ABSTRACT
1. Novel assays based on the use of the suicide repair enzyme O6-alkylguanine-DNA-alkyltransferase (AGT) to repair O6-alkylguanine-type adducts in DNA have been used for the analysis of extracts of human biopsy specimens of gastric mucosa, urinary bladder mucosa, colon and circulating lymphocytes. 2. Examination of these extracts revealed no detectable amounts of the precarcinogenic adduct O6-meG. 3. AGT measurements were the same among the normal and the autologous samples of all patients examined, which limits its prognostic value as a tumour marker. 4. AGT measurements from the cancer samples were much higher compared with the measurements of the other two groups which proves that AGT is just a marker of tumour burden. 5. Finally, AGT measurements from lymphocytes show that AGT from normal individuals have about the same value as that from patients suffering from cancer in urinary bladder mucosa and colon, but is much lower than that of patients with cancer in gastric mucosa.
Subject(s)
DNA Damage , DNA Repair , DNA, Neoplasm/chemistry , Guanine/analogs & derivatives , Methyltransferases/metabolism , Neoplasms/genetics , Base Sequence , Colonic Neoplasms/enzymology , Colonic Neoplasms/genetics , Guanine/chemistry , Humans , Molecular Sequence Data , Mucous Membrane/enzymology , Neoplasms/enzymology , O(6)-Methylguanine-DNA Methyltransferase , Stomach Neoplasms/enzymology , Stomach Neoplasms/genetics , Urinary Bladder Neoplasms/enzymology , Urinary Bladder Neoplasms/geneticsABSTRACT
The cuticle proteins of the insect Dacus oleae have been isolated by extraction with a solution of 7 M urea. The affinity properties of cuticle proteins, isolated from the third instar larvae (L3DCPs 1-7), to chitin have been studied. Purified cuticle antigens were polymerized by glutaraldehyde and used for raising antibodies. The developmental appearance of the cuticle proteins has been studied by two-dimensional electrophoresis.
Subject(s)
Diptera/growth & development , Insect Proteins , Proteins/isolation & purification , Animals , Antibodies , Chitin , Chromatography, Affinity , Diptera/analysis , Electrophoresis, Gel, Two-Dimensional , Molecular Weight , Solubility , UreaABSTRACT
The nucleosomal non-histone phosphoproteins, and phosphoproteins released during the digestion of nuclei by micrococcal nuclease, were studied in three rat liver nuclear populations, namely diploid stromal, diploid parenchymal, and tetraploid parenchymal nuclei, which were separated by zonal centrifugation, in 3-week-old rats in which the parenchymal cells contain diploid nuclei and in 2- and 4-month-old rats with increasing proportions of parenchymal tetraploid nuclei. Qualitative and quantitative differences in nucleosomal phosphoprotein band patterns were found among different types of nuclei and ages. More phosphoprotein bands were found in nucleosomes derived from parenchymal than stromal nuclei. The number of phosphoproteins released during micrococcal-nuclease digestion increased with age for parenchymal nuclei. The significance of these results, considered in conjunction with the increase of DNA repeat length and decrease of nuclease accessibility with age, is discussed.
Subject(s)
Cell Nucleus/metabolism , Liver/metabolism , Micrococcal Nuclease/pharmacology , Phosphoproteins/metabolism , Aging , Animals , Autoradiography , Centrifugation, Density Gradient , Electrophoresis, Polyacrylamide Gel , Liver/cytology , Liver/drug effects , Male , Nucleosomes/metabolism , RatsABSTRACT
The organization of chromatin in three rat liver nuclear populations, namely diploid stromal, diploid parenchymal, and tetraploid parenchymal nuclei, which were separated by zonal centrifugation, was studied by digestion with micrococcal nuclease and pancreatic deoxyribonuclease in 3-week-old rats in which the parenchymal cells contain diploid nuclei and in 2-and 4-month-old rats with a high proportion of tetraploid nuclei. Digestion by micrococcal nuclease allowed the estimation of DNA-repeat length in chromatin. Parenchymal nuclei have shorter repeat length than stromal nuclei and DNA-repeat length increases with the age in all three nuclei populations. The kinetics of digestion by micrococcal nuclease showed that nuclei with shorter repeat length are more sensitive to micrococcal nuclease and that the sensitivity of chromatin decreases with age for all the types of nuclei in this study. The kinetics of digestion by pancreatic deoxyribonuclease showed that sensitivity of chromatin is related to the repeat length and that the sensitivity decreases with the ages.
