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The lateral membrane organization and phase behavior of the binary lipid mixture DMPC (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine) - DSPC (1,2-distearoyl-sn-glycero-3-phosphatidylcholine) without and with incorporated gramicidin D (GD) as a model biomembrane polypeptide was studied by small-angle neutron scattering, Fourier-transform infrared spectroscopy, and by two-photon excitation fluorescence microscopy on giant unilamellar vesicles. The small-angle neutron scattering method allows the detection of concentration fluctuations in the range from 1 to 200 nm. Fluorescence microscopy was used for direct visualization of the lateral lipid organization and domain shapes on a micrometer length scale including information of the lipid phase state. In the fluid-gel coexistence region of the pure binary lipid system, large-scale concentration fluctuations appear. Infrared spectral parameters were used to determine the peptide conformation adopted in the different lipid phases. The data show that the structure of the temperature-dependent lipid phases is significantly altered by the insertion of 2 to 5 mol% GD. At temperatures corresponding to the gel-fluid phase coexistence region the concentration fluctuations drastically decrease, and we observe domains in the giant unilamellar vesicles, which mainly disappear by the incorporation of 2 to 5 mol% GD. Further, the lipid matrix has the ability to modulate the conformation of the inserted polypeptide. The balance between double-helical and helical dimer structures of GD depends on the phospholipid chain length and phase state. A large hydrophobic mismatch, such as in gel phase one-component DSPC bilayers, leads to an increase in population of double-helical structures. Using an effective molecular sorting mechanism, a large hydrophobic mismatch can be avoided in the DMPC-DSPC lipid mixture, which leads to significant changes in the heterogeneous lipid structure and in polypeptide conformation.

Previous attempts at eliminating the problem of PSE pork by genetic selection or rapid postmortem cooling have been only partially successful. A new approach, namely, postmortem injection of sodium bicarbonate (SBC), was tested on halothane-positive gilts. Sixteen pigs were used to establish a suitable SBC concentration. At approximately 15 min after death, the longissimus of one side of the carcass was injected with 10% (by weight) of .2 to .4 M SBC solutions containing .7% NaCl (wt/vol). All concentrations resulted in a higher ultimate pH, improved muscle color, and reduced drip loss. In a second experiment, with 23 pigs, .3 M SBC was injected into the longissimus and the biceps femoris at either 15 min or 24 h after death and with or without inclusion of .7% NaCl (wt/vol). Compared with controls, the 15-min SBC + NaCl injected samples had darker color ([L.sup.*] of 47 vs 53 in controls), higher ultimate pH (5.6 vs 5.3), lower drip loss (5% vs 10%), and increased protein solubility (140 vs 115 mg/g). Injection at 24 h reduced drip loss (from 10% to 5.7%) but did not correct the color defect. The SBC alone and SBC + NaCl treatments had essentially the same effects in reducing drip loss, increasing ultimate pH, and improving color; but the SBC-NaCl injected samples had improved juiciness and flavor compared with SBC. Early postmortem sodium bicarbonate injection seems to prevent the development of PSE pork when injected into carcasses of halothane-sensitive pigs. Key Words: Pigmeat, Quality, Sodium Bicarbonate

We investigated the potential contribution of mitochondrial DNA (mtDNA) variants, haplogroups, and polymorphisms in nuclear genes essential for mitochondrial biogenesis and function (PGC-1α TFAM) to late-onset Alzheimer's disease (LOAD) risk. Epistatic interaction analysis was conducted between the studied variables. Our results demonstrate that mtDNA haplogroups and subhaplogroups with putative role in partial uncoupling of oxidative phosphorylation are significantly associated with a decreased LOAD risk (OR <1). Conversely, mtDNA haplogroup H (p = 0.049) and HV cluster (p = 0.018) are significant LOAD risk factors, which was additionally confirmed by meta-analysis (OR = 1.22, OR = 1.25, respectively). Haplogroup K was demonstrated to exert a neutralizing effect on the high risk associated with APOE4+ status (p = 0.014). Further, two synergistic interactions between subhaplogroup H5 and APOE4 status (p = 0.009) and between TFAM rs1937 and APOE4 status (p < 0.001) were detected, influencing LOAD risk. No interaction pointing to a dual mitochondrial-nuclear genome variation effect on LOAD occurrence was identified. [ABSTRACT FROM AUTHOR]

