| 5432 matches found in 4023 documents. Search time: 3.167 seconds. |
|---|
|
Score: 1.00 |
|---|
| Title: Isoform-specific effects of charged residues at borders of the M1-M2 loop of the Na , K-ATPase alpha subunit .
| | Author: Coppi MV Compton LA Guidotti G | | Journal: Biochemistry Citation: V : 38 ( 8 ) P : 2494-505 Year: 1999 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10029544 Accession (PMID): 10029544 | | Abstract: The Na , K-ATPase is specifically inhibited by the cardiac glycoside , ouabain .
Via a largely undefined mechanism , the ouabain affinity of the Na , K-ATPase can be manipulated by mutating the residues at the borders of the first extracellular ( M1-M2 ) loop of the alpha subunit [ Price , E M , Rice , D A , and Lingrel , J B ( 1990 ) J Biol . Chem . 265 , 6638-6641 ] .
To address this issue , we compared the effects of two combinations of charged residues at the M1-M2 loop border , R113 , D124 and D113 , R124 ( numbered according to the rat alpha1 subunit ) , on the ouabain sensitivity of the alpha1 and alpha2 isoforms .
We report that ouabain sensitivity is dependent not only upon the identity of the residues at the M1-M2 loop border but also upon the context into which they are introduced .
Furthermore , at low concentrations of ATP , the identity of the residues at the M1-M2 loop border affects the regulation of ATP hydrolysis by potassium in an isoform-specific manner .
Analysis of chimeric alpha subunits reveals that the effects of potassium are determined primarily by the interaction of the N-terminus and M1-M2 loop with the C-terminal third of the alpha subunit .
M1-M2 loop border residues may , therefore , influence ouabain sensitivity indirectly by altering the stability or structure of the intermediate of the Na , K-ATPase catalytic cycle which is competent to bind ouabain .
| Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: Via a largely undefined mechanism , the ouabain affinity of the Na , K-ATPase can be manipulated by mutating the residues at the borders of the first extracellular ( M1-M2 ) loop of the alpha subunit [ Price , E M , Rice , D A , and Lingrel , J B ( 1990 ) J Biol . Chem . 265 , 6638-6641 ] .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: A rice homolog of Cdk7/MO15 phosphorylates both cyclin-dependent protein kinases and the carboxy-terminal domain of RNA polymerase II .
| | Author: Yamaguchi M Umeda M Uchimiya H | | Journal: Plant J Citation: V : 16 ( 5 ) P : 613-9 Year: 1998 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10036778 Accession (PMID): 10036778 | | Abstract: The activation of cyclin-dependent protein kinases ( CDKs ) requires phosphorylation of a threonine residue within the T-loop by a CDK-activating kinase ( CAK ) .
The R2 protein of rice is very similar to CAKs of animals and fission yeast at the amino acid level but phosphorylation by R2 has not yet been demonstrated .
When R2 was overexpressed in a CAK-deficient mutant of budding yeast , it suppressed the temperature sensitivity of the mutation .
Immunoprecipitates of rice proteins with the anti-R2 antibody phosphorylated human CDK2 , one of the rice CDKs ( Cdc2Os1 ) , and the carboxy-terminal domain ( CTD ) of the largest subunit of RNA polymerase II of Arabidopsis .
Mutational analysis indicated that R2 phosphorylated the threonine residue within the T-loop of CDK2 and Cdc2Os1 .
R2 was found mainly in two protein complexes which had molecular masses of 190 kDa and 70 kDa , respectively , whilst the CDK and CTD-kinase activities associated with R2 were identified in a complex of 105 kDa .
These results indicate that R2 is closely related to CAKs of animals and fission yeast in terms of its phosphorylation activity and , moreover , that this CAK of rice is distinct from a CAK of the dicotyledonous plant Arabidopsis . | Matching Sentences:
[ Sen. 4, subscore: 1.00 ]: Immunoprecipitates of rice proteins with the anti-R2 antibody phosphorylated human CDK2 , one of the rice CDKs ( Cdc2Os1 ) , and the carboxy-terminal domain ( CTD ) of the largest subunit of RNA polymerase II of Arabidopsis .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 2.00 |
|---|
| Title: Large-scale sequencing of plant genomes .
| | Author: Rounsley S Lin X Ketchum KA .
| | Journal: Curr . Opin . Plant Biol .
