| 1. |
- Bugge Harder, Christoffer, et al.
(författare)
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Successional trophic complexity and biogeographical structure of eukaryotic communities in waterworks' rapid sand filters
- 2019
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 95:11
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Tidskriftsartikel (refereegranskat)abstract
- As groundwater-fed waterworks clean their raw inlet water with sand filters, a variety of pro-and eukaryotic microbial communities develop on these filters. While several studies have targeted the prokaryotic sand filter communities, little is known about the eukaryotic communities, despite the obvious need for knowledge of microorganisms that get in contact with human drinking water. With a new general eukaryotic primer set (18S, V1-V3 region), we performed FLX-454 sequencing of material from 21 waterworks' sand filters varying in age (3-40 years) and geographical location on a 250 km east-west axis in Denmark, and put the data in context of their previously published prokaryotic communities. We find that filters vary highly in trophic complexity depending on age, from simple systems with bacteria and protozoa (3-6 years) to complex, mature systems with nematodes, rotifers and turbellarians as apex predators (40 years). Unlike the bacterial communities, the eukaryotic communities display a clear distance-decay relationship that predominates over environmental variations, indicating that the underlying aquifers feeding the filters harbor distinct eukaryotic communities with limited dispersal in between. Our findings have implications for waterworks' filter management, and offer a window down to the largely unexplored eukaryotic microbiology of groundwater aquifers.
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| 2. |
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| 3. |
- Jacobsen, Carsten Suhr, et al.
(författare)
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Inter-laboratory testing of the effect of DNA blocking reagent G2 on DNA extraction from low-biomass clay samples
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Here we show that a commercial blocking reagent (G2) based on modified eukaryotic DNA significantly improved DNA extraction efficiency. We subjected G2 to an inter-laboratory testing, where DNA was extracted from the same clay subsoil using the same batch of kits. The inter-laboratory extraction campaign revealed large variation among the participating laboratories, but the reagent increased the number of PCR-amplified16S rRNA genes recovered from biomass naturally present in the soils by one log unit. An extensive sequencing approach demonstrated that the blocking reagent was free of contaminating DNA, and may therefore also be used in metagenomics studies that require direct sequencing.
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| 4. |
- Lett, Signe, et al.
(författare)
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Can bryophyte groups increase functional resolution in tundra ecosystems?
- 2022
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Ingår i: Arctic Science. - Ottawa : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 609-637
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Tidskriftsartikel (refereegranskat)abstract
- The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.
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| 5. |
- Lundholm, Nina, et al.
(författare)
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Buried alive - Germination of up to a century-old marine protist resting stages
- 2011
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Ingår i: Phycologia. - : Informa UK Limited. - 0031-8884 .- 2330-2968. ; 50:6, s. 629-640
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Tidskriftsartikel (refereegranskat)abstract
- report on the survival and germination of up to a century-old marine protist resting stages naturally preserved insediments from Koljö Fjord on the west coast of Sweden. This work has focused on germination of dinoflagellate cysts,but diatom resting stages were also observed. We record the longest known survival of dormant dinoflagellate cells. Weindividually isolated more than 1200 cysts of the three most abundant dinoflagellate taxa: Pentapharsodinium dalei,Lingulodinium polyedrum and Scrippsiella spp. Germination success decreased with core depth, and all successfulgerminations took place within the first 2 wk of incubation. Pentapharsodinium dalei had the highest germination successrate, with a maximum of up to 80% in 28-yr-old sediment, and could successfully germinate from core sediments datedto 1920 ± 12. Scrippsiella spp. cysts with cell contents occurred down to c. 90-yr-old sediment and could germinate fromdown to ca. 40-yr-old sediments, with a maximum germination rate of 50-60% in recent sediments. Cysts of L.polyedrum germinated frequently down to 20 yr and rarely to c. 80 yr, with a maximum of 20-50% germination successin recent sediments. Cyst isolation under cooled conditions rather than at room temperature resulted in a significantlyhigher germination success in P. dalei, while no effect was observed for L. polyedrum. The time elapsed since slicing ofthe core affected survival of L. polyedrum cysts negatively, most likely due to the effect of oxygen. The long-termsurvival potential of benthic resting stages that we report here has important implications, as viable resting stagesaccumulated in bottom sediments can be transported back to the water column by, for example, bioturbation andhuman-mediated sediment dredging. Hence, the sediment may to a higher degree than previously considered play a roleas seed bank. This is important in a changing climate and might have particularly severe impacts in the case of harmful species.
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| 6. |
- Scheel, Maria, et al.
(författare)
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Abrupt permafrost thaw triggers activity of copiotrophs and microbiome predators
- 2023
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Ingår i: FEMS Microbiology Ecology. - 0168-6496 .- 1574-6941. ; 99:11
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Tidskriftsartikel (refereegranskat)abstract
- Permafrost soils store a substantial part of the global soil carbon and nitrogen. However, global warming causes abrupt erosion and gradual thaw, which make these stocks vulnerable to microbial decomposition into greenhouse gases. Here, we investigated the microbial response to abrupt in situ permafrost thaw. We sequenced the total RNA of a 1 m deep soil core consisting of up to 26 500-year-old permafrost material from an active abrupt erosion site. We analysed the microbial community in the active layer soil, the recently thawed, and the intact permafrost, and found maximum RNA:DNA ratios in recently thawed permafrost indicating a high microbial activity. In thawed permafrost, potentially copiotrophic Burkholderiales and Sphingobacteriales, but also microbiome predators dominated the community. Overall, both thaw-dependent and long-term soil properties significantly correlated with changes in community composition, as did microbiome predator abundance. Bacterial predators were dominated in shallower depths by Myxococcota, while protozoa, especially Cercozoa and Ciliophora, almost tripled in relative abundance in thawed layers. Our findings highlight the ecological importance of a diverse interkingdom and active microbial community highly abundant in abruptly thawing permafrost, as well as predation as potential biological control mechanism. Using total RNA from an up to 26 500-year-old abruptly eroding permafrost site in Greenland, we described increased microbial activity and its controls, including thaw and microbiome predator abundance.
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