Use of 5'-bromodeoxyuridine immunohistochemistry to examine proliferative activity of fish tissues

The suitability of bromodeoxyuridine (BrdU) immunohistochemistry for the study of myosatellite cell proliferation in three subadult carp (Cyprinus carpio) stages (11, 15, 17 cm) was examined. They were injected intraperitoneally with BrdU and fixed one hour late. After fixation and dehydration, white myotomal muscle and small intestine samples were embedded in Histowax. Cross sections mounted on glass slides, were incubated with monoclonal antiBrdU antibody (1:100) after HCl denaturation. After washing twice in PBS, slides were incubated in goat antimouse IgG FITC secondary antibody (1:20). Single cell suspensions were obtained from gut samples. Cellular DNA partially denatured with 2 N HCl, were immunolabelled with monoclonal antibodies against BrdU. Bivariate distribution of BrdU/total cellular DNA content was measured by flow cytometry. Good visualization of BrdU labelled myosatellite cells (4-6%) and small intestine (8-9%) was obtained. Flow cytometric bivariate BrdU/DNA analysis gave evidence of the same proliferative rate in the gut samples. The applicability of these methods to fish tissues further extend the broad range of biological and biomedical investigation in which BrdU immunohistochemistry has been used.