The early events of Meloidogyne incognita behavior and associated host responses following root p... more The early events of Meloidogyne incognita behavior and associated host responses following root penetration were studied in resistant (cv. Moapa 69) and susceptible (cv. Lahontan) alfalfa. Ten-day-old seedlings of alfalfa cultivars were inoculated with second-stage juveniles (J2) and harvested 12, 24, 48, and 72 hours and 7, 14, and 21 days later. Both cultivars supported similar root penetration and initial J2 migration. By 72 hours after inoculation the majority of J2 were amassed inside the vascular cylinder in roots of susceptible Lahontan, while J2 had not entered the vascular cylinder of resistant Moapa 69 and remained clumped at the root apex. Nematode development progressed normally in Lahontan, but J2 were not observed in Moapa 69 after day 7. The greatest differences between RNA translation products isolated from inoculated and uninoculated roots of Lahanton occurred 72 hours after inoculation. Only minor differences in gene expression were observed between inoculated and uninoculated Moapa 69 roots at 72 hours. Comparison of translation products from inoculated versus mechanically wounded Lahontan roots revealed products that were specific to or enhanced in nematode-infected plants. Moapa 69 appears to possess a type of resistance to M. incognita that does not depend on a conventional hypersensitive response.
Interindividual variation in the spontaneous and in the glucocorticoid-or rifampicin-inducible ex... more Interindividual variation in the spontaneous and in the glucocorticoid-or rifampicin-inducible expression of the CYP3A cytochromes P450, the dominant froms of this supergene family that catalyze the oxidation of numerous drugs and environmental chemicals in human liver, remains largely unexplained, due in part to the lack of a validated animal model. We analyzed the 5'-flanking sequences of CYP3A genes from the rat (CYP3A23, CYP3A2), rabbit (CYP3A6), and human (CYP3A4, CYP3A5, CYP3A7) and found variable regions separated by three areas (consensus I, II, and III) of sequence homology immediately upstream of their respective promoters. We used trans-species gene transfer in cellulo as a new approach for determining the basis for qualitative differences among species in liver expression of different forms of CYP3A. When we transfected into cultured rat hepatocytes vectors containing 5'-flanking DNA from CYP3A23, CYP3A4, or CYP3A6 genes, we found that CAT activity was induced on treatment with dexamethasone or pregnenolone-16 alpha-carbonitrile only if consensus II sequences were included. Rifampicin treatment had no effect. When the same constructions containing consensus II were transfected into rabbit hepatocytes, increased activity was observed on treatment of the cells with dexamethasone or with rifampicin but not with pregnenolone-16 alpha-carbonitrile. These results suggest that the host cellular environment rather than the structure of the gene dictates the pattern of CYP3A inducibility. The application of this new model system will provide a unique technique for identifying mechanisms of induction and advancing the development of appropriate toxicological models for human safety assessment.
The macrolide antibiotic rifampicin is a potent inducer of cytochrome P-450-mediated drug metabol... more The macrolide antibiotic rifampicin is a potent inducer of cytochrome P-450-mediated drug metabolism in humans and rabbits. In this report, we demonstrate that in immature rabbits, rifampicin activates the transcription of the Cyp3A6 gene which encodes P450IIIA6 (cytochrome P-450 3c). The maximum increase in transcription was seen at 12 h following administration of rifampicin. Northern and slot blot analyses indicate that mRNAs corresponding to P450IIIA6 accumulates during the period of increased transcription and persist at 18 h when the rate of transcription has returned to basal levels. P450IIIA6 protein accumulates in liver microsomes over this period. At 24 h a greater than 10-fold increase in microsomal P450IIIA6 protein is detected by immunoblotting using a monoclonal antibody to P450IIIA6. The rate of microsomal progesterone 6 beta-hydroxylase activity is also elevated when compared to untreated rabbits, and this enzyme is activated in vitro by alpha-naphthoflavone. To determine whether this enzyme is stimulated by alpha-naphthoflavone in intact cells, COS-1 cells were transfected with an expression vector harboring the coding region of a P450IIIA6 cDNA. Our results demonstrate that the transfected COS-1 cells exhibit progesterone 6 beta-hydroxylase activity that is stimulated by alpha-naphthoflavone added to the culture medium.
