Draft genome sequence of Vibrio lentus VLO8, recovered from the larval culture of the Chilean scallop (Argopecten purpuratus).

This announcement reports the genome of Vibrio lentus VLO8 recovered from the larval culture of Chilean scallop. The genomes of strain VLO8 have two contigs with a total length of 5,499,980 bp, an average G + C content of 44.22%, a total number of protein-coding genes of 6,439, and 170 RNAs.

First Report, Characterization and Pathogenicity of Vibrio chagasii Isolated from Diseased Reared Larvae of Chilean Scallop, Argopecten purpuratus (Lamarck, 1819).

Two Vibrio strains (VPAP36 and VPAP40) were isolated from moribund-settled larvae of the Chilean scallop Argopecten purpuratus during vibriosis outbreaks that occurred in two commercial scallop larvae hatcheries located in the Inglesa and Tongoy bays in Northern Chile. The strains were identified as Vibrio chagasii using phenotypic characterization and whole genome sequence analysis. Both strains exhibited the phenotypic properties associated with virulence, gelatin hydrolysis and ß-hemolysis, whereas only VPAP36 produced phospholipase and only VPAP40 produced caseinase. The whole genome analysis showed that the strains harbored genes encoding for the virulence factors, the EPS type II secretion system, and Quorum Sensing (auto-inductor 1 and auto-inductor 2), whereas genes encoding a metalloproteinase and a capsular polysaccharide were detected only in the VPAP40 genome. When challenge bioassays using healthy 11-day-old scallop larvae were performed, the V. chagasii VPAP36 and VPAP40 strains exhibited significant (p < 0.05) differences in their larval lethal activity, producing, after 48 h, larval mortalities of 65.51 ± 4.40% and 28.56 ± 5.35%, respectively. Otherwise, the cell-free extracellular products of the VPAP36 and VPAP40 strains produced larval mortalities of 20.86 ± 2.40% and 18.37 ± 2.40%, respectively, after 48 h of exposure. This study reports for the first time the isolation of V. chagasii from the massive larval mortalities of the farmed scallop (Argopecten purpuratus) in Chile, and demonstrates the pathogenic activity of V. chagasii towards the Chilean scallop, the second most important species for Chilean mariculture.

Immune response of the Antarctic sea urchin Sterechinus neumayeri: cellular, molecular and physiological approach / Respuesta inmune del erizo de mar Antártico Sterechinus neumayeri: un enfoque celular, molecular y fisiológico

Abstract In the Antarctic marine environment, the water temperature is usually between 2 and - 1.9 °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 °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. Rev. Biol. Trop. 63 (Suppl. 2): 309-320. Epub 2015 June 01.

Resumen 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.