bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of ribosomal DNA in Rhagoletis pomonella (Diptera: Tephritidae) by in situ hybridization
Authors: Procunier W. S. , Smith J. J. 
Published: December 2007

AbstractThe ribosomal DNA (rDNA) of Rhagoletis pomonella was localized within both salivary gland polytene chromosomes and somatic cell mitotic chromosomes by in situ hybridization using the heterospecific Drosophila melanogaster rDNA clone, Dm238. In situ hybridization analysis of polytene nuclei showed that R pomonella rDNA is located in the nucleolus and adjacent granular network of chromosome 1. The site of origin of rDNA is within this isomorphic granular network. The preservation of nucleolar ultrastructure in some polytene chromosome preparations allowed light microscope localization of R. pomonella rDNA to the apparent periphery of fibrillar centres within fibrillar complexes. In somatic cell nuclei, DM238 hybridized to the nucleolus organizing region (NOR) located on chromosome 1 at the site of the secondary constriction. The frequency distribution of heteromorphisms for rDNA content, differential appearance of secondary constrictions, non‐pairing of the NOR and differences in homologue lengths suggests that the structural differentiation of this region in chromosome 1 is sex linked. This the first published description of the salivary gland polytene chromosomes from R. pomonella, and we include a tentative karyotype description, polytene chromosome maps and comments on their suitability for banding and molecular analysis.
Cloning and analysis of the locus for mosquito vitellogenic carboxypeptidase
Authors: Deitsch K. W. , Raikhel A. S. 
Published: December 2007

AbstractVitellogenic carboxypeptidase is a 53 kDa yolk protein produced by the fat body of the female mosquito, Aedes aegypti, in response to a blood meal. Its expression is sex‐, stage‐ and tissue‐specific and is identical to that of the major yoik protein, vitellogenin. The gene is intronless and two alleles have been cloned and sequenced, including more than 1.5 kb on both sides of the coding region. A capsite consensus recently identified as an arthropod initiator is present at the start site of transcription. Upstream of this capsite is a 16 bp imperfect palindrome repeated four times showing strong homology to defined hormone‐response elements. In addition, a region that closely resembles the fat body enhancer and double sex binding site from the Drosophila yolk protein genes and several potential fat body‐specific regulatory protein binding sites were found.
The internal transcribed spacers of ribosomal DNA in five members of the Anopheles gambiae species complex
Authors: Paskewitz S. M. , Wesson D. M. , Collins F. H. 
Published: December 2007

AbstractThe primary and secondary structure of the internal transcribed spacers of ribosomal DNA (ITS1 and ITS2) and their utility for phylogenetic analysis of closely related species were examined using the Anopheles gambiae complex as a model. Restriction mapping revealed an unusual architectural feature in the ITS1 of several members of an An. gambiae cryptic species complex. Multiple spacer lengths are prevalent in An. merus and An. melas and are due to variable numbers of a repeated 250 bp sequence. Secondary structure analysis indicated that the repeat forms a helix and loop that may be involved in rDNA processing. Intra‐and interspecific polymorphism within the species complex were further examined by DNA sequencing of forty‐eight ITS2 clones obtained by polymerase chain reaction from individuals of the five species. Interspecies variation in the approximately 426 bp ITS2 sequence ranged between 0.4% and 1.6%; intraspecies variation ranged from 0.07% in An. arabiensis to 0.43% in An. gambiae. lntraindividual variation ranged from 0% in four individuals to a high of 0.4% in one An. quadriannulatus specimen. None of the variants were shared between species. The low level of variation supports the hypothesis that species of the complex evolved recently.
Chromosomal mapping of two loci affecting filarial worm susceptibility in Aedes aegypti
Authors: Severson D. W. , Mori A. , Zhang Y. , Christensen B. M. 
Published: December 2007

AbstractTwo quantitative trait loci (QTL) affecting susceptibility of the mosquito Aedes aegypti to the filarial worm parasite Brugia malayi were identified using restriction fragment length polymorphism (RFLP) markers. The first locus, fsb[1,LF178], resides within a 10 cM interval on chromosome 1 and exhibits a recessive effect with respect to susceptibility. The second locus, fsb[2,LF98], resides within a 9 cM interval on chromosome 2 and exhibits an additive effect on susceptibility. Significant epistasis was detected between these loci, although the effect of fsb[2,LF98] was dependent on the genetic background of the mosquito strains. Suggestions for a standard QTL nomenclature are included.
Evolutionary origin of whiteflies (Hemiptera: Sternorrhyncha: Aleyrodidae) inferred from 18S rDNA sequences
Authors: Campbell B. C. , Steffen‐Campbell J. D. , Gill R. J. 
Published: December 2007

