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Biomedical subjects

M Hatanaka

Publications and source records attributed to M Hatanaka.

At least 361 records · Page 20Linked to original sources
PubMed1977

Uracil phosphoribosyl transferase activity of mycoplasma and infected cell cultures.

Human H.Ep-2 and mouse 3T6 cells infected by Mycoplasma hyorhinis showed an increase in [3H]uracil uptake and a more than 20-fold increase in the activity of uracil phosphoribosyltransferase (UraPRT). Uninfected cell cultures gave background levels of this enzyme activity. A survey of 16 strains of mycoplasma showed 13 to possess UraPRT activity. Rabbit kidney cells (RK13) were infected with eight different strains of four mycoplasma species known to be common cell culture contaminants. Seven of the eight cell cultures showed elevated UraPRT activities four days after infection. This enzyme activity may be of value in monitoring cell cultures for mycoplasma and aid in classification.

Animals↗
PubMed1976

Saturable and nonsaturable process of sugar uptake: effect of oncogenic transformation in transport and uptake of nutrients.

Uptake of sugars into cells by a saturable process increased enormously during and after transformation, and uptake by a nonsaturable process increased significantly but less remarkably compared to controls. The drastic change of uptake rates, observed at around 5 x 10(-3) M sugar during and after transformation, emphasizes the significant observation that transition of the sugar uptake system from a saturable to a nonsaturable process occurs near the physiological concentration of D-glucose normally seen in animal blood. At concentrations below higher than 5 x 10(-3) M, where a saturable process is barely involved, nonsaturable uptakes of D-glucose, D-mannose, D-galactose, 2-deoxy-D-glucose and 3-O-methyl-D-glucose proceed tens to hundreds fold faster than the rate of simple diffusion of L-glucose. These findings suggest that nonsaturable uptake of the sugars known to be substrates for the saturable transport carrier system may not be a physical process or simple diffusion, as observed for L-glucose uptake. Rather, the nonsaturable uptake might be part of the total physiological process which, along with the saturable process, is controlled by a membrane-coordination mechanism. A plausible mechanism is discussed in which negative cooperativity of nutrient uptake, such as that found in bacteria, is involved.

Animals↗
PubMed1975

Murine sarcoma virus related nucleic acid sequences in a non-transforming virus derived from an interspecies pseudotype sarcoma virus.

A number of sarcomagenic viruses recovered from hamster tumors induced originally by Moloney sarcoma virus or several of its mouse pseudotypes appear to be interspecies pseudotypes with structural proteins of hamster type-C viruses and nucleic acid sequences of both mouse and hamster specificity. A non-transforming virus (GLOH-minus) recovered from a sarcomagenic virus preparation obtained from a tumor induced by the Gross pseudotype of Moloney sarcoma virus was previously shown to retain mouse sequences. The ability to discriminate readily between Gross and Moloney viruses by molecular hybridization, especially with regard to thermal stability of inter-strain hybrid molecules, and the stability of Moloney virus sequences in a rat-mouse interspecies pseudotype, made it possible to specify that the mouse virus-specific sequences in GLOH-minus are derived from Moloney virus and not Gross. Thus, even though GLOH-minus is non-transforming in vitro or in vivo, it still retains sequences highly related to Moloney sarcoma virus. The lack of transforming ability is thus probably based on loss or change of specific sequences necessary for transformation at some point in the history of this virus.

AKR murine leukemia virus↗
PubMed1975

Type-C virus-specific nucleic acid sequences in cultured rat cells.

Single-stranded DNA transcripts of rat type-C viruses prepared in the presence of actinomycin D, hybridized specifically to DNA of several rat cell cultures with no obvious qualitative or quantitative differences. Similar products prepared from a pseudo-type sarcoma virus with contributions from rat and mouse type-C viruses hybridized to both rat and mouse cellular DNA, while mouse viral transcripts did not hybridize to rat cell DNA. Viral RNA was detected in all rat cells by means of the rat viral DNA transcripts, with some differences between untreated low-passage cells and sister cultures treated with bromodeoxyuridine or bromodeoxyuridine and methylcholanthrene. Cells treated with both compounds were previously shown to be transformed and turorigenic, and these were distinguishable by kinetic analysis from the control cells.

Amino Acid Sequence↗
PubMed1975

Fate of viral RNA of murine leukemia virus after infection.

