Dinámica espacial del mero Epinephelus morio (Pisces: Serranidae) en el Banco de Campeche, Golfo de México

The spatial dynamics of the red grouper Epinephelus morio plays a fundamental role in the fishery management on the Campeche Bank, where it is overfished. The objective of this study was to characterize the spatial dynamics of this population. We used a dynamic model of spatial distribution to estimate population movement rates between adjacent areas. The model was applied using information on catch per unit effort and length-frequency distributions for the Mexican mid-sized fleet that operated in the area in the period 1973-1977. These data were chosen to ensure that the information would reflect the condition of the resource before overfishing. It was possible to quantify the spatial dynamics of the red grouper and the results were consistent with previously known movement patterns. The results showed different movement rates and temporal patterns of movement for different population sectors. The spawning aggregations and the seasonal upwelling occurring in the eastern part of the Bank were considered as key factors influencing the pattern of population movements.La población del mero rojo Epinephelus morio del Banco de Campeche está sobreexplotada. La dinámica espacial del mero juega un papel fundamental en la gestión de la pesquería. El objetivo de este estudio fue caracterizar la dinámica espacial de la población del mero en el Banco de Campeche. Se utilizó un modelo dinámico de distribución espacial para estimar tasas de movimiento poblacional entre áreas adyacentes. El modelo se aplicó con información de las capturas por unidad de esfuerzo y de distribuciones de frecuencias de longitud provenientes de la flota mediana mexicana que operó en la zona de 1973 a 1977. Estos datos fueron elegidos para asegurar que la información reflejara el estado del recurso antes de la sobrepesca. Fue posible cuantificar la dinámica espacial del mero y los resultados concordaron con patrones de movimientos conocidos anteriormente. Los resultados mostraron distintos patrones temporales de movimiento para los diferentes sectores de población. Se considera que las agregaciones de desove y la surgencia estacional que ocurre en la parte oriental del Banco son factores clave que influyen en el patrón de los movimientos de población

Productividad secundaria en los esteros de la barra de arena El Mogote en la Ensenada de La Paz, Baja California Sur, México

Mangrove ecosystems are critical habitats for many species, and their productivity is important because of their contribution of organic detritus and secondary production. The objective of this study was to identify suitable indicators of secondary productivity of mangrove systems, in order to establish a baseline for measuring changes in the mangrove system due to natural or anthropogenic potential disturbances. The bivalve mollusks chosen as indicators of secondary productivity were the mangrove cockle Anadara tuberculosa and the mangrove oyster Crassostrea palmula. Samples were collected in three estuaries from August 2007 to July 2009. Abundance and secondary production were estimated from biomass increase, calculated from individual growth rates determined using length frequency distributions analysis. The average abundance was 1.27 and 510 ind · m-2 of mangrove cockle and mangrove oyster respectively. It was estimated a growth rate of 4.91 mm · month-1 (3.67 g · month-1 ) for mangrove cockle and 3.80 mm · month-1 (0.18 g · month-1 ) for the mangrove oyster. The mean secondary production of mangrove cockle was 4.51 g · m-2 · month-1 and was higher during spring, while for the mangrove oyster it was 97.9 g · m-2 · month-1 , and the maximum production was recorded during summer. The results show that these indicators of benthos quality are suitable for measuring changes of the mangrove system in the Ensenada of La Paz, B. C. S., Mexico.Los ecosistemas de manglar son un hábitat crítico para numerosas especies y su productividad es importante por su contribución de detritos orgánicos y su producción secundaria. El objetivo del trabajo fue definir indicadores de productividad secundaria para establecer una línea base que permita medir alteraciones en el sistema de manglar por posibles perturbaciones naturales o antropogénicas. Como indicadores se escogieron los moluscos bivalvos pata de mula, Anadara tuberculosa y el ostión de mangle, Crassostrea palmula. Se realizaron muestreos en tres esteros de agosto de 2007 a julio de 2009. Se estimó la abundancia y la producción secundaria con base en el incremento de biomasa. Para la estimación del incremento en peso se usaron las tasas de crecimiento individual obtenidas mediante un análisis de distribuciones de frecuencia de tallas. La abundancia promedio fue de 1.27 y 510 ind · m-2 de la pata de mula y ostión de mangle respectivamente. Se estimó una tasa de crecimiento de 4.91 mm · mes-1 (3.67 g · mes-1 ) para la pata de mula y de 3.80 mm · mes-1 (0.18 g · mes-1 ) para el ostión de mangle. La producción secundaria promedio de pata de mula fue de 4.51 g · m-2 · mes-1 y fue mayor durante la primavera, mientras que para el ostión de mangle fue de 97.9 g · m-2 · mes-1 , registrándose la máxima producción durante el verano. Los resultados obtenidos demuestran que estos indicadores de calidad del bentos son adecuados para medir alteraciones al sistema de manglar de la Ensenada de La Paz, B. C. S., México

