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Nature Catalysis 2024The development of novel strategies to rapidly construct complex chiral molecules from readily available feedstocks is a long-term pursuit in the chemistry community....
The development of novel strategies to rapidly construct complex chiral molecules from readily available feedstocks is a long-term pursuit in the chemistry community. Radical-mediated alkene difunctionalizations represent an excellent platform towards this goal. However, asymmetric versions remain highly challenging, and more importantly, examples featuring simple hydrocarbons as reaction partners are elusive. Here we report an asymmetric three-component alkene dicarbofunctionalization capitalizing on the direct activation of C( )-H bonds through the combination of photocatalysed hydrogen atom transfer and nickel catalysis. This protocol provides an efficient platform for installing two vicinal carbon-carbon bonds across alkenes in an atom-economic fashion, providing a wide array of high-value chiral α-aryl/alkenyl carbonyls and phosphonates, as well as 1,1-diarylalkanes from ubiquitous alkane, ether and alcohol feedstocks. This method exhibits operational simplicity, broad substrate scope and excellent regioselectivity, chemoselectivity and enantioselectivity. The compatibility with bioactive motifs and expedient synthesis of pharmaceutically relevant molecules highlight the synthetic potential of this protocol.
PubMed: 38947227
DOI: 10.1038/s41929-024-01153-0 -
Journal of Immunotoxicology Dec 2024Per- and polyfluoroalkyl substances (PFAS) are anthropogenic organofluorine compounds that persist indefinitely in the environment and bioaccumulate throughout all...
Per- and polyfluoroalkyl substances (PFAS) are anthropogenic organofluorine compounds that persist indefinitely in the environment and bioaccumulate throughout all trophic levels. Biomonitoring efforts have detected multiple PFAS in the serum of most people. Immune suppression has been among the most consistent effects of exposure to PFAS. PFAS often co-occur as mixtures in the environment, however, few studies have examined immunosuppression of PFAS mixtures or determined whether PFAS exposure affects immune function in the context of infection. In this study, mixtures containing two or four different PFAS and a mouse model of infection with influenza A virus (IAV) were used to assess immunotoxicity of PFAS mixtures. PFAS were administered the drinking water as either a binary mixture of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) or quaternary mixture of PFOS, PFOA, perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). The results indicated that the binary mixture affected the T-cell response, while the quaternary mixture affected the B-cell response to infection. These findings indicate that the immunomodulatory effects of PFAS mixtures are not simply additive, and that the sensitivity of immune responses to PFAS varies by cell type and mixture. The study also demonstrates the importance of studying adverse health effects of PFAS mixtures.
Topics: Fluorocarbons; Animals; Mice; Influenza A virus; Alkanesulfonic Acids; Orthomyxoviridae Infections; Caprylates; Humans; Female; Mice, Inbred C57BL; Influenza, Human; Disease Models, Animal; T-Lymphocytes
PubMed: 38946256
DOI: 10.1080/1547691X.2024.2340495 -
Geobiology 2024Methane is a potent greenhouse gas that enters the marine system in large quantities at seafloor methane seeps. At a newly discovered seep site off the coast of Point...
Carbonate chimneys at the highly productive point Dume methane seep: Fine-scale mineralogical, geochemical, and microbiological heterogeneity reflects dynamic and long-lived methane-metabolizing habitats.
Methane is a potent greenhouse gas that enters the marine system in large quantities at seafloor methane seeps. At a newly discovered seep site off the coast of Point Dume, CA, ~ meter-scale carbonate chimneys host microbial communities that exhibit the highest methane-oxidizing potential recorded to date. Here, we provide a detailed assessment of chimney geobiology through correlative mineralogical, geochemical, and microbiological studies of seven chimney samples in order to clarify the longevity and heterogeneity of these highly productive systems. U-Th dating indicated that a methane-driven carbonate precipitating system at Point Dume has existed for ~20 Kyr, while millimeter-scale variations in carbon and calcium isotopic values, elemental abundances, and carbonate polymorphs revealed changes in carbon source, precipitation rates, and diagenetic processes throughout the chimneys' lifespan. Microbial community analyses revealed diverse modern communities with prominent anaerobic methanotrophs, sulfate-reducing bacteria, and Anaerolineaceae; communities were more similar within a given chimney wall transect than in similar horizons of distinct structures. The chimneys represent long-lived repositories of methane-oxidizing communities and provide a window into how carbon can be transformed, sequestered, and altered over millennia at the Point Dume methane seep.
