An evaluation of some natural enemies of >Nezara viridula in northern California

Natural enemies associated with eggs of >Nezara viridula (L.) (Heteroptera: Pentatomidae) wereevaluated by placing sentinel egg masses inweeds and cultivated tomato and bean crops innorthern California. Egg predation wasgenerally less than 10% and normally involvedpredators with chewing mouth parts. Predatorsseldom destroyed an entire egg mass, typicallyeating <40 eggs per exploited mass.Laboratory evaluation of >25 species ofpotential arthropod predators revealed that fewfed on >N. viridula eggs to any extent;however, numerous species fed on >N.viridula nymphs. Five species of eggparasites were recovered from sentinel eggmasses: >Trissolcus basalis (Wollaston),>Gryon obesum Masner and >Telenomuspodisi Ashmead (Scelionidae); and>Ooencyrtus californicus Girault and >O.johnsoni (Howard) (Encyrtidae). The major eggparasite was >T. basalis, the only exoticmember of the parasite guild; it typicallyparasitized 100% of the eggs in an exploitedegg mass. The results indicate thatparasitization of eggs and predation of smallnymphs can be important biotic mortalityfactors for >N. viridula populations innorthern California. It is suggested that acombination of factors – viz., eggparasitization, nymphal predation, regionalshortage of overwintering sites, and localshortages of suitable hosts – maintains thisexotic pest at relatively low levels in theregion.     

How to build a grid cell

Neurons in the medial entorhinal cortex fire action potentials at regular spatial intervals, creating a striking grid-like pattern of spike rates spanning the whole environment of a navigating animal. This remarkable spatial code may represent a neural map for path integration. Recent advances using patch-clamp recordings from entorhinal cortex neurons in vitro and in vivo have revealed how the microcircuitry in the medial entorhinal cortex may contribute to grid cell firing patterns, and how grid cells may transform synaptic inputs into spike output during firing field crossings. These new findings provide key insights into the ingredients necessary to build a grid cell.     

KCNJ11基因E23K基因多态对纽胞膜电流的影响

目的：KCNJ11基因E23K多态与心血管疾病、糖尿病等相关联,本实验通过研究人KCNJll基因外显子处E23K多态对细胞膜电流密度的影响,探讨其与相关疾病关联的机制。方法：普通PCR法扩增KCNJll基因外显子,重叠延伸PCR法使多态位点G—A突变,基因重组法将KCNJll基因外显子（分别含23E和23K等位基因）插入pcDNA3．1／Cr-GFP真核表达载体,脂质体转染法分别将重组质粒pcDNA3．1-KCNJll（E）和pcDNA3．1-KCNJll（K）转入HEK293T细胞。采用全细胞膜片钳技术,检测转染不同质粒的细胞膜电流密度。结果：PCR扩增获得长度为1173bp的KCNJll基因外显子,成功构建pcDNA3．1-KCNJ11（E）和pcDNA3．1-KCNJll（K）重组表达载体。全细胞膜片钳检测结果显示,两组转染不同质粒的HEK293T细胞表面均检测到正电流和负电流,细胞表面翻转电压均为50rTlV。两组细胞相比,转染pcDNA3．1-KCNJ11（E）质粒的细胞表面电流明显高于转染pcDNA3．1-KcNJ11（K）质粒的细胞（P〈0．05,n=10）。结论：KCNJll基因外显子E23K多态能导致细胞膜电流发生改变,为进一步研究多态位点与相关疾病的关联机制提供实验基础。     

基于斑块评价的三峡库区腹地坡耕地优化调控方法与案例研究

三峡库区腹地坡耕地大量存在,且25°的陡坡耕地实现全部退耕还林难度很大,同时还存在农户自发弃耕撂荒现象。有必要深入探讨库区腹地不同地域特征下坡耕地优化调控的理论与方法。在充分考虑坡耕地的分布现状和未来发展趋势的前提下,设定了坡耕地优化调控的6个原则,提出空间优化适宜性评价和农户对坡耕地资源的需求压力数量评价相结合的坡耕地综合优化调控方法。选取库区腹地典型流域草堂溪流域进行案例研究。根据草堂溪流域特点以及坡耕地分布特征,从坡耕地可达性、生态功能和坡改梯适宜性3方面选取相关指标作为格局适宜性调控体系,选取耕地压力指数和果园对农户需求的补充能力作为数量调控体系。综合优化将研究区坡耕地分为优化利用型、重点整治型、逐步退耕型和优先退耕型4种类型,结合研究区坡耕地特点在保持耕地压力不增加、减少陡坡不适宜耕地和土壤侵蚀的前提下设置了4种退耕情景。最后根据农户自发撂荒地的空间分布特征,验证了评价指标体系建立的合理性和正确性。     

A memory‐based foraging tactic reveals an adaptive mechanism for restricted space use

The restricted area of space used by most mobile animals is thought to result from fitness‐rewarding decisions derived from gaining information about the environment. Yet, assessments of how animals deal with uncertainty using memory have been largely theoretical, and an empirically derived mechanism explaining restricted space use in animals is still lacking. Using a patch‐to‐patch movement analysis, we investigated predictions of how free‐ranging bison (Bison bison) living in a meadow‐forest matrix use memory to reduce uncertainty in energy intake rate. Results indicate that bison remembered pertinent information about location and quality of meadows, and they used this information to selectively move to meadows of higher profitability. Moreover, bison chose profitable meadows they had previously visited, and this choice was stronger after visiting a relatively poor quality meadow. Our work demonstrates a link between memory, energy gains and restricted space use while establishing a fitness‐based integration of movement, cognitive and spatial ecology.     

