Abstract
Most spiders spin multiple types of silk, including silks for reproduction, prey capture, and draglines. Spiders are a megadiverse group and the majority of spider silks remain uncharacterized. For example, nothing is known about the silk molecules of Tengella perfuga, a spider that spins sheet webs lined with cribellar silk. Cribellar silk is a type of adhesive capture thread composed of numerous fibrils that originate from a specialized plate-like spinning organ called the cribellum. The predominant components of spider silks are spidroins, members of a protein family synthesized in silk glands. Here, we use silk gland RNA-Seq and cDNA libraries to infer T. perfuga silks at the protein level. We show that T. perfuga spiders express 13 silk transcripts representing at least five categories of spider silk proteins (spidroins). One category is a candidate for cribellar silk and is thus named cribellar spidroin (CrSp). Studies of ontogenetic changes in web construction and spigot morphology in T. perfuga have documented that after sexual maturation, T. perfuga females continue to make capture webs but males halt web maintenance and cease spinning cribellar silk. Consistent with these observations, our candidate CrSp was expressed only in females. The other four spidroin categories correspond to paralogs of aciniform, ampullate, pyriform, and tubuliform spidroins. These spidroins are associated with egg sac and web construction. Except for the tubuliform spidroin, the spidroins from T. perfuga contain novel combinations of amino acid sequence motifs that have not been observed before in these spidroin types. Characterization of T. perfuga silk genes, particularly CrSp, expand the diversity of the spidroin family and inspire new structure/function hypotheses.
Highlights
Spiders are widely distributed and abundant in most terrestrial communities, and their evolutionary success is partly associated with diversification of silk usage [1,2,3]
These spidroin contigs are associated with ampullate, aciniform, pyriform, tubuliform, and cribellate silk glands (S2 Table)
Maximum likelihood analyses of the C- and N-terminal region sequences show that T. perfuga ampullate (AmSp), aciniform (AcSp), pyriform (PySp), and tubuliform (TuSp) sequences group together with spidroins of the same respective type from the comparison species (Fig 1 and S1 Fig)
Summary
Spiders are widely distributed and abundant in most terrestrial communities, and their evolutionary success is partly associated with diversification of silk usage [1,2,3]. Most of the studies on spider silk use and molecular composition have been heavily focused on cobweb and ecribellate orb-web weaving spiders. These spiders have several silk types, including aciniform, major ampullate, pyriform, and tubuliform silks. Cribellate spiders have one pair of silk spinnerets modified into a cribellum, a plate-like spinning organ that is dotted with numerous miniscule spigots. From this dense field of spigots, thousands of ultrafine fibrils are produced; this silk type is referred to as cribellar silk [9,10,11,12]. Cribellar fibrils work together to stretch up to 500% their original length [17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
