Role of a serine protease gene (AccSp1) from Apis cerana cerana in abiotic stress responses and innate immunity

Abstract

Clip-domain serine proteases (Clip-SPs) mediate innate immunity and embryonic development in insects. However, the function of Clip-SPs in Apis cerana cerana is little known. Here, a Clip-SP gene, AccSp1, was identified. AccSp1 was mainly detected in third and sixth day instar larvae, dark-eyed pupae, and adults (1and 30 days post-emergence). In addition, AccSp1 was expressed at its highest level in the venom gland and epidermis than tentacle, abdomen, muscle, honey sac, head, leg, chest, hemolymph, rectum, and midgut. AccSp1 was induced by 4, 24, and 44°C; H 2 O 2 ; CdCl 2; HgCl 2 ; and pesticides (paraquat, pyridaben, and methomyl) and was inhibited by UV light and cyhalothrin treatments. When adults that had been pretreated with dsRNA 6 h prior (knocking AccSp1 down) were challenged with Bacillus bombysepticus for 18 h, the survival rate of bees greatly decreased, the activity of PO (phenoloxidase) was reduced, revealing that AccSp1 may play a critical role in assisting bees to survive the microbial infection and participate in regulating PO activity. The antioxidant enzymatic activities of catalase, peroxidase, and superoxide dismutase; the contents of hydrogen peroxide and malondialdehyde; and the ratio of NADP + /NADPH were all lower in samples containing dsRNA-AccSp1 interference than in control groups, but the content of carbonyl was not significantly different. These findings suggest the knockdown of AccSp1 may influence melanization so that the antioxidant enzyme activities and the harmful metabolites decreased. These results collectively suggest that AccSp1 plays critical roles in abiotic stresses responses and resistance to pathogens.

Clip-Domain Serine Protease Gene (LsCLIP3) Is Essential for Larval–Pupal Molting and Immunity in Lasioderma serricorne

“…Although many CLIPs have been identified and characterized in insects, the functions of most CLIPs are unknown (Kanost and Jiang, 2015). In Apis cerana cerana, a CLIP gene (AccSP1) is found to play crucial roles in the defense of abiotic stresses and resistance to pathogens (Gao et al, 2019). In B. mori, only three CLIP genes (CLIP1, CLIP2, and SP95) are documented to be involved in innate immune and integument remodeling during molting (Zhao et al, 2010;Liu et al, 2017).…”

Draft Genome Sequences of Two Bacillus bombysepticus Strains from Drinking Water

“…Studies have shown that B. bombysepticus infection in silkworms leads to the upregulation of serine protease inhibitor genes ( 4 ). Additionally, B. bombysepticus has also been shown to be lethal to bees ( 5 ); however, little is known about its pathogenicity in humans.…”