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1.
Sheng Wu Gong Cheng Xue Bao ; 36(6): 1150-1161, 2020 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-32597064

RESUMO

The aim of this study was to establish a novel technology using microalgae for NO3⁻ removal from high concentration wastewater and conversion to algal proteins. The effects of cultivation modes and illumination modes on the biomass yield, NO3⁻ assimilation rate and algal protein yield were first investigated in shaking flasks for mixotrophic cultivation of Chlorella pyrenoidosa, and subsequently the scale-up verification in 5-L photo fermenter was successfully conducted. Fed-batch cultivation without medium recycling was the best cultivation mode in shaking flask system, in which the highest biomass yield (35.95 g/L), the average NO3⁻ assimilation rate (2.06 g/(L·d)) and algal protein content (up to 42.44% of dry weight) were achieved. By using a staged increase of light intensity as illumination modes, the specific growth rate of cells could be significantly promoted to the highest (0.65 d⁻¹). After a 128-hour continuous cultivation in a 5-L photo fermenter, the highest biomass yield and the average NO3⁻ assimilation rate were reached to 66.22 g/L and 4.38 g/(L·d) respectively, with the highest algal protein content at 47.13% of dry weight. Our study could provide a photo fermentation technology of microalgae for highly efficient treatment of waste industrial nitric acid and/or high concentration nitrate wastewater. This microalgae-based bioconversion process could coproduce protein-rich microalgal biomass, which facilitates the resource utilization of these type wastewater by trash-to-treasure conversion.


Assuntos
Proteínas de Algas , Chlorella , Nitratos , Nitrogênio , Purificação da Água , Proteínas de Algas/biossíntese , Biomassa , Nitratos/isolamento & purificação , Nitratos/metabolismo , Nitrogênio/metabolismo , Águas Residuárias/química , Purificação da Água/métodos
2.
Biochim Biophys Acta Bioenerg ; 1861(5-6): 148183, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32173384

RESUMO

Photosynthetic organisms are frequently exposed to excess light conditions and hence to photo-oxidative stress. To counteract photo-oxidative damage, land plants and most algae make use of non- photochemical quenching (NPQ) of excess light energy, in particular the rapidly inducible and relaxing qE-mechanism. In vascular plants, the constitutively active PsbS protein is the key regulator of qE. In the green algae C. reinhardtii, however, qE activation is only possible after initial high-light (HL) acclimation for several hours and requires the synthesis of LHCSR proteins which act as qE regulators. The precise function of PsbS, which is transiently expressed during HL acclimation in C. reinhardtii, is still unclear. Here, we investigated the impact of different PsbS amounts on HL acclimation characteristics of C. reinhardtii cells. We demonstrate that lower PsbS amounts negatively affect HL acclimation at different levels, including NPQ capacity, electron transport characteristics, antenna organization and morphological changes, resulting in an overall increased HL sensitivity and lower vitality of cells. Contrarily, higher PsbS amounts do not result in a higher NPQ capacity, but nevertheless provide higher fitness and tolerance towards HL stress. Strikingly, constitutively expressed PsbS protein was found to be degraded during HL acclimation. We propose that PsbS is transiently required during HL acclimation for the reorganization of thylakoid membranes and/or antenna proteins along with the activation of NPQ and adjustment of electron transfer characteristics, and that degradation of PsbS is essential in the fully HL acclimated state.


Assuntos
Proteínas de Algas/metabolismo , Chlamydomonas reinhardtii/metabolismo , Chlamydomonas reinhardtii/efeitos da radiação , Transferência de Energia , Luz , Substâncias Protetoras/metabolismo , Proteínas de Algas/ultraestrutura , Chlamydomonas reinhardtii/ultraestrutura , Processos Fotoquímicos , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tilacoides/metabolismo
3.
Nature ; 579(7797): 146-151, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32076272

RESUMO

Photosynthetic organisms have developed various light-harvesting systems to adapt to their environments1. Phycobilisomes are large light-harvesting protein complexes found in cyanobacteria and red algae2-4, although how the energies of the chromophores within these complexes are modulated by their environment is unclear. Here we report the cryo-electron microscopy structure of a 14.7-megadalton phycobilisome with a hemiellipsoidal shape from the red alga Porphyridium purpureum. Within this complex we determine the structures of 706 protein subunits, including 528 phycoerythrin, 72 phycocyanin, 46 allophycocyanin and 60 linker proteins. In addition, 1,598 chromophores are resolved comprising 1,430 phycoerythrobilin, 48 phycourobilin and 120 phycocyanobilin molecules. The markedly improved resolution of our structure compared with that of the phycobilisome of Griffithsia pacifica5 enabled us to build an accurate atomic model of the P. purpureum phycobilisome system. The model reveals how the linker proteins affect the microenvironment of the chromophores, and suggests that interactions of the aromatic amino acids of the linker proteins with the chromophores may be a key factor in fine-tuning the energy states of the chromophores to ensure the efficient unidirectional transfer of energy.