Citation: V : 1 ( 2 ) P : 136-41 Year: 1998 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10066574 Accession (PMID): 10066574 | | Abstract: The large number of ESTs generated for Arabidopsis and rice in recent years now act as an important complement to whole genome sequencing projects .
The Arabidopsis Genome Initiative has begun a coordinated effort to sequence the entire genome and , as a result , increasing numbers of large sequence entries can be found in the public databases .
In addition , the mitochondrial genome of Arabidopsis has been completely sequenced .
Genome sequencing studies and the public sequence databases have begun to influence the direction of diverse areas of research from physiology to evolution .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: The large number of ESTs generated for Arabidopsis and rice in recent years now act as an important complement to whole genome sequencing projects .
[ Sen. 2, subscore: 1.00 ]: The Arabidopsis Genome Initiative has begun a coordinated effort to sequence the entire genome and , as a result , increasing numbers of large sequence entries can be found in the public databases .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Nitrate-ammonium synergism in rice .
A subcellular flux analysis | | Author: Kronzucker HJ Siddiqi MY Glass AD Kirk GJ .
| | Journal: Citation: V : 119 ( 3 ) P : 1041-6 Year: 1999 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10069842 Accession (PMID): 10069842 | | Abstract: Many reports have shown that plant growth and yield is superior on mixtures of NO3 and NH4+ compared with provision of either N source alone .
Despite its clear practical importance , the nature of this N-source synergism at the cellular level is poorly understood .
In the present study we have used the technique of compartmental analysis by efflux and the radiotracer 13N to measure cellular turnover kinetics , patterns of flux partitioning , and cytosolic pool sizes of both NO3 and NH4+ in seedling roots of rice ( Oryza sativa L cv IR72 ) , supplied simultaneously with the two N sources .
We show that plasma membrane fluxes for NH4+ , cytosolic NH4+ accumulation , and NH4+ metabolism are enhanced by the presence of NO3- , whereas NO3 fluxes , accumulation , and metabolism are strongly repressed by NH4+ .
However , net N acquisition and N translocation to the shoot with dual N-source provision are substantially larger than when NO3 or NH4+ is provided alone at identical N concentrations . | Matching Sentences:
[ Sen. 5, subscore: 1.00 ]: However , net N acquisition and N translocation to the shoot with dual N-source provision are substantially larger than when NO3 or NH4+ is provided alone at identical N concentrations .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 2.00 |
|---|
| Title: A "defeated" rice resistance gene acts as a QTL against a virulent strain of Xanthomonas oryzae pv . oryzae .
| | Author: Li ZK Luo LJ Mei HW Paterson AH Zhao XH Zhong DB Wang YP Yu XQ Zhu L Tabien R Stansel JW Ying CS .
| | Journal: Mol . Gen . Genet . Citation: V : 261 ( 1 ) P : 58-63 Year: 1999 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10071210 Accession (PMID): 10071210 | | Abstract: The genetic components responsible for qualitative and quantitative resistance of rice plants to three strains ( CR4 , CXO8 , and CR6 ) of Xanthomonas oryzae pv . oryzae ( Xoo ) were investigated using a set of 315 recombinant inbred lines ( RILs ) from the cross Lemont ( japonica ) x Teqing ( indica ) and a complete linkage map with 182 well distributed RFLP markers .
We mapped a major gene ( Xa4 ) and ten quantitative trait loci ( QTLs ) which were largely responsible for segregation of the resistance phenotype in the RILs .
The Teqing allele at the Xa4 locus , Xa4T , acted as a dominant resistance gene against CR4 and CXO8 .
The breakdown of Xa4T-associated resistance mediated by the mutant allele at the avrXa4 locus in the virulent strain CR6 results from significant changes in both gene action ( lose of dominance ) and the magnitude of gene effect ( approximately 50% reduction ) .
