Latrodectus Research Articles

In this Issue

i IN THIS ISSUE Bruce Osborne Varying perceptions of a non-native introduction The introduction of non-native species and their often negative impacts are of much current concern, although where would we be without many alien introductions,including the majority of crop plants? Clearly we want to be able to harness the benefits of many alien species without any harmful consequences ,although in a number of cases it is a balancing act,given that they may have both a positive and a negative contribution.The European brown hare (Lepus europaeus),which was introduced into Ireland in the 1880s for field sports,has been associated with a marked decline in the numbers of the native Irish Hare (L. timidus hibernicus) in parts of Northern Ireland as well as evidence for hybridisation between the two species.As Caravaggi et al., in this issue, point out,this is a cause of significant concern as the Irish hare is a high priority for conservation and one of the few Irish mammals that predate the Holocene. But how do we manage the conflicting interests of the field sports enthusiast with conservationists? When Caravaggi et al. conducted a survey among members of Countryside Alliance Ireland (CAI) and non-members to ascertain the contrasting attitudes to the lethal control of the European hare, they found some interesting results. Whilst both groups recognised the threats posed to native biodiversity by the European hare, CAI members were both more aware of the presence of non-native species and more prepared to support lethal management interventions. So what are we to make of all of this? One concern could be that the conclusions where based on a relatively small number of respondents (20%),suggesting a more extensive analysis might be required. However, these results may have also identified a more fundamental issue that conservationists are, in general, unwilling to agree to lethal control measures where animals are concerned, particularly those that have become an inextricable part of the regional fauna, irrespective of whether they are native or non-native. Using surrogate metrics to estimate fish weights In biology and ecology research we are often confronted with situations where direct measurements of the parameter(s) of interest are often almost impossible , impractical or uneconomical.This is where surrogate metrics become invaluable.We often, for instance, estimate leaf area from length and breadth measurements in plant growth and photosynthesis studies.Another such case relates to the estimates of fish stocks,where the recording of a sufficient number of individual weights is often very difficult or could result in significant mortality. Not only is this important for assessing fish stocks per se, it can also provide information on fish health and growth rate for both commercial and research purposes. What is required is a simple, cheap and effective method that provides reasonable estimates of fish weights. Connor et al., in this issue, provide an assessment of the use of length-weight relationships to estimate the weights of a range of fish species found in contrasting Irish lakes and rivers using a data set spanning a period of approximately 10 years.Their conclusions, based on an analysis of approximately 230,000 individuals, indicate that fish length is a good predictor of weight and provides a simple way of routinely assessing fish stocks in Irish lakes and rivers.In truth,the use of length as a surrogate measure of fish weights is not new, but significant variations can be found due to environmental factors and because of non-linearity in the relationship between weight and length, making general relationships difficult. What Connor et al. have done is to provide improved length-weight relationships that can be specifically applied to common fish species found in Irish lakes and rivers. The most feared spider in Britain and Ireland? The false widow spider (Steatoda nobilis) is widely regarded as the most feared spider in Britain, although it may often be confused with its much more dangerous cousin, the black widow spider (Latrodectus sp.), which has a venom reportedly fifteen times more toxic than a rattlesnake! The false widow can, however, still give you a nasty bite that could become infected if not properly treated.The first record...

Black widow spider bites experience from tertiary care center in Saudi Arabia.

Introduction:Black widow spiders are one of the most poisonous species to humans; there are more than 30 species of widow spiders in the globe but good thing that not all of them are dangerous. Some of these spiders produce toxic venoms, which cause broad spectrum of clinical manifestations including skin lesions, neurotoxicity, cardiac toxicity and death in some occasions. In Saudi Arabia there were no much reports of black widow spider bites apart from the case series by BUCUR and his group in ALBAHA region.Settings:In 2 years period a total of 8 patients were presented to the emergency departments diagnosed to have black widow spider bites based on description by the patients.Results:100 % of the cohort were males, aged between 25-58 years. The time between bite and presentation to emergency room was one hour in average (30 min to 4 hours). 75% occured during summer season. All of them 100% had one bite only and reported the bite to be at nighttime in 75% of the times. The average pain score at presentation was 4 /10.100% of the bites were in the lower extremities and almost all progressed to have lower back pain. Three patients had gastrointestinal tract manifestation in form of abdominal cramps and nausea. One had bilateral ptosis, none of them had cardiac or pulmonary complications. The outcome was excellent in all patients and the average of hospital stay was 2.5 days (1-5).

