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1.
Cells ; 8(10)2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31614608

RESUMO

Temperature is one of the key factors affecting growth and division of algal cells. High temperature inhibits the cell cycle in Chlamydomonas reinhardtii. At 39 °C, nuclear and cellular divisions in synchronized cultures were blocked completely, while DNA replication was partly affected. In contrast, growth (cell volume, dry matter, total protein, and RNA) remained unaffected, and starch accumulated at very high levels. The cell cycle arrest could be removed by transfer to 30 °C, but a full recovery occurred only in cultures cultivated up to 14 h at 39 °C. Thereafter, individual cell cycle processes began to be affected in sequence; daughter cell release, cell division, and DNA replication. Cell cycle arrest was accompanied by high mitotic cyclindependent kinase activity that decreased after completion of nuclear and cellular division following transfer to 30 °C. Cell cycle arrest was, therefore, not caused by a lack of cyclin-dependent kinase activity but rather a blockage in downstream processes.

2.
J Chromatogr A ; 1605: 460365, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31402108

RESUMO

The analysis of triacylglycerols and phospholipids - phosphatidylcholines allowed the use of shotgun lipidomics to identify very long-chain fatty acids and very long-chain polyunsaturated fatty acids in microalgae. These fatty acids were determined in triacylglycerols by positive electrospray ionization of neutral loss scans of different fatty acids, e.g. 24:0, 24:1ω9, 24:6ω3, 26:0, 26:1ω9, 28:0, 28:1ω9, 28:2ω6, and 28:8ω3. Likewise, very long-chain fatty acids in phosphatidylcholines were identified by negative electrospray ionization mass spectrometry in the selected ion-monitoring of the two most important ions (R1COO- and R2COO-). The limit of detection was determined at 10 nmol/L (∼11 pg/µL) in triacylglycerols and 8.6 nmoles/L (∼8 pg/µL) in phosphatidylcholines. The use of liquid chromatography-mass spectrometry is suitable for very long-chain polyunsaturated fatty acids with up to 8 double bonds due to the time of analysis as well as for reasons of lower thermal stability of polyunsaturated fatty acids towards saturated fatty acids, but gas chromatography-mass spectrometry is better suited for the analysis of saturated very long-chain fatty acids.


Assuntos
Bactérias/metabolismo , Ácidos Graxos/análise , Clorófitas/metabolismo , Ácidos Graxos Insaturados/análise , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Fosfatidilcolinas/análise , Padrões de Referência , Triglicerídeos/análise
3.
Cells ; 8(7)2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31319624

RESUMO

DNA damage is a ubiquitous threat endangering DNA integrity in all living organisms. Responses to DNA damage include, among others, induction of DNA repair and blocking of cell cycle progression in order to prevent transmission of damaged DNA to daughter cells. Here, we tested the effect of the antibiotic zeocin, inducing double stranded DNA breaks, on the cell cycle of synchronized cultures of the green alga Chlamydomonas reinhardtii. After zeocin application, DNA replication partially occurred but nuclear and cellular divisions were completely blocked. Application of zeocin combined with caffeine, known to alleviate DNA checkpoints, decreased cell viability significantly. This was probably caused by a partial overcoming of the cell cycle progression block in such cells, leading to aberrant cell divisions. The cell cycle block was accompanied by high steady state levels of mitotic cyclin-dependent kinase activity. The data indicate that DNA damage response in C. reinhardtii is connected to the cell cycle block, accompanied by increased and stabilized mitotic cyclin-dependent kinase activity.


