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Environmental Science & Technology Jul 2024Organic molecules in the environment oxidatively degrade by a variety of free radical, microbial, and biogeochemical pathways. A significant pathway is heterogeneous...
Organic molecules in the environment oxidatively degrade by a variety of free radical, microbial, and biogeochemical pathways. A significant pathway is heterogeneous autoxidation, in which degradation occurs via a network of carbon and oxygen centered free radicals. Recently, we found evidence for a new heterogeneous autoxidation mechanism of squalene that is initiated by hydroxyl (OH) radical addition to a carbon-carbon double bond and apparently propagated through pathways involving Criegee Intermediates (CI) produced from β-hydroxy peroxy radicals (β-OH-RO•). It remains unclear, however, exactly how CI are formed from β-OH-RO•, which could occur by a unimolecular or bimolecular pathway. Combining kinetic models and multiphase OH oxidation measurements of squalene, we evaluate the kinetic viability of three mechanistic scenarios. Scenario 1 assumes that CI are formed by the unimolecular bond scission of β-OH-RO•, whereas Scenarios 2 and 3 test bimolecular pathways of β-OH-RO• to yield CI. Scenario 1 best replicates the entire experimental data set, which includes effective uptake coefficients vs [OH] as well as the formation kinetics of the major products (i.e., aldehydes and secondary ozonides). Although the unimolecular pathway appears to be kinetically viable, future high-level theory is needed to fully explain the mechanistic relationship between CI and β-OH-RO• in the condensed phase.
Topics: Squalene; Oxidation-Reduction; Kinetics; Hydroxyl Radical; Models, Chemical
PubMed: 38900151
DOI: 10.1021/acs.est.4c02590 -
Environmental Microbiology Jun 2024The Great Pacific Garbage Patch, a significant collection of plastic introduced by human activities, provides an ideal environment to study bacterial lifestyles on...
The Great Pacific Garbage Patch, a significant collection of plastic introduced by human activities, provides an ideal environment to study bacterial lifestyles on plastic substrates. We proposed that bacteria colonizing the floating plastic debris would develop strategies to deal with the ultraviolet-exposed substrate, such as the production of antioxidant pigments. We observed a variety of pigmentation in 67 strains that were directly cultivated from plastic pieces sampled from the Garbage Patch. The genomic analysis of four representative strains, each distinct in taxonomy, revealed multiple pathways for carotenoid production. These pathways include those that produce less common carotenoids and a cluster of photosynthetic genes. This cluster appears to originate from a potentially new species of the Rhodobacteraceae family. This represents the first report of an aerobic anoxygenic photoheterotrophic bacterium from plastic biofilms. Spectral analysis showed that the bacteria actively produce carotenoids, such as beta-carotene and beta-cryptoxanthin, and bacteriochlorophyll a. Furthermore, we discovered that the genetic ability to synthesize carotenoids is more common in plastic biofilms than in the surrounding water communities. Our findings suggest that plastic biofilms could be an overlooked source of bacteria-produced carotenoids, including rare forms. It also suggests that photoreactive molecules might play a crucial role in bacterial biofilm communities in surface water.
Topics: Carotenoids; Biofilms; Pigments, Biological; Plastics; Rhodobacteraceae; Phylogeny; Bacteria; Pacific Ocean
PubMed: 38899733
DOI: 10.1111/1462-2920.16639 -
Acta Dermato-venereologica Jun 2024
Topics: Isotretinoin; Humans; Dermatologic Agents; Treatment Outcome; Male; Female; Adult
PubMed: 38899441
DOI: 10.2340/actadv.v104.40101 -
Huan Jing Ke Xue= Huanjing Kexue Jun 2024The continuous accumulation of microplastics in agricultural soils may affect the natural attenuation of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs). The...
