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991.
Astrid Cruaud Roula Jabbour‐Zahab Gwenaëlle Genson Corinne Cruaud Arnaud Couloux Finn Kjellberg Simon Van Noort Jean‐Yves Rasplus 《Cladistics : the international journal of the Willi Hennig Society》2010,26(4):359-387
A phylogeny of the Agaonidae (Chalcidoidea) in their restricted sense, pollinators of Ficus species (Moraceae), is estimated using 4182 nucleotides from six genes, obtained from 101 species representing 19 of the 20 recognized genera, and four outgroups. Data analysed by parsimony and Bayesian inference methods demonstrate that Agaonidae are monophyletic and that the previous classification is not supported. Agaonidae are partitioned into four groups: (i) Tetrapus, (ii) Ceratosolen + Kradibia, (iii) some Blastophaga + Wiebesia species, and (iv) all genera associated with monoecious figs and a few Blastophaga and Wiebesia. The latter group is subdivided into subgroups: (i) Pleistodontes, (ii) Blastophaga psenes and neocaledonian Dolichoris, (iii) some Blastophaga and Wiebesia species, and (iv) Platyscapa, all afrotropical genera and all genera associated with section Conosycea. Eleven genera were recovered as monophyletic, six were para‐ or polyphyletic, and two cannot be tested with our data set. Based on our phylogeny we propose a new classification for the Agaonidae. Two new subfamilies are proposed: Tetrapusiinae for the genus Tetrapus, and Kradibiinae for Ceratosolen + Kradibia. Liporrhopalum is synonymized with Kradibia and the subgenus Valisia of Blastophaga is elevated to generic rank. These changes resulted in 36 new combinations. Finally, we discuss the hypothesis of co‐speciation between the pollinators and their host species by comparing the two phylogenies. © The Willi Hennig Society 2009. 相似文献
992.
Robert Lam Vladimir Romanov Kathy Johns Kevin P. Battaile Jean Wu‐Brown Jennifer L. Guthrie Robert P. Hausinger Emil F. Pai Nickolay Y. Chirgadze 《Proteins》2010,78(13):2839-2848
Urease plays a central role in the pathogenesis of Helicobacter pylori in humans. Maturation of this nickel metalloenzyme in bacteria requires the participation of the accessory proteins UreD (termed UreH in H. pylori), UreF, and UreG, which form sequential complexes with the urease apoprotein as well as UreE, a metallochaperone. Here, we describe the crystal structure of C‐terminal truncated UreF from H. pylori (residues 1–233), the first UreF structure to be determined, at 1.55 Å resolution using SAD methods. UreF forms a dimer in vitro and adopts an all‐helical fold congruent with secondary structure prediction. On the basis of evolutionary conservation analysis, the structure reveals a probable binding surface for interaction with other urease components as well as key conserved residues of potential functional relevance. Proteins 2010. © 2010 Wiley‐Liss, Inc. 相似文献
993.
Stéphanie Gobin-Limballe Ryan P. McAndrew Fatima Djouadi Jung-Ja Kim Jean Bastin 《生物化学与生物物理学报:疾病的分子基础》2010,1802(5):478-484
Very-Long-Chain Acyl-CoA Dehydrogenase deficiency (VLCADD) is an autosomal recessive disorder considered as one of the more common ß-oxidation defects, possibly associated with neonatal cardiomyopathy, infantile hepatic coma, or adult-onset myopathy. Numerous gene missense mutations have been described in these VLCADD phenotypes, but only few of them have been structurally and functionally analyzed, and the molecular basis of disease variability is still poorly understood. To address this question, we first analyzed fourteen disease-causing amino acid changes using the recently described crystal structure of VLCAD. The predicted effects varied from the replacement of amino acid residues lining the substrate binding cavity, involved in holoenzyme–FAD interactions or in enzyme dimerisation, predicted to have severe functional consequences, up to amino acid substitutions outside key enzyme domains or lying on near enzyme surface, with predicted milder consequences. These data were combined with functional analysis of residual fatty acid oxidation (FAO) and VLCAD protein levels in patient cells harboring these mutations, before and after pharmacological stimulation by bezafibrate. Mutations identified as detrimental to the protein structure in the 3-D model were generally associated to profound FAO and VLCAD protein deficiencies in the patient cells, however, some mutations affecting FAD binding or monomer–monomer interactions allowed a partial response to bezafibrate. On the other hand, bezafibrate restored near-normal FAO rates in some mutations predicted to have milder consequences on enzyme structure. Overall, combination of structural, biochemical, and pharmacological analysis allowed assessment of the relative severity of individual mutations, with possible applications for disease management and therapeutic approach. 相似文献
994.
Mireia Martín-Satué Elise G. Lavoie Michel Fausther Joanna Lecka Elisabet Aliagas Filip Kukulski Jean Sévigny 《Histochemistry and cell biology》2010,133(6):659-668
Extracellular ATP and its hydrolysis product adenosine modulate various reproductive functions such as those requiring contraction,
steroidogenesis, and maintenance of fluid composition. Interestingly, adenosine might act as a key capacitative effector for
mammalian spermatozoa to acquire the capacity for fertilisation. Extracellular nucleotide levels are affected by cell surface
ectonucleotidases, amongst which the ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) family regroups the most abundant
and effective enzymes to hydrolyse ATP and ADP to AMP in physiological conditions. In the male reproductive tract three members
of this family have been indentified: NTPDase1, NTPDase2 and NTPDase3 (Martín-Satué et al. in Histochem Cell Biol 131:615–628,
2009). The purpose of the present study was to characterize in the male reproductive tract the expression profile of the main
enzyme responsible for the generation of adenosine from AMP, namely the ecto-5′-nucleotidase (CD73). The enzyme was identified
by immunological techniques and by in situ enzymatic assays, including inhibition experiments with α,β-methylene-ADP, a specific
CD73 inhibitor. High levels of ecto-5′-nucleotidase were detected in testes in association with both germinal and somatic
cells, in smooth muscle cells throughout the tract, in secretory epithelia from exocrine glands, and remarkably, in principal
cells of epididymis, where co-localization with NTPDase3 was found. The relevance of this co-expression on nucleotide hydrolysis
in these cells directly involved in the control of sperm fluid composition was addressed biochemically. This study suggests
close regulation of extracellular nucleoside and nucleotide levels in the genital tract by ecto-5′-nucleotidase that, in concurrence
with NTPDases, may impact male fertility. 相似文献
995.
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
996.
997.
998.
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
999.
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
1000.