The coupling coordination and spatiotemporal evolution of industrial water-energy-CO2 in the Yellow River Basin.

The Yellow River Basin (YRB) is an important energy, chemical, raw material, and basic industrial base in China. With economic growth, water and energy consumption in industrial industries increasing dramatically, huge pressure for CO2 emission reduction has generated. This paper constructed an industrial water-energy-CO2 (WEC) evaluation index system, analyzed the comprehensive evaluation level, coupling status and coupling coordination status, by using the comprehensive evaluation method, coupling degree model and coupling coordination degree model and used the spatial autocorrelation analysis to study the spatiotemporal evolution from 1999 to 2019 in the YRB. The results demonstrated that the integrated development level of the basin's industrial WEC system and subsystems had been improving. The basin was at a high coupling and the level of coupling had been increasing as a whole, and the industrial energy-CO2 coupling degree was bigger than the industrial water-energy and industrial water-CO2 coupling degrees in the YRB. The coupling coordination status had transitioned from forced coordination to good coordination. Spatially, the coupling coordination didn't appear a significant correlation and showed a random distribution. Accordingly, the suggestions were made to improve the level of industrial development in the basin, strengthen integrated resource management, and enhance intra-basin cooperation.

Ecological security evaluation and early warning in the water source area of the Middle Route of South-to-North Water Diversion Project.

Ecological security has important influence on regional sustainable development. The ecological security of Nanyang, the water source area of the Middle Route of South-to-North Water Diversion Project, was threatened because of surface water pollution. The existing studies had not been able to comprehensively assess the ecological security and future trend of water source area. In order to promote the high-quality development of the follow-up projects of the South-to-North Water Diversion project, it is very important to probe into the current situation and predict the future trend of ecological security in the water source area. Therefore, this paper constructed an ecological security evaluation index system based on the Driving force, Pressure, State, Impact and Response (DPSIR) model, used the combination of Analytic Hierarchy Process and- entropy weighting method to evaluate the ecological security of each district and county in Nanyang from 2000 to 2020, and used the auto regressive integrated moving average (ARIMA) model to predict the ecological security of the water source area from 2021 to 2030. The results demonstrated that: (1) The ecological security of Nanyang had changed from a moderate warning to a general safety, and the ecological security index had improved. The ecological security level of Nanyang would improve continuously from 2021 to 2030. (2) The northwest area and the central area of Nanyang had better ecological security states, while the southeast area wasn't so. Based on the results, the countermeasures for improving ecological security were proposed.

New scanning electron microscopic method for determination of adipocyte size in humans and mice.

OBJECTIVE: To evaluate a new scanning electronic microscopic (EM) method for assessing fat cell sizes and compare fat cell size distribution in human adipose tissue from different fat depots before and after weight loss. RESEARCH METHODS AND PROCEDURES: Identical human fat tissue biopsies were separated into two fractions: one used to prepare a fat cell suspension by collagenase digestion followed by photomicrography (collagenase method) and the other fixed in formalin for EM analysis. The EM method was evaluated further by determining fat cell sizes from lean and ob/ob mice. Finally, the EM method was used to assess fat cell sizes in biopsies of different human depots from before and after weight loss. RESULTS: Fat cell size distributions measured by the two methods were not identical, but differences were generally small. The EM method reproduced the well-documented fat cell size difference between lean and ob/ob mice. Large variation was detected in fat cell distributions among three depots in humans. Weight loss reduced fat cell sizes in subjects with large baseline fat cells but had no effect in subjects with small baseline fat cell sizes. DISCUSSION: Our results suggest that the EM method may be a useful alternative for fat cell size analysis of clinical samples.

Palmitate modulates intracellular signaling, induces endoplasmic reticulum stress, and causes apoptosis in mouse 3T3-L1 and rat primary preadipocytes.

