PubMed Health⌕ Search

Biomedical subjects

A Matsushiro

Publications and source records attributed to A Matsushiro.

At least 55 records · Page 3Linked to original sources
PubMed1988

Isolation of endo A cDNA from mouse 8-cell stage embryos.

To analyse the species of genes expressed in a cleavage stage mouse embryo, we have constructed a cDNA library containing 3.0 x 10(5) independent clones from about 2 x 10(3) embryos at the 8-cell stage of development. Endo A cDNA prepared from parietal yolk sac endoderm like PYS-2 cells was used to screen the library. Southern blot analyses using the endo A sequence as a probe and restriction mapping analyses revealed that four independent recombinants had been inserted endo A sequence. Sequencing data of these clones showed that endo A mRNA present in the 8-cell stage embryo is identical to that of parietal yolk sac endoderm cells.

Animals↗
PubMed1988

Nucleotide sequence of mouse EndoA cytokeratin cDNA reveals polypeptide characteristics of the type-II keratin subfamily.

EndoA cytokeratin (EndoA) belongs to a family of intermediate filaments (IFs) and is coordinately expressed with EndoB cytokeratin during early mouse embryogenesis. We have isolated and sequenced a cDNA from a library constructed from mRNA of parietal yolk sac-like cells, PYS-2, which are derived from mouse teratocarcinoma. Sequence analysis reveals that EndoA is composed of 490 amino acids, its Mr is 54,362, and it contains a central alpha-helical coiled-coil structure flanked by non-alpha-helical domains. The amino acid sequence of EndoA is highly homologous with human cytokeratin No. 8 (93%) and with bovine cytokeratin No. 8 (91%) not only in the central domain, but also in its tail portion, which is less conserved among other intermediate filaments. A comparison with the other cytokeratin proteins characterizes this polypeptide as a non-epidermal type of cytokeratin of the basic (type-II) subfamily. The C-terminal sequence of EndoA is identical to that of human and bovine cytokeratin No. 8 and also highly conserved in other intermediate filaments (desmin, vimentin, glial fibrillary acidic protein and EndoB). It suggests that these may be involved in interaction with some cell component(s), or in more general roles to form IFs. The N-terminal head region is rich in Ser residues including possible phosphorylation sites.

Amino Acid Sequence↗
PubMed1988

Detection of H-2K mRNA in mouse 8-cell embryo by cDNA cloning.

Mouse MHC class I gene expression in 8-cell embryo was examined by cDNA cloning. We constructed a cDNA library from 8-cell embryos of ICR mice and isolated a class I cDNA from 3.0 x 10(5) phage clones of the library. Sequencing analysis of this clone revealed it to include the cDNA fragment extending from the exon 6 of the cytoplasmic portion to 3' untranslated region 1 of H-2K gene. Qa, Tla or other embryonic class I cDNA have not been isolated in the library.

Animals↗
PubMed1987

Tryptophan synthase alpha subunit glutamic acid 49 is essential for activity. Studies with 19 mutants at position 49.

We have obtained a complete set of 20 variants of the alpha subunit of tryptophan synthase of Escherichia coli at position 49 in order to extend our previous studies on the effects of single amino acid replacements at position 49 on structure and function. Thirteen mutant alpha subunits have been newly constructed by site-directed mutagenesis using oligonucleotides. Six mutants were available from previous studies. We find that the wild type and all of the mutant alpha subunits form alpha 2 beta 2 complexes with the beta 2 subunit of tryptophan synthase with similar association constants and similarly stimulate the activity of the beta 2 subunit in the synthesis of L-tryptophan from L-serine and indole. Thus none of the changes at position 49 produces a change in the conformation of the alpha subunit which significantly interferes with normal subunit interaction. However, the 19 mutant alpha 2 beta 2 complexes are completely devoid of activity in reactions normally catalyzed by the active site of the alpha subunit. This is the first time that these several activities have been measured with a series of highly purified alpha subunits altered by mutation at a single site. Our finding that the mutant in which glutamic acid 49 is substituted by aspartic acid is totally devoid of alpha activity is especially significant and is strong evidence that glutamic acid 49 is an essential catalytic base in the reaction catalyzed by the alpha subunit. This result is consistent with the results of previous genetic studies, with evolutionary comparisons using sequence analysis, and with recent results from x-ray crystallography of the alpha 2 beta 2 complex of tryptophan synthase from Salmonella typhimurium.

Base Sequence↗
PubMed1986

Expression of c-mos proto-oncogene in undifferentiated teratocarcinoma cells.

Proto-oncogene c-mos, the cellular homologue of the transforming gene of Moloney murine sarcoma virus, has been characterized by the lack of expression in a variety of differentiated tissues, possibly because of the existence of an inhibitory upstream sequence. We detected mos-related transcripts in undifferentiated embryonal carcinoma cells of pluripotential cell line 311. The sizes of three major transcripts detected were estimated to be 1.8, 4.6 and 6.1-kilobases (kb) by northern analysis. Furthermore, these transcriptions were suppressed when the cell differentiation was induced by retinoic acid. Taken together, the results suggest that mos product plays a role in early stages of development.

