FIG. 2.

Combined whole-cell in situ hybridization and microautoradiography of Achromatium cells from Rydal Water sediments. Whole-cell hybridization was done using a fluorescein-labeled RY clone 1-specific probe (ARY655c) and a rhodamine-labeled RY clone 8-specific probe (ARY655b). The micrographs are phase-contrast (A and D), epifluorescence (B and E), and microautoradiographic (C and F) images of the same fields of view. The cells shown were purified from sediment cores treated with radiolabeled bicarbonate. A proportion of cells of all Achromatium spp. assimilated both bicarbonate and acetate (data not shown). Not all probe-positive cells assimilated labeled substrates (D to F). The scale bars represent 20 μm.