Absorption, assimilation and
catabolism of individual free amino acids by larval Atlantic halibut (Hippoglossus
hippoglossus)
S.L. Applebaum, I. Rønnestad-2004
Aquaculture, 230(1-4): 313-322
Abstract:
Following the completion of the lecithotrophic phase,
most marine larvae rely on an incompletely developed digestive tract to
absorb amino acids (AA) and other nutrients needed for rapid growth. Despite
their undeveloped state, larvae must absorb nutrients in sufficient amounts
to fuel exceptionally high rates of growth. This study examined the ability
of larval Atlantic halibut to absorb, assimilate and catabolise dispensable
(alanine, glutamate) and indispensable (arginine, lysine) dietary free amino
acids (FAA) using tube-fed AA solutions with 14C tracers.
Absorption of FAA was rapid with an average of 71% absorbed from the gut
within 30 min after tube feeding. Evacuation of FAA by larvae was low,
averaging only 6% of tube-fed dose. Dispensable amino acids (DAA) were
catabolised in greater proportion (17%) than indispensable FAA (54%).
Saturation of FAA transporters was not attained under the present conditions
(20 mM, 20% midgut filling). Absorption rates did not differ significantly
between the four FAA.
(Department
of Zoology, University of Bergen, Allegt. 41, N-5007, Bergen, Norway, e-mail
of I. Ronnestad: ivar.ronnestad@zoo.uib.no)