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De novo formation of an aggregation pheromone precursor by an isoprenyl diphosphate synthase-related terpene synthase in the harlequin bug.
Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (1S,6S,7R)-1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication
The Baryon Census in a Multiphase Intergalactic Medium: 30% of the Baryons May Still Be Missing
For low-redshift cosmology and galaxy formation rates, it is important to
account for all the baryons synthesized in the Big Bang. Although galaxies and
clusters contain 10% of the baryons, many more reside in the photoionized
Lyman-alpha forest and shocked-heated warm-hot intergalactic medium (WHIM) at T
= 10^5 to 10^7 K. Current tracers of WHIM at 10^5 to 10^6 K include the O VI
1032, 1038 absorption lines, together with broad Lyman-alpha absorbers (BLAs)
and EUV/X-ray absorption lines from Ne VIII, O VII, and O VIII. We improve the
O VI baryon surveys with corrections for oxygen metallicity (Z/Zsun) and O VI
ionization fraction (f_OVI) using cosmological simulations of heating, cooling,
and metal transport in a density-temperature structured medium. Statistically,
their product correlates with column density, (Z/Zsun)(f_OVI) =
(0.015)(N_OVI/10^{14} cm^-2)^0.70. The N_OVI-weighted mean is 0.01, which
doubles previous estimates of WHIM baryon content. We also reanalyze H I data
from the Hubble Space Telescope, applying redshift corrections for absorber
density, photoionizing background, and proper length, dl/dz. We find
substantial baryon fractions in the photoionized Lya forest (28 +/- 11%), O
VI/BLA-traced WHIM (25 +/- 8%), and collapsed phase (18 +/- 4%) in galaxies,
groups, clusters, and circumgalactic gas. The baryon shortfall is 29 +/- 13%,
which may be detected in X-ray absorbers from hotter WHIM or in weaker Lya and
O VI absorbers. Further progress will require higher-precision baryon surveys
of weak absorbers at column densities N_HI > 10^{12.0} cm^-2, N_OVI > 10^{12.5}
cm^-2, and N_OVII > 10^{14.5} cm^-2, with moderate-resolution UV and X-ray
spectrographs.Comment: 14 pages, 9 figures, revised submission to ApJ (new Fig 2, Appendices
A,B
The Epstein-Barr Virus G-Protein-Coupled Receptor Contributes to Immune Evasion by Targeting MHC Class I Molecules for Degradation
Epstein-Barr virus (EBV) is a human herpesvirus that persists as a largely subclinical infection in the vast majority of adults worldwide. Recent evidence indicates that an important component of the persistence strategy involves active interference with the MHC class I antigen processing pathway during the lytic replication cycle. We have now identified a novel role for the lytic cycle gene, BILF1, which encodes a glycoprotein with the properties of a constitutive signaling G-protein-coupled receptor (GPCR). BILF1 reduced the levels of MHC class I at the cell surface and inhibited CD8+ T cell recognition of
endogenous target antigens. The underlying mechanism involves physical association of BILF1 with MHC class I molecules, an increased turnover from the cell surface, and enhanced degradation via lysosomal proteases. The BILF1 protein of the closely related CeHV15 c1-herpesvirus of the Rhesus Old World primate (80% amino acid sequence identity) downregulated surface MHC class I similarly to EBV BILF1. Amongst the human herpesviruses, the GPCR encoded by the ORF74 of the KSHV c2-herpesvirus is most closely related to EBV BILF1 (15% amino acid sequence identity) but did not affect levels of surface MHC class I. An engineered mutant of BILF1 that was unable to activate G protein signaling pathways retained the ability to downregulate MHC class I, indicating that the immune-modulating and GPCR-signaling properties are two distinct functions of BILF1. These findings extend our understanding of the normal biology of an important human pathogen. The discovery of a third EBV lytic cycle gene that cooperates to interfere with MHC class I antigen processing underscores the importance of the need for EBV to be able to evade CD8+ T cell responses during the lytic replication cycle, at a time when such a large number of potential viral targets are expressed
Warm Gas in the Virgo Cluster: I. Distribution of Lya Absorbers
The first systematic study of the warm gas (T=10^4-5 K) distribution across a
galaxy cluster is presented using multiple background QSOs to the Virgo
Cluster. We detect 25 Lya absorbers (N_HI = 10^13.1-15.4 cm^-2) in the Virgo
velocity range toward 9 of 12 QSO sightlines observed with Cosmic Origin
Spectrograph, with a cluster impact parameter range of 0.36-1.65 Mpc
(0.23-1.05R_vir). Including 18 Lya absorbers previously detected by STIS or
GHRS toward 7 of 11 background QSOs in and around the Virgo Cluster, we
establish a sample of 43 absorbers towards a total of 23 background probes for
studying the incidence of Lya absorbers in and around the Virgo Cluster. With
these absorbers, we find: (1) warm gas is predominantly in the outskirts of the
cluster and avoids the X-ray detected hot ICM. Also, Lya absorption strength
increases with cluster impact parameter. (2) Lya absorbing warm gas traces cold
