| 37 matches found in 18 documents. Search time: 0.413 seconds. |
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Score: 13.00 |
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| Title: Identification of a new locus , Ptr ( t ) , required for rice blast resistance gene Pi-ta-mediated resistance .
| | Author: Jia Y Martin R | | Journal: Mol Plant Microbe Interact Citation: V : 21 P : 396-403 Year: 2008 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub18321185 Accession (PMID): 18321185 | | Abstract: Resistance to the blast pathogen Magnaporthe oryzae is proposed to be initiated by physical binding of a putative cytoplasmic receptor encoded by a nucleotide binding site-type resistance gene , Pi-ta , to the processed elicitor encoded by the corresponding avirulence gene AVR-Pita .
Here , we report the identification of a new locus , Ptr ( t ) , that is required for Pi-ta-mediated signal recognition .
A Pi-ta-expressing susceptible mutant was identified using a genetic screen .
Putative mutations at Ptr ( t ) do not alter recognition specificity to another resistance gene , Pi-k ( s ) , in the Pi-ta homozygote , indicating that Ptr ( t ) is more likely specific to Pi-ta-mediated signal recognition .
Genetic crosses of Pi-ta Ptr ( t ) and Pi-ta ptr ( t ) homozygotes suggest that Ptr ( t ) segregates as a single dominant nuclear gene .
A ratio of 1 : 1 ( resistant/susceptible ) of a population of BC1 of Pi-ta Ptr ( t ) with pi-ta ptr ( t ) homozygotes indicates that Pi-ta and Ptr ( t ) are linked and cosegregate .
Genotyping of mutants of pi-ta ptr ( t ) and Pi-ta Ptr ( t ) homozygotes using ten simple sequence repeat markers at the Pi-ta region determined that Pi-ta and Ptr ( t ) are located within a 9-megabase region and are of indica origin .
Identification of Ptr ( t ) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction .
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[ Sen. 5, subscore: 3.00 ]: Genetic crosses of Pi-ta Ptr ( t ) and Pi-ta ptr ( t ) homozygotes suggest that Ptr ( t ) segregates as a single dominant nuclear gene .
[ Sen. 6, subscore: 3.00 ]: A ratio of 1 : 1 ( resistant/susceptible ) of a population of BC1 of Pi-ta Ptr ( t ) with pi-ta ptr ( t ) homozygotes indicates that Pi-ta and Ptr ( t ) are linked and cosegregate .
[ Sen. 7, subscore: 3.00 ]: Genotyping of mutants of pi-ta ptr ( t ) and Pi-ta Ptr ( t ) homozygotes using ten simple sequence repeat markers at the Pi-ta region determined that Pi-ta and Ptr ( t ) are located within a 9-megabase region and are of indica origin .
[ Sen. 4, subscore: 2.00 ]: Putative mutations at Ptr ( t ) do not alter recognition specificity to another resistance gene , Pi-k ( s ) , in the Pi-ta homozygote , indicating that Ptr ( t ) is more likely specific to Pi-ta-mediated signal recognition .
[ Sen. 2, subscore: 1.00 ]: Here , we report the identification of a new locus , Ptr ( t ) , that is required for Pi-ta-mediated signal recognition .
[ Sen. 8, subscore: 1.00 ]: Identification of Ptr ( t ) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction .
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Score: 10.00 |
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| Title: Differential expression patterns of two new primary cell wall-related cellulose synthase cDNAs , PtrCesA6 and PtrCesA7 from aspen trees .
| | Author: Samuga A Joshi CP .
| | Journal: Gene Citation: V : 334 ( ) P : 73-82 Year: 2004 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub15256257 Accession (PMID): 15256257 | | Abstract: Based on elegant molecular genetic analyses , distinct classes of cellulose synthase ( CesA ) genes have been associated with either primary or secondary cell wall development in Arabidopsis .
Here , we report on cloning of two new CesA cDNAs , PtrCesA6 and PtrCesA7 involved in the primary cell wall development in aspen ( Populus tremuloides ) trees .
