Zeitschriftenartikel: „Klebsormidium nitens“

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Valchev, Dobril, Irina Ribarova, Blagoy Uzunov und Maya Stoyneva-Gärtner. „Photo-sequencing batch reactor with Klebsormidium nitens: a promising microalgal biotechnology for sustainable phosphorus management in wastewater treatment plants“. Water Science and Technology 83, Nr. 10 (16.04.2021): 2463–76. http://dx.doi.org/10.2166/wst.2021.149.

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Abstract This study aims at improving the existing algal-based wastewater treatment technologies by overcoming some of the major drawbacks of these systems such as large required land area, culture contamination, and energy-intensive algal harvesting. The experiments were carried out in an open photo-sequencing batch reactor at a laboratory-scale for nearly 2 months. A specific strain ACUS00207 of the aeroterrestrial green microalga Klebsormidium nitens (Kützing) Lokhorst was used. The strain is native to Bulgaria and belongs to a species that has never been used before in suspended growth systems for wastewater treatment for phosphorus removal. The culture of K. nitens showed promising results: phosphorus removal rates ranging from 0.4 to 1 mg total phosphorus L−1 d−1, efficient settling properties, and resistance to culture contamination with native microalgae. On the basis of the observed phosphorus removal mechanism of biologically mediated chemical precipitation/phosphorus precipitation, an innovative working mode of the sequencing batch reactor is suggested for reducing the hydraulic retention time and the required land area.

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Petlyovana, V., und Chen Minglei. „Purification of microalgae crops of ACKU collection from fungal contaminants“. Bulletin of Taras Shevchenko National University of Kyiv. Series: Biology 83, Nr. 4 (2020): 29–32. http://dx.doi.org/10.17721/728_2748.2020.83.29-32.

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The work is focused to the selection of the best purification methods of microalgae strains from ACKU collection (Algae Culture Collection of Kyiv University) from contamination by microscopic fungi. The screening of microalgae culture collection ACKU (Algae Culture Collection of Kyiv University) is deal. Contamination of some microalgae strains by fungi of Cladosporium Link, Alternaria Nees, and Monilia Bonord genera was detected. The following strains were selected for the experiment: ACKU 139-02 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell), ACKU 293-04 (Acutodesmus obliquus (Turpin) P. Tsarenko), ACKU 364-04 (cf. Chlorosarcinopsis dissociata Herndon), ACKU 599-06 (Klebsormidium nitens Menegh. in Kützing), ACKU 600-06 (Klebsormidium flaccidum (Kütz.) PC Silva, Mattox et Blackwell) и ACKU 1056 (Desmodesmus abundans (Kirchn.) E. Hegew.). The effect of carbendazim (Methylbenzimidazol-2-ylcarbamate), Antibiotic Antimycotic Solution (penicillin – 10,000 IU, streptomycin – 10 mg, amphotericin B – 25 μg) and Nuosept BMc 422 on fungi-contaminants of green algal culture strains with different morphological structure (coccoid and filamentous) was studied. Experimental concentrations of substances: carbendazim – 0.005%, Antibiotic Antimycotic Solution – 1%, Nuosept BMc 422 – 0.05% and 0.2%. Was shown that Antibiotic-Antimycotic Solution and Nuosept BMc-422 at the selected concentrations were not effective for purifying of green algae strains from significant contamination by microscopic fungi. It was found that the carbendazim solution is effective in the purification of cocoid green algae strains from contamination by microscopic fungi Cladosporium cladosporioides (Fresen.) G.A. de Vries). As a result, an axenic culture was obtained for the ACKU strain No.293-04 (A. obliquus).

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Allaguvatova, Rezeda Z., Arthur Yu Nikulin, Vyacheslav Yu Nikulin, Veronika B. Bagmet und Lira A. Gaysina. „Study of Biodiversity of Algae and Cyanobacteria of Mutnovsky and Gorely Volcanoes Soils (Kamchatka Peninsula) Using a Polyphasic Approach“. Diversity 14, Nr. 5 (07.05.2022): 375. http://dx.doi.org/10.3390/d14050375.

