The honeybee is the primary managed species worldwide for both crop pollination and honey production. Owing to beekeeping activity, its high relative abundance potentially affects the structure and ...functioning of pollination networks in natural ecosystems. Given that evidences about beekeeping impacts are restricted to observational studies of specific species and theoretical simulations, we still lack experimental data to test for their larger-scale impacts on biodiversity. Here we used a three-year field experiment in a natural ecosystem to compare the effects of pre- and post-establishment stages of beehives on the pollination network structure and plant reproductive success. Our results show that beekeeping reduces the diversity of wild pollinators and interaction links in the pollination networks. It disrupts their hierarchical structural organization causing the loss of interactions by generalist species, and also impairs pollination services by wild pollinators through reducing the reproductive success of those plant species highly visited by honeybees. High-density beekeeping in natural areas appears to have lasting, more serious negative impacts on biodiversity than was previously assumed.
Polymer identification of plastic marine debris can help identify its sources, degradation, and fate. We optimized and validated a fast, simple, and accessible technique, attenuated total reflectance ...Fourier transform infrared spectroscopy (ATR FT-IR), to identify polymers contained in plastic ingested by sea turtles. Spectra of consumer good items with known resin identification codes #1–6 and several #7 plastics were compared to standard and raw manufactured polymers. High temperature size exclusion chromatography measurements confirmed ATR FT-IR could differentiate these polymers. High-density (HDPE) and low-density polyethylene (LDPE) discrimination is challenging but a clear step-by-step guide is provided that identified 78% of ingested PE samples. The optimal cleaning methods consisted of wiping ingested pieces with water or cutting. Of 828 ingested plastics pieces from 50 Pacific sea turtles, 96% were identified by ATR FT-IR as HDPE, LDPE, unknown PE, polypropylene (PP), PE and PP mixtures, polystyrene, polyvinyl chloride, and nylon.
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•We validate ATR FT-IR to identify polymers of weathered and ingested plastics.•We outline criteria to differentiate HDPE from LDPE samples.•Cutting or cleaning ingested plastics with water improves identification.•A database of standards is not required for polymer identification.•Collaborations of life and materials sciences address plastic debris issues.
Objective
To investigate the association of maternal circulating 25‐hydroxyvitamin D3 25(OH)D3 concentration with pregnancy and birth outcomes.
Design
Prospective cohort study.
Setting
Four ...geographical areas of Spain, 2003–2008.
Population
Of 2382 mother–child pairs participating in the INfancia y Medio Ambiente (INMA) Project.
Methods
Maternal circulating 25(OH)D3 concentration was measured in pregnancy (mean SD 13.5 2.2 weeks of gestation). We tested associations of maternal 25(OH)D3 concentration with pregnancy and birth outcomes.
Main outcome measures
Gestational diabetes mellitus (GDM), preterm delivery, caesarean section, fetal growth restriction (FGR) and small‐for‐gestational age (SGA), anthropometric birth outcomes including weight, length and head circumference (HC).
Results
Overall, 31.8% and 19.7% of women had vitamin D insufficiency 25(OH)D3 20–29.99 ng/ml and deficiency 25(OH)D3 < 20 ng/ml, respectively. After adjustment, there was no association between maternal 25(OH)D3 concentration and risk of GDM or preterm delivery. Women with sufficient vitamin D 25(OH)D3 ≥ 30 ng/ml had a decreased risk of caesarean section by obstructed labour compared with women with vitamin D deficiency relative risk (RR) = 0.60, 95% CI 0.37, 0.97). Offspring of mothers with higher circulating 25(OH)D3 concentration tended to have smaller HC coefficient (SE) per doubling concentration of 25(OH)D3, −0.10 (0.05), P = 0.038. No significant associations were found for other birth outcomes.
Conclusion
This study did not find any evidence of an association between vitamin D status in pregnancy and GDM, preterm delivery, FGR, SGA and anthropometric birth outcomes. Results suggest that sufficient circulating vitamin D concentration 25(OH)D3 ≥ 30 ng/ml in pregnancy may reduce the risk of caesarean section by obstructed labour.
