Biomedical subjects

Etsuko Watanabe

Publications and source records attributed to Etsuko Watanabe.

7 recordsLinked to original sources

PubMed2004

Photoreceptor ubiquitination by COP1 E3 ligase desensitizes phytochrome A signaling.

Desensitization of activated receptors is an important mechanism for terminating signal transduction. Here we show that phytochrome (phy) A, a predominant photoreceptor for seedling deetiolation, colocalizes in nuclear bodies with CONSTITUTIVELY PHOTOMORPHOGENIC (COP) 1, a RING motif-containing E3 ligase. The phyA PAS domain interacts with the COP1 WD40 domain. Both the Pr and the Pfr forms of phyA, as well as the PHYA apoprotein, are ubiquitinated by COP1 in vitro. The phyA destruction rate is decreased in cop1 mutants and by expression of a COP1 RING motif mutant. Our results indicate that COP1 acts as an E3 ligase to regulate phyA signaling by targeting elimination of the phyA photoreceptor itself.

Arabidopsis↗

PubMed2004

Tensile properties and hardness of cast Fe-Pt magnetic alloys.

STATEMENT OF PROBLEM: There is little information about the mechanical properties of castable magnetic attachments made of iron-platinum (Fe-Pt) alloys after heat treatment. MATERIAL AND METHODS: Dumbbell-shaped tensile specimens were cast with 5 alloys: 2 types of Fe-Pt alloys for magnets and keepers, pure Ti, Ti-6Al-7Nb, and Co-Cr alloy. The tensile specimens of the Fe-Pt magnets and keepers underwent different heat treatments to obtain the appropriate properties for a magnet and a keeper. Vickers hardness was measured prior to testing. Tensile testing was conducted in a universal testing machine at a crosshead speed of 2 mm/min until failure. Ultimate tensile strength, yield strength, elongation, and modulus of elasticity were recorded. The data were analyzed using 1-way analysis of variance and the Tukey test (alpha=.05), fractured surfaces were examined using a scanning electron microscope (SEM). RESULTS: The highest tensile and yield strengths were found for Ti-6Al-7Nb, followed by Co-Cr, CP Ti, and the Fe-Pt keeper. There was no significant difference in ultimate tensile strength between the CP Ti and the Fe-Pt keeper. The lowest elongation was found for the Fe-Pt magnet (2.8%), whereas the Fe-Pt keeper had the highest elongation (14.0%). The Fe-Pt magnet and keeper had similar modulus of elasticity values. The hardness of the cast Fe-Pt magnets was the highest among the metals tested. SEM micrographs of the Fe-Pt keepers showed a microstructure with ductile dimple fractures, whereas the Fe-Pt magnets were characterized by brittle fractures at the grain boundaries. CONCLUSIONS: The mechanical properties of the cast Fe-Pt keepers were similar to those of the cast pure Ti. The Fe-Pt magnets were extremely hard and brittle.

Analysis of Variance↗

PubMed2004

An ER-localized form of PV72, a seed-specific vacuolar sorting receptor, interferes the transport of an NPIR-containing proteinase in Arabidopsis leaves.

Putative vacuolar sorting receptors that bind to the vacuolar targeting signals have been found in various plants; pumpkin PV72, pea BP-80 and Arabidopsis AtELP. PV72 is a seed-specific receptor that is predicted to sort seed storage proteins to protein storage vacuoles. Analysis by surface plasmon resonance showed that the lumenal domain of PV72 bound to an NPIR (a typical vacuolar targeting signal)-containing peptide of the precursor of a cysteine proteinase, AtALEU, in the presence of Ca(2+) (K(D) = 0.1 micro M). To elucidate the receptor-dependent transport of vacuolar proteins in plant cells, we produced transgenic Arabidopsis plants that expressed a fusion protein (PV72-HDEL) composed of the lumenal domain of PV72 and an endoplasmic reticulum (ER)-retention signal, HDEL. The expression of PV72-HDEL induced the accumulation of the AtALEU precursor. The accumulation level of the AtALEU precursor was dependent on that of PV72-HDEL. In contrast, it did not induce the accumulation of a precursor of another cysteine proteinase, RD21, which contains no NPIR. Detailed subcellular localization revealed that both the AtALEU precursor and PV72-HDEL accumulated in the ER fraction. We found that most of the AtALEU precursor molecules formed a complex with PV72-HDEL. The AtALEU precursor might be trapped by PV72-HDEL in the ER and not transported to the vacuoles. This in-planta analysis supports the hypothesis that an Arabidopsis homolog of PV72 functions as a sorting receptor for the NPIR-containing proteinase. The overall results suggest that vacuolar sorting receptors for the protein storage vacuoles and the lytic vacuoles share the similar recognition mechanism for a vacuolar targeting signal.

Arabidopsis↗

PubMed2003

Surface changes induced by fluoride prophylactic agents on titanium-based orthodontic wires.

