Davidson E W
J Invertebr Pathol. 1989 Mar;53(2):251-9. doi: 10.1016/0022-2011(89)90015-3.
Bacillus sphaericus toxin labeled with fluorescein isothiocyanate was readily ingested by Culex pipiens, Aedes aegypti, Anopheles stephensi, Anopheles gambiae, Anopheles quadrimaculatus, and Anopheles albimanus larvae. Fluorescent toxin bound to the luminal cell surface in discrete regions of the posterior midgut and gastric caecum in C. pipiens. In Anopheles spp., toxin bound in a variable pattern to these structures and central and anterior midgut as well. The toxin did not bind to midgut cells of A. aegypti. The toxin was internalized in bright fluorescent vesicles in C. pipiens, but was not internalized in Anopheles spp. and appeared to be weakly bound in these larvae, leaking rapidly from the gut surface. The lectin, wheat germ agglutinin, which interferes with binding of the B. sphaericus toxin, bound to the posterior midgut and gastric caecum of all species, but was not internalized. These results suggest that the sugar moiety of the receptor is not solely responsible for specificity of this toxin, and that binding to Culex spp. midgut cells may be highly specific and of high affinity, whereas binding to Anopheles spp. cells may be nonspecific and/or of low affinity.
用异硫氰酸荧光素标记的球形芽孢杆菌毒素很容易被致倦库蚊、埃及伊蚊、斯氏按蚊、冈比亚按蚊、四斑按蚊和白跗按蚊幼虫摄取。荧光毒素在致倦库蚊中肠后部和胃盲囊的离散区域与肠腔细胞表面结合。在按蚊属中，毒素以可变模式与这些结构以及中肠中部和前部结合。毒素不与埃及伊蚊的中肠细胞结合。毒素在致倦库蚊中被内化到明亮的荧光小泡中，但在按蚊属中不被内化，并且在这些幼虫中似乎结合较弱，从肠道表面迅速泄漏。凝集素麦胚凝集素可干扰球形芽孢杆菌毒素的结合，它与所有物种的中肠后部和胃盲囊结合，但不被内化。这些结果表明，受体的糖部分并非该毒素特异性的唯一决定因素，并且与库蚊属中肠细胞的结合可能具有高度特异性和高亲和力，而与按蚊属细胞的结合可能是非特异性的和/或低亲和力的。