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Volcanic activity has a significant influence on the development of terrestrial ecosystems, including the Kamchatka Peninsula. We aimed to study the terrestrial algoflora of the Mutnovsky and Gorely volcanoes based on the use of clonal cultures of algae and cyanobacteria, and phenotypic and molecular genetic analyses. A total of 48 taxa were identified: 9 cyanobacteria, 32 Chlorophyta (11 Chlorophyceae, 21 Trebouxiophyceae), 3 Ochrophyta, and 4 Charophyta. In soils of the Mutnovsky volcano, 30 taxa were found, and in soils of the Gorely volcano, 24 were observed. In the studied area, small coccoid or mucilage-producing algae, which belong to cosmopolitan species, were identified, including representatives of the genera Bracteacoccus, Chlorococcum, Coccomyxa, Coelastrella, Klebsormidium, Neocystis, and Vischeria. Certain taxa were detected for the first time in the studied region, including Bracteacoccus bullatus, Chlorococcum hypnosporum, Chlorococcum lobatum, Coccomyxa subellipsoidea, Klebsormidium nitens, Leptosira obovata, Lobosphaera incisa, Parietochloris pseudoalveolaris, Stenomitos tremulus, and Vischeria magna. Our analysis of the algal communities at different altitudes reveals expansion in species richness with increasing distance from the tops of the volcanoes. The obtained data allowed us to estimate the real biodiversity of terrestrial algae and cyanobacteria of Kamchatkan volcanic soils, as well as the ecologies of these microorganisms.

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Ohtaka, Kinuka, Koichi Hori, Yuri Kanno, Mitsunori Seo und Hiroyuki Ohta. „Primitive Auxin Response without TIR1 and Aux/IAA in the Charophyte Alga Klebsormidium nitens“. Plant Physiology 174, Nr. 3 (22.05.2017): 1621–32. http://dx.doi.org/10.1104/pp.17.00274.

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Takano, Hiroyoshi, Takashi Tsunefuka, Susumu Takio, Hayato Ishikawa und Katsuaki Takechi. „Visualization of Plastid Peptidoglycan in the Charophyte Alga Klebsormidium nitens Using a Metabolic Labeling Method“. CYTOLOGIA 83, Nr. 4 (25.12.2018): 375–80. http://dx.doi.org/10.1508/cytologia.83.375.

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Valchev, Dobril, Irina Ribarova, Blagoy Uzunov, Maya Stoyneva-Gärtner und Valentina Lyubomirova. „Reclamation Potential of Onsite Wastewater Post-Treatment with Microalgae: Chemical Elements Perspective“. Processes 11, Nr. 6 (15.06.2023): 1819. http://dx.doi.org/10.3390/pr11061819.

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Algae-based wastewater treatment is a promising technology with various applications for excess biomass such as biofertilizer production or valuable elements extraction. The benefits of the technology have been discussed for larger wastewater treatment plants (WWTPs), but the use of microalgae in decentralized wastewater treatment has been barely reported. The current study screens the possible resource recovery potential of onsite technology, which adds algae-based post-treatment to the conventional biological treatment of domestic wastewater. The effluent from the onsite sequencing batch reactor (SBR) of a household was further processed in laboratory conditions using an SBR technology with two local monocultures of algae—Klebsormidium nitens (Kützing) Lokhorst and Tetradesmus obliquus (Turpin) M. J. Wynne. The decant and the generated algal biomass were analyzed in terms of their element content. The post-treated effluent has a slightly better quality for irrigation purposes than the effluent of the onsite treatment facility—up to 1.6 times increased concentration for macro-elements and up to 1.9 times for micro elements. However, the generated algal biomass shows promising potential for re-use as a fertilizing agent since it contains valuable macro- and micro-elements and the heavy (hazardous) metal content is considerably lower than the limiting values in the current European and national legislations. The K. nitens strain may attract interest since it accumulates valuable metals such as chromium (36 mg/kgDS), nickel (83 mg/kgDS), and silver (0.7 mg/kgDS) that can be derived from the biomass and turn the technology to a circular one.

