Studies on three mutagen-sensitive mutants of mouse L5178Y cells. I. Characterization of the hybrids between L5178Y and mutagen-sensitive mutants

Three mutagen-sensitive mutants, MS-1, M10 and Q31, have been isolated from mouse L5178Y cells. MS-1 cells are sensitive to methyl methanesulfonate (MMS), M10 cells are cross-sensitive to X-rays, MMS and 4-nitroquinoline 1-oxide (4NQO), and Q31 cells are cross-sensitive to UV and 4NQO. Lines resistant to 6-thioguanine (TGr) and 5-bromo-2'-deoxyuridine (BUr) were isolated from L5178Y and these three mutagen -sensitive mutants. All the TGr lines were sensitive to 5-bromo-2'-deoxyuridine and HAT medium and all the BUr lines were sensitive to 6-thioguanine and HAT medium. The hybrids homozygous for the mutagen-sensitive markers showed nearly the same sensitivity to UV, 4NQO, X-rays and MMS as their parental TGr and BUr lines. The hybrids constructed by fusing L5178Y BUr and TGr lines from each of MS-1, M10 and Q31 displayed the normal UV, X-ray and MMS resistancy of L5178Y cells. Thus the UV-, X-ray- and MMS-sensitive markers in MS-1, M10 and Q31 were recessive in somatic cell hybrids. The 4NQO-sensitive phenotype, however, behaved codominantly in somatic cell hybrids.

Studies on three mutagen-sensitive mutants of mouse L5178Y cells. II. Complementation analyses between two methyl methanesulfonate-sensitive mutants and between two 4-nitroquinoline-1-oxide-sensitive mutants

Three mutagen-sensitive mutants, MS-1, M10 and Q31, were isolated from mouse L5178Y cells. MS-1 cells are sensitive to methyl methanesulfonate (MMS), M10 cells are cross-sensitive to X-rays, MMS and 4-nitroquinoline-1-oxide (4NQO); and Q31 cells are cross-sensitive to UV and 4NQO. MMS-, X-ray- and UV-sensitive markers in these mutants behaved recessively in hybrids between pairs of these mutants as in hybrids between L5178Y and these mutants as reported before (Shiomi et al., 1982b). Complementation analyses were carried out by forming hybrids between two MMS-sensitive mutants (MS-1 and M10) and between two 4NQO-sensitive mutants (M10 and Q31). MMS and 4NQO survivals were measured in these hybrid cells. MS-1 and M10 were found to belong to different complementation groups for MMS-sensitive phenotypes. The hybrid clones between M10 and Q31 were as sensitive to 4NQO as each of the mutants, indicating codominance of 4NQO sensitivity in these mutants. The hybrids constructed with L5178Y and three mutants were stable as to their chromosome constitution for 100 days of cultivation without selective pressure. From the segregation studies on these hybrids, it is concluded that neither the X-ray-sensitive mutation in M10 nor the UV-sensitive mutation in Q31 is located on the X chromosome.

Isolation of UV-sensitive mutants of mouse L5178Y cells by a cell suspension spotting method

We have isolated 56 UV-sensitive mutant clones from a mouse L51 T/t line of L5178Y cells by a cell suspension spotting method. Five mutants have also been isolated from L51 T/t and L5178Y cells by the method reported by Thompson and coworkers (22). We divided the mutants into two groups, "highly sensitive" and "moderately sensitive" mutants, according to their sensitivity to UV irradiation. Fifty-eight mutants were highly sensitive and three were moderately sensitive to UV. The reconstruction experiments indicate that more than 90% of highly sensitive mutants were recovered by the cell suspension spotting method. Frequencies of recovered mutants highly sensitive to UV increased with increasing dose of mutagens. Recovered mutant frequency reached 10(-2) after treatment with 1.5 micrograms/ml of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (survival 0.2%). Eight UV-sensitive mutants were divided into four complementation groups. These mutants were 2-6 times more sensitive to UV than parental L51 T/t cells in terms of D37 (dose required to reduce survival to 37%). Four representative UV-sensitive mutants which are classified into different complementation groups were examined for their sensitivity to killing by UV, 4-nitroquinoline-1-oxide (4NQO), mitomycin C (MMC), X-rays, and MNNG. All four classes of mutants were found to be cross-sensitive to UV, 4NQO, and MMC, but not sensitive to X-rays and MNNG.

