Biology subjects

Pedersen, K. M.

Publications and source records attributed to Pedersen, K. M..

3 recordsLinked to original sources

bioRxiv2025

Dissecting specialized metabolism in space: A MALDI-MSI atlas of Amaryllidaceae alkaloids in Hippeastrum papilio (Ravenna) Van Scheepen

Amaryllidoideae produce specific specialized metabolites known as Amaryllidaceae alkaloids (AAs), extensively studied for their significant pharmacological potential. AAs spatial distribution and biosynthesis within plant tissues remain poorly understood. This study investigates organ- and tissue-specific localization in Hippeastrum papilio, from precursors to galanthamine and haemanthamine, using matrix-assisted laser desorption/ionization mass spectrometry imaging. Consistent accumulation of AAs was observed in epidermal and vascular tissues, with leaves exhibiting a uniform distribution across all ages and positions. Bulbs exhibited higher concentrations in the outer-scales and basal-plates, while roots displayed compartmentalized patterns, with galanthamine being uniquely abundant in the vascular bundles. Haemanthamine and galanthamine were detected in high quantities in the leaves and bulbs mucilage, while precursors were scarce. Multivariate analyses revealed that precursors clustered separately from end-products and were specifically enriched in the middle-scales and apical-leaves of the bulbs. Nonetheless, biosynthetic intermediates were observed in all tissues, indicating widespread AA biosynthesis across all organs. These findings suggest a coordinated metabolic network in H. papilio, which challenges existing hypotheses on organ-specific AA biosynthesis and hints at the transport of end-products. This study refines current models of alkaloid biosynthesis and underscore the value of H. papilio as a promising resource for sustainable production of therapeutic AAs. HighlightsMALDI-MSI reveals widespread, tissue-specific alkaloid distribution in Hippeastrum papilio, challenging organ-specific biosynthesis and implicating epidermal and vascular tissues in Amaryllidaceae alkaloid production.

plant biology↗

bioRxiv2024

Reassembly of a tropical rainforest ecosystem: A new chronosequence in the Ecuadorian Choco tested with the recovery of tree attributes

From hunting and foraging to clearing land for agriculture, humans modify forest biodiversity, landscapes, and climate. Forests constantly undergo disturbance-recovery dynamics and understanding them is a major objective of ecologists and conservationists. Chronosequences are a useful tool for understanding global restoration efforts. They represent a space-for-time substitution approach suited for the quantification of the resistance of ecosystem properties to withstand disturbance and the resilience of these properties until reaching pre-disturbance levels. Here we introduce a newly established chronosequence with 62 plots (50 50 m) in active cacao plantations and pastures, early and late regeneration, and mature old-growth forests, across a 200 km2 area in the extremely wet Choco rainforest. Our chronosequence covers by far the largest total area of plots compared to others in the Neotropics. Plots ranged from 159-615 masl in a forested landscape with 74 {+/-} 2.8 % forest cover within a 1-km radius including substantial old-growth forest cover. Land-use legacy and regeneration time were not confounded by elevation. We tested how six forest structure variables (maximum tree height and DBH, basal area, number of stems, vertical vegetation heterogeneity, and light availability), aboveground biomass (AGB), and rarefied tree species richness change along our chronosequence. Forest structure variables, AGB, and tree species richness increased with regeneration time and are predicted to reach similar levels to those in old-growth forests after ca. 30-116, 202, and 108 yrs, respectively. Compared to previous work in the Neotropics, old-growth forests in Canande accumulate high AGB that takes one of the largest time spans reported until total recovery. Our chronosequence comprises one of the largest tree species pools, covers the largest total area of regenerating and old-growth forests, and has higher forest cover than other Neotropical chronosequences. Hence, our chronosequence can be used to determine the time for recovery and stability (resistance and resilience) of different taxa and ecosystem functions, including species interaction networks. This integrative effort will ultimately help to understand how one of the most diverse forests on the planet recovers from large-scale disturbances.

ecology↗

bioRxiv2020

SorCS1 binds the insulin receptor to enhance insulin sensitivity

Type 2 diabetes has reached endemic proportions and is a substantial burden for the affected patients and the society. Along with lifestyle factors, a number of genetic loci predisposing to type 2 diabetes have been identified, including SORCS1 that encodes the transmembrane receptor SorCS1. The ectodomain of SorCS1 (sol-SorCS1) is shed from plasma membranes but the biological function of this fragment is unknown. Here we show that sol-SorCS1 acts as a high-affinity binding partner for the insulin receptor to stabilize the receptor and increase insulin affinity, protein kinase B activation, and glucose uptake in myocytes. Sol-SorCS1 is liberated from adipocytes, and in diabetic patients the plasma concentration positively correlates with body mass index, but inversely with plasma glucose. In mouse models of insulin resistance, exogenous sol-SorCS1 restored insulin sensitivity. We conclude that sol-SorCS1 increases peripheral insulin sensitivity and propose sol-SorCS1 as a novel insulin sensitizing adipokine and potential antidiabetic agent.

physiology↗