Degenerate primers designed from conserved motifs of known plant resistance gene products were us... more Degenerate primers designed from conserved motifs of known plant resistance gene products were used to amplify genomic DNA sequences from the rootknot nematode (Meloidogyne incognita) resistance genetic source, Upland cotton (Gossypium hirsutum) cultivar Auburn 634 RNR. A total of 165 clones were isolated, and sequence analysis revealed 57 of the clones to be novel nucleotide sequences, many containing the resistance (R)-protein nucleotide-binding site motif. A cluster analysis was performed with resistance gene analogue (RGA) nucleotide sequences isolated in this study, in addition to 99 cotton RGA nucleotide sequences already deposited in GenBank, to generate a phylogenetic tree of cotton R genes. The cotton RGA nucleotide sequences were arranged into 11 groups and 56 subgroups , based on genetic distances. Multiple sequence alignments were performed on the RGA sequences of each subgroup , and either the consensus sequences or individual RGA sequences were used to design 61 RGA-sequence-tagged site primers. A recombinant inbred line (RIL) population of cultivated tetraploid cotton was genotyped using RGA-specific primers that amplified polymorphic fragments between the two RIL parents. Nine RGA markers were mapped to homeologous chromosomes 12 and 26, based on linkage to existing markers that are located on these chromosomes.
We have identified a single putative plastidic glutamine synthetase (GS 2), isolated from Medicag... more We have identified a single putative plastidic glutamine synthetase (GS 2), isolated from Medicago sativa (alfalfa) leaf. Analysis of organ/ tissue specific expression of the GS 2 gene in this study has shown that it is expressed in all green tissues. We show that the alfalfa GS 2 gene is also expressed in nitrogen fixing root nodules where its expression is not regulated by fixed nitrogen. Treatment with nitrate (NO 3 À) results in the induction of GS 2 in the roots and leaves of alfalfa, but the signaling mechanism in the two organs is different. In the roots NO 3 À appears to act as a direct signal for the induction of GS 2 whereas in the leaves secondary metabolites of NO 3 À probably act as the signal. We also demonstrate that 2-oxoglutarate (2-OG), in combination with NO 3 À , appears to significantly induce GS 2 expression, pointing to 2-OG as a potential primary metabolic inducer of alfalfa GS 2. Treatment with glutamine or sucrose, in combination with NO 3 À , also appears to induce GS 2 in the roots, but there is a lag in the induction when compared to the 2-OG/NO 3 À combination. Our interest ultimately lies in dissecting how carbon:nitrogen status modulates the expression of GS at transcriptional and post-transcriptional levels.
In Vitro Cellular & Developmental Biology - Plant, 2005
Since maize is a primary food stuff for humans and livestock, its amino acid balance is important... more Since maize is a primary food stuff for humans and livestock, its amino acid balance is important for proper nutrition. Methionine, an essential amino acid and a primary source of sulfur, is lacking in maize endosperm. Several maize populations were developed through breeding with enhanced methionine content in comparison with normal maize populations. BS31HM (high methionine) and BS31LM (low methionine) maize were among such populations created by the selection from the highest or lowest methionine content population from original BS31 maize. Candidate gene approach was adopted to determine the difference between the two populations at transcript level of the selected genes in the endosperm. The genes selected were mostly expressed in the endosperm and could be involved in enhanced methionine biosynthesis. The selected genes, that is, 15-kDa β-zein, 16-kDa γ-zein, 19-kDa α-zeinB1, 27-kDa γ-zein, 22-kDa α-zein and 18-kDa δ-zein were responsible for coding of endosperm storage proteins when analyzed through RT-PCR. Similarly, expression level relative to the high population (2-∆∆ct) values were also calculated for BS31HM and BS31LM, respectively. These values were found as 1 and 0.25, 1 and 0.07, 1 and 0.10, 1 and 0.15, 1 and 0.33, 1 and 0.43 for 27-kDa γ-zein, 22-kDa α-zein, 18-kDa δ-zein, 15-kDa β-zein, 16-kDa γ-zein and 19-kDa α-zeinB1, respectively, in both populations. The p-values were determined by student's t-test at confidence level of 95%. The expression of 18-kDa δ-gene, 15-kDa β-gene and 16-kDa γ-gene were found to be significant (p < 0.05) in high methionine maize population when compared with low methionine maize population. Non significant (p > 0.05) differences in the expression level of 27-kDa γ-gene, 22-kDa α-gene and 19-kDa αgene were observed in both HM and LM maize populations. From these results it can be concluded that all zein genes did not show expression equally in high and low methionine maize populations.