The continuous accumulation of microplastics in agricultural soils may affect the natural attenuation of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs). The effects of low-density polyethylene (LDPE) microplastics with the spiking proportion of 1 % and 0.01 % in soils on the natural attenuation of OPAHs were investigated via soil microcosm experiments. The relation between the response of bacterial communities and OPAHs dissipation was also explored. The initial content of OPAHs in the soil was 34.6 mg·kg. The dissipation of OPAHs in the soil on day 14 was inhibited by LDPE. The contents of OPAHs in LDPE groups were higher than that in the control by 0.9-1.6 mg·kg, and the inhibition degree increased with the proportion of LDPE. The contents of OPAHs were not significantly different among groups on day 28, indicating that the inhibitory effect of LDPE disappeared. LDPE did not change the composition of the dominant taxa in the OPAHs-contaminated soil community but influenced the relative abundances of some dominant taxa. LDPE increased the relative abundance of Proteobacteria and Actinobacteria at the phylum level and decreased that of and increased those of , , and (potential degrading bacteria of LDPE and endogenous substances) at the genus level, all four of which were the main genera dominating intergroup community differences. LDPE changed the and diversity of bacterial communities, but the extents were not significant. LDPE affected the function of the bacterial community, reducing the total abundance of PAHs-degrading genes and some degrading enzymes, inhibiting the growth of PAHs-degrading bacteria and thus interfering with the natural decay of OPAHs.
Topics: Polycyclic Aromatic Hydrocarbons; Polyethylene; Soil Pollutants; Biodegradation, Environmental; Microplastics; Soil Microbiology; Soil; Bacteria; Oxygen
PubMed: 38897788
DOI: 10.13227/j.hjkx.202307054 -
Huan Jing Ke Xue= Huanjing Kexue Jun 2024The threat of microplastic pollution in soil ecosystems has caused widespread concern. In order to clarify the effect of polyethylene microplastics on soil properties, a...
The threat of microplastic pollution in soil ecosystems has caused widespread concern. In order to clarify the effect of polyethylene microplastics on soil properties, a 4-month soil incubation experiment was conducted in this study to investigate the effect of different mass fraction (1 %, 2.5 %, and 5 %) and particle sizes (30 mesh and 100 mesh) of polyethylene microplastics on soil chemical properties, nutrient contents, and enzyme activities. The results showed that:① When the particle size was 100 mesh, microplastics at the mass concentrations of the 2.5 % and 5 % treatments significantly reduced soil pH, and the exposure of polyethylene microplastics had no significant effect on soil conductivity. ② Compared to that in CK, the addition of microplastics reduced soil available potassium, available phosphorus, and nitrate nitrogen to varying degrees. The addition of 100 mesh microplastics significantly increased soil organic matter and ammonium nitrogen. ③ When the particle size was 100 mesh, compared to that in CK, treatments of all concentrations significantly increased soil catalase activity and alkaline phosphatase, showing an increasing but not significant trend, and the 5 % concentration treatment significantly decreased soil sucrase activity. ④ Changes in soil properties were influenced by the addition of microplastics of different concentrations and sizes, with higher concentrations and smaller particle sizes having more significant effects. In conclusion, the effects of microplastics on soil properties were not as pronounced as expected, and future research should focus on the mechanisms involved in the different effects.
Topics: Soil; Soil Pollutants; Polyethylene; Microplastics; Phosphorus; Nitrogen; Catalase; Nutrients; Particle Size; Alkaline Phosphatase
PubMed: 38897787
DOI: 10.13227/j.hjkx.202306183 -
FP Essentials Jun 2024Acne is a chronic, recurrent inflammatory condition of the pilosebaceous unit. It affects approximately 85% of adolescents and creates significant psychosocial and... (Review)
Review
Acne is a chronic, recurrent inflammatory condition of the pilosebaceous unit. It affects approximately 85% of adolescents and creates significant psychosocial and financial burdens. The pathogenesis involves altered follicular growth and differentiation, microbial colonization with , increased sebum production influenced by androgen levels, and inflammation. Evidence-based risk factors include family history and body mass index. Diagnosis of acne is clinical, according to patient age and acne morphology and severity. Setting treatment expectations is an important aspect of management. For mild acne, benzoyl peroxide is an effective first-line drug as monotherapy or in combination with a topical retinoid and/or topical antibiotic. Oral tetracyclines are first-line drugs as part of a multipart treatment regimen for moderate to severe acne for patients older than 8 years. Oral isotretinoin is the first-line drug for moderate to severe inflammatory acne. Because of its teratogenic effects, its prescribing is monitored through the iPLEDGE Risk Evaluation and Mitigation Strategy (REMS) program. Prescribing oral or topical antibiotics as monotherapy for acne is not recommended, as this may increase microbial resistance. Combined oral contraceptives and spironolactone are used as adjunctive therapies in female adolescents. Patients with skin of color, pregnant patients, and transgender or gender diverse patients warrant special considerations in acne management.