The aim of the study was to analyse the influence of tenderising treatments applied to the carcasses of Polish Holstein-Friesian (PHF) bulls of Black-and-White variety on the process of meat tenderisation and to assess the role of collagen in this process. The research was carried out on m. longissimus thoracis et lumborum. The carcasses were subjected to high-voltage electrical stimulation (ES), conditioning (CD), and both treatments together (ES + CD). The carcasses which were only refrigerated were the control group. The content of collagen in meat, its solubility, the share of the polypeptide subunits α1(I)CB7 and α1(I)CB8 of type I collagen and α1(III)CB5 of type III collagen were also analysed. ES with and without CD significantly accelerated the meat tenderisation and increased collagen solubility. CD always caused the degradation of type I collagen subunits, especially the α1(I)CB7 subunit. However, CD had significantly lesser influence on the rate of meat tenderisation than ES. [ABSTRACT FROM AUTHOR]

Background & Aims: Hepatic fibrosis is characterized by enhanced deposition of extracellular matrix (ECM), which results from the wound healing response to chronic, repeated injury of any etiology. Upon injury, hepatic stellate cells (HSCs) activate and secrete ECM proteins, forming scar tissue, which leads to liver dysfunction. Monocyte-chemoattractant protein-induced protein 1 (MCPIP1) possesses anti-inflammatory activity, and its overexpression reduces liver injury in septic mice. In addition, mice with liver-specific deletion of Zc3h12a develop features of primary biliary cholangitis. In this study, we investigated the role of MCPIP1 in liver fibrosis and HSC activation., Methods: We analyzed MCPIP1 levels in patients' fibrotic livers and hepatic cells isolated from fibrotic murine livers. In vitro experiments were conducted on primary HSCs, cholangiocytes, hepatocytes, and LX-2 cells with MCPIP1 overexpression or silencing., Results: MCPIP1 levels are induced in patients' fibrotic livers compared with their nonfibrotic counterparts. Murine models of fibrosis revealed that its level is increased in HSCs and hepatocytes. Moreover, hepatocytes with Mcpip1 deletion trigger HSC activation via the release of connective tissue growth factor. Overexpression of MCPIP1 in LX-2 cells inhibits their activation through the regulation of TGFB1 expression, and this phenotype is reversed upon MCPIP1 silencing., Conclusions: We demonstrated that MCPIP1 is induced in human fibrotic livers and regulates the activation of HSCs in both autocrine and paracrine manners. Our results indicate that MCPIP1 could have a potential role in the development of liver fibrosis., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Epithelial-mesenchymal transition (EMT) refers to the acquisition of mesenchymal properties in cells participating in tumor progression. One hallmark of EMT is the increased level of active β-catenin, which can trigger the transcription of Wnt-specific genes responsible for the control of cell fate. We investigated how Monocyte Chemotactic Protein-1-Induced Protein-1 (MCPIP1), a negative regulator of inflammatory processes, affects EMT in a clear cell renal cell carcinoma (ccRCC) cell line, patient tumor tissues and a xenotransplant model. We showed that MCPIP1 degrades miRNAs via its RNase activity and thus protects the mRNA transcripts of negative regulators of the Wnt/β-catenin pathway from degradation, which in turn prevents EMT. Mechanistically, the loss of MCPIP1 RNase activity led to the upregulation of miRNA-519a-3p, miRNA-519b-3p, and miRNA-520c-3p, which inhibited the expression of Wnt pathway inhibitors (SFRP4, KREMEN1, CXXC4, CSNK1A1 and ZNFR3). Thus, the level of active nuclear β-catenin was increased, leading to increased levels of EMT inducers (SNAI1, SNAI2, ZEB1 and TWIST) and, consequently, decreased expression of E-cadherin, increased expression of mesenchymal markers, and acquisition of the mesenchymal phenotype. This study revealed that MCPIP1 may act as a tumor suppressor that prevents EMT by stabilizing Wnt inhibitors and decreasing the levels of active β-catenin and EMT inducers., (© 2021. The Author(s).)

