John Vidmar - Academia.edu (original) (raw)
Papers by John Vidmar
Plant Nutrition — Molecular Biology and Genetics, 1999
Plant molecular biology, 2003
The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine... more The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine the regulation of NRT2.1 gene expression, we used a promoter-beta-glucuronidase (GUS) fusion and found that the NRT2.1 promoter directs expression to the epidermal, cortical and endodermal cell layers of mature root parts. The gene appeared to be expressed essentially in roots, but was also present in the leaf hydathodes. Investigation of NRT2.1 expression pattern during the plant developmental cycle showed that it increased rapidly during early vegetative growth, peaked prior to floral stem emergence, and decreased to very low levels in flowering and silique-bearing plants. Experiments with various nitrogen supply regimes demonstrated the induction of NRT2.1 expression by nitrate and repression by amino acids. Amino acid analysis showed that this repression was specifically related to increased internal glutamine, suggesting a role for this particular amino acid in nitrogen signalling ...
Plant & cell physiology, 2003
Four low-affinity (NRT1), and seven high-affinity (NRT2) nitrate transporter gene homologues have... more Four low-affinity (NRT1), and seven high-affinity (NRT2) nitrate transporter gene homologues have been identified in Arabidopsis thaliana. We investigated the transcript abundances of all eleven genes in shoot and root tissues in response to the provision of 1 mM NO(3)(-), using relative quantitative RT-PCR. Based upon this criterion, genes were classified as nitrate-inducible, nitrate-repressible, or nitrate-constitutive. AtNRT1.1, 2.1, and 2.2 were strongly induced by NO(3)(-), peaking at 3-12 h and subsequently declining. By contrast AtNRT2.4 showed only modest induction both in shoots and roots. Expression of AtNRT2.5, one of the nitrate-repressible genes, was strongly suppressed by nitrate provision in both roots and shoots. The last group, characterized by a constitutive expression pattern, included AtNRT1.2, 1.4, 2.3, 2.6, and 2.7. Correlation coefficients between (13)NO(3)(-) influx from 100 micro M and 5 mM [NO(3)(-)], suggest that high- and low-affinity transport systems a...
Mutation research, Jan 16, 1994
We have developed and tested a simple phenotypic assay which monitors C to T transition mutations... more We have developed and tested a simple phenotypic assay which monitors C to T transition mutations at the second C of a CCAGG sequence in the lacZ gene of Escherichia coli. The assay is based on new data concerning amino acid requirements on either side of a crucial active site residue in beta-galactosidase, glutamic acid 461. We show that the frequency of occurrence of the mutation is influenced by two genes: dcm, the cytosine methylase gene, and vsr, one of the genes involved in very short patch repair. The assay has been used to evaluate the function of vsr cloned from a potential very short patch repair mutant.
To determine effect of interaction between dietary cholesterol and triglycéride, i.e., polyunsat... more To determine effect of interaction between dietary cholesterol and triglycéride, i.e., polyunsaturated to saturated (P:S) fatty acid ratio, on LDLmetabolism, male cynomolgus macaques were fed purified diets for 83 wk with cholesterol levels of 0.01, 0.06 and 0.50 mg/kJ and P:S ratios of 0.5 and 0.9, oleic acid constant. There were six groups of five animals each (cholesterol, mg/kJâ€"P:Sratio): Group
Plant Nutrition — Molecular Biology and Genetics, 1999
INORGANIC NITROGEN ABSORPTION BY PLANT ROOTS: Physiology and Molecular Biology ANTHONY DM GLASS1,... more INORGANIC NITROGEN ABSORPTION BY PLANT ROOTS: Physiology and Molecular Biology ANTHONY DM GLASS1, YAIR ERNER2, TAMERA HUNT1, HERBERT J. KRONZUCKER1, MAMORU OKAMOTO1, SUMAN RAWAT1, SALIM SILIM1, JAN K. SCHJOERRING3, M. YAEESH ...
