Abstract
Long-term memory formation (LTM) is a process accompanied by energy-demanding structural changes at synapses and increased spine density. Concomitant increases in both spine volume and ...postsynaptic density (PSD) surface area have been suggested but never quantified in vivo by clear-cut experimental evidence. Using novel object recognition in mice as a learning task followed by 3D electron microscopy analysis, we demonstrate that LTM induced all aforementioned synaptic changes, together with an increase in the size of astrocytic glycogen granules, which are a source of lactate for neurons. The selective inhibition of glycogen metabolism in astrocytes impaired learning, affecting all the related synaptic changes. Intrahippocampal administration of l-lactate rescued the behavioral phenotype, along with spine density within 24 hours. Spine dynamics in hippocampal organotypic slices undergoing theta burst-induced long-term potentiation was similarly affected by inhibition of glycogen metabolism and rescued by l-lactate. These results suggest that learning primes astrocytic energy stores and signaling to sustain synaptic plasticity via l-lactate.
Determining the structural properties of mRNA is key to understanding vital post-transcriptional processes. As experimental data on mRNA structure are scarce, accurate structure prediction is ...required to characterize RNA regulatory mechanisms. Although various structure prediction approaches are available, it is often unclear which to choose and how to set their parameters. Furthermore, no standard measure to compare predictions of local structure exists. We assessed the performance of different methods using two types of data: transcriptome-wide enzymatic probing information and a large, curated set of cis-regulatory elements. To compare the approaches, we introduced structure accuracy, a measure that is applicable to both global and local methods. Our results showed that local folding was more accurate than the classic global approach. We investigated how the locality parameters, maximum base pair span and window size, influenced the prediction performance. A span of 150 provided a reasonable balance between maximizing the number of accurately predicted base pairs, while minimizing effects of incorrect long-range predictions. We characterized the error at artificial sequence ends, which we reduced by setting the window size sufficiently greater than the maximum span. Our method, LocalFold, diminished all border effects and produced the most robust performance.
The Eurasian genotype of common reed Phragmites australis subsp. australis is rapidly invading freshwater marshes in North America. Several bird species depend upon particular plant assemblages for ...feeding and reproduction and could be adversely affected by the expansion of this invader. The objective of this study was to evaluate the effect of common reed on the abundance, richness, diversity and site occupancy of bird assemblages in freshwater marshes recently invaded by the plant (southern Quebec, Canada). We conducted fixed‐distance point counts for songbirds (passerines and rails) and visual surveys for waterbirds (ducks, geese and waders) during two nesting seasons (2009 and 2010). There were major structural differences between common reed stands and marsh vegetation assemblages dominated by other plant species (bulrushes, cattails, sedges). However, there was a little difference in abundance, richness, diversity and site occupancy for songbirds. Marsh wren Cistothorus palustris, a wetland specialist, was the only nesting bird that preferred a native plant (cattail) over common reed, probably because common reed stands have low plant diversity and few appropriate nest materials. No major differences were observed in the abundance of waterbirds between invaded and non‐invaded marshes. For most bird species, the water depth of the marsh had more influence on the abundance of individuals and on site occupancy than the composition of the plant assemblage. Common reed stands can therefore be used by generalist and specialist marsh passerines as feeding and reproduction sites. However, it is possible that in southern Quebec, the number and extent of common reed populations have not yet reached a threshold beyond which adverse effects of the invader on avian species could be significant. This study adds to a growing body of evidence showing that the relationship between invasive plants and birds is not straightforward.
A thin phase-shifting surface is described that consists of three metallic and two dielectric layers. The metallic layers consist of conducting shapes, which are tuned to introduce the desired phase ...shift on an incident wave, while maintaining a very high amplitude of transmission coefficient. Such a quasi-transparent surface is then applied to phase-correcting devices and their operation validated experimentally.
We describe the progress in the international coordination of long-range forecasting fostered by the World Meteorological Organisation (WMO), specifically for the seasonal to interannual timescale. ...Coordination has been achieved through the creation of new infrastructure, notably 11 Global Producing Centres (GPCs) for long-range forecasts, and definition of operational standards in forecast output and associated material. Examples discussed show improvements to the integration, usefulness and operational delivery of long-range forecast products to the world-wide climate community. Products are in wide use, and cover both predictive information, up to 6 mo ahead, and verification information indicating forecast quality. Proposals for future expansions of the role of GPCs are discussed, with a view to addressing the challenges presented by the development of the Global Framework for Climate Services. In particular, implementation of regular WMO-coordinated Global Seasonal Climate Updates is proposed, to provide authoritative, readily accessible advice on the state of the global climate and prospects for the next season. In addition we argue that the skill benefits provided by decadal-range predictions initialised with the observed climate state, relative to uninitialised (IPCC-type) predictions, are sufficient to begin similar international coordination in multiannual-to-decadal prediction, through extending the role of those GPCs that are developing decadal-prediction capability.
