Study Focuses on Spider Silk, Venom
By Edwin L. Aguirre
Sandra Correa has been fascinated with spiders since childhood. Unlike many people who have great fear of spiders, the master’s degree candidate in biology has no qualms handling or even caressing these eight-legged creatures.
“As a youngster, I always dressed up as Spiderwoman for Halloween parties,” says Correa, who has a venomous tarantula as a pet and collected dozens of black widows during a recent trip to California.
Correa’s current research involves investigating the evolutionary relationship between spider silks and the silk-like venom of the spitting spider, Scytodes thoracica. It’s called a spitting spider because it ejects a poisonous sticky silken substance to capture its prey.
For her work, Correa was awarded two one-year $1,000 grants by the Sigma Xi Scientific Research Society and the Society for Integrative and Comparative Biology (SCIB). Sigma Xi’s program promotes scientific excellence and achievement in the sciences and engineering through hands-on learning while the SICB provides supplemental awards to graduate students in support of their research in the fields of integrative and comparative biology.
“These are prestigious national awards, of which only so many are given each year,” says Biology Asst. Prof. Jessica Garb, who is an expert in spider silks
and is Correa’s thesis adviser.
Tracing the Silk Genes’ Evolutionary History
“All spiders produce silks composed of proteins known as ‘spidroins,’ which are secreted from specialized abdominal glands,” says Correa. “Unlike all other spiders, spitting spiders eject a wad of adhesive glue from their fangs onto their prey. This ejected material contains long, fibrous strands with structural similarities to abdominal spider silk, which led scientists to believe that venom from spitting spiders may also be composed of spidroins.”
She says the composition of the venom has not yet been characterized in detail, and if her hypothesis is correct — that the venom is indeed composed of spidroins — it would suggest that something extraordinary happened during the evolutionary history of spitting spiders that caused spider silk genes to be co-opted for venom gland expression.
Correa will test her hypothesis using DNA sequencing, protein analyses and bioinformatics to characterize the major protein products of the silk and venom as well as determine the mechanical properties of the silk itself.
“Spider silks are renowned for their outstanding mechanical properties, even surpassing steel and Kevlar in toughness,” she says. “Studying silk proteins will contribute to a better understanding of the genetic properties of spider silks, including their strength, elasticity and toughness, and help biotechnologists develop a variety of new materials for industrial, medical and military applications. These include lightweight, super-strong body armor, biodegradable surgical sutures and components for medical devices.”
A native of Colombia, Correa received a bachelor’s degree in biotechnology (with a minor in math) from UMass Lowell in 2010. After she obtains her master’s degree, she plans to pursue her Ph.D. in ecology, evolution and organismal biology this fall at the University of California, Riverside.