Showing 1981 - 1990 of 2039 Items
The tyrosine kinase Abl and its substrate enabled collaborate with the receptor phosphatase Dlar to control motor axon guidance
Date: 1999-01-01
Creator: Zachary Wills
Jack Bateman
Christopher A. Korey
Allen Comer
David, Van Vactor
Access: Open access
- Genetic analysis of growth cone guidance choice points in Drosophila identified neuronal receptor protein tyrosine phosphatases (RPTPs) as key determinants of axon pathfinding behavior. We now demonstrate that the Drosophila Abl tyrosine kinase functions in the intersegmental nerve b (ISNb) motor choice point pathway as an antagonist of the RPTP Dlar. The function of Abl in this pathway is dependent on an intact catalytic domain. We also show that the Abl phosphoprotein substrate Enabled (Ena) is required for choice point navigation. Both Abl and Ena proteins associate with the Dlar cytoplasmic domain and serve as substrates for Dlar in vitro, suggesting that they play a direct role in the Dlar pathway. These data suggest that Dlar, Abl, and Ena define a phosphorylation state-dependent switch that controls growth cone behavior by transmitting signals at the cell surface to the actin cytoskeleton.
Measurement of the B̄→D*lν̄ branching fractions and -Vcb-
Date: 1995-01-01
Creator: B. Barish
M. Chadha
S. Chan
D. F. Cowen
G., Eigen
J. S. Miller
C. O'Grady
J. Urheim
A. J. Weinstein
D. Acosta
M. Athanas
G. Masek
H. P. Paar
J. Gronberg
R. Kutschke
S. Menary
R. J. Morrison
S. Nakanishi
H. N. Nelson
T. K. Nelson
C. Qiao
J. D. Richman
A. Ryd
H. Tajima
D. Sperka
M. S. Witherell
M. Procario
R. Balest
K. Cho
M. Daoudi
W. T. Ford
Access: Open access
- We study the exclusive semileptonic B meson decays B-→D*0l-ν̄ and B̄0→D*+l-ν̄ using data collected with the CLEO II detector at the Cornell Electron-positron Storage Ring (CESR). We present measurements of the branching fractions scrB(B̄0→D*+l-ν̄)= (0.5/f00)[4.49±0.32(stat.)±0.39 (syst.)]% and scrB(B-→D*0l-(ν̄)= (0.5/f+-)[5.13±0.54 (stat) ±0.64 (syst)]%, where f00 and f+- are the neutral and charged B meson production fractions at the Υ(4S) resonance, respectively. Assuming isospin invariance and taking the ratio of charged to neutral B meson lifetimes measured at higher energy machines, we determine the ratio f+-/f00=1.04±0.13 (stat) ±0.12 (syst) ±0.10 (lifetime); further assuming f+-+f00=1 we also determine the partial width Γ(B̄→D*lν̄)=[29.9±1.9 (stat) ±2.7 (syst.) ±2.0 (lifetime)] ns-1 (independent of f+-/f00). From this partial width we calculate B̄→D*lν̄ branching fractions that do not depend on f+-/f00 or the individual B lifetimes, but only on the charged to neutral B lifetime ratio. The product of the CKM matrix element -Vcb- times the normalization of the decay form factor at the point of no recoil of the D* meson, scrF(y=1), is determined from a linear fit to the combined differential decay rate of the exclusive B̄→D*lν̄ decays: -Vcb-scrF(1)=0.0351±0.0019 (stat) ±0.0018 (syst) ±0.0008 (lifetime). The value for -Vcb- is extracted using theoretical calculations of the form factor normalization. © 1995 The American Physical Society.
Measurement of cabibbo-suppressed decays of the τ lepton
Date: 1994-01-01
Creator: M. Battle
J. Ernst
Y. Kwon
S. Roberts
E. H., Thorndike
C. H. Wang
J. Dominick
M. Lambrecht
S. Sanghera
V. Shelkov
T. Skwarnicki
R. Stroynowski
I. Volobouev
G. Wei
P. Zadorozhny
M. Artuso
M. Goldberg
D. He
N. Horwitz
R. Kennett
R. Mountain
G. C. Moneti
F. Muheim
Y. Muheim
S. Playfer
Y. Rozen
S. Stone
M. Thulasidas
G. Vasseur
G. Zhu
J. Bartelt
Access: Open access
- Branching ratios for the dominant Cabibbo-suppressed decays of the τ lepton have been measured by CLEO II in e+e- annihilation at the Cornell Electron Storage Ring (s∼10.6 GeV) using kaons with momenta below 0.7 GeV/c. The inclusive branching ratio into one charged kaon is (1.60 ± 0.12 ± 0.19)%. For the exclusive decays, B(τ-→K-ντ)=(0.66±0.07±0.09)%, B(τ-→K-π0ντ)=(0.51±0.10±0.07)%, and, based on three events, B(τ-→K-2π0ντ)<0.3% at the 90% confidence level. These represent significant improvements over previous results. B(τ-→K-π0ντ) is measured for the first time with exclusive π0 reconstruction. © 1994 The American Physical Society.
