The neuroethology of feeding in jellyfish

1.1.为了确定控制摄食的神经元，我们在水母中使用了磷酸MAPK抗体染色。通常，当神经元触发动作电位时，钙离子流入细胞内，导致MAPK/ERK信号通路激活，进而触发MAPK磷酸化为磷酸化MAPK(PMAPK)。因此，通过用pMAPK抗体对整个水母进行染色，我们可以识别激活的神经元。为了证明这种方法是有效的，我们用光刺激水母，并将pMAPK染色与保持在黑暗中的水母进行比较。这导致水母眼睛周围的神经元被强烈染色，但仅限于暴露在光下的动物。这证明抗pMAPK染色可以用于标记水母的活性神经元。不幸的是，当我们使用其他感官形式，如化学或机械刺激时，我们无法确定一个明确的模式。鉴定与水母摄食有关的基因为了更好地了解与水母摄食调控有关的基因，我们对饥饿和喂食的动物进行了RNA分析。通过这种方式，我们能够识别出数百个基因，当水母饿了或饱了时，这些基因的表达会更高。我们的假设是，这些基因中的一些可能参与了水母食欲的调节。使用生物信息学方法，我们能够识别潜在的保守基因，这些基因也在其他动物的食欲调节中发挥作用。

1.1. Neuronal activity mapping in the jellyfishTo identify neurons controlling feeding, we used phospho-MAPK antibody staining in the jellyfish. Typically, when a neuron fires an action potential, calcium flows into the cell, causing activation of the MAPK/ERK signaling pathway, which in turn triggers MAPK phosphorylation into phospho-MAPK (pMAPK). Thus, by staining whole jellyfish eith a pMAPK antibody, we can identify activated neurons. To prove that this approach works, we stimulated jellyfish with light and compared the pMAPK staining with jellyfish which remained in darkness. This resulted in strong staining of the neurons around the jellyfish eyes, but only for the animals that were exposed to light. This proves that anti-pMAPK staining can be used for labeling active neurons in jellyfish. Unfortunately, we were unable to identify a clear pattern when we used other sensory modalities, such as chemical or mechanical stimulation.1.2. Identification of genes involved in jellyfish feedingTo better understand the genes involved in the regulation of jellyfish feeding, we carried out RNA analyses in hungry and fed animals. In this way, we were able to identify hundreds of genes that become more highly expressed when the jellyfish is hungry or full. Our hypothesis is that some of these genes may be involved in the regulation of appetite in jellyfish. Using bioinformatics approaches, we were able to identify potentially conserved genes that also play a role in appetite regulation in other animals.