Photosynthetic apparatus organization and function in the wild type and a chlorophyll b -less mutant of Chlamydomonas reinhardtii . Dependence on carbon source

Planta ◽  
2000 ◽  
Vol 211 (3) ◽  
pp. 335-344 ◽  
Author(s):  
Juergen E. W. Polle ◽  
John R. Benemann ◽  
Ayumi Tanaka ◽  
Anastasios Melis
Keyword(s):  
Carbon Source ◽  
Chlamydomonas Reinhardtii ◽  
Photosynthetic Apparatus ◽  
Chlorophyll B ◽  
Wild Type ◽  
In The Wild ◽  
And Function

scholarly journals Arabidopsis thaliana cbp80, c2h2, and flk Knockout Mutants Accumulate Increased Amounts of Circular RNAs

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1937
Author(s):  
Anna Philips ◽  
Katarzyna Nowis ◽  
Michal Stelmaszczuk ◽  
Jan Podkowiński ◽  
Luiza Handschuh ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Circular Rnas ◽  
Wild Type ◽  
Proper Order ◽  
Knockout Mutants ◽  
In The Wild ◽  
And Function

Circular RNAs (circRNAs) are the products of the non-canonical splicing of pre-mRNAs. In contrast to humans and animals, our knowledge of the biogenesis and function of circRNAs in plants is very scarce. To identify proteins involved in plant circRNA generation, we characterized the transcriptomes of 18 Arabidopsis thaliana knockout mutants for genes related to splicing. The vast majority (>90%) of circRNAs were formed in more than one variant; only a small fraction of circRNAs was mutant-specific. Five times more circRNA types were identified in cbp80 and three times more in c2h2 mutants than in the wild-type. We also discovered that in cbp80, c2h2 and flk mutants, the accumulation of circRNAs was significantly increased. The increased accumulation of circular transcripts was not accompanied by corresponding changes in the accumulation of linear transcripts. Our results indicate that one of the roles of CBP80, C2H2 and FLK in splicing is to ensure the proper order of the exons. In the absence of one of the above-mentioned factors, the process might be altered, leading to the production of circular transcripts. This suggests that the transition toward circRNA production can be triggered by factors sequestering these proteins. Consequently, the expression of linear transcripts might be regulated through circRNA production.

Phosphatidylinositol phospholipase C mediates carbon sensing and vegetative nuclear duplication rates in Aspergillus nidulans

2011 ◽  
Vol 57 (7) ◽  
pp. 611-616 ◽  
Author(s):  
Ana Paula de Figueiredo Conte Vanzela ◽  
Suraia Said ◽  
Rolf Alexander Prade
Keyword(s):  
Molecular Weight ◽  
Carbon Source ◽  
Phospholipase C ◽  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Deficient Mutant ◽  
Wild Type ◽  
Pectinolytic Enzymes ◽  
In The Wild ◽  
Phosphatidylinositol Phospholipase C

In this work, we disrupted one of three putative phosphatidylinositol phospholipase C genes of Aspergillus nidulans and studied its effect on carbon source sensing linked to vegetative mitotic nuclear division. We showed that glucose does not affect nuclear division rates during early vegetative conidial germination (6–7 h) in either the wild type or the plcA-deficient mutant. Only after 8 h of cultivation on glucose did the mutant strain present some decrease in nuclear duplication. However, decreased nuclear division rates were observed in the wild type when cultivated in media amended with polypectate, whereas our plcA-deficient mutant did not show slow nuclear duplication rates when grown on this carbon source, even though it requires induction and secretion of multiple pectinolytic enzymes to be metabolized. Thus, plcA appears to be directly linked to high-molecular-weight carbon source sensing.

scholarly journals Three-dimensional Organization of Basal Bodies from Wild-Type and δ-Tubulin Deletion Strains of Chlamydomonas reinhardtii

2003 ◽  
Vol 14 (7) ◽  
pp. 2999-3012 ◽  
Author(s):  
Eileen T. O'Toole ◽  
Thomas H. Giddings ◽  
J. Richard McIntosh ◽  
Susan K. Dutcher
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Specimen Preparation ◽  
Basal Bodies ◽  
Wild Type ◽  
Tubulin Isoforms ◽  
Striated Fiber ◽  
And Function

