Comparative study of the adverse effects of various radiographic contrast media, including ioversol, a new low-osmolarity medium. II. The complement system and endothelial cells

The effects of ioversol, iohexol, iopamidol and meglumine sodium amidotrizoate (MSA) on the complement system and endothelial cells were investigated. The protein bindings of the radiographic contrast media (RCM), each tested with guinea pig plasma, were less than 1%. When guinea pig serum was incubated with any of the RCM, activation of the complement system, which leads to hemolysis, was not influenced by the nonionic agents, ioversol, iohexol or iopamidol. However, MSA, an ionic agent, significantly reduced hemolytic activity at 370 mgI/ml. Perfusion of the abdominal aorta with nonionic agents did not elicit significant endothelial damage; ioversol induced the least damage among the nonionic RCM, while MSA caused remarkable endothelial damage. Although MSA caused a marked release of endothelin-1 from cultured endothelial cells obtained from porcine aorta, nonionic RCM did not induce significant endothelin-1 release; no influence was elicited by ioversol and iohexol caused a weak suppression, while iopamidol had the opposite effect. These results indicate that ioversol could be used as a safe contrast medium in intravascular administration.

Effect of Tween 80 on formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex

The effects of Tween 80 supplementation of liquid culture medium on the formation of the superficial L1 layer of the Mycobacterium avium-Mycobacterium intracellulare complex (MAC) were examined by serological and scanning electron microscopic experiments. Specific antiserum to the glycopeptidolipids on the L1 layer of M. avium S-139, made in a rabbit, was used for seroagglutination reactions with antigens prepared from strain S-139 grown in medium supplemented with various levels of Tween 80 (0, 0.05, 0.5, 5, and 50 mg/ml). The agglutination titers gradually decreased as the concentration of Tween 80 rose. Scanning electron microscopy showed that the fibrillar materials consisting mainly of glycopeptidolipids on the L1 layer of strain S-139 also disappeared with increases in the concentration of Tween 80. In addition, there was no obvious correlation between (i) the plasmid DNAs and serotypes of MAC and (ii) formation of the L1 layer of MAC. It is therefore concluded that Tween 80 used to supplement liquid culture medium affects formation of the L1 layer, which has been considered to be one of the pathogenic factors of MAC.

Effect of Tween 80 on the growth of Mycobacterium avium complex

The effect of Tween 80 on the growth of Mycobacterium avium complex (MAC) in liquid culture condition was investigated. Observation of the colony-forming units (CFU) and the morphology of MAC with transmission and scanning electron microscopy showed that Tween 80 at 0.05% in the medium (ca. 0.5 mg/ml) had bacteriostatic action and caused cell elongation. Tween 80 at 0.5% or more in the medium (ca. 5 mg/ml) reduced the quantity of MAC glycolipids and also led to false positive or positive results in biochemical tests for mycobacterial identification using nitrate reductase, urease, or arylsulfatase. To determine whether or not surfactants could reduce the MAC permeability barrier, the minimal inhibitory concentration (MIC) of antituberculosis drugs on MAC was determined in liquid medium with or without several kinds of surfactants including Tween 80. Five surfactants including Tween 80 increased the activity of antituberculosis drugs to MAC. These findings suggest that Tween 80 acts directly on the cell wall of MAC.

Sex differences in cognitive abilities: a cross-cultural perspective

Studies in Western cultures have indicated significant sex differences in certain cognitive abilities. To determine whether similar differences occur in a non-Western culture, this study administered a cross-linguistic battery of tests to high school students in Japan and America. In both cultures, girls averaged significantly higher scores on a Story Recall test, the Digit-Symbol test and a Word Fluency test whereas boys achieved significantly higher scores on a Mental Rotation test. The analysis of standardized test scores further indicated that the size of the sex difference was culture-independent in three out of these four cases. These results are discussed in the context of the GESCHWIND and GALABURDA [Cerebral Lateralization, Biological Mechanisms, Associations and Pathology, Bradford Books, Cambridge, Massachusetts] account of the contribution of testosterone to left-right asymmetries in early cerebral development.

