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1.
World J Microbiol Biotechnol ; 35(7): 110, 2019 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-31280381

RESUMO

Carbon sources whether types or magnitudes were fateful in terms of stimulating growth and lipids accumulation in microalgae applied for biodiesel production. The set scenario of this work was to investigate the feasibilities of glucose (G) combining with sodium acetate (SA) carbon sources in enhancing biomass and lipid accumulation in Coccomyxa subellipsoidea. The results demonstrated that C. subellipsoidea subjected to the combination feeding of G (20 g/L) and SA (12 g/L) achieved the favorable biomass (5.22 g/L) and lipid content (52.16%). The resulting lipid productivity (388.96 mg/L/day) was 1.33- to 7.60-fold more than those of sole G or SA as well as other combinations of G and SA. Even though the total fatty acids of C. subellipsoidea cells treated with the optimal combination of G and SA showed no noticeable increment in comparison with sole G or SA, the proportion of monounsaturated C18:1 (over 48.69%) and the content of C18:3 (< 12%) were commendable in high-quality algal biodiesel production. Further, such fascinating lipid accumulation in C. subellipsoidea cells treated with G combining with SA might be attributed to that G promoted glycolysis as well as SA activated glyoxylate shunt and TCA cycle to synergistically provide sufficient acetyl-CoA precursors for lipid accumulation. These findings hinted the potential of the combination of carbon sources in enhancing the overall lipid productivity to offset alga-based biodiesel production cost and would guide other alga strains cultivation.


Assuntos
Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Glucose/metabolismo , Lipídeos/biossíntese , Acetato de Sódio/metabolismo , Biocombustíveis , Biomassa , Carbono/metabolismo , Clorófitas/citologia , Meios de Cultura/química , Ácidos Graxos/biossíntese , Metabolômica , Microalgas/crescimento & desenvolvimento , Microalgas/metabolismo , Nitrogênio/metabolismo
2.
BMC Evol Biol ; 19(1): 120, 2019 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-31185890

RESUMO

BACKGROUND: Volvocine algae provide a suitable model for investigation of the evolution of multicellular organisms. Within this group, evolution of the body plan from flattened to spheroidal colonies is thought to have occurred independently in two different lineages, Volvocaceae and Astrephomene. Volvocacean species undergo inversion to form a spheroidal cell layer following successive cell divisions during embryogenesis. During inversion, the daughter protoplasts change their shape and develop acute chloroplast ends (opposite to basal bodies). By contrast, Astrephomene does not undergo inversion; rather, its daughter protoplasts rotate during successive cell divisions to form a spheroidal colony. However, the evolutionary pathways of these cellular events involved in the two tactics for formation of spheroidal colony are unclear, since the embryogenesis of extant volvocine genera with ancestral flattened colonies, such as Gonium and Tetrabaena, has not previously been investigated in detail. RESULTS: We conducted time-lapse imaging by light microscopy and indirect immunofluorescence microscopy with staining of basal bodies, nuclei, and microtubules to observe embryogenesis in G. pectorale and T. socialis, which form 16-celled or 4-celled flattened colonies, respectively. In G. pectorale, a cup-shaped cell layer of the 16-celled embryo underwent gradual expansion after successive cell divisions, with the apical ends (position of basal bodies) of the square embryo's peripheral protoplasts separated from each other. In T. socialis, on the other hand, there was no apparent expansion of the daughter protoplasts in 4-celled embryos after successive cell divisions, however the two pairs of diagonally opposed daughter protoplasts shifted slightly and flattened after hatching. Neither of these two species exhibited rotation of daughter protoplasts during successive cell divisions as in Astrephomene or the formation of acute chloroplast ends of daughter protoplasts as in volvocacean inversion. CONCLUSIONS: The present results indicate that the ancestor of Astrephomene might have newly acquired the rotation of daughter protoplasts after it diverged from the ancestor of Gonium, while the ancestor of Volvocaceae might have newly acquired the formation of acute chloroplast ends to complete inversion after divergence from the ancestor of Goniaceae (Gonium and Astrephomene).


