21st century climate change threatens mountain flora unequally across Europe

Continental‐scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill‐suited for assessment of species‐specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high‐resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high‐resolution analyses consistently indicate marked levels of threat to cold‐adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation.     

Habitat Fragmentation can Modulate Drought Effects on the Plant-soil-microbial System in Mediterranean Holm Oak (<Emphasis Type="Italic">Quercus ilex</Emphasis>) Forests

Ecological transformations derived from habitat fragmentation have led to increased threats to above-ground biodiversity. However, the impacts of forest fragmentation on soils and their microbial communities are not well understood. We examined the effects of contrasting fragment sizes on the structure and functioning of soil microbial communities from holm oak forest patches in two bioclimatically different regions of Spain. We used a microcosm approach to simulate the annual summer drought cycle and first autumn rainfall (rewetting), evaluating the functional response of a plant-soil-microbial system. Forest fragment size had a significant effect on physicochemical characteristics and microbial functioning of soils, although the diversity and structure of microbial communities were not affected. The response of our plant-soil-microbial systems to drought was strongly modulated by the bioclimatic conditions and the fragment size from where the soils were obtained. Decreasing fragment size modulated the effects of drought by improving local environmental conditions with higher water and nutrient availability. However, this modulation was stronger for plant-soil-microbial systems built with soils from the northern region (colder and wetter) than for those built with soils from the southern region (warmer and drier) suggesting that the responsiveness of the soil-plant-microbial system to habitat fragmentation was strongly dependent on both the physicochemical characteristics of soils and the historical adaptation of soil microbial communities to specific bioclimatic conditions. This interaction challenges our understanding of future global change scenarios in Mediterranean ecosystems involving drier conditions and increased frequency of forest fragmentation.     

Soil characteristics influence species composition and forest structure differentially among tree size classes in a Bornean heath forest

Plant and Soil - To investigate how different tree species affect the composition of SOM and its mineralization in boreal forest ecosystems. We used pyrolysis GC–MS for molecular-level...     

Increases in Na/K pump numbers in isolated human lymphocytes exposed to lithium in vitro. Reversal by myo-inositol and by inhibitors of protein kinase C and the Na/H antiport

Lithium (1-8 mM) caused a dose-dependent increase in the number of [3H]ouabain binding sites and in sodium/potassium (Na/K) pump activity in normal lymphocytes after incubation for 72 h. The increase in Na/K pump activity was due to an increase in the Vmax of the pump, with no change in the apparent affinity (Km) for potassium (rubidium). There was no change in the turnover number of the pump and the intracellular sodium concentration fell. The increase in [3H]ouabain binding sites was prevented by the addition of myo-inositol (10 mM), by inhibition of the protein kinase C with staurosporine (100 nM) and by inhibition of the Na/H antiport with dimethylamiloride (50 microM). These results suggest that the increase in Na/K pump activity caused by lithium is due to an increase in pump numbers and not due to increased activity of individual pumps or to an alteration in the affinity of the pumps for potassium. The increase in Na/K pump numbers and activity in lymphocytes exposed to lithium for 72 h may be related to altered Na/H antiport activity secondary to inhibition of phosphoinositol breakdown by lithium.     

Optimal timing of operation for bleeding peptic ulcer: prospective randomised trial.

From October 1980 to September 1983 all patients with upper gastrointestinal bleeding were admitted to a centralised unit and investigated by early endoscopy. A total of 142 patients with a proved duodenal or gastric ulcer were randomised after stratification for age and site of ulcer to early (aggressive) surgical management or a delayed (conservative) policy. Significantly more operations (n = 42; 60%) were performed in the early than in the delayed (n = 9; 20%) groups (p less than 0.01). There were no deaths among the 42 patients under 60. The overall mortality in the 100 patients aged over 60 was 10% and when analysed on an "intention to treat" basis there was no difference between early and delayed surgery. When, however, an unrelated death from a bleeding colonic polyp was excluded and the data analysed on "treatment received" the mortality was only 2% in the early group compared with 13% in the delayed group (p less than 0.05). When analysis was confined to gastric ulcer the difference between early (0%) and delayed (24%) treatment was even greater. The results of this trial indicate that for patients over 60 an aggressive surgical policy is associated with a significant reduction in mortality.     

Gibberellin modulation of phosphatidyl-choline turnover in wheat aleurone tissue

Phosphatidyl choline (PC) is synthesised in wheat (Triticum aestivum L. cv. Flanders) aleurone tissue during early germination when new endomembranes are being formed. Although gibberellic acid does not ostensibly affect PC levels, it inhibits the incorporation of choline and differentially and specifically modulates the turnover of the N-methyl and methylene carbons of the choline headgroup of PC. Gibberellic acid has no effect on turnover of the phosphate moiety of either PC or the other major phosphatides. The possible biological importance of the findings is discussed.Abbreviations ER endoplasmic reticulum - GA gibberellin - GA₃ gibberellic acid - PA phosphatidic acid - PC phosphatidyl choline - PE phosphatidyl ethanolamine - PG phosphatidyl glycerol - PI phosphatidyl inositol - t_1/2 half-life     

体外细胞核组装中核纤层与核膜的关系

采用非洲爪蟾卵提取物非细胞体系,以外源Lambda DNA诱导细胞核的体外组装,以此实验模式为基础,研究了细胞核体外组装过程中核纤层的组装,结果表明核纤层蛋白参与细胞核的体外组装过程,核内骨架的组装与核纤层的组装在时间上是有序的,核内骨架的组装可能为核纤层的装配提供了先决条件.在非洲爪蟾卵提取物非细胞体系中加入抗核纤层蛋白抗体,抑制核纤层的正常装配过程,核膜组装发生异常.结果提示核纤层的组装与核膜的组装是密切相关的.     

Further studies on synaptic junctions

Summary Synaptic junctions in intact rat cerebral cortex have been examined following glutaraldehyde fixation and phosphotungstic acid (PTA) staining. In the presynaptic ending the network has a hexagonal arrangement, while the dense projections are regularly placed along the presynaptic membrane. Cleft densities occupy the intracleft region. The postsynaptic thickening extends uninterrupted along the length of the junction. Qualitatively, the majority of junctions fall into the discontinuous-continuous category, in which the internal coat of the presynaptic membrane together with its associated dense projections is discontinuous along the length of the junction, whereas the postsynaptic thickening is continuous. By contrast, a small number of junctions are continuous-continuous.In an attempt to analyze the junctions quantitatively, nine indices were measured. Histograms of the size distributions of seven of these appear to be bimodal, and from this it is concluded that two junction populations may be distinguishable on quantitative grounds. It is also shown that the distance separating dense projections at the presynaptic membrane is of the order of 10–15 nm. This surprisingly low value has consequences for current ideas on the relationship between synaptic vesicles and dense projections, and these are discussed at length.We would like to acknowledge the technical assistance of Mrs. C. Blackshaw, Mrs. G. Kay and Mr. D. Stuart.     

中国番茄黄化曲叶病毒——双生病毒的一个新种

用 2 0个单抗对中国番茄黄化曲叶病毒 (TYLCV CHI)和其他双生病毒进行了测定 ,在血清学水平上证实中国番茄黄化曲叶病毒与中国烟草曲叶病毒有较大的亲缘关系 ;同时报道了TYLCV CHI部分共同区、外壳蛋白N端基因和AV1基因的PCR及其克隆和序列分析 ,从分子水平上证实TYLCV CHI与世界各地的其他双生病毒不同 ,是一种新的粉虱传双生病毒