Resumen Este trabajo abarcó el estudio sedimentológico, paleontológico y geoquímico de la Formación La Luna, en una localidad al oeste del Macizo de Santander (Matanza, Colombia). La sección corresponde a un corte de 42 metros, compuesto por una alternancia de mudstones y wackestones inter- estratificados, niveles de chert, fosforitas y bentonitas. El contenido fósil está conformado por restos de amonitas, inocerámidos, gasterópodos turritélidos, fragmentos de peces y foraminíferos planctónicos. La asociación fósil indica una edad de Coniaciano-Santoniano. Las características sedimentológicas, el tipo de fósiles encontrados y los análisis petrográficos/geoquímicos desarrollados en esta sección sugieren condiciones de depositación en plataforma externa y una baja oxigenación en los sedimentos de fondo. Las conclusiones de este trabajo coinciden con interpretaciones preexistentes de la región cuenca, sugiriendo relaciones litoestratigráficas con la sucesión sedimentaria del Valle Medio del Magdalena (parte superior del “Miembro Galembo”). Sin embargo, solo estudios estratigráficos detallados en esta parte del Macizo de Santander, permitirán entender su evolución geológica durante el Cretácico superior.

Abstract This study comprised the sedimentological, paleontological and geochemical survey of the La Luna Formation, using as a reference one section in the west flank of the Santander Massif (Matanza, Colombia). The 42-meter length section comprises an alternance of interstratified mudstones, wackestones, chert, phosphorite and bentonite levels. Fossil content is defined by rest of ammonoids, inoceramids, turritellid gastropods, fish remains and planktonic foraminifers, suggesting all a Coniacian-Santonian age. The facial analysis, the fossil content and preliminary petrographic/geochemical analysis also suggest an outer shelf setting and low oxygenation conditions in the bottom sediments. In general, our results agree with previous interpretations of La Luna Formation, suggesting a closer relation with the Upper Cretaceous succession of the Middle Magdalena (upper “Galembo Member”). However, only detailed stratigraphical studies in this part of the Santander Massif, will allow a better understanding of its geological evolution during the Late Cretaceous.

ABSTRACT μ-Benzene-1,2,4,5-tetracarboxylato-κ2O1:O4)bis-[aqua-bis-2-(aminomethyl) pyridine-κ2N,N’) nickel (II)] decahydrate, [Ni2(amp)4(btc)(H2O)2]10H2O has been synthesized and its crystal structure determined by X-ray diffraction. The complex crystallizes in the Monoclinic space group P21/n with cell dimensions a= 11.0102 (10) Å, b= 21.5416 (19) Å, c= 11.0445 (10) Å and β= 118.753 (1)°, and two formula units per cell (Z= 2, Z’= 0.5). The structure consists of centrosymmetric dimeric units in which the benzene tetracarboxylate anions (btc) bridge the symmetry-related nickel (II) cations, two bidentate chelating molecules of 2-(aminomethyl) pyridine and a terminal aqua ligand completing the six-fold coordination at each metal. These dimers link to each other via H-bonding to form chains parallel to [100], while the water solvates form a strongly bound 2D network parallel to (100), made up by small (R44(8)) and large (R2020(40)) rings, the latter ones “pierced” by the chains of dimmers, with a profuse H-bonding interconnection between both substructures. Magnetic susceptibility measurements as a function of temperature disclose weak interdimeric exchange interactions. Fitting of these data to a dimeric model yields J= −3.5 cm-1 and g= 2.13.

