Malcolm Lowry, Under the Volcano
in Pouvelle, Jean; Demarche, Jean-Pierre (Eds.) Guide de la littérature britannique des origines à nos jours (2008)
This is a short introduction, in French, intended for students from 16 to 20. It brings out the most outstanding features of Lowry's major novel and provides three original translations.Detailed reference viewed: 129 (10 ULg)
MALDI imaging and profiling MS of higher mass proteins from tissue.
; ; et al
in Journal of the American Society for Mass Spectrometry (2010), 21(11), 1922-9Detailed reference viewed: 14 (0 ULg)
MALDI Imaging Mass Spectrometry for Studying Cancer Diseases
Longuespée, Rémi ; ; et al
Conference (2011, February)Detailed reference viewed: 48 (0 ULg)
MALDI imaging mass spectrometry in ovarian cancer for tracking, identifying, and validating biomarkers.
; ; Longuespée, Rémi et al
in Medical Science Monitor : International Medical Journal of Experimental and Clinical Research (2010), 16(8), 233-45Detailed reference viewed: 23 (0 ULg)
MALDI In-Source Decay for High Throughput sequencing of peptide animal toxins
Quinton, Loïc ; Degueldre, Michel ; et al
Poster (2012)Detailed reference viewed: 20 (2 ULg)
MALDI in-source decay of high mass protein isoforms: application to alpha- and beta-tubulin variants.
Calligaris, David ; ; et al
in Analytical Chemistry (2010), 82(14), 6176-6184
Tubulin is one of the major targets in cancer chemotherapy and the target of more than twenty percent of the cancer chemotherapic agents. The modulation of isoform content has been hypothesized as being a ... [more ▼]
Tubulin is one of the major targets in cancer chemotherapy and the target of more than twenty percent of the cancer chemotherapic agents. The modulation of isoform content has been hypothesized as being a cause of resistance to treatment. Isoform differences lie mostly in the C-terminus part of the protein. Extensive characterization of this polypeptide region is therefore of critical importance. MALDI-TOF fragmentation of tubulin C-terminal domains was tested using synthetic peptides. Then, isotypes from HeLa cells were successfully characterized for the first time by in-source decay (ISD) fragmentation of their C-terminus coupled to a pseudo MS3 technique named T3-sequencing. The fragmentation occurred in-source, preferentially generating yn-series ions. This approach required guanidination for the characterization of the βIII-tubulin C-terminus peptide. This study is, to our knowledge, the first example of reflectron in-source decay (reISD) of the C-terminus of a 50 kDa protein. This potentially occurs via a CID-like mechanism occurring in the MALDI plume. There are now new avenues for top-down characterization of important clinical biomarkers such as βIII-tubulin isotypes, a potential marker of drug resistance and tumor progression. This paper raises the challenge of protein isotypes characterization for early cancer detection and treatment monitoring. [less ▲]Detailed reference viewed: 27 (1 ULg)
MALDI In-Source Decay, from sequencing to imaging
Debois, Delphine ; Smargiasso, Nicolas ; Demeure, Kevin et al
in Topics in Current Chemistry (2013), 331
MALDI is now a mature method allowing the identification and, more challenging, the quantification of biopolymers (proteins, nucleic acids, glycans…). MALDI spectra show mostly intact singly charged ions ... [more ▼]
MALDI is now a mature method allowing the identification and, more challenging, the quantification of biopolymers (proteins, nucleic acids, glycans…). MALDI spectra show mostly intact singly charged ions. To obtain fragments, the activation of singly charged precursors is necessary, but not efficient above 3.5 kDa thus making MALDI MS/MS difficult for large species. In-source decay (ISD) is a prompt fragmentation reaction that can be induced thermally or by radicals. As fragments are formed in the source, precursor ions cannot be selected; however, the technique is not limited by the mass of the analyzed compounds and pseudo MS/MS can be performed on intense fragments. The discovery of new matrices that enhance the ISD yield, combined with the high sensitivity of MALDI mass spectrometers, and software development, opens new perspectives. We first review the mechanisms involved in the ISD processes, then discuss ISD applications like top-down sequencing and post-translational modifications studies, and finally review MALDI-ISD tissue imaging applications. [less ▲]Detailed reference viewed: 124 (43 ULg)
MALDI Mass Spectrometry Imaging for the Screening of Epithelial Ovarian Cancer Biomarkers.
