Argiope aurantia viscous silk. (A) Glue droplets suspended on the supporting axial thread; (B) a single droplet exposed to increasing humidity, demonstrating the hygroscopic properties; and (C) a flattened droplet showing the pair of supporting axial fibers (AF), outer aqueous layer (AL) and the inner glycoprotein core (GC).
Video of a spider glue droplet stretching after contact with a metal probe.
Droplet of spider glue stretching after contact with a metal probe.
Oxford Nanopore technology allows resolution of ultra-repetitive genes using a long-read sequencing platform.
All spiders use silk at some point during their lifetimes and some spiders use a suite of different silks to accomplish a variety of tasks. During my Ph.D. and postdoctoral fellowship at the US Army Research Laboratory, my research focused on the material and molecular properties of aggregate spider glue, a modified type of silk. Orb weaving spiders and their relatives cover their capture threads with sticky droplets of this glue that functions to retain prey in the web until a spider can capture them.
We recently discovered the complete genetic sequences that encode for two spider glue proteins. These massive, repetitive sequences were obtained using Oxford Nanopore's MinION combined with Illumina sequencing for error correction. I am interested in bridging the genetic backbone with the material phenotype of the final glue protein, as well as how glue properties relate to web ecology.
The effects of varying humidity on the glue droplets’ properties are well known, causing stiffer or softer glue with differing abilities to absorb energy of struggling prey. My research has focused on expanding the knowledge of how environmental variables affect the glue’s adhesive capabilities, including how temperature works in conjunction with humidity to stabilize the glue as conditions shift on a daily basis, and how ultraviolet radiation affects the glue of webs built in full-sun habitats differently than that of webs built in deep shade (cover of The Journal of Experimental Biology, 2015). I have also explored how spiders differentially deposit glue across a web’s top-bottom and inner-outer threads, revealing how they adaptively place the glue within their webs.
I have recently joined the BurnsLab, where I am applying the skills I acquired sequencing spider silk genes to whole genome sequencing of another arachnid, the facultatively parthenogenetic, mixed ploidy Japanese harvestman Leiobunum manubriatum. Parthenogenic organisms often have highly repetitive genomes, and Oxford Nanopore will aid in resolving difficult genomic regions during assembly. We recently traveled to Japan (August 2019) to collect specimens and extract DNA in preparation for the next round of sequencing.