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Proteins are the major constituents of muscle and are key molecules regulating the metabolic changes during conversion of muscle to meat. Brazil is one of the largest exporters of beef and most Brazilian cattle are composed by zebu (Nellore) genotype. Bos indicus beef is generally leaner and tougher than Bos taurus such as Angus. The aim of this study was to compare the muscle proteomic and phosphoproteomic profile of Angus and Nellore. Seven animals of each breed previously subjected the same growth management were confined for 84 days. Proteins were extracted from Longissimus lumborum samples collected immediately after slaughter and separated by two-dimensional electrophoresis. Pro-Q Diamond stain was used in phosphoproteomics. Proteins identification was performed using matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Tropomyosin alpha-1 chain, troponin-T, myosin light chain-1 fragment, cytoplasmic malate dehydrogenase, alpha-enolase and 78 kDa glucose-regulated protein were more abundant in Nellore, while myosin light chain 3, prohibitin, mitochondrial stress-70 protein and heat shock 70 kDa protein 6 were more abundant in Angus (P<0.05). Nellore had higher phosphorylation of myosin regulatory light chain-2, alpha actin-1, triosephosphate isomerase and 14-3-3 protein epsilon. However, Angus had greater phosphorylation of phosphoglucomutase-1 and troponin-T (P<0.05). Therefore, proteins involved in contraction and muscle organization, myofilaments expressed in fast or slow-twitch fibers and heat shock proteins localized in mitochondria or sarcoplasmic reticulum and involved in cell flux of calcium and apoptosis might be associated with differences in beef quality between Angus and Nellore. Furthermore, prohibitin appears to be a potential biomarker of intramuscular fat in cattle. Additionally, differences in phosphorylation of myofilaments and glycolytic enzymes could be involved with differences in muscle contraction force, susceptibility to calpain, apoptosis and postmortem glycolysis, which might also be related to differences in beef quality among Angus and Nellore.

Horses are seasonal polyoestrous animals, and the photoperiod is the main factor modulating their reproductive activity. There is no consensus on the andrological and biochemical factors that influence breeding seasonality. To assess the involvement of climate in reproduction, Mangalarga Marchador stallions were monitored over 1 year regarding semen quality and seminal plasma proteome. Here, we show that kallikrein (KLKs) proteoforms in seminal plasma are involved in climate conditioning of reproduction. During the breeding season, greater abundance and different types of KLKs occurred simultaneously to lower sperm motility, greater semen volumes and higher concentrations of glucose and cholesterol. Considering that vasodilation due to activation of the kallikrein-kinin system and the consequent inhibition of the renin-angiotensin system may be associated with lower sperm motility, unravelling the involvement of KLK proteoforms in reproductive seasonality is a priority in horse breeding.

Didelphis aurita is a widely distributed neotropical marsupial frequently found in peri-urban environments and known to harbor various pathogens, including hemoparasites of the genus Hepatozoon. However, the systemic physiological responses of naturally infected individuals remain poorly understood. This study aimed to characterize the serum proteomic profile of Didelphis aurita naturally infected with Hepatozoon sp., providing insights into host–parasite interactions and potential biomarkers of infection. Serum samples were analyzed using liquid chromatography–tandem mass spectrometry (LC-MS/MS), followed by functional annotation based on Gene Ontology and KEGG pathway enrichment. A total of 67 proteins were identified, 33 of which were exclusive to infected animals. The most abundant proteins included albumin, hemoglobin subunits, and venom metalloproteinase inhibitors (DM43 and DM64). Functional enrichment revealed significant involvement in complement and coagulation cascades, protease inhibition, antioxidant defense, and extracellular vesicle localization. Key proteins such as fibrinogen, plasminogen, antithrombin, SERPIN family members, vitronectin, and fibronectin suggest an integrated host response involving hemostasis, inflammation control, and tissue remodeling. This is the first report of the serum proteome of Didelphis aurita naturally infected with Hepatozoon sp. Despite the absence of protein validation, the findings provide novel insights into marsupial immunophysiology and offer a foundation for future biomarker research and ecoimmunological surveillance in synanthropic species.

Objectives Bovine seminal plasma proteins perform several functions related to sperm function. Changes in the expression pattern or abundance of seminal proteins are related to changes in the fertilizing capacity of bulls. Considering the role of seminal plasma proteins in sperm function and animal reproduction, we investigated changes in the protein abundance profile in response to sperm morphological changes using a proteomic approach. Datadescription In our present investigation, we employed liquid chromatography coupled with mass spectrometry to elucidate the proteomic composition of seminal plasma obtained from Nellore bulls exhibiting varying percentages of sperm abnormalities. Following semen collection, seminal plasma was promptly isolated from sperm, and proteins were subsequently precipitated, enzymatically digested using porcine trypsin, and subjected to analysis utilizing the Acquity nano UHPLC System in conjunction with a mass spectrometer. This dataset encompasses a total of 297 proteins, marking the inaugural instance in which a comparative profile of seminal plasma proteins in young Nellore bulls, categorized by their sperm abnormality percentages, has been delineated using LC-MS/MS. The comprehensive nature of this dataset contributes pivotal proteomic insights, representing a noteworthy advancement in our understanding of the reproductive biology of the Nellore breed.

