ASU Scholarship Showcase

Although emerging evidence indicates that deep-sea water contains an untapped reservoir of high metabolic and genetic diversity, this realm has not been studied well compared with surface sea water. The study provided the first integrated meta-genomic and -transcriptomic analysis of the microbial communities in deep-sea water of North Pacific Ocean. DNA/RNA amplifications and simultaneous metagenomic and metatranscriptomic analyses were employed to discover information concerning deep-sea microbial communities from four different deep-sea sites ranging from the mesopelagic to pelagic ocean. Within the prokaryotic community, bacteria is absolutely dominant (~90%) over archaea in both metagenomic and metatranscriptomic data pools. The emergence of archaeal phyla Crenarchaeota, Euryarchaeota, Thaumarchaeota, bacterial phyla Actinobacteria, Firmicutes, sub-phyla Betaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria, and the decrease of bacterial phyla Bacteroidetes and Alphaproteobacteria are the main composition changes of prokaryotic communities in the deep-sea water, when compared with the reference Global Ocean Sampling Expedition (GOS) surface water. Photosynthetic Cyanobacteria exist in all four metagenomic libraries and two metatranscriptomic libraries. In Eukaryota community, decreased abundance of fungi and algae in deep sea was observed. RNA/DNA ratio was employed as an index to show metabolic activity strength of microbes in deep sea. Functional analysis indicated that deep-sea microbes are leading a defensive lifestyle.

Attention deficit/hyperactivity disorder (ADHD) is a risk factor for tobacco use and dependence. This study examines the responsiveness to nicotine of an adolescent model of ADHD, the spontaneously hypertensive rat (SHR). The conditioned place preference (CPP) procedure was used to assess nicotine-induced locomotion and conditioned reward in SHR and the Wistar Kyoto (WKY) control strain over a range of nicotine doses (0.0, 0.1, 0.3 and 0.6 mg/kg). Prior to conditioning, SHRs were more active and less biased toward one side of the CPP chamber than WKY rats. Following conditioning, SHRs developed CPP to the highest dose of nicotine (0.6 mg/kg), whereas WKYs did not develop CPP to any nicotine dose tested. During conditioning, SHRs displayed greater locomotor activity in the nicotine-paired compartment than in the saline-paired compartment across conditioning trials. SHRs that received nicotine (0.1, 0.3, 0.6 mg/kg) in the nicotine-paired compartment showed an increase in locomotor activity between conditioning trials. Nicotine did not significantly affect WKY locomotor activity. These findings suggest that the SHR strain is a suitable model for studying ADHD-related nicotine use and dependence, but highlights potential limitations of the WKY control strain and the CPP procedure for modeling ADHD-related nicotine reward.

Cellular heterogeneity plays a pivotal role in a variety of functional processes in vivo including carcinogenesis. However, our knowledge about cell-to-cell diversity and how differences in individual cells manifest in alterations at the population level remains very limited mainly due to the lack of appropriate tools enabling studies at the single-cell level. We present a study on changes in cellular heterogeneity in the context of pre-malignant progression in response to hypoxic stress. Utilizing pre-malignant progression of Barrett’s esophagus (BE) as a disease model system we studied molecular mechanisms underlying the progression from metaplastic to dysplastic (pre-cancerous) stage. We used newly developed methods enabling measurements of cell-to-cell differences in copy numbers of mitochondrial DNA, expression levels of a set of mitochondrial and nuclear genes involved in hypoxia response pathways, and mitochondrial membrane potential. In contrast to bulk cell studies reported earlier, our study shows significant differences between metaplastic and dysplastic BE cells in both average values and single-cell parameter distributions of mtDNA copy numbers, mitochondrial function, and mRNA expression levels of studied genes. Based on single-cell data analysis, we propose that mitochondria may be one of the key factors in pre-malignant progression in BE.

