类鼻疽伯克霍尔德菌感染与免疫逃逸机制的研究进展

类鼻疽是由类鼻疽伯克霍尔德菌(Burkholderia pseudomallei,B.pseudomallei)(简称类鼻疽菌)感染引起的一种热带医学疾病.该病临床表现复杂多样,严重感染时可快速发展为败血症,病死率高达40％.越来越多的证据表明,它是一种正在扩散的人兽共患传染病.本文就近年来关于类鼻疽菌感染的重要毒力因...     

丰富环境对社会行为的影响及其生物学研究进展

哺乳动物大脑伴随个体从出生到成熟,衰老、死亡处于动态发展中,受到先天遗传因素和后天环境因素影响。其中遗传因素相对易于作为共性或特征进行研究,但是后天环境复杂多变。环境因素影响大脑对认知、情感、社会交往等行为的调控,其影响程度和机制尚未完全清楚,本文就丰富环境对大鼠社会行为影响研究进展做概要介绍。     

逃逸速率对分子马达定向运动的影响

在考虑逃逸速率的情况下采用主方程方法研究分子马达,计算了逃逸速率对分子马达的漂移速率、扩散系数、停留时间以及分子马达在轨道上移动的距离．通过计算发现,逃逸速率影响分子马达的定向运动．     

北京城区麻雀的逃逸距离及其影响因素

行为的改变促进野生动物与人类共存,其中逃逸距离的改变是鸟类适应城市生境的重要机制。本研究量化城市常见鸟类麻雀Passer montanus的逃逸距离,并分析其影响因素。2019年夏季对北京城区14个公园和15个高校的1 326只麻雀的观测发现,麻雀的警戒距离为5.67 m±1.13 m、惊飞距离为4.92 m±1.12 m、飞逃距离为6.51 m±1.75 m。麻雀的逃逸距离受到麻雀群体大小、捕食风险和生境特征的共同影响:警戒距离、惊飞距离和飞逃距离均随着危险稀释而减小;警戒距离随着生境中庇护场所的减少而增加;惊飞距离随着人类干扰的增多而减小;当生境中捕食者较多时,麻雀选择较近的飞逃距离。本研究有助于增进对逃逸距离在种内变异的了解,并可为探讨野生动物在城市生境的适应机制提供基础资料。     

风和光对东北鼢鼠堵洞行为的影响

东北鼢鼠的堵洞行为,是其适应地下生活一种行为反应。通常认为是其避光怕风的生态习性促使其产生堵洞行为,但相关的实验证据较为缺乏。为验证这一观点的正确性以及为进一步探究其堵洞行为产生的机理提供科学依据,本研究于2014年8月在内蒙古呼伦贝尔草甸草原进行了野外试验。试验采用2×2列联表设计,将风、光因子组合为4个处理,分别为,风光都进入洞道、风进入洞道光不进入洞道、风不进入洞道光进入洞道、风光都不进入洞道。并通过自行设计的专利“风光隔离器”使每个处理达到了试验的要求。试验随机选取68只东北鼢鼠作为试验样本,并将样本平均分配到4个处理中进行试验,对堵洞与否进行记录。通过Shannon信息量互信息法、卡方独立性检验分别对风、光因子的独立性、风光单因子与堵洞行为的关系进行了分析。结果表明：就堵洞而言,风光因子是独立的,不存在交互作用（I=7.22×10-5）;风、光单因子与东北鼢鼠的堵洞次数差异不显著（P﹥0.05）。野外试验表明,东北鼢鼠的堵洞行为与风和光无关。     

SOX2影响PD-L1表达参与乳腺癌细胞免疫逃逸的机制探讨

摘要 目的：探讨转录因子性别决定区Y框蛋白2（SOX2）基因通过诱导程序性死亡因子配体1（PD-L1）表达,促进乳腺癌细胞免疫逃逸的作用机制。方法：qRT-PCR和Western blot法检测人乳腺癌细胞系MDA-MB-231、SK-BR-3和正常乳腺上皮细胞系MCF10A中SOX2、PD-L1、T细胞免疫球蛋白及粘蛋白结构域分子3（TIM3）和核受体亚家族4 A组成员1（NR4A1）的mRNA表达量及对应蛋白表达量。分别构建SOX2敲减质粒NC和si-SOX2并转染MDA-MB-231,与细胞因子诱导的杀伤细胞构建共培养体系,连续培养48h,MTT法检测细胞增殖率,TUNEL法检测细胞凋亡率,乳酸脱氢酶（LDH）释放实验检测 T细胞杀伤率,ELISA检测T细胞活化标志物IL-2和IFN-γ,qRT-PCR 检测 T 细胞耗竭标志物 PD-1、TIM3和NR4A1 mRNA表达量。结果：与MCF10A相比,MDA-MB-231与SK-BR-3中SOX2、PD-L1、TIM3、NR4A1的mRNA表达量及对应蛋白表达量均显著升高（P＜0.05）。与空白组和NC组相比,si-SOX2组SOX2 mRNA和PD-L1蛋白表达量明显下降,细胞增殖率显著下降,细胞凋亡率增加,T细胞杀伤率增加,IL-2和IFN-γ水平升高,PD-1、TIM3和NR4A1 mRNA表达量降低（P＜0.05）。结论：SOX2基因可能通过诱导PD-L1高表达,进而促使乳腺癌细胞免疫逃逸的能力增强,沉默SOX2表达可以增强T细胞杀伤力,抑制肿瘤增殖,SOX2基因有望成为乳腺癌干预的重要分子靶点。     