Improved methods of specimen preparation and dual-axis electron tomography have been used to study the structure and organization of basal bodies in the unicellular alga Chlamydomonas reinhardtii. Novel structures have been found in both wild type and strains with mutations that affect specific tubulin isoforms. Previous studies have shown that strains lacking δ-tubulin fail to assemble the C-tubule of the basal body. Tomographic reconstructions of basal bodies from the δ-tubulin deletion mutant uni3-1 have confirmed that basal bodies contain mostly doublet microtubules. Our methods now show that the stellate fibers, which are present only in the transition zone of wild-type cells, repeat within the core of uni3-1 basal bodies. The distal striated fiber is incomplete in this mutant, rootlet microtubules can be misplaced, and multiflagellate cells have been observed. A suppressor of uni3-1, designated tua2-6, contains a mutation in α-tubulin. tua2-6; uni3-1 cells build both flagella, yet they retain defects in basal body structure and in rootlet microtubule positioning. These data suggest that the presence of specific tubulin isoforms in Chlamydomonas directly affects the assembly and function of both basal bodies and basal body-associated structures.

scholarly journals Physiological response of two different Chlamydomonas reinhardtii strains to light–dark rhythms

Botany ◽  
2016 ◽  
Vol 94 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Michael Sandmann ◽  
Andreas Garz ◽  
Ralf Menzel
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Cell Volume ◽  
Dark Respiration ◽  
Starch Content ◽  
Saturation Index ◽  
Cell Physiology ◽  
Wild Type ◽  
Cell Productivity ◽  
In The Wild ◽  
Entire Cell

Cells of a cell-wall deficient line (cw15-type) of Chlamydomonas reinhardtii and of the corresponding wild type were grown during repetitive light–dark cycles. In a direct comparison, both lines showed approximately the same relative biomass increase during light phase but the cw-line produced significantly more, and smaller, daughter cells. Throughout the light period the average cellular starch content, the cellular chlorophyll content, the cellular rate of dark respiration, and the cellular rate of photosynthesis of the cw-line was lower. Despite this, several non-cell volume related parameters like the development of starch content per cell volume were clearly different over time between the strains. Additionally, the chlorophyll-based photosynthesis rates were 2-fold higher in the mutant than in the wild-type cells, and the ratio of chlorophyll a to chlorophyll b as well as the light-saturation index were also consistently higher in the mutant cells. Differences in the starch content were also confirmed by single cell analyses using a sensitive SHG-based microscopy approach. In summary, the cw15-type mutant deviates from its genetic background in the entire cell physiology. Both lines should be used in further studies in comparative systems biology with focus on the detailed relation between cell volume increase, photosynthesis, starch metabolism, and daughter cell productivity.

scholarly journals Multiple Translational Control Sequences in the 5′ Leader of the Chloroplast psbC mRNA Interact With Nuclear Gene Products in Chlamydomonas reinhardtii

Genetics ◽  
2003 ◽  
Vol 163 (3) ◽  
pp. 895-904
Author(s):  
William Zerges ◽  
Andrea H Auchincloss ◽  
Jean-David Rochaix
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Reporter Gene ◽  
Translational Control ◽  
Nuclear Gene ◽  
Gene Products ◽  
Wild Type ◽  
Translation Initiation Region ◽  
Mrna Stabilization ◽  
In The Wild ◽  
Nuclear Loci

Abstract Translation of the chloroplast psbC mRNA in the unicellular eukaryotic alga Chlamydomonas reinhardtii is controlled by interactions between its 547-base 5′ untranslated region and the products of the nuclear loci TBC1, TBC2, and possibly TBC3. In this study, a series of site-directed mutations in this region was generated and the ability of these constructs to drive expression of a reporter gene was assayed in chloroplast transformants that are wild type or mutant at these nuclear loci. Two regions located in the middle of the 5′ leader and near the initiation codon are important for translation. Other deletions still allow for partial expression of the reporter gene in the wild-type background. Regions with target sites for TBC1 and TBC2 were identified by estimating the residual translation activity in the respective mutant backgrounds. TBC1 targets include mostly the central part of the leader and the translation initiation region whereas the only detected TBC2 targets are in the 3′ part. The 5′-most 93 nt of the leader are required for wild-type levels of transcription and/or mRNA stabilization. The results indicate that TBC1 and TBC2 function independently and further support the possibility that TBC1 acts together with TBC3.