Summary
The composition of ecologically important moss‐associated bacterial communities seems to be mainly driven by host species but may also be shaped by environmental conditions related with tree ...dominance. The moss phyllosphere has been studied in coniferous forests while broadleaf forests remain understudied. To determine if host species or environmental conditions defined by tree dominance drives the bacterial diversity in the moss phyllosphere, we used 16S rRNA gene amplicon sequencing to quantify changes in bacterial communities as a function of host species (Pleurozium schreberi and Ptilium crista‐castrensis) and forest type (coniferous black spruce versus deciduous broadleaf trembling aspen) in eastern Canada. The overall composition of moss phyllosphere was defined by the interaction of both factors, though most of the bacterial phyla were determined by a strong effect of forest type. Bacterial α‐diversity was highest in spruce forests, while there was greater turnover (β‐diversity) and higher γ‐diversity in aspen forests. Unexpectedly, Cyanobacteria were much more relatively abundant in aspen than in spruce forests, with the cyanobacteria family Nostocaceae differing the most between forest types. Our results advance the understanding of moss‐associated microbial communities among coniferous and broadleaf deciduous forests, which are important with the increasing changes in tree dominance in the boreal system.
Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and ...opportunistic nectarfeeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores. Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird—lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds). The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services.
Adaptation of malignant cells to the hostile milieu present in tumors is an important determinant of their survival and growth. However, the interaction between tumor-linked stress and antitumor ...immunity remains poorly characterized. Here, we show the critical role of the cellular stress sensor C/EBP-homologous protein (Chop) in the accumulation and immune inhibitory activity of tumor-infiltrating myeloid-derived suppressor cells (MDSCs). MDSCs lacking Chop had decreased immune-regulatory functions and showed the ability to prime T cell function and induce antitumor responses. Chop expression in MDSCs was induced by tumor-linked reactive oxygen and nitrogen species and regulated by the activating-transcription factor-4. Chop-deficient MDSCs displayed reduced signaling through CCAAT/enhancer-binding protein-β, leading to a decreased production of interleukin-6 (IL-6) and low expression of phospho-STAT3. IL-6 overexpression restored immune-suppressive activity of Chop-deficient MDSCs. These findings suggest the role of Chop in tumor-induced tolerance and the therapeutic potential of targeting Chop in MDSCs for cancer immunotherapy.
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•Chop regulates immune-suppressive activity and accumulation of MDSCs in tumors•Deletion of Chop in tumor stroma leads to effective antitumor T cell immunity•Reactive oxygen and nitrogen species in tumors trigger Chop in MDSCs through Atf4•Stromal cell Chop promotes MDSC activity through induction of C/EBPβ-IL-6 axis
Very little is known about the interaction between tumor-linked cellular stress and antitumor immunity. Rodriguez and colleagues demonstrate an essential role for the stress-response sensor Chop in regulating the inhibitory function and accumulation of myeloid-derived suppressor cells in tumors.
The strength of synaptic transmission is controlled by the number and activity of neurotransmitter receptors. However, little is known about absolute numbers and densities of receptor and scaffold ...proteins and the stoichiometry of molecular interactions at synapses. Here, we conducted three-dimensional and quantitative nanoscopic imaging based on single-molecule detections to characterize the ultrastructure of inhibitory synapses and to count scaffold proteins and receptor binding sites. We observed a close correspondence between the spatial organization of gephyrin scaffolds and glycine receptors at spinal cord synapses. Endogenous gephyrin was clustered at densities of 5,000–10,000 molecules/μm2. The stoichiometry between gephyrin molecules and receptor binding sites was approximately 1:1, consistent with a two-dimensional scaffold in which all gephyrin molecules can contribute to receptor binding. The competition of glycine and GABAA receptor complexes for synaptic binding sites highlights the potential of single-molecule imaging to quantify synaptic plasticity on the nanoscopic scale.
•Molecule counting using quantitative single-fluorophore imaging•Dual-color three-dimensional PALM/STORM using adaptive optics•Number and density of gephyrin scaffolds at inhibitory PSDs•Topology and density of receptor binding sites at inhibitory synapses
The molecular organization of synapses regulates the efficacy of synaptic transmission. However, little is known about the absolute protein numbers at synapses. Specht et al. implement single-molecule imaging to count synaptic scaffold proteins and receptor binding sites.
Parkinson's disease is a neurodegenerative process characterized by numerous motor and nonmotor clinical manifestations for which effective, mechanism-based treatments remain elusive. Here we discuss ...a series of critical issues that we think researchers need to address to stand a better chance of solving the different challenges posed by this pathology.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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