Application of proteomic to investigate the different degrees of meat tenderness in Nellore breed.

This study describes the association between meat tenderness and abundance of soluble muscle proteins in Nellore bulls (Bos indicus) using a proteomic approach. We evaluated shear force (SF) of Longissimus thoracis muscle 24 h after slaughter and selected three experimental groups of animals with moderately tender (TE; SF = 3.9 ± 0.7 kg), moderately tough (TO; SF = 5.6 ± 0.7 kg) and very tough meat (TO+; SF = 7.9 ± 1.4 kg). Proteome was investigated by two-dimensional electrophoresis (2D-PAGE) in combination with electrospray ionization-tandem mass spectrometry (ESI-MS/MS). The metabolic proteins triosephosphate isomerase (TPI1) and phosphoglucomutase 1 (PGM1), the structural protein profilin 1 (PFN1), and cytosol aminopeptidase (LAP3) were up-regulated (P < 0.05) in the TE meat group when compared to the TO and TO+ groups. Actin structural proteins (ACTA1, ACTB, and ACTG1), the oxidative stress protein peroxiredoxin (PRDX6, PRDX2, PRDX1, and PARK7), heat shock protein isoforms, and co-chaperones (CDC37 and STIP1) were up-regulated (P < 0.05) in the TO and TO+ meat groups. In addition, we also identified proteins PFN1, LAP3, PRDX1, PRDX2, HSPD1, and ARHGDIA to be associated with beef tenderness. The results reported herein demonstrated that meat tenderness in Nellore cattle depends on the modulation and expression of a set of proteins involved in different biological pathways. SIGNIFICANCE: The manuscript entitled "Application of proteomic to investigate the different degrees of meat tenderness in Nellore breed" describes a classical proteomics work using two-dimensional gel electrophoresis (2D-PAGE), followed by mass spectrometry coupled to electrospray ionization ion trap (ESI-MS/MS) in order to understand the biochemical engineering involved in the process of meat tenderness. We evaluated shear force (SF) of Longissimus thoracis muscle samples of Nellore cattle (n = 90) and select three experimental groups of animals with moderately tender (TE; SF = 3.9 ± 0.7), moderately tough (TO; SF = 5.6 ± 0.7) and very tough meat (TO+; SF = 7.9 ± 1.4). The proteomic approach allowed observing that meat tenderness is influenced by structural proteins (ACTA1, ACTG1, ACTB, MYL1 and PFN1), co-chaperones (CDC37 and STIP1), heat shock proteins (HSP90AA1, HSP90AB1, HSPD1, HSPA1L, HSPA1A and HSPB1), regulatory protein (ARHGDIA), metabolic proteins (TPI1 and PGM1) and oxidative stress proteins (PRDX1, PRDX2, PRDX6, PARK7). Our results suggest that meat tenderness in Nellore depends on the modulation and expression of a set of proteins involved in different biological pathways.

Metalloproteomics Approach to Analyze Mercury in Breast Milk and Hair Samples of Lactating Women in Communities of the Amazon Basin, Brazil.

Mercury is a potentially toxic element that is present in the environment of the Brazilian Amazon and is responsible for adverse health effects in humans. This study sought to assess possible protein biomarkers of mercury exposure in breast milk samples from lactating women in the Madeira and Negro Rivers in the Brazilian Amazon. The mercury content of hair samples of lactating women was determined, and the proteome of breast milk samples was obtained using two-dimensional electrophoresis after protein precipitation with acetone. Mercury measurements of protein spots obtained via protein fractionation were performed by graphite furnace atomic absorption spectrometry (GFAAS), and it was observed that mercury is linked to proteins with molecular masses in the range of 14-26 kDa. The total mercury concentration was also determined by GFAAS in unprocessed milk, lyophilized milk, and protein pellets, with the purpose of determining the mercury mass balance in relation to the concentration of this element in milk and pellets. Approximately 85 to 97% of mercury present in the lyophilized milk from samples of lactating women of the Madeira River is bound in the protein fraction. From lactating women of the Negro River, approximately 49% of the total mercury is bound in the protein fraction, and a difference of 51% is bound in the lipid fraction.

Mercury fractionation in dourada (Brachyplatystoma rousseauxii) of the Madeira River in Brazil using metalloproteomic strategies.

This paper presents the results of mercury fractionation in muscle samples of dourada (Brachyplatystoma rousseauxii) from the JIRAU Hydroelectric Power Plant in the Madeira River Basin in the Amazon region of Brazil. The proteome of the dourada muscle was separated by two-dimensional polyacrylamide gel electrophoresis (2D PAGE). The mercury present in the protein spots was determined by graphite furnace atomic absorption spectrometry (GFAAS) after acid mineralisation in an ultrasound bath. The protein spots in which the presence of mercury was detected were characterised by electrospray ionisation tandem mass spectrometry (ESI-MS/MS) after tryptic digestion. The GFAAS determinations indicated that 65% of the mercury was linked to the protein fraction with a molar mass (Mm) of less than 90 kDa. The mercury concentrations in the seven spots in which this protein fraction was present were in the range of 11.40-35.10 µg kg(-1). Based on the mercury concentrations, it was possible to estimate that the protein spots contained approximately 1-3 mercury atoms per protein molecule. The ESI-MS/MS analysis allowed characterisation of the seven protein spots as the following proteins: protein NLRC5 (molar mass=18.10, pI=6.30); 39S ribosomal protein L36 mitochondrial (molar mass=15.40, pI=8.23); N-alpha-acetyltransferase 20 (Mm=15.95, pI=8.80); Mth938 domain-containing protein (Mm=15.01, pI=9.60); ubiquitin-40S ribosomal protein S27a (Mm=9.80, pI=7.60); parvalbumin alpha (Mm=12.40, pI=3.80) and parvalbumin beta (Mm=13.10, pI=3.45).