Molecular factors of female high-fertility - a study of two outbred mouse lines selected for increased female reproductive performance

高生育率的因素只是描述得很差。大多数具有生殖表型的转基因或基因敲除模型是亚可育或不育的。只有少数基因型别与生育力增强(0.2%)或产仔数增加(1%)有关。因此，我们缺乏高生育率的模式。在这项研究中，我们通过使用两个世界上唯一的高繁殖力小鼠模型来改变这一观点。与未选择的对照系(Ctrl)相比，这些小鼠的产仔数和每窝的总出生体重几乎翻了一番，后代没有生长迟缓的迹象。这个项目的目的是描述这些选择系从表型到基因改变的并行特征。先驱研究表明，这两种卵子都能排出更多的卵母细胞。因此，我们假设(I)卵泡池的大小发生了变化(升高的卵泡池模型)或(Ii)由于在选择过程中下丘脑-垂体-性腺轴(HPG轴)的激素变化(超排模型)，排卵的卵泡数量增加。这两个假说都将在不同的卵巢发育阶段进行测试，确定卵泡池的大小，并分析HPG轴的内分泌变化。目前尚不清楚排卵卵巢在180多代后仍保持其特征。将FLS和Ctrl品系进行平行比较，将为揭示高育性现象的复杂性和多样性提供新的信息。整体基因表达方法将绘制一幅关于表型如何得到保证的全球图景。这些网络将与现有的基于QTL分析的数据进行比较，以产生潜在的候选基因或提高生育力的基因标记。鲜艳的甲酚蓝(BCB)超生命染色确定葡萄糖-6-磷酸脱氢酶(G6PDH)的活性，是卵母细胞成熟和发育能力的标志。初步实验表明，Fl1和Fl2小鼠从有腔卵泡中分离的卵母细胞中G6PDH活性降低。我们将通过试管受精实验来测试这些差异是否是提高生育率的促成因素。除了这些功能研究外，我们还将分析所有三个小鼠系的卵母细胞蛋白质组，根据它们的BCB状态来研究G6DPH活性降低的下游影响。通过从表型到基因的平行分析这两种FLS，我们期待着对卵巢的生理适应和受影响的基因以及生育力增加的生物特征有新的基本见解。此外，我们推测，这些基因和途径的调节，以维持高生育能力也是重要的表型下降的生育能力。因此，我们认为这项工作是进一步研究利用基因敲除/-in研究高育性表型的基础，并将测试其他物种的多产标记列表。

Factors of high-fertility are just poorly described. The majority of transgenic or knockout models with a reproductive phenotype is subfertile or sterile. Only a minority of genotypes is linked with enhanced fertility (0.2%) or increased litter size (1%). Thus, we are lacking of high-fertility models. In this study we change the perspective by using two worldwide unique mouse models fertility line (FL) 1 and FL2 selected for high-fertility. These mice almost doubled the number of littermates as well as the total birth weight per litter in comparison to an unselected control line (Ctrl) with no signs of growth retardation in the offspring. The aim of this project is to characterize these selection lines in parallel from phenotypic to genotypic alterations. Pioneer studies reveal both FLs ovulate more oocytes. Hence, we hypothesize that (i) the size of the follicle pool has changed (elevated follicle pool model) or (ii) the amount of ovulated follicles increased due to hormonal alterations in the hypothalamic-pituitary-gonad axis (HPG axis) during selection process (superovulation like model). Both hypotheses will be tested on different ovarian developmental stages determining the follicle pool size and in addition analysing for endocrine alteration of the HPG axis.Currently it is unknown how high ovulating ovaries are maintained their characteristics after more than 180 generations. Comparing both FLs and Ctrl line in parallel will provide new information of the complexity and diversity of the phenome high-fertility. The holistic gene expression approach will draw a global picture of how the phenotype is warranted. These networks will be compared with already existing data based on QTL analysis to generate a list of potential candidate genes or gene markers of increased fertility.Brilliant cresyl blue (BCB) supravital staining determines the activity of glucose-6-phosphate dehydrogenase (G6PDH) and is a marker of oocyte maturation and developmental competence. Pilot experiments reveal FL1 and FL2 mice have decreased activity of G6PDH in oocytes isolated from antral follicles. We will test if these differences are contributing factors of increased fertility using IVF experiments. In addition to these functional studies we will analyse the oocyte proteome of all three mouse lines in dependence of their BCB-status for downstream effects of decreased G6DPH activity.By analysing both FLs in parallel from the phenotype to the genotype we expect new basic insights into physiological adaptations of the ovary and affected genes and biosignatures of increased fertility. In addition we hypothesize that those genes and pathways regulated to maintain high fertility are also of importance to the phenotype reduced fertility. Hence we consider the work as a basis for further investigations to study the phenotype of high-fertility using gene knockout/-in and will test the list of prolificacy markers in other species.