Antimicrobial activity of microfungi from maritime Antarctic soil

The search for cold-adapted and cold-active fungi in extreme environments provides the potential for discovering new species and novel bioactive compounds. In this study, soil samples were collected from Deception Island, Wilhelmina Bay (north-west Antarctic Peninsula, Graham Land) and Yankee Bay (Greenwich Island), maritime Antarctica, for the isolation of soil fungi and determination of their antimicrobial activity. The soil-plate method, agar block, disc diffusion and broth micro-dilution assays were applied to characterize the thermal classes and antimicrobial activity of the isolated fungi. A total of 27 isolates of fungi were obtained from 14 soil samples, including 13 Ascomycota, 4 Zygomycota and 10 anamorphic fungi. Cold-active (psychrotolerant) fungi predominated over cold-adapted (psychrophilic) fungi. In the antimicrobial assay, 16 isolates showed substantial inhibitory activity against test bacterial pathogens. Ethyl acetate extracts of 10 competent isolates showed significant inhibition of bacterial pathogens. Antifungal activity was observed in the disc diffusion assay, but not in the agar block assay. Minimum inhibitory, bactericidal and fungicidal concentrations were determined using the broth micro-dilution method, with an average in the range of 0.78-25 mg ml-1 on the test microorganisms. Isolate WHB-sp. 7 showed the best broad spectrum antimicrobial activity, with the potential for biotechnological studies in antibiotic development

Four novel picornaviruses detected in Magellanic Penguins (Spheniscus magellanicus) in Chile

Members of the Picornaviridae family comprise a significant burden on the poultry industry, causing diseases such as gastroenteritis and hepatitis. However, with the advent of metagenomics, a number of picornaviruses have now been revealed in apparently healthy wild birds. In this study, we identified four novel viruses belonging to the family Picornaviridae in healthy Magellanic penguins, a near threatened species. All samples were subsequently screened by RT-PCR for these new viruses, and approximately 20% of the penguins were infected with at least one of these viruses. The viruses were distantly related to members of the genera Hepatovirus, Tremovirus, Gruhelivirus and Crahelvirus. Further, they had more than 60% amino acid divergence from other picornaviruses, and therefore likely constitute novel genera. Our results demonstrate the vast undersampling of wild birds for viruses, and we expect the discovery of numerous avian viruses that are related to hepatoviruses and tremoviruses in the future

Antimicrobial activity of microfungi from maritime Antarctic soil

The search for cold-adapted and cold-active fungi in extreme environments provides the potential for discovering new species and novel bioactive compounds. In this study, soil samples were collected from Deception Island, Wilhelmina Bay (north-west Antarctic Peninsula, Graham Land) and Yankee Bay (Greenwich Island), maritime Antarctica, for the isolation of soil fungi and determination of their antimicrobial activity. The soil-plate method, agar block, disc diffusion and broth micro-dilution assays were applied to characterize the thermal classes and antimicrobial activity of the isolated fungi. A total of 27 isolates of fungi were obtained from 14 soil samples, including 13 Ascomycota, 4 Zygomycota and 10 anamorphic fungi. Cold-active (psychrotolerant) fungi predominated over cold-adapted (psychrophilic) fungi. In the antimicrobial assay, 16 isolates showed substantial inhibitory activity against test bacterial pathogens. Ethyl acetate extracts of 10 competent isolates showed significant inhibition of bacterial pathogens. Antifungal activity was observed in the disc diffusion assay, but not in the agar block assay. Minimum inhibitory, bactericidal and fungicidal concentrations were determined using the broth micro-dilution method, with an average in the range of 0.78-25 mg ml-1 on the test microorganisms. Isolate WHB-sp. 7 showed the best broad spectrum antimicrobial activity, with the potential for biotechnological studies in antibiotic development

Embryonic and larval development is conditioned by water temperature and maternal origin of eggs in the sea urchin Arbacia dufresnii (Echinodermata: Echinoidea)

Introduction: Embryonic and larval development in sea urchins is highly dependent on maternal nutritionalstatus and on the environmental conditions of the seawater. Objective: To compare the development of Arbaciadufresnii in two different water temperatures and in progeny with varying maternal origins. Methods: Weinduced A. dufresnii females and males from Nuevo Gulf to spawn, collected the eggs of each female individually(progeny), separated them into two seawater temperatures (12 and 17 °C), and fertilized them. We recordedthe percentage of fertilized eggs and embryos per developmental stage according to time, temperature andprogeny. We measured larval growth by total length (TL) and midline body length (M) according to time postfecundation (DPF), temperature, and progeny. Results: Temperature did not affect fertilization, but embryodevelopment was faster and more synchronized in the high temperature treatment. The generalized linear modelsindicate that embryo development depends on a quadruple interaction between the embryonic stage, time (h),seawater temperature and progeny. Larval growth was faster, producing larger larvae at the highest temperature.Larval growth depends on a triple interaction between time (DPF), seawater temperature and progeny.Conclusions: We found a temperature and progeny impact during embryonic and larval development and, inboth cases, these factors generate a synergistic effect on developmental timing and larval size. This probablyprovides a survival advantage as a more rapid speed of development implies a decrease in the time spent in thewater column, where the sea urchins are vulnerable to biotic and abiotic stressors.Fil: Fernandez, Jimena Pía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Chaar, Florencia Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Epherra, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Gonzalez Aravena, Jorge Marcelo. Instituto Antartico Chileno; ChileFil: Rubilar Panasiuk, Cynthia Tamara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentin

Sponge richness on algae-dominated rocky reefs in the western Antarctic Peninsula and the Magellan Strait

Sponges are important components of high-latitude benthic communities, but their diversity and abundance in algal-dominated rocky reefs has been underestimated because of the difficulty of in situ identification. Further, the influence of canopy-forming algae on sponge richness has been poorly studied in southern high-latitude rocky reefs compared to other latitudes. Here, we quantified taxon richness of sponges in algae-dominated rocky reefs at three sites in the western Antarctic Peninsula (62–64° S) and two sites in the Magellan region (53° S). We found higher sponge richness at sites in Antarctica (15) than in Magallanes (8), with Antarctic sponge richness higher than that reported for Arctic algal beds and similar to that reported for temperate regions. Estimated sponge richness at our Antarctic sites highlights diverse sponge assemblages (16–26 taxa) between 5 and 20 m that are typically dominated by macroalgae. Our results suggest that sponge assemblages associated with canopy-forming macroalgae on southern high-latitude reefs are more diverse than previously thought

HSP70 from the Antarctic sea urchin Sterechinus neumayeri: molecular characterization and expression in response to heat stress

Background Heat stress proteins are implicated in stabilizing and refolding denatured proteins in vertebrates and invertebrates. Members of the Hsp70 gene family comprise the cognate heat shock protein (Hsc70) and inducible heat shock protein (Hsp70). However, the cDNA sequence and the expression of Hsp70 in the Antarctic sea urchin are unknown. Methods We amplified and cloned a transcript sequence of 1991 bp from the Antarctic sea urchin Sterechinus neumayeri, experimentally exposed to heat stress (5  and 10 °C for 1, 24 and 48 h). RACE-PCR and qPCR were employed to determine Hsp70 gene expression, while western blot and ELISA methods were used to determine protein expression. Results The sequence obtained from S. neumayeri showed high identity with Hsp70 members. Several Hsp70 family features were identified in the deduced amino acid sequence and they indicate that the isolated Hsp70 is related to the cognate heat shock protein type. The corresponding 70 kDa protein, called Sn-Hsp70, was immune detected in the coelomocytes and the digestive tract of S. neumayeri using a monospecific polyclonal antibody. We showed that S. neumayeri do not respond to acute heat stress by up-regulation of Sn-Hsp70 at transcript and protein level. Furthermore, the Sn-Hsp70 protein expression was not induced in the digestive tract. Conclusions Our results provide the first molecular evidence that Sn-Hsp70 is expressed constitutively and is non-induced by heat stress in S. neumayeri

Immune response of the Antarctic sea urchin Sterechinus neumayeri: cellular, molecular and physiological approach

In the Antarctic marine environment, the water temperature is usually between 2 and - 1.9 degrees C. Consequently, some Antarctic species have lost the capacity to adapt to sudden changes in temperature. The study of the immune response in Antarctic sea urchin (Sterechinus neumayeri) could help us understand the future impacts of global warming on endemic animals in the Antarctic Peninsula. In this study, the Antarctic sea urchins were challenged with lipopolysaccharides and Vibrio alginolitycus. The cellular response was evaluated by the number of coelomocytes and phagocytosis. A significant increase was observed in red sphere cells and total coelomocytes in animals exposed to LPS. A significant rise in phagocytosis in animals stimulated by LPS was also evidenced. Moreover, the gene expression of three immune related genes was measured by qPCR, showing a rapid increase in their expression levels. By contrast, these immune genes showed a depression in their expression by a thermal effect at 5 and 10 degrees C. In addition, during bacterial injection, the oxygen consumption was higher in challenged animals. Our results showed that the immune response in the Antarctic sea urchin may be affected by acute thermal stress and that this immune response has a metabolic cost.Respuesta inmune del erizo de mar Antártico Sterechinus neumayeri: un enfoque celular, molecular y fisiológico. En el medio ambiente de la Antártica la temperatura del agua es de entre 2 y - 1.9 °C. Por consecuencia ciertas especies han perdido la capacidad de adaptarse a los cambios repentinos de la temperatura del agua. El estudio de la respuesta inmune del erizo antártico (Sterechinus neumayeri) podría ayudar a comprender los futuros impactos en los animales endémicos del cambio climático en la Península Antártica. En este estudio nosotros hemos evaluado la respuesta inmunitaria de S. neumayeri respecto de estimulaciones con bacterias (Lipopolisacáridos y Vibrio alginolitycus) asi como durante el estrés térmico a 5 y 10 °C. La respuesta del erizo fue evaluada en relación al número de celomocitos circulantes, capacidad fagocítica de estos y por el análisis de la expresión de tres genes inmunitarios. Después de la estimulación con LPS un aumento significativo de células esferoidales rojas, de amebocitos fagocíticos y de celomocitos totales fue observado después de las primeras horas de estimulación, de la misma manera que la capacidad fagocítica. Por otra parte los tres genes inmunes medidos mostraron un aumento significativo de su expresión por qPCR después de la estimulación con LPS. El estrés térmico de 5 °C produjo un aumento de la expresión de estos tres genes inmunitarios, por el contrario a una temperatura más alta (10 °C) se produce la reducción de dos de entre ellos. Adicionalmente un aumento del consumo de oxígeno fue observado durante la estimulación bacteriana. Nuestros resultados muestran que la respuesta inmunitaria en el erizo antártico puede ser afectada por el estrés térmico agudo y que la respuesta inmune en invertebrados antárticos tendría un costo metabólico