Regeneration and autotomy exhibited by the Black Widow spider,Latrodectus variolus walckenaer

Summary Crustaceans, insects and to a lesser degree arachnids have been employed in regeneration studies. Amputation and ligation of the legs was used to determine occurring in a Black Widow spider complied with the developmental gradient model of regeneration. The occurrence of autotomy in this species was also documented. Amputation indicated the most proximal point from which regeneration of the leg could occur was the femoral mid-point. Amputation proximal to that area did not result in leg regeneration. Autotomy following amputation was not observed. Ligation of the legs resulted in autotomy when applied at and proximal to the mid-point of the tibia, increasing in frequency as more proximal segments were ligated. Autotomy always occurred at the trochanter-coxa joint. Autotomized legs did not regenerate. The regeneration observed complied with the developmental gradient model.     

The Genes Encoding Black Widow Spider Neurotoxins are Intronless

The overlapping fragments of the chromosomal DNA from black widow spider Latrodectus mactans carrying genes for high-molecular-mass protein neurotoxins, - and -latroinsectotoxins (-LIT and -LIT) and -latrotoxin (-LTX), were PCR-amplified and cloned. Restriction analysis of the PCR products showed that the distribution and sizes of the restriction fragments coincided with those deduced from the earlier sequencing of cDNAs of the corresponding genes. It thus followed that the -LIT and -LIT genes are intronless. Along with our data on the structure of the -latrocrustotoxin (-LCT), this implies that the lack of introns is a common feature of the black widow spider genes encoding high molecular mass neurotoxins.     

Protein Compositional Analysis of the Eggs of Black Widow Spider (Latrodectus tredecimguttatus): Implications for the Understanding of Egg Toxicity

Previous work found that high‐molecular‐weight fractions in the egg extract of Latrodectus tredecimguttatus exhibited strong toxicities. For investigating the possible relationship of proteins in the eggs with the toxic effect, the protein composition of the eggs was analyzed using proteomic strategies and compared with that of the spider's venom. SDS‐PAGE showed that the proteins of eggs were primarily distributed in the molecular weight range of higher than 55 kDa as well as around 34 kDa, having high abundance proteins with molecular weights of about 60 kDa and 130 kDa. A total of 157 proteins were identified from the egg extract, which were involved in important cellular functions and processes including catalysis, transport, and metabolism regulation. Comparison indicated that the protein composition of eggs is more complex than that of venom, and there are few similarities between the protein composition of the two materials, demonstrating that the eggs have their own distinct toxic mechanism. © 2012Wiley Periodicals, Inc. J BiochemMol Toxicol 26:510‐515, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21460     

Family Affects Sibling Cannibalism in the Black Widow Spider,Latrodectus hesperus

Adaptive foraging tactics are shaped by genes, the environment and gene–environment interactions. Because of relatively high levels of agonism toward conspecifics, spiders have been a popular focus for behavioral–ecological examinations of conspecific predation, or cannibalism. Surprisingly, studies examining the underlying, proximate assumption that cannibalism in spiders is a heritable trait shaped by interactions between genes and the environment are virtually non‐existent. Here, we examine the influence of family on the expression of sibling cannibalism in the post‐hatching, group‐living phase of an otherwise solitary, web‐building spider, the North American black widow (Latrodectus hesperus). Our results showed significant levels of variation in cannibalistic propensity among 26 sibships, with some families cannibalizing full sibs within 2 d and other families waiting 3 wk before resorting to cannibalism. A similar family‐level effect was evident in measures of sibling cohabitation, voracity toward cricket prey, and development speed. Negative correlations between maternal egg sac investment and offspring cannibalism suggest that this family effect may stem, at least in part, from a maternal effect, although we were not able to directly test the prediction that cannibalism is most common from spiderlings in poor condition. Thus, we present novel data suggesting family effects seem to be responsible for cannibalism in L. hesperus spiderlings; however, future work will be required to disentangle the relative importance of shared genes and shared maternal environment. We discuss several mechanisms that could explain the persistence of family‐level variation in cannibalism, a trait that seems likely to be subject to strong directional selection.     