Assuntos
Evolução Biológica , Clorófitas/embriologia , Corpos Basais/metabolismo , Divisão Celular , Núcleo Celular/metabolismo , Clorófitas/classificação , Clorófitas/citologia , Microtúbulos/metabolismo , Filogenia , Imagem com Lapso de Tempo
3.
Ecotoxicol Environ Saf ; 174: 584-591, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30870659

RESUMO

Single and multispecies algal bioassays were assessed using copper toxicity with three green algae (Scenedesmus subspicatus, Scenedesmus quadricauda and Ankistrodesmus angustus) and one blue-green algae species (Oscillatoria prolifera). Single and multispecies toxicity tests were conducted based on cell density as per standard toxicity testing, and on equivalent surface area. A higher copper sulfate toxicity was registered for O. prolifera, followed by S. subspicatus, S. quadricauda, and A. angustus in single-species toxicity tests based on cell density. Single species toxicity tests based on surface area showed increased copper toxicity with increasing algal surface area except for A. angustus. In multispecies control bioassays, the growth of A. angustus was inhibited in the presence of other species in surface area-based tests. As compared to single species bioassays, O. prolifera, and S. quadricauda showed a decreased sensitivity to copper sulfate in both cell density and surface area based multispecies tests. However, for the algae species with the smallest surface area, S. subspicatus, 96h-EC50 value decreased in multispecies bioassays based on surface area as compared to the single species test, while it increased in multispecies bioassays based on cell density. The difference in S. subspicatus sensitivity to copper between tests based on cell density and surface area supports the need to adopt multispecies toxicity testing based on surface area to avoid the confounding effect on copper toxicity of increased biomass for metal binding. 96h-EC50 values for all species combined in the multispecies test based on cell density and on surface area were significantly different from 96h-EC50 values obtained in single species bioassays. These results demonstrate that single-species bioassays may over- or underestimate metal toxicity in natural waters.


Assuntos
Clorófitas/efeitos dos fármacos , Sulfato de Cobre/toxicidade , Herbicidas/toxicidade , Bioensaio , Contagem de Células , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Cianobactérias/citologia , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Scenedesmus/citologia , Scenedesmus/efeitos dos fármacos , Scenedesmus/crescimento & desenvolvimento , Testes de Toxicidade
4.
Mar Drugs ; 17(1)2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30634492

RESUMO

Haematococcus pluvialis, as the best natural resource of astaxanthin, is widely used in nutraceuticals, aquaculture, and cosmetic industries. The purpose of this work was to compare the differences in astaxanthin accumulation between motile and nonmotile cells of H. pluvialis and to determine the relationship between the two cells and astaxanthin production. The experiment design was achieved by two different types of H. pluvialis cell and three different light intensities for an eight day induction period. The astaxanthin concentrations in nonmotile cell cultures were significantly increased compared to motile cell cultures. The increase of astaxanthin was closely associated with the enlargement of cell size, and the nonmotile cells were more conducive to the formation of large astaxanthin-rich cysts than motile cells. The cyst enlargement and astaxanthin accumulation of H. pluvialis were both affected by light intensity, and a general trend was that the higher the light intensity, the larger the cysts formed, and the larger the quantity of astaxanthin accumulated. In addition, the relatively low cell mortality rate in the nonmotile cell cultures indicated that the nonmotile cells have a stronger tolerance to photooxidative stress. We suggest that applying nonmotile cells as the major cell type of H. pluvialis to the induction period may help to enhance the content of astaxanthin and the stability of astaxanthin production.


