不同体重悦目金蛛的蛛网结构

蛛网是蜘蛛的捕食工具,其结构反映了蜘蛛的捕食投入和捕食策略。对不同大小悦目金蛛(Argiope amoena)的蛛网捕丝长度、捕丝间距、捕食面面积、支持带总面积、半径丝根数和网捕丝分布不对称性等进行观测。结果表明①在体重小于200mg的个体中,捕丝长度、捕丝间距和捕食面面积与个体大小呈显著正相关,而大于200mg的个体中,这种关系并不显著;②蜘蛛在发育到一定程度的时候(在本研究中为22.7mg)才可能出现支持带,并且支持带总面积与体重之间呈显著正相关;③半径丝根数会随体重的增加而减少;④在小于200mg的蜘蛛中,网上、下部捕丝长度比与体重呈显著负相关,而在大于200mg的个体中,二者之间的关系并不显著。这与我们预测的结果是基本一致的,即蛛网的这种结构变化是蜘蛛不同发育阶段捕食投入和捕食策略的反应。     

圆网蛛类系统发生与网型进化

本文从妖面蛛总科和园蛛总科系统发生关系、园蛛总科网型不同的蜘蛛间的系统发生关系及蛛网构建行为等几个方面着重介绍了圆网蛛类系统发生及网型进化的研究进展.圆网蛛类系统发生与其网型进化有效地结合、进行综合研究将有助于圆网蛛类的起源及网型多样性的研究.     

三突花蛛捕食速度的初步研究

本文研究了三突花蛛Misumenops tricuspidatus在不同条件下对果蝇的捕食速度.结果表明,蜘蛛的捕食速度与蜘蛛的步足长度、身体长度无关,而与性别、温度、饥饿程度有显著关系.25 ℃为三突花蛛捕食的最适温度,14 ℃和34 ℃即温度过低或过高时,它的捕食速度显著减慢;三突花蛛在饥饿3～4 d时的捕食速度最快;雄蛛的捕食速度显著大于雌蛛.蜘蛛的共存,如雌蛛-雌蛛、雄蛛-雄蛛、雌蛛-雄蛛共存,对捕食的速度也存在着一定的影响:2雄蛛共存时,各自的捕食速度显著减慢;2雌蛛共存时,各自的捕食速度变化不显著;1雌蛛1雄蛛共存时,雌蛛的捕食速度降低不显著,而雄蛛的捕食速度显著降低.     

园蛛总科网型不同的蜘蛛间分子系统发生关系的初步探讨

为初步探讨园蛛总科内网型不同的蜘蛛间分子系统发生关系,测定了9种蜘蛛核18S rRNA基因的部分序列。联合GenBank中的2种蜘蛛18S rRNA基因序列数据,用NJ法、MP法和ML法重建分子系统树,结果表明：（1）织圆网的园蛛科和肖蛸科蜘蛛在园蛛总科中不是姊妹群;（2）不织圆网的球蛛科和皿蛛科也不是单系发生,证实了皿蛛片网和球蛛网独立起源的观点;（3）皿蛛科蜘蛛的分子系统发生地位与肖蛸科较近、而与园蛛科较远,这表明皿蛛科和园蛛科问雄性触肢结构的相似性很可能是类似而不是同源相似。     

rRNA及MaSp1基因证据不支持圆网蛛类(蜘蛛目:妖面蛛总科+园蛛总科)的单系起源

圆网蛛类(妖面蛛总科 园蛛总科)是否为单系,圆网究竟经历一次进化还是多次进化,这是多年来有争论的、悬而未决的蛛形学难题之一。本文测定了包括妖面蛛总科、园蛛总科和非圆网蛛类等类群在内的9科10种蜘蛛线粒体12S rDNA、16S rDNA及核18S rDNA、28S rDNA等4个基因片段序列,并基于4个基因序列的整合数据,分别通过邻接(NJ)法、最大简约(MP)法、最大似然(ML)法和贝叶斯法(Bayesian)分析,对园蛛总科和妖面蛛总科蜘蛛之间的分子系统关系进行了探讨。系统发生结果表明:1)园蛛总科和妖面蛛总科蜘蛛不是姊妹群,从而支持这两个类群的圆网是平行演化而非同源演化的观点;2)筛器类蜘蛛并非单系发生而为多系发生。另外,依据编码大壶状腺丝蛋白-1(MaSp1)C末端非重复氨基酸序列区段的核酸序列重建的系统发生树也证实圆网蛛类并非单系发生。     

