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The present study was conducted to identify the major seminal plasma protein profile of boars and its associations with semen criteria. Semen samples were collected from 12 adult boars and subjected to evaluation of sperm parameters (motility, morphology, vitality, and percent of cells with intact acrosome). Seminal plasma was obtained by centrifugation, analyzed by two-dimensional SDS-PAGE, and proteins identified by mass spectrometry (electrospray ionization quadrupole time-of-flight). We tested regression models using spot intensities related to the same proteins as independent variables and semen parameters as dependent variables (P ≤ 0.05). One hundred twelve spots were identified in the boar seminal plasma gels, equivalent to 39 different proteins. Spermadhesin porcine seminal protein (PSP)-I and PSP-II, as well as spermadhesins AQN-1, AQN-3 and AWN-1 represented 45.2 ± 8% of the total intensity of all spots. Other proteins expressed in the boar seminal plasma included albumin, complement proteins (complement factor H precursor, complement C3 precursor and adipsin/complement factor D), immunoglobulins (IgG heavy chain precursor, IgG delta heavy chain membrane bound form, IgG gamma-chain, Ig lambda chain V-C region PLC3, and CH4 and secreted domains of swine IgM), IgG-binding proteins, epididymal-specific lipocalin 5, epididymal secretory protein E1 precursor, epididymal secretory glutathione peroxidase precursor, transferrin, lactotransferrin and fibronectin type 1 (FN1). On the basis of the regression analysis, the percentage of sperm with midpiece defects was related to the amount of CH4 and secreted domains of swine IgM and FN1 (r² = 0.58, P = 0.006), IgG-binding protein (r² = 0.41, P = 0.024), complement factor H precursor (r² = 0.61, P = 0.014) and lactadherin (r² = 0.45, P = 0.033). The percentage of sperm with tail defects was also related to CH4 and secreted domains of swine IgM and FN1 (r² = 0.40, P = 0.034), IgG-binding protein (r² = 0.35, P = 0.043) and lactadherin (r² = 0.74, P = 0.001). Sperm motility, in turn, had association with the intensities of spots identified as lactadherin (r² = 0.48, P = 0.027). In conclusion, we presently describe the major proteome of boar seminal plasma and significant associations between specific seminal plasma proteins and semen parameters. Such relationships will serve as the basis for determination of molecular markers of sperm function in the swine species.

Jatropha curcas seed cake is a low-value by-product resulting from biodiesel production. The seed cake is highly toxic, but it has great potential for biotechnology applications as it is a repository of biomolecules that could be important in agriculture, medicine, and industry. To explore this potential, a novel trypsin inhibitor called JcTI-I was purified by fractionation of the crude extract with trichloroacetic acid (2.5%, v/v) followed by affinity chromatography (Trypsin-Sepharose 4B) and molecular exclusion (Sephacryl S-200). Non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration showed that JcTI-I has approximately 20.0~kDa. Mass spectrometry analysis revealed that the intact molecular mass of JcTI-I is 10.252~kDa. Moreover, JcTI-I is a glycoprotein with 6.4% (m/m) carbohydrates, pI of 6.6, N-terminal sequence similarity around 60% to plant albumins and high stability to heat, pH, and salinity. JcTI-I presented antibacterial activity against the human pathogenic bacteria Salmonella enterica subspecies enterica serovar choleraesuis and Staphylococcus aureus, with minimum inhibitory concentration less than 5~μg/mL. Furthermore, JcTI-I did have inhibitory activity against the serine proteases from the tested bacteria. Otherwise, no hemolytic activity of human erythrocytes and signs of acute toxicity to mice were observed for JcTI-I. The results demonstrate the benefits of J. curcas seed cake as a source of trypsin inhibitor with potential for biotechnological application as a new antimicrobial agent against human pathogenic bacteria.

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