Isolation, identification, and preparation of tyrosinase inhibitory peptides from Pinctada martensii meat.

Recently, natural tyrosinase inhibitors have gained attention in clinical cosmetology research. In this study, the enzymatic hydrolysis of Pinctada martensii meat by protease from Bacillus licheniformis, 401 peptides with tyrosinase inhibitory were identified after isolated by ultrafiltration and Sephadex G-15 from the fraction F4. The peptide effects on the tyrosinase activity and structure were evaluated using molecular docking. Three synthetic peptides classified as W1 (WDRPKDDGGSPIK), W2 (DRGYPPVMF), and W3 (SGGGGGGGLGSGGSIRSSY), which had the lowest binding energies were selected for in vitro synthesis and biological activity investigation. The W3 peptide (5 mg/mL) had the highest tyrosinase activity, SPF, DPPH, and ABTS clearance values, and total antioxidant capacity. W3 did not affect the survival rate of mouse melanoma B16-F10 cells (1.0-5.0 mg/mL) but decreased the melanin content. Hence, W3 could be suitable for multifunctional tyrosinase inhibition and provides a novel method to use marine organisms as natural tyrosinase inhibitor sources.

Sapap4 deficiency leads to postsynaptic defects and abnormal behaviors relevant to hyperkinetic neuropsychiatric disorder in mice.

Postsynaptic proteins play critical roles in synaptic development, function, and plasticity. Dysfunction of postsynaptic proteins is strongly linked to neurodevelopmental and psychiatric disorders. SAP90/PSD95-associated protein 4 (SAPAP4; also known as DLGAP4) is a key component of the PSD95-SAPAP-SHANK excitatory postsynaptic scaffolding complex, which plays important roles at synapses. However, the exact function of the SAPAP4 protein in the brain is poorly understood. Here, we report that Sapap4 knockout (KO) mice have reduced spine density in the prefrontal cortex and abnormal compositions of key postsynaptic proteins in the postsynaptic density (PSD) including reduced PSD95, GluR1, and GluR2 as well as increased SHANK3. These synaptic defects are accompanied by a cluster of abnormal behaviors including hyperactivity, impulsivity, reduced despair/depression-like behavior, hypersensitivity to low dose of amphetamine, memory deficits, and decreased prepulse inhibition, which are reminiscent of mania. Furthermore, the hyperactivity of Sapap4 KO mice could be partially rescued by valproate, a mood stabilizer used for mania treatment in humans. Together, our findings provide evidence that SAPAP4 plays an important role at synapses and reinforce the view that dysfunction of the postsynaptic scaffolding protein SAPAP4 may contribute to the pathogenesis of hyperkinetic neuropsychiatric disorder.

SAPAP Scaffold Proteins: From Synaptic Function to Neuropsychiatric Disorders.

Excitatory (glutamatergic) synaptic transmission underlies many aspects of brain activity and the genesis of normal human behavior. The postsynaptic scaffolding proteins SAP90/PSD-95-associated proteins (SAPAPs), which are abundant components of the postsynaptic density (PSD) at excitatory synapses, play critical roles in synaptic structure, formation, development, plasticity, and signaling. The convergence of human genetic data with recent in vitro and in vivo animal model data indicates that mutations in the genes encoding SAPAP1-4 are associated with neurological and psychiatric disorders, and that dysfunction of SAPAP scaffolding proteins may contribute to the pathogenesis of various neuropsychiatric disorders, such as schizophrenia, autism spectrum disorders, obsessive compulsive disorders, Alzheimer's disease, and bipolar disorder. Here, we review recent major genetic, epigenetic, molecular, behavioral, electrophysiological, and circuitry studies that have advanced our knowledge by clarifying the roles of SAPAP proteins at the synapses, providing new insights into the mechanistic links to neurodevelopmental and neuropsychiatric disorders.

Social insurance and earnings management: Too rich to be good.

We examine the relationship between social insurance contributions and earnings management for publicly listed firms in China. Our empirical results show that the social insurance contributions burden significantly reduces the degree of earnings management by reducing the level of free cash flow. Additionally, the negative relation between social insurance contributions burden and earnings management is more pronounced when the internal and external social insurance pressures are high and when the firms are large non-state-owned enterprises. We also discuss the heterogeneity among firms for different financing constraints, external financing environment, regional marketization, and internal and external corporate governance. Finally, we further find that under the dual collecting system, although the social security administration is a better collecting agency, the local tax bureau acting with full responsibility is more effective than the collecting system.

Spatiotemporal patterns of gliosis and neuroinflammation in presenilin 1/2 conditional double knockout mice.