Nevertheless , Xa4T still acted as a recessive QTL with a significant residual effect against CR6 .
The mutant alleles at the avrXa4 locus in CXO8 and CR6 that lead to a reduction in effect , or "breakdown" , of Xa4T were apparently accompanied by corresponding penalties for their fitness .
The quantitative component of resistance to Xoo in the RILs was largely due to a number of resistance QTLs .
Most resistance QTLs mapped to genomic locations where major resistance genes and/or QTLs for resistance to Xoo , blast and sheath blight were identified in the same cross .
Most QTLs showed consistent levels of resistance against all three Xoo strains .
Our results suggest that a high level of durable resistance to Xoo may be achieved by the cumulative effects of multiple QTLs , including the residual effects of "defeated" major resistance genes . | Matching Sentences:
[ Sen. 2, subscore: 1.00 ]: We mapped a major gene ( Xa4 ) and ten quantitative trait loci ( QTLs ) which were largely responsible for segregation of the resistance phenotype in the RILs .
[ Sen. 7, subscore: 1.00 ]: The quantitative component of resistance to Xoo in the RILs was largely due to a number of resistance QTLs .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 2.00 |
|---|
| Title: Digital mapping of bacterial artificial chromosomes by fluorescence in situ hybridization .
| | Author: Jackson SA Dong F Jiang J | | Journal: Plant J Citation: V : 17 ( 5 ) P : 581-7 Year: 1999 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10205912 Accession (PMID): 10205912 | | Abstract: The bacterial artificial chromosome ( BAC ) has become the most popular tool for cloning large DNA fragments .
The inserts of most BAC clones average 100-200 kilobases ( kb ) and molecular characterization of such large DNA fragments is a major challenge .
Here we report a simple and expedient technique for physical mapping of BAC inserts .
Individual BAC molecules were immobilized on glass slides coated with Poly-L-lysine .
The intact circular BAC molecules were visualized by fluorescence in situ hybridization using BAC DNA as a probe .
The 7 . 4 kb BAC vector was extended to approximately 2 . 44 kb per micrometer .
Digitally measured linear distances can be transformed into kilobases of DNA using the extension of BAC vector as a standard calibration .
We mapped DNA fragments as small as 2 kb directly on circular BAC molecules .
A rice BAC clone containing both tandem and dispersed repeats was analyzed using this technique .
The distribution and organization of the different repeats within the BAC insert were efficiently determined .
The results showed that this technique will be especially valuable for characterizing BAC clones that contain complex repetitive DNA sequences .
| Matching Sentences:
[ Sen. 1, subscore: 1.00 ]: The bacterial artificial chromosome ( BAC ) has become the most popular tool for cloning large DNA fragments .
[ Sen. 2, subscore: 1.00 ]: The inserts of most BAC clones average 100-200 kilobases ( kb ) and molecular characterization of such large DNA fragments is a major challenge .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Antimutagens in food plants eaten by Polynesians : micronutrients , phytochemicals and protection against bacterial mutagenicity of the heterocyclic amine 2-amino-3-methylimidazo [ 4 , 5-f ] quinoline .
| | Author: Botting KJ Young MM Pearson AE Harris PJ Ferguson LR .
| | Journal: Food Chem . Toxicol . Citation: V : 37 ( 2-3 ) P : 95-103 Year: Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10227732 Accession (PMID): 10227732 | | Abstract: We have previously suggested that differences in cancer incidence between Polynesians ( including Maoris and people from several Pacific islands ) and Europeans in New Zealand may at least partially relate to differences in the species of food plants ( fruits , vegetables and cereals ) preferentially eaten by these groups .
Twenty-five food plants that are typically eaten in different amounts by these two population groups were selected for detailed study .
Antimutagenic properties of three extracts from each of the selected plants were investigated using a preincubation mutagenicity assay with Salmonella typhimurium strain TA1538 against the mutagenicity of the heterocyclic amine 2-amino-3-methylimidazo [ 4 , 5-f ] quinoline ( IQ ) .