Assuntos
Clorófitas/metabolismo , Fibrinolíticos/metabolismo , Sobrevivência Celular/efeitos da radiação , Clorófitas/citologia , Clorófitas/efeitos da radiação , Luz , Xantofilas/metabolismo
5.
Microsc Res Tech ; 82(5): 580-585, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30614133

RESUMO

INTRODUCTION: For sample collection, four sites were selected, sites where fresh water were present, that is, Ravi syphon, BRB Lahore, Shahdara, and Head Baloki. The latitude and altitude of the locations were recorded at the time of collection. RESULTS: A total of 21 species of algae belonging to eight genera and four families were examined in the current studies. The collected samples were mainly filamentous and they were primarily green in color as the photosynthetic pigment found to be dominated was Chlorophyll. It was observed that all the genera varied mainly on the basis of cell shape, size, number of pyramids and on the arrangement of cells. The site mainly selected was those where fresh water was mainly found and at the time of collection latitude and altitude was also recorded. CONCLUSIONS: The classical microscopic technique (Light Microscopy) and Modern microscopic technique (Staining Electron Microscopy) of some samples were done that, played a lively part in the correct identification of species as a slight difference was found among species that were only evident when the Modern microscopic technique was done.


Assuntos
Clorófitas/anatomia & histologia , Clorófitas/citologia , Microscopia/métodos , Clorófitas/química , Clorófitas/classificação , Pigmentos Biológicos/análise , Microbiologia da Água
6.
Electrophoresis ; 40(6): 969-978, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30221789

RESUMO

The composition of the ship's ballast water is complex and contains a large number of microalgae cells, bacteria, microplastics, and other microparticles. To increase the accuracy and efficiency of detection of the microalgae cells in ballast water, a new microfluidic chip for continuous separation of microalgae cells based on alternating current dielectrophoresis was proposed. In this microfluidic chip, one piece of 3-dimensional electrode is embedded on one side and eight discrete electrodes are arranged on the other side of the microchannel. An insulated triangular structure between electrodes is designed for increasing the inhomogeneity of the electric field distribution and enhancing the dielectrophoresis (DEP) force. A sheath flow is designed to focus the microparticles near the electrode, so as to increase the suffered DEP force and improve separation efficiency. To demonstrate the performance of the microfluidic separation chip, we developed two species of microalgae cells (Platymonas and Closterium) and a kind of microplastics to be used as test samples. Analyses of the related parameters and separation experiments by our designed microfluidic chip were then conducted. The results show that the presented method can separate the microalgae cells from the mixture efficiently, and this is the first time to separate two or more species of microalgae cells in a microfluidic chip by using negative and positive DEP force simultaneously, and moreover it has some advantages including simple operation, high efficiency, low cost, and small size and has great potential in on-site pretreatment of ballast water.


Assuntos
Eletroforese , Dispositivos Lab-On-A-Chip , Microalgas , Navios , Microbiologia da Água , Clorófitas/citologia , Closterium/citologia , Eletroforese/instrumentação , Eletroforese/métodos , Desenho de Equipamento , Microalgas/citologia , Microalgas/isolamento & purificação , Poliestirenos
7.
Environ Sci Pollut Res Int ; 26(3): 2873-2881, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30499085

RESUMO

Silver nanoparticles (AgNPs) were synthesized by incubating the mixture of AgNO3 solution and whole-cell aqueous extracts (WCAEs) of Neochloris oleoabundans under light conditions. By conducting single-factor and multi-factor optimization, the effects of parameters including AgNO3 concentration, pH, and extraction time were quantitatively evaluated. The optimal conditions in terms of AgNP yield were found to be 0.8 mM AgNO3, pH 5, and 9-h extraction. The AgNPs thus synthesized were quasi-spherical with a mean particle diameter of 16.63 nm and exhibited decent uniformity as well as antibacterial activities, which may facilitate AgNP biosynthesis's application in the near future.


Assuntos
Antibacterianos/isolamento & purificação , Extratos Celulares , Clorófitas/metabolismo , Luz , Nanopartículas Metálicas/química , Prata/metabolismo , Extratos Celulares/química , Extratos Celulares/efeitos da radiação , Clorófitas/citologia , Clorófitas/efeitos da radiação , Tamanho da Partícula , Prata/química , Prata/isolamento & purificação , Propriedades de Superfície
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.
Biochim Biophys Acta Bioenerg ; 1860(1): 78-88, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30414930

