A new method for identifying rapid decline dynamics in wild vertebrate populations

Tracking trends in the abundance of wildlife populations is a sensitive method for assessing biodiversity change due to the short time‐lag between human pressures and corresponding shifts in population trends. This study tests for proposed associations between different types of human pressures and wildlife population abundance decline‐curves and introduces a method to distinguish decline trajectories from natural fluctuations in population time‐series. First, we simulated typical mammalian population time‐series under different human pressure types and intensities and identified significant distinctions in population dynamics. Based on the concavity of the smoothed population trend and the algebraic function which was the closest fit to the data, we determined those differences in decline dynamics that were consistently attributable to each pressure type. We examined the robustness of the attribution of pressure type to population decline dynamics under more realistic conditions by simulating populations under different levels of environmental stochasticity and time‐series data quality. Finally, we applied our newly developed method to 124 wildlife population time‐series and investigated how those threat types diagnosed by our method compare to the specific threatening processes reported for those populations. We show how wildlife population decline curves can be used to discern between broad categories of pressure or threat types, but do not work for detailed threat attributions. More usefully, we find that differences in population decline curves can reliably identify populations where pressure is increasing over time, even when data quality is poor, and propose this method as a cost‐effective technique for prioritizing conservation actions between populations.     

A global analysis of the determinants of alien geographical range size in birds

Aim Determining the causes of range size variation in the distributions of alien species is important for understanding the spread of invasive species. Factors influencing alien range size have been explored for some species at a regional level, but to date there has been no global analysis of an entire class. Here, we present such an analysis for birds, testing for the effects of introduction event, location and species‐level variables on alien range sizes. Location Global. Methods We used a novel dataset on the global distributions of alien bird species to test for relationships between alien range size and colonization pressure, residence time, extent of the global climatic niche, native range size, body mass and specialization, using a statistical approach based on phylogenetic generalized least squares models. We performed this analysis globally, and for separate biogeographical realms. Results Approximately half of the variation in alien bird range size is explained by colonization pressure in univariate analysis. We identified consistent effects of higher colonization pressure at global and realm levels, as well as support for effects of native range size and residence time. We found less support for effects of body mass, specialization or extent of the global climatic niche on alien range size. Main conclusions Alien bird range sizes are generally small relative to their native range sizes, and many are continuing to expand. Nevertheless, current variation is predictable, most strongly by the event‐level factor of colonization pressure. Whether a species is widespread is a better predictor of alien range size than whether a species could be widespread (estimated by global climatic niche extent), while we also find effects of residence time on alien range size. These relationships may help to identify those alien species that are more likely to spread and hence have greater environmental and economic impacts where they have been introduced.     

Involvement of 1,25D3-MARRS (membrane associated, rapid response steroid-binding), a novel vitamin D receptor, in growth inhibition of breast cancer cells

In addition to classical roles in calcium homeostasis and bone development, 1,25 dihydroxyvitamin D₃ [1,25(OH)₂D₃] inhibits the growth of several cancer types, including breast cancer. Although cellular effects of 1,25(OH)₂D₃ traditionally have been attributed to activation of a nuclear vitamin D receptor (VDR), a novel receptor for 1,25(OH)₂D₃ called 1,25D₃-MARRS (membrane-associated, rapid response steroid-binding) protein was identified recently. The purpose of this study was to determine if the level of 1,25D₃-MARRS expression modulates 1,25(OH)₂D₃ activity in breast cancer cells.Relative levels of 1,25D₃-MARRS protein in MCF-7, MDA MB 231, and MCF-10A cells were estimated by real-time RT-PCR and Western blotting. To determine if 1,25D₃-MARRS receptor was involved in the growth inhibitory effects of 1,25(OH)₂D₃ in MCF-7 cells, a ribozyme construct designed to knock down 1,25D₃-MARRS mRNA was stably transfected into MCF-7 cells. MCF-7 clones in which 1,25D₃-MARRS receptor expression was reduced showed increased sensitivity to 1,25(OH)₂D₃ ( IC₅₀ 56 ± 24 nM) compared to controls (319 ± 181 nM; P < 0.05). Reduction in 1,25D₃-MARRS receptor lengthened the doubling time in transfectants treated with 1,25(OH)₂D₃. Knockdown of 1,25D₃-MARRS receptor also increased the sensitivity of MCF-7 cells to the vitamin D analogs KH1060 and MC903, but not to unrelated agents (all-trans retinoic acid, paclitaxel, serum/glucose starvation, or the isoflavone, pomiferin). These results suggest that 1,25D₃-MARRS receptor expression interferes with the growth inhibitory activity of 1,25(OH)₂D₃ in breast cancer cells, possibly through the nuclear VDR. Further research should examine the potential for pharmacological or natural agents that modify 1,25D₃-MARRS expression or activity as anticancer agents.     