ABSTRACT The mononuclear cobalt (III) complex derived from 1,10-phenanthroline with lactose [Co(phen)2lactose]Cl2·3H2O (1) has been prepared and its properties have been compared with the sucrose complex [Co(Phen)2sucrose]Cl2·3H2O(2) and the complex without carbohydrate [Co(Phen)2Cl2]Cl·3H2O(3). The chemical structure of (1) was assigned by 1H-NMR, IR, CD and UV-Vis spectral data. The antibacterial activity of (1) - (3) was evaluated by disc-diffusion assays, using Gram-negative and positive bacteria. The minimum inhibitory concentration of the three complexes on the studied bacteria and their cytotoxicity on HEK293 human cells was determined. A colorimetric plate assay was used to distinguish bacteriostatic from bactericidal effect. Finally, the complexes uptake mechanism was evaluated using bacteria with mutated genes that encode for carbohydrate and siderophore receptors. The results indicate that complex (1) has an antibacterial activity similar to (3), while (2) presents a more restricted one. Moreover, all three complexes act by a bacteriostatic effect against bacterial cells and both (1) and (3) use a siderophore uptake mechanism to enter on bacterial cytoplasm. Cytotoxicity assays show that carbohydrate complexes are not cytotoxic to human cells, in contrast with complex (3), which is highly toxic. These results suggest that the use of the lactose ligand would maintain the antibacterial activity and uptake mechanism of the complex at reasonable levels, and would also reduce its toxicity against human cells. Thus, its strategic use would allow a decrease in toxicity of complexes used in eventual studies on eukaryotic systems.

We report the synthesis and crystal structure of a copper (II) polymeric complex (I) prepared by reaction of Cu(ClO4)2 ·5H2O with H3tea (triethanolamine,) and dpe (1,2-di(4-pyridyl)ethylene). in ethanol. The compound is made up of two well differentiated substructures, the first one being a cationic 1D polymer balanced by ClO4- counteranions {[Cu2(H2tea)2(dpe)]·(ClO4)2}n and the second one made is up of two dimers of different occupancies and charge content, viz., [Cu2(Htea)2(dpe)] (neutral, 64% occupancy) and [Cu2(H2tea)2(dpe)]2+ (cationic, 36% occupancy), this latter fraction balancing the charge introduced by ClO4- anions with 72% occupancy. Both substructures differ in that the Hm tea anions in the dimers (m = 1,2) do not bridge cations as their homologue H2tea does in the polymer, but chelate instead one single Cu each. As shown in scheme. The structure of (I) is compared with its close relative [Cu2(H2tea)2(dpe)]·(bpe)·(ClO4)2·H2O (II), where the same original constituents assemble in a slightly different way¹.

The mononuclear cobalt(III) complex derived from 1,10-phenanthroline and maltose ([Co(phen)2maltose]Cl2∙3H2O) (1) has been synthesized and characterized in aqueous solution. Its characterization was based on its optical and spectroscopic properties. The antimicrobial activity of this complex was screened in vitro against the microorganisms Escherichia coli DH5a, Salmonella enterica sv Enteritidis ISP/953, Klebsiella pneumoniae RYC492, Pseudomonas aeruginosa PAO1, Enterococcus faecalis ATCC 29212, Bacillus cereus GCA234, Micrococcus sp. Staphylococcus aureus ATCC25923. Complex (1) showed antibacterial activity with a bacteriostatic effect over Gram positive and negative bacteria. The cytotoxicity of complex (1) was tested in vitro on human embryonic kidney cells.

Objetivo: comparar efectividad del polietilenglicol y manitol en la preparación intestinal mediante escala de Boston, pacientes de la consulta externa de gastroenterología, tercer trimestre, 2012. Pacientes y métodos: estudio prospectivo, transversal, experimental. Muestra de 100 pacientes aleatorizados en dos grupos: polietilenglicol y manitol, 50 en cada uno. A todos se les instauró dieta líquida el día previo al estudio e indicación para la ingesta de la solución a evaluar. Se realizó colonoscopia con evaluación endoscópica según escala de Boston. Resultados: la tolerancia a la preparación fue considerada fácil por 88% en el grupo polietilenglicol vs 100% del grupo manitol (p=0,041). El 98% del grupo manitol consideró que este medicamento tenía sabor agradable en comparación con polietilenglicol (78%) (p=0,002). El efecto adverso más frecuente en ambos grupos fue la náusea. El polietilenglicol alcanzó exploraciones completas con restos en un 82% colon derecho, 56% colon transverso y 72% colon izquierdo, mientras que con manitol prevaleció la exploración completa sin restos en 66%, 90% y 68% respectivamente (p<0,05). La puntuación global de la escala de Boston con polietilenglicol y manitol fue 6 vs 8 (p<0,05). Conclusiones: manitol resultó ser más efectivo que polietilenglicol para la preparación del colon en su totalidad y por segmentos.

