21 results on '"Calza RE"'
Search Results
2. Effects of feed additives on rumen fungi
- Author
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Chang, J-S, primary and Calza, RE, additional
- Published
- 1997
- Full Text
- View/download PDF
3. An NAD(+)-dependent glutamate dehydrogenase cloned from the ruminal ciliate protozoan, Entodinium caudatum.
- Author
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Newbold CJ, McEwan NR, Calza RE, Chareyron EN, Duval SM, Eschenlauer SC, McIntosh FM, Nelson N, Travis AJ, and Wallace RJ
- Subjects
- Amino Acid Sequence, Ammonia metabolism, Animals, Bacteroides genetics, Base Sequence, Cloning, Molecular, DNA, Protozoan chemistry, DNA, Protozoan genetics, Escherichia coli genetics, Escherichia coli metabolism, Gene Expression Regulation, Gene Transfer, Horizontal, Glutamate Dehydrogenase isolation & purification, Glutamic Acid metabolism, Ketoglutaric Acids metabolism, Molecular Sequence Data, Phylogeny, RNA, Messenger analysis, RNA, Protozoan analysis, Recombinant Proteins metabolism, Sequence Homology, Amino Acid, Substrate Specificity, Ciliophora enzymology, Genes, Protozoan, Glutamate Dehydrogenase genetics, Glutamate Dehydrogenase metabolism
- Abstract
An NAD(+)-dependent glutamate dehydrogenase (GDH; EC 1.4.1.24) was cloned from the ruminal ciliate protozoan, Entodinium caudatum. The gene had high sequence similarity to GDH genes from the Bacteroides (class)--a class of bacteria which is highly represented in the rumen. When expressed in Escherichia coli the enzyme had a high affinity for ammonia and alpha-ketoglutarate (apparent K(m) of 2.33 and 0.71 mM, respectively) and a low affinity for glutamate (apparent K(m) of 98 mM). GDH activity and GDH mRNA concentration were increased by incubating washed E. caudatum cells with ammonia and antibiotics. These results suggest that the GDH is an anabolic enzyme catalysing the assimilation of ammonia by E. caudatum in the rumen and that the gene was probably acquired by lateral gene transfer from a ruminal bacterium.
- Published
- 2005
- Full Text
- View/download PDF
4. Characterization of Aspergillus oryzae fermentation extract effects on the rumen fungus Neocallimastix frontalis, EB 188. Part 1. Zoospore development and physiology.
- Author
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Schmidt JA, Albright S, Tsai KP, Calza GM, Chang JS, and Calza RE
- Subjects
- Amylases metabolism, Animals, Carbohydrate Metabolism, Cattle, Cellulase biosynthesis, Cellulase metabolism, Enzymes metabolism, Fatty Acids, Volatile analysis, Fermentation, Fungal Proteins analysis, L-Lactate Dehydrogenase metabolism, Malate Dehydrogenase metabolism, Neocallimastix chemistry, Neocallimastix enzymology, Rumen microbiology, Spores, Fungal chemistry, beta-Glucosidase metabolism, Aspergillus oryzae metabolism, Dietary Supplements, Neocallimastix growth & development, Spores, Fungal growth & development
- Abstract
Experiments were performed to determine the effect of Aspergillus oryzae (AO) fermentation extract on zoospore development in the rumen fungus Neocallimastix frontalis EB 188. Powdered product, or liquid extract prepared from such powder, was added at the recommended value for supplementation in dairy cattle. Stationary and stirred cultures were periodically sampled and assayed for extracellular and intracellular protein and enzymes, gas production, zoospore production and maturation, and carbon source utilization. Soluble extract increased fungal physiology when grown in stirred vessels or stationary cultures. Treated cultures produced higher levels of enzymes (nearly double). Mobile zoospores matured into germination entities more rapidly in treated cultures, and when powdered product was used, nearly 3 times more motile zoospores were produced at 56 h of fungal growth. Levels of the intracellular enzyme malate dehydrogenase increased by 6-fold in the presence of powdered product. Product wheat bran carrier used as soluble extract or powder had very little effect on fungal cultures. Medium cellulose was completely hydrolyzed in all cultures but this occurred earlier in those containing AO treatment.
