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681.
Helen E. Roy Jodey Peyton David C. Aldridge Tristan Bantock Tim M. Blackburn Robert Britton Paul Clark Elizabeth Cook Katharina Dehnen‐Schmutz Trevor Dines Michael Dobson François Edwards Colin Harrower Martin C. Harvey Dan Minchin David G. Noble Dave Parrott Michael J. O. Pocock Chris D. Preston Sugoto Roy Andrew Salisbury Karsten Schönrogge Jack Sewell Richard H. Shaw Paul Stebbing Alan J. A. Stewart Kevin J. Walker 《Global Change Biology》2014,20(12):3859-3871
Invasive alien species (IAS) are considered one of the greatest threats to biodiversity, particularly through their interactions with other drivers of change. Horizon scanning, the systematic examination of future potential threats and opportunities, leading to prioritization of IAS threats is seen as an essential component of IAS management. Our aim was to consider IAS that were likely to impact on native biodiversity but were not yet established in the wild in Great Britain. To achieve this, we developed an approach which coupled consensus methods (which have previously been used for collaboratively identifying priorities in other contexts) with rapid risk assessment. The process involved two distinct phases:
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682.
The Role of Nitrogen Deposition in Widespread Plant Community Change Across Semi-natural Habitats 总被引:1,自引:0,他引:1
Chris D. Field Nancy B. Dise Richard J. Payne Andrea J. Britton Bridget A. Emmett Rachel C. Helliwell Steve Hughes Laurence Jones Steven Lees Jonathan R. Leake Ian D. Leith Gareth K. Phoenix Sally A. Power Lucy J. Sheppard Georgina E. Southon Carly J. Stevens Simon J. M. Caporn 《Ecosystems》2014,17(5):864-877
Experimental studies have shown that deposition of reactive nitrogen is an important driver of plant community change, however, most of these experiments are of short duration with unrealistic treatments, and conducted in regions with elevated ambient deposition. Studies of spatial gradients of pollution can complement experimental data and indicate whether the potential impacts demonstrated by experiments are actually occurring in the ‘real world’. However, targeted surveys exist for only a very few habitats and are not readily comparable. In a coordinated campaign, we determined the species richness and plant community composition of five widespread, semi-natural habitats across Great Britain in sites stratified along gradients of climate and pollution, and related these ecological parameters to major drivers of biodiversity, including climate, pollution deposition, and local edaphic factors. In every habitat, we found reduced species richness and changed species composition associated with higher nitrogen deposition, with remarkable consistency in relative species loss across ecosystem types. Whereas the diversity of mosses, lichens, forbs, and graminoids declines with N deposition in different habitats, the cover of graminoids generally increases. Considered alongside previous experimental studies and survey work, our results provide a compelling argument that nitrogen deposition is a widespread and pervasive threat to terrestrial ecosystems. 相似文献
683.