Both these distinct cDNAs , isolated from a developing xylem cDNA library , share only 60-67% identities with each other as well as with five other previously known aspen CesA cDNAs .
Interestingly , PtrCESA6 from aspen , a dicot species , shares maximum identity of 81-84% with three CESA isoforms from maize and rice , two monocot species .
On the other hand , PtrCESA7 shares a maximum identity of 86% with AtCESA2 , a primary wall-related CesA member from Arabidopsis , a dicot species .
Gene expression analyses by reverse transcriptase-polymerase chain reactions ( RT-PCRs ) suggested that both these genes are expressed at a low level in all aspen it issues examined but PtrCesA7 is expressed at a higher level than PtrCesA6 .
While corroborating these results , in situ mRNA hybridization studies using three different aspen organs also suggested that PtrCesA6 and PtrCesA7 genes are expressed in all expanding cells depositing primary cell wall but PtrCesA7 is expressed at a higher level than PtrCesA6 .
These differential gene expression profiles suggest that each of these CesAs may be playing a specific role during primary cell wall development in aspen trees .
Isolation of two primary wall related CesA genes from xylem it issues also suggest their importance during xylem development , which is traditionally considered to be enriched in secondary cell wall forming cells of economical significance .
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[ Sen. 7, subscore: 4.00 ]: While corroborating these results , in situ mRNA hybridization studies using three different aspen organs also suggested that PtrCesA6 and PtrCesA7 genes are expressed in all expanding cells depositing primary cell wall but PtrCesA7 is expressed at a higher level than PtrCesA6 .
[ Sen. 2, subscore: 2.00 ]: Here , we report on cloning of two new CesA cDNAs , PtrCesA6 and PtrCesA7 involved in the primary cell wall development in aspen ( Populus tremuloides ) trees .
[ Sen. 6, subscore: 2.00 ]: Gene expression analyses by reverse transcriptase-polymerase chain reactions ( RT-PCRs ) suggested that both these genes are expressed at a low level in all aspen it issues examined but PtrCesA7 is expressed at a higher level than PtrCesA6 .
[ Sen. 4, subscore: 1.00 ]: Interestingly , PtrCESA6 from aspen , a dicot species , shares maximum identity of 81-84% with three CESA isoforms from maize and rice , two monocot species .
[ Sen. 5, subscore: 1.00 ]: On the other hand , PtrCESA7 shares a maximum identity of 86% with AtCESA2 , a primary wall-related CesA member from Arabidopsis , a dicot species .
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Score: 5.00 |
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| Title: A cross-sectional investigation of regional patterns of diet and cardio-metabolic risk in India .
| | Author: Daniel CR Prabhakaran D Kapur K Graubard BI Devasenapathy N Ramakrishnan L George PS Shetty H Ferrucci LM Yurgalevitch S Chatterjee N Reddy KS Rastogi T Gupta PC Mathew A Sinha R | | Journal: Nutr J Citation: V : 10 P : 12 Year: 2011 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub21276235 Accession (PMID): 21276235 | | Abstract: BACKGROUND : The role of diet in Indias rapidly progressing chronic disease epidemic is unclear ; moreover , diet may vary considerably across North-South regions .
METHODS : The India Health Study was a multicenter study of men and women aged 35-69 , who provided diet , lifestyle , and medical histories , as well as blood pressure , fasting blood , urine , and anthropometric measurements .
In each region ( Delhi , n=824 ; Mumbai , n=743 ; Trivandrum , n=2 , 247 ) , we identified two dietary patterns with factor analysis .
In multiple logistic regression models adjusted for age , gender , education , income , marital status , religion , physical activity , tobacco , alcohol , and total energy intake , we investigated associations between regional dietary patterns and abdominal adiposity , hypertension , diabetes , and dyslipidemia .
RESULTS : Across the regions , more than 80% of the participants met the criteria for abdominal adiposity and 10 to 28% of participants were considered diabetic .