RESUMO

Photosynthetic pigment-protein complexes are highly concentrated in thylakoid membranes of chloroplasts and cyanobacteria that emit strong autofluorescence (mainly 600-800 nm). In Raman scattering microscopy that enables imaging of pigment concentrations of thylakoid membranes, near infrared laser excitation at 1064 nm or visible laser excitation at 488-532 nm has been often employed in order to avoid the autofluorescence. Here we explored a new approach to Raman imaging of thylakoid membranes by using excitation wavelength of 976 nm. Two types of differentiated cells, heterocysts and vegetative cells, in two diazotrophic filamentous cyanobacteria, Anabaena variabilis, and Rivularia M-261, were characterized. Relative Raman scattering intensities of phycobilisomes of the heterocyst in comparison with the nearest vegetative cells of Rivularia remained at a significantly higher level than those of A. variabilis. It was also found that the 976 nm excitation induces photoluminescence around 1017-1175 nm from the two cyanobacteria, green alga (Parachlorella kessleri) and plant (Arabidopsis thaliana). We propose that this photoluminescence can be used as an index of concentration of chlorophyll a that has relatively small Raman scattering cross-sections. The Rivularia heterocysts that we analyzed were clearly classified into at least two subgroups based on the Chla-associated photoluminescence and carotenoid Raman bands, indicating two physiologically distinct states in the development or aging of the terminal heterocyst.


Assuntos
Técnicas Citológicas/métodos , Medições Luminescentes , Análise Espectral Raman , Arabidopsis/citologia , Senescência Celular , Clorofila A/análise , Clorófitas/citologia , Cianobactérias/citologia , Técnicas Citológicas/instrumentação , Ficobilissomas/análise , Tilacoides
10.
Extremophiles ; 23(1): 79-89, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30341564

RESUMO

The extremophile green alga Coccomyxa melkonianii SCCA 048 was investigated to evaluate its ability to grow in culture media with different pH. Specifically, Coccomyxa melkonianii was sampled in the Rio Irvi river (Sardinia, Italy) which is severely polluted by heavy metals as a result of abandoned mining activities. In this study, the strain was cultivated in growth media where the pH was kept fixed at the values of 4.0, 6.8 and 8.0, respectively. During the investigation, a significant phenotypic plasticity of this strain was observed. The strain grew well in the pH range 4.0-8.0, while the optimal value for its growth was 6.8. Furthermore, maximum lipid contents of about 24 and 22 %wt were achieved at the end of cultivation when using pH 4.0 and 8.0, respectively. Finally, the analysis of fatty acid methyl esters (FAMEs) highlights the presence of suitable amounts of compounds which can be profitably exploited in the food, nutraceutical, and cosmetic industry. This aspect, coupled with the possibility of cultivating Coccomyxa melkonianii under extreme pH conditions in economic open ponds, makes this strain an interesting candidate for several biotechnological applications.


Assuntos
Clorófitas/metabolismo , Ácidos Graxos/biossíntese , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Termotolerância
11.
J Biosci Bioeng ; 127(2): 213-221, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30391236

RESUMO

Synergistic coexistence of nitrogen fixing cyanobacteria such as Anabaena variabilis, Nostoc muscorum and Westiellopsis prolifica with green algae namely Scenedesmus obliquus, Chlorella vulgaris and Botryococcus braunii was studied under nitrogen deficient conditions. The effect of these interactions was investigated on growth, fixed nitrogen content, lipid content and their secretomes in individual cultures and cocultures. Based on the cocultivation studies, it was found that out of the nine interactions studied, B. braunii-N. muscorum synergism was best established. This interaction resulted in a maximum of 50% enhancement in nitrogen fixation in B. braunii-N. muscorum co-culture leading to 27% enhancement in lipid content (membrane and neutral lipid). In general, B. braunii co-cultures showed an enhancement in biomass content of up to 38%. Secretome analysis showed presence of new and modified secondary metabolites having roles in quorum sensing/quenching, interspecies signaling, N-fixation, carbon metabolism, lipid metabolism, antimicrobial activity. Compounds such as trichloroacetic acid and hexadecane were identified that are known to have roles in nitrogen assimilation and carbon metabolism, respectively, were present in some of the co-culture secretomes. The combination of B. braunii-N. muscorum led to the formation of new compounds such as triacontanol which have role in improvement of glucose-lipid metabolism and 9-octadecenamide that is known to be a phytohormone.


