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.
Studies on the effects of neomycin on puffing in Chironomus.
Fourth instar Chironomus sp. larvae were used. Isolated salivaries (1/2) were incubated in RINGER containing various amounts of neomycin sulphate for various durations. Another half of salivaries, incubated in RINGER for corresponding durations served for controls. for in vivo experiments larvae were exposed to distilled water containing neomycin. Analysis of squashed preparations has revealed that puffing varies with incubation period in in vitro experiments with low concentration of drug. In in vivo studies also puff induction was evident. Higher concentrations of neomycin both in in vivo or in vitro treatments disorganized chromosomes. Present results suggest that neomycin can activate genes in an insect (or in other words in eukaryotes).
Sex-linked period genes in the silkmoth, Antheraea pernyi: implications for circadian clock regulation and the evolution of sex chromosomes.
Regulation of the period (per) gene is a critical feature of circadian clock function in insects. Here, we show that per is sex-linked in the silkmoth, Antheraea per-nyi. The previously described silkmoth per gene is found on the Z chromosome. Silkmoth per is not dosage compensated at either the RNA or the protein level. Although earlier studies showed the presence of an oscillating endogenous antisense per transcript, we show that this transcript comes from a locus on the female-specific W chromosome. We further demonstrate the presence of a homolog of per on W that encodes a truncated protein. Rhythmicity of male (ZZ) moths demonstrates that neither of the W-linked per-like genes is essential for clock function. The presence of a per allele with duplications on W provides insight into the evolution of the sex chromosomes.
Heavy metal accumulation, heat shock protein expression and cytogenetic changes in Tetrix tenuicornis (L.) (Tetrigidae, Orthoptera) from polluted areas.
The orthopteran insect Tetrix tenuicornis, collected from polluted and unpolluted areas, was used to study heavy metal accumulation and its impact on stress protein levels and on changes in the number and morphology of chromosomes in mitotic and meiotic cells. During two consecutive years, insects were collected from polluted areas of zinc-lead mine spoils near Bolesław (Poland) and from unpolluted areas near Busko and Staszów (Poland). T. tenuicornis from the polluted area showed 1.5, 4.03, 4.32 and 41.73 times higher concentrations of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), respectively, than insects of the same species collected from unpolluted areas. Insects exposed to heavy metals showed only small changes, and rather a decrease in the concentration of constitutive and inducible heat shock proteins Hsp70, the level of which increases under stress conditions. A cytogenetic study of T. tenuicornis revealed intra-population anomalies in chromosome number and morphology in mitotic and meiotic cells and the presence of an additional B chromosome in germinal cells. In 50% of females collected from polluted areas, mosaic oogonial mitotic chromosome sets and diploid, hypo- or hypertetraploid, tetraploid, and octoploid chromosome numbers were detected. In turn, 14.6% of males showed a heterozygous deficiency of chromatin in L2 and M3 bivalents in addition to the presence of B chromosomes.
Inherited semisteriity for control of harmful insects. 3. A first field experiment.
Explore the source record for details and available documents.
Conventional protein coding genes in the Drosophila Y chromosome: is the puzzle of the fertility gene function solved?
Explore the source record for details and available documents.
The gene organisation of a small RNA-containing insect virus: comparison with that of mammalian picornaviruses.
The coding regions of an insect virus, cricket paralysis virus, have been mapped using pactamycin. The results suggest that the genome of this virus functions as a polycistronic mRNA, the structural proteins being encoded by the 5' end of the RNA in an order similar to those of mammalian picornaviruses. High-molecular-weight proteins of unknown function map at the 3' end of the genome.
Spermatogenesis in Drosophila.