This study investigated the effect of fluoride prophylactic agents on the surfaces of titanium-based orthodontic wires. Four types of titanium-based orthodontic wires (2 nickel-titanium alloy wires [nickel-titanium and copper-nickel-titanium] and 2 beta-titanium alloy wires [titanium-molybdenum and titanium-niobium], all from Ormco, Glendora, Calif) with similar sizes were prepared and immersed in 5 fluoride prophylactic agents (2 acidulated phosphate fluoride agents [Nupro APF (Dentsply International, York, Pa) and Florentine III (Confi-Dental, Louisville, Colo)], 1 neutral agent [Neupro Neutral (Dentsply International)] and 2 stannous fluoride agents [Florentine II (Confi-Dental) and Perio-Med (Omni International, Warrenton, Va)]) for 5 minutes, 1 hour, and 24 hours. After immersion, average surface roughness and color changes were evaluated. The surface changes were observed with a scanning electron microscope. The average surface roughness data were statistically analyzed by analysis of variance and Tukey post hoc test at a significance level of alpha = 0.05. There were no significant differences in average surface roughness value among fluoride solutions or orthodontic wires, except for the titanium-molybdenum wire, which showed significantly (P <.05) higher average surface roughness values after immersion in Nupro APF for 24 hours. The results suggested that a few applications of acidulated phosphate fluoride agents might change the surface color of the beta-titanium alloy wires, particularly the titanium-molybdenum wire, which contains a large amount (about 80%) of titanium.

Acidulated Phosphate Fluoride↗

PubMed2003

Shear bond strengths of laboratory-cured prosthetic composite to primed metal surfaces.

PURPOSE: To examine the effect of using metal primers to enhance the shear bond strength of a laboratory-cured prosthetic composite to cast metal surfaces. METHODS: Cast discs (10 mm diam., 2.5 mm thick) were prepared from high gold-containing alloy, Ag-Au-Pd alloy, and commercially pure titanium (CP Ti). After casting, the surfaces of the discs were sandblasted with 50 microm Al2O3. Each surface to be bonded was treated with one of four types of metal primers: V-Primer (VP), Metal Primer II (MP), Cesead II Opaque Primer (OP), and an experimental primer (EP). Specimens without primer were prepared as controls. After tape with a circular hole (5 mm diam.) was fixed on the disc surface to define the bonding area, the opaque resin was applied within the hole and light-cured according to the manufacturer's instructions. After polymerization of the opaque resin, a layer (1 mm thick) of each dentin and enamel resin was applied separately using Teflon matrices (6 mm I. D.). The bonded specimens were immersed in 37 degrees C water for 24 hours (baseline) and were then thermocycled for 5,000 and 10,000 cycles. The shear bond strengths were determined at the baseline and after thermocycling. The results were analyzed using ANOVA/Bonferroni/Dunn's test (c = 0.05). RESULTS: There were no statistical differences (P > 0.05) in the shear bond strength among surface applications for the gold alloy at the baseline. After 5,000 and 10,000 thermocycles, the gold alloy specimens primed with OP and EP primers exhibited higher bond strength compared to those primed with VP and MP primers, and the non-primed control specimens. The Ag-Au-Pd alloy specimens tended to be similar to the gold alloy specimens after each number of thermocycles. The shear bond strengths to CP Ti primed with OP and EP were significantly (P < 0.05) higher than the others after 5,000 and 10,000 thermocycles.

Analysis of Variance↗

PubMed2002

A vacuolar sorting receptor PV72 on the membrane of vesicles that accumulate precursors of seed storage proteins (PAC vesicles).

A novel vesicle, referred to as a precursor-accumulating (PAC) vesicle, mediates the transport of storage protein precursors to protein storage vacuoles in maturing pumpkin seeds. PV72, a type I integral membrane protein with three repeats of epidermal growth factor, was found on the membrane of the PAC vesicles. PV72 had an ability to bind to pro2S albumin, a storage protein precursor, in a Ca(2+)-dependent manner, via the C-terminal region of pro2S albumin, which was found to function as a vacuolar targeting signal. This implies that PV72 is a vacuolar sorting receptor of the storage protein. PV72 was specifically and transiently accumulated at the middle stage of seed maturation in association with the synthesis of storage proteins. Subcellular fractionation showed that PV72 was also accumulated in the microsomal fraction. A fusion protein consisting of GFP and the transmembrane domain and the cytosolic tail of PV72 was localized in Golgi complex. PV72 in the isolated PAC vesicles had a complex type of oligosaccharide, indicating that PV72 passed though the Golgi complex. These results suggest that PV72 is recycled between PAC vesicles and Golgi complex/post-Golgi compartments. PV72 appears to be responsible for recruiting pro2S albumin molecules from the Golgi complex to the PAC vesicles.

Arabidopsis↗

PubMed2001

Calcium-mediated association of a putative vacuolar sorting receptor PV72 with a propeptide of 2S albumin.

PV72, a type I membrane protein with three epidermal-growth factor (EGF)-like motifs, was found to be localized on the membranes of the precursor-accumulating (PAC) vesicles that accumulated precursors of various seed storage proteins. To clarify the function of PV72 as a sorting receptor, we expressed four modified PV72s and analyzed their ability to bind the internal propeptide (the 2S-I peptide) of pro2S albumin by affinity chromatography and surface plasmon resonance. The recombinant PV72 specifically bound to the 2S-I peptide with a K(D) value of 0.2 microm, which was low enough for it to function as a receptor. The EGF-like motifs modulated the Ca(2+)-dependent conformational change of PV72 to form a functional pocket for the ligand binding. The binding of Ca(2+) stabilizes the receptor-ligand complex even at pH 4.0. The association and dissociation of PV72 with the ligand is modulated by the Ca(2+) concentration (EC(50) value = 40 microm) rather than the environmental pH. Overall results suggest that Ca(2+) regulates the vacuolar sorting mechanism in higher plants.

2S Albumins, Plant↗