Protoplast swelling and hypocotyl growth depend on different auxin signaling pathways

Members of the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX PROTEIN (TIR1/AFB) family are known auxin receptors. To analyze the possible receptor function of AUXIN BINDING PROTEIN1 (ABP1), an auxin receptor currently under debate, we performed different approaches. We performed a pharmacological approach using α-(2,4-dimethylphenylethyl-2-oxo)-indole-3-acetic acid (auxinole), α-(phenylethyl-2-oxo)-indole-3-acetic acid (PEO-IAA), and 5-fluoroindole-3-acetic acid (5-F-IAA) to discriminate between ABP1- and TIR1/AFB-mediated processes in Arabidopsis (Arabidopsis thaliana). We used a peptide of the carboxyl-terminal region of AtABP1 as a tool. We performed mutant analysis with the null alleles of ABP1, abp1-c1 and abp1-TD1, and the TILLING mutant abp1-5. We employed Coimbra, an accession that exhibits an amino acid exchange in the auxin-binding domain of ABP1. We measured either volume changes of single hypocotyl protoplasts or hypocotyl growth, both at high temporal resolution. 5-F-IAA selectively activated the TIR1/AFB pathway but did not induce protoplast swelling; instead, it showed auxin activity in the hypocotyl growth test. In contrast, PEO-IAA induced an auxin-like swelling response but no hypocotyl growth. The carboxyl-terminal peptide of AtABP1 induced an auxin-like swelling response. In the ABP1-related mutants and Coimbra, no auxin-induced protoplast swelling occurred. ABP1 seems to be involved in mediating rapid auxin-induced protoplast swelling, but it is not involved in the control of rapid auxin-induced growth.GlossaryFCfusicoccin1-NAA1-naphthaleneacetic acidMOEMolecular Operating Environment2-NAA2-naphthaleneacetic acidERendoplasmic reticulumCol-0Columbia-0Co-1CoimbraSNPsingle-nucleotide polymorphis

Differentiation of Staphylococcus argenteus (formerly: Staphylococcus aureus clonal complex 75) by mass spectrometry from S. aureus using the first strain isolated from a wild African great ape

The species Staphylococcus argenteus was separated recently from Staphylococcus aureus (Tong S.Y., F. Schaumburg, M.J. Ellington, J. Corander, B. Pichon, F. Leendertz, S.D. Bentley, J. Parkhill, D.C. Holt, G. Peters, and P.M. Giffard, 2015). The objective of this work was to characterise the genome of a non-human S. argenteus strain, which had been isolated from the faeces of a wild-living western lowland gorilla in Gabon, and analyse the spectrum of this species in matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The full genome sequence revealed a scarcity of virulence genes and absence of resistance genes, indicating a decreased virulence potential compared to S. aureus and the human methicillin-resistant S. argenteus isolate MSHR1132T. Spectra obtained by MALDI-TOF MS and the analysis of available sequences in the genome databases identified several MALDI-TOF MS signals that clearly differentiate S. argenteus, the closely related Staphylococcus schweitzeri and S. aureus. In conclusion, in the absence of biochemical tests that identify the three species, mass spectrometry should be employed as method of choice.This work was supported by a grant of the Deutsches Zentrum für Infektionsforschung (DZIF) to Gabriele Bierbaum (TTU 08.902) and the Fundação para a Ciência e a Tecnologia (FCT) to Luís D.R. Melo (SFRH/BD/66166/2009) as well as by the BONFOR funds of the Medical Faculty of the University of Bonn and funds of the Centre International de Recherches Médicales de Franceville (CIRMF) and the Institut de Recherche pour le Développement (IRD)