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Biomedical subjects

Y Asami

Publications and source records attributed to Y Asami.

At least 37 records · Page 2Linked to original sources
PubMed1994

Analysis of chromosome-sized DNA and genome typing of isolated strains of Taylorella equigenitalis.

Analysis of chromosome-sized DNA and genome typing of Taylorella equigenitalis NCTC11184, Kentucky 188, and five strains of T. equigenitalis isolated in Japan were carried out. The three restriction enzymes used, ApaI, NaeI and NotI, cleaved the genomic DNAs of five Japanese strains of T. equigenitalis into relatively limited numbers of restriction fragments, which were well resolved on crossed-field gel electrophoresis (CFGE). The respective profiles after CFGE of the restriction fragments from all five strains were essentially identical to each other after digestion by ApaI, NaeI or NotI. Hence it appears that these strains have a common genome type with respect to these three restriction enzymes. It was also shown that the respective profiles from these strains were essentially different from those of T. equigenitalis NCTC11184 and those of Kentucky 188 after digestion with ApaI, NaeI or NotI.

Animals↗
PubMed1994

Structural studies of new macrolide antibiotics, shurimycins A and B.

The structures of new antibiotics, shurimycins A and B produced by Streptomyces hygroscopicus A1491, were elucidated from the physico-chemical properties, 2D NMR techniques and chemical degradation experiments to be 36-membered macrolides related to azalomycins, scopafungin and guanidylfungins. Shurimycins were active against fungi and Gram-positive bacteria.

Anti-Bacterial Agents↗
PubMed1993

Molecular cloning of a sporulation-specific cell wall hydrolase gene of Bacillus subtilis.

Southern hybridization analysis of Bacillus subtilis 168S chromosomal DNA with a Bacillus licheniformis cell wall hydrolase gene, cwlM, as a probe indicated the presence of a cwlM homolog in B. subtilis. DNA sequencing of the cwlM homologous region showed that a gene encoding a polypeptide of 255 amino acids with a molecular mass of 27,146 Da is located 625 bp upstream and in the opposite direction of spoVJ. The deduced amino acid sequence of this gene (tentatively designated as cwlC) showed an overall identity of 73% with that of cwlM and of 40% with the C-terminal half of the B. subtilis vegetative autolysin, CwlB. The construction of an in-frame cwlC-lacZ fusion gene in the B. subtilis chromosome indicated that cwlC is induced at 6 to 7 h after sporulation (t6 to t7). The spoIIIC (sigma K) mutation and earlier sporulation mutations greatly reduced the expression of the cwlC-lacZ fusion gene. Northern hybridization analysis using oligonucleotide probes of the cwlC region indicated that a unique cwlC transcript appeared at t7.5 and t9. Transcriptional start points determined by primer extension analysis suggested that the -10 region is very similar to the consensus sequence for the sigma K-dependent promoter. Insertional inactivation of the cwlC gene in the B. subtilis chromosome caused the disappearance of a 31-kDa protein lytic for Micrococcus cell walls, which is mainly located within the cytoplasmic and membrane fractions of cells at t9. The CwlC protein hydrolyzed both B. subtilis vegetative cell walls and spore peptidoglycan.

Amino Acid Sequence↗
PubMed1992

Fine structure of the dorsal epithelium of the tongue of the Japanese terrapin, Clemmys japonica (Cheloia, Emydinae).

As reptiles are situated phylogenetically between the amphibians and the mammals, they exhibit considerable variation in the structure of their tongues. The present study, one of a series of studies on reptile tongues, aims to demonstrate the three-dimensional structure of the dorsal lingual surface of a turtle, the Japanese terrapin Clemmys japonica, and to clarify the ultrastructural features of the lingual epithelial cells. In the study lingual papillae were observed by scanning electron microscopy to be widely distributed over the dorsal surface of the tongue. Irregularly shaped (conical, columnar or angular) papillae were located in the anterior and central areas, and ridge-like ones, in the latero-posterior area. Histological examination revealed that the connective tissue penetrated into the core of the papillae, and the epithelium was of a stratified squamous and/or cuboidal type. Under the transmission electron microscope, two types of cells were identified in the intermediate layer of the apical epithelium of the lingual papilla: one type was probably an immature mucous cell, whereas the other was elongated in a baso-apical direction, its cytoplasm containing fine granules. In the surface layer of the apical epithelium, typical mucous cells and cells containing numerous, fine, electron-lucent granules were recognized. Both types of cells possessed microvilli on their free-surfaces. In the lateral epithelium of the lingual papillae, the cytological features from the basal layer to the superficial intermediate layer were essentially the same as in the apical epithelium. However, in the surface layer, mucous cells were significantly larger in number than in the apical epithelium.

