A hematoxylin staining technique to locate sites of aluminum binding in aquatic plants and animals

This paper describes a modified hematoxylin staining technique that can be used to locate sites of A1 binding in freshwater plants and animals. This technique is fast, simple, and inexpensive to use. It is more reliable for organisms raised under controlled conditions, although it can be used on organisms isolated from the field. In the presence of Al, a purple stain appears which absorbs between 560 and 570 nm. This stain can be used as a live stain over the pH range of 3 to 9. The stain remains stable for at least 12 mo in alcohol-preserved specimens. Low concentrations of Fe (reddish-brown) and high concentrations of Pb (grey) and Cu (pink) can mask the reaction with Al (purple). Fluoride (10:1 molar ratio to Al), EDTA (1:1 ratio to Al), humic acid and PO₄ (1:10 ratio to Al) can prevent A1 uptake or interfere with Al-hematein binding. Based on the technique described in this paper, sites of Al binding in aquatic plants and animals include: nucleus and cell wall of the green alga Mougeotia; cell wall of the aquatic moss Leptodictyum riparium; chloride cells, tip of the penis, and hind gut of the fairy shrimp, Branchinecta paludosa; and the anal papillae of the phantom midge, Chaoborus.