一株高度变异的中国SV40分离株的全基因组序列分析

对SV40中国云南分离株YNQD38进行了全基因组核苷酸序列测定。覆盖了整个基因组的9个重叠的基因片段被扩增和测序，与其它SV40株进行了序列比对并基于全基因序列建立了遗传进化树。结果显示：基因组全长5125bp，基因组构成与其它SV40毒株相似，均有6个开放读码框架和1个调控区。YNQD38与已被证实高度保守的其它SV40比，全基因组核苷酸同源性仅为91．0％。在SV40的保守区VP1、VP2、VP3、小t抗原（t—ag）和部分大T抗原（不包括大T抗原C末端）区，YNQD38与其它SV40之间核苷酸同源性分别为90．7％～91．1％、91．7％～92．0％、90．2％～90.8％、92.8％～93．3％、88．5％～89．7％。在SV40的可变区大T抗原C末端（T—ag—C）编码区，YNQD38同源性更低，仅为65．7％～74．3％。YNQD38发生在保守区的核苷酸变异多为无义突变，而发生在变异区的核苷酸变异多为有义突变。YNQD38的调控区缺少一个完整的72bp增强子，这种特别的调控区的结构以前未见报道。基于整个基因组构建的进化树显示该株病毒形成了一个独特的组。以上结果表明YNQD38是目前报道的SV40中变异最大的一株，而且也是第一株被完整测序的SV40中国株。这个报道不仅为SV40中国株的基础研究提供了一个完整清楚的分子生物学资料，还对这样一株高度变异的SV40能否成为人类致病因子进行了初步探讨。

筛板和筛顶高度解剖变异的CT观察

目的 根据CT表现探讨解剖变异与硬脑膜漏的关系。方法 收集了 160例受检者冠状位CT扫描资料 ,分别测量两侧筛顶高度差异 ,两侧筛板高度差异及左侧和右侧筛板与筛顶间高度差异。结果 ①两侧筛顶高度差异 :14例 ( 8 8% )右侧筛顶低于左侧筛顶 2～ 7mm ,平均 4mm ,2例 ( 1 2 % )左筛顶低于右筛顶 2～ 3mm。②两侧筛板高度差异 :13例 ( 8 1% )右侧筛板低于左侧筛板 2～ 7mm ,平均 3 8mm ,2例 ( 1 2 % )左筛板低于右筛板 2～ 4mm。③左侧筛板与筛顶间高度差异 :左侧筛板低于筛顶 2～ 7mm ,平均 5mm。④右侧筛板与筛顶间高度差异 :右侧筛板低于筛顶同样为2～ 7mm ,平均 5mm。结论 冠状位CT检查不仅可以评估病变的性质和范围 ,而且能够确定术区危险的解剖变异。

竹环中维管束分布密度和纤维鞘组织比量纵向变异研究

以毛竹为研究对象,研究了毛竹竹环中维管束分布密度和纤维鞘组织比量纵向变异。通过微细砂纸抛光结合高清扫描的方式获得竹环横切面,采用Image-Pro Plus等图像处理软件采集竹环横切面尺寸及维管束数量、纤维鞘面积等数据,计算竹环中维管束的分布密度、纤维鞘组织比量。结果表明:以微细砂纸抛光结合高清扫描的方式获得的竹环横切面用于维管束数量、面积计算,准确、可行;同一株毛竹,上部竹节间维管束的分布密度和纤维鞘的组织比量大于下部;在同一节间内,维管束的分布密度、纤维鞘的组织比量也随竹环的位置升高而略有增加。毛竹竹环中维管束分布密度和纤维鞘组织比量随高度的增加而增加。

中医辨治乙肝病毒变异思路浅探

乙肝病毒是高度变异的病毒，无论是乙肝病毒感染的自然病程，还是抗乙肝病毒的治疗过程中，都存在乙肝病毒变异的可能；对乙肝病毒变异机制的研究，目前虽然有许多新的发现，但还不能说已完全搞清楚；因此治疗上也缺乏统一和有效的方法，笔者试从中医辨治方面浅探如下：

维持性血液透析患者加速衰老的研究进展

维持性血液透析（maintenance hemodialysis,MHD）患者的预期寿命普遍低于正常人群,存在加速衰老的现象,同时MHD患者预期寿命的长短又是高度变异的,与年龄、伴随疾病及移植治疗等因素有关.本文就MHD患者快速衰老的机制及影响因素的研究进展进行综述.