Animals↗
PubMed1989

Isolation and characterization of s-myc, a member of the rat myc gene family.

A 9-kilobase-pair clone containing a myc-related gene that we have designated s-myc was isolated from a rat genomic library. The entire nucleotide sequence of the cloned DNA was determined, showing that the s-myc gene contains an open reading frame consisting of 1287 base pairs without introns. In vitro transcription-translation analysis of s-myc indicated that this gene produces a protein of approximately 50 kDa. The amino acid sequence predicted from the DNA sequence showed that the s-Myc protein is closely related to the murine N-Myc protein but lacks an acidic amino acid-rich sequence commonly present in the Myc-family proteins. Studies on transfection of s-myc into rat RT4-AC tumor cells revealed that the gene produces a polyadenylylated transcript of approximately 4.7 kilobases and that its high-level expression suppresses the tumor-igenicity of RT4-AC tumor cells in nude mice.

Amino Acid Sequence↗
PubMed1989

Studies on hypolipidemic agents. IV. 3-[4-(Phenylthio)benzoyl]propionic acid derivatives.

2-Acetylthio-3-benzoylpropionic acid derivatives having two benzene rings or condensed-ring moieties were prepared, and tested for hypolipidemic activity in normal rats. Some of these compounds were active. 2-Acetylthio-3-[4-(phenylthio)benzoyl]propionic acid (10) and its derivatives seemed to have the most potent hypocholesterolemic activities. Compound 10 showed strong activity, especially in cholesterol-fed rats.

Animals↗
PubMed1989

Isolation of the rat s-myc gene having tumor suppressing activity.

We have isolated a myc related gene, called s-myc, from a rat genomic library using a 32P-labeled fragment of exon 3 of v-myc as a probe. Nucleotide sequencing showed that the s-myc gene contains an open reading frame of 1,287 bp without introns. The s-Myc protein predicted from the DNA sequence has approximately 60% amino acid sequence homology with that of the mouse N-Myc protein. Transfection of the s-myc gene into rat RT4-AC tumor cells induced morphological changes of the cells and suppressed their tumorigenicity in nude mice.

Amino Acid Sequence↗
PubMed1989

[Stereo architecture of the connective tissue papillae of lips and gingiva in newborn dogs].

The surface structure of the connective tissue papillae of lips and gingiva of newborn dogs 1 and 4 weeks after birth were observed by scanning electron microscopy. 1. Long term HCl treatment successfully removed the epithelial cell layer from the connective tissue over a large area of fixed material. 2. Connective tissue papillae of labial skin, labial mucosa and alveolar and gingival mucosa were exposed and it became clear that connective tissue papillae were highly developed at the labial margin and just beneath the gingival margin. 3. In the hair growing area of the labial skin, connective tissue papillae became smaller, and some ridge-like structures were found running vertically. 4. On the lining mucosa such as the labial and alveolar mucosa, the surface of the connective tissue papillae showed only ridge-like structures running vertically. 5. From the results of both light and electron microscopy, we concluded that there was a tendency for the area to have a thick epithelial cell layer which contained highly developed connective tissue papillae. This suggested that the blood vessels in the connective tissue papillae can carry nutrients closer to more epithelial cells penetrating deeply into the epithelium thickness.

Animals↗
PubMed1989

[Anatomical studies on a supernumerary tooth considered to be a successional tooth of the lower first molar].

