Sex Results in Divergence in Gut Bacterial Community between Female and Male Pardosa astrigera (Araneae: Lycosidae)

Sex is one of the important factors affecting gut microbiota. As key predators in agro-forestry ecosystem, many spider species show dramatically different activity habits and nutritional requirements between female and male. However, how sex affects gut microbiota of spiders is still unclear. Therefore, in this study, the compositions and diversities of gut bacteria, based on bacterial 16S rRNA gene sequencing, were compared between female and male Pardosa astrigera. We found that bacterial richness indices (P < 0.05) in female were significantly lower than male, meanwhile, β-diversity showed significantly different between female and male (P < 0.05). The relative abundance of Actinobacteriota and Rhodococcus (belongs to Actinobacteria) were significantly higher in female than male (P < 0.05). Whereas, the relative abundance of Firmicutes and Acinetobacter (belongs to Proteobacteria), Ruminococcus and Fusicatenibacter (all belong to Firmicutes), were significantly higher in male than female (P < 0.05). The results of PICRUSt2 showed that amino acid and lipid metabolisms were significantly higher in female than male (P < 0.05), whereas glycan biosynthesis and metabolism was significantly higher in male than female (P < 0.05). Our results imply that sexual variation is a crucial factor in shaping gut bacterial community in P. astrigera. Male P. astrigera dispersed more widely than the female hence the male had a higher bacterial diversity. While the distinct differences of bacterial composition mainly due to their different nutritional and energy requirements.

Antibacterial and Anti-Inflammatory Effects of Novel Peptide Toxin from the Spider Pardosa astrigera

The prevalence of antibiotic-resistant bacteria has become an immediate threat to public health. Antimicrobial peptides are attracting attention as a new source of antibiotics due to their ability to prevent drug-resistances with fewer side effects. Spider venom is composed of various bioactive substances with multiple functionalities such as antimicrobial and anti-inflammatory effects. Here, RNA sequencing was conducted on the venom gland of the spider Pardosa astrigera, and a potential toxin peptide with antibacterial properties was selected via homology and in silico analysis. A novel toxin, Lycotoxin-Pa4a, inhibited both gram-negative and gram-positive bacteria by disrupting the outer and bacterial cytoplasmic membrane. Moreover, the peptide downregulated the expression of pro-inflammatory mediators while upregulating the level of anti-inflammatory cytokine by inactivating mitogen-activated protein kinase signaling in a lipopolysaccharide-stimulated murine macrophage cell line. In this research, we identified a novel peptide toxin, Lycotoxin-pa4a, with antibacterial and anti-inflammatory properties, suggesting its potential for the development of a new antibiotics, as well as offering insights into the utilization of biological resources.