Animals↗
PubMed1986

Identification and purification of the N gene product of bacteriophage phi 80.

To confirm the in vivo observation that the N gene product of phi 80, phi 80-pN, prevents termination of transcription at the tL1 region and is therefore a transcription antitermination factor (Tanaka and Matsushiro 1985), we demonstrated that phi 80-tL1 is a rho-dependent terminator, similar to lambda-tL1, and that phi 80-pN has a transcription antitermination function at this site in an in vitro transcription system using a nucleic acid-free S-100 extract. In the presence of rho-protein, transcription termination at tL1 was suppressed completely with an S-100 extract prepared from Escherichia coli strain NT525 containing the pBN1-N+ plasmid. Starting from this pN-overproducing cell extract, we purified phi 80-pN to homogeneity by chromatography on DEAE-Sephacel, Sephadex G-150 and CM-Sephadex C-50. The molecular weight of purified pN was about 12,000 and the NH2-terminal sequence was NH2-Met-Ile-Asp-Asp-Ile-Lys, which was consistent with the sequence deduced from the DNA sequence.

Cloning, Molecular↗
PubMed1986

Studies of developmental abnormalities at the molecular level of mouse embryos homozygous for the t12 lethal mutation.

Embryos obtained by crossing heterozygous t12 mutant mice were labeled metabolically with 14C-amino acids at the mid-morula stage, and the protein pattern of single embryos was examined by two-dimensional polyacrylamide gel electrophoresis. After labeling, the morphology was still normal. The genotypes of the embryos could be identified by the allelic forms of Tcp-1 (p63/6.9) protein on the gel. In t12/t12 embryos, the bulk of syntheses of macromolecules such as proteins and RNAs [poly(A)+, as well as poly(A)-RNA] was normal, however, syntheses of several proteins were markedly reduced. Some of these proteins present in reduced amounts appeared to be components of cytokeratin-type intermediate filaments (endo A and endo B), judging from their insolubility in non-ionic detergent, their appearance in the mid-morula stage, their location in trophectodermal cells, and their electrophoretic mobilities. These observations suggest that mechanisms for the induction of the intermediate filament proteins are defective in embryos homozygous for the t12 mutation. Possible relationships between the morphological abnormalities of the embryos and their defective synthesis of intermediate filaments are discussed.

Alleles↗
PubMed1985

Characterization and sequencing of the region containing gene N, the nutL site and tL1 terminator of bacteriophage phi 80.

We have cloned the early region of the major leftward operon of bacteriophage phi 80 DNA and determined the nucleotide sequence of the PL-nutL-tL1 segment. The genes and sites equivalent to lambda gene N, antiterminator nutL, and terminator tL1 were found in this region by functional tests using the recombinant plasmids carrying the transcriptional units Ptrp-tL1-galK, Ptrp-nutL-tL1-galK and PlacUV5-N. Sequence homologies were observed between the boxA of the phage 21 nutR site and the inverted repeat of the nut core in the nutL-equivalent site of phi 80. The N-equivalent gene of phi 80 codes for a protein with 98 amino acids. It is highly basic as is the lambda N protein. Recombinant plasmids carrying the phi 80-PL promoter and nut-equivalent site of phi 80 are lethal to the Escherichia coli host cell, but can be stably maintained in the presence of the phi 80-cI repressor.

Amino Acid Sequence↗
PubMed1984

Production, purification and characterization of the plasminogen activator in teratocarcinoma stem cells induced with sodium butyrate.

Suspension cultures of pluripotent teratocarcinoma cells were induced with sodium butyrate to produce plasminogen activator (PA), generally regarded as a marker enzyme of differentiation of the teratocarcinoma. The induction of plasminogen activator was very efficient, resulting in production of sufficient enzyme to allow its purification. The activator was inactivated by rabbit anti-human melanoma plasminogen activator antiserum, indicating that it was a tissue-type activator (t-PA). The enzyme was purified by column chromatograph on phosphocellulose, zinc-chelate agarose, Con-A Sepharose and Sephadex G-150. The preparation at the final step of purification gave a single peak of enzyme activity at pH 7.3 +/- 0.1 on isoelectric focusing, and showed a molecular weight of approximately 77,000 on SDS PAGE.

Animals↗
PubMed1983

Mode of cell surface marker changes during retinoic acid-induced differentiation in pluripotent embryonal carcinoma cells.

Pluripotent teratocarcinoma cell line, 311, was cultured in the presence of retinoic acid (RA) and studied for the processes of early marker changes associated with cell differentiation. The cell populations that have lost peanut agglutinin (PNA), Lotus tetragonolobus agglutinin (LTA) or wheat germ agglutinin (WGA) receptor increased in proportion to the period since the start of RA treatment. The kinetics of the appearance of these receptor-negative cell populations suggests that the differentiating cells lose lectin receptors in the order of PNA, LTA and WGA. However, the changes in F9 antigen(s) and LTA receptor occurred at an equal frequency in PNA+ and PNA- cells, indicating that, although the loss of lectin receptors takes place in a distinct order, the change in each receptor itself proceeds independently of the state of other lectin receptors.

