Department of Ecology and Evolutionary Biology, Biological Sciences West, University of Arizona, Tucson, AZ 85721, USA.
Trends Parasitol. 2010 Feb;26(2):70-4. doi: 10.1016/j.pt.2009.11.007. Epub 2009 Dec 18.
Although Giardia is of practical importance as a pathogen and has theoretical importance in evolutionary biology, it is not known whether it ever reproduces sexually. Several recent papers have shed light on this problem, without completely solving it. One paper shows that nuclei in the encysted organism can temporarily fuse and exchange genes; this may explain the genetic similarity of the two nuclei in a cell. Another paper demonstrates that Giardia does undergo sexual reproduction with outcrossing. However, we still do not know whether this involves a meiotic or a parasexual cycle, when it occurs, or how common it is.
尽管贾第虫在病原体方面具有实际意义，在进化生物学方面具有理论意义，但它是否曾经有性繁殖尚不清楚。最近的几篇论文揭示了这个问题，但并没有完全解决它。一篇论文表明，囊包生物体中的细胞核可以暂时融合并交换基因；这可能解释了细胞中两个细胞核的遗传相似性。另一篇论文证明，贾第虫确实通过异交进行有性生殖。然而，我们仍然不知道这涉及减数分裂还是准性循环，它发生的时间，以及它有多常见。