Topics: Methane; Carbonates; Bacteria; California; Seawater; Geologic Sediments; Ecosystem; Archaea
PubMed: 38946067
DOI: 10.1111/gbi.12608 -
Angewandte Chemie (International Ed. in... Jun 2024Acetic acid (AA), a vital compound in chemical production and materials manufacturing, is conventionally synthesized by starting with coal or methane through multiple...
Acetic acid (AA), a vital compound in chemical production and materials manufacturing, is conventionally synthesized by starting with coal or methane through multiple steps including high-temperature transformations. Here we present a new synthesis of AA from ethane through photocatalytic selective oxidation of ethane by H2O2 at 0-25°C. The catalyst designed for this process comprises g-C3N4 with anchored Pd1 single-atom sites. In-situ studies and computational simulation suggest the immobilized Pd1 atom becomes positively charged under photocatalytic condition. Under photoirradiation, the holes on the Pd1 single-atom of OH-Pd1Å/g-C3N4 serves as a catalytic site for activating a C-H instead of C-C of C2H6 with a low activation barrier of 0.14 eV, through a concerted mechanism. Remarkably, the selectivity for synthesizing AA reaches 98.7%, achieved under atmospheric pressure of ethane at 0°C. By integrating photocatalysis with thermal catalysis, we introduce a highly selective, environmentally friendly, energy-efficient synthetic route for AA, starting from ethane, presenting a promising alternative for AA synthesis. This integration of photocatalysis in low-temperature oxidation demonstrates a new route of selective oxidation of light alkanes.
PubMed: 38945836
DOI: 10.1002/anie.202404598 -
BMC Microbiology Jun 2024Mangroves are complex and dynamic coastal ecosystems under frequent fluctuations in physicochemical conditions related to the tidal regime. The frequent variation in...
BACKGROUND
Mangroves are complex and dynamic coastal ecosystems under frequent fluctuations in physicochemical conditions related to the tidal regime. The frequent variation in organic matter concentration, nutrients, and oxygen availability, among other factors, drives the microbial community composition, favoring syntrophic populations harboring a rich and diverse, stress-driven metabolism. Mangroves are known for their carbon sequestration capability, and their complex and integrated metabolic activity is essential to global biogeochemical cycling. Here, we present a metabolic reconstruction based on the genomic functional capability and flux profile between sympatric MAGs co-assembled from a tropical restored mangrove.
RESULTS
Eleven MAGs were assigned to six Bacteria phyla, all distantly related to the available reference genomes. The metabolic reconstruction showed several potential coupling points and shortcuts between complementary routes and predicted syntrophic interactions. Two metabolic scenarios were drawn: a heterotrophic scenario with plenty of carbon sources and an autotrophic scenario with limited carbon sources or under inhibitory conditions. The sulfur cycle was dominant over methane and the major pathways identified were acetate oxidation coupled to sulfate reduction, heterotrophic acetogenesis coupled to carbohydrate catabolism, ethanol production and carbon fixation. Interestingly, several gene sets and metabolic routes similar to those described for wastewater and organic effluent treatment processes were identified.
CONCLUSION
The mangrove microbial community metabolic reconstruction reflected the flexibility required to survive in fluctuating environments as the microhabitats created by the tidal regime in mangrove sediments. The metabolic components related to wastewater and organic effluent treatment processes identified strongly suggest that mangrove microbial communities could represent a resourceful microbial model for biotechnological applications that occur naturally in the environment.
Topics: Microbiota; Bacteria; Wetlands; Phylogeny; Heterotrophic Processes; Carbon Cycle; Carbon; Methane; Autotrophic Processes; Metabolic Networks and Pathways
PubMed: 38943070
DOI: 10.1186/s12866-024-03390-6 -
Journal of Dairy Science Jul 2024The objective was to evaluate the effects of separate offering of feed ingredients (SF) and frequency of concentrate feeding versus offering a TMR, on lactational...
Separate offering of forages and concentrates to lactating dairy cows: Effects on lactational performance, enteric methane emission, and efficiency of nutrient utilization.