The Action of Black Widow Spider Venom on Cholinergic Mechanisms in Synaptosomes

Abstract: Black widow spider venom (BWSV) promoted the massive release of labeled acetylcholine from synaptosomes and in addition, inhibited high-affinity choline uptake into the preparation. Both activities occurred in the absence of [Ca²⁺]₀. When Na⁺ in Krebs-Ringer was replaced isotonically by sucrose, BWSV did not cause any release of [³H]ACh. On the other hand, BWSV was still effective if Na⁺ was replaced by lithium, glucosamine, or Tris. Tetrodotoxin (10^?5 M) failed to prevent the ACh-releasing action of the venom. The uptake of [³H]norepinephrine and [³H]tyrosine into the P₂ fraction was significantly inhibited by BWSV pretreatment. However, the effect of the venom on the uptake of [³H]deoxyglucose was slight. In addition, the venom-induced release of [³H]norepinephrine was much higher than that of [³H]deoxyglucose. The change in membrane potential of the preparation in duced by BWSV as examined using the voltage-sensitive fluorescence probe, 3, 3′-dipentyl-2, 2′-oxacarbocyanine. BWSV pretreatment markedly increased the synaptosomal fluorescence, indicating a depolarization of the preparation. This action of the venom was also observed in a Ca²⁺ -free or K⁺ -free medium, but could be blocked by pretreatment with antivenom. Pretreatment of the P₂ fraction with concanavalin A completely blocked the action of BWSV. Also, the BWSV failed to promote the release of transmitter if the venom was prein-cubated with a low concentration of purified gangliosides. Even after prolonged treatment with high concentrations of BWSV, an electron microscopic study showed no depletion of the synaptic vesicles in presynaptic terminals of the cortical P₂ preparations or striatal slices. It is suggested that the venom expresses its activity by binding to glycoproteins and/or gangliosides on the synaptic membrane, opening a cation channel. The subsequent depolarization then inhibits uptake processes and promotes transmitter release that is independent of external calcium.     

Fine Structural Analysis of the Silk Apparatus in the Funnel-web Spider, Agelena limbata (Araneae: Agelenidae)

ABSTRACT Silk apparatus of the funnel-web spider, Agelena limbata was located at the ventral end of the abdominal part, and was composed of internal silk glands and external spinnerets. Among the three pairs of spinnerets, the posterior pairs were highly elongated along the body axis. By the light and electron microscopic inspections, it was found that four types of silk glands were connected through the typical spinning tubes of each spinneret. Anterior spinnerets comprise 2 pairs of the ampullate and 125 to 150 pairs (female) or 110 to 114 (male) of pyriform glands. Another 2 pairs of ampullate glands in both sexes, 5 to 8 pairs of tubuliform glands in females, and 20 to 26 pairs (female) or 15 to 17 pairs (male) of aciniform glands were connected on the median spinnerets. Additional 8 to 10 pairs of tubuliforms in female and 41 to 53 pairs (female) or 27 to 32 pairs (male) of aciniform glands were on the posterior spinnerets, respectively. While the ampullate and tubuliform glands were connected with the spigot-type spinning tubes, the pyriform and aciniform glands with that of spool-type tubes. It has been also revealed that the tubuliform glands were only observed in female spiders, however the flagelliform and aggregate glands which had the function of adhesive thread production in orb-web spiders were not observed at both sexes of this spiders.     