The Plant Journal, 1999
Putative high-affinity nitrate (NO 3 -) transporter genes, designated Nrt2;1At and Nrt2;2At, were... more Putative high-affinity nitrate (NO 3 -) transporter genes, designated Nrt2;1At and Nrt2;2At, were isolated from Arabidopsis thaliana by RT-PCR using degenerate primers. The genes shared 86% and 89% identity at the amino acid and nucleotide levels, respectively, while their proteins shared 30-73% identities with other eukaryotic highaffinity NO 3 transporters. Both genes were induced by NO 3 -, but Nrt2;1At gene expression was not apparent in 2-and 5-day-old plants. By 10 days, and thereafter, Nrt2; 1At gene expression in roots was substantially higher than for the Nrt2;2At gene. Root Nrt2;1At expression levels were strongly correlated with inducible high-affinity 13 NO 3 influx into intact roots under several treatment conditions. The use of inhibitors of N assimilation indicated that downregulation of Nrt2;1At expression was mediated by NH 4 ⍣ , gln and other amino acids.
The Plant Journal, 1999
Sulfate uptake and ATP sulfurylase activity in the roots of Arabidopsis thaliana and Brassica nap... more Sulfate uptake and ATP sulfurylase activity in the roots of Arabidopsis thaliana and Brassica napus were enhanced by S deprivation and reduced following resupply of SO 4 2-.
Plant Growth Regulation, 2000
ABSTRACT The effects of various growth regulators in Bambusa edulis inflorescence proliferation w... more ABSTRACT The effects of various growth regulators in Bambusa edulis inflorescence proliferation were studied. Cytokinin is essential for inflorescence proliferation. Thidiazuron (TDZ) had been the most efficient cytokinin to induce inflorescence proliferation. The optimal TDZ concentration was 0.01–0.1mgl–1. Inflorescences did not proliferate in media containing auxin, gibberellic acid (GA3), abscisic acid (ABA), or 1-amino- cyclopropane-1-carboxylic acid (ACC) alone. In TDZ-containing medium, the proliferation ratio decreased when the naphthaleneacetic acid (NAA) concentration higher than 5mgl–1.
Functional Plant Biology, 2007
Page 1. CSIRO PUBLISHING www.publish.csiro.au/journals/fpb Functional Plant Biology, 2007, 34, 73... more Page 1. CSIRO PUBLISHING www.publish.csiro.au/journals/fpb Functional Plant Biology, 2007, 34, 737749 Microarray analysis of bast fibre producing tissues of Cannabis sativa identifies transcripts associated with conserved and specialised ...
Canadian Journal of Microbiology, 1993
We have determined the numbers and types of mutations that occur in strains of Escherichia coli d... more We have determined the numbers and types of mutations that occur in strains of Escherichia coli defective in mutT and (or) mutY repair. High rates of C.G to A.T mutations in mutY- cells are unaffected by the status of mutT. However, mutT-/mutY+ strains have higher rates of A.T to C.G mutations than mutT-/mutY- strains. This result indicates that the high rates of A.T to C.G mutations seen in mutT- strains of E. coli are due in part to the activity of the mutY repair system. We conclude that mutY repair is mutagenic in a mutT- background.
Canadian Journal of Botany, 2007
Nitrogen (N) is the most important factor limiting crop productivity worldwide. The ability of pl... more Nitrogen (N) is the most important factor limiting crop productivity worldwide. The ability of plants to acquire N from applied fertilizers is one of the critical steps limiting the efficient use of nitrogen. To improve N use efficiency, genetically modified plants that overexpress alanine aminotransferase (AlaAT) were engineered by introducing a barley AlaAT cDNA driven by a canola root specific promoter (btg26). Compared with wild-type canola, transgenic plants had increased biomass and seed yield both in the laboratory and field under low N conditions, whereas no differences were observed under high N. The transgenics also had increased nitrate influx. These changes resulted in a 40% decrease in the amount of applied nitrogen fertilizer required under field conditions to achieve yields equivalent to wild-type plants.
