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、吸引配偶和识别亲缘关系。对特定气味做出反应的神经元投射到大脑嗅球中独立的肾小球团中。这些肾小球是气味识别的功能单位，对肾小球模式的研究是评估对特定气味的反应性的一个有价值的工具。了解肾小球与特定高级大脑结构的联系是动物对气味反应的一个指标。最近的研究揭示了斑马鱼肾小球的定位和功能，但关于非模式鱼嗅觉系统的功能组织却知之甚少。这项研究计划的目标是绘制出三种鱼类：七鳃鳗、鲑鱼和圆虎鱼的嗅觉系统的肾小球功能。嗅觉在海鳗这种基本脊椎动物的行为引导中起着主导作用。鲑鱼和虎鱼都是硬骨鱼。鲑鱼在产卵迁徙过程中利用嗅觉信号，而虎鱼则利用嗅觉信号来吸引配偶。七鳃鳗有不同的主、副嗅觉亚系统，硬骨鱼的嗅觉上皮由不同类型的嗅觉神经元组成的单一嗅觉系统。有三个目标。目标1集中在内侧肾小球。在七鳃鳗中，这些细胞包含来自辅助嗅觉器官的输入和到控制运动的神经继电器的神经输出。目的1a研究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做出反应而刺激运动的多面手。目的1b探索鲑鱼和虎鱼嗅觉神经元隐窝细胞的球状小球，因为这些细胞可能投射到内侧小球，在繁殖和亲缘识别过程中输入嗅觉信息。目标2是比较四个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，侧肾小球似乎专门负责氨基酸的化学接收。目标3是通过绘制这三种鱼的肾小球来合成鱼类的球状组织。这些映射将包括嗅觉感觉神经元输入、肾小球组织、气味映射和输出投影。这一知识对于理解在自然选择压力下生存的物种嗅觉系统组织背后的神经生物学是重要的。嗅觉功能的知识对于鱼类种群的管理、保护和栖息地恢复也很有价值。例如，嗅觉的神经生物学在昆虫中得到了特别好的描述，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.