A comparative study on the effect of dispersed and undispersed Kuwait crude oil on egg hatching and larval survival of Epinephelus coioides

Aim: The objective of the present study was to investigate the effects of dispersed and undispersed Kuwait crude oil on egg hatching and larval survival of Epinephelus coioides. Methodology: In the present study, the toxic effects of crude and dispersed oil using three formulations of oil dispersants against multiple life stages of Epinephelus coioides was assessed. The lethal concentration was calculated by ToxCal® software developed by Tidepool Scientific, LLC. Results: Specifically, the following life stages were investigated: embryonated eggs (EE), larvae hatched during exposure (LHE) and hatched larvae (HL). Chemical analysis showed that Total Petroleum Hydrocarbon (TPH) concentrations were higher in dispersed than undispersed oil solutions, indicating accommodation of more petroleum hydrocarbons in the aqueous phase. Acute static toxicity tests produced variable LC50 values for all chemical preparations and all fish life stages. Crude oil dispersed with both Corexit® EC 9500A and Corexit® EC 9527A separately was more toxic to both EE and LHE stages than undispersed oil, but crude oil dispersed with Slickgone® NS resulted in lower toxicity. Furthermore, all three types of dispersed oil exerted higher toxicity than undispersed oil at HL stage. Interpretation: A life stage dependent effect demonstrated variation in the toxicity of both dispersed and undispersed crude oil to fish. Few life stages were more sensitive than others to either dispersed or undispersed crude oil toxicity. While dispersion of an oil slick with oil dispersant has proved to be an effective tool in the oil response strategy, the fate of dispersed oil can exert lethal effects on embryo-larval stages of marine fish present near the spill.

Caracterización fenotípica de la cepa N2 de Caenorhabditis elegans como un modelo en enfermedades neurodegenerativas / Phenotypic characterization of the N2 strain of Caenorhabditis elegans as a model in neurodegenerative diseases

Resumen El nematodo C. elegans se estableció desde I960, gracias al biólogo sudafricano Sydney Brenner, como un organismo modelo en investigación. Sus cualidades biológicas permiten mejorar la visión y comprensión de patologías en los seres humanos y otros seres pluricelulares; además, sus fenotipos claros y observables lo convierten en un organismo adecuado para el estudio básico de enfermedades neurodegenerativas, inmunológicas y procesos cancerígenos. Objetivo. Analizar las características fenotípicas de la cepa silvestre N2 de C. elegans para su posterior uso como modelo de tamizaje en el laboratorio de Biotecnología y Genética (Universidad Colegio Mayor de Cundinamarca). Materiales y Métodos. El nematodo fue cultivado y crecido en el medio NGM con la cepa E. coli OP50. La cepa N2 fue sincronizada para obtener huevos y posteriormente larvas L1. Se estandarizaron los ensayos de longevidad, reproducción, longitud y estrés térmico. Resultados. La caracterización fenotípica de la cepa N2 de C. elegans presentó: una longevidad de 16 a 22 días, una reproducción promedio de 225 crías, la longitud del nematodo fue de 1100±50 μm y la supervivencia bajo estrés térmico evaluada en las dos etapas de desarrollo del nematodo es muy reducida a 37°C en comparación de 35°C; además, los nematodos fueron más resistentes al primer día de adulto joven en comparación con el sexto día de adulto. Conclusiones. Los resultados aportados por este estudio permiten sugerir que las características fenotípicas del nematodo analizadas se encuentran dentro de lo reportado en la literatura, por lo cual es viable usarlo como como modelo biológico en diferentes ensayos tal como lo reportan otros estudios.

Abstract The nematode C. elegans was established since I960, thanks to the South African biologist Sydney Brenner, as a model organism in research. Their biological qualities allow to improve the vision and understanding of pathologies in human and other multicellular beings; In addition, its clear and observable phenotypes make it a suitable organism for the basic study of neurodegenerative, immunological diseases and carcinogenic processes. Objective. To analyze the phenotypic characteristics of the C. elegans N2 wild strain for later use as a screening model in the Biotechnology and Genetics Laboratory (Colegio Mayor de Cundinamarca University). Materials and Methods. The nematode was grown and grown in the NGM medium with the strain E. coli OP50. The N2 strain was synchronized to obtain eggs and later L1 larvae. The tests of longevity, reproduction, length and thermal stress were standardized. Results. The phenotypic characterization of the N2 strain of C. elegans presented a longevity of 16 to 22 days, an average reproduction of 225 offspring, the length of the nematode was 1100 ± 50 μm and the survival under thermal stress evaluated in the two Development stages of the nematode is greatly reduced at 37 ° C compared to 35 ° C; In addition, nematodes were more resistant to the first day of young adult compared to the sixth day of adulthood. Conclusions. The results of this study suggest that the phenotypic characteristics of the nematode analyzed are within the literature, so it is feasible to use it as a biological model in different trials as reported in other studies.

Cercariae (Digenea: Strigeidae, Diplostomidae) in Biomphalaria straminea (Planorbidae) from a rice field in Northeastern Argentina / Cercarias (Orden: Strigeidae, Diplostomidae) en Biomphalaria straminea (Planorbidae) de un campo de arroz en el Nordeste Argentino

AbstractThe rice fields can provide habitats for many species of aquatic invertebrates, as insects, molluscs, crustaceans; and vertebrates, as fish, amphibians, reptiles and birds, which may act as hosts in the life cycles of digenean parasites. In this context, the goal of the present study was to describe the cercariae found in Biomphalaria straminea from a rice field in Northeastern Argentina. This freshwater snail inhabits a wide variety of environments, favoring shallow, temporary and standing or slow-flowing freshwater bodies. For this study, snails were collected from the cultivated parcels and irrigated channels during the flooding periods (from the time of sowing to soon after harvesting of the rice) between December 2010 and May 2011 and December 2011 and April 2012, in a rice field from Corrientes province, one of the main rice producers of Argentina. A total of 5 510 snails were examined of which 26 were infected with three different larval trematodes belonging to Strigeidae, Furcocercaria V (0.40 %) and Furcocercaria XX (0.04 %), and Diplostomidae, Furcocercaria XIX (0.04 %). Furcocercaria XX and Furcocercaria XIX were present in one rice cultivation cycle, while Furcocercaria V was present in both rice cultivation cycles. The prevalence of the different furcocercariae was somewhat higher in the second rice cultivation cycle. The cercariae described are new records for Argentina that added to 53 cercariae previously reported for Biomphalaria spp. in different aquatic environments of country. The study of the digenean larval in rice fields is important because contribute to the knowledge of the biodiversity of these environments.

ResumenLos campos de arroz pueden proporcionar hábitats para muchas especies de invertebrados acuáticos, como insectos, moluscos, crustáceos; y vertebrados, como peces, anfibios, reptiles y aves, los cuales pueden actuar como hospedadores en los ciclos de vida de los parásitos digeneos. En este contexto, el objetivo del presente estudio fue describir las cercarias encontradas en Biomphalaria straminea de un campo de arroz en el Nordeste Argentino. Este caracol de agua dulce habita una amplia variedad de ambientes, principalmente cuerpos de agua superficiales, estancados o de flujo lento. Para este estudio, los caracoles fueron recolectados de las parcelas cultivadas y los canales de riego durante los periodos de inundación (desde la siembra hasta poco después de la cosecha del arroz) entre diciembre 2010 y Mayo 2011 y Diciembre 2011 y Abril 2012, en un campo de arroz de la provincia de Corrientes, una de las principales productoras de arroz de Argentina. Un total de 5 510 caracoles fueron examinados de los cuales 26 estuvieron infectados con tres trematodes larvales pertenecientes a Strigeidae, Furcocercaria V (0.40 %) y Furcocercaria XX (0.04 %), y Diplostomidae, Furcocercaria XIX (0.04 %). Furcocercaria XX y Furcocercaria XIX estuvieron presentes en un ciclo de cultivo de arroz, mientras que Furcocercaria V estuvo presente en ambos ciclos de cultivo. La prevalencia de las diferentes furcocercarias fue algo mayor en el segundo ciclo de cultivo de arroz. Las cercarias descritas son nuevos registros para Argentina que se adicionan a las 53 cercarias previamente registradas para Biomphalaria spp. en diferentes ambientes acuáticos del país. El estudio de digeneos larvales en los campos de arroz es importante porque contribuye al conocimiento de la biodiversidad en estos ambientes.

Oestrus ovis infection of grazing sheep during summer in southern Chile

Oestrus ovis is a botfly whose larvae cause nasal myiasis, an environmental-dependent disease in small ruminants, generating acute and chronic injuries in the cranial cavities of sheep. Chile is a country of the southernmost worldwide distribution of this parasite, and there is few information about. Whence, the objective of this study was to approximate the epidemiological situation of O. ovis infection in Chilean sheep. From December 2009 to March 2010, a total of 87 samples were obtained by necropsy for skull inspection. The larvae were collected, and microscopically identified. The prevalence in the sampled sheep was 60.9%. From those that were infected, 85.7% (18/21) of sheep were 1 to 3 years old, constituting the stratum with the highest prevalence. The difference of infection in females and males was not significant. The high risk of infection seems to be dependent upon the environmental conditions of this southern region, especially during summer when the first larval stage (L1) could be found as the evidence. Therefore, the disease should be considered as a significant problem for this kind of livestock production.

Desarrollo embrionario y larva del sapo Incilius aucoinae (Bufonidae) en Golfito, Costa Rica / Embryonic development and larva of the toad Incilius aucoinae (Bufonidae) in Golfito, Costa Rica

Embryonic development and larva of the toad Incilius aucoinae (Bufonidae) in Golfito, Costa Rica. The larva and developmental stages of Incilius aucoinae are described using specimens from Río Cañaza, Golfito, Costa Rica. We collected the individuals in January 1997, and January and February 1998. The total sample was 696 individuals, 317 eggs in 1-12 stages, 176 eggs with embryos in stages 15-16, and 204 tadpoles in stages 21-43. The average number of eggs per nest was 8 940 (n = 4). These eggs were laid in strings, attached to the river strata. Eggs in stages 1-12 had an average diameter of 1.75 (s = 0.38) mm and eggs with embryos in stages 15 -16 measured 1.33 (0.34) mm wide and 3.06 (1.46) mm long. The description of the tadpole based on UCR 19982 is as follows: dorsal, ventral surfaces, and tail are brown with dark brown spots. Length of tail 9.43 mm, body length 6.18 mm (total length 15.62). Translucent light brown small fins, dorsal fin with scattered spots, ventral fin without dark pigments. Dorsal-ventral flattened oval body with anteroventral snout. A few individuals had varied colors, from black (3.4%) to uniform (0.5-1.5%). Rev. Biol. Trop. 57 (Suppl. 1): 291-299. Epub 2009 November 30.

Se describe la larva y los estadios del desarrollo del huevo y larva de Incilius aucoinae utilizando especímenes del río Cañaza, Golfito, Costa Rica, recolectados en enero de 1997 y enero-febrero de 1998. La muestra fue de 696 individuos, 317 huevos en estadios 1-12, 176 huevos con embriones en estadios 15-16, y 204 renacuajos en estadios 21-43. El promedio del número de huevos por nidada fue de 8 940 (n = 4), los cuales fueron colocados en una hilera, sujetos al sustrato del río. Los huevos en estadios 1-12 tienen un promedio de diámetro de 1.75 (s = 0.38) mm y los huevos con embriones en estadios 15-16 miden 1.33 (0.34) de ancho y 3.06 (1.46) mm de largo. La descripción del renacuajo basada en el espécimen UCR 19982, es como sigue: el dorso, el vientre y la cola son de color café y punteado de café oscuro; la cola mide 9.43 mm y el cuerpo 6.18, para un tamaño total de 15.62; las aletas son pequeñas café claro translúcidas, la dorsal con puntos dispersos y la ventral sin ningún tipo de pigmento oscuro. También es el único renacuajo ovoide con una tendencia a ser aplastado dorso-ventralmente, y con la boca antero-ventral. Dentro de la variación observada, algunos individuos son de color negro (3.4 %) y pocos son uniformes (0.5- 1.5 %).