480 research outputs found
Seasonal Trends in Honeydew-Foraging Strategies in the Red Wood Ant, Formica yessensis (Hymenoptera: Formicidae)
The red wood ants Formica yessensis are known to support super colonies comprising thousands of nests, contain approximately 360 million workers, and over one million queens along the Ishikari coast, Hokkaido, northern Japan. Previous studies revealed the abundance of prey insects in Ishikari is very limited; suggesting that honeydew collected from aphids is a critical resource for F. yessensis. Furthermore, several reports suggested F. yessensis performs a generation change between late July and early August at the study site. The present study examined seasonal changes in F. yessensis honeydewforaging workers and specifically addressed the following: information transfer to aphid trees; fidelity to aphid trees; and changes in F. yessensis body size. Observation of marked ants revealed that information transfer to aphid trees occurred by direct guidance from older to younger foragers. Seasonal sampling indicated that honeydew-foraging ant body size decreased with progressive seasons. Large gaster coefficient of variation (CV) values showed two honeydew-foraging ant worker types were present in the super colony. The results revealed older foragers exhibited a large body size, which decreased in number towards autumn. Younger workers exhibited a smaller body size, and initiated honeydew foraging after emergence. Honeydew is a critical resource, therefore information transfer to aphid tree location, and honeydew-foraging were the first priority tasks observed in F. yessensis at the study site.
Towards Better Ad Experience: Click Prediction Leveraging Sequential Networks Derived Specifically From User Search Behaviors
conference pape
Predictor for Histological Microvascular Invasion of Hepatocellular Carcinoma: A Lesson from 229 Consecutive Cases of Curative Liver Resection.
BACKGROUND: Microscopic vascular invasion is an important risk factor for recurrent hepatocellular carcinoma (HCC), even after curative liver resection or orthotopic liver transplantation. To predict microscopic portal venous invasion, the following two questions were examined retrospectively: Is it possible to detect microvascular invasion preoperatively? What are the characteristics of a group of early HCC recurrences even with no microvascular invasion? METHODS: Study 1 included 229 patients with HCC who underwent curative liver resection between 1991 and 2008; 127 had HCC without microscopic portal venous invasion, and 52 had HCC with microscopic portal venous invasion (MPVI). These two distinct groups were analyzed with regard to various clinicopathologic factors. Subsequently, we specifically investigated if HCCs 5 cm, the macroscopic appearance of HCC, and high levels of preoperative des-gamma-carboxyprothrombin are significant prognostic factors in identifying microvascular invasion of HCC. The strongest predictor of early recurrence (within 2 years) was the serum alpha-fetoprotein level in patients without clear microvascular invasion. CONCLUSIONS: Tumor size, macroscopic appearance, and high tumor marker levels are important elements in identifying the group of patients with a low HCC recurrence rate after curative liver resection
Telophase Correction Refines Division Orientation in Stratified Epithelia
During organogenesis, precise control of spindle orientation balances proliferation and differentiation. In the developing murine epidermis, planar and perpendicular divisions yield symmetric and asymmetric fate outcomes, respectively. Classically, division axis specification involves centrosome migration and spindle rotation, events occurring early in mitosis. Here, we identify a novel orientation mechanism which corrects erroneous anaphase orientations during telophase. The directionality of reorientation correlates with the maintenance or loss of basal contact by the apical daughter. While the scaffolding protein LGN is known to determine initial spindle positioning, we show that LGN also functions during telophase to reorient oblique divisions toward perpendicular. The fidelity of telophase correction also relies on the tension-sensitive adherens junction proteins vinculin, α-E-catenin, and afadin. Failure of this corrective mechanism impacts tissue architecture, as persistent oblique divisions induce precocious, sustained differentiation. The division orientation plasticity provided by telophase correction may enable progenitors to adapt to local tissue needs
Practical access to planar chiral 1,2-(α-Ketotetramethylene)- ferrocene by non-enzymatic kinetic resolution and conclusive confirmation of its absolute configuration
The asymmetric transfer hydrogenation (ATH) of racemic 1,2-(α-ketotetramethylene)ferrocene using the [N-(tosyl)-1,2-diphenylethylendiamine]ruthenium(II) complex [TsDPEN-Ru(II)] as catalyst takes place with a high level of kinetic resolution to deliver the ketone in up to 99% ee. The X-ray crystallographic structure of a derivative of the alcohol co-product serves to confirm conclusively both the absolute configuration of 1,2-(α-ketotetramethylene)ferrocene and the endo-reduction selectivity
MURC/Cavin-4 and cavin family members form tissue-specific caveolar complexes
Polymerase I and transcript release factor (PTRF)/Cavin is a cytoplasmic protein whose expression is obligatory for caveola formation. Using biochemistry and fluorescence resonance energy transfer–based approaches, we now show that a family of related proteins, PTRF/Cavin-1, serum deprivation response (SDR)/Cavin-2, SDR-related gene product that binds to C kinase (SRBC)/Cavin-3, and muscle-restricted coiled-coil protein (MURC)/Cavin-4, forms a multiprotein complex that associates with caveolae. This complex can constitutively assemble in the cytosol and associate with caveolin at plasma membrane caveolae. Cavin-1, but not other cavins, can induce caveola formation in a heterologous system and is required for the recruitment of the cavin complex to caveolae. The tissue-restricted expression of cavins suggests that caveolae may perform tissue-specific functions regulated by the composition of the cavin complex. Cavin-4 is expressed predominantly in muscle, and its distribution is perturbed in human muscle disease associated with Caveolin-3 dysfunction, identifying Cavin-4 as a novel muscle disease candidate caveolar protein
Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures
Topological insulators are characterized by a nontrivial band topology driven
by the spin-orbit coupling. To fully explore the fundamental science and
application of topological insulators, material realization is indispensable.