Assuntos
Microscopia Crioeletrônica , Transferência de Energia , Ficobilissomas/química , Ficobilissomas/ultraestrutura , Porphyridium/química , Porphyridium/ultraestrutura , Proteínas de Algas/química , Proteínas de Algas/metabolismo , Proteínas de Algas/ultraestrutura , Modelos Moleculares , Fotossíntese , Ficobilinas/química , Ficobilinas/metabolismo , Ficobilissomas/metabolismo , Conformação Proteica , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Rodófitas/química , Rodófitas/ultraestrutura
4.
BMC Plant Biol ; 20(1): 25, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31941449

RESUMO

BACKGROUND: The marine alga Ulva compressa is the dominant species in copper-polluted coastal areas in northern Chile. It has been shown that the alga tolerates micromolar concentrations of copper and accumulates copper at the intracellular level. Transcriptomic analyses were performed using total RNA of the alga cultivated with 10 µ M copper for 0, 1, 3 and 5 days using RNA-seq in order to identify processes involved in copper tolerance. RESULTS: The levels of transcripts encoding proteins belonging to Light Harvesting Complex II (LHCII), photosystem II (PSII), cytochrome b6f, PSI, LHCI, ATP synthase and proteins involved in repair of PSII and protection of PSI were increased in the alga cultivated with copper. In addition, the level of transcripts encoding proteins of mitochondrial electron transport chain, ATP synthase, and enzymes involved in C, N and S assimilation were also enhanced. The higher percentages of increase in the level of transcripts were mainly observed at days 3 and 5. In contrast, transcripts involved protein synthesis and degradation, signal transduction, and replication and DNA repair, were decreased. In addition, net photosynthesis and respiration increased in the alga cultivated with copper, mainly at days 1 to 3. Furthermore, the activities of enzymes involved in C, N and S assimilation, rubisco, glutamine synthase and cysteine synthase, respectively, were also increased, mainly at days 1 and 3. CONCLUSIONS: The marine alga U. compressa tolerates copper excess through a concomitant increase in expression of proteins involved in photosynthesis, respiration, and C, N and S assimilation, which represents an exceptional mechanism of copper tolerance.


Assuntos
Cobre/efeitos adversos , Fotossíntese/efeitos dos fármacos , Ulva/efeitos dos fármacos , Poluentes Químicos da Água/efeitos adversos , Proteínas de Algas/análise , Carbono/metabolismo , Perfilação da Expressão Gênica , Nitrogênio/metabolismo , Oxigênio/metabolismo , Enxofre/metabolismo , Ulva/metabolismo , Ulva/fisiologia
5.
Mar Genomics ; 52: 100740, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31937506

RESUMO

Brown algae are multicellular photosynthetic stramenopiles that colonize marine rocky shores worldwide. Ectocarpus sp. Ec32 has been established as a genomic model for brown algae. Here we present the genome and metabolic network of the closely related species, Ectocarpus subulatus Kützing, which is characterized by high abiotic stress tolerance. Since their separation, both strains show new traces of viral sequences and the activity of large retrotransposons, which may also be related to the expansion of a family of chlorophyll-binding proteins. Further features suspected to contribute to stress tolerance include an expanded family of heat shock proteins, the reduction of genes involved in the production of halogenated defence compounds, and the presence of fewer cell wall polysaccharide-modifying enzymes. Overall, E. subulatus has mainly lost members of gene families down-regulated in low salinities, and conserved those that were up-regulated in the same condition. However, 96% of genes that differed between the two examined Ectocarpus species, as well as all genes under positive selection, were found to encode proteins of unknown function. This underlines the uniqueness of brown algal stress tolerance mechanisms as well as the significance of establishing E. subulatus as a comparative model for future functional studies.