Synthetic cathinones, colloquially referred to as “bath salts,” are derivatives of the psychoactive alkaloid cathinone found in Catha edulis (Khat). Since the mid-to-late 2000s, these amphetamine-like psychostimulants have gained popularity amongst drug users due to their potency, low cost, ease of procurement, and constantly evolving chemical structures. Concomitant with their increased use is the emergence of a growing collection of case reports of bizarre and dangerous behaviors, toxicity to numerous organ systems, and death. However, scientific information regarding the abuse liability of these drugs has been relatively slower to materialize. Recently we have published several studies demonstrating that laboratory rodents will readily self-administer the “first generation” synthetic cathinones methylenedioxypyrovalerone (MDPV) and methylone via the intravenous route, in patterns similar to those of methamphetamine. Under progressive ratio schedules of reinforcement, the rank order of reinforcing efficacy of these compounds is MDPV ≥ methamphetamine > methylone. MDPV and methylone, as well as the “second generation” synthetic cathinones α-pyrrolidinovalerophenone (α-PVP) and 4-methylethcathinone (4-MEC), also dose-dependently increase brain reward function. Collectively, these findings indicate that synthetic cathinones have a high abuse and addiction potential and underscore the need for future assessment of the extent and duration of neurotoxicity induced by these emerging drugs of abuse.

The maternal separation (MS) paradigm is an animal model of early life stress. Animals subjected to MS during the first 2 weeks of life display altered behavioral and neuroendocrinological stress responses as adults. MS also produces altered responsiveness to and self-administration (SA) of various drugs of abuse including cocaine, ethanol, and amphetamine. However, no studies have yet examined the effects of MS on methamphetamine (METH) SA. This study was performed to examine the effects of MS on the acquisition of METH SA, extinction, and reinstatement of METH-seeking behavior in adulthood. Given the known influence of early life stress and drug exposure on epigenetic processes, we also investigated group differences in levels of the epigenetic marker methyl CpG binding protein 2 (MeCP2) in the nucleus accumbens (NAc) core. Long–Evans pups and dams were separated on postnatal days (PND) 2–14 for either 180 (MS180) or 15 min (MS15). Male offspring were allowed to acquire METH SA (0.05 mg/kg/infusion) in 15 2-h daily sessions starting at PND67, followed by extinction training and cue-induced reinstatement of METH-seeking behavior. Rats were then assessed for MeCP2 levels in the NAc core by immunohistochemistry. The MS180 group self-administered significantly more METH and acquired SA earlier than the MS15 group. No group differences in extinction or cue-induced reinstatement were observed. MS15 rats had significantly elevated MeCP2-immunoreactive cells in the NAc core as compared to MS180 rats. Together, these data suggest that MS has lasting influences on METH SA as well as epigenetic processes in the brain reward circuitry.

Background: 5-HT1B receptor agonists enhance cocaine intake during daily self-administration sessions but decrease cocaine intake when tested after prolonged abstinence. We examined if 5-HT1B receptor agonists produce similar abstinence-dependent effects on methamphetamine intake.

Methods: Male rats were trained to self-administer methamphetamine (0.1 mg/kg, i.v.) on low (fixed ratio 5 and variable ratio 5) and high (progressive ratio) effort schedules of reinforcement until intake was stable. Rats were then tested for the effects of the selective 5-HT1B receptor agonist, CP 94,253 (5.6 or 10 mg/kg), or the less selective but clinically available 5-HT1B/1D receptor agonist, zolmitriptan (10 mg/kg), on methamphetamine self-administration both before and after a 21-day forced abstinence period during which the rats remained in their home cages.

Results: The inverted U-shaped, methamphetamine dose-response function for intake on the fixed ratio 5 schedule was shifted downward by CP 94,253 both before and after abstinence. The CP 94,253-induced decrease in methamphetamine intake was replicated in rats tested on a variable ratio 5 schedule, and the 5-HT1B receptor antagonist SB 224,289 (10 mg/kg) reversed this effect. CP 94,253 also attenuated methamphetamine intake on a progressive ratio schedule both pre- and postabstinence. Similarly, zolmitriptan attenuated methamphetamine intake on a variable ratio 5 schedule both pre- and postabstinence, and the latter effect was sustained after each of 2 more treatments given every 2 to 3 days prior to daily sessions.

Conclusions: Unlike the abstinence-dependent effect of 5-HT1B receptor agonists on cocaine intake reported previously, both CP 94,253 and zolmitriptan decreased methamphetamine intake regardless of abstinence. These findings suggest that 5-HT1B receptor agonists may have clinical efficacy for psychostimulant use disorders.

