Rodney V. Jones

Multiple conductance states of the purified calcium release channel complex from skeletal sarcoplasmic reticulum.

The CHAPS-solubilized and purified 30S ryanodine receptor protein complex from skeletal sarcoplasmic reticulum (SR) was incorporated into planar lipid bilayers. The resulting electrical activity displayed similar responses to agents such as Ca2+, ATP, ryanodine, or caffeine as the native Ca2+ release channel, confirming the identification of the 30S complex as the Ca2+ release channel. The purified channel was permeable to monovalent ions such as Na+, with the permeability ratio PCa/PNa approximately 5, and was highly selective for cations over anions. The purified channel also showed at least four distinct conductance levels for both Na+ and Ca2+ conducting ions, with the major subconducting level in NaCl buffers possessing half the conductance value of the main conductance state. These levels may be produced by intrinsic subconductances present within the channel oligomer. Several of these conductances may be cooperatively coupled to produce the characteristic 100 +/- 10 pS unitary Ca2+ conductance of the native channel.

The Baade-Wesselink method and the distances to RR Lyrae stars. VIII: Comparisons with other techniques and implications for globular cluster distances and ages

All techniques that derive M V or M bol as a function of [Fe/H] for RR Lyrae variables are summarized. Baade-Wesselink analyses indicate ∞ 0.16[Fe/H] and ∞ 0.21[Fe/H]. Recent results from main-sequence fitting are revised to account for metallicity-dependent errors in B-V from model isochrones, finding ∞ 0.12[Fe/H]. The equilibrium temperature scale for RR Lyrae stars, a crucial quantity for comparison of theory with observations and the period-shift analyses of Sandage, is redefined

The Baade-Wesselink method and the distances to RR Lyrae stars. VII - The field stars SW Andromedae and DX Delphini and a comparison of recent Baade-Wesselink analyses

New BVK photometry and radial velocities from high-resolution spectroscopy for the metal-rich ([Fe/H]=-0.2) Ab-type RR Lyrae star SW Andromedae are presented. These data are utilized, along with previously published optical data, to derive the distance and absolute magnitudes of this star using the infrared surface brightness version of the Baade-Wesselink method. The metal-rich ([Fe/H]=-0.2) RR Lyrae variable DX Delphini is also analyzed using the same technique and previously published data

TEMPLATE K LIGHT CURVES FOR RR LYRAE STARS

We discuss a technique to compute using templates developed by fitting a Fourier series to existing high-quality K light curves of field RR Lyraes. We find that a series of order 2 is sufficient to model the light curves of first-overtone RRc variables, but 4 different 6th-order templates are needed for the fundamental RRab stars due to changes in the light curves that appear to correlate with the B amplitude. Applying the appropriate template to single-phase observations yield estimated values whose deviation from the true is randomly distributed over phase, and is of the same order of magnitude as the observational uncertainty, as long as the ephemeris phase is accurate. The addition of a second point, separated by at least 0.2 in phase from the first, allows the use of template-shifting to remove deviations that may arise from uncertainties in the ephemeris phase, and template and scaling factor selection, with final systematic errors reduced to less than 0.03 mag. We find that the use of templates yield superior results to those derived using other techniques, which can produce values that show systematic deviations over phase.

BV PHOTOMETRY OF RR LYRAE VARIABLES IN THE GLOBULAR CLUSTER M92

We present BV CCD photometry for 7 RR Lyrae variables in the globular cluster M92 (NGC 6341). New ephemerides are computed, and V, B, and B-V light curves are given. A color-magnitude diagram based on 2 V and 2 B short exposures is given, reaching from above the horizontal branch to below the main sequence turn-off. A comparison with results from other workers shows we agree with the photometry of Cathey (1974) and Stetson and Harris (1988). We study also the timing of the secondary bumps in the light curves of 5 of the RRab variables, finding it to be consistent with prediction from the echo model. Expansion radii derived from radial velocities are not consistent with the photospheric infall model of the secondary bump.