- Published
- 2004
- Full Text
- View/download PDF
5. Characterization of Aspergillus oryzae fermentation extract effects on the rumen fungus Neocallimastix frontalis, EB 188. Part 2. Carbon source utilization and effects on zoospore production.
- Author
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Schmidt JA, Albright S, Calza GM, and Calza RE
- Subjects
- Amylases metabolism, Amylases physiology, Animals, Carbohydrate Metabolism, Cattle, Cellulase biosynthesis, Cellulose metabolism, Enzymes metabolism, Fungal Proteins metabolism, Glucose metabolism, Neocallimastix enzymology, Rumen microbiology, Starch metabolism, beta-Glucosidase metabolism, Aspergillus oryzae metabolism, Dietary Supplements, Neocallimastix growth & development, Neocallimastix metabolism, Spores, Fungal growth & development
- Abstract
The effect of a commercial Aspergillus oryzae fermentation extract on the utilization of carbon source and zoospore production by the rumen fungus Neocallimastix frontalis EB 188 was determined. In addition, the composition of a soluble extract prepared from the commercial product was analyzed. This extract was added to N. frontalis EB 188 cultures grown on a variety of substrates and periodically assayed for protein, enzymes, zoospore production, and carbon source utilization. The powdered product contained 93% dry matter, more than 3,000 A. oryzaespores per gram, and did not contain strong buffers or high concentrations of salt. Measurable concentrations of DNA, protein, carbohydrate and several enzymes including cellulase and amylase were also found. Soluble extract increased fungal physiology and treated cultures produced significantly higher levels of supernatant protein and enzymes including amylase, cellulase and beta-glucosidase. The fungal response depended on culture carbon source. However, culture zoospore production was increased regardless of substrate provided. Culture utilization of glucose was more rapid in treated cultures, yet high levels of the extract greatly inhibited glucose utilization.
- Published
- 2004
- Full Text
- View/download PDF
6. The 3' untranslated region of messages in the rumen protozoan Entodinium caudatum.
- Author
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McEwan NR, Eschenlauer SC, Calza RE, Wallace RJ, and Newbold CJ
- Subjects
- Animals, Base Sequence, Ciliophora Infections parasitology, Ciliophora Infections veterinary, Codon, Terminator, DNA, Protozoan, Molecular Sequence Data, Poly A, Rumen parasitology, Sheep Diseases parasitology, 3' Untranslated Regions, Ciliophora genetics, RNA, Protozoan, Sheep parasitology
- Abstract
The 3' untranslated regions of a number of cDNAs from the rumen protozoal species Entodinium caudatum were studied with a view to characterising their preference for stop codons, general length, nucleotide composition and polyadenylation signals. Unlike a number of ciliates, Entodinium caudatum uses UAA as a stop codon, rather than as a codon for glutamine. In addition, the 3' untranslated region of the message is generally less than 100 nucleotides in length, extremely A+T rich, and does not appear to utilise any of the conventional polyadenylation signals described in other organisms.
- Published
- 2000
- Full Text
- View/download PDF
7. Protozoal sequences may reveal additional isoforms of the 14-3-3 protein family.
- Author
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McEwan NR, Eschenlauer SC, Calza RE, Wallace RJ, and Newbold CJ
- Subjects
- 14-3-3 Proteins, Animals, Phylogeny, Ciliophora chemistry, Entamoeba chemistry, Proteins chemistry, Protozoan Proteins chemistry, Tyrosine 3-Monooxygenase
- Abstract
The phylogenetic position of eleven 14-3-3 proteins from five protozoal species was tested relative to other eukaryotic 14-3-3 versions representing many of the previously described isoforms. The protozoal proteins, four from Entodinium caudatum, three from Entameoba histolytica and four from apicomplexan parasites formed clusters closer to the plant and animal epsilon isoforms than to the animal beta, gamma/eta, sigma/theta, and zeta isoforms. This extends the preliminary findings of Wang and Shakes (1996) but data from a wider range of genera are still required to strengthen our hypothesis that the protozoan isoforms may constitute novel isoforms of the 14-3-3 family.
