A multigene approach to determine the molecular phylogeography of Argiope mangal and Argiope dang (Araneae: Araneidae) and their genetic relationships with the Argiope aetherea species group

The genus Argiope represents a collection of morphologically diverse orb-weaving spiders with a cosmopolitan distribution. Argiope dang and A. mangal are two Southeast Asian species that share remarkably similar morphological characteristics congeneric to the A. aetherea species group. However, in previous investigations, molecular data have not been used for the taxonomic categorization of A. dang and A. mangal. Additionally, gene flow between populations of A. dang and of A. mangal in their natural habitats has not been adequately studied. In the present study, mitochondrial 16S, COI and COII markers were used in addition to the nuclear H3 gene to elucidate the relationships between A. dang, A. mangal and various congeners within the A. aetherea species group. The haplotype diversity of A. dang and A. mangal was also investigated. Based on our molecular results, the A. aetherea species group was composed of three genetic lineages: (i) [A. dang - (A. radon - A. picta)] - [A. modesta - A. aetherea]; (ii) A. mangal; and (iii) [(A. jinghongensis - A. aetheroides) - A. versicolor]. Haplotype analyses revealed a lack of gene flow between A. mangal populations in Peninsular Malaysia and those in Singapore. Populations of A. dang showed isolation-by-distance throughout the range of the species from Laos to Singapore. In this study for the first time, genetic data of A. mangal were reported for specimens collected from its type locality, Singapore. Four new distribution records were also reported: A. dang in Peninsular Malaysia and Cambodia; A. modesta in Bali, Indonesia; and A. jinghongensis in Peninsular Malaysia.     

悦目金蛛(Argiope amoena)染色体的观察

对悦目金株（Ａｒｇｉｏｐｅ ａｍｏｅｎａ）染色体的数目、形态特征和性染色体组成,进行了核型分析,本实验观察胚胎细胞有丝分裂的Ｃ－中期相,悦目金蛛体细胞染色体数目是：雌性２ｎ＝２６,雄性２ｎ＝２４,性别决定机制属于ＸＸＯ型。     

Carbohydrates in the webs of Argiope spiders

Glycoproteins are present in the web of the orb-weaving spiders Argiope trifasciata and Argiope aurantia. Periodic acid-Schriff reactive glyco-proteins are confined in large part, to the sticky spiral and sticky spiral-radial junctions. Glycoproteins containing amino sugars appear associated with all fibers, especially the radial fibers. Enzymes may be used to remove glycoproteins selectively from the sticky spiral and stabilimentum.     

悦目金蛛卵袋的结构与组成

采用SEM和氨基酸自动分析仪对悦目金蛛(Argiope amoena)卵袋的结构、纤维组成和覆盖层的氨基酸组成进行了观察研究.结果表明悦目金蛛卵袋呈封闭的倒三角形,是由多种丝腺纺出的丝纤维形成的多个覆盖层构成的,从外向内分别为:金黄色大壶状腺框架丝,灰绿色、浅棕色、白色外覆盖层和棕色内覆盖层,其中外覆盖层是由6根大直径(约4.8-6.8 μm) 柱状腺丝纤维和一些小直径(约0.26-0.76 μm)纤维混合成的基本纤维束单元所折叠成的片层丝被构成的,小直径丝纤维的数量从灰绿色丝被(外)到白色丝被(内)逐渐增加,而内覆盖层仅仅是由6根大直径(约5.20 μm)柱状腺丝纤维构成的基本纤维束单元折叠而成.卵袋外覆盖层丝(白色绒状纤维除外)的甘氨酸、丙氨酸和丝氨酸等氨基酸的百分含量分别介于卵袋内覆盖层丝和葡萄状腺丝相对应氨基酸的百分含量之间,这一数据支持Foradori等关于卵袋小直径丝纤维是由葡萄状腺纺出的推论.悦目金蛛能调节卵袋层丝的颜色、直径、覆盖层丝纤维和氨基酸的组成,使卵袋获得各方面最优化的功能,为卵或若蛛提供支持和保护.     

