ABSTRACT
Three bacteriophages infecting Streptomyces erythreus, called G3, G4 and G5, were isolated and characterized. They contain double-stranded linear DNA molecules with cohesive ends. The restriction map of G3 DNA (48 kilobases long) for four restriction endonucleases and that of G4 DNA (43 kilobases long) for seven restriction endonucleases are reported. Restriction analysis and hybridization experiments showed that G3 and G4 share little DNA homology, while G4 and G5 are apparently identical except for an additional EcoRI site present in G5. The region containing this EcoRI site has been mapped on G4 DNA. Microbiological and serological data showed that G5 is very similar to G4. G3- and G4-resistant mutants of S. erythreus PS1 were isolated. The screening of phage-resistant mutants showed a high frequency of strains with increased erythromycin production. The mechanism of phage resistance of strain PS3 (G3 resistant) and of strain PS16 (G4 resistant) was examined. The DNA of the resistant strains contains no phage DNA, ruling out lysogeny as a cause of phage resistance. Transfection of strains PS1, PS3, and PS16 with DNA of the three phages showed the same efficiency, indicating that resistance is at the level of the bacterial wall.
Subject(s)
Bacteriophages/pathogenicity , Mutation , Streptococcus , Bacteriophages/genetics , DNA Restriction Enzymes/metabolism , DNA, Bacterial/analysis , DNA, Viral/analysis , Lysogeny , Microscopy, Electron , Nucleic Acid Hybridization , Streptococcus/genetics , TransfectionABSTRACT
We report a morphometric study on the effect of 3-palmitoyl-(+)-catechin on phagocytic activity of latex particles by Kupffer cells in guinea pig liver. We found an increase in the density of latex particles in Kupffer cells of animals treated with 3-palmitoyl-(+)-catechin. The volume and density of Kupffer cells of treated animals increased (p less than 0.01); there was no significant difference in surface density of the plasma membrane. None of the parameters measured was altered in endothelial cells. These results show that 3-palmitoyl-(+)-catechin produces morphological and functional changes in Kupffer cells.
Subject(s)
Benzopyrans/pharmacology , Catechin/pharmacology , Kupffer Cells/drug effects , Liver/cytology , Animals , Catechin/analogs & derivatives , Endoplasmic Reticulum/ultrastructure , Guinea Pigs , Kupffer Cells/physiology , Kupffer Cells/ultrastructure , Male , Microspheres , Mitochondria, Liver/ultrastructure , Phagocytosis/drug effects , Pinocytosis/drug effectsABSTRACT
In a study of the ultrastructure of hepatocytes in mice treated with morphine a statistically significant increase in the volume density and surface density of smooth endoplasmic reticulum (SER) was observed. Morphometric measurements using the method described by Weibel (2,3) were employed to calculate volume density of smooth and rough endoplasmic reticulum mitochondria, and surface density of rough and smooth endoplasmic reticulum membranes and of the mitochondrial envelope and cristae. Statistical analysis using the t test of Student was carried out for all parameters. Both surface density and volume density of SER in mice treated with morphine increased significantly when compared to mice of control group (P less than 0.05 for surface density of smooth endoplasmic reticulum and P less than 0.01 for volume density of smooth endoplasmic reticulum). These ultrastructural changes after administration of morphine and related opiates are not accompanied by an increase of drug metabolizing enzymes and the huge tolerance observed in mice can be a phenomenon of adaptation at the receptor site (4).
Subject(s)
Liver/ultrastructure , Morphine/pharmacology , Animals , Endoplasmic Reticulum/ultrastructure , Liver/drug effects , MiceABSTRACT
In a study of the ultrastructure of a hepatocytes in mice treated with heroin a statistically significant increase in the volume density and surface density of smooth endoplasmic reticulum (SER) was observed. Morphometric measurements using the method described by Weibel (2,3) were employed to calculate volume density of smooth and rough endoplasmic reticulum and mitochondria, and surface density of rough and smooth endoplasmic reticulum membranes and of the mitochondrial envelope and cristae. Statistical analysis using the t test of Student was carried out for all parameters. Both surface density and volume density of SER in mice treated with heroin increased significantly when compared to mice of the control group. An increase in volume density of SER is generally believed to be correlated to an increase in drug metabolizing enzymes localized in or on smooth endoplasmic reticulum membranes. We have demonstrated a statistically significant increase in SER in mice treated with heroin which is not accompanied by an increase in drug metabolizing enzymes (7). We feel that further investigation of these anomalous cases is necessary in order to clarify the role of the SER membranes and their function in the metabolism of drugs.
Subject(s)
Heroin/pharmacology , Liver/ultrastructure , Animals , Endoplasmic Reticulum/ultrastructure , Liver/drug effects , Mice , Mitochondria, Liver/ultrastructureABSTRACT
In this paper we present the electron microscopic analysis of two distinct extramitochondrial circular DNA species in the fission yeast Schizosaccharomyces pombe (S. pombe). Both DNA species can be isolated from mitochondrial fractions, but disappear after DNase treatment of mitochondria, demonstrating their extramitochondrial location. The size of these molecular species is 3.08 ± 0.18 µm and 2.00 ± 0.09 µm (standard deviation). They are present in a ratio of approximately 9:1 in the DNA preparations analyzed.
