Biomedical subjects
Publications and source records attributed to D E Buetow.
The proportion of ribosomes active in protein synthesis and the content of polyribosomal poly(A)-containing RNA are unchanged when adult and senescent rat livers are compared. Therefore, the decreased protein synthesizing activity of senescent liver microsomes observed previously is not due to a deficiency in total mRNA content.
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The total free amino acid content per gram of liver wet weight does not differ significantly between adult and senescent female rats, being 28.8 +/- 3.3 mumol in adult (13-17 months) and 26.2 +/- 2.2 mumol in senescent (23-29 months) animals. This is the first study in which these two age-groups of rats have been so compared. These results combined with a survey of the literature show that amino acid levels in rat liver do not change much, if at all, throughout the lifespan of the animal.
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The 16S ribosomal RNA of the chloroplast of Euglena gracilis strain Z has been characterized in terms of its 2-dimensional electrophoretic "fingerprint" (T1 ribonuclease). Over 100 spots were resolved on the "fingerprint" and each spot was characterized as to which RNA oligonucleotide fragment(s) is contained. When compared to similar analyses of prokaryotic 16S rRNAs and eukaryotic cytoplasmic 18S rRNAs, the chloroplast 16S rRNA was a typically prokaryotic RNA, but bore little if any relationship to eukaryotic 18S rRNAs. Therefore, the cistrons for chloroplast 16S rRNA are related to the equivalent prokaryotic cistrons, but, apparently, are not related to the equivalent eukaryotic cistrons. Among the organisms available for comparison, the Euglena chloroplast 16S rRNA appears most closely related to the 16S rRNA of the eukaryote, Porphyridium cruentum (a red alga), and at least distantly related to the 16S rRNAs of the blue-green algae and perhaps also to the bacilli.
Optimal assay conditions are described for 8 hydrolases of Euglena gracilis var. bacillaris, SM-L1 (streptomycin-bleached) strain, 7 of which have an acid pH-optimum. Acid-phosphatase, beta-galactosidase, beta-glucosidase, b-fucosidase, cathepsin D, RNase, DNase, and an esterase are active in cell homogenates. Amylase has very low activity, and beta-glucuronidase, arylsulfatase, beta, N-acetyl-glucosaminidase, alpha-fucosidase, and alpha- and beta-mannosidase are inactive.
The 16S ribosomal RNA of the Euglena gracilis chloroplast has been characterized in terms of its two-dimensional electrophoretic "fingerprint" (T1 ribonuclease). Results show it to be a typically prokaryotic 16 S rRNA. By the present criterion, different chloroplasts are shown to be related to one another and at least distantly to blue-green algae and perhaps to Bacillaceae. These results argue in favor of an endosymbiont origin of the chloroplast.