Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3 ؉ ) transfectant cells from a GD3-negative (GD3 ؊ ) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3 ؉ cells showed markedly increased cell growth and invasive characteristics. Two bands that underwent stronger tyrosine phosphorylation in GD3 ؉ cell lines than in controls after treatment with FCS were found with molecular masses of 130 and 68 kDa. They were identified as p130Cas and paxillin by sequential immunoprecipitation. Their roles in cell growth and invasion were analyzed with a small interfering RNA (siRNA) approach. Cell growth, as analyzed by BrdUrd uptake, was strongly suppressed in GD3 ؉ cells to near the levels of GD3 ؊ cells when treated with siRNA for p130Cas but not when treated with siRNA for paxillin. However, treatment with siRNAs of either p130Cas or paxillin resulted in the marked suppression of the invasive activity of GD3 ؉ cells almost to the levels of control cells. These results suggested that these two molecules function as effectors of GD3-mediated signaling, leading to such malignant properties as rapid cell growth and invasion.small interfering RNA ͉ sialyltransferase ͉ phosphorylation

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Piezoelectricity in βphase poly(vinylidene fluoride) having a ''singlecrystal'' orientationPoly͑vinylidene fluoride͒ ͑PVDF͒ was crystallized under high pressures on the basis of the pressure-temperature ( P-T) phase diagram obtained recently, and piezoelectric and ferroelectric properties of the resulting films were evaluated. Crystallization in the metastable hexagonal phase appearing at high pressure and temperature below the triple point yielded a film comprising extended chain lamellar crystals of a mixture of ␤ and ␥ forms, the latter of which is transformed into ␤ form by poling at an elevated temperature ͑120°C͒. The poled film exhibits strong piezoelectric effect persistent up to the melting temperature ͑205°C͒. The electromechanical coupling factor k t for the thickness extensional piezoelectric effect is 0.27 at 25°C, the largest value ever found in PVDF. The results of studies on morphology, structure, and thermal properties are also described.

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Field-induced phase transformation and thermally induced phase transition in vinylidene fluoride (VDF) and trifluoroethylene copolymers with VDF content higher than 82 mol% and their ferroelectric and piezoelectric properties have been studied by means of x-ray diffraction, DSC, D-E hysteresis, and piezoelectric resonance. It is found that copolymers with VDF content ranging from ∼82 to 90 mol% crystallize under ordinary pressure into thick lamellar single crystals composed of a mixture of α, β, and possibly γ phases. Application of a strong ac electric field transforms these mixed phase crystals into β-phase crystals completely. The β-phase crystals are ferroelectric and exhibit strong piezoelectric activity stable up to the melting temperature (160–180  °C depending on VDF content); the Curie point coincides with the melting point. Unpoled, mixed phase film has a paraelectric or rotational phase below the melting temperature, in which thick lamellar single crystals are grown extensively, whereas β-phase film prepared by mechanical drawing has no paraelectric phase below the melting point. Definite ferroelectric-to-paraelectric phase transition in P(VDF-TrFE) is inferred to occur only in thick lamellar crystals grown in the paraelectric phase. A phase diagram of P(VDF-TrFE) is described.

Diverse cellular processes such as autophagic protein degradation require phosphoinositide signaling in eukaryotic cells. In the methylotrophic yeast Pichia pastoris, peroxisomes can be selectively degraded via two types of pexophagic pathways, macropexophagy and micropexophagy. Both involve membrane fusion events at the vacuolar surface that are characterized by internalization of the boundary domain of the fusion complex, indicating that fusion occurs at the vertex. Here, we show that PpAtg24, a molecule with a phosphatidylinositol 3-phosphate-binding module (PX domain) that is indispensable for pexophagy, functions in membrane fusion at the vacuolar surface. CFP-tagged PpAtg24 localized to the vertex and boundary region of the pexophagosome-vacuole fusion complex during macropexophagy. Depletion of PpAtg24 resulted in the blockage of macropexophagy after pexophagosome formation and before the fusion stage. These and other results suggest that PpAtg24 is involved in the spatiotemporal regulation of membrane fusion at the vacuolar surface during pexophagy via binding to phosphatidylinositol 3-phosphate, rather than the previously suggested function in formation of the pexophagosome.