Dystroglycan Adds More Sugars to the Midline Cocktail

In this issue of Neuron, Wright et al. (2012) identify two novel mediators of α-dystroglycan glycosylation in mouse and unravel a novel function of glycosylated dystroglycan in axon guidance by providing evidence for direct binding of α-DG to the midline chemorepellent Slit2

Local circuit amplification of spatial selectivity in the hippocampus

Local circuit architecture facilitates the emergence of feature selectivity in the cerebral cortex1. In the hippocampus, it remains unknown whether local computations supported by specific connectivity motifs2 regulate the spatial receptive fields of pyramidal cells3. Here we developed an in vivo electroporation method for monosynaptic retrograde tracing4 and optogenetics manipulation at single-cell resolution to interrogate the dynamic interaction of place cells with their microcircuitry during navigation. We found a local circuit mechanism in CA1 whereby the spatial tuning of an individual place cell can propagate to a functionally recurrent subnetwork5 to which it belongs. The emergence of place fields in individual neurons led to the development of inverse selectivity in a subset of their presynaptic interneurons, and recruited functionally coupled place cells at that location. Thus, the spatial selectivity of single CA1 neurons is amplified through local circuit plasticity to enable effective multi-neuronal representations that can flexibly scale environmental features locally without degrading the feedforward input structure

Formalism for dilepton production via virtual photon bremsstrahlung in hadronic reactions

We derive a set of new formulas for various distributions in dilepton production via virtual photon bremsstrahlung from pseudoscalar mesons and unpolarized spin-one-half fermions. These formulas correspond to the leading and sub-leading terms in the Low-Burnett-Kroll expansion for real photon bremsstrahlung. The relation of our leading-term formulas to previous works is also shown. Existing formulas are examined in the light of Lorentz covariance and gauge invariance. Numerical comparison is made in a simple example, where an "exact" formula and real photon data exist. The results reveal large discrepancies among different bremsstrahlung formulas. Of all the leading-term bremsstrahlung formulas, the one derived in this work agrees best with the exact formula. The issues of M_T-scaling and event generators are also addressed.Comment: 37 pages, RevTeX, epsf.sty, 10 embedded figure

Measurement of the lifetime of hadrons containing the b-quark

Data collected with the High Resolution Spectrometer at PEP, corresponding to an integrated luminosity of 200 pb-1 of e+e- annihilation at 29 GeV, were used to measure the mean lifetime of hadrons containing the bottom quark. The lifetime was determined using the impact parameter method on events containing a high-transverse-momentum electron. The result, based on a sample of 301 events, is [tau]B = 1.02 +/-0.390.42 ps, where the indicated errors include both statistics and systematics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26581/1/0000120.pd

Neutral K*(890) and [rho]0 meson production in e+e- annihilation at

The production of neutral K*(890) and [rho]0 mesons was studied in e+e- annihilation at using the High Resolution Spectrometer at PEP. Differential cross sections are presented as a function of the scaled energy variable z and compared to [pi]0 and K0 production. The measured multiplicities are 0.84+/-0.08 [varrho]0 mesons and 0.57+/-0.09 K*0(890) mesons per event for a meson momentum greater than 725 MeV/c. The ratios of vector meson to pseudoscalar meson production for (u,d), s and c quark are compared to predictions of the Lund model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25574/3/0000116.pd

Measurement of the D 0 → K - Π + Branching Fraction a

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72296/1/j.1749-6632.1988.tb51529.x.pd

Identification of slit3 as a locus affecting nicotine preference in zebrafish and human smoking behaviour

To facilitate smoking genetics research we determined whether a screen of mutagenized zebrafish for nicotine preference could predict loci affecting smoking behaviour. From 30 screened F-3 sibling groups, where each was derived from an individual ethyl-nitrosurea mutagenized F-0 fish, two showed increased or decreased nicotine preference. Out of 25 inactivating mutations carried by the F-3 fish, one in the slit3 gene segregated with increased nicotine preference in heterozygous individuals. Focussed SNP analysis of the human SLIT3 locus in cohorts from UK (n=863) and Finland (n=1715) identified two variants associated with cigarette consumption and likelihood of cessation. Characterisation of slit3 mutant larvae and adult fish revealed decreased sensitivity to the dopaminergic and serotonergic antagonist amisulpride, known to affect startle reflex that is correlated with addiction in humans, and increased htr1aa mRNA expression in mutant larvae. No effect on neuronal pathfinding was detected. These findings reveal a role for SLIT3 in development of pathways affecting responses to nicotine in zebrafish and smoking in humans.Peer reviewe

Charged particle multiplicity distributions in e + e − annihilation at 29 GeV: a comparison with hadronic data

The charged particle multiplicity distributions for two-jet events in e + e − annihilation at 29 GeV have been measured using the High Resolution Spectrometer at PEP. A Poisson distribution describes the data for both the complete event and for the single jets. In addition, no correlation is observed between the multiplicities in the two jets of an event. For fixed values of the prong number of the complete event, the multiplicity sharing between the two jets is in good agreement with a binomial distribution. The rapidity gap distribution is exponential with a slope equal to the mean rapidity density. These observations, which are consistent with a picture of independent emission of single particles, are contrasted to the results from soft hadronic collisions and conclusions are drawn about the nature of clusters.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47881/1/10052_2005_Article_BF01570767.pd