Transcriptional response of Emiliania huxleyi CCMP2090 exposed to the bacterial signaling molecule 2-heptyl-4-quinolone

In order to determine how the bacterial quorum-sensing precursor molecule 2-heptyl-4-quinolone (HHQ) induces cellular senescence in populations of some eukaryotic marine phytoplankton, we examined the transcriptional response of Emiliania huxleyi CCMP2090 to HHQ exposure. Quadruplicate batch cultures were treated with HHQ at three concentrations (1, 10 and 100 ng/ml) and compared to a vehicle control after 24 and 72 hours of exposure. The majority of gene expression changes occurred after 24 hr of exposure in the 10 and 100 ng/ml treatments and many of these changes persisted for 72 hr in the 100 ng/ml treatment. RNAseq analysis revealed that HHQ exposure impacts many aspects of Emiliania huxleyi metabolism including: chlorophyll biosynthesis and light harvesting, vitamin biosynthesis, vesicle trafficking, and general signals related to energy production. Changes in genes involved in intraphase cell cycle check points implicate DNA damage as the primary driver of HHQ-induced cellular senescence.

为明确细菌群体感应前体分子2-庚基-4-喹诺酮（2-heptyl-4-quinolone, HHQ）如何诱导部分真核海洋浮游植物种群产生细胞衰老，本研究检测了赫氏艾密里藻（Emiliania huxleyi）CCMP2090在HHQ暴露条件下的转录响应。我们设置了1、10、100 ng/ml三个浓度的HHQ处理组，以溶剂对照为参照，对四次重复的分批培养物分别在暴露24小时和72小时后开展取样分析。在10和100 ng/ml处理组中，多数基因表达变化发生于暴露24小时后，且100 ng/ml处理组的多数变化可延续至72小时。RNA测序（RNA-seq）分析显示，HHQ暴露会影响赫氏艾密里藻的诸多代谢过程，包括叶绿素生物合成与光捕获、维生素生物合成、囊泡运输，以及与能量产生相关的通用信号通路。细胞周期内检验点相关基因的表达变化表明，DNA损伤是HHQ诱导细胞衰老的主要驱动因素。