DISTRIBUTION OF FOLIC ACID COENZYMES AND FOLATE DEPENDENT ENZYMES IN MOUSE BRAIN1

—Folic acid coenzymes were found to be distributed equally between post-nuclear particulate and soluble fractions from whole Swiss mouse brain. Mitochondria isolated from the particulate fraction contained essentially only the N⁵-methyl derivative of folate, virtually all of which was in a polyglutamate form. Isolated synaptosomes contained significantly more folate than did mitochondria, with the greater proportion being non-N⁵-methyl derivatives. Osmotic lysis of synaptosomes released only a small portion of the folate; approximately 80 per cent remained with the particulate components of the synaptosome. The enzymes serine transhydroxymethylase and N⁵, N¹⁰-methylenetetrahydrofolate dehydrogenase were found in both the soluble and particulate fractions while formiminoglutamic acid:tetrahydrofolate formiminotransferase activity could not be detected. These findings may be of importance with respect to the synaptic functions of folate coenzymes, including the methylation of biogenic amines.     

The effects of sodium metaperiodate on T and B lymphocytes.

The differential mitogenic response of T and B lymphocytes to sodium metaperiodate has been investigated. It was found that periodate treatment leads to lymphocyte stimulation in spleen cells from Balb/c mice but not in spleen cells from the congenitally athymic nu/nu mice. In addition, treatment of Balb/c spleen cells with anti-θ serum plus complement lowers the mitogenic response to periodate and to concanavalin A without affecting the response to lipopolysaccharide. These results suggest a requirement for the presence of T lymphocytes in the initiation of a response to periodate. Spleen cells from nude mice also react with periodate, and their ability to respond to B cell mitogens is impaired after treatment with the chemical reagent.