Fine Structure of the Ovarian Development in the Orb-web Spider, Nephila clavata

ABSTRACT Fine structural changes of the ovary and cellular composition of oocyte with respect to ovarian development in the orb-web spider, Nephila clavata were examined by scanning and transmission electron microscopy. Unlike the other arthropods, the ovary of this spider has only two kinds of cells-follicle cells and oocytes. During the ovarian maturation, each oocyte bulges into the body cavity and attaches to surface of the elongated ovarian epithelium through its peculiar short stalk attachments. In the cytoplasm of the developing oocyte two main types of yolk granules, electron-dense proteid yolk and electron-lucent lipid yolk granules, are compactly aggregated with numerous glycogen particles. The cytoplasm of the developing oocyte contains a lot of ribosomes, poorly developed rough endoplasmic reticulum, mitochondria and lipid droplets. These cell organelles, however, gradually degenerate by the later stage of vitellogenesis. During the active vitellogenesis stage, the proteid yolk is very rapidly formed and the oocyte increases in size. However, the micropinocytosis invagination or pinocytotic vesicles can scarcely be recognized, although the microvilli can be found in some space between the oocyte and ovarian epithelium. During the vitellogenesis, the lipid droplets in the cytoplasm of oocytes increase in number, and become abundant in the peripheral cytoplasm close to the stalks. On completion of the yolk formation the vitelline membrane, which is composed of an inner homogeneous electron-lucent component and an outer layer of electron-dense component is formed around the oocyte.     

Frequent Failure of Male Monopolization Strategies as a Cost of Female Choice in the Black Widow Spider Latrodectus tredecimguttatus

In many mating systems, males strive for securing paternity through monopolizing females. As male monopolization attempts often contradict female interests, this conflict may fuel an evolutionary arms race. In the widow spider genus Latrodectus, females are commonly polyandrous, whereas males are monogynous, hence restricted to mate with a single female, making paternity protection particularly important. Potential mating plugs (specialized embolus sclerites of male copulatory organs) have been discovered in the complex female genital tracts of several Latrodectus species. In this study, we investigated mating strategies in the Mediterranean black widow spider Latrodectus tredecimguttatus and tested the adaptive value of female attacks against male monopolization efforts. In a double mating experiment, we manipulated the number of insertions (=copulations) for first and second males to assess female behaviour and male embolus sclerite placement success. Our results indicate that first males′ embolus sclerites inside the females′ sperm stores physically block sclerites of subsequent males. While female attacks did not affect the deposition of potential mating plugs, they significantly reduced copulation duration. Irrespective of female aggression, male sclerite placement failure occurred frequently, but large males were more successful than smaller competitors. We suggest that the complex genital morphology in both sexes may have co‐evolved antagonistically and female morphology could serve to favour large males for fertilization.     

间斑寇蛛粗毒液的生理生化分析及两种采毒方法的比较

利用两种不同方法采集间斑寇蛛（Latrodectus tredecimguttatus）毒液并对其进行理化和生物学性质的比较分析。结果显示,粗毒液中的蛋白质成分主要是相对分子质量较大（>104）的酸性蛋白质。与毒囊粗毒液相比,电刺激粗毒液中相对分子质量在105左右的蛋白质含量明显高于毒囊粗毒液中的含量,而两者中相对分子质量较小（<104）的蛋白质与多肽的组成非常相似。电刺激粗毒冻干粉和毒囊粗毒冻干粉对小白鼠的LD50值分别为(0.16±0.03) mg/kg和(0.39±0.05)mg/kg体重;对美洲蜚蠊（Periplaneta Americana）的LD50值分别为1.87 μg/g和2.32 μg/g。在浓度为3.2×10-6g/mL时,电刺激粗毒冻干粉能在（25.0±2.2） min内完全阻断小鼠膈神经-膈肌标本的神经肌肉接头传递;毒囊粗毒冻干粉在浓度为6×10-6g/mL时的完全阻断时间为（23.3±2.2） min;粗毒液中的低相对分子质量（<104）部分在10-4g/mL浓度下对标本的神经肌肉接头传递无明显影响。上述结果表明,间斑寇蛛毒液是一种富含大分子量蛋白质的混合物;哺乳动物神经毒性主要基于其中的大的相对分子质量酸性蛋白质成分,而不是低的相对分子质量的多肽;电刺激粗毒液中的活性成分与毒囊粗毒液中的相似,但含量高于毒囊粗毒液。     

Tetanus and Botulinum Toxins Inhibit, and Black Widow Spider Venom Stimulates the Release of Methionine-Enkephalin-Like Material In Vitro

