Ordóñez-Grande Borja, Fernández-Alacid Laura, Sanahuja Ignasi, Sánchez-Nuño Sergio, Fernández-Borràs Jaume, Blasco Josefina, Ibarz Antoni
Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain.
Conserv Physiol. 2020 Dec 1;8(1):coaa095. doi: 10.1093/conphys/coaa095. eCollection 2020.
Fish skin mucus is composed of insoluble components, which form the physical barrier, and soluble components, which are key for interrelationship functions. Mucus is continuously secreted, but rates of production and exudation are still unknown, as are the underlying mechanisms. Using stable isotope analysis, here, we evaluate skin mucus turnover and renewal in gilthead sea bream, separating raw mucus and its soluble and insoluble fractions. Isotopic abundance analysis reveals no differences between mucus and white muscle, thus confirming mucus samples as reliable non-invasive biomarkers. Mucus production was evaluated using a single labelled meal packaged in a gelatine capsule, with both C and N, via a time-course trial. C was gradually allocated to skin mucus fractions over the first 12 h and was significantly (4-fold) higher in the soluble fraction, indicating a higher turnover of soluble mucus components that are continuously produced and supplied. N was also gradually allocated to mucus, indicating incorporation of new proteins containing the labelled dietary amino acids, but with no differences between fractions. When existent mucus was removed, dietary stable isotopes revealed stimulated mucus neoformation dependent on the components. All this is novel knowledge concerning skin mucus dynamics and turnover in fish and could offer interesting non-invasive approaches to the use of skin mucus production in ecological or applied biological studies such as climate change effects, human impact, alterations in trophic networks or habitat degradation, especially of wild-captured species or protected species.
鱼皮黏液由形成物理屏障的不溶性成分和对相互关系功能起关键作用的可溶性成分组成。黏液持续分泌，但其产生和渗出速率以及潜在机制仍不清楚。在此，我们利用稳定同位素分析评估了金头鲷皮肤黏液的更新和周转情况，分离出了原始黏液及其可溶性和不溶性部分。同位素丰度分析表明黏液和白肌之间没有差异，从而证实黏液样本是可靠的非侵入性生物标志物。通过一项时间进程试验，使用包裹在明胶胶囊中的单一标记餐（同时含有碳和氮）来评估黏液的产生。在最初的12小时内，碳逐渐分配到皮肤黏液部分，且在可溶性部分显著更高（4倍），这表明持续产生和供应的可溶性黏液成分周转更快。氮也逐渐分配到黏液中，表明含有标记膳食氨基酸的新蛋白质被整合进去，但各部分之间没有差异。当去除现存黏液后，膳食稳定同位素显示黏液的新形成受到成分的刺激。所有这些都是关于鱼类皮肤黏液动态和周转的新知识，并且可以为在生态或应用生物学研究（如气候变化影响、人类影响、营养网络变化或栖息地退化，特别是野生捕获物种或受保护物种的相关研究）中利用皮肤黏液产生提供有趣的非侵入性方法。