In Delhi , the "fruit and dairy" dietary pattern was positively associated with abdominal adiposity [ highest versus lowest tertile , multivariate-adjusted OR and 95% CI : 2 . 32 ( 1 . 03-5 . 23 ) ; Ptrend=0 . 008 ] and hypertension [ 2 . 20 ( 1 . 47-3 . 31 ) ; Ptrend<0 . 0001 ] .
In Trivandrum , the "pulses and rice" pattern was inversely related to diabetes [ 0 . 70 ( 0 . 51-0 . 95 ) ; Ptrend=0 . 03 ] and the "snacks and sweets" pattern was positively associated with abdominal adiposity [ 2 . 05 ( 1 . 34-3 . 14 ) ; Ptrend=0 . 03 ] .
In Mumbai , the "fruit and vegetable" pattern was inversely associated with hypertension [ 0 . 63 ( 0 . 40-0 . 99 ) ; Ptrend=0 . 05 ] and the "snack and meat" pattern appeared to be positively associated with abdominal adiposity .
CONCLUSIONS : Cardio-metabolic risk factors were highly prevalent in this population .
Across all regions , we found little evidence of a Westernized diet ; however , dietary patterns characterized by animal products , fried snacks , or sweets appeared to be positively associated with abdominal adiposity .
Conversely , more traditional diets in the Southern regions were inversely related to diabetes and hypertension .
Continued investigation of diet , as well as other environmental and biological factors , will be needed to better understand the risk profile in this population and potential means of prevention .
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[ Sen. 6, subscore: 2.00 ]: In Delhi , the "fruit and dairy" dietary pattern was positively associated with abdominal adiposity [ highest versus lowest tertile , multivariate-adjusted OR and 95% CI : 2 . 32 ( 1 . 03-5 . 23 ) ; Ptrend=0 . 008 ] and hypertension [ 2 . 20 ( 1 . 47-3 . 31 ) ; Ptrend<0 . 0001 ] .
[ Sen. 7, subscore: 2.00 ]: In Trivandrum , the "pulses and rice" pattern was inversely related to diabetes [ 0 . 70 ( 0 . 51-0 . 95 ) ; Ptrend=0 . 03 ] and the "snacks and sweets" pattern was positively associated with abdominal adiposity [ 2 . 05 ( 1 . 34-3 . 14 ) ; Ptrend=0 . 03 ] .
[ Sen. 8, subscore: 1.00 ]: In Mumbai , the "fruit and vegetable" pattern was inversely associated with hypertension [ 0 . 63 ( 0 . 40-0 . 99 ) ; Ptrend=0 . 05 ] and the "snack and meat" pattern appeared to be positively associated with abdominal adiposity .
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Score: 3.00 |
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| Title: Differential distribution of proteins expressed in companion cells in the sieve element-companion cell complex of rice plants .
| | Author: Fukuda A Fujimaki S Mori T Suzui N Ishiyama K Hayakawa T Yamaya T Fujiwara T Yoneyama T Hayashi H | | Journal: Plant Cell Physiol .
Citation: V : 46 ( 11 ) P : 1779-86 Year: 2005 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub16120685 Accession (PMID): 16120685 | | Abstract: Sieve tubes are comprised of sieve elements , enucleated cells that are incapable of RNA and protein synthesis .
The proteins in sieve elements are supplied from the neighboring companion cells through plasmodesmata .
In rice plants , it was unclear whether or not all proteins produced in companion cells had the same distribution pattern in the sieve element-companion cell complex In this study , the distribution pattern of four proteins , beta-glucuronidase ( GUS ) , green fluorescent protein ( GFP ) , thioredoxin h ( TRXh ) and glutathione S-transferase ( GST ) were analyzed .
The foreign proteins GUS and GFP were expressed in transgenic rice plants under the control of the TRXh gene promoter ( PTRXh ) , a companion cell-specific promoter .
Analysis of leaf cross-sections of PTRXh-GUS and PTRXh-GFP plants indicated high accumulation of GUS and GFP , respectively , in companion cells rather than in sieve elements .
GUS and GFP were also detected in phloem sap collected from leaf sheaths of the transgenic rice plants , suggesting these proteins could enter sieve elements .