Assuntos
Bleomicina/toxicidade , Chlamydomonas reinhardtii/efeitos dos fármacos , Citostáticos/toxicidade , Mutagênicos/toxicidade , Cafeína/farmacologia , Pontos de Checagem do Ciclo Celular , Chlamydomonas reinhardtii/genética , Quinases Ciclina-Dependentes/metabolismo , Quebras de DNA de Cadeia Dupla , Replicação do DNA , DNA de Plantas/efeitos dos fármacos
4.
Folia Microbiol (Praha) ; 64(5): 663-672, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31347103

RESUMO

Most cells divide into two daughter cells; however, some green algae can have different division patterns in which a single mother cell can sometimes give rise to up to thousands of daughter cells. Although such cell cycle patterns can be very complex, they are governed by the same general concepts as the most common binary fission. Moreover, cell cycle progression appears to be connected with size, since cells need to ensure that their size after division will not drop below the limit required for survival. Although the exact mechanism that lets cells measure cell size remains largely unknown, there have been several prominent hypotheses that try to explain it.


Assuntos
Ciclo Celular , Divisão Celular , Clorófitas/citologia , Tamanho Celular , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo
5.
Folia Microbiol (Praha) ; 64(5): 673-681, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31352668

RESUMO

The rare stable isotope of hydrogen, deuterium, has fascinated researchers since its discovery in the 1930s. Subsequent large-scale production of deuterium oxide, commonly known as heavy water, became a starting point for further research. Deuterium exhibits unique physicochemical properties as well as having the strongest kinetic isotope effects among all other elements. Moreover, a broad variety of morphological and physiological changes have been observed in deuterium-treated cells and organisms, including changes in fundamental processes such as cell division or energy metabolism. Even though our understanding of such alterations is still insufficient, it is evident that some of them make growth in a deuterium-enriched environment a challenging task. There seems to be certain species-specific limits to their tolerance to heavy water, where some organisms are unable to grow in heavy water whilst others have no difficulties. Although the effects of deuterium on living organisms are, in general, negative, some of its applications are of great biotechnological potential, as is the case of stable isotope-labelled compounds or deuterated drugs.


Assuntos
Deutério/metabolismo , Animais , Deutério/química , Humanos , Cinética , Água/química , Água/metabolismo
6.
Phytochemistry ; 164: 243-251, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31128818

RESUMO

Lipid-like compounds containing a dimethylarsinoyl group, i.e. Me2As(O)-, have been identified by liquid chromatography/inductively coupled plasma mass spectrometry (LC/ICP-MS) and non-aqueous reversed-phase high-performance liquid chromatography (positive and/or negative high-resolution tandem electrospray ionization mass spectrometry (NARP-HPLC/HR-ESI+(-)-MS/MS) from three strains of green algae of the genus Coccomyxa (Trebouxiophyceae, Chlorophyta). The algae were cultivated in a medium containing 10 g arsenic/L, i.e. 133.5 mmol/L of Na2HAsO4.7H2O. After extraction by methyl-tert-butyl ether (MTBE), total lipids were analyzed by ICP-MS or ESI-MS without any further separation or fractionation. A total of 39 molecular species of arsenic triacylglycerols (AsTAG), 15 arsenic phosphatidylcholines (AsPC), 8 arsenic phosphatidylethanolamines (AsPE), 6 arsenic phosphatidylinositols (AsPI), 2 arsenic phosphatidylglycerols (AsPG) and 5 unknown lipids (probably ceramides) were identified. The structures of all molecular species were confirmed by tandem MS. Dry matter of the individual strains contained different amounts of total arsenolipids, i.e. C. elongata CCALA 427 (0.32 mg/g), C. onubensis (1.48 mg/g), C. elongata S3 (2.13 mg/g). On the other hand, there were only slight differences between strains in the relative abundances of individual molecular species. Possible biosynthesis of long-chain lipids with the end group Me2As(O) has also been suggested.