Predatory Behavior of Argiope argentata (Fabricius)

SYNOPSIS. Insects striking the web of Argiope argentata evokea complex sequence of behaviors. These involve prey-location,prey-immobilization, prey-transport, and preymanipulation beforefeeding. The behavioral elements which form a sequence are notalways the same nor do they always occur in the same order.This paper describes some commonly occurring sequences and reportson progress in the experimental analysis of the external stimuliwhich affect the form of such sequences. Particular emphasisis given to the stimuli which affect the first response to contactwith the prey. The initial response to butterflies and mothsis a long bite, whereas all other insects, except the very smallest,are wrapped in silk. This special response to Lepidoptera isprobably adaptive since it applies very rapid restraint to insectswhich can escape rapidly from spiders' webs. The long bite givento Lepidoptera is based on a discrimination which is not affectedby vibration, weight, size, or shape. Experiments suggest thatdiscrimination is based on surface texture. The functional significanceof other elements of the behavioral sequences is discussed.     

悦目金蛛拖丝的超微结构研究

采用非固定的抽丝方法,从一只未麻醉的悦目金蛛(Argiope amoena)的纺器将拖丝抽出,然后用扫描电镜(SEM)对拖丝进行超微结构的观察,结果表明:悦目金蛛拖丝至少具有2根、3根、4根及多根单丝纤维构成的4种不同结构,其中有一种类似弹簧的结构;另外,丝的表面还出现一种小环结构,这两种结构可能是拖丝纤维具有优良机械性能的原因之一。"束状结构"和"小环结构"在文献中未见报道。拖丝的直径范围为0.25~10.77μm;悦目金蛛似乎能调节拖丝的结构和直径,以适应其所面临的即时环境。本文基于上述观察结果并结合前人的研究,提出了蜘蛛拖丝结构-生物学功能多样性假说,对蜘蛛丝的结构与生物学功能之间的关系作了探讨。     

Glutamate receptor antagonists from the spider Argiope lobata venom

Homologous low molecular weight compounds blocking postsynaptic glutamate receptors were isolated from the Argiope lobata spider venom by ion-exchange chromatography and reverse-phase HPLC. Structures of nine different blocking agents were determined by NMR and mass spectroscopy. They can be divided into three groups: argiopin, argiopinins and pseudoargiopinines. The major principles of the structural organization of the novel class of antagonists of glutamate receptors were considered.     

The chemical fractionation of the orb web of Argiope spiders

The orb webs of Argiope aurantia Lucas and Argiope trifasciata (Forskal) were partitioned into three major fractions: trypsin soluble fibroin, trypsin insoluble fibroin and a water soluble fraction. The gravimetric proportions of these were nearly equal in both species. The water soluble fraction was further fractionated into KH₂PO₄, ninhydrin reactive and ninhydrin negative components. The proportions of these differed widely between the two species. The amino acid composition of the trypsin soluble fibroin and trypsin insoluble fibroin was ascertained, as well as the spinning gland luminal contents in order to assign the probable glandular origin of these fractions. The trypsin insoluble fibroin originates primarily from the large ampullate gland whereas the trypsin soluble fibroin appears to be the product of several glands.     

Determinants of natural mating success in the cannibalistic orb-web spider Argiope bruennichi

Monogynous mating systems (low male mating rates) occur in various taxa and have evolved several times independently in spiders. Monogyny is associated with remarkable male mating strategies and predicted to evolve under a male-biased sex ratio. While male reproductive strategies are well documented and male mating rates are easy to quantify, especially in sexually cannibalistic species, female reproductive strategies, the optimal female mating rate, and the factors that affect the evolution of female mating rates are still unclear. In this study, we examined natural female mating rates and tested the assumption of a male-biased sex ratio and female polyandry in a natural population of Argiope bruennichi in which we controlled female mating status prior to observations. We predicted variation in female mating frequencies as a result of spatial and temporal heterogeneity in the distribution of mature females and males. Females had a low average mating rate of 1.3 and the majority copulated only once. Polyandry did not entirely result from a male-biased sex-ratio but closely matched the rate of male bigamy. Male activity and the probability of polyandry correlated with factors affecting pheromone presence such as virgin females' density. We conclude that a strong sex ratio bias and high female mating rates are not necessary components of monogynous mating systems as long as males protect their paternity effectively and certain frequencies of bigyny stabilise the mating system.     

