Detection of quantitative trait loci for locomotion and osteochondrosis-related traits in Large White x Meishan pigs.

Data from the F2 generation of a Large White (LW) 5 Meishan (MS) crossbred population were analysed to detect quantitative trait loci (QTL) for leg and gait scores, osteochondrosis and physis scores. Legs, feet and gait score were assessed in 308 F2 animals at 85 (± 5) kg and osteochondrosis and physis scores were recorded for the right foreleg after slaughter. A genome scan was performed using 111 genetic markers chosen to span the genome that were genotyped on the F2 animals and their F1 parents and purebred grandparents. A QTL on chromosome 1 affecting gait score was significant at the genome-wide significance level. Additional QTL significant at the chromosome-wide 5% threshold level (approx. equivalent to the genome-wide suggestive level) were detected on chromosome 1 for front feet and back legs scores, on chromosome 13 for front legs and front feet scores, on chromosome 14 for front legs, front feet and back legs scores and on chromosome 15 for back feet score. None of the QTL for osteochondrosis score exceeded the chromosome-wide suggestive level, but one chromosome-wide QTL for physis score was found on chromosome 7. On chromosome 1, gait and front feet scores mapped to the middle of the chromosome and showed additive effects in favour of the LW alleles and no dominance effects. The QTL for back legs score mapped to the distal end of the chromosome and showed a dominant effect and no additive effect. On chromosomes 14 and 15, the LW allele was again superior to the MS allele. On chromosome 13, there were both additive and dominance effects in favour of the MS allele. The MS alleles on chromosome 13 may have potential for introgression into a commercial LW population. The other putative QTLs identified may have value in marker-assisted selection in LW or MS-synthetic populations

Luminosity Evolution of Early-type Galaxies to z=0.83: Constraints on Formation Epoch and Omega

We present deep spectroscopy with the Keck telescope of eight galaxies in the luminous X-ray cluster MS1054-03 at z=0.83. The data are combined with imaging observations from the Hubble Space Telescope (HST). The spectroscopic data are used to measure the internal kinematics of the galaxies, and the HST data to measure their structural parameters. Six galaxies have early-type spectra, and two have "E+A" spectra. The galaxies with early-type spectra define a tight Fundamental Plane (FP) relation. The evolution of the mass-to-light ratio is derived from the FP. The M/L ratio evolves as \Delta log M/L_B \propto -0.40 z (Omega_m=0.3, Omega_Lambda=0). The observed evolution of the M/L ratio provides a combined constraint on the formation redshift of the stars, the IMF, and cosmological parameters. For a Salpeter IMF (x=2.35) we find that z_form>2.8 and Omega_m<0.86 with 95% confidence. The constraint on the formation redshift is weaker if Omega_Lambda>0: z_form>1.7 if Omega_m=0.3 and Omega_Lambda=0.7. At present the limiting factor in constraining z_form and Omega from the observed luminosity evolution of early-type galaxies is the poor understanding of the IMF. We find that if Omega_m=1 the IMF must be significantly steeper than the Salpeter IMF (x>2.6).Comment: To be published in ApJ Letters, Volume 504, September 1, 1998. 5 pages, 4 figure

The Detection of a Red Sequence of Massive Field Galaxies at z~2.3 and its Evolution to z~0

