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Overexpressing Ferredoxins in Chlamydomonas reinhardtii Increase Starch and Oil Yields and Enhance Electric Power Production in a Photo Microbial Fuel Cell.

Huang LF, Lin JY, Pan KY, Huang CK, Chu YK - Int J Mol Sci (2015)

Bottom Line: The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion.Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion.Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan 320, Taiwan. hlf326@saturn.yzu.edu.tw.

ABSTRACT
Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC.

No MeSH data available.


Related in: MedlinePlus

Comparison of ROS accumulation pattern and H2O2 content in wild-type and transgenic cell lines overexpressing ferredoxins under normal and high temperature growth conditions. Wild-type (WT), PETF transgenic line (P51), and FDX5 transgenic line (F5-302) were incubated at 25 or 42 °C for 40 min and stained with H2DCFDA to monitor the accumulation of cellular ROS (A); The green color indicates the presence of ROS. The red color indicates autofluorescence of chlorophyll. Bars indicate 10 μm. The H2O2 content in cells was also measured (B). Error bars indicate SD of the mean for five replicate cell suspensions. Asterisks on the columns indicate significant differences from the WT based on Student’s t-test (p < 0.05).
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ijms-16-19308-f002: Comparison of ROS accumulation pattern and H2O2 content in wild-type and transgenic cell lines overexpressing ferredoxins under normal and high temperature growth conditions. Wild-type (WT), PETF transgenic line (P51), and FDX5 transgenic line (F5-302) were incubated at 25 or 42 °C for 40 min and stained with H2DCFDA to monitor the accumulation of cellular ROS (A); The green color indicates the presence of ROS. The red color indicates autofluorescence of chlorophyll. Bars indicate 10 μm. The H2O2 content in cells was also measured (B). Error bars indicate SD of the mean for five replicate cell suspensions. Asterisks on the columns indicate significant differences from the WT based on Student’s t-test (p < 0.05).

Mentions: In our previous study it was shown that overexpression of PETF in transgenic Chlamydomonas lines led to greater heat tolerance than in the wild type. ROS levels in these transgenic PETF lines also decreased in both normal and heat-stressed growth conditions [24]. To address whether overexpression of FDX5 also lowered the ROS level in Chlamydomonas, the levels of H2O2, which is the major ROS, were compared in the wild-type and transgenic lines. The accumulation of H2O2 was lowered by ectopic expression of PETF in both normal and heat-stress conditions (Figure 2), consistent with our previous results [24]. The H2O2 levels in the FDX5 transgenic line were lower than those in the wild-type cells in normal and heat-stressed conditions (Figure 2). A dye to label cellular ROS, H2DCFDA, was applied to observe Chlamydomonas cells under a confocal microscope. A ROS green signal was not observed under normal growth conditions for either the wild-type or transgenic lines. After heat treatment, strong ROS fluorescent signals were detected in the chloroplast of wild-type cells, whereas slight ROS signals were observed in both the PETF and FDX5 overexpression lines (Figure 2). These results indicate that ectopic expression of FDX5 cDNA decreased the ROS level in cells, similar to previous observations for ectopic expression of PETF.


Overexpressing Ferredoxins in Chlamydomonas reinhardtii Increase Starch and Oil Yields and Enhance Electric Power Production in a Photo Microbial Fuel Cell.

Huang LF, Lin JY, Pan KY, Huang CK, Chu YK - Int J Mol Sci (2015)

Comparison of ROS accumulation pattern and H2O2 content in wild-type and transgenic cell lines overexpressing ferredoxins under normal and high temperature growth conditions. Wild-type (WT), PETF transgenic line (P51), and FDX5 transgenic line (F5-302) were incubated at 25 or 42 °C for 40 min and stained with H2DCFDA to monitor the accumulation of cellular ROS (A); The green color indicates the presence of ROS. The red color indicates autofluorescence of chlorophyll. Bars indicate 10 μm. The H2O2 content in cells was also measured (B). Error bars indicate SD of the mean for five replicate cell suspensions. Asterisks on the columns indicate significant differences from the WT based on Student’s t-test (p < 0.05).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4581298&req=5

ijms-16-19308-f002: Comparison of ROS accumulation pattern and H2O2 content in wild-type and transgenic cell lines overexpressing ferredoxins under normal and high temperature growth conditions. Wild-type (WT), PETF transgenic line (P51), and FDX5 transgenic line (F5-302) were incubated at 25 or 42 °C for 40 min and stained with H2DCFDA to monitor the accumulation of cellular ROS (A); The green color indicates the presence of ROS. The red color indicates autofluorescence of chlorophyll. Bars indicate 10 μm. The H2O2 content in cells was also measured (B). Error bars indicate SD of the mean for five replicate cell suspensions. Asterisks on the columns indicate significant differences from the WT based on Student’s t-test (p < 0.05).
Mentions: In our previous study it was shown that overexpression of PETF in transgenic Chlamydomonas lines led to greater heat tolerance than in the wild type. ROS levels in these transgenic PETF lines also decreased in both normal and heat-stressed growth conditions [24]. To address whether overexpression of FDX5 also lowered the ROS level in Chlamydomonas, the levels of H2O2, which is the major ROS, were compared in the wild-type and transgenic lines. The accumulation of H2O2 was lowered by ectopic expression of PETF in both normal and heat-stress conditions (Figure 2), consistent with our previous results [24]. The H2O2 levels in the FDX5 transgenic line were lower than those in the wild-type cells in normal and heat-stressed conditions (Figure 2). A dye to label cellular ROS, H2DCFDA, was applied to observe Chlamydomonas cells under a confocal microscope. A ROS green signal was not observed under normal growth conditions for either the wild-type or transgenic lines. After heat treatment, strong ROS fluorescent signals were detected in the chloroplast of wild-type cells, whereas slight ROS signals were observed in both the PETF and FDX5 overexpression lines (Figure 2). These results indicate that ectopic expression of FDX5 cDNA decreased the ROS level in cells, similar to previous observations for ectopic expression of PETF.

Bottom Line: The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion.Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion.Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan 320, Taiwan. hlf326@saturn.yzu.edu.tw.

ABSTRACT
Ferredoxins (FDX) are final electron carrier proteins in the plant photosynthetic pathway, and function as major electron donors in diverse redox-driven metabolic pathways. We previously showed that overexpression of a major constitutively expressed ferredoxin gene PETF in Chlamydomonas decreased the reactive oxygen species (ROS) level and enhanced tolerance to heat stress. In addition to PETF, an endogenous anaerobic induced FDX5 was overexpressed in transgenic Chlamydomonas lines here to address the possible functions of FDX5. All the independent FDX transgenic lines showed decreased cellular ROS levels and enhanced tolerance to heat and salt stresses. The transgenic Chlamydomonas lines accumulated more starch than the wild-type line and this effect increased almost three-fold in conditions of nitrogen depletion. Furthermore, the lipid content was higher in the transgenic lines than in the wild-type line, both with and without nitrogen depletion. Two FDX-overexpressing Chlamydomonas lines were assessed in a photo microbial fuel cell (PMFC); power density production by the transgenic lines was higher than that of the wild-type cells. These findings suggest that overexpression of either PETF or FDX5 can confer tolerance against heat and salt stresses, increase starch and oil production, and raise electric power density in a PMFC.

No MeSH data available.


Related in: MedlinePlus