Assuntos
Arsenicais/isolamento & purificação , Chlorella/química , Lipídeos/isolamento & purificação , Arsenicais/química , Arsenicais/metabolismo , Chlorella/metabolismo , Lipídeos/química , Estrutura Molecular
7.
Molecules ; 24(7)2019 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-30959876

RESUMO

Red mud is a by-product of alumina production containing lanthanides. Growth of green microalgae on red mud and the intracellular accumulation of lanthanides was tested. The best growing species was Desmodesmus quadricauda (2.71 cell number doublings/day), which accumulated lanthanides to the highest level (27.3 mg/kg/day), if compared with Chlamydomonas reinhardtii and Parachlorella kessleri (2.50, 2.37 cell number doublings and 24.5, 12.5 mg/kg per day, respectively). With increasing concentrations of red mud, the growth rate decreased (2.71, 2.62, 2.43 cell number doublings/day) due to increased shadowing of cells by undissolved red mud particles. The accumulated lanthanide content, however, increased in the most efficient alga Desmodesmus quadricauda within 2 days from zero in red-mud free culture to 12.4, 39.0, 54.5 mg/kg of dry mass at red mud concentrations of 0.03, 0.05 and 0.1%, respectively. Red mud alleviated the metal starvation caused by cultivation in incomplete nutrient medium without added microelements. Moreover, the proportion of lanthanides in algae grown in red mud were about 250, 138, 117% higher than in culture grown in complete nutrient medium at red mud concentrations of 0.03, 0.05, 0.1%. Thus, green algae are prospective vehicles for bio-mining or bio-leaching of lanthanides from red mud.


Assuntos
Elementos da Série dos Lantanídeos , Microalgas , Microbiologia do Solo , Reatores Biológicos , Chlamydomonas reinhardtii , Elementos da Série dos Lantanídeos/química , Técnicas Microbiológicas
8.
J Exp Bot ; 70(3): 845-858, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-30395238

RESUMO

The progression of the cell cycle in green algae dividing by multiple fission is, under otherwise unlimited conditions, affected by the growth rate, set by a combination of light intensity and temperature. In this study, we compared the cell cycle characteristics of Desmodesmus quadricauda at 20 °C or 30 °C and upon shifts between these two temperatures. The duration of the cell cycle in cells grown under continuous illumination at 20 °C was more than double that at 30 °C, suggesting that it was set directly by the growth rate. Similarly, the amounts of DNA, RNA, and bulk protein content per cell at 20 °C were approximately double those of cells grown at the higher temperature. For the shift experiments, cells grown at either 20 °C or 30 °C were transferred to darkness to prevent further growth, and then cultivated at the same or the other temperature. Upon transfer to the lower temperature, fewer nuclei and daughter cells were produced, and not all cells were able to finish the cell cycle by division, remaining multinuclear. Correspondingly, cells placed in the dark at the higher temperature divided faster into more daughter cells than the control cells. These differences correlated with shifts in the preceding cyclin-dependent kinase activity, suggesting that cell cycle progression was not related to growth rate or cell biomass but correlated with cyclin-dependent kinase activity.


Assuntos
Proteínas de Algas/genética , Ciclo Celular , Clorófitas/fisiologia , Quinases Ciclina-Dependentes/genética , Proteínas de Algas/metabolismo , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Temperatura Baixa , Quinases Ciclina-Dependentes/metabolismo , Escuridão , Temperatura Alta
9.
Lipids ; 53(4): 413-427, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29709080