Restriction fragment length variations and chromosome mapping of two mouse metallothionein genes, Mt-1 and Mt-2

Restriction endonuclease fragment length variations (RFLVs) were found through the use of cDNA probes for metallothionein genes 1 (Mt-1) and 2 (Mt-2) in the mouse. RFLVs were detected in restriction patterns generated by BglII and XbaI in the Mt-1 gene and by PvuII in the Mt-2 gene. All laboratory strains carry the Mt-1a and Mt-2a alleles. Among strains of wild origin, some Western European subspecies (Mus mus domesticus and M. m. brevirostris) also carry the Mt-1a and Mt-2a alleles. In contrast, a European subspecies (M. m. musculus) and the great majority of subspecies from East Asian countries (M. m. molossinus, Chinese mice of wild origin, and M. m. yamashinai) carry the Mt-1b and Mt-2b alleles. A domesticus strain from Bulgaria and two castaneus strains from Thailand and Philippines carry the intermediate combination of Mt-1b and Mt-2a alleles. Using the RFLVs, we mapped the Mt-1 and Mt-2 genes on chromosome 8, and they appear to be very closely linked since no recombination was observed between them in any of the mice examined. Data from three-point cross tests showed that the recombination frequencies are 4.31% between Os and Mt, 15.52% between Mt and Prt-2, and 19.83% between Os and Prt-2. The gene order of Os-Mt-1,Mt-2-Prt-2 has been confirmed.

Linkage analysis of the mutation locus in the eye lens obsolescence (Elo) mouse

To map precisely the mutation locus of eye lens obsolescence (Elo) on mouse chromosome 1, subsequent linkage analysis was achieved using backcross mating between 129/SvSl-Elo (Elo/+) and 129/SvSl (+/+). Mouse genomic DNAs from 17 strains including the Elo mutant mouse were first digested with several restriction enzymes and analyzed by hybridization using gamma 2- and gamma 4-crystallin cDNAs as probes. Restriction endonuclease DraI showed distinct RFLP patterns in both cases. When gamma 2-crystallin cDNA was used as the probe, two strong bands were observed at 4.0 and 2.4 kb in the majority of strains, but the former fragment shifted to the 3.4-kb position in 129/SvSl-Elo (Elo/Elo) and CFO. The polymorphism between 4.0- and 3.4-kb fragments corresponded to the gamma 1-crystallin locus (Cryg-1), and that of the 2.4-kb one, to the gamma 2-crystallin locus (Cryg-2). Mouse DNAs were also analyzed by hybridization using gamma 4-crystallin cDNA (Cryg-4). In this case, 3.4- and 3.0-kb fragments were observed in Elo and wild-type mice, respectively. The backcross offsprings were analyzed with respect to Elo, Idh-1, Cryg-1, and Cryg-4 loci. Among 223 mice analyzed, recombination between Elo and Idh-1 loci was observed in three offsprings; and that between Cryg-1 or Cryg-4 and Idh-1 loci, in one offspring. No recombination occurred between Cryg-1 and Cryg-4 alleles.

Plasmid profiles of Mycobacterium avium complex isolated from swine

Twenty strains of Mycobacterium avium complex (MAC) isolated from swine and five strains from humans were examined for drug susceptibility and plasmid content. Four strains of swine origin and two strains of human origin harbored plasmid DNAs differing in molecular weights. No relationship between plasmid contents and drug resistance was observed. Southern DNA-DNA hybridization showed that small plasmids from swine MAC strains were homologous to those from human origin at the nucleotide level.

New antibiotics, resorcinomycins A and B: antibacterial activity of resorcinomycin A against mycobacteria in vitro

Resorcinomycin A, N-[(S)-alpha-guanidino-3,5-dihydroxy-4-isopropylphenylacetyl]glyci ne, S-RSM-A, a new antibiotic produced by Streptoverticillium roseoverticillatum, has an antibacterial spectrum directed towards mycobacterial species. It is not active against Gram-negative and Gram-positive bacteria, except mycobacteria and weakly active against mycoplasmas. In vitro activities of the S-, R- and S,R-isomers of RSM-A against atypical mycobacterial strains were compared with those of streptomycin (SM) and kanamycin (KM) by 2-fold agar dilution methods using Middlebrook 7H10 agar medium. Although R-RSM-A and S,R-RSM-A were comparable or inferior to both antibiotics, the antimycobacterial activity of S-RSM-A was superior to that of SM and KM.

Restriction fragment length polymorphism and chromosome mapping of a mouse homeo box gene, Hox-2.1

Restriction endonuclease fragment length polymorphisms (RFLPs) were found using the cDNA probe Hox-2.1 for the homeo box-2.1 gene in the mouse. Polymorphism was detected in restriction patterns generated by fragments from HindIII digestion. The great majority of laboratory strains of mice carries the Hox-2.1a allele. Only two laboratory strains carry the Hox-2.1b allele. Among strains of wild origin, the European subspecies (Mus m. domesticus, M. m. brevirostris, and M. m. musculus) and some Asian subspecies (M. m. castaneus) carry the Hox-2.1a allele. The subspecies from Far Eastern countries (M. m. molossinus, Chinese mice of wild origin, and M. m. yamashinai) carry the Hox-2.1b allele. Using the RFLP, the Hox-2.1 gene was mapped on chromosome 11. Three-point cross test data showed that the recombination frequency is 29.6% between the Hba and the Hox-2.1 genes and 23.5% between the Hox-2.1 and the Es-3 genes. The gene order of Hba-Hox-2.1-Es-3 has been confirmed.

Suppression of lens gamma-crystallin encoded by Len-1 in the mutant mouse with eye lens obsolescence (Elo)

Eye lens obsolescence (Elo) is a heritable, autosomal dominant eye disorder in mice. The Elo mutation lies close to the Len-1 locus on mouse chromosome 1, and it was speculated that the Elo locus affects the expression level of gamma-crystallin. To clarify this, we used the BASO-DALT system to compare the amount of lens gamma-crystallin between Elo and normal mice. The lens extracts from 10-day-old Elo mice revealed the same profiles and expression levels of alpha- and beta-crystallins as those of +/+ mice. Among gamma-crystallins, the amounts of the components encoded by Len-1 were lower than wild-type levels, but that encoded by Len-2 was not in the Elo mouse. NaDodSO4-gel analysis revealed that the lower gamma-crystallin level could be detected as early as the 14-day stage in the lens of the Elo mouse embryo. The suppression of gamma-crystallin gene expression in Elo mice was examined at the mRNA level. The concentration of gamma 2-crystallin mRNA in Elo mice lens was estimated at 1/13 of that of normal lens, indicating that a small amount of transcript production from gamma-crystallin genes may cause the low level of gamma-crystallin in Elo lens.

Structural study of immunoaffinity-purified DNA polymerase alpha-DNA primase complex from calf thymus

The DNA polymerase alpha-DNA primase complex was purified over 17,000-fold to near homogeneity from calf thymus using an immunoaffinity column. Sodium dodecyl sulfate gel electrophoresis revealed three polypeptides with molecular weights of 140, 50 and 47 kDa, in a ratio of 1:2:0.25. The complex showed a sedimentation coefficient of 9.7 S, a Stokes radius of 56 A and a native molecular weight of 250-260 kDa. Taken together, the data suggest that the calf thymus dNA polymerase alpha-DNA primase complex is essentially a heterotrimer of large (140 kDa) and small (50 kDa) subunits in a ratio of 1:2, with a globular conformation. Electron-microscopic studies of the complex revealed a spherical particle of 120 A in diameter, in agreement with the physiochemical results. The binding of the complex to DNA was also demonstrated.

Detection of proliferative cells in dysplasia, carcinoma in situ, and invasive carcinoma of the uterine cervix by monoclonal antibody against DNA polymerase alpha

The distribution of DNA polymerase alpha-positive cells in neoplasia of the uterine cervix and in normal cervical epithelium was studied using a monoclonal antibody against DNA polymerase alpha. The positive cells were found only in the parabasal layer of normal cervical epithelium and only in the nonkeratinized areas of the cancer nests of invasive keratinizing carcinoma. Most cells in cancer nests of an invasive nonkeratinizing carcinoma were found to be DNA polymerase alpha-positive. In cases of mild or moderate dysplasia DNA polymerase alpha-positive cells were found only in the lower half of the epithelium. DNA polymerase alpha-positive cells in severe dysplasia to carcinoma in situ were distributed throughout the full thickness of the epithelium. The percentages of DNA polymerase alpha-positive cells in mild or moderate dysplasia, severe dysplasia to carcinoma in situ, and invasive carcinoma were 32.2%, 45.7%, and 53.7%, respectively. The authors previously developed immunohistochemical methods for detecting DNA polymerase alpha by monoclonal antibody that allowed the proliferative activity of cells in normal and neoplastic tissues to be estimated.