Relative amounts of GFP and endogenous phloem proteins , TRXh and GST , in phloem sap and total leaf extracts were compared .
Compared to TRXh and GST , GFP content was higher in total leaf extracts , but lower in phloem sap , suggesting that GFP accumulated mainly in companion cells rather than in sieve elements .
On the other hand , TRXh and GST appeared to accumulate in sieve elements rather than in companion cells .
These results indicate the evidence for differential distribution of proteins between sieve elements and companion cells in rice plants . | Matching Sentences:
[ Sen. 5, subscore: 2.00 ]: Analysis of leaf cross-sections of PTRXh-GUS and PTRXh-GFP plants indicated high accumulation of GUS and GFP , respectively , in companion cells rather than in sieve elements .
[ Sen. 4, subscore: 1.00 ]: The foreign proteins GUS and GFP were expressed in transgenic rice plants under the control of the TRXh gene promoter ( PTRXh ) , a companion cell-specific promoter .
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Score: 3.00 |
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| Title: Homologs of ToxB , a host-selective toxin gene from Pyrenophora tritici-repentis , are present in the genome of sister-species Pyrenophora bromi and other members of the Ascomycota .
| | Author: Andrie RM Schoch CL Hedges R Spatafora JW Ciuffetti LM | | Journal: Fungal Genet Biol Citation: V : 45 P : 363-77 Year: 2008 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub18226934 Accession (PMID): 18226934 | | Abstract: Pyrenophora tritici-repentis requires the production of host-selective toxins ( HSTs ) to cause the disease tan spot of wheat , including Ptr ToxA , Ptr ToxB , and Ptr ToxC .
Pyrenophora bromi , the species most closely related to P tritici-repentis , is the causal agent of brown leaf spot of bromegrass .
Because of the relatedness of P bromi and P tritici-repentis , we investigated the possibility that P bromi contains sequences homologous to ToxA and/or ToxB , the products of which may be involved in its interaction with bromegrass .
Multiplex polymerase chain reaction ( PCR ) revealed the presence of ToxB-like sequences in P bromi and high-fidelity PCR was used to clone several of these loci , which were subsequently confirmed to be homologous to ToxB .
Additionally , Southern analysis revealed ToxB from P bromi to have a multicopy nature similar to ToxB from P tritici-repentis .
A combination of phylogenetic and Southern analyses revealed that the distribution of ToxB extends further into the Pleosporaceae , and a search of available fungal genomes identified a distant putative homolog in Magnaporthe grisea , causal agent of rice blast Thus , unlike most described HSTs , ToxB homologs are present across a broad range of plant pathogenic ascomycetes , suggesting that it may have arose in an early ancestor of the Ascomycota .
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[ Sen. 1, subscore: 3.00 ]: Pyrenophora tritici-repentis requires the production of host-selective toxins ( HSTs ) to cause the disease tan spot of wheat , including Ptr ToxA , Ptr ToxB , and Ptr ToxC .
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Score: 3.00 |
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| Title: Short panicle1 encodes a putative PTR family transporter and determines rice panicle size .
| | Author: Li S Qian Q Fu Z Zeng D Meng X Kyozuka J Maekawa M Zhu X Zhang J Li J Wang Y | | Journal: Plant J Citation: V : P : Year: 2009 Type: Publisher | | Literature: oryza Field: abstract Doc ID: pub19154200 Accession (PMID): 19154200 | | Abstract: Summary The architecture of the rice inflorescence , which is determined mainly by the number and length of primary and secondary inflorescence branches , is of importance in both agronomy and developmental biology .
The position and number of primary branches are established during the phase transition from vegetative to reproductive growth , and several of the genes identified as participating in this process do so by regulating the meristemic activities of inflorescence .
However , little is known about the molecular mechanism that controls inflorescence branch elongation .
Here , we report on a novel rice mutant , short panicle1 ( sp1 ) , which is defective in rice panicle elongation , and thus leads to the short-panicle phenotype .
