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The oceans have absorbed more than 40% of the carbon dioxide (CO2) generated by anthropogenic activities, causing a decrease in the average pH of 0.1 units in seawater since preindustrial times. This phenomenon has been called "ocean acidification." This change poses serious threats to the cultivation of oysters and especially to larval and spat production, activities carried out in coastal and estuarine areas, where pH levels are currently below the IPCC scenario for the year 2100 of pH = 7.8. The goal of the present work was to experimentally evaluate the effect of simulated acidification (pH 7.39 ± 0.04) on the culture in a short-term trial of Kumamoto oyster larvae Crassostrea sikamea taking the current ocean pH conditions (pH 8.116 ± 0.023) as a reference. The evaluation was carried out in an experimental system with continuous water flow and pH manipulation by CO2 bubbling. Veliger larvae (6-day-old postspawn) were cultured at a density of six larvae mL–1 and fed with a monoalgal diet based on Isochrysis galbana at 30,000 cells mL–1. Mortality (%) and growth (shell length in µm) were evaluated, and damage to larval morphology (determined using scanning electron microscopy) and Ca2+ contents in the shells (%) were quantified by X-ray fluorescence. The results show a high sensitivity of C. sikamea veliger larvae to low pH levels with negative impacts on growth and survival, decreases in the Ca2+ concentrations of the shells, and the presence of morphological anomalies during the prodissoconch I stage, which were observed after the first 24 h of cultivation in experimental conditions and became progressively more evident, especially by the sixth day of culture. Acute exposure to a low pH and a saturation of aragonite (Ωar) <1 caused poor calcification in C. sikamea larvae, causing negative effects on larvae, such as shell lesions during development, smaller larvae, and higher mortality and relation to a control pH. [ABSTRACT FROM AUTHOR]

Cosmoses uno de los géneros monofiléticos más diversos de la tribu Coreopsideae (Asteraceae). El grupo incluye 35 especies y 4 taxa infraespecíficos restringidos al continente americano. El objetivo del presente trabajo fue evaluar la distribución geográfica y la riqueza de Cosmosa través de un sistema de información geográfica (SIG). Se estimó el área de distribución geográfica de los taxa con más de un registro. También se evaluó la riqueza de las especies de Cosmospor región política, provincia geológica y una cuadrícula de 80×80km. Por último, se valoraron los patrones de distribución geográfica por hábito de crecimiento. Se encontraron 3 zonas de alta riqueza, todas en México, en los estados de Jalisco, Durango y México. Las hierbas anuales, las hierbas perennes y los sufrútices mostraron patrones de distribución geográfica diferente. Las hierbas anuales tuvieron la mayor área de distribución. En contraste, las hierbas perennes presentaron mayor cantidad de especies pero una distribución restringida. El Eje Neovolcánico ha sido el escenario de la diversificación de Cosmosy es la poliploidización el principal mecanismo de especiación.

Se caracterizaron y compararon los aparatos estomáticos de 26 especies de Asteraceae de la Reserva Ecológica del Pedregal de San Ángel, con la hipótesis de que las plantas que habitan en la cuenca de México están respondiendo a los incrementos antropogénicos de CO2atmosférico con modificaciones en su aparato estomático. Se llevó a cabo la comparación de hojas aclaradas de ejemplares de herbario recolectados antes de la década de los setenta, con ejemplares recolectados en 2009 y 2010 en la misma zona. Los resultados mostraron que la densidad estomática está relacionada negativamente con la longitud de las células guarda (rs=−0.73, p<0.0001), como ha sido observado en otros grupos taxonómicos. Además, se encontraron diferencias significativas (p<0.05) en los aparatos estomáticos de 13 especies; tanto la disminución de la densidad estomática (5 especies) como su incremento (6 especies) está asociado o no a la disminución o aumento de la longitud de las células guarda. Estas modificaciones asociadas a los incrementos de CO2, siguen las tendencias registradas para otros grupos de plantas. En Artemisia ludoviciana, Bidens odoratay Zinnia peruvianano se detectaron modificaciones en las 2 variables evaluadas. Las respuestas estomáticas a los incrementos antropogénicos de CO2son sumamente variables como lo demuestran los resultados obtenidos para las Asteraceae de la Reserva Ecológica del Pedregal de San Ángel.