Objective: To compare the effectiveness of polyethyleneglycol and mannitol bowel preparation by Boston scale, in patients from the outpatient gastroenterology in the third quarter of 2012. Method: Prospective, cross, experimental with a sample of 100 patients randomized to group polyethyleneglycol and mannitol group, 50 in each. All were introduced liquid diet the day before the test with the appropriate indication for the intake of the solution to evaluate and colonoscopy was performed endoscopic evaluation scale as Boston. Result: tolerance was considered easy preparation by 88% in polyethyleneglycol group vs 100% mannitol group (p=0.041). 98% mannitol group had considered that this medicine palatable compared with polyethyleneglycol (78%) (p=0.002). The most common adverse event in both groups was nausea. Polyethyleneglycol reached full scans with remains at 82% right colon, transverse colon 56% and 72% left colon, whereas mannitol prevailed without full exploration remains at 66%, 90% and 68% respectively (p<0,05). The overall rating scale was polyethyleneglycol Boston 6 vs 8 in the mannitol group (p<0,05). Conclusions: mannitol was more effective for the preparation of polyethyleneglycol entire colon and segments.

El hepatocarcinoma es la neoplasia primaria hepática más frecuente con una incidencia creciente en todo el mundo cuyo pronóstico está ligado con el diagnóstico temprano. Objetivos: Determinar la frecuencia del hepatocarcinoma en pacientes del Servicio de Gastroenterología del Hospital Militar "Dr. Carlos Arvelo" durante el período 2006-2011. Métodos: Trabajo retrospectivo y descriptivo. Se recolectaron historias médicas de 39 pacientes con ese diagnóstico. Resultados: Los rasgos demográficos fueron similares a los descritos en Occidente: predominio hombres (71,79%), edad promedio entre 60 y 69 años (35,8%). La primera causa fue por hepatitis C (35,89%), seguida por el alcohol (25,64%) y hepatitis B (15,38%). Para estadificación se usaron los criterios Barcelona Clinic Liver Cancer, siendo al momento del diagnóstico el estadio D el más frecuente (68,57%). El 28,20% recibió tratamiento. Sorafenib fue lo más utilizado, (7 pacientes) dado que ingresaban al Hospital en estadio terminal limitando las opciones terapéuticas. El 12,8% de los pacientes estaban vivos al momento de realizar el estudio. Conclusiones: El hepatocarcinoma es un tumor raro en nuestro medio. Frecuentemente produce pocos síntomas, manifestándose como descompensación de la función hepática en pacientes con cirrosis por lo que debe intensificarse la pesquisa, para lograr diagnóstico temprano y mejorar el pronóstico.

Hepatocellular carcinoma is the most common primary neoplasm liver with an increasing incidence worldwide whose prognosis is linked to early diagnosis. Objetives: To determine the frequency of hepatocellular carcinoma in patients from the Gastroenterology Service of the Military Hospital "Dr. Carlos Arvelo" during the period 2006-2011. Methods: Retrospective and descriptive. Were collected from medical records of 39 patients with that diagnosis. Results: The demographic features were similar to those described in the West: predominantly men (71.79%), average age between 60 and 69 (35.8%). The first cause was hepatitis C (35.89%), followed by alcohol (25.64%) and hepatitis B (15.38%). For staging criteria were used Barcelona Clinic Liver Cancer, being at the time of diagnosis, stage D the most common (68.57%). The 28.20% received treatment. Sorafenib was the most used, (7 patients) admitted to the hospital since end-stage limiting therapeutic options. 12.8% of patients were alive at the time of the study. Conclusions: Hepatocellular carcinoma is a rare tumor in our environment. Often produces few symptoms, manifesting as decompensation of liver function in patients with cirrhosis and should be intensified screening to achieve early diagnosis and improve prognosis.