AbstractPhylogenetic analysis of 18S rDNA nucleotide sequences of hemipteran exemplars shows Sternorrhyncha (psyllids, whiteflies, aphids and scales) is monophyletic and forms a sister group to all other hemipterans (Euhemiptera). Whiteflies form a sister group to aphids and scales. Psyllids form a sister group to all other Sternorrhyncha. Primary structures of 18S rDNAs of all sternorrhynchans are exceptionally long (˜2200 to ˜2500 bp) due to internal expansions. These expansions are a synapomorphy of Sternorrhyncha; other hemipterans possess shorter 18S rDNAs (˜1900 to ˜1925 bp). The 18S rDNA of whiteflies is the longest recorded to date and has a base substitution rate of ˜3 times greater than Euhemiptera taxa examined. The relevance of these findings to the fossil record, feeding strategies, reproductive biologies, and geoclimatic distribution is discussed.
The peach‐potato aphid Myzus persicae and the tobacco aphid Myzus nicotianae have the same esterase‐based mechanisms of insecticide resistance
Authors: Field L. M. , Javed N. , Stribley M. F. , Devonshire A. L. 
Published: December 2007

AbstractBiochemical and molecular studies have established that in the peach‐potato aphid, Myzus persicae, insecticide resistance is conferred by amplification of genes encoding the insecticide‐detoxifying esterases E4 or FE4. Here we report that two insecticide‐resistant clones of the closely related tobacco aphid Myzus nicotianae have elevated esterases indistinguishable from E4 and FE4 and amplified esterase DNA sequences, and flanking regions, with identical restriction maps to the M. persicae genes. Furthermore, the DNA sequences of c. 630 bp fragments of the E4 and FE4 genes of M. persicae are different from each other but identical to the fragment from corresponding M. nicotianae clones. The existence of apparently identical insecticide resistance genes in the two species can be best explained by the selection of the amplified genes in M. persicae, transfer to hybrids of M. persicae and M. nicotianae by sexual reproduction and subsequent spread through M. nicotianae populations.
Isolation of a trypsin‐like serine protease gene family from the sheep blowfly Lucilia cuprina
Authors: Casu R. E. , Jarmey J. M. , Elvin C. M. , Eisemann C. H. 
Published: December 2007

AbstractVarious protease inhibitors active against both trypsin‐ and chymotrypsin‐like serine proteases were used to characterize gut proteases from Lucilia cuprina by in vitro feeding assays. Significant larval growth retardation was observed on feeding first‐instar larvae with trypsin inhibitors, particularly soybean trypsin inhibitor. Feeding of chymostatin, a specific chymotrypsin inhibitor, resulted in no significant growth retardation. This information suggests that trypsin‐like serine proteases are probably the major gut digestive enzymes. A DNA fragment obtained by PCR which coded for part of a putative trypsin gene from L. cuprina was used to isolate a four‐member multigene family of trypsins. The full nucleotide sequence of one of the genes and partial sequence from the other three genes were determined. Transcription of at least one of the genes has been confirmed. All four of the genes appear to have arisen by two separate gene duplication events.
Comparative linkage maps for the mosquitoes, Aedes albopictus and Ae. aegypti, based on common RFLP loci
Authors: Severson D. W. , Mori A. , Kassner V. A. , Christensen B. M. 
Published: December 2007

