鼠李糖乳杆菌LV108及其发酵乳免疫调节作用的比较

目的 探讨鼠李糖乳杆菌LV108及其发酵乳对免疫抑制小鼠免疫功能的调节作用。 方法 将BALB/c小鼠随机分为5组,每组10只,即空白组(正常小鼠)、模型组(免疫抑制小鼠)、药物组(免疫抑制小鼠食物中添加左旋咪唑)、LV108菌悬液组(免疫抑制小鼠食物中添加LV108菌悬液)和LV108发酵乳组(免疫抑制小鼠食物中添加LV108发酵乳),除空白组外其余组构建免疫抑制小鼠模型。干预4周后,分别测定各组小鼠体质量和脏器指数,血清中白细胞介素2(IL2)、肿瘤坏死因子α(TNFα)和免疫球蛋白G(IgG)含量,血清溶血素含量、耳肿胀度和肝、脾巨噬细胞吞噬能力。 结果 相比模型组,LV108菌悬液组和LV108发酵乳组小鼠体质量增长速度、脏器指数、血清IL2与IgG水平、血清溶血值、耳肿胀度和巨噬细胞吞噬能力显著升高(均P结论 LV108菌体及发酵乳对免疫抑制小鼠具备较全面的免疫调节作用,均可提高小鼠的自身免疫力;LV108发酵乳对小鼠的免疫调节作用强于LV108菌体。     

甘南黄河流域4种典型林分土壤C、N、P化学计量特征

土壤碳（C）、氮（N）、磷（P）是参与植物光合作用和影响生态系统初级生产力的主要元素。甘南高原是黄河流域重要的生态屏障,为了解该区不同林分土壤养分状况的差异,选取该区4种典型林分：云杉林、华北落叶松林、巴山冷杉林以及岷江冷杉糙皮桦混交林为研究对象,研究土壤C、N、P化学计量特征。结果表明：（1）岷江冷杉及糙皮桦混交林土壤C、N含量最高,云杉林土壤N、P含量最低。不同林分间P含量差异显著（P<0.05）,不同土层间C、N含量差异均显著（P<0.05）。（2）云杉林土壤C ： N值显著高于其他林分,岷江冷杉及糙皮桦混交林土壤N ： P及C ： P高于其他林分。（3）海拔、土壤pH、容重与土壤含水量是影响土壤养分的重要因素。土壤C含量与N、P含量均显著相关（P<0.05）。总体来说,不同林分土壤化学计量特征具有显著差异,混交林土壤养分状况较纯林好,未来森林管理和植被建设中,可以通过选择合适的树种和提高树种多样性有效改善森林土壤质量。     

The influence of resprouting forest canopy species on richness in Southern Cape forests, South Africa

We investigated the relationship between species richness and numbers and types of individuals and species present in forests with different physiognomies in the southern Cape Province, South Africa. Data were collected from three different ‘plot’ types: 400 m², canopy‐scaled (plot length is directly proportional to canopy height) and per 100 individuals closest to a point. Plots were designed to control for the effect of scale on local richness. Canopy species richness was inversely proportional to the abundance of resprouting species. The strength of the relationship between the abundance of resprouters and canopy species richness increased progressively from the 400 m² plots to the canopy‐scaled plots and finally to the plots of 100 individuals. Resprouter abundance decreased, while canopy species richness increased, with increasing canopy height. Resprouters are able to retain their in situ position in the forests for longer periods of time than do reseeders. This reduces individual and species turnover, thus reducing species richness in resprouter‐dominated forests.     

Life history variables and risk-taking propensity

We examined the effects of life-history variables on risk-taking propensity, measured by subjective likelihoods of engaging in risky behaviors in five evolutionarily valid domains of risk, including between-group competition, within-group competition, environmental challenge, mating and resource allocation, and fertility and reproduction. The effects of life-history variables on risk-taking propensity were domain specific, except for the expected sex difference, where men predicted greater risk-taking than women in all domains. Males also perceived less inherent risk in actions than females across the five domains. Although the age range in the sample was limited, older respondents showed lower risk propensity in both between- and within-group competition. Parenthood reduced risk-taking propensity in within- and between-group competitions. Higher reproductive goal setting (desiring more offspring) was associated with lower risk-taking propensity. This effect was strongest in the risk domains of mating and reproduction. Having more siblings reduced risk-taking propensity (contrary to our initial prediction) in the domains of environmental challenge, reproduction, and between-group competition. Later-born children showed a higher propensity to engage in environmental and mating risks. Last, shorter subjective life expectancy was associated with increased willingness to take mating and reproductive risks. These results suggest that life-history variables regulate human risk-taking propensity in specific risk domains.     