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic in early 2020. The infection has been associated with a wide range of clinical symptoms. In the severely affected patients, it has caused dysregulation of immune responses including over-secretion of inflammatory cytokines and imbalances in the proportion of naïve helper T cells, memory helper T cells and regulatory T cells. Identification of the underlying mechanism of such aberrant function of immune system would help in the prediction of disease course and selection of susceptible patients for more intensive cares. In the current review, we summarize the results of studies which reported alterations in cytokine levels and immune cell functions in patients affected with SARS-CoV-2 and related viruses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Forensic DNA Phenotyping (FDP) provides the ability to predict externally visible characteristics from minute amounts of crime scene DNA, which can help find unknown perpetrators who are typically unidentifiable via conventional forensic DNA profiling. Fundamental human genetics research has led to a better understanding of the specific DNA variants responsible for physical appearance characteristics, particularly eye, hair, and skin color. Recently, we introduced the HIrisPlex-S system for the simultaneous prediction of eye, hair, and skin color based on 41 DNA variants generated from two forensically validated SNaPshot multiplex assays using capillary electrophoresis (CE). Here we introduce massively parallel sequencing (MPS) solutions for the HIrisPlex-S (HPS) system on two MPS platforms commonly used in forensics, Ion Torrent and MiSeq, that cover all 41 DNA variants in a single assay, respectively. Additionally, we present the forensic developmental validation of the two HPS-MPS assays. The Ion Torrent MPS assay, based on Ion AmpliSeq technology, illustrated the successful generation of full HIrisPlex-S genotypic profiles from 100 pg of input control DNA, while the MiSeq MPS assay based on an in-house design yielded complete profiles from 250 pg of input DNA. Assessing simulated forensic casework samples such as saliva, hair (bulb), blood, semen, and low quantity touch DNA, as well as artificially damaged DNA samples, concordance testing, and samples from numerous species, all illustrated the ability of both versions of the HIrisPlex-S MPS assay to produce results that motivate forensic applications. By also providing an integrated bioinformatics analysis pipeline, MPS data can now be analyzed and a file generated for upload to the publically accessible HIrisPlex online webtool (https://hirisplex.erasmusmc.nl). In addition, we updated the website to accept VCF input data for those with genome sequence data. We thus provide a user-friendly and semi-automated MPS workflow from DNA sample to individual eye, hair, and skin color prediction probabilities. Furthermore, we present a 2-person mixture separation tool that not only assesses genotype reliability with regards genotyping confidence but also provides the most fitting mixture scenario for both minor and major contributors, including profile separation. We envision this MPS implementation of the HIrisPlex-S system for eye, hair, and skin color prediction from DNA as a starting point for further expanding MPS-based forensic DNA phenotyping. This may include the future addition of SNPs predictive for more externally visible characteristics, as well as SNPs for bio-geographic ancestry inference, provided the statistical framework for DNA prediction of these traits is in place., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Monocyte chemoattractant protein-1-induced protein-1 (MCPIP1) acts as an endonuclease that degrades selected mRNAs, viral RNAs and pre-miRNAs. MCPIP1 inhibits adipogenesis by degradation of C/EBPβ mRNA and adipogenesis-related miRNA, however its role in the regulation of hepatic lipid homeostasis is unknown. In this study, we investigated the role of MCPIP1 in the regulation of lipid metabolism in hepatocytes. C57BL/6 mice were fed a high-fat diet (HFD) for 2-20 weeks and next primary hepatocytes and adipose tissue were isolated. For in vitro experiments we used murine primary hepatocytes, control HepG2 cells and HepG2 with overexpressed or silenced MCPIP1. We found that Mcpip1 levels were lower in primary hepatocytes isolated from HFD-fed mice than in control cells starting at 4 weeks of a HFD. Level of Mcpip1 was also depleted in visceral fat isolated from obese and glucose-intolerant mice characterized by fatty liver disease. We showed that MCPIP1 overexpression in HepG2 cells treated with oleate induces the level and activity of peroxisome proliferator-activated receptor γ (PPARγ). This phenotype was reverted upon silencing of MCPIP1 in HepG2 cells and in primary hepatocytes lacking Mcpip1 protein. MCPIP1 activated the PPARγ transcription factor via the thioredoxin-interacting protein (TXNIP)/peroxisome proliferator-activated receptor γ coactivator 1- α (PGC-1α) pathway. MCPIP1 contributes to lipid metabolism in hepatocytes by regulating the TXNIP/PGC-1α/PPARγ pathway., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Allergic responses to food components are an increasing problem all over the world. It is therefore important to protect people who are vulnerable to food allergens against accidental and unintended consumption of products containing allergic ingredients. The meat industry commonly uses various allergic additives in the production of processed products, such as legumes (soy, peas, beans), milk and egg preparations, cereals containing gluten (wheat, rye, barley and oats), and spices (celery and mustard). These meat additives have specific technological properties, which help to create a texture or flavor profile, or affect the nutritional value, although some of them, such as soy, mustard, milk and egg white proteins, can cause severe allergic reactions. The aim of this paper is to discuss the application of various recently established methods of detection of allergenic additives in processed meat products - for instance cold cuts and sausages. The new methods are based mainly on protein, DNA, and isoflavones or phytic acid analysis. The article also characterizes the latest trends in the development of research on methods that would enable quick and reliable identification of targeted allergens in meat products. © 2018 Society of Chemical Industry., (© 2018 Society of Chemical Industry.)

