12,322 research outputs found
Examination of actin and microtubule dependent APC localisations in living mammalian cells
Abstract (provisional)
Background
The trafficking of the adenomatous polyposis coli (APC) tumour suppressor protein in mammalian cells is a perennially controversial topic. Immunostaining evidence for an actin-associated APC localisation at intercellular junctions has been previously presented, though live imaging of mammalian junctional APC has not been documented.
Results
Using live imaging of transfected COS-7 cells we observed intercellular junction-associated pools of GFP-APC in addition to previously documented microtubule-associated GFP-APC and a variety of minor localisations. Although both microtubule and junction-associated populations could co-exist within individual cells, they differed in their subcellular location, dynamic behaviour and sensitivity to cytoskeletal poisons. GFP-APC deletion mutant analysis indicated that a protein truncated immediately after the APC armadillo repeat domain retained the ability to localise to adhesive membranes in transfected cells. Supporting this, we also observed junctional APC immunostaining in cultures of human colorectal cancer cell line that express truncated forms of APC.
Conclusions
Our data indicate that APC can be found in two spatially separate populations at the cell periphery and these populations can co-exist in the same cell. The first localisation is highly dynamic and associated with microtubules near free edges and in cell vertices, while the second is comparatively static and is closely associated with actin at sites of cell-cell contact. Our imaging confirms that human GFP-APC possesses many of the localisations and behaviours previously seen by live imaging of Xenopus GFP-APC. However, we report the novel finding that GFP-APC puncta can remain associated with the ends of shrinking microtubules. Deletion analysis indicated that the N-terminal region of the APC protein mediated its junctional localisation, consistent with our observation that truncated APC proteins in colon cancer cell lines are still capable of localising to the cell cortex. This may have implications for the development of colorectal cancer
A Renormalization Group Analysis of Coupled Superconducting and Stripe Order in 1+1 Dimensions
In this paper we perform a renormalization group analysis on the 1+1
dimensional version of an effective field theory (previously proposed by
Dung-Hai Lee, cond-mat/011393) describing (quantum) fluctuating stripe and
superconductor orders. We find four possible phases corresponding to stripe
order/disorder combined with superconducting order/disorder.Comment: 8 pages, 3 figures, revte
Ultra High Resolution Transmission Electron Microscopy of Matrix Mineral Grains in CM Chondrites: Preaccretionary or Parent Body Aqueous Processing?
CM chondrites are highly hydrated
meteorites associated with a parent asteroid that has
experienced significant aqueous processing. The meteoritic
evidence indicates that these non-differentiated
asteroids are formed by fine-grained minerals embedded
in a nanometric matrix that preserves chemical
clues of the forming environment. So far there are two
hypothesis to explain the presence of hydrated minerals
in the content of CM chondrites: one is based on textural
features in chondrule-rim boundaries [1-3], and
the other ‘preaccretionary’ hypothesis proposes the
incorporation of hydrated phases from the protoplanetary
disk [4-6]. The highly porous structure of these
chondrites is inherited from the diverse materials present
in the protoplanetary disk environment. These
bodies were presumably formed by low relative velocity
encounters that led to the accretion of silicate-rich
chondrules, refractory Ca- and Al-rich inclusions
(CAIs), metal grains, and the fine-grained materials
forming the matrix. Owing to the presence of significant
terrestrial water in meteorite finds [7], here we
have focused on two CM chondrite falls with minimal
terrestrial processing: Murchison and Cold Bokkeveld.
Anhydrous carbonaceous chondrite matrices are usually
represented by highly chemically unequilibrated
samples that contain distinguishable stellar grains.
Other chondrites have experienced hydration and
chemical homogeneization that reveal parent body
processes. We have studied CM chondrites because
these meteorites have experienced variable hydration
levels [8-10]. It is important to study the textural effects
of aqueous alteration in the main minerals to
decipher which steps and environments promote bulk
chemistry changes, and create the distinctive alteration
products. It is thought that aqueous alteration has particularly
played a key role in modifying primordial
bulk chemistry, and homogenizing the isotopic content
of fine-grained matrix materials [7, 11, 12]. Fortunately,
the mineralogy produced by parent-body and terrestrial
aqueous alteration processes is distinctive [5, 11]
Stripe order at low temperatures in La{2-x}Sr{x}NiO4 for 1/3 < x < 1/2
Stripe order in La{2-x}Sr{x}NiO4 beyond x = 1/3 was studied with neutron
scattering technique. At low temperatures, all the samples exhibit hole stripe
order. Incommensurability \epsilon of the stripe order is approximately linear
in the hole concentration n_h = x + 2\delta up to x = 1/2, where \delta denotes
the off-stoichiometry of oxygen atoms. The charge and spin ordering
temperatures exhibit maxima at n_h = 1/3, and both decrease beyond n_h > 1/3.
For 1/3 < n_h < 1/2, the stripe ordering consists of the mixture of the
\epsilon = 1/3 stripe order and the n_h = 1/2 charge/spin order.Comment: REVTeX, 4 pages, 4 figure
Time perspective, depression, and substance misuse among the homeless
Using the Zimbardo Time Perspective Inventory (ZTPI; P. G. Zimbardo & J. N. Boyd, 1999), the authors found that homeless people, in comparison with a control group, had a significantly more negative outlook concerning their past and present as evinced by high Past-Negative and Present-Fatalistic scores and low Past-Positive scores on the ZTPI. However, the homeless individuals were almost indistinguishable from control participants on measures of Present-Hedonism and Future thinking. The homeless individuals had significantly higher levels of depression, with 31 out of 50 (62%) reaching criteria for probable depression. However, this finding was unrelated to their atypical time perspective. There was no significant relation between substance misuse and time perspective. Despite their current difficulties, including depression and drug abuse, the homeless individuals maintained a propensity toward future thinking characterized by striving to achieve their goals.
Application of Digital Anti-Coincidence Counting Method for Primary Activity Determination of 59Fe
As a radiopharmaceutical, the use of 59Fe is classified as a high pharmaceutical risk product. Therefore, a standard reference for activity measurement of 59Fe is necessary to ensure its metrological aspect. This paper describes an alternative method for primary activity determination of 59Fe for establishing a standard reference. The 59Fe solution was prepared using two different cocktails and measured by the 4pb(LS)-g counting system using a digital anti-coincidence counting method with emulated live-time of the extending dead-time. A final activity results at the reference time for the two samples series are (473.32± 2.55) kBq/g and (477.14 ± 2.42) kBq/g with quoted uncertainty evaluated at k = 1. The final activity was compared to the value obtained from the other two coincidence counting method and found to be in a good agreement within its uncertainty value
Ancient Martian Floods in a Plausible Variable Climatic Environment as Revealed from the Sequential Growth of Allan Hills 84001 Carbonate Globules
No abstract available
Charged stripes from alternating static magnetic field
We motivate and perform a calculation of the energy of a cold fluid of
charged fermions in the presence of a striped magnetic background. We find that
a non-trivial value for the doping density on the walls is preferredComment: RevTeX, 3 pages, 3 encapsulated PostScript figure
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