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T Tamaoki

Publications and source records attributed to T Tamaoki.

At least 163 records · Page 9Linked to original sources
PubMed1980

Tetrocarcins, novel antitumor antibiotics. I. Producing organism, fermentation and antimicrobial activity.

A novel antitumor antibiotic complex has been obtained from the culture broth of Actinomycete strain DO-11 (KY11091) isolated from a soil sample collected in Sendai, Miyagi, Japan. On the taxonomic studies the producing organism is described as Micromonospora chalcea KY11091. For the production of the antibiotics, soluble starch served as a good carbon source and yeast extract was the best nitrogen source tested. The antibiotic complex designated as tetrocarcins is active against Gram-positive bacteria, but is not active against Gram-negative bacteria. Tetrocarcin A showed bacteriocidal activity against Bacillus subtilis.

Aminoglycosides↗
PubMed1980

Tetrocarcins, novel antitumor antibiotics. II. Isolation, characterization and antitumor activity.

Novel antitumor antibiotics, tetrocarcin complex composed of three components (A, B and C) were isolated from the culture broth of Micromonospora chalcea KY11091 through various procedures. Tetrocarcins showed marked activity against experimental tumors such as mouse sarcoma 180 and mouse leukemia P388. Multiple injections showed better therapeutic effect against tumors. Mode of action of tetrocarcin A against Bacillus subtilis was found to be through the inhibition of RNA synthesis.

Aminoglycosides↗
PubMed1980

Changes in polysomal polyadenylated RNA and alpha-fetoprotein messenger RNA during hepatocarcinogenesis.

Polysomal polyadenylated RNA was isolated from preneoplastic and neoplastic livers obtained from rats kept on a choline-deficient diet containing ethionine for 8 and 25 to 32 weeks, respectively. Normal, preneoplastic, and neoplastic liver polysomal messenger RNA's (mRNA's) were hybridized with homologous and heterologous 3H-labeled complementary DNA's (cDNA's). The results show that, in terms of RNA mass, all or most of the polysomal polyadenylated RNA present in preneoplastic or neoplastic liver is also present in normal liver. This was induced by the similar extent of hybridization between [3H]cDNA transcribed from preneoplastic or neoplastic liver mRNA's with their homologous mRNA's and with mRNA from normal liver. Conversely, most or all of the polysomal polyadenylated RNA of normal liver is also found in preneoplastic and neoplastic livers, as indicated by the extent of hybridization of [3H]cDNA transcribed from normal liver with mRNA's from normal, preneoplastic, and neoplastic livers. Shifts in the relative abundance of mRNA sequences were detected in the polysomal mRNA of preneoplastic livers and especially in the mRNA of neoplastic liver. Hybridization of alpha-fetoprotein cDNA with liver polyadenylated RNA showed a substantial increase in alpha-fetoprotein mRNA content after 8 and 15 weeks of feeding the carcinogenic diet. Similar experiments using globin cDNA failed to show an increase in globin mRNA content in preneoplastic livers.

Animals↗
PubMed1979

In vitro synthesis of murine pre-alpha-fetoprotein.

Murine alpha-fetoprotein was synthesized in a wheat germ cell-free system in the presence of radioactive amino acids under the direction of alpha-fetoprotein messenger RNA isolated from mouse yolk sacs. The radiolabeled alpha-fetoprotein was isolated by immunoabsorption, and the amino acid residues at the NH2 terminus were determined by radioactive sequencing techniques. In a comparison to the NH2-terminal sequence of circulating alpha-fetoprotein, the in vitro-synthesized alpha-fetoprotein was found to contain an extra peptide 20 amino acids long linked at the NH2 terminus, the sequence of which is: (formula: see text). The molecular size, the hydrophobic nature, and the other properties of the peptide are consistent with the "leader" or "signal" piece found in the precursors of many other secretory proteins. This suggests that alpha-fetoprotein, the synthesis of which is limited primarily to fetal development, is produced in the form of the precursor as are secretory proteins in the adult tissues.

Amino Acid Sequence↗
PubMed1976

Intracellular distribution of alpha-fetoprotein and albumin messenger RNAs in developing mouse liver.