Shape variation of human head hair shows striking variation within and between human populations, while its genetic basis is far from being understood. We performed a series of genome-wide association studies (GWASs) and replication studies in a total of 28 964 subjects from 9 cohorts from multiple geographic origins. A meta-analysis of three European GWASs identified 8 novel loci (1p36.23 ERRFI1/SLC45A1, 1p36.22 PEX14, 1p36.13 PADI3, 2p13.3 TGFA, 11p14.1 LGR4, 12q13.13 HOXC13, 17q21.2 KRTAP, and 20q13.33 PTK6), and confirmed 4 previously known ones (1q21.3 TCHH/TCHHL1/LCE3E, 2q35 WNT10A, 4q21.21 FRAS1, and 10p14 LINC00708/GATA3), all showing genome-wide significant association with hair shape (P < 5e-8). All except one (1p36.22 PEX14) were replicated with nominal significance in at least one of the 6 additional cohorts of European, Native American and East Asian origins. Three additional previously known genes (EDAR, OFCC1, and PRSS53) were confirmed at the nominal significance level. A multivariable regression model revealed that 14 SNPs from different genes significantly and independently contribute to hair shape variation, reaching a cross-validated AUC value of 0.66 (95% CI: 0.62-0.70) and an AUC value of 0.64 in an independent validation cohort, providing an improved accuracy compared with a previous model. Prediction outcomes of 2504 individuals from a multiethnic sample were largely consistent with general knowledge on the global distribution of hair shape variation. Our study thus delivers target genes and DNA variants for future functional studies to further evaluate the molecular basis of hair shape in humans., (© The Author(s) 2017. Published by Oxford University Press.)

Background: Proteins enzymatic digestion is a very complex process, during which some components are degraded, whereas others remain in an unchanged form. Moreover, enzymatic hydrolysis is one of the most popular methods used to reduce the allergenicity of food proteins. In the present study, the efficiency of enzymatic hydrolysis of lupin seed proteins was assessed by proteomic analysis as performed by two-dimensional gel electrophoresis (2-DE) coupled with mass spectrometry identification. Two digestion systems were used: oriented digestion carried out by trypsin and model in vitro digestion mimicking the conditions present in the gastrointestinal tract., Results: The comparisons of 2-DE maps of proteins isolated form different lupin seed species revealed that the differences in proteins expression were observed mainly in the central parts of gels (i.e. in the molecular weight range from 20 to 70 kDa, and the pH range 5-7). In total, 27 differentially expressed proteins spots were successfully identified by mass spectrometry analysis. An important reduction in the number of proteins spots on 2-DE maps was observed when trypsin and the in vitro digestion model were applied. The protein spot insensitive to digestion in both hydrolysis systems was identified as β-conglutin., Conclusions: The results of the present study provide insight into the nature of the digestion process that may take place after lupin seed protein intake and highlight the important fact that some of the proteins are insensitive to digestive enzyme activity. Moreover, evaluation of digestion activity of trypsin towards lupin seed proteins may be used for the development of specific processes with respect to hypoallergenic food production. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

