群落构建研究的新进展:进化和生态相结合的群落谱系结构研究

群落如何构建足群落生态学中的重要问题.群落谱系结构研究将物种间的亲缘进化关系运用到群落生态学研究中,利用物种的系统发育状况推测历史因素对现有群落的影响,为推断影响群落组成的生态学机制提供了有效方法.群落谱系结构的研究方法是首先建立可代表群落物种库的超级系统进化树,然后计算群落内物种间的谱系距离,最后通过统计方法检测其与随机模型下的谱系距离是否有显著差异来获得谱系结构(如谱系聚集、谱系发散),从而揭示群落构建中的关键生态过程(如生境过滤、竞争作用).群落谱系结构与空间尺度、分类群尺度、时间尺度等不同研究尺度有关.在小的空间尺度下,随着分类群尺度降低、树木年龄级增大,群落谱系结构从聚集逐渐转为发散;而随群落空间尺度的增大,谱系趋向于聚集.谱系结构受到环境因素影响,因此分析集合群落下的谱系可以揭示区域生态过程的影响.另外,群落谱系结构研究还有助于探讨中性理论、密度制约假说等生态学理论,并预测干扰作用下的群落演化趋势.在利用谱系结构深入探讨群落构建成因时,需要基于生态特征和环境变量共同分析,同时考虑小尺度局域过程(群落的微环境或群落内种间相互作用等)和大尺度区域过程(地史过程和物种形成等),并可结合生态控制实验,以确认群落构建的关键因素.在研究方法和手段上,今后需要注重通过选择合适的基因片段建立系统树,然后通过生态特征来加以校正,以更准确地反映物种间的亲缘距离.另外,获得谱系树后还需要寻找更加合理的统计模型和指数,增加统计分析和解决问题的能力.     

Construct synthetic gene encoding artificial spider dragline silk protein and its expression in milk of transgenic mice

Based on the known partial cDNA sequence of dragline silk protein an artificial gene monomer, a 360 bp sequence, was designed and polymerized to encode an analog of dragline silk protein. Six tandem copies of monomer were cloned into pBC1 vector and microinjected into the pronuclei of fertilized Kunming White eggs. Transgenic mice were screened by Polymerase Chain Reaction (PCR) and Southern blot which revealed that 10 mice (5 male, 5 female) among 58 mice were transgenic positive. Milk of five F0 mice and eight F1 mice was analyzed by Western blot, and two F0 mice and seven F1 mice expressed recombinant dragline silk protein. In transgenic mice milk a maximum of concentration of recombinant dragline silk protein was 11.7 mg/L by radioimmunoassay.     

The EGFP/hERG fusion protein alter the electrophysiological properties of hERG channels in HEK293 cells

EGFP (enhanced green fluorescent protein) tagged to either the N (amino)-terminus [EGFP/hERG (human ether-a-go-go-related gene)] or C (carboxyl)-terminus (hERG/EGFP) of hERG channel is used to study mutant channel protein trafficking for several years. However, it has been reported that the process can alter hERG channel properties. The aim of the study was to determine whether EGFP tagged to N-terminus of hERG channels would alter the cellular localizations and the electrophysiological properties of hERG channels compared with untagged hERG channels. The hERG channels tagged with or without EGFP were transiently expressed in HEK (human embryonic kidney) 293 cells using a lipofectamine method. HEK 293 cells expressing pCDNA3-hERG or pEGFP-hERG were double immunolabelled with anti-hERG and anti-calnexin (an ER marker protein) followed with FITC- and TRITC (tetramethylrhodamine β-isothiocyanate)-labelled secondary antibodies, respectively. Confocal laser scanning microscope was used to observe the cellular localization of EGFP-tagged hERG channels and untagged hERG channels. Patch-clamp technique was used to record whole cell currents. We found that the EGFP/hERG fusion protein and untagged hERG channels were both expressed not only on the cell surface membrane but also in the cytoplasm of HEK293 cells. The EGFP/hERG appeared to influence the hERG channel gating properties, including reduction of the peak tail current density, more rapid inactivation process, faster recovery from inactivation and faster deactivation kinetics compared with untagged hERG channels. Our results suggest that the EGFP/hERG channel alter the electrophysiological properties of hERG channel, but it does not seem to alter the cellular location of hERG channels. Thus, EGFP tagging to N-terminus might be used for research of subcellular location of hERG channels but not for the channel electrophysiological properties.     