Characterization of DNA primase separated from DNA polymerase alpha-DNA primase complex of calf thymus

It has been shown that DNA primase activity is tightly associated with 10S DNA polymerase alpha from calf thymus (Yoshida, S. et al. (1983) Biochim. Biophys. Acta 741, 348-357). In the present study, the primase activity was separated from DNA polymerase alpha by treating purified 10S DNA polymerase alpha with 3.4 M urea followed by a fast column chromatography (Pharmacia FPLC, Mono Q column equilibrated with 2 M urea). Ten to 20 % of the primase activity was separated from 10S DNA polymerase alpha by this procedure but 80-90% remained in the complex. The separated primase activity sedimented at 5.6S through a gradient of glycerol. The separated primase was strongly inhibited by araATP (Ki = 10 microM) and was also sensitive to salts such as KCl (50% inhibition at 30 mM). The primase used poly(dT) or poly(dC) as templates efficiently, but showed little activity with poly(dA) or poly(dI). These properties agree well with those of the primase activity in the DNA polymerase alpha-primase complex (10S DNA polymerase alpha). These results indicate that the calf thymus primase may be a part of the 10S DNA polymerase alpha and its enzymological characters are preserved after separation from the complex.

Characterization of a Mr = 56,000 polypeptide associated with 10S DNA polymerase alpha purified from calf thymus using monoclonal antibody

Existence of a Mr = 56,000 polypeptide associated with 10S DNA polymerase alpha was shown by production of a monoclonal anti-calf thymus 10S DNA polymerase alpha antibody secreted from a hybridoma line named 3H1. The antibody bound three polypeptides with Mr = 180,000, 56,000 and 32,000 in hydroxylapatite fraction of 10S DNA polymerase alpha by immunoblot. The antibody co-precipitated the polypeptides with the large polypeptide (Mr = 150,000-140,000) of 10S DNA polymerase alpha with the aid of second antibody. Among three polypeptides, the Mr = 56,000 polypeptide was co-purified with DNA polymerase alpha through DNA-cellulose chromatography and repeated sucrose rate-zonal centrifugations. The Mr = 56,000 polypeptide was still associated with 10S DNA polymerase alpha after second sucrose rate-zonal centrifugation, but the amount of it was reduced. The polypeptide was banded at pH 7.2-8.0 and displayed microheterogeneity in respect of isoelectric point by isoelectrofocusing with 7 M urea, and showed weak DNA-binding property after blotting onto a nitrocellulose. The antibody against the polypeptide precipitated DNA polymerase alpha from human, rat, and mouse, and Mr = 56,000 and 32,000 polypeptides were detected in these DNA polymerase alpha fractions by immunoblot. These results suggest that the polypeptide with Mr = 56,000 may take part in the DNA polymerase reaction.

Arabinosylnucleoside 5'-triphosphate inhibits DNA primase of calf thymus

It has been shown that DNA primase activity is tightly associated with 10S DNA polymerase alpha from calf thymus and that the ribonucleotide-dependent DNA synthesis is more sensitive to araCTP than DNA-primed DNA synthesis (Yoshida, S., et al. (1983) Biochim. Biophys. Acta 741, 348-357). Here we measured DNA primase activity using poly(dT) template or M13 bacteriophage single-stranded DNA template and primer RNA synthesis was coupled to the reaction by Escherichia coli DNA polymerase I Klenow fragment. By this method, the primer RNA synthesis can be measured independently of the associating DNA polymerase alpha. Using poly(dT) template, it was found that arabinosyladenine 5'-triphosphate (araATP) strongly inhibited DNA primase in competition with rATP. The apparent Ki for araATP was 21 microM and the ratio of Ki/Km (for rATP) was as low as 0.015. With poly(dI, dT) or M13 DNA, it was shown that araCTP also inhibited DNA primase in the similar manner. Product analysis using [alpha-32P]rATP showed that araATP inhibited the elongation of primer RNA. However, it is not likely that arabinosylnucleotides act as chain-terminators, since incubation of primer RNA with araATP did not abolish its priming activity. From these results, it is suggested that arabinosylnucleotide inhibits the initiation as well as elongation of Okazaki fragments in mammalian cells.

