ABSTRACT
The antimutagenic effects of selenium as sodium selenite were investigated using the Ames Salmonella/microsome mutagenicity test. The compounds examined were acridine orange and 7,12-dimethylbenz[alpha]anthracene. Selenium (22 ppm) reduced the number of histidine revertants caused by 20 microgram acridine orange and 20 microgram 7,12-dimethylbenz[alpha]anthracene by 52 and 74%, respectively. Increasing the quantity of selenium added to the plates further suppressed the mutagenicity of the test compounds. The antimutagenic effects of selenium cannot be explained by lethality of Salmonella typhimurium.
Subject(s)
9,10-Dimethyl-1,2-benzanthracene/antagonists & inhibitors , Acridine Orange/antagonists & inhibitors , Benz(a)Anthracenes/antagonists & inhibitors , Mutation/drug effects , Selenium/pharmacology , Dose-Response Relationship, Drug , Mutagenicity Tests , Salmonella typhimurium/geneticsABSTRACT
The regenerating blood of geese injected with phenylhydrazine was subjected to large scale, zonal centrifugation through density gradients of Ficoll. In this way, erythroid cells were fractionated according to their respective stages of development. Highly enriched fractions were obtained, containing cells that were well preserved as assessed by both light and electron microscopy. The separated cells exhibited ribosome density and nucleic acid and protein staining patterns typically associated with erythrocyte differentiation. Morphometric analysis of nuclei indicated that despite an apparent net increase in the amount of compact chromatin during development, comparatively little difference existed between the volumes of condensed chromatin present in immature and mature cells. Instead, there was a three fold decrease in nuclear volume between young erythroblasts and reticulocytes, coupled with a concomitant decrease in the volume occupied by dispersed chromatin, RNP and nucleoli. These observations are discussed in relation to molecular changes associated with nuclear differentiation in erythroid cells.
Subject(s)
Erythroblasts/ultrastructure , Erythrocytes/ultrastructure , Animals , Cell Nucleus/ultrastructure , Cell Separation/methods , Centrifugation, Zonal , Chromatin/analysis , Erythropoiesis , Geese , Microscopy, ElectronABSTRACT
The histone complements of erythroid cells from anemic rabbit marrow and cell fractions enriched in orthochromatic erythroblasts were examined using a variety of techniques. None of these methods revealed the presence of a histone comparable to H5, the erythrocyte-specific histone of birds and fish. Purified histones H1, H2A, H2B, H3 and H4 from rabbit marrow nuclei showed no unusual amino acid compositions.