Although fatty acids enhance preadipocyte differentiation in the presence of adequate hormone cocktails, little is known regarding their effects in the absence of these hormones. We have now shown that palmitate, a common long-chain saturated fatty acid, induced apoptosis in both mouse 3T3-L1 and rat primary preadipocytes grown in a normal serum-containing medium. Treatment of preadipocytes with palmitate induced multiple endoplasmic reticulum (ER) stress responses, evidenced by increased protein content of CHOP and GRP78 and splicing of XBP-1 mRNA, as well as altered phosphorylation of eIF2alpha and increased phosphorylation of JNK and Erk1/2. Intriguingly, palmitate induced an early activation of Akt but diminished both Akt activation and its protein mass after prolonged incubation (>6 h). In association with these changes, palmitate reduced expression of beta-catenin and its downstream target, c-Myc and cyclin D1, two key prosurvival proteins. Overexpression of constitutively active Akt did not block the apoptotic effect of palmitate. Cotreatment with unsaturated fatty acids (oleate, linoleate) or with LiCl (a glycogen synthase kinase-3beta inhibitor) attenuated the palmitate-induced apoptosis. Subsequent analysis suggested that the unsaturated fatty acids probably counteracted palmitate by reducing, not eliminating, ER stress, whereas LiCl probably improved viability by activating the Wnt signaling pathway. Cotreatment of palmitate with a standard adipogenic hormone cocktail also abolished the apoptotic effect and promoted adipocyte differentiation. Collectively, our results suggest that palmitate causes multiple cellular stresses that may lead to apoptosis in preadipocytes in the absence of adipogenic stimuli, highlighting the importance of exogenous hormones in directing cell fate in response to increased fatty acid influx.

Aging results in paradoxical susceptibility of fat cell progenitors to lipotoxicity.

Aging is associated with metabolic syndrome, tissue damage by cytotoxic lipids, and altered fatty acid handling. Fat tissue dysfunction may contribute to these processes. This could result, in part, from age-related changes in preadipocytes, since they give rise to new fat cells throughout life. To test this hypothesis, preadipocytes cultured from rats of different ages were exposed to oleic acid, the most abundant fatty acyl moiety in fat tissue and the diet. At fatty acid concentrations at which preadipocytes from young animals remained viable, cells from old animals accumulated lipid in multiple small lipid droplets and died, with increased apoptotic index, caspase activity, BAX, and p53. Rather than inducing apoptosis, oleic acid promoted adipogenesis in preadipocytes from young animals, with appearance of large lipid droplets. CCAAT/enhancer-binding protein-alpha (C/EBPalpha) and peroxisome proliferator-activated receptor-gamma (PPARgamma) increased to a greater extent in cells from young than old animals after oleate exposure. Oleic acid, but not glucose, oxidation was impaired in preadipocytes and fat cells from old animals. Expression of carnitine palmitoyltransferase (CPT)-1, which catalyzes the rate-limiting step in fatty acid beta-oxidation, was not reduced in preadipocytes from old animals. At lower fatty acid levels, constitutively active CPT I expression enhanced beta-oxidation. At higher levels, CPT I was not as effective in enhancing beta-oxidation in preadipocytes from old as young animals, suggesting that mitochondrial dysfunction may contribute. Consistent with this, medium-chain acyl-CoA dehydrogenase expression was reduced in preadipocytes from old animals. Thus preadipocyte fatty acid handling changes with aging, with increased susceptibly to lipotoxicity and impaired fatty acid-induced adipogenesis and beta-oxidation.

Modulation of adipocyte lipogenesis by octanoate: involvement of reactive oxygen species.

BACKGROUND: Octanoate is a medium-chain fatty acid (MCFA) that is rich in milk and tropical dietary lipids. It also accounts for 70% of the fatty acids in commercial medium chain triglycerides (MCT). Use of MCT for weight control tracks back to early 1950s and is highlighted by recent clinical trials. The molecular mechanisms of the weight reduction effect remain not completely understood. The findings of significant amounts of MCFA in adipose tissue in MCT-fed animals and humans suggest a direct influence of MCFA on fat cell functions. METHODS: 3T3-L1 adipocytes were treated with octanoate in a high glucose culture medium supplemented with 10% fetal bovine serum and 170 nM insulin. The effects on lipogenesis, fatty acid oxidation, cellular concentration of reactive oxygen species (ROS), and the expression and activity of peroxisome proliferator receptor gamma (PPARgamma) and its associated lipogenic genes were assessed. In selected experiments, long-chain fatty acid oleate, PPARgamma agonist troglitazone, and antioxidant N-acetylcysteine were used in parallel. Effects of insulin, L-carnitine, and etomoxir on beta-oxidation were also measured. RESULTS: Beta-oxidation of octanoate was primarily independent of CPT-I. Treatment with octanoate was linked to an increase in ROS in adipocytes, a decrease in triglyceride synthesis, and reduction of lipogenic gene expression. Co-treatment with troglitazone, N-acetylcysteine, or over-expression of glutathione peroxidase largely reversed the effects of octanoate. CONCLUSION: These findings suggest that octanoate-mediated inactivation of PPARgamma might contribute to the down regulation of lipogenic genes in adipocytes, and ROS appears to be involved as a mediator in this process.

