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- Klionsky, Daniel J., et al.
(author)
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Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
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In: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
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Research review (peer-reviewed)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
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3. |
- Huang, X., et al.
(author)
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HUBBLE SPACE TELESCOPE DISCOVERY OF A z=3.9 MULTIPLY IMAGED GALAXY BEHIND THE COMPLEX CLUSTER LENS WARPS J1415.1+36 AT z=1.026
- 2009
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In: ASTROPHYS J LETT. ; 707:1, s. l12-L16
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Journal article (peer-reviewed)abstract
- We report the discovery of a multiply lensed Ly alpha emitter at z = 3.90 behind the massive cluster WARPS J1415.1+3612 at z = 1.026. Images taken by the Hubble Space Telescope using the Advanced Camera for Surveys reveal a complex lensing system that produces a prominent, highly magnified arc and a triplet of smaller arcs grouped tightly around a spectroscopically confirmed cluster member. Spectroscopic observations using the Faint Object Camera and Spectrograph on Subaru confirm strong Lya emission in the source galaxy and provide the redshifts for more than 21 cluster members with a velocity dispersion of 807 +/- 185 km s(-1). Assuming a singular isothermal sphere profile, the mass within the Einstein ring (7.13 +/- 0.'' 38) corresponds to a central velocity dispersion of 686(-19)(+15) km s(-1) for the cluster, consistent with the value estimated from cluster member redshifts. Our mass profile estimate from combining strong lensing and dynamical analyses is in good agreement with both X-ray and weak lensing results.
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4. |
- Dawson, K. S., et al.
(author)
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An Intensive Hubble Space Telescope Survey for z>1 Type Ia Supernovae by Targeting Galaxy Clusters
- 2009
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In: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 138, s. 1271-1283
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Journal article (peer-reviewed)abstract
- We present a new survey strategy to discover and study high-redshift Type Ia supernovae (SNe Ia) using the Hubble Space Telescope (HST). By targeting massive galaxy clusters at 0.9 < z < 1.5, we obtain a twofold improvement in the efficiency of finding SNe compared to an HST field survey and a factor of 3 improvement in the total yield of SN detections in relatively dust-free red-sequence galaxies. In total, sixteen SNe were discovered at z>0.95, nine of which were in galaxy clusters. This strategy provides an SN sample that can be used to decouple the effects of host-galaxy extinction and intrinsic color in high-redshift SNe, thereby reducing one of the largest systematic uncertainties in SN cosmology. Based on observations made with the NASA/ESA Hubble Space Telescope and obtained from the data archive at the Space Telescope Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under the NASA contract NAS 5-26555. The observations are associated with program 10496.
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6. |
- Barbary, K., et al.
(author)
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Discovery of an Unusual Optical Transient with the Hubble Space Telescope
- 2009
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 690, s. 1358-1362
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Journal article (peer-reviewed)abstract
- We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a peak magnitude of ~ 21.0 in both i 775 and z 850, and then declined over a similar timescale. There is no host galaxy or progenitor star detected at the location of the transient to a 3σ upper limit of i 775 >= 26.4 and z 850 >= 26.1, giving a corresponding lower limit on the flux increase of a factor of ~ 120. Multiple spectra show five broad absorption bands between 4100 Å and 6500 Å, and a mostly featureless continuum longward of 6500 Å. The shape of the light curve is inconsistent with microlensing. The transient's spectrum, in addition to being inconsistent with all known supernova types, does not match any spectrum in the Sloan Digital Sky Survey database. We suggest that the transient may be one of a new class. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under the NASA contract NAS 5-26555. The observations are associated with program GO-10496. Based in part on observations obtained at the European Southern Observatory under ESO program 077.A-0110. Based in part on observations collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA.
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7. |
- Nobili, Serena, et al.
(author)
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Constraining Dust and Color Variations of High-z SNe Using NICMOS on the Hubble Space Telescope
- 2009
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 700, s. 1415-1427
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Journal article (peer-reviewed)abstract
- We present data from the Supernova Cosmology Project for five high redshift Type Ia supernovae (SNe Ia) that were obtained using the NICMOS infrared camera on the Hubble Space Telescope. We add two SNe from this sample to a rest-frame I-band Hubble diagram, doubling the number of high redshift supernovae on this diagram. This I-band Hubble diagram is consistent with a flat universe (ΩM, ΩΛ) = (0.29, 0.71). A homogeneous distribution of large grain dust in the intergalactic medium (replenishing dust) is incompatible with the data and is excluded at the 5σ confidence level, if the SN host galaxy reddening is corrected assuming RV = 1.75. We use both optical and infrared observations to compare photometric properties of distant SNe Ia with those of nearby objects. We find generally good agreement with the expected color evolution for all SNe except the highest redshift SN in our sample (SN 1997ek at z = 0.863) which shows a peculiar color behavior. We also present spectra obtained from ground-based telescopes for type identification and determination of redshift. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the association of Universities for Research in Astronomy, Inc. under the NASA contract NAS 5-26555. The observations are associated with program GO-07850.
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8. |
- Rubin, D., et al.
(author)
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Looking Beyond Lambda with the Union Supernova Compilation
- 2009
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 695, s. 391-403
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Journal article (peer-reviewed)abstract
- The recent robust and homogeneous analysis of the world's supernova distance-redshift data, together with cosmic microwave background and baryon acoustic oscillation data—provides a powerful tool for constraining cosmological models. Here we examine particular classes of scalar field, modified gravity, and phenomenological models to assess whether they are consistent with observations even when their behavior deviates from the cosmological constant Λ. Some models have tension with the data, while others survive only by approaching the cosmological constant, and a couple are statistically favored over Λ cold dark matter. Dark energy described by two equation-of-state parameters has considerable phase space to avoid Λ and next-generation data will be required to constrain such physics, with the level of complementarity between probes varying with cosmology.
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