Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland.
Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
Sci Rep. 2024 Jul 4;14(1):15379. doi: 10.1038/s41598-024-65336-2.
Venom is a remarkable innovation found across the animal kingdom, yet the evolutionary origins of venom systems in various groups, including spiders, remain enigmatic. Here, we investigated the organogenesis of the venom apparatus in the common house spider, Parasteatoda tepidariorum. The venom apparatus consists of a pair of secretory glands, each connected to an opening at the fang tip by a duct that runs through the chelicerae. We performed bulk RNA-seq to identify venom gland-specific markers and assayed their expression using RNA in situ hybridisation experiments on whole-mount time-series. These revealed that the gland primordium emerges during embryonic stage 13 at the chelicera tip, progresses proximally by the end of embryonic development and extends into the prosoma post-eclosion. The initiation of expression of an important toxin component in late postembryos marks the activation of venom-secreting cells. Our selected markers also exhibited distinct expression patterns in adult venom glands: sage and the toxin marker were expressed in the secretory epithelium, forkhead and sum-1 in the surrounding muscle layer, while Distal-less was predominantly expressed at the gland extremities. Our study provides the first comprehensive analysis of venom gland morphogenesis in spiders, offering key insights into their evolution and development.
毒液是动物界中一种非凡的创新，然而包括蜘蛛在内的各种群体的毒液系统的进化起源仍然是个谜。在这里，我们研究了常见的家蛛 Parasteatoda tepidariorum 的毒液器官发生。毒液器官由一对分泌腺组成，每个分泌腺通过一条穿过螯肢的导管与毒牙尖端的开口相连。我们进行了大量的 RNA-seq 来鉴定毒液腺特异性标记物，并使用整体原位杂交实验在整个时间序列的全胚胎上检测它们的表达。这些结果表明，腺体原基在胚胎第 13 期出现在螯肢尖端，在胚胎发育结束时向近端推进，并在孵化后延伸到体腔前。在后期胚胎中重要毒素成分的表达开始标志着毒液分泌细胞的激活。我们选择的标记物在成年毒液腺中也表现出明显的表达模式：sage 和毒素标记物在分泌上皮中表达，forkhead 和 sum-1 在周围的肌肉层中表达，而 Distal-less 主要在腺体末端表达。我们的研究提供了蜘蛛毒液腺形态发生的首次全面分析，为它们的进化和发育提供了关键的见解。
