Farhat Sarah, Florent Isabelle, Noel Benjamin, Kayal Ehsan, Da Silva Corinne, Bigeard Estelle, Alberti Adriana, Labadie Karine, Corre Erwan, Aury Jean-Marc, Rombauts Stephane, Wincker Patrick, Guillou Laure, Porcel Betina M
Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, Evry, France.
Communication Molecules and Adaptation of Microorganisms, National Museum of Natural History, CNRS, Paris, France.
Front Microbiol. 2018 Oct 2;9:2251. doi: 10.3389/fmicb.2018.02251. eCollection 2018.
Understanding factors that generate, maintain, and constrain host-parasite associations is of major interest to biologists. Although little studied, many extremely virulent micro-eukaryotic parasites infecting microalgae have been reported in the marine plankton. This is the case for , a diverse and highly widespread group of Syndiniales infecting and potentially controlling dinoflagellate populations. Here, we analyzed the time-scale gene expression of a complete infection cycle of two strains infecting the same host (the dinoflagellate ), but diverging by their host range (one infecting a single host, the other infecting more than one species). Over two-thirds of genes showed two-fold differences in expression between at least two sampled stages of the life cycle. Genes related to carbohydrate metabolism as well as signaling pathways involving proteases and transporters were overexpressed during the free-living stage of the parasitoid. Once inside the host, all genes related to transcription and translation pathways were actively expressed, suggesting the rapid and extensive protein translation needed following host-cell invasion. Finally, genes related to cellular division and components of the flagellum organization were overexpressed during the sporont stage. In order to gain a deeper understanding of the biological basis of the host-parasitoid interaction, we screened proteins involved in host-cell recognition, invasion, and protection against host-defense identified in model apicomplexan parasites. Very few of the genes encoding critical components of the parasitic lifestyle of apicomplexans could be unambiguously identified as highly expressed in . Genes related to the oxidative stress response were identified as highly expressed in both parasitoid strains. Among them, the correlated expression of superoxide dismutase/ascorbate peroxidase in the specialist parasite was consistent with previous studies on defense. However, this defense process could not be identified in the generalist strain, suggesting the establishment of different strategies for parasite protection related to host specificity.
了解产生、维持和限制宿主 - 寄生虫关联的因素是生物学家主要感兴趣的内容。尽管研究较少，但在海洋浮游生物中已报道了许多感染微藻的极具毒性的微真核寄生虫。感染并可能控制甲藻种群的多样且广泛分布的合胞体目就是这种情况。在这里，我们分析了两种感染同一宿主（甲藻）但宿主范围不同（一种感染单一宿主，另一种感染多种物种）的菌株完整感染周期的时间尺度基因表达。超过三分之二的基因在该寄生虫生命周期的至少两个采样阶段之间表现出两倍的表达差异。与碳水化合物代谢以及涉及蛋白酶和转运蛋白的信号通路相关的基因在寄生体的自由生活阶段过表达。一旦进入宿主，所有与转录和翻译通路相关的基因都被积极表达，这表明宿主细胞入侵后需要快速而广泛的蛋白质翻译。最后，与细胞分裂和鞭毛组织成分相关的基因在孢子母细胞阶段过表达。为了更深入地了解宿主 - 寄生体相互作用的生物学基础，我们筛选了参与宿主细胞识别、入侵以及针对在模型顶复门寄生虫中鉴定出的宿主防御的保护作用的蛋白质。在该寄生虫中，很少有编码顶复门寄生虫寄生生活方式关键成分的基因能被明确鉴定为高表达。与氧化应激反应相关的基因在两种寄生体菌株中均被鉴定为高表达。其中，在专性寄生虫中超氧化物歧化酶/抗坏血酸过氧化物酶的相关表达与先前关于该寄生虫防御的研究一致。然而，在兼性寄生虫菌株中无法识别这种防御过程，这表明与宿主特异性相关的寄生虫保护策略不同。