Gene cloning and characterization indicate that SP1 encodes a putative transporter that belongs to the peptide transporter ( PTR ) family .
This conclusion is based on the findings that SP1 contains a conserved PTR2 domain consisting of 12 transmembrane domains , and that the SP1-GFP fusion protein is localized in the plasma membrane .
The SP1 gene is highly expressed in the phloem of the branches of young panicles , which is consistent with the predicted function of SP1 and the sp1 phenotype .
Phylogenetic analysis implies that SP1 might be a nitrate transporter .
However , neither nitrate transporter activity nor any other compounds transported by known PTR proteins could be detected in either a Xenopus oocyte or yeast system , in our study , suggesting that SP1 may need other component ( s ) to be able to function as a transporter , or that it transports unknown substrates in the monocotyledonous rice plant .
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[ Sen. 5, subscore: 1.00 ]: Gene cloning and characterization indicate that SP1 encodes a putative transporter that belongs to the peptide transporter ( PTR ) family .
[ Sen. 6, subscore: 1.00 ]: This conclusion is based on the findings that SP1 contains a conserved PTR2 domain consisting of 12 transmembrane domains , and that the SP1-GFP fusion protein is localized in the plasma membrane .
[ Sen. 9, subscore: 1.00 ]: However , neither nitrate transporter activity nor any other compounds transported by known PTR proteins could be detected in either a Xenopus oocyte or yeast system , in our study , suggesting that SP1 may need other component ( s ) to be able to function as a transporter , or that it transports unknown substrates in the monocotyledonous rice plant .
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Score: 3.00 |
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| Title: Genomic survey , characterization and expression profile analysis of the peptide transporter family in rice ( Oryza sativa L ) .
| | Author: Zhao X Huang J Yu H Wang L Xie W | | Journal: BMC Plant Biol Citation: V : 10 P : 92 Year: 2010 Type: MEDLINE | | Literature: oryza Field: abstract Doc ID: pub20487558 Accession (PMID): 20487558 | | Abstract: BACKGROUND : Peptide transporter ( PTR ) family whose member can transport di-/tripeptides and nitrate is important for plant growth and development .
Although the rice ( Oryza sativa L ) genome has been sequenced for a few years , a genomic survey , characterization and expression profile analysis of the PTR family in this species has not been reported .
RESULTS : In this study , we report a comprehensive identification , characterization , phylogenetic and evolutionary analysis of 84 PTR family members in rice ( OsPTR ) as well as their whole-life expression patterns .
Chromosomal distribution and sequence analysis indicate that nearly 70% of OsPTR members are involved in the tandem and segmental duplication events .
It suggests that genome duplication might be a major mechanism for expansion of this family .
Highly conserved motifs were identified in most of the OsPTR members .
Meanwhile , expression profile of OsPTR genes has been analyzed by using Affymetrix rice microarray and real-time PCR in two elite hybrid rice parents , Minghui 63 and Zhenshan 97 .
Seven genes are found to exhibit either preferential or it issue-specific expression during different development stages of rice .
Under phytohormone ( NAA , GA3 and KT ) and light/dark treatments , 14 and 17 OsPTR genes are differentially expressed respectively .
Ka/Ks analysis of the paralogous OsPTR genes indicates that purifying selection plays an important role in function maintenance of this family .
CONCLUSION : These investigations add to our understanding of the importance of OsPTR family members and provide useful reference for selecting candidate genes for functional validation studies of this family in rice .
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[ Sen. 1, subscore: 1.00 ]: BACKGROUND : Peptide transporter ( PTR ) family whose member can transport di-/tripeptides and nitrate is important for plant growth and development .
[ Sen. 2, subscore: 1.00 ]: Although the rice ( Oryza sativa L ) genome has been sequenced for a few years , a genomic survey , characterization and expression profile analysis of the PTR family in this species has not been reported .
[ Sen. 3, subscore: 1.00 ]: RESULTS : In this study , we report a comprehensive identification , characterization , phylogenetic and evolutionary analysis of 84 PTR family members in rice ( OsPTR ) as well as their whole-life expression patterns .
