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Biomedical subjects

M J Oliver

Publications and source records attributed to M J Oliver.

At least 37 records · Page 2Linked to original sources
PubMed1992

Differential temperature sensitivity of pea superoxide dismutases.

The activity of pea (Pisum sativum L.) Cu/Zn and Mn superoxide dismutase isoforms was evaluated across a range of temperatures from 10 to 45 degrees C. Maximal activity of the Cu/Zn and Mn superoxide dismutase isoforms was observed at 10 degrees C. Both cytoplasmic and chloroplast Cu/Zn superoxide dismutases exhibit a reduction in staining intensity with increasing temperatures. Mn superoxide dismutase, however, maintained a relatively constant staining intensity across the range of temperatures evaluated. An unrelated enzyme used as a control, malate dehydrogenase, exhibited the expected increase in staining activity with increasing temperatures. These results describe a unique response of a protection enzyme to temperature.

Journal Article↗
PubMed1992

Metastatic clostridial myonecrosis associated with intra-uterine clostridial infection: a report of three cases.

Three cases of metastatic Clostridial myonecrosis are reported, two following spontaneous and one following criminal abortion. This particular combination has not been reported before. The two survivors were managed by hysterectomy and disarticulation of the leg through the hip. The patient who died did so before surgery could be undertaken. The literature on gas gangrene infections of the uterus and metastatic Clostridial myonecrosis is reviewed and guidelines for management are discussed.

Abortion, Illegal↗
PubMed1991

Influence of Protoplasmic Water Loss on the Control of Protein Synthesis in the Desiccation-Tolerant Moss Tortula ruralis: Ramifications for a Repair-Based Mechanism of Desiccation Tolerance.

Desiccation tolerance of the moss Tortula ruralis is characterized by a desiccation-induced change in gene expression that becomes evident upon rehydration. As reported earlier, this change in gene expression is apparently brought about by a change in the control of translation and does not include a major shift in mRNA abundance. A full qualitative and quantitative analysis of the alteration in gene expression, which is characterized by the loss of (or greater than fivefold decrease in) the synthesis of 25 hydration (h) proteins and initiation (or greater than fivefold increase) of the synthesis of 74 rehydration (r) proteins, is given in this report. Exposure to a desiccating atmosphere, for times that result in varying levels of water loss, enabled the determination that the control of synthesis of r proteins is different from the control of synthesis of h proteins. The r and h protein synthesis responses are internally coordinate, however. Similarly, the return to normal levels of h protein synthesis differs from that of the r proteins. The return to normal synthetic levels for all h proteins is synchronous, but the rate of loss of r protein synthesis varies with each individual r protein. Run-off translation of polysomes isolated from gametophytes during the drying phase demonstrates that there are no novel mRNAs recruited and no particular mRNA is favored for translation during desiccation. These findings add credence to the argument that translational control is the major component of the desiccation-induced alteration in gene expression in this plant, as discussed. Aspects of the response of protein synthesis to desiccation are consistent with the hypothesis that T. ruralis exhibits a repair-based mechanism of desiccation tolerance.

Journal Article↗
PubMed1986

In vitro transcription and translation of cloned cDNAs encoding the 30-kDa protein gene of TMV.

A cDNA clone encoding the nonstructural, 30-kDa protein of the common (U1) strain of tobacco mosaic virus (TMV) was isolated and characterized. cDNA clones representing the intact gene as well as deletions from the 5' end of the gene were subcloned into SP6 vectors. Capped RNAs produced by in vitro transcription reactions were translated in a wheat germ cell-free system. The resultant proteins were compared to proteins obtained from the in vitro translation of intermediate length (I2) rods of TMV. Transcripts of the cDNA clones encoded polypeptides of 30, 28, or 18 kDa that were immunoprecipitated by antibody prepared against a synthetic peptide representing the carboxy terminus of the 30-kDa protein. cDNA clones containing the intact 30-kDa sequence coded for 30-kDa polypeptides while clones lacking the 30-kDa initiation codon produced 28-kDa polypeptides. Surprisingly, translation of a transcript from a cDNA clone containing the 30-kDa gene plus 390 nucleotides 5' of the initiator AUG yielded a polypeptide with an approximate molecular mass of 18 kDa. The results indicate that an intact and functional 30-kDa protein gene has been cloned. The significance of these results, with respect to determining the function of the 30-kDa protein, is discussed.

