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Biomedical subjects

Kimiko Yamamoto

Publications and source records attributed to Kimiko Yamamoto.

26 records · Page 2Linked to original sources
PubMed2003

Novel gene encoding a Ca2+-binding protein and under hexokinase-dependent sugar regulation.

A cDNA encoding a predicted 15-kDa protein was earlier isolated from sugar-induced genes in rice embryos (Oryza sativa L.) by cDNA microarray analysis. Here we report that this cDNA encodes a novel Ca2+-binding protein, named OsSUR1 (for Oryza sativa sugar-up-regulated-1). The recombinant OsSUR1 protein expressed in Escherichia coli had 45Ca2+-binding activity. Northern analysis showed that the OsSUR1 gene was expressed mainly in the internodes of mature plants and in embryos at an early stage of germination. Expression of the OsSUR1 gene was induced by sugars that could serve as substrates of hexokinase, but expression was not repressed by Ca2+ signaling inhibitors, calmodulin antagonists and inhibitors of protein kinase or protein phosphatase. These results suggested that Os-SUR1 gene expression was stimulated by a hexokinase-dependent pathway not mediated by Ca2+.

Amino Acid Motifs↗
PubMed2003

Global analysis of shear stress-responsive genes in vascular endothelial cells.

DNA microarray gene expression analysis was conducted in human umbilical vein endothelial cells (HUVECs) and coronary artery endothelial cells (HCAECs) exposed to laminar or turbulent shear stress. Approximately 3% of the total 5600 gene in HUVECs and HCAECs increased their expression more than two-fold or decreased it to less than half the static control in response to an arterial level of laminar shear stress (15 dynes/cm(2) for 24 hours). The proportions of shear-stress-responsive genes decreased to around 2% under the venous level of laminar shear stress (1.5 dynes/cm(2)) in both cell lines. Turbulent shear stress of 1.5 dynes/cm(2) altered the expression of 1.1% of all genes in the HCAECs. Laminar shear stress, but not turbulent shear stress, decreased the expression of a number of genes involved in DNA synthesis and the cell cycle in both HUVECs and HCAECs. Clustering analysis showed a variety of temporal profiles of gene expression in HUVECs exposed to laminar shear stress of 15 dynes/cm(2) for 3, 6, 12, 24, and 48 hours. Turbulent shear stress affected expression of many genes that play a role in vascular remodeling, including genes encoding plasminogen activators and their inhibitor, endothelin-1, transforming growth factor-beta, collagen type IV, and ephrin A1.

Arteriosclerosis↗
PubMed2002

The genome sequence and structure of rice chromosome 1.

The rice species Oryza sativa is considered to be a model plant because of its small genome size, extensive genetic map, relative ease of transformation and synteny with other cereal crops. Here we report the essentially complete sequence of chromosome 1, the longest chromosome in the rice genome. We summarize characteristics of the chromosome structure and the biological insight gained from the sequence. The analysis of 43.3 megabases (Mb) of non-overlapping sequence reveals 6,756 protein coding genes, of which 3,161 show homology to proteins of Arabidopsis thaliana, another model plant. About 30% (2,073) of the genes have been functionally categorized. Rice chromosome 1 is (G + C)-rich, especially in its coding regions, and is characterized by several gene families that are dispersed or arranged in tandem repeats. Comparison with a draft sequence indicates the importance of a high-quality finished sequence.

Arabidopsis↗
PubMed2002

Sites of Ca(2+) wave initiation move with caveolae to the trailing edge of migrating cells.

The caveola is a membrane domain that compartmentalizes signal transduction at the cell surface. Normally in endothelial cells, groups of caveolae are found clustered along stress fibers or at the lateral margins in all regions of the cell. Subsets of these clusters appear to contain the signaling machinery for initiating Ca(2+) wave formation. Here we report that induction of cell migration, either by wounding a cell monolayer or by exposing cells to laminar shear stress, causes caveolae to move to the trailing edge of the cell. Concomitant with the relocation of the caveolae, sites of Ca(2+) wave initiation move to the same location. In as much as the relocated caveolae contain elements of the signaling machinery required for ATP-stimulated release of Ca(2+) from the ER, these results suggest that caveolae function as containers that carry this machinery to different cellular locations.

Actins↗
PubMed2002

cDNA microarray analysis of gene expression during Fe-deficiency stress in barley suggests that polar transport of vesicles is implicated in phytosiderophore secretion in Fe-deficient barley roots.

To acquire Fe from soil, graminaceous plants secrete mugineic acid family phytosiderophores (MAs) from their roots. The secretion of MAs increases in response to Fe deficiency, and shows a distinct diurnal rhythm. We used a microarray that included 8987 cDNAs of rice EST clones to examine gene expression profiles in barley roots during Fe-deficiency stress. Approximately 200 clones were identified as Fe-deficiency-inducible genes, of which seven had been identified previously. In order to meet the increased demand for methionine to produce MAs, Fe-deficiency enhances the expression of genes that participate in methionine synthesis, as well as recycling methionine through the Yang cycle. Of these 200 genes, approximately 50 exhibited different transcription levels in Fe-deficient roots at noon and at night. Northern blot analysis of time course experiments confirmed that five of these genes exhibited a diurnal change in their level of expression. The diurnal changes in the expression of these genes suggest that polar vesicle transport is involved in the diurnal secretion of MAs.

Azetidinecarboxylic Acid↗
PubMed2002

A comprehensive rice transcript map containing 6591 expressed sequence tag sites.

To determine the chromosomal positions of expressed rice genes, we have performed an expressed sequence tag (EST) mapping project by polymerase chain reaction-based yeast artificial chromosome (YAC) screening. Specific primers designed from 6713 unique EST sequences derived from 19 cDNA libraries were screened on 4387 YAC clones and used for map construction in combination with genetic analysis. Here, we describe the establishment of a comprehensive YAC-based rice transcript map that contains 6591 EST sites and covers 80.8% of the rice genome. Chromosomes 1, 2, and 3 have relatively high EST densities, approximately twice those of chromosomes 11 and 12, and contain 41% of the total EST sites on the map. Most of the EST-dense regions are distributed on the distal regions of each chromosome arm. Genomic regions flanking the centromeres for most of the chromosomes have lower EST density. Recombination frequency in these regions is suppressed significantly. Our EST mapping also shows that 40% of the assigned ESTs occupy only approximately 21% of the entire genome. The rice transcript map has been a valuable resource for genetic study, gene isolation, and genome sequencing at the Rice Genome Research Program and should become an important tool for comparative analysis of chromosome structure and evolution among the cereals.

Chromosome Mapping↗
PubMed2002

Single-cell imaging of the Ca2+ influx into bovine endothelial cells occurring in response to an alternating electric stimulus.

The electric control of cellular functions via Ca2+ was formerly suggested. From this viewpoint, the involvement of a Ca2+ channel was studied using bovine fetal arterial endothelial (BFAE) cells in which P2X4, an ATP-operated and fluid shear stress sensitive Ca2+ channel, exists predominantly. An electric stimulus (sine wave, 10 Hz, 10 VPP, 30 s) caused a marked influx of Ca2+ into BFAE cells from an extracellular solution. The magnitude of the [Ca2+]i change increased with a decrease in the frequency in the range from 100 Hz to 5 Hz. Regarding the pathway of this Ca2+ influx, single-cell imaging and an ATP depletion experiment strongly suggested the involvement of a pathway different from P2X4. This pathway was thought to be a non-specific one, because typical Ca2+ channel blockers, such as verapamil, Gd3+, and Co2+, could not inhibit the Ca2+ influx.

Animals↗