GENETIC DETERMINANTS OF STEROID HORMONE BIOSYNTHESIS

我们建议使用遗传学方法来研究 不同性别间睾酮生物合成途径酶的差异 间质细胞产生睾酮的能力。要做到这一点 摘要目的利用纯化的Leydig进行多种实验研究。 来自许多品系的近亲交配小鼠(祖先品系)的细胞，以及 从这些祖代衍生的各种重组自交系 菌株。我们将首先调查不同的近交系 睾丸间质细胞产生睾酮的能力显著增强。我们会 同时调查睾丸激素活性水平的差异 与光滑内质网相关的生物合成酶 (Ser)、3β-羟基类固醇脱氢酶异构酶、17α-羟基酶、 C17-20裂解酶和17-酮类固醇还原酶。的适当RI线 品系间差异最大的祖先菌株 睾酮的产生和一种或多种酶的最大活性 将被分析为表型的协同分离。国际扶轮线路也将 用来估计负责最大值的基因的数量 睾酮的产生，编码睾丸激素的基因的染色体位置 酶以及编码这些酶的基因之间可能存在的联系。最后， 我们将调查许多近亲繁殖的小鼠品系的不同酶 关于明显可检测的质量特征，例如 热稳定性或电泳性。在生理上的这种差异 特征是结构性基因变异的标志。这种方法 应在不诉诸环境扰动的情况下确定是否 基因决定的任何一种活动水平的变异 SER的酶的酶导致能力的变化 间质细胞产生睾丸激素。

We propose to use a genetic approach to investigate the influence of differences in enzymes of the testosterone biosynthetic pathway on the capacity of Leydig cells to produce testosterone. To accomplish this objective a variety of experiments have been designed using purified Leydig cells from numerous strains of inbred mice (progenitor strains), as well as various recombinant inbred (RI) lines derived from these progenitor strains. We will survey first for inbred strains which differ significantly in Leydig cell capacity for testosterone production. We will also survey for differences in the level of activities of the testosterone biosynthetic enzymes associated with the smooth endoplasmic reticulum (SER), 3Beta-hydroxysteroid dehydrogenase-isomerase, 17Alpha-hydroxylase, C17-20 lyase and 17-ketosteroid reductase. The appropriate RI lines of the progenitor strains with the greatest interstrain differences for maximum testosterone production and maximal activity of one or more of the enzymes will be analyzed for cosegregation of phenotypes. The RI lines will also be used to estimate the number of genes responsible for maximum testosterone production, the chromosomal location of the genes encoding the enzymes and possible linkage of the genes encoding the enzymes. Finally, we will survey numerous inbred strains of mice for enzymes which differ with regard to clearly detectable qualitative characteristics such as thermostability or electrophoretic mobility. Such differences in physical characteristics are indicative of structural gene variants. This approach should establish, without resorting to environmental perturbation, whether genetically determined variations in the level of activity of any one of the enzymes of the enzymes of the SER result in a change in the capacity of Leydig cells to produce testosterone.