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observed for trypsin in Senegalese sole Solea senegalensis (Martinez et al. 1999). During
the development of the carp ( Cirrhinus mrigala ), variations in digestive enzyme activities
(amylase, protease, trypsin, chymotrypsin, lipase) were also detected in the course of
ontogenesis (Chakrabarti and Rathore 2010). It appears that in the case of Betta splendens
(Siamese fighting fish), acid proteases play a major role throughout the early life stages
(10 days), whereas alkaline proteases take over in the later stages (Thongprajukaew et
al. 2010).
Age-related modifications in the quality/quantity of the pool of individual digestive
enzymes would signify evolutionary adaptations to different alimentary regimes and
the different nutritional needs of the developmental stages (Kumar et al. 2000). Kuz'mina
(1996) thus observed, at intestine level, considerable fluctuations of digestive enzyme activ-
ities according to age (0-7 years) in different species of fish. The general enzyme activity of
the digestive tract increases with the age of the individual, in response to the increase in
the size of the intestine and the weight of the mucus. On the other hand, changes concern-
ing specific activities (adjusted in comparison to the weight of the individual) have shown
that the higher digestive capacities observed during the early stages of development and
also in other stages in some species of fish, are probably related to the period of sexual
maturity of the organisms (Kuz'mina 1996). Recently, in fish endemic to Cuba ( Limia vit-
tata and Gambusia punctata ), Falcón-Hidalgo et al. (2011) have shown that digestive enzyme
activities can be used as an effective indicator of alimentary habits and of the development
of the digestive tract in these organisms.
11.5.2.2 Aquatic Invertebrates
In invertebrates, variations in digestive enzyme activities likewise exist during their
development cycle, notably in relation to changes in the alimentary regime (adaptation
to an omnivorous or carnivorous regime) (Le Vay et al. 2001). Ontogenetic changes, under
genetic control, such as physiological modifications (e.g., at the level of the gut diverticula
of the anterior region of the tract in penaeid decapods during the development of the
hepatopancreas), or the studied organ, have also had a major influence on enzyme activi-
ties (Lovett and Felder 1990; Kamarudin et al. 1994; Jones et al. 1997; Le Vay et al. 2001; Dai
et al. 2009; Díaz et al. 2009). When different larval stages of different species of crustacean
are fed with the same diet (phytoplankton or zooplankton), important variations of differ-
ent digestive enzyme activities (protease, trypsin, amylase, lipase) are likewise observed
according to development stage and individual size (Lovett and Felder 1990; Harms et al.
1991; Ceccaldi 1998; Le Vay et al. 2001; Johnston et al. 2004). In juvenile shrimps ( Litopenaeus
vannamai ), Gamboa-Delgado et al. (2003) observed positive correlations between amylase,
chymotrypsin, and lipase activities and the weight of the individuals. These increases in
enzymatic activities are related to increases in the quantity of stomach content in the same
individuals, in relation to their size (Gamboa-Delgado et al. 2003).
In the course of larval and postlarval development of invertebrates possessing an exo-
skeleton (arthropods), metamorphosis also seems to be an important factor in the varia-
tion of enzymatic activities (Van Wormhoudt 1983; Al-Mohanna and Nott 1989; Harms
et al. 1991; Fernández et al. 1997; Ceccaldi 1998; Muhlia-Almazán and García-Carreño
2002). These variations according to the stage of metamorphosis are likewise linked to
the sexual maturity cycle (Fernández et al. 1997). Indeed, variations of enzyme activity in
relation to the process of vitellogenesis in mature female crustaceans have been observed
(Van Wormhoudt and Ceccaldi 1973). Differences in amylase activities according to sex in
copepod crustaceans have been proposed by Gaudy and Boucher (1983). These amylase
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