Illicit psychostimulant addiction remains a significant problem worldwide, despite decades of research into the neural underpinnings and various treatment approaches. The purpose of this review is to provide a succinct overview of the neurocircuitry involved in drug addiction, as well as the acute and chronic effects of cocaine and amphetamines within this circuitry in humans. Investigational pharmacological treatments for illicit psychostimulant addiction are also reviewed. Our current knowledge base clearly demonstrates that illicit psychostimulants produce lasting adaptive neural and behavioral changes that contribute to the progression and maintenance of addiction. However, attempts at generating pharmacological treatments for psychostimulant addiction have historically focused on intervening at the level of the acute effects of these drugs. The lack of approved pharmacological treatments for psychostimulant addiction highlights the need for new treatment strategies, especially those that prevent or ameliorate the adaptive neural, cognitive, and behavioral changes caused by chronic use of this class of illicit drugs.

Quantitative three-dimensional (3D) computed tomography (CT) imaging of living single cells enables orientation-independent morphometric analysis of the intricacies of cellular physiology. Since its invention, x-ray CT has become indispensable in the clinic for diagnostic and prognostic purposes due to its quantitative absorption-based imaging in true 3D that allows objects of interest to be viewed and measured from any orientation. However, x-ray CT has not been useful at the level of single cells because there is insufficient contrast to form an image. Recently, optical CT has been developed successfully for fixed cells, but this technology called Cell-CT is incompatible with live-cell imaging due to the use of stains, such as hematoxylin, that are not compatible with cell viability. We present a novel development of optical CT for quantitative, multispectral functional 4D (three spatial + one spectral dimension) imaging of living single cells. The method applied to immune system cells offers truly isotropic 3D spatial resolution and enables time-resolved imaging studies of cells suspended in aqueous medium. Using live-cell optical CT, we found a heterogeneous response to mitochondrial fission inhibition in mouse macrophages and differential basal remodeling of small (0.1 to 1 fl) and large (1 to 20 fl) nuclear and mitochondrial structures on a 20- to 30-s time scale in human myelogenous leukemia cells. Because of its robust 3D measurement capabilities, live-cell optical CT represents a powerful new tool in the biomedical research field.

Driven by an increasing number of studies demonstrating its relevance to a broad variety of disease states, the bioenergy production phenotype has been widely characterized at the bulk sample level. Its cell-to-cell variability, a key player associated with cancer cell survival and recurrence, however, remains poorly understood due to ensemble averaging of the current approaches. We present a technology platform for performing oxygen consumption and extracellular acidification measurements of several hundreds to 1,000 individual cells per assay, while offering simultaneous analysis of cellular communication effects on the energy production phenotype. The platform comprises two major components: a tandem optical sensor for combined oxygen and pH detection, and a microwell device for isolation and analysis of single and few cells in hermetically sealed sub-nanoliter chambers. Our approach revealed subpopulations of cells with aberrant energy production profiles and enables determination of cellular response variability to electron transfer chain inhibitors and ion uncouplers.

Background: Use of synthetic cathinones, which are designer stimulants found in “bath salts,” has increased dramatically in recent years. Following governmental bans of methylenedioxypyrovalerone, mephedrone, and methylone, a second generation of synthetic cathinones with unknown abuse liability has emerged as replacements.

Methods: Using a discrete trials current intensity threshold intracranial self-stimulation procedure, the present study assessed the effects of 2 common second-generation synthetic cathinones, α‐pyrrolidinopentiophenone (0.1–5mg/kg) and 4-methyl-N-ethcathinone (1–100mg/kg) on brain reward function. Methamphetamine (0.1–3mg/kg) was also tested for comparison purposes.

Results: Results revealed both α‐pyrrolidinopentiophenone and 4-methyl-N-ethcathinone produced significant intracranial self-stimulation threshold reductions similar to that of methamphetamine. α‐Pyrrolidinopentiophenone (1mg/kg) produced a significant maximal reduction in intracranial self-stimulation thresholds (~19%) most similar to maximal reductions produced by methamphetamine (1mg/kg, ~20%). Maximal reductions in intracranial self-stimulation thresholds produced by 4-methyl-N-ethcathinone were observed at 30mg/kg (~15%) and were comparable with those observed with methamphetamine and α‐pyrrolidinopentiophenone tested at the 0.3-mg/kg dose (~14%). Additional analysis of the ED50 values from log-transformed data revealed the rank order potency of these drugs as methamphetamine ≈ α‐pyrrolidinopentiophenone>4-methyl-N-ethcathinone.

Conclusions: These data suggest that the newer second-generation synthetic cathinones activate the brain reward circuitry and thus may possess a similar degree of abuse potential as prototypical illicit psychostimulants such as methamphetamine as well as the first generation synthetic cathinone methylenedioxypyrovalerone, as previously reported.