; Longuespée, Rémi ; et al
Poster (2011, September)Detailed reference viewed: 40 (0 ULg)
MALDI mass spectrometry imaging of proteins exceeding 30,000 daltons.
; Longuespée, Rémi ; et al
in Medical Science Monitor : International Medical Journal of Experimental and Clinical Research (2010), 16(9), 293-9Detailed reference viewed: 30 (1 ULg)
MALDI mass spectrometry imaging of secreted lipopeptides in a bacterial biofilm colonizing plant roots
Debois, Delphine ; Jourdan, Emmanuel ; Ongena, Marc et al
Conference (2011, June 06)
During the aggression of a plant by a pathogen, different immune reactions may occur. "Induced Systemic Resistance” (ISR) is triggered by the specific interaction between plant and non-pathogenic ... [more ▼]
During the aggression of a plant by a pathogen, different immune reactions may occur. "Induced Systemic Resistance” (ISR) is triggered by the specific interaction between plant and non-pathogenic microorganism. The first step (of three) consists in the perception by plant cells of elicitors produced by the inducing agents that initiates the phenomenon. One class of known elicitors is antibiotics including surfactin- and fengycin-type lipopeptides. Recent studies in biology, genetics or biochemistry allowed a better understanding of the interactions between plants and microorganism but few has been done at the molecular level. MALDI MS imaging has been used to study the nature of the secreted lipopeptides, their relative quantity and their distribution in the root’s environment. Disinfected tomato seeds were first incubated at 28°C in sterile conditions for germination. Germinated seeds were then treated with freshly-grown cells of Bacillus amyloliquefaciens S499 and placed in Petri dish on ITO glass slide recovered with a thin layer of plant nutritive solution (Hoagland) containing 1,75% of agar. Petri dishes were finally incubated vertically in phytotron during 10 days (28°C, photoperiod 16h). For MALDI imaging experiments, the ITO slide was removed from the agar and dried in a dessiccator under vacuum. The matrix solution (9-aminoacridine) was applied with an ImagePrep automated sprayer (Bruker Daltonics). An UltraFlex II TOF/TOF mass spectrometer was used to record molecular cartographies. The average mass spectra recorded around the tomato root (2-3 mm on both sides of the root) showed that lipopeptides were major compounds detected on the agar. Only the surfactins have been detected when working with the S499 strain. The most abundant surfactins were those with longer fatty acyl chain lengths, such as C14- and C15-homologues. Such a surfactin signature is interesting since homologues with the longest acyl chains are also the more active biologically. The distribution of surfactins showed a gradient representing the diffusion of the molecules during the root growth. The more the fatty acyl chain is long, the more the surfactin is detected near the root. Other compounds detected during the analysis showed a clear anti-colocalization with the surfactins. Future work will be focused on the influence of the plant species (tobacco, salad, Arabidopsis thaliana) on the secretion of lipopeptides (type, concentration…) and the influence of the strain of Bacillus amyloliquefaciens regarding its ability to selectively produce specific lipopeptide families (overproducing or repressed mutants). This MS imaging technique thus appears to be a very powerful method to study in situ production of bioactive lipopeptides by bacteria developing on roots. This is crucial for a better understanding of the molecular dialogue governing perception of beneficial Bacillus strains by the host plant. This study provides a first analysis over a long root section of lipopeptides secreted by a bacterial biofilm colonizing plant. [less ▲]Detailed reference viewed: 121 (3 ULg)
MALDI Mass Spectrometry Imaging: a new tool to decipher the antibiome of Bacillus amyloliquefaciens
Debois, Delphine ; ; et al
Conference (2014, June 05)
Soil Bacillus isolates may devote up to 8% of their genome to nonribosomal synthesis of lipopeptide (LP)- and polyketide (PK)-type antibiotics. LPs from surfactin, iturin and fengycin families are known ... [more ▼]