Assuntos
Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Metaboloma , Interações Microbianas/fisiologia , Via Secretória , Biomassa , Metabolismo dos Carboidratos , Chlorella vulgaris/citologia , Chlorella vulgaris/crescimento & desenvolvimento , Chlorella vulgaris/metabolismo , Clorófitas/citologia , Técnicas de Cocultura/métodos , Cianobactérias/citologia , Metabolismo dos Lipídeos , Lipídeos/análise , Metabolômica/métodos , Técnicas Microbiológicas/métodos , Nitrogênio/metabolismo , Fixação de Nitrogênio
12.
Environ Monit Assess ; 191(1): 29, 2018 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-30591969

RESUMO

In this paper, the algal cell density of cyanobacteria, green algae, and diatoms and their responses to the hydrochemical factors were analyzed to reveal the structural characteristics of water quality in an urban river. A total of nine sampling sites from upstream to downstream was explored in our study. At each site, the density of algae was identified every week during the wet season (June-October) from 2012 to 2017, and in situ detection was used for the relative 11 hydrochemical variables. The temporal and spatial characteristics of 14 variables were analyzed using a heatmap coupled with the cluster analysis method. The trend of each parameter was analyzed using the smoothing method with locally weighted regression. The nonmetric multidimensional scaling method was employed to detect the temporal and spatial similarities among algae along hydrochemical gradients. The responses of algal density to hydrochemical variables were analyzed using a redundancy analysis. The results showed that the water temperature (Wtemp), pH, dissolved oxygen (DO), cyanobacteria, and diatoms exhibited significant declining trends, and significant increasing trends were shown in the permanganate index, chemical oxygen demand, total nitrogen, ammonia nitrogen, and total phosphorus; the cyanobacteria exhibited certain differences with green algae and diatoms in summer and the downstream areas of the river. The temporal-spatial homogeneity of algal to hydrochemical variables showed the key influencing factors of Wtemp for cyanobacteria density, chlorophyll for green algae density, DO, and pH for diatoms. The results presented here are valuable for deepening our understanding of river ecosystem evaluations and effective environmental management, as well as an important reference for the sustainable development of aquatic biological resources.


Assuntos
Clorófitas/citologia , Cianobactérias/citologia , Diatomáceas/citologia , Monitoramento Ambiental/métodos , Rios/química , Movimentos da Água , China , Clorofila/análise , Clorófitas/crescimento & desenvolvimento , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Ecossistema , Eutrofização , Nitrogênio/análise , Fósforo/análise , Estações do Ano , Urbanização , Qualidade da Água
13.
Plant Physiol Biochem ; 132: 535-546, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30316163

RESUMO

The effects of auxins (IAA, IBA, PAA) and cytokinins (tZ, Kin, DPU) on the growth, oxidative damage, level of antioxidants and the activity of antioxidant enzymes as well as the contents of proteins and photosynthetic pigments in green alga Acutodesmus obliquus were investigated under 100 µM lead (Pb) stress. Heavy metal induced oxidative damage as evidenced by a decrease in cell number and reduction in the contents of proteins and chlorophylls as a consequence of an increase in reactive oxygen species (ROS) formation and lipid peroxidation. The application of exogenous auxins and cytokinins modulated biosorption of Pb by algal cells significantly alleviated the growth inhibition and stimulated the accumulation of proteins, chlorophylls and carotenes. Phytohormones also activated the xanthophyll cycle which is extensively involved in the protection of the photosynthetic apparatus in adverse environmental conditions. The reduction in oxidative stress caused by the presence of toxic Pb was observed in algal cultures treated with phytohormones. Cytokinins were more effective in lowering hydrogen peroxide and lipid peroxidation levels in comparison with auxins. This improving effect of cytokinins seems to be mediated by a decrease in Pb accumulation by algal cells, whereas auxins promoted metal uptake. Importantly, auxins and cytokinins enhanced the redox status of algal cells inducing the increase in the content of antioxidants (ascorbate, glutathione, and proline) and in the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) involved in ROS scavenging. The results of the present study strongly suggest that exogenous auxins and cytokinins enhanced the resistance of microalga A. obliquus against Pb toxicity through the activation of the antioxidant defence system.