... Galling Index as a Criterion. Jinfa Zhang * a ,; C. Waddell a ,; C. Sengupta-Gopalan a ,; C. ... more ... Galling Index as a Criterion. Jinfa Zhang * a ,; C. Waddell a ,; C. Sengupta-Gopalan a ,; C. Potenza a and; RG Cantrell b. a Dep. of Plant and Environ. ... The holes were covered with the sandy loam soil immediately after planting. ...
Proceedings of the National Academy of Sciences of the United States of America, 1986
Several overlapping lambda gt11 cDNA clones have been sequenced and shown to encode for the full-... more Several overlapping lambda gt11 cDNA clones have been sequenced and shown to encode for the full-length human cytochrome P-450 4. The structure and location of the exons and flanking intron regions were also identified from a lambda EMBL-3 human genomic clone that encodes the full-length human P-450 4 gene. The human P-450 4 mRNA is flanked by 62 base pairs of 5'- and 1508 base pairs of 3'-noncoding sequence, with 1548 bases that encode a protein of 516 amino acids (Mr, 58,376). The predicted amino acid sequence of human P-450 4 is 69% and 70% homologous to its equivalent in mouse and rat, respectively, 75% homologous to rabbit P-450 4, and 68% homologous to human P1-450. The 7.6-kilobase gene encodes 3118 nucleotides of exon sequence that is separated by six introns into seven exons. Exon 7, which is 1802 nucleotides, contains three inverse/complement Alu sequences that are organized in tandem. Comparison of the genomic DNA sequence of the human P-450 4 gene with the human ...
A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible a... more A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible alfalfa cv. Lahontan seedlings 72 h after root-knot nematode inoculation was differentially screened with cDNA made from uninoculated control and M. incognita infested (72 h) root RNA. Of the six cDNAs isolated, the deduced amino acid sequences of four showed significant homology to sequences present in the databank, while two were pioneer sequences. The four cDNAs with matches to known sequences include those for glycine-rich protein, the gluconeogenic pathway enzyme phosphoenolpyruvate carboxykinase, an isoflavone reductase-like protein, and metallothionein. We have followed the expression of these genes during the course of nematode infection in both the susceptible and resistant host and also in different plant organs. Based on these analyses, the genes induced early in nematode infection are related either to metabolic pathways or to stress/defense.
Clarification of the genetic basis for root-knot nematode (RKN) resistance in the Auburn source a... more Clarification of the genetic basis for root-knot nematode (RKN) resistance in the Auburn source and development of closely linked markers to the resistance could finally put the RKN resistance gene(s) to work in cotton breeding. This study was conducted to verify the genetic mechanism of the Auburn source and to verify and identify molecular markers for the RKN resistance. Two F2 populations using Auburn 634 and its derived resistant line M-240 confirmed that the resistance is either controlled by one dominant gene or one dominant gene and one recessive gene. By comparing several pairs of near isogenic lines (NILs) with or without the Auburn source resistance, none of the previously reported RAPD and SSR markers exhibited consistent polymorphism, indicating that they were not closely linked to the RKN resistance. However, several SSR and two RGA markers were identified to be consistently polymorphic between the NILs. These markers will be employed in our mapping populations to evaluate their linkage with the RKN resistant gene(s).