Occurrence, reproductive rate and identification of the non-native Noble false widow spider Steatoda nobilis (Thorell, 1875) in Ireland

The noble false widow Steatoda nobilis (Thorell, 1875) has established thriving populations in urban centres throughout England and Wales since it was accidentally imported from the Canary Islands and Madeira to Britain over a century ago. In recent years, Steatoda nobilis has colonised parts of Western Europe, California, Chile and the Middle East. In Ireland, Steatoda nobilis was first recorded in 1999 from a single location in Co Wicklow. The present study examines the current range and main habitats of Steatoda nobilis in Ireland and assesses its potential as an invasive species by documenting its reproductive rate. Additionally, we present photographic material illustrating the intraspecific phenotypic variations exhibited by Steatoda nobilis to assist in correct identification of this species by the public. Our data shows that Steatoda nobilis is an extremely prolific, resilient species with distinct synanthropic affinities. This species currently occurs in at least sixteen Irish counties with the largest populations observed in the greater Dublin area, where it has become widespread in buildings and on street furniture. Steatoda nobilis seems to be currently absent from natural, undisturbed habitats such as woodlands, bogs and grassland. We suggest that due to its comparatively fast reproductive rate, long life span and year-round activity, Steatoda nobilis might have a detrimental impact on native urban-dwelling spiders.

Transcriptome Analysis to Understand the Toxicity of Latrodectus tredecimguttatus Eggs.

Latrodectus tredecimguttatus is a kind of highly venomous black widow spider, with toxicity coming from not only venomous glands but also other parts of its body as well as newborn spiderlings and eggs. Up to date, although L. tredecimguttatus eggs have been demonstrated to be rich in proteinaceous toxins, there is no systematic investigation on such active components at transcriptome level. In this study, we performed a high-throughput transcriptome sequencing of L. tredecimguttatus eggs with Illumina sequencing technology. As a result, 53,284 protein-coding unigenes were identified, of which 14,185 unigenes produced significant hits in the available databases, including 280 unigenes encoding proteins or peptides homologous to known proteinaceous toxins. GO term and KEGG pathway enrichment analyses of the 280 unigenes showed that 375 GO terms and 18 KEGG pathways were significantly enriched. Functional analysis indicated that these unigene-coded toxins have the bioactivities to degrade tissue proteins, inhibit ion channels, block neuromuscular transmission, provoke anaphylaxis, induce apoptosis and hyperalgesia, etc. No known typical proteinaceous toxins in L. tredecimguttatus venomous glands, such as latrotoxins, were identified, suggesting that the eggs have a different toxicity mechanism from that of the venom. Our present transcriptome analysis not only helps to reveal the gene expression profile and toxicity mechanism of the L. tredecimguttatus eggs, but also provides references for the further related researches.

Toxicity evaluation and initial characterization of the venom of a Colombian Latrodectus sp.

The genus Latrodectus has not been studied in Colombia even though it is medically important worldwide; there are three species for the country, this study focused on a non-identified species found in the Tatacoa Desert in the Huila Department. This research is the first approximation to the extraction, composition analysis and toxicity evaluation of the venom of a species of the genus Latrodectus in Colombia; and aims to evaluate the toxicity by the initial characterization of its venom. The venom extraction was accomplished with electrostimulation and total protein concentration was determined by the Lowry method and BCA assays from crude venom; with these methods, high protein concentration of the samples was measured. Bioassays on mice were also made to evaluate the toxicity and compare the symptoms produced by this Colombian spider to the Latrodectism Syndrome. Finally, an SDS-PAGE electrophoresis was used to separate the main components of high molecular weight from the samples and compared to a control of the venom of Latrodectus mactans to determine if the venom composition is different between these two species.

Using Global and Regional Species Distribution Models (SDM) to Infer the Invasive Stage ofLatrodectus geometricus(Araneae: Theridiidae) in the Americas

The brown widow spider, Latrodectus geometricus C. L. Koch, 1841, is a large spider of the family Theridiidae that belongs to a genus of medical interest owing to its potent neurotoxic venom, which causes severe pain in humans. In America, this alien spider has been found in virtually all countries in the region, mainly associated with human dwellings, but also in agricultural sectors. However, the invasive process and potential distribution of this invasive species across the American continent are completely unknown. In this context, using a combination of both global and regional niche models, it is possible to hypothesize the invasive phase of the species as well as the geographic space where these different phases occur. By comparing the global and regional niches of L. geometricus, we examined its invasive process and potential distribution across the American continent. This work is an innovative approach to understanding the invasion of the brown widow spider in this area and the ecological processes that underlie this invasion. In this context, the global and regional niche comparison constitutes an appropriate tool to account for the complexities of the invasive process, generating different hypotheses amenable to being tested in future studies.

Copulation with immature females increases male fitness in cannibalistic widow spiders.

Copulatory cannibalism of male 'widow' spiders (genus Latrodectus) is a model example of the extreme effects of sexual selection, particularly in L. hasselti and L. geometricus where males typically facilitate cannibalism by females and mate only once. We show that these males can increase their reproductive success by copulating with final-instar, immature females after piercing the female's exoskeleton to access her newly developed sperm storage organs. Females retain sperm through their final moult and have similar fecundity to adult-mated females. This is an adaptive male tactic because immature mating increases insemination success relative to adult mating (which predicts higher paternity) and moreover, rarely ends in cannibalism, so males can mate again. Although successful only during a brief period before the female's final moult, males may employ this tactic when they associate with final-instar females in nature. Consistent with this, one-third of L. hasselti females collected as immatures in nature were already mated. Immature mating alters sexual selection on these otherwise monogynous males, and may explain male traits allowing facultative polygyny in Latrodectus Since male cohabitation with immature females is common among invertebrates, immature mating may be a widespread, previously unrecognized mating tactic, particularly when unmated females are of high reproductive value.

Extreme developmental synchrony reduces sibling cannibalism in the black widow spider, Latrodectus hesperus

Cannibalism, intraspecific predation, is a fascinating behaviour that can serve as a model system for researchers interested in learning more about conspecific conflicts ranging from siblicide to sexual cannibalism. Cannibalism is most often studied in terms of the benefits it provides the predator, but the prevalence of such an ecologically significant behaviour is also shaped by the costs inherent in a cannibalistic attack. Perhaps most intuitively, the risk of injury when attacking a conspecific of similar or larger size has been considered, and led to the prediction that cannibalism should be most common by larger individuals among asymmetrically sized pairs. This prediction is commonplace in the cannibalism literature, and leads to the more novel hypothesis that siblicide then may be reduced to the extent that maternal investment yields developmental synchrony and size-matched siblings. Here we test these hypotheses in the western black widow spider, Latrodectus hesperus , by rearing some eggs at 4 °C warmer temperatures for 7 days, and thus experimentally creating size asymmetries between clutchmates. Our temperature manipulation was successful at speeding development (eggs reared at warmer temperatures attained their first moult 2.5 days sooner than their counterparts). This developmental asynchrony accelerated cannibalism by more than 3 days relative to control groups in which eggs and spiderlings were all reared at either consistently colder or warmer temperatures. Lastly, the mass and size of an egg were poor predictors of cannibalism in both treatments that included individuals reared at warm temperatures. In contrast, in our control group where both eggs were reared at cooler temperatures, we found that families typified by heavier and larger eggs were slower to show cannibalistic behaviour. We discuss the implications of these findings, paying particular attention to their relevance to the black widow's emerging role as an urban pest.

Ontogeny of defensive behaviors in the western black widow spider (Latrodectus hesperus)

Ontogeny of defensive behaviors in the western black widow spider (Latrodectus hesperus)

Neurotoxic manifestations of black widow spider envenomation in paediatric patients

IntroductionEnvenomation by black widow spiders manifests clinically with signs of neurotoxicity in paediatric patients. ObjectiveIdentify typical neurological signs and symptoms in paediatric patients of different ages, and describe treatment and outcomes in a paediatric hospital in northwest Mexico. Material and methodsWe reviewed 70 clinical records of patients hospitalised due to black widow spider bite between 1978 and 2014. We divided the total into 2 groups: Group 1, infants and preschool children; and Group 2, school-age children and adolescents. The demographic variables were age, sex, birthplace, place where envenomation occurred, body part(s) affected, degree of envenomation according to signs and symptoms, treatment, clinical outcome, and statistical differences. ResultsBoys accounted for 61.4% of all cases, and infants younger than one year made up 14.2%. Most patients (70%) were bitten by the spider at home; the anatomical areas most frequently affected were the legs, neck, thorax, and abdomen. The neurological signs and symptoms displayed by Group 1 were irritability, constant crying, sialorrhoea, nausea, tachycardia, arrhythmias, fatigue when walking, agitation, muscle spasms paraesthesia, tetany, seizures, and nystagmus. Signs in Group 2 included localised pain, headache, sialorrhoea, paraesthesia, profuse sweating, anxiety, muscle weakness, muscle spasms, and fine tremor. The predominant autonomic sign in Group 1 was sialorrhoea (P<.0001) and in Group 2, paraesthesia (P<.0001). Patients who received Fab antivenom treatment displayed better outcomes and shorter hospital stays than those who did not. No deaths were reported. ConclusionsThe neurological signs and symptoms caused by black widow spider bite are predominantly autonomic, and identifying them permits early diagnosis and more effective treatment.

Laboratory refugia preferences of the brown widow spider,Latrodectus geometricus(Araneae: Theridiidae)

During collecting episodes in urban southern California, brown widow spiders, Latrodectus geometricus C. L. Koch, 1841, were observed to reside most often in specific locations such as acute angles within patio furniture or on the underside of railings. In this laboratory study, we tested several variables to determine which factors brown widow females may use for web site selection. All tests were conducted with corrugated cardboard refugia in enclosed dome-shaped insect cages. Brown widows were found to significantly prefer: 1) 30o angles compared to 60o or 90o angles, 2) cavities of 75 and 100 mm depth compared to 25 or 50 mm depth, 3) cavities lined with single-faced corrugated cardboard compared to smooth surfaces, and 4) refuges that had previously housed a brown widow compared to similar but previously unoccupied refugia. These data provide unusually detailed information about microhabitat selection by an urban pest, with possible implications for the pest control industry for eradication or for home owners to avoid envenomations.

INTERVENTION PROGRAM FOR NURSING STAFF REGARDING APPROACH TO A PATIENT WITH SPIDER PHOBIA AND/OR BITE.

Spider bites are uncommon medical events, since there are limited number of spiders world-wide with fangs strong enough to pierce human skin, and most spiders bite humans only as a final defense when being crushed between skin and another object. Thus, most lesions attributed to spider bites are caused by some other etiology. The spiders that can cause medically significant bites include widow and false widow spiders (worldwide), recluse spiders (mostly North and South America), Australian funnel web spiders (eastern coastal Australia) and Phoneutria spiders (Brazil). Acute spider bites most commonly result in a solitary papule, pustule, or wheal. Systemic symptoms can accompany envenomation of widow; funnel web, and Phoneutria spiders, and less often, those of recluse spiders.

The contribution of developmental experience vs. condition to life history, trait variation and individual differences.

1. Developmental experience, for example food abundance during juvenile stages, is known to affect life history and behaviour. However, the life history and behavioural consequences of developmental experience have rarely been studied in concert. As a result, it is still unclear whether developmental experience affects behaviour through changes in life history, or independently of it. 2. The effect of developmental experience on life history and behaviour may also be masked or affected by individual condition during adulthood. Thus, it is critical to tease apart the effects of developmental experience and current individual condition on life history and behaviour. 3. In this study, we manipulated food abundance during development in the western black widow spider, Latrodectus hesperus, by rearing spiders on either a restricted or ad lib diet. We separated developmental from condition-dependent effects by assaying adult foraging behaviour (tendency to attack prey and to stay on out of the refuge following an attack) and web structure multiple times under different levels of satiation following different developmental treatments. 4. Spiders reared under food restriction matured slower and at a smaller size than spiders reared in ad lib conditions. Spiders reared on a restricted diet were more aggressive towards prey and built webs structured for prey capture, while spiders reared on an ad lib diet were less aggressive and built safer webs. Developmental treatment affected which traits were plastic as adults: restricted spiders built safer webs when their adult condition increased, while ad lib spiders reduced their aggression when their adult condition increased. The amount of individual variation in behaviour and web structure varied with developmental treatment. Spiders reared on a restricted diet exhibited consistent variation in all aspects of foraging behaviour and web structure, while spiders reared on an ad lib diet exhibited consistent individual variation in aggression and web weight only. 5. Developmental experience affected the average life history, behaviour and web structure of spiders, but also shaped the amount of phenotypic variation observed among individuals. Surprisingly, developmental experience also determined the particular way in which individuals plastically adjusted their behaviour and web structure to changes in adult condition.

Linking consistent individual differences in web structure and behavior in black widow spiders

Individuals may vary consistently in their architectural makeup of the constructions they build, which might have tremendous implications for their ecology and fitness. In particular, the relationship between individual differences in architectural constructions and behavior (i.e., animal personalities) is largely unexplored. Individual black widow spiders, Latrodectus hesperus, build a 3D cobweb made up of distinctive components serving to support foraging (gumfooted lines) or antipredator protection (structural lines). To explore the relationship between individual differences in behavior and architectural constructions, we quantified 1) the level of consistent individual variation in several elements of web structure and 2) the level of consistent individual variation in foraging behavior and its relationship with web structure. We controlled for condition-dependent or environmental effects by satiating all spiders prior to assays and maintaining them in standardized conditions. Spiders exhibited consistent differences in the number of gumfooted lines they built for capturing preys and overall web weight, but not in the number of structural lines. Individuals also varied consistently in their tendency to attack a prey cue, despite all spiders being satiated. Finally, spiders producing more gumfooted lines exhibited a higher tendency to attack the prey cue. Our results suggest that the architectural constructions may impact the expression of individual behavioral differences (or animal personalities) and suggest that individual behavior and extended phenotype may be part of alternative foraging strategies in L. hesperus.

Effects of Gene Duplication, Positive Selection, and Shifts in Gene Expression on the Evolution of the Venom Gland Transcriptome in Widow Spiders.

Gene duplication and positive selection can be important determinants of the evolution of venom, a protein-rich secretion used in prey capture and defense. In a typical model of venom evolution, gene duplicates switch to venom gland expression and change function under the action of positive selection, which together with further duplication produces large gene families encoding diverse toxins. Although these processes have been demonstrated for individual toxin families, high-throughput multitissue sequencing of closely related venomous species can provide insights into evolutionary dynamics at the scale of the entire venom gland transcriptome. By assembling and analyzing multitissue transcriptomes from the Western black widow spider and two closely related species with distinct venom toxicity phenotypes, we do not find that gene duplication and duplicate retention is greater in gene families with venom gland biased expression in comparison with broadly expressed families. Positive selection has acted on some venom toxin families, but does not appear to be in excess for families with venom gland biased expression. Moreover, we find 309 distinct gene families that have single transcripts with venom gland biased expression, suggesting that the switching of genes to venom gland expression in numerous unrelated gene families has been a dominant mode of evolution. We also find ample variation in protein sequences of venom gland–specific transcripts, lineage-specific family sizes, and ortholog expression among species. This variation might contribute to the variable venom toxicity of these species.

Aposematic signals in North American black widows are more conspicuous to predators than to prey

Abstract The iconic red hourglass of the black widow spiders (genus Latrodectus) is traditionally considered an aposematic signal, yet experimental evidence is lacking. Here, we present data that suggest that black widow coloration may have evolved to be an aposematic signal that is more conspicuous to their vertebrate predators than to their insect prey. In choice experiments with wild birds, we found that the red-and-black coloration deters potential predators: Wild birds were ~3 times less likely to attack a black widow model with an hourglass than one without. Using visual-system appropriate models, we also found that a black widow’s red-and-black color combo is more apparent to a typical bird than a typical insect. Additionally, an ancestral reconstruction reveals that red dorsal coloration is ancestral in black widows and that at some point some North American widows lost their red dorsal coloration. Behaviorally, differences in red dorsal coloration between 2 North American species are accompanied by differences in microhabitat that affects how often a bird will view a black widow’s dorsal region. All observations are consistent with a cost–benefit trade-off of being more conspicuous to predators than to prey. We suggest that limiting detection by prey may help explain why red and black aposematic signals occur frequently in nature.

Snake and Spider Toxins Induce a Rapid Recovery of Function of Botulinum Neurotoxin Paralysed Neuromuscular Junction.

Botulinum neurotoxins (BoNTs) and some animal neurotoxins (β-Bungarotoxin, β-Btx, from elapid snakes and α-Latrotoxin, α-Ltx, from black widow spiders) are pre-synaptic neurotoxins that paralyse motor axon terminals with similar clinical outcomes in patients. However, their mechanism of action is different, leading to a largely-different duration of neuromuscular junction (NMJ) blockade. BoNTs induce a long-lasting paralysis without nerve terminal degeneration acting via proteolytic cleavage of SNARE proteins, whereas animal neurotoxins cause an acute and complete degeneration of motor axon terminals, followed by a rapid recovery. In this study, the injection of animal neurotoxins in mice muscles previously paralyzed by BoNT/A or /B accelerates the recovery of neurotransmission, as assessed by electrophysiology and morphological analysis. This result provides a proof of principle that, by causing the complete degeneration, reabsorption, and regeneration of a paralysed nerve terminal, one could favour the recovery of function of a biochemically- or genetically-altered motor axon terminal. These observations might be relevant to dying-back neuropathies, where pathological changes first occur at the neuromuscular junction and then progress proximally toward the cell body.

Recent Advances in Research on Widow Spider Venoms and Toxins.

Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the α-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species.

Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey.

Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. This paper describes a novel and promising source of noninvasive spider and insect DNA from spider webs. Using black widow spiders (Latrodectus spp.) fed with house crickets (Acheta domesticus), we successfully extracted, amplified, and sequenced mitochondrial DNA from spider web samples that identified both spider and prey to species. Detectability of spider DNA did not differ between assays with amplicon sizes from 135 to 497 base pairs. Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. Spider web DNA as a proof-of-concept may open doors to other practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments.

Alteration of tubuliform silk gland cytoarchitecture with the reproductive cycle of the Western black widow spider, Latrodectus hesperus

AbstractThe protein synthetic and secretory activity of spider tubuliform glands is known to be coordinated with the reproductive stage of the spider. For spiders that produce multiple egg cases, such as the black widow Latrodectus hesperus, this means that the cells that make up the tubuliform gland cycle from minimal to maximal silk protein synthesis and exocytosis as the spider transitions from early vitellogenesis to a gravid state and back. The impact of these transitions on the cells that form the tubuliform gland has yet to be characterized. The entire tubuliform gland undergoes an elastic deformation, doubling in size in response to the accumulation and depletion of egg case silk proteins within its lumen. Similarly, the diversity and organization of organelles within the cytoplasm of the secretory epithelial cells that make up the wall of the tubuliform gland change with the reproductive stage of the spider. Progression of a spider from early to late vitellogenesis is accompanied by decondensed nucleoli and distention of the rough endoplasmic reticulum, markers of protein synthetic activity. The presumed silk proteins that fill the lumen of the tubuliform gland of a gravid spider include a fibrous matrix with homogeneous spherical inclusions. These components are also present within the cytoplasm of the cell; however, only the fibrous material appears to be enclosed by membranous organelles. Transition of the tubuliform gland from peak silk synthesis back to a quiescent state is marked by the appearance of multivesicular bodies and organelles resembling phagophores and autophagosomes, suggestive of a role for autophagy in the process of recovery. The reproducible cellular dynamics of the tubuliform silk gland of the black widow spider makes it a potential model system for study of the regulation of silk gene expression, endomembrane transport, and exocytosis of silk proteins and autophagy.