Do wearing masks and preservatives have a combined effect on skin health?

Chemical exposure and local hypoxia caused by mask-wearing may result in skin physiology changes. The effects of methylparaben (MeP), a commonly used preservative in personal care products, and hypoxia on skin health were investigated by HaCaT cell and ICR mouse experiments. MeP exposure resulted in lipid peroxidation and interfered with cellular glutathione metabolism, while hypoxia treatment disturbed phenylalanine, tyrosine, and tryptophan biosynthesis pathways and energy metabolism to respond to oxidative stress. A hypoxic environment increased the perturbation of MeP on the purine metabolism in HaCaT cells, resulting in increased expression of proinflammatory cytokines. The synergistic effects were further validated in a mouse model with MeP dermal exposure and "mask-wearing" treatment. CAT, PPARG, and MMP2 were identified as possible key gene targets associated with skin health risks posed by MeP and hypoxia. Network toxicity analysis suggested a synergistic effect, indicating the risk of skin inflammation and skin barrier aging.

High-throughput profiling of RNA modifications by ultra-performance liquid chromatography coupled to complementary mass spectrometry: Methods, quality control, and applications.

Although next-generation sequencing technology has been used to delineate RNA modifications in recent years, the paucity of appropriate converting reactions or specific antibodies impedes the accurate characterization and quantification of numerous RNA modifications, especially when these modifications demonstrate wide variations across developmental stages and cell types. In this study, we developed a high-throughput analytical platform coupling ultra-performance liquid chromatograph (UPLC) with complementary mass spectrometry (MS) to identify and quantify RNA modifications in both synthetic and biological samples. Sixty-four types of RNA modifications, including positional isomers and hypermodified ribonucleosides, were successfully monitored within a 16-min single run of UPLC-MS. Two independent methods to cross-validate the purity of RNA extracted from Caenorhabditis elegans (C. elegans) were developed using the coexisting C. elegans and Escherichia coli (E. coli) as a surveillance system. To test the validity of the method, we investigated the RNA modification landscape of three model organisms, C. elegans, E. coli, and Arabidopsis thaliana (A. thaliana). Both the identity and molarity of modified ribonucleosides markedly varied among the species. Moreover, our platform is not only useful for exploring the dynamics of RNA modifications in response to environmental cues (e.g., cold shock) but can also help with the identification of RNA-modifying enzymes in genetic studies. Cumulatively, our method presents a novel platform for the comprehensive analysis of RNA modifications, which will be of benefit to both analytical chemists involved in biomarker discovery and biologists conducting functional studies of RNA modifications.

Xanthine-derived reactive oxygen species exacerbates adipose tissue disorders in male db/db mice induced by real-ambient PM2.5 exposure.

Epidemiological and experimental data have associated exposure to fine particulate matter (PM2.5) with various metabolic dysfunctions and diseases, including overweight and type 2 diabetes. Adipose tissue is an energy pool for storing lipids, a necessary regulator of glucose homeostasis, and an active endocrine organ, playing an essential role in developing various related diseases such as diabetes and obesity. However, the molecular mechanisms underlying PM2.5-impaired functions in adipose tissue have rarely been explored. In this work, metabolomics based on liquid chromatography-mass spectrometry was performed to study the adverse impacts of PM2.5 exposure on brown adipose tissue (BAT) and white adipose tissue (WAT) in the diabetic mouse model. We found the effects of PM2.5 exposure by comparing the different metabolites in both adipose tissues of male db/db mice using real-ambient PM2.5 exposure. The results showed that PM2.5 exposure changed the purine metabolism in mice, especially the dramatic increase of xanthine content in both WAT and BAT. These changes led to significant oxidative stress. Then the results from real-time quantitative polymerase chain reaction showed that PM2.5 exposure could cause the production of inflammatory factors in both adipose tissues. Moreover, the increased reactive oxygen species (ROS) promoted triglyceride accumulation in WAT and inhibited its decomposition, causing increased WAT content in db/db mice. In addition, PM2.5 exposure significantly suppressed thermogenesis and affected energy metabolism in the BAT of male db/db mice, which may deteriorate insulin sensitivity and blood glucose regulation. This research demonstrated the impact of PM2.5 on the adipose tissue of male db/db mice, which may be necessary for public health.

Changes in texture, rheology and volatile compounds of golden pomfret sticks inoculated with Shewanella baltica during spoilage.

