153 research outputs found
Submillimeter Wave Astronomy Satellite mapping observations of water vapor around Sagittarius B2
Observations of the 1(10)-1(01) 556.936 GHz transition of ortho-water with
the Submillimeter Wave Astronomy Satellite (SWAS) have revealed the presence of
widespread emission and absorption by water vapor around the strong
submillimeter continuum source Sagittarius B2. An incompletely-sampled spectral
line map of a region of size 26 x 19 arcmin around Sgr B2 reveals three
noteworthy features. First, absorption by foreground water vapor is detectable
at local standard-of-rest (LSR) velocities in the range -100 to 0 km/s at
almost every observed position. Second, spatially-extended emission by water is
detectable at LSR velocities in the range 80 to 120 km/s at almost every
observed position. This emission is attributable to the 180-pc molecular ring
identified from previous observations of CO. The typical peak antenna
temperature of 0.075 K for this component implies a typical water abundance of
1.2E-6 to 8E-6 relative to H2. Third, strong absorption by water is observed
within 5 arcmin of Sgr B2 at LSR velocities in the range 60 to 82 km/s. An
analysis of this absorption yields a H2O abundance ~ 2E-7 to 4E-7 relative to
H2 if the absorbing water vapor is located within the core of Sgr B2 itself;
or, alternatively, a water column density ~ 2.5E+16 to 4E+16 per cm2 if the
water absorption originates in the warm, foreground layer of gas proposed
previously as the origin of ammonia absorption observed toward Sgr B2.Comment: 29 pages (AASTeX), including 9 postscript figures, to appear in the
Astrophysical Journa
Near-Infrared Spectroscopy of Molecular Filaments in the Reflection Nebula NGC 7023
We present near-infrared spectroscopy of fluorescent molecular hydrogen (H_2)
emission from molecular filaments in the reflection nebula NGC 7023. We derive
the relative column densities of H_2 rotational-vibrational states from the
measured line emission and compare these results with several model
photodissociation regions covering a range of densities, incident UV-fields,
and excitation mechanisms. Our best-fit models for one filament suggest, but do
not require, either a combination of different densities, suggesting clumps of
10^6 cm^{-3} in a 10^4 - 10^5 cm^{-3} filament, or a combination of fluorescent
excitation and thermally-excited gas, perhaps due to a shock from a bipolar
outflow. We derive densities and UV fields for these molecular filaments that
are in agreement with previous determinations.Comment: ApJ accepted, 26 pages including 5 embedded figures, uses AASTEX.
Also available at http://www-astronomy.mps.ohio-state.edu/~martini/pubs.htm
Near-Infrared Spectroscopy of Molecular Hydrogen Emission in Four Reflection Nebulae: NGC 1333, NGC 2023, NGC 2068, and NGC 7023
We present near-infrared spectroscopy of fluorescent molecular hydrogen (H_2)
emission from NGC 1333, NGC 2023, NGC 2068, and NGC 7023 and derive the
physical properties of the molecular material in these reflection nebulae. Our
observations of NGC 2023 and NGC 7023 and the physical parameters we derive for
these nebulae are in good agreement with previous studies. Both NGC 1333 and
NGC 2068 have no previously-published analysis of near-infrared spectra. Our
study reveals that the rotational-vibrational states of molecular hydrogen in
NGC 1333 are populated quite differently from NGC 2023 and NGC 7023. We
determine that the relatively weak UV field illuminating NGC 1333 is the
primary cause of the difference. Further, we find that the density of the
emitting material in NGC 1333 is of much lower density, with n ~ 10^2 - 10^4
cm^-3. NGC 2068 has molecular hydrogen line ratios more similar to those of NGC
7023 and NGC 2023. Our model fits to this nebula show that the bright,
H_2-emitting material may have a density as high as n ~ 10^5 cm^-3, similar to
what we find for NGC 2023 and NGC 7023. Our spectra of NGC 2023 and NGC 7023
show significant changes in both the near-infrared continuum and H_2 intensity
along the slit and offsets between the peaks of the H_2 and continuum emission.