RESUMO

Freshwater bryozoan Pectinatella magnifica was collected from a sand pit (South Bohemia). The total lipids after extraction from lyophilized bryozoans were analyzed using high-performance liquid chromatography/high-resolution negative tandem electrospray mass spectrometry. A total of 19 lipid classes were identified, including N-acyl-substituted phospholipids, that is, N-acylphosphatidylethanolamine and N-acylphosphatidylserine in their plasmenyl forms. Based on gas chromatography/mass spectrometry of 3-pyridylcarbonyl (picolinyl) esters, a very unusual fatty acid was identified, namely 24:7n-3 (all-cis-3,6,9,12,15,18,21-tetracosaheptaenoic acid). The presence of polyunsaturated fatty acids in individual classes is very specific: arachidonic and eicosapentaenoic acids being predominantly bound as amides in N-acyl phospholipids, that is, diacyl-N-acylphosphatidylethanolamines (NAPtdEtn), plasmenyl-N-acylphosphatidyl ethanolamines (PlsNAPtdEtn), diacyl-N-acylphosphatidylserines (NAPtdSer), and plasmenyl-N-acylphosphatidylserines (PlsNAPtdSer). While 24:6n-3 was identified in the sn-2 position of several phospholipids, 24:7n-3 was identified in only two plasmalogens, that is, PlsNAPtdEtn and PlsNAPtdSer. Thanks to the tandem mass spectrometry, we managed to identify the position of all acyl groups in both diacyl- and also in alkenyl-acyl-(plasmenyl) molecular species of N-acylphospholipids. The identification of the molecular species of N-acyl-substituted phosphatidylethanolamine and phosphatidylserine, including their plasmalogen forms, in the freshwater bryozoan P. magnifica has enabled the identification of endogenous cannabinoid precursors.


Assuntos
Briozoários/química , Endocanabinoides/análise , Endocanabinoides/química , Animais , Cromatografia Líquida de Alta Pressão , Água Doce , Espectrometria de Massas em Tandem
10.
Phytochemistry ; 148: 29-38, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29366853

RESUMO

Very long chain fatty acids (VLCFAs) were identified in four strains of the green alga Botryococcus braunii (Trebouxiophyceae). The algae contained a series of monoenoic fatty acids up to triacontenoic acid and further VLCFAs in amounts around 1% of total fatty acids. The separation of lipid classes using hydrophilic interaction chromatography revealed that the most abundant VLCFAs (28:2, 28:1 and 28:0) were contained in neutral lipids (triacylglycerols and/or diacylglycerols) and in phospholipids (phosphatidic acid and/or phosphatidylcholine). Using non-aqueous reversed-phase liquid chromatography tandem mass spectrometry (NARP-LC/MS2) of the appropriate collected fractions, molecular species of triacylglycerols containing one or two VLCFAs were described and phosphatidylcholines containing VLCFAs were separated for the first time. Because the presence of Botryosphaerella sudetica (Chlorophyceae) as contaminant of Botryococcus braunii strain Droop 1950/807-1 placed some doubts on the results of previous studies, a strain of this green alga of was also analyzed. In contrast to Botryococcus, C16, a substantially lower proportion of C18 polyunsaturated fatty acids and no VLCFAs were detected in Botryosphaerella.


Assuntos
Clorófitas/química , Ácidos Graxos/análise , Fosfolipídeos/análise , Cromatografia Líquida , Ácidos Graxos Insaturados/química
11.
Biotechnol Adv ; 36(3): 784-797, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29355599

RESUMO

Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies.


Assuntos
Biotecnologia/métodos , Desenho de Drogas , Marcação por Isótopo/métodos , Isótopos/análise , Isótopos/química , Animais , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Deutério/administração & dosagem , Deutério/efeitos adversos , Deutério/análise , Espectroscopia de Ressonância Magnética , Mamíferos , Espectrometria de Massas/métodos , Plantas/efeitos dos fármacos , Análise Espectral Raman/métodos
12.
Photosynth Res ; 130(1-3): 335-346, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27113221

