Analysis of GFA-protein mRNA expression in developing bovine brain by in situ hybridization and northern blot hybridization.

Using bovine brains of adult and developmental stages, the time and place of the appearance of mRNA for glial fibrillary acidic protein (GFA-protein) were studied by in situ- and Northern blot-hybridization. Double-stranded cDNA labeled with [3H]dCTP or [32P]dCTP was used as the probe for this mRNA. To compare the location of GFA-protein mRNA and GFA-protein itself on serial sections. GFA-protein immunohistochemistry was used. By in situ hybridization with adult bovine brain. GFA-protein mRNA was detected in astroglia, most of which were in the white matter. The distribution of these astroglia by in situ hybridization was consistent with the findings by GFA-protein immunohistochemistry and Northern blot hybridization, indicating that each techniques were specific. Concerning fetal stages, GFA-protein mRNA could be detected in the brain of a fetal calf with a body length of 28 cm by in situ hybridization using the 32P-labeled probe, and the mRNA was localized in the subpial area and the fornix. These results indicated that glial maturation first became recognizable at least in the subpial area and the fornix in the brain of a fetal calf measuring 28 cm. In this fetal brain, GFA-protein mRNA was almost undetectable by Northern blot hybridization. This suggested that in situ hybridization was more sensitive and useful for the analysis of gene expression than Northern blot hybridization, when the target mRNA is present in only a limited area, such as in the brain.