Oleate-induced formation of fat cells with impaired insulin sensitivity.

Exogenous FA cause lipid accumulation in pre-adipocytes. We investigated whether the fat cells thus formed are metabolically distinct from adipocytes differentiated with standard methylisobutylxanthine, dexamethasone, and insulin (MDI) hormonal cocktail by comparing their expression of adipogenic genes, accumulation of TAG, lipogenesis, lipolysis, glucose uptake, and the effects of insulin on selected metabolic activities. Cells exposed to oleate began to accumulate TAG in parallel or prior to the induction of adipogenic genes, whereas cells treated with MDI expressed adipogenic genes before TAG accumulation. Oleate-treated fat cells also showed exaggerated basal lipolysis and weak response to insulin in both lipolysis regulation and glucose uptake. These findings were associated with increased basal phosphorylation of perilipin, increased Glut-1 but decreased Glut-4 expression, and reduced insulin-induced Akt phosphorylation. We suggest that this unique fat cell phenotype might be a mimetic of what can happen to fat cells formed in vivo under the influence of circulating FA and might be a useful model for in vitro studies of obesity-related insulin resistance in adipocytes.

Fatty acid transport and metabolism in HepG2 cells.

The mechanism(s) of fatty acid uptake by liver cells is not fully understood. We applied new approaches to address long-standing controversies of fatty acid uptake and to distinguish diffusion and protein-based mechanisms. Using HepG2 cells containing an entrapped pH-sensing fluorescence dye, we showed that the addition of oleate (unbound or bound to cyclodextrin) to the external buffer caused a rapid (seconds) and dose-dependent decrease in intracellular pH (pH(in)), indicating diffusion of fatty acids across the plasma membrane. pH(in) returned to its initial value with a time course (in min) that paralleled the metabolism of radiolabeled oleate. Preincubation of cells with the inhibitors phloretin or triacsin C had no effect on the rapid pH(in) drop after the addition of oleate but greatly suppressed pH(in) recovery. Using radiolabeled oleate, we showed that its esterification was almost completely inhibited by phloretin or triacsin C, supporting the correlation between pH(in) recovery and metabolism. We then used a dual-fluorescence assay to study the interaction between HepG2 cells and cis-parinaric acid (PA), a naturally fluorescent but slowly metabolized fatty acid. The fluorescence of PA increased rapidly upon its addition to cells, indicating rapid binding to the plasma membrane; pH(in) decreased rapidly and simultaneously but did not recover within 5 min. Phloretin had no effect on the PA-mediated pH(in) drop or its slow recovery but decreased the absolute fluorescence of membrane-bound PA. Our results show that natural fatty acids rapidly bind to, and diffuse through, the plasma membrane without hindrance by metabolic inhibitors or by an inhibitor of putative membrane-bound fatty acid transporters.

Eicosapentaenoic acid, but not oleic acid, stimulates beta-oxidation in adipocytes.

The beneficial roles of dietary fish oil in lowering serum TAG levels in animals and humans have been attributed in part to the high content of two n-3 polyunsaturated very long-chain FA, EPA, and DHA. Recent studies show that EPA induces mitochondrial beta-oxidation in hepatocytes, which might contribute to the systemic lipid-lowering effect. Whether EPA affects FA storage or oxidation in adipocytes is not clear. To investigate this possibility, 3T3-L1 adipocytes incubated with EPA (100 microM) for 24 h were assayed for beta-oxidation, carnitine palmitoyl transferase 1 (CPT-1) activity, protein, and mRNA expression of CPT-1. For comparison, cells treated with oleic acid, octanoic acid, and clofibrate, a synthetic ligand for peroxisome proliferator-activated receptor alpha were also analyzed. Mitochondria were isolated by differential centrifugation, and the mitochondrial membrane acyl chain composition was measured by GLC. EPA increased the oxidation of endogenous FA but did not inhibit lipogenesis. Oleic acid and clofibrate did not affect FA oxidation or lipogenesis, whereas octanoic acid suppressed the oxidation of endogenous FA and inhibited lipogenesis. Increased beta-oxidation by EPA was associated with increased CPT-1 activity but without changes in its mRNA and protein expression. EPA treatment increased the percentage of this FA in the mitochondrial membrane lipids. We suggest that EPA increased the activity of CPT-1 and beta-oxidation in adipocytes by altering the structure or dynamics of the mitochondrial membranes.

