Impact of an exotic parasitoid on Plutella xylostella (Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya

Diadegma semiclausum (Hellén) (Hymenoptera: lchneumonidae), an exotic diamondback moth parasitoid, was released in two pilot areas (Werugha in Coast Region and Tharuni in Central Province) in Kenya. Fifteen month before release, observations on the diamondback moth, Plutella xylostella (Linnaeus), and local natural enemy population dynamics and pest damage were initiated in both areas and continued for three years after release. The P. xylostella population was bimodal with higher records during dry seasons. At Werugha, the peak population of P. xylostella was 16.8 per plant (October 2001); at Tharuni it was 12.8 (February 2002). Populations at Werugha declined from three months after release and decreased from 5.4 per plant (before release) to 0.8 (year 3 after release). Concurrently, average damage (1.9 to 1.5) (on a 0-5 scale), proportion of attacked plants (72 to 31%) and proportion of plants in damage group >2 (plants with head damage) decreased (21.4 to 5.3%), while total parasitism increased from 14.4 (before) to 52.5% (year 3 after release, 90% due to D. semiclausum). At Tharuni, D. semiclausum was only recovered 3 months after release. Average populations of P. xylostella declined from 5.9 per plant (before release) to 2.4 (year 3 after release) and damage scores from 2.3 to 1.7. The proportion of plants in damage group >2 declined from 39.7 to 4.5% while overall parasitism increased from 4.2 to 40.6% (98.3% by D. semiclausum). Four species of indigenous parasitoids (Diadegma mollipla (Holmgren), Oomyzus sokolowskii (Kurdjumov), Apanteles sp. and Itoplectis sp., all primary parasitoids) were almost completely displaced by D. semiclausum. Possible reasons for the different parasitoid development between the two release areas and the displacement of the indigenous species are discussed.     

重金属Hg2+离子作用于PSII 23 kD外周蛋白的光谱学研究

23 kD蛋白是光系统II(PSII)的外周蛋白,具有增加Ca2 和C l-的结合以维持放氧活性的作用。本文借助内源荧光光谱和紫外吸收差谱考察了23 kD蛋白与Hg2 的相互作用。所得结果表明:低浓度的Hg2 离子(<10μM)引起23 kD蛋白的荧光淬灭,淬灭程度与Hg2 离子浓度相关;进一步分析显示,Hg2 离子对23 kD蛋白色氨酸荧光的淬灭属于静态淬灭。紫外吸收差谱可以检测到明显的配体向金属进行电荷转移的谱带(LMCT band)。随着Hg2 浓度的增加,LMCT带的强度逐渐增强。分析显示23 kD蛋白只存在一类Hg2 离子结合位点。     

Design of Deinococcus radiodurans thioredoxin reductase with altered thioredoxin specificity using computational alanine mutagenesis

In this study, the X-ray crystal structure of the complex between Escherichia coli thioredoxin reductase (EC TrxR) and its substrate thioredoxin (Trx) was used as a guide to design a Deinococcus radiodurans TrxR (DR TrxR) mutant with altered Trx specificity. Previous studies have shown that TrxRs have higher affinity for cognate Trxs (same species) than that for Trxs from different species. Computational alanine scanning mutagenesis and visual inspection of the EC TrxR-Trx interface suggested that only four residues (F81, R130, F141, and F142) account for the majority of the EC TrxR-Trx interface stability. Individual replacement of equivalent residues in DR TrxR (M84, K137, F148, and F149) with alanine resulted in drastic changes in binding affinity, confirming that the four residues account for most of TrxR-Trx interface stability. When M84 and K137 were changed to match equivalent EC TrxR residues (K137R and M84F), the DR TrxR substrate specificity was altered from its own Trx to that of EC Trx. The results suggest that a small subset of the TrxR-Trx interface residues is responsible for the majority of Trx binding affinity and species-specific recognition.     

