Search PubMed⌕ Search

Biomedical subjects

Y Mano

Publications and source records attributed to Y Mano.

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

Association of DNA polymerase alpha and beta with rough endoplasmic reticulum in sea-urchin eggs and changes in subcellular distribution during early embryogenesis.

The subcellular distribution of DNA polymerase alpha and beta was examined in unfertilized eggs and embryos of the sea-urchin, Hemicentrotus pulcherrimus. In unfertilized egg homogenates, prepared in sucrose solution containing 5 mM 2-mercaptoethanol and 5 mM MgCl2, DNA polymerases equilibrated in isospycnic centrifugation as a single peak at a buoyant density of 1.261 g/cm3 (band I). This indicates that DNA polymerases associate with a cytoplasmic organelle. Band I was converted to bands II (1.227 g/cm3), III (1.177 g/cm3) and IV (1.146 g/cm3) by EDTA treatment. The RNA content of bands I, II, III and IV was approximately 0.34, 0.25, 0.10 and 0.04 mg/mg protein respectively. In isokinetic and isopycnic centrifugations both DNA polymerase and RNA cosedimented and coequilibrated. These results suggest that bands I, II, III and IV contain various amounts of ribosomes on a common structure. Examination by electron microscopy indicated that bands I, II, III and IV contained mainly monolayered membrane vesicles with different amounts of bound ribosomes. The content of ribosomes varied in the order: band I > band II > band III > band IV. Each band contained DNA polymerase with sedimentation coefficients of 5.8-7.6 S (sensitive to N-ethylmaleimide and aphidicolin) and 3.2 S (insensitive to these drugs). We conclude that almost all of DNA polymerases alpha and beta are localized on the rough endoplasmic reticulum in unfertilized eggs. Mixing experiments suggest that the association is specific and is not an artifact of homogenization. During development of embryos DNA polymerases associated with the membrane decreased with concomitant increase in the nuclear fraction. This suggests that the enzymes migrate from the cytoplasm to the nucleus. It is discussed that the role of the endoplasmic reticulum as a storage site of DNA polymerases in unfertilized eggs and the mechanism of translocation of DNA polymerases from the cytoplasm to the nucleus during early embryogenesis.

Animals↗
PubMed1980

Evaluation of different decompression tables by agarose gel method.

Nine different decompression tables were evaluated by the method of bubble formation in the agarose gel, the result of which is summarized as follows: 1) The number of bubbles formed in the agarose gel corresponded well with the exposed pressure. 2) The technique of this method was simple and the number of bubbles was accurately counted. 3) This method was considered useful for examining the decompression tables. 4) Using an equation obtained from the experiment with the same agarose gel, the critical number of bubbles at the end of decompression was found to be 6.6. 5) From this point of view, the R.N.P.L. Table of England and Mano's Model I Table were considered to be excellent. 6) The first stop at the deeper level during the ascent resulted in a smaller number of bubbles at the end of decompression, indicating the effectiveness of this procedure for the prevention of decompression sickness.

Atmospheric Pressure↗
PubMed1979

The mode of inhibitory action by pyridoxal 5-phosphate on DNA polymerase-alpha and -beta.

The kinetics of the inhibition of DNA polymerases-alpha and -beta from sea urchin embryos by pyridoxal 5-phosphate were studied. The inhibition of DNA polymerase-alpha activity by pyridoxal 5-phosphate was competitive with activated DNA but noncompetitive with each deoxynucleoside triphosphate. With poly(dC)-oligo(dG)12-18 as a template-primer, however, the inhibition of DNA polymerase-alpha was competitive with dGTP but noncompetitive with the template-primer. These results suggest that DNA polymerase-alpha interacts with activated DNA and poly(dC)-oligo(dG)12-18 in different ways. The inhibition of DNA polymerase-beta by pyridoxal 5-phosphate was competitive with deoxynucleoside triphosphate using activated DNA as a template-primer and noncompetitive with activated DNA. Using poly(rA)-oligo(dT)12-18 as a template-primer, DNA polymerase-beta activity yielded sigmoid curves against both dTTP and the template-primer concentrations and was inhibited by pyridoxal 5-phosphate noncompetitively with respect to both dTTP and the template-primer. These results indicate that the inhibitory mode of DNA polymerase-alpha by pyridoxal 5-phosphate is different from that of DNA polymerase-beta.

Animals↗
PubMed1979

Mutual homology of mouse immunoglobulin gamma-chain gene sequences.

