Detection of ADH activity in X. laevis tissues. Starch gel electrophoresis of tissue homogenates (15 μl) from different animals. (A) ADH1 or ADH1-like activity staining using 2-buten-1-ol as a substrate and NAD+ as a coenzyme. (B) Glutathione (GSH)-dependent formaldehyde dehydrogenase (ADH3) activity staining. Lanes: S, stomach; L, liver; O, ovary (pool of oocytes at different maturation stages). All detected ADH forms showed anodic mobility and different band patterns. ADH1 or ADH1-like activity is more abundant in liver extracts than in stomach and is absent in ovary, whereas ADH3 is more abundant in ovary.