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Score: 2.00 |
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| Title: Cloning and functional characterization of a constitutively expressed nitrate transporter gene , OsNRT1 , from rice .
| | Author: Lin CM Koh S Stacey G Yu SM Lin TY Tsay YF .
| | Journal: Plant Physiol .
Citation: V : 122 ( 2 ) P : 379-88 Year: 2000 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub10677431 Accession (PMID): 10677431 | | Abstract: Elucidating how rice ( Oryza sativa ) takes up nitrate at the molecular level could help improve the low recovery rate ( <50% ) of nitrogen fertilizer in rice paddies .
As a first step toward that goal , we have cloned a nitrate transporter gene from rice called OsNRT1 .
OsNRT1 is a new member of a growing transporter family called PTR , which consists not only of nitrate transporters from higher plants that are homologs of the Arabidopsis CHL1 ( AtNRT1 ) protein , but also peptide transporters from a wide variety of genera including animals , plants , fungi , and bacteria .
However , despite the fact that OsNRT1 shares a higher degree of sequence identity with the two peptide transporters from plants ( approximately 50% ) than with the nitrate transporters ( approximately 40% ) of the PTR family , no peptide transport activity was observed when OsNRT1 was expressed in either Xenopus oocytes or yeast Furthermore , contrasting the dual-affinity nitrate transport activity of CHL1 , OsNRT1 displayed only low-affinity nitrate transport activity in Xenopus oocytes , with a K ( m ) value of approximately 9 mM .
Northern-blot and in situ hybridization analysis indicated that OsNRT1 is constitutively expressed in the most external layer of the root , epidermis and root hair .
These data strongly indicate that OsNRT1 encodes a constitutive component of a low-affinity nitrate uptake system for rice . | Matching Sentences:
[ Sen. 3, subscore: 1.00 ]: OsNRT1 is a new member of a growing transporter family called PTR , which consists not only of nitrate transporters from higher plants that are homologs of the Arabidopsis CHL1 ( AtNRT1 ) protein , but also peptide transporters from a wide variety of genera including animals , plants , fungi , and bacteria .
[ Sen. 4, subscore: 1.00 ]: However , despite the fact that OsNRT1 shares a higher degree of sequence identity with the two peptide transporters from plants ( approximately 50% ) than with the nitrate transporters ( approximately 40% ) of the PTR family , no peptide transport activity was observed when OsNRT1 was expressed in either Xenopus oocytes or yeast Furthermore , contrasting the dual-affinity nitrate transport activity of CHL1 , OsNRT1 displayed only low-affinity nitrate transport activity in Xenopus oocytes , with a K ( m ) value of approximately 9 mM .
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Score: 2.00 |
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| Title: Cloning and expression of a distinct subclass of plant thioredoxins .
| | Author: Juttner J Olde D Langridge P Baumann U | | Journal: Eur .
J Biochem .
Citation: V : 267 ( 24 ) P : 7109-17 Year: 2000 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub11106422 Accession (PMID): 11106422 | | Abstract: mRNAs encoding a novel thioredoxin were isolated from pollen RNA of Lolium perenne ( LpTrx ) , Hordeum bulbosum ( HbTrx ) , Phalaris coerulescens ( PTrx ) and Secale cereale ( ScTrx ) .
The cDNAs contain a single ORF of 393 bp encoding a protein of 131 amino acids .
The predicted proteins showed highest homology to plant thioredoxins of the h class yet form a distinct subgroup that is characterized by a high level of sequence conservation ( 95 . 4-97 . 7% identity ) .
GenBank searches revealed additional members of this subclass in tomato , soybean , rice and pine .
LpTrx and PTrx were expressed as recombinant proteins in Escherichia coli and tested for thioredoxin activity .
Both proteins displayed typical thioredoxin activity in the nonspecific insulin reduction assay , however , were not reduced by E coli NADPH-dependant thioredoxin reductase .
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[ Sen. 1, subscore: 1.00 ]: mRNAs encoding a novel thioredoxin were isolated from pollen RNA of Lolium perenne ( LpTrx ) , Hordeum bulbosum ( HbTrx ) , Phalaris coerulescens ( PTrx ) and Secale cereale ( ScTrx ) .
