Morphology and histology of brown fats from control and <i>Bmal1</i> null mice.

<p>A. H&E staining of BAT from WT and <i>Bmal1</i> KO mice at 10 days, 10 weeks, or 5 months of age. The bar represents 100 µm. B. BAT/body weight ratio in 10-day old pups. C. Appearance of brown adipose tissues from 10-week old WT and KO mice. D–E. BAT/body weight and gWAT/body weight ratio in 10-week (D) or 5-month (E) old mice. Data represent mean ± SEM, WT (n = 4–6) vs. KO (n = 4–6), *p<0.05, **p<0.01.</p

Role of <i>Bmal1</i> in brown adipocyte differentiation.

<p>A. Time course expression of Bmal1 and Clock during brown adipocyte differentiation. B. Oil Red-O staining of adipocytes following 7 days of differentiation. C. qPCR analyses of brown adipocyte gene expression during differentiation. D. qPCR analyses of brown adipocyte gene expression following treatments with vehicle or 1 µM NE for 5 hrs. Data are collected from 3 replicates and represent mean ± stdev. WT vs. KO, *p<0.05, **p<0.01.</p

The Biological Clock is Regulated by Adrenergic Signaling in Brown Fat but is Dispensable for Cold-Induced Thermogenesis

<div><p>The biological clock plays an important role in integrating nutrient and energy metabolism with other cellular processes. Previous studies have demonstrated that core clock genes are rhythmically expressed in peripheral tissues, including the liver, skeletal muscle, pancreatic islets, and white and brown adipose tissues. These peripheral clocks are entrained by physiological cues, thereby aligning the circadian pacemaker to tissue functions. The mechanisms that regulate brown adipose tissue clock in response to physiological signals remain poorly understood. Here we found that the expression of core clock genes is highly responsive to cold exposure in brown fat, but not in white fat. This cold-inducible regulation of the clock network is mediated by adrenergic receptor activation and the transcriptional coactivator PGC-1α. Brown adipocytes in mice lacking a functional clock contain large lipid droplets accompanied by dysregulation of genes involved in lipid metabolism and adaptive thermogenesis. Paradoxically, the “clockless” mice were competent in maintaining core body temperature during cold exposure. These studies elucidated the presence of adrenergic receptor/clock crosstalk that appears to be required for normal thermogenic gene expression in brown fat.</p></div

Regulation of clock gene expression in adipose tissues by cold exposure.

<p>Mice were maintained at ambient temperature (24°C, open, n = 5) or exposed to cold (4°C, filled, n = 4) for 5 hours. qPCR analyses of gene expression in BAT (A) and WAT (B). Data represent mean ± SEM, 24°C vs. 4°C, *p<0.05. **p<0.01.</p

Requirements of β-adrenergic signaling and <i>PGC-1α</i> in <i>Bmal1</i> expression.

<p>A. qPCR analyses of BAT gene expression in saline-injected mice housed at room temperature (24°C, n = 4) and mice treated with saline (filled, n = 4) or propranolol (grey, n = 4) after 3 hrs of cold exposure. Data represent mean ± SEM, saline vs. propranolol at 4°C, *p<0.05. B. <i>Bmal1</i> mRNA expression in WT (filled) and <i>PGC-1α</i> null (open) mouse brown fat. Mice were housed at ambient temperature (n = 4 per WT or KO group) or subjected to cold exposure for 3.5 hrs (n = 6 per WT or KO group). Data represent mean ± SEM, WT vs. KO, *p<0.05. **p<0.01.</p

Circadian regulation of BAT gene expression.

<p>BAT from WT and <i>Bmal1</i> KO mice were collected at ZT4, 10, 16, and 22 (Zeitgeber time 0 is defined as the onset of subjective light phase; n = 4–6 mice for each data point per group). Total RNA was isolated for qPCR analyses of clock and metabolic gene expression. Data represent mean ± SEM. WT vs. KO, *p<0.05, **p<0.01.</p

<i>Bmal1</i>-deficient mice are cold-tolerant.