Abstract Aedes albopictus and Aedes aegypti are members of the mosquito family Culicidae and share a haploid chromosome complement of three. Although a genetic linkage map based on restriction fragment length polymorphism (RFLP), markers exists for Ae. aegypti, the extent of synteny and linkage order conservation between the two species was unknown. A comparative linkage map for Ae. albopictus was constructed based mainly on cDNA clones from Ae. aegypti. Nearly all Ae. aegypti probes hybridized to Ae. albopictus DNA at high stringency. For eighteen RFLP markers tested, the linkage group and linear order appears to be identical for the two species. 78% of the loci tested exhibited significant deviations from the expected segregation ratio in at least one of the test crosses. An excess of heterozygote genotypes was recovered with most loci. This probably reflects the effects of lethal loci on survival of F2 progeny homozygous for the parental genotypes. These results demonstrate that comparative linkage maps based on common DNA markers provide a basis for rapidly developing linkage maps for various mosquito species, and the opportunity to examine the significance and function of orthologous quantitative trait loci associated with mosquito vector competence for disease transmission.
Molecular mechanisms involved in increased expression of a cytochrome P450 responsible for pyrethroid resistance in the housefly, Musca domestica
Authors: Tomita T. , Liu N. , Smith F. F. , Sridhar P. , Scott J. G. 
Published: December 2007

AbstractCytochrome P450Ipr is a developmentally regulated P450 responsible for monooxygenase‐mediated pyrethroid resistance in the LPR strain of housefly. CYP6D1, the gene coding for P450iIpr, has recently been sequenced. We investigated the molecular basis for CYP6D1‐mediated pyrethroid resistance by comparison of mRNA levels, gene sequences, and gene copy number between LPR and pyrethroid susceptible strains of housefly. CYP6D1 mRNA levels were elevated in the LPR strain to a similar level as P450Ipr protein, suggesting that over‐expression of this important P450 in the resistant strain is probably due to increased transcription. Southern blots of susceptible and LPR strain DNA suggest that gene amplification is probably not involved in the increased expression of CYP6D1 protein. Five alleles of CYP6D1 were discovered and their possible role in resistance is discussed.
Parthenogenesis‐inducing microorganisms in Aphytis (Hymenoptera: Aphelinidae)
Authors: Zchori‐Fein E. , Faktor O. , Zeidan M. , Gottlieb Y. , Czosnek H. , Rosen D. 
Published: December 2007

AbstractProduction of males in uniparental lines of two species in the parasitic wasp genus Aphytis was induced by rifampicin, and male sexual functioning was determined. Wolbachia‐specific 16S rDNA primers were used in a PCR in order to: (1) assess correlation between thelytokous reproduction and the presence of Wolbachia; (2) detect the loss of Wolbachia DNA in uniparental A. lingnanensis following antibiotic treatments, with or without the presence of a host; and (3) clone and sequence part of the Wolbachia 16S rDNA from the uniparental Aphytis species for phylogenetic studies. Males produced viable sperm that was transferred to the female spermatheca following mating. However, sperm failure to effect egg fertilization resulted in all‐male progeny. Wolbachia were found in the two uniparental (A. lingnanensis and A. diaspidis) but not in the two biparental (A. lingnanensis and A. melinus) Aphytis lines tested. They can be detected in wasps up to 7 days following antibiotic treatments, regardless of the presence of host. The 16S rDNA for the symbionts in the two Aphytis species is virtually identical, and is most closely related to the Wolbachia found in Muscidifurax uniraptor (Pteromalidae).
A single isoform of the Na+/K+‐ATPase α‐subunit in Diptera: evidence from characterization of the first extracellular domain
Authors: Emery A. M. , Ready P. D. , Billingsley P. F. , Djamgoz M. B. A. 
Published: December 2007

AbstractThe first extracellular domain of the α‐subunit of the Na+/K+‐ATPase (sodium/potassium pump) is functionally important, affecting sensitivity of the enzyme to cardiac glycosides (e.g. ouabain) and being implicated in the transport of K+. This domain is also variable among mammalian isoforms of the α‐subunit. Using PCR, we have isolated from seven insect species with contrasting physiologies a DNA fragment containing this region, in order to help determine whether tissue‐specific expression might be associated with isoforms encoded by a gene family, as it is in mammals. A single sequence (with one ORF) characteristic of Na+/K+‐ATPase was obtained from genomic DNA of each species. Only the fragment from Manduca sexta contained an intron, but at a location different to that found in mammals. For all Diptera so far characterized, the species phylogeny is the same as the α‐subunit gene phylogeny (based on the sequences of the first extracellular domain and flanking transmembrane domains). The results strongly indicate a single, ouabain‐sensitive isoform of the α‐subunit of Na+/K+‐ATPase is present in Diptera.
PCR primers for the amplification of four insect mitochondrial gene fragments
Authors: Kambhampati S. , Smith P. T. 
Published: December 2007

