Cooper L A, Richards C S, Lewis F A, Minchella D J
Biomedical Research Institute, Rockville, Maryland 20852.
Exp Parasitol. 1994 Aug;79(1):21-8. doi: 10.1006/expr.1994.1055.
Biomphalaria glabrata snails which were not susceptible as juveniles to infection by Schistosoma mansoni were selectively bred (by self-fertilization) from the highly susceptible NMRI laboratory snail stock. The susceptibility rate among juvenile snails derived from interbreeding NMRI parents was initially 85-95%, but after several generations of selection, less than 5% of exposed snails became infected by the parasite. Selection for low susceptibility also resulted in a large proportion of snails that displayed low fecundity and produced abnormal egg masses. Individual adult snails which were isolated from an interbreeding population of nonselected NMRI snails usually produced well-developed egg masses each containing 15-30 embryos. However, when juvenile snails from this same population were reared in isolation and not allowed to cross-fertilize, many displayed a pattern of low fecundity and abnormal egg production similar to that observed in the selected low susceptible line. Furthermore, it was found that many of the isolated snails which exhibited low egg production were also not susceptible to parasitic infection.
光滑双脐螺最初作为幼螺对曼氏血吸虫感染不敏感，它们是从高度敏感的NMRI实验室蜗牛种群中通过自交进行选择性培育的。由NMRI亲本杂交产生的幼螺的易感性最初为85%-95%，但经过几代选择后，暴露于寄生虫的蜗牛中感染率不到5%。对低易感性的选择还导致很大一部分蜗牛繁殖力低且产出异常卵块。从非选择的NMRI蜗牛杂交种群中分离出的成年蜗牛个体通常会产出发育良好的卵块，每个卵块含有15-30个胚胎。然而，当来自同一群体的幼螺单独饲养且不允许杂交时，许多幼螺表现出繁殖力低和产卵异常的模式，这与在选择的低易感性品系中观察到的情况相似。此外，还发现许多产卵量低的分离蜗牛对寄生虫感染也不敏感。