Large polypeptides of 10S DNA polymerase alpha from calf thymus: rapid isolation using monoclonal antibody and tryptic peptide mapping analysis

The polypeptides recognized by a monoclonal antibody against calf thymus DNA polymerase alpha (secreted from a hybridoma CL22 -2- 42B , Nucleic Acids Res. (1982) 10, 4703-4713) were identified by the immunoblot method as the large polypeptides of the partially-purified 10S DNA polymerase alpha fraction. Using an immunoprecipitation technique with the monoclonal antibody, a rapid immunological isolation of the polypeptides has been achieved. By this method, the large polypeptides with Mr = 140,000, 145,000, and 150,000 were isolated from a partially-purified preparation of 10S DNA polymerase alpha. On the other hand, the polypeptides with Mr = 150,000, 180,000, and 240,000 were obtained from a crude extract of calf thymus. Tryptic peptide maps showed that the large polypeptides with Mr = 150,000, and 180,000 were very similar in primary structure and that the structures of Mr = 180,000 and 240,000 polypeptides contained partially common sequences. Among these polypeptides, the Mr = 150,000 polypeptide was shown to correlate with the enzyme activity. These results suggest that the large polypeptide of 10S DNA polymerase alpha is initially synthesized as Mr = 180,000 or larger polypeptide, then converted to the form with Mr = 150,000. The Mr = 140,000 and 145,000 polypeptides in the purified preparation may be artificial products formed during purification.

Intracellular localization and metabolism of DNA polymerase alpha in human cells visualized with monoclonal antibody

Indirect immunofluorescence microscopy with monoclonal antibody against DNA polymerase alpha revealed the intranuclear localization of DNA polymerase alpha in G1, S, and G2 phases of transformed human cells, and dispersed cytoplasmic distribution during mitosis. In the quiescent, G0 phase of normal human skin fibroblasts or lymphocytes, the alpha-enzyme was barely detectable by either immunofluorescence or enzyme activity. By exposing cells to proliferation stimuli, however, DNA polymerase alpha appeared in the nuclei just prior to onset of DNA synthesis, increased rapidly during S phase, reached the maximum level at late S and G2 phases, and was then redistributed to the daughter cells through mitosis. It was also found that the increase in the amount of DNA polymerase alpha by proliferation stimuli was not affected by inhibition of DNA synthesis with aphidicolin or hydroxyurea.

DNA primase associated with 10 S DNA polymerase alpha from calf thymus

Among multiple subspecies of DNA polymerase alpha of calf thymus, only 10 S DNA polymerase alpha had a capacity to initiate DNA synthesis on an unprimed single-stranded, circular M13 phage DNA in the presence of ribonucleoside triphosphates (DNA primase activity). The primase was copurified with 10 S DNA polymerase alpha through the purification and both activities cosedimented at 10 S through gradients of either sucrose or glycerol. Furthermore, these two activities were immunoprecipitated at a similar efficiency by a monoclonal antibody directed against calf thymus DNA polymerase alpha. These results indicate that the primase is tightly bound to 10 S DNA polymerase alpha. The RNA polymerizing activity was resistant to alpha-amanitin, required high concentration of all four ribonucleoside triphosphates (800 microM) for its maximal activity, and produced the limited length of oligonucleotides (around 10 nucleotides long) which were necessary to serve as a primer for DNA synthesis. Covalent bonding to RNA to DNA was strongly suggested by the nearest neighbour frequency analysis and the DNAase treatment. The DNA synthesis primed by the RNA oligomers may be carried out by the associating DNA polymerase alpha because it was strongly inhibited by araCTP, resistant to d2TTP, and was also inhibited by aphidicolin but at relatively high concentration. The primase preferred single-stranded DNA as a template, but it also showed an activity on the double-stranded DNA from calf thymus at an efficiency of approx. 10% of that with single-stranded DNA.

Production and characterization of monoclonal antibody against 10S DNA polymerase alpha from calf thymus

One hybridoma cell line that produces an antibody directed against 10S DNA polymerase alpha purified from calf thymus was obtained. The monoclonality of the antibody was tested by sodium dodecyl sulfate polyacrylamide gel electrophoresis, isoelectrofocusing and antibody subclass determination. The antibody specifically recognized the 10S DNA polymerase alpha and 6.5S DNA polymerase alpha-2 from calf thymus, but not 6.5S DNA polymerase alpha-1. The antibody precipitated both polypeptides of 140-150,000 and 46-50,000 dalton of 10S DNA polymerase alpha. The antibody also recognized the DNA polymerase alpha purified from human cells, but did pig DNA polymerase alpha only partially. The antibody did not crossreact with rat DNA polymerase alpha, calf DNA polymerase beta, virus DNA polymerase and E. coli DNA polymerase I. This antibody will be a useful tool for studying the mechanism of DNA replication in eukaryotic cells.

