Cryptosporidium oocysts were concentrated by an ether-phosphate-buffered saline sedimentation technique and then separated by density gradient centrifugation. This two-step method yielded highly concentrated oocysts largely free of bacteria and fecal debris.

Two density gradient ultracentrifugation methods, Redgrave et al. (1975. Anal. Biochem. 65: 42-49) and Nilsson et al. (1981. Anal. Biochem. 110: 342-348), currently used for the separation and analysis of plasma lipoproteins were compared with respect to their resolving power and capacity to obtain pure products as a function of time of ultracentrifugation using the same rotor (Beckman SW-40), ...

The isolation of Cowdria ruminantium by means of Percoll density gradient centrifugation permits the recovery of partially purified viable populations of the organism possessing distinctly different densities. These conclusions are based upon results of analyses of density fractions by intravenous inoculation into sheep, protein determination, electron microscopy and enzyme-linked immunosorbent...

New zonal centrifuges can conveniently process as much as five orders of magnitude (10(5)) greater sample volumes than conventional swinging-bucket rotors. The continuous-sample-flow-with-banding versions may be used in series with ancillary purification procedures. Here we have studied the combined process: absorption and elution of influenza virus with barium sulfate followed by concentration...

Correcting Errors Due to Species Correlations in the Marginal Probability Density Evolution Algorithm

An enrichment procedure, yielding plasmid deoxyribonucleic acid preparations normally containing less than 5% chromosomal contamination, has been devised for the isolation of plasmids from virtually all species of streptococci. The procedure is rapid, reproducible, and inexpensive, requiring no radioisotopes or density gradient centrifugation. The procedure can be used for routine screening of ...

A method was developed to obtain purified cryptosporidium oocysts from fecal samples. Oocysts were initially collected by centrifugation through a sucrose density gradient and further purified by passage through glass bead columns. The purified oocysts were antigenically active and sufficiently pure for immunological studies.

The nature of the arrangement of 16S and 23S ribosomal RNA genes on the Bacillus subtilis chromosome was studied by means of a Cs(2)SO(4) density gradient centrifugation technique after complexing DNA-(ribosomal) RNA hybrids with mercuric ions. It was observed that the same fragments of single-stranded DNA with an average molecular weight of 1.9 x 10(6) which hybridize with 23S RNA also hybridi...

No plasmids were detected in cells of Yersinia pestis which were bacteriocinogenic and positive for three additional determinants of virulence known to be lost at high frequency.