Papel de las actividades superóxido dismutasa y catalasa en la ...

INTRODUCTION
salina, is able to modulate, after oral administration, some components of the innate
defence mechanisms in rainbow trout (Oncorhynchus mykiss) such as the complement
alternative way, serum lysozyme and phagocytosis. The carotenoids increase the
phagocytic activity and citoquine production (Bendich, 1989; Chew, 1993).
Algae are also a natural source of vitamins, some of them have possible
immunostimulant effects on fish immune system, such as vitamin C (Hardie et al., 1991;
Cuesta et al., 2002; Jeney and Jeney, 2002; Lin and Shiau, 2005), vitamin E (Hardie et al.,
1990; Cuesta et al., 2001) and vitamins B (Miles et al., 2001).
The use of polysaccharides as immunostimulants is widely extended in aquaculture
(Kumar et al., 2005), the most studied in fish are the glucans. β-glucans are polyglucoses
that consist in series of residues of β-1,3-glucopiranosyl derived from yeast and fungus
micellium. These sugars seem to have a potent immunostimulant effect, mainly on
unspecific defence mechanisms, inducing resistance against infections. Numerous
studies confirm the use of β,1-3,1-6 glucans from yeasts and fungus cell walls as
immunostimulants in aquaculture. Greater part of these studies has focused on β-
glucans from the yeast specie Saccharomyces cerevisiae (Santarém et al., 1997; Castro
et al., 1999; Kumari and Sahoo, 2006; Marqués et al., 2006).
The use of these polysaccharides as immunostimulants in aquaculture industry is
widely extended and there are commercial products available (Siwicki et al., 1994; Cook
et al., 2003; Couso et al., 2003; Bagni et al., 2005).
Another potential immunostimulant polysaccharide derived from brown
macroalgae and microalgae, is the alginic acid. The alginate is known in aquaculture as
stabilizer of the structure of pellet diets. The immunostimulant properties were
determined in phyophaecaetes extracts of species such as Laminaria digitata (Dalmo et
al., 1998; Gabrielsen and Austreng, 1998) and others (Miles et al., 2001; Peddie et al.,
2002; Skjermo and Bergh, 2004; Bagni et al., 2005).
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