A Draft Genome Assembly of the Antarctic Springtail Cryptopygus antarcticus and Diversity of Glycoside Hydrolase Genes.

The Antarctic springtail Cryptopygus antarcticus Willem (family Isotomidae) is a representative arthropod species of the maritime Antarctic environment that could be used as an important organism for further study of animal evolution and adaptation. Despite the biological and ecological peculiarities that distinguish them from the majority of collembolan species, our understanding of the genetic background behind their success in an extreme habitat remains unclear. We present the first high-quality draft genome of C. antarcticus assembled from in-depth whole genome and transcriptome sequencing data obtained from both long-read and short-read sequencing platforms. The genome was 103.6 Mb in size with 81 scaffolds and a scaffold N50 of 3.4 Mb, appearing to have a smaller genome than that of hitherto known collembolan genomes. Following protein-coding gene prediction and annotation analyses, 19,808 non-redundant genes were identified, representing 97.0% Benchmarking Universal Single-Copy Ortholog (BUSCO) gene coverage. Subsequent Gene Ontology (GO) functional enrichment analyses revealed that significantly expanded gene families were mainly associated with cell cycle regulation and changes in cell states or activities, while contracted gene families were related to the inhibition of germ cell proliferation. Several glycoside hydrolase family genes were identified in C. antarcticus, some of which may have evolved to facilitate their survival in the extreme environment. These findings suggest that the evolution of these gene families is related to their adaptation to the habitat's extreme conditions.