The selective isolation ofMicromonospora from soil by cesium chloride density gradient ultracentrifugation

Summary A novel method is described for the selective isolation ofMicromonospora from mixed microbial populations in soil. Microorganisms were released from soil by sonication, and the bulk of the soil debris was discarded by low-speed centrifugation. The supernatant microbial suspension was concentrated and applied to a continuous, linear (1.1–1.6 g/ml) gradient of CsCl which was then centrifuged at high speed. The gradient was fractionated, and each fraction was diluted and plated on a medium devoid of antimicrobial agents.Micromonospora were found in the 1.35–1.42 g/ml density band. Occasionally,Bacillus species were also obtained in this density range, but other nonfilamentous bacteria or actinomycetes were usually not observed. This technique allowed the isolation of portions of the soilMicromonospora population which were suppressed by conventional isolation techniques employing heat and antibiotics.     

Cesium chloride density distributions in preparative equilibrium ultracentrifugation

A computer program has been developed for calculating equilibrium centrifugation density distributions by direct integration of tabulated data, which eliminates curve fitting. Error calculations showed that a high accuracy is required for the measurement of the data needed a determine a density distribution either by computation or by direct measurements. In particular, the variation in drop size during the fractionation of the contents of a centrifuge tube have been investigated by computer simulation. A direct measurement of the drop size indicated that it may increase somewhat during collection. In addition, plots are presented of the dependence upon seven parameters of the centrifugation required to approach equilibrium to a desired degree (based on the formula of Van Holde and Baldwin).     

Glutaraldehyde and glyoxal fixation of ribonucleoproteins for their analysis by cesium chloride equilibrium gradient centrifugation]

Conditions for fixation of different RNP (ribosomes, poliribosomes, informosomes) by glutaraldehyde and glyoxal for their subsequent analysis in CsCl density-gradient has been developed. Higher dialdehyde concentration and longer incubation time should be used for fixation of ribosomes and polyribosomes than for that of informosomes. For the fixation of all RNP studied their incubation with 0.01 M (0.1%) glutaraldehyde for several minutes is sufficient. Much higher concentration of the fixating agent (about 0.2-0.5 M i. e. 1-3%) and more prolonged time of incubation (in order of several 10 hours) are needed for the fixation of the RNP in the case of glyoxal. Conditions for selective aldehyde fixation of informosomes in the presence of ribosomes and polyribosomes has been developed.     

Purification of Toxoplasma gondii oocysts by cesium chloride gradient

We describe the use of a cesium chloride (CsCl) gradient as an improvement for the purification of Toxoplasma gondii oocysts from concentrated suspensions. After concentration by sucrose flotation, this technique gives a > 96% recovery of very pure unsporulated or sporulated oocysts, but requires "fresh" oocysts (< or = 10 weeks of age). This material is suitable for biochemical and immunological analyses of environmentally resistant T. gondii oocysts.     

Clastogenic effects of cesium chloride on mouse bone marrow cells in vivo

Clastogenic effects of cesium chloride (CsCl) on mouse bone marrow cells in vivo following oral administration were studied after 24 h. The incidence of chromosome aberrations increased linearly with increasing concentrations of the chemical from 1/20th to 1/5th of the LD50. The frequency of cell division was also enhanced by the lower doses but higher doses were mitostatic. This report is the first on the clastogenicity of cesium on animals.     

The localization of radioactive cesium in bovine muscle tissue]

The form in which radioactive caesium is present in muscular tissue has been investigated. It has been found that protein agents under study do not form stable complexes with radioactive caesium. It is suggested that caesium-137 is partially bound by muscular cell membranes upon meet storage.     

Immunoelectrophoretic analysis of mink sera lipoproteins fractionated by preparative ultracentrifugation]

Using the method of preparative ultracentrifugation, four lipoprotein fractions were obtained differing in hydrate density. By means of immunoelectrophoretic analysis of the fractions, it is found that mink sera (except chilomicrons) contains at least five lipoproteins; two of them, lipoproteins 2 and 3, bind the major bulk of lipids. Lipoprotein 1 is of very low density. Lipoprotein 2 mostly belongs to the fraction with density less than 1.100 g/ml, although antigenically identical molecules with higher density were identified. Lipoprotein 3 is much more heterogeneous antigenically, electrophoretically and in its density (from 1.006 to 1.210 g/ml and higher). This protein seems to contain several structurally similar, though not identical, apoproteins. Lipoproteins 4 and 5 are very dense (more than 1.210 g/ml) and are weakly stained with Sudan black. These data, together with the results obtained in our previous studies, indicate that lipoproteins 2 and 4 are marked with genetically alloantygenic determinants.