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Segura-Morales, F. J., A. Molina-Miras, M. C. Cerón-García, A. Sánchez-Mirón, S. Seoane, A. Contreras-Gómez und F. García-Camacho. „Unveiling potential of promising filamentous microalga Klebsormidium cf. nitens: Shear stress resilience and carotenoid-fatty acid dynamics in tubular photobioreactor“. Bioresource Technology 407 (September 2024): 131147. http://dx.doi.org/10.1016/j.biortech.2024.131147.

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Yang, Kim, Kim und Suh. „Functional Characterization of Physcomitrella patens Glycerol-3-Phosphate Acyltransferase 9 and an Increase in Seed Oil Content in Arabidopsis by Its Ectopic Expression“. Plants 8, Nr. 8 (13.08.2019): 284. http://dx.doi.org/10.3390/plants8080284.

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Since vegetable oils (usually triacylglycerol [TAG]) are extensively used as food and raw materials, an increase in storage oil content and production of valuable polyunsaturated fatty acids (PUFAs) in transgenic plants is desirable. In this study, a gene encoding glycerol-3-phosphate acyltransferase 9 (GPAT9), which catalyzes the synthesis of lysophosphatidic acid (LPA) from a glycerol-3-phosphate and acyl-CoA, was isolated from Physcomitrella patens, which produces high levels of very-long-chain PUFAs in protonema and gametophores. P. patens GPAT9 shares approximately 50%, 60%, and 70% amino acid similarity with GPAT9 from Chlamydomonas reinhardtii, Klebsormidium nitens, and Arabidopsis thaliana, respectively. PpGPAT9 transcripts were detected in both the protonema and gametophores. Fluorescent signals from the eYFP:PpGPAT9 construct were observed in the ER of Nicotiana benthamiana leaf epidermal cells. Ectopic expression of PpGPAT9 increased the seed oil content by approximately 10% in Arabidopsis. The levels of PUFAs (18:2, 18:3, and 20:2) and saturated FAs (16:0, 18:0, and 20:0) increased by 60% and 43%, respectively, in the storage oil of the transgenic seeds when compared with the wild type. The transgenic embryos with increased oil content contained larger embryonic cells than the wild type. Thus, PpGPAT9 may be a novel genetic resource to enhance storage oil yields from oilseed crops.

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Kuroiwa, Tsuneyoshi, Mio Ohnuma, Yuuta Imoto und Haruko Kuroiwa. „Lipid Droplet Formation in Cells of the Filamentous Green Alga Klebsormidium nitens as Revealed by BODIOY-DiOC6 and BODIPY-Nile Red Double-Staining Microscopy“. CYTOLOGIA 79, Nr. 4 (2014): 501–7. http://dx.doi.org/10.1508/cytologia.79.501.

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Solis, Celymar Angela, Miing-Tiem Yong, Meixue Zhou, Gayatri Venkataraman, Lana Shabala, Paul Holford, Sergey Shabala und Zhong-Hua Chen. „Evolutionary Significance of NHX Family and NHX1 in Salinity Stress Adaptation in the Genus Oryza“. International Journal of Molecular Sciences 23, Nr. 4 (14.02.2022): 2092. http://dx.doi.org/10.3390/ijms23042092.

