Caltech Authors
(24.207 recursos)
Repository of works by Caltech published authors.
Mostrando recursos 1 - 20 de 5.965
1.
Molecular Signatures in the Near-Infrared Dayside Spectrum of HD 189733b - Swain, M. R.; Vasisht, G.; Tinetti, G.; Bouwman, J.; Chen, Pin; Yung, Y.; Deming, D.; Deroo, P.
We have measured the dayside spectrum of HD 189733b between 1.5 and 2.5 ?m using the NICMOS instrument on the Hubble Space Telescope. The emergent spectrum contains significant modulation, which we attribute to the presence of molecular bands seen in absorption. We find that water (H2O), carbon monoxide (CO), and carbon dioxide (CO2) are needed to explain the observations, and we are able to estimate the mixing ratios for these molecules. We also find temperature decreases with altitude in the ~0.01 < P< ~1 bar region of the dayside near-infrared photosphere and set an upper limit to the dayside abundance...
2.
Spatially Resolved Stellar Populations of Eight GOODS-South Active Galactic Nuclei at z ~ 1 - Ammons, S. Mark; Melbourne, Jason; Max, Clare E.; Koo, Davd C.; Rosaroi, David J. V.
We present a pilot study of the stellar populations of eight active galactic nucleus (AGN) hosts at z ~ 1 and compare with (1) lower redshift samples and (2) a sample of nonactive galaxies of similar redshift. We utilize K' images in the Great Observatories Origins Deep Survey South field obtained with the laser guide star adaptive optics system at Keck Observatory. We combine these K' data with B, V, i, and z imaging from the Advanced Camera for Surveys on Hubble Space Telescope to give multicolor photometry at a matched spatial resolution better than 100 mas in all bands....
3.
Automated data integration for developmental biological research - Zhong, Weiwei; Sternberg, Paul W.
In an era exploding with genome-scale data, a major challenge for developmental biologists is how to extract significant clues from these publicly available data to benefit our studies of individual genes, and how to use them to improve our understanding of development at a systems level. Several studies have successfully demonstrated new approaches to classic developmental questions by computationally integrating various genome-wide data sets. Such computational approaches have shown great potential for facilitating research: instead of testing 20,000 genes, researchers might test 200 to the same effect. We discuss the nature and state of this art as it applies to...
4.
Clonal variation in cell surface display of an H-2 protein lacking a cytoplasmic tail - Zuniga, Martha C.; Hood, Leroy E.
Truncated variants of the gene encoding H-2Ld, an integral membrane protein encoded by the major histocompatibility complex, were constructed by in vitro mutagenesis to elucidate the function of charged amino acids found on the cytoplasmic side of the transmembrane (TM) region. Analysis of cloned L cells transfected with these genes shows that the seven amino acids following the TM segment, four of which are basic, enhance the cell surface expression of H-2Ld protein but are not required for it. However, some clones do not express a tailless H-2Ld protein on the cell surface but express it intracellularly where it has...
5.
A large-scale analysis of mRNAs expressed by primary mesenchyme cells of the sea urchin embryo - Zhu, Xiaodong; Maharias, Gregory; llies, Michele; Cameron, R. Andrew; Davidson, Eric H.; Ettensohn, Charles A.
The primary mesenchyme cells (PMCs) of the sea urchin embryo have been an important model system for the analysis of cell behavior during gastrulation. To gain an improved understanding of the molecular basis of PMC behavior, a set of 8293 expressed sequenced tags (ESTs) was derived from an enriched population of mid-gastrula stage PMCs. These ESTs represented approximately 1200 distinct proteins, or about 15% of the mRNAs expressed by the gastrula stage embryo. 655 proteins were similar (P<10-7 by BLAST comparisons) to other proteins in GenBank, for which some information is available concerning expression and/or function. Another 116 were similar...
6.
XASH-3, a novel Xenopus achaete-scute homolog, provides an early marker of planar neural induction and position along the mediolateral axis of the neural plate - Zimmerman, Kathryn; Shih, John; Bars, Julie; Collazo, Andres; Anderson, David J.
