An improved planar module automatic layout method for large number of dies

Abstract

In many fish species, the early pattern of nitrogen metabolism and excretion is influenced by the dominance of amino acids as the primary fuel, and by the resulting toxic end-product, ammonia. Pelagic eggs of marine teleosts at spawning contain a large yolk pool of FAA. During final oocyte maturation the FAA originate by hydrolysis of specific yolk proteins, and they assist in egg hydration. At the start of exogenous feeding, marine fish larvae will inevitably ingest a new supply of FAA with their zooplankton prey and they can thus continue an amino acid-based energy dissipation despite low intestinal proteolytic capacity. Ammonia excretion rates increase with developmental stage, but ammonia also accumulates to substantial levels around the time of hatching. Historically, urea excretion has been considered of minor importance in embryos and larvae of teleosts, but significant levels of urea cycle enzymes have recently been detected during embryogenesis in some species, despite low or nondetectable levels in the adults. Mechanisms of nitrogen excretion have been studied only in freshwater rainbow trout embryos, where ammonia excretion is dependent on the partial pressure gradient of NH3. Future research on a diverse array of species with different life histories and environments will broaden our understanding of the ontogeny of nitrogen excretion.