Regulating effects of low salt dry-curing pre-treatment on microbiota, biochemical changes and flavour precursors of grass carp (Ctenopharyngodon idella) fillets during storage at 4 °C.

Low salt dry-curing (LSD), as a healthier pre-treatment for the preservation of fishery products, is a potential technique substitute for excessively salty curing. The regulatory effects of 2 % and 3 % LSD on the quality evolution through an intrinsic correlation between microbiota succession and flavour precursors of refrigerated grass carp fillets were investigated in this study. The results showed that the LSD pre-treatment was effective in promoting proteolysis, free amino acid and fatty acid metabolism with the microbiota succession and quality evolution. Compared with unpre-treated samples, the 3 % LSD pre-treatment effectively extended the shelf life by 10 days within the acceptable quality attributes. Not only did the LSD pre-treatment lead to catalytic microbiota succession and inhibitive spoilage substance production but it also improved the flavour precursors, which are taste-active amino acids and polyunsaturated fatty acids (PUFAs). Moreover, considerable correlations between quality attributes, taste-active amino acids, PUFAs and microbiota were obtained.

An Integrated Method of Biomechanics Modeling for Pelvic Bone and Surrounding Soft Tissues.

The pelvis and its surrounding soft tissues create a complicated mechanical environment that greatly affects the success of fixing broken pelvic bones with surgical navigation systems and/or surgical robots. However, the modeling of the pelvic structure with the more complex surrounding soft tissues has not been considered in the current literature. The study developed an integrated finite element model of the pelvis, which includes bone and surrounding soft tissues, and verified it through experiments. Results from the experiments showed that including soft tissue in the model reduced stress and strain on the pelvis compared to when it was not included. The stress and strain distribution during pelvic loading was similar to what is typically seen in research studies and more accurate in modeling the pelvis. Additionally, the correlation with the experimental results from the predecessor's study was strong (R2 = 0.9627). The results suggest that the integrated model established in this study, which includes surrounding soft tissues, can enhance the comprehension of the complex biomechanics of the pelvis and potentially advance clinical interventions and treatments for pelvic injuries.

Methionine restriction constrains lipoylation and activates mitochondria for nitrogenic synthesis of amino acids.

Methionine restriction (MR) provides metabolic benefits in many organisms. However, mechanisms underlying the MR-induced effect remain incompletely understood. Here, we show in the budding yeast S. cerevisiae that MR relays a signal of S-adenosylmethionine (SAM) deprivation to adapt bioenergetic mitochondria to nitrogenic anabolism. In particular, decreases in cellular SAM constrain lipoate metabolism and protein lipoylation required for the operation of the tricarboxylic acid (TCA) cycle in the mitochondria, leading to incomplete glucose oxidation with an exit of acetyl-CoA and α-ketoglutarate from the TCA cycle to the syntheses of amino acids, such as arginine and leucine. This mitochondrial response achieves a trade-off between energy metabolism and nitrogenic anabolism, which serves as an effector mechanism promoting cell survival under MR.

Enzymolysis Reaction Kinetics and Liquid Chromatography High-Resolution Mass Spectrometry Analysis of Ovalbumin Glycated with Microwave Radiation.

Microwave radiation was adopted to accelerate glycation between ovalbumin (OVA) and d-glucose. We evaluated the digestibility of glycated OVA from the perspective of kinetics, using pepsin and trypsin as model enzymes. Hydrolysed protein concentrations, enzymolysis kinetics, and activation energy (Ea) were investigated. The results showed that, under the conditions of simulating human digestion, the hydrolysis rate of OVA by pepsin was faster than that by trypsin, but for digestive enzymes, the digestion efficiency of OVA hydrolyzed by trypsin was higher. It was found that the rate constant of enzymatic hydrolysis of OVA was independent of the initial concentration of OVA but related to the type of protease and temperature. The reaction rate constants of glycated OVAs were significantly higher than that of native OVA during enzymolysis. Ea required for glycated OVA enzymatic hydrolysis by pepsin decreased, while that required by trypsin enzymatic hydrolysis nearly doubled. Liquid chromatography high-resolution mass spectrometry revealed that sample 1 had three glycated sites (R111, K227, and K264), sample 2 had two glycated sites (K207 and K323), sample 3 had five glycated sites (R127, R159, K227, R340, and K370), sample 4 had three glycated sites (R85, R143, and K323), and sample 5 had two glycated sites (R51 and R59). These sites increased Ea required for enzymatic hydrolysis of glycated OVA by trypsin.