Exclusion of cooperating T cells as targets for heterologous anti-mu antiserum

BALB/c thymocytes were exposed to anti-μ serum in vitro, and both thymocytes and splenic T cells were exposed to anti-μ by long-term intensive treatment of intact animals. In all cases, the anti-μ-treated T cells could cooperate with splenocytes from nude mice in the in vitro immune response to sheep erythrocytes, indicating that cooperating T cells are not targets for immunosuppression by heterologous anti-μ antibodies.     

The anemia-induced reversible switch from hemoglobin A to hemoglobin C in caprine ruminants: immunochemical evidence that both hemoglobins are found in the same cell

During anemic episodes, goats and certain sheep replace hemoglobin A (HbA = α₂β₂^A) with hemoglobin C (HbC = α₂β₂^C). Rabbit serum directed against either purified sheep HbA or purified sheep HbC was prepared. Both types were used to test whether the two hemoglobins are found in the same cell during switching by an indirect fluorescent antibody assay.Unabsorbed antisheep HbA cross-reacted extensively with goat HbA but to a lesser extent with goat or sheep HbC. Similarly, unabsorbed antisheep HbC reacted with these antigens in the order: Sheep HbC > goat HbC > sheep HbA > goat HbA. Cross-absorption resulted in sera specific either for sheep and goat HbA or for sheep and goat HbC. The specificities were confirmed by indirect fluorescent antibody staining of sheep and goat erythrocytes containing either at least 99% HbA or at least 99% HbC.Smears of erythrocytes from sheep and goats in the process of switching were reacted with one of the absorbed sera then with fluorescein conjugated antirabbit immunoglobulin G. The sum of the fractions stained both by anti-HbA and by anti-HbC exceeded 100% during the switch. Most strikingly when HbA was replacing HbC, nearly all cells stained for HbC while more than half stained for HbA. Thus, the two hemoglobins are found in the same cell during switching.     

Improved viscometric assay for cellulase

A viscometric assay for the determination of carboxymethylcellulase is described. The method, which is developed from a direct theoretical approach, takes into account a kinetic energy correction and the non-Newtonian behavior of carboxymethylcellulose solutions. The enzymic hydrolysis of carboxymethylcellulose shows strong competitive inhibition by the products of the reaction and a method is presented for estimating the initial velocity of such reactions. A direct chemical determination of reducing end groups was used to confirm the validity of this approach.     

The morphology of the trout, Salmo gairdneri Richardson, thymus: some practical and theoretical considerations

An electron microscope study of the thymus in trout, Salmo gairdneri , showed that the membrane separating the thymus gland from the extenal water current was not specialized, but merely a continuation of the pharyngeal epithelium. This is discussed in relation to the evolution of the thymus in vertebrates, and to the possible effects on the thymus during hyperosmotic infiltration, a technique used for immunization.