Protein glycosylation mutants of procyclic Trypanosoma brucei: defects in the asparagine-glycosylation pathway

We employed a genetic approach to study protein glycosylation in the procyclic form of the parasite Trypanosoma brucei. Two different mutant parasites, ConA 1-1 and ConA 4-1, were isolated from mutagenized cultures by selecting cells which resisted killing or agglutination by concanavalin A. Both mutant cells show reduced concanavalin A binding. However, the mutants have different phenotypes, as indicated by the fact that ConA 1-1 binds to wheat germ agglutinin but ConA 4-1 and wild type do not. A blot probed with concanavalin A revealed that many proteins in both mutants lost the ability to bind this lectin, and the blots resembled one of wild type membrane proteins treated with PNGase F. This finding suggested that the mutants had altered asparagine- linked glycosylation. This conclusion was confirmed by studies on a flagellar protein (Fla1) and procyclic acidic repetitive protein (PARP). Structural analysis indicated that the N- glycan of wild type PARP is exclusively Man5GlcNAc2 whereas that in both mutants is predominantly a hybrid type with a terminal N- acetyllactosamine. The occupancy of the PARP glycosylation site in ConA 4-1 was much lower than that in ConA 1-1. These mutants will be useful for studying trypanosome glycosylation mechanisms and function.      

Polymorphisms for human chromosomes 1 and Y: Feulgen and UV DNA measurements

Some individuals show considerable length differences between the homologues of chromosome no. 1 and length variations for the Y chromosome have also been found. The variabilities in length appear to be localized in the heterochromatic regions. The aim of this study was to distinguish between two phenomena postulated to contribute to length variations: (1) a genetically determined uncoiling of a chromosomal region, and (2) an increase in the chromosomal DNA content. By cytophotometry of photographic negatives the integrated absorbance of polymorphic and normal no. 1 and Y-chromosomes was compared, using chromosome no. 2 as standard. Microphotometry was carried out on both unstained chromosomes at 265 nm and on Feulgen-stained chromosomes at 546 nm. Both methods showed that the length polymorphisms studied are, in general, characterized by an increase in the chromosomal DNA.     

Propranolol concentrations in plasma after insertion into the vagina.

Six healthy women participated in a study of the concentrations of propranolol achieved in plasma after insertion of the drug into the vagina. In four of the women the concentrations were also determined after administration by mouth. The area under the concentration curve for propranolol administered per vaginam was significantly greater than that after oral administration. There were small significant reduction in systolic blood pressure, pulse rate, and forced expiratory volume in one second after vaginal administration but these did not cause any symptomatic side effects. The tolerability of the vagina to drugs and the safety of this form of treatment remain to be determined. Probably further studies of the contraceptive effects of propranolol should be conducted with the dextro isomer of the drug.