The actions of tetanus toxin, botulinum A toxin, and black widow spider venom on the release of methionine-enkephalin-like immunoreactivity have been studied; a particulate fraction prepared from rat striata was used. Depending on the duration of preincubation, tetanus toxin diminished the release evoked by veratridine (50 microM final concentration), and abolished it at final concentrations between 0.1 and 1 micrograms/ml. Botulinum A toxin was about 10 to 20 times less potent. Heating or pretreatment with antitoxin inactivated the clostridial toxins. The particulate fraction pretreated with V. cholerae neuraminidase retained its toxin sensitivity. Tetanus toxin also depressed the release due to sea anemone toxin II and high K+. Spider venom stimulated the release in a concentration-dependent manner and required the presence of Ca2+; its effects were depressed by tetanus toxin. These results support the view that both clostridial toxins and spider venom act as broad-range presynaptic neurotoxins on peptidergic transmitter systems.     

Multiple recombining loci encode MaSp1, the primary constituent of dragline silk, in widow spiders (Latrodectus: Theridiidae)

Spiders spin a functionally diverse array of silk fibers, each composed of one or more unique proteins. Most of these proteins, in turn, are encoded by members of a single gene family thought to have arisen through duplication and divergence of an ancestral silk gene. Because of its remarkable mechanical properties, orb weaver dragline silk, a composite of 2 proteins (MaSp1 and MaSp2), is the best studied. Here, we demonstrate that multiple loci encode MaSp1 in widow spiders (Latrodectus). Because these copies may be the result of more recent duplication events than those leading to the currently recognized silk gene paralogs, they offer insight into the early evolutionary fate of silk gene duplicates. In addition to 3 presumed functional MaSp1 loci in Latrodectus hesperus (Western black widow) and Latrodectus geometricus (brown widow) genomes, we find a MaSp1 pseudogene in L. hesperus, demonstrating the potential for unrecognized extinction of silk gene paralogs. We also document recombination events among L. hesperus MaSp1 loci and between Latrodectus MaSp1 loci and MaSp2. This result supports the hypothesis that concerted evolution occurs not only within an individual silk gene but also among silk gene paralogs. One of the L. geometricus MaSp1 copies encodes a protein that has diverged in amino acid composition and potentially converged on the secondary structure of MaSp2. Based on the presence of multiple MaSp1 loci and the phylogenetic distribution of MaSp1 versus MaSp2, we propose that MaSp2 is derived from an ancestral MaSp1 duplicate. Finally, divergence has occurred in the upstream flanking sequences of the L. hesperus MaSp1 loci, the region most likely to contain regulatory motifs, providing ample opportunity for differential expression. However, the benefits associated with increased protein production may be the primary mechanism maintaining multiple functional MaSp1 copies in widow genomes.     

Some effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes

A study was made of the effects of the venom of the Chilean spider Latrodectus mactans on endogenous ion-currents of Xenopus laevis oocytes. 1 μg/ml of the venom made the resting plasma membrane potential more negative in cells voltage-clamped at −60 mV. The effect was potentially due to the closure of one or several conductances that were investigated further. Thus, we determined the effects of the venom on the following endogenous ionic-currents: (a) voltage-activated potassium currents, (b) voltage-activated chloride-currents, and (c) calcium-dependent chloride-currents (Tout). The results suggest that the venom exerts its action mainly on a transient outward potassium-current that is probably mediated by a Kv channel homologous to shaker. Consistent with the electrophysiological evidence we detected the expression of the mRNA coding for xKv1.1 in the oocytes.     

Investigation of two new putative pheromone components of the invasive Australian redback spider,Latrodectus hasseltii,with potential applications for control

The Australian redback spider, Latrodectus hasseltii preys on at least 10 endemic species in New Zealand, highlighting a need for control. Male redbacks are attracted to virgin females by an airborne pheromone. The aim of this study was to analyse the response of male redback spiders to two volatile chemicals found on the silk of virgin but not mated females, to determine whether these compounds constitute components of the airborne pheromone. Mature male redback spiders were placed in an olfactometer where they had a choice of two stimuli. We compared their response to paired combinations of a control, virgin silk, butyric acid and isovaleric acid. Male redbacks responded equally strongly to butyric acid and virgin silk, in terms of time spent near the stimulus. The identification of butyric acid as a component of the airborne sex pheromone of L. hasseltii provides the groundwork for developing a pheromone-based control.     

