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Growth phenotype of 5A7 . ( A ) This figure shows the phenotypic difference of 5A7 compared to the parental strain, 4A+ on heterotrophic/mixotrophic agar media (TAP) plates under five different light conditions: dark + paromomycin (P), dark, very dim light (VDL, 2–4 μmol photons m -2 s -1 ), dim light A (DLA, 10–15 μmol photons m -2 s -1 ) and dim light B (DLB, 20–25 μmol photons m -2 s -1 ). ( B ) This figure shows the growth phenotype of 5A7 in liquid photo-autotrophic media (HS) under dim light (DL = 10–15 μmol photons m -2 s -1 ).
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The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms and are synthesized via a common branched tetrapyrrole biosynthetic pathway. One of the enzymes i...
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... have changed the name of our chli1 mutant to chli1-1 and have changed the word "complements" to "rescued transformants". We have corrected the figure numbers for Figure 2 and Figure 6 in the manuscript text. We have also changed our discussion section with respect to the tetrapyrrole mediated nuclear gene expression changes in Chlamydomonas, according to Dr. Masuda's suggestion. ...
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... and identification of the mutant 5A7 Mutant 5A7 was generated by random insertional mutagenesis of the Chlamydomonas reinhardtii wild type strain 4A+ (137c genetic background). 5A7 lacks detectable chlorophyll, appears yellowish- brown in color and grows only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media ( Figure 2). It is incapable of photosynthesis and is sensitive to light intensities higher than 20 µmol photons m -2 s -1 ( Figure 2A). ...
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... lacks detectable chlorophyll, appears yellowish- brown in color and grows only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media ( Figure 2). It is incapable of photosynthesis and is sensitive to light intensities higher than 20 µmol photons m -2 s -1 ( Figure 2A). ...
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... the first chli1-1 mutant to be identified in C. reinhardtii and in green algae. CHLI1 deletion has affected Chl biosynthesis and photosynthetic growth in the chli1-1 mutant (Figure 2). Over- accumulation of photo-excitable PPIX leads to photo-oxidative damage to the cells in presence of light and oxygen 4-6 . ...
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... page 6, sentence 2 " lacks detectable chlorophyll, appears yellowish-brown in color and grows 5A7 only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media (Figure 1)." * Figure 1 should be Figure 2. On page 6, sentence 3 "It is incapable of photosynthesis and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly referred to as Figure 2A instead of Figure 2 only. ...
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... page 6, sentence 2 " lacks detectable chlorophyll, appears yellowish-brown in color and grows 5A7 only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media (Figure 1)." * Figure 1 should be Figure 2. On page 6, sentence 3 "It is incapable of photosynthesis and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly referred to as Figure 2A instead of Figure 2 only. On page 8, Figures 5A, 5B and 5C mentioned in text actually refers to Figures 6A, 6B and 6C. ...
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... page 6, sentence 2 " lacks detectable chlorophyll, appears yellowish-brown in color and grows 5A7 only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media (Figure 1)." * Figure 1 should be Figure 2. On page 6, sentence 3 "It is incapable of photosynthesis and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly referred to as Figure 2A instead of Figure 2 only. On page 8, Figures 5A, 5B and 5C mentioned in text actually refers to Figures 6A, 6B and 6C. ...
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... page 6, sentence 2 " lacks detectable chlorophyll, appears yellowish-brown in color and grows 5A7 only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media (Figure 1)." * Figure 1 should be Figure 2. On page 6, sentence 3 "It is incapable of photosynthesis and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly referred to as Figure 2A instead of Figure 2 only. On page 8, Figures 5A, 5B and 5C mentioned in text actually refers to Figures 6A, 6B and 6C. ...
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... page 6, sentence 2 " lacks detectable chlorophyll, appears yellowish-brown in color and grows 5A7 only under heterotrophic conditions in the dark or in the dim light in the presence of acetate in the growth media (Figure 1)." * Figure 1 should be Figure 2. On page 6, sentence 3 "It is incapable of photosynthesis and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly and is sensitive to light intensities higher than 20 μmol photons m-2s-1 (Figure 2)," ---*can be more clearly referred to as Figure 2A instead of Figure 2 only. On page 8, Figures 5A, 5B and 5C mentioned in text actually refers to Figures 6A, 6B and 6C. ...
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The green micro-alga Chlamydomonas reinhardtii is an elegant model organism to study all aspects of oxygenic photosynthesis. Chlorophyll (Chl) and heme are major tetrapyrroles that play an essential role in energy metabolism in photosynthetic organisms and are synthesized via a common branched tetrapyrrole biosynthetic pathway. One of the enzymes i...
Expressed sequence tag analyses revealed that two marine Chlorophyceae green algae, Chlamydomonas sp. W80 and Chlamydomonas sp. HS5, contain genes coding for chloroplastic class IIA aldolase (fructose-1, 6-bisphosphate aldolase: FBA). These genes show robust monophyly with those of the marine Prasinophyceae algae genera Micromonas, Ostreococcus and...
The maturation of transfer RNA precursors involves the 5' cleavage of leader sequences by essential endonucleases called RNase P. Beyond the ancestral ribonucleoprotein (RNP) RNases P, a second type of RNase P called PRORP, only composed of protein evolved in eukaryotes. The current view on the distribution of RNase P in cells is that multiple RNPs...