Cell-Free System↗
PubMed1984

Plant Desiccation and Protein Synthesis. IV. RNA Synthesis, Stability, and Recruitment of RNA into Protein Synthesis during Desiccation and Rehydration of the Desiccation-Tolerant Moss, Tortula ruralis.

Upon rehydration of desiccated Tortula ruralis, RNA synthesis is immediately resumed; this resumption is quicker in moss recovering from slow drying than from rapid drying. Newly synthesized RNA enters the protein synthetic complex almost immediately upon rehydration, reaching control steady state levels within 2 hours after slow drying and 6 hours after rapid drying. RNA synthesized in the 1st hour following the readdition of water enters into polysomes much earlier after slow drying than after rapid drying. The RNA components of the protein synthetic complex are stable to desiccation at either slow or rapid speeds, although more so following the former drying regime. Immediately upon rehydration, these conserved RNA are readily utilized for protein synthesis, and continue to be so at least 4 hours thereafter. Hence, the speed of desiccation affects the rate at which RNA is synthesized upon subsequent rehydration, as well as the mode of utilization of that RNA.

Journal Article↗
PubMed1984

Plant Desiccation and Protein Synthesis : V. Stability of Poly (A) and Poly (A) RNA during Desiccation and Their Synthesis upon Rehydration in the Desiccation-Tolerant Moss Tortula ruralis and the Intolerant Moss Cratoneuron filicinum.

Upon desiccation of gametophytes of the desiccation-tolerant moss Tortula ruralis preexisting pools of poly(A)(-) RNA (rRNA) remain inact, regardless of the speed at which desiccation is achieved. Preexisting poly(A)(+) RNA pools (mRNA) are unaffected by slow desiccation but are substantially reduced during rapid desiccation. Poly(A)(-) RNA involved in protein synthesis is also unaffected by desiccation, whereas the levels of polysomal poly(A)(+) RNA in rapid- and slow-dried moss closely reflect the state of the protein synthetic complex in these dried samples.Poly(A)(-) RNA pools, both total and polysomal, are also stable during the rehydration of both rapid- and slow-dried moss. The total poly(A)(+) RNA pool decreases upon rehydration, but this reduction is simply an expression of the normal turnover of poly(A)(+) RNA in this moss. Analysis of polysomal fractions during rehydration reveals the continued use of conserved poly(A)(+) RNA for protein synthesis. The rate of synthesis of poly(A)(+) RNA upon rehydration appears to depend upon the speed at which prior desiccation is administered. Rapidly dried moss synthesizes poly(A)(+) RNA at a faster rate, 60 to 120 minutes after the addition of water, than does rehydrated slowly dried moss. Recruitment of this RNA into the protein synthetic complex also follows this pattern. Comparative studies involving the aquatic moss Cratoneuron filicinum are used to gain an insight into the relevance of these findings with respect to the cellular mechanisms associated with desiccation tolerance.

Journal Article↗
PubMed1984

Plant Desiccation and Protein Synthesis : VI. Changes in Protein Synthesis Elicited by Desiccation of the Moss Tortula ruralis are Effected at the Translational Level.

