Internal Nitrogen Pools Shape the Infection of Aureococcus anophagefferens CCMP 1984 by a Giant Virus
Internal Nitrogen Pools Shape the Infection of Aureococcus anophagefferens CCMP 1984 by a Giant Virus
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DOI：
10.3389/fmicb.2020.00492
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发表时间：
2020-03
影响因子：
5.2
通讯作者：
Eric R. Gann;B. Hughes;Todd B. Reynolds;S. Wilhelm
中科院分区：
文献类型：
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作者：
Eric R. Gann;B. Hughes;Todd B. Reynolds;S. Wilhelm
浮游植物Aureococcus anophagefferens每年在世界各地的浅海湾中开花，在那里它被假设为部分通过使用替代氮源来竞争其他浮游植物。在水华后期感染的自然种群比例很高，这表明病毒导致了水华的崩溃。我们假设，Areococcus anophagefferens病毒（AaV）的感染周期将受到负面影响的文化适应减少外部氮的条件下，但实时外部氮浓度不会影响感染周期。在NO3浓度（0.0147 mM; N：P = 0.1225）中驯化的培养物显示出降低的终点细胞丰度、前向散射（代表大小）和红色荧光（代表叶绿素a），也以较慢的速率产生较少的病毒/细胞。感染后降低外部氮浓度并不改变破裂大小或溶解时间。这些数据表明，用于新病毒后代的氮在感染时存在于宿主细胞内。感染周期的流式细胞术数据显示感染后约12小时红色荧光减少，与感染周期期间富氮叶绿体的降解一致。使用细胞和病毒配额估计，我们确定A。对于所测定的爆发大小的较低范围，按蚊细胞具有足够的氮和碳，但不含足够的磷。与这一观察结果一致，硝酸盐和糖转运蛋白的表达在感染周期的公开可用的转录组数据中没有增加，而几种磷转运蛋白则增加。我们的数据表明，动态的病毒感染金球菌的过程中的水华是由宿主细胞状态感染后，这是先验的外部营养供应。
The pelagophyte Aureococcus anophagefferens blooms annually in shallow bays around the world, where it is hypothesized to outcompete other phytoplankton in part by using alternative nitrogen sources. The high proportion of natural populations that are infected during the late stages of the bloom suggest viruses cause bloom collapse. We hypothesized that the Aureococcus anophagefferens Virus (AaV) infection cycle would be negatively influenced in cultures acclimated to decreasing external nitrogen conditions, but that the real-time external nitrogen concentration would not influence the infection cycle. Cultures acclimated in NO3- concentrations (0.0147 mM; N:P = 0.1225) that showed reduced end point cell abundances, forward scatter (a proxy for size) and red fluorescence (a proxy for chlorophyll a), also produced fewer viruses per cell at a slower rate. Decreasing the external concentration of nitrogen post infection did not alter burst size or time to lysis. These data suggest that the nitrogen used for new viral progeny is present within host cells at the time of infection. Flow cytometric data of an infection cycle showed a reduction in red fluorescence around twelve hours post infection, consistent with degradation of nitrogen-rich chloroplasts during the infection cycle. Using cell and virus quota estimates, we determined that A. anophagefferens cells had sufficient nitrogen and carbon for the lower ranges of burst sizes determined but did not contain enough phosphorous. Consistent with this observation, expression of nitrate and sugar transporters did not increase in the publicly available transcriptome data of the infection cycle, while several phosphorus transporters were. Our data demonstrate that dynamics of viruses infecting Aureococcus over the course of a bloom is dictated by the host cell state upon infection, which is set a priori by external nutrient supplies.