit is located at position 80B on chromosome 3. The relationship between Dalpha4 and other previously cloned nAChR subunits has been examined and the implications for the nomenclature of insect nAChRs is discussed.

Alternative Splicing↗
PubMed1994

Deletions induced in the white and vermilion genes of Drosophila melanogaster by the antitumor drug cis-dichlorodiammineplatinum(II).

This paper describes the analysis of cisplatin induced mutations at the white (w) and vermilion (v) loci located on the X chromosome of Drosophila melanogaster. Twenty-eight w and eight v mutants have been found in a male genetic context and 42 w mutants in a female genetic context. In these latter experiments, genetic analysis showed the presence of multi-locus deficiencies in 18 out of 42 w mutants. Eighteen w and three v intragenic mutations were analyzed at the molecular level. Seventeen w and three v mutants carry deletions within the gene, ranging in size from 4 to 109 base pairs. Sequence analysis of the mutants indicates that most of them were produced by non-homologous recombinational events occurring between short (2-5 bp) sequence repeats on both sides of the deletion, one repeat being retained at the new junction. These results differ largely from those obtained in prokaryotic and other eukaryotic cells.

ATP-Binding Cassette Transporters↗
PubMed1993

Glutamate receptors of Drosophila melanogaster. Primary structure of a putative NMDA receptor protein expressed in the head of the adult fly.

The NMDA subtype of ionotropic glutamate receptors has been implicated in the activity-dependent modification of synaptic efficacy in the mammalian brain. Here we describe a cDNA isolated from Drosophila melanogaster which encodes a putative invertebrate NMDA receptor protein (DNMDAR-I). The deduced amino acid sequence of DNMDAR-I displays 46% amino acid identity to the rat NMDAR1 polypeptide and shows significant homology (16-23%) to other vertebrate and invertebrate glutamate receptor proteins. The DNMDAR-I gene maps to position 83AB of chromosome 3R and is highly expressed in the head of adult flies. Our data indicate that the NMDA subtype of glutamate receptors evolved early during phylogeny and suggest the existence of activity-dependent synaptic plasticity in the insect brain.

Amino Acid Sequence↗
PubMed2002

Sex-specific differences in meiotic chromosome segregation revealed by dicentric bridge resolution in mice.

The meiotic properties of paracentric inversion heterozygotes have been well studied in insects and plants, but not in mammalian species. In essence, a single meiotic recombination event within the inverted region results in the formation of a dicentric chromatid, which usually breaks or is stretched between the two daughter nuclei during the first meiotic anaphase. Here, we provide evidence that this is not the predominant mode of exchange resolution in female mice. In sharp contrast to previous observations in other organisms, we find that attempts to segregate the dicentric chromatid frequently result not in breakage, stretching, or loss, but instead in precocious separation of the sister centromeres of at least one homolog. This often further results in intact segregation of the dicentric into one of the meiotic products, where it can persist into the first few embryonic divisions. These novel observations point to an unusual mechanism for the processing of dicentric chromosomes in mammalian oogenesis. Furthermore, this mechanism is rare or nonexistent in mammalian spermatogenesis. Thus, our results provide additional evidence of sexual dimorphism in mammalian meiotic chromosome behavior; in "stressful" situations, meiotic sister chromatid cohesion is apparently handled differently in males than in females.

Animals↗
PubMed1997

Lack of degeneration of loci on the neo-Y chromosome of Drosophila americana americana.

The extent of genetic degeneration of the neo-Y chromosome of Drosophila americana americana has been investigated. Three loci, coding for the enzymes enolase, phosphoglycerate kinase and alcohol dehydrogenase, have been localized to chromosome 4 of D. a. americana, which forms the neo-Y and neo-X chromosomes. Crosses between D.a. americana and D. virilis or D. montana showed that the loci coding for these enzymes carry active alleles on the neo-Y chromosome in all wild-derived strains of americana that were tested. Intercrosses between a genetically marked stock of virilis and strains of americana were carried out, creating F3 males that were homozygous for sections of the neo-Y chromosome. The sex ratios in the F3 generation of the intercrosses showed that no lethal alleles have accumulated on any of the neo-Y chromosomes tested. There was evidence for more minor reductions in fitness, but this seems to be mainly caused by deleterious alleles that are specific to each strain. A similar picture was provided by examination of the segregation ratios of two marker genes among the F3 progeny. Overall, the data suggest that the neo-Y chromosome has undergone very little degeneration, certainly not to the extent of having lost the functions of vital genes. This is consistent with the recent origin of the neo-Y and neo-X chromosomes, and the slow rates at which the forces that cause Y chromosome degeneration are likely to work.

Animals↗