We find that these brightness changes may correspond to real changes in the
density and temperatures of the emitting region, although uncertainties in the
total column of emitting material along a given line of sight complicates the
interpretation. The spatial difference in the peak of the H_2 and near-infrared
continuum peaks in NGC 2023 and NGC 7023 shows that the near-infrared continuum
is due to a material which can survive closer to the star than H_2 can.Comment: Submitted for publication in ApJ. 34 pages including 12 embedded
postscript figures. Also available at
http://www.astronomy.ohio-state.edu/~martini/pub
Epigenetic studies in children at risk of stunting and their parents in India, Indonesia and Senegal : A UKRI GCRF Action Against Stunting Hub protocol paper
ASR provided research and organisational support within the Action Against Stunting Hub (AASH) epigenetics theme and drafted and revised the manuscript. MN led the AASH epigenetic theme in Senegal and oversees the implementation of the epigenetic protocol and contributed to the development of the protocol and critically revised the manuscript. RRK led the AASH epigenetic theme in India and oversaw the implementation of the epigenetic protocol, contributed to the development of the protocol and critically revised the manuscript. MKH led the AASH epigenetic theme in Indonesia and oversaw the implementation of the epigenetic protocol, contributed to the development of the protocol and critically revised the manuscript. DYD was responsible for monitoring evaluation and learning on the hub, critically reviewed the protocol and revised the manuscript. LFA managed the implementation of the study in India, critically reviewed the protocol and revised the manuscript. NLZ managed the implementation of the study in Indonesia, critically reviewed the protocol and revised the manuscript. AD managed the implementation of the study in Senegal, critically reviewed the protocol and revised the manuscript. DY, TCA and MN are epigenetic researchers in Indonesia, critically reviewed the protocol and reviewed the manuscript. MG, DS, SSV and MM are epigenetic researchers in India, critically reviewed the protocol and reviewed the manuscript. GWH advised on the statistical aspects of the protocol and the power calculation and reviewed the manuscript. UF is the AASH project lead in Indonesia, contributed to study design and coordination of the study and thematic linkages; supervised drafting of the manuscript. BF is the AASH project lead in Senegal, contributed to study design and coordination of the study and thematic linkages and supervised drafting of the manuscript. BK is the AASH project lead in India, contributed to study design and coordination of the study and thematic linkages and supervised drafting of the manuscript. PH is the AASH project deputy lead and epigenetic theme lead who designed the study, drafted and revised the manuscript, carried out the statistical calculations.Peer reviewe
Ixodes ricinus Tick Lipocalins: Identification, Cloning, Phylogenetic Analysis and Biochemical Characterization
BACKGROUND: During their blood meal, ticks secrete a wide variety of proteins that interfere with their host's defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response. METHODOLOGY/PRINCIPAL FINDINGS: Screening a cDNA library in association with RT-PCR and RACE methodologies allowed us to identify 14 new lipocalin genes in the salivary glands of the Ixodes ricinus hard tick. A computational in-depth structural analysis confirmed that LIRs belong to the lipocalin family. These proteins were called LIR for "Lipocalin from I. ricinus" and numbered from 1 to 14 (LIR1 to LIR14). According to their percentage identity/similarity, LIR proteins may be assigned to 6 distinct phylogenetic groups. The mature proteins have calculated pM and pI varying from 21.8 kDa to 37.2 kDa and from 4.45 to 9.57 respectively. In a western blot analysis, all recombinant LIRs appeared as a series of thin bands at 50-70 kDa, suggesting extensive glycosylation, which was experimentally confirmed by treatment with N-glycosidase F. In addition, the in vivo expression analysis of LIRs in I. ricinus, examined by RT-PCR, showed homogeneous expression profiles for certain phylogenetic groups and relatively heterogeneous profiles for other groups. Finally, we demonstrated that LIR6 codes for a protein that specifically binds leukotriene B4. CONCLUSIONS/SIGNIFICANCE: This work confirms that, regarding their biochemical properties, expression profile, and sequence signature, lipocalins in Ixodes hard tick genus, and more specifically in the Ixodes ricinus species, are segregated into distinct phylogenetic groups suggesting potential distinct function. This was particularly demonstrated by the ability of LIR6 to scavenge leukotriene B4. The other LIRs did not bind any of the ligands tested, such as 5-hydroxytryptamine, ADP, norepinephrine, platelet activating factor, prostaglandins D2 and E2, and finally leukotrienes B4 and C4.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe
Resolvin D2 is a potent regulator of leukocytes and controls microbial sepsis
National Institutes of Health grants GM-38765 and P50-DE016191 (C.N.S.), Welcome Trust Programme grant 086867/Z/08/Z (R.J.F. and M.P.) and Project grant 085903/Z/08 (R.J.F.) and Arthritis Research Campaign UK fellowships 18445 and 18103 (to L.V.N. and D.C., respectively). M.S. received a National Research Service Award from the NHLBI (HL087526)
Complexity of the Tensegrity Structure for Dynamic Energy and Force Distribution of Cytoskeleton during Cell Spreading