Female control of paternity in the sexually cannibalistic spider Argiope keyserlingi

Sexual conflict theory predicts an antagonistic coevolution, with each sex evolving adaptations and counter-adaptations to overcome a temporary dominance of the other sex over the control of paternity. Polyandry allows sexual selection to operate after mating has commenced, with male and female interests competing for control of fertilization. There are numerous examples of male control of paternity, but few studies have unambiguously revealed female control. Attributing variance in paternity to females is often difficult since male and female influences cannot be separated unambiguously. However, we show that polyandrous female orb-web spiders Argiope keserlingi (Arancidae) control the paternity of their offspring by adjusting the timing of sexual cannibalism. Our experiments reveal that females copulating with relatively smaller males delay sexual cannibalism, thereby prolonging the duration of copulation, and that these males consequently fertilize relatively more eggs.     

寡居种悦目金蛛若蛛群居机制初步研究

对寡居种悦目金蛛Argiope amoena若蛛群居生活对其结网的影响、温度和种群大小对若蛛存活率的影响、若蛛对限制性空间的利用及其扩散方式进行了观察和研究.结果表明,若蛛从卵袋出蛰后不经历群居扩散即具备结网能力,可结完整网,也具备在扩散前不进食水存活的能力;在变温条件下若蛛存活率要远远高于室温条件下的存活率,而在室温条件下若蛛开始死亡和半数死亡的时间比其聚居期长得多;若蛛主要通过群体空中扩散的方式进行扩散,可以减小能耗与敌害的威胁;不同种群大小的若蛛在限制性空间的分布均从第5d左右开始发生较大变化的,这与在空间不受限的条件下若蛛在第5d开始扩散的结果是一致的.据此我们推断:个体扩散代价最小化(包括御敌和能耗)和维持种群较高的生存率可能是寡居种悦目金蛛若蛛群居生活的主要原因.     

Novel molecular and mechanical properties of egg case silk from wasp spider, Argiope bruennichi

Araneoid spiders use specialized abdominal glands to produce up to seven different protein-based silks/glues that have various mechanical properties. To date, the fibroin sequences encoding egg case fibers have not been fully determined. To gain further understanding of a recently reported spider silk protein gene family, several novel strategies were utilized in this study to isolate two full-length cDNAs of egg case silk proteins, cylindrical silk protein 1 (CySp1, 9.1 kb) and cylindrical silk protein 2 (CySp2, 9.8 kb), from the wasp spider, Argiope bruennichi. Northern blotting analysis demonstrated that CySp1 and CySp2 are selectively expressed in the cylindrical glands. The amino acid composition of raw egg case silk was closely consistent with the deduced amino acid composition based on the sequences of CySp1 and CySp2, which supports the assertion that CySp1 and CySp2 represent two major components of egg case silk. CySp1 and CySp2 are primarily composed of remarkable homogeneous assemble repeats that are 180 residues in length and consist of several complex subrepeats, and they contain highly homologous C-termini and markedly different N-termini. Our results suggest a possible link between CySp1 and CySp2. In addition, comparisons of stress/strain curves for dragline and egg case silk from Argiope bruennichi showed obvious differences in ultimate strength and extensibility, and similarities in toughness.     

棒络新妇和悦目金蛛丝腺形态初步观察

研究比较了结网型蜘蛛棒络新妇Nephila clavata和悦目金蛛Argiope amoena的丝腺形态特征,为国内蜘蛛丝腺蛋白的研究提供原始的丝腺解剖图,同时结合对2种蜘蛛卵袋的解剖、网的特征和室内捕食黄粉虫Tenebrio molitor幼虫行为的观察比较,探讨了2种蜘蛛丝腺的生物学功能与其生存繁殖策略之间的关系。本文分别观察描述了棒络新妇和悦目金蛛的大壶状腺、小壶状腺、鞭状腺、柱状腺、葡萄状腺和梨状腺共6种丝腺。2种蜘蛛丝腺形态特征基本相似;部分丝腺在形态结构和颜色上有些差异;悦目金蛛的葡萄状腺比棒络新妇发达。观察表明2种蜘蛛的网和卵袋特征差异较大,两者捕食策略也不同,棒络新妇采用咬一捆缚（Bit—Wrapping）策略,悦目金蛛则采用捆缚一咬（Wrapping-Bit）策略。棒络新妇和悦目金蛛的网和卵袋特征与丝腺的颜色相一致。同时,其葡萄状腺数量和大小与其各自的捕食策略相关。     