痤疮与应激:儿茶酚胺对痤疮丙酸杆菌的影响

痤疮丙酸杆菌(cutibacterium acnes)基因组具有高度变异性,分为4种亚型及6种主要核糖类型,其中2个代表性菌株-RT4痤疮(acneic strain ribotype 4)和RT6非痤疮菌株(non-acneic strain ribotype 6)的基因组已经完成测序。有研究者分析了儿茶酚胺对这2种痤疮丙酸杆菌株的生长、生物膜形成、表面性质等生理指标的影响。

Interdecadal and Interannnual Variabilities of the Antarctic Oscillation Simulated by CAM3

Based on four sets of numerical simulations prescribed with atmospheric radiative forcing and sea surface temperature(SST) forcing in the Community Atmospheric Model version 3(CAM3), the interannual and interdecadal variabilities of the Antarctic oscillation(AAO) during austral summer were studied. It was found that the interannual variability is mainly driven by SST forcing. On the other hand, atmospheric radiative forcing plays a major role in the interdecadal variability. A cooling trend was found in the high latitudes of the Southern Hemisphere(SH) when atmospheric radiative forcing was specified in the model. This cooling trend tended to enhance the temperature gradient between the mid and high latitudes in the SH, inducing a transition of the AAO from a negative to a positive phase on the interdecadal timescale. The cooling trend was also partly weakened by the SST forcing, leading to a better simulation compared with the purely atmospheric radiative forcing run. Therefore, SST forcing cannot be ignored, although it is not as important as atmospheric radiative forcing.

Variability of Tropical Cyclone in High Frequent Occurrence Regions over the Western North Pacific

In this study, three high frequent occurrence regions of tropical cyclones(TCs), i.e., the northern South China Sea(the region S), the south Philippine Sea(the region P) and the region east of Taiwan Island(the region E), are defined with frequency of TC's occurrence at each grid for a 45-year period(1965–2009), where the frequency of occurrence(FO) of TCs is triple the mean value of the whole western North Pacific. Over the region S, there are decreasing trends in the FO of TCs, the number of TCs' tracks going though this region and the number of TCs' genesis in this region. Over the region P, the FO and tracks demonstrate decadal variation with periods of 10–12 year, while over the region E, a significant 4–5 years' oscillation appears in both FO and tracks. It is demonstrated that the differences of TCs' variation in these three different regions are mainly caused by the variation of the Western Pacific Subtropical High(WPSH) at different time scales. The westward shift of WPSH is responsible for the northwesterly anomaly over the region S which inhibits westward TC movement into the region S. On the decadal timescale, the WPSH stretches northwestward because of the anomalous anticyclone over the northwestern part of the region P, and steers more TCs reaching the region P in the greater FO years of the region P. The retreating of the WPSH on the interannual time scale is the main reason for the FO's oscillation over the region E.

科学防治,面对甲流不要慌

甲型流感病毒H1N1,也被称为甲型H1N1流感病毒,它是一种负链单股RNA病毒,能够引起人类和动物的流感。甲型流感病毒具有高度变异性,其中H1N1亚型是导致流感大流行的主要原因之一。甲型流感病毒主要通过飞沫传播,当感染者咳嗽、打喷嚏或说话时,病毒含在飞沫中可以传染给周围的人。

Determining whether Qinghai–Tibet Plateau waterbodies have acted like carbon sinks or sources over the past 20 years