Increasing evidence indicates that neuroinflammation contributes to and exacerbates the pathogenesis of Alzheimer's disease (AD). Neuroinflammation is thought to be primarily driven by glial cells (microglia and astrocytes) and escalates with neurodegenerative progression in AD. However, the spatiotemporal change patterns of glial reactivity and neuroinflammatory response during different stages of neurodegeneration, especially early in disease, remain unknown. Here we found that gliosis and the up-regulation of substantial neuroinflammatory genes were primarily initiated in the cortex of presenilin 1/2 conditional double knockout (cDKO) mice, rather than in the hippocampus. Specifically, astrocyte activation preceding microglial activation was found in the somatosensory cortex (SS) of cDKO mice at 6 weeks of age. Over time, both astrocyte and microglial activation were found in the whole cortex, and age-related increases in gliosis activation were more pronounced in the cortex compared to hippocampus. Moreover, the age-associated increase in glial activation was accompanied by a gradual increase in the expression of cell chemokines Ccl3 and Ccl4, complement related factors C1qb, C3 and C4, and lysosomal proteases cathepsin S and Z. These findings suggest that astrocyte and microglial activation with a concurrent increase in inflammatory mediators such as chemokines might be an early event and contribute to the pathogenesis of neurodegeneration due to presenilin deficiency.

Characterization of Key Aroma Compounds in Fermented Bamboo Shoots Using Gas Chromatography-Olfactometry-Mass Spectrometry, Odor Activity Values, and Aroma Recombination Experiments.

Guangxi fermented bamboo shoots (GFBS) are widely appreciated by consumers in China because of their unique aroma. In this study, the dominant aroma compounds of GFBS were investigated using gas chromatography-olfactometry-mass spectrometry, odor-activity values, and aroma recombination. The results show that 70 aroma compounds, including alcohols, esters, aldehydes, acids, phenols, ethers, ketones, alkenes, benzene derivatives, and furans, were identified in GFBS. Among them, 15 aroma compounds with odor-activity values (OAVs) > 1 were identified. Aroma-recombination-omission experiments and sensory evaluation demonstrated that octanal, (E)-2-octenal, acetic acid, guaiacol, phenylethyl alcohol, creosol, 4-ethylguaiacol, and p-cresol significantly contributed to the characteristic aroma of GFBS. Most importantly, p-cresol (34,997.95 ≤ OAV ≤ 71,409.51) and acetic acid (2155.79 ≤ OAV ≤ 3872.09) significantly contributed to its aroma (p < 0.001). The major aroma profile of GFBS included a strong fermented odor, which was pungent and sour. This study provides a theoretical basis for improving the flavor of GFBS.

Recent advances in microbial ε-poly-L-lysine fermentation and its diverse applications.

The naturally occurring homo-polyamide biopolymer, ε-poly-L-lysine (ε-PL) consists of 25-35 L-lysine residues with amide linkages between α-carboxyl groups and ε-amino groups. ɛ-PL exhibits several useful properties because of its unusual structure, such as biodegradability, water solubility, no human toxicity, and broad-spectrum antibacterial activities; it is widely applied in the fields of food, medicine, clinical chemistry and electronics. However, current industrial production of ε-PL is only performed in a few countries. Based on an analysis of the physiological characteristics of ε-PL fermentation, current advances that enhance ε-PL fermentation, from strain improvement to product isolation are systematically reviewed, focusing on: (1) elucidating the metabolic pathway and regulatory mechanism of ε-PL synthesis; (2) enhancing biosynthetic performance through mutagenesis, fermentation optimization and metabolic engineering; and (3) understanding and improving the biological activity and functional properties of ε-PL. Finally, perspectives on engineering and exploiting ε-PL as a source material for the production of various advanced materials are also discussed, providing scientific guidelines for researchers to further improve the ε-PL fermentation process.

META analysis on the effect of taijiquan on improving negative psychological symptoms of college students and the optimal dose.

Background: Taijiquan, as a physical and mental exercise, can improve the negative psychology of college students. However, it is still controversial, and the optimal exercise dose of taijiquan to interfere with negative psychology has not been evaluated. Objective: This study is aimed at systematically evaluating the effect of taijiquan therapy on improving negative psychological symptoms of college students and its optimal intervention dose. Methods: Search databases such as Web of Science, Embase, PubMed, CNKI, WFSD, etc. Collect high-quality relevant RCT studies. After screening, extracting, coding and counting the data, a META analysis is done through Review Manage 5.3 and Stata 15.0 software. PICOS established the eligibility criteria to select the studies as follows: (i) population - non-clinical of college students; (ii) intervention - taijiquan intervention; (iii) comparison - taijiquan intervention group and regular physical activity group; (iv) outcomes - depression, anxiety; and (v) study design - randomized controlled trial. Results: A total of 12 articles and 1,000 samples were included. All of the participants are college students. Taijiquan therapy can significantly reduce the depression and anxiety symptoms of college students [SMD = -0.53, 95% CI (-0.82, -0.23)], [SMD = -0.49, 95% CI (-0.90, -0.09)], with statistical significance (P < 0.05). Subgroup analysis shows that: there is a precise focus on depression and anxiety symptoms. The intervention period is more than 12 weeks, and the best effect appears when people practice 3 times a week. The best single intervention time for depression symptoms is 60 min, and for anxiety symptoms 80-90 min. It is found that taijiquan combined with mindfulness intervention can significantly reduce negative psychological symptoms like depression and anxiety of college students than single taijiquan intervention. Funnel plot combined with sensitivity analysis, Begg, Egger test showed no publication bias. Conclusion: Taijiquan intervention can effectively improve the negative psychological symptoms of college students, and it has great promotion value in colleges and universities. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022314071.