- Published
- 1999
- Full Text
- View/download PDF
8. Fermentation extract effects on the morphology and metabolism of the rumen fungus Neocallimastix frontalis EB188.
- Author
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Chang JS, Harper EM, and Calza RE
- Subjects
- Animals, Cellulase metabolism, Chromatography, Thin Layer, Ethers, Fatty Acids, Volatile analysis, Fatty Acids, Volatile metabolism, Fungal Proteins analysis, Fungal Proteins metabolism, Malate Dehydrogenase metabolism, Microscopy, Electron, Scanning, Neocallimastix drug effects, Neocallimastix ultrastructure, Aspergillus oryzae metabolism, Fermentation physiology, Neocallimastix enzymology, Rumen microbiology
- Abstract
The effects of Aspergillus oryzae fermentation extract, Amaferm, on the rumen fungus Neocallimastix frontalis EB188 were studied. The secretion of cellulase was increased by 67% and rhyzoid development was increased 3.8-fold in the presence of extract. Strength of fungal response increased in a dose-dependent manner and demonstrated a positive correlation between cell surface area and enzyme secretion. Above certain concentrations of extract, however, the development of the fungus and enzyme secretions remained at control values or slightly diminished. Supernatant fluid appearance of the intracellular enzyme, malate dehydrogenase, paralleled the secretion of cellulase both in the presence and absence of extract. Ether solubilization of extract demonstrated that the active component(s) possessed a moderately polar value between 2.7 and 2.8. Thin layer chromatography separated extract into inert, inhibitory and intensely stimulating fractions. These results support the idea that by accelerating fungal growth and metabolism, Amaferm increases the rate (or extent) of fibre degradation caused by rumen fungi and that this, in turn, may contribute to enhanced animal performance.
- Published
- 1999
- Full Text
- View/download PDF
9. Phylogenetic position and codon usage of two centrin genes from the rumen ciliate protozoan, Entodinium caudatum.
- Author
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Eschenlauer SC, McEwan NR, Calza RE, Wallace RJ, Onodera R, and Newbold CJ
- Subjects
- Animals, Antibodies, Protozoan, Base Sequence, Calcium-Binding Proteins immunology, Codon genetics, DNA, Protozoan genetics, Paramecium tetraurelia genetics, Phylogeny, Protozoan Proteins immunology, Rabbits, Rumen parasitology, Sequence Homology, Amino Acid, Sequence Homology, Nucleic Acid, Sheep parasitology, Calcium-Binding Proteins genetics, Chromosomal Proteins, Non-Histone, Ciliophora genetics, Genes, Protozoan, Protozoan Proteins genetics
- Abstract
A lambda phage cDNA expression library was constructed from washed suspensions of the rumen ciliate protozoan, Entodinium caudatum, which had been maintained in an isolated, monofaunated sheep. The library was screened using an anti-E. caudatum antiserum raised in rabbits against sonically disrupted protozoa, DNA sequences for two centrins or caltractins, a subfamily of the EF-hand Ca(2+)-modulated proteins which are closely related, highly conserved cytoskeletal proteins, were identified and characterised. Their phylogenetic position was established relative to other centrin gene sequences. The two proteins showed homology to Paramecium tetraurelia centrins: 50 and 52% identities and 71 and 75% similarities in the protein sequence, over 99 and 110 amino acids fragments. Codon usage and indices revealed the E. caudatum follows universal codon usage, but with a restricted number of codons, and has a low G&C content.
- Published
- 1998
- Full Text
- View/download PDF
10. Enzymatic method for measuring subnanomolar concentrations of oxygen in gaseous or aqueous solutions.
- Author
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O'Fallon JV, Wright RW Jr, and Calza RE
- Subjects
- Carbohydrate Epimerases metabolism, Detergents, Enzyme Inhibitors metabolism, Glucose metabolism, Glucose Oxidase metabolism, Hydrogen-Ion Concentration, Metals, Pyruvic Acid metabolism, Oxygen analysis, Solutions chemistry
- Abstract
A method that combines glucose oxidase with [U-14C]glucose to measure subnanomolar to decamillimolar concentrations of oxygen is presented. The method is inexpensive and easy to use. It is independent of sample pH and enzyme inhibitors, including detergents and metal ions. This method can be directly applied to gaseous or aqueous samples and multiple assays can be run simultaneously.
