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Consequences of thymidine catabolism for estimates of bacterial production: An example from a coastal marine sediment
Author(s) -
Carman Kevin R.,
Dobbs Fred C.,
Guckert James B.
Publication year - 1988
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1988.33.6part2.1595
Subject(s) - catabolism , sediment , thymidine , anabolism , dna , dna synthesis , fraction (chemistry) , chemistry , environmental chemistry , desoxyribonucleic acid , metabolism , biology , biochemistry , chromatography , paleontology
Radioactively labeled thymidine (TdR) has been used extensively to measure bacterial production in aquatic environments, but critical assumptions of the TdR technique often have gone untested. In this study of a coastal marine sediment, the metabolic fate of methyl [ 3 H]TdR and methyl [ 14 C]TdR was at variance with the assumptions necessary for determining bacterial production. Only 2% of incorporated radioactivity was recovered in the DNA fraction of TCA‐insoluble material following time‐course incubations of 1–300 min. At least the methyl group of TdR was extensively catabolized, as shown by copious production of 14 CO 2 . The temporal patterns of 3 H: 14 C ratios in macromolecular fractions indicated that products of catabolism were recycled into the DNA fraction. The accuracy of the TdR technique depends in large part on the degree to which such catabolism occurs.