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

对当前环境或社会条件作出反应和适应的能力，在很大程度上取决于使行为、生理和神经发生变化的灵活性。一个非常有趣的领域是大脑在应对新挑战时的可塑性。这种能力的一个最好的例子是在鱼类身上看到的，它们能够从雌性变成雄性或从雄性变成雌性，无论是行为上还是表型上。这种情况发生在种群发生变化时，雄性或雌性的减少通过变化增加了繁殖能力。在社会控制性别变化和/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）中观察到这一点，蓝头濑鱼是一种加勒比海珊瑚礁鱼类，具有类似韭鱼的交配系统，在该系统中，领地终末阶段（T-TP）雄性捍卫产卵区域以获得雌性并与多个雌性繁殖。将T-TP雄性从产卵领地中移除会创造一个宽松的环境，导致最大的雌性发生性别变化，或最大的非领地雄性发生角色变化，无论是初始阶段（IP）雄性还是非领地末期（NT-TP）雄性。本研究将探讨雄激素在应对不断变化的社会影响中促进行为和表型变化的作用。这些类型的研究很重要，因为它们有能力证明社会互动的限制，以及大脑在限制消失或环境发生重大变化时的变化能力。在将一条T-TP雄性蓝头濑鱼移出其领地的几分钟到几小时内，最大的雌性、IP雄性或NT-TP雄性的大脑变化会诱发T-TP雄性的典型行为，比如雌性的求爱和针对其他雄性的激烈行为。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。在性别和角色的转变过程中，雌性和从属雄性在性腺转变过程中产生雄激素，特别是11KT。虽然先前的研究表明11KT的增加对行为改变不是必要的，但其他观察结果表明这种雄激素可能起着重要作用。神经肽血管催产素（哺乳动物血管加压素的同系物）似乎与早期行为改变有关。然而，11KT的存在是否会导致行为改变的早期发生，并增加T-TP男性典型行为的表现？NT-TP男性的11KT基线水平高于IP男性和女性，并且似乎更快地转变为T-TP男性的角色。11KT要为更快的角色转换负责吗？研究人员假设11KT促进了T-TP期男性在宽松的社会条件下的典型行为和基因表达谱。本研究将采用捕获/标记-释放/再捕获方法，通过性腺切除术和11KT植入进行激素操纵，标记个体的行为观察，11KT血清检测以及qRT-PCR基因表达分析相结合的方法，检验1)在允许条件下发生性别和角色变化的女性、IP男性和NT-TP男性之间，T-TP男性典型行为的时间、频率和持续时间是否存在显著差异；2)性腺存在影响性别和角色转换过程中T-TP雄性典型行为和血管催产素系统以及kisspeptin和促性腺激素释放激素两种神经肽系统的基因表达；3)11KT促进性别和角色转换过程中T-TP雄性典型行为和这些神经肽系统的基因表达。这项研究将有助于确定11KT是否为竞争成为领土表型的个体提供优势