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)
98 D. Lemos et al.rAquaculture 186 (2000 89–105

Fig. 4. Digestive proteinases from F. paulensis adult hepatopancreas in substrate-SDS-PAGE ŽLemos et al.,
1999 .. MWsmolecular weight markers; Psprotein pattern. C, 1, 2, and 3 lanes denote the activity pattern of
the samples incubated with different inhibitors as follows: C, control Žwithout inhibitor ; 1, TLCK; 2, PMSF;
.
3, TPCK. Other abbreviations are as in Fig. 2.

to 21.7 kDa Žlane 1 and three possible chymotrypsins of 28.9, 32 and 37.7 kDa lane 2 .
.
Ž
were found in adult F. paulensis ŽFig. 4 . Their molecular weight is similar to that
.
reported for P. monodon trypsin ŽJiang et al., 1991 and L. Õannamei chymotrypsin
.
´
´
ŽHernandez-Cortes et al., 1997 .
.
The nutritional requirements of penaeid species are quite variable ŽTacon, 1987;
Akiyama et al., 1992 .. Nevertheless, the bulk of studies on penaeid nutrition has been
focused on the most widely cultured species such as M. japonicus, P. monodon and L.
´
Õannamei ŽGarcıa, 1996 . The success in culturing these species is mostly based on the
.
availability of suitable formulated feeds that yield satisfactory growth. When growing
alternative penaeid species, farmers depend on the use of standard diets that have not
been developed according to the species nutritional needs ŽAkiyama et al., 1992 . The
.
different characteristics of digestive proteinases from F. californiensis, L. Õannamei, F.
paulensis, and L. schmitti ŽFig. 5 are evidences of a species-specific pattern of protein
.
digestion. A common feature among these species is the occurrence of enzymes with
molecular mass equal to or lower than 20 kDa. F. californiensis Žlane 2 exhibited a
.
higher number of low molecular weight enzymes than the other species, while in L.
Õannamei Žlane 3 , intense bands are observed between 20 and 29 kDa. Few activity
.
zones heavier than 29 kDa were detected. Because of the diverse proteinase pattern
among these species, different properties related to the digestion of feed protein fraction
may be expected.
The lack of nutritional information has limited the number of potential species for
shrimp culture. As an example, several Brazilian shrimp farmers have chosen the exotic
L. Õannamei instead of autochthonous species because of its better growth performance.
The availability of a suitable commercial feed for L. Õannamei has contributed to the
adoption of this species. On the other hand, the cultivation of the native F. paulensis in