This study investigated the impact of packaging systems on the degradation and oxidation of beef proteins regarding beef tenderness of longissimus lumborum (LL) and biceps femoris (BF) muscles stored in vacuum skin packaging (VSP), a modified atmosphere with high oxygen concentration (MAP), and combined of these two methods (VSP+MAP). A significant decrease in the Warner-Bratzler shear force (WBSF) in VSP at D14 and D28 for LL was observed compared to BF. A significant effect of packaging system on troponin-T (Tn-T) and desmin degradation was shown (p≤0.001). A high concentration of oxygen in MAP and VSP+MAP affected protein oxidation, which was reflected in myosin oxidative cross-linking. An increase of WBSF values detected in steaks packed in VSP and VSP+MAP systems could be caused by the intensification of protein oxidation. Furthermore, BF was more susceptible to oxidation compared to LL. The VSP+MAP packaging system has resulted in the maintenance of a bright, red color, however has not improved the beef tenderness., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Human skin colour is highly heritable and externally visible with relevance in medical, forensic, and anthropological genetics. Although eye and hair colour can already be predicted with high accuracies from small sets of carefully selected DNA markers, knowledge about the genetic predictability of skin colour is limited. Here, we investigate the skin colour predictive value of 77 single-nucleotide polymorphisms (SNPs) from 37 genetic loci previously associated with human pigmentation using 2025 individuals from 31 global populations. We identified a minimal set of 36 highly informative skin colour predictive SNPs and developed a statistical prediction model capable of skin colour prediction on a global scale. Average cross-validated prediction accuracies expressed as area under the receiver-operating characteristic curve (AUC) ± standard deviation were 0.97 ± 0.02 for Light, 0.83 ± 0.11 for Dark, and 0.96 ± 0.03 for Dark-Black. When using a 5-category, this resulted in 0.74 ± 0.05 for Very Pale, 0.72 ± 0.03 for Pale, 0.73 ± 0.03 for Intermediate, 0.87±0.1 for Dark, and 0.97 ± 0.03 for Dark-Black. A comparative analysis in 194 independent samples from 17 populations demonstrated that our model outperformed a previously proposed 10-SNP-classifier approach with AUCs rising from 0.79 to 0.82 for White, comparable at the intermediate level of 0.63 and 0.62, respectively, and a large increase from 0.64 to 0.92 for Black. Overall, this study demonstrates that the chosen DNA markers and prediction model, particularly the 5-category level; allow skin colour predictions within and between continental regions for the first time, which will serve as a valuable resource for future applications in forensic and anthropologic genetics.

New approaches to rapid examination of proteins and peptides in complex food matrices are of great interest to the community of food scientists. The aim of the study is to examine the influence of microwave irradiation on the acceleration of enzymatic cleavage and enzymatic digestion of denatured proteins in cooked meat of five species (cattle, horse, pig, chicken and turkey) and processed meat products (coarsely minced, smoked, cooked and semi-dried sausages). Severe protein aggregation occurred not only in heated meat under harsh treatment at 190 °C but also in processed meat products. All the protein aggregates were thoroughly hydrolyzed after 1 h of trypsin treatment with short exposure times of 40 and 20 s to microwave irradiation at 138 and 303 W. There were much more missed cleavage sites observed in all microwave-assisted digestions. Despite the incompleteness of microwave-assisted digestion, six unique peptide markers were detected, which allowed unambiguous identification of processed meat derived from the examined species. Although the microwave-assisted tryptic digestion can serve as a tool for rapid and high-throughput protein identification, great caution and pre-evaluation of individual samples is recommended in protein quantitation.

The research was carried out on 32 crossbred pigs of Polish Large White × Danish Landrace with Duroc and 80 rams, crossbreds of the Prolific-Dairy Koludzka Sheep with the Ile de France, a meat sheep. The fodder for the animals was enriched with the unsaturated fatty acids originated mainly from linseed and rapeseed oils. The fatty acid profile was determined in cooked longissimus lumborum, roasted triceps brachii and raw ripened rump from pigs as well as in grilled lambs' legs and their corresponding raw materials. Roasting caused the most pronounced increase of the saturated fatty acids and decrease in the polyunsaturated fatty acids of heated pork muscles. The smallest changes were observed in grilled lamb legs. The heating processes applied in this study, in most cases, did not cause essential changes in the indices of pro-health properties of fatty acid, therefore meat in the majority fulfil the latest recommendations of EFSA and FAO/WHO according to human health.

