ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00148.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractApplications to release genetically modified organisms (GMOs) into the environment, usually the agricultural environment, are increasing exponentially. Many involve crop plants that are also weeds. Studies of biological invasions and of biological control show that the probability that a genetically new organism establishing itself is small; it is also unpredictable and in some cases could have severe ecological effects. GMOs pose risks both because they will be released in large numbers and because the greater the genetic novelty the greater the possibility of ecological novelty. Molecular ecology is an essential ingredient in ensuring that risks are assessed efficiently.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00149.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA vector system was developed employing the recA genes of Rhizobium meliloti and Rhizobium leguminosarum biovar. viciae as target sequences for the stable genomic integration of foreign DNA. The plasmid vectors can be used either as integration vectors (single cross–over), or as gene replacement vectors (double cross–over). Gene replacement results in the antibiotic–marker–free integration of cloned DNA into the recA genes of R. meliloti and R. leguminosarum bv. viciae. Consequently, the recombinant strains become recombination deficient (RecA‐). The expression of integrated genes is under the control of the neomycin phosphotransferase II (nptll) promoter of transposon Tn5. The system was used to construct recA mutant strains of R. meliloti and R. leguminosarum by. viciae, carrying the Escherichia coli gusA gene encoding β–glucuronidase as well as the firefly (Photinus pyralis) luc gene encoding luciferase as marker genes. The GUS activity in the constructed strains was found to be absolutely stable over more than 100 generations of non–selective growth in liquid culture. The stability was also confirmed in root–nodule passages. In addition, the potential use of the luc gene as a stable genetic marker in the unequivocal identification of tagged strains among indigenous microbes in non–sterile soil was demonstrated. It is proposed to use bioluminescent recA mutants as model organisms in risk assessment studies with genetically engineered

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00150.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe use of DNA fingerprinting to identify members of the same clone in completely or partially asexual organisms requires that the individuals within a clone share a recent common ancestor. By considering the expected distributions of band–sharing values in asexual and sexual organisms, it is shown that DNA fingerprinting may be effective in distinguishing members of the same clone, provided that the frequency of sexual reproduction is considerably greater than the minisatellite mutation rat

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00151.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMitochondrial DNA (mtDNA) from 25 blue titsParus caeruleussampled from two populations of the Grenoble region (France) was assayed for polymorphism with 17 restriction endonucleases. Nine genotypes were found. Several mtDNA genotypes were also analysed by amplificationviathe polymerase chain reaction (PCR) and direct sequencing of 903 bp of the cytochromebgene. The mtDNA polymorphism is greater in P.caeruleusthan in other comparable bird species and results from the presence of two clearly differentiated mitochondrial lineages. Using the data of restriction polymorphism, the mean sequence divergence between individuals of the two lineages is 1.23%. Therefore,P. caeruleusshould fall into the category II of phylogeographic patternsensuAviseet al.(1987): discontinuous mtDNA genotypes which co–occur in the same region. P.caeruleus, like humans and other mobile species with high gene flow, seems to have lost its geographic structure in terms of mtDNA phylogeny. This unusual mitochondrial polymorphism can be explained by the recent admixture of two long–term isolated populations. This could be accounted for by two different scenarios. One assumes a simultaneous post–glacial colonization of the Grenoble region by two isolated European populations of P.caeruleus.Alternatively, hybridization between P.caeruleusand P.cyanuscould have caused the observed pattern of mtDNA vari

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00152.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractNatural transformation is the mechanism of procaryotic gene transfer that involves the uptake and expression of genetic information encoded in extracellular DNA. This process has been regarded as a mechanism to transfer genes (primarily chromosomal markers) between closely related strains or species. Here we demonstrate the cell–contact–dependent transfer of a non–conjugative plasmid from a laboratoryE. colistrain to a marineVibriospecies, the first report of intergeneric natural plasmid transformation involving a marine bacterium. The nucleic acid synthesis inhibitors nalidixic acid and rifampicin inhibited the ability of theE. colito function as a donor. However, dead cells also served as efficient donors. There was an obligate requirement for cell contact. No transfer occurred in the presence of DNase I, when donors and recipients were separated by a 0.2–μm filter, or when spent medium alone was used as a source of transforming DNA. These results indicate that contact–mediated intergeneric plasmid exchange can occur in the absence of detectable viable donor cells and that small non–conjugative plasmids can be spread through heterogeneous microbial communities by a process previously not recognized, natural plasmid transformation. These findings are important in the assessment of genetic risk to the environment, particularly from wastewater treatment systems and the use of genetically engineered organisms in the

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00153.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMales of the bushcricketPoecilimon veluchianuspass a large spermatophore to the female during mating. The spermatophore is eaten by the female after copulation. Because females mate with several males during their reproductive life, the competition between spermatozoa of different males affects a male's reproductive success. In order to determine the outcome of sperm competition, the paternity of the progeny of double–mated females was established by DNA fingerprinting with the oligonucleotide (GATA)4. TypicalP. veluchianusDNA fingerprints consisted of 15 scoreable fragments per individual. The proportion of bands shared between presumably unrelated bushcrickets was 17%. After the second copulation the second mating male clearly predominated at fertilization. The mean proportion of eggs fertilized by the second male was 90.1%. There was no significant relationship between the level of sperm precedence and the time of ovipositions after the second mating. If femaleP. veluchianusincrease the fitness of their offspring by the incorporation of spermatophore–derived substances in developing eggs, there is little chance for the feeding male to fertilize eggs containing his nutrients, because of the very short mating intervals of females and the observed high level of last–male sperm precedence in this species. Under such conditions the last mating male would fertilize many eggs containing nutrients from a prior male. Because nuptial gifts, like the tettigoniid spermatophore, function only as paternal investment if the donating male's progeny benefit from the gift, a paternal investment function of theP. veluchianusspermatophore seems to be unl

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00154.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMolecular genetic markers have been developed into powerful tools to analyse genetic relationships and genetic diversity. As an extension to the variety of existing techniques using polymorphic DNA markers, the Random Amplified Polymorphic DNA (RAPD) technique may be used in molecular ecology to determine taxonomic identity, assess kinship relationships, analyse mixed genome samples, and create specific probes. Main advantages of the RAPD technology include (i) suitability for work on anonymous genomes, (ii) applicability to problems where only limited quantities of DNA are available, (iii) efficiency and low expense.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00155.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00156.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1992.tb00157.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY