Pb(II)-inducible proviolacein biosynthesis enables a dual-color biosensor toward environmental lead.

With the rapid development of synthetic biology, various whole-cell biosensors have been designed as valuable biological devices for the selective and sensitive detection of toxic heavy metals in environmental water. However, most proposed biosensors are based on fluorescent and bioluminescent signals invisible to the naked eye. The development of visible pigment-based biosensors can address this issue. The pbr operon from Klebsiella pneumoniae is selectively induced by bioavailable Pb(II). In the present study, the proviolacein biosynthetic gene cluster was transcriptionally fused to the pbr Pb(II) responsive element and introduced into Escherichia coli. The resultant biosensor responded to Pb(II) in a time- and dose-dependent manner. After a 5-h incubation with Pb(II), the brown pigment was produced, which could be extracted into n-butanol. Extra hydrogen peroxide treatment during n-butanol extract resulted in the generation of a stable green pigment. An increased brown signal was observed upon exposure to lead concentrations above 2.93 nM, and a linear regression was fitted from 2.93 to 3,000 nM. Extra oxidation significantly decreased the difference between parallel groups. The green signal responded to as low as 0.183 nM Pb(II), and a non-linear regression was fitted in a wide concentration range from 0.183 to 3,000 nM. The specific response toward Pb(II) was not interfered with by various metals except for Cd(II) and Hg(II). The PV-based biosensor was validated in monitoring bioaccessible Pb(II) spiked into environmental water. The complex matrices did not influence the regression relationship between spiked Pb(II) and the dual-color signals. Direct reading with the naked eye and colorimetric quantification enable the PV-based biosensor to be a dual-color and low-cost bioindicator for pollutant heavy metal.

Evolution and neural representation of mammalian cooperative behavior.

Cooperation is common in nature and is pivotal to the development of human society. However, the details of how and why cooperation evolved remain poorly understood. Cross-species investigation of cooperation may help to elucidate the evolution of cooperative strategies. Thus, we design an automated cooperative behavioral paradigm and quantitatively examine the cooperative abilities and strategies of mice, rats, and tree shrews. We find that social communication plays a key role in the establishment of cooperation and that increased cooperative ability and a more efficient cooperative strategy emerge as a function of the evolutionary hierarchy of the tested species. Moreover, we demonstrate that single-unit activities in the orbitofrontal and prelimbic cortex in rats represent neural signals that may be used to distinguish between the cooperative and non-cooperative tasks, and such signals are distinct from the reward signals. Both signals may represent distinct components of the internal drive for cooperation.

Mu-Opioid Receptors Expressed in Glutamatergic Neurons are Essential for Morphine Withdrawal.

Although opioids still remain the most powerful pain-killers, the chronic use of opioid analgesics is largely limited by their numerous side-effects, including opioid dependence. However, the mechanism underlying this dependence is largely unknown. In this study, we used the withdrawal symptoms precipitated by naloxone to characterize opioid dependence in mice. We determined the functional role of mu-opioid receptors (MORs) expressed in different subpopulations of neurons in the development of morphine withdrawal. We found that conditional deletion of MORs from glutamatergic neurons expressing vesicular glutamate transporter 2 (Vglut2+) largely eliminated the naloxone-precipitated withdrawal symptoms. In contrast, conditional deletion of MORs expressed in GABAergic neurons had a limited effect on morphine withdrawal. Consistently, mice with MORs deleted from Vglut2+ glutamatergic neurons also showed no morphine-induced locomotor hyperactivity. Furthermore, morphine withdrawal and morphine-induced hyperactivity were not significantly affected by conditional knockout of MORs from dorsal spinal neurons. Taken together, our data indicate that the development of morphine withdrawal is largely mediated by MORs expressed in Vglut2+ glutamatergic neurons.

Short-term intensive atorvastatin therapy improves endothelial function partly via attenuating perivascular adipose tissue inflammation through 5-lipoxygenase pathway in hyperlipidemic rabbits.

BACKGROUND: Atherosclerosis is a kind of disease with multiple risk factors, of which hyperlipidemia is a major classical risk factor resulting in its pathogenesis and development. The aim of this study was to determine the effects of short-term intensive atorvastatin (IA) therapy on vascular endothelial function and explore the possible mechanisms that may help to explain the clinical benefits from short-term intensive statin therapy. METHODS: After exposure to high-fat diet (HFD) for 8 weeks, the animals were, respectively, treated with IA or low-dose atorvastatin (LA) for 5 days. Blood lipids, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide (NO), endothelin-1 (ET-1), and endothelium-dependent vasorelaxation function were, respectively, measured. mRNA and protein expression of CRP, TNF-α, IL-6, macrophage chemoattractant protein-1 (MCP-1), and 5-lipoxygenase (5-LO) were also evaluated in pericarotid adipose tissue (PCAT) and cultured adipocytes. RESULTS: HFD increased serum inflammatory factor levels; induced significant hyperlipidemia and endothelial dysfunction, including imbalance between NO and ET-1; enhanced inflammatory factors and 5-LO expression; and promoted macrophage infiltration into adipose tissue. Five-day IA therapy could significantly decrease serum inflammatory factor levels and their expression in PCAT; restore the balance between NO and ET-1; and improve endothelial function and macrophage infiltration without significant changes in blood lipids. However, all of the above were not observed in LA therapy. In vitro experiment found that lipopolysaccharide (LPS) enhanced the expression of inflammatory factors and 5-LO in cultured adipocytes, which could be attenuated by short-time (6 hours) treatment of high-dose (5 µmol/L) but not low-dose (0.5 µmol/L) atorvastatin. In addition, inhibiting 5-LO by Cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC, a potent and direct 5-LO inhibitor) could significantly downregulate the above-mentioned gene expression in LPS-treated adipocytes. CONCLUSION: Short-term IA therapy could significantly ameliorate endothelial dysfunction induced by HFD, which may be partly due to attenuating inflammation of PCAT through inhibiting 5-LO pathway.