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T Baba

Publications and source records attributed to T Baba.

At least 109 records · Page 6Linked to original sources
PubMed1996

A 460-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 40.1-50.0 min region on the linkage map.

The 465,813 base pair sequence corresponding to the 40.1-50.0 min region on the genetic map of Escherichia coli K-12 (W3110) was determined. Analysis of the sequence revealed that this region contained at least 466 potential open reading frames, of which 187 (40%) were previously reported, 105 (23%) were homologous to other known genes, 103 (22%) were identical or similar to hypothetical genes registered in databases, and the remaining 71 (15%) did not show a significant similarity to any other gene. At the 45.2-46.0 min region, we found a very large cluster of about 30 genes, whose functions are involved in the biosynthesis of polysaccharides as the components of outer membranes. In addition, we identified a new asn-tRNA gene, designated asnW, between the asnT and asnU genes and a new lysogenic phage attachment site as the cis-element.

Attachment Sites, Microbiological↗
PubMed1996

Target cell specificity of a bacteriocin molecule: a C-terminal signal directs lysostaphin to the cell wall of Staphylococcus aureus.

Microbial organisms secrete antibiotics that cause the selective destruction of specific target cells. Although the mode of action is known for many antibiotics, the mechanisms by which these molecules are directed specifically to their target cells hitherto have not been described. Staphylococcus simulans secretes lysostaphin, a bacteriolytic enzyme that cleaves staphylococcal peptidoglycans in general but that is directed specifically to Staphylococcus aureus target cells. The sequence element sufficient for the binding of the bacteriocin as well as of hybrid indicator proteins to the cell wall of S.aureus consisted of 92 C-terminal lysostaphin residues. Targeting to the cell wall of S.aureus occurred either when the hybrid indicator molecules were added externally to the bacteria or when they were synthesized and exported from their cytoplasm by an N-terminal leader peptide. A lysostaphin molecule lacking the C-terminal targeting signal was enzymatically active but had lost its ability to distinguish between S.aureus and S.simulans cells, indicating that this domain functions to confer target cell specificity to the bacteriolytic molecule.

Bacterial Outer Membrane Proteins↗
PubMed1996

A 718-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 12.7-28.0 min region on the linkage map.

The 718,122 base pair sequence of the Escherichia coli K-12 genome corresponding to the region from 12.7 to 28.0 minutes on the genetic map is described. This region contains at least 681 potential open reading frames, of which 277 (41%) have been previously identified, 147 (22%) are homologous to other known genes, 139 (20%) are identical or similar to the hypothetical genes registered in databases, and the remaining 118 (17%) do not show a significant similarity to any other gene. In this region, we assigned a cluster of cit genes encoding multienzyme citrate lyase, two clusters of fimbrial genes and a set of lysogenic phage genes encoding integrase, excisionase and repressor in the e14 genetic element. In addition, a new valine tRNA gene, designated valZ, and a family of long directly repeated sequences, LDR-A, -B and -C, were found.

DNA, Bacterial↗
PubMed1996

Boar proacrosin expressed in spermatids of transgenic mice does not reach the acrosome and disrupts spermatogenesis.

Transgenic mice that express boar proacrosin were produced to examine mechanisms for targeting hydrolytic enzymes to the acrosome. A 2.3 kb transgene was constructed by ligating the cDNA for boar preproacrosin with the mouse protamine 2 promoter region. Six founder mice that incorporated the transgene were identified by polymerase chain reaction and Southern blot analysis. Northern blots indicated that the two male founders (Ac.2 and Ac.5) and male progeny from three female founders (Ac.3, Ac.4, Ac.6) expressed the transgene mRNA in testis, but not in somatic tissues. In these transgenic animals boar proacrosin was detected by immunohistochemistry in condensing spermatids, but was not localized in the acrosome. This acrosomal targeting defect of the transgene product may result from its delayed expression during the later steps of haploid differentiation. Furthermore, both male founders and all Ac.4 and Ac.6 males were infertile, as determined by multiple matings for at least 2 months. Ac.3 males were either infertile or rarely transmitted the transgene to their offspring. The infertile males mated, produced copulatory plugs, and had seminal vesicle weights and testosterone levels within the normal range. However, they produced significantly fewer spermatozoa and had lower testis weights than controls. Although the mitotic and meiotic phases of spermatogenesis appeared normal by histological criteria, condensing spermatids were missing from most tubules, and multinucleated cells were present in the lumen of seminiferous tubules and in the epididymis. We hypothesize that boar proacrosin which fails to reach the acrosome is activated in these transgenic mice, and that its proteolytic activity disrupts spermatogenesis during spermatid formation.

Acrosin↗
PubMed1996

Determination of enamel protein synthesized by recombined mouse molar tooth germs in organ culture.

Epithelial-mesenchymal interaction is a prerequisite for tooth morphogenesis. To study this interaction, inner enamel epithelium and dental papilla mesenchyme of molar tooth germs from a 16.5-day mouse embryo were dissociated enzymatically and cultured alone or after recombination. Characteristic matrix protein synthesized and secreted by recombined tooth germ was determined quantitatively by enzyme-linked immunosorbent assay. The protein was detected in the culture of recombined tooth germ but not of dissociated enamel epithelium alone. The amount of enamel protein increased until 8 days in culture. Morphological differentiation of the recombined epithelial rudiment into ameloblasts and enamel protein production were confirmed.