3种中型蜘蛛卵袋形态特征与纤维组成结构

采用扫描电镜和氨基酸自动分析仪对球蛛科(Theridiidae)温室拟肥腹蛛(Parasteatodatepidariorum)、肖蛸蛛科(Tetragnathidae)肩斑银鳞蛛(Leucauge blanda)及狼蛛科(Lycosidae)猴马蛛(Hippasa holmerae)3种中型蜘蛛卵袋的超微结构和氨基酸组成进行了观察。形态观察表明,这3种蜘蛛的卵袋形态各异,温室拟肥腹蛛卵袋一头尖,呈梨状;肩斑银鳞蛛卵袋呈扁平状;猴马蛛卵袋呈椭球形。扫描电镜观察表明,温室拟肥腹蛛卵袋外覆盖层仅仅由一种均一直径的柱状腺丝组成,而另外2种蜘蛛卵袋外覆盖层主要由柱状腺丝与少量其他丝腺纺出的丝纤维组成。氨基酸组成分析表明,温室拟肥腹蛛卵袋外覆盖层的丝纤维的氨基酸组成与具有保守性的其他种类蜘蛛柱状腺丝心蛋白的氨基酸组成差异较大,这表明其可能含有新的丝心蛋白家族成员。本文根据氨基酸组成与扫描电镜的结果分析探讨了不同直径丝纤维的丝腺来源。     

蚊幼对狼蛛的营养作用研究

研究蚊子幼虫（子孓）以拟水狼蛛（Ｐｉｒａｔａｓｕｂｐｉｒａｔｉｃｕｓ）的营养,繁殖作用,结果表明狼蛛对蚊幼的捕食符合ＨｏｌｌｉｎｇⅡ型功能反应,喂以蚊幼和不喂蚊幼处理狼蛛的体重增长率和生殖有极显著差异,在相同蚊幼密度下,狼蛛初始体重越小,增长率越大,经计算狼蛛每增重１ｍｇ,需消耗１０．５８ｍｇ蚊幼,这基本符合生态系统营养级能量流动的１／１０法则,狼蛛体重大小对褐飞虱的捕食量有明显差异,体重大的个体     

大腹园蛛主壶腹腺蛛丝蛋白末端结构域的克隆表达

牵引丝(dragline silk)由主壶腹腺蛛丝蛋白(major ampullate spidroin, MaSp)组成,是蜘蛛丝中强度最好的丝,同时具有极佳的生物相容性和可降解性,因此引起研究者的研究热潮。目前关于大腹园蛛MaSp结构和成丝机理方面的研究甚少,限制了其仿生应用。本文以大腹园蛛牵引丝的组成蛋白质之一MaSp1为研究对象,通过锚定PCR的方法首次获取了大腹园蛛MaSp1 NT的完整编码基因,并对其进行了克隆、表达、纯化,产量可达60 mg/L;同时对该MaSp1的CT进行表达纯化,产量可达80 mg/L。另外,通过CD色谱分析了MaSp1 NT和CT的二级结构,结果表明二者的二级结构均以α-螺旋为主。上述结果为大腹园蛛MaSp1的结构和成丝机理研究奠定了基础。     

八斑鞘蛛对多种猎物的选择捕食作用研究

研究八斑鞘蛛在多种猎物共存时的日捕食量,功能反应,捕食作用率。在有棉铃虫和棉蚜共存且密度互补时,八斑鞘蛛对棉铃虫的功能反应属Holling Ⅲ型反应;一种猎物密度变化,其他种猎物密度固定时,功能反应呈Holling Ⅱ型反应。研究了捕食作用率与猎物共存种类,相对丰盛度,捕食者本身数量的关系。 计算机(IBM-PC)模拟结果表明:捕食者个体间的相互干扰、温度、猎物内禀增长率对系统稳定性有一定影响。     