In this study, the influence of the probiotics, Pediococcus acidilactici (PA) and Saccharomyces cerevisiae boulardii (SCB), on intestinal immune traits and resistance to enterotoxigenic Escherichia ...coli (ETEC) infection was evaluated in pigs. Two weeks before farrowing, 30 sows and their future litters were allocated to the following treatments: 1) control group without antibiotic or probiotic treatment (CTRL), 2) control with antibiotic (tiamulin) added to weanling feed (ABT), or litters treated with 3) PA, 4) SCB, or 5) PA+SCB from 24 h after birth. During lactation, PA, SCB, or PA+SCB were given to piglets 3 times a week by gavage. After weaning at 21 d of age, probiotics or ABT were added to the diet. Four pigs per litter were chosen to evaluate performance and blood concentrations of folic acid and vitamin B₁₂. Three of these were orally challenged with an ETEC strain on d 49 to 51 and killed on d 52. Three piglets from the rest of the litter were slaughtered on d 18 and 3 others on d 24. Blood, ileum, and mesenteric lymph node (MLN) samples were taken to characterize leukocyte populations, determine IgA concentrations in ileal flushes, and evaluate bacterial translocation in MLN. No treatment effect on postweaning performance and on blood concentrations of folic acid and vitamin B₁₂ was observed. In the ileum, the percentage of CD4⁻CD8⁺low T cells was greater (P = 0.05) in 18-d-old nursed piglets treated with PA than in those of the CTRL and PA+SCB groups. In the MLN, the percentage of CD8⁺ T cells was not affected by any of the treatments at d 18 and 24 but decreased (P = 0.006) after weaning. In the blood, CD8⁺ T cells were not affected by treatments or weaning. After the ETEC challenge (d 52), bacterial translocation to MLN was reduced (P = 0.05) in pigs treated with PA, SCB, PA+SCB, or ABT compared with CTRL. No treatment effect was observed on blood leukocyte populations after ETEC challenge, although a time effect (d 42 vs. 52) indicated that blood CD4⁺ and γδ-T lymphocytes were increased (P < 0.05) on d 52 compared with d 42, whereas CD4⁻CD8⁺low T lymphocytes and monocytes were markedly reduced (P < 0.01). Finally, the IgA concentration in ileal flushes collected on d 42 and 52 was greater in SCB and CTRL piglets than in ABT and PA piglets. In conclusion, probiotics may have the potential to modulate establishment of lymphocyte populations and IgA secretion in the gut and to reduce bacterial translocation to MLN after ETEC infection.
The bacterial and archaeal CRISPR/Cas adaptive immune system targets specific protospacer nucleotide sequences in invading organisms. This requires base pairing between processed CRISPR RNA and the ...target protospacer. For type I and II CRISPR/Cas systems, protospacer adjacent motifs (PAM) are essential for target recognition, and for type III, mismatches in the flanking sequences are important in the antiviral response. In this study, we examine the properties of each class of CRISPR. We use this information to provide a tool (CRISPRTarget) that predicts the most likely targets of CRISPR RNAs (
http://bioanalysis.otago.ac.nz/CRISPRTarget
). This can be used to discover targets in newly sequenced genomic or metagenomic data. To test its utility, we discover features and targets of well-characterized Streptococcus thermophilus and Sulfolobus solfataricus type II and III CRISPR/Cas systems. Finally, in Pectobacterium species, we identify new CRISPR targets and propose a model of temperate phage exposure and subsequent inhibition by the type I CRISPR/Cas systems.
Four ruminally lactating Holstein cows averaging 602+/-25 kg of body weight and 64+/-6 d in milk at the beginning of the experiment were randomly assigned to a 4 x 4 Latin square design to determine ...the effects of feeding whole flaxseed and calcium salts of flaxseed oil on dry matter intake, digestibility, ruminal fermentation, milk production and composition, and milk fatty acid profile. The treatments were a control with no flaxseed products (CON) or a diet (on a dry matter basis) of 4.2% whole flaxseed (FLA), 1.9% calcium salts of flaxseed oil (SAL), or 2.3% whole flaxseed and 0.8% calcium salts of flaxseed oil (MIX). The 4 isonitrogenous and isoenergetic diets were fed for ad libitum intake. Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection and sampling. Dry matter intake, digestibility, milk production, and milk concentrations of protein, lactose, urea N, and total solids did not differ among treatments. Ruminal pH was reduced for cows fed the CON diet compared with those fed the SAL diet. Propionate proportion was higher in ruminal fluid of cows fed CON than in that of those fed SAL, and cows fed the SAL and CON diets had ruminal propionate concentrations similar to those of cows fed the FLA and MIX diets. Butyrate concentration was numerically higher for cows fed the SAL diet compared with those fed the FLA diet. Milk fat concentration was lower for cows fed SAL than for those fed CON, and there was no difference between cows fed CON and those fed FLA and MIX. Milk yields of protein, fat, lactose, and total solids were similar among treatments. Concentrations of cis-9 18:1 and of intermediates of ruminal biohydrogenation of fatty acids such as trans-9 18:1 were higher in milk fat of cows fed SAL and MIX than for those fed the CON diet. Concentration of rumenic acid (cis-9, trans-11 18:2) in milk fat was increased by 63% when feeding SAL compared with FLA. Concentration of alpha-linolenic acid was higher in milk fat of cows fed SAL and MIX than in milk of cows fed CON (75 and 61%, respectively), whereas there was no difference between FLA and CON. Flaxseed products (FLA, SAL, and MIX diets) decreased the n-6 to n-3 fatty acid ratio in milk fat. Results confirm that flax products supplying 0.7 to 1.4% supplemental fat in the diet can slightly improve the nutritive value of milk fat for better human health.
PDF
