Degradation of [14C]GlcDGD in the marine sediment by monitoring radioactivity in the aqueous and gas phase using liquid scintillation counting (LSC) techniques

An experiment was conceived in which we monitored degradation of GlcDGD. Independent of the fate of the [14C]glucosyl headgroup after hydrolysis from the glycerol backbone, the 14C enters the aqueous or gas phase whereas the intact lipid is insoluble and remains in the sediment phase. Total degradation of GlcDGD then is obtained by combining the increase of radioactivity in the aqueous and gaseous phases. We chose two different sediment to perform this experiment. One is from microbially actie surface sediment sampled in February 2010 from the upper tidal flat of the German Wadden Sea near Wremen (53° 38' 0N, 8° 29' 30E). The other one is deep subsurface sediments recovered from northern Cascadia Margin during Integrated Ocean Drilling Program Expedition 311 [site U1326, 138.2 meters below seafloor (mbsf), in situ temperature 20 °C, water depth 1,828 m. We performed both alive and killed control experiments for comparison. Surface and subsurface sediment slurry were incubated in the dark at in situ temperature, 4 °C and 20 °C for 300 d, respectively. The sterilized slurry was stored at 20 °C. All incubations were carried out under N2 headspace to ensure anaerobic conditions. The sampling frequency was high during the first half-month, i.e., after 1, 2, 7, and 14 d; thereafter, the sediment slurry was sampled every 2 months. At each time point, samples were taken in triplicate for radioactivity measurements. After 300 d of incubation, no significant changes of radioactivity in the aqueous phase were detected. This may be the result of either the rapid turnover of released [14C] glucose or the relatively high limit of detection caused by the slight solubility (equivalent to 2% of initial radioactivity) of GlcDGD in water. Therefore, total degradation of GlcDGD in the dataset was calculated by combining radioactivity of DIC, CH4, and CO2, leading to a minimum estimate.

Guide to urban traffic volume counting. Final report.

Federal Highway Administration, Urban Planning Division, Washington, D.C.

1980 census, counting illegal aliens : hearing before the Subcommittee on Energy, Nuclear Proliferation, and Federal Services of the Committee on Governmental Affairs, United States Senate, Ninety-sixth Congress, second session, on S. 2366 ... March 26, 1980.

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Speed independent counting circuits /

"July 1, 1956"

Geiger counting of tritium as water vapor /

"July 1, 1961."

The application of photosensitive gas counters to scintillation counting /

"Contract No. AT-(40-1)-2513."

Serial reports on start-up experiments : no. 5. counting losses in BF₃ proportional counter systems.

"Work performed under Contract No. AT-30-2-Gen-16."

Determination of uranium in air dust samples by alpha counting methods / by John H. Harley, Evelyn Jetter.

"3-16-50--575-A18845."

Preparation of water samples for asbestos fiber counting by electron microscopy /

Prepared by Ontario Research Foundation, under contract no. 68-03-2389.

Improved method of detecting and counting bacteria. /

Address inquiries and all applications for license for this invention to NASA Patent Counsel, Goddard Space Flight Center, Mail Code 204, Greenbelt, Maryland, 20771.

Counting the labor force /

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