Short-term responses of winter soil respiration to snow removal in a Picea asperata forest of western Sichuan

Aims Seasonal snow cover is one of the most important factors that control winter soil respiration in the cold biomes. The warming-induced decreases in snowpack could affect winter soil respiration of subalpine forests. The aim of this study was to explore the effects of snow removal on winter soil respiration in a Picea asperata forest.Methods A snow removal experiment was conducted in a P. asperata forest stand in western Sichuan during the winter of 2015/2016. The snow removal treatment was implemented using wooden roof method. Soil temperatures, snow depth and soil respiration rate were simultaneously measured in plots of snow removal and controls during the experimental period.Important findings Compared to the control, snow removal increased the fluctuations of soil temperatures. The average daily temperature of the soil surface and that at 5 cm depth were 1.12 °C and 0.34 °C lower, respectively, and the numbers of freeze-thaw cycles of the soil surface and that at 5 cm depth were increased by 39 and 12, respectively, in plots of snow removal than in the controls. The average rate of winter soil respiration and CO₂ efflux were 0.52 μmol·m^-2·s^-1 and 88.44 g·m^-2, respectively. On average, snow removal reduced soil respiration rate by 21.02% and CO₂ efflux by 25.99%, respectively. More importantly, the snow effect mainly occurred in the early winter. The winter soil respiration rate had a significant exponential relationship with soil temperature. However, snow removal significantly reduced temperature sensitivity of the winter soil respiration. Our results suggest that seasonal snow reduction associated with climate change could inhibit winter soil respiration in the subalpine forests of western Sichuan, with significant implications for the carbon dynamics of the subalpine forests.     

田间转Bt基因水稻上稻飞虱卵量、孵化率及天敌作用

为了评估转基因水稻释放后对非靶标害虫及其天敌的影响, 本研究在浙江大学实验农场和中国水稻研究所实验农场2008和2009年连续两年监测了转Bt基因水稻对田间稻飞虱着卵量、卵孵化率、卵被捕食率、卵被寄生率和卵死亡率的影响。结果表明: 两年2个调查地点3个水稻品系（克螟稻1、克螟稻2和秀水11）上的稻飞虱平均每分蘖着卵量、卵孵化率、卵被捕食率和卵被寄生率的趋势基本一致, 而且田间3个水稻品系上稻飞虱卵量的高峰期均持续2周左右; 但是两年2个调查地点3个水稻品系上稻飞虱卵死亡率则没有一致的趋势。此外, 总体上3个水稻品系上稻飞虱平均每分蘖着卵量、卵孵化率、卵被捕食率、卵被寄生率和卵死亡率差异均不显著（P>0.05）。因此, 稻田中转Bt基因水稻对稻飞虱卵没有显著的影响。     

圈养白头叶猴春季昼夜活动节律

2008 年3 ～5 月,采用瞬时扫描法,对上海动物园5 只白头叶猴的行为进行24 h 昼夜连续观察。结果表明:春季圈养白头叶猴一天的活动起于06∶ 00 左右,结束于18∶ 00 或18∶ 30。白天白头叶猴的主要行为为休息、取食和移动,平均频次依次是13.79 次、4.75 次和2.18 次。夜间的主要行为为休息、移动和抓挠,平均频次依次是22.13 次、0.43 次和0.26 次。不同个体昼夜活动节律差异很大。其中,移动、理毛、玩耍和其它行为的差异显著。夜间无理毛和玩耍行为,移动行为在夜间21∶ 00, 00 ∶ 30, 03∶00 和04∶ 30 出现高峰。在22∶ 30, 01∶ 00, 02∶ 00, 03∶ 30, 04∶ 30 和05∶30 则出现抓挠高峰。这预示白头叶猴夜间休息时处于一个“轻睡眠”状态。同时,雌雄白头叶猴昼夜移动行为差异显著。     

生物工程学报2014年度优秀论文奖北大核心CSCD

为了鼓励优秀作者,本刊每年年末对3年前发表在《生物工程学报》的论文进行回溯与评估。今年,编辑部从我刊2011年度发表的205篇论文中,根据论文的创新性（审稿专家的评审意见）和读者的关注度（中国知网CNKI的被引频次和下载量）综合评选出了20篇优秀论文,授予“2014年度生物工程学报优秀论文奖”,获奖作者将获得编辑部颁发的证书。今后,凡以下获奖名单中的作者再向本刊投稿时附此证书,录用后可享有优先发表和稿酬加倍的优惠。     

