Robert W. Briggs 1911-1983.
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Embryology↗
Biomedical subjects
G Malacinski
Publications and source records attributed to G Malacinski.
Reiteration frequency of the histone genes in the genome of the amphibian, Xenopus laevis.
Radioactive RNA was obtained from Xenopus laevis gastrula-stage embryos which had been labelled by microinjection of [3H]uridine. A 9-12-S RNA fraction was isolated by phenol extraction of whole embryos followed by sucrose gradient centrifugation of the RNA and polyacrylamide gel electrophoresis. This RNA was identified as histone mRNA on the basis of its chemical and physical properties. On polyacrylamide gels the labelled RNA could be subfractionated into different components with electrophoretic mobilities similar to those of histone mRNAs of the sea urchin. 9-12-S RNA lacked poly(A) sequences. In a protein synthesis system in vitro the RNA fraction directed the synthesis of the histones H4, H2A, H2B, H3 and, possibly, of H1 protein. The Xenopus gistone mRNA was challenged with Xenopus DNA under conditions of vast DNA excess. A cot1/2 of between 110 and 250 mol-s-1(-1) was obtained from the RNA trace curve, indicating that the histone genes were 20-50-fold reiterated in the haploid genome of the species. This value indicates that although amphibians have several embryological and morphological features in common with sea urchins, the reiteration frequency for Xenopus histone genes is closer to the value of 10-20 established for mammals than the value of 400-1000 determined for sea urchins.
Animals↗
Bacterial oxidation of orthophosphate.
Malacinski, George (Indiana University, Bloomington), and Walter A. Konetzka. Bacterial oxidation of orthophosphite. J. Bacteriol. 91:578-582. 1966.-A variety of bacteria grown on a glucose and salts medium were capable of utilizing orthophosphite as a sole source of phosphorus. Two organisms, Pseudomonas fluorescens 195 and Serratia marcescens 24, were studied in detail. Growth rates and total cell yields of the bacteria grown on phosphite indicated that the bacteria utilized phosphite as efficiently as phosphate. The ability to oxidize the anion was shown to be inducible. A period of adaptation was required prior to growth on phosphite when phosphate-grown cells were transferred to a medium containing a limiting amount of phosphate and excess phosphite. No phosphite-oxidizing activity could be detected in whole cells or cell-free extracts of phosphate-grown cells. Both whole cells and cell-free extracts of phosphite-grown cells possessed phosphite-oxidizing activity.
Bacillus megaterium↗