We have isolated a novel Xenopus homolog of the Drosophila achaete-scute genes, called XASH-3. XASH-3 expression is neural specific and is detected as early as stage 11 1/2, making it one of the earliest markers of neural induction so far described. Moreover, XASH-3 expression within the neural plate is regionally restricted. Transverse bands of XASH-3 mRNA mark discrete positions along the anteroposterior axis, while longitudinal bands mark a discrete position along the mediolateral axis. This latter site of XASH-3 expression appears to demarcate the prospective sulcus limitans, a boundary zone that later separates the functionally distinct dorsal (alar) and ventral...
7.
Functional expression of the yeast alpha-factor receptor in Xenopus oocytes - Yu, Lei; Blumer, Kendall J.; Davidson, Norman; Lester, Henry A.; Thorner, Jeremy
The STE2 gene of the yeast Saccharomyces cerevisiae encodes a 431- residue polypeptide that has been shown by chemical cross-linking and genetic studies to be a component of the receptor for the peptide mating pheromone, alpha-factor. To demonstrate directly that the ligand binding site of the alpha-factor receptor is comprised solely of the STE2 gene product, the STE2 protein was expressed in Xenopus oocytes. Oocytes microinjected with synthetic STE2 mRNA displayed specific surface binding for 35S-labeled alpha-factor (up to 40 sites/micron2/ng RNA). Oocytes injected with either STE2 antisense RNA or heterologous receptor mRNA (nicotinic acetylcholine receptor alpha, beta, gamma, and...
8.
A pathway of signals regulating effector and initiator caspases in the developing Drosophila eye - Yu, Sun-Yun; Yoo, Soon Ji; Yang, Lihui; Zapata, Cynthia; Srinivasan, Anu; Hay, Bruce A.; Baker, Nicholas E.
Regulated cell death and survival play important roles in neural development. Extracellular signals are presumed to regulate seven apparent caspases to determine the final structure of the nervous system. In the eye, the EGF receptor, Notch, and intact primary pigment and cone cells have been implicated in survival or death signals. An antibody raised against a peptide from human caspase 3 was used to investigate how extracellular signals controlled spatial patterning of cell death. The antibody crossreacted specifically with dying Drosophila cells and labelled the activated effector caspase Drice. It was found that the initiator caspase Dronc and the proapoptotic...
9.
Wasp-7: A Bright Transiting-Exoplanet System in the Southern Hemisphere - Hellier, Coel; Anderson, D. R.; Gillon, M.; Lister, T. A.; Maxted, P. F. L.; Queloz, D.; Smalley, B.; Triaud, A. H. M. J.; West, R. G.; Wilson, D. M.; Alsubai, K.; Bentley, S. J.; Collier Cameron, A.; Hebb, L.; Horne, K.; Irwin, J.; Kane, S. R.; Mayor, M.; Pepe, F.; Pollacco, D.; Skillen, I.; Udry, S.; Wheatley, P. J.; Christian, D. J.; Enoch, R.; Haswell, C. A.; Joshi, Y. C.; Norton, A. J.; Parley, N.; Ryans, R.; Street, R. A.; Todd, I.
We report that a Jupiter-mass planet, WASP-7b, transits the V = 9.5 star HD 197286 every 4.95 d. This is the brightest discovery from the WASP-South transit survey so far and is currently the brightest transiting-exoplanet system in the southern hemisphere. WASP-7b is among the densest of the known Jupiter-mass planets, suggesting that it has a massive core. The planet mass is 0.96+0.12 0.18 M Jup, the radius is 0.915+0.046 0.040 R Jup, and the density is 1.26+0.25 0.21 ?Jup (1.67+0.33 0.28 g cm^3).
10.
A method for estimating timefrequency characteristics of compact binary mergers to improve searches for inspiral, merger and ring-down phases separately - Hanna, Chad; Megevand, Miguel; Ochsner, Evan; Palenzuela, Carlos
Recent advances in the description of compact binary systems have produced gravitational waveforms that include inspiral, merger and ring-down phases. Comparing results from numerical simulations with those of post-Newtonian, and related, expansions has provided motivation for employing post-Newtonian waveforms in near merger epochs when searching for gravitational waves and has encouraged the development of analytic fits to full numerical waveforms. Until searches employ full waveforms as templates, data analysts can still conduct separate inspiral, merger and ring-down searches. Improved knowledge about the end of the inspiral phase, the beginning of the merger and the ring-down frequencies will increase the efficiency...