The aim was to search for proteins differentiating the six species (cattle, pig, chicken, turkey, duck and goose) and relatively stable during the meat aging and only slightly degraded in ready-made products. The two-dimensional electrophoresis was used for analysis of the protein profiles from raw meat and frankfurters and sausages (15 products). The observed species-specific differences in protein expression in raw meat were retained in processed products after finishing the entire technological process. Regulatory proteins, metabolic enzymes, some myofibrillar and blood plasma proteins were identified, which were characterised by the electrophoretic mobility specific to the given species. Large differences in the primary structure were observed in serum albumin, apolipoprotein B, HSP27, H-FABP, ATP synthase, cytochrome bc-1 subunit 1 and alpha-ETF. Some of these proteins have potential to be used as markers in authentication of meat products., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Investigation of protein changes as well as authentication of meat is particularly difficult in processed meat products due to their different composition, complexity and very often inhomogeneity. The aim of this study was to check if the inter-species differences in the expression of myosin light chain (MLC) isoforms observed in raw meat were retained in meat products. MLCs from mixtures of minced meat (16 variants), frankfurters and sausages (15 products) made from cattle, pig, chicken, turkey, duck and goose were analysed by 2DE. Species-specific patterns of MLC isoforms were observed in all the mixtures and processed meat products. Relatively small degradation was observed in the MLCs after processing. Image analysis enabled species identification of the meat in all samples when the content of meat of one species was not lower than 10%. However, it was impossible to differentiate between all the six species under investigation on the basis of individual isoform. It was possible when the combination of all the three isoforms (myosin light chain 1 fast, myosin light chain 2 fast and myosin light chain 3 fast) was analysed. The results evidenced that MLCs have potential to be used as markers in authentication of meat products made from the analysed six species., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Authentication of regional and traditional food made of meat poses a significant challenge. It continues to be a very difficult task which requires employment of quite advanced analytical techniques. These products, despite a similar process of manufacturing, differ in taste and aroma. This happens due to the use of special breeds of animals, the application of appropriate feeding regimes as well as the effect of the place and climate. In order to perform correct identification of geographical origin, a good solution is to determine both stable isotopes as well as trace elements. It is essential to collect detailed meteorological and geochemical data and information about farming practices and to compare them with the obtained results. In a majority of cases, the performed identification is confined to species and the determination of the animal breed is very limited. In the case of individual breeds a comparative analysis of SNPs appears to present the highest potential, especially genes affecting the coat color of animals may serve as markers. Experiments confirm that genes responsible for pigmentation underwent mutations in individual breeds. Authentication on the basis of the manufacturing process appears to be easier to realize than tracing geographical origins.

Background: In this study the interspecies differences in two-dimensional electrophoresis patterns of skeletal muscle myosin light chain (MLC) isoforms between Bos taurus (cattle), Sus scrofa (pig), Gallus gallus (chicken), Meleagris gallopavo (turkey), Anas platyrhynchos (duck) and Anser anser (goose) were characterised on the basis of specific properties of MLCs associated with their structure and mobility in gel., Results: Two-dimensional electrophoresis separations revealed species-specific differences in the molecular weight and pI of individual MLC isoforms (MLC1f, MLC2f and MLC3f). In the case of closely related animal species such as goose and duck or turkey and chicken, significant differences occurred in MLC1f. For MLC2f, differences between cattle and turkey and between pig and chicken were around 1 and 0.3 kDa respectively. It appeared from the comparison of amino acid sequences that even MLCs with only 2% difference in sequences have different electrophoretic mobilities., Conclusion: Interspecies differences in skeletal MLC isoforms appeared between cattle, pig, chicken, turkey, duck and goose. The slight changes observed in the course of the aging process confirmed that these proteins are relatively little susceptible to proteolytic enzymes during meat aging., (Copyright © 2011 Society of Chemical Industry.)