Assembly of the SIR complex and its regulation by O-acetyl-ADP-ribose, a product of NAD-dependent histone deacetylation

Assembly of silent chromatin domains in budding yeast involves the deacetylation of histone tails by Sir2 and the association of the Sir3 and Sir4 proteins with hypoacetylated histone tails. Sir2 couples deacetylation to NAD hydrolysis and the synthesis of a metabolite, O-acetyl-ADP-ribose (AAR), but the functional significance of NAD hydrolysis or AAR, if any, is unknown. Here we examine the association of the Sir2, Sir3, and Sir4 proteins with each other and histone tails. Our analysis reveals that deacetylation of histone H4-lysine 16 (K16), which is critical for silencing in vivo, is also critical for the binding of Sir3 and Sir4 to histone H4 peptides in vitro. Moreover, AAR itself promotes the association of multiple copies of Sir3 with Sir2/Sir4 and induces a dramatic structural rearrangement in the SIR complex. These results suggest that Sir2 activity modulates the assembly of the SIR complex through both histone deacetylation and AAR synthesis.     

Is docosahexaenoic acid more effective than eicosapentaenoic acid for increasing calcium bioavailability?

Experimental animal and human studies have indicated that long chain polyunsaturated fatty acids (LCPUFA) may enhance calcium absorption, reduce urinary calcium excretion, and increase bone calcium content. In the present study, the effect of LCPUFA, as provided in evening primrose oil, fish and tuna oils, on calcium bioavailability was investigated. Growing male rats were fed a semi-synthetic diet for 6 weeks, after which calcium absorption, bone mineral density (ex vivo), bone calcium content, and bone biomechanics were measured. Calcium absorption, ex vivo bone mineral density, and bone calcium content were significantly higher in the animals fed tuna oil compared with those of a control group fed corn oil. Significant correlations were found between the docosahexaenoic acid (DHA) (22:6n-3) content of the red cell membranes and bone density and bone calcium content. DHA increased accretion of calcium in bone significantly more so than eicosapentaenoic acid (EPA) (20:5n-3).     

Tsc1+ and tsc2+ regulate arginine uptake and metabolism in Schizosaccharomyces pombe

Mutations in either TSC1 or TSC2 cause tuberous sclerosis complex, an autosomal dominant disorder characterized by seizures, mental retardation, and benign tumors of the skin, brain, heart, and kidneys. Homologs for the TSC1 and TSC2 genes have been identified in mouse, rat, Fugu, Drosophila, and in the yeast Schizosaccharomyces pombe. Here we show that S. pombe lacking tsc1+ or tsc2+ have similar phenotypes including decreased arginine uptake, decreased expression of three amino acid permeases, and low intracellular levels of four members of the arginine biosynthesis pathway. Recently, the small GTPase Rheb was identified as a target of the GTPase-activating domain of tuberin in mammalian cells and in Drosophila. We show that the defect in arginine uptake in cells lacking tsc2+ is rescued by the expression of a dominant negative form of rhb1+, the Rheb homolog in S. pombe, but not by expressing wild-type rhb1+. Expression of the tsc2+ gene with a patient-derived mutation within the GAP domain did not rescue the arginine uptake defect in tsc2+ mutant yeast. Taken together, these findings support a model in which arginine uptake is regulated through tsc1+, tsc2+, and rhb1+ in S. pombe and also suggest a role for the Tsc1 and Tsc2 proteins in amino acid biosynthesis and sensing.     

中国环境管理分区:方法与方案

我国生态环境可持续性及其影响因素的区域差异显著,各地区环境管理面临的主要挑战和需要优先解决的生态环境问题不同。进行环境管理分区,根据各地区生态环境特征及其影响因素的差异性,制定有针对性的环境管理政策,将有效促进我国区域生态环境的整体优化。采取定性和定量分析相结合的方法进行我国环境管理分区。首先,在我国3大自然区的基础上,根据我国的自然地理格局和已有的相关区划成果,把我国划分为4个环境管理大区,包括:南部季风区、北部季风区、西北干旱区和青藏高寒区。其次,通过建立的包含13个指标的环境管理分区指标体系,采用一维化欧式距离法分析各环境管理大区下相邻省级行政区环境特征的相似性,把环境特征相似性大的相邻地区划分到同一分区,得到以省级行政区为基本单元的我国环境管理分区方案。然后,结合地区间历史渊源和区域未来发展趋势分析,对基于相似性分析的初步分区方案进行调整,把我国划分为8个以省级行政区为基本单元环境管理区。最后,根据相关调整原则和方法,对以省级行政区为基本单元的分区方案的边界线进行调整,得到以地级行政区为基本单元的分区方案,把我国划分为东北地区、华北平原区、华北山地与高原区、东南沿海地区、长江流域中游地区、西南地区、西北干旱区和青藏高寒区8个环境管理区。