Quorum sensing is a cell-cell communication mechanism mediated by chemical signals that leads to differential gene expression in response to high population density. Salmonella is unable to synthesize the autoinducer-1 (AI-1), N-acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. This study aimed to evaluate the fatty acid and protein profiles of Salmonella enterica serovar Enteritidis PT4 578 throughout time of cultivation in the presence of AHL. The presence of N-dodecanoyl-homoserine lactone (C12-HSL) altered the fatty acid and protein profiles of Salmonella cultivated during 4, 6, 7, 12 and 36 h in anaerobic condition. The profiles of Salmonella Enteritidis at logarithmic phase of growth (4 h of cultivation), in the presence of C12-HSL, were similar to those of cells at late stationary phase (36 h). In addition, there was less variation in both protein and fatty acid profiles along growth, suggesting that this quorum sensing signal anticipated a stationary phase response. The presence of C12-HSL increased the abundance of thiol related proteins such as Tpx, Q7CR42, Q8ZP25, YfgD, AhpC, NfsB, YdhD and TrxA, as well as the levels of free cellular thiol after 6 h of cultivation, suggesting that these cells have greater potential to resist oxidative stress. Additionally, the LuxS protein which synthesizes the AI-2 signaling molecule was differentially abundant in the presence of C12-HSL. The NfsB protein had its abundance increased in the presence of C12-HSL at all evaluated times, which is a suggestion that the cells may be susceptible to the action of nitrofurans or that AHLs present some toxicity. Overall, the presence of C12-HSL altered important pathways related to oxidative stress and stationary phase response in Salmonella.

Hypertension is nowadays one of the major world concerns in public health. Several food proteins, among which caseins, can be substrates for generating peptides with antihypertensive potential. With the increasingly evolution of computational tools, in silico molecular modeling have gained prominence in studies of protein-ligand complexes in different research fields, such as pharmaceutics and biochemical engineering. However, the application of such methodologies in food-related research can be considered still embryonic. Thus, the central aim of the present work was to apply molecular modelling in order to elucidate the molecular bases of the anti-hypertensive potential of milk caseins-derived peptides. Firstly, hydrolysates obtained from a controlled trypsinolysis of caseins were fractioned according to their molecular weight, by ultrafiltration and RP-HPLC. The obtained fractions were evaluated with regard to their in vitro inhibitory angiotensin-converting enzyme activity (%IACE). Six chromatographic fractions were identified, and three of them displayed high ACE-inhibition (F1: 80.68%; F2: 79.00%; and F4: 62.44%). Finally, intermolecular interactions networks in complexes formed between ACE and the identified peptides were assessed through in silico molecular docking. At the molecular level, a correlation between in vitro and in silico results was found: the peptides FFVAPFPEVFGK (F6), FALPQYLK (F2, F4) and ALNEINQFYQK (F1) presented the lowest biding energies and interacted by specific H-bonds, electrostatic and hydrophobic interactions formed within ACE active site S1 residues (Ala354, Glu384, and Tyr 523) and the Zn2+ coordinated residues (His383, His387, and Glu411). The fraction F3, despite its low total peptide concentration, presented a moderate inhibitory activity for ACE (49.2%), likely due to H-bonds between HQGLPQEVLNENLLR and the active site S1 residues.

This study aimed to evaluate the proteomic profile of seminal plasma from young Nellore bulls. We used 20 bulls aged between 19.8 and 22.7 months, divided into two groups according to the results of the Breeding Soundness Evaluation (BSE): approved (FIT n = 10) and not approved (UNFIT n = 10). The scrotal perimeter was measured and a semen collection was performed through electroejaculation. The percentage of sperm motility, mass motility, and sperm vigor were calculated using conventional microscopy, and the percentage of sperm abnormalities was calculated using phase-contrast microscopy of all ejaculates. Seminal plasma was separated from spermatozoa using centrifugation and processed for proteomic analysis by LC-MS/MS. Seminal plasma proteins were identified using MASCOT Daemon software v.2.4.0 and label-free quantification analysis was carried out by SCAFFOLD Q+ software v.4.0 using the Exponentially Modified Protein Abundance Index (emPAI) method. Functional classification of proteins was performed based on their genetic ontology terms using KOG. Functional cluster analysis was performed on DAVID. There were no differences in scrotal perimeter and physical semen characteristics between FIT and UNFIT groups of bulls. The percentage of sperm abnormalities was higher (p < 0.05) in the UNFIT group of bulls. A total of 297 proteins were identified for the two groups. There were a total of 11 differentially abundant proteins (p < 0.05), two of them more abundant in FIT bulls (Spermadhesin-1 and Ig gamma-1 chain C region) and nine in UNFIT bulls (Vasoactive intestinal peptide, Metalloproteinase inhibitor 2, Ig lambda-1 chain C regions, Protein FAM3C, Hemoglobin beta, Seminal ribonuclease, Spermadhesin 2, Seminal plasma protein BSP-30kDa, and Spermadhesin Z13). Spermadhesin-1 was the protein with the highest relative abundance (36.7%) in the seminal plasma among all bulls, corresponding to 47.7% for the FIT bulls and 25,7% for the UNFIT bulls. Posttranslational modification, protein turnover, and chaperones were the functional categories with the highest number of classified proteins. Protein functional annotation clusters were related to Phospholipid efflux, ATP binding, and chaperonin-containing T-complex. The differentially abundant proteins in the group of FIT bulls were related to sperm capacitation and protection against reactive species of oxygen. In contrast, differentially expressed proteins in the group of UNFIT bulls were related to motility inhibition, intramembrane cholesterol removal and oxidative stress. In conclusion, the proteomic profile of the seminal plasma of FIT bulls presents proteins with participation in several biological processes favorable to fertilization, while the proteins of the seminal plasma of UNFIT bulls indicate a series of alterations that can compromise the fertilizing capacity of the spermatozoa. In addition, the relative abundance of spermadhesin-1 found in the seminal plasma of young Nellore bulls could be studied as a reproductive parameter for selection.