Analysis of calf thymus DNA polymerases alpha and beta and terminal deoxynucleotidyl transferase on two-dimensional polyacrylamide gels

Calf thymus DNA polymerases alpha and beta [EC 2.7.7.7] and terminal deoxynucleotidyl transferase [EC 2.7.7.31] were analyzed on two-dimensional gel slabs. DNA polymerase beta appeared as a single spot on two-dimensional gel at the position of 40,000 daltons and pI 8.0 using non-equilibrium pH gradient gel electrophoresis for the first-dimensional run. By overlapping gel slabs, it was possible to identify the distinct spot of DNA polymerase beta among many polypeptide spots of a crude enzyme fraction. 10S DNA polymerase alpha showed two clusters of polypeptide spots on two-dimensional gel slab. One cluster was composed of three large polypeptides of 140,000-150,000 daltons and another was composed of four smaller polypeptides of 46,000-50,000 daltons. All these spots were arranged in a narrow pI range (6.5-6.8) although each spot showed a distinct pI value. Purified terminal deoxynucleotidyl transferase showed three polypeptides of 57,000, 42,000, and 33,000 daltons at similar pI values (7.0-7.2). Each polypeptide consisted of plural spots which differed slightly in pI but were the same in molecular weight. These results suggest a microheterogeneity of polypeptides of terminal deoxynucleotidyl transferase as well as those of 10S DNA polymerase alpha.

10 S DNA polymerase alpha of calf thymus shows a microheterogeneity in its large polypeptide component

The 10 S DNA polymerase alpha from calf thymus (Masaki, S., and Yoshida, S. (1978) Biochim. Biophys. Acta 521, 74-88) has been purified to near homogeneity. The most purified fraction obtained by repeated sucrose rate-zonal centrifugation contained three large polypeptides of 150,000, 145,000, and 140,000 daltons and three to four smaller polypeptides ranging from 43,000 to 50,000 daltons. A good resolution of these polypeptides was achieved on a sodium dodecyl sulfate-polyacrylamide linear gradient gel (5-20%) which was stained by the silver stain method. The three large polypeptides were also observed in the more crude fractions prepared in the presence of three kinds of protease inhibitors. By a peptide mapping analysis, it was revealed that these three polypeptides have a similar primary structure. Treatments of the enzyme with alkaline phosphatase, phosphodiesterase, and neuraminidase did not affect the gel pattern. These results indicate that the 10 S DNA polymerase alpha of calf thymus has a microheterogeneity in terms of the large polypeptide component. Among these three large polypeptides, the two polypeptides of 150,000 and 145,000 daltons disappeared by keeping the sucrose gradient fraction at 4 degrees C in the absence of glycerol, while the 140,000-dalton polypeptide was well preserved. The poly(rA)oligo(dT)-dependent activity of 10 S DNA polymerase alpha was selectively lost under this condition.

Further characterization of a poly(rA) . oligo(dT)-dependent activity of multiple DNA polymerase alpha from calf thymus

DNA polymerase alpha (EC 2.7.7.7) from calf thymus has been separated into three molecular species, i.e., 10 S DNA polymerase alpha, 6.5 S DNA polymerase alpha-1 and 6.5 S DNA polymerase alpha-2 (Masaki, S. and Yoshida, S. (1978) Biochim, Biophys. Acta 531, 74-88; Yoshida, S., Yamada, M., Masaki S. and Seneyoshi, M. (1979) Cancer Res. 39, 3955-3958). Among these three, 10 S DNA polymerase alpha and 6.5 S DNA polymerase alpha-2 were found to copy efficiently poly(rA) . oligo(dT), a template-primer, which was thought to be specific for DNA polymerase gamma or beta. 6.5 S DNA polymerase alpha-1, however, could not use the ribopolymer as a template. The poly(rA) . oligo(dT)-dependent activities of DNA polymerase alpha species differed markedly from those with activated calf thymus DNA in sensitivity to various reagents: the former was inhibited more than 80% by 80 mM KCl, while the latter was stimulated somewhat. Furthermore, aphidicolin, a specific inhibitor of DNA polymerase alpha, did not inhibit the poly(rA) . oligo(dT)-dependent activity. 2',3'-DideoxyTTP, a potent inhibitor of DNA polymerase beta or gamma, slightly inhibited the reactions with poly(rA) . oligo(dT), while it did not inhibit the reactions with activated DNA. The apparent Km values for dTTP on poly(rA) . oligo(dT) template were 260 and 70 microM for 10 S alpha and 6.5 S alpha-2, respectively; these values were much higher than those obtained on activated DNA template (8-10 microM).

