Toxic action of copper on the membrane system of a marine diatom measured by flow cytometry

Flow cytometric measurements were used to investigate the toxic action of copper on some Phaeodactylum tricornutum membrane systems. Throughout the time of metal exposure, the percentage of viable cells decreased as copper concentration increased. The forward scatter signal increased as a result of copper exposure. After 72 h of metal exposure, cultures with 0.5 and 1 mg l−1 of copper showed an important increase in the peroxidase activity in comparison with control cells. Cells cultured with copper presented alterations in the membrane potential, increasing as copper concentration increased, after 96 h of metal exposure. Results obtained in this work showed that copper induced a degenerative process in P. tricornutum cells, closely related with alterations or disorders in membrane systems.Xunta de Galicia; XUGA 10301B9

Culture of the marine diatom Phaeodactylum tricornutum with different nitrogen sources: Growth, nutrient conversion and biochemical composition

[Abstract] Cultures of the marine diatom Phaeodaetylum trieornutum were grown in nitrate, nitrite, ammonia or urea media. Nitrogen transformation efficiencies were close to 100% in cultures with nitrate, nitrite or urea, with productivities in dry biomass between 2.2 g.l-1 (urea) and 2.8 g.t1 (nitrate). However growth in ammonia cultures ceased due to a drop in pH of the medium. The biochemical profile was more affected by the growth phase than by the N source. Cellular contents of chlorophylls a and e decreased and the chlorophyll ale ratio increased when cultures entered the stationary phase. Protein and RNA were higher during exponential growth (about 30% and 8% ash free dry weight (AFDW), respectively), but carbohydrates increased up to 220% in the stationary phase. Although significant differences were observed in cellular contents, the biochemical composition (as % AFDW) of the nitrate, nitrite and urea-grown cells was very similar. The highest total fatty acids and polyunsaturated fatty acids (PUFAs) contents in the stationary phase were obtained in the urea-grown cells, with an eicosapentaenoic acid (EPA) content of 26.8 mg.g-1 of dry biomass.[Résumé] Des cultures de la diatomee marine Phaeodaetylum trieornutum ont ete realisees dans des milieux contenant du nitrate, du nitrite, de l'ammonium ou de l'uree. Dans les milieux contenant nitrate, nitrite ou uree, l'efficacite de transformation de l'azote a ete proche de 100 ok, avec des rendements en biomasse seche allant de 2,2 g.l-1 (uree) a 2,8 g.t1 (nitrate), alors que la croissance en presence d'ammonium a ete inhibee a la suite d'une chute de pH du milieu. La phase de croissance a eu une influence plus grande sur Ie profil biochimique que la source d'azote. Les contenus cellulaires en chlorophylle a et e ont diminue et Ie rapport chlorophylle a Ie a augmente pendant la phase stationnaire. La quantite de proteines et d' ARN a ete plus elevee pendant la croissance exponentielle (environ 30 % et 8 % du poids sec ·sans cendres (AFDW) respectivement), tandis que les hydrates de carbone ont augmente de plus de 220 % durant la phase stationnaire. Malgre les differences significatives observees pour les contenus cellulaires, la composition biochimique des cellules (exprimee en % de AFDW) etait comparable dans les milieux contenant nitrate, nitrite ou uree. Le maximum en acides gras totaux et en acides gras polyinsatures (PUFAs) pendant la phase stationnaire a ete observe en presence d'uree, avec un contenu en acide eicosapentaenolque (EPA) de 26.78 mg.g-1 de biomasse seche.Consejo Interinstitucional de Ciencia y Tecnología; n° AGF92073

Características clínicas y biológicas del tromboembolismo pulmonar no provocado. Estudio de las mutaciones somáticas relacionadas con la hematopoyesis clonal de significado intermedio

[ES] Una cuestión clínica importante en el manejo de la enfermedad tromboembólica venosa (ETEV) es cómo seleccionar a los candidatos a anticoagulación prolongada. Según las guías actuales, para mantener el tratamiento anticoagulante debe evaluarse, en primer lugar, el tipo de evento tromboembólico: “provocado” (con factores de riesgo transitorios o persistentes) o “no provocado” (sin factores de riesgo identificados), así como determinar periódicamente los riesgos de hemorragia y de recurrencia. La categorización de los factores de riesgo para ETEV, es importante para valorar riesgo de recurrencia, y consecuentemente para tomar decisiones sobre la duración de la anticoagulación. Nuestro interés se centra en determinar las características clínicas y biológicas del tromboembolismo pulmonar (TEP) no provocado y también en la identificación de nuevos factores de riesgo con la relevancia que puedan tener las mutaciones relacionadas con la hematopoyesis clonal de significado indeterminado (CHIP)

