Metabolism of amino acids during hyposmotic adaptation in the whiteleg shrimp, Litopenaeus vannamei

Abstract

The penaeid prawn, Litopenaeus vannamei, was employed to investigate intracellular isosmotic regulation in situations where invertebrates encounter hyposmosis. Hemolymph osmolality was first analyzed to confirm osmoregulatory conditions in the experimental animals, followed by analysis of amino acids in muscle and hemolymph using high-performance liquid chromatography. Total muscle amino acid levels decreased when hemolymph osmolality was extremely low, whereas glycine and L-serine levels increased in the hemolymph. These results suggest that tissue amino acids were released into the hemolymph to lower the osmolality of the tissues for purposes of low-salinity adaptation. Next, oxygen consumption and ammonia excretion rates were examined, and the O/N ratio was determined. Oxygen consumption levels and ammonia excretion rates increased, and the O/N ratio decreased when the animals were exposed to low salinity. These results suggest that amino acids were abundantly consumed as an energy source when animals were exposed to low salinity. To confirm the consumption of particular amino acids, the specific activity of L-serine ammonia lyase was also examined. Specific activity was highest when L-serine levels in the hemolymph were highest. Thus, it appears that L-serine levels increased under hyposmotic conditions due to the consumption of L-serine as an energy source. It was concluded that particular amino acids as osmolytes are likely metabolized as energy sources and consumed for purposes of hyposmotic adaptation.

Performance of zero water discharge (ZWD) system with nitrifying bacteria Bacillus megaterium and microalgae Chaetoceros calcitrans components in super intensive pacific white shrimp Litopenaeus vannamei culture at low salinity

“…Low growth of white shrimp reared at low salinity was assumed due to enormous energy demand in ion and amino acid osmolarity in body tissues for osmoregulation process. It was in line with Shinji et al (2012) who stated that white shrimp reared at salinity 3 g/L would synthesized certain amino acid (L-serine and lysine) which suspected to regulate osmoregulation process. Roy et al (2010) also presented that rearing media modification using magnesium and potassium fertilizer was further effective compared with feed modification technique in producing high growth and survival rate, and stable osmoregulation.…”

1H NMR-based metabolomics of Daphnia magna responses after sub-lethal exposure to triclosan, carbamazepine and ibuprofen

“…The consistent depletion of serine across carbamazepine exposure concentrations indicates that serine may be a very sensitive indicator for carbamazepine exposure in D. magna. In crustaceans and other aquatic invertebrates, glycine can be metabolized to serine, and serine is used as an energy source in the Krebs cycle through conversion to pyruvate (Shinji et al, 2012). A decrease in serine and glycine may also be due to their use in the transsulfuration pathway that can be activated for oxidative stress defense against carbamazepine exposure, with serine used to convert homocysteine to cystathionine and glycine used to convert γ-glutamylcysteine to glutathione (Long et al, 2015).…”

Changes in free amino acid concentrations and associated gene expression profiles in the abdominal muscle of kuruma shrimpMarsupenaeus japonicusacclimated at different salinities

“…Therefore, the two amino acids are considered to be important osmolytes for these invertebrates (Abe et al, 1999(Abe et al, , 2005Fujimori and Abe, 2002;Okuma and Abe, 1994). Another experiment indicated that the concentrations of total free amino acids were decreased in the muscle of Pacific white shrimp, Litopenaeus vannamei, acclimated at low salinity, whereas those of glycine and L-serine were increased in the hemolymph and were associated with a decrease in the osmotic pressure in the muscle, suggesting that tissue amino acids were released into the hemolymph to lower the osmolarity of the tissue (Shinji et al, 2012).…”