Cooperation of terminal deoxynucleotidyl transferase with DNA polymerase alpha in the replication of ultraviolet-irradiated DNA

The amount of DNA synthesis in vitro with the ultraviolet-irradiated poly-(dT) . oligo(rA) template initiators catalysed by DNA polymerase alpha (Masaki, S. and Yoshida, S., Biochim. Biophys. Acta 521, 74--88) decreased with the dose of ultraviolet-irradiation. The ultraviolet irradiation to the template, however did not affect the rate of incorporation of incorrect deoxynucleotides into the newly synthesized poly(dA). The addition of terminal deoxynucleotidyl transferase to this system enhanced the DNA synthesis to a level which is comparable to that of the control and it concomitantly increased the incorporation of the mismatched deoxynucleotide into the newly synthetized poly(dA) strands. On the other hand, with an unirradiated template initiator, the misincorporation was only slightly enhanced by the addition of terminal deoxynucleotidyl transferase. The sizes of newly synthetized DNA measured by sedimentation velocities were found to be smaller with the ultraviolet-irradiated templates but they increased to the control level with the addition of terminal deoxynucleotidyl transferase to the systems. These results suggest that terminal deoxynucleotidyl transferase can help DNA polymerase alpha to "bypass" thymine dimers in vitro by the formation of mismatched regions at the positions opposite to pyrimidine dimers on the template.

Utilization of 2'-deoxy-6-thioguanosine 5'-triphosphate in DNA synthesis in vitro by DNA polymerase alpha from calf thymus

Chemically synthesized beta-2'-deoxy-6-thioguanosine 5'-triphosphate, a putative active form of beta-2'-deoxy-6-thioguanosine, was used efficiently as a substrate for DNA synthesis catalyzed by DNA polymerase alpha from calf thymus. The deoxythioguanylate was incorporated into DNA by replacing deoxyguanylate and supported the further elongation of DNA chains on activated calf thymus DNA. In contrast, DNA polymerase beta used beta-2'-deoxy-6-thioguanosine 5'-triphosphate at a much lower rate. The reaction product of DNA polymerase alpha, i.e., 6-thioguanine-containing DNA, adsorbed specifically to the organomercurial agarose column, and showed a peak of UV absorption at 342 nm, which is characteristic of thioguanine.

Novel properties of DNA polymerase beta with poly(rA).oligo(dT) template-primer

Purified DNA polymerase beta of calf thymus can utilize poly(rA).oligo(dT) as efficiently as poly(dA).oligo(dT) or activated DNA as a template primer. The poly(rA).oligo(dT)-dependent activity of DNA polymerase beta was found to differ markedly from the DNA-dependent activity of the same enzyme (with either activated calf thymus DNA or poly(dA).(dT)10) in the following respects. 1) Poly(rA)-dependent activity was strongly inhibited by natural DNA from various sources or synthetic deoxypolymer duplexes at very low concentrations (less than 0.5 microgram/ml) at which the DNA-dependent activity was affected to a much smaller extent, if at all. 2) Poly(rA)-dependent activity was inhibited by N-ethylmaleimide more strongly than DNA-dependent activity measured at 37 degrees C, while it was resistant to this reagent at 26 degrees C. 3) The curves of the activity versus substrate concentration were sigmoidal in the poly(rA)-dependent reaction but hyperbolic in the activated DNA-dependent reaction. A kinetic study suggested that the association of beta-enzyme protomers may be required to copy the poly(rA) strand.