The data revealed strong antimutagenic properties in several of the food plants commonly eaten by Polynesians , especially rice , watercress , pawpaw , taro leaves , green banana and mango .
Using the New Zealand food database , a number of nutrients and micronutrients with antimutagenic and anticarcinogenic potential were identified from the selected food plants .
Some of these were tested for antimutagenic potential in parallel experiments to those done with the food plant extracts .
Although some of these micronutrients are antimutagens against IQ , their concentrations in the food plants failed to explain the protection against mutagenicity found in the experiments with extracts of the food plants .
Thus , other types of chemical , not identified in the database , must be leading to antimutagenesis .
Possible active molecules include chlorophylls , carotenoids , flavonoids and coumarins , many of which are also known to be anticarcinogens .
If human cancer data are to be interpreted in terms of cancer protection , these components need urgently to be quantified in food plants in the New Zealand diet , especially in those food plants eaten in large amounts by Polynesians .
| Matching Sentences:
[ Sen. 10, subscore: 1.00 ]: If human cancer data are to be interpreted in terms of cancer protection , these components need urgently to be quantified in food plants in the New Zealand diet , especially in those food plants eaten in large amounts by Polynesians .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: The effects of climatic patterns and agricultural practices on the population dynamics of Culex tritaeniorhynchus in Asia .
| | Author: Reisen WK Aslamkhan M Basio RG .
| | Journal: Southeast Asian J Trop . Med . Public Health Citation: V : -1 P : 61-71 Year: 1976 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub1027111 Accession (PMID): 1027111 | | Abstract: Annual population curves for C tritaeniorhynchus are presented for representative localities distributed from Pakistan , east through Southeast Asia and the Philippines and north to Japan and Korea .
In the dry temperature ( Pakistan ) and colder maritime climates ( Japan and Korea ) .
C tritaeniorhynchus populations apparently overwintered as hibernating adults , while in the warmer maritime climates ( Okinawa and Taiwan ) , gonotrophic activity and larval development continued throughout the winter months .
In these climatic types , the population curves closely paralleled the annual temperature curves .
In the tropical climates , however , temporal population patterns were closely related to available moisture either in the form of annual precipitation and/or rice irrigation .
The extremely variable environmental conditions tolerated C tritaeniorhynchus throughout its distribution attests to the physiological and ecological plasticity of this species and suggests that further ecological and genetic studies may reveal marked clinical variances among selected biological parameters .
| Matching Sentences:
[ Sen. 3, subscore: 1.00 ]: C tritaeniorhynchus populations apparently overwintered as hibernating adults , while in the warmer maritime climates ( Okinawa and Taiwan ) , gonotrophic activity and larval development continued throughout the winter months .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Agro-engineering and sanitation improvement in the control of schistosomiasis japonica in the Philippines : a review .
| | Author: Blas BL .
| | Journal: Southeast Asian J Trop . Med . Public Health Citation: V : 7 ( 2 ) P : 341-5 Year: 1976 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub1030838 Accession (PMID): 1030838 | | Abstract: Measures that would change the habitat of the snails were found to prevent its breeding .
Among these are clearing and drainage of waterlogged areas ; filling of depressions where filling materials are available ; ponding of areas which can not be drained , and improved rice culture .
The degree of success in snail control depends to a large extent on the amount of change brought about in the habitat .
The more radical the change , the greater the reduction in snail density .
It can be expected that improvement in sanitation in the form of toilet construction and use , provision of safe water supply , building of footbridges and the control of stray animals will bring a further decline in the transmission of the disease .
Studies have shown that perfect sanitation in the form of toilet construction and use will reduce transmission by about 75% , the other 25% being contributed by lower mammals .
Agro-engineering control measures are presently being carried out intensively in 7 town of Leyte , with food assistance from the UN/FAO World Food Program being given to volunteer workers as incentives for them to work .
Snail evaluation after 2 years has shown a snail reduction by 72% in the areas covered .
