Borash DJ, Pierce VA, Gibbs AG, Mueller LD
Department of Systems Science-Biology, University of Tokyo, Komaba, Japan
J Insect Physiol. 2000 May 1;46(5):763-769. doi: 10.1016/s0022-1910(99)00165-1.
We examined whether populations of Drosophila melanogaster could evolve a genetically based tolerance to high levels of toxic compounds (urea or ammonia) added to their larval food medium. We also examined whether tolerance to one compound may impart cross-tolerance to other compounds. Five populations selected for ammonia tolerance (AX), five populations selected for urea tolerance (UX), and five unselected controls (AUC) were assayed for developmental time, viability, and female fertility. These characteristics were measured on each of the 15 populations reared on one of three larval food conditions (plain banana-molasses, 0.35 M NH(4)Cl, or 0.266 M urea). On urea-supplemented media, the urea-selected populations developed fastest and expressed the highest viability; the ammonia-selected populations developed significantly faster and had a higher viability than the controls. Similarly, on ammonia-supplemented media, the ammonia-selected populations developed fastest and expressed the highest viability; the urea-selected populations developed significantly faster and had a higher viability than the controls. This suggests that a cross-tolerance exists for resisting different toxic compounds. Urea-selected females reared on urea-containing food media displayed superior fecundity, without any observable cross-tolerance effect. When all populations were reared on food containing 0.266 M urea, the urea-selected populations had the lowest levels of urea in their tissues. All populations reared on food containing 0.37 M ammonia or 0.266 M urea, contained more ammonia in their tissues than did populations reared on plain food.
我们研究了黑腹果蝇种群是否能够进化出对添加到其幼虫食物培养基中的高浓度有毒化合物（尿素或氨）的遗传耐受性。我们还研究了对一种化合物的耐受性是否可能赋予对其他化合物的交叉耐受性。对五个选择用于氨耐受性的种群（AX）、五个选择用于尿素耐受性的种群（UX）和五个未选择的对照种群（AUC）进行了发育时间、活力和雌性生育力的测定。在三种幼虫食物条件（普通香蕉糖浆、0.35 M NH₄Cl或0.266 M尿素）之一饲养的15个种群中的每一个种群上测量了这些特征。在添加尿素的培养基上，选择尿素的种群发育最快且活力最高；选择氨的种群发育明显快于对照种群且活力更高。同样，在添加氨的培养基上，选择氨 的种群发育最快且活力最高；选择尿素的种群发育明显快于对照种群且活力更高。这表明存在抵抗不同有毒化合物的交叉耐受性。在含尿素的食物培养基上饲养的选择尿素的雌性表现出较高的繁殖力，没有任何可观察到的交叉耐受性效应。当所有种群都在含有0.266 M尿素的食物上饲养时，选择尿素的种群组织中的尿素水平最低。在含有0.37 M氨或0.266 M尿素的食物上饲养的所有种群，其组织中的氨含量都比在普通食物上饲养的种群多。
