Neotessella volvocina
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ABSTRACT:
PROVIDER: PRJNA43453 | ENA |
REPOSITORIES: ENA
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Project description:Photoacclimation of unicellular algae allows for reversible changes in the number and/or effective absorption cross section of photosynthetic units on time scales of hours to days in response to changes in irradiance. The process involves an enigmatic signaling pathway from the plastid to the nucleus.Our results reveal, for the first time, a fundamental pathway of retrograde signal transduction in a eukaryotic photosynthetic alga.
2019-11-01 | GSE133301 | GEO
Project description:Transcriptome of a non-photosynthetic green alga
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Project description:Genome sequencing of a non-photosynthetic green alga
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Project description:In the model green alga Chlamydomonas (Chlamydomonas reinhardtii), the synthesis of several chloroplast-encoded photosynthetic subunits is feedback-regulated by the assembly state of the respective protein complex. This regulation is known as control by epistasy of synthesis (CES) and matches protein synthesis with the requirements of protein complex assembly in photosystem II (PSII), the cytochrome b6f complex (Cyt b6f), photosystem I (PSI), ATP synthase and Rubisco . In embryophytes, however, CES was only described to coordinate synthesis of the large and small subunits of Rubisco, raising the question if additional CES mechanisms exist in land plants or if stoichiometric photosynthetic protein accumulation is only achieved by the wasteful degradation of excess subunits. We systematically examined suitable tobacco and Arabidopsis mutants with assembly defects in PSII, PSI, Cyt b6f complex, ATP synthase, NDH (NAD(P)H dehydrogenase-like) complex and Rubisco for feedback regulation. Thereby, we validated the CES in Rubisco and uncovered translational feedback regulation in PSII, involving psbA, psbB, psbD and psbH and in Cyt b6f, connecting PetA and PetB protein synthesis. Remarkably, some of these feedback regulation mechanisms are not conserved between the green alga and embryophytes. Our data do not provide any evidence for CES in PSI, ATP synthase or NDH complex assembly in embryophytes. In addition, our data disclose translational feedback regulation adjusting PSI levels with PSII accumulation. Overall, we discovered commonalities and differences in assembly-dependent feedback regulation of photosynthetic complexes between embryophytes and green algae.
2025-07-01 | GSE286011 | GEO
Project description:For the model alga Chlamydomonas, acclimation to diurnal low light (LL) or high light (HL) results in changes in photosynthetic complexes, chlorophyll content, thylakoid membrane architecture, and nonphotochemical quenching capacity that are maintained through the intervening night phases. To determine how diurnal photoacclimation influences algal fitness and document the molecular events during reacclimation upon a change in daylight intensity, we transitioned LL-acclimated populations to diurnal HL and HL-acclimated populations to diurnal LL and performed an RNA-Seq timecourse over two diurnal periods.
2025-12-16 | GSE307139 | GEO
Project description:Bigelowiella natans is a marine chlorarachniophyte whose plastid was acquired secondarily via endosymbiosis with a green alga. Integrating a photosynthetic endosymbiont within the host metabolism on route to plastid evolution would require the acquisition of strategies for coping with changes in light intensity and modifications of host genes to appropriately respond to changes in photosynthetic metabolism. To investigate the transcriptional response to light intensity in chlorarachniophytes, we conducted an RNA-seq experiment to identify differentially-expressed genes following four-hour shift to high or very-low light. A shift to high light altered the expression of over 2000 genes, many involved with photosynthesis, primary metabolism, and reactive-oxygen scavenging. These changes are related to an attempt to optimize photosynthesis and increase energy sinks for excess reductant, while minimizing photo-oxidative stress. A transfer to very-low light resulted in a lower photosynthetic performance and metabolic alteration, reflecting an energy-limited state. Genes located on the nucleomorph, the vestigial nucleus in the plastid, had few changes in expression in either light treatment, indicating this organelle has relinquished most transcriptional control to the nucleus. Overall, during plastid origin, both host and transferred endosymbiont genes evolved a harmonized transcriptional network to respond to a classic photosynthetic stress.
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Project description:Responses of photosynthetic organisms to sulfur starvation include (i) increasing the capacity of the cell for transporting and/or assimilating exogenous sulfate, (ii) restructuring cellular features to conserve sulfur resources, and (iii) modulating metabolic processes and rates of cell growth and division. We used microarray analyses to obtain a genome-level view of changes in mRNA abundances in the green alga Chlamydomonas reinhardtii during sulfur starvation. The work confirms and extends upon previous findings showing that sulfur deprivation elicits changes in levels of transcripts for proteins that help scavenge sulfate and economize on the use of sulfur resources. Changes in levels of transcripts encoding members of the light-harvesting polypeptide family, such as LhcSR2, suggest restructuring of the photosynthetic apparatus during sulfur deprivation. There are also significant changes in levels of transcripts encoding enzymes involved in metabolic processes (e.g., carbon metabolism), intracellular proteolysis, and the amelioration of oxidative damage; a marked and sustained increase in mRNAs for a putative vanadium chloroperoxidase and a peroxiredoxin may help prolong survival of C. reinhardtii during sulfur deprivation. Furthermore, many of the sulfur stress-regulated transcripts (encoding polypeptides associated with sulfate uptake and assimilation, oxidative stress, and photosynthetic function) are not properly regulated in the sac1 mutant of C. reinhardtii, a strain that dies much more rapidly than parental cells during sulfur deprivation. Interestingly, sulfur stress elicits dramatic changes in levels of transcripts encoding putative chloroplast-localized chaperones in the sac1 mutant but not in the parental strain. These results suggest various strategies used by photosynthetic organisms during acclimation to nutrient-limited growth.
2005-07-22 | E-SMDB-2992 | biostudies-arrayexpress
Project description:Photosystem I (PSI) enables photo-electron transfer and regulates photosynthesis in the bioenergetic membranes of cyanobacteria and chloroplasts. Being a multi-subunit complex, its macromolecular organization affects the dynamics of photosynthetic membranes. Here we reveal a chloroplast PSI from the green alga Chlamydomonas reinhardtii that is organized as a homodimer.
2023-03-11 | PXD027067 | Pride
Project description:Photosystem I (PSI) enables photo-electron transfer and regulates photosynthesis in the bioenergetic membranes of cyanobacteria and chloroplasts. Being a multi-subunit complex, its macromolecular organization affects the dynamics of photosynthetic membranes. Here we reveal a chloroplast PSI from the green alga Chlamydomonas reinhardtii that is organized as a homodimer.
2023-03-11 | PXD026990 | Pride