Winter M D, McPherson M J, Atkinson H J
Center for Plant Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, UK.
Parasitology. 2002 Dec;125(Pt 6):561-5.
Low doses of the acetylcholinesterase-inhibiting carbamate nematicides disrupt chemoreception in plant-parasitic nematodes. Fluorescein isothiocyanate (FITC)/dextran conjugates up to 12 kDa are taken up from the external medium by certain chemosensory neurons in Caenorhabditis elegans. Similar chemoreceptive neurons of the non-feeding infective stage of Heterodera glycines (soybean cyst nematode) fill with FITC and the nuclei of their cell bodies selectively stain with bisbenzimide. The widely used nematicide aldicarb disrupts the chemoreceptive response of H. glycines with 50% inhibition at very low concentrations (ca 1 pM), some 10(-6)-fold lower than required to affect locomotion. Similarly, the anthelmintic levamisole had this effect at 1 nM. Peptides selected as mimetics of aldicarb and levamisole also disrupt chemoreception in H. glycines and Globodera pallida at 10(-3)-fold or lower concentration than required to inhibit locomotion. We propose an uptake pathway for aldicarb, levamisole, peptide mimetics and other soluble molecules by retrograde transport along dendrites of chemoreceptive neurons to the cell bodies and synapses where they act. This may prove to be a general mechanism for the low-dose effects of some nematicides and anthelmintics.
低剂量的乙酰胆碱酯酶抑制性氨基甲酸酯类杀线虫剂会破坏植物寄生线虫的化学感受。在秀丽隐杆线虫中，分子量高达12 kDa的异硫氰酸荧光素（FITC）/葡聚糖偶联物会被某些化学感受神经元从外部介质中摄取。大豆胞囊线虫非取食感染阶段的类似化学感受神经元会充满FITC，其细胞体的细胞核会被双苯甲酰亚胺选择性染色。广泛使用的杀线虫剂涕灭威在极低浓度（约1 pM）下就能破坏大豆胞囊线虫的化学感受反应，抑制率达50%，这一浓度比影响其运动所需浓度低约10^(-6)倍。同样，驱虫药左旋咪唑在1 nM时也有此作用。被选作涕灭威和左旋咪唑模拟物的肽类在比抑制运动所需浓度低10^(-3)倍或更低的浓度下，也会破坏大豆胞囊线虫和苍白球孢囊线虫的化学感受。我们提出了一条涕灭威、左旋咪唑、肽类模拟物及其他可溶性分子的摄取途径，即通过化学感受神经元的树突逆行转运至细胞体和突触，在那里它们发挥作用。这可能是某些杀线虫剂和驱虫药产生低剂量效应的一种普遍机制。