The existence of massive galaxies with strongly suppressed star formation at z~2.3, identified in a previous paper, suggests that a red sequence may already be in place beyond z=2. In order to test this hypothesis, we study the rest-frame U-B color distribution of massive galaxies at 2<z<3. The sample is drawn from our near-infrared spectroscopic survey for massive galaxies. The color distribution shows a statistically significant (>3 sigma) red sequence, which hosts ~60% of the stellar mass at the high-mass end. The red-sequence galaxies have little or no ongoing star formation, as inferred from both emission-line diagnostics and stellar continuum shapes. Their strong Balmer breaks and their location in the rest-frame U-B, B-V plane indicate that they are in a post-starburst phase, with typical ages of ~0.5-1.0 Gyr. In order to study the evolution of the red sequence, we compare our sample with spectroscopic massive galaxy samples at 0.02<z<0.045 and 0.6<z<1.0. The rest-frame U-B color reddens by ~0.25 mag from z~2.3 to the present at a given mass. Over the same redshift interval, the number and stellar mass density on the high-mass end (>10^11 Msol) of the red sequence grow by factors of ~8 and ~6, respectively. We explore simple models to explain the observed evolution. Passive evolution models predict too strong d(U-B), and produce z~0 galaxies that are too red. More complicated models that include aging, galaxy transformations, and red mergers can explain both the number density and color evolution of the massive end of the red sequence between z~2.3 and the present.Comment: Accepted for publication in the Astrophysical Journa

The Evolution of Early-Type Galaxies in Distant Clusters III.: M/L_V Ratios in the z=0.33 Cluster CL1358+62

Keck spectroscopy and Hubble Space Telescope WFPC2 imaging over a 1.5x1.5 Mpc field of CL1358+62 at z=0.33 are used to study the Fundamental Plane of galaxies based on a new, large sample of 53 galaxies. First, we have constructed the Fundamental Plane for the 30 E and S0 galaxies and find that it has the following shape: r_e = sigma**(1.31+-0.13) * _e**(-0.86+-0.10), similar to that found locally. The 1-sigma intrinsic scatter about this plane is 14% in M/L(V), comparable to that observed in Coma. We conclude that these E and S0 galaxies are structurally mature and homogeneous, like those observed in nearby clusters. The M/L(V) ratios of these early-type galaxies are offset from the Coma Fundamental Plane by delta log M/L(V) = -0.13+- 0.03 (q0=0.1), indicative of mild luminosity evolution. This evolution suggests a formation epoch for the stars of z > 1. We have also analyzed the M/L(V) ratios of galaxies of type S0/a and later. These early-type spirals follow a different plane from the E and S0 galaxies, with a scatter that is twice as large as the scatter for the E/S0s. The difference in the tilt between the plane of the spirals and the plane of the E/S0s is shown to be due to a systematic correlation of velocity dispersion with residual from the plane of the early-type galaxies. These residuals also correlate with the residuals from the Color-Magnitude relation. Thus for spirals in clusters, we see a systematic variation in the luminosity-weighted mean properties of the stellar populations with central velocity dispersion. If this is a relative age trend, then luminosity-weighted age is positively correlated with dispersion. [abridged version]Comment: 18 pages, 8 figures; revised version, accepted by ApJ on 13 August 199

The Evolution of Early-Type Galaxies in Distant Clusters II: Internal Kinematics of 55 Galaxies in the z=0.33 Cluster CL1358+62

We define a large sample of galaxies for use in a study of the fundamental plane in the intermediate redshift cluster CL1358+62 at $z=0.33$. We have analyzed high resolution spectra for 55 members of the cluster. The data were acquired with the Low Resolution Imaging Spectrograph on the Keck I 10m telescope. A new algorithm for measuring velocity dispersions is presented and used to measure the internal kinematics of the galaxies. This algorithm has been tested against the Fourier Fitting method so the data presented here can be compared with those measured previously in nearby galaxies. We have measured central velocity dispersions suitable for use in a fundamental plane analysis. The data have high $S/N$ and the resulting random errors on the dispersions are very low, typically $<5$. Uncertainties due to mismatch of the stellar templates has been minimized through several tests and the total systematic error is of order \about 5%. Good seeing enabled us to measure velocity dispersion profiles and rotation curves for most of the sample and although a large fraction of the galaxies display a high level of rotation, the gradients of the total second moment of the kinematics are all very regular and similar to those in nearby galaxies. We conclude that the data therefore can be reliably corrected for aperture size in a manner consistent with nearby galaxy samples.Comment: 30 pages, 13 figures; for publication in the ApJ (accepted on 23 August 1999