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Rice (Oryza sativa), a staple crop for a substantial part of the world’s population, is highly sensitive to soil salinity; however, some wild Oryza relatives can survive in highly saline environments. Sodium/hydrogen antiporter (NHX) family members contribute to Na+ homeostasis in plants and play a major role in conferring salinity tolerance. In this study, we analyzed the evolution of NHX family members using phylogeny, conserved domains, tertiary structures, expression patterns, and physiology of cultivated and wild Oryza species to decipher the role of NHXs in salt tolerance in Oryza. Phylogenetic analysis showed that the NHX family can be classified into three subfamilies directly related to their subcellular localization: endomembrane, plasma membrane, and tonoplast (vacuolar subfamily, vNHX1). Phylogenetic and structural analysis showed that vNHX1s have evolved from streptophyte algae (e.g., Klebsormidium nitens) and are abundant and highly conserved in all major land plant lineages, including Oryza. Moreover, we showed that tissue tolerance is a crucial trait conferring tolerance to salinity in wild rice species. Higher Na+ accumulation and reduced Na+ effluxes in leaf mesophyll were observed in the salt-tolerant wild rice species O. alta, O. latifolia, and O. coarctata. Among the key genes affecting tissue tolerance, expression of NHX1 and SOS1/NHX7 exhibited significant correlation with salt tolerance among the rice species and cultivars. This study provides insights into the evolutionary origin of plant NHXs and their role in tissue tolerance of Oryza species and facilitates the inclusion of this trait during the development of salinity-tolerant rice cultivars.

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Kondakova, L. V., N. V. Syrchina, L. V. Pilip und I. A. Kondakova. „Manure runoff impact on soil phototrophic microorganisms“. Theoretical and Applied Ecology, Nr. 2 (26.06.2023): 190–97. http://dx.doi.org/10.25750/1995-4301-2023-2-190-197.

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Soil phototrophic microorganisms (algae, cyanobacteria) play a very important role in functioning of anthropogenic systems. They take an active part in soil self-purification by directly absorbing biogenic elements, as well as by stimulating the activity of mineralizing microorganisms at the expense of disengaged oxygen. The research was carried out at a plough field with sod-podzol soil situated near a large pig-breeding farm. Neutralization took place due to natural microbiological processes during the time of disgorging the liquid fraction in the lagoons. Long-term application of manure runoff from pig-breeding farms into plough soil had an impact on species diversity of phototrophic microorganisms, which was considered in the research. Groups of species tolerant to the impact formed in the soil in course of long-term application of liquid manure fraction. The influence of long-term runoff of manure from pig breeding farms on specious diversity of soil phototrophic microorganisms was assessed. In plough soils affected by liquid manure runoff a group of species tolerant to this impact has formed. Their basis is represented by green algae: Klebsormidium flaccidum, K. nitens, Chlorococcum infusionum, Chlorella vulgaris, as well as by the heterocyst-free cyanobacteria Phormidium autumnale and the diatom alga Hantzschia amphioxys. On the surface of plough soil these species make microscopically marked films, i. e. soil “blooming” takes place. General species diversity of microphototrophs in soil of the experimental site is lower than that of the control site. Jaccard coefficient of the experimental and control sites of the field is 47.8%. Nitrogen-fixing cyanobacteria are not represented in the microphototrophic community; it indicates that the natural microcoenosis is damaged in the plough soils and nitrogen content is high.

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Chatelain, Pauline, Cécile Blanchard, Jeremy Astier, Agnès Klinguer, David Wendehenne, Sylvain Jeandroz und Claire Rosnoblet. „Reliable reference genes and abiotic stress marker genes in Klebsormidium nitens“. Scientific Reports 12, Nr. 1 (08.11.2022). http://dx.doi.org/10.1038/s41598-022-23783-9.

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AbstractMicroalgae have recently emerged as a key research topic, especially as biological models. Among them, the green alga Klebsormidium nitens, thanks to its particular adaptation to environmental stresses, represents an interesting photosynthetic eukaryote for studying the transition stages leading to the colonization of terrestrial life. The tolerance to different stresses is manifested by changes in gene expression, which can be monitored by quantifying the amounts of transcripts by RT-qPCR. The identification of optimal reference genes for experiment normalization was therefore necessary. In this study, using four statistical algorithms followed by the RankAggreg package, we determined the best reference gene pairs suitable for normalizing RT-qPCR data in K. nitens in response to three abiotic stresses: high salinity, PEG-induced dehydration and heat shock. Based on these reference genes, we were able to identify marker genes in response to the three abiotic stresses in K. nitens.