Characterization of a norflurazon-resistant mutant of Chlamydomonas reinhardtii

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 374-377 ◽  
Author(s):  
Varsha Vartak ◽  
Sujata Bhargava
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Mode Of Action ◽  
Resistant Mutant ◽  
Phytoene Desaturase ◽  
Wild Type ◽  
Cross Tolerance ◽  
In The Wild ◽  
Similar Mode ◽  
Target Enzyme

A norflurazon-resistant mutant has been isolated from Chlamydomonas reinhardtii that showed a three-fold factor of resistance over wild type cultures. In comparison to wild type cultures, the mutant showed better retention of chlorophylls and carotenoids when grown in light in the presence of norflurazon. When grown in the dark, chlorophyll losses were similar, while carotenoid losses were lower than in the wild type cultures. Higher levels of phytoene accumulated in the wild type cultures in the presence of norflurazon than in the resistant cultures. The resistant cultures also showed cross tolerance to EMD-IT 5914, a herbicide with a similar mode of action. Norflurazon resistance in this alga appears to arise from alterations in the target enzyme phytoene desaturase.

Consequences of High CO2-Concentrations in Air on Growth and Gas-Exchange Rates in Tobacco Mutants

1995 ◽  
Vol 50 (11-12) ◽  
pp. 781-788 ◽  
Author(s):  
P He ◽  
K. P Bader ◽  
A Radunz ◽  
G.H Schmid
Keyword(s):  
Gas Exchange ◽  
Photosynthetic Apparatus ◽  
Wild Type ◽  
Induction Kinetics ◽  
Partial Pressures ◽  
In The Wild ◽  
Rate Of Photosynthesis ◽  
Aurea Mutant ◽  
Kinetics Of

Abstract Wild type tobacco N. tabacum var. John William’s Broadleaf and the tobacco aurea mutant Su/su were permanently grown under 700 ppm CO2 in air. In comparison to plants grown under 350 ppm CO2 in air but under otherwise identical conditions growth was substantially enhanced. Gas exchange measurements carried out by mass spectrometry show that the rate of photosynthesis in the wild type and in the mutant is increased by more than 100%. The photorespiratory rate in the wild type measured as 18O2-uptake in the light in the “700 ppm CO2-plants” is not reduced to the extent expected or deduced from experiments in which the 350 ppm system responds under in vitro conditions to 700 ppm CO2. An analysis of the induction kinetics of room temperature fluorescence kinetics of the adapted (700 ppm CO2) system and the control system (350 ppm CO2) under various CO2-partial pressures shows that permanent growth under the elevated CO2-partial pressure leads to a structural modification of the photosynthetic apparatus.

scholarly journals Triacylglyceride Production and Autophagous Responses in Chlamydomonas reinhardtii Depend on Resource Allocation and Carbon Source

2014 ◽  
Vol 13 (3) ◽  
pp. 392-400 ◽  
Author(s):  
Matthew P. Davey ◽  
Irmtraud Horst ◽  
Giang-Huong Duong ◽  
Eleanor V. Tomsett ◽  
Alexander C. P. Litvinenko ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Membrane Lipids ◽  
N Availability ◽  
Wild Type ◽  
Metabolic Switch ◽  
Content Type ◽  
Carbon Supply ◽  
Microalgal Biodiesel ◽  
In The Wild ◽  
Mutant Cells

ABSTRACT To improve the economic viability of microalgal biodiesel, it will be essential to optimize the productivity of fuel molecules such as triacylglyceride (TAG) within the microalgal cell. To understand some of the triggers required for the metabolic switch to TAG production, we studied the effect of the carbon supply (acetate or CO 2 ) in Chlamydomonas reinhardtii (wild type and the starchless sta6 mutant) grown under low N availability. As expected, initial rates of TAG production were much higher when acetate was present than under strictly photosynthetic conditions, particularly for the sta6 mutant, which cannot allocate resources to starch. However, in both strains, TAG production plateaued after a few days in mixotrophic cultures, whereas under autotrophic conditions, TAG levels continued to rise. Moreover, the reduced growth of the sta6 mutant meant that the greatest productivity (measured as mg TAG liter −1 day −1 ) was found in the wild type growing autotrophically. Wild-type cells responded to low N by autophagy, as shown by degradation of polar (membrane) lipids and loss of photosynthetic pigments, and this was less in cells supplied with acetate. In contrast, little or no autophagy was observed in sta6 mutant cells, regardless of the carbon supply. Instead, very high levels of free fatty acids were observed in the sta6 mutant, suggesting considerable alteration in metabolism. These measurements show the importance of carbon supply and strain selection for lipid productivity. Our findings will be of use for industrial cultivation, where it will be preferable to use fast-growing wild-type strains supplied with gaseous CO 2 under autotrophic conditions rather than require an exogenous supply of organic carbon.

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