Assuntos
Genoma/genética , Feófitas/genética , Estresse Fisiológico/genética , Proteínas de Algas/genética , Redes e Vias Metabólicas/genética , Família Multigênica/genética , Vitória
6.
J Photochem Photobiol B ; 202: 111638, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733613

RESUMO

The present study investigates the phycoremediation potentials of two microalgal consortia (MAC1 and MAC2) for treating sewage water and producing biomass with high lipid, protein and chlorophyll contents. During the study, the microalgal strains were tested for lipid enhancement, biomass production and contaminant removal from wastewater. The microalgal consortia showed prolific growth in wastewater with 75% dilution and accumulated higher lipid content of 31.33% dry cell weight in MAC1. The maximum biomass (50% diluted wastewater) for both the consortia was 1.53 and 1.04 gL-1. Total chlorophyll (19.17-25.17 µg mL-1) and protein contents (0.12-0.16 mg mL-1) for both the consortia were found to be maximum in 75 WW. MAC1 was capable of removing 86.27% of total organic carbon and 87.6% of chemical oxygen demand. Approximately, 94% of nitrate and phosphate contents were removed from the initial contents of wastewater. Heavy metal removal efficiency was also found to be better and showed 85.06% Cu, 75.2% Cr, 98.2% Pb, and 99.6% Cd removal by the algal consortia. Pyrolytic decomposition of algal consortia was observed using thermogravimetric analysis. The stepwise decomposition of algae indicated distinct losses of functional groups. The gas chromatography-mass spectrometric analysis revealed the majority of saturated fatty acids followed by monounsaturated and polyunsaturated fatty acids. Thus, the present study proved that both the consortia show tremendous potential for the treatment of domestic wastewaters with successive lipid enhancement for biodiesel production.


Assuntos
Biocombustíveis/análise , Ácidos Graxos/metabolismo , Microalgas/crescimento & desenvolvimento , Eliminação de Resíduos Líquidos/métodos , Proteínas de Algas/metabolismo , Biomassa , Clorofila/análise , Ácidos Graxos/análise , Cromatografia Gasosa-Espectrometria de Massas , Metais Pesados/química , Metais Pesados/metabolismo , Microalgas/metabolismo
7.
BMC Genomics ; 20(1): 975, 2019 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-31830918

RESUMO

BACKGROUND: Alginate is an important cell wall component and mannitol is a soluble storage carbon substance in the brown seaweed Saccharina japonica. Their contents vary with kelp developmental periods and harvesting time. Alginate and mannitol regulatory networks and molecular mechanisms are largely unknown. RESULTS: With WGCNA and trend analysis of 20,940 known genes and 4264 new genes produced from transcriptome sequencing of 30 kelp samples from different stages and tissues, we deduced that ribosomal proteins, light harvesting complex proteins and "imm upregulated 3" gene family are closely associated with the meristematic growth and kelp maturity. Moreover, 134 and 6 genes directly involved in the alginate and mannitol metabolism were identified, respectively. Mannose-6-phosphate isomerase (MPI2), phosphomannomutase (PMM1), GDP-mannose 6-dehydrogenase (GMD3) and mannuronate C5-epimerase (MC5E70 and MC5E122) are closely related with the high content of alginate in the distal blade. Mannitol accumulation in the basal blade might be ascribed to high expression of mannitol-1-phosphate dehydrogenase (M1PDH1) and mannitol-1-phosphatase (M1Pase) (in biosynthesis direction) and low expression of mannitol-2-dehydrogenase (M2DH) and Fructokinase (FK) (in degradation direction). Oxidative phosphorylation and photosynthesis provide ATP and NADH for mannitol metabolism whereas glycosylated cycle and tricarboxylic acid (TCA) cycle produce GTP for alginate biosynthesis. RNA/protein synthesis and transportation might affect alginate complex polymerization and secretion processes. Cryptochrome (CRY-DASH), xanthophyll cycle, photosynthesis and carbon fixation influence the production of intermediate metabolite of fructose-6-phosphate, contributing to high content of mannitol in the basal blade. CONCLUSIONS: The network of co-responsive DNA synthesis, repair and proteolysis are presumed to be involved in alginate polymerization and secretion, while upstream light-responsive reactions are important for mannitol accumulation in meristem of kelp. Our transcriptome analysis provides new insights into the transcriptional regulatory networks underlying the biosynthesis of alginate and mannitol during S. japonica developments.


Assuntos
Perfilação da Expressão Gênica/métodos , Redes Reguladoras de Genes , Laminaria/crescimento & desenvolvimento , Alga Marinha/crescimento & desenvolvimento , Proteínas de Algas/genética , Alginatos/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Sequenciamento de Nucleotídeos em Larga Escala , Laminaria/genética , Manitol/metabolismo , Meristema/genética , Meristema/crescimento & desenvolvimento , Fosforilação Oxidativa , Alga Marinha/genética , Análise de Sequência de RNA
8.
PLoS One ; 14(12): e0226278, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31881027

