von Byern Janek, Dorrer Victoria, Merritt David J, Chandler Peter, Stringer Ian, Marchetti-Deschmann Martina, McNaughton Andrew, Cyran Norbert, Thiel Karsten, Noeske Michael, Grunwald Ingo
Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.
University of Vienna, Faculty of Life Science, Core Facility Cell Imaging & Ultrastructure Research, Vienna, Austria.
PLoS One. 2016 Dec 14;11(12):e0162687. doi: 10.1371/journal.pone.0162687. eCollection 2016.
Animals use adhesive secretions in a plethora of ways, either for attachment, egg anchorage, mating or as either active or passive defence. The most interesting function, however, is the use of adhesive threads to capture prey, as the bonding must be performed within milliseconds and under unsuitable conditions (movement of prey, variable environmental conditions, unfavourable attack angle, etc.) to be nonetheless successful. In the following study a detailed characterization of the prey capture system of the world-renowned glowworm group Arachnocampa from the macroscopic to the ultrastructural level is performed. The data reveal that the adhesive droplets consist mostly of water and display hygroscopic properties at varying humidity levels. The droplet core of Arachnocampa luminosa includes a certain amount of the elements sodium, sulphur and potassium (beside carbon, oxygen and nitrogen), while a different element composition is found in the two related species A. richardsae and A. tasmaniensis. Evidence for lipids, carbohydrates and proteins was negative on the histochemical level, however X-ray photoelectron spectroscopy confirm the presence of peptides within the droplet content. Different to earlier assumptions, the present study indicates that rather than oxalic acid, urea or uric acid are present in the adhesive droplets, presumably originating from the gut. Comparing the capture system in Arachnocampa with those of orb-spiders, large differences appear not only regarding the silky threads, but also, in the composition, hygroscopic properties and size of the mucous droplets.
动物以多种方式使用粘性分泌物，用于附着、固定卵、交配或作为主动或被动防御。然而，最有趣的功能是利用粘性丝线捕获猎物，因为这种结合必须在几毫秒内且在不利条件下（猎物移动、环境条件多变、攻击角度不利等）完成，才能成功。在下面的研究中，从宏观到超微结构水平对世界著名的萤火虫类群Arachnocampa的猎物捕获系统进行了详细的表征。数据显示，粘性液滴主要由水组成，并在不同湿度水平下表现出吸湿特性。Arachnocampa luminosa的液滴核心除了碳、氧和氮之外，还含有一定量的钠、硫和钾元素，而在两个相关物种A. richardsae和A. tasmaniensis中发现了不同的元素组成。在组织化学水平上，脂质、碳水化合物和蛋白质的证据为阴性，然而X射线光电子能谱证实液滴内容物中存在肽。与早期假设不同，本研究表明粘性液滴中存在的不是草酸、尿素或尿酸，推测这些物质源自肠道。将Arachnocampa的捕获系统与圆蛛的捕获系统进行比较，不仅在丝线方面存在很大差异，而且在粘液滴的组成、吸湿特性和大小方面也存在很大差异。