Four new modified eremophilanes, angulifolide (1) and angulifolins A-C (2-4), and two new triacetylglucosides (7and 8) were isolated from Roldana angulifolia, together with several known compounds. The structures of the new compounds were elucidated by spectroscopic analysis and chemical reactions. The absolute configuration of compounds 2and 3was established by Mosher ester methodology. Cytotoxicity against selected human cancer cell lines was determined for the more abundant isolated metabolites.

Eight new eremophilanolides (1, 2, 4−7, 9, and 10), a new eremophilane (13), and several known compounds were isolated from the roots and aerial parts of Senecio mairetianus. The chemical structures were proposed taking into consideration spectroscopic analyses and chemical transformations. X-ray diffraction analysis of 2, 4, and 9confirmed their structures. The stereochemistry of 1,10-epoxy-8-methoxyermophilanolide (3) was determined. Compounds 4−7, 9, and 10are possible artifacts obtained by preparation of the alkaloidal extract.

This study compared the transcriptional changes in Nicotiana benthamianaplants treated with homologous sequences derived from Pepper golden mosaic virus(PepGMV) and heterologous sequences that derived from another begomovirus, Tomato chino La Paz virus(ToChLPV) prior to infection by PepGMV. The results of microarray analyses identified upregulated genes associated with RNAi such as DCL2, DCL4, AGO3, AGO7, AGO10, NRPD2B (Pol IV), DRB3, CMT3, RDR6. The components that participate in different RNAi pathways were identified, including methylation induced by both constructs, as well as the code of these genes in Arabidopsis thalianaand its counterpart in N. benthamianathrough different genome assembly. The expression of these genes was validated by quantitative reverse transcription polymerase chain reaction (RT-qPCR), where DCL3, DCL4, AGO1-1, AGO2, RDR6 and PPR1 showed increased expression during plant protection with the heterologous construct compared to those protected with the homologous construct. The results of this study confirmed the activation of the gene silencing mechanism at the transcriptional level with both constructs and established the possibility of their use as a protection system for both homologous and heterologous sequences.

Six 1.2-m3tanks were stocked with an initial biomass of 500 g m-3of Litopenaeus vannameijuveniles (individual weight: 1.0±0.3 g), to evaluate the effect of biofloc promotion on water quality and on shrimp growth and production, and to identify the dominant taxa in the heterotrophic communities present in experimental closed cultures. Feeding was ad libitumtwice daily with 35% protein shrimp feed. Three tanks were managed as biofloc technology (BFT) systems, adding daily an amount of cornmeal equivalent to 50% of the shrimp feed supplied. The remaining three received only shrimp feed and served as controls. Experiment lasted 21 days. The mean concentrations of P-PO43-and inorganic dissolved N species (TAN, N-NO2-, N-NO3-) were significantly lower (P<0.5) in BFT than in the control. The individual final weight, increase in biomass, food, and protein conversion rates were significantly better in BFT than in the control (P<0.05). The mean N content of the shrimp biomass gained in the BFT cultures was equivalent to 45.7% of the protein-N added as feed, and was significantly higher than the 34.7% recycled into shrimp biomass in the control cultures. Bacterial concentrations were not significantly different. Vibrionaceae dominated in both systems; in both some isolates were potential pathogens, and diversity was higher in the control than in the BFT treatment. The advantages of BFT technology are confirmed by the significantly lower TAN and N-NO2-concentrations, as well as by the better shrimp performance in terms of growth, biomass yield, and food and protein conversion efficiency.