- Published
- 1996
- Full Text
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11. Fractionation of cellulases from the ruminal fungus Neocallimastix frontalis EB188.
- Author
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Li XL and Calza RE
- Subjects
- Animals, Cattle, Cellulase chemistry, Chemical Fractionation, Chromatography, Liquid, Chytridiomycota chemistry, Culture Media, Durapatite, Electrophoresis, Polyacrylamide Gel, Fungal Proteins chemistry, Hydroxyapatites, Cellulase isolation & purification, Chytridiomycota enzymology, Fungal Proteins isolation & purification, Rumen microbiology
- Abstract
Cellulases from the ruminal fungus Neocallimastix frontalis EB188 were separated by using hydroxylapatite column chromatography. Seven carboxymethylcellulases, six avicelases, and four beta-glucosidases accounted for the majority of the activities. The separation of enzymes was confirmed by using polyacrylamide gel electrophoresis. Electrophoretic migration, analysis of hydrolysis products, and substrate specificity measurements suggested that several different cellulases were secreted in N. frontalis EB188. The possible relationship of cellulase diversity to protein glycosylation is discussed.
- Published
- 1991
- Full Text
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12. Kinetic study of a cellobiase purified from Neocallimastix frontalis EB188.
- Author
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Li XL and Calza RE
- Subjects
- Animals, Carbohydrates pharmacology, Cattle, Cellobiose, Cellulose 1,4-beta-Cellobiosidase, Chytridiomycota isolation & purification, Electrophoresis, Polyacrylamide Gel, Glycoside Hydrolases isolation & purification, Isoelectric Focusing, Kinetics, Molecular Weight, Rumen microbiology, Substrate Specificity, beta-Glucosidase isolation & purification, Chytridiomycota enzymology, Glycoside Hydrolases metabolism, beta-Glucosidase immunology
- Abstract
A cellobiase was purified from the culture supernatant of Neocallimastix frontalis EB188. This enzyme possessed a molecular weight of 85,000 and an isoelectric point of 6.95. The enzyme rapidly hydrolyzed cellobiose, p-nitrophenyl (pNP) beta-D-glucopyranoside (pNPG) and cellotriose and slowly hydrolyzed cellopentaose and salicin. The enzyme did not hydrolyze pNP alpha-D-glucopyranoside or pNP beta-D-cellobioside. Substrate inhibition was observed when cellobiose or pNPG were used as the substrates and glucose production was measured. The kinetic parameters were: K = 0.053 mM, V = 5.88 U/mg of protein and Ki = 0.95 mM for cellobiose; K = 0.36 mM, V = 1.05 U/mg and Ki = 8.86 mM for pNPG. Substrate inhibition was not detected during the hydrolysis of pNPG when pNP production was measured. The kinetic parameters for pNPG were: K = 0.67 mM and V = 1.49 U/mg of protein. The presence of an enzyme.glucose.substrate complex and transglucosylation was evident during the catalysis. Glucose, cellobiose, glucono-delta-lactone, galactose, lactose, maltose and salicin acted as competitive inhibitors during the hydrolysis of pNPG with the apparent inhibition constants (Kis) of 4.8 mM, 0.035 mM, 0.062 mM, 28.5 mM, 0.38 mM, 15.0 mm and 31.0 mM, respectively.