Endoplasmic reticulum stress in wake-active neurons progresses with aging

Fragmentation of wakefulness and sleep are expected outcomes of advanced aging. We hypothesize that wake neurons develop endoplasmic reticulum dyshomeostasis with aging, in parallel with impaired wakefulness. In this series of experiments, we sought to more fully characterize age-related changes in wakefulness and then, in relevant wake neuronal populations, explore functionality and endoplasmic reticulum homeostasis. We report that old mice show greater sleep/wake transitions in the active period with markedly shortened wake periods, shortened latencies to sleep, and less wake time in the subjective day in response to a novel social encounter. Consistent with sleep/wake instability and reduced social encounter wakefulness, orexinergic and noradrenergic wake neurons in aged mice show reduced c-fos response to wakefulness and endoplasmic reticulum dyshomeostasis with increased nuclear translocation of CHOP and GADD34. We have identified an age-related unfolded protein response injury to and dysfunction of wake neurons. It is anticipated that these changes contribute to sleep/wake fragmentation and cognitive impairment in aging.     

Expansion of bone marrow IFN-alpha-producing dendritic cells in New Zealand Black (NZB) mice: high level expression of TLR9 and secretion of IFN-alpha in NZB bone marrow

Patients with systemic lupus erythematosus have elevated IFN-alpha production. Furthermore, sera IFN-alpha levels correlate with disease activity. We have focused our attention on whether this phenotype is also seen in the New Zealand Black (NZB) mice and simultaneously addressed the underlying mechanisms. Specifically, we analyzed: 1) levels of sera IFN-alpha after type A CpG ODN 2216 injection in autoimmunity-prone NZB and control mice, and 2) levels of IFN-alpha synthesized by IFN-alpha-producing dendritic cells (IPDCs) using highly enriched populations of CD11c+B220+ IPDCs derived from NZB and control mice; IPDCs are divided into two subpopulations (CD4+CD11c+B220+ and CD4-CD11c+B220+). Our data demonstrate that NZB mice produced higher levels of sera IFN-alpha after type A CpG ODN 2216 injection when compared with control mice (p < 0.01). In addition, the cell numbers, frequency, and TLR9 mRNA levels of CD4+ and CD4- IPDC were markedly increased in the bone marrow (BM) of NZB mice. Upon in vitro stimulation with TLR9 ligand-CpG ODN 2216, higher levels of IFN-alpha were synthesized by IPDCs from the BM of NZB. The major contributor of IFN-alpha was the CD4-CD11c+B220+ IPDC subpopulation. Furthermore, NZB BM IPDCs manifest impaired expression of homing chemokine CCR7 and CD62L, and IL-12 production. These data on the functional characteristics of the IPDC lineages explain in part the mechanism of hyper-IFN-alpha production and help clarify the mechanism for the expansion of NZB BM IPDCs.     

亚硝酸盐氮对凡纳滨对虾毒性和抗病相关因子影响

用常规生物毒性实验方法,在不同盐度下进行亚硝酸盐氮对凡纳滨对虾的急性毒性实验;并加亚硝酸盐氮于凡纳滨对虾的养殖环境中,检测与抗病力相关因子的变化。研究亚硝酸盐氮对凡纳滨对虾的毒性和抗病力相关因子的影响。结果表明:盐度对亚硝酸盐氮的毒性有较大影响。盐度为31时,24hLC50、48hLC50、72hLC50和96hLC50分别为314.9mg/L1、75.3mg/L1、00.2mg/L和89.0mg/L;盐度为17时,分别为132.3mg/L、65.6mg/L、51.3mg/L和39.5mg/L。盐度31实验组的亚硝酸盐氮半致死浓度均显著(P<0.05)高于盐度17实验组。在低盐度条件下亚硝酸盐氮的毒性较强。亚硝酸盐氮对凡纳滨对虾抗病力相关因子有显著的影响。亚硝酸盐氮浓度为4.0mg/L和8.0mg/L时,其血细胞数、超氧化物歧化酶(SOD)活力、酚氧化酶(PO)活力、抗菌活力(Ua)、溶菌活力(UL)和血清蛋白含量均显著(P<0.05)低于对照组;不吸污组抗病力相关因子活性均显著(P<0.05)低于吸污组。低浓度的亚硝酸盐氮可降低凡纳滨对虾抗病能力,亚硝酸盐氮浓度越高,其抗病能力越弱。     

