8,780 research outputs found
Entomopathogenic nematodes for biological control of codling moth
Entomopathogenic nematodes are often found naturally infecting codling moth larvae. The
effect of an autumn treatment with S. feltiae on the fruit damage in the following summer
was evaluated by treating 4 different apple orchards in October 2004 and 2005 at
application rates of 3.75; 2 and 1.5 billion nematodes in 4000 l / ha. In three of the treated
orchards, one treated with 3.75x109 nematodes/ha the other two treated with 2e9
nematode/ha, reduction in fruit damage was around 50%. In the most heavily infested
orchard, which was treated with 1.5x109 nematode/ha only 33% reduction in fruit damage
was achieved. Compared to previous studies, this was the first assessing the effect on the
fruit damage in the summer following the treatment rather than assessing the mortality of
sentinel larvae fixed to the treated tree trunks
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Binding to medium and long chain fatty acyls is a common property of HEAT and ARM repeat modules.
Covalent post-translational modification (PTM) of proteins with acyl groups of various carbon chain-lengths regulates diverse biological processes ranging from chromatin dynamics to subcellular localization. While the YEATS domain has been found to be a prominent reader of acetylation and other short acyl modifications, whether additional acyl-lysine reader domains exist, particularly for longer carbon chains, is unclear. Here, we employed a quantitative proteomic approach using various modified peptide baits to identify reader proteins of various acyl modifications. We discovered that proteins harboring HEAT and ARM repeats bind to lysine myristoylated peptides. Recombinant HEAT and ARM repeats bind to myristoylated peptides independent of the peptide sequence or the position of the myristoyl group. Indeed, HEAT and ARM repeats bind directly to medium- and long-chain free fatty acids (MCFA and LCFA). Lipidomic experiments suggest that MCFAs and LCFAs interact with HEAT and ARM repeat proteins in mammalian cells. Finally, treatment of cells with exogenous MCFAs and inhibitors of MCFA-CoA synthases increase the transactivation activity of the ARM repeat protein β-catenin. Taken together, our results suggest an unappreciated role for fatty acids in the regulation of proteins harboring HEAT or ARM repeats
Impeded Growth of Magnetic Flux Bubbles in the Intermediate State Pattern of Type I Superconductors
Normal state bubble patterns in Type I superconducting Indium and Lead slabs
are studied by the high resolution magneto-optical imaging technique. The size
of bubbles is found to be almost independent of the long-range interaction
between the normal state domains. Under bubble diameter and slab thickness
proper scaling, the results gather onto a single master curve. On this basis,
in the framework of the "current-loop" model [R.E. Goldstein, D.P. Jackson and
A.T. Dorsey, Phys. Rev. Lett. 76, 3818 (1996)], we calculate the equilibrium
diameter of an isolated bubble resulting from the competition between the
Biot-and-Savart interaction of the Meissner current encircling the bubble and
the superconductor-normal interface energy. A good quantitative agreement with
the master curve is found over two decades of the magnetic Bond number. The
isolation of each bubble in the superconducting matrix and the existence of a
positive interface energy are shown to preclude any continuous size variation
of the bubbles after their formation, contrary to the prediction of mean-field
models.Comment: \'{e}quipe Nanostructures Quantique
The supernova impostor PSN J09132750+7627410 and its progenitor
We report the results of our follow-up campaign of the supernova impostor PSN
J09132750+7627410, based on optical data covering . From the
beginning, the transient shows prominent narrow Balmer lines with P-Cygni
profiles, with a blue-shifted absorption component becoming more prominent with
time. Along the of the spectroscopic monitoring, broad
components are never detected in the hydrogen lines, suggesting that these
features are produced in slowly expanding material. The transient reaches an
absolute magnitude at maximum, a typical
luminosity for supernova impostors. Amateur astronomers provided
of archival observations of the host galaxy, NGC 2748. The
detection of the quiescent progenitor star in archival images obtained with the
Hubble Space Telescope suggests it to be an \msun white-yellow
supergiant.Comment: 7 pages, 4 figures, supplemental material available in the source
file. Accepted for publication on Astrophysical Journal Letter
Comparing and characterizing some constructions of canonical bases from Coxeter systems
