USE OF IMMUNOFLUORESCENCE TO VISUALIZE CELL-SPECIFIC GENE-EXPRESSION DURING SPORULATION IN BACILLUS-SUBTILIS

We have adapted immunofluorescence microscopy for use in Bacillus subt ilis and have employed this procedure for visualizing cell-specific ge ne expression at early to intermediate stages of sporulation. Sporangi a were doubly stained with propidium iodide to visualize the forespore and mother cell nucleoids and with fluorescein-conjugated antibodies to visualize the location of beta-galactosidase produced under the con trol of the sporulation RNA polymerase sigma factors sigma(E) and sigm a(F). In confirmation and extension of earlier reports, we found that expression of a lacZ fusion under the control of sigma(E) was confined to the mother cell compartment of sporangia at the septation (II) and engulfment (III) stages of morphogenesis. Conversely, sigma(F)-direct ed gene expression was confined to the forespore compartment of sporan gia at postseptation stages of development. Little indication was foun d for sigma(E)- or sigma(F)-directed gene expression prior to septatio n or in both compartments of postseptation sporangia. Gene expression under the control of the forespore sigma factor ac also exhibited a hi gh level of compartmentalization. A high proportion of sporangia exhib ited fluorescence in our immunostaining protocol, which should be suit able for the subcellular localization of sporulation proteins for whic h specific antibodies are available.