The objective was to evaluate the effects of separate offering of feed ingredients (SF) and frequency of concentrate feeding versus offering a TMR, on lactational performance, ruminal fermentation, enteric CH emissions, nutrient digestibility, N use efficiency, milk fatty acid profile, and blood variables in mid-lactation dairy cows. Twenty-four Holstein cows (12 primi- and 12 multiparous) averaging (±SD) 141 ± 35 DIM and 43 ± 6 kg/d of milk yield (MY) at the beginning of the study were used in a replicated 3 × 3 Latin square design experiment with 3 periods of 28 d each, composed of 7 d for adaptation to the diets, 11 d for estimation of net energy and metabolizable protein requirements, and 10 d for data and samples collection. Cows were grouped based on parity, DIM, and MY into 4 Latin squares. Treatment allocation was balanced for carryover effects, and cows within square were assigned to (1) basal diet fed ad libitum as TMR; (2) basal diet fed as SF with forages fed ad libitum and concentrates fed 3×/d (SF×3); or (3) basal diet fed as SF with forages fed ad libitum and concentrates fed 6×/d (SF×6). Compared with TMR, SF decreased total DMI by 1.2 kg/d. Treatments did not affect MY, milk components, or ECM yield, except for a decrease in milk fat concentration and an increase in milk urea N by SF×3, compared with TMR. Feed efficiency (kg of MY/kg of DMI) was increased by 7% in SF, compared with TMR. Ruminal molar proportion of acetate and acetate-to-propionate ratio were decreased, whereas molar proportion of propionate was increased by SF×3, compared with TMR and SF×6. There was a 9% decrease in daily CH production by SF, compared with TMR. Enteric CH yield (per kg of DMI) was not affected by treatments in the current study. Methane intensity per kilogram of MY tended to be decreased by 10% in SF, compared with TMR. The sums of odd- and branched-chain, odd-chain, and anteiso milk fatty acids tended to be or were increased by SF, compared with TMR. Intake of nutrients tended to be or were decreased by SF, compared with TMR. The digestibility of amylase-treated NDF tended to be decreased and ADF digestibility was decreased by 3% in SF, compared with TMR. Urinary and fecal N excretions were not affected by treatments. As a percentage of total N intake, separate offering of feed ingredients increased milk N secretion, indicating an increased N use efficiency by SF, compared with TMR. Blood total fatty acid concentration was decreased by SF relative to TMR. Compared with both TMR and SF×6, SF×3 increased blood urea N concentration. Overall, feed and N use efficiencies were increased by separate offering of feed ingredients, and increasing the frequency of concentrate feeding promoted ruminal fermentation effects similar to those obtained by feeding a TMR.
Topics: Animals; Cattle; Lactation; Female; Milk; Diet; Methane; Animal Feed; Digestion; Nutrients; Rumen; Fermentation
PubMed: 38942562
DOI: 10.3168/jds.2023-24261 -
Journal of Dairy Science Jul 2024Methane, both enteric and from manure management, is the most important greenhouse gas from ruminant livestock, and its mitigation can deliver substantial decreases in... (Review)
Review
Methane, both enteric and from manure management, is the most important greenhouse gas from ruminant livestock, and its mitigation can deliver substantial decreases in the carbon footprint of animal products and potentially contribute to climate change mitigation. Although choices may be limited, certain feeding-related practices can substantially decrease livestock enteric CH emission. These practices can be generally classified into 2 categories: diet manipulation and feed additives. Within the first category, selection of forages and increasing forage digestibility are likely to decrease enteric CH emission, but the size of the effect, relative to current forage practices in the United States dairy industry, is likely to be minimal to moderate. An opportunity also exists to decrease enteric CH emissions by increasing dietary starch concentration, but interventions have to be weighed against potential decreases in milk fat yield and farm profitability. A similar conclusion can be made about dietary lipids and oilseeds, which are proven to decrease CH emission but can also have a negative effect on rumen fermentation, feed intake, and milk production and composition. Sufficient and robust scientific evidence indicates that some feed additives, specifically the CH inhibitor 3-nitrooxypropanol, can substantially reduce CH emissions from dairy and beef cattle. However, the long-term effects and external factors affecting the efficacy of the inhibitor need to be further studied. The practicality of mass-application of other mitigation practices with proven short-term efficacy (i.e., macroalgae) is currently unknown. One area that needs more research is how nutritional mitigation practices (both diet manipulation and feed additives) interact with each other and whether there is synergism among feed additives with different mode of action. Further, effects of diet on manure composition and greenhouse gas emissions during storage (e.g., emission trade-offs) have not been adequately studied. Overall, if currently available mitigation practices prove to deliver consistent results and novel, potent, and safe strategies are discovered and are practical, nutrition alone can deliver up to 60% reduction in enteric CH emissions from dairy farms in the United States.
