NaCl胁迫对PSII光能利用和耗散的影响

用荧光动力学的方法研究了不同浓度的ＮａＣｌ 处理对ＰＳＩＩ光能利用和耗散的影响。结果表明,在较低的光强下,与对照、１００ｍ ｍｏｌ／Ｌ 和２００ｍ ｍｏｌ／Ｌ ＮａＣｌ 处理相比,经３００ｍ ｍｏｌ／Ｌ 和４００ｍ ｍｏｌ／Ｌ ＮａＣｌ 处理的小麦,其荧光光化学淬灭效率较低,荧光非光化学淬灭效率较高,Ｆｏ 淬灭系数较大,ＱＢ － 非还原性ＰＳＩＩ反应中心含量较大; 而在较高光强下, 其荧光非光化学淬灭效率和Ｆｏ 淬灭系数则相对较低。     

Global stability of Gause-type predator-prey systems

In this paper, we present some global stability results obtained from comparison analysis, Bendixson-Dulac criterion or limit cycle stability analysis for the general Gause-type predator-type systems.Research supported in part by a FGIA grant from the Arizona State University Research Fund AMS (MOS) subject classifications. Primary 34C05; secondary 34C25, 92A15.     

人工饲养条件下恒河猴血液学、血液生化正常参考值测定及分析

目的测定人工饲养条件下104只健康恒河猴的血液学、血液生化正常参考值,并分析不同性别、不同年龄阶段(青幼年组∶3～4岁,成年组∶5～10岁,老年组∶11～25岁)恒河猴的血液学、血液生化值的差异及相互关系.方法应用全自动血液细胞分析仪和全自动血液生化分析仪,测定及分析非麻醉状态下健康恒河猴血液学和血液生化正常值.结果血液学值中较明显低 (P<0.05) 的项目为MED.血液生化值中♀猴比♂猴明显低 (P<0.01)的项目有ALT、ALP、GGT、CHOL、APOA、HDL、LDL、P3+、BUN,较明显低 (P<0.05) 的项目为ALB.较明显高 (P<0.05) 的项目为UA.各年龄组之间的分析如下:血液学值中RDW值为青幼年组比成年组及老年组均明显低(P<0.01),MEDIAN值为成年组比青幼年组较明显高 (P<0.05),血液生化值中青幼年组比成年组及老年组均明显高 (P<0.01)的项目有ALT、ALP、GGT、P3+,青幼年组比成年组明显高(P<0.01)的项目为BUN、ALP、AST、,青幼年组比老年组明显高(P<0.01)的项目为CK、TF;成年组比老年组明显低(P<0.01)的项目为CREAT,较明显低 (P<0.05) 的为TRIG.结论本文建立了人工饲养条件下健康恒河猴血液学和血液生化值的正常指标,并讨论了年龄、性别对其正常指标的影响,可供参考.     

Phospholipase A2-like activity of human bocavirus VP1 unique region

Human bocavirus (HBoV) is a new parvovirus first discovered in 2005, which is associated with acute respiratory infection. Analysis of sequence homology has revealed that a putative phospholipase A₂ (PLA₂) motif exists in the VP1 unique region of HBoV. However, little is known about whether the VP1 unique region of HBoV has PLA₂ enzymatic activity and how these critical residues contribute to its PLA₂ activity. To address these issues, the VP1 unique region protein and four of its mutants, were expressed in Eschericha coli. The purified VP1 unique protein (VP1U) showed a typical Ca²⁺-dependent secreted PLA₂-like (sPLA₂) activity, which was inhibited by sPLA₂-specific inhibitors in a time-dependent manner. Mutation of one of the amino acids (21Pro, 41His, 42Asp or 63Asp) in VP1U almost eliminated the sPLA₂ activity of HBoV VP1U. These data indicate that VP1U of HBoV has sPLA₂-like enzymatic activity, and these residues are crucial for its sPLA₂-like activity. Potentially, VP1U may be a target for the development of anti-viral drugs for HBoV.     