AbstractInsect mitochondrial genome (mtDNA) analysis is a powerful tool for the study of population genetics and phylogenetics. In the past few years primer sequences for the PCR amplification of various insect mtDNA genes have been published. The objectives of this study were (1) present new primer sequences for six insect mitochondrial genes and (2) test primers designed in our laboratory and some previously published primers on a wide range of insects to determine if amplification of the target fragment could be obtained. The primers for the amplification of the two ribosomal RNA gene (16S and 12S rRNA) fragments are universal for insects and related groups; the primers for NADH5 and NADH4 dehydrogenase gene fragments and cytochrome c oxidase I gene fragment are applicable broadly.
Isolation and characterization of a retroelement from B chromosome (PSR) in the parasitic wasp Nasonia vitripennis
Authors: McAllister B. F. 
Published: December 2007

AbstractMolecular characterization of the paternal‐sex‐ratio (PSR) chromosome in Nasonia vitripennis (Hymenoptera: Pteromalidae) has led to the isolation of a dispersed repetitive element. The element is a LTR‐containing retrotransposon which has been named NATE (NAsonia Transposable Element). NATE has direct terminal repeats and has an internal amino acid sequence similar to reverse transcriptases of other retroelements. Phylogenetic analysis indicates NATE is a member of the Gypsy/Ty3 group of retrotransposons, and represents the first isolated from Hymenoptera. Five closely related copies of NATE were isolated from the PSR chromosome, but cross‐hybridizing elements were not detected on the autosomes of N. vitripennis. Strongly cross‐hybridizing elements were, however, detected in two other Nasonia species. This observed distribution of NATE is interesting, because the supernumerary PSR chromosome may be derived from the genome of a sibling species of N. vitripennis.
Molecular characterization of the Anopheles gambiae 2L telomeric region via an integrated transgene
Authors: Biessmann H. , Donath J. , Walter M. F. 
Published: December 2007

AbstractA Drosophila P‐element derivative (pUChsneo) integrated into the telomeric region of the left arm of the second chromosome of Anopheles gambiae was used to clone the proximally flanking An. gambiae sequences. Molecular analyses revealed that the pUChsneo construct was partially duplicated and had integrated into a subterminal minisatellite. This satellite has a repeat unit of 820 bp and is located exclusively at the tip of 2L. No sequence similarity to subterminal minisatellites from other dipterans was detected, but some structural features such as tandem subrepeats are shared. The end of the chromosome was mapped with respect to restriction sites in pUChsneo at approximately generation 100 after the integration event. Considering inevitable terminal nucleotide loss due to incomplete DNA replication, we conclude that the chromosome end must have undergone a dramatic elongation process since it was mapped in generation 23.
Evolution of the mitochondrial DNA control region in the Anopheles gambiae complex
Authors: Caccone A. , Garcia B. A. , Powell J. R. 
Published: December 2007

AbstractWe have sequenced the AT‐rich control region of the mitochondrial DNA (mtDNA) of six species in the Afrotropical Anopheles gambiae complex and the closely related A. christyi. Contrary to expectations, the AT‐rich region in this group is evolving rather slowly, more slowly than the third position of mtDNA proteincoding genes. Despite being relatively conserved between species, we detected intraspecific and intra‐individual (heteroplasmy) variation in this region. Phylogenetically, we found we could place the rare endemic A. bwambae as a sister taxon to A. melas, the same evolutionary position as indicated by chromosomal inversions. The outgroup, A. christyi, gave evidence of the root of the tree. In comparing the molecular trees with that deduced by chromosomal inversions, they are completely congruent with the exception of the placement of A. arabiensis. The anomalous position of this species can be explained by introgression with A. gambiae. From the phylo‐genetic position, we could infer mtDNA gene flow from A. gambiae to A. arabiensis.
The polyubiquitin gene of the mosquito Anopheles gambiae: structure and expression
Authors: Beard C. B. , Cornel A. J. , Colllns F. H. 
Published: December 2007