Soil Bacillus isolates may devote up to 8% of their genome to nonribosomal synthesis of lipopeptide (LP)- and polyketide (PK)-type antibiotics. LPs from surfactin, iturin and fengycin families are known to exert different actions on the wellness of the producing strain such as fungitoxicity (iturin, fengycin) or motility, root colonization and immune stimulating agent (surfactin). Nevertheless, few is reported about the actual antibiome secreted in situ by Bacillus cells during confrontation with phytopathogens or plant root colonization. We developed a method mimicking the conditions prevailing in the rhizosphere and, taking advantage of the versatility of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging, we were able to localize and identify antibiotics produced in situ by bacterial cells. First, we applied this new methodology to bioassays in which Bacillus amyloliquefaciens 98S were grown together with Fusarium oxysporum, with the aim of deciphering the role of the different LP families during the phytopathogen growth inhibition. Our results showed that the three LP families were readily produced in different proportions. Especially, images of surfactins, iturins and fengycins demonstrated that iturins are the antibiotic family actually involved in the antagonism against Fusarium oxysporum. In a second approach, we used a “in planta” model in which Bacillus amyloliquefaciens S499 was simultaneously grown with Tomato and Arabidopsis thaliana roots. Imaging results, obtained during a time course analysis, showed that surfactin is always the major lipopeptide detected. In further experiments involving a refined time-window, we observed that surfactin is actually produced as soon as 24h post inoculation. These results were the starting point of a wider study showing that the early accumulation of surfactin is a complex phenomenon involving, among other mechanisms, cell-well components recognition by bacteria, and that this interaction is a win-win association for both plant and bacterial cells. [less ▲]Detailed reference viewed: 148 (11 ULg)
MALDI MS Tissue Imaging of Crystallins using an original metyhod to direct protein identification on lens slices
Bertrand, Virginie ; Debois, Delphine ; Quinton, Loïc et al
Poster (2010, April 16)
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. Crystallins, α, β and γ, are the predominant structural proteins ... [more ▼]
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. Crystallins, α, β and γ, are the predominant structural proteins in lens. They constitute 90% of water soluble proteins and contribute to its transparency and refractive properties by a uniform concentration gradient in the lens. Nevertheless, if these crystallins undergo post translational modifications, they become less soluble and the opacity of eye lens increases. This phenomenon defines cataract. Yet, the nature and the mechanism of occurring of these modifications and how they happen are not fully understood. MALDI mass spectrometry imaging is a recent technique allowing examining proteins in their native location without the need for traditional processing methods such as extraction, homogenization, and separation. Nevertheless, one main difficulty lies in the identification of the detected species, especially proteins. MALDI-In Source Decay (MALDI-ISD) is a fragmentation process occurring in the mass spectrometer ion source. When the analyzed sample is a protein, ISD fragmentation leads to b-, c- and z-ions series, which allows for some sequencing of the protein. One great advantage of ISD is its fastness and easiness to be implemented since there is no need for a special treatment of the sample. The only requirement is the use of “ISD-favourable MALDI matrix” such as 2,5-dihydroxybenzoic acid or 1,5-diaminonaphtalene. 18 µm-thick equatorial sections of frozen porcine eye lenses were realized with a cryostat. 1,5-DAN matrix was either manually deposited or sprayed with an ImagePrep automated device (Bruker Daltonics). Data were acquired with an UltraFlex II MALDI-TOF/TOF mass spectrometer (BD) in positive reflector mode. For imaging experiments, the surface of the sample was divided into 100-µm-wide pixels and 500 shots were averaged on each. Based on calculated mass differences between consecutive ISD fragments peaks, tags of amino acids were established and submitted to a search in protein databases using a BLAST algorithm (search by sequence homology). Imaging experiments showed that the localization information may be very useful to associate fragments which exhibit close distributions, suggesting they are originating from the same protein. It is thus possible to arrange fragments in groups of probable origin and to extract the mass spectrum of a high-intensity pixel. This allows to work with a “purified” ISD mass spectrum where fragments of only one protein are present and potentially exhibiting a higher number of peaks, leading to a longer tag and to an easier identification. With this imaging strategy, we were able to identify (by homology) the Beta-Crystallins S and B2, the Gamma-Crystallin B, the Alpha-Crystallin A. [less ▲]Detailed reference viewed: 43 (9 ULg)
MALDI MSI for ovarian cancer biomarkers research: latest developments of the technology for screening and tracking.
in Histochemistry & Cell Biology (2012, July), 138(1), 141-54Detailed reference viewed: 22 (1 ULg)
MALDI MSI for the screening of ovarian cancer biomarkers: new insight of the technology for new issues in pharmacology.