Mechanism of inhibition of retrovirus release from cells by interferon-induced gene ISG15

Budding of retroviruses from cell membranes requires ubiquitination of Gag and recruitment of cellular proteins involved in endosome sorting, including endosome sorting complex required for transport III (ESCRT-III) protein complex and vacuolar protein sorting 4 (VPS4) and its ATPase. In response to infection, a cellular mechanism has evolved that blocks virus replication early and late in the budding process through expression of interferon-stimulated gene 15 (ISG15), a dimer homologue of ubiquitin. Interferon treatment of DF-1 cells blocks avian sarcoma/leukosis virus release, demonstrating that this mechanism is functional under physiological conditions. The late block to release is caused in part by a loss in interaction between VPS4 and its coactivator protein LIP5, which is required to promote the formation of the ESCRT III-VPS4 double-hexamer complex to activate its ATPase. ISG15 is conjugated to two different LIP5-ESCRT-III-binding charged multivesicular body proteins, CHMP2A and CHMP5. Upon ISGylation of each, interaction with LIP5 is no longer detected. Two other ESCRT-III proteins, CHMP4B and CHMP6, are also conjugated to ISG15. ISGylation of CHMP2A, CHMP4B, and CHMP6 weakens their binding directly to VPS4, thereby facilitating the release of this protein from the membrane into the cytosol. The remaining budding complex fails to release particles from the cell membrane. Introducing a mutant of ISG15 into cells that cannot be conjugated to proteins prevents the ISG15-dependent mechanism from blocking virus release. CHMP5 is the primary switch to initiate the antiviral mechanism, because removal of CHMP5 from cells prevents ISGylation of CHMP2A and CHMP6.     

微菌落观察法快速检测和鉴别结核杆菌培养物的研究

将取自肺结核患者的219例痰标本接种匡氏琼脂平板,共分离到112例结核菌生长物。其中培养法104例(92.8％)阳性,微菌落观察法108例(96.4％)阳性,微菌落法阳性率稍高。培养法和微菌落法阳性标本首次检出时间分别为18.6d和11d,微菌落检出时间更短(P<0.01)。常规菌型鉴别方法与微菌落法对结核杆菌菌型鉴别的符合率为99％。     

光敏核不育水稻61kD特异性蛋白质的纯化和N—端序列分析

用制备型聚丙烯酰胺凝胶电泳和制备型等电聚焦纯化了曾报道的光敏核不育水稻 (Oryza sativa)农垦 58S叶绿体的特异性蛋白质 P2 ,得到 SDS- PAGE和等电聚焦 (IEF )纯的 P2。经 SDS- PAGE和 IEF测定 ,该纯蛋白质的分子量是 61 k D,等电点是 5.8。现称 P2为 P61。氨基酸序列分析表明 P61的 N-端氨基酸序列与水稻和大麦叶绿体 ATPaseβ亚基的 N-端氨基酸序列同源。     

CO2倍增对不同基因型大豆光合色素含量和荧光诱导动力学参数的影响

研究了CO_2倍增对大豆(Glycine max L.)Bragg(野生型)及其不同单基因突变品系Nts 382(超结瘤突变体)和Nod 49(不结瘤突变体)某些光合特性的影响。结果表明,CO_2倍增能提高Bragg、Nts 382和Nod 49的叶绿素(Chl)和类胡萝卜素(Car)的含量,但不同品系提高的幅度有所不同。荧光诱导动力学测定结果表明,CO_2倍增均能提高其PSⅡ活性、PSⅡ原初光能转化效率和光合作用潜在量子转化效率。CO_2倍增更有利于提高Nts 382的荧光光化学猝灭系数(qp)和PSⅡ总的光化学量子产量,以及较大幅度地降低荧光非光化学猝灭系数(qN),有助于把所捕获的光能用于进行光合作用。这可能与Nts 382是超结瘤突变体,比Bragg和Nod 49能更充分地利用空气中的氮素有关。     

Profile-based string kernels for remote homology detection and motif extraction

We introduce novel profile-based string kernels for use with support vector machines (SVMs) for the problems of protein classification and remote homology detection. These kernels use probabilistic profiles, such as those produced by the PSI-BLAST algorithm, to define position-dependent mutation neighborhoods along protein sequences for inexact matching of k-length subsequences ("k-mers") in the data. By use of an efficient data structure, the kernels are fast to compute once the profiles have been obtained. For example, the time needed to run PSI-BLAST in order to build the profiles is significantly longer than both the kernel computation time and the SVM training time. We present remote homology detection experiments based on the SCOP database where we show that profile-based string kernels used with SVM classifiers strongly outperform all recently presented supervised SVM methods. We further examine how to incorporate predicted secondary structure information into the profile kernel to obtain a small but significant performance improvement. We also show how we can use the learned SVM classifier to extract "discriminative sequence motifs"--short regions of the original profile that contribute almost all the weight of the SVM classification score--and show that these discriminative motifs correspond to meaningful structural features in the protein data. The use of PSI-BLAST profiles can be seen as a semi-supervised learning technique, since PSI-BLAST leverages unlabeled data from a large sequence database to build more informative profiles. Recently presented "cluster kernels" give general semi-supervised methods for improving SVM protein classification performance. We show that our profile kernel results also outperform cluster kernels while providing much better scalability to large datasets.