Invasive plants that displace native floral communities can cause changes to associated invertebrate species assemblages. Using a mini‐review of the literature and our own data we add to the still considerable debate about the most effective methods for testing community‐level impacts by invasive species. In endangered saltmarshes of southeast Australia, the non‐native rush Juncus acutus L. is displacing its native congener J. kraussii Hochst., with concurrent changes to floral and faunal assemblages. In two coastal saltmarshes, we tested the hypothesis that the ability to detect differences in the invertebrate assemblage associated with these congeneric rushes depends on the microhabitat of the plant sampled. We used three sampling methods, each targeting specific microhabitats: sweep netting of the plant stems, vacuum sampling of the plant tussock, and vacuum sampling of the ground directly below the plants. Over 3800 individuals and 92 morphospecies were collected across four main taxa: gastropods, crustaceans, hexapods and arachnids. Detection of differences in invertebrate density, richness and composition associated with native compared with non‐native rushes was dependent on the microhabitat sampled and these differences were spatially variable. For example, at one saltmarsh the stems and tussock of J. acutus had a lower density and richness of total invertebrates and hexapods than those of the native J. kraussii. In contrast, crustaceans on the ground were in greater abundance below J. acutus than J. kraussii. This study demonstrates that on occasions where overall differences in the assemblage are not detected between species, differences may become apparent when targeting different microhabitats of the plant. In addition, separately targeting multiple microhabitats likely leads to a greater probability of detecting impacts of invasion. Comparing the invertebrate assemblage without differentiating between or sampling an array of microhabitats can fail to determine the impact of invasive species. These results highlight that a combination of methods targeting different microhabitats is important for detecting differences within the invertebrate community, even for phylogenetically related species. 相似文献
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In this paper the essential GTPase YlqF is shown to participate in the biogenesis of the 50S ribosomal subunit in Bacillus subtilis. Cells depleted of YlqF displayed gene expression profiles and nucleoid morphologies that were consistent with a function for YlqF in translation. In addition, YlqF is evolutionarily linked to two eukaryotic GTPases, Nog2p and Nug1p, that are involved in the biogenesis and the nuclear export of the 60S ribosomal subunit. Analysis of ribosomes from cells depleted of YlqF demonstrated that the formation of 70S ribosomes was greatly reduced and the large subunit sedimented at 45S. Cells grown with varying depleted levels of YlqF, yielding doubling times ranging from 38 min to 150 min, all displayed the 45S intermediate. Purified YlqF-His(6) protein associates with the 45S intermediate, but not the mature 50S subunit in vitro. Analysis of proteins from the 45S intermediate indicated that ribosomal protein L16, which is added late during in vitro Escherichia coli 50S ribosome biogenesis, was missing from the 45S intermediate. These results support a model in which YlqF participates in the formation of active 70S ribosomes in the cell by functioning in a late step of 50S subunit biogenesis. Based on these results we propose to rename the ylqF gene rbgA (ribosome biogenesis GTPase A). 相似文献
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Paul Clark Laurence J Britton Lawrie W Powell 《The Clinical biochemist. Reviews / Australian Association of Clinical Biochemists》2010,31(1):3-8
Hereditary haemochromatosis (HH) is a common genetic disorder of iron metabolism in individuals of Northern European ancestry which leads to inappropriate iron absorption from the intestine and iron overload in susceptible individuals. Iron overload is suggested by elevations in serum ferritin and transferrin saturation. The majority of patients with clinically significant iron overload are homozygous for the C282Y mutation of the HFE gene, however only a minority of C282Y homozygotes fully express the disease clinically. Those with a high serum ferritin (>1000 μg/L) and additional hepatic insults from cofactors are more likely to develop cirrhosis and its complications. The mainstay of treatment is venesection. Those without cirrhosis who undergo appropriate venesection have a normal life expectancy. Family screening is recommended for all first degree relatives of an individual with the disease.HH refers to a group of inherited disorders that result in progressive iron overload. Mutations of the HFE gene are responsible for the majority of cases of HH,1 although disease expression is highly variable.2 The ready availability of testing for the two clinically relevant mutations: C282Y and H63D, has substantially altered the approach to suspected iron overload in clinical practice. A number of rare but important forms of non-HFE related HH have also been described.3 The other main causes of iron overload are outlined in the HH HFE related HH (C282Y/C282Y, C282Y/H63D) Non-HFE related HH Juvenile Haemochromatosis Hemojuvelin related Hepcidin related Transferrin receptor-2 related HH Ferroportin related HH Secondary Iron Overload Iron loading anaemia Thalassaemia major Sideroblastic anaemia Chronic haemolytic anaemia Parenteral iron overload (multiple transfusions) Others Metabolic syndrome Chronic liver disease Hepatitis C Alcoholic liver disease Non-alcoholic steatohepatitis Porphyria cutanea tarda African Iron Overload Acaeruloplasminaemia Atransferrinaemia Neonatal iron overload