EXPRESSION OF THE UBIQUITIN GENES OF TRYPANOSOMA CRUZI

锥虫科的寄生原虫 世界范围内各种脊椎动物的疾病， 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大部分地区流行 美国有两千多万人深受其害。虽然这种疾病 在北美基本上没有，克氏锥虫是土生土长的 美国西南部的部分地区。 克氏锥虫有一个复杂的生命周期，包括强制性的 昆虫媒介和哺乳动物体内的发育阶段 主持人。这些阶段包括不分裂的锥虫。 (在昆虫媒介和宿主的血液中都有发现) 以及分裂的上胚体(仅在昆虫中 载体)和胞内无鞭毛体。仅有的表单能够 入侵的脊椎动物细胞是不分裂的锥虫体。 对遗传机制的理解 对发育周期的控制无疑会增加 对我们理解这一类生物的生物学意义重大 原生动物。为了阐明这些遗传机制，我们有 选择研究多泛素(PUB)和 克鲁兹毛滴虫泛素融合(FUS)基因。这些基因是被选中的 因为许多已知的调节它们在体内表达的因素 寄生虫也会遇到其他真核生物。 作为其发育生命周期或变化的结果 在传播过程中经历的生长条件。我们的 以前的工作已经证明，这些基因是顺从的 调节以应对环境压力或改变生长 条件。此外，我们还证明了至少有两个酒吧基因 前面是包含与热量同源的DNA序列 在其他有机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，启动子和 调控序列必须首先被识别和表征。 尚未确定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 初级转录产物的鉴定和鉴定 酒馆的产品和FUS基因。通过将其5‘末端映射到 包含潜在启动子的初级转录本 和/或监管区域将被确定。这些地区将是 根据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.