Dissertation Research: Functional Divergence of Cytochrome C Paralogs

线粒体电子传递链中的蛋白质由核和线粒体编码亚基组成，它们必须紧密相互作用。在果蝇中，超过五分之一的核编码亚基有第二个拷贝，只在睾丸中表达。本研究的目的是剖析一个这样的重复基因，细胞色素c近端和细胞色素c远端功能差异。为此提出的实验如下。1)测量在体细胞和睾丸中表达睾丸或体细胞色素c的转基因果蝇的适应度相关性。对于体细胞功能，将测量寿命，繁殖力和幼虫活力的性状。对于睾丸功能，将测量精子活力、精子数量和精子竞争能力等特征。2)通过量化组织特异性细胞色素c氧化酶在氧化睾丸或体细胞细胞色素c时的酶活性来测试组织特异性酶复合物的共适应。本研究整合了1)生殖进化，通过测量一种以前未研究过的生殖蛋白的生殖适应性特征，2)共适应进化，通过测试强迫非共适应分子相互作用引起的功能破坏和3)基因复制和亚功能化的进化，通过测量两个基因拷贝的功能差异。因此，研究结果将为广泛的研究人员提供信息，并将在其他松散关联的领域之间提供紧密联系。

Proteins in the mitochondrial electron transport chain are composed of both nuclear and mitochondrially encoded subunits that must tightly interact. In Drosophila, over one fifth of the nuclear encoded subunits have a second copy that is only expressed in the testes. This study aims to dissect the functional differences of one such duplicate gene, cytochrome-c proximal and cytochrome-c distal. The experiments proposed to test this are as follows. 1) Measure fitness correlates of transgenic flies expressing either testis or somatic cytochrome c in both the soma and testes. For somatic function the traits of lifespan, fecundity, and larval viability will be measured. For testis function the traits of sperm viability, sperm count and sperm competitive ability will be measured. 2) Test for coadaptation of tissue specific enzyme complexes by quantifying enzymatic activity of tissue specific cytochrome c oxidase when oxidizing either testis or somatic cytochrome c.This study integrates 1) reproductive evolution, by measuring reproductive fitness traits in a previously uninvestigated class of reproductive proteins, 2) evolution of coadaptation, by testing the functional disruption induced by forcing non-coadapted molecules to interact and 3) evolution of gene duplication and subfunctionalization, by measuring functional divergence of two gene copies. As such, findings will prove informative to a broad range of researchers and will provide tight connections between otherwise loosely affiliated fields.