Ángel I. Campa-Córdova

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.

Superoxide dismutase activity in juvenile Litopenaeus vannamei and Nodipecten subnodosus exposed to the toxic dinoflagellate Prorocentrum lima

The toxic effect of the dinoflagellate Prorocentrum lima on juvenile American whiteleg shrimp Litopenaeus vannamei and giant lion-paw scallop Nodipecten subnodosus was evaluated. Organisms were exposed to three densities (500, 2000, or 5000 cells mL(-1)), superoxide dismutase activity and soluble protein in the hepatopancreas and muscle were determined at 1, 6, 24 and 48 h after challenge. Shrimp exposed at 5000 cells mL(-1) significantly increased SOD activity in the hepatopancreas at 1 h post-challenge, whereas enzymatic activity in muscle significantly increased at 24 h at all densities. Scallops exposed to 500 and 2000 cells mL(-1) showed significant SOD activity increase in hepatopancreas at 24 and 12 h, respectively. Mortality at 48 h was 100% in scallops exposed to 5000 cells mL(-1). Shrimp showed higher levels of SOD activity than scallops. Soluble protein content in the shrimp hepatopancreas was significantly higher at densities of 500 and 2000 cells mL(-1) at 6 and 1 h, respectively. Soluble protein content in the scallop hepatopancreas was higher than control values at 1 h after challenge. In this study, 500 cells mL(-1) was enough to trigger SOD activity in two benthic species exposed to the toxic dinoflagellate P. lima.

The use of probiotics in aquatic organisms: A review

The production of aquatic organisms for human consumption has been decreasing while its demand has increased. The decline of fish products from fisheries has been in part compensated by the aquaculture industry. The need for enhanced disease resistance, feed efficiency, growth performance and lower production costs of cultured organisms is substantial for various sectors of this industry. Different products have been used at some extent to prevent disease and as growth promoters; however, their inadequate application can create adverse disorders, environmental imbalances, and increase predisposition to disease. In the search of new disease control and prevention options, several studies have been carried out to test some functional additives (probiotics). Probiotics have been shown to improve energy expenditure derived from sources such as carbohydrates and increase the incorporation of protein for growth; and to increase the immunity and disease resistance of the host. The use of probiotics in aquaculture has high potential application at a commercial level; however, it has been poorly characterized and studied. This study aims to review the use and action of probiotics in the culture of aquatic organisms (bivalve, fish, shrimp); and the potential for further application of this in aquaculture production.

Isolation and in vitro selection of actinomycetes strains as potential probiotics for aquaculture.

Aim: This study was designed to describe a series of in vitro tests that may aid the discovery of probiotic strains from actinomycetes. Materials and Methods: Actinomycetes were isolated from marine sediments using four different isolation media, followed by antimicrobial activity and toxicity assessment by the agar diffusion method and the hemolysis of human blood cells, respectively. Extracellular enzymatic production was monitored by the hydrolysis of proteins, lipids and carbohydrates. Tolerance to different pH values and salt concentrations was also determined, followed by hydrophobicity analysis and genetic identification of the most promising strains. Results: Five out of 31 isolated strains showed antimicrobial activity against three Vibrio species. Three non-hemolytic strains (N7, RL8 and V4) among these active isolates yielded positive results in hydrophobicity tests and exhibited good growth at salt concentrations ranging from 0% to 10%, except strain RL8, which required a salt concentration >0.6%. Although these strains did not grow at pH<3, they showed different enzymatic activities. Phylogenetic analysis revealed that strains N7 and V4 have more than 99% identity with several Streptomyces species, whereas the closest matches to strain RL8 are Streptomyces panacagri and Streptomyces flocculus, with 98% and 98.2% similarity, respectively. Conclusion: Three actinomycetes strains showing probiotic-like properties were discovered using several in vitro tests that can be easily implemented in different institutions around the world.

