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Biomedical subjects

K Yoda

Publications and source records attributed to K Yoda.

At least 37 records · Page 2Linked to original sources
PubMed1999

Interaction among the subunits of Golgi membrane mannosyltransferase complexes of the yeast Saccharomyces cerevisiae.

Saccharomyces cerevisiae Mnn9 protein is a type II Golgi membrane protein which concerns in protein mannosylation. When solubilized by Triton X-100, it was recovered in two distinct complexes both having mannosyltransferase activity; one with Van1 protein (V-complex) and the other with Anp1, Hoc1, Mnn10, and Mnn11 proteins (A-complex). Characterization of the null mutants suggested that A-complex is also concerned in protein O-glycosylation. A-complex was more resistant than V-complex to dissociating conditions. Interaction between the lumenal domains of Van1 and Mnn9 was detected by a two-hybrid experiment. The anchor domain of Mnn9 protein could be replaced with other membrane anchors without losing the ability to form complexes similar to V- and A-complexes. Thus the lumenal domains are important to assemble these distinct complexes.

Fungal Proteins↗
PubMed1999

Comparison of 26,27-hexafluoro-1 alpha,25-dihydroxyvitamin D3 and 1 alpha,25-dihydroxyvitamin D3 on the resorption of bone explants ex vivo.

26,27-Hexafluoro-1 alpha,25-dihydroxyvitamin D3 [F6-1,25-(OH)2D3] is more potent than 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] in stimulating bone resorption in vitro and in vivo. The reason why F6-1,25(OH)2D3 is more active remains unclear. To clarify the relationship between the bone-resorbing activity of each vitamin D3 analogue and the metabolism of each analogue, in the present study, we used an ex vivo method that was established by Reynolds et al (Calcif Tissue Res, 1974, 15, 333-339). The effect of F6-1,25(OH)2D3 or 1,25(OH)2D3 on 45Ca release from parietal bones, prepared at 3, 14 and 24 h after injection of 1.9, 3.8, 7.6 or 15.2 pmol vitamin D analog/g body weight, was examined. F6-1,25(OH)2D3 was more potent than 1,25(OH)2D3 during each in vivo time period. 1,25(OH)2D3 at 3 h after the injection was more active compared to the control (no injection of 1,25(OH)2D3) but not at 14 and 24 h. The radioactivity of the bones after the injection of [3H]-F6-1,25(OH)2D3 was retained even at 24 h. In the case of [3H]-1,25(OH)2D3, the radioactivity of bones decreased with an increase in the in vivo period. In a HPLC analysis of the lipid extract of bone homogenate, [3H]-F6-1,25(OH)2D3 alone was detected at 3 h after the injection and both [3H]-F6-1,25(OH)2D3 and [3H]-26,27-hexafluoro-1 alpha, 23S,25-trihydroxyvitamin D3 [F6-1,23,25(OH)3D3] were detected at 14 and 24 h after the injection. [3H]-1,25(OH)2D3 was highly detected at 3 h after the injection, but it decreased with an increase in the in vivo period. In the ex vivo test, the activity of F6-1,23,25(OH)3D3 was less than that of F6-1,25(OH)2D3 but similar to that of 1,25(OH)2D3. The present study indicates that F6-1,25(OH)2D3 is more active and more long-lasting than 1,25(OH)2D3 in the ex vivo method. A higher potency of F6-1,25(OH)2D3 is explained, at least partly, by the results that the amounts of both F6-1,25(OH)2D3 and its active metabolite, F6-1,23,25(OH)3D3, in the bones are higher than that of 1,25(OH)2D3, and that F6-1,25(OH)2D3 and its metabolite are retained in bones longer than 1,25(OH)2D3.

Animals↗
PubMed1998

Protein-protein interactions of the yeast Golgi t-SNARE Sed5 protein distinct from its neural plasma membrane cognate syntaxin 1.

