School of Life Sciences, University of Nottingham, University Park, NottinghamNG7 2RD, UK.
J Helminthol. 2021 Nov 22;95:e69. doi: 10.1017/S0022149X21000596.
Nematode spicules vary in shape and size even between closely related species and, therefore, constitute key characters in nematode taxonomy for distinguishing between species. Spicules are seldom measured on fresh specimens, but rather at some time after extraction from culled hosts and after a period of preservation of the worms in chemical fixatives or by freezing. We carried out two experiments to assess the effects of freezing in Hanks' balanced salt solution, 70% or 80% ethanol and 10% formalin (both of the latter at room temperature and after storage at -80°C) on spicule length of Heligmosomoides bakeri at two time intervals after extraction from mice (Experiment 1, one and four weeks; Experiment 2, one and four months). In Experiment 1, no significant differences were detected, although there was some variation between treatments and over time. In Experiment 2, spicule length varied significantly between treatments and over time, the greatest shrinkage being in 80% ethanol and the least in 10% formalin. However, overall variation in spicule length was very limited, accounting for no more than 5.03% change in length over time and 4.95% between treatments at any of the periods of assessment. Therefore, while whole nematodes can shrivel and shrink in preservatives, making many measurements unreliable, our data indicated that spicule lengths are very little changed by preservation techniques over time, and so spicule length remains as a reliable taxonomic character.
线虫的刺形状和大小在亲缘关系密切的物种之间也存在差异，因此，刺是线虫分类学中区分物种的关键特征。刺通常不在新鲜标本上测量，而是在从淘汰的宿主中提取后，以及在化学固定剂或冷冻中保存一段时间后进行测量。我们进行了两项实验，以评估在汉克氏平衡盐溶液、70%或 80%乙醇和 10%福尔马林（两者均在室温下，然后在-80°C 下储存）中冷冻对从老鼠中提取后两个时间间隔的 Heligmosomoides bakeri 刺长度的影响（实验 1，提取后 1 周和 4 周；实验 2，提取后 1 个月和 4 个月）。在实验 1 中，尽管处理之间和随时间变化存在一些差异，但未检测到显着差异。在实验 2 中，处理之间和随时间变化的刺长度差异显着，在 80%乙醇中收缩最大，在 10%福尔马林中收缩最小。然而，刺长度的总体变化非常有限，在任何评估期内，长度变化不超过 5.03%，处理之间变化不超过 4.95%。因此，虽然整个线虫在保存剂中会枯萎和收缩，使许多测量变得不可靠，但我们的数据表明，刺长度随时间的保存技术变化很小，因此刺长度仍然是一个可靠的分类特征。
