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Denis Saulnier Sophie De Decker Philippe Haffner Laetitia Cobret Maeva Robert Céline Garcia 《Microbial ecology》2010,59(4):787-798
A 4-year bacteriological survey (2003-2007) of four molluscs cultivated in France and faced with mortality episodes was performed by the French shellfish pathology network. The more abundant bacteria isolated during 92 mortality episodes, occurring mainly in Pacific oyster Crassostrea gigas, were identified by genotyping methods. It allowed us both to confirm the representativeness of Vibrio splendidus and Vibrio aestuarianus bacterial strains and to identify both a large number of Vibrio harveyi-related strains mainly detected during 2007 oyster mortality outbreaks and to a lesser extent bacterial strains identified as Shewanella colwelliana. Because metalloprotease has been reported to constitute a virulence factor in a few Vibrio strains pathogenic for C. gigas, several bacterial strains isolated in this study were screened to evaluate their pathogenicity in C. gigas spat by experimental infection and their ability to produce metalloprotease-like activity in the culture supernatant fluids. A high level (84%) of concordant results between azocaseinase activities and virulence of strains was obtained in this study. Because bacterial metalloprotease activities appeared as a common feature of pathogenic bacteria strains associated with mortality events of C. gigas reared in France, this phenotypic test could be useful for the evaluation of virulence in bacterial strains associated with such mortality episodes. 相似文献
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Laetitia Malphettes Yevgeniy Freyvert Jennifer Chang Pei‐Qi Liu Edmond Chan Jeffrey C. Miller Zhe Zhou Thu Nguyen Christina Tsai Andrew W. Snowden Trevor N. Collingwood Philip D. Gregory Gregory J. Cost 《Biotechnology and bioengineering》2010,106(5):774-783
IgG1 antibodies produced in Chinese hamster ovary (CHO) cells are heavily α1,6‐fucosylated, a modification that reduces antibody‐dependent cellular cytotoxicity (ADCC) and can inhibit therapeutic antibody function in vivo. Addition of fucose is catalyzed by Fut8, a α1,6‐fucosyltransferase. FUT8?/? CHO cell lines produce completely nonfucosylated antibodies, but the difficulty of recapitulating the knockout in protein‐production cell lines has prevented the widespread adoption of FUT8?/? cells as hosts for antibody production. We have created zinc‐finger nucleases (ZFNs) that cleave the FUT8 gene in a region encoding the catalytic core of the enzyme, allowing the functional disruption of FUT8 in any CHO cell line. These reagents produce FUT8?/? CHO cells in 3 weeks at a frequency of 5% in the absence of any selection. Alternately, populations of ZFN‐treated cells can be directly selected to give FUT8?/? cell pools in as few as 3 days. To demonstrate the utility of this method in bioprocess, FUT8 was disrupted in a CHO cell line used for stable protein production. ZFN‐derived FUT8?/? cell lines were as transfectable as wild‐type, had similar or better growth profiles, and produced equivalent amounts of antibody during transient transfection. Antibodies made in these lines completely lacked core fucosylation but had an otherwise normal glycosylation pattern. Cell lines stably expressing a model antibody were made from wild‐type and ZFN‐generated FUT8?/? cells. Clones from both lines had equivalent titer, specific productivity distributions, and integrated viable cell counts. Antibody titer in the best ZFN‐generated FUT8?/? cell lines was fourfold higher than in the best‐producing clones of FUT8?/? cells made by standard homologous recombination in a different CHO subtype. These data demonstrate the straightforward, ZFN‐mediated transfer of the Fut8? phenotype to a production CHO cell line without adverse phenotypic effects. This process will speed the production of highly active, completely nonfucosylated therapeutic antibodies. Biotechnol. Bioeng. 2010;106: 774–783. © 2010 Wiley Periodicals, Inc. 相似文献
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Caroline Michot Asmaa Mamoune Joseph Vamecq Mai Thao Viou Lu-Sheng Hsieh Eric Testet Jeanne Lainé Laurence Hubert Anne-Frédérique Dessein Monique Fontaine Chris Ottolenghi Laetitia Fouillen Karim Nadra Etienne Blanc Jean Bastin Sophie Candon Mario Pende Arnold Munnich Pascale de Lonlay 《生物化学与生物物理学报:疾病的分子基础》2013,1832(12):2103-2114
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Dussart P Petit L Labeau B Bremand L Leduc A Moua D Matheus S Baril L 《PLoS neglected tropical diseases》2008,2(8):e280
Background
We compared the performance of two new commercial tests for the detection of dengue NS1 protein during the clinical phase of dengue virus (DENV) infection—an immunochromatographic test allowing rapid detection of the NS1 antigen, Dengue NS1 Ag STRIP (Bio-Rad Laboratories - Marnes La Coquette, France), and a two-step sandwich-format microplate enzyme-linked immunosorbent assay (ELISA), pan-E Dengue Early ELISA (Panbio - Brisbane, Australia)—with a one-step sandwich-format microplate ELISA, the Platelia Dengue NS1 Ag test (Bio-Rad).Methods
We tested 272 serum samples from patients with dengue disease. Of these, 222 were from patients with acute infection of one of the four dengue serotypes, detected by RT-PCR and/or virus isolation. Forty-eight acute-phase serum samples from patients not infected with dengue virus were also included.Results
The sensitivity of the Platelia Dengue NS1 Ag test on acute serum samples (n = 222) was 87.4% (95% confidence interval: 82.3% to 91.5%); that of Dengue NS1 Ag STRIP was 81.5% (95% CI: 75.8% to 86.4%) after 15 minutes and 82.4% (95% CI: 76.8% to 87.2%) after 30 minutes. Both tests had a specificity of 100% (97.5% CI, one-sided test: 92.6% to 100.0%). The pan-E Dengue Early ELISA had a sensitivity of 60.4% (95% CI: 53.4% to 66.8%) and a specificity of 97.9% (95% CI: 88.9% to 99.9%).Conclusion
Our findings support the use of diagnostic tools based on the NS1 antigen detection for the diagnosis of acute DENV infection. The immunochromatographic test, Dengue NS1 Ag STRIP—the first rapid diagnostic test for DENV infection—was highly sensitive and specific, and would therefore be a suitable first-line test in the field. The pan-E Dengue Early ELISA was less sensitive than the Platelia test; this two-step ELISA should be combined with DENV IgM antibody detection for the diagnosis of DENV infection. 相似文献46.
