Diversity and Convergence in Fish Olfactory Subsystems

鱼类利用嗅觉进行摄食、警报反应、产卵迁移、配偶吸引和亲属识别。对特定气味有反应的神经元投射到大脑嗅球中独立的肾小球簇中。这些肾小球是气味辨别的功能单位，并且肾小球模式的研究是评估对特定气味的反应性的有价值的工具。了解肾小球与特定高级大脑结构的连接是动物对气味剂反应的指标。最近的研究揭示了很多关于肾小球映射和功能在斑马鱼，但相当少的是已知的非模式鱼的嗅觉系统的功能组织。这项研究计划的目标是绘制出三种鱼类嗅觉系统的肾小球功能：七鳃鳗，鲑鱼和圆虾虎鱼。嗅觉在指导七鳃鳗（一种基础脊椎动物）的行为中起着主导作用。鲑鱼和虾虎鱼都是硬骨鱼。鲑鱼利用嗅觉信号在产卵迁移和虾虎鱼使用嗅觉线索，以吸引配偶。七鳃鳗的嗅觉系统具有明显的主、副嗅觉子系统，硬骨鱼的嗅觉系统是单一的，不同类型的嗅觉感觉神经元混杂在一起。有三个目标。 目的1：研究中膜肾小球。在七鳃鳗中，这些包含来自辅助嗅觉器官的输入和到控制运动的神经中继的神经输出。目的探讨七鳃鳗副嗅器单个细胞的化学感受特性。这些发现将确定这些神经元是否是对许多气味刺激运动的多面手。目的1b探索鲑鱼和虾虎鱼嗅感觉神经元隐窝细胞的球小球，因为这些球小球可能投射到内侧小球，在生殖和亲属识别过程中输入嗅觉信息。目的二是比较四种非内侧肾小球的气味反应和神经投射。例如，从七鳃鳗到鲑鱼，侧肾小球似乎专门用于氨基酸化学感受。目的3是通过绘制这三种鱼的肾小球来合成鱼的延髓组织。这些地图将包括嗅觉感觉神经元输入，肾小球组织，气味映射和输出预测。这些知识对于理解在自然选择压力下生存的物种中嗅觉系统组织背后的神经生物学非常重要。嗅觉功能的知识也是有价值的鱼类种群的保护和栖息地恢复的管理。例如，嗅觉的神经生物学在昆虫中得到了很好的描述，由此产生的概念推动了害虫控制的新方法。

Fish utilize olfaction for feeding, alarm response, spawning migration, mate attraction and kin recognition. The neurons that respond to specific odorants project into separate glomerular clusters in the olfactory bulb of the brain. These glomeruli are the functional units of odorant discrimination, and the study of glomerular patterning is a valuable tool to assess the responsiveness to specific odorants. Knowledge of glomerular connections to specific higher brain structures is an indicator of the animal's response to an odorant. Recent studies have revealed much about glomerular mapping and functionality in zebrafish, however considerably less is known regarding the functional organization of the olfactory system in non-model fish. The goal of this research program is to map out glomerular function of the olfactory system in three fish: the sea lamprey, salmon and round goby. Olfaction has a dominant role in guiding behaviour in sea lamprey, a basal vertebrate. Both salmon and gobies are teleost fish. Salmon utilize olfactory signals during spawning migration and gobies use olfactory cues to attract mates. There are distinct main and accessory olfactory subsystems in lampreys, but a single olfactory system with different types of olfactory sensory neurons intermingling in the olfactory epithelium of teleost fish. There are three objectives.  Objective 1 focuses on medial glomeruli. In lampreys, these contain input from the accessory olfactory organ and neural output to a neural relay that controls movement. Objective 1a is to investigate chemoreceptive properties of individual cells in the lamprey accessory olfactory organ. The findings will determine if these neurons are generalists that stimulate movement in response to many odorants. Objective 1b is to probe for the bulbar glomeruli of olfactory sensory neuron crypt cells in salmon and goby, as these may project to medial glomeruli that input olfactory information during reproduction and kin recognition. Objective 2 is to compare odorant responses and neural projections for four non-medial glomeruli. For example, lateral glomeruli appear to be dedicated to amino acid chemoreception, from lampreys to salmon. Objective 3 is to produce a synthesis of bulbar organization in fish by mapping the glomeruli in these three fish. These maps will include olfactory sensory neuron input, glomerular organization, odorant mapping and output projections. This knowledge is important for understanding the neurobiology behind the organization of the olfactory system in species that survive under natural selection pressure. Knowledge of olfactory function is also valuable to the management of fish populations for conservation and habitat restoration. For example, the neurobiology of olfaction is particularly well described in insects and resulting concepts have driven novel approaches to pest control.