Effects of alkylating agents on lymphocytes from controls and from patients with Fanconi's anemia

Summary The frequency of sister chromatid exchanges (SCE) and chromosome aberrations and the dynamics of cell division in peripheral blood lymphocytes of four patients with Fanconi's anemia were studied after in vitro exposure to alkylating agents TEPA and mitomycin.SCE frequency was significantly increased even after very low doses of mutagens, while chromosome aberrations were significantly increased only after high doses (0.160 g/ml mitomycin and 10^-5 M TEPA). The responses of Fanconi's anemia cells and control cells did not differ significantly. The increased frequency of both SCE and chromosome aberrations was accompanied by gradual delay of cell division, which was most conspicuous in cells from patients with Fanconi's anemia.     

Induction of chromosomal disturbances other than tetraploidy in barley root tips by colchicine treatment

Barley embryos were treated by 0.1% colchicine for 30 min. Samples of root tips were fixed after 4 h, 8 h and 12 h. In the first sample,c-metaphases, normal metaphases and anaphases were present jointly. Inc-metaphases, chromosomes sometimes tended to make two groups with 7 chromosomes in each. In anaphases, lagging chromosomes, tripolar and multipolar anaphasos were found. No chromosomal aberrations were detected in anaphases and metaphases. No chromosome disturbances were found in root tips sampled 8 h and 12 h after colchicine treatment.     

Effect of various inhibitors on the multiplication of BLE bacteriophage inBacillus licheniformis

A total of 40 substances were tested for their inhibitory effect on the multiplication of a bacteriophage in a growing culture ofBacillus licheniformis and their influence on bacitracin production. Acriflavine was the only substance which, at a concentration of 3 μg ml^-1, completely suppressed phage multiplication while having no effect on the growth ofBacillus licheniformis and on the production of the antibiotic.     

Histocompatibility-2 system in wild mice

Six semicongenic lines carrying differentt haplotypes on the background of strain C57BL/10Sn (B10.t strains) and a (B10 ×T/t ⁰) F₁ hybrid were tested against one another in the mixed lymphocyte reaction (MLR) and cell-mediated lymphocytotoxicity (CML) assays. In every instance, the MLR results paralleled those of the CML typing: strain combinations giving a positive result in one assay gave a positive result in the second; combinations in which no response was observed in the MLR assay also failed to kill target cells specifically in the CML assay. Furthermore, the MLR and CML results were concordant with the results of the serological typing of these strains, as reported previously by us. The combined results suggest sharing ofH-2 hyplotypes between B10.t¹² and B10.t³², between B10.t⁶ and B10.t^w1, and between B10.t^w2 and (B10. ×T/t ⁰) F₁. These data support the conclusion, reached in our previous publication, that members of the samet-complementation group, with few exceptions, shareH-2 haplotypes.     

Origin of sclerotia-like cells in submerged Claviceps purpurea producing clavine alkaloids

Ultrathin sectioning of submerged mycelium of Claviceps purpurea Tul. producing clavine alkaloids revealed yeast-like budding resulting in asexual sporesblastospores. These deciduous spores were born by extended hyphal cells and retained the same ultrastructure of cell organelles. Both the extended hyphae and the blastospores resembled the cells of ergot sclerotial tissue. A surface culture of C. purpurea Tul. producing no alkaloids was used as a reference.     

Penicillinamidohydrolase inEscherichia coli

Substrate specificity of the bacterial penicillinamidohydrolase (penicillinacylase, EC 3.5.1.11) fromEscherichia coli was determined by measuring initial rates of enzyme hydrolysis of different substrates within zero order kinetics. SomeN-phenylacetyl derivatives of amino acids and amides of phenylacetic acid and phenoxyacetic acid of different substituted amides of these acids or amides, structurally and chemically similar to these compounds, served as substrates. Significant differences in ratios of initial Tates of the enzyme hydrolysis of different substrates were found when using a toluenized suspension of bacterial cells or a crude enzyme preparation, in spite of the fact that the enzyme is localized between the cell wall and cytoplasmic membrane, in the so-called periplasmic space.N-phenylacetyl derivatives are the most rapidly hydrolyzed substrates. Beta-phenylpropionamide and 4-phenylbutyramide were not utilized as substrates. The substrate specificity of the enzyme is discussed with respect to a possible use of certain colourless compounds as substrates, hydrolysis of which yields chromophor products suitable for a simple and rapid assay of the enzyme activity.