病原体酵母“白念珠菌”过去曾被认为是严格无性生殖的，但现在人们知道，这种生物有一个秘密交配循环。交配通常涉及a-细胞类型和alpha-细胞类型的融合，与相关酵母“酿酒酵母”中所见的类似。
现在，另外一种新颖的有性生殖模式已在“白念珠菌”中被发现：在特定情况下，即在没有为一种分泌出的蛋白酶编码的BAR1基因存在的情况下，高效同性交配可在a-型细胞之间进行。“白念珠菌”的同性交配与相关真菌病原体“新型隐球菌”的同性交配之间的相似性提出一个可能性：这种类型的“同宗配合”也许可帮助这些物种在哺乳动物宿主体内更加具有适应性。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 460, 890-893 (13 August 2009) | doi:10.1038/nature08252
Homothallic and heterothallic mating in the opportunistic pathogen Candida albicans
Kevin Alby1, Dana Schaefer1 & Richard J. Bennett1
1 Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island 02912, USA
Candida albicans is the most common fungal pathogen in humans, causing both debilitating mucosal infections and potentially life-threatening systemic infections1, 2. Until recently, C. albicans was thought to be strictly asexual, existing only as an obligate diploid. A cryptic mating cycle has since been uncovered in which diploid a and cells undergo efficient cell and nuclear fusion, resulting in tetraploid a/ mating products3, 4, 5, 6. Whereas mating between a and cells has been established (heterothallism), we report here two pathways for same-sex mating (homothallism) in C. albicans. First, unisexual populations of a cells were found to undergo autocrine pheromone signalling and same-sex mating in the absence of the Bar1 protease. In both C. albicans and Saccharomyces cerevisiae, Bar1 is produced by a cells and inactivates mating pheromone , typically secreted by cells7, 8, 9, 10. C. albicans bar1 a cells were shown to secrete both a and mating pheromones; -pheromone activated self-mating in these cells in a process dependent on Ste2, the receptor for -pheromone. In addition, pheromone production by cells was found to promote same-sex mating between wild-type a cells. These results establish that homothallic mating can occur in C. albicans, revealing the potential for genetic exchange even within unisexual populations of the organism. Furthermore, Bar1 protease has an unexpected but pivotal role in determining whether sexual reproduction can potentially be homothallic or is exclusively heterothallic. These findings also have implications for the mode of sexual reproduction in related species that propagate unisexually, and indicate a role for specialized sexual cycles in the survival and adaptation of pathogenic fungi.