环境因子对细菌形成芽孢的影响

环境因子对细菌形成芽孢的影响范玉贞（河北省衡水师范专科学校生物学系００３３００）由于芽抱对不良环境和物理、化学杀菌因于有极强的抵抗力,故一般认为芽抱是细菌在不良条件下形成的适应逆境的产物。但实际情况并非完全如此。细菌形成芽抱的根本原因在于细胞内部含有...     

环境因子对冬小麦水分利用效率的影响

对干湿两种水分处理下农田冬小麦群体水分利用效率与环境因子的关系进行分析。结果表明：（１）各环境因子以综合复杂的方式影响水分利用效率。（２）由土壤干旱和大气高蒸发势迭加而成的水分亏缺所引起的气阻阻力上升有利于提高水分利用效率,但水分亏缺同时引起的叶－气水汽压梯度增大则会降低水分利用效率。在水分亏缺最强的午后１２：００￣１６：００时,水分利用效率最低。     

环境温度对(虫)蜓能量需求和食物同化影响的研究

研究了环境温度对成体Yan蜓能量需求和食物同化的影响。在24℃—33℃范围内,雌、雄Yan蜓摄入能、表观消化系数和同化效率的两性差异不显著。温度显著影响Yan蜓的能量摄入和同化效率,27℃时的能量摄入显著高于30℃和33℃,27℃时的同化效率显著高于24℃和33℃。各实验温级表观消化系数的差异不显著。结果表明：环境温度对Yan蜓能量需求和食物同化的影响显著。     

蜓和蓝尾石龙子幼体食物同化的热依赖性

用采自安徽滁州琅琊山的(虫匽)蜓(Sphenomorphus indicus,头体长42.8～54.4mm,n=12)和蓝尾石龙子(Eumeces elegans,头体长43.9～57.3mm,n=10)幼体,研究温度(24～32℃)对(虫匽)蜓和蓝尾石龙子幼体食物通过时间、摄食量、表观消化系数(ADC)、同化效率(AE)和生长的影响.结果显示,24～30℃范围内,(虫匽)蜓和蓝尾石龙子幼体的食物通过时间随温度的升高而缩短,超过30℃则基本不变.(虫匽)蜓幼体30和32℃摄食量和生长小于24～28℃;24～30℃ADC、AE随温度升高而下降,但32℃时又升高.蓝尾石龙子幼体24～26℃摄食量随温度升高而增加,26℃后随温度升高显著下降;24～28℃ADC、AE大于30和32℃,呈现出随温度升高而下降的趋势;26℃生长最快.结果表明,(虫匽)蜓和蓝尾石龙子幼体的摄食和同化能力均低于相应的成体.     

蝘蜓和蓝尾石龙子幼体食物同化的热依赖性

用采自安徽滁州琅琊山的蝘蜓(Sphenomorphus indicus,头体长42．8～54．4mm,n=12)和蓝尾石龙子(Eumeces elegans,头体长43,9～57．3mm,n=10)幼体,研究温度(24～32℃)对蝘蜓和蓝尾石龙子幼体食物通过时间、摄食量、表观消化系数(ADC)、同化效率(AE)和生长的影响。结果显示,24～30℃范围内,蝘蜓和蓝尾石龙子幼体的食物通过时间随温度的升高而缩短,超过30℃则基本不变。蝘蜓幼体：30和32℃摄食量和生长小于24～28℃;24～30℃．ADC、AE随温度升高而下降,但32℃时又升高。蓝尾石龙子幼体：24～26℃摄食量随温度升高而增加,26℃后随温度升高显著下降;24～28℃ADC、AE大于30和32℃,呈现出随温度升高而下降的趋势;26℃生长最快。结果表明,蝘蜓和蓝尾石龙子幼体的摄食和同化能力均低于相应的成体。     

Magnitude of food reward affects escape behavior and acceptable risk in Balearic lizards, Podarcis lilfordi

During encounters with predators, prey must balance the degreeof risk against the loss of fitness-enhancing benefits suchas feeding and social activities. Most studies of tradeoffsbetween risk and cost of escaping have measured flight initiationdistance and time to emerge from refuge, for which theory providesrobustly supported predictions. Tradeoffs involving other aspectsof encounters, including distance fled and time between escapeand return to a food source, have received little theoreticalor empirical attention. By adapting models of flight initiationdistance and time between entry into refuge and emergence, wepredict effects of predation risk and cost on distance fledand time to return to a source of benefit after fleeing. Actingas simulated predators that approached at a fixed speed, weconducted an experimental field study to test the hypothesesthat flight initiation distance, distance fled, and time toreturn to food by Balearic lizards (Podarcis lilfordi) decreasewith the presence and amount of insect food. Predictions ofthe models were strongly supported, including those for distancefled and return time, but predictions for other cost factorsand predation risk factors remain to be tested.     

