Young J W, Dashek W V, Llewellyn G C
Mycopathologia. 1978 Dec 29;66(1-2):91-7. doi: 10.1007/BF00429599.
The present work reports a portion of our continuing effort to determine the mechanism(s) whereby aflatoxins cause toxic responses in in vitro cultured plant tissues. Few investigations have dealt with the mode of action of aflatoxin B1 (AFB1) in excised plant tissues. Here is detailed AFB1 influence on growth, uptake and incorporation of 14C-leucine by excised, incubated soya-bean roots. Pure AFB1 was added to culture medium prior to autoclaving. One gram fresh weight portions of roots from three-day old soya-bean seedlings were excised and incubated for 4, 8, 12 and 24 hours. Growth was assayed by following changes in root dry weight. Aflatoxin B1 inhibited root dry weight at both 20 and 30 micrograms/ml. Uptake of 14C-leucine was checked by following its depletion from the medium. Reduced 14C-leucine uptake by roots exposed to 20 micrograms/ml AFB1 suggests that the toxin may alter the plasmalemma. A possible role for AFB1 in modification of membrane-associated amino acid transport mechanisms is discussed. Incorporation of 14C-leucine into trichloroacetic acid-precipitable cytoplasm was assayed. Inhibition of this incorporation at 20 micrograms/ml AFB1 was most apparent at 12 hours. Thus, AFB1 may also impair the ability of excised soya-bean roots to carry out protein synthesis.
本研究报告了我们在确定黄曲霉毒素在体外培养植物组织中引起毒性反应的机制方面持续努力的一部分。很少有研究涉及黄曲霉毒素B1（AFB1）在离体植物组织中的作用方式。以下是AFB1对离体培养的大豆根的生长、14C-亮氨酸的吸收和掺入的详细影响。在高压灭菌前将纯AFB1添加到培养基中。从三天大的大豆幼苗中切下1克鲜重的根段，分别培养4、8、12和24小时。通过跟踪根干重的变化来测定生长情况。AFB1在20和30微克/毫升时均抑制根干重。通过跟踪培养基中14C-亮氨酸的消耗来检查其吸收情况。暴露于20微克/毫升AFB1的根对14C-亮氨酸的吸收减少，这表明毒素可能改变了质膜。讨论了AFB1在修饰与膜相关的氨基酸转运机制中的可能作用。测定了14C-亮氨酸掺入三氯乙酸可沉淀细胞质的情况。在20微克/毫升AFB1时，这种掺入的抑制在12小时时最为明显。因此，AFB1也可能损害离体大豆根进行蛋白质合成的能力。