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Sharma, Sunita, Avinash Kumar Gautam, Rajani Singh, Samudrala Gourinath und Suneel Kateriya. „Unusual photodynamic characteristics of the light‐oxygen‐voltage domain of phototropin linked to terrestrial adaptation of Klebsormidium nitens“. FEBS Journal, 29.09.2024. http://dx.doi.org/10.1111/febs.17284.

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Phototropin (Phot), a blue light‐sensing LOV domain protein, mediates blue light responses and is evolutionarily conserved across the green lineage. Klebsormidium nitens, a green terrestrial alga, presents a valuable opportunity to study adaptive responses from aquatic to land habitat transitions. We determined the crystal structure of Klebsormidium nitens Phot LOV1 domain (KnLOV1) in the dark and engineered different mutations (R60K, Q122N, and D33N) to modulate the lifetime of the photorecovery cycle. We observed unusual, slow recovery kinetics in the wild‐type KnLOV1 domain (τ = 41 ± 3 min) compared to different mutants (R60K: τ = 2.0 ± 0.1 min, Q122N: τ = 1.7 ± 0.1 min, D33N: τ = 9.6 ± 0.1 min). Crystal structures of wild‐type KnLOV1 and mutants revealed subtle but critical changes near the protein chromophore that is responsible for modulating protein dark recovery time. Our findings shed light on the unique structural and biochemical characteristics of the newly studied KnLOV1 and its evolutionary importance for phototropin‐mediated physiology.

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Tounosu, Noriaki, Kanami Sesoko, Koichi Hori, Mie Shimojima und Hiroyuki Ohta. „Cis-regulatory elements and transcription factors related to auxin signaling in the streptophyte algae Klebsormidium nitens“. Scientific Reports 13, Nr. 1 (15.06.2023). http://dx.doi.org/10.1038/s41598-023-36500-x.

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AbstractThe phytohormone auxin affects numerous processes in land plants. The central auxin signaling machinery, called the nuclear auxin pathway, is mediated by its pivotal receptor named TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFB). The nuclear auxin pathway is widely conserved in land plants, but auxin also accumulates in various algae. Although auxin affects the growth of several algae, the components that mediate auxin signaling have not been identified. We previously reported that exogenous auxin suppresses cell proliferation in the Klebsormidium nitens that is a member of streptophyte algae, a paraphyletic group sharing the common ancestor with land plants. Although K. nitens lacks TIR1/AFB, auxin affects the expression of numerous genes. Thus, elucidation of the mechanism of auxin-inducible gene expression in K. nitens would provide important insights into the evolution of auxin signaling. Here, we show that some motifs are enriched in the promoter sequences of auxin-inducible genes in K. nitens. We also found that the transcription factor KnRAV activates several auxin-inducible genes and directly binds the promoter of KnLBD1, a representative auxin-inducible gene. We propose that KnRAV has the potential to regulate auxin-responsive gene expression in K. nitens.

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Frascogna, Federica, Benjamin Ledermann, Jana Hartmann, Eugenio Pérez Patallo, Fjoralba Zeqiri, Eckhard Hofmann und Nicole Frankenberg-Dinkel. „On the evolution of the plant phytochrome chromophore biosynthesis“. Plant Physiology, 13.06.2023. http://dx.doi.org/10.1093/plphys/kiad327.

