摘要:

AbstractInsect mitochondrial cytochrome oxidase I (COI) genes are used as a model to examine the within‐gene heterogeneity of evolutionary rate and Its implications for evolutionary analyses. The complete sequence (1537 bp) of the meadow grasshopper (Chorthippus parallelus) COI gene has been determined, and compared with eight other Insect COI genes at both the DNA and amino acid sequence levels. This reveals that different regions evolve at different rates, and the patterns of sequence variability seems associated with functional constraints on the protein. The COOH‐terminal was found to be significantly more variable than Internal loops (I), external loops (E), transmembrane helices (M) or the NH2 terminal. The central region of COI (M5‐M8) has lower levels of sequence variability, which Is related to several Important functional domains In this region. Highly conserved primers which amplify regions of different variabilities have been designed to cover the entire insect COI gene. These primers have been shown to amplify COI in a wide range of species, representing all the major insect groups; some even In an arachnid. Implications of the observed evolutionary pattern for phylogenetic analysis are discussed, with particular regard to the choice of regions of suitable variability for specific phylogenetic pro

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00049.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractTwo welldescribed elements of the Immune response of insects include encapsulation of metazoan parasites (blood‐cell‐mediated) and the production of antibacterial peptides (humoral and/or cellular). However, the possible functional interrelationship between cellular encapsulation and antibacterial responses, and the extent to which the two components may be co‐regulated, are poorly understood. We used a novel approach involving strains ofDrosophilaresistant (R) or susceptible (S) to the wasp parasitoldLeptopilina boulardito study the expression of three genes involved in the antibacterial response:Dorsal‐related immunity factor (Dil), Cecropin (CecA1) andDiptericin (Dip). Both S and R strains produced high levels of all antibacterial transcripts upon bacterial injection. However, when parasitized the R strain showed no induction whilst the S strain did. This lack of antibacterial transcript induction in the parasitized R strain not only clarifies the separation of these two types of immune response but also raises the fascinating possibility of a link in their genetic reg

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00050.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractOpsin is a G protein coupled photoreceptor that actlvates a signal transduction cascade in the ommatidia. Its primary and secondary structure Is conserved both In insects and vertebrates as exemplified by theDrosophiiaopslns. Through serendipitous cloning of a PCR fragment, we have Identified an opsln cDNA. The latter was used to clone full length cDNAs from a mosquito head library. the main purpose of cloning was to have a positive control probe to establish anIn situhybridization protocol for less abundant probes. Opsin‐mRNA is localized specifically to the visual receptor cells in the ommatida. No other cells in the brain or the remainder of the body are positive. This is confirmed by Northern blot analysis.The sequence of the receptor, of which we have found two different transcripts, confirms Its typical topology, including the seven transmembrane spanning regions and the intracellular carboxy terminus that has potential phosphorylatlon sites.Ourin situhybridization protocol combines several procedures: the most important points are: (a) the immediate processing of sections after cutting, and (b) the sections are never allowed to dry out once the procedure was started. Our protocol has a much higher sensitivity, using approximately 50times lower concentrations of probe compared to published protocols. In addition to the detection of opsin‐mRNA, It has been successfully applied to the detection of the low abundant Insulin receptor homologue. Furthermore,Aedes aegyptiprobes were visualizing a similar tissue specificity when applied to the malaria mosquitoAnopheles albima

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00051.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe primary and secondary structure of the second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) of two members of theCx. pipienscomplex,Cx. pipiensandCx. 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 ofCx. pipiensandCx. quinquefasciatuswere 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 ofCx. pipiensandCx. quinquefasciafuswere very similar. Furthermore, the ITS2 sequences of specimens belonging to three populations ofCx. pipiensfrom Italy and four populations ofCx. quinquefasciatus(three from Africa and one from North America) were enalysed in order to detect the presence of potential species‐specific diagnostic restrictio

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00052.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractFingerprint profiles were generaed from twenty insect cell lines spanning the Orders, Lepldoptera, Diptera, Coleoptera and Homoptera employing DNA amplification fingerprinting (DAF) with arbitrarily selected prlmers. The fingerprint pattern is a stable characteristlc of the cell line because high and low passages generated the same profile. In addition, insect hosts and homologous cell lines generated similar profiles. All cell lines could be distinguished from each other with the following exceptions:Plutella xylostella(BCIRL‐PX2‐HNU3) andMamestra brassicaee(IZD‐MB‐0503) produced identical patterns toTrichoplusia ni(TN‐CL1). AlsoSpodoptera exigua(UCR‐SE‐1C) produced the same profile asSpodoptera frugiperde(SF9) and the parent cell line IPLB‐SF21. All these cases of identical patterns are believed to be due to cross contamination or mislabelling of cultures. DAF will serve as an additional, valuable and rellable technique for the identification of in

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00053.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe ability of a peach‐potato aphid (Myzus persicae) to resist insecticides can depend on both the presence of amplified esterase genes and on differences in their expression. Here we report a polymerase chain reaction‐restriction enzyme (PCR‐REN) technique which can detect the presence of ampiifled esterase genes and distinguish between the two possible types of amplified gene (E4 and FE4) and a homologous fragment from susceptible aphids. The technique is quick and sensitive enough to be used on a fraction of an aphid or an individual embryo. Furthermore, it can be combined with a pre‐PCR digestion using a methylation‐sensitive enzyme (Hpail) to determine whether or not the esterase genes contain 5–methyicytosine, the presence or absence of which is known to correlate with changes in gene

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00054.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractLarvae of the mosquito vector of human malaria,Anopheles gambiae, were inoculated wlth bacteria and extracts were biochemically fractionated by reverse‐phase HPLC. Multiple induced polypeptides and antibacterial activities were observed following bacterial infection, including a member of the Insect defensin family of antibacterial proteins. A cDNA encodingAn. gambiaepreprodefensin was isolated using PCR primers based on phyiogeneticaiiy conserved sequences. The mature peptide is highly conserved, but the signal and propeptide segments are not, relative to corresponding defensin sequences of other insects. Defensin expression is Induced in response to bacterial infection, in both adult and larval stages. in contrast, pupae express defensin mRNA constitutively. Defensin expression may prove a valuable molecular marker to monitor theAn. gambiaehost response to infection by parasitic protozoa of medical importanc

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00055.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractPCR primers designed from the α‐esterase gene cluster ofDrosophiiamelanogaster have been used to isolate fragments from eight esterase genes In the Australian sheep blowfly,Lucilia cuprina. Phyio‐genetic analysis suggests that three are homologues of the αE7, αE8 and αE9 genes of the α‐esterase cluster ofD. melanogaster. A further three are also probably α‐esterases, whereas the remaining two more closely resemble β‐esterases. Transcripts for five of the α‐esterase genes were detected by PCR in adult midgut, consistent with a role for these enzymes in digestion andlor detoxification. Based on the tissue distribution of these transcripts,LcαE7may possibly encode the esterase, E3, which is involved in organo

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00056.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractWolbachia, 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 ofWolbachiaIn a strain of the spider miteTetranychus urticaebased on the ampllflcatlon and sequencing of part of the 16S rDNA andftsZgenes. In order to establish the phylogenetlc relationships betweenWolbachiafound InT. urticaeand In other arthropods, we aligned the resulting sequences with already published ones. For both 16s andftsZgenes theWolbachiacarried byT. urticaeclustered together withWolbachiafound in other arthropods.

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1996.tb00057.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY