The effect of valinomycin and nigericin on the efficacy of bacteriophage infection of staphylococcal cells

The effect of ionophore antibiotics, valinomycin and nigericin, on the generation of the membrane potential, the pH gradient and the efficacy of phage infection in tetracycline-resistant staphylococci has been studied. Valinomycin at a concentration of 0.5 microM induces the dissipation of the membrane potential, and nigericin at a concentration of 12.0 microM decreases the value of the pH gradient on the membrane of staphylococci. The separate use of antibiotics has no essential influence on the efficacy of phage infection. The combined use of valinomycin and nigerimycin produces the maximum inhibition of phage infection (64.5%) at the stage of the introduction of DNA into the bacterial cell, which is indicative of a definite role played by the membrane potential and the pH gradient in the transport of phage DNA into staphylococcal cells.     

Partial trisomy 11q as the result of sporadic translocation

Summary Partial trisomy 11q due to a sporadic translocation was found in a mentally retarded girl with multiple abnormalities. The proportion of sporadic translocations involved in the total incidence of partial trisomies is discussed.     

Isolation of Tyr- mutants of facultative methylotrophic Pseudomonas sp. M

A method for isolation of Tyr- mutants of facultative methylotrophic bacteria Pseudomonas sp. M which possess two tyrosine synthesis pathways is presented. The method is based on the two-step blocking of the tyrosine synthesis: the first step of the supplementary pathway of synthesis from phenylalanine, the second being the main pathway from 4-hydroxyphenylpyruvate.     

Assay of DNA-RNA hybrids by S1 nuclease digestion and adsorption to DEAE-cellulose filters.

A fast and accurate assay procedure for DNA-RNA hybrids is described in which exhaustive digestion of unhybridized DNA with S1 nuclease is followed by binding of hybrids to filter discs of DEAE-cellulose. The digested DNA can be efficiently washed from the filters so that background levels of 0.1-0.2% of input tracer DNA can be achieved, in contrast to the much higher (approximately 1-5%) backgrounds obtained using TCA precipitation procedures. Short duplexes, as small as 36 nucleotides in length, which are inefficiently bound to hydroxyapatite, are quantitatively bound to the DEAE-cellulose filters.     

Immunological diagnosis of Mycoplasma pneumonias]

A complex of immunological cell tests with M. pneumoniae antigen (the lymphocyte blast-cell transformation test, the allergic neutrophil alteration test) was carried out in order to establish the correlation between the results of positive seroconversion and the sepcific immunological reactivity of lymphoid cells in pneumonia patients. Mycoplasmic cutireactive allergen, when used for the accelerated diagnosis of mycoplasmic pneumonia in humans, was shown to be specific and safe. Cuti-allergic tests with mycoplasmic allergen allowed to diagnose mycoplasmic pneumonia at early stages (beginning from days 5--7), which ensures the possibility of indicating etiotropic treatment to patients in due time.     

Ultrastructural demonstration of NAD-pyrophosphorylase activity in mouse liver nuclei.

Ultrastructural demonstration of NAD-pyrophosphorylase activity (E.C.2.7.7.1) in isolated mouse liver nuclei was investigated with the use of an electronhistochemical procedure based on the precipitation of pyrophosphate ions with lead ions under conditions permitting simultaneous ATPase inhibition by formaldehyde/ethanol prefixation. In isolated mouse liver nuclei activity of NAD-pyrophosphorylase was found in nucleoli, in interchromatin granules, coiled bodies and strand-like structures in nucleoplasm.