Amino acid tissue levels and GABAa receptor binding in the developing rat cerebellum following status epilepticus

Incidence of status epilepticus (SE) is higher in children than in adults and SE can be induced in developing rats. The cerebellum can be affected after SE; however, consequences of cerebellar amino acid transmission have been poorly studied. The goal of this study was to determine amino acid tissue concentration and GABAA receptor binding in the immature rat cerebellum after an episode of SE. Thirteen-day-old (P13) rat pups received in- traperitoneal injections of lithium chloride (3 mEq/kg). Twenty hours later, on P14, SE was induced by subcutaneous injection of pilocarpine hydrochloride (60 mg/kg). Control ani- mals were given an equal volume of saline subcutaneously. Animals were killed 24 h after SE induction, the cerebellum was quickly removed, and the vermis and hemispheres were rapidly dissected out on ice. Amino acid tissue concentrations in the vermis and hemi- spheres were evaluated by HPLC and fluorescent detection. GABAA receptor binding in the medial vermis was analyzed by in vitro autoradiography. SE increased the tissue levels of the inhibitory amino acids taurine (80%) and alanine (91%), as well as glutamine (168%) in the cerebellar hemisphere; no changes were observed in the vermis. SE did not modify GABAA receptor binding in any cerebellar lobule from the vermis. Our data demonstrate that SE produces region-specific changes in amino acid concentrations in the developing cerebellum

Estimation of growth parameters in a wild population of lion-paw scallop (Nodipecten subnodosus ) in Bahia de Los Angeles, Baja California, Mexico

The lion-paw scallop Nodipecten subnodosus is a commercially important resource in the northwest of Mexico; however few studies evaluate its growth. Length of shell was used to estimate individual growth parameters of the lion-paw scallop from a wild population. Monthly samplings were performed from January to December 2006 in Bahia de Los Angeles on the western coast of the Gulf of California, Mexico. Morphometric relationships between total length, height, total weight, and mass weight were estimated. The number of cohorts was determined monthly using the multinomial technique based on a likelihood function. The cohort that was best represented over time was used to fit the stationary growth model of von Bertalanffy. The results indicated that this species presents negative allometric growth and showed high correlation among different morphometric measures (R2 > 0.88). Length frequency distributions showed two cohorts in each sample, except from August to November when there were up to three cohorts, with greater variance in those of intermediate sizes. The growth parameters were: L? = 19.06 cm, k = 0.47 year-1, t0 = -0.19 years, C = 0.38, ts = 0.37. Due to fluctuations in the growth of the species, assessments should be performed based on age-structured models to support fishery management measures for this species

La pesquería de la almeja chocolata Megapitaria squalida (Bivalvia: Veneridae) en Baja California Sur, México