Intracellular distribution of active mRNAs for alpha-fetoprotein (alphaFP) and albumin in fetal and adult mouse liver was studied. Livers were fractionated into nucleus and cytoplasm. The latter was further fractionated by sucrose density-gradient centrifugation into four subfractions, the top fraction containing soluble components, the 1.0 M sucrose layer containing primarily 80S ribosomes, the 1.5 M sucrose layer containing light polysomes and the pellets containing heavy polysomes. RNA was extracted from each fraction and its ability to direct the synthesis of alphaFP and albumin was determined in a mouse sarcoma 180 cell-free system. Distribution of alphaFP and albumin mRNAs in fetal mouse liver was similar; 2% in the nucleus, 98% in the cytoplasm, of which more than 90% was found in the polysome fractions. The results suggest that alphaFP and albumin mRNAs, once formed, are quickly and efficiently utilized for protein synthesis. The major proportion of albumin mRNA in adult mouse liver was also found to be associated with polysomes. However, the amount of translatable alphaFP mRNA was low in all subcellular fractions examined, suggesting that transcription or processing of alphaFP mRNA is defective in adult mouse liver.

Aging↗
PubMed1976

Preparation of active run-off 80S ribosomes and their subunits from mouse liver.

A method is described for the preparation of active "run-off" 80S ribosomes and 40S and 60S subunits of mouse liver. A polysome preparation was incubated at 37 degrees C for 10 min under the condition for protein synthesis (4 mM Mg2+, 100 mM KCL). Puromycin (10 mM)and 2 M KCL were added to a final concentration of 0.1 mM and 500 mM, respectively, and the reaction mixture was further incubated at 37 degrees C for 10 min. This latter treatment destabilized small polysomes and "stuck" 80S particles, which were remaining after the first incubation, leading to complete release of 40S and 60S particles. Thus, the present method minimized variations in yield of subunits due to polysome preparations and preincubation conditions. The subunits were separated by sucrose density-gradient centrifugation or recovered by precipitation following reassociation into 80S particles (run-off 80S). The reformation of 80S particles from the subunits occurred spontaneously at 5 mM Mg2+ and 100mM KCL. The isolated 40S and 60S subunits, separately, showed low phenylalanine-incorporating activity in the presence of poly(U), but when recombined, polymerized up to 10 phenylalanine residues per couple.

Amino Acyl-tRNA Synthetases↗
PubMed1975

Consequences of methotrexate inhibition of purine biosynthesis in L5178Y cells.

Addition of 1 muM methotrexate to cultures of L5178Y cells results in an initial inhibition of thymidine, uridine, and leucine incorporation into acid-insoluble material followed, after about 10 hr, by a partial recovery in the extent of incorporation of these precursors. Acid-soluble adenosine triphosphate and guanosine triphosphate concentrations are greatly reduced initially, but guanosine triphosphate concentrations appear to recover partially by 10 hr. Acid-soluble uridine triphosphate and cytidine triphosphate concentrations initially increase after methotrexate treatment but then, with time, they too decline. Hypoxanthine and guanine are more effective than is adenine in overcoming the methotrexate-induced inhibition of thymidine incorporation. These results suggest that, in the presence of methotrexate, guanine nucleotides become limiting for nucleic acid synthesis before adenine nucleotides do. The block of purine de novo synthesis in L5178Y cells by methotrexate is almost complete and is not reversed with time. This suggests that the additional purine nucleotides that are available for nucleic acid synthesis 8 to 10 hr after addition of methotrexate are being derived from nucleic acid breakdown. Consistent with this is the observed reduction in the number of polyribosomes and hence, presumably in messenger RNA levels.

Adenine↗
PubMed1975

Inhibition of DNA chain growth by alpha-2'-deoxythioguanosine.

Mecca lymphosarcoma cells were incubated with (35-S)-alpha-2'-deoxythioguanosine for 8 hr and DNA was analyzed in alkaline sucrose gradients. 35-S radioactivity was found exclusively in a low-molecular-weight fraction. Pulse-chase experiments showed that 35-S-containing DNA fragments formed during the pulse were not incorporated into high-molecular-weight DNA following the chase. These results, together with the previous observation that (35-S)-alpha-2'-deoxythioguanosine was found predominantly in the terminal nucleoside position of DNA chains, suggested that alpha-2'deoxythioguanosine, once incorporated, terminates chain elongation.

Animals↗