Lactobacillus reuteri LPB P01-001 was isolated from the gastrointestinal tract of wild swine and was characterised by biochemical testing and sequencing of gene 16S rRNA. A simple and low-cost culture medium based on cane sugar (2.5% p/v) and yeast extract (1% p/v) was used in the production of this probiotic. The fermentative conditions were a) pH control at 6.5 and b) no pH control; both were set at 37°C in a 12 L slightly stirred tank bioreactor. Fermentation parameters such as the specific growth rate, productivity and yield of biomass, lactic and acetic acid levels were determined. L. reuteri LPB P01-001 behaves as an aciduric bacteria because it grows better in a low pH medium without pH control. However, the lactic acid production yield was practically half (9.22 g.L-1) of that obtained under a constant pH of 6.5, which reached 30.5 g.L-1 after 28 hours of fermentation. The acetic acid production was also higher under pH-controlled fermentation, reaching 10.09 g.L-1 after 28 hours of fermentation. These parameters may raise the interest of those committed to the efficient production of a probiotic agent for swine.

A study from cows with mastitis was performed and Staphylococcus aureus was the predominant pathogen in 46.4 % among 153 studied strains from 276 milk samples of infected cows. Antibiotic resistance of 71 S. aureus isolates was determined in order to search resistant strains to antibiotics of clinical interest, as well as to determine their degree of multi-resistance. It was found that 60% of the S. aureus strains presented resistance to β-lactams, but none to oxacillin, teicoplamin or vancomycin. On the other hand, with the aim of reducing the use of current antibiotics and their associated resistance, a new formulation was introduced. The antimicrobial compounds (P22-P32), demonstrated to be effective in 55% of the 76 mastitis cases studied. The use of P22-P32 reduced the number of somatic cell to less than 300,000 SCC/mL-1 in 75.2 % of milk samples analyzed, normalizing the milk quality, fat and lactose levels and increasing the volume of production in 10.1 %.

D-Glucose derivatives 1,2:5,6-di-O-isopropyline-a-D-glucofuranose (1) and 1,2-O-isopropyline-a-D-glucofuranose (2) with Ti(IV) are chiral catalysts in the addition of diethylzinc to benzaldehyde. The Ti(IV)-carbohydrate catalytic system is optimal with excess Ti(IV) and substoichiometric carbohydrate and 2 is the more active chiral catalyst probably because this derivative acts as a bidentate ligand in the proposed reaction. The arrangement of OH groups is crucial in determining the configuration of the alcohol product.

A extração de fitases produzidas por fermentação em estado sólido de polpa cítrica foi estudada utilizando um processo de extração sólido-líquido em varias etapas. A adição de EDTA permite manter durante 24 horas a temperatura ambiente 90% da atividade inicial do caldo com a enzima extraída. Um planejamento fatorial 2², com 4 replicas no ponto central, foi desenvolvido para testar os valores de ph e agitação convenientes para a extração das enzimas. A interação entre ambos os fatores foi estadisticamente significativa. A atividade da enzima foi otimizada nos valores onde o pH (5.0) e a agitação (350 rpm) resultaram ser as melhores condições para extrair a enzima da matriz sólida. O ajuste do modelo matemático obtido mostra que é possível considerar a difusividade como o mecanismo que controla o processo de transferência de massa. A constante cinética que descreve este processo e a concentração de saturação foram 0.039 min-1 e 4.01 IU/mL respectivamente. A extração em varias etapas mostrou que nas duas primeiras etapas é possível recuperar 85% da fitase produzida.