- Published
- 1991
- Full Text
- View/download PDF
13. Glucose metabolic pathways in the anaerobic rumen fungus Neocallimastix frontalis EB188.
- Author
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O'Fallon JV, Wright RW Jr, and Calza RE
- Subjects
- Acetates metabolism, Anaerobiosis, Animals, Chytridiomycota isolation & purification, Ethanol metabolism, Fermentation, Glycolysis, Kinetics, Lactates metabolism, Malate Dehydrogenase, Ruminants, Chytridiomycota metabolism, Glucose metabolism, Rumen microbiology
- Abstract
Primary pathways for glucose metabolism were established in the anaerobic rumen fungus Neocallimastix frontalis EB188. This highly capable cellulolytic organism demonstrated a strict anaerobic integration of metabolic pathways. Glycolysis in N. frontalis EB188 was coupled to malate dehydrogenase, 'malic' enzyme and specified hydrogenosome reactions. Pyruvate, as in most life forms, was a pivotal compound. The major fermentation products of N. frontalis EB188 were acetate, ethanol and lactate, with the concomitant generation of H2. On the basis of its unique characteristics and streamlined fermentation pathways, it was concluded that N. frontalis EB188 should be an important contributor to programs generating energy and selected chemicals from currently intractable biomass.
- Published
- 1991
- Full Text
- View/download PDF
14. Supernatant protein and cellulase activities of the anaerobic ruminal fungus Neocallimastix frontalis EB188.
- Author
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Barichievich EM and Calza RE
- Subjects
- Anaerobiosis, Animals, Cattle, Cellulose metabolism, Chromatography, Gel, Chytridiomycota enzymology, Colorimetry, Culture Media, Densitometry, Electrophoresis, Polyacrylamide Gel, Glucose metabolism, Hydrogen-Ion Concentration, Isoelectric Focusing, Molecular Weight, Cellulase biosynthesis, Chytridiomycota metabolism, Fungal Proteins biosynthesis, Rumen microbiology
- Abstract
Protein and cellulose activities were measured in culture supernatants of the anaerobic ruminal fungus Neocallimastix frontalis EB188 established in glucose medium and switched to either glucose, cellobiose, or cellulose media. Polyacrylamide gel electrophoresis was used to show differences caused by changing medium carbon source. Culture supernatants contained proteins with molecular weights ranging from greater than 116,000 to about 19,000. Low levels of cellulose activity were evident in glucose-grown cultures. Increased amounts of slowly migrating cellulase activities appeared in the supernatants of glucose-grown cultures switched to cellulose. Cellulase activities which reacted differentially during colorimetric and in situ assays were produced. Isoelectric points of cellulase activities varied from 3.7 to 8.3, and activities possessed optimal pHs of between 5.9 and 6.5.
- Published
- 1990
- Full Text
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15. Release of high molecular weight DNA from Neurospora crassa using enzymic digestions.
- Author
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Calza RE and Schroeder AL
- Subjects
- Centrifugation, Density Gradient, Chromatography, Agarose, DNA Repair, DNA, Fungal analysis, Endonucleases, Molecular Weight, Neurospora crassa drug effects, Neurospora crassa radiation effects, Ultraviolet Rays, DNA, Fungal biosynthesis, Enzymes pharmacology, Hydrolases, Neurospora metabolism, Neurospora crassa metabolism
- Abstract
Methods are described that allow extraction of high molecular weight DNA from germinated conidia of Neurospora crassa. By labelling DNA with ribonucleosides, early conidia were shown to be active in DNA synthesis. These cells when treated with the enzyme Zymolyase became fragile and could be readily lysed with ionic detergents to release high molecular weight DNA. The DNA extracted from Zymolyase treated cells on to alkaline sucrose gradients sedimented as a heterogeneous species of up to 150 x 10(6) molecular weight. A minor DNA species (presumably mitochondrial) of 20 x 10(6) molecular weight comprised 2-7% of the total. The identity of the DNA was confirmed by sensitivity to DNAase, the diphenylamine assay and TLC. Sedimentation patterns were unaffected by protease digestions and no anomalous high speed rotor effects were evident. Isopycnic gradients suggested that the DNA released was uncomplexed with either protein or carbohydrates. Sepharose chromatography of extracted, RNAase-treated Zymolyase lysate resulted in clearly separate high molecular weight DNA and RNA-protein elution profiles. UV light preferentially inhibited nuclear DNA synthesis and drastically reduced the size and amount of nascent DNA being synthesized in the excision defective uvs-2 mutant. Sites in parental DNA sensitive to Micrococcus luteus UV endonuclease were measured in cells made permeable with Triton X-100.