Here we predict, based on tight-binding modeling and first-principles
calculations, that bilayers of perovskite-type transition-metal oxides grown
along the [111] crystallographic axis are potential candidates for
two-dimensional topological insulators. The topological band structure of these
materials can be fine-tuned by changing dopant ions, substrates, and external
gate voltages. We predict that LaAuO bilayers have a
topologically-nontrivial energy gap of about 0.15 eV, which is sufficiently
large to realize the quantum spin-Hall effect at room temperature. Intriguing
phenomena, such as fractional quantum Hall effect, associated with the
nearly-flat topologically-nontrivial bands found in systems are also
discussed.Comment: Main text 11 pages with 4 figures and 1 table. Supplementary
materials 4 pages with 2 figure
A PDZ-containing Scaffold Related to the Dystrophin Complex at the Basolateral Membrane of Epithelial Cells
Membrane scaffolding complexes are key features of many cell types, serving as specialized links between the extracellular matrix and the actin cytoskeleton. An important scaffold in skeletal muscle is the dystrophin-associated protein complex. One of the proteins bound directly to dystrophin is syntrophin, a modular protein comprised entirely of interaction motifs, including PDZ (protein domain named for PSD-95, discs large, ZO-1) and pleckstrin homology (PH) domains. In skeletal muscle, the syntrophin PDZ domain recruits sodium channels and signaling molecules, such as neuronal nitric oxide synthase, to the dystrophin complex. In epithelia, we identified a variation of the dystrophin complex, in which syntrophin, and the dystrophin homologues, utrophin and dystrobrevin, are restricted to the basolateral membrane. We used exogenously expressed green fluorescent protein (GFP)-tagged fusion proteins to determine which domains of syntrophin are responsible for its polarized localization. GFP-tagged full-length syntrophin targeted to the basolateral membrane, but individual domains remained in the cytoplasm. In contrast, the second PH domain tandemly linked to a highly conserved, COOH-terminal region was sufficient for basolateral membrane targeting and association with utrophin. The results suggest an interaction between syntrophin and utrophin that leaves the PDZ domain of syntrophin available to recruit additional proteins to the epithelial basolateral membrane. The assembly of multiprotein signaling complexes at sites of membrane specialization may be a widespread function of dystrophin-related protein complexes
Anti-HIV-1 activity of anionic polymers: a comparative study of candidate microbicides
BACKGROUND: Cellulose acetate phthalate (CAP) in soluble form blocks coreceptor binding sites on the virus envelope glycoprotein gp120 and elicits gp41 six-helix bundle formation, processes involved in virus inactivation. CAP is not soluble at pH < 5.5, normal for microbicide target sites. Therefore, the interaction between insoluble micronized CAP and HIV-1 was studied. Carbomer 974P/BufferGel; carrageenan; cellulose sulfate; dextran/dextrin sulfate, poly(napthalene sulfonate) and poly(styrene-4-sulfonate) are also being considered as anti-HIV-1 microbicides, and their antiviral properties were compared with those of CAP. METHODS: Enzyme linked immunosorbent assays (ELISA) were used to (1) study HIV-1 IIIB and BaL binding to micronized CAP; (2) detect virus disintegration; and (3) measure gp41 six-helix bundle formation. Cells containing integrated HIV-1 LTR linked to the β-gal gene and expressing CD4 and coreceptors CXCR4 or CCR5 were used to measure virus infectivity. RESULTS: 1) HIV-1 IIIB and BaL, respectively, effectively bound to micronized CAP. 2) The interaction between HIV-1 and micronized CAP led to: (a) gp41 six-helix bundle formation; (b) virus disintegration and shedding of envelope glycoproteins; and (c) rapid loss of infectivity. Polymers other than CAP, except Carbomer 974P, elicited gp41 six-helix bundle formation in HIV-1 IIIB but only poly(napthalene sulfonate), in addition to CAP, had this effect on HIV-1 BaL. These polymers differed with respect to their virucidal activities, the differences being more pronounced for HIV-1 BaL. CONCLUSIONS: Micronized CAP is the only candidate topical microbicide with the capacity to remove rapidly by adsorption from physiological fluids HIV-1 of both the X4 and R5 biotypes and is likely to prevent virus contact with target cells. The interaction between micronized CAP and HIV-1 leads to rapid virus inactivation. Among other anionic polymers, cellulose sulfate, BufferGel and aryl sulfonates appear most effective in this respect
Synthesis and applications of MOF - derived porous nanostructures
Metal organic frameworks (MOFs) represent a class of porous material which is formed by strong bonds between metal ions and organic linkers. By careful selection of constituents, MOFs can exhibit very high surface area, large pore volume, and excellent chemical stability. Research on synthesis, structures and properties of various MOFs has shown that they are promising materials for many applications, such as energy storage, gas storage, heterogeneous catalysis and sensing. Apart from direct use, MOFs have also been used as support substrates for nanomaterials or as sacrificial templates/precursors for preparation of various functional nanostructures. In this review, we aim to present the most recent development of MOFs as precursors for the preparation of various nanostructures and their potential applications in energy-related devices and processes. Specifically, this present survey intends to push the boundaries and covers the literatures from the year 2013 to early 2017, on supercapacitors, lithium-ion batteries, electrocatalysts, photocatalyst, gas sensing, water treatment, solar cells, and carbon dioxide capture. Finally, an outlook in terms of future challenges and potential prospects towards industrial applications are also discussed
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