Nucleoside analysis of DNA from Trypanosoma brucei and Trypanosoma equiperdum.

We have digested trypanosome DNA with a combination of pancreatic DNase I, nuclease P1 and bovine alkaline phosphatase and fractionated the resulting nucleosides on a Supelcosil LC-18-S column by high pressure liquid chromatography. We find less than 0.1% unusual nucleosides, both in Trypanosoma brucei and in a Trypanosoma equiperdum stock, in contrast to a previous report of an unusual nucleoside replacing dC at 1.

O2- and O4-ethylthymine and the ethylphosphotriester dTp(Et)dT are highly persistent DNA modifications in slowly dividing tissues of the ethylnitrosourea-treated rat.

Male Wistar rats received a single i.p. injection of [3H]ethylnitrosourea (140 mg/kg) and were killed after 2 h, 1, 3, 6, 28 or 56 days.

Formation and stability of alkylated pyrimidines and purines (including imidazole ring-opened 7-alkylguanine) and alkylphosphotriesters in liver DNA of adult rats treated with ethylnitrosourea or dimethylnitrosamine.

Adult rats received a single injection of the carcinogens N-ethyl-N-nitrosourea (ENU) or N,N-dimethylnitrosamine (DMN) and were killed after various time intervals (up to 56 days). Liver DNA was analysed by h.p.

The induction of chromosomal damage in rat hepatocytes and lymphocytes. II. Alkylation damage and repair of rat-liver DNA after diethylnitrosamine, dimethylnitrosamine and ethyl methanesulphonate in relation to clastogenic effects.

Rat-liver DNA alkylation by diethylnitrosamine (DEN), dimethylnitrosamine (DMN) and ethyl methanesulphonate (EMS) was studied in an attempt to relate chromosome-damaging effects of these agents (the formation of micronuclei in hepatocytes; see preceding paper) to specific alkylation patterns. No correlation was observed between the induction of micronuclei and liver DNA N-alkylation, measured as 3- and 7-alkyl-purines. O6-Alkylguanine is probably not involved in micronucleus induction because it is lost from DNA too rapidly to explain the much more persistent clastogenic effects.

O6-alkylguanine and structural modifications in liver DNA of dialkylnitrosamine-treated rats.

Isolated rat liver DNA was fractionated on benzoylated-naphthoylated-DEAE-cellulose (BND-cellulose) columns. In experiments with dimethyl-nitrosamine (DMN)-treated (1-30 mg/kg) rats killed 24 h after injection, the amount of DNA eluting in the formamide fraction (i.e.

Persistence and accumulation of (potential) single-strand breaks in liver DNA of rats treated with ethyl methanesulphonate.

In vivo alkylation of DNA leads to DNA fragmentation in alkaline sucrose gradients. In a previous paper (Chem.-Biol.

Clearance of alpha 1-antitrypsin isoelectric focusing patterns in blood samples treated with heparin.

Plasma samples, whose typing for alpha 1-AT is made difficult or impossible because of an excess of heparin used as anticoagulant, can be treated very effectively with protamine sulphate. The addition of this heparin antagonist results in complete clearance of the isoelectric focusing pattern.