A method for characterizing dissolved <scp>DNA</scp> and its application to the North Pacific Subtropical Gyre

Dissolved DNA (D-DNA) is a ubiquitous component of dissolved organic matter in aquatic systems. It operationally defined as the that passes membrane filter and thus includes pools truly “free” (F-DNA), virion encapsidated DNA, within vesicles, possibly other bound forms, each with different sources lability. We investigated whether filtration (< 0.1 μm), concentration by tangential flow ultrafiltration (> 30 kDa), fractionation an equilibrium buoyant density gradient could be used to discriminate mass contributions filterable seawater. Spike-in experiments known range standards (75–20,000 bp) indicated this method results high recoveries F-DNA (68–86%) minimal degradation. Application seawater samples collected from oligotrophic North Pacific Ocean followed analysis fractions (epifluorescence electron microscopy, DNase digestion) suggested low-density (1.30–1.35 g mL−1) were dominated vesicle-like particles, mid-density (1.45–1.55 virus-like high-density (1.60–1.70 F-DNA. The estimated either F-DNA, viruses, or vesicles was 0.13, 0.14, 0.08 μg L−1, respectively euphotic zone 0.09, 0.04, 0.03 mesopelagic zone. approach described should useful for more detailed investigations abundance, dynamics, distinct comprise environments.