AbstractThe polyubiquitin gene from the mosquito Anopheles gambiae has been cloned and sequenced, and its stucture is reported along with sequence analysis results. The gene consists of approximately seven tandem head‐to‐tail repeat units of the seventy‐six amino acid‐coding ubiquitin monomer. It is expressed constitutively in larvae, pupae and adults of An. gambiae, as well as in a cell line derived from this mosquito species. A probe made from a DNA fragment containing the coding region of the gene recognizes transcripts of approximately 3.6 kb and 4.4 kb in RNA isolated from all mosquito developmental stages and a unique transcript of approximately 3.0 kb in RNA from the cell line. Single monomeric units of the An. gambiae polyubiquitin gene shared from 75.9% to 85.5% identity at the DNA level with homologous sequences from other organisms ranging from yeast to man. A comparison of individual repeat units of the An. gambiae gene revealed that, in general, the 5′ ends of the individual monomers are more highly conserved than the 3 ends. The gene mapped by in situ hybridization on ovarian nurse cell polytene chromosomes to a primary site at division 12C on chromosome 2R and to a secondary site at division 9C on the same chromosome.
Sequence and secondary structure of the rDNA second internal transcribed spacer in the sibling species Culex pipiens L. and Cx. quinquefasciatus Say (Diptera: Culicidae)
Authors: Severini C. , Sllvestrlnl F. , Manclnl P. , Rosa G. La , Marlnucci M. 
Published: December 2007

AbstractThe primary and secondary structure of the second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) of two members of the Cx. pipiens complex, Cx. pipiens and Cx. quinquefasciafus, were examined in order to better understand the relationships between these two sibling mosquito species. The length of the sequenced rDNA fragments was 512 bp (Cx. pipiens) and 513 bp (Cx. quinquefasciatus), including the ITS2 regions and flanking 5.8S‐28S coding regions. The ITS2 sequences of Cx. pipiens and Cx. quinquefasciatus were 297 and 298 bp in length respectively and showed a 97% identity. In fact, they had identical G + C content (58%) and the only differences observed are six mismatches (three transitionslthree transversions), six single‐base and one triple‐base deletions/insertions. The observed ITS2 secondary structures of Cx. pipiens and Cx. quinquefasciafus were very similar. Furthermore, the ITS2 sequences of specimens belonging to three populations of Cx. pipiens from Italy and four populations of Cx. quinquefasciatus (three from Africa and one from North America) were enalysed in order to detect the presence of potential species‐specific diagnostic restriction sites.
Molecular identification of a Wolbachia endosymbiont in a Tetranychus urticae strain (Acari: Tetranychidae)
Authors: Tsagkarakou A. , Gulllemaud T. , Rousset F. , NavaJas M. 
Published: December 2007

Abstract Wolbachia, a maternally lnherlted bacierium, is Involved In alterations of arthropod sexuality. Reproductive incompatlbllities are often observed in mites, but the existence of this microorganism In their cytoplasm has not yet been demonstrated. We Identified the presence of Wolbachia In a strain of the spider mite Tetranychus urticae based on the ampllflcatlon and sequencing of part of the 16S rDNA and ftsZ genes. In order to establish the phylogenetlc relationships between Wolbachia found In T. urticae and In other arthropods, we aligned the resulting sequences with already published ones. For both 16s and ftsZ genes the Wolbachia carried by T. urticae clustered together with Wolbachia found in other arthropods.
Phylogenetic relationship among termite families based on DNA sequence of mitochondrial 16S ribosomal RNA gene
Authors: Kambhampati S. , Kjer K. M. , Thorne B. L. 
Published: December 2007

AbstractTermites (Order isoptera: Class Insecta), are comprised of a complex assemblage of species, with considerable variation in life history, morphology, social behaviour, caste development and ecology. At present, isoptera is divided into seven families, fourteen subfamilies, ∼ 270 genera and over 2000 species. Phylogenetic hypotheses currently available for termite families and genera are based on a limited number of morphological characters and lack rigorous cladistic analysis. In this paper we report on phylogenetic relationships among ten termite genera of five families based on a DNA sequence analysis of a portion of the mitochondrial 16S rRNA gene. Parsimony and distance analysis of DNA sequences supported the existing hypothesis that Mastotermitidae is the basal lineage among extant termites. Kalotermitidae was not found to be a sister taxon of Mastotermitidae as existing hypotheses suggest, but was most closely related to Rhinotermitidae and Termitidae. Representatives of Termopsidae were more basal relative to those of Kaiotermitidae. The utility of 16S rRNA nucieotide sequence analysis for inferring phylogenetic relationships among termite families, subfamilies and genera is discussed.