肠炎沙门氏菌鸡源株ompR 基因缺失株的构建及生物学特性与亲本株的比较

【目的】为了探讨ompR基因在肠炎沙门氏菌生物被膜形成及毒力中的作用。【方法】以肠炎沙门氏菌作为母本,运用自杀性载体pGMB151构建了ompR基因缺失株,结晶紫染色法和扫描电镜观察测定缺失株的生物被膜形成能力,细胞的吸附和侵入及小鼠攻毒试验测定缺失株的毒力。【结果】RT-PCR和蛋白表达证明了ompR基因缺失株构建成功;该缺失株不表达纤维素和菌毛,不形成生物被膜;上皮细胞吸附和侵入试验表明缺失株与野生株具有相同的吸附和侵入率;BALB/c鼠腹腔感染性试验表明,缺失株的半数致死量为106.67CFU,而野生株的半数致死量小于2 CFU。【结论】ompR基因既是肠炎沙门氏菌生物膜形成的调控基因,又是重要的毒力基因。     

金黄色葡萄球菌hmp基因缺失突变株的构建及抗一氧化氮能力分析

摘要：【目的】:构建金黄色葡萄球菌RN6390黄素血红蛋白(flavohaemoglobin, HMP)基因缺失突变株,研究其抗一氧化氮(Nitric Oxide, NO) 能力及其在细菌生物被膜形成中的作用。【方法】：根据同源重组技术的原理,利用PCR扩增RN6390的hmp基因上下游同源臂,经过抗生素和温度交替培养筛选hmp基因缺失突变株,利用基因组PCR、定量PCR对突变菌株进行鉴定。以硝普钠（SNP）为NO供体,检测了hmp基因缺失菌株的抗NO能力,并初步研究了hmp基因在生物被膜形成中的作用。【结果】：成功构建了RN6390的hmp基因缺失突变株,外源NO能够诱导菌株hmp基因的表达,hmp基因缺失菌株抗NO能力明显下降,但其生物被膜形成能力有明显提高。【结论】：获得了RN6390的hmp基因缺失突变株,该突变株的获得为进一步研究hmp基因的生物功能,以及细菌内源性NO的作用奠定了良好的技术平台。     

长期不同施磷条件下玉米产量、养分吸收及土壤养分平衡状况

以设置在沈阳潮棕壤上的连续12年的田间定位磷微区试验为依托,研究在不同磷肥施用条件下(施用量和施磷频次),玉米产量、养分吸收以及土壤养分平衡状况。结果表明:磷素不是该研究区域玉米生产的主要限制因子;施肥促进养分吸收,其各处理间增加趋势为氮磷氮对照,并且一次性施磷肥方式优于每年施磷肥方式;与土壤本底值相比,施肥后土壤耕层(0~20 cm)全磷、速效磷、全氮、碱解氮呈增加趋势,由于长年没有外源钾的补充,土壤全钾和速效钾呈下降趋势,其各处理间下降趋势为氮磷氮对照;土壤速效磷在不施用肥料条件下有下降趋势,只施用氮肥条件下有增加趋势,只是两者变化并不很明显;在每年施磷条件下,土壤速效磷量呈缓慢上升趋势,而在一次性施磷条件下,施肥当年的土壤速效磷量激增,而后呈减小的趋势,即与每年施磷肥方式相比,一次性施磷方式更有利于建立土壤"宏大"有效磷库;为了保证土壤养分平衡,在施用足量氮肥的前提下,施用磷肥量为等于或略高于作物移出磷量,施氮磷比控制在1∶0.167到1∶0.5之间。     

一个带有离散和分布时滞的Holling-Ⅳ型捕食被捕食模型的稳定性和分支

本文研究了一个带有离散和分布时滞的Holling-IV型功能反应的捕食与被捕食模型,将离散时滞r看作分支参数,讨论了正平衡点的局部稳定性和Hopf分支,利用Routh-Hurwitz定理得到了平衡点局部渐近稳定的充分条件.通过分析相应的特征方程,发现随着r穿越某临界值,Hopf分支会发生,并且可能出现小范围周期解.     

The Chloroplast Outer Envelope Membrane： The Edge of Liaht and Excitement

The chloroplast is surrounded by a double-membrane envelope at which proteins, ions, and numerous metabolites including nucleotides, amino acids, fatty acids, and carbohydrates are exchanged between the two aqueous phases, the cytoplasm and the chloroplast stroma. The chloroplast envelope is also the location where the biosynthesis and accumulation of various lipids take place. By contrast to the inner membrane, which contains a number of specific transporters and acts as the permeability barrier, the chloroplast outer membrane has often been considered a passive compartment derived from the phagosomal membrane. However, the presence of galactoglycerolipids and β-barrel membrane proteins support the common origin of the outer membranes of the chloroplast envelope and extant cyanobacteria. Furthermore, recent progress in the field underlines that the chloroplast outer envelope plays important roles not only for translocation of various molecules, but also for regulation of metabolic activities and signaling processes. The chloroplast outer envelope membrane offers various interesting and challenging questions that are relevant to the understanding of organelle biogenesis, plant growth and development, and also membrane biology in general.     

环境污染中三维时变Volterra捕食-被捕食系统的持续生存

对环境容量很大且被污染的三种群时变系统进行了研究,给出了三维时变Ｖｏｌｔｅｒｒａ捕食－被捕食系统弱平均持续生存与绝灭的充分条件。