207 research outputs found
Crystalline cyclophane-protein cage frameworks
open10siCyclophanes are macrocyclic supramolecular hosts famous for their ability to bind atomic or molecular guests via noncovalent interactions within their well-defined cavities. In a similar way, porous crystalline networks, such as metal organic frameworks, can create microenvironments that enable controlled guest binding in the solid state. Both types of materials often consist of synthetic components, and they have been developed within separate research fields. Moreover, the use of biomolecules as their structural units has remained elusive. Here, we have synthesized a library of organic cyclophanes and studied their electrostatic self-assembly with biological metal-binding protein cages (ferritins) into ordered structures. We show that cationic pillar[S]arenes and ferritin cages form biohybrid cocrystals with an open protein network structure. Our cyclophane-protein cage frameworks bridge the gap between molecular frameworks and colloidal nanoparticle crystals and combine the versatility of synthetic supramolecular hosts with the highly selective recognition properties of biomolecules. Such host-guest materials are interesting for porous material applications, including water remediation and heterogeneous catalysis.openBeyeh N.K.; Nonappa; Liljestrom V.; Mikkila J.; Korpi A.; Bochicchio D.; Pavan G.M.; Ikkala O.; Ras R.H.A.; Kostiainen M.A.Beyeh, N. K.; Nonappa, ; Liljestrom, V.; Mikkila, J.; Korpi, A.; Bochicchio, D.; Pavan, G. M.; Ikkala, O.; Ras, R. H. A.; Kostiainen, M. A
GATA6 modulates the ductular reaction to bile duct ligation
Background GATA6, a transcription factor expressed in cholangiocytes, has been implicated in the response to liver injury. In biliary atresia, a disease characterized by extrahepatic bile duct obstruction, liver expression of GATA6 increases with pathological bile duct expansion and decreases after successful Kasai portoenterostomy. The aim of this study was to garner genetic evidence that GATA6 is involved in ductular formation/expansion. Methods The murine Gata6 gene was conditionally deleted using Alb-cre, a transgene expressed in hepatoblasts (the precursors of hepatocytes and cholangiocytes) and mature hepatocytes. Bile duct ligation (BDL) was used to model biliary obstruction. Results Alb-Cre;Gata6(flox/flox) mice were viable and fertile. Cre-mediated recombination of Gata6 in hepatocytes had little impact on cellular structure or function. GATA6 immunoreactivity was retained in a majority of biliary epithelial cells in adult Alb-Cre;Gata6(flox/flox) mice, implying that surviving cholangiocytes were derived from hepatoblasts that had escaped biallelic Cre-mediated recombination. Although GATA6 immunoreactivity was preserved in cholangiocytes, Alb-cre;Gata6(flox/flox) mice had a demonstrable biliary phenotype. A neutrophil-rich infiltrate surrounded newly formed bile ducts in neonatal Alb-Cre;Gata6(flox/flox) mice. Foci of fibrosis/necrosis, presumed to reflect patchy defects in bile duct formation, were observed in the livers of 37% of adult Alb-cre;Gata6(flox/flox) mice and 0% of controls (p <0.05). Most notably, Alb-cre;Gata6(flox/flox) mice had an altered response to BDL manifest as reduced survival, impaired bile ductule proliferation, increased parenchymal necrosis, reduced fibrosis, and enhanced macrophage accumulation in the portal space. Conclusions GATA6 orchestrates intrahepatic biliary remodeling and mitigates liver injury following extrahepatic bile duct obstruction. Graphic abstractPeer reviewe
Reynolds stresses from hydrodynamic turbulence with shear and rotation
To study the Reynolds stresses which describe turbulent momentum transport
from turbulence affected by large-scale shear and rotation. Three-dimensional
numerical simulations are used to study turbulent transport under the
influences of large-scale shear and rotation in homogeneous, isotropically
forced turbulence. We study three cases: one with only shear, and two others
where in addition to shear, rotation is present. These cases differ by the
angle (0 or 90\degr) the rotation vector makes with respect to the z-direction.
Two subsets of runs are performed with both values of \theta where either
rotation or shear is kept constant. When only shear is present, the
off-diagonal stress can be described by turbulent viscosity whereas if the
system also rotates, nondiffusive contributions (\Lambda-effect) to the stress
can arise. Comparison of the direct simulations are made with analytical
results from a simple closure model. We find that the turbulent viscosity is of
the order of the first order smoothing result in the parameter regime studied
and that for sufficiently large Reynolds numbers the Strouhal number,
describing the ratio of correlation to turnover times, is roughly 1.5. This is
consistent with the closure model based on the minimal tau-approximation which
produces a reasonable fit to the simulation data for similar Strouhal numbers.
