Use of Whole Genome Phylogeny and Comparisons in the Development of a Multiplex-PCR Assay to Identify Sequence Type 36 Vibrio parahaemolyticus

Vibrio parahaemolyticus sequence type (ST) 36 strains that are native to the Pacific Ocean have recently caused multi-state outbreaks of gastroenteritis linked to shellfish harvested from the Atlantic Ocean. Whole genome comparisons of 295 genomes of V. parahaemolyticus, including several traced to northeastern US sources, were used to identify diagnostic loci: one putatively encoding an endonuclease (prp), and two others potentially conferring O-antigenic properties (cps and flp). The combination of all three loci was present only in one clade of closely-related strains, of ST36, ST59 and one additional unknown sequence type. However, each locus was also identified outside this clade, with prp and flp occurring in only two non-clade isolates, and cps in four. Based on the distribution of these loci in sequenced genomes, prp could identify clade strains with \u3e99% accuracy, but the addition of one more locus would increase accuracy to 100%. Oligonucleotide primers targeting prp and cps were combined in a multiplex PCR method that defines species using the tlh locus, and determines presence of both the tdh and trh hemolysin-encoding genes which are also present in ST36. Application of the method in vitro to a collection of 94 clinical isolates collected over a four year period in three Northeastern US, and 87 environmental isolates, revealed the prp and cps amplicons were only detected in clinical isolates identified as belonging to the ST36-clade, and in no environmental isolates from the region. The assay should improve detection and surveillance, thereby reducing infections

Nicotine binding to brain receptors requires a strong cation–π interaction

Nicotine addiction begins with high-affinity binding of nicotine to acetylcholine (ACh) receptors in the brain. The end result is over 4,000,000 smoking-related deaths annually worldwide and the largest source of preventable mortality in developed countries. Stress reduction, pleasure, improved cognition and other central nervous system effects are strongly associated with smoking. However, if nicotine activated ACh receptors found in muscle as potently as it does brain ACh receptors, smoking would cause intolerable and perhaps fatal muscle contractions. Despite extensive pharmacological, functional and structural studies of ACh receptors, the basis for the differential action of nicotine on brain compared with muscle ACh receptors has not been determined. Here we show that at the α4β2 brain receptors thought to underlie nicotine addiction, the high affinity for nicotine is the result of a strong cation–π interaction to a specific aromatic amino acid of the receptor, TrpB. In contrast, the low affinity for nicotine at the muscle type ACh receptor is largely due to the fact that this key interaction is absent, even though the immediate binding site residues, including the key amino acid TrpB, are identical in the brain and muscle receptors. At the same time a hydrogen bond from nicotine to the backbone carbonyl of TrpB is enhanced in the neuronal receptor relative to the muscle type. A point mutation near TrpB that differentiates α4β2 and muscle-type receptors seems to influence the shape of the binding site, allowing nicotine to interact more strongly with TrpB in the neuronal receptor. ACh receptors are established therapeutic targets for Alzheimer’s disease, schizophrenia, Parkinson’s disease, smoking cessation, pain, attention-deficit hyperactivity disorder, epilepsy, autism and depression. Along with solving a chemical mystery in nicotine addiction, our results provide guidance for efforts to develop drugs that target specific types of nicotinic receptors

Isomeric Xylene Molecules in the Terahertz Far Infrared Regime Computational Chemistry and Spectral Modeling View

The theoretical assignments of spectral peaks of liquid phase ortho , meta , and para xylene recorded with far infrared FIR and THz spectroscopy in the spectral range between 550 and 50 cm amp; 8722;1 is done with density functional theory DFT calculations. As THz spectroscopic techniques drastically evolved in recent years, the critical focus of this paper lies on the applicability of theoretical concepts, used as computational standard in near and mid IR spectra, to the FIR THz region. An evaluation of the choice of functionals, basis sets, and appropriate scaling factors as well as the tractability of the liquid phase in a polarizable continuum model is performed. Alongside a new analysis procedure based on spectral Hard Modeling has been developed. DFT line spectra are fitted to experimental FIR spectra where a quantitative track record allows for meaningful comparisons. With all these tools we are able to reproduce experimental spectra in an optically appealing way and we can explain trends for each spectrum as well as across the row of the isomer

Between the Literary and the Visual: Inter-Artistic Approaches to African-American Art History