RESUMO

Lanthanides (La, Gd, Nd, Ce) accumulated in the green alga Desmodesmus quadricauda but their intracellular localizations were distinctly different: lanthanum and gadolinium were localized in cytoplasm, while neodymium and cerium were in the chloroplast. The effect of lanthanum and neodymium, as representatives of these two groups, on growth, chlorophyll content and photosynthetic rate at different light intensities was studied. At the lowest light intensity used (50 µmol photons m-2 s-1), in the presence of lanthanides (Nd), growth was enhanced by as much as 36 % over lanthanide free control, and the photosynthetic rate increased by up to 300 %. At high light intensities (238, 460, and 750 µmol photons m-2 s-1), photosynthetic rate increased markedly, but there was no significant difference between rates in the presence or absence of lanthanides. However, growth, measured as a percentage of dry weight, if compared with lanthanide free control, increased at all light intensities (31, 39, and 20 %, respectively). The total amount of chlorophyll after lanthanide treatment increased by up to 21 % relative to the control culture, mainly due to an increase in the level of chlorophyll b. Addition of lanthanides caused a change in the chlorophyll a/b ratio from 4.583 in control cultivation, to 1.05. Possible mechanisms of lanthanide-induced photosynthetic change, alterations in photosynthetic structures, and increases in growth are discussed and compared with findings in higher plants. The hypothesis that the lanthanide effect could be due to formation of lanthanide-pheophytins was not confirmed as lanthanide pheophytins were not found in D. quadricauda. Furthermore, we have shown that the preferential incorporation of heavy isotopes of magnesium, namely 25Mg and 26Mg, into chlorophyll during photosynthesis that occurred in controls was diminished in the presence of lanthanides.


Assuntos
Clorofila/análise , Clorófitas/efeitos dos fármacos , Elementos da Série dos Lantanídeos/farmacologia , Fotossíntese/efeitos dos fármacos , Clorofila/isolamento & purificação , Clorofila/fisiologia , Clorófitas/química , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo
13.
Methods Mol Biol ; 1370: 3-16, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26659950

RESUMO

A synchronous population of cells is one of the prerequisites for studying cell cycle processes such as DNA replication, nuclear and cellular division. Green algae dividing by multiple fission represent a unique single cell system enabling the preparation of highly synchronous cultures by application of a light-dark regime similar to what they experience in nature. This chapter provides detailed protocols for synchronization of different algal species by alternating light-dark cycles; all critical points are discussed extensively. Moreover, detailed information on basic analysis of cell cycle progression in such cultures is presented, including analyses of nuclear, cellular, and chloroplast divisions. Modifications of basic protocols that enable changes in cell cycle progression are also suggested so that nuclear or chloroplast divisions can be followed separately.


Assuntos
Chlamydomonas reinhardtii/citologia , Clorófitas/citologia , Fotoperíodo , Técnicas de Cultura de Células/métodos , Ciclo Celular , Divisão Celular , Fracionamento Celular/métodos , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Clorófitas/genética , Clorófitas/crescimento & desenvolvimento , Cloroplastos/genética , Replicação do DNA , DNA de Plantas/genética , Luz , Coloração e Rotulagem/métodos
14.
Folia Microbiol (Praha) ; 61(4): 329-35, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26683688

RESUMO

Oxidative stress induced by zero-valent iron nanoparticles (nZVIs) was used to improve lipid accumulation in various oleaginous and non-oleginous yeasts-Candida sp., Kluyveromyces polysporus, Rhodotorula glutinis, Saccharomyces cerevisiae, Torulospora delbrueckii, Trichosporon cutaneum, and Yarrowia lipolytica. The highest lipid yields occurred at 9-13 mg/L nZVIs. Gas chromatography-mass spectrometry was used for the quantitative and qualitative analysis of the fatty acids. It showed an increasing abundance of polyunsaturated fatty acids, especially essential linoleic acid, in the presence of nZVIs. Our results suggest that nZVIs can be used to improve not only lipid production by oleaginous microorganisms but also the nutritional value of biosynthesized unsaturated fatty acids.