Plant genetic engineering has contributed substantially to the understanding of gene regulation a... more Plant genetic engineering has contributed substantially to the understanding of gene regulation and plant development, in the generation of transgenic organisms for widespread usage in agriculture, and has increased the potential uses of crops for industrial and pharmaceutical purposes. As the application of genetically engineered plants has widened, so has the need to develop methods to fine-tune control of transgene expression. The availability of a broad spectrum of promoters that differ in their ability to regulate the temporal and spatial expression patterns of the transgene can dramatically increase the successful application of transgenic technology. Indeed, a variety of promoters is necessary at all levels of genetic engineering in plants, from basic research discoveries, concepts and questions, to development of economically viable crops and plant commodities, to addressing legitimate concerns raised about the safety and containment of transgenic plants in the environment. This review covers the characterization and usage of a broad range of promoters employed in plant genetic engineering, including the widespread use of plant promoters with viral and plant origin that drive constitutive expression. Also covered are selected tissue-specific promoters from fruit, seed and grain, tubers, flowers, pistils, anther and pollen, roots and root nodules, and leaves and green tissue. Topics also include organellar promoters, and those found in specific cell types, as well as the development and evaluation of inducible (endogenous and exogenous origin) and synthetic plant promoter systems. Discussions on the relevance and potential pitfalls within specific applications are included.
Higher plants assimilate nitrogen in the form of ammonia through the concerted activity of glutam... more Higher plants assimilate nitrogen in the form of ammonia through the concerted activity of glutamine synthetase (GS) and glutamate synthase (GOGAT). The GS enzyme is either located in the cytoplasm (GS1) or in the chloroplast (GS2). Glutamine synthetase 1 is regulated in different plants at the transcriptional level and there are some reports of regulation at the level of protein stability. Here we present data that clearly establish that GS1 in plants is also regulated at the level of transcript turnover and at the translational level. Using a Glycine max (soybean) GS1 transgene, with and without its 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; untranslated region (UTR), driven by the constitutive CaMV 35S promoter in Medicago sativa (alfalfa) and Nicotiana tabacum (tobacco), we show that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR plays a major role in both transcript turnover and translation repression in both the leaves and the nodules. Our data suggest that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR mediated turnover of the transcript is regulated by a nitrogen metabolite or carbon/nitrogen ratios. We also show that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR of the gene for the soybean GS1 confers post-transcriptional regulation on a reporter gene. Our dissection of post-transcriptional and translational levels of regulation of GS in plants shows that the situation in plants strongly resembles that in other organisms where GS is regulated at almost all levels. Multistep regulation of GS shows the high priority given by organisms to regulating and ensuring optimal control of nitrogen substrates and preventing overproduction of glutamine and drainage of the glutamate pool.
Proceedings of the National Academy of Sciences, 1986
Several overlapping Xgtll cDNA clones have been sequenced and shown to encode for the full-length... more Several overlapping Xgtll cDNA clones have been sequenced and shown to encode for the full-length human cytochrome P-450 4. The structure and location of the exons and flanking intron regions were also identified from a XEMBL-3 human genomic clone that encodes the full-length human P-450 4 gene. The human P-450 4 mRNA is flanked by 62 base pairs of 5'and 1508 base pairs of 3'-noncoding sequence, with 1548 bases that encode a protein of 516 amino acids (Mr, 58,376). The predicted amino acid sequence of
A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible a... more A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible alfalfa cv. Lahontan seedlings 72 h after root-knot nematode inoculation was differentially screened with cDNA made from uninoculated control and M. incognita infested (72 h) root RNA. Of the six cDNAs isolated, the deduced amino acid sequences of four showed significant homology to sequences present in the databank, while two were pioneer sequences. The four cDNAs with matches to known sequences include those for glycine-rich protein, the gluconeogenic pathway enzyme phosphoenolpyruvate carboxykinase, an isoflavone reductase-like protein, and metallothionein. We have followed the expression of these genes during the course of nematode infection in both the susceptible and resistant host and also in different plant organs. Based on these analyses, the genes induced early in nematode infection are related either to metabolic pathways or to stress/defense.