A stubborn truism vexes African-American art history: the canon of black American literature is viewed as more established and robust than that of black American visual arts. This misconception has more to do with conventional disciplinary divisions, than it does with either the quantity or quality of black visual expression. Segregating the literary from the visual --and assigning these to English and Art History departments, respectively--has obscured the originally inter-artistic nature of much black cultural expression as well as the terms of its early reception and critique. African-American artists have repeatedly worked in black literary contexts--from Aaron Douglas\u27s illustrations for Alain Locke\u27s The New Negro to Glenn Ligon\u27s painted excerpts from Ralph Ellison and Richard Pryor. At the same time, many (nonblack) literary critics have been enthusiastic interpreters of black visual arts. Theater critic and novelist Carl Van Vechten promoted the painters of the Harlem Renaissance; Sidney Hirsch, one of Vanderbilt University\u27s influential literary modernists, discovered black folk sculptor William Edmondson; and French poststructuralist Roland Barthes famously used a photograph by James Van Der Zee to explain his concept of the photographic punctum. This panel seeks papers that take stock of this prodigious overlap between the literary and the visual arts. Participants are invited to address how literature and literary criticism may productively inform African-American art history, to recount the specific historical circumstances that compel this approach, and to consider broadly how attention to inter-artistic histories might helpfully reform both approaches to and canons of black cultural expression

Probing the Effects of Residues Located Outside the Agonist Binding Site on Drug-Receptor Selectivity in the Nicotinic Receptor

The nicotinic acetylcholine receptors (nAChRs) are a family of closely related but pharmacologically distinct neurotransmitter-gated ion channels. They are therapeutic targets for a wide range of neurological disorders, and a key issue in drug development is selective targeting among the more than 20 subtypes of nAChRs that are known. The present work evaluates a proposed hydrogen bonding interaction involving a residue known as the “loop B glycine” that distinguishes receptors that are highly responsive to ACh and nicotine from those that are much less so. We have performed structure–function studies on the loop B site, including unnatural amino acid mutagenesis, in three different nAChR subtypes and found that the correlation between agonist potency and this residue is strong. Low potency receptor subtypes have a glycine at this key site, and mutation to a residue with a side chain converts a low potency receptor to a high potency receptor. Innately high potency receptors have a lysine at the loop B site and show a decrease in potency for the reverse mutation (i.e., introducing a glycine). This residue lies outside of the agonist binding site, and studies of other residues at the agonist binding site show that the details of how changes at the loop B glycine site impact agonist potency vary for differing receptor subtypes. This suggests a model in which the loop B residue influences the global shape of the agonist binding site rather than modulating any specific interaction

α4* Nicotinic Receptors in preBotzinger Complex Mediate Cholinergic/Nicotinic Modulation of Respiratory Rhythm

Acetylcholine and nicotine can modulate respiratory patterns by acting on nicotinic acetylcholine receptors (nAChRs) in the preBötzinger complex (preBötC). To further explore the molecular composition of these nAChRs, we studied a knock-in mouse strain with a leucine-to-alanine mutation in the M2 pore-lining region (L9′A) of the nAChR α4 subunit; this mutation renders α4-containing receptors hypersensitive to agonists. We recorded respiratory-related rhythmic motor activity from hypoglossal nerve (XIIn) and patch-clamped preBötC inspiratory neurons in an in vitro medullary slice preparation from neonatal mice. Nicotine affected respiratory rhythm at concentrations ∼100-fold lower in the homozygous L9′A knock-in mice compared with wild-type mice. Bath application of 5 nm nicotine increased the excitability of preBötC inspiratory neurons, increased respiratory frequency, and induced tonic/seizure-like activities in XIIn in L9′A mice, effects similar to those induced by 1 μm nicotine in wild-type mice. In L9′A mice, microinjection of low nanomolar concentrations of nicotine into the preBötC increased respiratory frequency, whereas injection into the ipsilateral hypoglossal (XII) nucleus induced tonic/seizure-like activity. The α4*-selective nAChR antagonist dihydro-β-erythroidine produced opposite effects and blocked the nicotinic responses. These data, showing that nAChRs in the preBötC and XII nucleus in L9'A mice are hypersensitive to nicotine and endogenous ACh, suggest that functional α4* nAChRs are present in the preBötC. They mediate cholinergic/nicotinic modulation of the excitability of preBötC inspiratory neurons and of respiratory rhythm. Furthermore, functional α4* nAChRs are present in XII nucleus and mediate cholinergic/nicotinic modulation of tonic activity in XIIn