Detection of simian immunodeficiency virus DNA in macrophages from infected rhesus macaques.

We have examined the frequency of infection of monocyte-derived and alveolar macrophages isolated from rhesus macaques inoculated with simian immunodeficiency virus (SIVmac) utilizing a semiquantitative PCR methodology. Animals were inoculated with either pathogenic (SIVmac239) or nonpathogenic (SIVmac1A11) molecularly cloned viruses of SIVmac, or with uncloned pathogenic SIVmacBIOL. The frequency of SIV DNA in macrophages was highest early after infection and at terminal stages of disease, whereas during the asymptomatic period, SIV DNA was present at very low levels in macrophages.     

吉林省森林生态系统的碳储量、碳密度及其分布

利用森林资源二类调查汇总数据和标准地实测数据,研究吉林省森林生态系统的碳密度、碳储量及其组分和分布特征.结果表明:吉林省森林生态系统碳储量为1827.293TgC,其中乔木层、灌草层、枯落物层和土壤层的碳储量分别为439.152、5.195、45.600和1330.466TgC,分别占总碳量的24.1%、0.3%、2.5%和73.1%.吉林省森林生态系统碳密度为225.304MgC.hm-2,各层碳密度的大小顺序为土壤层(164.666MgC.hm-2)>乔木层(54.352MgC.hm-2)>枯落物层(5.644MgC.hm-2)>灌草层(0.643MgC.hm-2).不同类型森林生态系统碳储量在9.357～959.716TgC,碳密度在180.648～254.627MgC.hm-2之间,各林型分配特征表现为土壤层最大、灌草层最小.全省森林生态系统碳储量和碳密度的空间分布总体上为东部山区高、中西部平原地区低.吉林省森林中中龄林分比重大,若对现有森林加以更好的管理,可以增加其碳吸存潜力.     

华山新麦草叶片的光合生理特性

对华山新麦草(Psathyrostachys huashanica Keng ex P.C.Kuo)营养叶的净光合速率(Pn)和蒸腾速率(Tr)的日变化曲线进行了分析,并在对叶温(Tl)、气孔阻力(Rs)、光合有效辐射强度(PAR)和气温(Ta)的日变化曲线进行测定的基础上分析了它们对华山新麦草Pn的影响规律。结果表明:华山新麦草Pn的日变化曲线呈"三峰"型,峰值分别为6.5、6.2和9.0μmol.m-2.s-1,依次出现在9:30、11:30和16:30,而且具有明显的"午降"现象;Tr的日变化曲线呈"单峰"型,最大值为1.7 mmol.m-2.s-1,出现在13:30;Tl、Rs、PAR和Ta的日变化曲线均呈"单峰"型,峰值分别出现在12:30、11:30、12:30和13:30。华山新麦草的Pn对Tl、PAR和Ta的响应曲线均呈"抛物线"型,Pn在一定范围内与Tl、PAR和Ta呈正相关,随着Tl、PAR和Ta的升高逐渐增加至最大值后逐渐降低;而Pn与Rs则呈负相关,Pn在一定范围内随Rs的增大逐渐降低。根据拟合方程,华山新麦草营养叶的光补偿点和光饱和点分别为1.1和531.5μmol.m-2.s-1,说明该种类具有很强的喜光性,且对光照强度的适应范围较广。研究结果表明:较大的气孔阻力是造成华山新麦草叶片净光合速率偏低的主要原因。     

地衣芽孢杆菌对养殖水体氨氮、残饵降解特性研究

试验对从健康养殖大黄鱼肠道中分离筛选到的一株益生地衣芽孢杆菌X3914的氨氮、残饵降解特性进行了研究。结果表明,X3914菌株降解氨氮的最适温度、盐度和pH分别为30℃、2.0%和7.0,在氨氮初始浓度为100 mg/L时,24h内的氨氮降解率达到36.2%。通过向添加1%饲料的大黄鱼养殖用水中接种1%和5%(体积比)的菌量(菌浓度约为9.0×108 cfu/L)来研究地衣芽孢杆菌浓度对降解饲料中蛋白质、淀粉的影响。结果表明,接种5%菌量的降解率均高于1%菌量的降解率,其中,48h内接种5%菌量的蛋白质和淀粉的降解率分别为35.2%和52.6%。X3914菌株具有较好的氨氮、饲料蛋白质和淀粉的降解能力,在水产养殖上具有潜在的应用价值。     

Characterization of sarcoplasmic reticulum Ca ATPase nucleotide binding domain mutants using NMR spectroscopy