Heterologous expression of the benzoate para-hydroxylase encoding gene (CYP53B1) from Rhodotorula minuta by Yarrowia lipolytica

There is currently an increasing number of cytochrome P450 (CYP450) monooxygenase encoding genes becoming available from various genome-sequencing projects. These enzymes require association with cytochrome P450 reductase (CPR) to achieve optimal activities. In this study, the CYP53B1 gene, which encodes a benzoate para-hydroxylase, was successfully cloned from Rhodotorula minuta and overexpressed in Yarrowia lipolytica E150. Multiple copies of the CYP53B1 cDNA were cloned under the POX2 promoter, while the Y. lipolytica CPR was cloned under the isocitrate lyase promoter. Whole cell biotransformation of benzoic acid to para-hydroxybenzoic acid (pHBA) was used to analyse the hydroxylase activity of the recombinant Y. lipolytica UOFS Y-2366. Different induction conditions were tested in shake flask cultures. The highest concentration of pHBA produced by UOFS Y-2366 was 1.6 g l⁻¹ after 200 h when stearic acid was repeatedly added to the media. R. minuta accumulated up to 1.8 g l⁻¹ of pHBA within only 24 h. Thus, the specific hydroxylase activity of Y. lipolytica UOFS Y-2366 [approximately 0.07 U (g dry wt.)⁻¹] was about 30 times lower than the specific hydroxylase activity of R. minuta [2.62 U (g dry wt.)⁻¹]. However, the hydroxylation activity obtained with Y. lipolytica was one of the highest hydroxylation activities thus reported for whole cell biotransformation studies carried out with yeasts expressing foreign CYP450s.     

冠心病合并代谢综合征患者的冠状动脉病变特点及与 代谢综合征组分的相关性研究

目的:探讨冠心病合并代谢综合征(metabolic syndrome,MS)患者的冠脉病变特点及冠心病与MS各组分的相关性。方法:选取540例冠心病患者为研究对象,其中合并MS患者164例,非合并MS患者376例,并将所有患者根据MS的组分个数进行分组,比较冠心病合并MS的病变特点、MS组分个数对冠状动脉病变程度的影响及冠状动脉病变程度与代谢综合症各组分的相关性;结果:①冠心病合并MS组BMI、FBG、TG、LDL-C、TC、UA、FIB、高血压分级等指标较非MS组高,差异有统计学意义(P<0.01),HDL-C、LVEF较非MS组低,差异有显著性(P<0.01);②MS组冠脉Gensini积分较高,三支病变、主干病变发生率高,差异有显著性(P<0.01);③随着合并MS组分个数的增加,冠脉Gensini积分也逐渐增加,各组间比较有显著性差异(P<0.01);④冠脉Gensini积分与MS组分BMI、高血压分级、TG、TC、LDL-C、UA等指标存在正相关(P<0.05),与性别、HDL-C存在负相关(p<0.01);调整传统危险因素后,Gensini积分与MS的组分数显著相关(r=0.739、P<0.01)。结论:冠心病患者有较高的MS患病率,冠心病合并MS患者冠脉病变程度更重,且以多支病变、主干病变为主;随着合并MS组分个数的增加,冠脉病变程度也呈加重趋势;MS的各个组分均与冠状动脉病变程度显著相关,可以作为冠心病严重程度的预测指标。     

血浆蛋白质组学的研究进展

血浆蛋白质组学是研究血浆蛋白质的功能和变化的一门科学。血浆中蕴藏着生命机体的所有信息,因此只有彻底了解血浆中存在哪些蛋白质,才能知道如何利用血浆来预测人体对疾病的易感性并监控疾病的进程,以期达到对疾病进行早诊断早治疗。由于血浆蛋白质组动态范围大,给研究带来了很大的困难。尤其是高丰度蛋白质的存在影响了低丰度蛋白质的检测率。而低丰度蛋白质都是有意义的具有临床诊断价值的蛋白质。因此去除高丰度蛋白质的干扰成了血浆蛋白质组学研究的关键。近年来,血浆蛋白质组学相关研究技术也得到了长足进展,为深入研究血浆蛋白质做出了重要贡献。血浆蛋白质组学作为一种无创性的研究方法,值得我们去探讨。本文就血浆蛋白质组学研究进展情况做一简要综述。     

江苏近海北部海域春季鱼类群落结构的年间变化

根据2009—2014年在江苏近海北部海域(34.00°—35.13°N,119.40°—121.50°E)的底拖网调查数据,结合综合性指标和多元统计分析等方法研究了该海域的鱼类群落结构随时间的变化.结果表明: 江苏近海海域共有鱼类68种,相对资源量波动较大,站位平均渔获质量的变化范围为0.75～1.62 kg·h^-1,站位平均渔获尾数显著下降,变化范围为203～370 ind·h^-1. 2009—2014年江苏近海的鱼类群落平均营养级指数在3.58～3.72,2009—2010年相对较低,2011—2014年在3.70以上波动.2009—2014年鱼类群落的平均个体大小在2.93～11.18 g之间波动上升,变化趋势与平均营养级基本一致.聚类分析和非度量多维标度排序分析表明,研究期间大致分为2009—2010和2011—2014年两个年份组.组间分歧种主要有尖海龙、小头栉孔虾虎鱼和玉筋鱼等.对前后两个年份组的分析表明,中上层、浮游生物食性鱼类优势度增加,冷温种和本地种优势度下降.表明江苏近海海域鱼类群落结构发生了较为明显的演替.针对演替规律提出了渔业管理的建议,为渔业资源的合理利用提供理论参考.     

