Egg Case Silk Gene Sequences from Argiope Spiders: Evidence for Multiple Loci and a Loss of Function Between Paralogs

G3: Genes, Genomes, Genetics

Matthew Collin^1¹  R. Crystal Chaw^1²  Marjorie Wimmer^1³  Kara-Leigh Helmrick^1⁴ 

[1] Department of Biology, University of California, Riverside, California 92521;Department of Biology, University of California, Riverside, California 92521^1;Division of Invertebrate Zoology, American Museum of Natural History, New York, New York 10024;Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York 10024^2

关键词: evolution;    gene family;    spider silk;    tubuliform spidroin;    TuSp1;   

DOI  :  10.1534/g3.117.300283

学科分类：生物科学（综合）

来源: Genetics Society of America

【 摘 要 】

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.

【 授权许可】

CC BY