Abstract Many species of microalga Dunaliella exhibit a remarkable tolerance to salinity and are therefore ideal for probing the effects of salinity. In this work, we assessed the effects of NaC1 stress on the growth,...Abstract Many species of microalga Dunaliella exhibit a remarkable tolerance to salinity and are therefore ideal for probing the effects of salinity. In this work, we assessed the effects of NaC1 stress on the growth, activity and mRNA level of carbon and nitrogen metabolism enzymes of D. viridis. The alga could grow over a salinity range of 0.44 mol L-t to 3.00 mol L-1 NaCI, but the most rapid growth was observed at 1.00molL-1NaC1, followed by 2.00 molL-l NaC1. Paralleling these growth patterns, the highest initial and total Rubisco activities were detected in the presence of 1.00molL-t NaC1, decreasing to 37.33% and 26.39% of those values, re- spectively, in the presence of 3.00 mol L-1 NaC1, respectively. However, the highest extracellular carbonic anhydrase （CA） activity was measured in the presence of 2.00molL-1 NaC1, followed by 1.00molL-1NaC1. Different from the two carbon enzymes, nitrate reductase （NR） activity showed a slight change under different NaC1 concentrations. At the transcriptional level, the mRNAs of Rubisco large subunit （rbcL）, and small subunit （rbcS）, attained their highest abundances in the presence of 1.00 and 2.00molL-1 NaC1, respectively. The CA mRNA accumulation was induced from 0.44molL ~ to 3.00molL-1 NaC1, but the NR mRNA showed the decreasing tendency with the increasing salinity. In conclusion, the growth and carbon fixation enzyme of Rubisco displayed similar tendency in response to NaC1 stress, CA was proved be salt-inducible within a certain salinity range and NR showed the least effect by NaC1 in D. viridis.展开更多
Effects of different iron concentrations(final concentrations of iron in Artari’s medium:3.7,37.0,74.0,and 185.0 mmol$L-1)on growth rate and contents of protein,triacylglycerides,andβ-carotene in Dunaliella viridis ...Effects of different iron concentrations(final concentrations of iron in Artari’s medium:3.7,37.0,74.0,and 185.0 mmol$L-1)on growth rate and contents of protein,triacylglycerides,andβ-carotene in Dunaliella viridis cells at cultivation in different months were investigated.It was shown that the dose-dependent effects of iron were notable for season variability.In the 1st experimental series(October,2007),iron at researched concentrations did not affect growth rate of culture and protein,triacylglyceride,andβ-carotene contents in cells.In experimental series conducted respectively in November 2007,December 2007,and February 2008,the dosedependent stimulation of microalgae growth was observed.For each of these experimental series,there were particular dose dependences of protein,triacylglyceride,andβ-carotene contents in microalgae cells at cultivation on media with iron at different concentrations.Meanwhile,for all of the four experimental series conducted in different months,variability of growth rate and analyzed parameters of microalgae Dunaliella viridis as control(cultivation without iron)was shown.It is suggested that these functional differences of control cultures of microalgae in different months caused variability in the dosedependent effects of iron in a Dunaliella viridis culture.The possibility of iron usage for increasing microalgae biomass and for enriching it byβ-carotene in Dunaliella viridis culture with initial low productivity and lowβ-carotene content is considered.展开更多
基金funded by the Project of Science and Technology Innovation Team of Zhejiang Province (2010R50025-25)sponsored by the K. C. Wong Magna Fund
文摘Abstract Many species of microalga Dunaliella exhibit a remarkable tolerance to salinity and are therefore ideal for probing the effects of salinity. In this work, we assessed the effects of NaC1 stress on the growth, activity and mRNA level of carbon and nitrogen metabolism enzymes of D. viridis. The alga could grow over a salinity range of 0.44 mol L-t to 3.00 mol L-1 NaCI, but the most rapid growth was observed at 1.00molL-1NaC1, followed by 2.00 molL-l NaC1. Paralleling these growth patterns, the highest initial and total Rubisco activities were detected in the presence of 1.00molL-t NaC1, decreasing to 37.33% and 26.39% of those values, re- spectively, in the presence of 3.00 mol L-1 NaC1, respectively. However, the highest extracellular carbonic anhydrase （CA） activity was measured in the presence of 2.00molL-1 NaC1, followed by 1.00molL-1NaC1. Different from the two carbon enzymes, nitrate reductase （NR） activity showed a slight change under different NaC1 concentrations. At the transcriptional level, the mRNAs of Rubisco large subunit （rbcL）, and small subunit （rbcS）, attained their highest abundances in the presence of 1.00 and 2.00molL-1 NaC1, respectively. The CA mRNA accumulation was induced from 0.44molL ~ to 3.00molL-1 NaC1, but the NR mRNA showed the decreasing tendency with the increasing salinity. In conclusion, the growth and carbon fixation enzyme of Rubisco displayed similar tendency in response to NaC1 stress, CA was proved be salt-inducible within a certain salinity range and NR showed the least effect by NaC1 in D. viridis.
文摘Effects of different iron concentrations(final concentrations of iron in Artari’s medium:3.7,37.0,74.0,and 185.0 mmol$L-1)on growth rate and contents of protein,triacylglycerides,andβ-carotene in Dunaliella viridis cells at cultivation in different months were investigated.It was shown that the dose-dependent effects of iron were notable for season variability.In the 1st experimental series(October,2007),iron at researched concentrations did not affect growth rate of culture and protein,triacylglyceride,andβ-carotene contents in cells.In experimental series conducted respectively in November 2007,December 2007,and February 2008,the dosedependent stimulation of microalgae growth was observed.For each of these experimental series,there were particular dose dependences of protein,triacylglyceride,andβ-carotene contents in microalgae cells at cultivation on media with iron at different concentrations.Meanwhile,for all of the four experimental series conducted in different months,variability of growth rate and analyzed parameters of microalgae Dunaliella viridis as control(cultivation without iron)was shown.It is suggested that these functional differences of control cultures of microalgae in different months caused variability in the dosedependent effects of iron in a Dunaliella viridis culture.The possibility of iron usage for increasing microalgae biomass and for enriching it byβ-carotene in Dunaliella viridis culture with initial low productivity and lowβ-carotene content is considered.
