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Yeast-based reporter assays are useful for detecting various genotoxic chemicals. We established a genotoxicity assay using recombinant strains of Saccharomyces cerevisiae, each containing a reporter plasmid with the secretory luciferase gene from Cypridina noctiluca, driven by a DNA damage-responsive promoter of the yeast RNR3 gene. This system detected the genotoxicity of methyl methanesulphonate (MMS) as sensitively as conventional yeast-based reporter assays, using the β-galactosidase gene in a concentration-dependent manner; it also detects four other genotoxic chemicals, allowing us to monitor DNA damage easily by skipping the cell extraction process for the assay. We examined Cypridina luciferase levels induced by MMS and three antitumour agents using a set of BY4741-derived deletion mutants, each defective in a DNA repair pathway or DNA damage checkpoint. Luciferase activities were particularly enhanced in mutant strains with mms2 Δ and mag1 Δ by exposure to MMS, rad59 Δ and mlh1 Δ to camptothecin and mms2 Δ and mlh1 Δ to mitomycin C, respectively, compared with their parent strains. Enhanced reporter activities were also found in some DNA repair mutants with cisplatin. These observations suggest that this Cypridina secretory luciferase reporter assay using yeast DNA repair mutants offers convenient and sensitive detection of the potential genotoxicity of numerous compounds, including antitumour drugs and studying the mechanisms of DNA damage response in yeast.

Retigeranic acid, C25H38O2, a sesterterpene isolated from the lichen, Lobaria retigera group, L. isidiosa VAIN. var. subisidiosa ASAH., was separated by high performance liquid chromatography into two components, retigeranic acid A (minor) (1) and B (major) (2). Crystals of both components were subjected to X-ray crystallographic analysis. The crystal parameters are monoclinic space group P21, Z=4 with a=24.10(3), b=12.86(1), c=7.412(9) A, β=96.5(1)° for 1 and a=24.067(17), b=12.614(9), c=7.457(5) A, β=96.30(7)° for 2.Retigeranic acids A and B were proved to be S and R stereoisomers at C-18, respectively. The absolute configurations of other parts of the structure of retigeranic acids are assumed to be identical, as they have previously been determined by the X-ray anomalous dispersion method on the p-bromoanilide derived from native retigeranic acid.

Based upon the autopsy findings, the incidence of distant metastasis was studied to seek the relativity between the method of treatment and the TNM system at the time of initial examination on 31 cases with squamous cell carcinoma in the maxilla-facial region. The results are summarized as follows: 1) The incidence of distant metastasis among all of these cases was 58 per cent. 2) There was no significant difference in the incidence between the groups with radiation therapy and chemotherapy. 3) There was no relativity with the TNM system. 4) In the group with radiation therapy, the incidence at the “sites of the movable mucosa” was significantly higher than that at the “sites of the non-movable mucosa.” 5) There was no relationship to the performance of radical neck dissection.