A short summary on the present knowledge on spermatogenesis in Drosophila is given which also points out particular questions of interest in the context of this morphogenetic process. Such points of interest are the formation of lampbrush loops in primary spermatocytes, the chromosomal events during meiosis, the occurrence of chromatin rearrangements and the regulation of gene activities at the posttranscriptional level. The activities and some major conclusions from my laboratory are subsequently described. They include studies of the expression of histone variants, the structure and function of lampbrush loops and the expression of genes participating in sperm morphogenesis.
X-linked genes evolve higher codon bias in Drosophila and Caenorhabditis.
Comparing patterns of molecular evolution between autosomes and sex chromosomes (such as X and W chromosomes) can provide insight into the forces underlying genome evolution. Here we investigate patterns of codon bias evolution on the X chromosome and autosomes in Drosophila and Caenorhabditis. We demonstrate that X-linked genes have significantly higher codon bias compared to autosomal genes in both Drosophila and Caenorhabditis. Furthermore, genes that become X-linked evolve higher codon bias gradually, over tens of millions of years. We provide several lines of evidence that this elevation in codon bias is due exclusively to their chromosomal location and not to any other property of X-linked genes. We present two possible explanations for these observations. One possibility is that natural selection is more efficient on the X chromosome due to effective haploidy of the X chromosomes in males and persistently low effective numbers of reproducing males compared to that of females. Alternatively, X-linked genes might experience stronger natural selection for higher codon bias as a result of maladaptive reduction of their dosage engendered by the loss of the Y-linked homologs.
Molecular differentiation between chromosomally defined incipient species of Anopheles funestus.
Anopheles funestus Giles is one of the most important vectors of malaria in sub-Saharan Africa. The population structure of this mosquito in Burkina Faso, West Africa based on chromosomal inversion data led to the description of two chromosomal forms, Kiribina and Folonzo. Because both forms co-occur in the same locales yet differ significantly, both in the frequency of inverted arrangements on chromosome arms 3R and 2R and in vectorial capacity, they were hypothesized to be emerging species with at least partial barriers to gene flow. This hypothesis would be strengthened by molecular evidence of differentiation between Kiribina and Folonzo at loci outside chromosomal inversions. We surveyed molecular variation in sympatric populations of the two forms using sequences from the mitochondrial ND5 gene and genotypes at sixteen microsatellite loci distributed across the genome. Both classes of marker revealed slight but significant differentiation between the two forms (mtDNA F(ST) = 0.023, P < 0.001; microsatellite F(ST) = 0.004, P < 0.001; R(st) = 0.009, P = 0.002). Locus-by-locus analysis of the microsatellite data showed that significant differentiation was not genome-wide, but could be attributed to five loci on chromosome 3R (F(ST) = 0.010, P < 0.001; R(st) = 0.016, P = 0.002). Importantly, three of these loci are outside of, and in linkage equilibrium with, chromosomal inversions, suggesting that differentiation between chromosomal forms extends beyond the inversions themselves. The slight overall degree of differentiation indicated by both marker classes is likely an underestimate because of recent population expansion inferred for both Folonzo and Kiribina. The molecular evidence from this study is consistent with the hypothesis of incipient speciation between Kiribina and Folonzo.
An integrated genetic and physical map for the malaria vector Anopheles funestus.
We have constructed a genetic map of the major African malaria vector, Anopheles funestus, using genetic markers segregating in F(2) progeny from crosses between two strains colonized from different field sites. Genotyping was performed on 174 progeny from three families using 33 microsatellite markers, a single RFLP, and 15 single nucleotide polymorphism (SNP) loci. Four linkage groups were resolved and these were anchored to chromosomes X and 2 and chromosomal arms 3R and 3L by comparison with a physical map of this species. Five markers were linked to the X chromosome, 16 markers to chromosome 2, and 10 and 11 markers to chromosomal arms 3R and 3L, respectively. This significantly increases the number of chromosomally defined genetic markers for this species and will facilitate the identification of genes controlling epidemiologically important traits such as resistance to insecticides or vector competence.
[Analysis of spontaneous and ethylmethanesulfonate-induced visible mutations in the genetically unstable MS, w strain of Drosophila melanogaster].