Rapid assay for the analysis of class III metallothioneins by capillary zone electrophoresis in crude extracts of microalgal cells exposed to cadmium

An optimization strategy for the separation and analysis of class III metallothioneins from a complex matrix by capillary zone electrophoresis (CZE) is presented and illustrated. Metallothioneins are a group of polypeptides used for many organisms to alleviate stresses imposed by exposure to heavy-metal excess. The analysis requires several steps: chromatography on exclusion or anion-exchange columns, ultrafiltration and HPLC with derivatization. In the present paper, a rapid and simple separation technique by CZE with an uncoated polyimide-clad fused-silica capillary is described. This technique permits the analysis of these molecules without prior steps of purification and derivatization. The running conditions were voltage −12 kV, room temperature and 150 mM sodium phosphate buffer (pH 3.5). Based on this preliminary study, CZE with an uncoated fused-silica capillary using sodium phosphate buffer appears to be a useful technique for the separation of class III metallothioneins

Tolerance and detoxification mechanisms in marine diatom Phaeodactylum tricornutum exposed to cadmium

Tolerance is one of the most important mechanisms for survival. Organisms living in polluted environments with heavy metals develop tolerance to these contaminants; this tolerance has been attributed to the ability to synthesize metal-binding substances or another different mechanism able to mediate metal detoxification. It has been demonstrated that high levels of metals induce the formation of these substances in plants, algae, and some fungi (phytochelatins), which are a protective mechanism against the toxicity of heavy metals. In this study we have addressed the capacity of the microalga Phaeodactylum tricornutum to produce metal-binding pep tides in response to stress induced by cadmium. Liquid chromatography using biogel P-60, thiol analysis in chromatographic fractions, and capillary electrophoresis provided evidence of phytochelatins production in this alga

Variations in the biochemical profile of the marine microalga Dunaliella tertiolecta (Butcher) cultured with different nutrient concentrations and urea as a nitrogen source

[Abstract] Variations in the biochemical profile of the marine microalga Dunaliella tertiolecta (Butcher) cultured with different nutrient concentrations and urea as a nitrogen source. Cultures of the marine microalga Dwwliella tertiolecta were grown in a urea-based medium, using four nutrient concentrations following a geometrical progression of order 2, expressed as x I, x2, x4 and x8, in order to obtain a maximum biomass production and to find out its biochemical variability. The nutrient concentration had little effect on the growth rate in the logari thmic phase, with values between 0.40 and 0.44 doublings.day-I. Maximum cellular densities of7.53x106 and 7.96x106 cells.ml-I were obtained in x2 and x4 cultures (corresponding to 2 and 4 mM of urea). Differences in biochemical composition were found in function of the nutrient concentration. Protein content reached maximum values in the stationary phase in x4 and x8 cultures, with 29.56 and 29.28 pg.ceW I. The maximum value of carbohydrates was obtained in xl cultures, with 14.38 pg.cell- I. Maximum lipids per cell were obtained in the stationary phase in cultures with the higher nutrient concentration asssayed (x8), with 23.12 pg.ceWI. Cultures at the lower nutrient concentration assayed (xl) showed a nitrogen deficiency, with cells with low protein and high carbohydrate content at the stationary phase.[Resume] Variations du profil biochimique de la microalgue marine Dunaliellatertiolecta (Butcher) cultivee avec differentes concentrations de nourriture et dans un milieu d' uree. Afin d'obtenir les plus gran des quantites de biomasse et de trouver la variabilite biochimique de la microalgue marine D. tertiolecta, nous avons effectue des cultures dans un milieu d'uree, sous quatre concentrations differentes de nourriture, suivant une progress ion geometrique d' ordre (xl, x2, x4, x8). La concentration en nutriment azote n'a guere d'effet sur Ie taux de croissance dans la phase logarithmique (0,40 it 0,44 division.jour- I). Les densites cellulaires maximales (7,53 x 106 et 7,96 x 106 ceII.ml- l) ont ete obtenues dans les cultures x2 et x4, correspondant respectivement it 2 et 4 mM d' uree. Des differences au ni veau de la composition biochimique ont ete observees en fonction de la concentration en nourriture. Les contenus en proteines les plus eleves ont ete observes dans les cultures x4 et x8, soit 29,56 et 29,28 pg. ceWI. La valeur maxima en carbohydrates a ete obtenue dans les cultures x I (14,38 pg.ceW I). Les contenus en lipides par cellule les plus eleves ont ete observes dans les cultures ayant les plus grandes concentrations de nourriture (x8 : 23,12 pg.ceW I). Les cultures effectuees a la plus faible concentration en nutriment ont conduit it la production de cellules aux contenus peu eleves en pfbteines mais eleves en carbohydrates, lies au manque d'azote.Consejo Interinstitucional de Ciencia y Tecnología; n° AGF92-073

