University of Bielefeld, Department of Animal Ecology, Morgenbreede 45, 33615 Bielefeld, Germany.
Ecotoxicol Environ Saf. 2011 Oct;74(7):1824-31. doi: 10.1016/j.ecoenv.2011.07.007. Epub 2011 Jul 23.
This study examined an alternative test medium for nematodes that use gellan gum as the gelling agent instead of agar. The semi-fluid consistency of the gel-like component nematode growth gellan gum (CNGG) supports three-dimensional distribution of the nematodes and food bacteria, but still allows free movement of the former. Moreover, flexible preparation of the medium and easy recovery of the test organisms are possible. Here, the effects of the nematicides ivermectin (pharmaceutical) and aldicarb (pesticide) and of the metal cadmium on the growth and reproduction of the free-living nematodes Caenorhabditis elegans and Panagrolaimus cf. thienemanni were studied in CNGG media. Results were compared to those obtained with the standard liquid test media in order to evaluate the applicability of CNGG for nematode toxicity testing. The sensitivity of P. cf. thienemanni to all three substances was found to be higher than that of C. elegans, but both nematodes showed the highest sensitivity to ivermectin exposure. This raises concerns about the risk posed by the pharmaceutical to non-target nematodes. In contrast to ivermectin bioassays carried out in CNGG medium, those conducted in liquid medium resulted in wide-ranging variability between and within replicates. Thus, CNGG seems to be particularly valuable for testing hydrophobic substances with a high sorption affinity as it favors their sorption to food bacteria and minimizes contact with the surfaces of the test vessels. However, the medium was less suitable for deriving toxicity thresholds for cadmium and may likewise not be an appropriate choice for testing other metals. The medium introduced herein was shown to be appropriate for sublethal nematode toxicity testing and likely provides a convenient environment for testing other nematode species. Besides improved testing of hydrophobic substances, CNGG also offers advantages for long-term studies, such as full life-cycle experiments, in which fresh medium is regularly needed. Moreover it may be beneficial for testing other poorly soluble or insoluble substances, such as nanoparticles.
本研究探讨了一种替代的线虫测试介质，该介质使用结冷胶作为胶凝剂，而不是琼脂。凝胶状成分线虫生长结冷胶（CNGG）的半流体一致性支持线虫和食物细菌的三维分布，但仍允许前者自由移动。此外，该介质的制备灵活，测试生物的回收也很容易。在这里，研究了驱虫药伊维菌素（药物）和涕灭威（农药）以及金属镉对自由生活线虫秀丽隐杆线虫和 Panagrolaimus cf. thienemanni 的生长和繁殖的影响在 CNGG 培养基中。将结果与标准液体测试培养基的结果进行了比较，以评估 CNGG 在线虫毒性测试中的适用性。结果表明，P. cf. thienemanni 对所有三种物质的敏感性均高于 C. elegans，但两种线虫对伊维菌素暴露的敏感性最高。这引起了人们对药物对非靶标线虫构成风险的关注。与在 CNGG 培养基中进行的伊维菌素生物测定相比，在液体培养基中进行的生物测定在重复之间和重复内产生了广泛的可变性。因此，CNGG 似乎特别适合测试具有高吸附亲和力的疏水性物质，因为它有利于它们被食物细菌吸附，并最大限度地减少与测试容器表面的接触。然而，该培养基不太适合确定镉的毒性阈值，并且对于测试其他金属可能也不是一个合适的选择。本文介绍的培养基适用于亚致死线虫毒性测试，并可能为测试其他线虫物种提供便利的环境。除了对疏水性物质的测试得到改善外，CNGG 还为长期研究提供了优势，例如全生命周期实验，其中经常需要新鲜的培养基。此外，它可能有助于测试其他难溶性或不溶性物质，如纳米颗粒。
