PARAGON 2 - KM2209 - Leucine Incorporation Timecourse Incubations

This dataset contains measurements of rates of leucine incorporation as a measure of bacterial production collected during the PARAGON 2 expedition (KM2209) in the North Pacific Subtropical Gyre. Measurements come from time-course incubation experiments initiated with whole seawater collected at 150 m using trace metal clean techniques and modified with various additions of organic carbon, iron, and/or nitrogen. Rates of leucine incorporation were measured at multiple time points for each experimental biological replicate by subsampling 1 mL aliquots from polycarbonate incubation bottles into 2 mL microcentrifuge tubes (Axygen) and spiking with a final concentration of 20 nmol L⁻¹ leucine with a ³H specific activity of 53.3 Ci mmol⁻¹ of leucine (Perkin Elmer). A killed blank measurement was made for each experimental biological replicate by spiking an additional 1 mL aliquot with 100 µL of 100% (w/v) ice-cold trichloroacetic acid (TCA) prior to spiking with ³H-leucine. All aliquots were then incubated in the dark at in situ temperature for 4-6 hours after which live incubations were terminated with the addition of 100 µL of 100% (w/v) ice-cold TCA. Samples were processed at sea using the centrifugation method of Smith and Azam (1992), and radioactivity incorporated into bacterial protein was measured on a TriCarb 4910TR scintillation counter using Ultima Gold LLT scintillation cocktail (Perkin Elmer). Values reported are the blank-corrected averages of technical triplicate measurements from each sample. Timestamp is in UTC.