RhoA Is Essential for Maintaining Normal Megakaryocyte Ploidy and Platelet Generation

RhoA plays a multifaceted role in platelet biology. During platelet development, RhoA has been proposed to regulate endomitosis, proplatelet formation, and platelet release, in addition to having a role in platelet activation. These processes were previously studied using pharmacological inhibitors in vitro, which have potential drawbacks, such as non-specific inhibition or incomplete disruption of the intended target proteins. Therefore, we developed a conditional knockout mouse model utilizing the CRE-LOX strategy to ablate RhoA, specifically in megakaryocytes and in platelets to determine its role in platelet development. We demonstrated that deleting RhoA in megakaryocytes in vivo resulted in significant macrothrombocytopenia. RhoA-null megakaryocytes were larger, had higher mean ploidy, and exhibited stiff membranes with micropipette aspiration. However, in contrast to the results observed in experiments relying upon pharmacologic inhibitors, we did not observe any defects in proplatelet formation in megakaryocytes lacking RhoA. Infused RhoA-null megakaryocytes rapidly released platelets, but platelet levels rapidly plummeted within several hours. Our evidence supports the hypothesis that changes in membrane rheology caused infused RhoA-null megakaryocytes to prematurely release aberrant platelets that were unstable. These platelets were cleared quickly from circulation, which led to the macrothrombocytopenia. These observations demonstrate that RhoA is critical for maintaining normal megakaryocyte development and the production of normal platelets.     

海南霸王岭热带雨林的种间分离

 基于地理信息系统软件绘制了海南岛霸王岭热带雨林1个0.5 hm2永久样地所有DBH≥1 cm树木的分布图,进而借助最近邻体分析扩展模块判定每个个体的最近邻体植株,并得到每个基株最近邻体种对的距离。采用N×N最近邻体列联表的截表法,研究了这个多物种群落的种间分离。结果表明,随机毗邻种对占优势,正分离种对次之,负分离种对最少。多数灌木和一些小乔木（平均胸径<15 cm）彼此呈正分离,少数负分离;灌木和乔木间的分离关系复杂;大乔木种类（平均胸径≥65 cm）间不存在负分离。种间分离存在种间差异。种间分离与分布格局明显相关,聚集分布的物种与其它物种正分离比例远比随机分布、均匀分布大;相反,聚集分布物种与其它物种负分离比例要比随机分布、均匀分布小。聚集 聚集分布的种对最可能出现正分离;聚集 均匀分布的种对以及随机 随机分布的种对则最可能出现负分离。但是,无论物种的分布格局或种对相对分布格局如何,随机毗邻的种对都占优势。与种间联结不同,种间分离反映的是小尺度的物种空间关系。在此基础上,初步阐述了种间分离的可能原因及其生态学涵义。     

4 689例血培养病原菌的临床分布与种类分析

目的：了解本院血培养病原菌的检出种类及在临床各科的分布。方法：应用Bact/Alert-120全自动血培养仅对4689例血标本进行培养,标本检出病原菌按常规鉴定并分类统计。结果：检出有临床意义病原菌355株,其中肠杆菌科和葡萄球菌属的细菌为主要病原菌（35.5%和27.3%)。以2000年全年标本统计,阳性率12.5%,假阳性率0.4%。以内科,外科,儿科,传染科,血液科,新生儿科等为病区统计,病原菌种类分布有明显不同,此外,病原菌种类不同,其阳性报告时间不同。结论：应用全自动血培养仪可以缩短阳性检出时间,了解病原菌在临床各科的分布特点,有利于医师对败血症诊治,及时准确地选择药物。