Rotifers as Models in Toxicity Screening of Chemicals and Environmental Samples

An important objective of aquatic ecotoxicology is to determine the effects of toxic compounds in organisms that play a central role in aquatic communities where rotifers have a large impact on several important ecological processes. The contribution of the rotifers to secondary production in many aquatic communities is substantial as they are often the larger fraction of zooplankton biomass at certain times of the year. In addition to the importance of their ecological roles in aquatic communities, the rotifers are attractive organisms for ecotoxicological studies by its short life cycles and rapid reproduction, their small size, and little volumes needed for culture and toxicity assays. The main end points used in ecotoxicological studies are mortality, reproduction, behavior, and biomarkers. Such parameters are included in international regulations from all over the world, where different species are used to evaluate the effect of environmental samples or chemical compounds. The high diversity of rotifers is an important issue because it can modify their relative susceptibility to toxicants. Thus, more studies are needed to know the relations and mechanisms involved in clonal variation, sensitivity, and development, which can be all assessed by state-of-the-art procedures

Policultivo del acocil (Procambarus acanthophorus) y tilapia del Nilo (Oreochromis niloticus) como estrategia de uso sustentable del agua

Background. The crayfish Procambarus acanthophorus has a high potential for cultivation; however, it is necessary to evaluate its performance in polyculture with tilapia as a strategy for sustainable production in the rural sector where resources are limited. Goals. Assess the effect of polyculture of the crayfish and tilapia by measuring survival and growth. Methods. Three methods of cultivation with three replicates were evaluated: T1) crayfish monoculture, T2) polyculture crayfish/tilapia and T3) tilapia monoculture. Nine high-density polyethylene tanks (3 m diameter × 1.2 m deep) were used during the trial. The tilapia were fed commercial feed, 32/5% protein / lipids, while the crayfish were given commercial shrimp feed with 35/7% protein / lipids. The productive efficiency of mono- and biculture was determined based on survival feeding efficiency and growth performance. Results. Contrary to what was expected, interspecific competition, space, food availability, and weight gain of crayfish were similar in all treatments, whereas survival was influenced by the treatment, particularly during polyculture, where it was observed that tilapia affected the survival of crayfish. Unlike crayfish, tilapia maintained similar growth and survival in all treatments. Conclusions. The results indicate that polyculture of crayfish/tilapia in a recirculation system is possible and promotes the use of the water column. However, it is necessary to consider the antagonistic effect between species.Antecedentes. Los cangrejos de río Procambarus acanthophorus, tiene un alto potencial de cultivo; sin embargo, es necesario evaluar su desempeño en policultivo con tilapia como estrategia de producción sustentable para el sector rural, donde los recursos son limitados. Objetivos. Evaluar el efecto del policultivo del acocil y la tilapia en la supervivencia y el crecimiento. Métodos. Se evaluaron tres esquemas de cultivo con tres réplicas: T1) monocultivo de acocil, T2) policultivo acocil/; T3) monocultivo de tilapia. Nueve tanques de polietileno de alta densidad (3 m diámetro x 1.2 m profundidad) fueron usados durante el estudio. Las tilapias se alimentaron con alimento comercial con 32/5% proteína/lípidos, mientras que a los acociles se les dio alimento comercial de camarón con 35/7% proteína/lípidos. La eficiencia productiva en el mono- y bicultivo se determinó en base a la supervivencia, eficiencia alimenticia y crecimiento. Resultados. Contrario a lo esperado en relación con la competencia interespecífica, espacio y disponibilidad de alimento, fue similar el peso ganado de los acociles en todos los tratamientos, mientras que su supervivencia estuvo influenciada por los tratamientos, particularmente en el policultivo, en donde se observó que la tilapia afectó la supervivencia de los acociles. A diferencia de los acociles, las tilapias presentaron una supervivencia y crecimiento similar en todos los tratamientos. Conclusiones. Los resultados indican que es posible realizar el policultivo de acocil/tilapia en un sistema de recirculación, lo que promueve el aprovechamiento de la columna de agua, considerando sin embargo el efecto antagónico entre especies

On the description of Brachionus araceliae sp. nov. A new species of freshwater rotifer from Mexico

This contribution describes a new species of Brachionus distinguished of the other species of the genus for the presence of two prominent posterior wing-like structures. These structures were previously recorded in Brachionus bidentatus Anderson 1899 var. ambidentatus De Ridder 1991. However, De Ridder assumed that these structures were induced by an environmental factor and then named it as a variety. This work demonstrates that this rotifer deserves species status based on: 1) the general morphology of the female with six anterior spines with a distinctive pattern different to all known Brachionus bidentatus varieties, and the two prominent posterior wings that represent permanent structures in all females (B. araceliae has been cultivated under constant conditions in the laboratory and the wings have been preserved beyond the fifth generation); 2) the morphology of the male of B. araceliae is different of that of the B. bidentatus male

La plaza pública

1 archivo PDF (269 páginas) : incluye ilustraciones"El interés central de la publicación radica en discutir sobre la crisis de la “ciudad” o de la “urbanidad” que se manifiesta con más fuerza en el espacio público, ya que actualmente existen formas que obstaculizan el contacto; esto es, la relación entre personas y entre actividades dentro del espacio urbano. Algunos autores han insinuado que el espacio público está condenado a la irrelevancia, de manera que incluso plantean la existencia de los llamados “no lugares” que no están vinculados a algún sitio específico. ...

Margarita de Sossa, Sixteenth-Century Puebla de los Ángeles, New Spain (Mexico)

Margarita de Sossa’s freedom journey was defiant and entrepreneurial. In her early twenties, still enslaved in Portugal, she took possession of her body; after refusing to endure her owner’s sexual demands, he sold her, and she was transported to Mexico. There, she purchased her freedom with money earned as a healer and then conducted an enviable business as an innkeeper. Sossa’s biography provides striking insights into how she conceptualized freedom in terms that included – but was not limited to – legal manumission. Her transatlantic biography offers a rare insight into the life of a free black woman (and former slave) in late sixteenth-century Puebla, who sought to establish various degrees of freedom for herself. Whether she was refusing to acquiesce to an abusive owner, embracing entrepreneurship, marrying, purchasing her own slave property, or later using the courts to petition for divorce. Sossa continued to advocate on her own behalf. Her biography shows that obtaining legal manumission was not always equivalent to independence and autonomy, particularly if married to an abusive husband, or if financial successes inspired the envy of neighbors

Reduced expression of exocytotic proteins caused by anti-cholinesterase pesticides in Brachionus calyciflorus (Rotifera: Monogononta)

AbstractThe organophosphate and carbamate pesticides methyl-parathion and carbaryl have a common action mechanism: they inhibit acetylcholinesterase enzyme by blocking the transmission of nerve impulses. However, they can alter the expression of exocytotic membrane proteins (SNARE), by modifying release of neurotransmitters and other substances. This study evaluated the adverse effects of the pesticides methyl-parathion and carbaryl on expression of SNARE proteins: Syntaxin-1, Syntaxin-4 and SNAP-23 in freshwater rotifer Brachionus calyciflorus. Protein expression of these three proteins was analyzed before and after exposure to these two pesticides by Western Blot. The expression of Syntaxin-1, Syntaxin-4 and SNAP-23 proteins in B. calyciflorussignificantly decreases with increasing concentration of either pesticides. This suggests that organophosphates and carbamates have adverse effects on expression of membrane proteins of exocytosis by altering the recognition, docking and fusion of presynaptic and vesicular membranes involved in exocytosis of neurotransmitters. Our results demonstrate that the neurotoxic effect of anticholinesterase pesticides influences the interaction of syntaxins and SNAP-25 and the proper assembly of the SNARE complex