Immune response to chemically modified flagellin. IV. Further studies on the relationship between humoral and cell-mediated immunity

Acetoacetylation converts flagellin from an antigen which preferentially induces humoral antibodies to an antigen which exclusively provokes cell-mediated immunity and, under certain circumstances, induces antibody tolerance. Studies reported in this paper revealed that the acetoacetylated flagellins expressed similar immunological properties in flagellin primed rats as in normal rats. Thus, on the one hand, acetoacetylation destroyed the capacity of flagellin to trigger a secondary antibody response, but on the other hand, the acetoacetyl-flagellins very effectively induced delayed-type hypersensitivity reactions in flagellin primed animals. It was concluded from these results that humoral and cell-mediated immunity may be opposing immunological processes in both unprimed and primed animals.Acetoacetylated flagellin induced antibody tolerance in both strain W (low responder) and J (high responder) Wistar rats. Maximum tolerance was induced 12 hr after injection of antigen, but in strain J animals the tolerance had disappeared by 48 hr, whereas in strain W rats tolerance persisted for >28 days. The potential to recover from tolerance in strain J rats appeared to coincide with the level of delayed hypersensitivity at the time of challenge. However, this delayed hypersensitivity disappeared when breaking of tolerance occurred. These results suggest that the T cells which participate in delayed hypersensitivity reactions may also act as “helper” cells in antibody responses. On the other hand, it was found that priming for a secondary antibody response by flagellin appeared to coincide with development of primary antibodies rather than with induction of delayed-type hypersensitivity. The relative importance of specific T and B cells in these phenomena is discussed.     

The Glycine–Glomus–Rhizobium symbiosis. IV. Interactions between the mycorrhizal and nitrogen-fixing endophytes

Abstract Soybean (Glycine max (L.) Men) plants were grown under controlled conditions in an experiment designed as a 4 × 4 factorial. The factors were N or P nutrition, with different strains of Rhizobium japonicum or N-fertilization as levels of the first factor and different species of vesicular-arbuscular mycorrhizal (VAM) fungi or P fertilization as levels of the other. Organisms used were R. japonicum strains USDA 110, USDA 136, and 61A118, and the VAM fungi Glomus versiforme (Karst.) Berch, Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe, and Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe. There were 16 treatments: nine Rhizobium + Glomus combinations, three Rhizobium + V and three Glomus+ N combinations, and one non-symbiotic set of plants supplied with N + P. The tripartite symbioses were evaluated by analysis of variance against the Rhizobium + P and Glomus + N comparison treatments for effects on root and leaf dry mass, root N and P content, nodule mass and activity, and VAM colinization. Significant to highly significant main effects and interactions were found in virtually all evaluations due to both Rhizobium strain and VAM–fungal species. We conclude that different endophyte isolates affect not only the host plant, but also the development and function of their co-endophytes. These findings establish the existence of inter-endophyte compatibility, an important consideration when selecting or engineering for desirable endophyte traits.     

The association between an objective measure of physical activity and weight status in preschoolers

Objective: Our objective was to determine the association between physical activity and BMI among racially diverse low‐income preschoolers. Research Methods and Procedures: This was a cross‐sectional study of 2‐ to 5‐year‐olds (n = 56) enrolled in Massachusetts Special Supplemental Nutrition Program for Women, Infants & Children (WIC). Physical activity was measured for 7 consecutive days with an accelerometer. Height and weight were obtained from WIC records, and BMI‐for‐age percentiles were calculated based on the Centers for Disease Control and Prevention's (CDC) 2000 Growth Charts. At‐risk‐for‐overweight (BMI‐for‐age of ≥85th to <95th percentile) and overweight (BMI‐for‐age ≥95th percentile) groups were combined and referred to as overweight. Final analysis inclusion criteria were: completion of 4.5 days of activity assessment and anthropometric data obtained within 90 and 120 days of the activity assessment for children ages 24 to 35.99 and 36 to 59.99 months, respectively. Results: Overweight children had significantly lower mean daily very vigorous minutes (VVM) (2.6 mins vs. 4.6 mins, p < 0.05) and lower very active minutes (VAM) [i.e., sum of vigorous minutes (VM) and VVM] per day (22.9 mins vs. 32.1 mins, p < 0.05) than children who were not overweight. Daily VVM [odds ratio (OR) = 0.68; 95% confidence interval (CI), 0.49 to 0.96], VM (OR = 0.94; CI, 0.88 to 1.00), and VAM (OR = 0.94; 95% CI, 0.89 to 1.00) were all associated with significantly lower odds of being overweight. Discussion: This study suggests that, in a diverse group of preschoolers, vigorous and very vigorous activity are associated with lower odds of overweight. However, these findings require corroboration in a diverse sample of preschoolers using a longitudinal design.     

The solubility of cholesterol and its exchange between membranes

It has been proposed that exchange between membrane cholesterol pools occurs by desorption of molecules into the aqueous environment rather than by formation of a transitory collision complex between the membranes. The rate of exchange is likely to be determined by the rate of dissociation of cholesterol from the membrane bilayer and by the concentration of cholesterol monomers or aggregates of cholesterol molecules in solution. The aim of this study was to measure the effects of agents known to increase cholesterol exchange rates on cholesterol solubility, critical micellar concentration and on the activation energy of exchange. A comparison was also made with regard to these parameters, of the exchange of cholesterol to that of 4-cholesten-3-one, another steroid which exchanges more rapidly than cholesterol. Acetone and dimethylsulphoxide increased cholesterol exchange between liposomes and erythrocytes, but only modestly increased the apparent solubility of cholesterol in saline and had no effect on the activation energy of the exchange process. However, acetone and dimethylsulphoxide increased the critical micellar concentration of the cholesterol 3-fold, although tetraethylammonium iodide, which had a smaller effect on exchange, did not. 4-Cholesten-3-one had a lower solubility and critical micellar concentration than that of cholesterol, but had the same activation energy for exchange. It is concluded that the apparent solubility of steroid aggregates are unlikely to determine the rate of exchange, but that agents which substantially increase exchange also increase the critical micellar concentration. The low critical micellar concentration of cholestenone suggests that the actual monomer concentration in an exchange system is low and that the rate of dissociation of the molecules from the liposomes must determine the exchange rate. This is not reflected in the activation energy measurements since these are a composite of all the elements of the exchange process.     

Studies on the reproduction of cirripedes. IV. The protein amino-acid composition and gel electrophoresis of the oviducal sac and egg case

The oviducal sac of Pollicipes cornucopia Leach and of Balanus balanoides(L.) and also the egg case of the latter species are almost pure protein: the ash of B. balanoides egg cases contains, however, a considerable quantity of iron. The amino-acid composition of the proteins has been determined; that of the sacs is quite different in the two species. In spite of the different way in which the sacs were obtained it is considered that these differences are specific in origin. This is in accordance with probably specific differences in ovisacases, and the behaviour of the egg lamella of different species towards attack by protease.The behaviour of the proteins of the sac of Pollicipes cornucopia on SDS polyacrylamide gel electrophoresis indicates a variable polypeptide composition according to the ‘age’ of the sac; with increasing age there is a greater degree of polymerization.The results are discussed in relation to the mode of release of ovisacase, its passage across the egg case, activation, and the attack on only one envelope.