Variation in the Chemical Composition of Orb Webs Built by the Spider Nephila Clavipes (Araneae, Tetragnathidae)

Abstract

The adhesive droplets in the orb webs of araneoid spiders contain, among other constituents, an aqueous solution of organic low-molecular-weight compounds. The chemical composition of this solution has been investigated for pooled web collections from several species, but little is known about how the composition might vary among individuals or among environments. To begin addressing these questions, we analyzed serial collections of orb webs spun by individual juvenile Nephila clavipes from three different populations held first under field conditions and then under laboratory conditions.Our results indicate that the composition of the organic low-molecular-weight solution is not fixed. We found significant differences in the droplet composition among individuals, among populations, and with the transfer of spiders to laboratory conditions. The possible origins and consequences of these differences are discussed.

The Nephila clavipes genome highlights the diversity of spider silk genes and their complex expression

“…Variants were hard-filtered to include only SNPs meeting minimum quality (20) and depth (20) thresholds and then subdivided into 14 categories (genome, noncoding, genes (gold set), CDS, mRNAs, 3′ UTRs, 5′ UTRs, exons, introns, gold N termini, gold C termini, spidroin genes, spidroin N termini, spidroin C termini) using VCFtools 93 . SNPs were counted for each category, and polymorphic levels were assessed on the basis of heterozygosity, number of segregating sites, SNP rate, and Watterson's estimator of theta (θ W ) 94 .…”

“…The silk classes of a typical 'gluey silk' orb-weaver (Araneoidea) female include (i) major ampullate silk, which exhibits great tensile strength and is employed in draglines, bridgelines, and web radii 11,12 ; (ii) minor ampullate silk, used for inelastic temporary spirals during web building 11,12 ; (iii) cement-like piriform silk that bonds fibers together and to other substrates 13,14 ; (iv) strong, yet flexible aciniform silk used for prey wrapping and egg case insulation 15 ; (v) tubuliform and cylindriform silk that constitutes the tough outer layer of egg cases 16,17 ; (vi) flagelliform silk that exhibits unparalleled extensibility and is used in the capture spiral 18,19 ; and (vii) the viscous and sticky aggregate silk that aids in prey capture [20][21][22][23][24] . Many spider species produce just a subset of these silk classes, and some produce yet other silk types, including cribellate silk 25 .…”

Environmental response and adaptation of glycoprotein glue within the droplets of viscous prey capture threads from araneoid spider orb-webs

“…When these coated fibers first merge to form a thread, their aqueous covering forms a continuous cylinder. Salts and as many as 12 low molecular weight compounds, such as GABamide, glycine and choline (Edmonds and Vollrath, 1992;Fisher and Brander, 1960;Higgins et al, 2001;Townley et al, 1991;Tillinghast and Christenson, 1984;Townley et al, 2006;Vollrath et al, 1990) make this coating hygroscopic, causing it to rapidly absorb atmospheric moisture and be reconfigured by Rayleigh instability into droplets (Edmonds and Vollrath, 1992). Within each droplet, ASG1 and ASG2 glycoproteins condense into a viscoelastic core that is both adhesive and extensible (Choresh et al, 2009;Tillinghast et al, 1993;Townley et al, 2006), properties that combine to generate an effective adhesive delivery system (Opell and Hendricks, 2007;Opell and Hendricks, 2009).…”

N-Acetyltaurine dissimilated via taurine by Delftia acidovorans NAT

“…1) is secreted by orb spiders in molar concentrations in the viscid droplets applied to their webs as one component of the complex mechanism to catch prey (Vollrath et al 1990;Higgins et al 2001); the compound is thus widespread in Nature. The compound is usually the major, low molecular-weight species present on these webs, and it is one of the many derivatives of taurine (2-aminoethanesulfonate) found in Nature (Huxtable 1992).…”