Investigação do perfil proteômico de oreochromis niloticus (tilápia do nilo): identificação de proteínas relacionadas ao estresse causado por amônia

Abstract

The investigation of the proteome is an essential component to provide information about the proteins involved in stress. This study aims to determine possible changes in the expression profile of proteins induced by stress with ammonia in liver and gill tissues of Oreochromis. niloticus (Nile tilapia) and identify potential biomarkers related to stress, as well, purify a lectin identified in the liver of tilapia. The fish were grown in outdoor system and divided into two groups: negative control (they received no mechanical aeration) positive control (which received mechanical aeration of water). 10 fishes from each group were used for proteomic analysis. The proteins profiles were obtained by two-dimensional electrophoresis and identified by mass spectrometry. Lectin was isolated from liver of commercially available fish. Comparative proteomic analysis revealed changes in the expression of 24 spots in the liver and 6 spots in the gills at the negative control. The differentially expressed spots were subjected to analysis of mass spectrometry, with resulting identification of 5 proteins for liver and in gills were not identified. The altered expression levels proteins in the liver are involved in cell structure, signal transduction, protein modification, metabolism and transport, which can be strong candidates for ammonia biomarkers stress. This may be related to the recovery and cell protection by preventing severe damage to the cell. These results may provide a better understanding of the proteins that are involved in the stress response studied. It has also been isolated lectin of tilapia liver from the combination of affinity and ion exchange chromatographies, having a molecular weight estimated by SDS-PAGE at 26 kDa, was inhibited more efficiently by the 4-Nitrophenyl ß-Galactopironoside sugar, inhibiting the lectin activity at a concentration of 1,562 mM, exhibited toxicity at Artemia sp after 48 hours and showed interference in the formation of biofilms in concentrations of 31,25 and 62 5 µg/mL for Staphylococcus aureus and 125 and 250 µg/mL for Escherichia coli and inhibited significantly the number of viable cells in the tested bacteria.