Regulation of acetyl CoA carboxylase and carnitine palmitoyl transferase-1 in rat adipocytes.

OBJECTIVE: Acetyl CoA carboxylase (ACC) is a key enzyme in energy balance. It controls the synthesis of malonyl-CoA, an allosteric inhibitor of carnitine palmitoyltransferase-1 (CPT-I). CPT-I is the gatekeeper of free fatty acid (FFA) oxidation. To test the hypothesis that both enzymes play critical roles in regulation of FFA partitioning in adipocytes, we compared enzyme mRNA expression and specific activity from fed, fasted, and diabetic rats. RESEARCH METHODS AND PROCEDURES: Direct effects of nutritional state, insulin, and FFAs on CPT-I and ACC mRNA expression were assessed in adipocytes, liver, and cultured adipose tissue explants. We also determined FFA partitioning in adipocytes from donors exposed to different nutritional conditions. RESULTS: CPT-I mRNA and activity decreased in adipocytes but increased in liver in response to fasting. ACC mRNA and activity decreased in both adipocytes and liver during fasting. These changes were not caused directly by fasting-associated changes in plasma insulin and FFA concentrations because insulin suppressed CPT-I mRNA and did not affect ACC mRNA in vitro, whereas exogenous oleate had no effect on either. Despite the decrease in adipocyte CPT-I mRNA and specific activity, CO(2) production from endogenous FFAs increased, suggesting increased FFA transport through CPT-I for beta-oxidation. DISCUSSION: Stimulation of FFA transport through CPT-I occurs in both tissues, but CPT-I mRNA and specific activity correlate with FFA transport in liver and not in adipocytes. We conclude that the mechanism responsible for increasing FFA oxidation in adipose tissue during fasting involves mainly allosteric regulation, whereas altered gene expression may play a central role in the liver.

Medium-chain Fatty acids attenuate agonist-stimulated lipolysis, mimicking the effects of starvation.

OBJECTIVE: To test the hypothesis that incorporation of medium-chain fatty acids (FAs) into adipocyte triglycerides alters intracellular lipolysis. RESEARCH METHODS AND PROCEDURES: 3T3-L1 adipocytes were pretreated with octanoate for various incubation periods. After the removal of exogenous FAs, cells were incubated with different lipolytic agonists. To determine the effects on lipolysis, we measured the following: the release of glycerol and FAs, lipase activity, protein levels of hormone-sensitive lipase (HSL), and perilipin A; translocation of HSL; phosphorylation of perilipin A; and levels of cellular adenosine triphosphate, cyclic adenosine monophosphate, and H2O2. To compare the effects of starvation with those caused by octanoate pretreatment, we measured glycerol release and H2O2 generation in rat adipocytes of starved donors. RESULTS: Pretreatment of adipocytes with octanoate in vitro increased basal lipolysis but decreased the cellular response for agonists. The same effects were seen in starvation in vivo. Preincubation with octanoate for 48 hours did not affect basal lipase activity, HSL, and perilipin protein levels, but it reduced agonist-stimulated perilipin phosphorylation and HSL translocation toward fat droplets. This was associated with a reduction in basal cellular adenosine triphosphate levels and agonist-stimulated cyclic adenosine monophosphate generation. Starvation and octanoate pretreatment both increased intracellular H2O2 concentrations, which might also contribute to the inhibition on agonist-stimulated lipolysis. DISCUSSION: Pretreatment with octanoate seems to induce changes in adipocyte lipolysis in a pattern mimicking the effects of starvation. Such changes could contribute, in part, to weight loss in animals and humans associated with dietary medium-chain FAs.