The purpose of this study is to investigate features of the successional tooth of the lower first molar. Materials investigated in this study deal with a supernumerary tooth formed at the distolingual deep part to the lower right first molar of a male patient aged twenty-four. It was observed with binocular microscopy and under X-ray. The occlusal surface of it was observed with scanning electron microscopy. Horizontal ground sections of it were prepared and observed with polarizing microscopy, fluorescent microscopy, and scanning electron microscopy. It is thought that this supernumerary tooth is a true successional tooth of the lower first molar because it was formed at the distolingual deep part to the lower first molar and the fissure of it is Y-shaped and it has five cusps. It is considered that two impressions at buccal and distal surfaces of it isn't original hereditary features but was accidentally formed by pressures of mesial and distal roots of the lower first molar. The rough form of it has most resemblance to the lower second premolar and distal and lingual parts of it are smaller than that of the lower first molar. But fundamental features of the lower first molar are preserved in it. It is thought that the center of the molarization field of human lower successional teeth lies at the successional tooth of the lower first molar because the form of the occlusal surface of it is more complex and functional than those of the lower first and second premolars.

Adult↗
PubMed1989

[Anatomical and histological studies on a microdontic wisdom tooth].

The purpose of this study is to investigate features and histological structures of the microdontic wisdom tooth. Materials investigated in this study deal with a very small upper right microdontic wisdom tooth of a male patient aged thirty-six. It was observed with binocular microscopy and under X-ray. Horizontal ground sections of it were prepared and observed with polarizing microscopy, phase microscopy, microradiograph, and scanning electron microscopy. Total length of this specimen was about 1/2 of the average measurement in Japanese upper third molars, breadth of the crown about 1/3, thickness of the crown about 1/4. It had one cusp and one root. It is considered that one cusp was formed by fusing of the mesiolingual cusp and mesiobuccal one because fundamental features of the buccal and lingual surfaces of upper molars were preserved in this specimen. It is thought that dental tubules in this specimen were formed more densely than those in the common wisdom tooth because the space of retreating odontoblasts of this specimen was limited but that enamel rods in this specimen were formed more thickly than those in the common wisdom tooth because the space of retreating ameloblasts of this specimen was wide. It is considered that the degeneration in this specimen came up to not only the dental form, but also the histological structure of the enamel because the surface layer of the enamel of this specimen was composed of the laminal structure.

Adult↗
PubMed1989

[On the peculiar dentin existing in the gutter-shaped root].

The purpose of this study is to investigate the histological structure of the gutter-shaped root. Materials investigated in this study deal with 15 japanese lower molars of adults having gutter-shaped roots and 2 of them of children. Buccolingual, mesiodistal, and horizontal ground sections of them were prepared and observed with binocular microscopy, polarizing microscopy, phase microscopy, fluorescent microscopy, microradiograph, and scanning electron microscopy. It is thought that the lingual dentin of the gutter-shaped root is transparent and roentgenopaque because it has primarily slender and sparse dentinal tubules. It is considered that the lingual dentin differs from the transparent dentin of which dentinal tubules were secondarily filled with calcified substance. It is considered that the lingual dentin of the gutter-shaped root is thinner than the buccal dentin because the forming time of the lingual dentin isn't brief but the forming speed of it is late. It is thought that the peculiar dentin is formed at the lingual part because one odontoblast shares more broad forming space of the dentin there than the other part.

Adult↗
PubMed1988

Beta-actinin: a capping protein at the pointed end of thin filaments in skeletal muscle.

We examined the function of beta-actinin as a pointed end capping protein of thin filaments in skeletal muscle. An improvement in preparing beta-actinin yielded purified beta-actinin which retained its activity for more than a week. Two-dimensional gel electrophoresis showed that the two subunits, beta I and beta II, of beta-actinin are, respectively, split into two to three components (isoforms) with different isoelectric points. Polyclonal antibody was raised by injecting such purified and undenatured chicken breast muscle beta-actinin composed of several components into a rabbit. Immuno-gold labeling examination with electron microscopy of an F-actin-beta-actinin complex decorated with HMM showed that 85% of bound gold particles was on the pointed end of actin filaments, while the remaining 15% was on the barbed end. This suggests that in beta-actinin preparation pointed end and barbed end capping proteins inevitably coexist. Immunofluorescence and immunoelectron microscopy directly showed that beta-actinin is located at the pointed end of thin filaments in myofibrils; it was also suggested that a capping protein having common antigenic determinants to beta-actinin is located at Z-line. Thus, the physiological function of beta-actinin as a pointed end capping protein was examined as follows: When beta-actinin was dissociated from the pointed end of thin filaments in an I-Z-I brush by using a high salt solution, thin filaments could be disassembled at the pointed ends at concentrations of exogenous actin lower than a critical value. At a physiological ionic strength, these salt-washed thin filaments gradually shortened at a constant rate of about 45 nm/h. Both the association and dissociation of monomeric actin at the pointed end were suppressed by the rebinding of exogenous beta-actinin. The main physiological role of beta-actinin is therefore to stabilize thin filaments in the sarcomere by preventing addition and removal of actin monomers at the pointed filament end.