RESUMO

Wastewater treatment plant effluents are important point sources of micropollutants. To assess how the discharge of treated wastewater affects the ecotoxicity of small to medium-sized streams we collected water samples up- and downstream of 24 wastewater treatment plants across the Swiss Plateau and the Jura regions of Switzerland. We investigated estrogenicity, inhibition of algal photosynthetic activity (photosystem II, PSII) and growth, and acetylcholinesterase (AChE) inhibition. At four sites, we measured feeding activity of amphipods (Gammarus fossarum) in situ as well as water flea (Ceriodaphnia dubia) reproduction in water samples. Ecotoxicological endpoints were compared with results from analyses of general water quality parameters as well as a target screening of a wide range of organic micropollutants with a focus on pesticides and pharmaceuticals using liquid chromatography high-resolution tandem mass spectrometry. Measured ecotoxicological effects in stream water varied substantially among sites: 17ß-estradiol equivalent concentrations (EEQbio, indicating the degree of estrogenicity) were relatively low and ranged from 0.04 to 0.85 ng/L, never exceeding a proposed effect-based trigger (EBT) value of 0.88 ng/L. Diuron equivalent (DEQbio) concentrations (indicating the degree of photosystem II inhibition in algae) ranged from 2.4 to 1576 ng/L and exceeded the EBT value (70 ng/L) in one third of the rivers studied, sometimes even upstream of the WWTP. Parathion equivalent (PtEQbio) concentrations (indicating the degree of AChE inhibition) reached relatively high values (37 to 1278 ng/L) mostly exceeding the corresponding EBT (196 ng/L PtEQbio). Decreased feeding activity by amphipods or decreased water flea reproduction downstream compared to the upstream site was observed at one of four investigated sites only. Results of the combined algae assay (PSII inhibition) correlated best with results of chemical analysis for PSII inhibiting herbicides. Estrogenicity was partly and AChE inhibition strongly underestimated based on measured steroidal estrogens respectively organophosphate and carbamate insecticides. An impact of dissolved organic carbon on results of the AChE inhibition assay was obvious. For this assay more work is required to further explore the missing correlation of bioassay data with chemical analytical data. Overall, the discharge of WWTP effluent led to increased estrogenicity, PSII and AChE inhibition downstream, irrespective of upstream land use.


Assuntos
Anfípodes/fisiologia , Cladóceros/fisiologia , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Águas Residuárias/análise , Águas Residuárias/toxicidade , Acetilcolinesterase/metabolismo , Proteínas de Algas/efeitos dos fármacos , Anfípodes/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Cromatografia Líquida , Cladóceros/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Rios/química , Suíça , Espectrometria de Massas em Tandem , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Purificação da Água
9.
Int J Mol Sci ; 21(1)2019 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-31881655

RESUMO

In this work, transcripts encoding three metallothioneins from Ulva compressa (UcMTs) were amplified: The 5'and 3' UTRs by RACE-PCR, and the open reading frames (ORFs) by PCR. Transcripts encoding UcMT1.1 (Crassostrea-like), UcMT2 (Mytilus-like), and UcMT3 (Dreissena-like) showed a 5'UTR of 61, 71, and 65 nucleotides and a 3'UTR of 418, 235, and 193 nucleotides, respectively. UcMT1.1 ORF encodes a protein of 81 amino acids (MW 8.2 KDa) with 25 cysteines (29.4%), arranged as three motifs CC and nine motifs CXC; UcMT2 ORF encode a protein of 90 amino acids (9.05 kDa) with 27 cysteines (30%), arranged as three motifs CC, nine motifs CXC, and one motif CXXC; UcMT3 encode a protein of 139 amino acids (13.4 kDa) with 34 cysteines (24%), arranged as seven motifs CC and seven motifs CXC. UcMT1 and UcMT2 were more similar among each other, showing 60% similarity in amino acids; UcMT3 showed only 31% similarity with UcMT1 and UcMT2. In addition, UcMTs displayed structural similarity with MTs of marine invertebrates MTs and the terrestrial invertebrate Caenorhabtidis elegans MTs, but not with MTs from red or brown macroalgae. The ORFs fused with GST were expressed in bacteria allowing copper accumulation, mainly in MT1 and MT2, and zinc, in the case of the three MTs. Thus, the three MTs allowed copper and zinc accumulation in vivo. UcMTs may play a role in copper and zinc accumulation in U. compressa.


Assuntos
Proteínas de Algas/metabolismo , Metalotioneína/metabolismo , Ulva/enzimologia , Proteínas de Algas/química , Proteínas de Algas/genética , Sequência de Aminoácidos , Clonagem Molecular , Cobre/metabolismo , Escherichia coli/metabolismo , Metalotioneína/química , Metalotioneína/genética , Fases de Leitura Aberta/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Alinhamento de Sequência , Zinco/metabolismo
10.
Aquat Toxicol ; 217: 105317, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31670168