HI emitting gas in the substructures of the Virgo Cluster. (3) Including the
absorbers associated with the surrounding substructures, the warm gas covering
fraction (100% for N_HI > 10^13.1 cm^-2) is in agreement with cosmological
simulations. We speculate that the observed warm gas is part of large-scale gas
flows feeding the cluster both the ICM and galaxies.Comment: 15 pages, 6 figures, 8 tables, ApJ in pres
Metal-enriched, subkiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy★
We report the serendipitous detection of a 0.2 L, Lyman- emitting
galaxy at redshift 2.5 at an impact parameter of 50 kpc from a bright
background QSO sightline. A high-resolution spectrum of the QSO reveals a
partial Lyman-limit absorption system (
cm) with many associated metal absorption lines at the same redshift as
the foreground galaxy. Using photoionization models that carefully treat
measurement errors and marginalise over uncertainties in the shape and
normalisation of the ionizing radiation spectrum, we derive the total hydrogen
column density cm, and show that all the
absorbing clouds are metal enriched, with -. These
metallicities and the system's large velocity width ( kms)
suggest the gas is produced by an outflowing wind. Using an expanding shell
model we estimate a mass outflow rate of yr. Our
photoionization model yields extremely small sizes (100-500 pc) for the
absorbing clouds, which we argue are typical of high column density absorbers
in the circumgalactic medium (CGM). Given these small sizes and extreme
kinematics, it is unclear how the clumps survive in the CGM without being
destroyed by hydrodynamic instabilities. The small cloud sizes imply that even
state-of-the-art cosmological simulations require more than a -fold
improvement in mass resolution to resolve the hydrodynamics relevant for cool
gas in the CGM.Comment: Fixed an incorrect reference to D'Odorico & Petitjean 2001, A&A, 370,
729. Data and code used for the paper are at https://github.com/nhmc/LA
Сетевая система контроля технологического процесса выращивания полупроводниковых кристаллов и тонких пленок
Экспериментальное моделирование аппаратно-программного обеспечения показало достаточную надежность работы системы и значительное уменьшение трудоемкости контроля и управления параметрами технологического процесса
What has changed in canine pyoderma? A narrative review
Canine pyoderma is a common presentation in small animal practice and frequently leads to prescription of systemic antimicrobial agents. A good foundation of knowledge on pyoderma was established during the 1970s and 1980s, when treatment of infection provided relatively few challenges. However, the ability to treat canine pyoderma effectively is now limited substantially by the emergence of multidrug-resistant, methicillin-resistant staphylococci (MRS) and, in some countries, by restrictions on antimicrobial prescribing for pets. The threat from rising antimicrobial resistance and the zoonotic potential of MRS add a new dimension of public health implications to the management of canine pyoderma and necessitate a revisit and the search for new best management strategies. This narrative review focusses on the impact of MRS on how canine pyoderma is managed and how traditional treatment recommendations need to be updated in the interest of good antimicrobial stewardship. Background information on clinical characteristics, pathogens, and appropriate clinical and microbiological diagnostic techniques, are reviewed in so far as they can support early identification of multidrug-resistant pathogens. The potential of new approaches for the control and treatment of bacterial skin infections is examined and the role of owner education and hygiene is highlighted. Dogs with pyoderma offer opportunities for good antimicrobial stewardship by making use of the unique accessibility of the skin through cytology, bacterial culture and topical therapy. In order to achieve long term success and to limit the spread of multidrug resistance, there is a need to focus on identification and correction of underlying diseases that trigger pyoderma in order to avoid repeated treatment
Baryons: What, When and Where?
We review the current state of empirical knowledge of the total budget of
baryonic matter in the Universe as observed since the epoch of reionization.
Our summary examines on three milestone redshifts since the reionization of H
in the IGM, z = 3, 1, and 0, with emphasis on the endpoints. We review the
observational techniques used to discover and characterize the phases of
baryons. In the spirit of the meeting, the level is aimed at a diverse and
non-expert audience and additional attention is given to describe how space
missions expected to launch within the next decade will impact this scientific
field.Comment: Proceedings Review for "Astrophysics in the Next Decade: JWST and
Concurrent Facilities", ed. X. Tielens, 38 pages, 10 color figures. Revised
to address comments from the communit
Ultraviolet Perspectives on Diffuse Gas in the Largest Cosmic Structures
Large scale structure and cosmolog
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