Imaging mass spectrometry for spatial metabolomics

Over the past decade, mass spectrometry (MS) has seen major technical advances that have increased the scope, applicability and adoption of the technology in a vast array of research areas (1)

A Survey of the Foot and Mouth Disease Problem in Mexico.

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Mass spectrometry based imaging of labile glucosides in plants

Mass spectrometry based imaging is a powerful tool to investigate the spatial distribution of a broad range of metabolites across a variety of sample types. The recent developments in instrumentation and computing capabilities have increased the mass range, sensitivity and resolution and rendered sample preparation the limiting step for further improvements. Sample preparation involves sectioning and mounting followed by selection and application of matrix. In plant tissues, labile small molecules and specialized metabolites are subject to degradation upon mechanical disruption of plant tissues. In this study, the benefits of cryo-sectioning, stabilization of fragile tissues and optimal application of the matrix to improve the results from MALDI mass spectrometry imaging (MSI) is investigated with hydroxynitrile glucosides as the main experimental system. Denatured albumin proved an excellent agent for stabilizing fragile tissues such as Lotus japonicus leaves. In stem cross sections of Manihot esculenta, maintaining the samples frozen throughout the sectioning process and preparation of the samples by freeze drying enhanced the obtained signal intensity by twofold to fourfold. Deposition of the matrix by sublimation improved the spatial information obtained compared to spray. The imaging demonstrated that the cyanogenic glucosides (CNglcs) were localized in the vascular tissues in old stems of M. esculenta and in the periderm and vascular tissues of tubers. In MALDI mass spectrometry, the imaged compounds are solely identified by their m/z ratio. L. japonicus MG20 and the mutant cyd1 that is devoid of hydroxynitrile glucosides were used as negative controls to verify the assignment of the observed masses to linamarin, lotaustralin, and linamarin acid

The metabolic environment of the developing embryo: A multidisciplinary approach on oilseed rapeseed

Brassicaceae seeds consist of three genetically distinct structures: the embryo, endosperm and seed coat, all of which are involved in assimilate allocation during seed development. The complexity of their metabolic interrelations remains unresolved to date. In the present study, we apply state-of-the-art imaging and analytical approaches to assess the metabolic environment of the Brassica napus embryo. Nuclear magnetic resonance imaging (MRI) provided volumetric data on the living embryo and endosperm, revealing how the endosperm envelops the embryo, determining endosperm's priority in assimilate uptake from the seed coat during early development. MRI analysis showed higher levels of sugars in the peripheral endosperm facing the seed coat, but a lower sugar content within the central vacuole and the region surrounding the embryo. Feeding intact siliques with 13C-labeled sucrose allowed tracing of the post-phloem route of sucrose transfer within the seed at the heart stage of embryogenesis, by means of mass spectrometry imaging. Quantification of over 70 organic and inorganic compounds in the endosperm revealed shifts in their abundance over different stages of development, while sugars and potassium were the main determinants of osmolality throughout these stages. Our multidisciplinary approach allows access to the hidden aspects of endosperm metabolism, a task which remains unattainable for the small-seeded model plant Arabidopsis thaliana

Prevalence and number of Salmonella in retail pork sausages

The aim of this study was to assess the prevalence of Salmonella in Irish pork sausage at retail level. Samples, comprising branded prepacked sausages, loose sausages from supermarket meat counters and butcher shops, were collected from selected retail sites in four cities from October to December 2001 and from June to August 2002. A 3-tube Most Probable Number (MPN) method was used to enumerate Salmonella in a selected number of samples, which were positive by enrichment. Salmonella serotypes were detected in 4.4% and 1.7% of samples at each of the respective sampling periods; a level similar to those reported in other U.S. and U.K. studies. Limited results available on enumeration suggest that contamination rates were low. This study revealed that Salmonella are present in a proportion of Irish sausages and further risk analysis work is necessary in order to quantify the risk posed to public health. Keywords: control programme, enumeration, serology, bacteriology, food safety

Metabolic profiling of a transgenic Caenorhabditis elegans Alzheimer model

Despite decades of research, no early-onset biomarkers are currently available for Alzheimer’s disease, a cureless neurodegenerative disease afflicting millions worldwide. In this study, transgenic Caenorhabditis elegans were used to investigate changes in the metabolome after induced expression of amyloid-β. GC- and LC–MS-based platforms determined a total of 157 differential features. Some of these were identified using in-house (GC–MS) or public libraries (LC–MS), revealing changes in allantoin, cystathionine and tyrosine levels. Since C. elegans is far better suited to metabolomics studies than most other model systems, the accordance of these findings with vertebrate literature is promising and argues for further use of C. elegans as a model of human pathology in the study of AD

Corrigendum: Quantification and localization of Formylated Phloroglucinol Compounds (FPCs) in Eucalyptus Species

Error in Figure/Table In the original article, there was a mistake in Figure 4 and Supplementary Table S2 as published. There was an error during the FPCs quantification process, whereby the ratio of injection volume between sample and standard was accidentally inverted. This error has resulted in the overestimation of FPCs concentration reported, but does not alter the biological significance of the results. The corrected Figure 4 appears below, and Supplementary Table S2 has been replaced in the original article. Furthermore, in the original article, there was an error in the results section where the number of total FPCs for different tissues of two species are cited. A correction has been made to the Results section, sub-section Detection and Quantification of FPCs, paragraph four: “From all species analyzed, E. camphora and E. globulus had the highest concentration of total FPCs in leaves, with 65 and 41mg g−1 DW, respectively (Figure 4, Supplementary Table S2). Eucalyptus camphora also had high concentration of FPCs in flower buds and flowers, with 13 and 12mg g−1 DW, respectively. Interestingly, three Eucalyptus species showed a tendency to accumulate more FPCs in flowers compared to the leaves. Eucalyptus leucoxylon, E. sideroxylon, and E. viminalis contained ~40, 5, and 3 times more total FPCs in the flowers compared to leaves, respectively Figure 4, Supplementary Table S2. Eucalyptus yarraensis presented very low amounts of FPCs in leaves and flower buds, and it is the only species that does not contain any sideroxylonals. Eucalyptus cladocalyx and C. ficifolia did not show any traces of this class of specialized metabolites in the tissues analyzed.

Phenothiazine-Salt Mixture, Free Choice, for the Control of the Large Stomach Worm in Range Sheep.

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