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Large Diversity (large + diversity)
Selected AbstractsDevelopment and experimental validation of a nifH oligonucleotide microarray to study diazotrophic communities in a glacier forefieldENVIRONMENTAL MICROBIOLOGY, Issue 8 2009Laurence Duc Summary Functional microarrays are powerful tools that allow the parallel detection of multiple strains at the species level and therefore to rapidly obtain information on microbial communities in the environment. However, the design of suitable probes is prone to uncertainties, as it is based so far on in silico predictions including weighted mismatch number and Gibbs free-energy values. This study describes the experimental selection of probes targeting subsequences of the nifH gene to study the community structure of diazotrophic populations present in Damma glacier (Swiss Central Alps) forefield soils. Using the Geniom® One in situ synthesis technology (Febit, Germany), 2727 in silico designed candidate probes were tested. A total of 946 specific probes were selected and validated. This probe set covered a large diversity of the NifH phylotypes (35 out of the 45) found in the forefield. Hybridization predictors were tested statistically. Gibbs free-energy value for probe-target binding gave the best prediction for hybridization efficiency, while the weighted mismatch number was not significantly associated to probe specificity. In this study, we demonstrate that extensive experimental tests of probe-hybridization behaviour against sequences present in the studied environment remain a prerequisite for meaningful probe selection. [source] Dispersal pattern of domestic cats (Felis catus) in a promiscuous urban population: do females disperse or die?JOURNAL OF ANIMAL ECOLOGY, Issue 2 2003Sébastien Devillard Summary 1The domestic feral cat (Felis catus L.) is a good model for studying intraspecific variability of dispersal patterns in mammals because cats live under a large diversity of socio-ecological conditions. We analysed both the natal and breeding dispersal patterns of domestic cats in a promiscuous urban population and tested whether or not it differed from the male-biased natal dispersal pattern observed for polygynous rural populations. 2During an 8-year study we recorded the exact date of in situ death for 148 marked cats and the exact date of disappearance from the population for 99 other cats. Because undiscovered deaths might over-estimate dispersal probabilities when considering only disappearance probabilities, we made an novel application of multistrata capture,recapture methods in order to disentangle dispersal from true mortality. 3We showed that mature females dispersed, both before and after their first reproduction, at 1 and 2 years old. Contrary to females, no dispersal seemed to occur in males. Before sexual maturity, females that disappeared at 1 and 2 years old were in worse body condition than females that stayed in the population area after 2 years old. However, they did not reproduce less successfully before their disappearance than females that died later in the population area. 4The female-biased and low natal dispersal pattern in this population was atypical compared to other promiscuous/polygynous mammals and differed from that observed in rural polygynous populations of domestic cat. Neither local mate competition nor inbreeding avoidance appeared to be sufficient pressures to counterbalance ecological constraints on dispersal in an urban environment. However, local resource competition for den sites between potential matriarchies could lead to the breeding dispersal of less competitive females. [source] Assessment of the rind microbial diversity in a farmhouse-produced vs a pasteurized industrially produced soft red-smear cheese using both cultivation and rDNA-based methodsJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004C. Feurer Abstract Aims:, The diversity of the surface flora of two French red-smear soft cheeses was examined by cultivation-dependent and cultivation-independent methods to assess their composition and to evaluate the accuracy of both approaches. Methods and Results:, Culture-independent methods used involved 16S ribosomal DNA gene cloning and sequencing and single-strand conformation polymorphism analysis (SSCP). The culture-dependent method used involved direct culture and macroscopic observation, polymerase chain reaction of the 16S rRNA gene from DNA extracted from single colonies followed by complete sequencing of the gene. Only few species were recovered by both approaches either in the pasteurized and the farmer cheese. A large diversity of isolates or 16S rDNA sequences related to marine bacteria was identified at the surface of both cheeses. Conclusions:, The results indicated that all three techniques were informative and complementary to allow a more accurate representativeness of the cheese surface biodiversity. Significance and Impact of the Study:, Cultivation