Production and identification of peptides with activity promoting osteoblast proliferation from meat dregs of Pinctada martensii.

As a by-product of pearl production, Pinctada martensii meat dregs have a high level of protein but cannot be fully utilized. In this study, P. martensii meat dregs were first hydrolyzed by three pepsin enzymes, resulting in neutral proteinase enzymatic hydrolysate that had a higher effect on stimulating the proliferation of MC3T3-E1 cells, and cell proliferation increases of 37.37 ± 0.03%. Subsequently, after purification of alcohol precipitation, ultrafiltration, and Superdex G-25 gel chromatography, five fractions were further separated and purified in which fraction ZP2 could effectively improve cell proliferation induced an increase of 43.95 ± 0.03% in MC3T3-E1 cells growth. Consequently, with the help of alkaline phosphatase and methyl thiazolyl tetrazolium assay, five novel peptides (FDNEGKGKLPEEY, FWDGRDGEVDGFK, VLQTDNDALGKAK, IVLDSGDGVTH, and MVAPEEHP) derived from fraction ZP2 with the strongest osteogenic activity were screened, and their sequences were identified using Orbitrap Fusion Lumos Tribrid Orbital liquid chromatography-mass spectrometry. Therefore, the research results demonstrated that P. martensii meat could be used as a promising material for producing food additives for improving osteoporosis. PRACTICAL APPLICATIONS: In this study, after enzymolysis and purification, the fraction ZP2, derived from Pinctada martensii meat dregs were found to have a better activity of promoting osteoblast proliferation, showing the higher osteogenic activity with an increase of 43.95 ± 0.03% in terms of cell proliferation. It is beneficial to realize the high value and resource utilization of P. martensii meat dregs as a by-product of pearl production. The research demonstrated that the meat dregs of P. martensii could be used as an attractive material for producing active peptides in functional foods. In addition, the molecular weight of the peptides we identified from the ZP2 fraction is suitable for the proliferation of MC3T3-E1 cells, which lays a foundation for the further synthesis of peptides that promote the high proliferation activity of osteocytes.

Production of welan gum from cane molasses by Sphingomonas sp. FM01.

As an extracellular exopolysaccharide, welan gum could serve as a suspending agent, stabilizer, emulsifier and thickener with characteristics that include bio-adhesion, non-toxicity, biocompatibility and biodegradability. In this study, Sphingomonas sp. FM01 was applied to effectively produce welan gum using cane molasses as the carbon source. After pretreatment with phosphoric acid and polyacrylamide, 60 g/L cane molasses combined with 6.0 g/L beef extract, 3 g/L KH2PO4, 0.5 g/L MgSO4, 15 mmol/L H2O2 and 4 mg/L niacin significantly improved the fermentation performance of Sphingomonas sp. FM01, increasing the production of welan gum to 37.65 g/L. Investigation of the rheological behavior of the welan gum obtained from the molasses-welan gum mixture showed it had an acceptable molecular weight and similar rheological properties and better viscosity stability compared to that obtained from sucrose, indicating that cane molasses could be explored as a suitable and inexpensive substrate for cost-effective welan gum production.

Extracting bio-zinc and taurine from Pinctada martensii meat.

Recently, intensive processing of marine resources has attracted considerable attention. In order to further utilize the byproducts of aquatic shellfish (Pinctada martensii meat) with high value, this study proposes a method of extracting zinc and taurine from P. martensii meat. Zinc was first extracted from P. martensii meat with an ultrasonic crusher, and then taurine was further extracted by ultrasonic-assisted water extraction from the remaining shellfish. After optimization, the biological zinc extraction rate reached 8.63%, and the taurine extraction rate reached 0.71%. Meanwhile, the parameters for cation exchange separation and taurine purification were optimized, in which the injection volume, pH value, and elution rate were set to 8.0 mL, 4.5, and 3.0 mL/min, respectively. Ultimately, the purity the extracted taurine reached 98.16%. This study provides a novel method for the extraction of biological zinc and taurine by deep processing of shellfish meat.