Presentation Type

Oral Presentation

Keywords

Biology, temperature, tensile strength, spider silk, Araneus gemmoides

Department

Biology

Major

Biology and Music

Abstract

Temperature ranges between day and night in southern California can be as great as 30°C and may influence vital functioning of ectothermic organisms. Arachnids produce silks from a pair of spinnerets in their abdomen and rely on variance in protein composition to make different types of silks. Temperature may influence tensile strength of filaments. We tested the effects of temperature on tensile strength of dragline silk of five specimens of Araneus gemmoides (orb-weaver) which were collected from Malibu Creek State Park in the Santa Monica Mountains of southern California, under five temperature conditions. Each specimen was placed in a 0.0283 m3 mesh enclosure and allowed 24- hours to acclimate to a temperature increase of 5°C. Photoperiods were set at 12-hour intervals for light and dark to simulate natural conditions. We then removed a single thread of dragline silk and measured tensile strength using an mechanical testing device (Instron 5544-A). We found that dragline silk is typically composed of two monofilaments wrapped together at points and thus quantified transverse area of both monofilaments. This structure may explain the reason why variability around mean values was similar for the plot of stress at break versus temperature. After running a one way ANOVA statistical analysis for repeated measures, we found that at 10°C both the Young’s Modulus and stress at break were significantly greater (P<0.05) than values obtained at 15°C. Additionally, mass of spider seems to correlate with greater tensile strength (R2=0.52) suggesting that larger spiders produce stronger silk. Currently, biomaterial engineers are attempting to exploit the incredible properties of silk for production of fiber materials. Therefore, understanding how Araneus gemmoides is influenced by temperature offers insight into the optimal temperature for harvesting silk.

Faculty Mentor

Stephen Davis

Funding Source or Research Program

Keck Scholars Program

Presentation Session

Session E

Location

Rockwell Academic Center 178

Start Date

21-3-2014 3:30 PM

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Mar 21st, 3:30 PM

Influence of Temperature on the Tensile Strength of Spider Silk (Araneus gemmoides)

Rockwell Academic Center 178

Temperature ranges between day and night in southern California can be as great as 30°C and may influence vital functioning of ectothermic organisms. Arachnids produce silks from a pair of spinnerets in their abdomen and rely on variance in protein composition to make different types of silks. Temperature may influence tensile strength of filaments. We tested the effects of temperature on tensile strength of dragline silk of five specimens of Araneus gemmoides (orb-weaver) which were collected from Malibu Creek State Park in the Santa Monica Mountains of southern California, under five temperature conditions. Each specimen was placed in a 0.0283 m3 mesh enclosure and allowed 24- hours to acclimate to a temperature increase of 5°C. Photoperiods were set at 12-hour intervals for light and dark to simulate natural conditions. We then removed a single thread of dragline silk and measured tensile strength using an mechanical testing device (Instron 5544-A). We found that dragline silk is typically composed of two monofilaments wrapped together at points and thus quantified transverse area of both monofilaments. This structure may explain the reason why variability around mean values was similar for the plot of stress at break versus temperature. After running a one way ANOVA statistical analysis for repeated measures, we found that at 10°C both the Young’s Modulus and stress at break were significantly greater (P<0.05) than values obtained at 15°C. Additionally, mass of spider seems to correlate with greater tensile strength (R2=0.52) suggesting that larger spiders produce stronger silk. Currently, biomaterial engineers are attempting to exploit the incredible properties of silk for production of fiber materials. Therefore, understanding how Araneus gemmoides is influenced by temperature offers insight into the optimal temperature for harvesting silk.