The early events of Meloidogyne incognita behavior and associated host responses following root p... more The early events of Meloidogyne incognita behavior and associated host responses following root penetration were studied in resistant (cv. Moapa 69) and susceptible (cv. Lahontan) alfalfa. Ten-day-old seedlings of alfalfa cultivars were inoculated with second-stage juveniles (J2) and harvested 12, 24, 48, and 72 hours and 7, 14, and 21 days later. Both cultivars supported similar root penetration and initial J2 migration. By 72 hours after inoculation the majority of J2 were amassed inside the vascular cylinder in roots of susceptible Lahontan, while J2 had not entered the vascular cylinder of resistant Moapa 69 and remained clumped at the root apex. Nematode development progressed normally in Lahontan, but J2 were not observed in Moapa 69 after day 7. The greatest differences between RNA translation products isolated from inoculated and uninoculated roots of Lahanton occurred 72 hours after inoculation. Only minor differences in gene expression were observed between inoculated and uninoculated Moapa 69 roots at 72 hours. Comparison of translation products from inoculated versus mechanically wounded Lahontan roots revealed products that were specific to or enhanced in nematode-infected plants. Moapa 69 appears to possess a type of resistance to M. incognita that does not depend on a conventional hypersensitive response.
Interindividual variation in the spontaneous and in the glucocorticoid-or rifampicin-inducible ex... more Interindividual variation in the spontaneous and in the glucocorticoid-or rifampicin-inducible expression of the CYP3A cytochromes P450, the dominant froms of this supergene family that catalyze the oxidation of numerous drugs and environmental chemicals in human liver, remains largely unexplained, due in part to the lack of a validated animal model. We analyzed the 5'-flanking sequences of CYP3A genes from the rat (CYP3A23, CYP3A2), rabbit (CYP3A6), and human (CYP3A4, CYP3A5, CYP3A7) and found variable regions separated by three areas (consensus I, II, and III) of sequence homology immediately upstream of their respective promoters. We used trans-species gene transfer in cellulo as a new approach for determining the basis for qualitative differences among species in liver expression of different forms of CYP3A. When we transfected into cultured rat hepatocytes vectors containing 5'-flanking DNA from CYP3A23, CYP3A4, or CYP3A6 genes, we found that CAT activity was induced on treatment with dexamethasone or pregnenolone-16 alpha-carbonitrile only if consensus II sequences were included. Rifampicin treatment had no effect. When the same constructions containing consensus II were transfected into rabbit hepatocytes, increased activity was observed on treatment of the cells with dexamethasone or with rifampicin but not with pregnenolone-16 alpha-carbonitrile. These results suggest that the host cellular environment rather than the structure of the gene dictates the pattern of CYP3A inducibility. The application of this new model system will provide a unique technique for identifying mechanisms of induction and advancing the development of appropriate toxicological models for human safety assessment.
The macrolide antibiotic rifampicin is a potent inducer of cytochrome P-450-mediated drug metabol... more The macrolide antibiotic rifampicin is a potent inducer of cytochrome P-450-mediated drug metabolism in humans and rabbits. In this report, we demonstrate that in immature rabbits, rifampicin activates the transcription of the Cyp3A6 gene which encodes P450IIIA6 (cytochrome P-450 3c). The maximum increase in transcription was seen at 12 h following administration of rifampicin. Northern and slot blot analyses indicate that mRNAs corresponding to P450IIIA6 accumulates during the period of increased transcription and persist at 18 h when the rate of transcription has returned to basal levels. P450IIIA6 protein accumulates in liver microsomes over this period. At 24 h a greater than 10-fold increase in microsomal P450IIIA6 protein is detected by immunoblotting using a monoclonal antibody to P450IIIA6. The rate of microsomal progesterone 6 beta-hydroxylase activity is also elevated when compared to untreated rabbits, and this enzyme is activated in vitro by alpha-naphthoflavone. To determine whether this enzyme is stimulated by alpha-naphthoflavone in intact cells, COS-1 cells were transfected with an expression vector harboring the coding region of a P450IIIA6 cDNA. Our results demonstrate that the transfected COS-1 cells exhibit progesterone 6 beta-hydroxylase activity that is stimulated by alpha-naphthoflavone added to the culture medium.