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Abstract Phytochromes are biliprotein photoreceptors present in plants, algae, certain bacteria and fungi. Land plant phytochromes use phytochromobilin (PΦB) as the bilin chromophore. Phytochromes of streptophyte algae, the clade within which land plants evolved, employ phycocyanobilin (PCB), leading to a more blue-shifted absorption spectrum. Both chromophores are synthesized by ferredoxin-dependent bilin reductases (FDBRs) starting from biliverdin IXα (BV). In cyanobacteria and chlorophyta, BV is reduced to PCB by the FDBR phycocyanobilin:ferredoxin oxidoreductase (PcyA), whereas, in land plants, BV is reduced to PФB by phytochromobilin synthase (HY2). However, phylogenetic studies suggested the absence of any ortholog of PcyA in streptophyte algae and the presence of only PФB biosynthesis related genes (HY2). The HY2 of the streptophyte alga Klebsormidium nitens (formerly Klebsormidium flaccidum) has already indirectly been indicated to participate in PCB biosynthesis. Here, we overexpressed and purified a His6-tagged variant of K. nitens HY2 (KflaHY2) in Escherichia coli. Employing anaerobic bilin reductase activity assays and coupled phytochrome assembly assays, we confirmed the product and identified intermediates of the reaction. Site-directed mutagenesis revealed two aspartate residues critical for catalysis. While it was not possible to convert KflaHY2 into a PΦB-producing enzyme by simply exchanging the catalytic pair, the biochemical investigation of two additional members of the HY2 lineage enabled us to define two distinct clades, the PCB-HY2 and the PΦB-HY2 clade. Overall, our study gives insight into the evolution of the HY2 lineage of FDBRs.

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Zhong, Ruiqin, Earle R. Adams und Zheng-Hua Ye. „Ancient origin of acetyltransferases catalyzing O-acetylation of plant cell wall polysaccharides“. Plant And Cell Physiology, 25.06.2024. http://dx.doi.org/10.1093/pcp/pcae070.

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Abstract Members of the domain of unknown function 231 (DUF231)/trichome birefringence-like (TBL) family have been shown to be O-acetyltransferases catalyzing the acetylation of plant cell wall polysaccharides, including pectins, mannan, xyloglucan and xylan. However, little is known about the origin and evolution of plant cell wall polysaccharide acetyltransferases. Here, we investigated the biochemical functions of TBL homologs from Klebsormidium nitens, a representative of an early divergent class of charophyte green algae that are considered to be the closest living relatives of land plants, and Marchantia polymorpha, a liverwort that is an extant representative of an ancient lineage of land plants. The genomes of K. nitens and M. polymorpha harbor two and six TBL homologs, respectively. Biochemical characterization of their recombinant proteins expressed in human embryonic kidney (HEK) 293 cells demonstrated that the two K. nitens TBLs exhibited acetyltransferase activities acetylating the pectin homogalacturonan (HG) and hence were named KnPOAT1 and KnPOAT2. Among the six M. polymorpha TBLs, five of them (MpPOAT1 to 5) possessed acetyltransferase activities toward pectins and the remaining one (MpMOAT1) catalyzed 2-O- and 3-O-acetylation of mannan. While MpPOAT1,2 specifically acetylated HG, MpPOAT3,4,5 could acetylate both HG and rhamnogalacturonan-I (RG-I). Consistent with the acetyltransferase activities of these TBLs, pectins isolated from K. nitens and both pectins and mannan from M. polymorpha were shown to be acetylated. These findings indicate that the TBL genes were recruited as cell wall polysaccharide O-acetyltransferases as early as in charophyte green algae with activities toward pectins and they underwent expansion and functional diversification to acetylate various cell wall polysaccharides during evolution of land plants.

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Tashiro, Rintaro, Kumari Sushmita, Shoko Hososhima, Sunita Sharma, Suneel Kateriya, Hideki Kandori und Satoshi P. Tsunoda. „Specific residues in the cytoplasmic domain modulate photocurrent kinetics of channelrhodopsin from Klebsormidium nitens“. Communications Biology 4, Nr. 1 (23.02.2021). http://dx.doi.org/10.1038/s42003-021-01755-5.

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AbstractChannelrhodopsins (ChRs) are light-gated ion channels extensively applied as optogenetics tools for manipulating neuronal activity. All currently known ChRs comprise a large cytoplasmic domain, whose function is elusive. Here, we report the cation channel properties of KnChR, one of the photoreceptors from a filamentous terrestrial alga Klebsormidium nitens, and demonstrate that the cytoplasmic domain of KnChR modulates the ion channel properties. KnChR is constituted of a 7-transmembrane domain forming a channel pore, followed by a C-terminus moiety encoding a peptidoglycan binding domain (FimV). Notably, the channel closure rate was affected by the C-terminus moiety. Truncation of the moiety to various lengths prolonged the channel open lifetime by more than 10-fold. Two Arginine residues (R287 and R291) are crucial for altering the photocurrent kinetics. We propose that electrostatic interaction between the rhodopsin domain and the C-terminus domain accelerates the channel kinetics. Additionally, maximal sensitivity was exhibited at 430 and 460 nm, the former making KnChR one of the most blue-shifted ChRs characterized thus far, serving as a novel prototype for studying the molecular mechanism of color tuning of the ChRs. Furthermore, KnChR would expand the optogenetics tool kit, especially for dual light applications when short-wavelength excitation is required.

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Chatelain, Pauline, Jeremy Astier, David Wendehenne, Claire Rosnoblet und Sylvain Jeandroz. „Identification of Partner Proteins of the Algae Klebsormidium nitens NO Synthases: Toward a Better Understanding of NO Signaling in Eukaryotic Photosynthetic Organisms“. Frontiers in Plant Science 12 (22.12.2021). http://dx.doi.org/10.3389/fpls.2021.797451.

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In animals, NO is synthesized from L-arginine by three isoforms of nitric oxide synthase (NOS) enzyme. NO production and effects have also been reported in plants but the identification of its sources, especially the enzymatic ones, remains one of the critical issues in the field. NOS-like activities have been reported, although there are no homologs of mammalian NOS in the land plant genomes sequenced so far. However, several NOS homologs have been found in algal genomes and transcriptomes. A first study has characterized a functional NOS in the chlorophyte Ostreococcus tauri and the presence of NOS homologs was later confirmed in a dozen algae. These results raise the questions of the significance of the presence of NOS and their molecular diversity in algae. We hypothesize that comparisons among protein structures of the two KnNOS, together with the identification of their interacting partner proteins, might allow a better understanding of the molecular diversification and functioning of NOS in different physiological contexts and, more generally, new insights into NO signaling in photosynthetic organisms. We recently identified two NOS homologs sequences in the genome of the streptophyte Klebsormidium nitens, a model alga in the study of plant adaptation to terrestrial life. The first sequence, named KnNOS1, contains canonical NOS signatures while the second, named KnNOS2, presents a large C-ter extension including a globin domain. In order to identify putative candidates for KnNOSs partner proteins, we draw the protein–protein interaction networks of the three human NOS using the BioGRID database and hypothesized on the biological role of K. nitens orthologs. Some of these conserved partners are known to be involved in mammalian NOSs regulation and functioning. In parallel, our methodological strategy for the identification of partner proteins of KnNOS1 and KnNOS2 by in vitro pull-down assay is presented.

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Arzac, Miren Irati, Jon Miranda‐Apodaca, Francisco Gasulla, María Arce‐Guerrero, Beatriz Fernández‐Marín und José Ignacio García‐Plazaola. „Acquisition of Desiccation Tolerance Unveiled: Polar Lipid Profiles of Streptophyte Algae Offer Insights“. Physiologia Plantarum 175, Nr. 6 (November 2023). http://dx.doi.org/10.1111/ppl.14073.

