Guehrs K-H, Schlott B, Grosse F, Weisshart K
Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstrasse 11, D-07745 Jena, Germany.
Insect Mol Biol. 2008 Sep;17(5):553-64. doi: 10.1111/j.1365-2583.2008.00826.x.
The silk formed in the major ampullate (MA) gland of the orb weaving spider Nephila clavipes is composed of two silk fibroins, which are called major ampullate spidroins 1 (MaSp1) and 2 (MaSp2). Analysis of proteolytic peptides and reactivity to spidroin type specific antibodies indicated that MaSp2 constituted only a minor part in the spinning dope as well as in the spun filaments. Upon starvation, a change in the silk's characteristic features was observed that was concomitant of a decrease in the contribution of MaSp2. The silk became less elastic and stiffer, which will better tailor its usability for the safety line, albeit at the expense of its employment as the web frame threads. In addition, since MaSp2 production requires greater ATP consumption, such a shift in the protein ratio cuts down on the energy costs to produce the silk. From this change in protein composition the spider might therefore benefit twice, by synthesizing 'cheaper' silk that into the bargain has properties that potentially can better support foraging in times of food shortage.
圆网蛛类棒络新妇蛛（Nephila clavipes）主壶腹腺（MA）中形成的蛛丝由两种丝心蛋白组成，分别称为主壶腹蛛丝蛋白1（MaSp1）和主壶腹蛛丝蛋白2（MaSp2）。对蛋白水解肽的分析以及对蛛丝蛋白类型特异性抗体的反应表明，MaSp2在纺丝原液和纺出的丝中仅占一小部分。饥饿时，观察到蛛丝的特征发生了变化，同时MaSp2的贡献也减少了。蛛丝变得弹性更小、更硬，这将更适合用于安全线，尽管代价是不能再用作蛛网框架的丝线。此外，由于MaSp2的产生需要消耗更多的ATP，这种蛋白质比例的变化降低了生产蛛丝的能量成本。因此，通过合成“更便宜”的蛛丝，这种蛋白质组成的变化可能会让蜘蛛获得双重好处，而且这种蛛丝在食物短缺时可能更有利于觅食。
