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排序方式: 共有182条查询结果,搜索用时 15 毫秒
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Abstract Seventy phytosociological relevés were performed in 1 m × 1 m plots at 14 study sites spread along sandy shores in northern and southern Sardinia (Italy). The plots were selected in different habitat types (open dunes, native Juniperus woodlands, maquis, and plantations with Acacia, Eucalyptus and Pinus) according to a stratified sampling method in order to investigate impacts deriving from different levels of Carpobrotus spp. cover, dry litter from exotic trees, and other disturbance types. The quantile regression and logistic regression analyses revealed that the reduction in the amount of bryophyte and lichen cover on sand dunes of the study area is caused either by a high cover of Carpobrotus spp. mats or by a high cover of dry exotic litter in dense, unmanaged or poorly managed forest plantations. Additional detrimental effects are often driven by other kinds of man‐made disturbances. Forest management in the coastal areas of Sardinia should be gradually modified to take into account the conservation of bryophytes and lichens. Some of the biological indicators used are quite widespread in the Mediterranean coastal habitats or are exclusively associated with sand dunes; therefore, they can also be conveniently used as indicators of biological impacts in other countries or islands of the same biogeographical region. 相似文献
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Geromy G. Moore Jacalyn L. Elliott Rakhi Singh Bruce W. Horn Joe W. Dorner Eric A. Stone Sofia N. Chulze German G. Barros Manjunath K. Naik Graeme C. Wright Kerstin Hell Ignazio Carbone 《PLoS pathogens》2013,9(8)
Aflatoxins are produced by Aspergillus flavus and A. parasiticus in oil-rich seed and grain crops and are a serious problem in agriculture, with aflatoxin B1 being the most carcinogenic natural compound known. Sexual reproduction in these species occurs between individuals belonging to different vegetative compatibility groups (VCGs). We examined natural genetic variation in 758 isolates of A. flavus, A. parasiticus and A. minisclerotigenes sampled from single peanut fields in the United States (Georgia), Africa (Benin), Argentina (Córdoba), Australia (Queensland) and India (Karnataka). Analysis of DNA sequence variation across multiple intergenic regions in the aflatoxin gene clusters of A. flavus, A. parasiticus and A. minisclerotigenes revealed significant linkage disequilibrium (LD) organized into distinct blocks that are conserved across different localities, suggesting that genetic recombination is nonrandom and a global occurrence. To assess the contributions of asexual and sexual reproduction to fixation and maintenance of toxin chemotype diversity in populations from each locality/species, we tested the null hypothesis of an equal number of MAT1-1 and MAT1-2 mating-type individuals, which is indicative of a sexually recombining population. All samples were clone-corrected using multi-locus sequence typing which associates closely with VCG. For both A. flavus and A. parasiticus, when the proportions of MAT1-1 and MAT1-2 were significantly different, there was more extensive LD in the aflatoxin cluster and populations were fixed for specific toxin chemotype classes, either the non-aflatoxigenic class in A. flavus or the B1-dominant and G1-dominant classes in A. parasiticus. A mating type ratio close to 1∶1 in A. flavus, A. parasiticus and A. minisclerotigenes was associated with higher recombination rates in the aflatoxin cluster and less pronounced chemotype differences in populations. This work shows that the reproductive nature of the population (more sexual versus more asexual) is predictive of aflatoxin chemotype diversity in these agriculturally important fungi. 相似文献
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Chiara Zoppellaro Anna Bin Paola Brun Serena Banzato Veronica Macchi Ignazio Castagliuolo Maria Cecilia Giron 《PloS one》2013,8(8)
Adenosine plays an important role in regulating intestinal motility and inflammatory processes. Previous studies in rodent models have demonstrated that adenosine metabolism and signalling are altered during chronic intestinal inflammatory diseases. However, the involvement of the adenosinergic system in the pathophysiology of gut dysmotility associated to a primary neurodysfunction is still unclear. Recently, we showed that the neurotropic Herpes simplex virus type-1 (HSV-1), orally inoculated to rodents, infects the rat enteric nervous system (ENS) and affects gut motor function without signs of systemic infection. In this study we examined whether changes in purinergic metabolism and signaling occur during permanent HSV-1 infection of rat ENS. Using isolated organ bath assays, we found that contraction mediated by adenosine engagement of A1 or A2A receptors was impaired at 1 and 6 weeks post-viral administration. Immunofluorescence studies revealed that viral infection of ENS led to a marked redistribution of adenosine receptors: A1 and A2B receptors were confined to the muscle layers whereas A2A and A3 receptors were expressed mainly in the myenteric plexus. Viral-induced ENS neurodysfunction influenced adenosine metabolism by increasing adenosine deaminase and CD73 levels in longitudinal muscle-myenteric plexus with no sign of frank inflammation. This study provides the first evidence for involvement of the adenosinergic system during HSV-1 infection of the ENS. As such, this may represent a valid therapeutic target for modulating gut contractility associated to a primary neurodysfunction. 相似文献
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Bianca M Bianca S Vecchio I Raffaele R Ingegnosi C Nicoletti F 《Annales de génétique》2003,46(4):467-469
Gerstmann-Str?ussler-Scheinker disease (GSS) is an adult onset, rare, genetically determined autosomal dominant prion disease. Clinically, it is characterized predominantly by slowly progressive spino-cerebellar dysfunction with ataxia, absent reflexes in the legs and cognitive impairment. Onset is usually in the fifth decade and in the early phase, ataxia is predominant. Mutations in the prion protein gene (PRNP) had been identified and the most important of these is at codon 129. A genotype-phenotype relationship with genetic polymorphism at residue 129 between methionine and valine has been supposed. We describe a patient with GSS and P102L-V129 mutation in which the onset with prominent psychiatric features characterized by apathy and depression and not with cerebellar sign and the clinical course with seizures, nor observed in P102L-V129 cases, allow us to confirm observations that the GSS caused by the 102 mutation is influenced by the codon 129 polymorphism with a specific genotype-phenotype influence, but probably other additional factors might be considered as background for phenotypic variability. 相似文献
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The release of [3H]GABA evoked by depolarization with various concentrations of KCl was studied using superfused rat cerebrocortex synaptosomes. Elevating [K+] produced release of [3H]GABA over basal which was increasingly less dependent on external Ca2+ but more sensitive to the GABA transporter blocker SKF 100330 A. Accordingly, the sensitivity to clostridial toxins of the depolarization-evoked amino acid release was inversely correlated to the concentration of KCl used. However, at 50 mM K+, one-third of the stimulated release remained which was external Ca2+-independent but insensitive to SKF 100330 A. This release was prevented by BAPTA, thapsigargin or dantrolene; it also was inhibited by blocking in mitochondria the ATP production with oligomycin, the H+-dependent Ca2+ uniporter with RU 360, the Na+/Ca2+ exchanger with CGP 37157 or by lowering extraterminal [Na+]. In fluorescence experiments with fura-2/AM, 50 mM K+ (in Ca2+ free medium) caused elevation of cytosolic [Ca2+] that was sensitive to thapsigargin or CGP 37157; these compounds produced partially additive effects. When exocytosis was monitored with the fluorescent dye acridine orange, the fluorescence elicited by 50 mM K+ was sensitive to thapsigargin or CGP 37157, which produced additive effects, and to low-Na+ media. To conclude, extracellular K+ concentrations occurring in the CNS in certain pathological conditions provoke GABA release by mechanisms different from classical exocytosis. These include carrier-mediated release and internal Ca2+-dependent exocytosis; in the latter, mitochondrial Ca2+ seems to play a primary role. 相似文献