- Published
- 1983
- Full Text
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16. Postreplication repair in Neurospora crassa.
- Author
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Calza RE and Schroeder AL
- Subjects
- Caffeine pharmacology, Centrifugation, Density Gradient, DNA Replication, DNA, Fungal biosynthesis, Deoxyribodipyrimidine Photo-Lyase metabolism, Molecular Weight, Ultraviolet Rays, DNA Repair, DNA, Fungal metabolism, Neurospora genetics, Neurospora crassa genetics
- Abstract
Changes in the molecular weight of nascent DNA made after ultraviolet (UV) irradiation have been studied in the excision-defective Neurospora mutant uvs-2 using isotopic pulse labeling, alkaline gradient centrifugation and alkaline filter elution. Both the size of nascent DNA and the rate of incorporation of label into DNA was reduced by UV light in a dose dependent manner. However, this DNA repair mutant did recover the ability to synthesize control-like high molecular weight DNA 3 hours after UV treatment, although the rate of DNA synthesis remained depressed after the temporary block to elongation (or ligation) had been overcome. Photoreactivation partially eliminated the depression of DNA synthesis rate and UV light killing of cells, providing strong evidence that the effects on DNA synthesis and killing were caused by pyrimidine cyclobutane dimers. The caffeine inhibition repair studies performed were difficult to quantitate but did suggest either partial inhibition of a single repair pathway or alternate postreplication DNA repair pathways in Neurospora. No enhancement in killing was detected after UV irradiation when cells were grown on caffeine containing plates.
- Published
- 1982
- Full Text
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17. In-vitro transcription in tobacco chromatin.
- Author
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Calza RE and Lurquin PF
- Abstract
A method is described to isolate transcriptionally active Nicotiana tabacum L. cv. Xanthi chromatin from suspension-cultured cells. Enzymatic preparation of protoplasts with solubilization of the plasma membrane, Triton X-100 and homogenization resulted in chromatin free from cellular debris. Incroporation of [(3)H]uridine triphosphate into RNA increased for more than 30 min at 30° C. Transcriptional activity was maximally stimulated at 10 mM MgCl2, 200 mM (NH4)2SO4 and 150 mM KCl. The in-vitro synthesized RNA was found to contain 3.8% polyadenylated RNA. The results of digestion studies with ribonuclease, heat and detergent inactivation studies, α-amanitin and actinomycin D inhibitor effects, as well as dependency on ribonucleotide triphosphates, showed that the activity recorded in the tobacco chromatin was bona-fide enzymatic RNA transcription. There also was marked stimulation of transcriptional activity when exogenous DNA was added to the assay mixture.
- Published
- 1983
- Full Text
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18. Transcription in nuclei isolated from carrot protoplasts: effects of exogenous DNA.
- Author
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Calza RE, Oelke SM, and Lurquin PF
- Subjects
- Ammonium Sulfate pharmacology, Cell Nucleus drug effects, Magnesium pharmacology, Manganese pharmacology, Uridine Triphosphate metabolism, Cell Nucleus metabolism, DNA genetics, Plants metabolism, Transcription, Genetic drug effects
