The reactivity of alkaloids in dehydrogenation was investigated using multimatrix variation matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of over 20 different alkaloids with six matrices. The dehydrogenated molecular ions [M - H] generated by in-source decay were detected in the MALDI mass spectra of some types of alkaloids such as reserpine. The dehydrogenation proceeded at the cyclic tertiary amine rather than double-bonded nitrogen atoms and indole rings involved in the electron-delocalized systems. The stable protonated primary amines hindered dehydrogenation. The laser-induced dehydrogenation correlated with the chemical properties and structures of alkaloids. Alkaloids were classified into three types by the ratio of dehydrogenation by comparing the relative abundances of [M - H], [M], and [M + H] ions in α-cyano-4-hydroxycinnamic acid and 5-formylsalicylic acid matrices. Structural isomers were also discriminated by this method of analyzing the three molecular ions' ratio using multimatrix variation MALDI-MS.
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http://dx.doi.org/10.1021/jasms.2c00221 | DOI Listing |
Evolution
November 2024
Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, United Kingdom.
Intraspecific variation is necessary for evolutionary change and population resilience, but the extent to which it contributes to either depends on the causes of this variation. Understanding the causes of individual variation in traits involved with reproductive timing is important in the face of environmental change, especially in systems where reproduction must coincide with seasonal resource availability. However, separating the genetic and environmental causes of variation is not straightforward, and there has been limited consideration of how small-scale environmental effects might lead to similarity between individuals that occupy similar environments, potentially biasing estimates of genetic heritability.
View Article and Find Full Text PDFJ Toxicol Environ Health A
December 2024
Department of Environmental and Occupational Health, Chair in Toxicological Risk Assessment and Management, and Public Health Research Center (CReSP), University of Montreal, Montreal, Canada.
The aim of this study was to determine factors influencing observed increased metal biomarkers of exposure levels in a group of 116 Quebec apprentice welders during a longitudinal follow-up of exposure. Analysis of 14 metals was carried out in hair, fingernail, and toenail samples taken from participants over the course of their welding curriculum at 6 different times. Personal and socio-demographic characteristics, lifestyle habits, and other potential confounding factors were documented by questionnaire.
View Article and Find Full Text PDFBiometrics
January 2024
Division of Biostatistics and Health Data Science, University of Minnesota, Minneapolis, MN 55414, United States.
Statistical approaches that successfully combine multiple datasets are more powerful, efficient, and scientifically informative than separate analyses. To address variation architectures correctly and comprehensively for high-dimensional data across multiple sample sets (ie, cohorts), we propose multiple augmented reduced rank regression (maRRR), a flexible matrix regression and factorization method to concurrently learn both covariate-driven and auxiliary structured variations. We consider a structured nuclear norm objective that is motivated by random matrix theory, in which the regression or factorization terms may be shared or specific to any number of cohorts.
View Article and Find Full Text PDFStatistical approaches that successfully combine multiple datasets are more powerful, efficient, and scientifically informative than separate analyses. To address variation architectures correctly and comprehensively for high-dimensional data across multiple sample sets (i.e.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
December 2022
Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan.
The reactivity of alkaloids in dehydrogenation was investigated using multimatrix variation matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of over 20 different alkaloids with six matrices. The dehydrogenated molecular ions [M - H] generated by in-source decay were detected in the MALDI mass spectra of some types of alkaloids such as reserpine. The dehydrogenation proceeded at the cyclic tertiary amine rather than double-bonded nitrogen atoms and indole rings involved in the electron-delocalized systems.
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