Topics: Methane; Animals; Animal Feed; Diet; Cattle; Milk; Dairying
PubMed: 38942560
DOI: 10.3168/jds.2023-24440 -
Journal of Biochemical and Molecular... Jul 2024
Short communication on "new insights into the combined toxicity of aflatoxin B1 and Fumonisin B1 in HepG2 cells using Seahorse respirometry analysis and RNA transcriptome sequencing".
Topics: Humans; Aflatoxin B1; Fumonisins; Hep G2 Cells; Transcriptome; Sequence Analysis, RNA
PubMed: 38940674
DOI: 10.1002/jbt.23756 -
MSystems Jun 2024The Mariana Trench (MT) is the deepest part of the ocean on Earth. Previous studies have described the microbial community structures and functional potential in the...
UNLABELLED
The Mariana Trench (MT) is the deepest part of the ocean on Earth. Previous studies have described the microbial community structures and functional potential in the seawater and surface sediment of MT. Still, the metabolic features and adaptation strategies of the microorganisms involved in nitrogen cycling processes are poorly understood. In this study, comparative metagenomic approaches were used to study microbial nitrogen cycling in three MT habitats, including hadal seawater [9,600-10,500 m below sea level (mbsl)], surface sediments [0-46 cm below seafloor (cmbsf) at a water depth between 7,143 and 8,638 mbsl], and deep sediments (200-306 cmbsf at a water depth of 8,300 mbsl). We identified five new nitrite-oxidizing bacteria (NOB) lineages that had adapted to the oligotrophic MT slope sediment, their CO fixation capability through the reductive tricarboxylic acid (rTCA) or Calvin-Benson-Bassham (CBB) cycle; an anammox bacterium might perform aerobic respiration and utilize sedimentary carbohydrates for energy generation because it contains genes encoding type A cytochrome oxidase and complete glycolysis pathway. In seawater, abundant alkane-oxidizing species can fix inert N released from other denitrifying and/or anammox bacteria. This study further expands our understanding of microbial life in the largely unexplored deepest part of the ocean.
IMPORTANCE
The metabolic features and adaptation strategies of the nitrogen cycling microorganisms in the deepest part of the ocean are largely unknown. This study revealed that anammox bacteria might perform aerobic respiration in response to nutrient limitation or O fluctuations in the Mariana Trench sediments. Meanwhile, an abundant alkane-oxidizing species could fix N in hadal seawater. This study provides new insights into the roles of hadal microorganisms in global nitrogen biogeochemical cycles. It substantially expands our understanding of the microbial life in the largely unexplored deepest part of the ocean.
PubMed: 38940525
DOI: 10.1128/msystems.00243-24 -
The Journal of Physical Chemistry... Jun 2024Photocatalytic oxidative dehydrogenation of propane (CH) into propene (CH) under mild conditions holds great potential in the chemical industry, but understanding how...
Photocatalytic oxidative dehydrogenation of propane (CH) into propene (CH) under mild conditions holds great potential in the chemical industry, but understanding how active species participate in CH conversion remains a significant challenge. Here, the wavelength-dependent activities of bridging oxygen (O) and the Ti-bound oxygen adatom (O) of model rutile (R) TiO(110) in CH conversion have been investigated. Under 257 and 343 nm irradiation, hole-trapped O and O can abstract the hydrogen atom of CH, forming the CHCHCH radical and CH. However, the rate of CH conversion with hole-trapped O is strongly dependent on the wavelength, primarily producing the CH radical. In the case of hole-trapped O, CH is the main product, which is nearly independent of wavelength. The differences in the wavelength-dependent activity and product selectivity are likely due to dynamic control rather than thermodynamic control. The result provides a deeper understanding of the dynamic processes involved in the conversion of light alkanes in TiO photocatalysis.
PubMed: 38940377
DOI: 10.1021/acs.jpclett.4c01035