Antioxidant screening and phenolic content of ethanol extracts of selected Baja California Peninsula macroalgae

The Baja California Peninsula in México has about 670 species of macroalgae along its coast. Species richness increases the probability of finding native macroalgae with potential as sources of bioactive compounds suitable for health, pharmacological, and cosmetic ingredients. To understand the biotechnological value of macroalgae from the peninsula, ethanol extracts from 17 macroalgae (four Chlorophyta, six Rhodophyta, seven Ochrophyta) were screened for antioxidant potential. To determine the antioxidant capacity of macroalgal extracts, 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power, and nitric oxide radical scavenging as well as total phenolic content (TPC) were measured. Extracts of the brown macroalgae were most active. Among these, Eisenia arborea, Padina concrecens, and Cystoseira osmundacea had the highest TPC and exhibited the strongest radical scavenging activities. Correlations were found between TPC macroalgal and scavenging capacity, indicating an important role of polyphenols as antioxidants. This suggests that some brown macroalgae from Baja California Peninsula may be a good source of natural bioactive compounds.

Toxicity of Cultured Bullseye Puffer Fish Sphoeroides annulatus

The toxin content in various life cycle stages of tank-cultivated bullseye puffer (Sphoeroides annulatus) were analyzed by mouse bioassay and ESI-MS spectrometry analysis. The presence of toxin content was determined in extracts of sperm, eggs, embryo, larvae, post-larvae, juvenile, pre-adult, and adult fish, as well as in food items used during the cultivation of the species. Our findings show that only the muscle of juveniles, the viscera of pre-adults, and muscle, liver, and gonad of adult specimens were slightly toxic (<1 mouse unit). Thus, cultivated S. annulatus, as occurs with other cultivated puffer fish species, does not represent a food safety risk to consumers. This is the first report of toxin analysis covering the complete life stages of a puffer fish under controlled conditions.

Immunostimulant effects and potential application of β-glucans derived from marine yeast Debaryomyces hansenii in goat peripheral blood leucocytes

Debaryomyces hansenii has been described to be effective probiotic and immunostimulatory marine yeast in fish. Nonetheless, to the best of our knowledge, it has been not assayed in ruminants. This study attempts to describe the immunostimulatory effects of its β-glucan content through in vitro assays using goat peripheral blood leukocytes at 24 h of stimulation. The structural characterization of yeast glucans by proton nuclear magnetic resonance indicated structures containing (1-6)-branched (1-3)-β-D-glucan. In vitro assays using peripheral blood leukocytes stimulated with β-glucans derived from three D. hansenii strains and zymosan revealed that β-glucans significantly increased cell immune parameters, such as phagocytic ability, reactive oxygen species production (respiratory burst), peroxidase activity and nitric oxide production. Antioxidant enzymes revealed an increase in superoxide dismutase and catalase activities in leukocytes stimulated with yeast β-glucans. This study revealed that yeast β-glucans were able to activate dectin-1 mRNA gene expression in leukocytes. The TLR4 gene expression was up-regulated in leukocytes after stimulation with yeast β-glucans. In conclusion, β-glucans were able to modulate the immune system by promoting cell viability, phagocytic activity, antioxidant immune response and immune-related gene expression in leukocytes. Therefore, β-glucans derived from Debaryomyces hansenii should be considered a potential immunostimulant for goat production systems.

Digestive enzymes of the Californian two-spot octopus, Octopus bimaculoides (Pickford and McConnaughey, 1949)

Octopus bimaculoides is an important commercially fished species in the California Peninsula with aquaculture potential; however, to date limited information is available regarding its digestive physiology. The objective of this study was focused on biochemically characterizing the main enzymes involved in the digestion of O. bimaculoides. Optimum pH, temperature and thermostability were determined for amylases, lipases, trypsin and chymotrypsin; optimum pH and protease inhibitor effect were assessed for acidic and alkaline proteases, and the effect of divalent ions on trypsin and chymotrypsin activity was evaluated in enzymatic extracts from the digestive (DG) and salivary glands (SG) and crop gastric juices (GJ). High amylase activity was detected in GD and GJ whereas this activity is very low in other cephalopods. Salivary glands had the greatest activity in most of the enzyme groups, showing the importance of this organ in digestion. Optimum pH was different depending on the organ and enzyme analyzed. The optimum pH in DG was 3 showing the predominance of acidic proteases in the digestion process. All enzymes were resistant and stable at high temperatures in contrast with other marine species. Trypsin and chymotrypsin activity were highly incremented with the presence of Mg2+, Co2+, Cu2+ and Zn2+ in some tissues. The inhibitor assay showed the importance of serine proteases, metalloproteases and aspartic proteases in the digestive process of this species. This study is the first in assessing the main digestive enzymes of O. bimaculoides and in remarking the importance of other digestive enzyme groups besides proteases in octopuses.