Biology subjects

Edwards, M. E.

Publications and source records attributed to Edwards, M. E..

3 recordsLinked to original sources

bioRxiv2020

Holocene plant diversity revealed by ancient DNA from 10 lakes in northern Fennoscandia

The effects of climate change on species richness is debated but can be informed by the past. Here, we assess the impact of Holocene climate changes and nutrients on terrestrial plant richness across multiple sites from northern Fennoscandia using new sedimentary ancient DNA (sedaDNA) data quality control methods. We find that richness increased steeply during the rapidly warming Early Holocene. In contrast to findings from most pollen studies, we show that richness continued to increase through the Middle to Late Holocene even though temperature decreased, with the regional species pool only stabilizing during the last two millennia. Furthermore, overall increase in richness was greater in catchments with higher soil nutrient availability. We suggest that richness will rapidly increase with ongoing warming, especially at localities with high nutrient availability and even in the absence of increased human activity in the region, although delays of millennia may be expected.

ecology↗

bioRxiv2020

Quantification of extracellular vesicles with unaltered surface membranes using an internalized oligonucleotide tracer and droplet digital PCR applied to modeling of in vivo kinetics

Extracellular vesicles (EVs) continue to attract interest for their potential role in targeted therapeutics and as biomarkers of disease and drug response. In order to achieve clinical utility, it is important to determine the pharmacokinetic parameters of candidate EVs during preclinical development using in vivo animal models. To date, no methods exist for studying EV kinetics without modification to surface ligands that may affect normal behavior. Here we introduce an accessible method for labeling and quantifying EVs administered to conscious animals, without disrupting endogenous ligands. Our method relies upon established laboratory techniques and can be tailored to a variety of biological questions. Digital PCR is leveraged to detect a non-homologous oligonucleotide tracer introduced into the vesicles, allowing for quantification over a wide dynamic range. Using an application of this method, we found differences in the in vivo kinetics of EVs from three different cell types using non-linear mixed effects modeling. We propose that this method will provide a complementary approach for the of study EV ligand-receptor interactions in the context of EV uptake and targeted therapeutics.

molecular biology↗

bioRxiv2018

Metabarcoding lake sediments: taphonomy and representation of contemporary vegetation in environmental DNA (eDNA) records

Metabarcoding of lake sediments may reveal current and past biodiversity, but little is known about the degree to which taxa growing in the vegetation are represented in environmental DNA (eDNA) records. We analysed composition of lake and catchment vegetation and vascular plant eDNA at 11 lakes in northern Norway. Out of 489 records of taxa growing within 2 m from the lake shore, 17-49% (mean 31%) of the identifiable taxa recorded were detected with eDNA. Of the 217 eDNA records, 73% and 12% matched taxa recorded in vegetation surveys within 2 m and up to about 50 m away from the lakeshore, respectively, whereas 16% were not recorded in the vegetation surveys of the same lake. The latter include taxa likely overlooked in the vegetation surveys or growing outside the survey area. The percentages detected were 61, 47, 25, and 15 for dominant, common, scattered, and rare taxa, respectively. Similar numbers for aquatic plants were 88, 88, 33 and 62%, respectively. Detection rate and taxonomic resolution varied among plant families and functional groups with good detection of e.g. Ericaceae, Roseaceae, deciduous trees, ferns, club mosses and aquatics. The representation of terrestrial taxa in eDNA depends on both their distance from the sampling site and their abundance and is sufficient for recording vegetation types. For aquatic vegetation, eDNA may be comparable with, or even superior to, in-lake vegetation surveys and therefore be used as an tool for biomonitoring. For reconstruction of terrestrial vegetation, technical improvements and more intensive sampling is needed to detect a higher proportion of rare taxa although DNA of some taxa may never reach the lake sediments due to taphonomical constrains. Nevertheless, eDNA performs similar to conventional methods of pollen and macrofossil analyses and may therefore be an important tool for reconstruction of past vegetation.

ecology↗