Effects of risk assessment, predator behavior, and habitat on escape behavior in Columbian black-tailed deer

The relationship between preflight risk assessment by prey andthe escape behaviors they perform while fleeing from predatorsis relatively unexplored. To examine this relationship, a humanobserver approached groups of Columbian black-tailed deer (Odocoileushemionus columbianus), varying his behavior to simulate moreor less threatening behavior. We measured the focal deer's angleof escape, distance moved during flight, duration of trottingand stotting behavior, and change in elevation during flight.Analyses revealed positive relationships between the distancemoved during flight and the distance at which they fled. Whenflight was initiated when the approacher was close, deer fledrelatively shorter distances and took flight paths at more acuteangles, a property that would force a real predator to changedirection suddenly. Our results indicate that deer do not compensatefor allowing the observer to approach more closely by fleeinggreater distances. Rather, distance moved and flight initiationdistance are linked by level of reactivity and habituation:more reactive or less habituated deer both flee at a greaterdistance and move away to a greater distance during flight.More threatening behavior by the approacher led to longer durationsof rapid flight behavior (e.g., trotting and stotting), anddeer tended to flee uphill and into taller vegetation, usingthese landscape features as refuge from danger. Finally, weprovide the first evidence for Pitcher's untested "antiambush"hypothesis for the function of stotting and discuss its significance.In general, both preflight predator behavior and habitat featuresinfluence both duration and direction of escape.     

Regeneration of cercal filiform hair sensory neurons in the first-instar cockroach restores escape behavior

Neural regeneration in the escape circuit of the first-instar cockroach is described using behavioral analysis, electrophysiology, intracellular staining, and electron microscopy. Each of the two filiform hairs on each of the animal's cerci is innervated by a single sensory neuron, which specifically synapses with a set of giant interneurons (GIs) in the terminal ganglion. These trigger a directed escape run. Severing the sensory axons causes them to degenerate and perturbs escape behavior, which is restored to near normal after 4–6 days. Within this time, afferents regenerate and reestablish arborizations in the terminal ganglion. In most cases, regenerating afferents enter the cercal glomerulus and re-form most of the specific monosynaptic connections they acquired during embryogenesis, although their morphology deviates markedly from normal; these animals reestablish near normal escape behavior. In a few cases, regenerating afferents remain within the cercus or bypass the cercal glomerulus, and thereby fail to re-form synapses with GIs; these animals continue to exhibit perturbed escape behavior. We conclude that in most cases, specific synapses are reestablished and appropriate escape behavior is restored. This regeneration system therefore provides a tractable model for the establishment of synaptic specificity in a simple neuronal circuit. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 439–458, 1997     

Factors affecting feeding selectivity of visual predators on the copepod Acartia tonsa: locomotion,visibility and escape responses

Visual predation by fish on copepods involves prey encounter, attack and capture; during any of these processes prey selection can occur. Developmental changes in copepods, including increases in swimming speed, size and image contrast increase the encounter rate and distance at which they can be detected by predators. Copepods compensate for this increase vulnerability with age through diel vertical migration and improved escape capabilities. This study quantifies the changes in swimming speed and movement pattern with developmental stage of the copepod Acartia tonsa, using a video-computer system for motion analysis. Changes in visible size and image contrast with developmental stage were quantified under simulated natural illumination conditions using a video based image analysis system. The escape responses of the naupliar stages of the copepod Acartia tonsa were quantified in response to a stationary pipette sucking in water at a constant speed. Accurate quantification of the parameters that affect feeding selectivity of planktivorous fish will provide the basis for evaluation of their relative importance in future studies.     

The Red Tooth Hypothesis: A computational model of predator-prey relations, protean escape behavior and sexual reproduction

This paper presents an extension of the Red Queen Hypothesis (hereafter, RQH) that we call the Red Tooth Hypothesis (RTH). This hypothesis suggests that predator-prey relations may play a role in the maintenance of sexual reproduction in many higher animals. RTH is based on an interaction between learning on the part of predators and evolution on the part of prey. We present a simple predator-prey computer simulation that illustrates the effects of this interaction. This simulation suggests that the optimal escape strategy from the prey's standpoint would be to have a small number of highly reflexive, largely innate (and, therefore, very fast) escape patterns, but that would also be unlearnable by the predator. One way to achieve this would be for each individual in the prey population to have a small set of hard-wired escape patterns, but which were different for each individual.We argue that polymorphic escape patterns at the population level could be produced via sexual reproduction at little or no evolutionary cost and would be as, or potentially more, efficient than individual-level protean (i.e., random) escape behavior. We further argue that, especially under high predation pressure, sexual recombination would be a more rapid, and therefore more effective, means of producing highly variable escape behaviors at the population level than asexual reproduction.