School of Life Sciences, Anhui Agricultural University, Hefei, China; Anhui International Joint Research and Developmental Center of Sericulture Resources Utilization, Hefei, China; National Navel Orange Engineering and Technology Research Center, Gannan Normal University, Ganzhou, China.
School of Life Sciences, Anhui Agricultural University, Hefei, China; Anhui International Joint Research and Developmental Center of Sericulture Resources Utilization, Hefei, China.
J Invertebr Pathol. 2018 Nov;159:61-70. doi: 10.1016/j.jip.2018.10.009. Epub 2018 Oct 19.
Apolipophorin-III (ApoLp-III) is an abundant hemolymph protein mainly involved in lipid transport and innate immunity in insects. In the present study, the gene Samia cynthia ricini ApoLp-III (ScApoLp-III) was identified from a transcriptome database, and contained 790 nucleotides with a putative open reading frame (ORF) of 561 bp encoding 186 amino acid residues. Phylogenetic analysis revealed that ScApoLp-III had significant homology with ApoLp-III protein from Antheraea pernyi. Higher ScApoLp-III expression levels were found in the fat body and silk gland by reverse transcription quantitative PCR (RT-qPCR). Injection of Staphylococcus aureus induced up-regulation of ScApoLp-III in the midgut, fat body and hemocytes. However, ScApoLp-III was down-regulated in the midgut and fat body after Pseudomonas aeruginosa injection, indicating that ScApoLp-III may contribute to the host's defense against invading pathogens. Additionally, recombinant ScApoLp-III was found to bind different bacteria, including E. coli, P. aeruginosa, S. aureus and B. subtilis. Bactericidal tests showed that recombinant ScApoLp-III strongly inhibited Gram-negative bacteria, including Escherichia coli and P. aeruginosa. However, it had no obvious influence on Gram-positive bacteria. Taken together, our results suggest that the ScApoLp-III might play an important role in the innate immunity of S. c. ricini.
载脂蛋白 Lp-III（ApoLp-III）是昆虫血淋巴中一种丰富的蛋白，主要参与脂质运输和先天免疫。本研究从转录组数据库中鉴定出桑蚕载脂蛋白 Lp-III（ScApoLp-III）基因，其包含 790 个核苷酸，推测开放阅读框（ORF）为 561bp，编码 186 个氨基酸残基。系统进化分析表明，ScApoLp-III 与柞蚕 ApoLp-III 蛋白具有显著同源性。荧光定量 RT-PCR（RT-qPCR）显示 ScApoLp-III 在脂肪体和丝腺中表达量较高。金黄色葡萄球菌感染诱导中肠、脂肪体和血细胞中 ScApoLp-III 上调，铜绿假单胞菌感染诱导中肠和脂肪体中 ScApoLp-III 下调，表明 ScApoLp-III 可能参与宿主防御入侵病原体。此外，重组 ScApoLp-III 与不同细菌结合，包括大肠杆菌、铜绿假单胞菌、金黄色葡萄球菌和枯草芽孢杆菌。杀菌试验表明，重组 ScApoLp-III 强烈抑制革兰氏阴性菌，包括大肠杆菌和铜绿假单胞菌。然而，它对革兰氏阳性菌没有明显影响。综上，我们的研究结果表明 ScApoLp-III 可能在桑蚕的先天免疫中发挥重要作用。