鄱阳湖水生维管束植物生物量及其合理开发利用的初步建议

用4种不同的计算方法测定了鄱阳湖水生维管束植物的生物量。根据22个断面,199个采集点,398个样方的测定结果,得出鄱阳湖水生维管束植物的年生产量为431.76万吨(湿重),即相当于5.44×10~(-15)焦耳(能量)。其中,马来眼子菜、苦草和黑藻等3种合计约占总生物量的71.46%。全湖可供草食性鱼类食用的水生维管束植物约占总量的86.9%。文中还对4个植物带和9个群丛生物量的分布规律进行了讨论。提出了人工增殖草食性鱼类,调整湖中植被组成,保护和种植水生经济植物等合理开发利用鄱阳湖水生植物资源的初步建议。     

纳米颗粒Gd@C_(82)(OH)_(22)抑制哺乳动物细胞外排转运的研究

目的 探讨纳米颗粒Gd@C_(82)(OH)_(22)体外对哺乳动物细胞外排转运的影响,研究该外排转运抑制作用与MRP1蛋白和ATP酶活性间的关系,为Gd@C_(82)(OH)_(22)应用于耐药肿瘤治疗提供初步实验依据.方法 通过Calcein-AM(C-AM)摄入法,以仓鼠肾细胞BHK-21、转染表达多药耐药相关蛋白MRP1的BHK-21/MRP1细胞以及肿瘤细胞PC-3为模型测定Gd@C_(82)(OH)_(22)对细胞外排转运的整体影响;用比色法测定Gd@C_(82)(OH)_(22)对MRP1蛋白截短体及BHK-21/MRP1质膜微囊的ATP酶活性的影响.结果 经Gd@C_(82)(OH)_(22)处理后,3种细胞的C-AM摄入量均上调,BHK-21与BHK-21/MRP1摄入量增加相似;用MRP1抑制剂MK571处理BHK-21/MRP1后,细胞C-AM摄入增长趋势不变;Gd@C_(82)(OH)_(22)对MRP1蛋白截短体及质膜微囊的ATP酶活性没有抑制作用.结论 表明Gd@C_(82)(OH)_(22)可抑制哺乳动物细胞的外排转运,其抑制作用并不是通过抑制MRP1蛋白或ATP酶活性来实现的.     

赤潮棕囊藻(Phaeocystis globosa)rDNA ITS区序列变异与二级结构分析

测定了南海球形棕囊藻香港株P1、P2和湛江株ZhJ1的rDNAITS区序列(含5.8srDNA),结合Gen Bank的13条同源序列,比对长度为904bp,变异位点271个,简约信息位点221个,平均(A+T)(34.5%)<(G+C)(65.4%).藻株P1、P2和ZhJ1序列存在变异位点20个,序列间相似性为97.9%～98.5%.ITS序列在种间和种内的解析度高于18srDNA和28srDNA基因;构建的NJ树、MP树、贝叶斯推断系统树的结构是一致的,不同种类的棕囊藻单独聚类,不同地理来源的球形棕囊藻混杂分布但相同地理来源的藻株多聚类在一起.RNA二级结构显示,不同藻种间5.8srDNA区结构基本一致,表现出属的特异性;ITS1、2区结构表现较大的种间差异,表明ITS区RNA二级结构可为棕囊藻分类鉴定提供有用的分子结构信息.     

基于临界氮浓度的小麦地上部氮亏缺模型

基于3年的大田试验,选择代表性的中蛋白小麦品种（扬麦16）和低蛋白小麦品种（宁麦13）,分别构建了小麦地上部干物质临界氮浓度(N_cnc)稀释曲线模型、氮营养指数（NNI）模型和氮亏缺(N_and)模型.结果表明： 小麦地上部干物质临界氮浓度稀释曲线模型具有明确的生物学意义,小麦临界氮浓度与地上部最大干物质（DM）符合幂函数关系（扬麦16为N_cnc=4.65DM^-0.44;宁麦13为N_cnc=4.33DM^-0.45）;小麦地上部氮营养指数模型可以准确诊断氮素营养状况;小麦地上部氮亏缺模型可以定量调控氮肥管理措施.利用2007-2008年的独立试验资料对小麦地上部干物质临界氮浓度稀释模型、氮营养指数模型和氮亏缺模型进行检验和测试,结果表明模型的准确性较高,普适性较强.本文所构建模型可以直接用于诊断调控小麦氮素营养,为小麦生产中精确施肥管理提供了较好的技术途径和理论基础.