摘要:

AbstractThree methods were used to provide information on the identity and phylogenetic relatedness of 19 aerobic, chemoheterotrophic bacteria isolated from topsoil and deep subsurface sediments at a site in South Carolina. These methods were (i) analysis of selected physiological traits, (ii) restriction endonuclease analysis (REA) of genomic DNA, and (iii) analysis of 16S ribosomal RNA sequences. When the 16S rRNA sequences were compared with those for 12 standard strains, two topsoil isolates and six subsurface strains formed a tight group with the high‐G+C Gram‐positive bacteria and appeared to be most closely related toArthrobacter globiformis— a coryneform‐actinomycete bacterium with unusually effective survival capabilities. The rest of the subsurface isolates were scattered among the standard strains from theProteobacteria— including the pseudomonads andAgrobacterium tumefaciens— or the low‐G+C Gram‐po

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00186.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractCulture conditions, and other variables that modulate a cell's physiology, can bias a polymerase chain reaction (PCR) amplification against generating a representative population profile. TwoPseudomonas putida nahRalleles were constructed in pUC19 that differ solely in a 31‐bp internal segment whose sequence has been inverted. After PCR amplification, the products could be distinguished on the basis of a change in a unique restriction site. When anEscherichia colistrain carrying onenahRallele is submitted to different growth conditions, the consequences of such variations on the relative PCR amplification of whole cells can be ascertained through coamplification with a strain carrying the other allele and subsequent restriction analysis. Cells in stationary phase displayed improved amplifiability while cells grown at 42°C were equally amplifiable as compared to cells grown at 37°C. However, sublethal levels of tetracycline or growth in minimal medium made the PCR target in these cells relatively less amplifiable. When cells are completely lysed and the plasmid DNA is purified beforehand, the coamplification bias is eliminated. These results suggest that mixed populations containing cells in different physiological states may not be representatively amplified by PCR unless a DNA extraction step is inclu

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00187.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe responses of three different soil microbial communities to the experimental application of 2, 4‐dichlorophenoxyacetic acid (2, 4‐D) were evaluated with a variety of molecular genetic techniques. Two of the three soil communities had histories of prior direct exposure to 2, 4‐D, and one had no prior direct application of any herbicide. Dominant 2, 4‐D degrading strains isolated from these soils the previous year were screened for hybridization with three catabolic genes (tfdA,tfdAII, andtfdB) cloned from the well‐studied 2, 4‐D degradative plasmid, pJP4, revealing varying degrees of similarity with the three genes. Hybridization of total community DNA from the three soils with thetfdgene probes also indicated that pJP4‐liketfdgenes were not harboured by a significant percentage of the community. Community level response was evaluated by the comparison of different treatments by Random Amplified Polymorphic DNA (RAPD) fingerprints and by community DNA cross‐hybridization. No differences between treatments within the same soil were detected in any of the RAPD fingerprints generated with 17 primers. Community DNA cross‐hybridization also indicated that the application of 2, 4‐D at the applied rates did not quantitatively affect the structure of the soil microbial communities present in the three soils during the

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00188.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTheHolcuscomplex in France consists of two species,Holcus lanatusL. (Yorkshire fog; 2n= 2x= 14) andHolcus mollisL. (Creeping soft‐grass; 2n= 4x= 28) and an interspecific hybridH.m.×H.l.(2n= 5x= 35), which is morphologically similar toHolcus mollis.A heterologous rDNA probe from wheat was used to detect the corresponding region in Holcus (s. l.) genomic DNA'fragments, for six to eight plants from 13 populations located south‐west of Paris. A restriction enzyme map of the ribosomal RNA genes (rDNA) inHolcus(s. l.) was also constructed. The length polymorphism detected in the IGS region was used as a DNA fingerprint for the identification of different cytotypes and species of theHolcuscomplex and for the typing and delimitation of individuals in populations. In the light of the results we reconsider the assumption that the pentaploid hybridH.m.×H.l.is purely clonal. New hypotheses concerning the origin of the pentaploid hybrid and its reproduction are proposed, and the consequences for genetic diversity in natural populations disc

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00189.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe structure of genetic variation in disjunct Scandinavian populations ofHippocrepis emeruswas studied using allozymes and DNA fingerprinting. Variation in the three native regional populations in Scandinavia was compared with that in a recently introduced population in Sweden. In contrast to the recently introduced population, the native Scandinavian isolates ofH. emerusshowed high levels of allozyme fixation and low levels of DNA diversity. Variation in allozymes and at DNA fingerprint loci showed closely congruent patterns of geographic variation, with pronounced differentiation between the native Norwegian and Swedish isolates of the species. The structure of genetic variation in native ScandinavianH. emerusis interpreted in terms of historical population bottlenecks and founder events during the species' postglacial immigration into Scandinavia.

