bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of induction of complement susceptibility of erythrocytes by spider and bacterial sphingomyelinases
Authors: Tambourgi Denise V. , De Sousa Da Silva Marcelo , Billington Stephen J. , Gonçalves De Andrade Rute M. , Magnoli Fábio C. , Songer J. Glenn , Van Den Berg Carmen W. 
Published: March 2003

SummaryWe have recently shown that the sphingomyelinase toxins P1 and P2 from the venom of the spider Loxosceles intermedia induce complement (C)‐dependent lysis of autologous erythrocytes by induction of the cleavage of cell surface glycophorins through activation of an endogenous metalloproteinase facilitating the activation of the alternative pathway of C. Phospholipase D (PLD) from Corynebacterium pseudotuberculosis shows some degree of homology with the spider sphingomyelinases and can induce similar clinical symptoms to those observed after spider envenomation. The aim of this study was to investigate if the bacterial PLD‐induced haemolysis of human erythrocytes was C dependent and if cleavage of glycophorins occurred. We show here that haemolysis of both PLD‐ and P1‐treated human erythrocytes was C dependent, but while PLD‐mediated haemolysis was dependent on activation of the classical pathway of C, P1 induced lysis via both the classical and alternative pathways. P1, but not PLD, induced cleavage of glycophorins and no change in expression of complement regulators was induced by either of the toxins. In both cases, annexin V binding sites were exposed, suggesting that the membrane asymmetry had been disturbed causing exposure of phosphatidylserine to the cell surface. Our results suggest that C susceptibility induced by L. intermedia and C. pseudotuberculosis PLD is a result of exposure of phosphatidylserine, and the higher potency of P1 toxin can be explained by its additional effect of cleavage of glycophorins.
Life and death within germinal centres: a double‐edged sword
Authors: Guzman‐Rojas Liliana , Sims‐Mourtada Jennifer C. , Rangel Roberto , Martinez‐Valdez Hector 
Published: March 2003

SummaryWithin germinal centres, B lymphocytes are destined to die by apoptosis via Fas signalling, unless they are positively rescued by antigen and by signals initiated by CD40–CD154 interactions. Thus, while the germinal centre microenvironment can become a virtual graveyard for most B lymphocytes that fail to bind antigen with high affinity, it concomitantly provides the necessary stimuli for the survival of cells that successfully accomplish affinity maturation. Such dichotomy in the physiology of germinal centre reaction that results in survival of the functional B‐cell repertoire and the elimination of abnormal cells, dictates the fate towards B‐cell homeostasis or disease. Consequently, the death and survival‐signalling arms within germinal centres predominantly reside on the timely and controlled expression of Fas and its ligand (FasL), and CD40 and CD154, respectively. In keeping with this notion, lymphoproliferation or deficient immunity are documented landmarks of inactivation of either the Fas/FasL or CD40/CD154 signalling pathways. The present review considers two different scenarios in the control of B‐cell survival and death within germinal centres. The first is an idealistic scenario, in which a discriminatory and co‐ordinate signalling initiated by the CD40/CD154 and Fas/FasL pairs, respectively, leads the rescue of the functional B‐cell repertoire and the elimination of the abnormal phenotype. The second is a gloomy scenario in which both the lack and the hyperexpression of either receptor/ligand pairs, are seen as equally deleterious.
Inducible nitric oxide synthase deficiency in mice increases resistance to chronic infection with Echinococcus multilocularis
Authors: Dai Wen J. , Waldvogel Andreas , Jungi Thomas , Stettler Marianne , Gottstein Bruno 
Published: March 2003

SummaryThe production of nitric oxide (NO) by intraperitoneal macrophages of mice during secondary infection with Echinococcus multilocularis mediates immunosuppression at early and late stages of infection. We addressed the role of NO in host resistance against this extracellular metazoan parasite by infecting inducible nitric oxide synthase knockout ((iNOS‐KO) mice (of the C57BL/6 background) with 100 metacestode vesicles. The parasite weight was significantly lower in iNOS‐KO mice when compared with wild‐type (WT) mice at 4 months postinfection (late stage), thus demonstrating that iNOS deficiency confers a certain degree of resistance against persistent chronic infection. However, histological analysis of periparasitic tissue showed no differences between WT and iNOS‐KO mice, as both exhibited granuloma formation and the presence of giant cells. Together with histology, the production of a high level of interferon‐γ (IFN‐γ) in infected iNOS‐KO mice upon stimulation with concanavalin A (Con A) and VF‐antigen indicated normal T‐cell signalling in these animals. As expected, peritoneal exudate cells (PEC) from infected iNOS‐KO mice produced no detectable NO, while the PEC from infected WT mice produced high levels of NO after stimulation with lipopolysaccharide (LPS) and parasite protein or carbohydrate antigen, or even without in vitro stimulation. Consequently, the high level of NO production observed during chronic infection in WT mice appears to contribute more to immunosuppression than to limitation of parasite growth. This is also reflected by the fact that splenocyte proliferation was significantly higher and parasite masses lower in iNOS‐KO mice (at 1 and 4 months postinfection) than in WT mice.
Phenotypic profile and functional characterization of rat lymph node‐derived γδ T cells: implication in the immune response to cytomegalovirus
Authors: Dyugovskaya Larissa , Hirsh Mark , Ginsburg Haim 
Published: March 2003

Summaryγδ T cells are unique, and their localization at sites of infection is considered critical in immune defence. We demonstrate the accumulation of γδ T cells in rat regional popliteal lymph nodes (PLNi) starting 2 days after inoculation of cytomegalovirus (CMV) into the footpad. Early‐appearance PLNi γδ T cells significantly inhibited plaque development and the spread of CMV infection. These γδ T cells were negative for CD4 and CD8beta receptors, proliferated in response to interleukin‐2 (IL‐2) and contained high levels of interferon‐γ (IFN‐γ), the appearance of which correlated with the curing of fibroblasts from virus infection. The addition of anti‐IFN‐γ abolished the ability of fibroblast monolayers to be cured from CMV infection. In contrast, this protection was not abolished by the addition of anti‐rat IL‐2 or anti‐rat TNF‐α, or by the depletion of NKR‐P1‐bearing cells within γδ T cells. In addition, the present study shows that while γδ T cells derived from naive and CMV‐infected rats are able to kill both YAC‐1 targets and CMV‐infected syngeneic fibroblasts in vitro, only the latter are able to clear CMV‐infected fibroblast monolayers. Finally, our data suggest that the expression of NKR‐P1 by γδ T cells is critical for cytotoxicity, but its contribution to the curing from CMV infection was limited.
Assessing and managing the benefits of enterprise systems: the business manager's perspective
Authors: Shang Shari , Seddon Peter B 
Published: March 2003

Abstract.This paper focuses on the benefits that organizations may achieve from their investment in enterprise systems (ES). It proposes an ES benefit framework for summarizing benefits in the years after ES implementation. Based on an analysis of the features of enterprise systems, on the literature on information technology (IT) value, on data from 233 enterprise systems vendor‐reported stories published on the Web and on interviews with managers of 34 organizations using ES, the framework provides a detailed list of benefits that have reportedly been acquired through ES implementation. This list of benefits is consolidated into five benefits dimensions: operational, managerial, strategic, IT infrastructure and organizational, and illustrated using perceived net benefit flow (PNBF) graphs. In a detailed example, the paper shows how the framework has been applied to the identification of benefits in a longitudinal case study of four organizations.
Ribosomal protein L5 of Bombyx mori: cDNA sequence and tissue differences in the L5 mRNA content
Authors: Yang C. , Sehnal F. 
Published: March 2003

AbstractA gene encoding the ribosomal protein L5, which assembles with the 5S rRNA into one of the components of the 60S ribosomal subunit, was identified in insects for the first time. We report on the isolation of Bombyx mori cDNA, whose putative translation product is 60–76% identical with the L5 sequences known from other animals and about 50% identical with the L5 of rice and yeasts. Bombyx contains a single copy of the L5 gene, which is constitutively expressed as a 1.1 kb mRNA in all tissues. The ratio of L5 mRNA to total RNA appears to reflect the proteosynthetic tissue capacity. A very high level of L5 mRNA is maintained in functional silk glands. A rapid decline of the ratio of L5 mRNA to the rRNA, which occurs in the silk glands after cocoon spinning, indicates differences in the stability of these two RNA classes.
Amplification of a serine esterase gene is involved in insecticide resistance in Sri Lankan Culex tritaeniorhynchus
Authors: Karunaratne S. H. P. P. , Vaughan A. , Paton M. G. , Hemingway J. 
Published: March 2003

AbstractCulex tritaeniorhynchus, the major vector of Japanese encephalitis in Sri Lanka, is resistant to organophosphorus insecticides, with a 10‐fold resistance ratio at the LC50 for chlorpyrifos, and a high heterogeneity factor in the insect field population. The major mechanism of resistance in this species, as in the mosquito C. quinquefasciatus, is elevation of esterase activity. Basic biochemical, immunological and molecular analysis suggests that the C. tritaeniorhynchus CtrEstβ1 gene is orthologous to the C. quinquefasciatus amplified Est7beta;s. The Estβ21 antiserum cross‐reacts strongly with CtrEstβ11. Its corresponding cDNA, over the 545 base pairs sequenced, has ∼84% identity with the various C. quinquefasciatus Estβs. The gene is amplified in C. tritaeniorhynchus. Amplification of the same esterase in two independent species, along with multiple amplification events involving this esterase gene in C. quinquefasciatus suggests that the location of this gene within the genome predisposes it to amplification.
Phylogenetic analysis of parthenogenesis‐inducing Wolbachia in the genus Aphytis (Hymenoptera: Aphelinidae)
Authors: Gottlieb Y. , Zchori‐Fein E. , Faktor O. , Rosen D. 
Published: March 2003

AbstractParthenogenesis‐inducing intracellular bacteria of the genus Wolbachia are found in a variety of parasitoid wasp genera. The presence of Wolbachia in the uniparental Aphytis species A. fingnanensis Compere, A. diaspidis (Howard), A. chilensis Howard, and A. chrysomphali (Mercet) was tested using primers specific for the ftsZ gene. The symbiont was detected in all of these species. Wolbachia ftsZ genes that were sequenced from the four hosts show a high degree of similarity. Both the PCR with specific primers for group ‘A’ and phylogenetic analysis place these Wolbachia in group ‘A’. The fact that the tested Aphytis species belong to different phylogenetic groups and harbour what seem to be almost identical Wolbachia, lends credence to the horizontal transmission hypothesis.
Phylogenetic relationships of seven palearctic members of the maculipennis complex inferred from ITS2 sequence analysis
Authors: Marinucci M. , Romi R. , Mancini P. , Luca M. Di , Severini C. 
Published: March 2003

AbstractThe sequences of the second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) were determined from seven palearctic mosquitoes species belonging to the Anopheles maculipennis species complex, namely An. atroparvus, An. labranchiae, An. maculipennis, An. messeae, An. melanoon, An. sacharovi and An. martinius. The length of the ITS2 ranged from 280 to 300 bp, with a GC content of 49.4–54.1%. With the exception of An. messeae, negligible levels of intraspecific polymorphism and no intrapopulation variation were observed. The phylogenetic relationships among the members of the maculipennis complex were inferred by maximum‐parsimony analysis of the
paup program and the neighbour‐joining and maximun‐likelihood analysis of the
phylip program. All of the trees obtained were almost identical in topology, although the relationships among three species, i.e. An. maculipennis, An. messeae and An. melanoon, remained unresolved. The phylogenies were in good agreement with the previous gene–enzyme and polytene chromosome banding pattern studies.
Comparative analysis of promoters for transient gene expression in cultured mosquito cells
Authors: Zhao Y‐G. , Eggleston P. 
Published: March 2003

AbstractThree heterologous promoters (hsp 70 and actin 5C from Drosophila melanogaster and IE1 from the immediate early gene of the Bombyx mori baculovirus) were assessed for their ability to drive transient luciferase expression in mosquito cells. Overall, the actin 5C promoter was considerably more effective at driving luciferase expression than either hsp70 or IE1 in cell lines derived from Anopheles, Aedes and Culex species. hsp70 functioned well when induced by heat shock and was also induced to a lesser extent by chemicals such as sodium arsenite. IE1 was also an effective initiator of transcription, particularly in two Anopheles cell lines, but generally it performed less well than the actin 5C promoter and was also outperformed by hsp70 in Anopheles gambiae cells.
Insect immunity: molecular cloning, expression, and characterization of cDNAs and genomic DNA encoding three isoforms of insect defensin in Aedes aegypti
Authors: Lowenberger C. A. , Smartt C. T. , Bulet P. , Ferdig M. T. , Severson D. W. , Hoffmann J. A. , Christensen B. M. 
Published: March 2003

Abstract Aedesaegypti were immune activated by injection with bacteria, and the expression of insect defensins was measured over time. Northern analyses indicated that defensin transcriptional activity continued for at least 21 days after bacterial injection, and up to 10days after saline inoculation. Mature defensin levels in the haemolymph reached approximately 45 μM at 24 h post inoculation. cDNAs encoding the preprodefensins of three previously described mature Ae. aegypti defensins were amplified by PCR, cloned and sequenced. Genomic clones were amplified using primers designed against the cDNA sequence. Sequence comparison indicates that there is significant inter–and intra–isoform variability in the signal peptide and prodefensin sequences of defensin genes. Preprodefensin sequences of isoforms A and B are very similar, consisting of a signal peptide region of twenty amino acids, a prodefensin region of thirty–eight amino acids and a forty amino acid mature peptide domain. The sequence encoding isoform C is significantly different, comprising a signal peptide region of twenty–six amino acids, and the mature protein domain of forty amino acids, Analysis of the genomic clones of each isoform revealed one intron spatially conserved in the prodefensin region of all sequences. The intron in isoforms A and B is 64 nt long, and except for a 4 nt substitution in one clone, these intron sequences are identical. The intron in isoform C is 76 nt long and does not share significant identity with the intron sequences of isoforms A or B. The defensin gene mapped to chromosome 3, between two known loci, blt and LF 168.
Precise excision and transposition of piggyBac in pink bollworm embryos
Authors: Thibault S. T. , Luu H. T. , Vann N. , Miller T. A. 
Published: March 2003

AbstractTransposable elements such as P, hobo, Hermes, mariner and Minos have been successfully harnessed as gene vectors to achieve the transformation of several dipteran species including Drosophila melanogaster, Ceratitis capitata and Aedes aegypti. Plasmid‐based excision and transposition assays have been useful indicators of an element's ability to be mobilized in vivo and thus potentially serve as a transforming vector. We report that the transposable element piggyBac is capable of precise excision and transposition in the pink bolloworm (Pectinophora gossypiella), a worldwide pest of cultivated cotton. Combined with a suitble marker gene, the piggyBac element may serve as a vector for germline transformation in this and (potentially) other lepidopteran species.
Phylogenetic relationships of phlebotomine sandflies inferred from small subunit nuclear ribosomal DNA
Authors: Aransay A. M. , Scoulica E. , Tselentis Y. , Ready P. D. 
Published: March 2003

AbstractRelationships among seventy specimens, fifteen species and three genera of phlebotomines were inferred from the phylogenetic analysis of small subunit nuclear rDNA, obtained by the PCR amplification and cloning of almost full‐length genes. Outgroups included fifteen dipterans, and single representatives of four other insect orders. The more distant the taxa compared, the larger were the regions of ambiguous sequence alignment that needed to be deleted in order to avoid circularity in performing parsimony analyses. Phlebotomine sequences formed a monophyletic clade within the suborder Nematocera, with the progressively more basal sister groups of Diptera being Culicomorpha, Tipulomorpha and the suborder Brachycera. Within Phlebotominae, subgeneric relationships were resolved and the genus Phlebotomus was shown to be monophyletic, but markers for intraspecific geographical populations were not found and intergeneric relationships were not resolved.
A gut‐specific serine protease from the malaria vector Anopheles gambiae is downregulated after blood ingestion
Authors: Shen Z. , Edwards M. J. , Jacobs‐Lorena M. 
Published: March 2003

AbstractA chymotrypsin‐like serine protease gene (AgChyL) was cloned from the mosquito Anopheles gambiae by a polymerase chain reaction (PCR)‐based subtractive cDNA cloning strategy. AgChyL messenger RNA (mRNA) is abundant in the adult female gut prior to, and for 8 h following, a blood meal. During the peak of digestion, from 12 to 24 h following a blood meal, AgChyL mRNA abundance decreased to barely detectable levels. AgChyL mRNA was abundant again by 48 h following a blood meal. Recombinant pro‐AgChyL was expressed in Escherichia coli. The pro‐enzyme can be activated by trypsin. Activated AgChyL cleaves the synthetic chymotrypsin substrate succinyl‐
l‐Ala‐Ala‐Pro‐Phe‐nitroanilide, but not two other synthetic chymotrypsin substrates or synthetic trypsin and elastase substrates. The potential role of AgChyL in the coordination of An. gambiae digestion is discussed.
Germ‐line transformation of pink bollworm (Lepidoptera: Gelechiidae) mediated by the piggyBac transposable element
Authors: Peloquin J. J. , Thibault S. T. , Staten R. , Miller T. A. 
Published: March 2003

AbstractThe pink bollworm, Pectinophora gossypiella, is a world‐wide pest of cultivated cotton. In certain growing regions populations are suppressed by a sterile release strategy. Efforts to improve the sterile insect technique as well as our understanding of lepidopteran biology could benefit greatly from a germ‐line transformation system. We report transformation of pink bollworm with a piggyBac transposable element carrying the enhanced green flourescent protein (EGFP) marker gene. This vector–marker system resulted in recovery of transgenics at a rate of approximately 3.5%. Integration of the transforming construct that was typical of piggyBac was demonstrated by Southern analysis and sequence determination of transposon flanks. Expression of the EGFP marker was visualized by fluorescent microscopy and Western Blot analysis. Maintenance of transformed strains indicates that the transgene segregates in a Mendelian fashion and has been stable over fourteen generations to date.
Genomic organization and immune regulation of the defensin gene from the mosquito, Anopheles gambiae
Authors: Eggleston P. , Lu W. , Zhao Y. 
Published: March 2003

AbstractThe defensin gene from the mosquito, Anopheles gambiae, is present as a single copy per haploid genome. Two exons, encoding a 102 residue preprodefensin, are separated by a 105 bp intron bounded by consensus splice sites. The upstream regulatory sequence includes a TATA box, arthropod initiator and numerous motifs homologous to insect and mammalian immune response elements. This promoter is capable of upregulation by immune challenge in cultured cells and activity is further stimulated by Gambif1, a mosquito Rel protein known to translocate to the nucleus and bind NF‐κB sites in target promoters. Activity is inhibited by p50, a mammalian Rel protein that competitively binds NF‐κB sites, and virtually abolished by p40, an avian IκB protein that inhibits nuclear translocation.
Immune activation upregulates lysozyme gene expression in Aedesaegypti mosquito cell culture
Authors: Gao Y. , Fallon A. M. 
Published: March 2003

AbstractAfter stimulation with heat‐killed bacteria, cultured cells from the mosquito Aedesaegypti (Aag‐2 cells) secreted an induced protein with a mass of ≈ 16 kDa that cross‐reacted with antibody to chicken egg lysozyme. To investigate whether lysozyme messenger RNA is induced in bacteria‐treated cells, we used polymerase chain reaction‐based approaches to obtain the complete lysozyme cDNA from Aag‐2 cells. The deduced protein contained 148 amino acids, including a 23 amino acid signal sequence. The calculated mass of the precursor protein is 16 965 Da, which is processed to yield a mature lysozyme of 14 471 Da with a calculated pI of 10.1. The lysozyme from Ae. aegypti shared 50% amino acid identity with lysozymes from Anophelesgambiae and Anophelesdarlingi, which in turn shared 70% identity between each other. Northern analysis with the lysozyme cDNA probe showed induction of a 1.3 kb messenger RNA during the first 3 h after treatment of Aag‐2 cells with heat‐killed bacteria, followed by maximal expression 12–36 h after treatment. Southern analysis suggested that the gene likely occurs as a single copy in the genome of Aag‐2 cells.
Microsatellite loci are not abundant in all arthropod genomes: analyses in the hard tick, Ixodes scapularis and the yellow fever mosquito, Aedes aegypti
Authors: Fagerberg A. J. , Fulton R. E. , Black Iv W. C. 
Published: March 2003

AbstractPlasmid libraries enriched for microsatellites were generated in the tick, Ixodes scapularis and in the mosquito Aedes aegypti. Libraries were enriched for genomic DNA containing (AC)n, (AG)n, (ATG)n, (CAG)n, (TAG)n, (AAT)n, (CTGY)n or (GATA)n motifs. Clones containing each motif were sequenced in both species for PCR primer design. In I. scapularis, most primers amplified a single locus and alleles varied in the number of microsatellite repeats and segregated as codominant markers. In contrast (AC)n, (TAG)n and (GATA)n microsatellite loci extracted from Ae. aegypti appeared to be members of multigene families. A primer pair designed to amplify a particular TAG locus instead amplified many independently segregating loci, some of which did not contain TAG microsatellites. Alleles at the TAG loci segregated as dominant markers and there was limited evidence for length variation among alleles. These results suggest that microsatellite loci are not universally abundant in arthropod genomes nor do alleles always segregate as codominant markers.