Pollitt Laura C, Colegrave Nick, Khan Shahid M, Sajid Mohammed, Reece Sarah E
Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, School of Biological Sciences, Edinburgh, EH9 3JT, UK.
Parasit Vectors. 2010 Nov 16;3:105. doi: 10.1186/1756-3305-3-105.
Apoptosis is a precisely regulated process of cell death which occurs widely in multicellular organisms and is essential for normal development and immune defences. In recent years, interest has grown in the occurrence of apoptosis in unicellular organisms. In particular, as apoptosis has been reported in a wide range of species, including protozoan malaria parasites and trypanosomes, it may provide a novel target for intervention. However, it is important to understand when and why parasites employ an apoptosis strategy before the likely long- and short-term success of such an intervention can be evaluated. The occurrence of apoptosis in unicellular parasites provides a challenge for evolutionary theory to explain as organisms are expected to have evolved to maximise their own proliferation, not death. One possible explanation is that protozoan parasites undergo apoptosis in order to gain a group benefit from controlling their density as this prevents premature vector mortality. However, experimental manipulations to examine the ultimate causes behind apoptosis in parasites are lacking. In this review, we focus on malaria parasites to outline how an evolutionary framework can help make predictions about the ecological circumstances under which apoptosis could evolve. We then highlight the ecological considerations that should be taken into account when designing evolutionary experiments involving markers of cell death, and we call for collaboration between researchers in different fields to identify and develop appropriate markers in reference to parasite ecology and to resolve debates on terminology.
细胞凋亡是一种精确调控的细胞死亡过程，广泛存在于多细胞生物中，对正常发育和免疫防御至关重要。近年来，单细胞生物中细胞凋亡的发生受到越来越多的关注。特别是，由于在包括原生动物疟原虫和锥虫在内的广泛物种中都报道了细胞凋亡，它可能提供一个新的干预靶点。然而，在评估这种干预可能的长期和短期成功之前，了解寄生虫何时以及为何采用细胞凋亡策略很重要。单细胞寄生虫中细胞凋亡的发生给进化理论带来了挑战，因为生物体预计会进化以最大化自身增殖，而非死亡。一种可能的解释是，原生动物寄生虫经历细胞凋亡是为了通过控制自身密度获得群体利益，因为这可以防止媒介过早死亡。然而，缺乏检验寄生虫细胞凋亡背后最终原因的实验操作。在本综述中，我们聚焦疟原虫，概述进化框架如何有助于预测细胞凋亡可能进化的生态环境。然后，我们强调在设计涉及细胞死亡标记物的进化实验时应考虑的生态因素，并呼吁不同领域的研究人员合作，参照寄生虫生态学确定和开发合适的标记物，并解决术语争议。
