Molecular Basis of F2 Hybrid Breakdown

当遗传上不同的种群杂交时，第一代（F1）杂交种可能表现出高生产力（杂种活力），但随后的杂交后代（F2及以后）经常表现出生产力和适应性的损失（杂种崩溃）。 杂交失败是由于种群间分化的基因之间的负相互作用，但哪些基因？ 拟议的调查使用海洋桡足类，Tigriopus californicus，作为一个模型系统，并专注于线粒体基因（那些位于小，母系遗传的mtDNA）和那些位于核基因组之间的相互作用。 产生大部分细胞能量的酶复合物是来自两种来源的成分的混合物，因此负面的相互作用可能会影响能量的产生和适应性。 通过比较自然种群和种群间杂交种中线粒体基因表达、酶活性和能量产生，评估这些特定相互作用对杂交种崩溃的作用。核/线粒体基因相互作用在整个生物科学中受到广泛关注。 了解线粒体DNA序列变异如何导致线粒体功能的变化，可能会为从种内生理变异和人类线粒体疾病到核移植克隆实验成功率等问题提供新的线索。除了这些更广泛的科学应用之外，拟议的工作（以及研究中采用的实验方法）将作为各种推广活动的起点，包括公开讲座，分子生态学的大学课程开发以及由非营利环境教育组织实施的K-12实验室活动的开发。

When genetically divergent populations interbreed, first generation (F1) hybrids may show high productivity (hybrid vigor), but subsequent hybrid generations (F2 and beyond) frequently show a loss of productivity and fitness (hybrid breakdown). Hybrid breakdown is due to negative interactions among genes that have diverged between the populations, but which genes? The proposed investigations use the marine copepod, Tigriopus californicus, as a model system and focus on the interactions between mitochondrial genes (those located in the small, maternally-inherited mtDNA) and those located in the nuclear genome. The enzyme complexes that produce most cellular energy are mixes of components from both sources, so negative interactions may impact energy production and fitness. The role of these specific interactions on hybrid breakdown will be assessed by comparing mitochondrial gene expression, enzyme activities and energy production in natural populations and interpopulation hybrids. Nuclear/mitochondrial gene interactions are of broad interest throughout biological sciences. Understanding how sequence variation in mtDNA leads to changes in mitochondrial function may shed new light on issues ranging from intraspecific physiological variation and human mitochondrial disease to success rates of nuclear-transplant cloning experiments. In addition to these broader scientific applications, the proposed work (and the experimental methods employed in the research) will serve as starting points for diverse outreach activities including public lectures, university curriculum development in molecular ecology, and development of K-12 laboratory activities implemented by a not-for-profit environmental education organization.