11.
SynGAP Regulates Steady-State and Activity-Dependent Phosphorylation of Cofilin - Carlisle, Holly J.; Manzerra, Pasquale; Marcora, Edoardo; Kennedy, Mary B.
SynGAP, a prominent Ras/Rap GTPase-activating protein in the postsynaptic density, regulates the timing of spine formation and trafficking of glutamate receptors in cultured neurons. However, the molecular mechanisms by which it does this are unknown. Here, we show that synGAP is a key regulator of spine morphology in adult mice. Heterozygous deletion of synGAP was sufficient to cause an excess of mushroom spines in adult brains, indicating that synGAP is involved in steady-state regulation of actin in mature spines. Both Ras- and Rac-GTP levels were elevated in forebrains from adult synGAP+/- mice. Rac is a well known regulator of actin...
12.
Distinct roles of transcription factors EGL-46 and DAF-19 in specifying the functionality of a polycystin-expressing sensory neuron necessary for C. elegans male vulva location behavior - Yu, Hui; Prétôt, René F.; Bürglin, Thomas R.; Sternberg, Paul W.
Caenorhabditis elegans polycystins LOV-1 and PKD-2 are expressed in the male-specific HOB neuron, and are necessary for sensation of the hermaphrodite vulva during mating. We demonstrate that male vulva location behavior and expression of lov-1 and pkd-2 in the ciliated sensory neuron HOB require the activities of transcription factor EGL-46 and to some extent also EGL-44. This EGL-46- regulated program is specific to HOB and is distinct from a general ciliogenic pathway functioning in all ciliated neurons. The ciliogenic pathway regulator DAF-19 affects downstream components of the HOB-specific program indirectly and is independent of EGL-46 activity. The sensory function of...
13.
Modular cis-regulatory organization of Endo16, a gut-specific gene of the sea urchin embryo - Yuh, Chiou-Hwa; Davidson, Eric H.
The Endo16 gene of Strongylocentrotus purpuratus is expressed at the blastula stage of embryogenesis throughout the vegetal plate, at the gastrula stage in the whole of the archenteron and in postgastrular stages only in the midgut. We showed earlier that a 2300 bp upstream sequence suffices to faithfully recreate this pattern of expression when fused to a CAT reporter gene. Here we define the functional organization of this cis-regulatory domain, which includes over thirty high specificity binding sites, serviced by at least thirteen different putative transcription factors, in addition to >20 sites for a factor commonly found in the regulatory...
14.
Quantitative functional interrelations within the cis-regulatory system of the S. purpuratus Endo16 gene - Yuh, Chiou-Hwa; Moore, James G.; Davidson, Eric H.
Embryonic expression of the Endo16 gene of Strongylocentrotus purpuratus is controlled by interactions with at least 13 different DNA-binding factors. These interactions occur within a cis-regulatory domain that extends about 2300 bp upstream from the transcription start site. A recent functional characterization of this domain reveals six different subregions, or cis-regulatory modules, each of which displays a specific regulatory subfunction when linked with the basal promoter and in some cases various other modules (C.-H. Yuh and E. Davidson (1996) Development 122, 1069-1082). In the present work, we analyzed quantitative time-course measurements of the CAT enzyme output of embryos bearing expression...
15.
Cis-regulatory logic in the endo16 gene: switching from a specification to a differentiation mode of control - Yuh, Chiou-Hwa; Bolouri, Hamid; Davidson, Eric H.
The endo16 gene of Strongylocentrotus purpuratus encodes a secreted protein of the embryonic and larval midgut. The overall functional organization of the spatial and temporal control system of this gene are relatively well known from a series of earlier cis-regulatory studies. Our recent computational model for the logic operations of the proximal region of the endo16 control system (Module A) specifies the function of interactions at each transcription factor target site of Module A. Here, we extend sequence level functional analysis to the adjacent cis-regulatory region, Module B. The computational logic model is broadened to include B/A interactions as well...
16.
