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We develop a theory for transit times and mean ages for nonautonomous compartmental systems. Using the McKendrick-von Förster equation, we show that the mean ages of mass in a compartmental system satisfy a linear nonautonomous ordinary differential equation that is exponentially stable. We then define a nonautonomous version of transit time as the mean age of mass leaving the compartmental system at a particular time and show that our nonautonomous theory generalises the autonomous case. We apply these results to study a nine-dimensional nonautonomous compartmental system modeling the terrestrial carbon cycle, which is a modification of the Carnegie-Ames-Stanford approach model, and we demonstrate that the nonautonomous versions of transit time and mean age differ significantly from the autonomous quantities when calculated for that model.
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http://dx.doi.org/10.1007/s00285-016-0990-8 | DOI Listing |
Nutr J
September 2025
Department of Life Sciences, Division of Food and Nutrition Science, Chalmers University of Technology, Gothenburg, 412 96, Sweden.
Background: Avenanthramides (AVAs) and Avenacosides (AVEs) are unique to oats (Avena Sativa) and may serve as biomarkers of oat intake. However, information regarding their validity as food intake biomarkers is missing. We aimed to investigate critical validation parameters such as half-lives, dose-response, matrix effects, relative bioavailability under single dose, and in relation to the abundance of Feacalibacterium prausnitzii, and under repeated dosing, to understand the potential applications of AVAs and AVEs as biomarkers of oat intake.
View Article and Find Full Text PDFNat Metab
September 2025
Cellular and Molecular Physiology Department, Yale School of Medicine, New Haven, CT, USA.
The essential cofactor coenzyme A (CoASH) and its thioester derivatives (acyl-CoAs) have pivotal roles in cellular metabolism. However, the mechanism by which different acyl-CoAs are accurately partitioned into different subcellular compartments to support site-specific reactions, and the physiological impact of such compartmentalization, remain poorly understood. Here, we report an optimized liquid chromatography-mass spectrometry-based pan-chain acyl-CoA extraction and profiling method that enables a robust detection of 33 cellular and 23 mitochondrial acyl-CoAs from cultured human cells.
View Article and Find Full Text PDFCurr Biol
September 2025
Institute of Microbiology and Genetics, Department of Applied Bioinformatics, University of Göttingen, Goldschmidtstr. 1, 37077 Göttingen, Germany; Research Training Group 2984 Evolutionary Genomics: Consequences of Biodiverse Reproductive Systems (EvoReSt) and IMPRS Molecular Biology, Department
A new study shows that Sacoglossan sea slugs sequester stolen plastids in arrested phagosomes called 'kleptosomes', redefining how these organelles are compartmentalized and regulated in animal cells. Under normal conditions, the plastids are supported and maintained, but starvation causes their degradation, supporting a potential nutritional role.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202.
Retinal ganglion cells (RGCs) are highly compartmentalized neurons whose long axons serve as the sole connection between the eye and the brain. In both injury and disease, RGC degeneration occurs in a similarly compartmentalized manner, with distinct molecular and cellular responses in the axonal and somatodendritic regions. The goal of this study was to establish a microfluidic-based platform to investigate RGC compartmentalization in both health and disease states.
View Article and Find Full Text PDFInt J Biol Macromol
September 2025
Department of Chemical Engineering, Institute of Chemical Technology, Matunga (E), Mumbai, 400019, India. Electronic address:
Integrating multi-enzyme systems within metal-organic frameworks (MOFs) has garnered significant attention in biocatalysis due to their tunable structural properties and ability to enhance enzyme performance in cascade reactions. The unique features of MOFs, such as well-defined pore apertures, tailorable compositions, and high loading capacity, facilitate the design of robust multi-enzyme bio-composites with enhanced recyclability and specificity. This review explores systematic approaches for the compartmentalization and positional co-immobilization of multiple enzymes within MOFs, focusing on two key strategies: (i) layer-by-layer assembly and (ii) pore-engineered compartmentalization.
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