Assuntos
Ferro/metabolismo , Metabolismo dos Lipídeos , Nanopartículas/metabolismo , Estresse Oxidativo , Leveduras/efeitos dos fármacos , Citosol/química , Ácidos Graxos/análise , Cromatografia Gasosa-Espectrometria de Massas , Leveduras/metabolismo
15.
Lipids ; 50(8): 811-20, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26123693

RESUMO

Liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS/APCI) with reversed- and chiral phases was used for separation of triacylglycerols (TAG) from protozoan and mold. This study describes the separation and identification of odd numbered chains of regioisomers and enantiomers of triacylglycerols from different natural sources, i.e., the protozoan Khawkinea quartana and the mold Mortierella alpina. Using the above-mentioned separation methods and the synthesis of appropriate standards of TAG, we identified regioisomers and enantiomers of both even and odd numbered TAG. The biosynthesis of odd numbered TAG was found to be strictly stereospecific and to depend on the production microorganism, one enantiomer predominating in the protozoan and the other in the mold. It was proved that even numbered TAG are synthesized in a higher optical purity, which can be explained by a higher affinity of acyltransferases to the respective substrate, i.e., to even chain PUFA.


Assuntos
Euglena/química , Mortierella/química , Triglicerídeos/isolamento & purificação , Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Triglicerídeos/química
16.
Biotechnol Adv ; 33(6 Pt 2): 1204-18, 2015 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25986035

RESUMO

Starch and lipids are key components of algal cells and responsible for buffering variable supplies of energy and carbon that are vital for cell growth and reproduction, particularly DNA replication, nuclear and cellular division. The basic characteristics of energy reserves, their ultrastructure and localization inside the cell, regulation of their synthesis in relation to cell cycle phases, and their control by external factors, including light intensity, temperature, and carbon dioxide are described. Over the last two decades, research in this field has been boosted by possible biotechnological applications of algae for the production of biofuels from energy conserving compounds (bioethanol from starch and biodiesel from lipids). Recent findings on mechanisms that lead to an accumulation of exceptionally high levels of starch and lipids in algae will be summarized in this review. Macroelement (N, S, P) limitation, or depletion in mineral medium, as the most widely used approaches for enhancing both starch and lipid accumulation, are reviewed in detail. Potential biotechnological strategies for the economically viable overproduction of lipid and starch, such as a two-step procedure exploiting the effects of nutrient limitation and depletion, as well as the means and rationale for selecting appropriate strains, are discussed.


Assuntos
Biotecnologia/métodos , Ciclo Celular , Metabolismo Energético , Eucariotos/metabolismo , Especificidade da Espécie
17.
Front Microbiol ; 6: 2, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25674079

RESUMO

Lanthanides are biologically non-essential elements with wide applications in technology and industry. Their concentration as environmental contaminants is, therefore, increasing. Although non-essential, lanthanides have been proposed (and even used) to produce beneficial effects in plants, even though their mechanisms of action are unclear. Recently, it was suggested that they may replace essential elements. We tested the effect of low concentrations of lanthanides on the common freshwater microalga Desmodesmus quadricauda, grown under conditions of metal ion-deficiency (lower calcium or manganese concentrations). Our goal was to test if lanthanides can replace essential metals in their functions. Physiological stress was recorded by studying growth and photosynthetic activity using a pulse amplitude modulation (PAM) fluorimeter. We found that nutrient stress reduced parameters of growth and photosynthesis, such as maximal quantum yield, relative electron transport rate, photon capturing efficiency and light saturation irradiance. After adding low concentrations of five lanthanides, we confirmed that they can produce a stimulatory effect on microalgae, depending on the nutrient (metal) deprivation. In the case of a calcium deficit, the addition of lanthanides partly alleviated the adverse effects, probably by a partial substitution of the element. In contrast, with manganese deprivation (and at even lower concentrations), lanthanides enhanced the deleterious effect on cellular growth and photosynthetic competence. These results show that lanthanides can replace essential elements, but their effects on microalgae depend on stress and the nutritional state of the microalgae, raising the possibility of environmental impacts at even low concentrations.

