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

1. Introduction
Solea senegalensis (Kaup, 1858) is one of the new candidate species for
aquaculture in the Portuguese and Spanish coasts [1]. One of the main limiting factors
in its production is pseudotuberculosis, due to the bacterial pathogen Photobacterium
damselae subsp. piscicida [2-4]. There are several means of protection against this
microorganism, including antibiotherapy, although the use of antibiotics leads to the
appearance of resistant strains [5]. Vaccination is another option which has been
demonstrated effective protection against pseudotuberculosis in sole [4].
Since immunostimulants mainly facilitate the function of phagocytic cells and
increase their bactericidal activities, it may be possible that immunostimulants
administration to fish increase the respiratory burst activity of the phagocytes and
enhance the protection against pseudotuberculosis. Several authors have reported that P.
damselae subsp. piscicida has the ability to survive as an intracellular pathogen [6-10].
The search for new immunostimulant agents is mainly due to the great development of
fish farming and the stress situations and diseases, which arise from intensive culture
[11].
Several polysaccharides, such as chitin, chitosan and β-glucans obtained from
crustaceans and yeasts have been used in fish and shellfish as immunostimulants [11-
18]. Due to their content in polysaccharides, algae could be an alternative source to
obtain polysaccharides easily. Polysaccharides from Spirulina platensis and Chlorella
have been demonstrated their immunomodulating capacity in mammalian models [19-
21]. However, few studies have been focused on the immunostimulant properties of
algal polysaccharides in farmed fish [22, 23, 24]. The red microalga Porphyridium
cruentum excrete a sulphurized polysaccharide, commercially used in the industry as
thickener, stabilizer and emulsifier for its gelling properties [25-28]. This
polysaccharide is an acidic heteropolymer composed of xylose, glucose, galactose and
sulphate esters [29]. In a previous study, Morris et al. [30] suggested a possible
stimulation of the metabolic and functional action of phagocytic cells of Balb/c mice
after an intraperitoneal administration of polysaccharides isolated from cultures of P.
cruentum in stationary phase.
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