We analyzed genetic effects of ethylmethanesulfonate (EMS) on mature sperm of males of the Drosophila melanogaster MS, w strain. The frequency of induced mutations was estimated in the X chromosome, in five loci of chromosome 2 (b, j, pr, cn, and vg), and in eight loci of chromosome 3 (ru, h, th, st, cu, sr, es, and ca). Mutability was significantly increased in the genetically unstable MS, w strain in comparison with the reference laboratory ss, w strain. In MS, w, genetic instability was characteristic of more than 50% EMS-induced mutations. Analysis of the mutation spectrum revealed a specific distribution along the chromosomes. In MS, w, exhibition of spontaneous and induced instability was shown to be similar. This could imply a common mechanism of control of mutability involving transpositions of mobile genetic elements.
Inherited semisterility for control of harmful insects. II. Degree of sterility and types of translocations in the mosquito Culex pipiens L.
Explore the source record for details and available documents.
Systematic gene targeting on the X chromosome of Drosophila melanogaster.
The genome of the model organism Drosophila melanogaster has been sequenced and annotated. Based on this groundwork, we performed a systematic genetic screen of the D. melanogaster X chromosome, which carries about one sixth of the genes of the organism. We generated a collection of single P-element insertions to provide genetic and molecular access to virtually all X-chromosomal genes. The study complements earlier work designed to systematically identify vital genes on the X chromosome by targeting transcription units which are phenotypically silent. We describe single UAS sequence-bearing P-element insertions throughout the X chromosome, which allows one to express the tagged genes under control of tissue/organ-directed GAL4 activity. In addition, the present collection of single insertion lines provides a tool to generate chromosomal deletions which are on average less than 33 kb in size.
Gene mapping and cross-resistance in cyclodiene insecticide-resistant Drosophila melanogaster (Mg.).
Resistance to the cyclodiene insecticide dieldrin maps to a single gene (Rdl) on the left arm of chromosome III in Drosophila melanogaster (Meigen). The gene was further mapped by the use of chromosomal deficiencies to a single letter sub-region, 66F, on the polytene chromosome. The cross-resistance spectrum of a backcrossed strain lacking elevated mixed function oxidase activity, a common resistance mechanism, was examined. Levels of resistance similar to those found in other insects were found to dieldrin, aldrin, endrin, lindane, and picrotoxinin. Strong similarity of this single major gene with that found in other cyclodiene resistant insects is suggested by its cross-resistance spectrum and chromosomal location, via homology with other Diptera. The significance of major genes in insecticide resistance is discussed.
Insect molecular biology on Crete.
Explore the source record for details and available documents.
Population control potential of heterozygous translocations as determined by computer simulations.
A possible method for genetic control of insect vector species involves the use of translocation heterozygotes. The potential of single and double heterozygotes already available in Aedes aegypti has been investigated with computer simulations of release strategies. Such simulations indicate a possible role for translocation heterozygotes of these types in an insect population characterized by a 5-fold population growth per generation, or less.
[Investigation of different dosages of inserted Bt genes and their insect-resistance in transgenic Bt cotton].
The plants with various dosages of inserted Bt genes were developed by intercrossing among transgenic Bt lines in which Bt genes were inserted in different chromosomes, and commercial non-transgenic Bt varieties. Laboratory bioassay of insect-resistance and Bt toxin protein assays with ELISA were used to detect efficacy to bollworm in different cotton growing stages. As transgenic Bt insect-resistant cotton, temporal difference of resistance existed in plants converging on different dosages of inserted Bt genes, i.e., there was a declining level of efficacy with plant age as the mortality (%) of Helicoverpa and Bt toxin protein expressional level decreased gradually, when analyzed with leaves from the main stem. Our research also revealed that the insect-resistance of converging 4 Bt genes plants was decreased due to homozygous suppression.