Expression analyses of digestive enzymes during early development and in adults of the chame fish Dormitator latifrons

This study describes the expression of genes that encode digestive enzymes (trypsin, pepsinogen, maltase‐glucoamylase, sucrase‐isomaltase, alkaline phosphatase and leucine aminopeptidase) using qRT‐PCR in 0‐ to 7‐day post‐hatching (dph) chame (Dormitator latifrons). Additionally, adults liver and intestine were analysed for enzyme expression. Results showed that transcripts for all enzymes are present in both adult and larvae tissues. In adults, the expression of maltase‐glucoamylase and sucrose‐isomaltase showed the highest values in the middle intestine, while the liver and anterior and posterior intestine showed low expression levels. Other enzymes showed low expression in all tissues, with the exception of leucine aminopeptidase, which showed high expression in liver. In larvae whole‐body samples of D. latifrons, maltase‐glucoamylase and sucrose‐isomaltase showed the highest expression from 3 to 5 dph, while other enzymes maintained low levels from hatching to 7 dph. The highest expression of disaccharidases such as maltase‐glucoamylase and sucrose‐isomaltase corresponded to the beginning of exogenous feeding, suggesting that this species exhibits an herbivorous profile. However, the presence of proteolytic enzymes may indicate that D. latifrons is programmed to be able to digest other substrates. This information will contribute to the development of larval feeding protocols to produce chame juveniles in laboratory conditions, as prior larval feeding essays have not been successful, using either live feeds or commercial fish larval diets.