Spano F, Crisanti A
Istituto di Parassitologia, Università di Roma "La Sapienza", P. le A. Moro, 5, Box 6 Roma 62, 00185, Rome, Italy.
Int J Parasitol. 2000 Apr 10;30(4):553-65. doi: 10.1016/s0020-7519(99)00188-5.
The coccidium Cryptosporidium parvum is an obligate intracellular parasite of the phylum Apicomplexa. It infects the gastrointestinal tract of humans and livestock, and represents the third major cause of diarrhoeal disease worldwide. Scarcely considered for decades due to its apparently non-pathogenic nature, C. parvum has been studied very actively over the last 15 years, after its medical relevance as a dangerous opportunistic parasite and widespread water contaminant was fully recognised. Despite the lack of an efficient in vitro culture system and appropriate animal models, significant advances have been made in this relatively short period of time towards understanding C. parvum biology, immunology, genetics and epidemiology. Until recently, very little was known about the genome of C. parvum, with even basic issues, such as the number and size of chromosomes, being the object of a certain controversy. With the advent of pulsed field gradient electrophoresis and the introduction of molecular biology techniques, the overall structure and fine organisation of the genome of C. parvum have started to be disclosed. Organised into eight chromosomes distributed in a very narrow range of molecular masses, the genome of C. parvum is one of the smallest so far described among unicellular eukaryotic organisms. Although fewer than 30 C. parvum genes have been cloned so far, information about the overall structure of the parasite genome has increased exponentially over the last 2 years. From the first karyotypic analyses to the recent development of physical maps for individual chromosomes, this review will try to describe the state-of-the-art of our knowledge on the nuclear genome of C. parvum and will discuss the available experimental evidence concerning the presence of extra-chromosomal elements.
微小隐孢子虫是顶复门的专性细胞内寄生虫。它感染人类和家畜的胃肠道，是全球第三大致腹泻病病因。由于其明显的非致病性，几十年来几乎未被关注，在其作为危险的机会性寄生虫和广泛的水源污染物的医学相关性被充分认识后，微小隐孢子虫在过去15年里得到了非常积极的研究。尽管缺乏有效的体外培养系统和合适的动物模型，但在这相对较短的时间内，在了解微小隐孢子虫的生物学、免疫学、遗传学和流行病学方面已取得了重大进展。直到最近，人们对微小隐孢子虫的基因组知之甚少，甚至像染色体数量和大小等基本问题都存在一定争议。随着脉冲场梯度电泳的出现和分子生物学技术的引入，微小隐孢子虫基因组的整体结构和精细组织开始被揭示。微小隐孢子虫的基因组由八条染色体组成，分布在非常窄的分子量范围内，是迄今为止在单细胞真核生物中描述的最小基因组之一。尽管到目前为止克隆的微小隐孢子虫基因不到30个，但在过去两年里，关于该寄生虫基因组整体结构的信息呈指数级增长。从首次核型分析到最近单个染色体物理图谱的绘制，本综述将试图描述我们对微小隐孢子虫核基因组的最新认识，并讨论有关染色体外元件存在的现有实验证据。