Animals↗
PubMed1983

Induction of teratocarcinoma cell differentiation. Effect of the inhibitors of DNA synthesis.

Induction of teratocarcinoma cell (F9) differentiation was studied by using inhibitors of DNA synthesis and several agents known to be differentiation inducers. Inhibition of DNA synthesis induced changes in cell surface marker F9 and stimulated the production of plasminogen activator (PA) in a manner that is dependent upon de novo synthesis of RNA and protein. The results thus indicate close association between inhibition of DNA synthesis and induction of cell differentiation. This approach will be useful in investigating the mechanism of teratocarcinoma cell differentiation.

Animals↗
PubMed1983

Isolation of the ST Ent plasmid specific bacteriophage M124.

For simple detection of enterotoxigenic E. coli from patients, attempts were made to find a bacteriophage that specifically proliferate on these bacteria. As a result phage M124 was isolated. Analysis of plasmid DNA together with detection of ST enterotoxin showed that this phage can specifically attack E. coli carrying the ST Ent plasmid (80 Mdalton). These results indicate that phage M124 is very useful for detection of ST enterotoxigenic bacteria.

Bacterial Toxins↗
PubMed1982

Effects of beta-mercaptoethanol-containing medium and feeder cells on the differentiation of embryonal carcinoma cells.

Pluripotent, feeder-dependent teratocarcinoma cell lines were cultured without a feeder layer in a medium containing 10(-4) M beta-mercaptoethanol (beta-medium) and compared for the development of early markers with cells cultured with a feeder layer. The cells cultured in beta-medium lost the PNA (peanut agglutinin) receptor typically at low density. This change was accompanied with enhanced secretion of plasminogen activator and the loss of sensitivity to anti-F9 serum, indicating the stem cell differentiation. In contrast, the cells cultured on a feeder layer did not show any marker changes, thus indicating the lack of differentiation. These results indicate that while the presence of feeder cells inhibits cell differentiation, cultivation in beta-medium permits the differentiation of pluripotent teratocarcinoma cells.

Animals↗
PubMed1981

Isolation and characterization of deletion mutants affected in early genes of bacteriophage phi 80.

When Escherichia coli cells that had been irradiated with ultraviolet light were infected with bacteriophage phi 80, five major (pE, pB, pA, pC and pD) and two minor (pU and pV) proteins were found to be synthesized during early stages of infection. The genes coding for the five major proteins were mapped on the phi 80 chromosome using various deletion mutants which lacked the capacity to synthesize some or all the major proteins. The size and positions of all the deletions were determined by gel electrophoresis of EcoRi digests of phage DNA and by electron microscopy of heteroduplexes between DNAs of the deletion and wild-type phage. The five major proteins designated pE(25K), pB(40K), pA(45K), pC(34K) and pD(31K) were shown to be encoded in this order presumably by a single operon that was located at 60.2--67.4% on the phi 80 genome. These proteins were found to be involved in phage recombination. The absence of pE or pB resulted in a Red- phenotype and the absence of three proteins (pE, pB and pA) resulted in a Fec- phenotype. The exact positions of the genes for the minor proteins pU(29K) and pV(26K) have not been determined.

Bacteriophages↗
PubMed1981

Regulation of early gene expression of bacteriophage phi 80: transcriptional regulation by phi 80 gene 30.

The gene30sus620 mutation of bacteriophage phi 80 was mapped close to the left of the cI gene on the standard genetic map. The distance between the mutation (gene30sus620) and the cI gene was about 0.01%, as judged by recombination frequencies. The transcriptional pattern of the mutant showed two distinct differences from that of the wild type; late mRNAs were not synthesized, and early genes were preferentially transcribed rightward in contrast with the predominantly leftward transcription in the wild type. The synthesis of early proteins was also affected. Wild-type phi 80 permits synthesis of five major proteins (pE, pB, pA, pC, and pD) and two minor proteins (pU and pV) upon infection of ultraviolet-irradiated cells. Synthesis of the major proteins was significantly reduced in the mutant, while synthesis of the two minor proteins was enhanced several-fold in this mutant. These results indicate that the gene 30 product regulates the transcription of the two operons in the early region of phi 80, i.e., operon 1, which is transcribed to the left and codes for the five major proteins, and operon 2, which seems to be transcribed to the right and codes for the two minor proteins.

Bacteriophages↗
PubMed1981

Genetic labeling of an Ent plasmid that encodes heat-stable enterotoxin of enterotoxigenic Escherichia coli isolated from patients.

Ent plasmids of enterotoxigenic Escherichia coli that encode heat-stable enterotoxin (ST) and both ST and heat-labile enterotoxin (LT) were labeled with a kanamycin- and an ampicillin-resistance transposon, respectively. These transposons were kept stably in the respective Ent plasmids. By monitoring antibiotic resistance we could easily select strains carrying Ent plasmids. Strains carrying the labeled plasmids produced enterotoxins that were immunologically indistinguishable from those produced by the parent strains. Moreover the strain carrying a labeled ST-Ent plasmid produced 16 times more ST than the parent strain.

Ampicillin↗