The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine... more The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine the regulation of NRT2.1 gene expression, we used a promoter-beta-glucuronidase (GUS) fusion and found that the NRT2.1 promoter directs expression to the epidermal, cortical and endodermal cell layers of mature root parts. The gene appeared to be expressed essentially in roots, but was also present in the leaf hydathodes. Investigation of NRT2.1 expression pattern during the plant developmental cycle showed that it increased rapidly during early vegetative growth, peaked prior to floral stem emergence, and decreased to very low levels in flowering and silique-bearing plants. Experiments with various nitrogen supply regimes demonstrated the induction of NRT2.1 expression by nitrate and repression by amino acids. Amino acid analysis showed that this repression was specifically related to increased internal glutamine, suggesting a role for this particular amino acid in nitrogen signalling responsible for nitrate uptake regulation. Taken together, our results support the hypothesis that the NRT2.1 gene codes for a major component of the inducible high-affinity transport system for nitrate, which is spatially and developmentally controlled at the transcriptional level. Surprisingly, NRT2.1 was not expressed in younger root parts, although a similar rate of nitrate influx was observed in both young and old root samples. This lack of correlation between nitrate influx and NRT2.1 expression suggests that another high-affinity nitrate transporter operates in root tips.
Acta Physiologiae Plantarum, 2011
Barley is a cereal grain derived from annual grass. In modern agriculture, barley plays a signifi... more Barley is a cereal grain derived from annual grass. In modern agriculture, barley plays a significant role as feedstock for feed, malt and food. During its life cycle, as do most plants, barley faces numerous external challenges from the environment. Both biotic and abiotic stresses decrease the growth, yield and cultivation area of barley. Plants have to respond to biotic
Canadian Unconventional Resources Conference, 2011
Plant Nutrition — Molecular Biology and Genetics, 1999
Plant molecular biology, 2003
The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine... more The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine the regulation of NRT2.1 gene expression, we used a promoter-beta-glucuronidase (GUS) fusion and found that the NRT2.1 promoter directs expression to the epidermal, cortical and endodermal cell layers of mature root parts. The gene appeared to be expressed essentially in roots, but was also present in the leaf hydathodes. Investigation of NRT2.1 expression pattern during the plant developmental cycle showed that it increased rapidly during early vegetative growth, peaked prior to floral stem emergence, and decreased to very low levels in flowering and silique-bearing plants. Experiments with various nitrogen supply regimes demonstrated the induction of NRT2.1 expression by nitrate and repression by amino acids. Amino acid analysis showed that this repression was specifically related to increased internal glutamine, suggesting a role for this particular amino acid in nitrogen signalling ...
Plant & cell physiology, 2003
Four low-affinity (NRT1), and seven high-affinity (NRT2) nitrate transporter gene homologues have... more Four low-affinity (NRT1), and seven high-affinity (NRT2) nitrate transporter gene homologues have been identified in Arabidopsis thaliana. We investigated the transcript abundances of all eleven genes in shoot and root tissues in response to the provision of 1 mM NO(3)(-), using relative quantitative RT-PCR. Based upon this criterion, genes were classified as nitrate-inducible, nitrate-repressible, or nitrate-constitutive. AtNRT1.1, 2.1, and 2.2 were strongly induced by NO(3)(-), peaking at 3-12 h and subsequently declining. By contrast AtNRT2.4 showed only modest induction both in shoots and roots. Expression of AtNRT2.5, one of the nitrate-repressible genes, was strongly suppressed by nitrate provision in both roots and shoots. The last group, characterized by a constitutive expression pattern, included AtNRT1.2, 1.4, 2.3, 2.6, and 2.7. Correlation coefficients between (13)NO(3)(-) influx from 100 micro M and 5 mM [NO(3)(-)], suggest that high- and low-affinity transport systems a...