Degenerate primers designed from conserved motifs of known plant resistance gene products were us... more Degenerate primers designed from conserved motifs of known plant resistance gene products were used to amplify genomic DNA sequences from the rootknot nematode (Meloidogyne incognita) resistance genetic source, Upland cotton (Gossypium hirsutum) cultivar Auburn 634 RNR. A total of 165 clones were isolated, and sequence analysis revealed 57 of the clones to be novel nucleotide sequences, many containing the resistance (R)-protein nucleotide-binding site motif. A cluster analysis was performed with resistance gene analogue (RGA) nucleotide sequences isolated in this study, in addition to 99 cotton RGA nucleotide sequences already deposited in GenBank, to generate a phylogenetic tree of cotton R genes. The cotton RGA nucleotide sequences were arranged into 11 groups and 56 subgroups , based on genetic distances. Multiple sequence alignments were performed on the RGA sequences of each subgroup , and either the consensus sequences or individual RGA sequences were used to design 61 RGA-sequence-tagged site primers. A recombinant inbred line (RIL) population of cultivated tetraploid cotton was genotyped using RGA-specific primers that amplified polymorphic fragments between the two RIL parents. Nine RGA markers were mapped to homeologous chromosomes 12 and 26, based on linkage to existing markers that are located on these chromosomes.
We have identified a single putative plastidic glutamine synthetase (GS 2), isolated from Medicag... more We have identified a single putative plastidic glutamine synthetase (GS 2), isolated from Medicago sativa (alfalfa) leaf. Analysis of organ/ tissue specific expression of the GS 2 gene in this study has shown that it is expressed in all green tissues. We show that the alfalfa GS 2 gene is also expressed in nitrogen fixing root nodules where its expression is not regulated by fixed nitrogen. Treatment with nitrate (NO 3 À) results in the induction of GS 2 in the roots and leaves of alfalfa, but the signaling mechanism in the two organs is different. In the roots NO 3 À appears to act as a direct signal for the induction of GS 2 whereas in the leaves secondary metabolites of NO 3 À probably act as the signal. We also demonstrate that 2-oxoglutarate (2-OG), in combination with NO 3 À , appears to significantly induce GS 2 expression, pointing to 2-OG as a potential primary metabolic inducer of alfalfa GS 2. Treatment with glutamine or sucrose, in combination with NO 3 À , also appears to induce GS 2 in the roots, but there is a lag in the induction when compared to the 2-OG/NO 3 À combination. Our interest ultimately lies in dissecting how carbon:nitrogen status modulates the expression of GS at transcriptional and post-transcriptional levels.
In Vitro Cellular & Developmental Biology - Plant, 2005
Since maize is a primary food stuff for humans and livestock, its amino acid balance is important... more Since maize is a primary food stuff for humans and livestock, its amino acid balance is important for proper nutrition. Methionine, an essential amino acid and a primary source of sulfur, is lacking in maize endosperm. Several maize populations were developed through breeding with enhanced methionine content in comparison with normal maize populations. BS31HM (high methionine) and BS31LM (low methionine) maize were among such populations created by the selection from the highest or lowest methionine content population from original BS31 maize. Candidate gene approach was adopted to determine the difference between the two populations at transcript level of the selected genes in the endosperm. The genes selected were mostly expressed in the endosperm and could be involved in enhanced methionine biosynthesis. The selected genes, that is, 15-kDa β-zein, 16-kDa γ-zein, 19-kDa α-zeinB1, 27-kDa γ-zein, 22-kDa α-zein and 18-kDa δ-zein were responsible for coding of endosperm storage proteins when analyzed through RT-PCR. Similarly, expression level relative to the high population (2-∆∆ct) values were also calculated for BS31HM and BS31LM, respectively. These values were found as 1 and 0.25, 1 and 0.07, 1 and 0.10, 1 and 0.15, 1 and 0.33, 1 and 0.43 for 27-kDa γ-zein, 22-kDa α-zein, 18-kDa δ-zein, 15-kDa β-zein, 16-kDa γ-zein and 19-kDa α-zeinB1, respectively, in both populations. The p-values were determined by student's t-test at confidence level of 95%. The expression of 18-kDa δ-gene, 15-kDa β-gene and 16-kDa γ-gene were found to be significant (p < 0.05) in high methionine maize population when compared with low methionine maize population. Non significant (p > 0.05) differences in the expression level of 27-kDa γ-gene, 22-kDa α-gene and 19-kDa αgene were observed in both HM and LM maize populations. From these results it can be concluded that all zein genes did not show expression equally in high and low methionine maize populations.