RESUMO

The microalga Chlorella vulgaris is one of the prominent and most widely distributed green microalgae found in aquatic environments, often used in toxicity tests due to its sensitivity to various pollutants. To examine the toxicity of metals found in the effluent discharges from an electroplating industry, physicochemical parameters in the microalga C. vulgaris were measured. pH, turbidity, total dissolved solids, color, and the concentrations of metals such as chromium (1.97 mg/L), mercury (104.2 mg/L), and zinc (167.25 mg/L) were found exceeding the permissible limits. Several endpoints such as total protein content, reactive oxygen species (ROS) production, photosynthetic pigment contents, and antioxidant enzymatic activities, including those of superoxide dismutase (SOD) and catalase (CAT), were measured in C. vulgaris in response to treated electroplating industrial effluent (TEPIE). In addition, concentration-dependent morphological changes were also observed in response to TEPIE. Under both acute and chronic TEPIE exposure, increase in the ROS level was observed indicating increased production of ROS in C. vulgaris cells. The total protein and chlorophyll contents were found to be gradually decreasing in an effluent concentration-dependent manner. Moreover, lower concentrations of effluent stimulated the antioxidant enzyme systems. A concentration-dependent increase was observed in both SOD and CAT enzymatic activities. The results indicated toxic impairments by the effluent on the function of C. vulgaris in response to both acute and chronic exposure, indicating an urgent need of proper treatment processes/modification of the existing one of TEPIE, with continuous monitoring of the discharge of the pollutants into the aquatic ecosystems using biological assays.


Assuntos
Antioxidantes/metabolismo , Chlorella vulgaris/metabolismo , Galvanoplastia , Resíduos Industriais , Metais/toxicidade , Microalgas/metabolismo , Poluentes Químicos da Água/toxicidade , Proteínas de Algas/metabolismo , Catalase/metabolismo , Chlorella vulgaris/efeitos dos fármacos , Chlorella vulgaris/ultraestrutura , Clorofila/metabolismo , Microalgas/efeitos dos fármacos , Microalgas/ultraestrutura , Fotossíntese/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Testes de Toxicidade
11.
Nat Commun ; 10(1): 4061, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492891

RESUMO

Tiny marine green algae issued from two deep branches of the Chlorophyta, the Mamiellophyceae and Chloropicophyceae, dominate different regions of the oceans and play key roles in planktonic communities. Considering that the Mamiellophyceae is the sole lineage of prasinophyte algae that has been intensively investigated, the extent to which these two algal groups differ in their metabolic capacities and cellular processes is currently unknown. To address this gap of knowledge, we investigate here the nuclear genome sequence of a member of the Chloropicophyceae, Chloropicon primus. Among the main biological insights that emerge from this 17.4 Mb genome, we find an unexpected diploid structure for most chromosomes and a propionate detoxification pathway in green algae. Our results support the notion that separate events of genome minimization, which entailed differential losses of genes/pathways, have occurred in the Chloropicophyceae and Mamiellophyceae, suggesting different strategies of adaptation to oceanic environments.


Assuntos
Proteínas de Algas/genética , Clorófitas/genética , Diploide , Genoma , Água do Mar/microbiologia , Transdução de Sinais/genética , Adaptação Fisiológica/genética , Clorófitas/classificação , Evolução Molecular , Mutação INDEL , Oceanos e Mares , Filogenia , Polimorfismo de Nucleotídeo Único
12.
Nat Commun ; 10(1): 4099, 2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31506429

RESUMO

Light is essential for photosynthesis, but the amounts of light that exceed an organism's assimilation capacity can result in oxidative stress and even cell death. Plants and microalgae have developed a photoprotective response mechanism, qE, that dissipates excess light energy as thermal energy. In the green alga Chlamydomonas reinhardtii, qE is regulated by light-inducible photoprotective proteins, but the pathway from light perception to qE is not fully understood. Here, we show that the transcription factors CONSTANS and Nuclear transcription Factor Ys (NF-Ys) form a complex that governs light-dependent photoprotective responses in C. reinhardtii. The qE responses do not occur in CONSTANS or NF-Y mutants. The signal from light perception to the CONSTANS/NF-Ys complex is directly inhibited by the SPA1/COP1-dependent E3 ubiquitin ligase. This negative regulation mediated by the E3 ubiquitin ligase and the CONSTANS/NF-Ys complex is common to photoprotective response in algal photosynthesis and flowering in plants.


