Molecular Basis of F2 Hybrid Breakdown

当遗传不同的群体杂交时，第一代（F1）杂交可能表现出高生产力（杂交活力），但随后的杂交世代（F2及以后）经常表现出生产力和适应性的丧失（杂交崩溃）。杂交崩溃是由于在种群中分化的基因之间的负相互作用，但是是哪些基因呢？该研究以海洋桡足动物加利福尼亚虎足（Tigriopus californicus）为模型系统，重点研究线粒体基因（位于母体遗传的小mtDNA中）与核基因组中线粒体基因之间的相互作用。产生大多数细胞能量的酶复合物是两种来源成分的混合物，因此负面的相互作用可能会影响能量产生和健康。将通过比较自然种群和种群间杂交的线粒体基因表达、酶活性和能量产生来评估这些特定相互作用在杂交破裂中的作用。核/线粒体基因相互作用是整个生物科学广泛关注的问题。了解mtDNA的序列变异如何导致线粒体功能的变化，可以为从种内生理变异和人类线粒体疾病到核移植克隆实验的成功率等一系列问题提供新的思路。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.