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991.
Aurélie Gardarin Stéphane Chédin Gilles Lagniel Jean‐Christophe Aude Emmanuel Godat Patrice Catty Jean Labarre 《Molecular microbiology》2010,76(4):1034-1048
Cadmium (Cd2+) is a very toxic metal that causes DNA damage, oxidative stress and apoptosis. Despite many studies, the cellular and molecular mechanisms underlying its high toxicity are not clearly understood. We show here that very low doses of Cd2+ cause ER stress in Saccharomyces cerevisiae as evidenced by the induction of the unfolded protein response (UPR) and the splicing of HAC1 mRNA. Furthermore, mutant strains (Δire1 and Δhac1) unable to induce the UPR are hypersensitive to Cd2+, but not to arsenite and mercury. The full functionality of the pathways involved in ER stress response is required for Cd2+ tolerance. The data also suggest that Cd2+‐induced ER stress and Cd2+ toxicity are a direct consequence of Cd2+ accumulation in the ER. Cd2+ does not inhibit disulfide bond formation but perturbs calcium metabolism. In particular, Cd2+ activates the calcium channel Cch1/Mid1, which also contributes to Cd2+ entry into the cell. The results reinforce the interest of using yeast as a cellular model to study toxicity mechanisms in eukaryotic cells. 相似文献
992.
993.
994.
Lakshmiprasad Potluri Aneta Karczmarek Jolanda Verheul Andre Piette Jean‐Marc Wilkin Nadine Werth Manuel Banzhaf Waldemar Vollmer Kevin D. Young Martine Nguyen‐Distèche Tanneke Den Blaauwen 《Molecular microbiology》2010,77(2):300-323
The distribution of PBP5, the major D,D‐carboxypeptidase in Escherichia coli, was mapped by immunolabelling and by visualization of GFP fusion proteins in wild‐type cells and in mutants lacking one or more D,D‐carboxypeptidases. In addition to being scattered around the lateral envelope, PBP5 was also concentrated at nascent division sites prior to visible constriction. Inhibiting PBP2 activity (which eliminates wall elongation) shifted PBP5 to midcell, whereas inhibiting PBP3 (which aborts divisome invagination) led to the creation of PBP5 rings at positions of preseptal wall formation, implying that PBP5 localizes to areas of ongoing peptidoglycan synthesis. A PBP5(S44G) active site mutant was more evenly dispersed, indicating that localization required enzyme activity and the availability of pentapeptide substrates. Both the membrane bound and soluble forms of PBP5 converted pentapeptides to tetrapeptides in vitro and in vivo, and the enzymes accepted the same range of substrates, including sacculi, Lipid II, muropeptides and artificial substrates. However, only the membrane‐bound form localized to the developing septum and restored wild‐type rod morphology to shape defective mutants, suggesting that the two events are related. The results indicate that PBP5 localization to sites of ongoing peptidoglycan synthesis is substrate dependent and requires membrane attachment. 相似文献
995.
Yvonne Meyer-Lucht Celine Otten Thomas Püttker Renata Pardini Jean Paul Metzger Simone Sommer 《Conservation Genetics》2010,11(5):2001-2013
The adaptive potential of a species to a changing environment and in disease defence is primarily based on genetic variation.
Immune genes, such as genes of the major histocompatibility complex (MHC), may thereby be of particular importance. In marsupials,
however, there is very little knowledge about natural levels and functional importance of MHC polymorphism, despite their
key role in the mammalian evolution. In a previous study, we discovered remarkable differences in the MHC class II diversity
between two species of mouse opossums (Gracilinanus microtarsus, Marmosops incanus) from the Brazilian Atlantic forest, which is one of the most endangered hotspots for biodiversity conservation. Since the
main forces in generating MHC diversity are assumed to be pathogens, we investigated in this study gastrointestinal parasite
burden and functional associations between the individual MHC constitution and parasite load. We tested two contrasting scenarios,
which might explain differences in MHC diversity between species. We predicted that a species with low MHC diversity would
either be under relaxed selection pressure by low parasite diversity (‘Evolutionary equilibrium’ scenario), or there was a recent loss in MHC diversity leading to a lack of resistance alleles and increased parasite burden
(‘Unbalanced situation’ scenario). In both species it became apparent that the MHC class II is functionally important in defence against gastrointestinal
helminths, which was shown here for the first time in marsupials. On the population level, parasite diversity did not markedly
differ between the two host species. However, we did observe considerable differences in the individual parasite load (parasite
prevalence and infection intensity): while M. incanus revealed low MHC DAB diversity and high parasite load, G. microtarsus showed a tenfold higher population wide MHC DAB diversity and lower parasite burden. These results support the second scenario
of an unbalanced situation. 相似文献
996.