横纹金蛛捕食经验对其丝纤维力学行为与性能的影响

蛛网是蜘蛛的捕食工具,蛛网网丝的结构与性能不仅影响蜘蛛的捕食效率,也关系着蜘蛛的捕食投入。本文利用单纤维电子强力仪研究横纹金蛛(Argiope bruennichi)室内捕食面包虫(Tenebrio molitor)时上前与返回捕食拖丝的力学性能以及捕食经验对圆网半径丝修补前后的力学性能的影响。结果表明,与上前捕食拖丝相比,返回捕食拖丝减小了弹性区的投入,增加了屈服区和加强区的投入,且返回时捕食拖丝更具柔韧性。整体而言,与初始半径丝相比,在未喂食面包虫的条件下,网的半径修补丝增加了力学性能的投入;而在喂食面包虫的条件下,网的半径修补丝减少了力学性能的投入。所测试丝样中出现了两种类型的蛛丝力学行为:一种为典型的蛛丝力学行为;另外一种为似黏流性材料的力学行为,其反映的是满足蛛丝耗散猎物或自身下降时动能的另外一种力学性能的策略。本研究表明蜘蛛能根据其捕食经验遵循Cost-Benefit原则对蜘蛛丝的力学性能进行调节,从而调整捕食投入。     

Capture thread extensibility of orb-weaving spiders: testing punctuated and associative explanations of character evolution

Spider orb-webs contain sticky prey capture threads and non-sticky support threads. Primitive orb-weavers of the Deinopoidea produce dry cribellar threads made of thousands of silk fibrils that surround supporting axial fibres, whereas the viscous threads of modern Araneoidea orb-weavers produce adhesive threads with an aqueous solution that coalesces as droplets around the axial fibres. We have previously shown that the greater diversity of the Araneoidea is phylogenetically significant and attributed this disparity to a number of advantages, considered key innovations, that adhesive thread has over cribellar thread. An important putative advantage of adhesive thread demonstrated by Kohler and Vollrath in their 1995 study is its greater extensibility, a feature that better adapts it to absorb the kinetic energy of a prey strike. However, this conclusion is based on a two-species comparison that does not take advantage of the modern comparative method that requires hypotheses to be tested in a phylogenetic context. Using a transformational analysis to examine threads produced by nine species, our study finds no support for the punctuated explanation that adhesive thread has a greater extensibility than cribellar thread. Instead, it strongly supports the associative null hypothesis that capture thread extensibility is tuned to spider mass and to architectural features of the web, including its capture area, capture spiral spacing, and capture area per radius.     

The material cost and stickiness of capture threads and the evolution of orb-weaving spiders

Prey capture threads are essential to the operation of spider orb-webs because they prevent insects that have been intercepted from escaping before a spider can subdue them. The volume of material invested in a web's capture threads is related to spider weight and is the same for primitive orb-weavers that produce cribellar capture thread and modern orb-weavers that produce adhesive capture thread. However, as adhesive capture thread achieves greater stickiness relative to its volume, adhesive orb-webs have a greater total stickiness and, consequently, a greater prey capture potential than cribellate orb-webs. These differences appear to have favoured the transition from cribellate to adhesive capture threads and the success of adhesive orb-weavers, which include 95% of all orb-weaving species. Differences in the thread economy and the total stickiness of webs constructed by spiders of different weights also suggest that adhesive orb-weavers should grow more rapidly and be capable of attaining a larger size than cribellate orb-weavers.     