In the cases where rotation is present, separating the diffusive and
nondiffusive components of the stress turns out to be challenging but taking
the results at face value, we can obtain nondiffusive contributions of the
order of 0.1 times the turbulent viscosity. We also find that the simple
closure model is able to reproduce most of the qualitative features of the
numerical results provided that the Strouhal number is of the order of unity.Comment: 19 pages, 12 figures, published versio
Water and ammonia abundances in S140 with the Odin satellite
We have used the Odin satellite to obtain strip maps of the ground-state
rotational transitions of ortho-water and ortho-ammonia, as well as CO(5-4) and
13CO(5-4) across the PDR, and H218O in the central position. A physi-chemical
inhomogeneous PDR model was used to compute the temperature and abundance
distributions for water, ammonia and CO. A multi-zone escape probability method
then calculated the level populations and intensity distributions. These
results are compared to a homogeneous model computed with an enhanced version
of the RADEX code. H2O, NH3 and 13CO show emission from an extended PDR with a
narrow line width of ~3 kms. Like CO, the water line profile is dominated by
outflow emission, however, mainly in the red wing. The PDR model suggests that
the water emission mainly arises from the surfaces of optically thick, high
density clumps with n(H2)>10^6 cm^-3 and a clump water abundance, with respect
to H2, of 5x10^-8. The mean water abundance in the PDR is 5x10^-9, and between
~2x10^-8 -- 2x10^-7 in the outflow derived from a simple two-level
approximation. Ammonia is also observed in the extended clumpy PDR, likely from
the same high density and warm clumps as water. The average ammonia abundance
is about the same as for water: 4x10^-9 and 8x10^-9 given by the PDR model and
RADEX, respectively. The similarity of water and ammonia PDR emission is also
seen in the almost identical line profiles observed close to the bright rim.
Around the central position, ammonia also shows some outflow emission although
weaker than water in the red wing. Predictions of the H2O(110-101) and
(111-000) antenna temperatures across the PDR are estimated with our PDR model
for the forthcoming observations with the Herschel Space Observatory.Comment: 13 pages, 14 figures, 10 tables. Accepted for publication in
Astronomy & Astrophysics 14 November 200
The design and function of birdsâ nests
All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is
becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract
a mate, nests contain eggs and/or offspring, thereby suggesting a direct tradeoff between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects
of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birdsâ nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birdsâ nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s
The molecular disk surrounding the protostellar binary L1551 IRS5
The inner three arcminutes surrounding the Class 0/1 binary protostar L1551 IRS5 have been observed using the J=1â0 transitions of the HCO+, H13CO+, 12CO and 13CO molecular species. Since the line core of HCO+ is self reversed over a substantial part of our map, observations of isotopomers such as H13CO+ are required in order to estimate the mass of the molecular gas in the immediate vicinity of IRS5. Our observations demonstrate the presence of a large ( ~ 7000 AU radius) dense, possibly rotating, molecular disk with a mass of a few Mâ oriented perpendicular to the major axis of an extended molecular outflow. The disk is surrounded by an envelope with a radius of ~ 10 000 AU that contains two massive (each ~ 1 Mâ) clumps. One of these features appears to be kinematically disconnected from both the disk and the molecular outflow
From Motion to Emotion : Accelerometer Data Predict Subjective Experience of Music
Music is often discussed to be emotional because it reflects expressive movements in audible form. Thus, a valid approach to measure musical emotion could be to assess movement stimulated by music. In two experiments we evaluated the discriminative power of mobile-device generated acceleration data produced by free movement during music listening for the prediction of ratings on the Geneva Emotion Music Scales (GEMS-9). The quality of prediction for different dimensions of GEMS varied between experiments for tenderness (R12(first experiment) = 0.50, R22(second experiment) = 0.39), nostalgia (R12 = 0.42, R22 = 0.30), wonder (R12 = 0.25, R22 = 0.34), sadness (R12 = 0.24, R22 = 0.35), peacefulness (R12 = 0.20, R22 = 0.35) and joy (R12 = 0.19, R22 = 0.33) and transcendence (R12 = 0.14, R22 = 0.00). For others like power (R12 = 0.42, R22 = 0.49) and tension (R12 = 0.28, R22 = 0.27) results could be almost reproduced. Furthermore, we extracted two principle components from GEMS ratings, one representing arousal and the other one valence of the experienced feeling. Both qualities, arousal and valence, could be predicted by acceleration data, indicating, that they provide information on the quantity and quality of experience. On the one hand, these findings show how music-evoked movement patterns relate to music-evoked feelings. On the other hand, they contribute to integrate findings from the field of embodied music cognition into music recommender systems
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