Measurement of charmless semileptonic decays of B mesons
Date: 1993-01-01
Creator: J. Bartelt
S. E. Csorna
Z. Egyed
V. Jain
D. S., Akerib
B. Barish
M. Chadha
S. Chan
D. F. Cowen
G. Eigen
J. S. Miller
C. O'Grady
J. Urheim
A. J. Weinstein
D. Acosta
M. Athanas
G. Masek
H. Paar
M. Sivertz
A. Bean
J. Gronberg
R. Kutschke
S. Menary
R. J. Morrison
S. Nakanishi
H. N. Nelson
T. K. Nelson
J. D. Richman
A. Ryd
H. Tajima
D. Schmidt
Access: Open access
- Using the CLEO II detector and a sample of 955 000 Υ(4S) decays we have confirmed charmless semileptonic decays of B mesons. In the momentum interval 2.3-2.6 GeV/c we observe an excess of 107±15±11 leptons, which we attribute to b→ulν. This result yields a model-dependent range of values for Vub/Vcb that is lower than has been obtained in previous studies. For the inclusive spectator model of Altarelli et al. we find Vub/Vcb=0.076±0.008. Models that describe b→ulν with a limited set of exclusive final states give Vub/Vcb=0.06-0.10. © 1993 The American Physical Society.
Search for τ-→γμ-: A test of lepton number conservation
Date: 1993-01-01
Creator: A. Bean
J. Gronberg
R. Kutschke
S. Menary
R. J., Morrison
H. Nelson
J. Richman
H. Tajima
D. Schmidt
D. Sperka
M. Witherell
M. Procario
S. Yang
M. Daoudi
W. T. Ford
D. R. Johnson
K. Lingel
M. Lohner
P. Rankin
J. G. Smith
J. P. Alexander
C. Bebek
K. Berkelman
D. Besson
T. E. Browder
D. G. Cassel
D. M. Coffman
P. S. Drell
R. Ehrlich
R. S. Galik
M. Garcia-Sciveres
Access: Open access
- A search for the lepton mumber violating decay of the τ lepton to the γμ final state has been performed with the CLEO II detector at the Cornell e+e- storage ring CESR. In a data sample that corresponds to an integrated luminosity of 1.55 fb-1, we observe no candidates in the signal region. We thus determine an upper limit of B(τ-→γμ-)<4. 2×10-6 at 90% confidence level. © 1993 The American Physical Society.
Circadian signaling in Homarus americanus: Region-specific de novo assembled transcriptomes show that both the brain and eyestalk ganglia possess the molecular components of a putative clock system
Date: 2018-07-01
Creator: Andrew E. Christie
Andy Yu
Micah G. Pascual
Vittoria Roncalli
Matthew C., Cieslak
Amanda N. Warner
Tess J. Lameyer
Meredith E. Stanhope
Patsy S. Dickinson
J. Joe Hull
Access: Open access
- Essentially all organisms exhibit recurring patterns of physiology/behavior that oscillate with a period of ~24-h and are synchronized to the solar day. Crustaceans are no exception, with robust circadian rhythms having been documented in many members of this arthropod subphylum. However, little is known about the molecular underpinnings of their circadian rhythmicity. Moreover, the location of the crustacean central clock has not been firmly established, although both the brain and eyestalk ganglia have been hypothesized as loci. The American lobster, Homarus americanus, is known to exhibit multiple circadian rhythms, and immunodetection data suggest that its central clock is located within the eyestalk ganglia rather than in the brain. Here, brain- and eyestalk ganglia-specific transcriptomes were generated and used to assess the presence/absence of transcripts encoding the commonly recognized protein components of arthropod circadian signaling systems in these two regions of the lobster central nervous system. Transcripts encoding putative homologs of the core clock proteins clock, cryptochrome 2, cycle, period and timeless were found in both the brain and eyestalk ganglia assemblies, as were transcripts encoding similar complements of putative clock-associated, clock input pathway and clock output pathway proteins. The presence and identity of transcripts encoding core clock proteins in both regions were confirmed using PCR. These findings suggest that both the brain and eyestalk ganglia possess all of the molecular components needed for the establishment of a circadian signaling system. Whether the brain and eyestalk clocks are independent of one another or represent a single timekeeping system remains to be determined. Interestingly, while most of the proteins deduced from the identified transcripts are shared by both the brain and eyestalk ganglia, assembly-specific isoforms were also identified, e.g., several period variants, suggesting the possibility of region-specific variation in clock function, especially if the brain and eyestalk clocks represent independent oscillators.