... Galling Index as a Criterion. Jinfa Zhang * a ,; C. Waddell a ,; C. Sengupta-Gopalan a ,; C. ... more ... Galling Index as a Criterion. Jinfa Zhang * a ,; C. Waddell a ,; C. Sengupta-Gopalan a ,; C. Potenza a and; RG Cantrell b. a Dep. of Plant and Environ. ... The holes were covered with the sandy loam soil immediately after planting. ...
Proceedings of the National Academy of Sciences of the United States of America, 1986
Several overlapping lambda gt11 cDNA clones have been sequenced and shown to encode for the full-... more Several overlapping lambda gt11 cDNA clones have been sequenced and shown to encode for the full-length human cytochrome P-450 4. The structure and location of the exons and flanking intron regions were also identified from a lambda EMBL-3 human genomic clone that encodes the full-length human P-450 4 gene. The human P-450 4 mRNA is flanked by 62 base pairs of 5'- and 1508 base pairs of 3'-noncoding sequence, with 1548 bases that encode a protein of 516 amino acids (Mr, 58,376). The predicted amino acid sequence of human P-450 4 is 69% and 70% homologous to its equivalent in mouse and rat, respectively, 75% homologous to rabbit P-450 4, and 68% homologous to human P1-450. The 7.6-kilobase gene encodes 3118 nucleotides of exon sequence that is separated by six introns into seven exons. Exon 7, which is 1802 nucleotides, contains three inverse/complement Alu sequences that are organized in tandem. Comparison of the genomic DNA sequence of the human P-450 4 gene with the human ...
A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible a... more A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible alfalfa cv. Lahontan seedlings 72 h after root-knot nematode inoculation was differentially screened with cDNA made from uninoculated control and M. incognita infested (72 h) root RNA. Of the six cDNAs isolated, the deduced amino acid sequences of four showed significant homology to sequences present in the databank, while two were pioneer sequences. The four cDNAs with matches to known sequences include those for glycine-rich protein, the gluconeogenic pathway enzyme phosphoenolpyruvate carboxykinase, an isoflavone reductase-like protein, and metallothionein. We have followed the expression of these genes during the course of nematode infection in both the susceptible and resistant host and also in different plant organs. Based on these analyses, the genes induced early in nematode infection are related either to metabolic pathways or to stress/defense.
Clarification of the genetic basis for root-knot nematode (RKN) resistance in the Auburn source a... more Clarification of the genetic basis for root-knot nematode (RKN) resistance in the Auburn source and development of closely linked markers to the resistance could finally put the RKN resistance gene(s) to work in cotton breeding. This study was conducted to verify the genetic mechanism of the Auburn source and to verify and identify molecular markers for the RKN resistance. Two F2 populations using Auburn 634 and its derived resistant line M-240 confirmed that the resistance is either controlled by one dominant gene or one dominant gene and one recessive gene. By comparing several pairs of near isogenic lines (NILs) with or without the Auburn source resistance, none of the previously reported RAPD and SSR markers exhibited consistent polymorphism, indicating that they were not closely linked to the RKN resistance. However, several SSR and two RGA markers were identified to be consistently polymorphic between the NILs. These markers will be employed in our mapping populations to evaluate their linkage with the RKN resistant gene(s).