Targeting of vesicles to the acceptor membrane in protein transport depends on membrane proteins called SNAREs. Saccharomyces cerevisiae Golgi t-SNARE Sed5 protein and its neural cognate syntaxin 1 have similar three alpha-helices which are predicted to form coiled coils. We dissected the helices of Sed5 and found several characteristics unexpectedly distinct from those of syntaxin 1. Most importantly, only the N-terminal helix is responsible for the binding of Sly1 protein while almost the entire molecule of syntaxin is necessary for the binding of the cognate, Munc-18. The N-terminal region of Sed5 protein also binds to the C-terminal helix and Sly1 protein interfered this binding.

Antigens, Surface↗
PubMed1998

Suppressive effects of low-power laser irradiation on bradykinin evoked action potentials in cultured murine dorsal root ganglion cells.

The effects of Ga-Al-As diode laser (830 nm, 16.2 mW) irradiation on the distal portion of the processes of cultured murine dorsal root ganglion (DRG) neurons associated with C-fibers were studied by patch-clamp whole-cell recording of membrane potentials at the cell body. The chemical as well as laser light stimulations were limited to the processes of the neuron isolated from the cell body with a separator. The action potentials elicited by bradykinin (BK) in the cell body were reversibly suppressed by the irradiation of laser light. The laser irradiation may block the conduction of nociceptive signals in primary afferent neurons. The present experimental method offers a simple and easy to use procedure for studying the pain relief effects by laser irradiation.

Action Potentials↗
PubMed1998

Separation of a process from the neuronal cell body using a thin aluminum foil separator.

A new technique using a simple-structured separator is described to separate the end of the process from the cell body (soma) of cultured cells. By this method, stimulation limited to neuronal processes is experimentally possible. The separator is of an oblong shape and consists of two parts: a square bracket-shaped frame made of Teflon and a thin aluminum foil which is stuck on both free ends of frame (bracket) coated with epoxy-resin. The separator is horizontally placed on the dish under microscope to divide the process on the way, so that the free end of the process is outside the oblong separator. This separator is simple and low cost, and does not need a long process, unlike other methods requiring a special culture dish with a micro-groove for growth of the neuronal process (neurite). The new technique could be useful in basic pain research and neurophysiology.

Aluminum↗
PubMed1998

In vitro assembly of the CENP-B/alpha-satellite DNA/core histone complex: CENP-B causes nucleosome positioning.

BACKGROUND: We have studied the nucleosome structure formed from alpha-satellite DNA bound with CENP-B and core histones, in order to develop a previous proposal that the CENP-B dimer may play a critical role in the assembly of higher order structures of the human centromere by juxtaposing CENP-B boxes in long alpha-satellite arrays. RESULTS: The dimeric structure of CENP-B was sufficiently stable to bundle together two 3.5 kbp DNA fragments when each DNA contained a CENP-B box. When the same length of DNA included two CENP-B boxes, the intra-molecular interaction with the CENP-B dimer predominated, resulting in the formation of loop structures. The in vitro assembly of CENP-B/alpha-satellite DNA/core histone complexes with the aid of nucleosome assembly protein-1 (NAP-1) permitted an investigation into the nucleosome arrangement in alpha-satellite DNA with CENP-B bound to CENP-B boxes. Footprint analyses with micrococcal nuclease (MNase) revealed that CENP-B causes nucleosome positioning between pairs of CENP-B boxes with unique hypersensitive sites created on both sides. CONCLUSION: We propose that CENP-B functions as a structural factor in the centromere region in order to establish a unique, centromere specific pattern of nucleosome positioning.

Autoantigens↗
PubMed1998

[Usefulness of genotypic analysis for investigation of an epidemic of Shigella sonnei infections in Ooami-shirasato Town, Chiba Prefecture].

