Meeting Abstract
Spiders (Araneae) are exceptional among silk producing arthropods for the diversity of silk types and functions found within and among species. Functionally and mechanically distinct silk fibers are composed primarily of unique proteins synthesized in specialized abdominal glands. Araneoid spiders (a mega-diverse clade that include orb-web, sheet-web, and cobweb weavers) possess up to seven gland types, each producing silk fibers or glues with distinctive mechanical properties that correspond to a particular function. Almost all molecular studies of spider silks have focused on members of the gene family that encode the fibers’ primary structural proteins – spidroins. Each of the spidroin paralogs characterized thus far appears to have gland-specific expression. Recently, high throughput sequencing of genes expressed in the silk glands of the Western black widow identified ~650 transcripts that were significantly more abundant in silk glands than other tissues, suggesting a far more complex silk protein system than previously recognized. Here we describe gene expression patterns of all seven of the functionally differentiated silk gland types in three species of cobweb weaving spiders including the Western black widow. GO term analysis of differentially expressed transcripts identified similar functions enriched in each of the differentiated gland types in all three species, including oxidation-reduction, extracellular exportation, and lipases. Intriguingly, the identity of these transcripts in each of the individual gland types is unique – e.g. different paralogs are expressed in each of the gland types within a single species. Thus, silk glands types share basic functions, but have diverged in paralog expression, mirroring the pattern found for spidroin expression.