Mutation research, Jan 16, 1994
We have developed and tested a simple phenotypic assay which monitors C to T transition mutations... more We have developed and tested a simple phenotypic assay which monitors C to T transition mutations at the second C of a CCAGG sequence in the lacZ gene of Escherichia coli. The assay is based on new data concerning amino acid requirements on either side of a crucial active site residue in beta-galactosidase, glutamic acid 461. We show that the frequency of occurrence of the mutation is influenced by two genes: dcm, the cytosine methylase gene, and vsr, one of the genes involved in very short patch repair. The assay has been used to evaluate the function of vsr cloned from a potential very short patch repair mutant.
To determine effect of interaction between dietary cholesterol and triglycéride, i.e., polyunsat... more To determine effect of interaction between dietary cholesterol and triglycéride, i.e., polyunsaturated to saturated (P:S) fatty acid ratio, on LDLmetabolism, male cynomolgus macaques were fed purified diets for 83 wk with cholesterol levels of 0.01, 0.06 and 0.50 mg/kJ and P:S ratios of 0.5 and 0.9, oleic acid constant. There were six groups of five animals each (cholesterol, mg/kJâ€"P:Sratio): Group
Plant Nutrition — Molecular Biology and Genetics, 1999
INORGANIC NITROGEN ABSORPTION BY PLANT ROOTS: Physiology and Molecular Biology ANTHONY DM GLASS1,... more INORGANIC NITROGEN ABSORPTION BY PLANT ROOTS: Physiology and Molecular Biology ANTHONY DM GLASS1, YAIR ERNER2, TAMERA HUNT1, HERBERT J. KRONZUCKER1, MAMORU OKAMOTO1, SUMAN RAWAT1, SALIM SILIM1, JAN K. SCHJOERRING3, M. YAEESH ...
The Plant Journal, 1999
Putative high-affinity nitrate (NO 3 -) transporter genes, designated Nrt2;1At and Nrt2;2At, were... more Putative high-affinity nitrate (NO 3 -) transporter genes, designated Nrt2;1At and Nrt2;2At, were isolated from Arabidopsis thaliana by RT-PCR using degenerate primers. The genes shared 86% and 89% identity at the amino acid and nucleotide levels, respectively, while their proteins shared 30-73% identities with other eukaryotic highaffinity NO 3 transporters. Both genes were induced by NO 3 -, but Nrt2;1At gene expression was not apparent in 2-and 5-day-old plants. By 10 days, and thereafter, Nrt2; 1At gene expression in roots was substantially higher than for the Nrt2;2At gene. Root Nrt2;1At expression levels were strongly correlated with inducible high-affinity 13 NO 3 influx into intact roots under several treatment conditions. The use of inhibitors of N assimilation indicated that downregulation of Nrt2;1At expression was mediated by NH 4 ⍣ , gln and other amino acids.
The Plant Journal, 1999
Sulfate uptake and ATP sulfurylase activity in the roots of Arabidopsis thaliana and Brassica nap... more Sulfate uptake and ATP sulfurylase activity in the roots of Arabidopsis thaliana and Brassica napus were enhanced by S deprivation and reduced following resupply of SO 4 2-.
Plant Growth Regulation, 2000
ABSTRACT The effects of various growth regulators in Bambusa edulis inflorescence proliferation w... more ABSTRACT The effects of various growth regulators in Bambusa edulis inflorescence proliferation were studied. Cytokinin is essential for inflorescence proliferation. Thidiazuron (TDZ) had been the most efficient cytokinin to induce inflorescence proliferation. The optimal TDZ concentration was 0.01–0.1mgl–1. Inflorescences did not proliferate in media containing auxin, gibberellic acid (GA3), abscisic acid (ABA), or 1-amino- cyclopropane-1-carboxylic acid (ACC) alone. In TDZ-containing medium, the proliferation ratio decreased when the naphthaleneacetic acid (NAA) concentration higher than 5mgl–1.