The Iwahori-Hecke algebra of a Coxeter system has a
"standard basis" indexed by the elements of and a "bar involution" given by
a certain antilinear map. Together, these form an example of what Webster calls
a pre-canonical structure, relative to which the well-known Kazhdan-Lusztig
basis of is a canonical basis. Lusztig and Vogan have defined a
representation of a modified Iwahori-Hecke algebra on the free
-module generated by the set of twisted involutions in
, and shown that this module has a unique pre-canonical structure satisfying
a certain compatibility condition, which admits its own canonical basis which
can be viewed as a generalization of the Kazhdan-Lusztig basis. One can modify
the parameters defining Lusztig and Vogan's module to obtain other
pre-canonical structures, each of which admits a unique canonical basis indexed
by twisted involutions. We classify all of the pre-canonical structures which
arise in this fashion, and explain the relationships between their resulting
canonical bases. While some of these canonical bases are related in a trivial
fashion to Lusztig and Vogan's construction, others appear to have no simple
relation to what has been previously studied. Along the way, we also clarify
the differences between Webster's notion of a canonical basis and the related
concepts of an IC basis and a -kernel.Comment: 32 pages; v2: additional discussion of relationship between canonical
bases, IC bases, and P-kernels; v3: minor revisions; v4: a few corrections
and updated references, final versio
Near-infrared light curves of type Ia supernovae
Aims. With our time-dependent model atmosphere code PHOENIX, our goal is to
simulate light curves and spectra of hydrodynamical models of all types of
supernovae. In this work, we simulate near-infrared light curves of SNe Ia and
confirm the cause of the secondary maximum. Methods. We apply a simple energy
solver to compute the evolution of an SN Ia envelope during the free expansion
phase. Included in the solver are energy changes due to expansion, the energy
deposition of {\gamma}-rays and interaction of radiation with the material.
Results. We computed theoretical light curves of several SN Ia hydrodynamical
models in the I, J, H, and K bands and compared them to the observed SN Ia
light curves of SN 1999ee and SN 2002bo. By changing a line scattering
parameter in time, we obtained quite reasonable fits to the observed
near-infrared light curves. This is a strong hint that detailed NLTE effects in
IR lines have to be modeled, which will be a future focus of our work.
Conclusions. We found that IR line scattering is very important for the
near-infrared SN Ia light curve modeling. In addition, the recombination of Fe
III to Fe II and of Co III to Co II is responsible for the secondary maximum in
the near-infrared bands. For future work the consideration of NLTE for all
lines (including the IR subordinate lines) will be crucial.Comment: 5 pages, 12 figures, A&A in pres
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Proteomic Profiling of γ-Secretase Substrates and Mapping of Substrate Requirements
The presenilin/γ-secretase complex, an unusual intramembrane aspartyl protease, plays an essential role in cellular signaling and membrane protein turnover. Its ability to liberate numerous intracellular signaling proteins from the membrane and also mediate the secretion of amyloid-β protein (Aβ) has made modulation of γ-secretase activity a therapeutic goal for cancer and Alzheimer disease. Although the proteolysis of the prototypical substrates Notch and β-amyloid precursor protein (APP) has been intensely studied, the full spectrum of substrates and the determinants that make a transmembrane protein a substrate remain unclear. Using an unbiased approach to substrate identification, we surveyed the proteome of a human cell line for targets of γ-secretase and found a relatively small population of new substrates, all of which are type I transmembrane proteins but have diverse biological roles. By comparing these substrates to type I proteins not regulated by γ-secretase, we determined that besides a short ectodomain, γ-secretase requires permissive transmembrane and cytoplasmic domains to bind and cleave its substrates. In addition, we provide evidence for at least two mechanisms that can target a substrate for γ cleavage: one in which a substrate with a short ectodomain is directly cleaved independent of sheddase association, and a second where a substrate requires ectodomain shedding to instruct subsequent γ-secretase processing. These findings expand our understanding of the mechanisms of substrate selection as well as the diverse cellular processes to which γ-secretase contributes
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