A novel mutant of mouse lymphoma cells sensitive to alkylating agents and caffeine

Two-methyl-methanesulfonate-sensitive strains have been isolated, one of which, M10, was cross-sensitive to X-rays as reported before. Sensitivities of parental L5178Y, M10, and newly isolated MS-1 cells to various mutagens were examined. Mutagens tested were UV, X-rays, 4-nitroquinoline 1-oxide (4NQO), caffeine and alkylating agents; methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS) and mitomycin C (MMC). In terms of D37 values, M10 cells were 2.5-7 times more sensitive to EMS, MMC and 4NQO as well as to MMS and X-rays than were parental L5178Y cells, while the new mutant MS-1 was about 3 times more sensitive to MMS, EMS, MMC and caffeine than were parental cells. The characteristics in sensitivities of M10 cells to X-rays, alkylating agents and 4NQO resemble resemble some ataxia telangiectasia cells; and MS-1 cells to alkylating agents and caffeine are novel among mammalian cell mutants so far reported. Sensitivity of M10 cells to mutagens has so far been stable for one year, and that of MS-1 cells was stable for 6 months in continuous culture.

A mouse-cell mutant sensitive to ionizing radiation is hypermutable by low doses of gamma-radiation

The mutant mouse lymphoma cell M10, which is sensitive to methyl methanesulfonate and ionizing radiation, was compared with the parental L5178Y cells for mutation induction after gamma-irradiation. The rate of induced mutations to 6-thioguanine resistance in L5178Y cells was 2-3 X 10(-7) per R, as determined after exposures ranging from 25 to 500 R. The induced mutation frequency per unit dose per locus in M10 cells was about 4 times higher than that in L5178Y cells at the lower doses of exposure (25-75 R), but it declined sharply at the higher doses of gamma-rays (100-150 R). The rate of induced mutation per unit cell killing in M10 cells was nearly the same as that in L5178Y cells when they were compared at the levels of lower cell killing.

Urinary bladder tumors induced by N-butyl-N-(4-hydroxybutyl)nitrosamine in dogs

Clinicopathological, radiological, and histological studies were performed on urinary bladder neoplasia induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in five adult beagle dogs and in ten adult mongrel dogs. Tumors of the urinary bladder developed in dogs given various daily doses of BBN p.o. for different periods. The latent period of tumor induction was 4 years in dogs receiving a daily dose of 80 mg of BBN, 2 to 2.5 years in dogs receiving a daily dose of 160 mg of BBN, and 1.5 years in dogs receiving a daily dose of 240 mg of BBN. The total dose of BBN ingested by the dogs until the first tumors were observed by urological examinations was nearly the same in all groups, 100 to 140 g. These results suggest that there is a correlation between dose and induction time, but further dose-response studies are required. Histologically, tumors of the urinary bladder were transitional cell papillomas or transitional cell carcinomas resembling morphologically those found in human cases. It is possible to observe the process of development of urinary bladder tumors from initial lesions to invasive tumors using routine urological examinations. We believe that this experimental model is valuable for clinicopathological studies of urinary bladder tumors.

Detection of potent mutagens, Trp-P-1 and Trp-P-2, in broiled fish

The potent mutagens Trp-P-1 (3-amino-1, 4-dimethyl-5H-pyrido-[4,3-b]-indole) and Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-b]indole) are known to be produced by pyrolysis of tryptophan [8]. To determine whether such mutagens are produced by cooking foods, the fractions obtained from broiled sardines cooked in the ordinary way were analysed by gas chromatography/mass spectrometry. The results showed that 13.3 ng of Trp-P-1 and 13.1 ng of Trp-P-2 were, in fact, present per gram of broiled sardines.

The pharmacology of 20681-S and 20682-S, 6-oxo-N-cyclopropylmethylmorphinans, as narcotic antagonist analgesics

It has been demonstrated that L-3hydroxy-6-oxo-N-cyclopropylmethylmorphinan methansulfonate (20681-S) and L-3,14-dihydroxy-6-oxo-N-cyclopropylmethylmorphinan methansulfonate (20682-S), have antinociceptive and narcotic antagonistic properties. In the rodent antinociceptive test, the action of 20681-S was more potent and of longer duration than that of morphine and of cyclazocine after subcutaneous or oral administration. The antinociceptive effect of 20682-S ranked between that of morphine and that of pentazocine in the mouse acetic acid-writhing test. Both compounds possessed potent narcotic antagonistic activities, 20682-S being more active than naloxone and oxilorphan and 20681-S being equipotent with cyclazocine. The latent side effects (respiratory depression and fall in blood pressure) and the acute toxicity of 20681-S and 20682-S, were less than those of reference narcotic antagonists or of narcotic antagonist analgesics.