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AbstractTerrestrialization by photosynthetic eukaryotes took place in the two branches of green microalgae: Chlorophyta and Charophyta. Within the latter, the paraphyletic streptophytic algae divide into two clades. These are named Klebsormidiophyceae‐Chlorokybophyceae‐Mesostigmatophyceae (KCM), which is the oldest, and Zygnematophyceae‐Coleochaetophyceae‐Charophyceae (ZCC), which contains the closest relatives of vascular plants. Terrestrialization required the emergence of adaptations in response to new challenges, such as irradiance, temperature oscillations and water deprivation. In this study, we evaluated lipid composition in species representative of distinct phylogenetic clusters within Charophyta and Chlorophyta. We aim to study whether the inherent thylakoid lipid composition, as well as its adaptability in response to desiccation, were fundamental factors for the evolutionary history of terrestrial plants. The results showed that the lipid composition was similar to that found in flowering land plants, differing only in betaine lipids. Likewise, the largest constitutive pool of oligogalactolipids (OGL) was found only in the fully desiccation‐tolerant species Klebsormidium nitens. After desiccation, the content of polar lipids decreased in all species. Conversely, the content of OGL increased, particularly trigalactosyldiacylglycerol and tetragalactosyldiacylglycerol in the ZCC clade. The analysis of the molecular species composition of the newly formed OGL may suggest a different biosynthetic route for the KCM and ZCC clades. We speculate that the appearance of a new OGL synthesis pathway, which eventually arose during the streptophyte evolutionary process, endowed algae with a much more dynamic regulation of thylakoid composition in response to stress, which ultimately contributed to the colonization of terrestrial habitats.

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Slawinski, Lucie, Abir Israel, Caroline Paillot, Florence Thibault, Richard Cordaux, Rossitza Atanassova, Fabienne Dédaldéchamp und Maryse Laloi. „Early Response to Dehydration Six-Like Transporter Family: Early Origin in Streptophytes and Evolution in Land Plants“. Frontiers in Plant Science 12 (06.09.2021). http://dx.doi.org/10.3389/fpls.2021.681929.

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Carbon management by plants involves the activity of many sugar transporters, which play roles in sugar subcellular partitioning and reallocation at the whole organism scale. Among these transporters, the early response to dehydration six-like (ESL) monosaccharide transporters (MSTs) are still poorly characterized although they represent one of the largest sugar transporter subfamilies. In this study, we used an evolutionary genomic approach to infer the evolutionary history of this multigenic family. No ESL could be identified in the genomes of rhodophytes, chlorophytes, and the brown algae Ectocarpus siliculosus, whereas one ESL was identified in the genome of Klebsormidium nitens providing evidence for the early emergence of these transporters in Streptophytes. A phylogenetic analysis using the 519 putative ESL proteins identified in the genomes of 47 Embryophyta species and being representative of the plant kingdom has revealed that ESL protein sequences can be divided into three major groups. The first and second groups originated in the common ancestor of all spermaphytes [ζ: 340 million years ago (MYA)] and of angiosperms (ε: 170–235 MYA), respectively, and the third group originated before the divergence of rosids and asterids (γ/1R: 117 MYA). In some eudicots (Vitales, Malpighiales, Myrtales, Sapindales, Brassicales, Malvales, and Solanales), the ESL family presents remarkable expansions of gene copies associated with tandem duplications. The analysis of non-synonymous and synonymous substitutions for the dN/dS ratio of the ESL copies of the genus Arabidopsis has revealed that ESL genes are evolved under a purifying selection even though the progressive increase of dN/dS ratios in the three groups suggests subdiversification phenomena. To further explore the possible acquisition of novel functions by ESL MSTs, we identified the gene structure and promoter cis-acting elements for Arabidopsis thaliana ESL genes. The expression profiling of Arabidopsis ESL unraveled some gene copies that are almost constitutively expressed, whereas other gene copies display organ-preferential expression patterns. This study provides an evolving framework to better understand the roles of ESL transporters in plant development and response to environmental constraints.

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