2种不同采样方法对麦田蜘蛛群落结构的比较研究

分别于1998年11月到1999年5月和1999年11月到2000年5月间,在位于武汉市武昌区的沙湖边,使用样方和陷阱法系统采样,研究了裸粒大麦田的蜘蛛群落结构。研究结果显示,1998-1999年麦田蜘蛛群落由11科44种蜘蛛组成,1999-2000年麦田蜘蛛群落由14科59种蜘蛛组成;相同年份不同采样方法获得的蜘蛛群落优势种组成不同,陷阱法采样获得的优势种集中在皿蛛科、狼蛛科和平腹蛛科,而样方采样虽然也以皿蛛科和狼蛛科蜘蛛为主,但球蛛科、肖蛸科和园蛛科蜘蛛的比例明显上升;不同的年份使用相同的采样方法获得的蜘蛛优势种组成不同,显示了群落结构的年际变动。对2种采样方法获得的群落相似性分析显示,不同采样方法获得的群落结构相似性较小。     

小麦,玉米轮作田蜘蛛群落结构及多样性研究

一、研究方法本项工作于1988—1990年在青州市南郊农田进行。位于东经118°17′,北纬36°27′,年平均气温9℃,年降雨量860mm以上,无霜期180天左右。调查了不同作物类型的地块,包括玉米间作(大豆)田、净玉米田、有水浇条件的麦田、旱麦田和田埂杂草五种生境。其中小麦、玉米轮作田各3块,每块面积0.2ha以     

Effects of food deprivation on Latrodectus hasselti Thorell (Araneae: Theridiidae), the Australian redback spider

Abstract

Food deprivation tests indicate that most sub-adult and adult female Latrodectus hasselti spiders would be able to endure long periods of starvation if incarcerated in cargo. The data show that, under appropriate conditions, sub-adults survive for up to 160 days and some adults for more that 300 days. Temperature is an important variable with longevity being greatest at 10°C and markedly reduced at 25°C. Sluggishness is more pronounced at lower temperatures and probably reflects reduced metabolic rates. Even after 2–3 months without food, most spiders recover when fed.

Five stages mark the progress of starvation (Indices of Starvation) and reflect a gradual decline in the spider’s normal functions. As the abdomen shrinks, with a concomitant loss of hydraulic pressure, there is a gradual decline in web-building and locomotory activities which ultimately end in the spider’s death. It is assumed that nutritional deficiency and, to a lesser extent, dehydration contribute to mortality.     

不同冬季气候条件下的麦田蜘蛛群落结构和优势种繁殖情况

1998～1999年、1999～2000年在武汉地区使用陷阱法系统采样,研究了大麦田蜘蛛群落结构,比较了不同的冬天气候因素对麦田蜘蛛群落结构的影响.使用Berger-Parker优势度指数分析了调查时间段大麦田的地面优势种蜘蛛.结果显示,1998～1999年的优势种蜘蛛为皿蛛科蜘蛛,隆背微蛛Erigone prominens Boes. et Str.在大麦的全生长期均为优势种.1999～2000年,主要的优势种蜘蛛为狼蛛科的类水狼株Pirata piratoides Boes.et Str.、沟渠豹蛛Pardosa laura Karsch和拟环纹豹蛛Pardosa pseudoannulata (Boes.et Str.).另外,通过各优势种蜘蛛雄蛛的个体数变化,探讨了各优势种蜘蛛在田间的交配繁殖情况.结果表明,冬天气候对蜘蛛的交配时期有明显影响.在暖冬天气,大多数种类的交配比冷冬提前.一般情况下,各优势种蜘蛛能在麦田繁殖1代.另外,还对平腹蛛科的2种蜘蛛的雄蛛在田间的活动情况进行了描述.     

High-Resolution Cryo-EM Structure of the Cardiac Actomyosin Complex

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