Simple differential Giemsa staining of sister chromatids after treatment with photosensitive dyes and exposure to light and the mechanism of staining

The essential steps of the 33258 Hoechst-Giemsa method for differential chromatid staining consist of (1) 33258 Hoechst treatment, (2) exposure to light, and (3) Giemsa staining. The staining was shown to be a function of the concentration of 33258 Hoechst and the light exposure. The dye was successfully replaced by various metachromatic dyes such as thionine. Two simple methods are proposed. Failure of the pale stained chromatids to restore Giemsa affinity with urea and trypsin and the diminished Feulgen reaction after light exposure suggest that not masking proteins but photolysis of the BrdU-incorporation chromatid components in the present of photosensitive dyes play a role in the differential staining.

Mucosal damage induced by various gastric carcinogens in the glandular stomach of the rat

The process of erosion formation in the glandular stomach of the rat given single and multiple intragastric doses of 100 mg N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)/kg body weight, was studied histologically, histochemically, and ultramicroscopically and compared with erosion induced by other gastric carcinogens and erosion-forming chemicals. The acute effect of several nongastric carcinogens on the glandular mucosa was also studied. The earliest degenerative transformation, fatty change, was found in the surface mucous cells within 1 hour a one-pulse intragastric dose of 100 mg MNNG/kg body weight; the change gradually progressed into deeper glandular cells and after three successive doses, erosion was complete in every rat. Ultrastructurally, four main glandular cells showed essentially similar degenerative alterations. Fatty change was also induced by other gastric caricnogens such as 4-nitroquinoline-1-oxide, methylnitrosocyanamide, methylnitrosourea, N-2-fluorenylacetamide, and iodacetamide, a noncarcinogenic alkylating agent. Mucosal damage induced by acetylsalicylic acid and thermal burn did not show fatty change. Nongastric carcinogens failed to induce mucosal damage. The relationship of the carcinogen-induced fatty change and mucosal damage to carcinogenesis was discussed.

Occurrence of Pyruvate Orthophosphate Dikinase in the Succulent Plant, Kalanchoë daigremontiana Hamet. et. Perr

Pyruvate orthophosphate dikinase was detected from Kalanchoë daigremontiana Hamet. et. Perr., a succulent plant with crassulacean acid metabolism. Enzyme activity was similar to that of maize extracts. Two enzymes demonstrating pyruvate orthophosphate dikinase activity from K. daigremontiana and Zea mays were found to be partially identical from enzyme-inhibition and immunoprecipitin tests with maize enzyme antiserum. A time course study demonstrated that pyruvate orthophosphate dikinase activity in leaf extracts was dependent upon exposure of leaves to light.

Acute cytogenetic effect of 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2, a food preservative) on rat bone marrow cells in vivo

The cytogenetic effects of 2(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2), a food preservative used in Japan, on rat bone marrow cells in vivo were studied. The aberrant metaphase cells in the bone marrow increased and reached the peak level 6 h after intraperitoneal injection of 240 mg/kg body weight of AF-2 and returned to the normal level within 24 h. A dose-response relationship was obtained using 4-240 mg/kg of AF-2. Chromosome aberrations were also induced after oral administration of 30-240 mg/kg. The aberrations were mostly chromatid breaks and the distribution among and within chromosomes was similar to those induced by a carcinogen, 7, 12-dimethylbenz(a)anthracene (DMBA). The present results provide the first evidence of in vivo cytogenetic effects of AF-2 on mammalian cells and, together with the evidence of mutagenicity already proved in other organisms, warn of the possible genetic hazards to cells exposed to this compounds.

