EXPRESSION OF THE UBIQUITIN GENES OF TRYPANOSOMA CRUZI

锥虫科的寄生原生动物 在世界范围内， 无脊椎动物和植物物种。 克氏锥虫 恰加斯病的病原体，是这个家族的成员。 恰加斯病在南部和中部的大部分地区都是地方病 影响了超过两千万的美国人。 虽然这种疾病 在北美基本上是不存在的，T. cruzi是土著， 美国西南部的部分地区。 T. cruzi有一个复杂的生命周期， 在昆虫媒介和哺乳动物中的发育阶段 主持人 这些阶段包括不分裂的锥鞭毛体 （在昆虫媒介和宿主的血流中发现） 以及分裂的外鞭毛体（仅在昆虫中 载体）和细胞内无鞭毛体。 唯一能够 侵入的脊椎动物细胞是不分裂的锥鞭毛体。 了解参与的遗传机制， 控制发展周期无疑会增加 对我们理解这类生物学意义重大 原生动物。 为了阐明这些遗传机制， 选择研究多聚泛素（PUB）的表达， 泛素融合基因（ubiquitin-fusion，FUS）。克鲁兹 这些基因被选中 因为许多已知的调节其表达的因子， 寄生虫遇到的其他真核生物 由于它们的发育生命周期或改变， 在传播过程中经历的生长条件。 我们 以前的工作已经证明这些基因是不稳定的， 受环境压力或生长变化的调节 条件 此外，我们已经表明，至少有两个PUB基因， 在DNA序列之前含有与热的同源性， 在其他生物体中发现的电击元素。 在基因调控之前 可以在分子水平上理解， 必须首先鉴定和表征调节序列。 尚未鉴定出任何蛋白质编码基因的启动子 因此，在锥虫中，我们首先将重点放在 初级转录本的鉴定和表征 PUB和FUS基因的产物。 通过绘制5'末端的 一级转录物，含有潜在启动子的区域 和/或监管区域。 这些地区将 基于它们的蛋白质结合特性进一步分析。

Parasitic protozoans of the family Trypanosomatidae cause disease on a world wide scale in a variety of verterbrate, inverterbrate, and plant species. Trypanosoma cruzi, the etiologic agent of Chagas' disease, is a member of this family. Chagas disease is endemic throughout much of South and Central America afflicting over twenty million people. While the disease is essentially absent from North America, T. cruzi is indigenous to portions of the southwestern United States. T. cruzi has a complex life cycle involving obligatory developmental stages within the insect vector and the mammalian host. These stages include the non-dividing trypomastigotes (found in both the insect vector and the blood stream of the host) as well as the dividing epimastigotes (exclusively in the insect vector) and intracellular amastigotes. The only forms capable of invading vertebrate cells are the non-dividing trypomastigotes. An understanding of the genetic mechanisms involved in the control of the developmental cycle will undoubtedly add significantly to our understanding of the biology of this class of protozoan. To elucidate these genetic mechanisms we have chosen to study the expression of the polyubiquitin (PUB) and ubiquitin-fusion (FUS) genes of T. cruzi. These genes were chosen because many of the factors known to regulate their expression in other eukaryotic organisms are encountered by the parasite either as a consequence of their developmental life cycle or alterations in the growth conditions experienced during transmission. Our previous work has demonstrated that these genes are deferentially regulated in response to environmental stress or altered growth conditions. Further we have shown that at least two PUB genes are preceded by DNA sequences containing homologies to the heat shock elements found in other organisms. Before gene regulation can be understood at the molecular level, promoters and regulatory sequences must first be identified and characterized. Promoters have not been identified for any protein coding genes in trypanosomes therefore, we shall initially focus on the identification and characterization of the primary transcription products of the PUB and FUS genes. By mapping the 5' termini of the primary transcripts, regions containing potential promoters and/or regulatory regions will be identified. These regions will be further analyzed based on their protein binding characteristics.