<p>A. Rectal temperature in Bmal1 WT (n = 5) and KO (n = 4) mice during cold exposure. B. qPCR analyses BAT gene expression in WT (filled) and KO (open) mice at room temperature (24°C) or 5 hours after cold exposure (4°C). C. Immunoblots of total BAT lysates from treated mice. D. The UCP1 and PGC-1α protein levels were graphed from immunoblot C after normalization to TUBULIN. E. Skeletal muscle gene expression in WT (n = 4) and KO (n = 4) mice after cold exposure. Data represent mean ± SEM, WT vs. KO, *p<0.05, **p<0.01.</p

Slow Electron–Hole Recombination in Lead Iodide Perovskites Does Not Require a Molecular Dipole

Hybrid organic/inorganic lead iodide perovskites of the formula APbI₃, where A is a molecular cation such as methylammonium, exhibit remarkably slow photoinduced charge carrier recombination rates, for reasons that remain uncertain. Prevalent hypotheses credit this behavior to the unique dipolar nature of the molecular cation. Herein, transient terahertz spectroscopy is applied to solution-processed, all-inorganic, perovskite-phase cesium lead iodide (CsPbI₃) thin films, which lack such a dipole. The recombination kinetics are studied as a function of the initial photoinduced carrier concentration and the wavelength of excitation. A kinetic model combining diffusion and recombination is fit to the data, from which the rate constants are determined, revealing a bimolecular recombination rate of 10^–10 cm³ s^–1, comparable to high-quality, single-crystal, direct-gap semiconductors. This rate, as well as a charge carrier mobility > 30 cm² V^–1 s^–1 measured herein for CsPbI₃, are similar to values reported for the hybrid perovskites, strongly suggesting that the organic cation does not confer a fundamental advantage

Molecular mechanism of the selectivity between BAFF/APRIL and their receptors by molecular simulations

<p>B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) belonging to the tumour necrosis factor (TNF) ligand family can bind three unusual TNF receptors (BCMA, TACI and BR3) with various binding affinities. BAFF and APRIL are regarded as promising therapeutic targets for autoimmune diseases because of their pivotal roles in cell survival and immune regulation. In this work, we carried out molecular dynamics calculations to explore the structural and chemical features responsible for ligand recognition by extracellular functional segments of TNF receptors. We found that the conserved pocket D_cons of BAFF/APRIL contacted the DxL motif of TNF receptors, while the D_spe1–3 sub-domains were responsible for their different affinities, especially D_spe1 and D_spe2. The residues at position II–V of DxL motif were wrapped into the D_cons pocket via salt-bridge and hydrophobic interactions. The hydrophobic residues of strand3 and helix1 in TNF receptors provided remarkable contributions for the affinities to BAFF/APRIL. Additionally, Arg^VI of DxL motif played a key role in the binding selectivity via salt-bridge interaction with residue D275B in BAFF. Arg27 in BCMA contributed to the high affinity for APRIL so that BCMA showed a preference for APRIL. Our studies indicated that Arg84 and Gln95 in TACI2 played an important role in the selectivity of two cysteine-rich domain segments in TACI, leading to the higher binding affinities of TACI2 than those of TACI1. The primary cause of the disability to bind APRIL was the space conflict with the rigid conformation of the C-terminus coil of BR3. These thorough understanding of the molecular mechanism for BAFF/APRIL recognition by their receptors provides new insights for guiding inhibitor design.</p

Kinetics Study of Hydrogenation of Dimethyl Oxalate over Cu/SiO₂ Catalyst

Gas-phase hydrogenation of dimethyl oxalate (DMO) on a copper-based catalyst is one of the crucial technologies in the production of ethylene glycol (EG) from syngas. Even though Cu/SiO₂ catalyst is widely used in ester hydrogenation reactions, a kinetics study considering multiple active sites has not yet been reported. In this study, a series of experiments were carried out to investigate the heterogeneous catalytic reaction kinetics of the hydrogenation of DMO over Cu/SiO₂ catalyst. Considering different situations of ester adsorption, H₂ adsorption, and active sites, 34 possible kinetics models were proposed and screened to identify the one most appropriate to describe the hydrogenation of DMO over Cu/SiO₂ catalyst. With the help of relevant thermodynamic theories and statistical evaluations, the optimal model was found to fit well to our experimental data. This model proved that the hydrogenation of DMO depends on the synergistic effect of two active sites, wherein hydrogen and the ester were adsorbed on two different active sites with dissociative states. The dissociative adsorption of the ester was found to be the rate-controlling step in the hydrogenation of DMO over Cu/SiO₂ catalyst prepared by an ammonia-evaporation method