We have assessed the relative homology of mouse immunoglobulin heavy-chain gene sequence using complementary DNAs (cDNAs) synthesized against gamma-chain mRNAs (gamma 1, gamma 2a, gamma 2b, and gamma 3) purified from mouse myelomas. cDNAs complementary to the gamma-chain mRNAs did not cross-hybridize with the mu- and alpha-chain mRNAs, whereas they cross-hybridized to significant extents (22--66%) with the gamma-chain mRNAs of other subclasses. The heterologous hybrids formed, however, melt at 5--13 degrees C lower temperatures as compared to the homologous hybrids, indicating that significant portions of the heterologous hybrids are mismatched. The rates of the cross-hybridization reactions are 2- to 17-fold slower than those of the homologous hybridization reactions. Therefore, the gamma-chain gene sequences of four subclasses share a part of homology with each other, but they are different enough to be measured separately. Cross-hybridization analysis indicate that the gamma 2a and gamma 2b genes are the most closely related, while the gamma 1 and gamma 3 genes are the least related among the gamma subclass genes.

Animals↗
PubMed1979

Identification of gamma-like DNA polymerase from sea urchin embryos.

A gamma-like DNA polymerase devoid of DNA polymerase-alpha and -beta activities was prepared from the nuclear fraction of blastulae of the sea urchin, Hemicentrotus pulcherrimus. The enzyme sedimented at the position of an approximate sedimentation coefficient of 3.3 S under high salt conditions by sucrose gradient centrifugation. An isoelectric point was determined to be pH 5.8. The enzyme activity was sensitive to sulfhydryl blocking reagents. Poly(rA) . oligo(dT)12--18 followed by poly(dA) . oligo(dT)12--18 was effectively utilized as a template-primer. From the above results, this polymerase seems to resemble the vertebrate DNA polymerase-gamma.

Animals↗
PubMed1979

Inhibition by aphidicolin of cell cycle progression and DNA replication in sea urchin embryos.

We have recently found that aphidicolin, a tetracyclic diterpene-tetraol produced by several fungi, blocks DNA synthesis of sea urchin embryos by interfering with the activity of DNA polyermase alpha. These cells fail to proliferate in the presence of aphidicolin. In continuation of these studies, we determined the drug-sensitive stage in the first cell cycle of the sea urchin Clypeaster japonicus embryo. In continuous exposure to aphidicolin (2 micrograms/ml) from five minutes after fertilization, mitotic division of the embryo was completely suppressed. Embryos were exposed to the drug at progressively later intervals and their capability for cytokinesis was examined. Evidence was thereby obtained that aphidicolin acts at the S-period to inhibit DNA synthesis resulting in developmental arrest of the embryo.

Animals↗
PubMed1979

The mode of inhibitory action by aphidicolin on eukaryotic DNA polymerase alpha.

The mode of action by aphidicolin on DNA polymerase alpha from the nuclear fraction of sea-urchin blastulae was studied. The inhibition of DNA polymerase alpha by aphidicolin was uncompetive with activated DNA and competitive with the four deoxynucleoside triphosphates using activated DNA as a template-primer. For truncated (residual or limited) DNA synthesis with only three deoxynucleoside triphosphates, aphidicolin inhibited the residual synthesis more strongly in the absence of dCTP than in the absence of each of the other three deoxynucleoside triphosphates. The inhibition was reversed with excess dCTP but not with the other three deoxynucleoside triphosphates. That is, aphidicolin inhibited DNA polymerase alpha by competing with dCTP with a Ki value of 0.5 microgram/ml and by not competing with the other three deoxynucleoside triphosphates. dTMP incorporation with the activated DNA was more sensitive to aphidicolin than dGMP or dTMP incorporation with poly(dC). (dG)12-18 or poly(dA) . (dT)12-18. Similar results were obtained for DNA polymerase alpha (B form) from mouse myeloma MOPC 104E.

Animals↗
PubMed1979

Growth and DNA synthesis of bacteriophage phi x174 in a dnaP mutant of Escherichia coli.

phi X174am3trD, a temperature-resistant mutant of bacteriophage phi X174am3, exhibited a reduced ability to grow in a dnaP mutant, Escherichia coli KM107, at the restrictive temperature (43 degrees C). Under conditions at which the dnaP gene function was inactivated, the amount and the rate of phi X174am3trD DNA synthesis were reduced. The efficiency of phage attachment to E. coli KM107 at 43 degrees C was the same as to the parental strain, E. coli KD4301, but phage eclipse and phage DNA penetration were inhibited in E. coli KM107 at 43 degrees C. It is suggested that the dnaP gene product, which is necessary for the initiation of host DNA replication, participates in the conversion of attached phages to eclipsed particles and in phage DNA penetration in vivo in normal infection.

