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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/40988

Title: Bacterioplankton growth responses to temperature and chlorophyll variations in estuaries measured by thymidine:leucine incorporation ratio
Authors: Fuh-Kwo Shiah
Hugh W. Ducklow
Contributors: 國立臺灣海洋大學:海洋環境化學與生態研究所
Keywords: Unbalanced growth
Bacterioplankton
Diel and seasonal cycles
Estuary
DNA
Protein
Temperature
Date: 1997
Issue Date: 2017-02-07T08:42:31Z
Publisher: Aquatic Microbial Ecology
Abstract: Abstract: To identify the biochemical response of heterotrophic bacterioplankton to changing environmental conditions, seasonal and diel cycles of bacterial protein and DNA synthesis rates were estimated in temperate estuarine habitats from 3H-leucine (Leu) and 3H-thymidine (TdR) incorporation rates. Several short-term temperature manipulation experiments (5 to 35°C) and 2 mesocosm experiments were performed to examine the effects of temperature and substrate supply on the ratio of Leu:TdR, respectively. The molar ratio of Leu to TdR varied about 5-fold (5.6 to 29.5) in the field and the values of the ratio were lower and more constant during high temperature (>25°C) and high chlorophyll a (>8.0 μg l-1) periods. In the temperature manipulation experiments, the Leu:TdR ratio decreased as temperature increased. In the mesocosm experiments, the Leu:TdR ratio was negatively correlated with chlorophyll a concentrations and bacterial specific growth rates. We propose that changes toward less favorable environmental conditions (e.g. reductions in temperature or substrate supply in temperate estuaries) might reduce bacterial protein and DNA synthesis rates simultaneously. However, the former process may be favored to maximize survival and this might lead to a higher Leu:TdR ratio. Conversely, when environmental conditions turn favorable, both processes could be enhanced and bacteria might optimize DNA duplication over protein metabolism to maximize reproduction, resulting in lower Leu:TdR ratios. Our results further indicate the complementariness of 3H-thymidine and 3H-leucine incorporation measurements for understanding processes controlling bacterial production since the ratio of these 2 tracer methods varied independently with temperature and substrate supply.
Relation: 13
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/40988
Appears in Collections:[海洋環境與生態研究所] 期刊論文

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