Ontogeny of Lipolytic Enzyme Gene Expression in Sea Bass (lates Calcarifer) Larvae

— In this study, larvae of Asian seabass Lates calcarifer were fed, from mouth opening to 11 days post hatching (dph), with rotifers and then with newly hatched Artemia nauplii. Gene expression patterns of the lipolytic enzymes phospholipase A2 (PLA2) and triacylgycerol lipase (TGL) were determined by quantitative real time-PCR. The larvae were sampled at 0, 1, 2, 3, 5, 7, 10, 12, 15, 17, 20, 22, 24, 26, 28 and 30 dph. Larval dry weight was also measured. In order to quantify the mRNA levels of PLA2 and TGL, a 244-bp fragment of β-actin complementary DNA was cloned and sequenced. Based on this sequence, a real-time reverse transcriptase polymerase chain reaction technique to monitor the change in the mRNA levels in the larvae was developed. PLA2 and TGL mRNA were present at hatching and their levels generally increased with larval age and then reached a plateau. PLA2 mRNA expression was highest at 17 dph while the highest TGL mRNA expression was observed at 20 dph.