Activation of the skeletal muscle Ca2+ release channel by the triazine dyes Cibacron Blue F3A-G and reactive Red 120☆

Vesicle-45Ca2+ ion flux and planar lipid bilayer single-channel measurements have shown that the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (SR) is activated by micromolar concentrations of Cibacron Blue F3A-G (Reactive Blue 2) and Reactive Red 120. Cibacron Blue increased the 45Ca2+ efflux rate from heavy SR vesicles by apparently interacting with both the adenine nucleotide and caffeine activating sites of the channel. Dye-induced 45Ca2+ release was inhibited by Mg2+ and ruthenium red. In single channel recordings with the purified channel protein complex, Cibacron Blue increased the open time of the Ca2+ release channel without an apparent change in the conductance of the main and subconductance states of the channel.

Chemical abundances of the extreme-velocity RR Lyrae variable VY Serpentis

VY Serpentis is one of the brighter field RR Lyrae variable stars of type ab. A high-dispersion spectrogram of VY Ser has been obtained and analyzed. The present investigation has the objective to estimate the metallicity and gravity of the star for use in an analysis. Estimates of both metallicity and gravity may be obtained by photometric means, but corroborating data are always desirable. The results will be used to convert photometric colors to temperatures and bolometric corrections. Attention is given to observations, reddening, model atmosphere calculations, line data, microturbulence and gravity. Photometric gravities and derived elemental abundances are presented in tables. It is found that VY Ser is a metal-poor star. It is a very cool variable, near the red edge of the instability strip, which may explain its large microturbulent velocity of 4.2 km/sec.

Comparison of CHAPS-induced current fluctuations with sarcoplasmic reticulum Ca2+ release channel activity

The process of purifying and reconstituting transport membrane proteins generally involves the use of detergents, which often cannot be completely separated from the proteins. The effects of the zwitterionic detergent CHAPS on planar lipid bilayers have been measured, and it is demonstrated that CHAPS can induce microscopic electrical activity in the bilayers. Typical CHAPS-induced activity consists of large current bursts, often separated by intervals of quiescent activity, with no definable conductance levels. The size of the current bursts is generally increased by higher CHAPS concentration or by millimolar ATP and usually reduced by millimolar Mg2+ and micromolar ruthenium red. The response of the CHAPS-induced currents to these agents is compared to that of the ligand-gated Ca2+ release channel of muscle sarcoplasmic reticulum.

The Distance and Age of the Globular Cluster M5

Using optical and infrared photometry and echelle spectroscopy of variable V8 in the globular cluster M5, we derive a cluster distance of 6.8 kpc using the Baade-Wesselink method. This agrees with the prediction obtained for the clusters metallicity using a sample of 19 field stars studied by us and by Liu and Janes (this volume). It also agrees well with estimates for Mv obtained from statistical parallaxes of field stars. It agrees as well with the main sequence fitting procedure where we have used only HD 103095, the field halo dwarf with the most accurate trigonometric parallax (3% error), and which has a metallicity almost identical to that of M5. The star is also cool, hence unevolved, and is not a binary. Using the luminosity of the clusters main sequence, both Yale and Victoria isochrones yield a cluster age of 18 ± 3 Gyrs. at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100011611 Downloaded from https://www.cambridge.org/core. IP address: 54.191.40.80, on 21 Aug 2017 at 16:37:10, subject to the Cambridge Core terms of use, available

The Distances to RR Lyrae Variables

Of all the different methods employed to estimate the mean absolute magnitude of RR Lyrae variables, only an analysis of the Baade-Wesselink type can determine this quantity directly. The distance to a globular cluster can therefore be measured by determining RR for that cluster instead of being forced to assume that RR is tne same as that of the nearby field variables. This is important in that the field stars may have a different luminosity than cluster variables. In addition, since RR should depend on the composition (especially helium) and history of mass loss of these stars, this quantity may vary from cluster to cluster.