Molecular Regulation of Carbon Fixation in Oceanic Picoplankton

二磷酸核酮糖羧化酶加氧酶（RuBPCase）是地球上几乎所有碳固定的酶，也是世界海洋浮游植物中主要的羧化酶。此外，RuBPCase可能在调节一种温室气体二氧化碳方面发挥全球作用。了解这种酶的调节对于理解海洋初级生产的控制和浮游植物对环境扰动或长期变化的反应是重要的。Paul博士和他的合作者Tabita博士将专注于这种酶在沿海和少营养海洋环境中浮游生物中的分子调节。他们最近开发了一种从浮游植物中提取mRNA的方法，并在自然种群中检测了RuBPCase基因的表达。这些生物分子技术将用于研究RuBPCase基因在培养的聚藻属和原绿藻以及自然种群中的光依赖性调控。第二个目标是通过扩增RUBPCase mRNA，从自然种群中克隆和测序，鉴定和表征关键的初级生产者。mRNA的扩增将产生来自转录活性光养生物的克隆。序列数据将与RuBPCase数据库进行比对，以确定活性物种。如果遇到新的光养生物，将进行简约分析，将这些形式与它们进化上最接近的亲戚联系起来。总而言之，该项目将为RuBPCase基因对环境因子的调控提供基础信息，并鉴定海洋微浮游生物中的关键光营养生物。

Ribulose bisphosphate carboxylase-oxygenase (RuBPCase) is the enzyme responsible for nearly all carbon fixation on this planet and is the major carboxylating enzyme in the phytoplankton of the world's oceans. Additionally, RuBPCase may play a global role in modulating one of the greenhouse gases, CO2. Knowledge of the regulation of this enzyme is important for understanding control of primary production in the oceans and phytoplankton response to environmental perturbations or long term change. Dr. Paul and his collaborator, Dr. Tabita, will focus on the molecular regulation of this enzyme in picoplankton in coastal and oligotrophic oceanic environments. They have recently developed a method for extraction of mRNA from phytoplankton and have detected RuBPCase gene expression in natural populations. These biomolecular techniques will be used to study diel and light-dependent regulation of the RuBPCase gene in cultured Synechococcus spp. and prochlorophytes, and in natural populations. The second objective is to identify and characterize the key primary producers by amplifying RUBPCase mRNA for cloning and sequencing from natural populations. Amplification of mRNA will result in clones that originated from transcriptionally active phototrophs. Sequence data will be compared to RuBPCase data bases to identify the active species. If novel phototrophs are encountered, parsimony analysis will be performed to relate these forms to their evolutionary closest relative. In summary, the project will provide fundamental information on the control of the RuBPCase genes in response to environmental factors and identify key phototrophic organisms in oceanic picoplankton.