Immunological analysis of glycolipids and lipopolysaccharides derived from various mycoplasmas

The lipids and lipopolysaccharides of five mycoplasmas were examined for complement-fixing activity to antimembrane rabbit sera. Total glycolipid fractions and the aqueous phenol fractions (lipopolysaccharides) from the membranes of Acholeplasma laidlawii, A. modicum, A. axanthum, and Mycoplasma neurolyticum exhibited significant antigenic activity. The glycolipids and phosphoglycolipids from Thermoplasma acidophilum were either anticomplementary or did not react due to their extreme hydrophobic nature. High activity was found using the lipopolysaccharide of T. acidophilum. The pure glycolipids and phosphoglycolipids of the Acholeplasma and Mycoplasma species also exhibited significant complement-fixing activity. Acylation of the sugar residues of these lipids reduced or negated complement-fixing activity. Double cross-reactions between the glycolipids of A. laidlawii and A. modicum appeared to be due to mono- and diglucosyl diglycerides of identical structure. Specificity of glycolipid structure was noted by the absence of cross-reactions between A. laidlawii and M. neurolyticum, the glycolipids of which differ only in the nature of the glucose linkages. The existence of lipopolysaccharides in the membranes of mycoplasmas and their complement-fixing activity in the presence of antimembrane sera suggest their possible importance as specific antigenic determinants.

Studies on transfer ribonucleic acids and related compounds. 8(1). Further studies on aromatic phosphoramidates as a protecting group for phosphomonoesters

Stability of aromatic phosphoramidates was studied using 2',3'-O-dibenzoyluridine 5'-phosphoramidates and N,2',3'-O-tribenzoylcytidine 5'-phosphate. The effect of dicyclohexylcarbodiimide in this mixture was investigated. Decomposition of the anilidate was slower in the presence of DCC. Substituted anilidates of uridine 5'-phosphate were synthesized and the stability of these amidates in anhydrous pyridine was studied.2'-O-Benzoyluridine 3'-phosphoranilidate and the corresponding beta-naphthylidate were compared in their stabilities in anhydrous pyridine, 50% aqueous pyridine and 80% acetic acid. 2'-O-Benzoyluridine 3'-phosphoro-beta-naphthylidate was used for synthesis of dinucleotides.

Role of erythropoietin in 7,12-dimethylbenz(a)anthracene induction of acute chromosome aberration and leukemia in the rat

The incidence of chromosome aberrations in rat bone marrow, examined 6 hr after the administration of 7,12-dimethylbenz(a)anthracene, was significantly enhanced by induction of anemia 0-48 hr before the carcinogen treatment and was suppressed by induction of polycythemia. The suppressive influence of polycythemia was reversed by sheep erythropoietin injected shortly before or after the carcinogen injection; this suppressive effect was proportional to the dose of erythropoietin used. These data suggest that erythropoietin is essential to make bone-marrow cells susceptible to chromosome aberrations with 7,12-dimethylbenz(a)anthracene. The incidence of carcinogen-induced leukemia was also increased by anemia and suppressed by polycythemia induction.

Cytogenetic studies of leukemia induced by 6,8,12-and 7,8,12-trimethylbenz(a)anthracene

Cytogenetic studies on 64 rat leukemias induced with 7,8,12- and 6,8,12-trimethylbenz(a)anthracene were performed. Highly distinctive changes were found repeatedly in one special pair of chromosomes. 10 leukemias (15.6%) showed the presence of stemline(s) with trisomy of the largest telocentric chromosome (C-1 trisomy). Another chromosome abnormality, elongation of one of the pairs of the same chromosome (long C-1), was found in 5 leukemias (7.8%) as the predominant stemline and in 7 other cases as a small cell population. This chromosome abnormality, despite slight differences in their elongation rate, was defined as a new specific chromosome abnormality. Other chromosome abnormalities not related with C-1 chromosome were found in 8 cases (12.5%). The remaining 41 leukemias (64.1%) had the predominant stemline with normal karyotype. From this study it appears that three structurally different hydrocarbon carcinogens, 7,12-dimethylbenz(a)anthracene and 7,8,12- and 6,8,12-trimethylbenz(a)anthracene act on blood-forming cells by a common specific mechanism.

Transfer RNA: A comparison by gel electrophoresis of the tRNA in HeLa cytoplasm, HeLa mitochondrial fraction, and E. coli

A class of transfer RNA separable from the majority of transfer RNA by gel electrophoresis has been observed in E. coli and in the mitochondrial fraction of HeLa cells but not in HeLa cytoplasm. The size of this class of transfer RNA, as judged by its mobility on polyacrylamide gel, is intermediate between the major part of the transfer RNA and 5S RNA. It exists in part associated with the ribosomes, and its amino acid acceptor activity is different from the major class of transfer RNA.