title: Incorporation of 3H-thymidine by different prokaryotic groups in relation to temperature and nutrients in a lacustrine ecosystem.
abstract: The incorporation of [3H-methyl] thymidine (3H-TdR) by Eubacteria, bacterial groups (alpha- and beta-Proteobacteria, Cytophaga-Flavobacter), and Archaea was measured according to temperature (7 and 17 degrees C) and nutrient levels (nitrogen, phosphorus, and carbon) in a lacustrine system (Sep, France). Short-term incubation was performed using a combination of microautoradiography and fluorescent in situ hybridization. Irrespective of the temperatures and nutrients studied, all the major phylogenetic bacterial groups assimilated 3H-TdR, and in most of the treatments studied, the proportion of beta-Proteobacteria taking up 3H-TdR was higher than those in the other bacterial groups. The proportion of Bacteria and different bacterial groups studied incorporating 3H-TdR were significantly increased, approximately 1.5-fold, by temperature except for alpha-Proteobacteria (7.6-fold). The nutrient effect was not the same for the different bacterial groups according to the temperatures studied. The proportions of alpha-Proteobacteria (at both temperatures) and Cytophaga-Flavobacter (at 7 degrees C) taking up 3H-TdR were significantly decreased and increased by adding N and P, respectively. Also, adding N, P, and C increased and decreased the percentage of beta-Proteobacteria incorporating 3H-TdR at 7 and 17 degrees C, respectively. The archaeal community showed a similar proportion of active cells (i.e., 3H-TdR) to the bacterial community, and uptake of 3H-TdR by Archaea was significantly increased (P < 0.05) by both temperature and nutrients. Thus, the assimilation of 3H-TdR by bacterial groups and Archaea in lacustrine system is significantly controlled by both temperature and nutrients.
authors.affiliation: Laboratoire de Biologie des Protistes UMR CNRS 6023, Université Blaise Pascal, 63177, Aubière, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Boucher
authors.forename: Mathilde
authors.initials: M
authors.lastname: Richardot
authors.forename: Aurélie
authors.initials: A
authors.lastname: Thénot
authors.forename: Didier
authors.initials: D
authors.lastname: Debroas
mesh_terms: D000222:Adaptation, Physiological; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism*; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D003589:Cytophaga / Q000254:growth & development / Q000378:metabolism; D017753:Ecosystem; D017404:In Situ Hybridization, Fluorescence; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D020560:Proteobacteria / Q000254:growth & development / Q000378:metabolism; D012988:Soil Microbiology; D013696:Temperature; D013936:Thymidine / Q000378:metabolism*; D014316:Tritium
chemical_list: D014316:Tritium; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen; D013936:Thymidine