In March 1996, an epidemic of Shigella sonnei infection occurred in Ooamishira-sato Town, Chiba Prefecture. Colicine typing, antibiotic resistance patterns, plasmid profiles, pulsed-field gel electrophoresis (PFGE) and random amplified poly-morphic DNA (RAPD) were used for the investigation of the epidemic. Ninety-four isolates from patients exhibited three different colicine types and five different antibiotic resistance patterns. But the patterns of plasmid profile, PFGE and RAPD were uniform among the isolates with different colicine type and antibiotic resistance pattern. It is possible that these isolates belonged to a single bacterial clone and circulated through human to human.

Dysentery, Bacillary↗
PubMed1998

Multidrug resistance phenotype conferred by overexpressing bfr2+/pad1+/sks1+ or pap1+ genes and mediated by bfr1+ gene product, a structural and functional homologue of P-glycoprotein in Schizosaccharomyces pombe.

We investigated the mechanism of multidrug resistance conferred by overexpression of bfr2+/pad1+/sks1+ or pap1+ genes of Schizosaccharomyces pombe. Overexpression of bfr2+ did not confer multidrug resistance on a pap1-disrupted strain. In a mutant with bfr1+ (a putative membrane transporter which belongs to the ATP-binding cassette superfamily) disrupted, overexpression of either bfr2+ or pap1+ did not confer multidrug resistance. These findings suggest that bfr1+ acts as the most downstream effector of the multidrug resistance conferred by bfr2+ and pap1+ genes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Novel membrane protein complexes for protein glycosylation in the yeast Golgi apparatus.

Three type II membrane proteins Anp1, Van1 and Mnn9 of Saccharomyces cerevisiae share significant sequence homology. Their precise biochemical activity has long been unknown though the mutant phenotype indicates their participation in protein glycosylation in the Golgi apparatus. To shed light on their molecular characteristics, interactions of these proteins were studied by immunoprecipitation after solubilizing the membrane by nonionic detergent. Our results indicated that there are at least two submembrane complexes containing these proteins: one contains Van1 and Mnn9 proteins and the other contains Anp1 and Mnn9 proteins. In addition, Hoc1 protein which has significant homology to Och1 protein colocalized with Anp1 and Mnn9 proteins. These complexes with similar but partially different constituents may represent essential parts of glycosylation machinery in the yeast Golgi compartments.

Alleles↗
PubMed1997

Saccharomyces cerevisiae VIG9 encodes GDP-mannose pyrophosphorylase, which is essential for protein glycosylation.

A genomic DNA fragment that complements a newly identified protein glycosylation-defective mutation, vig9, of Saccharomyces cerevisiae was cloned. Chromosomal integration of this fragment by homologous recombination indicated that it contains the wild type VIG9 gene. The nucleotide sequence was determined. A predicted gene product showed significant amino acid sequence homology with several bacterial enzymes that catalyze the synthesis of (deoxy)ribonucleotide diphosphate sugars from sugar phosphates and (deoxy)ribonucleotide triphosphate. We examined the enzyme activity to synthesize GDP-mannose in the cell extracts of the wild type, vig9-1 mutant, and VIG9 transformant yeasts. Reduction of the activity in the mutant cell and its restoration by VIG9 suggested that the VIG9 gene is the structural gene for GDP-mannose pyrophosphorylase of S. cerevisiae which catalyzes the production of GDP-mannose. We demonstrated the enzyme activity of Vig9 protein using a recombinant fusion protein produced in Escherichia coli.

Amino Acid Sequence↗
PubMed1997

Purification and partial characterization of an antigen specific to Lactobacillus brevis strains with beer spoilage activity.

