Genetic Dissection of Acute Ethanol Responsive Gene Networks in Prefrontal Cortex: Functional and Mechanistic Implications

Background Individual differences in initial sensitivity to ethanol are strongly related to the heritable risk of alcoholism in humans. To elucidate key molecular networks that modulate ethanol sensitivity we performed the first systems genetics analysis of ethanol-responsive gene expression in brain regions of the mesocorticolimbic reward circuit (prefrontal cortex, nucleus accumbens, and ventral midbrain) across a highly diverse family of 27 isogenic mouse strains (BXD panel) before and after treatment with ethanol. Results Acute ethanol altered the expression of ~2,750 genes in one or more regions and 400 transcripts were jointly modulated in all three. Ethanol-responsive gene networks were extracted with a powerful graph theoretical method that efficiently summarized ethanol\u27s effects. These networks correlated with acute behavioral responses to ethanol and other drugs of abuse. As predicted, networks were heavily populated by genes controlling synaptic transmission and neuroplasticity. Several of the most densely interconnected network hubs, including Kcnma1 and Gsk3β, are known to influence behavioral or physiological responses to ethanol, validating our overall approach. Other major hub genes like Grm3, Pten and Nrg3 represent novel targets of ethanol effects. Networks were under strong genetic control by variants that we mapped to a small number of chromosomal loci. Using a novel combination of genetic, bioinformatic and network-based approaches, we identified high priority cis-regulatory candidate genes, including Scn1b,Gria1, Sncb and Nell2. Conclusions The ethanol-responsive gene networks identified here represent a previously uncharacterized intermediate phenotype between DNA variation and ethanol sensitivity in mice. Networks involved in synaptic transmission were strongly regulated by ethanol and could contribute to behavioral plasticity seen with chronic ethanol. Our novel finding that hub genes and a small number of loci exert major influence over the ethanol response of gene networks could have important implications for future studies regarding the mechanisms and treatment of alcohol use disorders

Probing built-in strain in freestanding graphene monolayers by Raman spectroscopy

We report a detailed spatially resolved Raman study on a set of eight pristine freestanding graphene monolayers. While we find, as previously reported, that freestanding graphene is quasi-undoped, our study also reveals that non-negligible built-in strain occurs in these samples. The level of built-in strain varies significantly from one sample to another and can be estimated with accuracy from the correlation of the frequencies of the G and 2D Raman modes. Sample-dependent compressive and tensile strains as high as 0.1% are reported. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Nest building is a novel method for indexing severity of alcohol withdrawal in mice

Withdrawal after chronic ethanol (EtOH) affects body temperature, goal-directed behavior and motor function in mice and increases general central nervous system excitability. Nest-building tests have been used to assay these states but to this point have not been employed as measures of EtOH withdrawal severity. We first refined nest-scoring methods using a genetically heterogeneous stock of mice (HS/Npt). Mice were then made physically dependent following three days of chronic EtOH vapor inhalation to produce average blood EtOH concentrations (BECs) of 1.89 mg/mL. EtOH withdrawal affected the progression of nest building over time when mice were tested 2–4 days after removal from three days of chronic exposure to EtOH. In a separate group of mice, chronic EtOH vapor inhalation (BECs 1.84 mg/mL) suppressed nest building over days 1–2 but not days 2–3 of withdrawal. In a following experiment, EtOH withdrawal dose-dependently slowed recovery of nest building for up to 32 h. Finally, we determined that long-lasting nest-building deficits extend to mice undergoing withdrawal from a high dose (4 g/kg) of acute EtOH. Sex differences for nest building were absent following EtOH exposure. In mice naïve to EtOH treatments, male mice had lower pre-test body temperatures and increased nest scores across a two-day testing period compared to females. These results suggest that nest building can be used to assess chronic and acute EtOH withdrawal severity in mice

Room temperature dry processing of patterned CVD graphene devices

We present a strategy for avoiding polymeric residues, excessive heating and solvent exposure when transforming large area transferred CVD graphene single layer films into series of planar devices. Such dry process is a key prerequisite for chemical functionalization applications or for organic electronics compatibility, and opens the possibility to integrate graphene electrodes with thermally or chemically sensitive materials, as well as substrates incompatible with lithography processing. Patterning and metal evaporation are performed through a multi-step mechanical stencils methodology, and low temperatures magneto transport measurements are used to validate devices with preserved electrical fingerprints of graphene. This is particularly critical for the argon beam milling process step. Remarkably, the Quantum Hall signature of our devices remains robust, even though defective sample edges result from the beam exposure. Shubnikov-de Hass (SdH) oscillations and weak (anti-) localization signatures of monolayer graphene confirm the excellent intrinsic properties of such processed samples, rarely observed on CVD-processed devices