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J Ryals

Publications and source records attributed to J Ryals.

42 records · Page 3Linked to original sources
PubMed1982

Control of RNA synthesis in Escherichia coli after a shift to higher temperature.

Parameters of RNA synthesis were measured after a temperature upshift in a pair of Escherichia coli B/r strains that are isogenic except for having relA and relA+ loci, to examine the cause for a reported anomaly in the correlation between guanosine tetraphosphate (ppGpp) and stable RNA (rRNA, tRNA) synthesis under such conditions. Two main results were: (i) the specific stable RNA gene activity (stable RNA per total RNA synthesis) correlated in the conventionally expected fashion with the level of ppGpp but was obscured by a nonspecific increase in the RNA chain elongation rate due to the higher temperature; (ii) the temperature upshift caused a transient reduction in the RNA polymerase activity (transcribing per total enzyme) that accounts for the previously observed oscillating RNA synthesis rate after a temperature shift.

Bacterial Proteins↗
PubMedDate not supplied

A new multigene family inducible by tobacco mosaic virus or salicylic acid in tobacco.

A previously undescribed cDNA family was isolated from tobacco challenged with tobacco mosaic virus (TMV). A cDNA library was constructed with mRNA from upper leaves of Xanthi nc tobacco plants that had been inoculated with TMV on the lower leaves 11 days previously. The library was screened differentially with radiolabeled cDNA synthesized with mRNA from upper, uninoculated leaves of either TMV-inoculated or mock-inoculated tobacco plants. The new cDNA family, designated SAR8.2, had at least five expressed members, one or more of which were inducible by TMV inoculation and by salicylic acid treatment. The cDNAs encoded small, highly basic proteins containing N-terminal hydrophobic signal peptides and highly conserved cysteine-rich C-terminal domains. One of the SAR8.2 family members contained a direct repeat of the C-terminal domain in tandem. Hybridization of SAR8.2 cDNA to tobacco genomic DNAs indicated a gene family of 10-12 members.

Amino Acid Sequence↗
PubMedDate not supplied

Regulation of a hevein-like gene in Arabidopsis.

An Arabidopisis cDNA clone was isolated that encodes a protein similar to the antifungal chitin-binding protein hevein from rubber tree latex. This hevein-like (HEL) mRNA was inducible by either turnip crinkle virus infection or ethylene treatment. In addition, expression was moderately inducible by treatment with the resistance-inducing compounds salicylic acid and 2,6-dichlorisonicotinic acid. The 786-bp cDNA contains an open reading frame of 212 codons. The deduced amino acid sequence contains a putative signal sequence of 21 amino acids followed by a 43-amino-acid cysteine-rich lectin domain and a 129-amino-acid carboxy-terminal domain. The predicted protein is approximately 70% identical to hevein, to the wound-inducible WIN1 and WIN2 proteins from potato, and to PR-4, a pathogenesis-related protein from tobacco.

Amino Acid Sequence↗
PubMedDate not supplied

Regulation of cucumber class III chitinase gene expression.

The chromosomal region encoding the acidic class III chitinase from cucumber has been isolated and characterized. As a result of an apparent gene triplication, the pathogen-induced gene (CHI2) is flanked by two closely related genes with complete open reading frames (ORF). The high level of conservation within the three ORFs suggests an essential role for each encoded protein in plant growth and development. The developmental and tissue-specific expression of RNA from each gene was analyzed using both gene-specific probes and RNA-PCR. The expression of each gene in response to various inducing treatments was also characterized. Only transcripts corresponding to CHI2 were detected. Chitinase mRNA abundance increased slightly following cycloheximide application; however, its potent induction by salicylic acid was inhibited by cycloheximide treatment.

Amino Acid Sequence↗
PubMedDate not supplied

Systemic acquired resistance in Arabidopsis requires salicylic acid but not ethylene.

Systemic acquired resistance (SAR) is an inducible plant response to infection by a necrotizing pathogen. In the induced plant, SAR provides broad-spectrum protection against not only the inducing pathogen, but also against other, unrelated pathogens. Both salicylic acid (SA) and SAR-gene expression have been implicated as playing important roles in the initiation and maintenance of SAR. Here, we describe the characterization of transgenic Arabidopsis plants that express the bacterial nahG gene encoding salicylate hydroxylase, an enzyme that can metabolize SA. Strong, constitutive expression of this gene prevents pathogen-induced accumulation of SA and the activation of SAR by exogenous SA. We show that SAR in Arabidopsis can be induced by inoculation with Pseudomonas syringe pv. tomato against infection by a challenge inoculation with Peronospora parasitica. This response is abolished in transgenic, nahG-expressing Arabidopsis, but not in ethylene-insensitive mutants. These experiments support the critical role of SA in SAR and show that ethylene sensitivity is not required for SAR induction. The NahG Arabidopsis plants will be important for future studies aimed at understanding the role of SA in plant disease resistance mechanisms.

Arabidopsis↗