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Chlamydomonas reinhardtii is one of the most characterized green algae. The open-pond cultivation can be challenging due to sensitivity of strain to fluctuating environmental conditions and unavailability of low-cost photoautotrophic media. In this study, the photoautotrophic growth of C. reinhardtii was evaluated in 1-m² open ponds placed in green...
Citations
... These include mutants of both the light-and the dark-dependent protochlorophyllide reductases (POR1 and DPOR), of the Mg-protoporphyrin IX methyltransferase (CHLM), and of the three subunits of Mg chelatase (CHLH1, CHLI1/2 and CHLD). These mutants are photosensitive, severely chlorotic and/or yellow in the dark (Li and Timko, 1996;Chekounova et al., 2001;Falciatore et al., 2005;von Gromoff et al., 2008;Meinecke et al., 2010;Grovenstein et al., 2013). It was recently demonstrated that the specific loss of Chl b in Chlamydomonas does not disrupt accumulation of LHCI and LHCII polypeptides as long as Chl a biosynthesis remains intact (Bujaldon et al., 2017). ...
In land plants, linear tetrapyrrole (bilin)-based phytochrome photosensors optimize photosynthetic light capture by mediating massive reprogramming of gene expression. But, surprisingly, many green algal genomes lack phytochrome genes. Studies of the heme oxygenase mutant (hmox1) of the green alga Chlamydomonas reinhardtii suggest that bilin biosynthesis in plastids is essential for proper regulation of a nuclear gene network implicated in oxygen detoxification during dark-to-light transitions. hmox1 cannot grow photoautotrophically and photoacclimates p oorly to increased illumination. We show that these phenotypes are due to reduced accumulation of photosystem I (PSI) reaction centers, the PSI electron acceptors 5'-monohydroxyphylloquinone and phylloquinone, and the loss of PSI and photosystem II (PSII) antennae complexes during photoacclimation. The hmox1 mutant resembles chlorophyll biosynthesis mutants phenotypically, but can be rescued by exogenous biliverdin IXα, the bilin produced by HMOX1. This rescue is independent of photosynthesis and is strongly dependent on blue light. RNA-Seq comparisons of hmox1, genetically complemented hmox1, and chemically rescued hmox1 reveal that tetrapyrrole biosynthesis, known photoreceptor and photosynthesis-related genes are not impacted in the hmox1 mutant at the transcript level. We propose that a bilin-based, blue-light-sensing system within plastids evolved together with a bilin-based retrograde signaling pathway to ensure that a robust photosynthetic apparatus is sustained in light-grown C. reinhardtii.
... As an example of ALCOdb use, consider the functional estimation of causative genes for a certain mutant phenotype. Chlamydomonas mutant strain 5A7, which exhibits a light-sensitive phenotype and reduced chlorophyll content, was isolated by screening photosynthesis-and pigment-deficient mutants (Grovenstein et al. 2013). The authors confirmed that this phenotype is due in part to a defect in Cre06g306300 expression. ...
In the era of energy and food shortage, microalgae have been gained much attention as promising sources of biofuels and food
ingredients. However, only a small fraction of microalgal genes have been functionally characterized. Here, we have developed
the Algae Gene Coexpression Database (ALCOdb, http://alcodb.jp), which provides gene coexpression information to survey gene modules for a function of interest. ALCOdb currently supports
two model algae: the green alga Chlamydomonas reinhardtii and the red alga Cyanidioschyzon merolae. Users can retrieve coexpression information for genes of interest through three unique data pages: (i) Coexpressed Gene
List, (ii) Gene Information and (iii) Coexpressed Gene Network. In addition to the basal coexpression information, ALCOdb
also provides several advanced functionalities such as an expression profile viewer and a differentially expressed gene search
tool. Using these user interfaces, we demonstrated that our gene coexpression data have the potential to detect functionally
related genes and are useful in extrapolating the biological roles of uncharacterized genes. ALCOdb will facilitate the molecular
and biochemical studies of microalgal biological phenomena, such as lipid metabolism and organelle development, and promote
the evolutionary understanding of plant cellular systems.
Chlamydomonas reinhardtii is a nonpathogenic, nontoxigenic green algae used as a sustainable source of protein in foods. In order to mimic meat-like qualities, a strain rich in protoporphyrin IX (PPIX), an endogenous heme/chlorophyll precursor, was developed using an evolution and selection strategy, and investigations were carried out to evaluate the safety of the novel strain, C. reinhardtii (red), strain TAI114 (TAI114). Digestibly and proteomic evaluations were conducted to determine whether any potentially allergenic or toxic proteins occurred as the result of the mutation process. The genotoxic potential of pure PPIX was evaluated using a bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test, and an in vivo mammalian micronucleus test. Finally, the novel TAI114 biomass was evaluated for general toxicity and identification of target organs in a 90-day repeated-dose oral toxicity study in rats. All proteins were rapidly degraded in pepsin at pH 2.0 suggesting low allergenic potential. The proteomic evaluation indicated that TAI114 biomass contains typical C. reinhardtii proteins. PPIX was unequivocally negative for genotoxic potential and no target organs or adverse effects were observed in rats up to the maximum feasible dose of 4000 mg/kg bw/day TAI114 biomass, which was determined to be the no-observed-adverse-effect-level (NOAEL). These results support the further development and risk characterization of TAI114 biomass as a novel ingredient for use in the meat analogue category of food.