The extraction of phytase produced by solid-state fermentation of citrus peel was studied employing a multistage leaching process. It was observed that the extracts containing EDTA retained over 90% of phytase activity at room temperature after 24 h after the leaching. A fractional design 2² (with 4 replicates at the central point) was carried out for testing the pH and agitation as process independent factors. Only the interaction between the pH and agitation showed a significant influence. These factors were optimized with a central composite design. Agitation at 300 rpm and pH at 5.0 were the best conditions to extract the enzyme from solid matrix. The modeling of the process indicated that diffusivity of the enzyme in the solvent was the controlling mechanism. The corresponding kinetic constant and saturation concentration in this process were 0.89 min-1 and 4.0 IU/mL, respectively. The multistage process indicated that after two steps, it was possible to recover 85% of total enzyme produced.

Introducción: la resección de la lesión con márgenes libres de tumor es el objetivo de la cirugía conservadora del cáncer mamario. Si hay tumor en el margen quirúrgico la tasa de recurrencia será más alta. Objetivos: se evalúa la experiencia del Centro de Diagnóstico Mamario (CENDIMA) de la Asociación Española Primera de Socorros Mutuos en cuanto a la cirugía conservadora del cáncer mamario guiada por marcador metálico. Se estudia la amplitud de los márgenes quirúrgicos y se analizan los factores que se asocian con la obtención de márgenes positivos. Material y método: se analizan todos los casos de cáncer mamario subclínico tratados con cirugía conservadora guiada por marcador metálico desde enero de 2007 a diciembre de 2009 (147 casos). Resultados: los márgenes fueron positivos (en contacto con la lesión o con una amplitud de hasta 1 mm) en 39 casos (26%) y negativos (con una amplitud de 2 mm o mayor) en 108 casos (74%). El tamaño promedio de la lesión fue mayor en los casos con márgenes positivos (15,6 mm contra 11,4 mm). En la población con márgenes positivos se observó mayor frecuencia de un componente ductal in situ (82% contra 42%), y mayor frecuencia de microcalcificaciones en la imagen mamográfica (51% contra 14%). Se realizó la reexcisión por márgenes insuficientes en 42 casos (29%) y se encontró tumor residual en 21 de estos casos (50%). Conclusión: el perfil de la lesión con mayor probabilidad de que los márgenes quirúrgicos sean positivos luego de la cirugía conservadora guiada por marcador metálico es el siguiente: lesión mayor de 10 mm, con un componente ductal in situ en su histología y con microcalcificaciones en la imagen.

Résumé Introduction: la résection de la lésion à marges libres de tumeur est le but de la chirurgie conservatrice du cancer de sein. S’il existe une tumeur à la marge chirurgicale, le taux de récurrence sera plus élevé. Objectifs: on évalue l’expérience du Centre de Diagnostic Mammaire (CENDIMA) de l’Asociación Española Primera de Socorros Mutuos en ce qui concerne la chirurgie conservatrice du cancer de sein guidée par marqueur métallique. On étudie la proportion des marges chirurgicales et on analyse les facteurs associés à l’obtention de marges positives. Matériel et méthode: on analyse tous les cas de cancer mammaire sous clinique traités avec une chirurgie conservatrice guidée par marqueur métallique depuis janvier 2007 jusqu’en décembre 2009 (147 cas). Résultats: les marges ont été positives (en contact avec la lésion ou avec une amplitude qui atteint 1 mm) à 39 cas (26%) et négatives (à amplitude de 2 mm ou plus) à 108 cas (74%). La taille moyenne de la lésion est plus grande aux cas ayant des marges positives (15,6 mm contre 11,4 mm). Dans la population à marges positives, on observe une plus haute fréquence d’un composant canaliculaire in situ (82%) contre 42%), et une plus haute fréquence de micro calcifications à la marge mammographique (51% contre 14%). On a fait résection pour marges insuffisants à 42 cas (29%) et on a trouvé une tumeur résiduelle à 21 cas (50%). Conclusion: le profil de la lésion qui a plus de chances d’avoir des marges chirurgicales positives après la chirurgie conservatrice guidée par marqueur métallique, est le suivant: lésion majeure de 10 mm, avec un composant canaliculaire in situ à son histologie et avec des micro calcifications à l’image.

