摘要:

AbstractAlthough uracil‐DNA glycosylases were at one time considered to be ubiquitous in nature, this DNA repair activity is notably absent inDrosophila melanogasterand other pupating insects. On the other hand, a nuclease has been identified inDrosophilathat is specific for uracil‐containing DNA, but curiously the expression of this activity is restricted to late larval stages of development. Since the nuclease activity is only detected near the time of histolysation, we began questioning the possible role uracil might play in the events associated with the eventual DNA degradation that is involved in the metamorphotic process. The results of these studies have provided us with a molecular model for pupating insects that contains all the necessary elements to program cells for their ultimate death, and in so doing, shows why uracil‐DNA glycosylases would be incompatible with our proposed pathway for apop

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA low‐abundance haemolymph protein from adult maleManduca sextawas purified to homogeneity. The 29,000 Da glycoprotein is synthesized in the fat body, is present in both male and female, and is present during all stages of development. Antiserum against the 29 kDa protein was raised in a rabbit and used to screen anM. sextalarval fat body cDNA library. An 880 base pair clone was isolated and found to contain the full‐length transcript. Sequencing of the cDNA revealed an open reading frame of 699 bases beginning from the possible translation initiation site. The deduced 233‐amino acid polypeptide contains an apparent 17‐amino acid signal peptide and three potential N‐glycosylation sites. The function of the 29 kDa protein i

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTsetse flies (Diptera: Glossinidae) harbour two morphologically different endosymbionts intracellularly associated with gut tissue: a primary (P) and a secondary (S) organism. The P‐endosymbiont is a gram‐negative rod, 8–10 μm in size, and resides intracellularly within specialized cells, mycetocytes which are organized into an organelle (mycetome), in the anterior portion of the gut. The S‐endosymbiont is a smaller (1–2 μm) gram‐negative rod and is harboured in the epithelial sheath cells in midgut. Phylogenetic characterization of S‐endosymbionts from taxonomically distant insects including tsetse flies has shown that they are related to the free‐living bacterium,Escherichia coli, and are members of the family Enterobacteriaceae within the γ‐3 subdivision of Proteobacteria. In this study, a polymerase chain reaction (PCR) based assay was designed utilizing the conserved sequences of 16S rDNA in order to phylogenetically characterize the mycetome‐associated P‐endosymbionts directly from tsetse mycetome tissue. Analysis from five species of flies representing the three major subgenera of genusGlossinaindicates that P‐endosymbionts constitute a distinct lineage within the γ‐3 subdivision of Proteobacteria. Mycetome endosymbiont phylogeny appears to parallel the classic taxonomic assignments independently developed for their insect host species. This suggests an ancient association for this symbiosis, which may have subsequently radiated with time, giving rise to the current species of tsetse flies and their modern‐day endosymbionts. Based on endosymbiont phylogeny, thefuscaflies constitute the most ancient subgenus, followed b

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on 16S rDNA sequence comparison, intracellular mycetome‐associated endosymbionts (P‐endosymbionts) of tsetse flies (Diptera: Glossinidae) form a distinct lineage within the γ‐3 subdivision of proteobacteria, related to the free‐living bacteriumEscherichia coli, midgut S‐endosymbionts of various insects including tsetse flies, and to the P‐endosymbiont lineage of aphids,Buchnera aphidicola.Gene organization and expression of several loci in intracellular microorganisms have revealed differences from free‐living bacteria. This study analyses two of these characteristics in tsetse endosymbionts; the copy number and gene organization of rDNA operons and the nature of the abundant protein(s) synthesized by these microorganisms. Results indicate thatGlossina morsitans morsitansS‐endosymbionts have multiple (seven) rDNA operons coding for 16S (rrs) followed by 23S (rrl) gene sequences, whereas tsetse P‐endosymbionts have a single, similarly organized rDNA operon. In tsetse mycetocytesin vitro, P‐endosymbionts synthesize a predominant protein of 60 kDa in size (p60) which by Western blot analysis shows immunological cross‐reactivity with the abundant 63 kDa (p63) protein ofB. aphidicola.p63 (also referred to as symbionin) has been characterized as a molecular chaperone, structurally and functionally similar to the groEL protein ofE. coli.Underin vitroconditions, tsetse S‐endosymbionts synthesize high levels of a similarly‐sized protein that cross‐reacts with p63 chaperonin. Antisera against the tsetse p60 protein also recognizes p63 protein ofB. aphidicola, suggesting that the abundant tsetse endosymb

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractDegenerate primers designed and synthesized based on two conserved regions of themarinertransposase open reading frame were used to amplify a 454 bp DNA fragment fromM. occidentalis.Two inverse primers were then synthesized and used to amplify flanking genomic DNA fragments fromM. occidentalisby a ligation‐mediated inverse PCR. The completemarinerelement(Moc 1)was 1284 bp long, including the imperfect 28 bp inverted terminal repeat sequences, and shared 59% similarity to an active 1286 bp longD. mauritiana marinerelement(Mos 1).Insertions, deletions and substitutions were observed in theMoc 1sequence at several positions. No intact open reading frame was detected and theMoc 1element is considered inactive. Stringent Southern blot hybridizations revealed at least twelve copies ofmarinersequences similar toMoc 1in the colonies teste

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAedes albopictusandAedes aegyptiare 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 forAe. aegypti, the extent of synteny and linkage order conservation between the two species was unknown. A comparative linkage map forAe. albopictuswas constructed based mainly on cDNA clones fromAe. aegypti.Nearly allAe. aegyptiprobes hybridized toAe. albopictusDNA 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 F2progeny 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.

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo DNA fragments (3941 and 7152 base pairs) from the procaryotic endosymbiont(Buchnera)of the aphidSchlechtendalia chinensiswere cloned and sequenced. The smaller fragment containedtrpEGand the larger fragment containedtrpDC(F)BA, genes coding for enzymes of the tryptophan biosynthetic pathway which convert chorismate to tryptophan. Both of these gene clusters were present as one copy on the endosymbiont chromosome and probably constitute two transcription units. The deduced amino acid sequences of the proteins was 51–61% identical to the corresponding proteins were previously studied inBuchneraof the aphidSchizaphis graminum.In this endosymbiont,trpEGis amplified and located on a plasmid, whereas, in the endosymbiont ofS. chinensis, as in other eubacteria,trpEGoccurs as a single copy on the bacterial chromosome. Implications of these findings for the evolution of this mutualistic association are discusse

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA 2.99 kb mtDNA fragment containing two variable restriction endonuclease sites (EcoRVandXbal) was subcloned and sequenced from the Mediterranean fruit fly(Ceratitis capitata).This fragment represents approximately one‐fifth of the entire mitochondrial sequence. The sequence was aligned with the comparable region fromDrosophila yakubaandAnopheles gambiae, resulting in 81.8% and 76.7% identity at the nucleotide level, and 77% and 67.7% identity, respectively, at the amino acid level. The sequenced region includes the complete genes for NADH dehydrogenase 4, NADH dehydrogenase 4L, NADH dehydrogenase 6, and transfer RNAs for proline, threonine and histidine, and part of the genes for NADH dehydrogenase 5 and cytochromeb.Oligonucleotide primers were designed to asymmetrically bracket each of two variable restriction endonuclease sites to allow PCR amplification and subsequent restriction endonuclease analysis of individual fly sample

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1995.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY