Project description:Spider silk proteins are synthesized in the silk-producing glands, where the spidroins are produced, stored and processed into a solid fiber from a crystalline liquid solution. Despite great interest in the spider silk properties, that make this material suitable for biomedical and biotechnological applications, the mechanism of formation and spinning of the silk fibers has not been fully elucidated; and no combination of proteomic and transcriptomic study has been carried out so far in the spider silk-producing glands. Nephila clavipes is an attractive orb-web spider to investigate the spinning process of silk production, given the properties of strength, elasticity and biocompatibility of their silk fibers. Thus, considering that the combination of proteomic and transcriptomic analysis may reveal an extensive repertoire of novel proteins involved in the silk spinning process, and in order to facilitate and enable proteomics in this non-model organism, the current study aims to construct a high quality reference mRNA-derived protein database that could be used to identify tissue specific expression patterns in spider silk glands. Next-generation sequencing has offered a powerful and cost-efficient technique for the generation of transcriptomic datasets in non-model species using diverse platforms such as the Illumina HiSeq, Roche 454, Pacific Biosystems, and Applied Biosystems SOLiD; In the current study, the Illumina HiSeq 2000 platform will be used to generate a N. clavipes spider silk glands transcriptome-based protein database. The transcriptome data generated in this study will provide a comprehensive and valuable genomic resource for future research of the group of spider silk-producing glands, in order to improve our understanding of the overall mechanism of action involved in production, secretion, storage, transport, protection and conformational changes of spidroins during the spinning process, and prey capture; and the results may be relevant for scientists in material Science, biology, biochemistry, and environmental scientists.
Project description:The golden orb-weaver spider Nephila clavipes, known for its sexual size dimorphism, is abundant and widespread in the New World. The first annotated genome of orb-weaver spiders, exploring N. clavipes, has recently been reported. The study, focused primarily on the diversity of silk specific genes, shed light into the complex evolutionary history of spiders. Furthermore, a robust transcriptome analysis provided a massive resource for N. clavipes RNA survey. Here, I present evidence of viral sequences corresponding to the first 10 extant virus species associated to N. clavipes and indeed, nephilids. The putatively new species are linked to ssRNA positive-strand viruses, such as Picornavirales, and to ssRNA negative-strand and dsRNA viruses. In addition, I detected sequence data of new strains of two recently reported arthropod viruses, which complemented and extended the corresponding sequence references. The identified viruses appear to be complete, potentially functional, and presenting the typical architecture and consistent viral domains. The intrinsic nature of the detected sequences and their absence in the recently generated genome assembly, suggest that they correspond to bona fide RNA virus sequences. The available RNA data allowed for the first time to address a tissue/organ specific analysis of virus loads/presence in spiders, suggesting a complex spatial and differential distribution of the tentative viruses, encompassing the spider brain and also silk and venom glands. Until recently, the virus landscape associated to spiders remained elusive. The discovered viruses described here provide only a fragmented glimpse of the potential magnitude of the Aranea virosphere. Future studies should focus not only on complementing and expanding these findings, but also on addressing the potential ecological role of these viruses, which might influence the biology of these outstanding arthropod species.
Project description:Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous comparison of tissue-specific RNAseq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ~5% of these transcripts encode spidroins and the remaining predicted genes presumably encode other proteins associated with silk production. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands, and detect 16 SST encoded proteins in major ampullate silk fibers. The observed proteins include known silk-related proteins, but most are uncharacterized, with no annotation. These unannotated proteins likely include novel silk associated proteins. Major ampullate and minor ampullate glands have the highest overlap of identified proteins, consistent with their shared, distinctive ampullate shape and the overlapping functions of major ampullate and minor ampullate silks. Our study substantiates and prioritizes predictions from differential expression analysis of spider silk gland transcriptomes.
Project description:Spider silk research has largely focused on spidroins, proteins that are the primary components of spider silk fibers. Although a number of spidroins have been characterized, other types of proteins associated with silk synthesis are virtually unknown. Previous comparison of tissue-specific RNAseq libraries identified 647 predicted genes that were differentially expressed in silk glands of the Western black widow, Latrodectus hesperus. Only ~5% of these transcripts encode spidroins and the remaining predicted genes presumably encode other proteins associated with silk production. Here, we used proteomic analysis of multiple silk glands and dragline silk fiber to investigate the translation of the differentially expressed genes. We find 48 proteins encoded by the differentially expressed transcripts in L. hesperus major ampullate, minor ampullate, and tubuliform silk glands, and detect 16 SST encoded proteins in major ampullate silk fibers. The observed proteins include known silk-related proteins, but most are uncharacterized, with no annotation. These unannotated proteins likely include novel silk associated proteins. Major ampullate and minor ampullate glands have the highest overlap of identified proteins, consistent with their shared, distinctive ampullate shape and the overlapping functions of major ampullate and minor ampullate silks. Our study substantiates and prioritizes predictions from differential expression analysis of spider silk gland transcriptomes.
Project description:Spiders are a highly diverse group of arthropods that occur in most habitats on land. Notably, spiders have significant ecological impact as predators because of their extraordinary prey capture adaptations, venom and silk. Spider venom is among the most heterogeneous animal venoms and has pharmacological applications, while spider silk is characterized by great toughness with potential for biomaterial application. We describe the genome sequences of two spiders representing two major taxonomic groups, the social velvet spider Stegodyphus mimosarum (Araneomorphae), and the Brazilian white-knee tarantula Acanthoscurria geniculata (Mygalomorphae). We annotate genes using a combination of transcriptomic and in-depth proteomic analyses. The genomes are large (2.6 Gb and 6 Gb, respectively) with short exons and long introns and approximately 50% repeats, reminiscent of typical mammalian genomes. Phylogenetic analyses show that spiders and ticks are sister groups outgrouped by mites, and phylogenetic dating using a molecular clock dates separation of velvet spider and tarantula at 270 my. Based on the genomes and proteomes, we characterize the genetic basis of venom and silk production of both species in detail. Venom protein composition differs markedly between the two spiders, with lipases as the most abundant protein in the velvet spider and present only at low concentration in tarantula. Venom in both spiders contains proteolytic enzymes, and our analyses suggest that these enzymes target and process precursor peptides that subsequently mediate the toxic effects of venom. Complete analysis of silk genes reveal a diverse suite of silk proteins in the velvet spider including novel types of spidroins, and dynamic evolution of major ampullate spidroin genes, whereas silk protein diversity in tarantula is far less complex. The difference in silk proteins between species is consistent with a more complex silk gland morpholgy and use of three-dimentional capture webs consisting of multiple silk types in aranomorph spiders.
Project description:Some ichneumonid wasps induce modifications in the web building behavior of their spider hosts to produce resistant "cocoon" webs. These structures hold and protect the wasp's cocoon during pupa development. The mechanism responsible for host manipulation probably involves the inoculation of psychotropic chemicals by the parasitoid larva during a specific developmental period. Recent studies indicate that some spiders build cocoon webs similar to those normally built immediately before ecdysis, suggesting that this substance might be a molting hormone or a precursor chemical of this hormone. Here, we report that Cyclosa spider species exhibiting modified behavior presented higher 20-OH-ecdysone levels than parasitized spiders acting normally or unparasitized individuals. We suggest that the lack of control that spiders have when constructing modified webs can be triggered by anachronic activation of ecdysis.