Topics: Humans; Acne Vulgaris; Adolescent; Child; Dermatologic Agents; Anti-Bacterial Agents; Isotretinoin; Female; Benzoyl Peroxide; Risk Factors; Male; Spironolactone; Retinoids
PubMed: 38896825
DOI: No ID Found -
The ISME Journal Jun 2024The rhizosphere, which serves as the primary interface between plant roots and the soil, constitutes an ecological niche for a huge diversity of microbial communities....
The rhizosphere, which serves as the primary interface between plant roots and the soil, constitutes an ecological niche for a huge diversity of microbial communities. Currently, there is little knowledge on the nature and the function of the different metabolites released by rhizospheric microbes to facilitate colonization of this highly competitive environment. Here, we demonstrate how the production of galbonolides, a group of polyene macrolides that inhibit plant and fungal inositol phosphorylceramide synthase (IPCS), empowers the rhizospheric Streptomyces strain AgN23, to thrive in the rhizosphere by triggering the plant's defence mechanisms. Metabolomic analysis of AgN23-inoculated Arabidopsis roots revealed a strong induction in the production of an indole alkaloid, camalexin, which is a major phytoalexin in Arabidopsis. By using a plant mutant compromized in camalexin synthesis, we show that camalexin production is necessary for the successful colonization of the rhizosphere by AgN23. Conversely, hindering galbonolides biosynthesis in AgN23 knock-out mutant resulted in loss of inhibition of IPCS, a deficiency in plant defence activation, notably the production of camalexin, and a strongly reduced development of the mutant bacteria in the rhizosphere. Together, our results identified galbonolides as important metabolites mediating rhizosphere colonization by Streptomyces.
PubMed: 38896026
DOI: 10.1093/ismejo/wrae112 -
International Journal of Nanomedicine 2024To improve the bioavailability of resveratrol (-Res), it is commonly co-delivered with antioxidant bioactives using a complex synthetic intestinal targeted carrier,...
INTRODUCTION
To improve the bioavailability of resveratrol (-Res), it is commonly co-delivered with antioxidant bioactives using a complex synthetic intestinal targeted carrier, however, which makes practical application challenging.
METHODS
A nanogel (Ngel), as broad-spectrum autonomous ROS scavenger, was prepared using selenized thiolated sodium alginate (TSA-Se) and crosslinked with calcium lactate (CL) for loading Res to obtain Ngel@Res, which maintained spherical morphology in the upper digestive tract but broke down in the lower digestive tract, resulting in -Res release.
RESULTS
Under protection of Ngel, Res showed enhanced stability and broad-spectrum ROS scavenging activity. The synergistic mucoadhesion of Ngel prolonged the retention time of Res in the intestine. Ngel and Ngel@Res increased the lifespan of to 26.00 ± 2.17 and 26.00 ± 4.27 days by enhancing the activity of antioxidases, upregulating the expression of and , while downregulating the expression of and .
CONCLUSION
This readily available, intestinal targeted selenized alginate-based nanogel effectively improves the bioactivity of Res.
Topics: Animals; Caenorhabditis elegans; Resveratrol; Reactive Oxygen Species; Alginates; Nanogels; Antioxidants; Polyethylene Glycols; Polyethyleneimine; Free Radical Scavengers; Intestinal Mucosa; Drug Carriers
PubMed: 38895150
DOI: 10.2147/IJN.S464849 -
A pattern for the early, middle, and late phase of tea chrysanthemum response to Fusarium oxysporum.Physiologia Plantarum 2024Chrysanthemum morifolium is cultivated worldwide and has high ornamental, tea, and medicinal value. With the increasing area of chrysanthemum cultivation and years of...