- Published
- 1982
- Full Text
- View/download PDF
19. The role of pyrimidine dimers in postreplication repair in Neurospora.
- Author
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Calza RE and Schroeder AL
- Subjects
- DNA Replication radiation effects, Dose-Response Relationship, Radiation, Multienzyme Complexes metabolism, Neurospora crassa radiation effects, Ultraviolet Rays, DNA Repair, Endodeoxyribonucleases, N-Glycosyl Hydrolases, Neurospora genetics, Neurospora crassa genetics, Pyrimidine Dimers genetics
- Abstract
Using the Micrococcus luteus dimer specific endonuclease assay of Wilkins (1973), and photoreactivation we have examined the induction and fate of ultraviolet induced pyrimidine dimers in the excision defective strain, uvs-2, of Neurospora crassa. Dimer induction was fluence dependent from 0 to 800 ergs/mm2 UV. An interdimer distance of 19.6 x 10(6) DNA molecular weight was found after a fluence of 220 ergs/mm2. We confirm the earlier report that this mutant is completely excision defective (Worthy and Epler 1972). Photoreactivation (PR), which greatly enhanced survival (by 10 fold after 440 ergs/mm2 UV), reduced significantly (40-44%) the number of UV-endonuclease sensitive sites found in irradiated DNA. This treatment also alleviated immediately some of the temporary blocks to high molecular weight DNA synthesis (elongation or ligation) seen in irradiated cells. We have also attempted to elucidate the mechanism of cellular postreplication repair used to overcome the UV inhibition to DNA synthesis. It was determined that during postreplication repair, Neurospora does not use recombination to bypass dimers and that single stranded DNA gaps opposite dimers do not appear to be present during the time when DNA being synthesized is made only in short pieces.
- Published
- 1982
- Full Text
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20. Sodium butyrate stimulates DNA repair in UV-irradiated normal and xeroderma pigmentosum human fibroblasts.
- Author
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Smerdon MJ, Lan SY, Calza RE, and Reeves R
- Subjects
- Butyric Acid, Cell Line, DNA Replication drug effects, DNA Replication radiation effects, Fibroblasts drug effects, Fibroblasts metabolism, Fibroblasts radiation effects, Humans, Butyrates pharmacology, DNA Repair drug effects, Ultraviolet Rays, Xeroderma Pigmentosum metabolism
- Abstract
Histone acetylation, DNA replicative synthesis, UV-induced DNA repair synthesis, and UV-induced endonuclease-sensitive sites were measured in normal human fibroblasts and xeroderma pigmentosum fibroblasts (complementation groups A, C, and D) following exposure to sodium butyrate. In all four cell types, treatment with millimolar concentrations of sodium butyrate resulted in a hyperacetylation of the core histones. Furthermore, following an exposure of 20 mM sodium butyrate for 48 h, the extent of hyperacetylation was the same in each cell type. In agreement with previous reports, we observed a marked decrease in DNA replicative synthesis in each cell type following increasing times of exposure to sodium butyrate. On the other hand, we observed a marked increase in DNA repair synthesis occurring during early times after UV irradiation in normal cells and in two of the xeroderma pigmentosum cell strains (groups C and D). This increase appeared to correlate with the increase in the highest acetylated form of histone H4. Furthermore, the total number of endonuclease-sensitive sites (i.e. prior to the onset of repair) induced by UV radiation was the same in both butyrated-treated and untreated normal cells over the dose range of 0-20 J/m2. However, the initial rate of removal of these sites increased in butyrate-treated normal cells. These results indicate that sodium butyrate stimulates the initial rate of nucleotide excision repair in both normal and (partially) repair-deficient human cells at concentrations where the histones are maximally hyperacetylated.
- Published
- 1982
21. Changes in gene position are accompanied by a change in time of replication.
- Author
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Calza RE, Eckhardt LA, DelGiudice T, and Schildkraut CL
- Subjects
- Animals, Cell Line, Genes, Genetic Linkage, Leukemia, Erythroblastic, Acute physiopathology, Mice, Oncogenes, Recombination, Genetic, DNA Replication, Immunoglobulin Heavy Chains genetics, Immunoglobulin alpha-Chains genetics
- Abstract
The globin and immunoglobulin multigene families have been used to study the effect of chromosomal organization on the time of gene replication. Some of the genes are late-replicating, providing the first identification of late-replicating sequences that are not highly repetitive. One is a member of the mouse alpha-globin gene family, which consists of genes mapping to three different chromosomes. The other genes in this family replicate early during S. Our studies demonstrate that immunoglobulin gene rearrangements and rearrangements between these genes and the c-myc oncogene are accompanied by dramatic differences in their temporal order of replication. We conclude that a gene's position in the chromosome, rather than its sequence, determines the time of replication. We suggest that the differences in association with gene rearrangement result from changes in the proximity of the affected gene to sites that control the temporal order of replication during S.
- Published
- 1984
- Full Text
- View/download PDF
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