Metabarcoding of lake sediments have been shown to 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 of 47 plant taxa in the 11 lakes, 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 may 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.
Nucleotide analog inhibitors have shown clinical success in the treatment of hepatitis C virus (HCV) infection, despite an incomplete mechanistic understanding of NS5B, the viral RNA-dependent RNA ...polymerase. Here we study the details of HCV RNA replication by determining crystal structures of stalled polymerase ternary complexes with enzymes, RNA templates, RNA primers, incoming nucleotides, and catalytic metal ions during both primed initiation and elongation of RNA synthesis. Our analysis revealed that highly conserved active-site residues in NS5B position the primer for in-line attack on the incoming nucleotide. A β loop and a C-terminal membrane–anchoring linker occlude the active-site cavity in the apo state, retract in the primed initiation assembly to enforce replication of the HCV genome from the 3′ terminus, and vacate the active-site cavity during elongation. We investigated the incorporation of nucleotide analog inhibitors, including the clinically active metabolite formed by sofosbuvir, to elucidate key molecular interactions in the active site.
The timing of the seasonal freeze-thaw cycle of arctic lakes affects ecological processes and land-atmosphere energy fluxes. We carried out detailed ice-phenology mapping of arctic lakes, based on ...daily surface-reflectance time series for 2000-2013 from MODIS at 250 m spatial resolution. We used over 13,300 lakes, area >1 km
, in five study areas distributed evenly across the circumpolar Arctic - the first such phenological dataset. All areas showed significant trends towards an earlier break-up, stronger than previously reported. The mean shift in break-up start ranged from -0.10 days/year (Northern Europe) to -1.05 days/year (central Siberia); the shift in break-up end was between -0.14 and -0.72 days/year. Finally, we explored the effect of temperature on break-up timing and compared results among study areas. The 0 °C isotherm shows the strongest relationship (r = 0.56-0.81) in all study areas. If the trend in early break-up continues, rapidly changing ice phenology will likely generate significant, arctic-wide impacts.
The benefits and safety of the treatment of mild chronic hypertension (blood pressure, <160/100 mm Hg) during pregnancy are uncertain. Data are needed on whether a strategy of targeting a blood ...pressure of less than 140/90 mm Hg reduces the incidence of adverse pregnancy outcomes without compromising fetal growth.
In this open-label, multicenter, randomized trial, we assigned pregnant women with mild chronic hypertension and singleton fetuses at a gestational age of less than 23 weeks to receive antihypertensive medications recommended for use in pregnancy (active-treatment group) or to receive no such treatment unless severe hypertension (systolic pressure, ≥160 mm Hg; or diastolic pressure, ≥105 mm Hg) developed (control group). The primary outcome was a composite of preeclampsia with severe features, medically indicated preterm birth at less than 35 weeks' gestation, placental abruption, or fetal or neonatal death. The safety outcome was small-for-gestational-age birth weight below the 10th percentile for gestational age. Secondary outcomes included composites of serious neonatal or maternal complications, preeclampsia, and preterm birth.
A total of 2408 women were enrolled in the trial. The incidence of a primary-outcome event was lower in the active-treatment group than in the control group (30.2% vs. 37.0%), for an adjusted risk ratio of 0.82 (95% confidence interval CI, 0.74 to 0.92; P<0.001). The percentage of small-for-gestational-age birth weights below the 10th percentile was 11.2% in the active-treatment group and 10.4% in the control group (adjusted risk ratio, 1.04; 95% CI, 0.82 to 1.31; P = 0.76). The incidence of serious maternal complications was 2.1% and 2.8%, respectively (risk ratio, 0.75; 95% CI, 0.45 to 1.26), and the incidence of severe neonatal complications was 2.0% and 2.6% (risk ratio, 0.77; 95% CI, 0.45 to 1.30). The incidence of any preeclampsia in the two groups was 24.4% and 31.1%, respectively (risk ratio, 0.79; 95% CI, 0.69 to 0.89), and the incidence of preterm birth was 27.5% and 31.4% (risk ratio, 0.87; 95% CI, 0.77 to 0.99).
In pregnant women with mild chronic hypertension, a strategy of targeting a blood pressure of less than 140/90 mm Hg was associated with better pregnancy outcomes than a strategy of reserving treatment only for severe hypertension, with no increase in the risk of small-for-gestational-age birth weight. (Funded by the National Heart, Lung, and Blood Institute; CHAP ClinicalTrials.gov number, NCT02299414.).
The Perinatal Quality Foundation and the American College of Medical Genetics and Genomics, in association with the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal ...Medicine, and the National Society of Genetic Counselors, have collaborated to provide education for clinicians and laboratories regarding the use of expanded genetic carrier screening in reproductive medicine. This statement does not replace current screening guidelines, which are published by individual organizations to direct the practice of their constituents. As organizations develop practice guidelines for expanded carrier screening, further direction is likely. The current statement demonstrates an approach for health care providers and laboratories who wish to or who are currently offering expanded carrier screening to their patients.
Sedimentary DNA (sedDNA) has recently emerged as a new proxy for reconstructing past vegetation, but its taphonomy, source area and representation biases need better assessment. We investigated how ...sedDNA in recent sediments of two small Scottish lakes reflects a major vegetation change, using well-documented 20th Century plantations of exotic conifers as an experimental system.
We used next-generation sequencing to barcode sedDNA retrieved from subrecent lake sediments. For comparison, pollen was analysed from the same samples.
The sedDNA record contains 73 taxa (mainly genus or species), all but one of which are present in the study area. Pollen and sedDNA shared 35% of taxa, which partly reflects a difference in source area. More aquatic taxa were recorded in sedDNA, whereas taxa assumed to be of regional rather than local origin were recorded only as pollen.
The chronology of the sediments and planting records are well aligned, and sedDNA of exotic conifers appears in high quantities with the establishment of plantations around the lakes. SedDNA recorded other changes in local vegetation that accompanied afforestation. There were no signs of DNA leaching in the sediments or DNA originating from pollen.
Background. Group A rotaviruses (RVA) are a significant cause of pediatric gastroenteritis worldwide. The New Vaccine Surveillance Network (NVSN) has conducted active surveillance for RVA at ...pediatrie hospitals and emergency departments at 3-7 geographically diverse sites in the United States since 2006. Methods. Over 6 consecutive years, from 2008 to 2013, 1523 samples from NVSN sites that were tested positive by a Rotaclone enzyme immunoassay were submitted to the Centers for Disease Control and Prevention for genotyping. Results. In the 2009, 2010, and 2011 seasons, genotype G3P8 was the predominant genotype throughout the network, with a 46%-84% prevalence. In the 2012 season, G12P8 replaced G3P8 as the most common genotype, with a 70% prevalence, and this trend persisted in 2013 (68.0% prevalence). Vaccine (RotaTeq; Rotarix) strains were detected in 0.6%-3.4% of genotyped samples each season. Uncommon and unusual strains (eg, G8P4, G3P24, G2P8, G3P4, G3P6, G24P14, G4P6, and G9P4) were detected sporadically over the study period. Year, study site, and race were found to be significant predictors of genotype. Conclusions. Continued active surveillance is needed to monitor RVA genotypes in the United States and to detect potential changes since vaccine licensure.
The collapse of the steppe-tundra biome (mammoth steppe) at the end of the Pleistocene is used as an important example of top-down ecosystem cascades, where human hunting of keystone species led to ...profound changes in vegetation across high latitudes in the Northern Hemisphere. Alternatively, it is argued that this biome transformation occurred through a bottom-up process, where climate-driven expansion of shrub tundra (
,
spp.) replaced the steppe-tundra vegetation that grazing megafauna taxa relied on. In eastern Beringia, these differing hypotheses remain largely untested, in part because the precise timing and spatial pattern of Late Pleistocene shrub expansion remains poorly resolved. This uncertainty is caused by chronological ambiguity in many lake sediment records, which typically rely on radiocarbon (
C) dates from bulk sediment or aquatic macrofossils-materials that are known to overestimate the age of sediment layers. Here, we reexamine Late Pleistocene pollen records for which
C dating of terrestrial macrofossils is available and augment these data with
C dates from arctic ground-squirrel middens and plant macrofossils. Comparing these paleovegetation data with a database of published
C dates from megafauna remains, we find the postglacial expansion of shrub tundra preceded the regional extinctions of horse (
spp.) and mammoth (
) and began during a period when the frequency of
C dates indicates large grazers were abundant. These results are not consistent with a model of top-down ecosystem cascades and support the hypothesis that climate-driven habitat loss preceded and contributed to turnover in mammal communities.
In recent years, there has been an increased interest in injectable, in situ crosslinking hydrogels due to their minimally invasive application and ability to conform to their environment. Current in ...situ crosslinking chitosan hydrogels are either mechanically robust with poor biocompatibility and limited biodegradation due to toxic crosslinking agents or the hydrogels are mechanically weak and undergo biodegradation too rapidly due to insufficient crosslinking. Herein, the authors developed and characterized a thermally‐driven, injectable chitosan‐genipin hydrogel capable of in situ crosslinking at 37 °C that is mechanically robust, biodegradable, and maintain high biocompatibility. The natural crosslinker genipin is utilized as a thermally‐driven, non‐toxic crosslinking agent. The chitosan‐genipin hydrogel's crosslinking kinetics, injectability, viscoelasticity, swelling and pH response, and biocompatibility against human keratinocyte cells are characterized. The developed chitosan‐genipin hydrogels are successfully crosslinked at 37 °C, demonstrating temperature sensitivity. The hydrogels maintained a high percentage of swelling over several weeks before degrading in biologically relevant environments, demonstrating mechanical stability while remaining biodegradable. Long‐term cell viability studies demonstrated that chitosan‐genipin hydrogels have excellent biocompatibility over 7 days, including during the hydrogel crosslinking phase. Overall, these findings support the development of an injectable, in situ crosslinking chitosan‐genipin hydrogel for minimally invasive biomedical applications.
This paper presents the development and characterization of an injectable chitosan‐genipin hydrogel capable of in situ crosslinking at 37 °C that is mechanically robust, biodegradable, and maintained high biocompatibility. The hydrogel's crosslinking kinetics, injectability, viscoelasticity, swelling and pH response, and biocompatibility are characterized. Findings support the development of an injectable chitosan‐genipin hydrogel for minimally invasive biomedical applications.
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