Actin Cytoskeleton↗
PubMed1988

Transition of beta-actinin isoforms during development of chicken skeletal muscle.

We examined by means of the immunoblotting technique the transition of beta-actinin isoforms during the development of the chicken from 5 day embryo to adult. As an antigen, beta-actinin was prepared from adult chicken breast muscle (pectoralis major) and polyclonal antibody was obtained by injecting undenatured beta-actinin into a rabbit. Immunoblotting examination of breast muscle at several stages of development (except 5 day embryo, in which the whole body minus the head and limbs was examined) showed that the species of beta-actinin subunits change during development: 1) beta I is already present in 5 day embryo, whereas beta II appears only after 9 days. 2) In 5 day embryo, we found, instead of beta II, a new subunit (designated beta III) that cross-reacts with the antibody, has the apparent molecular weight of 30,000 daltons and has a slightly alkaline isoelectric point compared with beta I. The content of beta III gradually decreased and beta III completely disappeared a week after hatching. Such a type of transition of the isoforms in beta-actinin subunits is similar to that observed in other muscle proteins. The transition of beta-actinin isoforms may correlate to the organization of an I-Z-I brush, especially to the length determination of thin filaments, because the developmental stage at which beta III disappears coincides with that at which the length of thin filaments is strictly determined.

Actinin↗
PubMed1988

Beta-actinin isoforms in various types of muscle and non-muscle tissues.

We found that beta-actinin isoforms are present in various types of tissues in adult chicken by using immunoblotting after two dimensional gel electrophoresis; for this purpose, an antibody was raised against beta-actinin purified from adult chicken breast muscle (pectoralis major). One of the beta-actinin subunits, beta I, was present in all tissues we examined, i.e. skeletal (pectoralis major, semitendinosus, and anterior latissimus dorsi), cardiac, and smooth (gizzard) muscles, non-muscle (brain, liver, and kidney) tissues and blood, whereas another subunit, beta II, was present only in muscle tissues. A new subunit (designated beta III) that was found in the embryonic stages of skeletal muscle (Asami, Funatsu & Ishiwata (1988) J. Biochem. 103, 72-75) was present instead of beta II in non-muscle tissues and blood. In cardiac and smooth muscles, beta III coexisted with beta I and beta II. The antibody of beta-actinin did not cross-react to cytoplasmic beta-actinin (molecular weight, 80,000 daltons) found in kidney. It was suggested that the combination of beta I and beta III present in non-muscle tissues and blood is identical to the barbed end capping protein isolated from brain by Killiman and Isenberg (EMBO J. 1, 889-894 (1982)). It is likely that beta-actinin forms a genetic family whose constituents have an ability to cap either the pointed or barbed end of actin filaments.

Actinin↗
PubMed1988

Disruption of the Escherichia coli cls gene responsible for cardiolipin synthesis.

The cls gene of Escherichia coli is responsible for the synthesis of a major membrane phospholipid, cardiolipin, and has been proposed to encode cardiolipin synthase. This gene cloned on a pBR322 derivative was disrupted by either insertion of or replacement with a kanamycin-resistant gene followed by exchange with the homologous chromosomal region. The proper genomic disruptions were confirmed by Southern blot hybridization and a transductional linkage analysis. Both types of disruptants had essentially the same properties; cardiolipin synthase activity was not detectable, but the strains grew well, although their growth rates and final culture densities were lower than those of the corresponding wild-type strains and strains with the classical cls-1 mutation. A disruptant harboring a plasmid that carried the intact cls gene grew normally. The results indicate that the cls gene and probably the cardiolipin synthase are dispensable for E. coli but may confer growth or survival advantages. Low but definite levels of cardiolipin were synthesized by all the disruptants. Cardiolipin content of the cls mutants depended on the dosage of the pss gene, and attempts to transfer a null allele of the cls gene into a pss-1 mutant were unsuccessful. We point out the possibilities of minor cardiolipin formation by phosphatidylserine synthase and of the essential nature of cardiolipin for the survival of E. coli cells.

Alleles↗