最近，科学家发现，导致艾滋病人等罹患慢性腹泻的名为微孢子虫的真菌，在感染人和其它宿主动物时，能够进行有性繁殖，该发现有望帮助研究人员理解其“工作原理”并找到方法治疗上述疾病。相关研究结果刊登在近期出版的《当代生物学》（Current Biology）杂志上。
该论文的主要作者、杜克大学分子遗传学和微生物学博士后李颂昌（音译）说：“微孢子虫感染很难治疗，因为我们对其知之甚少，50%%的艾滋病患者遭遇微孢子真菌感染，引发慢性腹泻。这些感染也在旅行性腹泻病人、器官移植接受者和老人身上发现。”
微孢子虫病是一种人兽共患病，各年龄组均可受染，人类为孢子虫感染与宿主的免疫功能严重地受到抑制有密切关系，以前人们认为微孢子虫无有性生殖期。
杜克大学的研究人员使用两个基因研究证明，微孢子虫明显地从有性的真菌中进化，并且尤其同接合菌密切相关，他们发现，微孢子虫的2000多个基因中，有33个基因同接合菌一样，这些染色体标记显示，微孢子虫同接合菌很可能拥有共同的祖先，并且，它同其他已知的真菌联系更为疏远。另外，有性繁殖所包含的其他基因也在这两类真菌中出现，这表明，微孢子虫可能有一个遗传控制生殖周期，并且可能在感染宿主时开始进行有性繁殖。
研究人员接下来打算探究这些物种的有性繁殖，有性繁殖会导致更严重的感染，因为病原体使用宿主的细胞环境和体系，将其作为繁殖的安全港。该研究团队将会在培植细胞和线虫上进行试验，他们发现，线虫是微孢子虫的天然宿主。该研究由美国国家卫生研究院和加拿大卫生研究院资助。（生物谷Bioon.com）
生物谷推荐原始出处：
Current Biology，doi:10.1016/j.cub.2008.09.030，Soo Chan Lee, Joseph Heitman
Microsporidia Evolved from Ancestral Sexual Fungi
Soo Chan Lee1,Nicolas Corradi2,Edmond J. Byrnes1,Santiago Torres-Martinez3,Fred S. Dietrich1,4,Patrick J. Keeling2andJoseph Heitman1,,
1 Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
2 Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC V6T1Z4, Canada
3 Departamento de Genetica y Microbiologia, Facultad de Biologia, Universidad de Murcia, 30071 Murcia, Spain
4 Institute for Genome Sciences and Policy, Duke University, Durham, NC 27710, USA
SUMMARY
Microsporidia are obligate, intracellular eukaryotic pathogens that infect animal cells, including humans [[1]]. Previous studies suggested microsporidia share a common ancestor with fungi []. However, the exact nature of this phylogenetic relationship is unclear because of unusual features of microsporidial genomes, which are compact with fewer and highly divergent genes [[8]]. As a consequence, it is unclear whether microsporidia evolved from a specific fungal lineage, or whether microsporidia are a sister group to all fungi. Here, we present evidence addressing this controversial question that is independent of sequence-based phylogenetic reconstruction, but rather based on genome structure. In the zygomycete basal fungal lineage, the sex locus is a syntenic gene cluster governing sexual reproduction in which a high mobility group (HMG) transcription-factor gene is flanked by triose-phosphate transporter (TPT) and RNA helicase genes [[9]]. Strikingly, microsporidian genomes harbor a sex-related locus with the same genes in the same order. Genome-wide synteny analysis reveals multiple other loci conserved between microsporidia and zygomycetes to the exclusion of all other fungal lineages with sequenced genomes. These findings support the hypothesis that microsporidia are true fungi that descended from a zygomycete ancestor and suggest microsporidia may have an extant sexual cycle.