[3H]Uridine-labeled Rauscher leukemia virus was used to infect mouse embryo fibroblasts. After the infected cells were separated into nuclear and cytoplasmic fractions nucleic acid was extracted by sodium dodecyl sulfate-phenol-chloroform treatment and analyzed by Cs2SO4 and sucrose density gradient centrifugation. Between 45 and 70 min after infection a transient and synchronized shift of the acid-insoluble radioactive peak toward the RNA-DNA hybrid region occurred in both the nuclear and cytoplasmic fractions. The density of the cytoplasmic hybrid shifted to 1.56 g/ml (RNA equals about 50%), while the sedimentation rate decreased from 36 S to 14 S; however, the density of the nuclear hybrid shifted to 1.58-1.48 g/ml (RNA equals 57-17%, respectively), while its sedimentation rate remained about 65 S. The hybrids in both the nuclear and the cytoplasmic fractions still showed hybrid density after heat denaturation. The processes of the early stages of RNA tumor virus infection are discussed with regard to the functions of viral RNA-dependent DNA polymerase (reverse transcriptase) and a possible integration of viral genetic information into the host chromosome.

Animals↗
PubMed1975

Adenine formation from adenosine by mycoplasmas: adenosine phosphorylase activity.

Mammalian cells have enzymes to convert adenosine to inosine by deamination and inosine to hypoxanthine by phosphorolysis, but they do not possess the enzymes necessary to form the free base, adenine, from adenosine. Mycoplasmas grown in broth or in cell cultures can produce adenine from adenosine. This activity was detected in a variety of mycoplasmatales, and the enzyme was shown to be adenosine phosphorylase. Adenosine formation from adenine and ribose 1-phosphate, the reverse reaction of adenine formation from adenosine, was also observed with the mycoplasma enzyme. Adenosine phosphorylase is apparently common to the mycoplasmatales but it is not universal, and the organisms can be divided into three groups on the basis of their use of adenosine as substrate. Thirteen of 16 Mycoplasma, Acholeplasma, and Siroplasma species tested exhibit adenosine phosphorylase activity. M. lipophilium differed from the other mycoplasmas and shared with mammalian cells the ability to convert adenosine to inosine by deamination. M. pneumoniae and the unclassified M. sp. 70-159 showed no reaction with adenosine. Adenosine phosphorylase activity offers an additional method for the detection of mycoplasma contamination of cells. The patterns of nucleoside metabolism will provide additional characteristics for identification of mycoplasmas and also may provide new insight into the classification of mycoplasmas.

Acholeplasma laidlawii↗
PubMed1975

Effect of UV Light on RNA-Directed DNA Polymerase Activity of Murine Oncornaviruses.

The UV inactivation of RNA-directed DNA polymerase activity of Rauscher leukemia virus was shown to be due to damage to the protein. The UV dose resulting in 37% survival of viral polymerase activity at 254 nm was 2.4 x 10(4) to 3.1 x 10(4) ergs/mm(2). The inactivation rate of p30, a major internal viral protein, was much slower.

Journal Article↗
PubMed1975

Kinetics of murine type C virus-specific DNA synthesis newly infected cells.

Replicating transforming functions of Rauscher leukemia virus (RLV) and the RLV pseudotype of Moloney sarcoma virus in mouse embryo fibroblasts were found to be most sensitive to inhibition by cytosine arabinoside (ara-C) 30 to 90 min after infection. The initiation of intracellular RLV DNA synthesis was detected by nucleic acid hybridization within this time interval. Treatment of infected cells with cytosine arabinoside abolished RLV DNA synthesis. Peak synthesis of the DNA complementary to the infecting RLV genome, the (-) strand, occurred 40 to 60 min after infection. During this interval two s two species of DNA were observed with estimated molecular weights of 0.5 X 10(5) to 1.0 X 10(5) and 3 X 10(6). Peak synthesis of the (+) strand viral DNA occurred 50 to 70 min after infection. The initial species detected had a molecular weight of 1.5 X 10(5) to 4.0 X 10(5) which shifted as a function of time to 3 X 10(6). Both (+) strand species were initially detected in the cytoplasm followed by a rapid (10-min interval) appearance of the faster-sedimenting species in the nucleus. The virus-specific (-) and (+) strand DNA species are presumably unintegrated intermediates in provirus formation.