Sarcoplasmic reticulum Ca²⁺ ATPase (SERCA) is essential for muscle function by transporting Ca²⁺ from the cytosol into the sarcoplasmic reticulum through ATP hydrolysis. In this report, the effects of substitution mutations on the isolated SERCA-nucleotide binding domain (SERCA-N) were studied using NMR. ¹⁵N–¹H HSQC spectra of substitution mutants at the nucleotide binding site, T441A, R560V, and C561A, showed chemical shift changes, primarily in residues adjacent to the mutation sites, indicating only local effects. Further, the patterns of chemical shift changes upon AMP–PNP binding to these mutants were similar to that of the wild type SERCA-N (WT). In contrast to these nucleotide binding site mutants, a mutant found in patients with Darier’s disease, E412G, showed small but significant chemical shift changes throughout the protein and rapid precipitation. However, the AMP–PNP dissociation constant (∼2.5 mM) was similar to that of WT (∼3.8 mM). These results indicate that the E412G mutant retains its catalytic activity but most likely reduces its stability. Our findings provide molecular insight into previous clinical, physiological, and biochemical observations.     

Adaptor protein containing PH domain, PTB domain and leucine zipper (APPL1) regulates the protein level of EGFR by modulating its trafficking

The EGFR-mediated signaling pathway regulates multiple biological processes such as cell proliferation, survival and differentiation. Previously APPL1 (adaptor protein containing PH domain, PTB domain and leucine zipper 1) has been reported to function as a downstream effector of EGF-initiated signaling. Here we demonstrate that APPL1 regulates EGFR protein levels in response to EGF stimulation. Overexpression of APPL1 enhances EGFR stabilization while APPL1 depletion by siRNA reduces EGFR protein levels. APPL1 depletion accelerates EGFR internalization and movement of EGF/EGFR from cell surface to the perinuclear region in response to EGF treatment. Conversely, overexpression of APPL1 decelerates EGFR internalization and translocation of EGF/EGFR to the perinuclear region. Furthermore, APPL1 depletion enhances the activity of Rab5 which is involved in internalization and trafficking of EGFR and inhibition of Rab5 in APPL1-depleted cells restored EGFR levels. Consistently, APPL1 depletion reduced activation of Akt, the downstream signaling effector of EGFR and this is restored by inhibition of Rab5. These findings suggest that APPL1 is required for EGFR signaling by regulation of EGFR stabilities through inhibition of Rab5.     

流域视野下梯田聚落的人居环境空间特征——以元江流域为例

针对村落人居环境研究过于注重村落本体的现状,以GIS的技术方法结合实地调研,选取梯田聚落所处的元江流域及典型样本大瓦遮河子流域为研究范围,探讨流域视野下人居环境空间的宏观与微观特征。结论如下：1）哀牢山区的崎岖山脉与密集水系造就了元江流域的格局,以水平、垂直特征奠定子流域尺度中梯田聚落的人居环境基础;2）大瓦遮河子流域的人居环境以“典型山地本底、帚状水系关联”为共性,在中低山区形成“面状森林核心、村落散布周边、旱地梯田混合”的彝族聚落区,在中山区形成“面状梯田核心、村落环绕周边、带状森林围合”的哈尼族聚落区,二者差异源自不同民族适应垂直分异效应的差异化农作策略;3）流域是人居环境研究的基本单元,超越村落本体之外的流域视野对复杂地理环境中的人居环境研究具有重要价值与普遍意义。     

A Ubiquitin-Binding Domain that Binds a Structural Fold Distinct from that of Ubiquitin

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Site fidelity and range size of wintering Barnacle Geese Branta leucopsis

CapsuleBarnacle Geese restrict their movements to relatively few key sites and exhibit considerable variation in ranging behaviour.

Aims To examine individual and seasonal variation in site fidelity, habitat use, range size and foraging strategies of Barnacle Geese Branta leucopsis.

Methods The movements of 18 male Barnacle Geese tagged in two discrete areas were tracked for 3–6 months from late autumn until departure on the spring migration.

Results Tagged geese concentrated their feeding in a relatively small proportion of apparently suitable habitat. Geese moved increasingly further afield in midwinter, and there was a clear predeparture shift to the largest area of relatively undisturbed, and possibly more nitrogen-rich, saltmarsh on the Solway. Birds from one of the two capture sites tended to be more sedentary and have smaller home ranges.

Conclusion There is considerable between-site and inter-individual variation in the degree of site-faithfulness of Barnacle Geese.     

斑驳病毒对‘牛尾’山药叶片光合作用的影响

为了解斑驳病毒对‘牛尾’山药叶片光合作用的影响,对不同病害程度的‘牛尾’山药叶片的叶绿素和光合日变化进行了测定。结果表明,轻病植株的叶片叶绿素a和总叶绿素显著低于健康植株,重病植株的叶绿素b和类胡萝卜素也较健康植株低,但轻病植株与健康植株间无显著差异。斑驳病毒侵染山药后,轻病和重病植株的净光合速率、气孔导度、蒸腾速率均低于健康植株,但胞间CO₂浓度与健康植株间无显著差异。这表明山药感染斑驳病毒后光合效率下降,从而导致生理机能受到影响。