Study species: Cyclosa mulmeinensis
The effects of wind on microstructures of major ampullate silks produced by Cyclosa mulmeinensis
Previous studies show that spider major ampullate (MA) silk is composed of crystal and amorphous secondary structures. The crystal structure is majorly encoded by Major Ampullate Spidroin 1 (MaSp1) gene and it provides the strength and toughness of a thread. The amorphous structure is encoded by Major Ampullate Spidroin 2 (MaSp2) gene and it provide the extensibility of a thread. In the production process of a MA silk, a series of post secretion processing such as ion exchange, dehydration and rearrangement of secondary structures occurs after the spidroin protein is secreted in silk glands. Such post secretion processing plays an important role in achieving the superior mechanical properties of MA silks. The properties of spider silk and web are affected by various biotic and abiotic factors. Such phenomenon implies that spiders may adjust post secretion processing then alter the mechanical properties of MA silks. In this study, I subjected Cyclosa mulmeinensis spiders to different wind disturbance level in the laboratory and then compared the microstructure characters of spiders' MA silk. I used Fourier transform infrared spectroscopy (FTIR) to measured the level of crystallization and I found higher ratio of crystallization in MA silk produced by C. mulmeinensis receiving wind disturbance. Previous studies showed that when MA silk was subjected to supercontraction the effects of post secretion processing on silk can be eliminated. Therefore, I compared the mechanical properties of normal MA silks to those of silks under saturated humidity condition (to induce supercontraction) to estimate whether C. mulmeinensis spiders were able to adjust their mechanical properties of MA silks without altering the chemical properties. The results showed that most of tensile properties of supercontracted silks were not significantly different, except for extensibility. To determine the degree of alignment and geometry as well as distribution pattern of secondary structures of MA silk, X-ray diffraction will be applied in the future works.
Updated: Mar-10-2014 01:22:51 (Taiwan, GMT+08:00).