Half of all of China’s lakes are on the Qinghai–Tibet Plateau(QTP),which are mainly distributed at altitudes above 4000 m asl.Being under conditions of progressively intensifying anthropogenic activities and climate change,the debate on whether QTP lakes act as carbon(C)sinks or sources remains unresolved.This study explores QTP lake C exchange processes and characteristics over the past two decades through field monitoring and data integration.Results reveal high lake carbon dioxide(CO_(2))exchange flux distribution patterns in its western and southern regions and correspondingly low values in its eastern and northern regions.Lake CO_(2)exchange flux rates also show significant temporal differences where those in the 2000s and 2010s were significantly higher compared to the 2020s.Annual total CO_(2)emission flux from QTP lakes has increased from 1.60 Tg Ca^(-1)in the 2000s to 6.87 Tg Ca^(-1)in the 2010s before decreasing to 1.16 Tg Ca^(-1)in the 2020s.However,QTP lakes have generally acted as C sinks when annual ice-cover periods are included in the estimation of annual C budgets.Consequently,QTP lakes are gradually evolving towards C sinks.Some small-sized freshwater lakes on the QTP exhibit C sequestration characteristics while low-mid altitude saltwater lakes also act as C sinks.Therefore,owing to the high uncertainties in the estimation of C exchange flux,the QTP lake C sink capacity has been largely underestimated.

HEART RATE VARIABILITY DURING HIGH-INTENSITY EXERCISE

The aim of this paper is to describe and analyse the behaviour of heart rate variability(HRV)during constant-load,high-intensity exercise using a time frequency analysis(Wavelet Transform).Eleven elite cyclists took part in the study(age:18.6±3.0 years;VO_(2max):4.88±0.61 litres·min^(-1)).Initially,all subjects performed an incremental cycloergometer test to determine load power in a constant load-test(379.55±36.02 W;89.0%).HRV declined dramatically from the start of testing(p<0.05).The behaviour of power spectral density within the LF band mirrored that of total energy,recording a significant decrease from the outset LF peaks fell rapidly thereafter,remaining stable until the end of the test.HF-VHF fell sharply in the first 20 to 30 seconds.The relative weighting(%) of HF-VHF was inverted with the onset of fatigue,[1.6%at the start,7.1(p<0.05) at the end of the first phase,and 43.1%(p<0.05) at the end of the test].HF-VHF_(peak) displayed three phases:a moderate initial increase,followed by a slight fall,thereafter increasing to the end of the test.The LF/HF-VHF ratio increased at the start,later falling progressively until the end of the first phase and remaining around minimal values until the end of the test.

Genetic Differentiation of Pinus koraiensis under Different Altitude Conditions in Changbai Mountain

The genetic differentiation of Korean pine (Pinus koraiensis) in different altitudes in Changbai Mountain was analyzed by ISSR technique, and it was found that the level of genetic diversity of Korean pine reduces along with altitude increasing in Changbai Mountain. The variation of Korean pine is mainly from intra-population and there is a positive relativity between genetic distance and vertical geographic distance of Korean pine in different altitudes. The genedc coherence shows that altitude has less insulation to Korean pine. Therefore, it is deduced that the terrain formation of vertical distribution of Korean pine is a result of diffusion from lower altitude to higher altitude in the course of enlarging its adaptability.

Explaining variation in productivity requires intraspecific variability in plant height among communities

While recent studies have shown the importance of intraspecific trait variation in the processes of community assembly,we still know little about the contributions of intraspecific trait variability to ecosystem functions.Here,we conducted a functional group removal experiment in an alpine meadow in Qinghai-Tibetan Plateau over 4 years to investigate the relative importance of inter-and intraspecific variability in plant height for productivity.We split total variability in plant height within each of 75 manipulated communities into interspecific variability(TV_(inter))and intraspecific variability within a community(ITV_(within)).Community-weighted mean height among communities was decomposed into fixed community-weighted mean(CWM_(fixed))and intraspecific variability among communities(ITV_(among)).We constructed a series of generalized additive mixed models and piecewise structural equation modeling to determine how trait variability(i.e.TV_(inter),ITV_(within),CWM_(fixed) and ITV_(among))indirectly mediated the changes in productivity in response to functional group removal.Community productivity was not only affected directly by treatment manipulations,but also increased with both inter-and intraspecific variability(i.e.CWM_(fixed) and ITV_(among))in plant height indirectly.This suggests that both the‘selection effect’and a‘shade-avoidance syndrome’can incur higher CWM_(fixed) and ITV_(among),and may simultaneously operate to regulate productivity.Our findings provide new evidence that,besides interspecific variability,intraspecific trait variability in plant height also plays a role in maintaining net primary productivity.