Enzymatic oxidation of cholesterol generates numerous distinct bile acids that function both as detergents that facilitate digestion and absorption of dietary lipids, and as hormones that activate ...four distinct receptors. Activation of these receptors alters gene expression in multiple tissues, leading to changes not only in bile acid metabolism but also in glucose homeostasis, lipid and lipoprotein metabolism, energy expenditure, intestinal motility and bacterial growth, inflammation, liver regeneration, and hepatocarcinogenesis. This review covers the roles of specific bile acids, synthetic agonists, and their cognate receptors in controlling these diverse functions, as well as their current use in treating human diseases.
The history of freshwater fish production and consumption in Thailand were reviewed in the late 1970s. While aquaculture had a history of more than a century in the country it had only started to ...expand relatively recently because of the abundance of wild fish in former times. Historical aspects of freshwater capture fisheries and freshwater aquaculture in Thailand, and the development of irrigation in Central Thailand which played an important role in facilitating the development of inland aquaculture in the country were reviewed. While dam construction led to the demise of the flood plain capture fishery, it provided a controlled water supply necessary for the subsequent development of aquaculture. The study informed the development of education and research in aquaculture at the Asian Institute of Technology (AIT). More recent developments in Thai aquaculture are outlined. Malnutrition in developing countries and fish in the Thai diet at the time of the study were also reviewed.
With mounting concerns over climate change, the utilisation or conversion of carbon dioxide into sustainable, synthetic hydrocarbons fuels, most notably for transportation purposes, continues to ...attract worldwide interest. This is particularly true in the search for sustainable or renewable aviation fuels. These offer considerable potential since, instead of consuming fossil crude oil, the fuels are produced from carbon dioxide using sustainable renewable hydrogen and energy. We report here a synthetic protocol to the fixation of carbon dioxide by converting it directly into aviation jet fuel using novel, inexpensive iron-based catalysts. We prepare the Fe-Mn-K catalyst by the so-called Organic Combustion Method, and the catalyst shows a carbon dioxide conversion through hydrogenation to hydrocarbons in the aviation jet fuel range of 38.2%, with a yield of 17.2%, and a selectivity of 47.8%, and with an attendant low carbon monoxide (5.6%) and methane selectivity (10.4%). The conversion reaction also produces light olefins ethylene, propylene, and butenes, totalling a yield of 8.7%, which are important raw materials for the petrochemical industry and are presently also only obtained from fossil crude oil. As this carbon dioxide is extracted from air, and re-emitted from jet fuels when combusted in flight, the overall effect is a carbon-neutral fuel. This contrasts with jet fuels produced from hydrocarbon fossil sources where the combustion process unlocks the fossil carbon and places it into the atmosphere, in longevity, as aerial carbon - carbon dioxide.
A detailed molecular orbital (MO) analysis of the structure and electronic properties of the great variety of species in lithium-ammonia solutions is provided. In the odd-electron, doublet states we ...have considered: e⁻@(NH₃)n (the solvated electron, likely to be a dynamic ensemble of molecules), the Li(NH₃)₄ monomer, and the Li(NH₃)₄ ⁺ · e⁻@(NH₃)n ion-pairs, the Li 2s electron enters a diffuse orbital built up largely from the lowest unoccupied MOs of the ammonia molecules. The singly occupied MOs are bonding between the hydrogen atoms; we call this stabilizing interaction HH bonding. In e⁻@(NH₃)n the odd electron is not located in the center of the cavities formed by the ammonia molecules. Possible species with two or more weakly interacting electrons also exhibit HH bonding. For these, we find that the singlet (S=0) states are slightly lower in energy than those with unpaired (S=1, 2em leader) spins. TD-DFT calculations on various ion-pairs show that the three most intense electronic excitations arise from the transition between the SOMO (of s pseudosymmetry) into the lowest lying p-like levels. The optical absorption spectra are relatively metal-independent, and account for the absorption tail which extends into the visible. This is the source of Sir Humphry Davy's "fine blue colour" first observed just over 200 years ago.
