Density gradient centrifugation: fixation of bands by photopolymerization of acrylamide.

A method for immobilization of proteins in a density gradient is described. This method eliminates the collection of drops or the use of a schlieren optical system, but visualizes the results of the Amido Schwarz stain. Although only sucrose gradients have been examined, the method possibly may be extended to other gradients.

Use of nile red as a rapid measure of lipid content in ciliates.

We report the use of nile red as a rapid and inexpensive method to estimate cellular lipids in three species of Paramecium and in Tetrahymena by the direct application of the dye to living or fixed cells without extraction and purification. Qualitative estimates of the relative changes in the lipid content of cells of varying culture ages were obtained using fluorescence microscopy, while semiquantitative determinations were obtained by measuring the total fluorescence from the emission spectrum (excitation, 535 nm) of fixed cells treated with excess nile red. The relative amounts of neutral (excitation, 488 nm; emission, 540 nm) and polar (excitation, 535 nm; emission, 680 nm) lipids were approximated using fluorescence intensity at these selected spectral conditions to avoid any spill over from each other. The patterns of change with culture age in total lipids in Tetrahymena and in total, neutral and polar lipids in Paramecium obtained using nile red agreed well with published gravimetric data for these ciliates.

Salmonellae from dogs in Vom, Northern Nigeria.

Examination by culture of single faecal samples from 120 domestic dogs in the Vom area of Nigeria showed 22 (18 per cent) of the animals to be excreting Salmonella organisms. One of the dogs yielded two and another three different serotypes. The total number of Salmonella serotypes isolated in the survey was 21. Dogs may be important in Nigeria as agents for the transmission of salmonellosis to man and domestic livestock.