Assuntos
Antioxidantes/metabolismo , Clorófitas/metabolismo , Citocininas/farmacologia , Ácidos Indolacéticos/farmacologia , Chumbo/toxicidade , Adsorção , Proteínas de Algas/metabolismo , Carotenoides/metabolismo , Clorofila/metabolismo , Clorófitas/citologia , Clorófitas/efeitos dos fármacos , Clorófitas/crescimento & desenvolvimento , Estresse Oxidativo/efeitos dos fármacos , Solubilidade
14.
Aquat Toxicol ; 204: 80-90, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30205248

RESUMO

Over the last decade, concerns have been raised regarding the potential health and environmental effects associated with the release of metal oxide nanoparticles (NPs) into ecosystems. In the present work, the potential hazards of nickel oxide (NiO) NPs were investigated using the ecologically relevant freshwater alga Pseudokirchneriella subcapitata. NiO NP suspensions in algal OECD medium were characterized with regard to their physicochemical properties: agglomeration, surface charge, stability (dissolution of the NPs) and abiotic reactive oxygen species (ROS) production. NiO NPs formed loose agglomerates and released Ni2+. NiO NPs presented a 72 h-EC50 of 1.6 mg L-1, which was evaluated using the algal growth inhibition assay and allowed this NP to be classified as toxic. NiO NPs caused the loss of esterase activity (metabolic activity), the bleaching of photosynthetic pigments and the intracellular accumulation of reactive oxygen species (ROS) in the absence of the disruption of plasma membrane integrity. NiO NPs also disturbed the photosynthetic process. A reduction in the photosynthetic efficiency (ΦPSII) accompanied by a decrease in the flow rate of electrons through the photosynthetic chain was also observed. The leakage of electrons from the photosynthetic chain may be the origin of the ROS found in the algal cells. The exposure to NiO NPs led to the arrest of the cell cycle prior to the first cell division (primary mitosis), an increase in cell volume and the presence of aberrant morphology in the algal cells. In this work, the use of different approaches allowed new clues related to the toxicity mechanisms of NiO NPs to be obtained. This work also contributes to the characterization of the environmental and toxicological hazards of NiO NPs and provides information on the possible adverse effects of these NPs on aquatic systems.


Assuntos
Clorófitas/efeitos dos fármacos , Água Doce , Nanopartículas/toxicidade , Níquel/toxicidade , Testes de Toxicidade , Ciclo Celular/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Clorófitas/citologia , Clorófitas/crescimento & desenvolvimento , Clorófitas/metabolismo , Fotossíntese/efeitos dos fármacos , Pigmentos Biológicos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Suspensões , Poluentes Químicos da Água/toxicidade
15.
PLoS One ; 13(8): e0201446, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30089142

RESUMO

The emergence of functional specialization is a core problem in biology. In this work we focus on the emergence of reproductive (germ) and vegetative viability-enhancing (soma) cell functions (or germ-soma specialization). We consider a group of cells and assume that they contribute to two different evolutionary tasks, fecundity and viability. The potential of cells to contribute to fitness components is traded off. As embodied in current models, the curvature of the trade-off between fecundity and viability is concave in small-sized organisms and convex in large-sized multicellular organisms. We present a general mathematical model that explores how the division of labor in a cell colony depends on the trade-off curvatures, a resource constraint and different fecundity and viability rates. Moreover, we consider the case of different trade-off functions for different cells. We describe the set of all possible solutions of the formulated mathematical programming problem and show some interesting examples of optimal specialization strategies found for our objective fitness function. Our results suggest that the transition to specialized organisms can be achieved in several ways. The evolution of Volvocalean green algae is considered to illustrate the application of our model. The proposed model can be generalized to address a number of important biological issues, including the evolution of specialized enzymes and the emergence of complex organs.


