S. Ozkizilcik et al., ONTOGENIC CHANGES OF LIPOLYTIC ENZYMES IN STRIPED BASS (MORONE-SAXATILIS), Comparative biochemistry and physiology. B. Comparative biochemistry, 113(3), 1996, pp. 631-637
Ontogenetic changes of triacylglycerol hydrolase (TAGH), wax ester hyd
rolase (WEH) and phospholipase A(2) (PLA(2)) activities were determine
d in the fertilized eggs and premetamorphosed larvae of striped bass a
nd the larval food Artemia using radioassays. Maximum activities of th
e three enzymes were observed at a substrate concentration of 500 mu M
and in the presence of 5 mM Na-taurocholate. PLA(2) showed the major
activity in the eggs, followed by TAGH and WEH. TAGH became the domina
nt lipolytic activity after feeding was initiated at 7 days post-hatch
ing (DPH). The proportions of TAGH:PLA(2):WEH in the fertilized eggs w
ere 1.1:1.6:1.0. In 20 DPH fed larvae, however, the proportion changed
to 6.3:1.9:1.0. In unfed larvae, the enzyme activities were significa
ntly lower compared to feeding larvae (P < 0.05). The activities of PL
A(2), TAGH and WEH in Artemia were in the order of PLA(2) > TAGH > WEH
. The contribution of dietary enzymes to the total lipolytic processes
is estimated to be less than 6.5% of the total enzyme activity throug
hout the development. The results of this study indicate that first fe
eding striped bass larvae have the capacity to digest 47% of their dai
ly lipid ingestion.