UCIBIO-Applied Molecular Biosciences Unit, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
Histochem Cell Biol. 2020 Sep;154(3):315-325. doi: 10.1007/s00418-020-01889-3. Epub 2020 Jun 7.
Either through differentiated glands or specialised individual cells, the coating epithelia of soft-bodied marine invertebrates are responsible for the secretion of a broad span of peptidic substances, from protective mucins to biocides. These secretions are characterised by the presence of cysteine-rich proteins and peptides, rendering a distinct histochemical signature of secretory epithelia. Through a histochemical procedure for fluorescence microscopy in paraffin sections, we performed a comparative assessment of the distribution of thiol-rich compounds in multiple epithelia of different species of intertidal Polychaeta, which revealed distinctive patterns of distribution that closely relate to ecology, morphoanatomy and physiology. The presence of free thiols was notorious in mucocytes and enzyme-plus toxin-secreting cells. Consequently, strong signals were recorded in the mucocytes of the parapodia of Nereis splendida, the epidermis and pharynx epithelium of Mysta picta and the venom glands of Glycera alba. The findings show an investment in mucus secretion in foragers such as Nereis and Mysta, especially the latter, which is not a native burrower, as a protective response and as lubricant for locomotion. Additionally, nereidids are believed to secret integumentary toxins for defence. On the other hand, Glycera is an ambush predatorial burrower whose behaviour entirely revolves around the delivery of venom making use of its four jaws. The results showed that the detection of thiol-rich compounds in histological sections can be a tool to identify potential toxin secretion and delivery structures, with important consequences for the bioprospecting of novel bioreactives from marine invertebrates for the purpose of drug discovery.
通过分化的腺体或专门的单个细胞，软体海洋无脊椎动物的覆盖上皮负责分泌广泛的肽类物质，从保护性粘蛋白到杀菌剂。这些分泌物的特点是含有富含半胱氨酸的蛋白质和肽，使分泌上皮具有独特的组织化学特征。通过石蜡切片荧光显微镜的组织化学程序，我们对不同潮间带多毛类动物的多种上皮中富含硫醇化合物的分布进行了比较评估，结果揭示了与生态学、形态解剖学和生理学密切相关的独特分布模式。在粘液细胞和酶加毒素分泌细胞中存在游离的巯基是众所周知的。因此，在 Nereis splendida 的副足粘液细胞、Mysta picta 的表皮和咽上皮以及 Glycera alba 的毒腺中记录到了强烈的信号。研究结果表明，觅食者（如 Nereis 和 Mysta）会大量分泌粘液，尤其是后者，它不是原生的洞穴生物，这是一种保护反应，也是运动的润滑剂。此外，沙蚕类动物被认为会分泌表皮毒素进行防御。另一方面，Glycera 是一种伏击性的洞穴捕食者，它的行为完全围绕着毒液的释放，利用它的四个下颚。研究结果表明，在组织学切片中检测富含硫醇的化合物可以成为识别潜在毒素分泌和输送结构的工具，这对从海洋无脊椎动物中寻找新型生物反应物质以进行药物发现具有重要意义。