Effects of nitrogen source and growth phase on proximate biochemical composition, lipid classes and fatty acid profile of the marine microalga "Isochrysis Galbana"

[Abstract]The marine microalga Isochrysis galbana was cultured in nitrate, nitrite or urea media to examine changes in the gross biochemical composition, with special emphasis on the growth phase associated changes in the compositions of the lipid classes and fatty acids. The gross biochemical composition was affected more by the growth phase than by the nitrogen source. Protein was higher during exponential growth (about 37–45% AFDW) but the pattern changed as the cultures aged, and lipids were the main algal constituents on all nitrogen sources in the late stationary phase. In all cultures, the relative abundance of neutral lipid increased in the late stationary phase concomitant with a proportional reduction in phospholipids, whereas galactolipids only slightly changed during the growth of the cultures. Total fatty acid content was affected by nitrogen source and growth phase. Maximal PUFA values were obtained at the early stationary phase and decreased throughout the stationary phase. The highest fatty acid contents in the early stationary phase were produced in urea cultures; these cultures also had higher PUFA content, with EPA and DHA contents of 27.66% and 14.13% of total fatty acids, respectively.Consejo Interinstitucional de Ciencia y Tecnología; nº AGF92073

Long-chain class III metallothioneins as a mechanism of cadmium tolerance in the marine diatom Phaeodactylum tricornutum Bohlin

Cadmium tolerance of the marine diatom Phaeodactylum tricornutum Bohlin was studied. P. tricornutum growth was significantly reduced by cadmium concentrations of 5 mg l−1 or higher. The EC50 value was 22.39 mg l−1 of cadmium after four days of exposure. Therefore, P. tricornutum is more tolerant to cadmium than other microalgal cells. In response to exposure to cadmium, P. tricornutum synthesize class III metallothioneins which sequester the metal in a harmless form. However, cadmium tolerance of P. tricornutum cells is not only due to the ability of this microalga to synthesize class III metallothioneins (γ-Glu-Cys)n-Gly, but also because these metallothioneins are composed of long-chain polypeptides. The cadmium-metallothionein complexes of P. tricornutum cells contain predominantly polypeptides of n = 4−9. Long-chain metallothioneins are more efficient in binding heavy metals. Capillary electrophoresis was used to separate class III metallothioneins. This is a recent technique used to separate many molecules. With this technique, the length of the separated polypeptides can also be estimated.Xunta de Galicia; XUGA 10301B9

Microalgas: cultivo y aplicaciones

Monografías; n. 26[Resumen] Esta obra ofrece una amplia y detallada panorámica de las microalgas, su cultivo (parámetros, especies utilizadas, sistemas y procedimientos) y las aplicaciones que pueden tener en la nutrición animal, la acuicultura, las prácticas terapéuticas, en distintas ramas de la industria o en el tratamiento de aguas residuales. INDICE: 1. Introducción; 2. Antecedentes históricos; 3. Parámetros de cultivo; 4. Especies utilizadas y criterios de selección; 5. Sistemas de cultivo y recogida; 6. Composición bioquímica; 7. Microalgas en nutrición animal; 8. Microalgas en acuicultura; 9. Otras aplicaciones; 10. Bibliografía

Un nuevo criterio para sexar mirlos acuáticos (Cinclus cinclus) en la Península Ibérica

Una mostra de 231 merles d'aigua de la península Ibèrica es van mesurar i sexar utilitzant mètodes moleculars. Les merles d'aigua es van capturar en quatre àrees diferents d'Espanya que es poden agrupar en dues grans regions segons les seves característiques morfològiques: sud (muntanyes de Sierra Nevada) i la resta d'Espanya (Pirineus Occidentals, serralada Cantàbrica i Sistema Central). A partir d'una regressió logística considerant la longitud de la tercera primària, massa corporal i àrea geogràfica com a variables descriptives, es va obtenir una fórmula per a la classificació dels mascles i les femelles de merla d'aigua amb un error del 1,3% més baix que el que s'obté amb altres criteris disponibles a la bibliografia europea