FIG. 5.

Primer extension analysis of expression of the coxB gene in A. variabilis strain ATCC 29413 FD. Primer extension assays were carried out with RNA isolated from cells grown with ammonium (NH₄⁺), nitrate (NO₃⁻), or nitrate plus fructose (NO₃⁻ Fruc) or in medium lacking combined nitrogen (N₂). Assays were carried out using oligonucleotide CB1 (see Materials and Methods). The sequencing ladder shown was generated with the same oligonucleotide on a subclone of λE2. Arrowheads point to the putative tsp.