蜘蛛用丝绸包裹卵,以保护发育中的胚胎和幼体。蛋壳丝,像其他纤维蜘蛛丝一样,主要由称为spidroins(spidroin=蜘蛛丝蛋白)的蛋白质组成。丝绸,因此,蜘蛛,在蜘蛛的一生中都很重要,然而,spidroin基因的进化研究相对不足。众所周知,自旋蛋白基因很难测序,因为它们通常非常长(编码序列≥10kb)并且高度重复。这里,我们通过细菌人工染色体(BAC)克隆的长读数测序研究蜘蛛丝基因的进化。我们证明了银园蜘蛛Argiopeargentata具有多个卵壳鞘蛋白基因座,在一个基因座处功能丧失。我们还使用简并的PCR引物来搜索同属物种的基因组DNA,并在其他Argiope蜘蛛中找到多个卵病例spidroin基因座的证据。比较分析显示,这些多个基因座在物种内的核苷酸水平上比物种之间更相似。这种模式与基因组内均质化基因拷贝的协同进化一致。更复杂的解释包括每个物种内的趋同进化或最近的独立基因重复。
Spiders swath their eggs with silk to protect developing embryos and hatchlings. Egg
case silks, like other fibrous spider silks, are primarily composed of proteins called spidroins (spidroin = spider-fibroin). Silks, and thus spidroins, are important throughout the lives of spiders, yet the evolution of spidroin genes has been relatively understudied. Spidroin genes are notoriously difficult to sequence because they are typically very long (≥ 10 kb of coding sequence) and highly repetitive. Here, we investigate the evolution of spider silk genes through long-read sequencing of Bacterial Artificial Chromosome (BAC) clones. We demonstrate that the silver garden spider Argiope argentata has multiple egg
case spidroin loci with a loss of function at one locus. We also use degenerate PCR primers to search the genomic DNA of congeneric species and find evidence for multiple egg
case spidroin loci in other Argiope spiders. Comparative analyses show that these multiple loci are more similar at the nucleotide level within a species than between species. This pattern is consistent with concerted evolution homogenizing gene copies within a genome. More complicated explanations include convergent evolution or recent independent gene duplications within each species.