Ameloblasts↗
PubMed1996

An acetophenone glycoside from Exacum affine.

A new acetophenone glycoside, affinoside, was isolated from the aerial parts of Exacum affine and its structure was determined as 2-O-primeverosylpaenol. The known glucosides, gentiopicroside, 2'-O-E/Z-p-coumaroylloganin and glucopaeonol, were also identified.

Acetophenones↗
PubMed1996

Inhibition of cytotoxic activity of carp lymphocytes (Cyprinus carpio) by anti-thymocyte monoclonal antibodies.

A series of monoclonal antibodies (mAbs) were developed against carp thymocytes and carp immunoglobulin (IgM). Anti-thymocyte mAbs reacted with thymocytes, head kidney lymphocytes (HKL) as well as peripheral blood lymphocytes (PBL) at various proportions. Anti-IgM antibody reacted with HKL and PBL but not with thymocytes. PBL from carp immunized with xenogeneic mouse myeloma cells exhibited cytotoxic activity against target cells but PBL from unimmunized fish showed weak cytotoxicity. Treatment of PBL with anti-thymocyte mAbs and guinea pig complement suppressed the cytotoxic activity dose dependently; however, anti-IgM mAb did not. These results indicate the cytotoxic cells in PBL possess cell surface antigens common to thymocytes.

Animals↗
PubMed1996

The study of ultraviolet B-induced apoptosis in cultured mouse keratinocytes and in mouse skin.

The responsibility of ultraviolet B (UVB) radiation for the induction of apoptosis in epidermal cells in vitro and in vivo was examined. Using cultured mouse keratinocytes, PAM212 cells, the morphological development of apoptotic cells (AC) after UVB irradiation was observed, and their DNA status was also examined. In addition, histochemical analysis was performed to establish whether the UVB-mediated sunburn cells (SBC) were AC or not. The cultured cells exposed to UVB showed the morphological characteristics of AC, and the electrophoresis of DNA isolated from these cells showed characteristic fragmentation, i.e. 'DNA ladder'. DNA fragmentation was detectable with UVB doses of more than 50 mJ/cm2, and it appeared 12 h after irradiation, indicating endonuclease-mediated DNA damage. In vivo experimentation using the TdT-mediated dUTP-biotin nick end labeling method (TUNEL) for detection of AC showed scattered positive cells in the basal layer of the UVB-irradiated mouse ear skin. The distributed pattern of the TUNEL-positive cells was similar to that of SBCs. These findings suggest that UVB is a causative factor of apoptosis in the epidermal cells, and that SBC is formed as a result of the apoptosis.

Animals↗
PubMed1996

Cell biology of kidney glomerulus.

It has been accepted that some artifacts are inevitably produced by the conventional preparation steps for electron microscopy, including fixation, dehydration, embedding, ultrathin sectioning, and staining. Therefore, conventional ultrastructural findings on kidney glomeruli are hardly thought to be correlated with the physiological functions of kidneys in vivo. In this chapter, two preparation techniques, the quick-freezing and deep-etching (QF-DE) method or the quick-freezing and freeze-substitution (QF-FS) method, are presented and shown to be useful for clarifying the ultrastructures of kidney glomeruli more closely to structures in vivo with fewer artifacts. Moreover, the ultrastructures of glomerular capillary loops have been demonstrated by a new "in vivo cryotechnique," that shows that hemodynamic factors should be considered in the morphological study of glomerular functions.

Animals↗
PubMed1996

A case of von Recklinghausen's disease with bilateral pheochromocytoma-malignant peripheral nerve sheath tumors of the adrenal and gastrointestinal autonomic nerve tumors.

A 48-year-old man with neurofibromatosis type 1 presented with chest pain, paroxysmal hypertension, tachycardia, and progressive respiratory insufficiency. Clinical investigation displayed calcified tumors in the anterior mediastinum and pararenal region. Histological examination at autopsy revealed composite tumors consisting of pheochromocytoma and malignant peripheral nerve sheath tumor (MPNST) at two sites: the left adrenal gland and the region surrounding the inferior vena cava, probably corresponding to the right adrenal gland. The MPNST component showed a varied histological appearance, including hyalinized bands with polygonal cells, a cartilaginous and myxoid stroma, a hemangiopericytomatous architecture, and a fibrosarcomatous structure, which suggested osteosarcoma, chondrosarcoma, angiosarcoma, and fibrosarcoma, respectively. In addition, based on the ultrastructural findings, the gastrointestinal tract was involved with mesenchymal tumors showing neurogenic differentiation. These lesions suggest the divergent cellular differentiation of neural crest-derived cells to mesenchymal elements as well as neuroectodermal neoplasms.

Adrenal Gland Neoplasms↗
PubMed1996

Successful treatment of mucosal melanosis of the lip with normal pulsed ruby laser.

Melanosis of the lip is not rare in Orientals. Although it causes cosmetic problems, treatment of this pigmentary disorder is often neglected because a satisfactory tool for complete removal of mucosal melanosis has not yet been developed. The pulsed ruby laser, which has a wavelength of 694 nm and a short pulse duration of 1-2 msec, selectively damages pigmented cells in the skin. In this study, six Japanese patients with labial melanosis, manifested as labial lentigo and Peutz-Jeghers syndrome, were successfully treated with the pulsed ruby laser. The therapy achieved rapid results without producing changes in mucosal texture or recurrence after operation.

Adolescent↗