Plant genetic engineering has contributed substantially to the understanding of gene regulation a... more Plant genetic engineering has contributed substantially to the understanding of gene regulation and plant development, in the generation of transgenic organisms for widespread usage in agriculture, and has increased the potential uses of crops for industrial and pharmaceutical purposes. As the application of genetically engineered plants has widened, so has the need to develop methods to fine-tune control of transgene expression. The availability of a broad spectrum of promoters that differ in their ability to regulate the temporal and spatial expression patterns of the transgene can dramatically increase the successful application of transgenic technology. Indeed, a variety of promoters is necessary at all levels of genetic engineering in plants, from basic research discoveries, concepts and questions, to development of economically viable crops and plant commodities, to addressing legitimate concerns raised about the safety and containment of transgenic plants in the environment. This review covers the characterization and usage of a broad range of promoters employed in plant genetic engineering, including the widespread use of plant promoters with viral and plant origin that drive constitutive expression. Also covered are selected tissue-specific promoters from fruit, seed and grain, tubers, flowers, pistils, anther and pollen, roots and root nodules, and leaves and green tissue. Topics also include organellar promoters, and those found in specific cell types, as well as the development and evaluation of inducible (endogenous and exogenous origin) and synthetic plant promoter systems. Discussions on the relevance and potential pitfalls within specific applications are included.
Higher plants assimilate nitrogen in the form of ammonia through the concerted activity of glutam... more Higher plants assimilate nitrogen in the form of ammonia through the concerted activity of glutamine synthetase (GS) and glutamate synthase (GOGAT). The GS enzyme is either located in the cytoplasm (GS1) or in the chloroplast (GS2). Glutamine synthetase 1 is regulated in different plants at the transcriptional level and there are some reports of regulation at the level of protein stability. Here we present data that clearly establish that GS1 in plants is also regulated at the level of transcript turnover and at the translational level. Using a Glycine max (soybean) GS1 transgene, with and without its 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; untranslated region (UTR), driven by the constitutive CaMV 35S promoter in Medicago sativa (alfalfa) and Nicotiana tabacum (tobacco), we show that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR plays a major role in both transcript turnover and translation repression in both the leaves and the nodules. Our data suggest that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR mediated turnover of the transcript is regulated by a nitrogen metabolite or carbon/nitrogen ratios. We also show that the 3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; UTR of the gene for the soybean GS1 confers post-transcriptional regulation on a reporter gene. Our dissection of post-transcriptional and translational levels of regulation of GS in plants shows that the situation in plants strongly resembles that in other organisms where GS is regulated at almost all levels. Multistep regulation of GS shows the high priority given by organisms to regulating and ensuring optimal control of nitrogen substrates and preventing overproduction of glutamine and drainage of the glutamate pool.
Proceedings of the National Academy of Sciences, 1986
Several overlapping Xgtll cDNA clones have been sequenced and shown to encode for the full-length... more Several overlapping Xgtll cDNA clones have been sequenced and shown to encode for the full-length human cytochrome P-450 4. The structure and location of the exons and flanking intron regions were also identified from a XEMBL-3 human genomic clone that encodes the full-length human P-450 4 gene. The human P-450 4 mRNA is flanked by 62 base pairs of 5'and 1508 base pairs of 3'-noncoding sequence, with 1548 bases that encode a protein of 516 amino acids (Mr, 58,376). The predicted amino acid sequence of
A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible a... more A cDNA library made to RNA from roots of Meloidogyne incognita (root-knot nematode) susceptible alfalfa cv. Lahontan seedlings 72 h after root-knot nematode inoculation was differentially screened with cDNA made from uninoculated control and M. incognita infested (72 h) root RNA. Of the six cDNAs isolated, the deduced amino acid sequences of four showed significant homology to sequences present in the databank, while two were pioneer sequences. The four cDNAs with matches to known sequences include those for glycine-rich protein, the gluconeogenic pathway enzyme phosphoenolpyruvate carboxykinase, an isoflavone reductase-like protein, and metallothionein. We have followed the expression of these genes during the course of nematode infection in both the susceptible and resistant host and also in different plant organs. Based on these analyses, the genes induced early in nematode infection are related either to metabolic pathways or to stress/defense.
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Papers by Carol Potenza