Preuss Anika, Appel Esther, Gorb Stanislav N, Büsse Sebastian
Department of Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Am Botanischen Garten 9, 24118 Kiel, Germany.
Department for Cytology and Evolutionary Biology, Zoological Institute and Museum, University of Greifswald, Soldmannstr. 23, 17489 Greifswald, Germany.
Interface Focus. 2024 Apr 12;14(2):20230076. doi: 10.1098/rsfs.2023.0076. eCollection 2024 Apr 15.
The arthropod cuticle offers strength, protection, and lightweight. Due to its limit in expandability, arthropods have to moult periodically to grow. While moulting is beneficial in terms of parasite or toxin control, growth and adaptation to environmental conditions, it costs energy and leaves the soft animal's body vulnerable to injuries and desiccation directly after ecdysis. To investigate the temporal change in sclerotization and pigmentation during and after ecdysis, we combined macrophotography, confocal laser scanning microscopy, scanning electron microscopy and histological sectioning. We analysed the tarsal and mandibular cuticle of the blue emperor dragonfly to compare the progress of tanning for structures that are functionally involved during emergence (tarsus/tarsal claws) with structures whose functionality is required much later (mandibles). Our results show that: (i) the tanning of the tarsal and mandibular cuticle increases during emergence; (ii) the tarsal cuticle tans faster than the mandibular cuticle; (iii) the mandibles tan faster on the aboral than on the oral side; and (iv) both the exo- and the endocuticle are tanned. The change in the cuticle composition of the tarsal and mandibular cuticle reflects the demand for higher mechanical stability of these body parts when holding on to the substrate during emergence and during first walking or hunting attempts.
节肢动物的角质层提供强度、保护和轻便性。由于其可扩展性有限，节肢动物必须定期蜕皮以生长。虽然蜕皮在控制寄生虫或毒素、生长以及适应环境条件方面有益，但它需要消耗能量，并且在蜕皮后会使柔软的动物身体直接容易受到伤害和脱水。为了研究蜕皮期间和之后硬化和色素沉着的时间变化，我们结合了宏观摄影、共聚焦激光扫描显微镜、扫描电子显微镜和组织切片技术。我们分析了蓝帝王蜻蜓的跗节和下颚角质层，以比较在羽化过程中功能上起作用的结构（跗节/跗爪）与功能需求在更晚时候才出现的结构（下颚）的鞣化进程。我们的结果表明：（i）跗节和下颚角质层的鞣化在羽化过程中增加；（ii）跗节角质层的鞣化比下颚角质层快；（iii）下颚在背侧比在口侧鞣化得更快；（iv）外表皮和内表皮都发生了鞣化。跗节和下颚角质层组成的变化反映了在羽化过程中以及首次行走或捕食尝试期间，这些身体部位在附着于基质时对更高机械稳定性的需求。