The Squalid Callista Megapitaria squalida is one of the most important bivalve fisheries in Baja California Sur. However, there is scarce information about the current state of the fishery. In order to obtain an overview of the fishery development, spatial and temporal catch trends were analyzed. The analysis was based on monthly and by area catches records from 1999 to 2006. Results show six major fishing areas: La Paz Bay, Ojo de Liebre Lagoon, Magdalena Bay, San Ignacio Lagoon, Loreto and Santa Rosalía. In the first three areas it was observed 96% of the total catch. There was a general increase in catches from 1992 (315 t) to 2002 (1,128 t) due to the catch increase in Ojo de Liebre Lagoon and La Paz Bay. However, a substantial catch decline occurred in Magdalena Bay from 2001 (457 t) to 2006 (73 t). Since 2002 there has been a general catch decline. Therefore, the conclusion of the study affirms that the fisheries in La Paz Bay and Ojo de Liebre Lagoon are at their maximum level of exploitation. In Magdalena Bay there is evidence of overfishing, while San Ignacio Lagoon, Loreto and Santa Rosalía could have developing potential. A detailed stock assessment is recommended due to the recent negative catch trends that could indicate an excessive fishing pressure.La almeja chocolata Megapitaria squalida representa una de las pesquerías de bivalvos más importantes en Baja California Sur. Sin embargo, poco se sabe sobre el estado actual de esta pesquería. Con el objetivo de obtener una perspectiva del desarrollo de la pesquería, se analizaron las tendencias espacio-temporales de las capturas, utilizando los registros de producción mensual y por localidad de 1999 a 2006. Los resultados muestran seis regiones de pesca importantes: Bahía de La Paz, Laguna Ojo de Liebre, Bahía Magdalena, Laguna San Ignacio, Bahía de Loreto y la costa de Santa Rosalía. En las tres primeras se obtuvieron 96% de las capturas totales. Se observó un incremento en la producción de 1992 (315 t) a 2002 (1,128 t) debido al aumento en la Laguna Ojo de Liebre y Bahía de La Paz, sin embargo es notable la disminución de las capturas en Bahía Magdalena desde el 2001 (457 t) al 2006 (73 t). A partir de 2002 se observó una disminución general de las capturas. Se concluye que la pesquería en Bahía de La Paz y Laguna Ojo de Liebre se encuentra en su máxima capacidad, en Bahía Magdalena hay indicios de sobreexplotación, mientras que en Laguna San Ignacio, Bahía de Loreto y Santa Rosalía podría haber potencial de desarrollo. Se recomienda profundizar en la evaluación del recurso, debido a que las tendencias de disminución de las capturas observadas en los últimos años, pueden estar indicando una excesiva presión de pesca

Escenarios de la alternancia

Conjunto de reflexiones en torno a los desafíos y perspectivas políticas y sociales que se le presentan a México en el marco de la alternancia política con la llegada de Vicente Fox, del Partido Acción Nacional (PAN) a la Presidencia de la República.ITESO, A.C

Application of Silver Nanoparticles for Water Treatment

In recent past development of silver nanoparticles and their application in the treatment of wastewaters is becoming a major area of research. It is mainly applicable to the removal of three major pollutants like pesticides, heavy metals, and microorganisms. Variety of synthesis techniques have been reported for preparation and characterization of silver nanoparticles. In our research, we synthesized Ag nanoparticles supported on ZrO2 and ZrO2-CeO2 by a “deposit-precipitation method” as the first step and later sequentially synthesized Ag-Au supported on ZrO2 and ZrO2-CeO2 by Redox method. Catalysts were evaluated in catalytic wet air oxidation (CWAO) of methyl tert-butyl ether and phenol. The CWAO is a liquid phase process for the treatment of organic pollutants operating at temperatures in the range of 100–325°C at 5–200 bar pressures. The selectivity and efficient of catalysts were evaluated by total organic carbon (TOC) and high-performance liquid chromatograph (HPLC). Ideally, the total mineralization of pollutants into CO2 and H2O is preferred

Adenylyl Cyclase Plays a Regulatory Role in Development, Stress Resistance and Secondary Metabolism in Fusarium fujikuroi

The ascomycete fungus Fusarium fujikuroi (Gibberella fujikuroi MP-C) produces secondary metabolites of biotechnological interest, such as gibberellins, bikaverin, and carotenoids. Production of these metabolites is regulated by nitrogen availability and, in a specific manner, by other environmental signals, such as light in the case of the carotenoid pathway. A complex regulatory network controlling these processes is recently emerging from the alterations of metabolite production found through the mutation of different regulatory genes. Here we show the effect of the targeted mutation of the acyA gene of F. fujikuroi, coding for adenylyl cyclase. Mutants lacking the catalytic domain of the AcyA protein showed different phenotypic alterations, including reduced growth, enhanced production of unidentified red pigments, reduced production of gibberellins and partially derepressed carotenoid biosynthesis in the dark. The phenotype differs in some aspects from that of similar mutants of the close relatives F. proliferatum and F. verticillioides: contrary to what was observed in these species, ΔacyA mutants of F. fujikuroi showed enhanced sensitivity to oxidative stress (H2O2), but no change in heavy metal resistance or in the ability to colonize tomato tissue, indicating a high versatility in the regulatory roles played by cAMP in this fungal group