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Jyoti Shah

Publications and source records attributed to Jyoti Shah.

26 records · Page 2Linked to original sources
PubMed2003

Ethylene and jasmonic acid signaling affect the NPR1-independent expression of defense genes without impacting resistance to Pseudomonas syringae and Peronospora parasitica in the Arabidopsis ssi1 mutant.

Salicylic acid (SA), ethylene, and jasmonic acid (JA) are important signaling molecules in plant defense to biotic stress. An intricate signaling network involving SA, ethylene, and JA fine tunes plant defense responses. SA-dependent defense responses in Arabidopsis thaliana are mediated through NPR1-dependent and -independent mechanisms. We have previously shown that activation of an NPR1-independent defense mechanism confers enhanced disease resistance and constitutive expression of the pathogenesis-related (PR) genes in the Arabidopsis ssi1 mutant. In addition, the ssi1 mutant constitutively expresses the defensin gene PDF1.2. Moreover, SA is required for the ssi1-conferred constitutive expression of PDF1.2 in addition to PR genes. Hence, the ssi1 mutant appears to target a step common to SA- and ethylene- or JA-regulated defense pathways. In the present study, we show that, in addition to SA, ethylene and JA signaling also are required for the ssi1-conferred constitutive expression of PDF1.2 and the NPR1-independent expression of PR-1. Furthermore, the ethylene-insensitive ein2 and JA-insensitive jar1 mutants enhance susceptibility of ssi1 plants to the necrotrophic fungus Botrytis cinerea. However, defects in either the ethylene- or JA-signaling pathways do not compromise ssi1-conferred resistance to the bacterial pathogen Pseudomonas synringae pv. maculicola and the oomycete pathogen Peronospora parasitica. Interestingly, ssi1 exhibits a marginal increase in the levels of ethylene and JA, suggesting that low endogenous levels of these phytohormones are sufficient to activate expression of defense genes. Taken together, our results indicate that although cross talk in ssi1 renders expression of ethylene- or JA-responsive defense genes sensitive to SA and vice versa, it does not affect downstream signaling leading to resistance.

Arabidopsis↗
PubMed2003

Multiple Objective Measures of Skill (MOMS): a new approach to the assessment of technical ability in surgical trainees.

OBJECTIVE: The assessment of surgical technical skills has become an important topic in recent years. This study presents the validation of a 6-task skills examination for junior surgical trainees (at the level of the Membership of the Royal College of Surgeons). SUMMARY BACKGROUND DATA: Six tasks were evaluated in a project that also examined the feasibility of this method of assessment. The tasks were knowledge of sutures and instruments; knowledge of surgical devices; knot formation; skin-pad suturing, closure of an enterotomy; excision of a skin lesion; and laparoscopic manipulation. Comparisons were made between a group of junior trainees (n = 13), and a group of seniors (n = 8). RESULTS: Each of the 6 tasks was able to be used to discriminate between the 2 groups. In all, there were 19 primary analyses across the 6 tasks, and 17 of these showed significant differences between the groups (P values ranging from 0.037 to < 0.001). There was generally a strong correlation between the analyses, and when a mean rank was calculated, the difference between groups was significant (P = 0.005 on Mann-Whitney U test; mean ranks 13.9 and 6.3 [of 21], for juniors and seniors respectively). Reliability of the 6-task assessment was very good at 0.70 (Cronbach's Alpha). CONCLUSIONS: A skills examination is a feasible and effective method of assessing the technical ability of basic surgical trainees.

Computer Graphics↗
PubMed2002

RCY1, an Arabidopsis thaliana RPP8/HRT family resistance gene, conferring resistance to cucumber mosaic virus requires salicylic acid, ethylene and a novel signal transduction mechanism.

The dominant locus, RCY1, in the Arabidopsis thaliana ecotype C24 confers resistance to the yellow strain of cucumber mosaic virus (CMV-Y). The RCY1 locus was mapped to a 150-kb region on chromosome 5. Sequence comparison of this region from C24 and a CMV-Y-susceptible C24 mutant predicts that the RCY1 gene encodes a 104-kDa CC-NBS-LRR-type protein. The RCY1 gene from C24, when expressed in the susceptible ecotype Wassilewskija (Ws), restricted the systemic spread of virus. RCY1 is allelic to the resistance genes RPP8 from the ecotype Landsberg erecta and HRT from the ecotype Dijon-17, which confer resistance to Peronospora parasitica biotype Emco5 and turnip crinkle virus (TCV), respectively. Examination of RCY1 plants defective in salicylic acid (SA), jasmonic acid (JA) and ethylene signaling revealed a requirement for SA and ethylene signaling in mounting a resistance response to CMV-Y. The RCY1 nahG etr1 double mutants exhibited an intermediate level of susceptibility to CMV-Y, compared to the resistant ecotype C24 and the susceptible ecotypes Columbia and Nossen. This suggests that in addition to SA and ethylene, a novel signaling mechanism is associated with the induction of resistance in CMV-Y-infected C24 plants. Moreover, our results suggest that the signaling pathways downstream of the RPP8, HRT, and RCY1 have evolved independently.

Amino Acid Sequence↗
PubMed2002

Robot-assisted laparoscopic Heller's cardiomyotomy.

There are many options available for the management of achalasia. Recently, the list of options has expanded to include robotic-assisted Heller's cardiomyotomy. In this article, we describe the procedure for a robotic-assisted cardiomyotomy and discuss the advantages of using a robotic, master-slave system.

Adult↗
PubMed2002

A gain-of-function mutation in an Arabidopsis Toll Interleukin1 receptor-nucleotide binding site-leucine-rich repeat type R gene triggers defense responses and results in enhanced disease resistance.

In a screen for suppressors of npr1-5-based salicylic acid (SA) insensitivity, we isolated a semidominant gain-of-function mutation, designated ssi4, that confers constitutive expression of several PR (pathogenesis-related) genes, induces SA accumulation, triggers programmed cell death, and enhances resistance to bacterial and oomycete pathogens. Through map-based cloning, ssi4 was identified and found to encode a putative protein belonging to the TIR-NBS-LRR (Toll Interleukin1 Receptor-Nucleotide Binding Site-Leu-Rich Repeat) class of R (resistance) proteins. Comparison between ssi4 and the corresponding wild-type sequence revealed a single amino acid substitution in the NBS. Epistasis analysis indicated that SA and EDS1 are required for ssi4-induced PR-1 expression and enhanced disease resistance; they also are required for the increased accumulation of SSI4 and EDS1 transcripts detected in the ssi4 mutant. Although high levels of ssi4 transcripts correlate with the appearance of the mutant phenotype, overexpression of the wild-type SSI4 gene failed to induce stunting, spontaneous lesion formation, or increased PR-1 expression associated with the ssi4 mutation. Thus, the ssi4 phenotype does not appear to be caused by overexpression of this R gene; rather, we propose that the NBS substitution generates a constitutively activated R protein. Furthermore, because SA treatment induced the expression of SSI4 and the closely related TIR-NBS-LRR genes RPP1 and RPS4 but had little effect on the expression of the coiled-coil NBS-LRR genes RPM1 and RPS2, we suggest that SA not only functions as a critical signal for downstream resistance events but also upregulates the expression of certain R genes.

Amino Acid Sequence↗