Cytoskeleton plays important roles in intracellular force equilibrium and extracellular force transmission from/to attaching substrate through focal adhesions (FAs). Numerical simulations of intracellular force distribution to describe dynamic cell behaviors are still limited. The tensegrity structure comprises tension-supporting cables and compression-supporting struts that represent the actin filament and microtubule respectively, and has many features consistent with living cells. To simulate the dynamics of intracellular force distribution and total stored energy during cell spreading, the present study employed different complexities of the tensegrity structures by using octahedron tensegrity (OT) and cuboctahedron tensegrity (COT). The spreading was simulated by assigning specific connection nodes for radial displacement and attachment to substrate to form FAs. The traction force on each FA was estimated by summarizing the force carried in sounding cytoskeletal elements. The OT structure consisted of 24 cables and 6 struts and had limitations soon after the beginning of spreading by declining energy stored in struts indicating the abolishment of compression in microtubules. The COT structure, double the amount of cables and struts than the OT structure, provided sufficient spreading area and expressed similar features with documented cell behaviors. The traction force pointed inward on peripheral FAs in the spread out COT structure. The complex structure in COT provided further investigation of various FA number during different spreading stages. Before the middle phase of spreading (half of maximum spreading area), cell attachment with 8 FAs obtained minimized cytoskeletal energy. The maximum number of 12 FAs in the COT structure was required to achieve further spreading. The stored energy in actin filaments increased as cells spread out, while the energy stored in microtubules increased at initial spreading, peaked in middle phase, and then declined as cells reached maximum spreading. The dynamic flows of energy in struts imply that microtubules contribute to structure stabilization
Evolutionary Origins and Functions of the Carotenoid Biosynthetic Pathway in Marine Diatoms
Carotenoids are produced by all photosynthetic organisms, where they play essential roles in light harvesting and photoprotection. The carotenoid biosynthetic pathway of diatoms is largely unstudied, but is of particular interest because these organisms have a very different evolutionary history with respect to the Plantae and are thought to be derived from an ancient secondary endosymbiosis between heterotrophic and autotrophic eukaryotes. Furthermore, diatoms have an additional xanthophyll-based cycle for dissipating excess light energy with respect to green algae and higher plants. To explore the origins and functions of the carotenoid pathway in diatoms we searched for genes encoding pathway components in the recently completed genome sequences of two marine diatoms. Consistent with the supplemental xanthophyll cycle in diatoms, we found more copies of the genes encoding violaxanthin de-epoxidase (VDE) and zeaxanthin epoxidase (ZEP) enzymes compared with other photosynthetic eukaryotes. However, the similarity of these enzymes with those of higher plants indicates that they had very probably diversified before the secondary endosymbiosis had occurred, implying that VDE and ZEP represent early eukaryotic innovations in the Plantae. Consequently, the diatom chromist lineage likely obtained all paralogues of ZEP and VDE genes during the process of secondary endosymbiosis by gene transfer from the nucleus of the algal endosymbiont to the host nucleus. Furthermore, the presence of a ZEP gene in Tetrahymena thermophila provides the first evidence for a secondary plastid gene encoded in a heterotrophic ciliate, providing support for the chromalveolate hypothesis. Protein domain structures and expression analyses in the pennate diatom Phaeodactylum tricornutum indicate diverse roles for the different ZEP and VDE isoforms and demonstrate that they are differentially regulated by light. These studies therefore reveal the ancient origins of several components of the carotenoid biosynthesis pathway in photosynthetic eukaryotes and provide information about how they have diversified and acquired new functions in the diatoms
Up-Regulation of Annexin-A1 and Lipoxin A4 in Individuals with Ulcerative Colitis May Promote Mucosal Homeostasis
PubMed ID: 22723974This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
The Human Serum Metabolome
Continuing improvements in analytical technology along with an increased interest in performing comprehensive, quantitative metabolic profiling, is leading to increased interest pressures within the metabolomics community to develop centralized metabolite reference resources for certain clinically important biofluids, such as cerebrospinal fluid, urine and blood. As part of an ongoing effort to systematically characterize the human metabolome through the Human Metabolome Project, we have undertaken the task of characterizing the human serum metabolome. In doing so, we have combined targeted and non-targeted NMR, GC-MS and LC-MS methods with computer-aided literature mining to identify and quantify a comprehensive, if not absolutely complete, set of metabolites commonly detected and quantified (with today's technology) in the human serum metabolome. Our use of multiple metabolomics platforms and technologies allowed us to substantially enhance the level of metabolome coverage while critically assessing the relative strengths and weaknesses of these platforms or technologies. Tables containing the complete set of 4229 confirmed and highly probable human serum compounds, their concentrations, related literature references and links to their known disease associations are freely available at http://www.serummetabolome.ca
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