Billingsley P F, Hecker H
Swiss Tropical Institute, Basel.
J Med Entomol. 1991 Nov;28(6):865-71. doi: 10.1093/jmedent/28.6.865.
The activities of trypsin, aminopeptidase, and alpha-glucosidase were studied in the whole midgut, anterior and posterior midgut, and posterior midgut lumen and epithelium of the mosquito Anopheles stephensi Liston. Trypsin activity was restricted entirely to the posterior midgut lumen. No trypsin activity was found before the blood meal, but activity increased continuously up to 30 h after feeding, and subsequently returned to baseline levels by 60 h. Aminopeptidase was active in anterior and posterior midgut regions before and after feeding. In whole midguts, activity rose from a baseline of approximately 3 enzyme units (EU) per midgut to a maximum of 12 EU at 30 h after the blood meal, subsequently falling to baseline levels by 60 h. A similar cycle of activity was observed in the posterior midgut and posterior midgut lumen, whereas aminopeptidase in the posterior midgut epithelium decreased in activity during digestion. Aminopeptidase in the anterior midgut was maintained at a constant low level, showing no significant variation with time after feeding. alpha-glucosidase was active in anterior and posterior midguts before and at all times after feeding. In whole midgut homogenates, alpha-glucosidase activity increased slowly up to 18 h after the blood meal, then rose rapidly to a maximum at 30 h after the blood meal, whereas the subsequent decline in activity was less predictable. All posterior midgut activity was restricted to the posterior midgut lumen. Depending upon the time after feeding, greater than 25% of the total midgut activity of alpha-glucosidase was located in the anterior midgut. The enzyme distributions are consistent with described structural models for digestion in mosquitoes. After blood meal ingestion, proteases are active only in the posterior midgut. Trypsin is the major primary hydrolytic protease and is secreted into the posterior midgut lumen without activation in the posterior midgut epithelium. Aminopeptidase activity is also luminal in the posterior midgut, but cellular aminopeptidases are required for peptide processing in both anterior and posterior midguts. alpha-glucosidase activity is elevated in the posterior midgut after feeding in response to the blood meal, whereas activity in the anterior midgut is consistent with a nectar-processing role for this midgut region.
在斯氏按蚊（Anopheles stephensi Liston）的整个中肠、中肠前部和后部以及中肠后部管腔和上皮中，研究了胰蛋白酶、氨肽酶和α-葡萄糖苷酶的活性。胰蛋白酶活性完全局限于中肠后部管腔。在进食血餐之前未发现胰蛋白酶活性，但活性在进食后持续增加，直至30小时，随后在60小时恢复到基线水平。氨肽酶在进食前后的中肠前部和后部区域均有活性。在整个中肠中，活性从每个中肠约3个酶单位（EU）的基线水平上升至进食血餐后30小时的最高12 EU，随后在60小时降至基线水平。在中肠后部和中肠后部管腔中观察到类似的活性循环，而中肠后部上皮中的氨肽酶在消化过程中活性降低。中肠前部的氨肽酶维持在恒定的低水平，进食后随时间无显著变化。α-葡萄糖苷酶在进食前和进食后的所有时间在中肠前部和后部均有活性。在整个中肠匀浆中，α-葡萄糖苷酶活性在进食血餐后缓慢增加，直至18小时，然后在进食血餐后30小时迅速升至最高，而随后的活性下降则较难预测。所有中肠后部活性均局限于中肠后部管腔。根据进食后的时间，α-葡萄糖苷酶总中肠活性的超过25%位于中肠前部。酶的分布与描述的蚊子消化结构模型一致。摄入血餐后，蛋白酶仅在中肠后部有活性。胰蛋白酶是主要的初级水解蛋白酶，分泌到中肠后部管腔中，在中肠后部上皮中不被激活。氨肽酶活性在中肠后部也是管腔性的，但细胞氨肽酶在中肠前部和后部的肽加工中都是必需的。进食血餐后，中肠后部的α-葡萄糖苷酶活性升高，以响应血餐，而中肠前部的活性与该中肠区域在花蜜加工中的作用一致。
