Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
Rice Technology Research and Development Center, China National Rice Research Institute, Hangzhou, China.
Insect Sci. 2023 Jun;30(3):693-704. doi: 10.1111/1744-7917.13118. Epub 2022 Nov 2.
The lipid metabolism plays an essential role in the development and reproduction of insects, and lipases are important enzymes in lipid metabolism. In Nilaparvata lugens, an important insect pest on rice, triacylglycerol hydrolytic activities were different among tissues, with high activity in integument, ovary, and fat body, but low activity in intestine. To figure out the tissue-specific triacylglycerol hydrolytic activity, we identified 43 lipases in N. lugens. Of these 43 lipases, 23 belonged to neutral lipases, so this group was selected to perform further experiments on triacylglycerol hydrolysis. The complete motifs of catalytic triads, β9 loop, and lid motif, are required for the triacylglycerol hydrolytic activity in neutral lipases, which were found in some neutral lipases with high gene expression levels in integument and ovary, but not in intestine. The recombinant proteins of 3 neutral lipases with or without 3 complete motifs were obtained, and the activity determination confirmed the importance of 3 motifs. Silencing XM_022331066.1, which is highly expressed in ovary and with 3 complete motifs, significantly decreased the egg production and hatchability of N. lugens, partially through decline of the lipid metabolism. In summary, at least one-third of important motifs were incomplete in all neutral lipases with high gene expression in intestine, which could partially explain why the lipase activity in intestine was much lower than that in other tissues. The low activity to hydrolyze triacylglycerol in N. lugens intestine might be associated with its food resource and nutrient components, and the ovary-specific neutral lipases were important for N. lugens reproduction.
脂质代谢在昆虫的发育和繁殖中起着至关重要的作用，而脂肪酶是脂质代谢中的重要酶。在水稻上的重要害虫褐飞虱中，组织间的三酰基甘油水解活性不同，表皮、卵巢和脂肪体活性高，而肠道活性低。为了弄清组织特异性的三酰基甘油水解活性，我们在褐飞虱中鉴定了 43 种脂肪酶。在这 43 种脂肪酶中，有 23 种属于中性脂肪酶，因此选择这一组进行进一步的三酰基甘油水解实验。催化三联体、β9 环和盖子基序的完整基序是中性脂肪酶三酰基甘油水解活性所必需的，在表皮和卵巢中基因表达水平较高的一些中性脂肪酶中发现了这些基序，但在肠道中没有发现。获得了 3 种具有或不具有 3 个完整基序的中性脂肪酶的重组蛋白，并通过活性测定证实了这 3 个基序的重要性。沉默在卵巢中高表达且具有 3 个完整基序的 XM_022331066.1，显著降低了褐飞虱的产卵量和孵化率，部分原因是脂质代谢下降。总之，在肠道中基因表达水平较高的所有重要中性脂肪酶中，至少有三分之一的关键基序不完整，这部分解释了为什么肠道中的脂肪酶活性远低于其他组织。褐飞虱肠道中三酰基甘油水解活性低可能与其食物资源和营养成分有关，卵巢特异性中性脂肪酶对褐飞虱的繁殖很重要。