[ Sen. 5, subscore: 1.00 ]: LpTrx and PTrx were expressed as recombinant proteins in Escherichia coli and tested for thioredoxin activity .
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Score: 2.00 |
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| Title: Deduced consensus sequence of Sindbis virus strain AR339 : mutations contained in laboratory strains which affect cell culture and in vivo phenotypes .
| | Author: McKnight KL Simpson DA Lin SC Knott TA Polo JM Pence DF Johannsen DB Heidner HW Davis NL Johnston RE .
| | Journal: J Virol .
Citation: V : 70 ( 3 ) P : 1981-9 Year: 1996 Type: ARTICLE | | Literature: oryza Field: abstract Doc ID: pub8627724 Accession (PMID): 8627724 | | Abstract: The consensus sequence of the Sindbis virus AR339 isolate , the prototype alphavirus , has been deduced .
THe results presented here suggest ( i ) that a substantial proportion of the sequence divergence evident between the consensus sequence and sequences of laboratory strains of AR339 has resulted from selection for efficient growth in cell culture , ( ii ) that many of these changes affect the virulence of the virus in animal models , and ( iii ) that such modified genetic backgrounds present in laboratory strains can exert a significant influence on genetic studies of virus pathogenesis and host range .
A laboratory strain of Sindbis virus AR339 was sequenced and cloned as a cDNA ( pTRSB ) from which infectious virus ( TRSB ) could be derived .
The consensus sequence was deduced from the complete sequences of pTRSB and HRsp ( E G Strauss , C M Rice , and J H Strauss , Virology 133 : 92-110 , 1984 ) , from partial sequences of the glycoprotein genes of three other AR339 laboratory strains , and by comparison with the sequences of the glycoprotein genes of three other AR339 sequence .
HRsp differed form the consensus sequence by eight coding changes , and TRSB differed by three coding changes .
In the 5 untranslated region , HRsp differed from the consensus sequence at nucleotide ( nt ) 5 .
These differences were likely the result of cell culture passage of the original AR339 isolate .
At three of the difference loci ( one in TRSB and two in HRsp ) , selection of cell-culture-adaptive mutations was documented with Sindbis virus or other alphaviruses .
Selection in cell culture often results in attenuation of virulence in animals .
Considering the TRSB and HRsp sequences together , one noncoding difference from the consensus ( an A-for-G substitution in the 5 untranslated region at nt 5 ) and six coding differences in the glycoprotein genes ( at E2 amino acids 1 , 3 , 70 , and 172 and at E1 amino acids 72 and 237 ) were at loci which , either individually or in combination , significantly affected alphavirus virulence in mice .
Although the levels of virulence of isogenic strains containing either nt 5 A or nt 5 G did not differ significantly in neonatal mice , the presence of nt 5 A greatly enhanced the effect of a second attenuating mutation in the E2 gene .
These results suggest that minimal differences in the "wild type" genetic background into which an additional mutation is introduced can have a dramatic effect on apparent virulence and pathogenesis phenotypes .
A cDNA clone of the consensus AR339 sequence , a sequence devoid of occult attenuating mutations introduced by cell culture passage , will allow the molecular genetic examination of cell culture and in vivo phenotypes of a virus which may best reflect the sequence of Sindbis virus AR339 at the time of its isolation .
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[ Sen. 3, subscore: 1.00 ]: A laboratory strain of Sindbis virus AR339 was sequenced and cloned as a cDNA ( pTRSB ) from which infectious virus ( TRSB ) could be derived .
[ Sen. 4, subscore: 1.00 ]: The consensus sequence was deduced from the complete sequences of pTRSB and HRsp ( E G Strauss , C M Rice , and J H Strauss , Virology 133 : 92-110 , 1984 ) , from partial sequences of the glycoprotein genes of three other AR339 laboratory strains , and by comparison with the sequences of the glycoprotein genes of three other AR339 sequence .
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