Studies of non-migrating, long-lived lymphocytes in rats. 3. Decreased retention in lymph nodes of gnotobiotic rats

Tritiated thymidine was injected into the hind foot pads of isolated, gnotobiotic rats and of conventional rats after a stimulus with <i>Salmonella flagellin </i>or after no specific antigenic stimulus. The popliteal nodes were examined 30, 37, and 45 days after labeling. The rate of disappearance of stably labeled, long-lived small lymphocytes was more rapid in nodes from isolated rats than in nodes from conventional rats. Prior immunization made no difference. Labeled plasma cells persisted in high proportion in isolated rats, but in greater numbers in conventional rats.

Observations on acid-fastness and respiration of germinating yeast ascospores

Germination of the ascospores of a strain of Saccharomyces cerevisiae Hansen was stimulated by fermentable carbon sources. Nitrogen sources alone had little or no stimulating effect on germination unless glucose was present, but peptone and casein hydrolysate were exceptions. Loss of acid-fastness proved to be a useful criterion of spore germination. Evidence was obtained that germination occurs anaerobically, but is not restricted by oxygen. It is concluded that the respiratory characteristics of the three main phases of the yeast life cycle differ in that growth can occur aerobically or anaerobically, sporulation is restricted to aerobic conditions, and spore germination is anaerobic.

Perception of disability by welfare and rehabilitation clients

Recent federal legislation has provided for the active rehabilitation, by vocational rehabilitation agencies, of socially and economically disadvantaged persons. 11 welfare and 14 rehabilitation clients were compared on the basis of internal-external control expectancy and perception of disability. Salient commonalities exist between the samples that may have implications for intervention strategies used by agencies working with either or both types of clients.

Convenient microscopic tests for yeast viability and sporogenic capability

Drops of cell suspension are seeded on nutrient medium containing 5% purified agar and spread between the agar surface and a cover glass. The liquid phase is absorbed by the concentrated agar, so that the cells are held in situ between glass and agar. After incubation nongerminated cells and micro-colonies are counted microscopically. Sporogenic capability is assessed by seeding very dense cell suspensions on acetate agar and covering with Teflon F.E.P. membrane which is permeable to oxygen.

Proteolytic activity of intact yeast cells during sporulation

The ability of intact cells of three strains of Saccharomyces to degrade haemoglobin at pH 3.7 increased during sporulation in acetate medium. The highest proteolytic activity was found approximately 17 hours after transfer to sporulation medium, at which time a large percentage of the cell population was in the tetranucleate stage just before the appearance of spore walls. Three non-sporogenic strains showed no change in proteolytic activity. On the basis of permeability relationship and the absence of activity in sporulation medium from which the sporulating cells were separated, the writers suggest a peripheral location of the enzyme, apparently the first such report for a yeast proteinase.

Resistance of long-lived lymphocytes and plasma cells in rat lymph nodes to treatment with prednisone, cyclophosphamide, 6-mercaptopurine, and actinomycin D

The cells of the popliteal lymph nodes of rats were labeled for 4 days after a secondary immunological stimulus. 31 days after the last dose of tritiated thymidine, groups of rats were started on courses of daily, intraperitoneal injections of prednisone, cyclophosphamide, 6-mercaptopurine, or actinomycin D. The initially low doses of these agents were doubled in successive weeks until either lymphoid hypoplasia or death occurred. Rats from each group were killed weekly, and the percentages of persisting, labeled small lymphocytes in the popliteal nodes were determined. Sections of these nodes were examined for persisting, labeled plasma cells. The per cent of lymphocytes labeled increased while the total number of lymphocytes decreased during treatment with prednisone and cyclophosphamide. Prednisone decreased the numbers of long-lived plasma cells, but these cells were preferentially resistant to cyclophosphamide. Neither 6-mercaptopurine nor actinomycin D had an appreciable effect on lymphoid tissues histologically nor on the proportions of labeled, long-lived lymphocytes and plasma cells before causing the deaths of the rats receiving them. These results indicate that long-lived lymphocytes and plasma cells survive treatment with the immunolytic drugs studied, and that long-lived lymphocytes are specifically resistant to prednisone and cyclophosphamide. We believe these results have an application to the attempts to find drugs useful in the treatment of immunologic rejections of organ transplants, and for therapy of autoimmune diseases.

A serological comparison of vegetative cell and ascus walls and the spore coat of Saccharomyces cerevisiae

Cross-agglutination tests with sera obtained by injection of vegetative cells, asci, and spores into rabbits revealed no immunological distinction between the walls of vegetative cells and asci, whereas the spore coats were found to be serologically distinct from cell and ascus walls. Treatment of vegetative cells and asci with periodate or a proteolytic enzyme before agglutination tests gave results which suggest that the critical antigen is a protein structure.