and molecular methods have to be combined in order to obtain an extended view of the bacterial populations of complex ecosystems. [source] Flexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosaeMOLECULAR ECOLOGY, Issue 8 2009YUKO ULRICH Abstract The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae, a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects. [source] Software utilities for the interpretation of mass spectrometric data of glycoconjugates: application to glycosphingolipids of human serumRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2010Jamal Souady Glycosphingolipids (GSLs) are major components of the outer leaflet of the cell membrane. These lipids are involved in many cell surface events and show disease-related expression changes. GSLs could thus serve as useful targets for biomarker discovery. The GSL structure is characterized by two entities: a hydrophilic glycan and a hydrophobic ceramide moiety. Both components exhibit numerous structural variations, the combination of which results in a large diversity of GSL structures that can potentially exist. Mass spectrometry (MS) is a powerful tool for high-throughput analysis of GSL expression analysis and structural elucidation. Yet, the assignment of GSL structures using MS data is tedious and demands highly specialized expertise. SysBioWare, a software platform developed for MS data evaluation in glycomics, was here applied for the MS analysis of human serum GSLs. The program was tuned to provide automated compositional assignment, supporting a variety of glycan and ceramide structures. Upon in silico fragmentation, the masses of predicted ions arising from cleavages in the glycan as well as the ceramide moiety were calculated, thus enabling structural characterization of both entities. Validation of proposed structures was achieved by matching in silico calculated fragment ions with those of experimental MS/MS data. These results indicate that SysBioWare can facilitate data interpretation and, furthermore, help the user to deal with large sets of data by supporting management of MS and non-MS data. SysBioWare has the potential to be a powerful tool for high-throughput glycosphingolipidomics in clinical applications. Copyright © 2010 John Wiley & Sons, Ltd. [source] Radio bimodality: Spin, accretion mode, or both?ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009M. Sikora Abstract A new scenario is suggested to explain a large diversity of the AGN radio properties and their dependence on the galaxy morphology. The scenario is based on the assumption that the growth of supermassive BHs is dominated by the accretion only during the quasar (high accretion rate) phase, otherwise , by mergers with less massive black holes. Following that, BHs are expected to spin much faster in giant ellipticals than in disk galaxies. Within the frame of the spin paradigm this explains the observed relation of the radio-dichotomy with the galaxy morphology. Various theoretical and observational aspects of such a dichotomy are discussed. In particular, the issue of the intermittency and suppression of a jet production at high accretion rates is addressed and a scenario for production of powerful, extended radio sources is drafted (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Molecular epidemiology of the nasal colonization by methicillin-susceptible Staphylococcus aureus in Swiss childrenCLINICAL MICROBIOLOGY AND INFECTION, Issue 9 2010C. Mégevand Clin Microbiol Infect 2010; 16: 1414,1420 Abstract Nasal carriage of Staphylococcus aureus contributes to an increased risk of developing an infection with the same bacterial strain. Genetic regulatory elements and toxin-expressing genes are virulence factors associated with the pathogenic potential of S. aureus. We undertook an extensive molecular characterization of methicillin-susceptible S. aureus (MSSA) carried by children. MSSA were recovered from the nostrils of children. The presence of Panton-Valentine leukocidin (PVL), exfoliatins A and B (exfoA and exfoB), and the toxic-shock staphylococcal toxin (TSST-1) and agr group typing were determined by quantitative PCR. A multiple-locus variable-number of tandem repeat analysis (MLVA) assay was also performed for genotyping. Five hundred and seventy-two strains of MSSA were analysed. Overall, 30% were positive for toxin-expressing genes: 29% contained one toxin and 1.6% two toxins. The most commonly detected toxin gene was tst, which was present in 145 (25%) strains. The TSST-1 gene was significantly associated with the agr group 3 (OR 56.8, 95% CI 32.0,100.8). MLVA analysis revealed a large diversity of genetic content and no clonal relationship was demonstrated among the analysed MSSA strains. Multilocus sequence typing confirmed this observation of diversity and identified ST45 as a frequent colonizer. This broad diversity in MSSA carriage strains suggests a limited selection pressure in our geographical area. [source] | ||||||||||