The objective of this study was to estimate the impact of the polymorphism of μ-calpain (CAPN1S) gene on protein changes of the cattle muscle tissue and its tenderness during 10-day cold storage. The analysis was performed on the longest dorsal and lumbar muscles collected from 76 bulls 6 to 12 months of age. Polymorphism identification of the above-mentioned gene was conducted using the PCR-RFLP technique. Its effect on the course of the proteolysis process was assessed by monitoring changes in proportions of tissue proteins during 10-day process of meat ageing. Special attention was focused on changes in native titin (T1) share and products of its degradation (proteins of molecular weight (m.w.) of 2400 and 200 kDa), α-actinin and protein of 37 kDa as well as myosin heavy chains (MHC). In the case of the last proteins, their polymorphism was evaluated as well. Meat tenderness was estimated measuring the value of shear force and sensorially. The highest tenderness was ascertained for the heterozygote. Its improvement was associated with a significant decrease in proportions of proteins of molecular weight of approximately 37 kDa accompanied by an increase of those with 200 kDa molecular weight. Muscles derived from cattle of CT genotype were characterised by the highest proportions of type 2a MHC isoform. Value differences between proportions determined for the heterozygote and CC and TT homozygotes of the CAPN1S gene were statistically significant. Therefore, it can be presumed that the process of meat tenderisation was especially connected with MHC polymorphism.

Changes occurring during post-mortem ageing in structure of psoas major and minor (PM) and semitendinosus (ST) muscles of calves, heifers and cows were observed. Samples from muscles taken 3 h after slaughter and after 6 and 12 days of storage at the temperature of 4 °C were analysed using light and transmission electron microscopy. Three hours after slaughter muscle fibres were close to each other and sarcomeres showed normal structure of A- and I-bands, M-lines and Z-disks. The space between myofibrils and sarcolemma and also between single myofibrils in muscle fibres increased during storage. Structure of sarcomeres underwent continuous degradation, length of sarcomeres increased due to enlargement of I-bands accompanied by Z-disk degradation. During ageing structural changes in myofibrils took place faster, were more intensive in muscles of younger animals and were more extensive and faster in PM than in ST muscles.

Changes in myofibrillar protein content and centrifugal drip proteins of psoas major and minor (PM) and semitendinosus (ST) muscles of calves, heifers and cows taken from carcasses on the 1st, 6th and 12th day of post-mortem cold storage were estimated. Washed myofibrils and centrifugal drip from muscles were analysed using SDS-PAGE 10 and 12% polyacrylamide gels. No significant changes were observed in content of contractile proteins, α-actinin and regulatory proteins (except for TN-T). There were no significant differences between muscles from investigated groups and between muscles aged in chilled conditions. The levels of titin T1 during ageing varied slightly. The 30 kDa-fraction appearance was fastest in calf, slower in heifer and slowest in cow muscles. More pronounced differences in the level of protein degradation with regards to muscle type, age of animals and time of storage were found in the centrifugal drip of meat. In the drip, the level of high molecular weight proteins was higher in muscles from young animals and in the muscles stored longer. The opposite was observed in case of 26-28 kDa proteins. Their amount in muscle drip decreased with increased storage time. The rate of proteolysis and release of cytoskeletal proteins during cold storage of muscles were related to change in shear values of roasted meat. The highest rate of protein degradation was observed in PM calf muscle and the lowest rate in ST cow muscle. The fastest tenderization process was registered in calves muscles and the slowest tenderization in cows.

The thermal properties of titin isolated from porcine and bovine longissimus muscles were investigated by differential scanning calorimetry in the temperature range from 20 to 100 °C. A single peak with average maximum temperatures of 75.6 and 78.4 °C characterized porcine and bovine titin denaturation, respectively. The peaks were much broader than those from the other major muscle proteins. Titin denaturation enthalpy values (1.6-2.6 J/g) were only about half those of whole meat and also lower than those previously determined for myosin, actin, or collagen. The relatively high titin denaturation temperature suggests that it may be partially responsible for meat toughening when muscle tissue is heated above 60 °C.

The aim of the research was to determine water binding and holding capacity and to measure the force and work of penetration of minced pork and beef cured with brine of varying concentrations of sodium chloride and lactic acid and then heated. M. biceps femoris was cut out from chilled pork and beef carcasses three times from each species. Minced meat was subjected to curing. Each of the 20 experimental treatments resulted from appropriate combinations of salt (0.0-2.0%) and lactic acid (0.0-1.5%). The individual concentrations of these two compounds differed by 0.5%. The addition of the curing brine containing only sodium chloride or only lactic acid caused an increase of water holding and binding capacity. The additions of curing brines containing various concentrations of mixtures of salt and acid cause lowering of water holding and binding capacity. Higher penetration force and work had to be applied for pork than for beef samples. With the increase of salt and lactic acid concentrations applied together, after the initial increase of the penetration force and work, their values were found to decrease at higher concentrations of mixtures of these substances in meat.