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D L Montgomery

Publications and source records attributed to D L Montgomery.

72 records · Page 4Linked to original sources
PubMed1982

The molecular characterization of three transcriptional mutations in the yeast iso-2-cytochrome c gene.

Three mutations, each of which causes overproduction of iso-2-cytochrome c, were characterized biochemically. Two, CYP3-4 and CYP3-15, were previously shown to be cis-dominant and map to the CYC7 locus which encodes the iso-2 protein, while the third, cyp1-16, maps to an unliked locus. All three mutations caused dramatically increased levels of transcription of the CYC7 gene, and the CYC7 mRNA in mutant cells was found to be the same size as that in wild type cells. The CYP3-4 mutation was found to be caused by the integration of a transposable element, Tyl, 269 base pairs 5' to the coding sequences. The CYP3-15 mutation was also found to alter the DNA, probably through a deletion or inversion with one endpoint 285 base pairs upstream from the coding sequence. The CYC7 gene in both wild type and mutant cells was not subject to catabolite repression.

Base Sequence↗
PubMed1980

Isolation and sequence of the gene for iso-2-cytochrome c in Saccharomyces cerevisiae.

The two apocytochrome c proteins of yeast are coded for by separate genes. Iso-2-cytochrome c differs from the iso-1 protein at 17 positions within a homologous sequence of 108 amino acids. The previously cloned iso-1-cytochrome c coding sequence has been used to identify lambda-yeast recombinant phage containing the gene for iso-2-cytochrome c. The latter protein contains the dipeptide Ala-Ala which is coded for by the nucleic acid sequence G-C-N-G-C-N. The recognition specificity of restriction endonuclease Fnu4HI for G-C-N-G-C provided a rapid means of locating the region of the cloned fragment which codes for iso-2-cytochrome c. The DNA sequence of this gene has been determined and compared with that of the iso-1-cytochrome c locus. There is no intervening sequence within the gene for iso-2-cytochrome c. At 45 of the 91 positions for which iso-1- and iso-2-cytochrome c have the same amino acid, the codons differ. Such third position variation does not occur within the region coding for amino acids 70-80, the protein sequence that is also most conserved among all eukaryotic cytochromes c.

Apoproteins↗
PubMed1979

The effect of a four-month physical fitness program on a young and an old group matched for physical fitness.

A young (X = 36.8 years) and an old (X = 52.9 years) group (n = 12) matched for physical fitness performed a graded exercise test at the beginning and after a 4-month physical fitness program consisting of calisthenics, jogging, and recreational activities. The purpose of the study was to determine if there were any differences in response to physical training in the two age groups of similar fitness. Sixteen physiological and four biochemical variables were measured. There was no significant difference in VO2 max between the young and old groups. Also, there were no significant differences between groups for serum total lipids, cholesterol, triglycerides, or glucose levels. The effects of the training program were similar for both the young and old groups.

Adult↗
PubMed1979

Transcriptional regulation of the yeast cytochrome c gene.

DNA from the cloned yeast iso-1-cytochrome c, cycl, gene was used in a hybridization assay to measure levels and rates of synthesis of cycl RNA. Derepressed cells synthesized cycl RNA at 6 times the rate of that of glucose-repressed cells. Upon glucose addition to a derepressed culture, the transcription of the cycl gene was repressed within 2.5 min. The half-life of hybridizable cycl RNA was determined to be 12-13.5 min under repressed and derepressed conditions and during repression. The results demonstrate that the expression of the cycl gene is subject to transcriptional regulation.

Cytochrome c Group↗
PubMed1979

Characteristics of "old timer" hockey play.

Many Canadian adults play Old Timer hockey to improve and/or maintain their cardiorespiratory fitness. This review examined the intensity and duration of play that characterizes adult noncontact hockey. The exercise intensity was assessed by continuously monitoring the heart rate response via telemetry. The duration of play was studied utilizing time-motion analysis, during the typical Old Timer game, the forwards spent 28 minutes on the ice when the heart rate was at least at 60% KM intensity. The forwards averaged 85% KM intensity during game activity. The mean heart rate response of the goaltenders was 143 beats per minute or 64% KM intensity.

