最近,，科學(xué)家發(fā)現(xiàn)，導(dǎo)致艾滋病人等罹患慢性腹瀉的名為微孢子蟲的真菌，在感染人和其它宿主動(dòng)物時(shí),，能夠進(jìn)行有性繁殖，該發(fā)現(xiàn)有望幫助研究人員理解其“工作原理”并找到方法治療上述疾病,。相關(guān)研究結(jié)果刊登在近期出版的《當(dāng)代生物學(xué)》（Current Biology）雜志上,。
該論文的主要作者、杜克大學(xué)分子遺傳學(xué)和微生物學(xué)博士后李頌昌（音譯）說：“微孢子蟲感染很難治療,，因?yàn)槲覀儗ζ渲跎伲?0%%的艾滋病患者遭遇微孢子真菌感染,，引發(fā)慢性腹瀉。這些感染也在旅行性腹瀉病人,、器官移植接受者和老人身上發(fā)現(xiàn),。”
微孢子蟲病是一種人獸共患病，各年齡組均可受染,，人類為孢子蟲感染與宿主的免疫功能嚴(yán)重地受到抑制有密切關(guān)系,，以前人們認(rèn)為微孢子蟲無有性生殖期。
杜克大學(xué)的研究人員使用兩個(gè)基因研究證明,，微孢子蟲明顯地從有性的真菌中進(jìn)化,，并且尤其同接合菌密切相關(guān)，他們發(fā)現(xiàn),，微孢子蟲的2000多個(gè)基因中,，有33個(gè)基因同接合菌一樣，這些染色體標(biāo)記顯示,，微孢子蟲同接合菌很可能擁有共同的祖先,，并且，它同其他已知的真菌聯(lián)系更為疏遠(yuǎn),。另外,，有性繁殖所包含的其他基因也在這兩類真菌中出現(xiàn)，這表明,，微孢子蟲可能有一個(gè)遺傳控制生殖周期,，并且可能在感染宿主時(shí)開始進(jìn)行有性繁殖。
研究人員接下來打算探究這些物種的有性繁殖,，有性繁殖會導(dǎo)致更嚴(yán)重的感染,，因?yàn)椴≡w使用宿主的細(xì)胞環(huán)境和體系，將其作為繁殖的安全港。該研究團(tuán)隊(duì)將會在培植細(xì)胞和線蟲上進(jìn)行試驗(yàn),，他們發(fā)現(xiàn),，線蟲是微孢子蟲的天然宿主。該研究由美國國家衛(wèi)生研究院和加拿大衛(wèi)生研究院資助,。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