Surgical Efficiencies and Quality in the Performance of Voluntary Medical Male Circumcision (VMMC) Procedures in Kenya,South Africa,Tanzania, and Zimbabwe

Introduction

This analysis explores the association between elements of surgical efficiency in voluntary medical male circumcision (VMMC), quality of surgical technique, and the amount of time required to conduct VMMC procedures in actual field settings. Efficiency outcomes are defined in terms of the primary provider’s time with the client (PPTC) and total elapsed operating time (TEOT).

Methods

Two serial cross-sectional surveys of VMMC sites were conducted in Kenya, Republic of South Africa, Tanzania and Zimbabwe in 2011 and 2012. Trained clinicians observed quality of surgical technique and timed 9 steps in the VMMC procedure. Four elements of efficiency (task-shifting, task-sharing [of suturing], rotation among multiple surgical beds, and use of electrocautery) and quality of surgical technique were assessed as explanatory variables. Mann Whitney and Kruskal Wallis tests were used in the bivariate analysis and linear regression models for the multivariate analyses to test the relationship between these five explanatory variables and two outcomes: PPTC and TEOT. The VMMC procedure TEOT and PPTC averaged 23–25 minutes and 6–15 minutes, respectively, across the four countries and two years. The data showed time savings from task-sharing in suturing and use of electrocautery in South Africa and Zimbabwe (where task-shifting is not authorized). After adjusting for confounders, results demonstrated that having a secondary provider complete suturing and use of electrocautery reduced PPTC. Factors related to TEOT varied by country and year, but task-sharing of suturing and/or electrocautery were significant in two countries. Quality of surgical technique was not significantly related to PPTC or TEOT, except for South Africa in 2012 where higher quality was associated with lower TEOT.

Conclusions

SYMMACS data confirm the efficiency benefits of task-sharing of suturing and use of electrocautery for decreasing TEOT. Reduced TEOT and PPTC in high volume setting did not result in decreased quality of surgical care.     

杉木人工林凋落物生态化学计量与土壤有效养分对长期模拟氮沉降的响应

凋落物分解的快慢和养分释放的速度决定了生态系统中土壤有效养分的供应。探讨全球变化条件下森林生态系统凋落物与土壤养分的变化规律,有利于深入认识凋落物-土壤相互作用的养分调控因素,从而揭示生态系统C、N、P循环。通过模拟氮沉降增加试验,分4个水平处理,分别为0、60、120、240 kg N hm~(-2)a~(-1)。模拟氮沉降13年后,分析了杉木人工林凋落物中不同组分(落叶、落枝、落果)生态化学计量与土壤有效养分(有效氮、碱解氮、速效磷、速效钾)的关系。结果表明:氮沉降(N1、N2和N3)显著提高了落叶和落枝的N含量,平均增幅分别为35.27%和32.21%;高水平氮沉降(N3)处理显著降低了落叶和落枝的C/N,平均降幅分别为25.95%和22.32%,但N3增加了落枝和落果N/P,平均增幅分别为38.4%和31.7%;氮沉降对凋落物各组分的C、P和C/P均影响不显著。氮沉降处理显著增加了土壤NO_3~--N和NH_4~+-N含量,均表现为N3N2N1N0,其中NO_3~--N含量更容易受氮沉降处理的影响,表现为更大的增幅。N2显著增加0—20 cm土层的碱解氮含量,N1显著降低0—20 cm土层的速效钾,但氮沉降对速效磷含量没有影响。凋落物生态化学计量与土壤有效养分之间的Pearson相关和冗余分析(RDA)表明,凋落物生态化学计量与土壤有效养分之间关系紧密,凋落物P含量(蒙特卡罗检验,P=0.018)和C/P比值(P=0.037)对土壤有效养分影响显著。凋落物中C/N比值、C/P比值与土壤有效养分呈显著负相关,其比值越高越不利于土壤有效养分的累积。