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D Mills

Publications and source records attributed to D Mills.

At least 109 records · Page 6Linked to original sources
PubMed1976

Macromolecule synthesis in a mutant of Saccharomyces cerevisiae inhibited by S-adenosyimethionine.

Saccharomyces cerevisiae strain 83384-B3 carries the sai-1 mutation which confers sensitivity to S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH). It was shown that the mutant is impermeable to precursors of ribonucleic acid (RNA) and protein during inhibition by SAM (0.2 mM). Inhibition of uptake of adenine and uracil was nearly complete 3 h after growth in the presence of SAM and the uptake of leucine was at least 10-fold lower. The incorporation of 3H-adenine into ribosomal RNA, transfer RNA and heterodisperse RNA, believed to be messenger, was reduced 10-fold when measured after 1 h inhibition. The inhibition of growth was completely reversed by methionine (2.0 mM) in cells previously exposed to SAM for 90 min. The polysome content in cells inhibited by SAM was 25% less than the control after 4 h inhibition. Ribosome synthesis increased only about 40% in the presence of SAM and about 5-fold in the control over an 8 h period. All classes of RNA were synthesized during inhibition.

Electrophoresis, Polyacrylamide Gel↗
PubMed1976

Ribonucleic acid synthesized in meiotic cells of Saccharomyces cerevisiae: effect of culture medium pH.

Pulse-labeled ribonucleic acid (RNA) was extracted from polysomes of sporulating cells of Saccharomyces cerevisiae and characterized in sucrose gradients and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Transfer RNA, ribosomal RNA, and heterodisperse RNA, presumed to be messenger RNA, were synthesized during a 20-min pulse at T4 and T6 when labeling was performed in sporulation medium adjusted to pH 6.0. Furthermore, ribosomal RNA was processed into functional ribosomes during the pulse. The specific activity of pulse-labeled RNA of cells labeled in sporulation medium where the pH was unadjusted at T4 (pH 7.8) and T9 (pH 8.6) was 20- to 50-fold lower than RNA from cells labeled at pH 6.0. The low specific activity resulted from a 50-fold reduction in uptake of labeled precursors when the medium pH was greater than 7.2. However, heterodisperse RNA ranging from 4-17S in size and transfer RNA were synthesized during the pulse at T4 (pH 7.8),but the low specific activity of ribosomal RNA prevented a thorough analysis of its synthesis. Cellular impermeability at T9 (pH 8.6) resulted in minimal uptake of label, and an analysis of pulse-labeled transcripts was impossible. A comparison of the percantage of polysomal material indicate, however, that these cells were at least as active in translation as cells pulse-labeled at pH 6.0.

Adenine↗
PubMed1974

Isolation of polyribosomes from yeast during sporulation and vegetative growth.

Exponentially growing and sporulating cells of Saccharomyces cerevisiae have been subjected to a variety of conditions which mechanically disrupt the cell in an effort to establish conditions which permit the recovery of intact polyribosomes. Grinding cells for 10 s with glass beads in a Bronwill cell homogenizer was sufficiently gentle to yield a polyribosome content in exponentially growing cells which was similar to values obtained from yeast spheroplasts. Polyribosome patterns in sporulating yeast were similar to those from exponentially growing cells. This technique is fast, reproducible over a wide range of cell concentrations, and eliminates the need to make spheroplasts to recover intact polyribosomes.

Cell Fractionation↗
PubMed1972

Effect of pH on adenine and amino acid uptake during sporulation in Saccharomyces cerevisiae.

During the early stages of sporulation in Saccharomyces cerevisiae, the pH of the acetate sporulation medium rises to values of 8.0 or higher. Associated with this rise in pH is a reduced cell permeability to certain precursors of ribonucleic acid (RNA), deoxyribonucleic acid or protein. Uptake of adenine, alanine, and leucine was optimal at pH 5.6 to 6.0, but sporulation was inhibited when the sporulation medium was buffered below pH 7.0. Cellular impermeability can be largely overcome by adjusting the acetate sporulation medium to pH 6.0 for optimal uptake of (14) C-adenine during short pulses without any apparent effect on sporulation. Sporulating cells pulse-labeled 20 min at pH 6.0 incorporated 40 times more (14)C-adenine into RNA than sporulating cells pulse-labeled at pH 8.0. This increased incorporation can be attributed to a 100-fold increase in labeled adenosine triphosphate in cells pulse-labeled at pH 6.0 where maximum uptake occurs.

Acetates↗
PubMed1969

Dr. Julius Lempert.

Explore the source record for details and available documents.

Fenestration, Labyrinth↗
PubMedDate not supplied

Characterization of genome plasticity in Ustilago hordei.

Southern-blot hybridization analysis was used to identify and quantify chromosome-length polymorphisms for ten linkage groups of 14 races of Ustilago hordei. The bands identified by the probes were shown to vary as much as hundreds of kilobase pairs, but the magnitude of the variability was typically 5-15% of the average size of all bands to which a particular probe hybridized. A filamentous morphology mutant, recovered following heat-shock treatment of a strain with the greatest number of chromosome bands, was shown to have suffered a 50-kb deletion in a 940-kb chromosome. The mutation to filamentous morphology, designated fil1-1, and the deletion, were shown to invariably cosegregate 2:2 with the wild-type (sporidial) morphology in an ordered tetrad. Genetic and physical analyses place the Fil1 locus and the deletion near the terminus of one arm of the 940-kb chromosome. These results suggest that deletions of this type may be one of the causes of chromosome-length polymorphisms observed in field isolates of U. hordei.

Blotting, Southern↗
PubMedDate not supplied

Scanning transmission electron microscopy study of the molecular mass of amphipol/cytochrome b6f complexes.

The composition and mass of complexes between Chlamydomonas reinhardtii cytochrome b6f and low molecular mass amphipathic polymers ('amphipols') have been studied using biochemical analysis and scanning transmission electron microscopy at liquid helium temperature (cryo-STEM). Cytochrome b6f was trapped by amphipols either under its native 14-meric state or as a delipidated, lighter form. A good consistency was observed between the masses of either form calculated from their biochemical composition and those determined by cryo-STEM. These data show that association with amphipols preserved the original original state of the protein in detergent solution. Complexation with amphipols appears to facilitate preparation of the samples and mass determination by cryo-STEM as compared to conventional solubilization with detergents.

Animals↗
PubMedDate not supplied

Quantitative structure-property relationships (QSPRs) for the estimation of vapor pressure: a hierarchical approach using mathematical structural descriptors.

A set of 379 molecular descriptors was calculated for use in hierarchical quantitative structure-property relationship (QSPR) modeling of vapor pressure for a structurally diverse database consisting of 469 chemicals. The hierarchical approach utilizes topostructural, topochemical, geometrical, and quantum chemical descriptors in a stepwise fashion to develop QSPR models. In this way, the relative roles of the various levels of descriptors can be examined. The results show that the easily calculated topological descriptors explain the majority of the variance and that the addition of geometrical and quantum chemical descriptors does not result in a significantly improved model.

Journal Article↗