Faculty of Science, Technology and Engineering, University of Suffolk, James Hehir Building, University Avenue, Ipswich, Suffolk, IP3 0FS, UK.
Faculty of Science, Technology and Engineering, University of Suffolk, James Hehir Building, University Avenue, Ipswich, Suffolk, IP3 0FS, UK.
Zoology (Jena). 2020 Dec;143:125833. doi: 10.1016/j.zool.2020.125833. Epub 2020 Aug 14.
Stages of the moult cycle of the amphipod Gammarus pulex have been previously characterised based on the examination of either apolysis of the 3 dactyl, or the whole body and eye appearance. In the current study the aim was to compare these two established moult staging techniques with a novel X-ray micro-computed tomography (micro-CT) scan method. The micro-CT provides information on the degree of calcification of the external integument and of the internal structures, such as the gastric mill. The degree of calcification is predicted to change during the moult cycle. Successful micro-CT scans were obtained from 80 G. pulex specimens and the radiological appearance of the 28 specimens immediately immersed in 4 % PFA were not different to the 52 specimens stored in 4 % PFA for at least 28 days prior to scanning. These specimens could be classified into moult stages A, B, C, early D or late D based on the degree of calcification. Good agreement was obtained between all three methods of moult stage classification if fresh specimens were used, but if specimens had been preserved in 4% Paraformaldehyde (PFA) for more than 24 hours the loss of colour from the whole body and eye meant these methods were not suitable. This is the first time that a micro-CT method has been used to study G. pulex and shows that this method of moult staging is accurate and reliable.
节肢动物的蜕皮周期阶段以前是通过检查 3 个跗节的解体，或整个身体和眼睛的外观来确定的。在目前的研究中，目的是将这两种已建立的蜕皮分期技术与一种新的 X 射线微计算机断层扫描（micro-CT）扫描方法进行比较。micro-CT 提供了关于外骨骼和内部结构（如胃磨）的钙化程度的信息。预计在蜕皮周期中钙化程度会发生变化。成功地对 80 个 G. pulex 标本进行了 micro-CT 扫描，并且立即浸入 4%多聚甲醛（PFA）中的 28 个标本的放射学外观与至少在扫描前 28 天储存在 4%PFA 中的 52 个标本没有不同。这些标本可以根据钙化程度分为 A、B、C、早期 D 或晚期 D 蜕皮阶段。如果使用新鲜标本，所有三种蜕皮阶段分类方法都能获得很好的一致性，但如果标本在 4%多聚甲醛（PFA）中保存超过 24 小时，整个身体和眼睛的颜色丧失意味着这些方法不合适。这是首次使用 micro-CT 方法研究 G. pulex，表明这种蜕皮阶段的方法是准确和可靠的。
