Growth and antioxidant response of juvenile oysters Crassostrea sikamea and Crassostrea corteziensis treated with Streptomyces strains / Crescimento e resposta oxidative de ostras jovens Crassostrea sikamea e Crassostrea corteziensis tratadas com cultura Streptomyces

The effect of three Streptomyces strains (N7, RL8 and V4) and a mixture of Bacillus (BMix) on the growth (Weight, Size) and superoxide dismutase activity (SOD) in hatchery-reared juvenile oysters Crassostrea corteziensis and Crassostrea sikamea was investigated to determine their probiotic potential. Microorganisms were added to culture water at 1×106 CFU/ml once a day during 30 days and all oysters fed daily a microalgae mix. Juveniles of C. sikamea treated with strains N7, RL8 and V4 had a significant weight gain compared to the control group. C. corteziensis juveniles treated with strains RL8 and BMix showed a significantly higher weight gain than the control group. No significant size increase was observed in any treated group for both oyster species. SOD activity significantly increased in C. sikamea treated with RL8 and with RL8, N7 and BMix in C. corteziensis. Streptomyces strains RL8 and N7 emerge as promising probiotic agents to cultivate C. sikamea and C. corteziensis and may also be useful to other molluscs and marine invertebrates .(AU)

O efeito de três culturas Streptomyces (N7, RL8 e V4) e uma mistura de Bacillus (BMix) sobre o cresimento (Peso, Tamanho) e atividade superóxido dismutase (SOD) em ostras jovens Crassostrea corteziensis e Crassostrea sikamea cultivadas artificalmente foi investigado para determinar seu potencial probiótico. Microorganismos foram adicionados à água de cultura a 1×10 6 CFU/ml uma vez por dia durante 30 dias e todas as ostras foram alimentadas diariamente com uma mistura de microalgas. Jovens C. sikamea tratados com culturas N7, RL8 e V4 tiveram ganho de peso significativo quando comparado ao grupo de controle. Jovens C. corteziensis tratados com culturas RL8 e BMix demonstraram peso significativamente mais algo que o grupo de controle. Nenhum aumento em tamanho foi observado em grupos tratados em ambas espécies. A atividade SOD foi significamente aumentada em C. sikamea treatado com RL8 e com RL8, N7 e BMix em C. corteziensis. Culturas Streptomyces RL8 e N7 surgem como agentes probióticos promissores para o cultivo de C. sikamea e C. corteziensis e podem ser úteis para outros moluscos animais marinhos invertebrados.(AU)

Gold nanoparticles (AuNP) exert immunostimulatory and protective effects in shrimp (Litopenaeus vannamei) against Vibrio parahaemolyticus.

Gold nanoparticles (AuNP) stimulate immune responses in mammals but they have not been tested in species of relevance in aquaculture. In this study the immunostimulant and protective potential of orally administered AuNP against V. parahaemolyticus, the causative agent of Acute Hepatopancreatic Necrosis Disease, was determined in shrimp. Synthetized AuNP (18.57 ±â€¯4.37 nm) were moderately dispersed with a negative ζ potential of -10.3 ±â€¯0.208 mV (pH = 7). AuNP were administered (single dose) at 0.2, 2, and 20 µg/g feed in shrimp. Hemolymph samples were withdrawn daily for 6 days. Hemolymph or hemocytes were used to determine total hemocyte counts, immune-related enzymatic activities, and expression of immune-relevant genes. Hepatopancreas was sampled for the analysis of AuNP biodistribution and histological examination. Survival was recorded daily. No mortality or toxicity signs in hepatopancreas were found. AuNP were detected in hepatopancreas. Early (24-48 h) immunostimulation was mainly related to immune gene up-regulation. Upon a challenge with V. parahaemolyticus, survival was higher (80%) and histopathological damages were lower in shrimp treated with the 2 µg/g dose when compared to the control. Therefore orally administered AuNP are proposed as immunostimulants that protect shrimp against V. parahaemolyticus infection.

Sexual comparisons in immune ability, survival and parasite intensity in two damselfly species.

Recent evolutionary studies have suggested that females have a more robust immune system than males. Using two damselfly species (Hetaerina americana and Argia tezpi), we tested if females produced higher immune responses (as phenoloxidase and hydrolytic enzymes), had a higher survival (using a nylon implant inserted in the abdomen and measuring survival after 24h) and fewer parasites (gregarines and water mites) than males. We also tested whether immune differences should emerge in different body areas (thorax vs. abdomen) within each sex with the prediction that only females will differ with the abdomen having a higher immune response than their thorax since the former area, for ecological and physiological reasons, may be a target zone for increased immune investment. Animals were adults of approximately the same age. In both species, females were more immunocompetent than males, but only in H. americana females were immune responses greater in the abdomen than in the thorax. However, there were no differences in survival and parasite intensity or the probability of being parasitised between the sexes in either of the two species. Thus, this study lends partial support to the principle that females are better at defending than males despite the null difference in parasitism and survival.

Superoxide dismutase as modulator of immune function in American white shrimp (Litopenaeus vannamei).

The immunomodulatory action of superoxide dismutase (SOD) and its possible use as an indicator of immune responses in American white shrimp (Litopenaeus vannamei) were studied. Juvenile shrimp were immersed in aerated beta-glucan and sulfated polysaccharide solutions for 6 h. SOD activity in haemocytes and muscle was quantified to evaluate whether beta-glucan and sulfated polysaccharide induce immunostimulatory activity. Haemocytes and muscle showed similar increased levels of SOD activity (1.5- and 1.4-fold that of control, respectively). Total haemocyte count decreased within the first 24 h after challenge with immunostimulants, but total haemocyte count and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulfated polysaccharide is sufficient to generate an increase in the antioxidant activity of L. vannamei SOD.

Generation of superoxide anion and SOD activity in haemocytes and muscle of American white shrimp (Litopenaeus vannamei) as a response to beta-glucan and sulphated polysaccharide.

Juvenile American white shrimp (Litopenaeus vannamei) were immersed in aerated beta-glucan and sulphated polysaccharide solutions for 1, 3 and 6 h. Superoxide anion and SOD activity in haemocytes and muscle were investigated to evaluate whether beta-glucan and sulphated polysaccharide induce any immunostimulatory activity. Haemocytes and muscle showed different levels of superoxide anion generation and SOD activity (2.0 and 14 times that of control, respectively) when shrimp were immersed for 6 h in aerated sea water containing beta-glucan and sulphated polysaccharide. Total haemocyte count (THC) decreased within the first 24 h after challenge with immunostimulants, but THC and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulphated polysaccharide is capable of generating an increase in the respiratory burst of L. vannamei haemocytes.