Cell Transformation, Neoplastic↗
PubMed1975

Size of virus-specific RNA in B-34, a hamster tumor cell producing nucleic acids of type C viruses from three species.

B-34 is the designation of a hamster tumor-derived cell line induced by the Harvey sarcoma virus. This cell line produces virions which contain structural proteins common to edogenous hamster viruses and nucleic acid sequences of hamster, mouse, and rat origin. The sedimentation characteristics of the intracellular virus-specific RNA was determined in sucrose gradients after treatment with dimethylsulfoxide by molecular hybridization using complementary DNA of strict virus specificity. Hamster virus-specific RNA sedimented at 35S (major peak) as is characteristic of productive infection by type C leukemia viruses of other species. Rat virus-specific RNA sedimented at 30S which is characteristic of the sarcoma virus-related genome found in nonproducer cells transformed by Kirsten sarcoma virus. Both Harvey and Kirsten sarcoma viruses contain a related but not necessarily identical 30S rat-specific component which is also found in normal cultured rat cells. Mouse cells producing Harvey sarcoma virus also contain a rat-specific 30S RNA. Mouse virus-derived sequences also sedimented at 30S in B-34 cells and in a similar size range in Harvey virus-infected mouse cells. The possibility that the mouse and rat-derived sequences are present on a single 30S RNA species which would then be related to sarcomagenic potential is one attractive hypothesis suggested by these data.

Animals↗
PubMed1975

Hexose transport in sarcoma virus transformed cells.

Avian and mammalian fibroblast cultures transformed by type C sarcoma viruses show a dramatic enhancement of the rate of hexose transport at the beginning of transformation which is quantitatively and qualitatively different from that seen by variation in culture conditions of nontransformed control cells. The identification of this change as being a transport alteration independent of total glucose metabolism has been shown by use of nonmetabolizable analogues, 2-deoxyglucose, 3-O-methylglucose, and L-glucose. Increased transport rates were not dependent on levels of hexokinase activity. Transport studies of 3-O-methylglucose confirmed these conclusions and further revealed an additional altered nature of hexose transport after transformation by sarcoma virus. 3-O-methylglucose was not only transported more rapidly in the transformed cells than in the parental nontransformed cells, but the sugar "infiltrated" into the transformed cells despite the inhibitory effect of cytochalasin B. This was not seen with control cells. The sarcoma cells were also able to transport L-glucose in contrast to lack of uptake by nontransformed cells. Under conditions in which cell toxicity was not a factor, 2-deoxyglucose and several other sugars present in culture media inhibited transformation by sarcoma viruses. These same sugars reduced the incidence of sarcomas produced by virus in vivo when administered daily to test animals. The transport changes also correlate well with the transformed state as found by other laboratories using temperature-sensitive mutants and revertant cell lines. Collectively these data suggest that manipulation of transport systems may prove useful for control of certain malignancies.

Animals↗
PubMed1974

Mutants of nonproducer cell lines transformed by murine sarcoma virus. 3. Detection and characterization of RNA specific for helper and sarcoma viruses.

BALB/3T3 cells transformed by the Kirsten sarcoma virus (nonvirus producer BALB/3T3 cells) and mutant cell lines derived therefrom by treatment with bromodeoxyuridine (BrdU) were analyzed for expression of virus-specific RNA using single-stranded DNA transcripts of Rauscher leukemia virus (RLV), a virus activated in one of the cell lines (58-2T), and Ki-SV-specific DNA transcript; the latter transcript after removal of all sequences cross-reactive with RLV RNA. The Rauscher virus DNA detected multiple copies of viral RNA in virus-producing cells ( approximately 2.5 x 10(3)/cell) whether infected with RLV or activated to produce virus with BrdU. Nonproducer (NP) cells and normal BALB cells showed small numbers of RNA genomes (70-250/cell) and only partial saturation of the transcript. The intracellular RNA sedimented at 35S (main peak) with a variable minor peak at 20S with the exception of one mutant cell, M-43-2 (main peak at 26-27S). The 58-2T transcript reacted preferentially in NP cells and their derivatives with biphasic kinetics suggesting the possibility of sequences specific for the original transforming virus. The size of Ki-SV specific sequences were 30S in mutant cells whether or not complete virus was being produced and independent of in vivo transplantability.

Animals↗