Factors governing the stickiness of cribellar prey capture threads in the spider family Uloboridae

The surface of a cribellar prey capture thread is formed of thousands of fine, looped fibrils, each issuing from one of the spigots on an oval spinning plate termed the cribellum. This plesiomorphic capture thread is retained by members of the family Uloboridae, in which its stickiness differs among genera. An examination of five cribellar thread features in nine uloborid species shows that only the number of fibrils that form a thread explains these differences in thread stickiness. Neither the physical features of these fibrils, nor the manner in which they are combined to form threads differs among species. Threads produced by orb-weaving species contain fewer fibrils than those produced by species that build reduced webs. Relative to spider weight, the number of fibrils that form a cribellar thread is greatest in simple-web species of the genus Miagrammopes, less in triangle-web species of the genus Hyptiotes, and least in orb-weaving species representing five genera. A transformational analysis shows that change in the number of cribellum spigots is directly related to change in the stickiness of cribellar thread. This direct relationship between the material invested in a cribellar thread and its stickiness may have been a limiting factor that favored the switch from the dry cribellar threads of uloborids to the adhesive capture threads produced by other orb-weaving families. © 1994 Wiley-Liss, Inc.     

Design features of the orb web of the spider, Araneus diadematus

Analysis of orb webs of the garden cross spider (Araneus diadematus)showed that these vertical webs have a significant up/down asymmetry.Experiments demonstrated that the spider runs down faster thanup, and thus confers a relatively higher foraging value to sectionsbelow the hub. Simulations suggested that the density of capturespiral spacing, prey size, and the density of prey should allaffect the capture efficiency of a web. Webs lose effectivecapture area because of overlap of the capture zone around eachthread; the smaller the prey, the finer the mesh can be withoutlosing effective area. Lower sectors of the web have a particularmesh size (height and length of capture spiral segments) throughout,whereas in the upper sectors the mesh size changes, wideningfrom the hub towards the periphery.     

On the diet of the rock sole <Emphasis Type="Italic">Lepidopsetta polyxystra</Emphasis> off the eastern coast of the northern Kuril Islands and the southern extremity of Kamchatka

The bulk of diet of the rock sole Lepidopsetta polyxystra in waters of the eastern coast of the northern Kuril Islands and the southern extremity of Kamchatka from September to October 1997 was formed by polychaetes and amphipods (36.8 and 35.1% of the food bolus weight, respectively), which is typical of the feeding of this species, on the whole. The dominant consumption by L. polyxystra of polychaetes is recorded from February to June and of amphipods, from August to December. Polychaetes dominated in the diet of individuals with a length of 16–45 cm and amphipods, in the diet of individuals 46–55 cm long. The feeding migration of L. polyxystra in the study area took place at sites with an increased biomass of the accessible food benthos.     

Economics of spider orb-webs: the benefits of producing adhesive capture thread and of recycling silk

1. The replacement of dry, fuzzy cribellar prey capture thread by viscous, adhesive capture thread was a major event in the evolution of orb-weaving spiders. Over 95% of all orb-weaving species now produce adhesive threads.
2. Adhesive thread achieves its stickiness with a much greater material economy than does cribellar thread.
3. Transformational analyses show that, relative to spider mass, adhesive orb-weavers invest less material per mm of capture thread and produce stickier capture threads than do cribellate orb-weavers.
4. The total cost of producing an orb-web that contains cribellar thread is reduced by 32% when a spider recycles its silk and another 34% when these capture threads are replaced by adhesive threads of equal stickiness.
5. The increased economy with which adhesive capture thread achieves its stickiness may have been an important factor that favoured the origin and success of modern orb-weaving spiders that produce adhesive capture threads.     

Clonal Plasticity in Response to Reciprocal Patchiness of Light and Nutrients in the Stoloniferous Herb Glechoma longituba L.

Interconnected ramets of clonal plants can functionally specialize in the uptake of resources from aboveground and/or underground sources. Ramet pairs of the clonal stoloniferous herb Glechoma Iongltuba L. were grown In spatially heterogeneous environments with complementary availability of light and nutrients. Plasticity with respect to root-shoot ratio, fitness-related traits （biomass, number of ramets and dry weight per ramet）, morphological traits （lamina area, root length） were experimentally examined. The aim was to understand the adaptation of G. Iongltuba to an environment with reciprocal patchiness of light and soil nutrients by plasticity In Its root-shoot ratio and clonal morphology. The results showed that the performance of ramets growing In patches with high light Intensity and low soil nutrients into the adjacent opposite patches was Increased in terms of fitness-related traits. However, the performance of those from patches with low light Intensity and high soil nutrients into the adjacent opposite patches was not changed. The root-shoot ratio and clonal morphology were plastic. Morphological traits such as lamina area and root length were altered In a way that enhanced the capture of light resources and soil nutrients. Apparent reciprocal resource transport between the ramets In an environment of reciprocal patchiness of resources can enhance the growth of ramets with complementary resource deficiencies.     