Upon rehydration of the moss Tortula ruralis following desiccation at a rapid or slow rate, there is increasing utilization of newly synthesized-poly(A)(+) RNA for protein synthesis. Initially, poly(A)(+) RNA conserved in the dry moss is associated with polysomes, but by 2 hours of rehydration there is an overwhelming recruitment of newly synthesized poly(A)(+) RNA, at the expense of conserved messages. In rehydrated moss, there is a marked synthesis in vivo of new proteins, which are separable by two-dimensional electrophoresis, and identifiable by fluorography. These new proteins, termed rehydration proteins, are synthesized after both rapid and slow desiccation, but their synthesis persists longer after rapid desiccation. The protein patterns obtained following in vitro translation of bulk RNA from hydrated, desiccated, and rehydrated moss were qualitatively identical. Thus the differences in protein patterns observed in vivo must result from preferential selection of specific mRNAs from the same pool, which is indicative of control of protein synthesis at the translational level. The implications of these observations in relation to the response of the moss to drying in its natural environment are discussed.

Journal Article↗
PubMed1981

The effects of molybate, tungstate and lxd on aldehyde oxidase and xanthine dehydrogenase in Drosophila melanogaster.

The effects of dietary sodium molybdate and sodium tungstate on eye color and aldehyde oxidase and xanthine dehydrogenase activities have been determined in Drosophila melanogaster. Dietary sodium tungstate administration has been used as a screening procedure to identify two new lxd alleles. Tungstate administration results in increased frequencies of "brown-eyed" flies in lxd stocks and a coordinate decrease in AO and XDH activities in all genotypes tested. The two new lxd alleles affect AO and XDH in a qualitatively but not quantitatively similar fashion to the original lxd allele. AO and XDH activity and AO-CRM levels appear much more sensitive to mutational perturbations of this gene-enzyme than do XDH-CRM levels in the genotypes tested.

Aldehyde Dehydrogenase↗
PubMed1979

Genetic and biochemical aspects of sucrase from Drosophila melanogaster.

Isoelectrofocusing of abdominal extracts of Drosophila melanogaster revealed the existence of two forms of sucrase (E.C. 3.2.1.26). One form exhibited an isoelectric point of 4.63 +/- 0.02 while the other form exhibited an isoelectric point of 4.83 +/- 0.02. The localization of the structural gene for sucrase is proposed on the basis of enzyme determinations in a series of duplication- and deletion-bearing aneuploids. We suggest that the sucrase structural gene lies between 31CD and 31EF on the left arm of chromosome 2 and that the two forms of abdominal sucrase derive from a common protein coded for by a single sucrase gene designated Sucr+.

Animals↗
PubMed1978

Genetic and biochemical aspects of trehalase from Drosophila melanogaster.

Only one molecular form of trehalase (E.C. 3.2.1.28) was detectable in adult Drosophila melanogaster by polyacrylamide gel electrophoresis and isoelectric focusing. An examination of duplication- and deletion-bearing aneuploids exhibiting dosage sensitivity indicated that the enzyme is encoded by a gene, Treh+, located between 55B and 55E of the second chromosome. The tissue-specific soluble and particulate forms of trehalase appear to be manifestations of a single protein encoded by a single gene.

Aneuploidy↗
PubMed1978

Oxygen absorption in evaporating and condensing water droplets.

The amount of oxygen absorbed by individual drops of water suspended in a gas stream was measured. The water vapor content in the gas was regulated so that oxygen mass transfer could be observed under evaporation or condensation conditions. Other variables studied were oxygen concentration and exposure time. The rate of mass transfer of oxygen increased significantly with increasing water vapor and oxygen content in the gas. The relevance of mass transfer in growing aerosol systems to industrial hygiene is discussed.

Absorption↗
PubMed1978

The effects of lao on aldehyde, oxidase activity and cross-reacting-material in Drosophila melanogaster.

In Drosophila melanogaster aldehyde oxidase occurs in at least two forms that can be separated electrophoretically. The mutant allele lao (low aldehyde oxidase activity) causes a deficiency of the major form of this enzyme. Immunoelectrophoretic analyses suggest that lao homozygotes produce aldehyde oxidase cross-reacting-material in nearly wild-type levels. Although aldehyde oxidase from the mutant stock is heat labile. properties such as Km and pH optima are not different from the normal enzyme.

Aldehyde Oxidoreductases↗