Research of the mechanical property, gene expression, and behaviroal ecology of spider silk. (1/3) (NSC 91-2311-B-029-006)

Abstract

Spider silks have various function, composition and structure and are produced by different spinning glands. Dragline silk produced by ampullate glands has greatest strength than other types of silks thus have been the focus of most studies. Previous studies had demonstrated that the amino acid sequences translated from dragline genes of orb-weaving spiders exhibited many consensus repeats and formed specific structures. However, there are few studies on dragline silks produced by other guilds of spiders such as space web builders and wandering spiders. In this study, the relationship between web-related predation behaviors and silk protein structures is studied by examining amino acid sequences from dragline genes amplified from different spider guilds. Currently, four dragline gene partial sequences from the orb-weaving Nephila pipipes and Octonoba varians and one form the space web builder Psechrus sinensis are obtained. Among these partial sequences, the non-repetitive portions are highly similar to each other and are in accordance with the non-repetitive regions of published dragline genes. The space web builder Psechrus sinensis is phylogenetically related to the wandering Dolomedes, however, its dragline gene non-repetitive portion is more similar to that of orb-weavers. The extreme similarity in dragline gene non-repetitive portions of web builders from differ clades show that this sequence exhibits important function. In addition, two partial dragline gene sequences are amplified from a single individual of N. pilipes by same PCR primers. These two sequences are almost identical in non-repetitive portion but are different in repetitive portion. Both sequences exhibit GGX, GA and Poly-A motifs but the numbers and arrangement pattern differ. This result suggested that dragline silk of N. pilipes may have multiple alleles and operate like a multiple gene system. Previous behavior studies showed that diet variation might induce a significant change in amino acid composition of dragline. Field censes also demonstrated that different populations of N. pilipes in Taiwan had different prey composition and their dragline amino acid composition also differed significantly. These results suggest that diet variation may cause differential expression of dragline alleles thus generates silk of different amino acid composition.

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Updated: Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).