Inclusive and exclusive decays of B mesons to final states including charm and charmonium mesons
Date: 1992-01-01
Creator: D. Bortoletto
D. N. Brown
J. Dominick
R. L. McIlwain
D. H., Miller
M. Modesitt
E. I. Shibata
S. Schaffner
I. P.J. Shipsey
M. Battle
H. Kroha
K. Sparks
E. H. Thorndike
C. H. Wang
M. Goldberg
T. Haupt
N. Horwitz
V. Jain
G. C. Moneti
Y. Rozen
P. Rubin
T. Skwarnicki
V. Sharma
S. Stone
M. Thusalidas
W. M. Yao
G. Zhu
A. V. Barnes
J. Bartelt
S. E. Csorna
T. Letson
Access: Open access
- We have studied hadronic decays of B mesons. We report measurements of exclusive branching ratios of several charm decay modes of B mesons to final states with a D or D* and one to three charged pions or a charged and to final states with a or , a kaon, and up to two charged pions. We have also measured inclusive branching ratios for B decays to D and D* and the spectra of these particles in B decays. The total charm content in B decay is found to be (10112)%. The branching ratios and spectra are compared to form-factor models. We extract the parameters a1 and a2 of the model of Bauer, Stech, and Wirbel and the DS decay constant. The masses of the B0 and B- mesons are measured. The mass difference between B0 and B- is found to be -0.40.60.5 MeV/c2. © 1992 The American Physical Society.
Seeking shear waves in liquids with picosecond ultrasonics
Date: 2007-12-01
Creator: M. E. Msall
O. B. Wright
O. Matsuda
Access: Open access
- Picosecond shear acoustic pulses can be generated in solids using ultrashort optical pulses. Here we use this technique to seek high frequency shear waves in water, ethylene glycol and glycerol while simultaneously measuring high frequency longitudinal wave velocity and attenuation. We use a silica thin film on (114) GaAs to generate shear and longitudinal acoustic pulses at frequencies up to ∼50 GHz by ultrashort pulsed optical excitation. The acoustic pulses are transmitted into adjacent liquids, and are detected through variations in the optical reflectivity. Although we could not detect shear waves in these liquids, we did detect gigahertz longitudinal elastic stiffening. © 2007 IOP Publishing Ltd.
AMGSEFLamide, a member of a broadly conserved peptide family, modulates multiple neural networks in Homarus americanus
Date: 2019-01-01
Creator: Patsy S. Dickinson
Evyn S. Dickinson
Emily R. Oleisky
Cindy D. Rivera
Meredith E., Stanhope
Elizabeth A. Stemmler
J. Joe Hull
Andrew E. Christie
Access: Open access
- Recent genomic/transcriptomic studies have identified a novel peptide family whose members share the carboxyl terminal sequence –GSEFLamide. However, the presence/identity of the predicted isoforms of this peptide group have yet to be confirmed biochemically, and no physiological function has yet been ascribed to any member of this peptide family. To determine the extent to which GSEFLamides are conserved within the Arthropoda, we searched publicly accessible databases for genomic/transcriptomic evidence of their presence. GSEFLamides appear to be highly conserved within the Arthropoda, with the possible exception of the Insecta, in which sequence evidence was limited to the more basal orders. One crustacean in which GSEFLamides have been predicted using transcriptomics is the lobster, Homarus americanus. Expression of the previously published transcriptome-derived sequences was confirmed by reverse transcription (RT)-PCR of brain and eyestalk ganglia cDNAs; mass spectral analyses confirmed the presence of all six of the predicted GSEFLamide isoforms – IGSEFLamide, MGSEFLamide, AMGSEFLamide, VMGSEFLamide, ALGSEFLamide and AVGSEFLamide – in H. americanus brain extracts. AMGSEFLamide, of which there are multiple copies in the cloned transcripts, was the most abundant isoform detected in the brain. Because the GSEFLamides are present in the lobster nervous system, we hypothesized that they might function as neuromodulators, as is common for neuropeptides. We thus asked whether AMGSEFLamide modulates the rhythmic outputs of the cardiac ganglion and the stomatogastric ganglion. Physiological recordings showed that AMGSEFLamide potently modulates the motor patterns produced by both ganglia, suggesting that the GSEFLamides may serve as important and conserved modulators of rhythmic motor activity in arthropods.
TAKs, thylakoid membrane protein kinases associated with energy transduction
Date: 1999-04-02
Creator: Shaun Snyders
Bruce D. Kohorn
Access: Open access
- The phosphorylation of proteins within the eukaryotic photosynthetic membrane is thought to regulate a number of photosynthetic processes in land plants and algae. Both light quality and intensity influence protein kinase activity via the levels of reductants produced by the thylakoid electron transport chain. We have isolated a family of proteins called TAKs, Arabidopsis thylakoid membrane threonine kinases that phosphorylate the light harvesting complex proteins. TAK activity is enhanced by reductant and is associated with the photosynthetic reaction center II and the cytochrome b6f complex. TAKs are encoded by a gene family that has striking similarity to transforming growth factor β receptors of metazoans. Thus thylakoid protein phosphorylation may be regulated by a cascade of reductant-controlled membrane-bound protein kinases.