Sexual rest is a transient condition, which compromises conception rates, characterized by large volumes of ejaculate with high percentages of dead sperm observed in bulls. The biochemical mechanisms leading to this ejaculate pattern are not fully understood. Six adult resting Nellore bulls were submitted to Breeding Soundness Evaluation by four consecutive semen collections through the electroejaculation method during a 30 min period. Each ejaculate had its semen phenotypic parameters; morphology and physical aspects were evaluated. To assess enzymatic activity (superoxide dismutase, catalase, and glutathione S-transferase), lipid peroxidation (concentrations of malondialdehyde and nitric oxide), fatty acid, and proteomic profile aliquots of spermatozoa from the first and fourth ejaculates were used. All sperm parameters differed between the first and fourth ejaculates. Spermatozoa from the first ejaculate showed lower enzymatic activity and a higher concentration of lipid peroxidation markers. Among the 19 identified fatty acids, 52.7% are polyunsaturated. Relative abundance analysis showed that C12:0 and C18:0 fatty acids differed between the first and fourth ejaculates, being the fourth ejaculate richer in spermatozoa. The proteomics analysis identified a total of 974 proteins in both sample groups (first and fourth ejaculates). The majority of identified proteins are related to cellular processes and signaling. Quantitative proteomics showed 36 differentially abundant proteins, 6 up-regulated proteins in the first ejaculate, and 30 up-regulated proteins in the fourth ejaculate. Spermatozoa from bulls at sexual rest have less antioxidant capacity, causing changes in their fatty acid composition and protein profile, which generates the observed sperm pattern and lower fertilization capacity. Graphical Abstract

Sexual rest (SR) in bulls leads to the accumulation of senescent spermatozoa in the extragonadal reserves, potentially affecting semen quality and reproductive efficiency. Therefore, this study aimed to investigate the impact of SR on the seminal plasma proteome and oxidative status of Nellore bulls. Six adult bulls were subjected to 195 days of SR and sequential semen collections using the electroejaculation method. The ejaculates were analyzed to assess sperm quality. Seminal plasma from the first and last ejaculates was evaluated for oxidative status and proteomic profile using LC-MS. The results revealed significant improvements in sperm motility, vigor, and antioxidant enzyme activity (superoxide dismutase and catalase) in the last ejaculate compared to the first. Conversely, higher levels of oxidative markers, such as malondialdehyde and carbonyl proteins, were observed in the first ejaculate. Proteomic analysis identified 156 proteins, with 28 differentially abundant between ejaculates. The first ejaculate showed a higher abundance of proteins linked to acrosomal exocytosis and energy metabolism, while proteins associated with sperm motility and immune modulation were elevated in the last ejaculate. These findings suggest that SR induces oxidative stress and proteomic alterations in seminal plasma, negatively affecting sperm quality, emphasizing the need for strategic reproductive management in bulls.

Ant venom has several functions, including predation, communication, defense against predators, and action against pathogens. There is a scarcity of data about ant venom components that could provide support for understanding the mechanisms of action. The objective here was to identify the amino acids and proteins in the venom of the predatory ant Ectatomma brunneum and to evaluate its antimicrobial activity. The amino acids were analyzed by liquid chromatography, with diode array detection, and were identified using amino acid standards. The two-dimensional (2D) gel electrophoresis fractionation approach was used to identify the proteins, together with MALDI-TOF/TOF mass spectrometry and protein databases. The antimicrobial activity of the venom was evaluated using the minimum inhibitory and minimum microbiocidal concentrations. The venom of E. brunneum contained free amino acids, with a high amount of alanine. The 2D gel analysis showed 104 spots, of which 21 were identified and classified according to biological function, as follows: venom proteins, nontoxic reservoir protection, cellular maintenance proteins, and proteins with unknown function. The venom showed antimicrobial activity, inhibiting the growth of all the bacteria and fungi tested. The results provide new insights into ant venom components and antimicrobial activity.