Chromosome-level reference genome for the medically important Arabian horned viper (Cerastes gasperettii)

Abstract

Venoms have traditionally been studied from a proteomic and/or transcriptomic perspective, often overlooking the true genetic com- plexity underlying venom production. The recent surge in genome-based venom resear c h (sometimes called “venomics”) has proven to be instrumental in deepening our understanding of venom evolution at the molecular level, particularly through the identifica- tion and mapping of toxin-coding loci across the broader chromosomal ar c hitecture . Although venomous snakes are a model sys- tem in venom resear c h, the number of high-quality r efer ence genomes in the gr oup r emains limited. In this study, we present a chr omosome-r esolution r efer ence genome for the Ara bian horned viper Cerastes gasperettii (NCBI: txid110202), a venomous snake na- ti v e to the Arabian Peninsula. Our highly contiguous genome (genome size: 1.63 Gbp; contig N50: 45.6 Mbp; BUSCO: 92.8%) allowed us to explore macrochromosomal rearrangements within the Viperidae family, as well as across squamates. We identified the main highl y expr essed toxin genes within the venom glands comprising the v enom’s cor e, in line with our pr oteomic r esults. We also com- par ed micr osyntenic changes in the main toxin gene clusters with those of other venomous snake species, highlighting the pi v otal role of gene duplication and loss in the emergence and di v ersification of snake v enom metallopr oteinases and snake venom serine proteases for C. gasperettii . Using Illumina short-read sequencing data, we reconstructed the demographic history and genome-wide heterozigosity of the species, revealing how historical aridity likely drove population expansions. Finally, this study highlights the im- portance of using long-read sequencing as well as chr omosome-lev el r efer ence genomes to disentangle the origin and di v ersification of toxin gene families in venomous snake species.