Prey protein influences growth and decoration building in the orb web spider Argiope keyserlingi

Abstract. 1. Protein is important for a foraging animal to consume, as it promotes growth and enhances survival, particularly in web‐building spiders, which need to invest considerable protein into web building and may trade‐off growth for web investment. 2. The influence of dietary protein uptake on growth and web investment was tested in the orb web spider Argiope keyserlingi, by feeding them flies reared on three different media: (1) high protein, (2) low protein, and (3) standard (control) media. There was a negative correlation between protein and energy content of the flies across treatments; flies reared on the high protein media had the highest protein, but lowest energy, while flies reared on the low protein media had the lowest protein but highest energy. 3. It was found that silk investment and web architecture in A. keyserlingi was not affected by diet. Growth and decoration building were both enhanced when spiders were fed a high protein diet. 4. It was concluded that protein intake, rather than energy, influenced both growth and decoration building because: (1) protein intake enhances growth in other animals, (2) protein is essential for silk synthesis, especially aciniform silk, and (3) protein is a limiting factor actively sought by foraging animals in natural environments.     

悦目金蛛丝腺SMART RACE cDNA文库的构建与鉴定

运用SMART 技术构建了悦目金蛛丝腺SMART RACE cDNA文库.经检测,文库所含全长cDNA的长度主要集中在500 bp～2000 bp 之间;把双链cDNA通过T/A克隆、随机挑选阳性克隆并测序后,得到1条752 bp的全长cDNA序列.以该文库为模板,用依据这条全长cDNA序列设计的基因特异性引物与接头引物进行RACE, 3'RACE 和5'RACE的产物拼接后的全长序列与上述全长cDNA序列一致.结果表明,该文库适于用RACE方法从中分离在悦目金蛛丝腺中表达基因的全长cDNA.本文还对SMART 技术的特点和局限性进行了讨论.     

Males of the orb-web spider Argiope bruennichi sacrifice themselves to unrelated females

Costs of inbreeding can lead to total reproductive failure and inbreeding avoidance is, therefore, common. In classical sex roles with no paternal care, the selective pressure to avoid inbreeding is mostly on the female, which carries the higher costs. In some orb-web spiders, this situation is very different because females are polyandrous and males are monogynous or at most bigynous. Additionally, females of many entelegyne orb weavers are thought to bias paternity post-copulatorily towards a desired mate. This increases the selective pressure on males to adjust their investment in a mating with regard to the compatibility to a female.Here, we examine whether genetic relatedness influences mating behaviour in the orb-web spider Argiope bruennichi. We mated either a sibling or a non-sibling male to a female in single copulation trials and compared copulation duration, cannibalism rate and female fecundity.Our experiment revealed that males prolonged their copulation duration and were cannibalized more frequently when mating with a non-sibling female. Males mating with a sibling female were more likely to escape cannibalism by copulating briefly, thus presumably increasing their chances of re-mating with a more compatible female. This suggests that males can adaptively adjust their investment relating to the compatibility of a female.     

Properties of synthetic spider silk fibers based on Argiope aurantia MaSp2

Spiders have evolved a complex system of silk producing glands. Each of the glands produces silk with strength and elasticity tailored to its biological purpose. Sequence analysis of the major ampullate silk reveals four highly conserved concatenated blocks of amino acids: (GA) n , A n , GPGXX, and GGX. While the GPGXX motif, which has been hypothesized to be responsible for the extensibility of the fiber, displays natural variation in its precise sequence arrangement and content, correlating these differences with particular fiber properties has been difficult. Three genetic constructs based on the Argiope aurantia sequence were engineered to progressively increase the number of GPGXX repeats in a head-to-tail assembly prior to interruption by another motif. Circular dichroism and Fourier transform infrared spectroscopy of synthetic spider silk spin dopes show secondary structures that correspond to an increase in the repeat number of GPGXX regions and an increase in the extensibility of synthetically spun recombinant fibers.