Diversity and evolutionary history of RNA viruses among different horseshoe crab species.

Horseshoe crabs (Xiphosura: Limulidae) are the sole surviving species of the class Merostomata, with only four extant species remaining today. Recent advances in metagenomic next-generation sequencing have unveiled a vast diversity of RNA viruses and non-retroviral endogenous RNA viral elements (nrEVEs) in invertebrates. This raises intriguing questions about the RNA virome and nrEVEs in horseshoe crabs as "living fossils," potentially offering insights into the evolutionary relationships between RNA viruses and these ancient organisms.

A truncated Sph with potent antimicrobial activity showing resistance against bacterial challenge in Oryzias melastigma.

Antimicrobial peptides (AMPs) represent an efficient part of innate immunity and are found in a variety of life. Among them Histone 2A (H2A), as a promising class of AMPs, attracts great attention, but the in vivo mechanism of H2A derived AMP is still less known. Based on the acquisition of Sphistin, a synthetic 38-amino acid H2A derived peptide from Scylla paramamosain, as reported in our previous study, was truncated into three short fragments (Sph, Sph and Sph) and further investigated for its possible functional domains.