Resumo Introdução: a resecção da lesão com margens sem tumor é o objetivo da cirurgia conservadora de câncer de mama. A presença de tumor na margem cirúrgica faz com que a taxa de reincidência seja mais alta. Objetivos: avaliar a experiência do Centro de Diagnóstico Mamário (CENDIMA) da Asociación Española Primera de Socorros Mutuos nas cirurgias conservadoras de câncer de mama guiadas por fio metálico. Faz-se o estudo da dimensão das margens cirúrgicas e analisam-se os fatores associados à obtenção de margens positivas. Material e método: faz-se uma análise de todos os casos de câncer de mama subclínico tratados com cirurgia conservadora guiada por fio metálico no período janeiro de 2007 a dezembro de 2009 (147 casos). Resultados: as margens foram positivas (em contato com a lesão ou com até 1 mm de dimensão) em 39 casos (26%) e negativos (com 22 mm ou mais de extensão) em 108 casos (74%). O tamanho médio da lesão era maior nos casos com margens positivas (15,6 mm contra 11,4 mm). Na população com margens positivas observou-se uma maior freqüência de um componente ductal in situ (82% contra 42%), e maior freqüência de microcalcificações nas imagens mamográficas (51% contra 14%). Em 42 casos (29%) fez-se uma reextirpação por margens insuficientes e em 21 destes casos havia tumor residual (50%). Conclusão: o perfil da lesão com maior probabilidade de ter margens cirúrgicas positivas depois de uma cirurgia guiada por fio metálico é: lesão com mais de 10 mm, com componente ductal in situ na histologia e com microcalcificações na imagenologia.

Summary Introduction: lesion resection with tumor free margins is the objective in breast cancer. If there is a tumor in the surgical margin the rates of recurrence will be higher. Objectives: to evaluate the experience at the Centro de Diagnóstico Mamario (CENDIMA - Breast Diagnosis Center) of the Asociación Española Primera de Socorros Mutuos, in terms of conservative surgery of breast cancer guided by metal markers. The surgical margins width and the factors associated with the positive margins are studied. Method: we analysed all cases of subclinical breast cancer treated with conservative surgery guided by metal markers from January 2007 through December 2009 (147 cases). Results: margins were positive (in contact with the lesion or nearest margin width was up to 1mm) in 39 cases (26%) and negative (width was 22 mm or larger) in 108 cases (74%). Average lesion size was greater the positive margin cases (15,6 mm compared to 11,4 mm). An in-situ ductal component was more frequently observed among the positive margins population (82% compares to 42%), and microcalcifications were more frequent in mammographic images (51% compared to 14%). Re-excision due to insufficient margins was performed in 42 cases (29%) and residual tumors were found in 21 of these cases (50%). Conclusion: the profile of the lesion that is more likely to evidence positive surgical margins after a conservative surgery guided by a metal marker is the following: lesion greater than 10 mm, with an in-situ component in its histology and microcalcification observed in the image.

Um derivado da D-xylose, 1,2-O-isopropilideno-α-D-xilofuranose (1), com Ti(OiPr)4 foi usado como catalisador chiral na alquilação assimétrica do benzaldeído com dietilzinco (Et2Zn) para produção de 1-fenil-1-propanol em alto rendimento (conversão de 90%) e enantiosseletividade moderada (45% ee (S)). As condições ótimas (conversão e enantiosseletividade) para o sistema catalítico formado por 1 e Ti(IV) foram 10.0 mol % de 1 e 1 equivalente de Ti(IV) com relação ao benzaldeído em CH2Cl2 como solvente, a temperatura ambiente. Na alquilação assimétrica do benzaldeído com Et2Zn, o composto 1 em quantidade sub-estequiométrica com Ti(OiPr)4 forma um catalisador quiral do tipo Ti(IV)-açúcar, o que assegura uma conversão com bom rendimento e a enantiosseletividade da reação.