Assuntos
Proteínas de Algas/metabolismo , Chlamydomonas/metabolismo , Fotossíntese , Regiões Promotoras Genéticas/genética , Ligação Proteica , Transdução de Sinais , Transcrição Genética , Ubiquitina-Proteína Ligases/metabolismo
13.
Genomics Proteomics Bioinformatics ; 17(3): 260-272, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31494267

RESUMO

Chromochloris zofingiensis represents an industrially relevant and unique green alga, given its capability of synthesizing triacylglycerol (TAG) and astaxanthin simultaneously for storage in lipid droplets (LDs). To further decipher lipid metabolism, the nitrogen deprivation (ND)-induced LDs from C. zofingiensis were isolated, purified, and subjected to proteomic analysis. Intriguingly, many C. zofingiensis LD proteins had no orthologs present in LD proteome of the model alga Chlamydomonas reinhardtii. Seven novel LD proteins (i.e., two functionally unknown proteins, two caleosins, two lipases, and one l-gulonolactone oxidase) and the major LD protein (MLDP), which were all transcriptionally up-regulated by ND, were selected for further investigation. Heterologous expression in yeast demonstrated that all tested LD proteins were localized to LDs and all except the two functionally unknown proteins enabled yeast to produce more TAG. MLDP could restore the phenotype of mldp mutant strain and enhance TAG synthesis in wild-type strain of C. reinhardtii. Although MLDP and caleosins had a comparable abundance in LDs, they responded distinctly to ND at the transcriptional level. The two lipases, instead of functioning as TAG lipases, likely recycled polar lipids to support TAG synthesis. For the first time, we reported that l-gulonolactone oxidase was abundant in LDs and facilitated TAG accumulation. Moreover, we also proposed a novel working model for C. zofingiensis LDs. Taken together, our work unravels the unique characteristics of C. zofingiensis LDs and provides insights into algal LD biogenesis and TAG synthesis, which would facilitate genetic engineering of this alga for TAG improvement.


Assuntos
Proteínas de Algas/metabolismo , Clorófitas/metabolismo , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Proteômica/métodos , Ácidos Graxos/metabolismo , Mutação/genética , Nitrogênio/deficiência , Fases de Leitura Aberta/genética , Fenótipo , Proteoma/metabolismo , Saccharomyces cerevisiae/metabolismo , Triglicerídeos/biossíntese
14.
Aquat Toxicol ; 215: 105281, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31446302

RESUMO

Phthalate esters are highly present in aquatic plastic litter, which can interfere with the biological processes in the wildlife. In this work, the commonly found freshwater microalga Scenedesmus sp. was exposed to environmental concentrations (0.02, 1 and 100 µg L-1) and to a higher concentration (500 µg L-1) of dibutyl phthalate (DBP), which is an environmental pollutant. The growth, pH variation, production of photosynthetic pigments, proteins and carbohydrates were evaluated. The main inhibition effect of DBP on the microalgal growth was observed in the first 48 h of the exposure (EC50: 41.88 µg L-1). A reduction in the photosynthetic pigment concentration was observed for the 0.02, 1 and 100 µg L-1 conditions indicating that the DBP downregulated the growth rate and affected the photosynthetic process. A significant increase in protein production was only observed under 500 µg L-1 DBP exposure. The extracellular carbohydrates production slightly decreased with the presence of DBP, with a stronger decrease occurring in the 500 µg L-1 condition. These results highlight the environmental risk evaluation and ecotoxicological effects of DBP on the production of biovaluable compounds by microalgae. The results also emphasize the importance of assessing the consequences of the environmental concentrations exposure as a result of the DBP dose-dependent correlation effects.


Assuntos
Dibutilftalato/toxicidade , Ecotoxicologia , Plásticos/toxicidade , Scenedesmus/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Proteínas de Algas/biossíntese , Carboidratos/biossíntese , Concentração de Íons de Hidrogênio , Fotossíntese/efeitos dos fármacos , Pigmentos Biológicos/biossíntese , Scenedesmus/crescimento & desenvolvimento
15.
Arch Biochem Biophys ; 672: 108070, 2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31408624

RESUMO

Intrinsically disordered proteins (IDPs) are proteins that provide many functional advantages in a large number of metabolic and signalling pathways. Because of their high flexibility that endows them with pressure-, heat- and acid-resistance, IDPs are valuable metabolic regulators that help algae to cope with extreme conditions of pH, temperature, pressure and light. They have, however, been overlooked in these organisms. In this review, we present some well-known algal IDPs, including the conditionally disordered CP12, a protein involved in the regulation of CO2 assimilation, as probably the best known example, whose disorder content is strongly dependent on the redox conditions, and the essential pyrenoid component 1 that serves as a scaffold for ribulose-1, 5-bisphosphate carboxylase/oxygenase. We also describe how some enzymes are regulated by protein regions, called intrinsically disordered regions (IDRs), such as ribulose-1, 5-bisphosphate carboxylase/oxygenase activase, the A2B2 form of glyceraldehyde-3-phosphate dehydrogenase and the adenylate kinase. Several molecular chaperones, which are crucial for cell proteostasis, also display significant disorder propensities such as the algal heat shock proteins HSP33, HSP70 and HSP90. This review confirms the wide distribution of IDPs in algae but highlights that further studies are needed to uncover their full role in orchestrating algal metabolism.


