Time series measurements of nifH gene abundances for several cyanobacteria in the subtropical North Pacific Ocean

Time series measurements of nitrogenase (nifH) gene abundances at Station ALOHA in the subtropical North Pacific Ocean. Seawater for subsequent DNA extractions was subsampled from CTD rosette bottles into 4L polycarbonate bottles. At sea, samples were filtered onto 0.2 µm filters and filters were stored frozen until processing. Genomic DNA was extracted using either the Qiagen Plant Kit (2006-2016) or MasterPure Complete DNA and RNA Purification Kit (Lucigen; 2016-2017) and quantitfied with a Qubit v4 flourometer and a High-Sensitivity DNA Kit (ThermoFisher Scientific). Analyses of nifH gene abundances were determined by quantitative PCR using TaqMan probes and primers (as described in Church et al. 2009), relative to standard curves consisting of ten-fold dilutions of plasmids containing the appropriate nifH gene fragment. Abundances converted to concentrations (genes per liter of seawater) based on sample volumes filtered.北太平洋亚热带海域ALOHA站固氮酶nifH基因（nitrogenase）丰度的时间序列测定数据集。后续用于DNA提取的海水样本从温盐深仪（Conductivity-Temperature-Depth, CTD）采水瓶架中抽取至4L聚碳酸酯瓶中分装；采样现场将样本过滤至0.2 µm滤膜，滤膜经冻存保存直至后续处理。基因组DNA提取分别采用Qiagen植物基因组提取试剂盒（2006-2016年）或MasterPure完整DNA与RNA纯化试剂盒（Lucigen公司，2016-2017年）；DNA浓度通过Qubit v4荧光计搭配高灵敏度DNA试剂盒（赛默飞世尔科技，ThermoFisher Scientific）进行定量。nifH基因丰度采用定量PCR（qPCR）分析，使用TaqMan探针与引物（参照Church等人2009年的研究方法），以含有目标nifH基因片段的质粒10倍梯度稀释产物制作标准曲线进行定量；最终根据过滤的样本体积，将基因丰度换算为浓度单位（基因数/升海水）。