Polyploidization, gene dosage, and the evolution of hormonal phenotypes

类固醇激素（肾上腺糖皮质激素和性腺类固醇）在生态学和行为学的背景下得到了广泛的研究，因为这些激素在介导对生存和繁殖至关重要的表型变化中发挥着不可或缺的作用。这些研究中最引人注目的发现之一是这些激素的调节存在多样性。例如，这些激素的循环水平和升高的糖皮质激素抑制性腺类固醇产生的程度在脊椎动物物种中都是高度可变的。本研究探讨肾上腺糖皮质激素和性腺类固醇的二倍体-多倍体树蛙物种复杂的了解如何多倍化（基因组的复制）有助于这种变化。多倍体化预计将推动激素调节的修改，因为相关的基因拷贝数的变化可以引入新的基因表达模式和/或增加突变率，改变基因产物的表达，控制激素水平和激素相互作用。拟议的研究是相关的了解激素调节的变化的广泛模式，因为多倍性是脊椎动物的历史特征和活脊椎动物基因拷贝数变化的主要来源。这项研究将与赞助机构的夏季研究计划相结合，从STEM领域服务不足的群体中招募至少8名高中生参与该项目。该项目还涉及对本科生和研究生以及一名博士后助理的培训，他们将相互密切合作，与高中生和主要调查人员密切合作，通过同伴指导来交叉促进培训和职业发展。 肾上腺糖皮质激素和性腺类固醇的循环水平，以及这些激素之间的相互作用，在脊椎动物中有很大的差异，但引起这种多样性的遗传基础知之甚少。这项研究检查了多倍体的内分泌调节，以了解基因拷贝数的相关变化（即，基因剂量）有助于这种非凡的多样性。多倍体化和相关的基因剂量变化可以通过改变基因表达模式和/或增加基因突变率来显著影响表型的进化，但多倍体化如何有助于激素调节的修饰仍在很大程度上未被研究。拟议的工作检查调节肾上腺糖皮质激素和性腺类固醇在三个自然的四倍体灰树蛙谱系和他们的二倍体祖先，以了解多倍体化如何影响内分泌控制。通过表征激素水平和下丘脑-垂体-肾上腺/肾间和下丘脑-垂体-性腺轴之间的相互作用，比较类固醇受体和结合蛋白mRNA表达水平和序列，并检查类固醇结合蛋白水平和动力学在二倍体和四倍体树蛙，本研究将阐明如何通过多倍体化影响激素调节的基因剂量的变化。这项研究的更广泛的影响包括不同的学生参与领域和实验室为基础的跨学科研究内分泌学，遗传学和神经科学。该奖项反映了NSF的法定使命，通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Steroid hormones (adrenal glucocorticoids and gonadal steroids) have been extensively studied in the context of ecology and behavior because of the integral roles these hormones play in mediating phenotypic changes that are crucial for survival and reproduction. One of the most striking findings emerging from such studies is the diversity that exists with respect to regulation of these hormones. For example, circulating levels of these hormones and the extent to which elevated glucocorticoids suppress the production of gonadal steroids are both highly variable across vertebrate species. This study examines adrenal glucocorticoids and gonadal steroids in a diploid-polyploid treefrog species complex to understand how polyploidization (duplication of the genome) contributes to this variation. Polyploidization is expected to drive modifications in hormonal regulation because associated changes in gene copy number can introduce novel gene expression patterns and/or increase rates of mutation that alter the expression of gene products governing hormone levels and hormonal interactions. The proposed study is relevant to understanding broad patterns of variation in hormonal regulation because polyploidy is a historical feature of vertebrates and a major source of variation in gene copy number in living vertebrates. This research will be integrated with summer research programs at the sponsoring institution to recruit at least eight high-school students from groups underserved in STEM fields to participate in the project. The project also involves training of undergraduate and graduate students and one post-doctoral associate, who will work closely with one another, high- school students, and the principal investigators, to cross-foster training and career development through peer mentoring. Circulating levels of adrenal glucocorticoids and gonadal steroids, and interactions between these hormones, are remarkably variable across vertebrates, but the genetic underpinnings giving rise to this diversity are poorly understood. This study examines endocrine regulation in polyploids to understand how associated changes in gene copy number (i.e., gene dosage) contribute to this extraordinary diversity. Polyploidization and associated changes in gene dosage can dramatically influence the evolution of the phenotype by altering gene expression patterns and/or by increasing gene mutation rates, but how polyploidization contributes to modifications in hormonal regulation remains largely unstudied. The proposed work examines regulation of adrenal glucocorticoids and gonadal steroids in three natural tetraploid gray treefrog lineages and their diploid ancestor to understand how polyploidization impacts endocrine control. By characterizing hormone levels and interactions between the hypothalamic-pituitary-adrenal/interrenal and hypothalamic-pituitary-gonadal axes, comparing steroid receptor and binding protein mRNA expression levels and sequences, and examining steroid binding protein levels and kinetics in diploid and tetraploid treefrogs, this study will elucidate how changes in gene dosage through polyploidization impact hormonal regulation. The broader impacts of this research include diverse student involvement in field and lab-based interdisciplinary research in endocrinology, genetics, and neuroscience. Rural high-school students will be recruited to participate in the research during summers and the impact of their experiences will be assessed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.