Weiss Linda C, Leese Florian, Laforsch Christian, Tollrian Ralph
Department of Animal Ecology, Evolution and Biodiversity, Ruhr University Bochum, Universitätsstrasse 150, Bochum 44801, Germany Environmental Genomics Group, School of Biosciences, University of Birmingham, Birmingham B18 2TT, UK
Department of Animal Ecology, Evolution and Biodiversity, Ruhr University Bochum, Universitätsstrasse 150, Bochum 44801, Germany Aquatic Ecosystem Research Group, University of Duisburg and Essen, Universitätsstrasse 5, Essen 45141, Germany.
Proc Biol Sci. 2015 Oct 7;282(1816):20151440. doi: 10.1098/rspb.2015.1440.
The waterflea Daphnia is a model to investigate the genetic basis of phenotypic plasticity resulting from one differentially expressed genome. Daphnia develops adaptive phenotypes (e.g. morphological defences) thwarting predators, based on chemical predator cue perception. To understand the genomic basis of phenotypic plasticity, the description of the precedent cellular and neuronal mechanisms is fundamental. However, key regulators remain unknown. All neuronal and endocrine stimulants were able to modulate but not induce defences, indicating a pathway of interlinked steps. A candidate able to link neuronal with endocrine responses is the multi-functional amine dopamine. We here tested its involvement in trait formation in Daphnia pulex and Daphnia longicephala using an induction assay composed of predator cues combined with dopaminergic and cholinergic stimulants. The mere application of both stimulants was sufficient to induce morphological defences. We determined dopamine localization in cells found in close association with the defensive trait. These cells serve as centres controlling divergent morphologies. As a mitogen and sclerotization agent, we anticipate that dopamine is involved in proliferation and structural formation of morphological defences. Furthermore, dopamine pathways appear to be interconnected with endocrine pathways, and control juvenile hormone and ecdysone levels. In conclusion, dopamine is suggested as a key regulator of phenotypic plasticity.
水蚤是研究由一个差异表达基因组导致的表型可塑性遗传基础的模型。水蚤基于对化学捕食者线索的感知，发育出抵御捕食者的适应性表型（如形态防御）。为了理解表型可塑性的基因组基础，对先前的细胞和神经元机制进行描述至关重要。然而，关键调节因子仍然未知。所有神经元和内分泌刺激物都能够调节但不能诱导防御，这表明存在一个相互关联的步骤途径。一种能够将神经元反应与内分泌反应联系起来的候选物质是多功能胺多巴胺。我们在此使用由捕食者线索与多巴胺能和胆碱能刺激物组成的诱导试验，测试了多巴胺在蚤状溞和长刺溞性状形成中的作用。仅应用这两种刺激物就足以诱导形态防御。我们确定了与防御性状紧密相关的细胞中多巴胺的定位。这些细胞作为控制不同形态的中心。作为一种有丝分裂原和硬化剂，我们预计多巴胺参与形态防御的增殖和结构形成。此外，多巴胺途径似乎与内分泌途径相互连接，并控制保幼激素和蜕皮激素水平。总之，多巴胺被认为是表型可塑性的关键调节因子。