成年大鼠海马CA1区锥体细胞K_(ATP)通道的特性

为了解成年大鼠海马CA1区锥体细胞KATP 通道的特性 ,实验采用膜片钳技术的内面向外式记录法 ,在急性分离的CA1区锥体神经元上 ,研究了可被胞浆侧ATP所抑制的钾离子单通道的特性。当细胞膜内外两侧的K 浓度均为 14 0mmol/L时 ,通道的电导为 63pS ,翻转电位为 1 71mV ,通道呈弱内向整流性。在负钳制电位时 ,通道开放时常被短时程的关闭所打断 ,而在正钳制电位时 ,这种短时程的关闭状态明显少于负钳制电位时。但通道开放概率未见明显的电压依赖性。ATP对通道活动的抑制作用呈浓度依赖性 ,抑制通道活动 5 0 %的ATP浓度为 0 1mmol/L。KATP 通道的特异性阻断剂tolbutamide (甲糖宁 ,1mmol/L)可完全阻断通道的活动 ,而KATP 通道开放剂diazoxide (二氮嗪 ,1mmol/L)则不增强通道的活动。     

异质养分环境中一年生分蘖草本黍根系的生长特征

为揭示黍（Panicum miliaceum L.)根系对异质养分环境的生长反应,作研究了黍根系从起始斑块向目标斑块水平生长时,时始斑块和目标斑块养分水平根生长的影响,就低养分起始珏块而言,粗根生物量,粗根长度,粗根表面积和细极长度在高养分目标斑块中的分配比例均小于其在低养分目标斑块中的分配比例,而细根长度及其密度,细根表面积指及其密度的变化恰好相反,就高养分起始斑块而言,高养分目标斑块的细根长度,细根长度密度,细根表面积指数和细根表面积密均不于低养分目标斑块,而粗根对目标斑块中养分状的反应不明显。当黍根系从桢的起始斑块进入不同的目标斑块后,目标斑块的养分状况对细根生物量及其分配无影响,而显影响细根长度和表现积,这指示细根是通过长度和表面积可塑性而不是生物量变化响应目标斑块中的养分差异。     

太行山中低山区河谷内农田斑块特征及其分布格局—以河北省阜平县胭脂河主流河谷为例

以景观生态学原理为指导,调查了位于太行山中低山区的河北省阜平县胭脂河主流河谷,对河谷内农田斑块的特征及其分布格局进行了分析,结果表明,农田斑块了作河流源头外贯穿整个河谷,从上游向下游,人为活动的增加使农田的比重不断增加,导致自然景观减少,环境异质性降低,农田斑块破碎化和蔼减小,胭脂河河谷总面积为2297.09hm^2,构成河谷景观主体的农田有117个斑块,面积为1027.78hm^2,占河谷面积的44．74％,农田基本紧靠河岸分布,处在水分条件优越但易受洪水威胁的土地带上,农田在河流两侧是非对称分布,其中左岸农田面积587.58hm^2,占57．17％,斑块的宽度呈增加的态势,但变化比较大,基本上以狭长的特征出现。     

The effect of intra- and interspecific aggression on patch residence time in Negev Desert gerbils: a competing risk analysis

We observed patch-use behavior by two gerbil species in a fieldsetting and investigated how aggression and intrinsic decision-makinginteract to influence patch residence times. Results were interpretedby using a competing risk analysis model, which uniquely enabledus to estimate the intrinsic patch-leaving decisions independentlyof external interruptions of foraging bouts by aggression. Theexperiment was conducted in two 1-ha field enclosures completelysurrounded by rodent-proof fences and included allopatric (onlyGerbillus andersoni allenbyi) and sympatric (G. a. allenbyiand G. pyramidum) treatments. We predicted that increased foodpatch quality (i.e., habitat quality) should decrease intrinsicpatch-leaving rates and increase rates of aggressive interactionsinvolving the forager feeding in the patch (i.e., the occupantindividual). We also anticipated that increasing populationdensity should result in an increase in the rate of aggressiveinteractions involving the occupant individual. Our resultssupported the first two predictions, indicating a trade-offbetween foraging and aggression. However, the third predictionwas realized only for G. a. allenbyi in allopatry. Furthermore,in allopatry, occupant G. a. allenbyi individuals with highcompetitive ranks were involved in aggressive interactions atlower rates than those with low competitive ranks. However,in sympatry, patch-use behavior of occupant G. a. allenbyi individualswas mainly influenced by aggressive behavior of G. pyramidum,which did not respond to their competitive rank. Thus, it shouldpay less for G. a. allenbyi to be aggressive in sympatric populations.The observed reduction in intraspecific aggression among individualG. a. allenbyi in the presence of G. pyramidum supports thisassertion. We suggest that this reduction likely weakens thenegative effect of intra- and interspecific density on the percapita growth rate of G. a. allenbyi. Because this would changethe slope of the isocline of G. a. allenbyi, it could be animportant mechanism promoting coexistence when habitat selectionis constrained.