The fatty acyl composition of phospholipids determines the biophysical character of membranes and impacts the function of membrane proteins. Here, we define a nuclear receptor pathway for the dynamic ...modulation of membrane composition in response to changes in cellular lipid metabolism. Ligand activation of liver X receptors (LXRs) preferentially drives the incorporation of polyunsaturated fatty acids into phospholipids through induction of the remodeling enzyme Lpcat3. Promotion of Lpcat3 activity ameliorates endoplasmic reticulum (ER) stress induced by saturated free fatty acids in vitro or by hepatic lipid accumulation in vivo. Conversely, Lpcat3 knockdown in liver exacerbates ER stress and inflammation. Mechanistically, Lpcat3 modulates inflammation both by regulating inflammatory kinase activation through changes in membrane composition and by affecting substrate availability for inflammatory mediator production. These results outline an endogenous mechanism for the preservation of membrane homeostasis during lipid stress and identify Lpcat3 as an important mediator of LXR effects on metabolism.
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•Induction of Lpcat3 expression by LXRs promotes phospholipid remodeling•LXR-Lpcat3 activation drives unsaturated fatty acid incorporation into phospholipids•Lpcat3 activity in liver modulates lipid-induced ER stress and inflammation•Lpcat3 affects inflammation through regulation of membrane c-Src activity
Hydrogen technologies and fuel cells offer an alternative and improved solution for a decarbonised energy future. Fuel cells are electrochemical converters; transforming hydrogen (or energy sources ...containing hydrogen) and oxygen directly into electricity. The hydrogen fuel cell, invented in 1839, permits the generation of electrical energy with high efficiency through a non-combustion, electrochemical process and, importantly, without the emission of CO2 at its point of use. Hitherto, despite numerous efforts to exploit the obvious attractions of hydrogen technologies and hydrogen fuel cells, various challenges have been encountered, some of which are reviewed here. Now, however, given the exigent need to urgently seek low-carbon paths for humankind's energy future, numerous countries are advancing the deployment of hydrogen technologies and hydrogen fuel cells not only for transport, but also as a means of the storage of excess renewable energy from, for example, wind and solar farms. Furthermore, hydrogen is also being blended into the natural gas supplies used in domestic heating and targeted in the decarbonisation of critical, large-scale industrial processes such as steel making. We briefly review specific examples in countries such as Japan, South Korea and the People's Republic of China, as well as selected examples from Europe and North America in the utilization of hydrogen technologies and hydrogen fuel cells.
A vision of a future hydrogen energy society is illustrated in the photomontage below. The US National Hydrogen Day was officially launched on October 8 (1008), 2015 after 1H1.008.
ElenaTlt/Shutterstock; Chesky/Shutterstock; Deniz Toprak/Shutterstock Display omitted
Four members of the mammalian ATP binding cassette (ABC) transporter G subfamily are thought to be involved in transmembrane (TM) transport of sterols. The residues responsible for this transport are ...unknown. The mechanism of action of ABCG1 is controversial and it has been proposed to act at the plasma membrane to facilitate the efflux of cellular sterols to exogenous high-density lipoprotein (HDL). Here we show that ABCG1 function is dependent on localization to intracellular endosomes. Importantly, localization to the endosome pathway distinguishes ABCG1 and/or ABCG4 from all other mammalian members of this superfamily, including other sterol transporters. We have identified critical residues within the TM domains of ABCG1 that are both essential for sterol transport and conserved in some other members of the ABCG subfamily and/or the insulin-induced gene 2 (INSIG-2). Our conclusions are based on studies in which (i) biotinylation of peritoneal macrophages showed that endogenous ABCG1 is intracellular and undetectable at the cell surface, (ii) a chimeric protein containing the TM of ABCG1 and the cytoplasmic domains of the nonsterol transporter ABCG2 is both targeted to endosomes and functional, and (iii) ABCG1 colocalizes with multiple proteins that mark late endosomes and recycling endosomes. Mutagenesis studies identify critical residues in the TM domains that are important for ABCG1 to alter sterol efflux, induce sterol regulatory element binding protein-2 (SREBP-2) processing, and selectively attenuate the oxysterol-mediated repression of SREBP-2 processing. Our data demonstrate that ABCG1 is an intracellular sterol transporter that localizes to endocytic vesicles to facilitate the redistribution of specific intracellular sterols away from the endoplasmic reticulum (ER).
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