It may be mentioned here that sanitation improvement , especially latrine construction , is an ongoing program of the Department of Health in all rural areas .
| Matching Sentences:
[ Sen. 3, subscore: 1.00 ]: The degree of success in snail control depends to a large extent on the amount of change brought about in the habitat .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
Score: 1.00 |
|---|
| Title: Catalytic mechanism of scytalone dehydratase : site-directed mutagenisis , kinetic isotope effects , and alternate substrates .
| | Author: Basarab GS Steffens JJ Wawrzak Z Schwartz RS Lundqvist T Jordan DB .
| | Journal: Biochemistry Citation: V : 38 ( 19 ) P : 6012-24 Year: 1999 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10320327 Accession (PMID): 10320327 | | Abstract: On the basis of the X-ray crystal structure of scytalone dehydratase complexed with an active center inhibitor [ Lundqvist , T , Rice , J , Hodge , C N , Basarab , G S , Pierce , J and Lindqvist , Y ( 1994 ) Structure ( London ) 2 , 937-944 ] , eight active-site residues were mutated to examine their roles in the catalytic mechanism .
All but one residue ( Lys73 , a potential base in an anti elimination mechanism ) were found to be important to catalysis or substrate binding .
Steady-state kinetic parameters for the mutants support the native roles for the residues ( Asn131 , Asp31 , His85 , His110 , Ser129 , Tyr30 , and Tyr50 ) within a syn elimination mechanism .
Relative substrate specificities for the two physiological substrates , scytalone and veremelone , versus a Ser129 mutant help assign the orientation of the substrates within the active site .
His85Asn was the most damaging mutation to catalysis consistent with its native roles as a general base and a general acid in a syn elimination .
The additive effect of Tyr30Phe and Tyr50Phe mutations in the double mutant is consistent with their roles in protonating the substrates carbonyl through a water molecule .
Studies on a synthetic substrate , which has an anomeric carbon atom which can better stabilize a carbocation than the physiological substrate ( vermelone ) , suggest that His110Asn prefers this substrate over vermelone in order to balance the mutation-imposed weakness in promoting the elimination of hydroxide from substrates .
All mutant enzymes bound a potent active-site inhibitor in near 1 : 1 stoichiometry , thereby supporting their active-site integrity .
An X-ray crystal structure of the Tyr50Phe mutant indicated that both active-site waters were retained , likely accounting for its residual catalytic activity .
Steady-state kinetic parameters with deuterated scytalone gave kinetic isotope effects of 2 . 7 on kcat and 4 . 2 on kcat/Km , suggesting that steps after dehydration partially limit kcat .
Pre-steady-state measurements of a single-enzyme turnover with scytalone gave a rate that was 6-fold larger than kcat . kcat/Km with scytalone has a pKa of 7 . 9 similar to the pKa value for the ionization of the substrates C6 phenolic hydroxyl , whereas kcat was unaffected by pH , indicating that the anionic form of scytalone does not bind well to enzyme .
With an alternate substrate having a pKa above 11 , kcat/Km had a pKa of 9 . 3 likely due to the ionization of Tyr50 .
The non-enzyme-catalyzed rate of dehydration of scytalone was nearly a billion-fold slower than the enzyme-catalyzed rate at pH 7 . 0 and 25 degrees C The non-enzyme-catalyzed rate of dehydration of scytalone had a deuterium kinetic isotope effect of 1 . 2 at pH 7 . 0 and 25 degrees C , and scytalone incorporated deuterium from D2O in the C2 position about 70-fold more rapidly than the dehydration rate .
Thus , scytalone dehydrates through an E1cb mechanism off the enzyme .
| Matching Sentences:
[ Sen. 11, subscore: 1.00 ]: Pre-steady-state measurements of a single-enzyme turnover with scytalone gave a rate that was 6-fold larger than kcat . kcat/Km with scytalone has a pKa of 7 . 9 similar to the pKa value for the ionization of the substrates C6 phenolic hydroxyl , whereas kcat was unaffected by pH , indicating that the anionic form of scytalone does not bind well to enzyme .
| | Supplemental links/files: reference in endnote online text related articles pubmed citation | |