Selfish male‐determining element favors the transition from hermaphroditism to androdioecy 下载免费PDF全文
Sylvain Billiard Laetitia Husse Pierre Lepercq Cécile Godé Angélique Bourceaux Jacques Lepart Philippe Vernet Pierre Saumitou‐Laprade 《Evolution; international journal of organic evolution》2015,69(3):683-693
According to the current, widely accepted paradigm, the evolutionary transition from hermaphroditism toward separate sexes occurs in two successive steps: an initial, intermediate step in which unisexual individuals, male or female, sterility mutants coexist with hermaphrodites and a final step that definitively establishes dioecy. Two nonexclusive processes can drive this transition: inbreeding avoidance and reallocation of resources from one sexual function to the other. Here, we report results of controlled crosses between males and hermaphrodites in Phillyrea angustifolia, an androdioecious species with two mutually intercompatible, but intraincompatible groups of hermaphrodites. We observed different segregation patterns that can be explained by: (1) epistatic interactions between two unlinked diallelic loci, determining sex and mating compatibility, and (2) a mutation with pleiotropic effects: female sterility, full compatibility of males with both hermaphrodite incompatibility groups, and complete male‐biased sex‐ratio distortion in one of the two groups. Modeling shows that these mechanisms can explain the high frequency of males in populations of P. angustifolia and can promote the maintenance of androdioecy without requiring inbreeding depression or resource reallocation. We thus argue that segregation distortion establishes the right conditions for the evolution of cryptic dioecy and potentially initiates the evolution toward separate sexes. 相似文献
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Segregation of replicated chromosomes is an essential process in all organisms. How bacteria, such as the oval-shaped human pathogen Streptococcus pneumoniae, efficiently segregate their chromosomes is poorly understood. Here we show that the pneumococcal homologue of the DNA-binding protein ParB recruits S. pneumoniae condensin (SMC) to centromere-like DNA sequences (parS) that are located near the origin of replication, in a similar fashion as was shown for the rod-shaped model bacterium Bacillus subtilis. In contrast to B. subtilis, smc is not essential in S. pneumoniae, and Δsmc cells do not show an increased sensitivity to gyrase inhibitors or high temperatures. However, deletion of smc and/or parB results in a mild chromosome segregation defect. Our results show that S. pneumoniae contains a functional chromosome segregation machine that promotes efficient chromosome segregation by recruitment of SMC via ParB. Intriguingly, the data indicate that other, as of yet unknown mechanisms, are at play to ensure proper chromosome segregation in this organism. 相似文献
50.
Ensemble modelling of species distribution: the effects of geographical and environmental ranges 总被引:1,自引:0,他引:1
The aim of this study was to analyse the effects of species geographical and environmental ranges on the predictive performances of species distribution models (SDMs). We explored the usefulness of ensemble modelling approaches and tested whether species attributes influenced the outcomes of such approaches. Eight SDMs were used to model the current distribution of 35 fish species at 1110 stream sections in France. We first quantified the consensus among the resulting set of predictions for each fish species. Next, we created an average model by taking the average of the individual model predictions and tested whether the average model improved the predictive performances of single SDMs. Lastly, we described the ranges of fish species along four gradients: latitudinal, thermal, stream gradient (i.e. upstream‐downstream) and elevation. After accounting for the effects of phylogenetic relatedness and species prevalence, these four species attributes were related to the observed variations in both consensus among SDMs and predictive performances by using generalized estimation equations. Our results highlight the usefulness of ensemble approaches for identifying geographical areas of agreement among predictions. Although the geographical extent of species had no effect on the performances of SDMs, we demonstrated that more consensual and accurate predictions were obtained for species with low thermal and elevation ranges, validating the hypothesis that specialist species yield models with higher accuracy than generalist ones. We emphasized that significant improvements in the accuracy of SDMs can be achieved by using an average model. Furthermore, these improvements were higher for species with smaller ranges along the four gradients studied. The geographical extent and ranges of species along environmental gradients provide promising insights into our understanding of uncertainties in species distribution modelling. 相似文献