Assuntos
Proteínas de Algas/metabolismo , Clorófitas/metabolismo , Proteínas Intrinsicamente Desordenadas/metabolismo , Proteínas de Algas/química , Clorófitas/química , Proteínas Intrinsicamente Desordenadas/química , Microalgas/química , Microalgas/metabolismo , Chaperonas Moleculares/química , Chaperonas Moleculares/metabolismo , Fotossíntese/fisiologia
16.
Int J Biol Macromol ; 140: 1073-1083, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31465798

RESUMO

Protein from Haematococcus pluvialis (H. pluvialis) residues after pigment removal was prepared by alkaline extraction and acid precipitation. And the structural and functional properties of protein extracts were measured and analyzed. The effect of extraction conditions (liquid/solid ratio 10-20 mL/g), pH 10-12 and 25-45 °C (temperature) on the yield of H. pluvialis protein (HP) was carried out using Box-Behnken design. Under optimum extraction conditions: liquid/solid 20 mL/g, pH 11.5 and lower extraction temperature 35 °C, the highest extraction yield (81.36%) of HP was gained, which was close to the predicted value (83.32%). The HP exhibited the better functional properties. The solubility could reach 93.65% at pH 10.0; the foaming capacity and stability were 88.32 and 89.62%, respectively; the emulsifying capacity and stability were 161.52 and 48.2%, respectively; the water holding capacity (WHC) and oil absorption capacity (OAC) were 4.06 and 3.29 g/g, respectively. Fourier Transform infrared spectroscopy (FTIR) data of the HP showed the ß-sheet content (30.37%) was the maximum, while α-helix content (14.86%) was the minimum, whereas the content of amino acids was rich in HP. These results demonstrated that the HP had potential use in food industry.


Assuntos
Proteínas de Algas/química , Proteínas de Algas/isolamento & purificação , Microalgas/química , Pigmentos Biológicos/isolamento & purificação , Aminoácidos/análise , Emulsões/química , Concentração de Íons de Hidrogênio , Lipídeos , Modelos Teóricos , Óleos/química , Estrutura Secundária de Proteína , Análise de Regressão , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
17.
BMC Plant Biol ; 19(1): 325, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31324146

RESUMO

BACKGROUND: The heteroside floridoside is a primary photosynthetic product that is known to contribute to osmotic acclimation in almost all orders of Rhodophyta. However, the encoding genes and enzymes responsible for the synthesis of floridoside and its isomeric form, L- or D-isofloridoside, are poorly studied. RESULTS: Here, four putative trehalose-6-phosphate synthase (TPS) genes, designated as PhTPS1, PhTPS2, PhTPS3, and PhTPS4, were cloned and characterized from the red alga Pyropia haitanensis (Bangiophyceae). The deduced amino acid sequence is similar to the annotated TPS proteins of other organisms, especially the UDP-galactose substrate binding sites of PhTPS1, 2, which are highly conserved. Of these, PhTPS1, 4 are involved in the biosynthesis of floridoside and isofloridoside, with isofloridoside being the main product. PhTPS3 is an isofloridoside phosphate synthase, while PhTPS2 exhibits no activity. When challenged by desiccation, high temperature, and salt stress, PhTPS members were expressed to different degrees, but the responses to thermal stress and desiccation were stronger. CONCLUSIONS: Thus, in P. haitanensis, PhTPSs encode the enzymatical activity of floridoside and isofloridoside phosphate synthase and are crucial for the abiotic stress defense response.


Assuntos
Proteínas de Algas/metabolismo , Glucosiltransferases/metabolismo , Glicerol/análogos & derivados , Rodófitas/fisiologia , Trealose/biossíntese , Proteínas de Algas/genética , Proteínas de Algas/fisiologia , Glucosiltransferases/genética , Glicerol/metabolismo , Filogenia , Rodófitas/enzimologia , Rodófitas/genética , Rodófitas/metabolismo , Alinhamento de Sequência , Estresse Fisiológico
18.
Planta ; 250(4): 1379-1385, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31359139

RESUMO

MAIN CONCLUSION: L-Arginine supports growth and resulted in increased PII signaling protein levels and lipid droplet accumulation in the colorless green alga Polytomella parva. Polytomella parva, a model system for nonphotosynthetic green algae, utilizes ammonium and several carbon sources, including ethanol and acetate. We previously reported that P. parva accumulates high amounts of arginine with the key enzyme of the ornithine/arginine biosynthesis pathway, N-acetyl-L-glutamate kinase, exhibiting high activity. Here we demonstrate that L-arginine can be used by this alga as a nitrogen source. Externally supplied arginine directly influenced the levels of PII signaling protein and formation of triacylglycerol (TAG)-filled lipid bodies (LBs). Our results suggest that the nitrogen source, but not nitrogen starvation, may be critical for the accumulation of LBs in a PII-independent manner in P. parva.