Assuntos
Comunicação Celular/fisiologia , Diferenciação Celular/fisiologia , Clorófitas/fisiologia , Fertilidade/fisiologia , Modelos Biológicos , Evolução Biológica , Sobrevivência Celular/fisiologia , Clorófitas/citologia , Células Germinativas Vegetais/fisiologia
16.
Plant Cell Physiol ; 59(12): 2536-2548, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30137453

RESUMO

Under environmental stresses, Haematococcus pluvialis accumulates large amounts of carotenoids. Scale of carotenoid biosynthesis depends on availability of geranylgeranyl pyrophosphate (GGPP) precursor, which is supplied by GGPP synthase (GGPPS) through sequential 1'-4 condensation of three isopentenyl pyrophosphates (IPPs) into dimethylallyl pyrophosphate (DMAPP). Using IPP and DMAPP as substrates, a tri-functional HpGGPPS was identified in this study to promiscuously synthesize allylic prenyl pyrophosphates (PPPs), e.g. C10 geranyl pyrophosphate (GPP), C15 farnesyl pyrophosphate (FPP), and C20 GGPP. Intriguingly, HpGGPPS can utilize GPP or FPP as a single substrate to synthesize GGPP by hydrolyzing the allylic PPP substrate into C5 IPP. Transcription of HpGGPPS and key carotenogenesis genes, morphological transformation, and carotenoid biosynthesis were differentially induced by environmental stresses, while HpGGPPS's products were low in vivo, implying that most of PPP flux had been shunted into carotenoid biosynthesis. Hydrolyzing allylic PPP intermediates into C5 building blocks by promiscuous HpGGPPS may be a fail safe for carotenoid accumulation against environmental stress.


Assuntos
Proteínas de Algas/metabolismo , Clorófitas/enzimologia , Geranil-Geranildifosfato Geranil-Geraniltransferase/metabolismo , Carotenoides/biossíntese , Clorófitas/citologia , Clorófitas/genética , Ensaios Enzimáticos , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Teste de Complementação Genética , Hidrólise , Cinética , Fosfatos de Poli-Isoprenil/metabolismo , Proteínas Recombinantes/metabolismo , Estresse Fisiológico , Especificidade por Substrato , Fatores de Tempo
17.
J Phycol ; 54(6): 811-817, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30137670

RESUMO

Light/scanning electron/transmission microscopy-based morphological analyses and multiple nucleotide sequences-based molecular phylogenetic analyses are used to identify and assess the phylogenetic position of a new unidentified green alga isolated from bleached corals living in the South China Sea. This new unidentified green alga is a unicellular marine alga and has uninucleate vegetative cells and multiple chloroplasts with a pyrenoid. It can form aplanosporangium covered by cell walls and reproduces by releasing autospore. These features differ substantially from those of the two genera Ignatius and Pseudocharacium. Those two genera have been accommodated in the Ignatius clade. Nucleotide sequences of the nuclear small subunit ribosomal RNA gene (18S rRNA), internal transcribed spacer 2 of ribosomal RNA gene (ITS2) and ribulose-1,5 bisphosphate carboxylase/oxygenase large subunit gene (rbcL, partial) are obtained and compared with published green algal sequences. The results from the morphology, ultrastructure, and multiple nucleotide sequences data support the placement of the new unidentified green alga in Ulvophyceae. This new unidentified isolate is described as Symbiochlorum hainanensis gen. et sp. nov., a new sister lineage to the Ignatius clade, Ulvophyceae, Chlorophyta.


Assuntos
Clorófitas/classificação , Microalgas/classificação , Filogenia , RNA de Algas/análise , Animais , Antozoários , China , Clorófitas/citologia , Clorófitas/enzimologia , Clorófitas/genética , DNA Espaçador Ribossômico/análise , Microalgas/citologia , Microalgas/enzimologia , Microalgas/genética , Oceano Pacífico , RNA Ribossômico 18S/análise , Ribulose-Bifosfato Carboxilase/análise , Simbiose
18.
J Phycol ; 54(5): 616-629, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30076711