997.
Eugene Diatloff Rémi Peyronnet Jean Colcombet Sébastien Thomine Hélène Barbier-Brygoo Jean-Marie Frachisse 《Plant signaling & behavior》2010,5(11):1347-1352
Plant genomes code for channels involved in the transport of cations, anions and uncharged molecules through membranes. Although the molecular identity of channels for cations and uncharged molecules has progressed rapidly in the recent years, the molecular identity of anion channels has lagged behind. Electrophysiological studies have identified S-type (slow) and R-type (rapid) anion channels. In this brief review, we summarize the proposed functions of the R-type anion channels which, like the S-type, were first characterized by electrophysiology over 20 years ago, but unlike the S-type, have still yet to be cloned. We show that the R-type channel can play multiple roles.Key words: R-type anion channel, nitrate, sulphate, guard cell, action potentialAnion channels play a central role in signal transduction, nutrient transport and cell turgor regulation.1 By far, their function was particularly well investigated in the guard cells of stomata using a combination of electrophysiological, pharmacological and genetic tools. In this system, anion channel activation was shown to be one of the limiting steps in the loss of cell turgor leading to stomatal closure.2 In algal cells, anion channels were shown to contribute to membrane excitability through the generation of action potential.1,3With the burst of molecular biology in the nineties, the genes coding for plant ion channels started to be unveiled. The first channel gene to be cloned in plant was the shaker-like potassium channel identified in a yeast functional expression screen.4,5 More than ten years later, TaALMT1 and AtCLCa were characterized as the first members of two important anion channel families.6,7 This growing group of newly identified channels, accounting for electrophysiological activity described long ago, includes the MSLs anion selective mechanosensitive channels.8 Recently, the well known S-type channel has been finally recognized to be encoded by members of the SLAC1 (and other SLAH) family (Slow Anion Channel-Associated 1).9 In agreement with electrophysiological data,10–13 it requires phosphorylation by a Protein Kinase in order to be functional.14,15 In contrast, the molecular identity of the R-type anion channel remains unknown. Therefore, this candidate, which has been functionally known since twenty years, remains the next challenge for plant channel physiologists. 相似文献
998.
999.
Lyme disease risk is increasing in the United States due in part to the spread of blacklegged ticks Ixodes
scapularis, the principal vector of the spirochetal pathogen Borrelia
burgdorferi. A 5-year study was undertaken to investigate hypothesized coinvasion of I. scapularis and B. burgdorferi in Lower Michigan. We tracked the spatial and temporal dynamics of the tick and spirochete using mammal, bird, and vegetation
drag sampling at eight field sites along coastal and inland transects originating in a zone of recent I.
scapularis establishment. We document northward invasion of these ticks along Michigan’s west coast during the study period; this pattern
was most evident in ticks removed from rodents. B.
burgdorferi infection prevalences in I.
scapularis sampled from vegetation in the invasion zone were 9.3% and 36.6% in nymphs and adults, respectively, with the majority of
infection (95.1%) found at the most endemic site. There was no evidence of I. scapularis invasion along the inland transect; however, low-prevalence B.
burgdorferi infection was detected in other tick species and in wildlife at inland sites, and at northern coastal sites in years before
the arrival of I.
scapularis. These infections suggest that cryptic B.
burgdorferi transmission by other vector-competent tick species is occurring in the absence of I.
scapularis. Other Borrelia spirochetes, including those that group with B. miyamotoi and B. andersonii, were present at a low prevalence within invading ticks and local wildlife. Reports of Lyme disease have increased significantly
in the invasion zone in recent years. This rapid blacklegged tick invasion—measurable within 5 years—in combination with cryptic
pathogen maintenance suggests a complex ecology of Lyme disease emergence in which wildlife sentinels can provide an early
warning of disease emergence. 相似文献
1000.
TreeSNPs: a laboratory information management system (LIMS) dedicated to SNP discovery in trees 总被引:1,自引:0,他引:1
Sébastien Clément Joël Fillon Jean Bousquet Jean Beaulieu 《Tree Genetics & Genomes》2010,6(3):435-438
TreeSNPs is a laboratory information management system with a user-friendly Web interface for the gathering and display of
data generated through medium- to large-scale single nucleotide polymorphism (SNP) identification by resequencing, in the
context of whole genome association, outlier detection, quantitative trait locus, and genetic mapping studies. Its multi-gene
approach allows the tracking of all the steps from candidate gene classification and prioritization to SNP discovery. The
system, source code, and documentation are available for download at . An online demo version can also be accessed from the above link. 相似文献