Lysine (Lys) is an indispensable amino acid (AA) and is generally the first limiting AA in most vegetable proteins used in fish feeds. Lys availability may thus limit protein synthesis and accretion, and growth of fish. Metabolic effects of dietary Lys imbalance were examined by 2D-proteomics using zebrafish as model. The Control diet (Lys: 2.47 g kg(-1)) was based on zebrafish carcass AA profiles previously obtained. Two other experimental diets were deficient in Lys [Lys(-); 1.34 g kg(-1)] and Lys added in excess [Lys(+); 4.63 g kg(-1)]. Fish growth was monitored from 33 to 49 days post-fertilization and the whole body proteome screened by means of two-dimension gel electrophoresis and mass spectrometry. Growth rate was negatively affected in group Lys(-). Comparative proteomic analysis showed 45 spots differentially expressed among groups. Twenty-nine of these proteins were identified revealing proteins involved in muscle growth, energy and lipid metabolism, eye lens differentiation, chaperone activity and apoptosis. Lys deficiency is accompanied by a down-regulation of muscle proteins and up-regulation of proteins affected by fasting, energy deficit, growth arrest and apoptosis. Excess Lys was accompanied by an up-regulation of proteins related to glycolysis, steroidogenesis and sexual maturation.

http://www.ncbi.nlm.nih.gov/pubmed/21440519?dopt=Abstract