RESUMO

Lake Baikal, the oldest lake in the world, is home to spectacular biodiversity and extraordinary levels of endemism. While many of the animal species flocks from Lake Baikal are famous examples of evolutionary radiations, the lake also includes a wide diversity of endemic algae that are not well investigated with regards to molecular-biological taxonomy and phylogeny. The endemic taxa of the green algal order Cladophorales show a range of divergent morphologies that led to their classification in four genera in two families. We sequenced partial large- and small-subunit rDNA as well as the internal transcribed spacer region of 14 of the 16 described endemic taxa to clarify their phylogenetic relationships. One endemic morphospecies, Cladophora kusnetzowii, was shown to be conspecific with the widespread Aegagropila linnaei. All other endemic morphospecies formed a monophyletic group nested within the genus Rhizoclonium (Cladophoraceae), a very surprising result, in stark contrast to their morphological affinities. The Baikal clade represents a species flock of closely related taxa with very low genetic differentiation. Some of the morphospecies were congruent with lineages recovered in the phylogenies, but due to the low phylogenetic signal in the rDNA sequences the relationships within the Baikal clade were not all well resolved. The Baikal clade appears to represent a recent radiation, based on the low molecular divergence within the group, and it is hypothesized that the large morphological variation results from diversification in sympatry from a common ancestor in Lake Baikal.


Assuntos
Biodiversidade , Evolução Biológica , Clorófitas/classificação , Filogenia , Clorófitas/anatomia & histologia , Clorófitas/citologia , Clorófitas/genética , DNA de Algas/análise , DNA Ribossômico/análise , Evolução Molecular , Lagos , Análise de Sequência de DNA , Sibéria
19.
ACS Nano ; 12(7): 6668-6676, 2018 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-29906098

RESUMO

In this work, we demonstrate a simple, versatile, and real-time motion guidance strategy for artificial microengines and motile microorganisms in a ferrofluid by dynamic topographical pathways (DTPs), which are assembled from superparamagnetic nanoparticles in response to external magnetic field ( H). In this general strategy, the DTPs can exert anisotropic resistance forces on autonomously moving microengines and thus regulate their orientation. As the DTPs with different directions and lengths can be reversibly and swiftly assembled in response to the applied H, the microengines in the ferrofluid can be guided on demand with controlled motion directions and trajectories, including circular, elliptical, straight-line, semi-sine, and sinusoidal trajectories. The as-demonstrated control strategy obviates reliance on the customized responses of micromotors and applies to autonomously propelling agents swimming both in bulk and near substrate walls. Furthermore, the microengines (or motile microorganisms) in a ferrofluid can be considered as an integrated system, and it may inspire the development of intelligent systems with cooperative functions for biomedical and environmental applications.


Assuntos
Coloides/química , Hidrodinâmica , Nanopartículas de Magnetita/química , Nanotecnologia/instrumentação , Povidona/química , Catálise , Clorófitas/citologia , Desenho de Equipamento , Campos Magnéticos , Movimento (Física) , Platina/química , Polímeros/química , Pirróis/química
20.
Biosens Bioelectron ; 117: 15-22, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-29879583

RESUMO

Direct extraction of photosynthetic electrons from the whole photosynthetic cells such as plant cells or algal cells can be highly efficient and sustainable compared to other approaches based on isolated photosynthetic apparatus such as photosystems I, II, and thylakoid membranes. However, insertion of nanoelectrodes (NEs) into individual cells are time-consuming and unsuitable for scale-up processes. We propose simple and efficient insertion of massively-populated NEs into cell films in which algal cells are densely packed in a monolayer. After stacking the cell film over an NE array, gentle pressing of the stack allows a large number of NEs to be inserted into the cells in the cell film. The NE array was fabricated by metal-assisted chemical etching (MAC-etching) followed by additional steps of wet oxidation and oxide etching. The cell film was prepared by mixing highly concentrated algal cells with alginate hydrogel. Photosynthetic currents of up to 106 nA/cm2 was achieved without aid of mediators, and the photosynthetic function was maintained for 6 days after NE array insertion into algal cells.


Assuntos
Técnicas Biossensoriais/métodos , Elétrons , Fotossíntese , Clorófitas/química , Clorófitas/citologia , Eletrodos
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