SRA

Two diatoms (Cylindrotheca closterium) and two coccolithophores (Gephyrocapsa oceanica and Gephyrocapsa huxleyi, formerly Emiliania huxleyi) were isolated from inner and out shelf waters of the South Atlantic Bight (SAB), respectively. Isolates were grown in triplicate* under steady-state high and low iron conditions, with an additional iron amendment treatment to investigate iron-related metabolic strategies of isolates from an iron gradient. Isolates were harvested at early exponential growth; at which point half of the low iron treatment volume was used for an additional 24 hour iron amendment experiment. Physiological parameters measured were growth rate, Chl a concentration, cell size, cell counts, and photophysiology parameters such as Fv/Fm and NPQ. RNA was extracted using a Qiagen RNeasy Plant Mini Kit and sent to the Georgia Genomics and Bioinformatics Core (GGBC) in Athens, Georgia for sequencing. Illumina NGS was performed on all samples with a NextSeq 2000 platform, 300 cycles, and 150 paired end reads, and PacBio IsoSeq was performed on one iron amendment sample for each isolate. Both sequencing methods used poly-A selected reads to select for mRNA. The iron driven physiology and gene expression were compared between lineages and within isolates from different shelf zones. Lineage specific differences were observed with the diatoms employing strategies that may enable success across shelf zones, and species-specific differences within the coccolithophores demonstrated metabolic strategies reflecting conditions of the shelf region each originated.*only two replicates of the iron amendment treatment were performed for the diatoms.