Certain Lactobacillus brevis strains are resistant to hop-derived compounds such as isohumulone and are able to grow in beer. In this study, we raised an antiserum against our beer spoilage laboratory strain L. brevis 578 which reacted with 23 of 24 beer spoilers and two of 13 non-spoilers in precipitation reactions using 0.5 M NaOH cell extracts. This specific antigen to the beer spoilage L. brevis strains (SABSL) was demonstrated to be located beneath the S-layer proteins by agglutination reactions using S-layer protein-stripped cells obtained by treatment with 0.1 M NaOH. SABSL was purified using an affinity column coupled with an antibody against SABSL. The purified antigen was hydrolyzed with 2 M HCl and the hydrolyzate was analyzed by thin-layer chromatography and enzymatic analysis. The results showed that SABSL contains glycerol, phosphate, glycerophosphate, D-galactose and D-glucose. D-Galactose and D-glucose accounted for 4.7% and 0.1% of the composition, respectively. Melibiose, but not mannose, inhibited the precipitation reaction. Intense precipitation reactions were obtained with fractions which did not bind to the ConA-column. These results indicate that the immunodominant component of the SABSL is galactose and the SABSL determinant is most probably a galactosylated glycerol teichoic acid. The antiserum raised against the beer spoilage strain L. brevis 578 could distinguish between Pediococcus beer spoilers and non-spoilers in precipitation reactions.

Animals↗
PubMed1997

Excitatory effects of algesic compounds on neuronal processes in murine dorsal root ganglion cell culture.

The effects of algesic compounds on the distal portion of the processes of cultured dorsal root ganglion cells (C-fiber) of mouse were studied by patch-clamp whole-cell recording at the cell soma (cell body). The processes of the cell were isolated from the cell body with a separator. Bradykinin (BK, 10 microM), prostaglandin E2 (PGE2, 20 microM), and capsaicin (CAP, 2 microM) were applied to the processes of a cell on the third day after seeding, each of which evoked action potentials in the cell body. No desensitization was seen by the repeated application of BK to the processes. No action potentials in the cell body were observed when BK (10 microM) was applied concomitantly with tetrodotoxin (6 microM). These results suggest that the stimuli of algesic compounds to the neuronal processes of the cultured dorsal root ganglion cells are useful for studying the neuronal mechanism involved in pain.

Action Potentials↗
PubMed1997

Isolation and characterization of nickel-accumulating yeasts.

We selected three yeast strains that efficiently remove heavy metal ions from aqueous solution. We first screened yeasts that grew in the presence of 2 mM NiCl2 among our stock of wild yeasts, and then selected those that removed Ni most efficiently from aqueous solution. These strains also removed Cu and Zn from aqueous solution and were identified as Candida species. Ni uptake was efficient at pH between 4.0 and 7.0, but less efficient at pH below 3.0. The amount of Ni taken up by the yeast cells was proportional to the initial concentration of NiCl2 below about 4 mM Ni. The cells retained the abilities to remove Ni after treatment with 10 mM EDTA or 1 M HCl for repeated usage, or after heat treatment.

Hydrogen-Ion Concentration↗
PubMed1997

Improved translational efficiency of subtilisin YaB gene with different initiation codons in Bacillus subtilis and alkalophilic Bacillus YaB.

The ale gene specifying the subtilisin YaB produced by alkalophilic Bacillus YaB, has an unusual start codon UUG. Changing this codon to AUG and GUG increased expression of the ale gene in B. subtilis DB104 and in an ale deficient mutant strain YaB-DEC4. The relative translational efficiency order of the three initiation codons is AUG > GUG > UUG in B. subtilis DB104 and in YaB-DEC4. These data suggest that the preferred initiation codon is AUG for ale gene expression in Bacillus.

Bacillus subtilis↗
PubMed1997

Dose optimization of proton and heavy ion therapy using generalized sampled pattern matching.

We have proposed a new dose optimization method for proton and heavy ion therapy using generalized sampled pattern matching, where an optimal beam weight distribution for scanning is obtained as a solution. Using water phantom models, one-dimensional lateral and depth dose distributions were separately optimized, each resulting in a uniform dose distribution within a target region and minimum dose fall-off to minimize undesired irradiation onto neighbouring tissues. Subsequently, we have applied the technique to broad beam three-dimensional proton therapy, leading to a homogeneous dose distribution inside a target and minimized distal and lateral dose fall-off for most convex tumour shapes.

Humans↗