Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Faculty of Science, The Hebrew University of Jerusalem, Jerusalem, Israel.
Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway.
BMC Biol. 2020 Sep 9;18(1):121. doi: 10.1186/s12915-020-00855-8.
In cnidarians, antagonistic interactions with predators and prey are mediated by their venom, whose synthesis may be metabolically expensive. The potentially high cost of venom production has been hypothesized to drive population-specific variation in venom expression due to differences in abiotic conditions. However, the effects of environmental factors on venom production have been rarely demonstrated in animals. Here, we explore the impact of specific abiotic stresses on venom production of distinct populations of the sea anemone Nematostella vectensis (Actiniaria, Cnidaria) inhabiting estuaries over a broad geographic range where environmental conditions such as temperatures and salinity vary widely.
We challenged Nematostella polyps with heat, salinity, UV light stressors, and a combination of all three factors to determine how abiotic stressors impact toxin expression for individuals collected across this species' range. Transcriptomics and proteomics revealed that the highly abundant toxin Nv1 was the most downregulated gene under heat stress conditions in multiple populations. Physiological measurements demonstrated that venom is metabolically costly to produce. Strikingly, under a range of abiotic stressors, individuals from different geographic locations along this latitudinal cline modulate differently their venom production levels.
We demonstrate that abiotic stress results in venom regulation in Nematostella. Together with anecdotal observations from other cnidarian species, our results suggest this might be a universal phenomenon in Cnidaria. The decrease in venom production under stress conditions across species coupled with the evidence for its high metabolic cost in Nematostella suggests downregulation of venom production under certain conditions may be highly advantageous and adaptive. Furthermore, our results point towards local adaptation of this mechanism in Nematostella populations along a latitudinal cline, possibly resulting from distinct genetics and significant environmental differences between their habitats.
在刺胞动物中，与捕食者和猎物的拮抗相互作用是由它们的毒液介导的，毒液的合成可能代价高昂。由于环境条件的不同，毒液产生的潜在高成本被假设为导致种群特异性毒液表达的差异。然而，环境因素对毒液产生的影响在动物中很少被证明。在这里，我们探索了特定的非生物压力对生活在广泛地理范围内的河口区的海葵 Nematostella vectensis（Actiniaria，Cnidaria）的不同种群的毒液产生的影响，在这些地区，温度和盐度等环境条件变化很大。
我们用热、盐度、UV 应激源和这三种因素的组合来挑战 Nematostella 水螅体，以确定非生物应激源如何影响从该物种分布范围内采集的个体的毒素表达。转录组学和蛋白质组学显示，在多个种群中，高度丰富的毒素 Nv1 在热应激条件下是下调最明显的基因。生理测量表明，毒液的产生在代谢上是昂贵的。引人注目的是，在一系列非生物应激源下，来自该纬度梯度不同地理位置的个体在调节其毒液产生水平方面存在差异。
我们证明了非生物应激会导致 Nematostella 中的毒液调节。结合其他刺胞动物物种的轶事观察，我们的结果表明这可能是刺胞动物的普遍现象。跨物种的应激条件下毒液产生的减少，加上 Nematostella 中证据表明其代谢成本高，表明在某些条件下下调毒液产生可能具有高度优势和适应性。此外，我们的结果表明，在 Nematostella 种群中，这种机制可能存在沿纬度梯度的局部适应，可能是由于它们栖息地之间的遗传差异和显著的环境差异所致。