Longuespée, Rémi ; ; et al
Conference (2011, September)Detailed reference viewed: 39 (0 ULg)
MALDI-FTICR MS Imaging as a Powerful Tool to Identify Paenibacillus Antibiotics Involved in the Inhibition of Plant Pathogens
Debois, Delphine ; Ongena, Marc ; Cawoy, Hélène et al
in Journal of the American Society for Mass Spectrometry (2013), 24(8), 1202-1213
Nowadays, microorganisms are more and more often used as biocontrol agents for crop protection against diseases. Among them, bacteria of Bacillus and Paenibacillus genders are already used as commercial ... [more ▼]
Nowadays, microorganisms are more and more often used as biocontrol agents for crop protection against diseases. Among them, bacteria of Bacillus and Paenibacillus genders are already used as commercial biocontrol agents. Their mode of action is supposed to be related to their production of antibiotics, such as cyclic lipopeptides, which exhibit great antimicrobial activities. We chose to work with a Paenibacillus polymyxa strain (Pp56) very resistant to various microorganisms. The bacteria were grown simultaneously with Fusarium oxysporum and we applied matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) mass spectrometry to identify the antibiotics compounds present in the fungus growth inhibition area. We, therefore, identified fusaricidins A, B, and C and numerous members of the LI-F antibiotics family. MALDIFTICR mass spectrometry imaging was then used to follow the diffusion of lipopeptides involved in the inhibitory activity over time. We analyzed the molecular content of the inhibitory area at different Pp56 and Fusarium incubation durations and concluded that some lipopeptides such as fusaricidin B and a mixture of LI-F05b/06b/08a were mainly involved in the defense mechanism of Pp56. Our study confirms that MALDI imaging may be a powerful tool to quickly determine which molecular species is involved in an antagonism with another microorganism, avoiding time-consuming steps of extraction, purification, and activity tests, which are still commonly used in microbiology. [less ▲]Detailed reference viewed: 70 (16 ULg)
MALDI-In Source Decay Applied to Mass Spectrometry Imaging: A New Tool for Protein Identification.
Debois, Delphine ; Bertrand, Virginie ; Quinton, Loïc et al
in Analytical Chemistry (2010), 82(10), 3969-4304
Matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) imaging is a powerful technique giving access to the distribution of a large range of biomolecules directly from a tissue section ... [more ▼]
Matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS) imaging is a powerful technique giving access to the distribution of a large range of biomolecules directly from a tissue section, allowing, for example, the discovery of new pathological biomarkers. Nevertheless, one main difficulty lies in the identification of the detected species, especially proteins. MALDI-in source decay (ISD) is used to fragment ions directly in the mass spectrometer ion source. This technique does not require any special sample treatment but only the use of a specific MALDI matrix such as 2,5-dihydroxybenzoic acid or 1,5-diaminonaphthalene. MALDI-ISD is generally employed on classical, purified samples, but here we demonstrate that ISD can also be performed directly on mixtures and on a tissue slice leading to fragment ions, allowing the identification of major proteins without any further treatment. On a porcine eye lens slice, de novo sequencing was even performed. Crystallins not yet referenced in databases were identified by sequence homology with other mammalian species. On a mouse brain slice, we demonstrate that results obtained with ISD are comparable and even better than those obtained with a classical in situ digestion. [less ▲]Detailed reference viewed: 158 (36 ULg)
Maldi-TOF : 3 years of experience in the university hospital of liege - Integration in the routine workflow and participation to the filamentous fungi project
Conference (2012)Detailed reference viewed: 15 (0 ULg)
MALDI-TOF : a revolution in the clinical microbiology lab ! Which impact on infectious diseases management ?
Conference (2010)Detailed reference viewed: 7 (0 ULg)