Mortality in cultures of the dinoflagellate Amphidinium carterae during culture senescence and darkness
Mortality in cultures of the dinoflagellate Amphidinium carterae during culture senescence and darkness
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DOI：
10.1098/rspb.2004.2810
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发表时间：
2004-10-22
影响因子：
4.7
通讯作者：
Berges, JA
中科院分区：
文献类型：
--
作者：
Franklin, DJ;Berges, JA
对高等动植物细胞死亡的研究表明，在大多数类型的细胞中都存在一个活跃的(‘程序性’)过程，而植物、动物、酵母和细菌之间的细胞死亡的相似性表明，程序性细胞死亡(PCD)起源于进化。尽管它们在初级生产中具有全球重要性，但有关藻细胞死亡的信息有限。藻类细胞死亡可能与后生动物细胞死亡有相似之处。光胁迫可以诱导单细胞绿藻杜氏藻PCD的一种形态，即细胞凋亡。其他藻类的情况就不那么清楚了。我们使用一个甲藻模型(Amphiddium Carterae)来测试黑暗和培养衰老过程中的死亡率是否表现出细胞凋亡的特征。利用透射电子显微镜、荧光生物标记物、叶绿素荧光和颗粒碳分析等手段对细胞死亡过程进行了分析，发现光剥夺导致了大量死亡。相反，在晚期培养中发现较少的死亡细胞(占种群的5%-20%)，同时观察到类似的退化细胞形态(缩小、褪绿)。在形态上，我们的观察表明，在圆环毛藻中描述的凋亡性细胞死亡并不发生在圆环毛藻中。发现与最近提出的PCD的另一种形态类型--Paraptosis有更大的相似性。不确定的DNA片段化结果支持一个类似的结论。我们强调在系统发育不同的细胞类型之间传递基本范式时必须谨慎，我们主张在赋予细胞死亡过程因果关系所需的证据责任上有更大的一致性。
The study of cell death in higher plants and animals has revealed the existence of an active ('programmed') process in most types of cell, and similarities in cell death between plants, animals, yeast and bacteria suggest an evolutionarily ancient origin of programmed cell death (PCD). Despite their global importance in primary production, information on algal cell death is limited. Algal cell death could have similarities with metazoan cell death. One morphotype of metazoan PCD, apoptosis, can be induced by light deprivation in the unicellular chlorophyte Dunaliella tertiolecta. The situation in other algal taxa is less clear. We used a model dinoflagellate (Amphidinium carterae) to test whether mortality during darkness and culture senescence showed apoptotic characteristics. Using transmission electron microscopy, fluorescent biomarkers, chlorophyll fluorescence and particulate carbon analysis we analysed the process of cell mortality and found that light deprivation caused mass mortality. By contrast, fewer dead cells (5-20% of the population) were found in late-phase cultures, while a similar degenerate cell morphology (shrunken, chlorotic) was observed. On morphological grounds, our observations suggest that the apoptotic cell death described in D. tertiolecta does not occur in A. carterae. Greater similarity was found with paraptosis, a recently proposed alternative morphotype of PCD. A paraptotic conclusion is supported by inconclusive DNA fragmentation results. We emphasize the care that must be taken in transferring fundamental paradigms between phylogenetically diverse cell types and we argue for a greater consistency in the burden of proof needed to assign causality to cell death processes.