8,808 research outputs found
Cutting Edge : Failure of Antigen-Specific CD4+ T Cell Recruitment to the Kidney during Systemic Candidiasis
Copyright © 2014 The Authors. Acknowledgments We thank E. Bolton and H. Bagavant for reagents and advice. We also acknowledge the staff of the Medical Research Facility at the University of Aberdeen for care of the animals used in this study. This work was supported by the Medical Research Council and the Wellcome Trust.Peer reviewedPublisher PD
On the kinks and dynamical phase transitions of alpha-helix protein chains
Heuristic insights into a physical picture of Davydov's solitonic model of
the one-dimensional protein chain are presented supporting the idea of a
non-equilibrium competition between the Davydov phase and a complementary,
dynamical- `ferroelectric' phase along the chainComment: small latex file with possible glue problems, just go on !, no
figures, small corrections with respect to the published text, follow-up work
to cond-mat/9304034 [PRE 47 (June 1993) R3818
RNAseq reveals hydrophobins that are involved in the adaptation of aspergillus nidulans to lignocellulose
Background
Sugarcane is one of the world’s most profitable crops. Waste steam-exploded sugarcane bagasse (SEB) is a cheap, abundant, and renewable lignocellulosic feedstock for the next-generation biofuels. In nature, fungi seldom exist as planktonic cells, similar to those found in the nutrient-rich environment created within an industrial fermenter. Instead, fungi predominantly form biofilms that allow them to thrive in hostile environments.
Results
In turn, we adopted an RNA-sequencing approach to interrogate how the model fungus, Aspergillus nidulans, adapts to SEB, revealing the induction of carbon starvation responses and the lignocellulolytic machinery, in addition to morphological adaptations. Genetic analyses showed the importance of hydrophobins for growth on SEB. The major hydrophobin, RodA, was retained within the fungal biofilm on SEB fibres. The StuA transcription factor that regulates fungal morphology was up-regulated during growth on SEB and controlled hydrophobin gene induction. The absence of the RodA or DewC hydrophobins reduced biofilm formation. The loss of a RodA or a functional StuA reduced the retention of the hydrolytic enzymes within the vicinity of the fungus. Hence, hydrophobins promote biofilm formation on SEB, and may enhance lignocellulose utilisation via promoting a compact substrate-enzyme-fungus structure.
Conclusion
This novel study highlights the importance of hydrophobins to the formation of biofilms and the efficient deconstruction of lignocellulose
The experimental gas-phase structures of 1,3,5-trisilylbenzene and hexasilylbenzene and the theoretical structures of all benzenes with three or more silyl substituents
The structures of 1,3,5-trisilylbenzene and hexasilylbenzene in the gas phase have been determined by electron diffraction, and that of 1,3,5-trisilylbenzene by X-ray crystallography. The structures of three trisilylbenzene isomers, three tetrasilylbenzenes, pentasilylbenzene and hexasilylbenzene have been computed, ab initio and using Density Functional Theory, at levels up to MP2/6-31G*. The primary effect of silyl substituents is to narrow the ring angle at the substituted carbon atoms. Steric interactions between silyl groups on neighbouring carbon atoms lead first to displacement of these groups away from one another, and then to displacement out of the ring plane, with alternate groups moving to opposite sides of the ring. In the extreme example, hexasilylbenzene, the SiCCSi dihedral angle is 17.8(8)°
C3b/iC3b Deposition on Streptococcus pneumoniae Is Not Affected by HIV Infection
Streptococcus pneumoniae is a common cause of infection in both HIV positive patients and those with complement deficiencies. We hypothesised that HIV positive individuals might exhibit reduced opsonisation of pneumococcus with complement due to reduced levels of S. pneumoniae specific IgG. We discovered no difference in C3 deposition on S. pneumoniae between HIV positive or negative individuals, and furthermore C3 deposition remained unchanged as HIV progressed towards AIDS. We found no correlation between C3 deposition on S. pneumoniae and CD4 cell count in HIV infected individuals. Hence we have demonstrated no failure of complement immunity in HIV positive patients
Does M31 result from an ancient major merger?
The numerous streams in the M31 halo are currently assumed to be due to
multiple minor mergers. Here we use the GADGET2 simulation code to test whether
M31 could have experienced a major merger in its past history. It results that
a 3+/-0.5:1 gaseous rich merger with r(per)=25+/-5 kpc and a polar orbit can
explain many properties of M31 and of its halo. The interaction and the fusion
may have begun 8.75+/-0.35 Gyr and 5.5 +/-0.5 Gyr ago, respectively. With an
almost quiescent star formation history before the fusion we retrieve fractions
of bulge, thin and thick disks as well as relative fractions of intermediate
age and old stars in both the thick disk and the Giant Stream. The Giant Stream
is caused by returning stars from a tidal tail previously stripped from the
satellite prior to the fusion. These returning stars are trapped into
elliptical orbits or loops for almost a Hubble time period. Large loops are
also predicted and they scale rather well with the recently discovered features
in the M31 outskirts. We demonstrate that a single merger could explain
first-order (intensity and size), morphological and kinematical properties of
the disk, thick disk, bulge and streams in the halo of M31, as well as the
distribution of stellar ages, and perhaps metallicities. It challenges
scenarios assuming one minor merger per feature in the disk (10 kpc ring) or at
the outskirts (numerous streams & thick disk). Further constraints will help to
properly evaluate the impact of such a major event to the Local Group.Comment: accepted in Astrophysical Journal, 29 September, 2010 ; proof-edited
version; 1st column of Table 3 correcte
Impulsive phase transport
The transport of nonthermal electrons is explored. The thick-target electron beam model, in which electrons are presumed to be accelerated in the corona and typically thermalized primarily in the chromosphere and photosphere, is supported by observations throughout the electromagnetic spectrum. At the highest energies, the anisotropy of gamma-ray emission above 10 MeV clearly indicates that these photons are emitted by anisotropically-directed particles. The timing of this high-energy gamma-radiation with respect to lower-energy hard X-radiation implies that the energetic particles have short life-times. For collisional energy loss, this means that they are stopped in the chromosphere or below. Stereoscopic (two-spacecraft) observations at hard X-ray energies (up to 350 keV) imply that these lower-energy (but certainly nonthermal) electrons are also stopped deep in the chromosphere. Hard X-ray images show that, in spatially resolved flares whose radiation consists of impulsive bursts, the impulsive phase starts with X-radiation that comes mostly from the foot-points of coronal loops whose coronal component is outlined by microwaves
Experimental investigation of planar ion traps
Chiaverini et al. [Quant. Inf. Comput. 5, 419 (2005)] recently suggested a
linear Paul trap geometry for ion trap quantum computation that places all of
the electrodes in a plane. Such planar ion traps are compatible with modern
semiconductor fabrication techniques and can be scaled to make compact, many
zone traps. In this paper we present an experimental realization of planar ion
traps using electrodes on a printed circuit board to trap linear chains of tens
of 0.44 micron diameter charged particles in a vacuum of 15 Pa (0.1 torr). With
these traps we address concerns about the low trap depth of planar ion traps
and develop control electrode layouts for moving ions between trap zones
without facing some of the technical difficulties involved in an atomic ion
trap experiment. Specifically, we use a trap with 36 zones (77 electrodes)
arranged in a cross to demonstrate loading from a traditional four rod linear
Paul trap, linear ion movement, splitting and joining of ion chains, and
movement of ions through intersections. We further propose an additional DC
biased electrode above the trap which increases the trap depth dramatically,
and a novel planar ion trap geometry that generates a two dimensional lattice
of point Paul traps.Comment: 11 pages, 20 figure
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