Chrysanthemum morifolium is cultivated worldwide and has high ornamental, tea, and medicinal value. With the increasing area of chrysanthemum cultivation and years of continuous cropping, Fusarium wilt disease frequently occurs in various production areas, seriously affecting the quality and yield and causing huge economic losses. However, the molecular response mechanism of Fusarium wilt infection remains unclear, which limits the molecular breeding process for disease resistance in chrysanthemums. In the present study, we analyzed the molecular response mechanisms of 'Huangju,' one of the tea chrysanthemum cultivars severely infested with Fusarium wilt in the field at the early, middle, and late phases of F. oxysporum infestation. 'Huangju' responded to the infestation mainly through galactose metabolism, plant-pathogen interaction, auxin, abscisic acid, and ethylene signalling in the early phase; galactose metabolism, plant-pathogen interaction, auxin, salicylic acid signal, and certain transcription factors (e.g., CmWRKY48) in the middle phase; and galactose metabolism in the late phase. Notably, the galactose metabolism was important in the early, middle, and late phases of 'Huangju' response to F. oxysporum. Meanwhile, the phytohormone auxin was involved in the early and middle responses. Furthermore, silencing of CmWRKY48 in 'Huangju' resulted in resistance to F. oxysporum. Our results revealed a new molecular pattern for chrysanthemum in response to Fusarium wilt in the early, middle, and late phases, providing a foundation for the molecular breeding of chrysanthemum for disease resistance.
Topics: Fusarium; Chrysanthemum; Plant Diseases; Plant Growth Regulators; Gene Expression Regulation, Plant; Indoleacetic Acids; Disease Resistance; Abscisic Acid; Host-Pathogen Interactions; Galactose; Plant Proteins
PubMed: 38894555
DOI: 10.1111/ppl.14373 -
Molecules (Basel, Switzerland) May 2024Yerba Mate drink made from dried and crushed leaves and twigs of Paraguayan holly ( A. St.-Hil.), which is a valuable source of bioactive substances, in particular...
Yerba Mate drink made from dried and crushed leaves and twigs of Paraguayan holly ( A. St.-Hil.), which is a valuable source of bioactive substances, in particular antioxidants. The available literature lacks data on changes in the content and profile of bioactive compounds such as tannins, caffeine, the phenolic acid profile of flavonoids and carotenoids, as well as total polyphenol content and antioxidant activity in Yerba Mate infusions depending on different brewing conditions, and how different brewing conditions affect the physicochemical properties of these infusions. Therefore, this study evaluated the physicochemical properties of dried and Yerba Mate infusions prepared via single and double brewing processes at 70 °C and 100 °C. The organoleptic evaluation, as well as the instrumental color measurement, showed significant changes in the total color difference (Δ) and the *** chromatic coordinates of dried Yerba Mate samples and their infusions. Moreover, the research showed higher contents of tannins (mean 1.36 ± 0.14 g/100 g d.m.), caffeine (mean 17.79 ± 3.49 mg/g d.m.), carotenoids (mean 12.90 ± 0.44 μg/g d.m.), phenolic acids (mean 69.97 ± 7.10 mg/g d.m.), flavonoids (mean 5.47 ± 1.78 mg/g d.m.), total polyphenols (mean 55.26 ± 8.51 mg GAE/g d.m.), and antioxidant activity (mean 2031.98 ± 146.47 μM TEAC/g d.m.) in single-brewed Yerba Mate infusions compared to double-brewed (0.77 ± 0.12 g/100 g d.m., 14.28 ± 5.80 mg/g d.m., 12.67 ± 0.62 μg/g d.m., 57.75 ± 8.73 mg/g d.m., 3.64 ± 0.76 mg/g d.m., 33.44 ± 6.48 mg GAE/g d.m. and 1683.09 ± 155.34 μM TEAC/g d.m., respectively). In addition, infusions prepared at a lower temperature (70 °C) were characterized by a higher content of total polyphenols and higher antioxidant activity, in contrast to the tannin and carotenoid contents, the levels of which were higher at 100 °C than at 70 °C. Considering the high amount of bioactive ingredients, in particular antioxidants, and a wide range of health benefits, it is worth including Yerba Mate in the daily diet.
Topics: Ilex paraguariensis; Antioxidants; Polyphenols; Tannins; Flavonoids; Carotenoids; Plant Extracts; Plant Leaves; Caffeine; Hydroxybenzoates; Beverages
PubMed: 38893465
DOI: 10.3390/molecules29112590