Assuntos
Arginina/farmacologia , Clorofíceas/fisiologia , Gotículas Lipídicas/metabolismo , Nitrogênio/metabolismo , Proteínas PII Reguladoras de Nitrogênio/metabolismo , Fosfotransferases (Aceptor do Grupo Carboxila)/metabolismo , Proteínas de Algas/genética , Proteínas de Algas/metabolismo , Clorofíceas/crescimento & desenvolvimento , Gotículas Lipídicas/efeitos dos fármacos , Proteínas PII Reguladoras de Nitrogênio/genética , Fosfotransferases (Aceptor do Grupo Carboxila)/genética , Transdução de Sinais/efeitos dos fármacos , Triglicerídeos/metabolismo
19.
BMC Biotechnol ; 19(1): 53, 2019 07 26.
Artigo em Inglês | MEDLINE | ID: mdl-31349823

RESUMO

BACKGROUND: Increasing CO2 emissions have resulted in ocean acidification, affecting marine plant photosynthesis and changing the nutrient composition of marine ecosystems. The physiological and biochemical processes of marine phytoplankton in response to ocean acidification have been reported, but have been mainly focused on growth and photosynthetic physiology. To acquire a thorough knowledge of the molecular regulation mechanisms, model species with clear genetic background should be selected for systematic study. Phaeodactylum tricornutum is a pennate diatom with the characteristics of small genome size, short generation cycle, and easy to transform. Furthermore, the genome of P. tricornutum has been completely sequenced. RESULTS AND DISCUSSION: In this study, P. tricornutum was cultured at high and normal CO2 concentrations. Cell composition changes during culture time were investigated. The 13C isotope tracing technique was used to determine fractional labeling enrichments for the main cellular components. The results suggested that when lipid content increased significantly under high CO2 conditions, total protein and soluble sugar contents decreased. The 13C labeling experiment indicated that the C skeleton needed for fatty acid C chain elongation in lipid synthesis under high CO2 conditions is not mainly derived from NaHCO3 (carbon fixed by photosynthesis). CONCLUSION: This study indicated that breakdown of intracellular protein and soluble sugar provide C skeleton for lipid synthesis under high CO2 concentration.


Assuntos
Proteínas de Algas/metabolismo , Dióxido de Carbono/metabolismo , Carbono/metabolismo , Diatomáceas/metabolismo , Lipídeos/biossíntese , Açúcares/metabolismo , Isótopos de Carbono/metabolismo , Diatomáceas/genética , Diatomáceas/fisiologia , Ecossistema , Concentração de Íons de Hidrogênio , Espaço Intracelular/metabolismo , Lipogênese , Oceanos e Mares , Fotossíntese , Água do Mar/química , Solubilidade , Açúcares/química
20.
Int J Mol Sci ; 20(12)2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31238532

RESUMO

We have analyzed protein expression in the bleached small vegetative cells of synchronous Scenedesmus vacuolatus to investigate how unicellular algae lived through stress. These cells were subjected to heat treatment (46.5 °C for 1h in dark condition) and then cultured under continuous illumination for 24 h. Flow cytometry analysis of the chlorophyll autofluorescence intensity of S. vacuolatus cells indicated that heat-treated cells were completely bleached within 24 h of light cultivation. Transmission electron microscopy (TEM) images showed that bleached cells maintained thylakoid membrane structure, but with lower contrast. The bleached cells regained green color after 72 h, along with a recovery in contrast, which indicated a return of photosynthetic ability. Two-dimensional gel electrophoresis (2DE) showed that the protein expression patterns were very difference between control and bleached cells. ATP synthase subunits and glutamine synthetase were down-regulated among the many differences, while some of phototransduction, stress response proteins were up-regulated in bleached cells, elucidating bleached cells can undergo changes in their biochemical activity, and activate some stress response proteins to survive the heat stress and then revive. In addition, small heat shock proteins (HSPs), but not HSP40 and HSP70 family proteins, protected the bleaching cells.


Assuntos
Proteínas de Choque Térmico/genética , Temperatura Alta , Fotodegradação , Scenedesmus/fisiologia , Scenedesmus/efeitos da radiação , Estresse Fisiológico , Proteínas de Algas/genética , Cromatografia Líquida , Regulação da Expressão Gênica de Plantas , Proteoma , Proteômica/métodos , Scenedesmus/ultraestrutura , Espectrometria de Massas em Tandem
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