Are the Main Methionine Sources Equivalent? A Focus on DL-Methionine and DL-Methionine Hydroxy Analog Reveals Differences on Rainbow Trout Hepatic Cell Lines Functions

Abstract

The replacement of fishmeal by plant proteins in aquafeeds imposes the use of synthetic methionine (MET) sources to balance the amino acid composition of alternative diets and so to meet the metabolic needs of fish of agronomic interest such as rainbow trout (RT-Oncorhynchus mykiss). Nonetheless, debates still exist to determine if one MET source is more efficiently used than another by fish. To address this question, the use of fish cell lines appeared a convenient strategy, since it allowed to perfectly control cell growing conditions notably by fully depleting MET from the media and studying which MET source is capable to restore cell growth/proliferation and metabolism when supplemented back. Thus, results of cell proliferation assays, Western blots, RT-qPCR and liquid chromatography analyses from two RT liver-derived cell lines revealed a better absorption and metabolization of DL-MET than DL-Methionine Hydroxy Analog (MHA) with the activation of the mechanistic Target Of Rapamycin (mTOR) pathway for DL-MET and the activation of integrated stress response (ISR) pathway for MHA. Altogether, the results clearly allow to conclude that both synthetic MET sources are not biologically equivalent, suggesting similar in vivo effects in RT liver and, therefore, questioning the MHA efficiencies in other RT tissues.

Precision formulation, a new concept to improve dietary amino acid absorption based on the study of cationic amino acid transporters

“…Primers were validated when i) efficiencies was comprised between 1,85 and 2,15, ii) RT-PCR product migrate in an agarose gel at the expected size and iii) when sequence obtained by DNA sequencing (Genewiz, Leipzig, Germany) corresponded to the theorical sequence of the mRNA targeted. Primers for ddit3 , asns , xbp1 , edem1 and slc7a7 validated in previous studies 26 , 28 , 49 , 50 , 51 as well as those newly designed and validated for all RT CAAT genes identified are listed in Table S1 . The gene expression levels were presented as the relative quotient (RQ) calculated using the ΔΔCT method.…”