Adsorption↗
PubMed1979

Evaluation of standard decompression schedule by agarose gel method.

The Standard Decompression Schedule was evaluated by the method of bubble formation in agarose gel, the result of which can be summarized as follows: 1) The number of bubbles formed in agarose gel corresponded well with the exposed pressure. 2) The technique of this method was simple and the number of bubbles was accurately counted. 3) Eventually, this method was useful for examining the decompression schedules. 4) It is not always safe to follow the Standard Decompression Schedule in some pressure conditions. 5) As to the period of time that a person is able to tolerate a high pressure condition, the prescription of the Standard Decompression Schedule is not necessarily correct. 6) The number of bubbles was small by the proper decompression schedule, for example, in the cases of exposure above the 60-meter depth of water. 7) This method can be applied for the prevention of decompression sickness when the agarose gel samples are attached to the workers during the compressed air work. 8) The number of bubbles was inconsistent with the coefficient of body pressure (1. N2 in the body), therefore it is not necessarily safe to rely only on the coefficient of body pressure. 9) To prevent osteonecrosis, the Standard Decompression Schedule is not proper, a deeper first stop and slower ascent being recommended.

Decompression↗
PubMed1979

Bubble production in agarose gels subjected to different decompression schedules.

The relative effectiveness of seven different (military, commercial, and experimental) decompression schedules in reducing bubble formation within aqueous gels has been evaluated quantitatively under rigorously controlled conditions. Specifically, visual counts have been conducted of the bubbles formed in highly purified agarose gels subjected to the different decompression schedules. The order of effectiveness among these schedules in reducing bubble formation in the agarose gel samples was as follows: Model 1 greater than Royal Naval Physiological Laboratory approximately French Ministry of Labor greater than Yount et al. greater than Japanese Department of Labor greater than United States Navy greater than French Navy. It was concluded that the depth at which slow decompression commences is a major factor, along with the total decompression time, in determining the extent of bubble formation.

Decompression↗
PubMed1978

Differential susceptibilities of DNA polymerases-alpha and -beta to polyanions.

The effects of various polyanions including synthetic polynucleotides on DNApolymerases-alpha and -beta from blastulae of the sea urchin Hemicentrotus pulcherrimus and HeLa cells were studied. Only DNA polymerase-alpha was inhibited by polyanions, such as polyvinyl sufate, dextran sulfate, heparin, poly(G), poly(I), poly(U) and poly(ADP-Rib). Of the various polynucleotides tested, poly(G) and poly(I) were the strongest inhibitors. Kinetic studies showed that the Ki value for poly(G) was 0.3 microgram/ml and that poly(G) had 20-fold higher affinity than activated DNA for the template-primer site of DNA polymerase-alpha. Poly(U) and poly(ADP-Rib) were also inhibitory, but they were one hundredth as inhibitory as poly(G) or poly(I). Poly(A), poly(C), poly(A).poly(U) AND POLY(I).poly(C) were not inhibitory to DNA polymerase-alpha. In contrast, DNA olymerase-beta was not affected at all by these polyanions under the same conditions.

Animals↗
PubMed1978

Relationship between CO2 levels and decompression sickness: implications for disease prevention.

Extensive data concerning the incidence of decompression sickness among workers participating in the deepest caisson operation in Japan to date have been collected and analyzed for the period April through August, 1976. When the bottom pressure was between 3.0 and 3.2 ATA, the incidence of decompression sickness was 3.05%; subsequently, the incidence was only 0.96% between 3.2 and 3.4 ATA. The man lock (i.e., decompression chamber) had never been ventilated during the former group of decompressions and the level of CO2 had ranged between 1.8 and 2.3% (v/v); in the latter group of decompressions, the CO2 level ranged between 0.3 and 0.8% with ventilation. All other conditions, including the decompression table used, were the same. Moreover, based upon the nature of the muscular activity required of the caisson workers just prior to decompression, their most common site of affliction was found to lie within the body region where the highest tissue tensions of CO2 would be expected during decompression.

Adult↗