Analysis of heterocyst envelope glycolipids in regulatory Fox− mutants, mutant FQ1490 (11; see Table 2), and wild-type Anabaena sp. Heterocyst envelope glycolipids (arrows) are distinguishable from other Anabaena sp. lipids by their violet coloration when incompletely oxidized. The upper glycolipid is less abundant than the lower and may for that reason sometimes not be visualized together with the latter. Concordant with the results in Fig. 1, mutants bearing transposon insertions in ORFs all0187 and all2760 produce abundant heterocyst envelope glycolipids, little of such glycolipid is seen in an alr0117 mutant (see the text), and no more than a trace is seen in an alr1086 mutant, whereas mutant FQ1490 is known to form none (11).