Far-infrared imaging of tokamak plasma - Young, P. E.; Luhmann, N. C., Jr.; Taylor, R. J.; Neikirk, D. P.; Rutledge, D. B.
A 20-channel interferometer has been developed which utilizes a linear, one-dimensional microbolometer array to obtain single-shot density profiles from the UCLA Microtor tokamak plasma. The interferometer has been used to study time-dependent phenomena in the plasma density profile. Observations of the sawtooth instability clearly show the growth of the m=0 mode from a localized oscillation (r=1 cm) on axis to an oscillation of the entire plasma. Also, measurements during the initial startup phase of the discharge show evidence of hollow density profiles. In addition, a simultaneous measurement of the poloidal magnetic field has been developed which provides 20 channels of...
17.
Multichannel far-infrared phase imaging for fusion plasmas - Young, P. E.; Neikirk, D. P.; Tong, P. P.; Rutledge, D. B.; Luhmann, N. C., Jr.
A 20-channel far-infrared imaging interferometer system has been used to obtain single-shot density profiles in the UCLA Microtor tokamak. This system differs from conventional multichannel interferometers in that the phase distribution produced by the plasma is imaged onto a single, monolithic, integrated microbolometer linear detector array and provides significantly more channels than previous far-infrared interferometers. The system has been demonstrated to provide diffraction-limited phase images of dielectric targets.
18.
Characterization of a Go? Mutant That Binds Xanthine Nucleotides - Yu, Bo; Slepak, Vladlen Z.; Simon, Melvin I.
Several GTP binding proteins, including EF-Tu, Ypt1, rab-5, and FtsY, and adenylosuccinate synthetase have been reported to bind xanthine nucleotides when the conserved aspartate residue in the NKXD motif was changed to asparagine. However, the corresponding single Go? mutant protein (D273N) did not bind either xanthine nucleotides or guanine nucleotides. Interestingly, the introduction of a second mutation to generate the Go? subunit D273N/Q205L switched nucleotide binding specificity to xanthine nucleotide. The double mutant protein Go?D273N/Q205L (Go?X) bound xanthine triphosphate, but not guanine triphosphate. Recombinant Go?X (Go?D273N/Q205L) formed heterotrimers with ?? complexes only in the presence of xanthine diphosphate (XDP), and...
19.
Cooperation of Gq, Gi, and G12/13 in Protein Kinase D Activation and Phosphorylation Induced by Lysophosphatidic Acid - Yuan, Jingzhen; Slice, Lee W.; Gu, Jennifer; Rozengurt, Enrique
To examine the contribution of different G-protein pathways to lysophosphatidic acid (LPA)-induced protein kinase D (PKD) activation, we tested the effect of LPA on PKD activity in murine embryonic cell lines deficient in Galpha q/11 (Galpha q/11 KO cells) or Galpha 12/13 (Galpha 12/13 KO cells) and used cells lacking rhodopsin kinase (RK cells) as a control. In RK and Galpha 12/13 KO cells, LPA induced PKD activation through a phospholipase C/protein kinase C pathway in a concentration-dependent fashion with maximal stimulation (6-fold for RK cells and 4-fold for Galpha 12/13 KO cells in autophosphorylation activity) achieved at 3 µM....
20.
Inhibition of Subsets of G Protein-coupled Receptors by Empty Mutants of G Protein ? Subunits in Go, G11, and G16 - Yu, Bo; Gu, Lingjie; Simon, Melvin I.
We previously reported that the xanthine nucleotide binding Go? mutant, Go?X, inhibited the activation of Gi-coupled receptors. We constructed similar mutations in G11? and G16? and characterized their nucleotide binding and receptor interaction. First, we found that G11?X and G16?X expressed in COS-7 cells bound xanthine 5'-O-(thiotriphosphate) instead of guanosine 5'-O-(thiotriphosphate). Second, we found that G11?X and G16?X interacted with ?? subunits in the presence of xanthine diphosphate. These experiments demonstrated that G11a?X and G16?X were xanthine nucleotide-binding proteins, similar to Go?X. Third, in COS-7 cells, both G11?X and G16?X inhibited the activation of Gq-coupled receptors, whereas only G16?X inhibited...
1.
