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Unformatted text preview: 1053 Orb-weaving spiders construct webs to catch prey and this trait is easy to quantify, therefore they have been a popular model to study how foragers respond to various foraging conditions (Eberhard, 1990; Craig, 1992; Heiling and Herberstein, 1999, 2000). In addition to changes in foraging site (Enders, 1973, 1977; Rypstra, 1981; Smallwood, 1993; Chmiel et al., 2000), web structures (Higgins and Buskirk, 1992; Pasquet et al., 1994; Sandoval, 1994; Sherman, 1994; Blackledge, 1998; Heiling and Herberstein, 2000; Tso, 1999; Watanabe, 1999; Venner et al., 2000) and silk output (Higgins and Buskirk, 1992; Sherman, 1994; Tso, 1999), more and more studies have demonstrated that orb-weaving spiders may also alter various properties of the silk. Madsen et al. (1999) suggested that malnutrition would decrease the amount of available amino acids of spiders, which might affect silk chemistry and mechanical properties. Higgins et al. (2001) reported that the low molecular weight (LMW) organic compounds of adhesive spirals of Nephila clavipes changed significantly when spiders were moved from field to laboratory. Higgins et al. (2001) suggested that diet variations might have induced the production of different LMW organic compounds by aggregate glands. Craig et al. (1996) also demonstrated that Nephila clavipes could adjust silk pigment production according to the intensity and spectral composition of its light environment. In a field survey and manipulative study, Craig et al. (2000) showed that Argiope spiders may alter the properties of their dragline silk according to different prey intakes. In their study, dragline silks obtained from A. argentata of 13 Caribbean islands exhibited an inverse relationship between percentages of glycine and serine. Moreover, when the diet of A. keyserlingi was changed from fly to cricket, the composition of serine changed significantly. Results of Craig et al. (2000) suggested that in addition to changes of web structure and silk quantity, orb-weaving spiders might also change silk protein in response to prey variation. Recent research has revealed that dragline silks are composed of the products of at least two genes: major ampullate spidroin 1 ( MaSp1 ; Xu and Lewis, 1990) and major ampullate spidroin 2 ( MaSp2 ; Hinman and Lewis, 1992). The MaSp1 protein exhibits poly (GA), poly (A) and poly (GGX) motifs (G, glycine; A, alanine; X, any amino acid; Xu and Lewis, 1990). Among these motifs, poly (GA) and poly (A) are major components of the β-sheet crystal structure (Gosline The Journal of Experimental Biology 208, 1053-1061 Published by The Company of Biologists 2005 doi:10.1242/jeb.01437 Recent studies have demonstrated that orb-weaving spiders may alter web structures, foraging localities or silk output in response to prey variations. In this study we conducted field surveys and food manipulations to examine whether orb-weaving spiders may also adjust the protein of silk to prey variations. A comparison of dragline silks collected from nine giant wood spider...
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This note was uploaded on 01/27/2012 for the course ECOLOGY 300 taught by Professor Zumdahli during the Spring '11 term at St. Mary NE.
- Spring '11