18.
Phytochemistry ; 110: 37-45, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25564261

RESUMO

This study describes the identification of regioisomers and enantiomers of triacylglycerols of C20 polyunsaturated fatty acids (PUFAs) in the alga Trachydiscus minutus cultivated at different temperatures using reversed- and chiral-phase liquid chromatography-mass spectrometry. The use of the two different phases contributes to ready identification, both qualitative and semiquantitative, of regioisomers and enantiomers of triacylglycerols containing eicosapentaenoic and arachidonic in the molecule. The ratio of regioisomers and enantiomers of triacylglycerols (TAG) depends on the temperature of cultivation; with lowering temperature the proportion of the achiral TAG increases and the enantiomer ratio diverges from 1:1.


Assuntos
Ácidos Graxos Insaturados/análise , Estramenópilas/química , Triglicerídeos/isolamento & purificação , Estereoisomerismo , Temperatura Ambiente , Triglicerídeos/química , Triglicerídeos/metabolismo
19.
Bioresour Technol ; 144: 268-74, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23876655

RESUMO

Photosynthetic carbon partitioning into starch and neutral lipids, as well as the influence of nutrient depletion and replenishment on growth, pigments and storage compounds, were studied in the microalga, Parachlorella kessleri. Starch was utilized as a primary carbon and energy storage compound, but nutrient depletion drove the microalgae to channel fixed carbon into lipids as secondary storage compounds. Nutrient depletion inhibited both cellular division and growth and caused degradation of chlorophyll. Starch content decreased from an initial value of 25, to around 10% of dry weight (DW), while storage lipids increased from almost 0 to about 29% of DW. After transfer of cells into replenished mineral medium, growth, reproductive processes and chlorophyll content recovered within 2 days, while the content of both starch and lipids decreased markedly to 3 or less % of DW; this suggested that they were being used as a source of energy and carbon.


Assuntos
Clorófitas/metabolismo , Metabolismo dos Lipídeos , Microalgas/metabolismo , Nitrogênio/deficiência , Fósforo/deficiência , Amido/metabolismo , Biomassa , Contagem de Células , Clorofila/metabolismo , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Meios de Cultura/química , Microalgas/citologia , Microalgas/crescimento & desenvolvimento , Fotobiorreatores/microbiologia
20.
Biotechnol Bioeng ; 110(1): 97-107, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22766749

RESUMO

The alga Parachlorella kessleri, strain CCALA 255, grown under optimal conditions, is characterized by storage of energy in the form of starch rather than lipids. If grown in the complete medium, the cultures grew rapidly, producing large amounts of biomass in a relatively short time. The cells, however, contained negligible lipid reserves (1-10% of DW). Treatments inducing hyperproduction of storage lipids in P. kessleri biomass were described. The cultures were grown in the absence or fivefold decreased concentration of either nitrogen or phosphorus or sulfur. Limitation by all elements using fivefold or 10-fold diluted mineral medium was also tested. Limitation with any macroelement (nitrogen, sulfur, or phosphorus) led to an increase in the amount of lipids; nitrogen limitation was the most effective. Diluted nutrient media (5- or 10-fold) were identified as the best method to stimulate lipid overproduction (60% of DW). The strategy for lipid overproduction consists of the fast growth of P. kessleri culture grown in the complete medium to produce sufficient biomass (DW more than 10 g/L) followed by the dilution of nutrient medium to stop growth and cell division by limitation of all elements, leading to induction of lipid production and accumulation up to 60% DW. Cultivation conditions necessary for maximizing lipid content in P. kessleri biomass generated in a scale-up solar open thin-layer photobioreactor were described.


Assuntos
Clorófitas/metabolismo , Lipídeos/biossíntese , Microalgas/metabolismo , Biomassa , Biotecnologia , Dióxido de Carbono/metabolismo , Clorofila/análise , Clorofila/metabolismo , Meios de Cultura , Ácidos Graxos/análise , Ácidos Graxos/metabolismo , Metabolismo dos Lipídeos , Fotobiorreatores , Amido/análise , Amido/metabolismo
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