Studies on lactic dehydrogenase of patients with urinary bladder tumors. I. Urinary lactic dehydrogenase

Urinary lactic dehydrogenase (LDH) activity and isozyme pattern were investigated in 38 patients with bladder tumors of various stages and grades and in 10 healthy persons. Urinary LDH activity was markedly elevated and directly correlated with histologic stage and grade of tumors. The urinary LDH isozyme pattern differed significantly from that of normal urine even in early and well-differentiated tumor cases. LDH4 and LDH5 became more prominent as the degree of the histologic stage and grade of the tumor increased. In the patients with tumors more advanced than stage T2, LDH4 and LDH5 were greater than LDH1 plus LDH2, the reverse of what is found in normal urine. As analogous result was obtained in patients with tumors of grade II or higher. No appreciable difference was found in the LDH isozyme pattern of patients with single or multiple tumors although the total activity was greater with multiple tumors. A comparison between LDH isozyme pattern in urine and in tumor tissue was evaluated in 26 patients with a good correlation (r = 0.40, P less than 0.05). Comparison of the results with urine LDH and urine cytology was attempted for each stage and grade. In 5 of 16 cases having negative urine cytology, a positive isozyme index was present and 10 of 13 cases having positive urine cytology had a positive isozyme index. These data suggest that evaluation of urinary LDH combined with urinary cytology might be of value in the diagnosis of bladder tumors and for following patients who have had bladder tumors.

Isolation of UV-sensitive variants of human FL cells by a viral suicide method

A new method (viral suicide method) for the isolation of UV-sensitive mutants is described. Colonies of mutagenized human FL cells were infected with UV-irradiated Herpes simplex viruses and surviving ones which seemed to be deficient in host cell reactivation (HCR) were examined for their UV sensitivity. Nineteen of 238 clones examined were sensitive to UV irradiation at the time of the isolation. After recloning, four of these clones have been studied and two (UVS-1 and UVS-2) of them are stable in their UV sensitivity for 4 months in culture. UV sensitivity of UVS-1, UVS-2, and the parental FL cells are as follows: the extrapolation numbers (n) are 2.2, 2.1, and 1.8 and mean lethal doses (D0) are 2.9, 3.7, and 7.8 J/m2 for UVS-1, UVS-2, and the parental FL cells, respectively- They are no more sensitive than FL cells to X-irradiation. The ability of HCR in UVS-2 cells is apparently lower than that in FL cells, whereas UVS-1 cells are the same as FL cells in the ability.

Hemolytic activity of a togavirus, Getah

A purified toga-alphavirus, Getah (GET), showed optimal hemolytic activity for one-day-old chick red blood cells when incubated at 37 C for 120 min at pH 6.2. Experimental data obtained from various angles, such as pH dependency, inhibition by virus-specific antiserum and by concanavalin A, indicated that the hemolysis was a property of the virus particle itself. Although the mechanism of hemolysis by togaviruses has not been known, our results indicated that viral lipids may participate in this activity since the hemolytic activity was impaired by delipidation procedures.

The fine structure and the protein composition of gamma phage of Bacillus anthracis

The fine structure of gamma phage of Bacillus anthracis was studied by electron microscopy with a negative-staining technique. The phage has a hexagonal head and a long tail without a sheath. By electrophoresis on polyacrylamide gels, the proteins of the phage particles are separate into 10 polypeptides with molecular weights ranging from 140 000 to 12 000.

Inhibiting materials for gamma phage adsorption to the cell wall of Bacillus anthracis, strain Pasteur No. 2-H

Cell wall preparations of Bacillus anthracis, strain Pasteur No. 2-H, were treated with heat or with acetone and ether. Both of the treated cell walls preparations inactivated gamma phage. The centrifuged supernatant of the heat-treated cell walls was fractionated on Sephadex G-200, and four fractions containing reducing sugars were obtained. The first fraction had the phage-inactivating activity. On the other hand, the fourth fraction had no phage-inactivating activity, but strongly inhibited phage adsorption to the cell walls. In the fourth fraction, glutamic acid, alanine, 2,6-diaminopimelic acid and glucosamine were detected by paper chromatography after acid hydrolysis. Authentic D, L-2, 6-diaminopimelic acid and D-glucosamine markedly inhibited phage adsorption to the cell walls. D-Galactosamine, D-mannosamine and L-lysine also showed similar activities. Results suggest the possibility that one or a combination of these substances defines the characteristics of phage adsorption to the cell walls of B. anthracis, strain Pasteur No. 2-H.

Agglutination of Japanese encephalitis virus with concanavalin A

Results of experiments have indicated that reduction in biological activities at high concentrations of Japanese encephalitis virus is caused by aggregates of the virus by concanavalin A. The possibility exists that the concanavalin A binding site is different from hemagglutination and antireceptor sites of Japanese encephalitis virus.