Transcriptomic Signatures of Ash (Fraxinus spp.) Phloem

Ash (Fraxinus spp.) is a dominant tree species throughout urban and forested landscapes of North America (NA). The rapid invasion of NA by emerald ash borer (Agrilus planipennis), a wood-boring beetle endemic to Eastern Asia, has resulted in the death of millions of ash trees and threatens billions more. Larvae feed primarily on phloem tissue, which girdles and kills the tree. While NA ash species including black (F. nigra), green (F. pennsylvannica) and white (F. americana) are highly susceptible, the Asian species Manchurian ash (F. mandshurica) is resistant to A. planipennis perhaps due to their co-evolutionary history. Little is known about the molecular genetics of ash. Hence, we undertook a functional genomics approach to identify the repertoire of genes expressed in ash phloem.Using 454 pyrosequencing we obtained 58,673 high quality ash sequences from pooled phloem samples of green, white, black, blue and Manchurian ash. Intriguingly, 45% of the deduced proteins were not significantly similar to any sequences in the GenBank non-redundant database. KEGG analysis of the ash sequences revealed a high occurrence of defense related genes. Expression analysis of early regulators potentially involved in plant defense (i.e. transcription factors, calcium dependent protein kinases and a lipoxygenase 3) revealed higher mRNA levels in resistant ash compared to susceptible ash species. Lastly, we predicted a total of 1,272 single nucleotide polymorphisms and 980 microsatellite loci, among which seven microsatellite loci showed polymorphism between different ash species.The current transcriptomic data provide an invaluable resource for understanding the genetic make-up of ash phloem, the target tissue of A. planipennis. These data along with future functional studies could lead to the identification/characterization of defense genes involved in resistance of ash to A. planipennis, and in future ash breeding programs for marker development

On Cysteine and Cystein Peptides. II. S-Acylcysteines in Peptide Synthesis

An approach to the synthesis of unsymmetrical cystine peptides containing at least two-S-S-bridges which entails the use of selectively removable S-protecting groups is discussed. In addition to S-trityl- and S-diphenylmethyl-, S-benzoyl-, S-acetyl- and S-carbobenzoxycysteines are shown to be very useful intermediates for the incorporation of cysteine residues into a peptide chain. The removal of these S-acyl groups which are, in a certain sense, “active esters” can easily be achieved by methanolysis in the presence of sodium methoxide. Furthermore, the S-benzoyl group is not attacked by the N-decarbobenzoxylating agents trifluoroacetic acid and hydrogen bromide in acetic acid. The S-acetyl group is resistant to trifluoroacetic acid but is removed by hydrogen bromide in acetic acid and the S-carbobenzoxy group is split off by trifluoroacetic acid but survives the treatment with 2 N hydrogen bromide in acetic acid to a very great extent. Consequently, these S-acylcysteine residues can be used for peptide synthesis by means of their N-carbobenzoxy derivatives. Using S-acylcysteine residues, several cysteine-containing peptides have been synthesized and converted to the corresponding cystine peptides. The use of the above-mentioned S-protecting groups for overcoming the unique difficulties inherent in establishing a disulfide bridge specifically between two of three cysteine residues of a peptide chain, as in fragment IX of insulin, has been explored. © 1963, American Chemical Society. All rights reserved

Etude structurale et fonctionnelle des aspartokinases-homoserine deshydrogenases d'E. coli

SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Thoracic sarcopenia as a predictive factor of SARS-COV2 evolution

Purpose: Evaluation of CT sarcopenia as a predictor of intensive care hospitalization during SARS-COV2 infection.Materials and methods: Single-center retrospective study of patients admitted to hospital with SARS-COV2 infection. The estimation of muscle mass (skeletal muscle index (SMI)) for sarcopenia, measure-ment of muscle density for muscle quality and body adiposity, were based on CT views on the T4 and L3 levels measured at admission. Demographic data, percentage of pulmonary parenchymal involvement as well as the orientation of patients during hospitalization and the risk of hospitalization in intensive care were collected.Results: A total of 162 patients hospitalized for SARS-COV2 infection were included (92 men and 70 women, with an average age of 64.6 years and an average BMI of 27.4). The muscle area measured at the level of L3 was significantly associated with the patient's unfavorable evolution (124.4cm2 [97; 147] vs 141.5 cm2 [108; 173]) (p 1/4 0.007), as was a lowered SMI (p < 0.001) and the muscle area measured in T4 (OR 1/4 0.98 [0.97; 0.99]), (p 1/4 0.026). Finally, an abdominal visceral fat area measured at the level of L3 was also associated with a risk of hospitalization in intensive care (249.4cm2 [173; 313] vs 147.5cm2 [93.1; 228] (p < 0.001).Conclusion: This study demonstrates that thoracic and abdominal sarcopenia are independently asso-ciated with an increased risk of hospitalization in an intensive care unit, suggesting the need to assess sarcopenia on admission during SARS-COV2 infection

An early Ca2+ influx is a prerequisite to thaxtomin A-induced cell death in Arabidopsis thaliana cells

International audienceThe pathogenicity of various Streptomyces scabies isolates involved in potato scab disease was correlated with the production of thaxtomin A. Since calcium is known as an essential second messenger associated with pathogen-induced plant responses and cell death, it was investigated whether thaxtomin A could induce a Ca 2+ influx related to cell death and to other putative plant responses using Arabidopsis thaliana suspension cells, which is a convenient model to study plant–microbe interactions. A. thaliana cells were treated with micromolar concentrations of thaxto-min A. Cell death was quantified and ion flux variations were analysed from electrophysiological measurements with the apoaequorin Ca 2+ reporter protein and by external pH measurement. Involvement of anion and calcium channels in signal transduction leading to programmed cell death was determined by using specific inhibitors. These data suggest that this toxin induces a rapid Ca 2+ influx and cell death in A. thaliana cell suspensions. Moreover, these data provide strong evidence that the Ca 2+ influx induced by thaxtomin A is necessary to achieve this cell death and is a prerequisite to early thaxtomin A-induced responses: anion current increase, alkalization of the external medium, and the expression of PAL1 coding for a key enzyme of the phenylpropanoid pathway