Gene expression studies in giardia lambia

多细胞生物体中的每个细胞，如人类，都包含相同的基因蓝图--那么，血细胞与肌肉细胞有什么不同呢？答案是遗传物质是如何被激活的。不同的细胞类型激活不同的一组基因，以制造特定细胞功能所特有的蛋白质。例如，血细胞会产生一种蛋白质，用于在体内输送氧气，而肌肉细胞会产生一种用于细胞收缩的蛋白质。这种差异基因激活的过程被称为基因表达。尽管基因表达的控制发生在细胞内的许多层面，但最常见的控制水平是在转录开始时。转录是制作特定基因“影印”的机制。这些拷贝被称为信使RNA(信使RNA)，它们是蛋白质生产的指令。转录的启动是通过特定因子的有序组装来严格控制的，这些因子识别并结合到称为启动子的区域中的特定DNA序列，这些启动子位于每个基因开始的前面。我对基因表达，特别是单细胞原生动物蓝氏贾第鞭毛虫的转录起始调控感兴趣。这种生物是世界范围内人类感染性腹泻的最常见原因，也是加拿大淡水的常见污染物。贾第虫是真核生物，就像人类细胞一样，因为它的基因位于细胞内一个称为细胞核的特殊隔间。然而，贾第虫体内控制转录启动的调控区域比人类细胞更小、更不复杂，而且与人类细胞相比，贾第虫体内启动转录前在这些区域组装所需的因子数量似乎大大减少。因此，对贾第鞭毛虫转录和基因表达的研究将是一个机会，可以在简化的生物系统中确定这些过程的基本要素。此外，这些研究可能确定贾第虫这些途径的独特方面，可以利用这些方面来开发改进和更有效的治疗贾第虫感染的方法。

Every cell within a multicellular organism, such as a human, contains the same genetic blueprint - so what makes a blood cell different from a muscle cell? The answer is how the genetic material is activated.  Different cell types activate different sets of genes to make proteins that are specific for the function of the particular cell.  For example, a blood cell would produce a protein for carrying oxygen through the body, while a muscle cell would produce a protein that is used for cell contraction.  The process of this differential gene activation is referred to as gene expression.  The control of gene expression occurs at many levels within a cell but the most common level of control is at the initiation of transcription.  Transcription is the mechanism that makes 'photocopies' of particular genes. These copies are called messenger RNA (mRNA), and they serve as the instructions for the production of proteins.  The initiation of transcription is tightly controlled through the orderly assembly of specific factors that recognize and bind to specific DNA sequences in regions called promoters, which precede the beginning of each gene.  I am interested in studying gene expression, in particular the regulation of transcription initiation in the single cell protozoan, Giardia lamblia.  This organism is the most common cause of infectious diarrhea in humans worldwide, and is a frequent contaminant of freshwaters in Canada.  Giardia is an eukaryote, like a human cell, because its genes are located in a special compartment within the cell called the nucleus.  However, the regulatory regions for the control of transcription initiation in Giardia are smaller and less complex than those in a human cell, and the number of factors that are required to assemble at these regions before transcription can initiate appears to be greatly reduced in Giardia compared to a human cell. Therefore, the study of transcription and gene expression in Giardia would be an opportunity to identify the bare essentials of these processes in a streamlined biological system.  Moreover, these studies may identify unique aspects of these pathways in Giardia that can be exploited to develop improved and more effective treatments of Giardia infections.