Utilization in vitro of deoxyuridine triphosphate in DNA synthesis by DNA polymerases alpha and beta from calf thymus

DNA polymerases alpha and beta (EC 2.7.7.7.) from calf thymus could utilize dUTP as a substrate for DNA synthesis as well as DNA polymerase I of Escherichia coli. Deoxyuridylate was incorporated into DNA by replacing deoxythymidylate and supported the further elongation of DNA chains on activated DNA or on the intiated homopolymers, poly(dA) . (dT)10 and poly(rA) . (dT)10. The rate of the incorporation of deoxyuridylate into DNA varied from 50 to 160% of that of deoxythymidylate, depending on the nature of the template primers and the species of DNA polymerase used. The apparent Km values for dUTP were very similar to those for dTTP. Uracil DNA-glycosylase excised efficiently the uracil residues in products of DNA polymerase reactions with either activated calf thymus DNA or initiated homopolymers.

10-S DNA polymerase from calf thymus which copies both poly(rA) . oligo(dT) and activated DNA

A novel DNA polymerase, which could use both poly(rA) . oligo(dT) and activated calf thymus DNA efficiently as template-primers, was purified 20 000-fold from calf thymus extract. These activities were co-purified throughout successive column chromatographies and banded at the same position in either electrofocussing (pI = 6.5--7.0) or sucrose rate-zonal centrifugation (10--10.5 S). The most purified fraction (DNA-cellulose fraction) possessed specific activities of 3900 units/mg of protein with poly(rA) . oligo(dT) and 32 000 units/mg of protein with activated DNA. The poly(rA) . oligo(dT)-dependent activity differed from the previously described DNA polymerase gamma from other sources in the following ways: 1. The activity was inhibited by 100--300 mM KCl and and 80 mM potassium phosphate buffer. 2. The activity was 4-fold higher at 26 degrees C than at 37 degrees C. 3. The Km value for dTTP was 2.6--3.0 . 10(-4) M, which is several hundred-fold greater than that of DNA polymerase gamma. 4. Mn2+ was essential for the reaction and could not be replaced by Mg2+. The activated DNA-dependent activity shared many properties with DNA polymerase alpha, except that it was less sensitive to N-ethylmaleimide and anti-alpha polymerase immunoglobulin G. The 10-S DNA polymerase was dissociated into 8.5-S and 3.3-S by treatment with Triton X-100.

Inhibition of DNA polymerase-alpha and -beta of calf thymus by 1-beta-D-arabinofuranosylcytosine-5'-triphosphate

1-beta-D-Arabinofuranosylcytosine 5'-triphosphate (araCTP), an active form of a inhibitor of DNA replication, 1-beta-D-arabinofuranosylcytosine (araC) was tested for its inhibitory action on the DNA polymerase-alpha and -beta (EC 2.7.7.7) purified from calf thymus. The reaction of DNA polymerase-alpha was shown to be more sensitive to the inhibition by araCTP than that of DNA polymerase-beta. The mode of the inhibition by araCTP was competitive to dCTP in the reaction catalysed by either DNA polymerase-alpha or -beta. The Ki value of DNA polymerase-beta for araCTP was 32 micron; eight times higher than that of DNA polymerase-alpha (4 micron) for this inhibition.

Effects of polyamines on in vitro dna synthesis by DNA polymerases from calf thymus

DNA synthesizing reactions catalyzed both large and small species of calf thymus DNA polymerase (DNA polymerase-alpha and -beta) [EC 2.7.7.7] were stimulated to comparable extents by the presence of spermidine or spermine, and it was not possible to differentiate these two species in terms of their sensitivities to polyamines. Optimal concentrations for stimulation were 0.5-1.0 mM for spermidine and 2-10 mjM for spermine. Excess polyamines strongly inhibited the reactions. The modes of stimulation were as follows: 1) Stimulation was observed with templates bearing long single-stranded sections when either natural DNA or synthetic homopolymer-oligomer duplex was used. 2) The nautral DNA-dependent reaction was stimulated by polyamines at suboptimal concentrations of Mg2+; the apparent Km value for Mg2+ was lowered on adding polyamines, while the Vmax value was unchanged. When synthetic homopolymer-oligomer duplex was used as a template, the reaction was stimulated spermidine even at the optimal concentration of Mn2+. 3) Polyamines markedly influenced the salt requirements of the reactions of DNA polymerase. Spermidine could replace salts such as KC1 or NaC1 at concentrations less than 1/100 of those of salts.