The Color-Magnitude Relation in CL 1358+62 at z=0.33: Evidence for Significant Evolution in the S0 Population

We use a large mosaic of HST WFPC2 images to measure the colors and morphologies of 194 spectroscopically confirmed members of the rich galaxy cluster CL1358+62 at z=0.33. We study the color-magnitude (CM) relation as a function of radius in the cluster. The intrinsic scatter in the restframe B-V CM relation of the elliptical galaxies is very small: ~0.022 magnitudes. The CM relation of the ellipticals does not depend significantly on the distance from the cluster center. In contrast, the CM relation for the S0 galaxies does depend on radius: the S0s in the core follow a CM relation similar to the ellipticals, but at large radii (R>0.7Mpc) the S0s are systematically bluer and the scatter in the CM relation approximately doubles to ~0.043 magnitudes. The blueing of the S0s is significant at the 95% confidence level. These results imply that the S0 galaxies in the outer parts of the cluster have formed stars more recently than the S0s in the inner parts. A likely explanation is that clusters at z=0.33 continue to accrete galaxies and groups from the field and that infall extinguishes star formation. The apparent homogeneity of the elliptical galaxy population implies that star formation in recently accreted ellipticals was terminated well before accretion occurred. We have constructed models to explore the constraints that these observations place on the star formation history of cluster galaxies. We conclude that the population of S0s in clusters is likely to evolve as star forming galaxies are converted into passively evolving galaxies. Assuming a constant accretion rate after z=0.33, we estimate ~15% of the present day early-type galaxy population in rich clusters was accreted between z=0.33 and z=0. The ellipticals (and the brightest S0s) are probably a more stable population, at least since z=0.6.Comment: Accepted for publication in the ApJ. 20 pages, 12 figures. Full version and plates available at http://www.astro.rug.nl/~dokkum/papers.htm

Successful use of axonal transport for drug delivery by synthetic molecular vehicles

We report the use of axonal transport to achieve intraneural drug delivery. We constructed a novel tripartite complex of an axonal transport facilitator conjugated to a linker molecule bearing up to a hundred reversibly attached drug molecules. The complex efficiently enters nerve terminals after intramuscular or intradermal administration and travels within axonal processes to neuron cell bodies. The tripartite agent provided 100-fold amplification of saturable neural uptake events, delivering multiple drug molecules per complex. _In vivo_, analgesic drug delivery to systemic and to non-targeted neural tissues was greatly reduced compared to existing routes of administration, thus exemplifying the possibility of specific nerve root targeting and effectively increasing the potency of the candidate drug gabapentin 300-fold relative to oral administration

The Hubble Space Telescope Extragalactic Distance Scale Key Project. X. The Cepheid Distance to NGC 7331

The distance to NGC 7331 has been derived from Cepheid variables observed with HST/WFPC2, as part of the Extragalactic Distance Scale Key Project. Multi-epoch exposures in F555W (V) and F814W (I), with photometry derived independently from DoPHOT and DAOPHOT/ALLFRAME programs, were used to detect a total of 13 reliable Cepheids, with periods between 11 and 42 days. The relative distance moduli between NGC 7331 and the LMC, imply an extinction to NGC 7331 of A_V = 0.47+-0.15 mag, and an extinction-corrected distance modulus to NGC 7331 of 30.89+-0.14(random) mag, equivalent to a distance of 15.1 Mpc. There are additional systematic uncertainties in the distance modulus of +-0.12 mag due to the calibration of the Cepheid Period-Luminosity relation, and a systematic offset of +0.05+-0.04 mag if we applied the metallicity correction inferred from the M101 results of Kennicutt et al 1998.Comment: To be published in The Astrophysical Journal, 1998 July 1, v501 note: Figs 1 and 2 (JPEG files) and Fig 7 (multipage .eps file) need to be viewed/printed separatel