A derivative of D-xylose, 1,2-O-isopropylidene-α-D-xylofuranose (1), with Ti(OiPr)4 was used as a chiral catalyst in the asymmetric alkylation of benzaldehyde with diethylzinc (Et2Zn) for the high-yield production (90% conversion) and moderate enantioselectivity (45% ee (S)) of 1-phenyl-1-propanol. Optimum conditions (conversion and enantioselectivity) for the catalytic system formed by 1 and Ti(IV) were 10.0 mol % of 1 and 1 equivalent of Ti(IV) with respect to benzaldehyde in CH2Cl2 as a solvent, at room temperature. In the asymmetric alkylation of benzaldehyde with Et2Zn compound 1 in substoichiometric amount with Ti(OiPr)4 forms a chiral catalyst of the Ti(IV)-sugar type that ensures the good-yield conversion and the enantioselectivity of the reaction.

The cockle Cerastoderma edule (L.) settles preferably in intertidal estuarine zones, buried under the uppermost centimetres of the sediment. Owing to this specific environment, the density of its populations is affected not only by biotic interactions, but also by meteorological phenomena, especially during low tide. A study was conducted over the course of seven years on the population dynamics and fishery of the cockle in two intertidal beds of the Ria of Arousa (NW Spain). The relationship between mortality and the population total density, precipitation and atmospheric temperature was analyzed during this period. The multiple regression model that includes the four variables under study provides a satisfactory explanation for the mortalities observed during the periods being compared. This model allows us to estimate the natural mortality by using variables that are relatively easy to obtain. It also proved to be a useful computational tool for readjusting the estimations of stock sizes in light of the meteorological conditions recorded.

El berberecho Cerastoderma edule (L.) se asienta preferentemente, en áreas estuáricas intermareales, enterrado bajo los primeros centímetros del sedimento. En este ambiente la densidad de sus poblaciones se ve afectada no sólo por diferentes interacciones biológicas, sino también por los fenómenos meteorológicos, sobre todo durante la bajamar. A lo largo de siete años se estudió la dinámica de poblaciones del berberecho y su pesquería en dos bancos intermareales de la ría de Arousa (NW de España). En este período se ha analizado la relación entre la mortalidad de juveniles y la densidad total de la población, la precipitación y la temperatura atmosférica. El modelo de regresión múltiple que incluye las cuatro variables estudiadas explica satisfactoriamente las mortalidades observadas entre los períodos comparados. Este modelo permite estimar la mortalidad natural a partir de variables relativamente fáciles de obtener, y constituye una herramienta de cálculo útil para reajustar las estimaciones del tamaño de los stocks en función de las condiciones meteorológicas registradas.

This study describes the fast and simultaneous determination of glutathione and glutathione disulfide by Capillary Zone Electrophoresis in plant extracts of shoot and root of tomato plants. Frequentuse of acidic precipitation of protein generates an acidic matrixof strength and pH tha may cause changes inthe method sensitivity, comigration of species or changes in the equilibria that relate both species in cells or fluids. In this study, the resulting acidic matrix was previously treated with the same background electrolyte to prevent comigration and to improve signal resolution. Optimization of some parameters of the technique allowed the determination of both analytes in less than three minutes. The optimized method showed good reproducibility and linearity, with correlation coefficients above 0.999 and detection limits below 3 µM for both peptides. Analyte recovery in the process was in the 88-104% range. The concentration found in tomato plants hydroponically grown inthe absence of stress factors was inthe 51-100 nmol g-1 range, fresh weight for GSH and 5-32 nmol g-1 range, fresh weightfor GSSG