Functional Plant Biology, 2007
Page 1. CSIRO PUBLISHING www.publish.csiro.au/journals/fpb Functional Plant Biology, 2007, 34, 73... more Page 1. CSIRO PUBLISHING www.publish.csiro.au/journals/fpb Functional Plant Biology, 2007, 34, 737749 Microarray analysis of bast fibre producing tissues of Cannabis sativa identifies transcripts associated with conserved and specialised ...
Canadian Journal of Microbiology, 1993
We have determined the numbers and types of mutations that occur in strains of Escherichia coli d... more We have determined the numbers and types of mutations that occur in strains of Escherichia coli defective in mutT and (or) mutY repair. High rates of C.G to A.T mutations in mutY- cells are unaffected by the status of mutT. However, mutT-/mutY+ strains have higher rates of A.T to C.G mutations than mutT-/mutY- strains. This result indicates that the high rates of A.T to C.G mutations seen in mutT- strains of E. coli are due in part to the activity of the mutY repair system. We conclude that mutY repair is mutagenic in a mutT- background.
Canadian Journal of Botany, 2007
Nitrogen (N) is the most important factor limiting crop productivity worldwide. The ability of pl... more Nitrogen (N) is the most important factor limiting crop productivity worldwide. The ability of plants to acquire N from applied fertilizers is one of the critical steps limiting the efficient use of nitrogen. To improve N use efficiency, genetically modified plants that overexpress alanine aminotransferase (AlaAT) were engineered by introducing a barley AlaAT cDNA driven by a canola root specific promoter (btg26). Compared with wild-type canola, transgenic plants had increased biomass and seed yield both in the laboratory and field under low N conditions, whereas no differences were observed under high N. The transgenics also had increased nitrate influx. These changes resulted in a 40% decrease in the amount of applied nitrogen fertilizer required under field conditions to achieve yields equivalent to wild-type plants.
The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine... more The NR72.1 gene codes for a high-affinity nitrate transporter in Arabidopsis thaliana. To examine the regulation of NRT2.1 gene expression, we used a promoter-beta-glucuronidase (GUS) fusion and found that the NRT2.1 promoter directs expression to the epidermal, cortical and endodermal cell layers of mature root parts. The gene appeared to be expressed essentially in roots, but was also present in the leaf hydathodes. Investigation of NRT2.1 expression pattern during the plant developmental cycle showed that it increased rapidly during early vegetative growth, peaked prior to floral stem emergence, and decreased to very low levels in flowering and silique-bearing plants. Experiments with various nitrogen supply regimes demonstrated the induction of NRT2.1 expression by nitrate and repression by amino acids. Amino acid analysis showed that this repression was specifically related to increased internal glutamine, suggesting a role for this particular amino acid in nitrogen signalling responsible for nitrate uptake regulation. Taken together, our results support the hypothesis that the NRT2.1 gene codes for a major component of the inducible high-affinity transport system for nitrate, which is spatially and developmentally controlled at the transcriptional level. Surprisingly, NRT2.1 was not expressed in younger root parts, although a similar rate of nitrate influx was observed in both young and old root samples. This lack of correlation between nitrate influx and NRT2.1 expression suggests that another high-affinity nitrate transporter operates in root tips.
Acta Physiologiae Plantarum, 2011
Barley is a cereal grain derived from annual grass. In modern agriculture, barley plays a signifi... more Barley is a cereal grain derived from annual grass. In modern agriculture, barley plays a significant role as feedstock for feed, malt and food. During its life cycle, as do most plants, barley faces numerous external challenges from the environment. Both biotic and abiotic stresses decrease the growth, yield and cultivation area of barley. Plants have to respond to biotic
Canadian Unconventional Resources Conference, 2011