Adult↗
PubMed1978

Identification and isolation of the yeast cytochrome c gene.

The iso-1-cytochrome c gene of yeast has been identified and cloned using a synthetic oligodeoxynucleotide as a hybridization probe. The oligomer d[pT-T-A-G-C-A-G-A-A--C-C-G-G] is complementary to a region near the N terminal coding region of the yeast cyc 1 gene. Of several yeast Eco RI fragments which hybridize to this probe, one is changed in size by a G leads to T mutation which eliminates an Eco RI site within the cyc 1 gene. Both the wild-type and the RI- mutant forms were cloned in lambda gt vectors. Maxam-Gilbert sequencing for 91 nucleotides into the coding region for iso-1-cytochrome c yielded a DNA sequence in perfect correspondence with the known protein sequence.

Base Sequence↗
PubMed1977

Effects of exercise on free serum cholesterol.

Two age groups (young and old, n = 12) matched for physical fitness and two physical fitness groups (high and old, n = 12) matched for age participated in a four month physical fitness programme. Blood samples were drawn at four stages of metabolic stress at the pre-test and five stages at the post-test. The blood samples were analyzed by colorimetric methods for total cholesterol and free cholesterol. Statistical analysis revealed that: (1) Short-term exercise increased total cholesterol, free cholesterol, and the percent free cholesterol from the resting state to the submaximal and maximal exercise states. (2) There was no change in free serum cholesterol from the pre- to post-tests. (3) The high-fit group, compared with the low-fit group, had a lower free cholesterol level but had similar percent free cholesterol values. (4) There was no significant difference between age groups for either total serum cholesterol, free cholesterol, or the percent free cholesterol levels.

Adult↗
PubMedDate not supplied

Higher ploidy in Saccharomyces cerevisiae supports enhanced hepatitis B virus S cloned gene expression at the pilot scale.

The effect of host strain ploidy on the production of hepatitis B surface antigen (HBsAg) in Saccharomyces cerevisiae was evaluated at the pilot scale (75 L). We found that the accumulation of HBsAg normalized to cell protein was 2-fold higher for the diploid strain compared to its isogenic haploid. No detectable differences in many fermentation parameters were observed (e.g., rate of fermentation, growth rate, final cell yield). However, the enhancement of productivity in the diploid strain appeared to be associated with a slower rate of plasmid shedding (2 microns element) and, thus, a higher average copy number (2-fold at stationary phase) compared to those of the haploid strain.

Cloning, Molecular↗
PubMedDate not supplied

Physiological profile of fire fighters compared to norms for the Canadian population.

The purpose of this study was to determine the physical fitness level of Canadian fire fighters and to compare them to norms for Canadians of similar age and sex. The subjects were 1,303 male fire fighters from the Montreal fire department between the ages of 19 and 58 years. The subjects were categorized into four age groups: 19-29 years (n = 351), 30-39 years (n = 408), 40-49 years (n = 408), and 50-59 years (n = 136). Physical fitness was evaluated using the Canadian Standardized Test of Fitness. The test battery included: 1) pre-test screening, 2) anthropometric assessment, 3) cardiovascular, 4) flexibility and 5) muscular endurance measurements. Compared to the norms for the Canadian population of similar age, the fire fighters have: 1) higher body mass, body mass index and waist-to-hip ratio, 2) higher flexibility, 3) higher muscular endurance and 4) lower cardiovascular endurance. The lower cardiovascular endurance of the fire fighters was attributed to elevated body mass and an elevated heart rate response to the step test. It is unknown whether the heart rate response reflects long-term effects of exposure to carbon monoxide and vapours from combustible materials and chemicals.

Adult↗