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00190.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA noncoding nuclear DNA marker sequence (Cpnl‐1) was used to investigate subdivision in the grasshopperChorthippus parallelusand deduce postglacial expansion patterns across its species range in Europe. Investigation of the spatial distribution of 71Cpnl‐1haplotypes and estimation of levels of genetic differentiation (KSTvalues) between populations and geographic regions provided evidence for subdivision ofC. parallelusinto at least five major geographic regions and indicated that the French form ofC. parallelusoriginated after range expansion from a Balkan refugium, Further evidence for subdivision ofC. parallelusbetween Italy and northern Europe suggests that the Alps may have formed a significant barrier to gene flow in this grasshop

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00191.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractMycorrhizal fungi are usually identified on the basis of the morphological characters shown by fruit bodies, spores, vegetative mycelia or symbiotic structures. The development of molecular techniques provides a valuable and alternative approach to identify mycorrhizal fungi, especially when it is difficult to gather a sufficient number of data on morphological features. Short arbitrary oligonucleotides were used as primers for the amplification of genomic DNA extracted from spores of arbuscular fungi. The RAPD fingerprints showed banding patterns which allowed us to distinguish between species and even isolates within Glomales. In order to identify mycorrhizal fungi during their symbiotic phase, a nonpolymorphic RAPD band identified as marker for some isolates ofGlomus mosseaewas purified from agarose gels and cloned in a bluescript vector. The fragment was sequenced and specific primers (PO‐M3) were designed for the mycorrhizal fungus. They specifically and successfully amplified the DNA not only fromG. mosseaespores, but also from roots of pea, clover, leek and onion plants when they were colonized byG. mosseaeisolate

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00192.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo thousand seven hundred and forty‐seven isolates ofSclerotinia sclerotiorumwere sampled from four field populations of canola in western Canada. Each field was sampled in a grid of 128 50‐m 50‐m quadrats plus four intensive quadrats each sampled in a diagonal transect. Sampling was done at two phases of the disease cycle: (1) from ascospore inoculum on petals and (2) from disease lesions in stems. A total of 594 unique genotypes was identified by DNA fingerprinting. In each field, a small group of clones represented the majority of the sample, with a large group of clones or genotypes sampled once or twice. Clone frequencies were compared by χ2tests. The difference in profiles of clone frequencies for the two fields sampled in 1991 was not significant, but in 1992 the difference in profiles was marginally significant, indicating some local population substructure. The difference in profiles of clone frequencies for petals and lesions was not significant in each of the two fields sampled in 1991. In each of the two fields sampled in 1992, however, the difference was highly significant, consistent either with selection for some clones or with waves of immigration during the disease cycle. Nine of the 30 most frequently sampled clones from this study were previously recovered in a macrogeographical sample from western Canada in 1990. For spatial analyses, randomization tests indicated no significant spatial aggregation of either clones on petals or clones from lesions. Also, isolates of a clone on petals were not closer to isolates of the same clone from lesions than could be predicted by chance. Both observations suggest spatial mixing of ascospore inoculum from resident or immigrant s

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00193.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractBay cod, Atlantic cod (Gadus morhua) that over‐winter in the deep‐water bays of northeastern Newfoundland, have historically been regarded as distinct in migration and spawning behaviour from offshore (Grand Bank) cod stocks. To investigate their genetic relationships, we determined the DNA sequence of a 307‐base‐pair portion of the mitochondrial cytochromebgene for 236 adult cod taken from the waters off northeastern Newfoundland, including fish found over‐wintering and spawning in Trinity Bay. Although 17 genotypes were found, a single common genotype occurs at a frequency of greater than 80% in all samples, and no alternative genotype occurs at a frequency of greater than 3%. Genotype proportions did not differ significantly among samples. Measures of genetic subdivision among sampling locations are nil. Cod over‐wintering in Trinity Bay are not genetically distinct from offshore cod. In combination with tagging and physiological studies, these data suggest that there is sufficient movement of cod between bay and offshore locations to prevent the development or maintenance of independent inshore stocks. Adult cod that over‐winter in Trinity Bay appear to represent an assemblage of temporarily nonmigratory fish that have become physiologically acclimated to cold‐water inshore environments. The pattern of genetic variation in northern cod suggests a recent population structure characterized by extensive movement of contemporary individuals superimposed on an older structure characterized by a bottleneck in the population size of cod in the north

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00194.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractHighly variable microsatellites enabled a precise assessment of the number of queen matings in the colonies of five bumble bee species. Fifteen of the sixteen microsatellites initially cloned fromB. terrestrishad flanking regions similar enough to allow PCR amplification on the otherBombusspecies analysed. The microsatellites selected for intracolony study (four per species) were characterized by a high heterozygosity (0.58–0.93) and a large number of alleles (3–18) in the local populations from which the colonies originated. A single male appeared to have inseminated the queens in the colonies of four species,B. terrestris, B. lucorum, B. lapidariusandB. pratorum, which belong to three subgenera, whereas two of the three analysed colonies ofB. hypnorumwere polyandrous (minimum number of two and four patrilines, respective

ISSN:0962-1083    

DOI:10.1111/j.1365-294X.1995.tb00195.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY