Collaborative Research: Integrative Approaches to Plant Cell Wall Digestion by Non holometabolous Insects

植物细胞壁含有难以降解的木质纤维化合物，如木聚糖、纤维素、半纤维素和果胶。然而，昆虫食草动物能够降解这些化合物，并使用从降解过程中获得能量的更简单的化合物。虽然早期的工作假设昆虫体内参与木质纤维素化合物(即植物细胞壁降解酶，PCWDE)生化分解的催化剂酶的来源是肠道共生细菌，但最近的工作表明，昆虫肠道细胞产生的PCWDE比以前认识的更重要。这项研究的目的是利用功能基因组学和生化测试相结合的方法来检查两个主要的低等昆虫谱系中PCWDE的多样性。这项基础研究将提高对昆虫消化生理机制的理解，并可能在昆虫控制方法、生物燃料工业改进和其他工业应用方面产生新的见解。这项工作将为本科生、高中生和研究生提供在尖端功能基因组学、昆虫生理学和生物化学方面获得经验的机会。博物馆将制作展品，教育公众有关取材昆虫的重要性。这些展品将在加州大学大卫·博哈特昆虫学博物馆以及加州和田纳西州的其他几个科学博物馆展出。初步工作表明，Phasmids(拐杖)和Thysanurans(银鱼和火虫)具有惊人数量的PCWDE，这些基因在肠道中显示隔室特异性表达，并有效地降解植物细胞壁化合物。该项目将确定焦点物种(6个节肢动物和3个胸腺动物)中存在的全部PCWDE，并比较它们在这些昆虫消化系统中的活动和表达水平。利用异源表达，研究人员将表征这些系统中最活跃的酶的活性。研究人员还将分析基因表达模式如何与肠道的物理属性相关，肠道的物理属性在两个焦点昆虫目之间差异很大。最终目标是描述消化系统生理分区的变化，并确定它如何与各种差异表达的酶协同工作，以最大限度地消化木质纤维化合物。这项研究的结果将发表在同行评议的期刊上，并在区域和国家科学会议上公布。

Plant cell walls contain lignocellulosic compounds that are difficult to degrade, such as xylan, cellulose, hemicellulose, and pectin. However, insect herbivores are capable of degrading these compounds and using the simpler compounds derived from the degradation processes for energy. While early work assumed that the source of the catalyst enzymes involved in the biochemical breakdown of lignocellulosic compounds (i.e., plant cell wall degradation enzymes, PCWDE) in insects was gut-resident symbiotic bacteria, recent work has shown that PCWDE produced by the cells of the insect gut are more important than previously realized. The goal of this research is to examine the diversity of PCWDE in two major lower insect lineages using a combination of functional genomics and biochemical tests. This basic research will improve understanding about the physiological mechanisms of insect digestion and may yield novel insights about insect control methods, biofuel industry improvements, and other industrial applications. This work will provide the opportunity for undergraduate, high school and graduate students to gain experience in cutting edge functional genomics, and insect physiology and biochemistry. Museum exhibits will be produced to educate the public about the importance of wood feeding insects. These exhibits will be presented at the University of California David Bohart Museum of Entomology and several other science museums across California and Tennessee. Preliminary work revealed that Phasmids (walking sticks) and Thysanurans (silverfish and firebrats) have strikingly high numbers of PCWDE, that these genes show compartment specific expression within the gut, and are effective at degrading plant cell wall compounds. This project will identify the full complement of PCWDE present in the focal species (6 Phasmids and 3 Thysanurans) and compare the activity and expression levels of them in the digestive systems of these insects. Using heterologous expression, the researchers will characterize the activity of the most active enzymes in these systems. The researchers will also analyze how patterns of gene expression correlate with the physical attributes of the gut, which vary greatly between the two focal insect orders. The ultimate goal is to describe the variation in physiological compartmentalization of the digestive system and determine how it works synergistically with a diversity of differentially-expressed enzymes to maximize digestion of lignocellulosic compounds. Findings from this research will be published in peer-reviewed journals, and presented at regional and national scientific meetings.