The Mg2+ precipitation procedure of R. D. Palmiter ((1974) Biochemistry 13, 3606) has been used for preparative scale isolation of polysomes from Ehrlich ascites mitochondria. Digitonin-washed metochondria used for isolating the polysomes contain no detectable reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase and over 200-fold reduced hexokinase activity. The mitochondrial polysomes exhibit a heterogeneous sedimentation and appear to contain highly aggregated particlses ranging over hexamers. These polysomes are sensitive to RNase, (ethylenedinitrilo)tetraacetic acid and puromycin. Mitochondrial polysomes are active in portein synthesis when supplied with supernatant enzymes from the homologous mitochondrial source or from Escherichia coli. Cytoplasmic enzymes, however, appear to be completely inactive. Protein synthesis by mitochrondrial polysomes is sensitive to chloramphenicol and resistant to cycloheximide and emetine. The procedure yields particles containing intact rRNAs. The extent of cytoplasmic RNA contaminating the total mitochondrial RNA or mitochondrial polysomal RNA has been estimated to be negligible.
Bipiperidyl mustard, after conversion to its bis-cyclic immonium ion forme, has been found to cause rapid and extensive lipid deposition in mice given single doses of the drug. The obe sity appears to result from an alkylation reaction; the responses of the treated ani mals to food restriction and realimenta tion resemble those observed in gold thioglucose-treated mice; also in anal ogy to gold thioglucose, the bipiperidyl mustard effects can be counteracted by sulfhydryl compounds. These observa tions are suggestive of a similarity of mode of action between the alkylating agent and gold thioglucose, a conclusion which is supported by preliminary find ings of ventromedial lesions in the hypo thalamus of the bipiperidyl mustard treated mice.
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