DISSERTATION RESEARCH: Androgen regulation of territorial male-typical behavior and neuropeptide gene expression during socially-induced sex and role change in a coral reef fish

论文研究：珊瑚礁鱼在社会诱导的性别和角色变化过程中雄激素对领地雄性典型行为和神经肽基因表达的调节

• 批准号: 1406863
• 负责人: John Godwin
• 金额: $ 1.88万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1406863&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Androgen; regulation; territorial

The ability to respond and adapt to current environmental or social condition, depends to a large extent of the flexibility to make behavioral, physiological and neurological changes. An area of great interest is the plasticity of the brain to change in response to new challenges. One of the greatest examples of this ability is seen in fish that are capable of switching from female-to-male or male-to-female either behavioral or phenotypically. This occurs when changes in the population, loss of males or females increase the ability to reproduce by changing. In species with socially-controlled sex change and/or role change, the brain perceives alterations in the social environment that indicate it is favorable for these changes and therefore "permissive". This is observed in the bluehead wrasse (Thalassoma bifasciatum), a Caribbean coral reef fish with a lek-like mating system in which territorial-terminal phase (T-TP) males defend spawning territories for access to females and breed with multiple females. Removal of a T-TP male from a spawning territory creates a permissive environment that induces sex change in the largest female or male role change in the largest non-territorial male, either an initial phase (IP) male or non-territorial-terminal phase (NT-TP) male. This research will examine the role androgen hormones in response to changing social influences to promote behavioral and phenotypic changes. These types of studies are important as they have the ability to demonstrate the constraint of social interactions and the brains ability to change to when constraints are left or there are major changes in the environment. Within minutes-to-hours of removing a bluehead wrasse T-TP male from its territory, changes in the brain of the largest female, IP male, or NT-TP male induce T-TP male-typical behaviors, such as courtship of females and agonistic behavior directed at other males. Changes in the brain also activate the hypothalamo-pituitary-gonadal (HPG) axis, causing transformation of female ovaries or IP male testes into TP male testes. Androgen production, particularly of 11KT, rises during gonadal transformation in both females and subordinate males during sex and role change. While previous studies show 11KT increases are not necessary for behavioral changes, other observations nevertheless suggest this androgen may play an important role. The neuropeptide vasotocin (homologue of vasopressin in mammals) appears responsible for early behavioral changes. However, could the presence of 11KT induce earlier onset of behavioral changes and increase the display of T-TP male-typical behaviors? NT-TP males have higher baseline levels of 11KT than IP males and females and appear to transition into the role of T-TP male faster. Is 11KT responsible for faster role change? The researchers hypothesize that 11KT promotes behaviors and gene expression profiles typical of T-TP phase males under permissive social conditions. Using a combination of capture/tag-and-release/recapture approaches, hormonal manipulations via gonadectomy and 11KT implantation, behavioral observations of tagged individuals, 11KT serum assays, and gene expression analysis via qRT-PCR, this study will test whether 1) significant differences exist in the timing, frequency, and duration of T-TP male-typical behaviors among females, IP males, and NT-TP males undergoing sex and role change under permissive conditions, 2) gonadal presence affects T-TP male-typical behaviors and gene expression of the vasotocin system and two other neuropeptide systems, kisspeptin and gonadotropin-releasing hormone, during sex and role change, and 3) 11KT promotes T-TP male-typical behaviors and gene expression of these neuropeptide systems during sex and role change. This study will help determine whether 11KT confers an advantage for individuals competing to become the territorial phenotype

响应和适应当前环境或社会条件的能力在很大程度上取决于做出行为、生理和神经变化的灵活性。 一个令人非常感兴趣的领域是大脑响应新挑战的可塑性。这种能力的最好例子之一是鱼类能够在行为或表型上从雌性转变为雄性或从雄性转变为雌性。当人口变化、雄性或雌性的丧失通过变化增加繁殖能力时，就会发生这种情况。在具有社会控制的性别变化和/或角色变化的物种中，大脑感知到社会环境的变化，表明它有利于这些变化，因此是“宽容的”。在蓝头濑鱼 (Thalassoma bifasciatum) 中观察到了这一点，蓝头濑鱼是一种加勒比珊瑚礁鱼类，具有类似 lek 的交配系统，其中领地末期 (T-TP) 雄性捍卫产卵领地以接近雌性，并与多个雌性繁殖。将T-TP雄性从产卵领地移走会创造一个宽松的环境，诱导最大雌性的性别变化或最大非领地雄性的雄性角色变化，无论是初始阶段（IP）雄性还是非领地末期（NT-TP）雄性。这项研究将探讨雄激素在应对不断变化的社会影响以促进行为和表型变化方面的作用。这些类型的研究很重要，因为它们能够证明社交互动的限制，以及大脑在限制消失或环境发生重大变化时发生变化的能力。 在将蓝头濑鱼 T-TP 雄性从其领地移走后的几分钟到几小时内，最大的雌性、IP 雄性或 NT-TP 雄性的大脑发生变化，诱导 T-TP 雄性典型的行为，例如对雌性的求爱和针对其他雄性的竞争行为。大脑的变化也会激活下丘脑-垂体-性腺 (HPG) 轴，导致女性卵巢或 IP 男性睾丸转变为 TP 男性睾丸。在性别和角色转变过程中，女性和从属男性的性腺转变过程中，雄激素的产生，尤其是 11KT 的产生都会增加。虽然之前的研究表明 11KT 的增加对于行为改变并不是必需的，但其他观察结果表明这种雄激素可能发挥着重要作用。神经肽加压素（哺乳动物加压素的同系物）似乎与早期行为变化有关。然而，11KT 的存在是否会导致行为改变更早发生并增加 T-TP 男性典型行为的表现？ NT-TP 男性比 IP 男性和女性具有更高的 11KT 基线水平，并且似乎更快地转变为 T-TP 男性角色。 11KT 负责更快的角色转换吗？研究人员推测，在宽松的社会条件下，11KT 可以促进 T-TP 阶段男性的典型行为和基因表达谱。通过结合捕获/标记-释放/重新捕获方法、通过性腺切除术和 11KT 植入进行的激素操作、标记个体的行为观察、11KT 血清测定以及通过 qRT-PCR 进行的基因表达分析，本研究将测试 1) 女性、IP 男性和 NT-TP 之间 T-TP 男性典型行为的时间、频率和持续时间是否存在显着差异 在允许的条件下经历性别和角色改变的男性，2) 性腺的存在在性别和角色改变过程中影响 T-TP 男性典型行为以及催产素系统和其他两种神经肽系统（Kisspeptin 和促性腺激素释放激素）的基因表达，以及 3) 11KT 在性别和角色改变期间促进 T-TP 男性典型行为和这些神经肽系统的基因表达 改变。这项研究将有助于确定 11KT 是否为竞争成为领地表型的个体带来优势