Why plants bother: root proliferation results in increased nitrogen capture from an organic patch when two grasses compete

We investigated whether the capacities of Lolium perenne L. and Poa pratensis L. roots to proliferate locally and to alter local nitrogen (N) inflows in a decomposing organic matter patch were important in their capture of N when grown together. In the presence of a patch, plants of both species were significantly heavier and contained more N. Root length and weight densities increased in the patch, but specific root length was unaltered. Although both species proliferated roots in the patch, L. perenne produced greater root length densities than P. pratensis , and also captured more N from the patch. Indeed, total N uptake from the patch was related to root length density within the patch. N inflows (rate of N uptake per unit root length) in the patch were no faster than in the whole root system for both species. Under the conditions of this study, root proliferation in an organic patch was more important for N capture from the patch than alterations in N inflows. Local proliferation of roots may be a key factor in interspecific competition for non-uniformly distributed supplies of N in natural habitats, so resolving the previous uncertainty as to the 'adaptive' nature of root proliferation.     

池养条件下似刺鳊鮈早期发育阶段的摄食与生长特性

对人工培育的似刺鳊鮈（Paracanthobrama guichenoti）仔鱼、稚鱼和幼鱼的生长与摄食节律进行了研究。结果显示,在1～70日龄间,似刺鳊鮈全长平均日增长率为3．55％,体重平均日增长率为11．26％,头长／全长值随着日龄的增长而变小。全长（L,mm）与体重（M,mg）的关系式为M=O．0012L^2-0．0564L＋0．6504;体重（M,mg）与日龄（D,d）的关系式为M=O．0043e^0.0936D;全长（L,mm）和日龄（D,d）的关系式为L=0．0154D^2-0．0128D＋8．1965。在饵料充足的条件下,20日龄晚期仔鱼全天均有很高的摄食发生率,小高峰出现在8：00时;40日龄稚鱼则表现出明显的昼夜摄食节律,属于典型的白天摄食类型,日摄食率2．3376％。20日龄仔鱼和4013龄稚鱼饱食后分别经6h、5h整个消化道排空。在水温25℃及饥饿空胃状态下,10日龄仔鱼只经3d即开始出现死亡个体,经5d全部死亡;20日龄仔鱼经6d开始出现死亡个体,经9d全部死亡;40日龄稚鱼经7d才开始出现死亡个体,10d后全部个体均死亡。     

Changes in antioxidant potential and sink-organ dry matter with pigment accumulation induced by hexaconazole in Plectranthus forskholii Briq

An investigation was conducted in Plectranthus forskholii by giving it different concentrations (10, 15, 20, 25, and 30 mg L(-1)) of hexaconazole, a fungicide cum plant-growth regulator, in order to find out its effects on growth, pigment composition, and antioxidant potential. The treatments were given as soil drenching on different growth stages. All the concentrations of hexaconazole used significantly decreased the stem length and leaf area, whereas side branches, fresh and dry matter content, photosynthetic pigments, and antioxidant potential were increased. The number of tubers, length and girth of tubers, fresh and dry weight of tubers and tuber pigments were found to be the highest at a 25 mg L(-1) concentration of hexaconazole. Hexaconazole application at 25 mg L(-1) concentration was found to be more effective than 10, 15, 20, 25, and 30 mg L(-1) in promoting fresh and dry weight of root tuber over 165 days after planting. The pigments like chlorophyll, carotenoid; anthocyanins, xanthophylls and antioxidants such as ascorbic acid, reduced glutathione and total phenol were significantly increased under hexaconazole treatment when compared to untreated control plants.