Shewanella baltica has a high spoilage ability to decompose nutrients in fish. To investigate the role of S. baltica in fish protein and flavour during spoilage, the texture, rheology, protein patterns and volatile compounds of golden pomfret inoculated with S. baltica during 10-day storage were tested. During storage, S. baltica reduced the hardness of fish sticks by 29.73-49.24 %. Compared to the control (G0': 20.27 ± 2.15 kPa), inoculated samples showed lower moduli (G0': 16.71 ± 0.82-17.50 ± 1.80 kPa). Their myosin heavy chains, myosin-binding protein C and actin were decomposed into smaller proteins, which was validated by the lower intensities of molecules with Mw 160-176 kDa. Furthermore, S. baltica generated volatile spoilage markers, including dimethyl sulfide, 2-methyl-butanal and 3-methyl-butanal. This study reveals the mechanism of fish texture and flavour changes induced by S. baltica, and provides insights into controlling bacterial spoilage of seafood.

NMR-based metabolomics reveals the antibacterial effect of electrolysed water combined with citric acid on Aeromonas spp. in barramundi (Lates calcarifer) fillets.

The citric acid (CA) and electrolysed water (EW) are considered effectively in inactivating microorganisms. The objective of this study was to explore the bactericidal mechanism of CA combined with EW on Aeromonas spp. in barramundi (Lates calcarifer) by in vitro metabolomics method. This study determined the survival population of three strains of Aeromonas bacteria (strain 1: Aeromonas salmonicida strain A1 (skin); strain 2: A. veronii strain Til2 (gut), and strain 3: A. hydrophila strain B11 (gill)), which were isolated and identified from putrid barramundi treated alone or in combination with 1 % CA and EW (free available chlorine (FAC) 25 mg/L, pH 3.23, oxidation-reduction potential (ORP) 1015 mV). The bactericidal mechanism was investigated by microbiological analysis, nuclear magnetic resonance (NMR), multivariate data analysis, and fluorescence staining analysis. The results showed that the combined treatment significantly reduced the number of Aeromonas bacteria at 1.64-1.69 log CFU/g and extended the shelf life of barramundi fillets. In addition, the combined treatment had a higher effect on the cell membrane integrity of the bacteria. In total, 36 metabolites were identified in the three strains. The undissociated molecules of CA can enter the cytoplasm, resulting in cell damage and inhibiting metabolic pathways. EW could lead to the reduction of metabolic products caused by oxidative stress and acid stress. Under the synergistic stress of CA and EW, the changes of main metabolite contents in the combined treatment group were significantly reduced. After combined treatment, there were 20, 31, and 31 pathways in which carbohydrate metabolism, amino acid metabolism, and energy metabolism were changed considerably. These findings indicated that the bactericidal mechanism of the bactericidal substance might be explained by the interference of the metabolic pathway, which guided post-treatment sanitisation and extended the applicability of the NMR spectrum to specific spoilage organisms (SSO) analysis in fish.

Nanoemulsified clove essential oils-based edible coating controls Pseudomonas spp.-causing spoilage of tilapia (Oreochromis niloticus) fillets: Working mechanism and bacteria metabolic responses.

Fish products suffer Pseudomonas-causing spoilage quickly during refrigeration storage, which could be solved by applying edible coating derived from nanoemulsified clove essential oils and fish gelatin (NCEO-FG). This study aimed to evaluate the effects and mechanism of NCEO-FG in preserving tilapia (Oreochromis niloticus) fillets that were inoculated with Pseudomonas spp. (Pseudomonas sp. strain ABa3, P. psychrophila strain ABe3, and P. fragi strain BBa3). NCEO caused remarkable leakage of proteins (198.5-252.8 µg/L) and nucleic acids (0.30-0.34 of OD260). After being incorporated into FG, NCEO-FG effectively delayed the deterioration of tilapia fillets because it significantly reduced the surviving bacteria populations (0.78 - 1.80 log CFU/g reductions) and inhibited the proteolysis and oxidation during cold storage. Further, the metabolic responses of NCEO-FG coated Pseudomonas spp. were revealed using NMR spectroscopy: the reducing levels of metabolites (e.g., pyruvate, amino acids, and betaine) suggested that the NCEO-FG disturbed energy and amino acid metabolisms of bacteria cells. However, the levels of metabolites (e.g., amino acids and osmoprotectants) were upregulated after 3 h and then back to normal concentration after 24 h, which indicated a defense system was built in bacterial cells to tolerate NCEO-FG. In short, this study confirmed that NCEO-FG could control the Pseudomonas-causing spoilage in fish fillets via elucidating the metabolisms.