Changing Dietary Calcium-Phosphorus Level and Cereal Source Selectively Alters Abundance of Bacteria and Metabolites in the Upper Gastrointestinal Tracts of Weaned Pigs

Several dietary ingredients may affect the bacterial community structure and metabolism in the porcine gut and may therefore influence animals'' health and performance. This study investigated the effects of cereal source and calcium-phosphorus (CaP) level in the diet on bacterial microbiota and metabolites, nutrient intake, and gut environment in weaned pigs. Pigs (n = 8/treatment) were fed wheat-barley- or corn-based diets with an adequate or high CaP level for 14 days. Effects on microbiota in the stomach, ileum, and midcolon were assessed using quantitative PCR. Data showed that Enterobacteriaceae, Campylobacter spp., and Helicobacter spp., which all contain highly immune reactive lipopolysaccharide (LPS), were abundant at all gut sites. Diet effects on bacteria and metabolites were moderate and occurred mainly in the upper gut, whereas no effects on bacteria, fermentation products, and LPS could be observed in the colon. Differences in carbohydrate intake with corn versus wheat-barley diets selectively stimulated Bifidobacterium in the stomach and ileum. There was a growth advantage for a few bacterial groups in the stomach and ileum of pigs fed the high versus adequate CaP level (i.e., gastric Enterobacteriaceae and ileal Enterococcus, Bacteroides-Prevotella-Porphyromonas, and Campylobacter). Interestingly, gastrointestinal pH was not affected by dietary CaP level. The present findings demonstrate the stability of the bacterial community and gut environment toward dietary changes even in young pigs. The results on stimulation of gastric and ileal Bifidobacterium by corn diets may be employed in nutritional strategies to support gut health after weaning.     

The impact of nandrolone decanoate and growth hormone on biosynthesis of steroids in rats

Growth hormone (GH) and anabolic androgenic steroids (AAS) are commonly used in sports communities. Several studies have suggested an association between GH and AAS. We have investigated the impact of GH in rats treated with nandrolone decanoate (ND). Male Wistar rats received ND (15 mg/kg) every third day during three weeks and were subsequently treated with recombinant human GH (1.0 IU/kg) for ten consecutive days. Plasma samples were collected and peripheral organs (i.e. heart, liver, testis and thymus) were dissected and weighed. Concentration of thirteen endogenous steroids was measured in the rat plasma samples using high specificity LC–MS/MS methods. Seven steroids were detected and quantified, and concentrations of estrone, testosterone, and androstenedione were significantly different among the groups, while concentrations of pregnenolone, DHEA, 17-hydroxyprogesterone and corticosterone were not altered. Administration of rhGH alone altered the plasma steroid distribution, and the results demonstrated significantly increased concentrations of plasma estrone as well as decreased concentrations of testosterone and androstenedione in the ND-treated rats. Administration of rhGH to ND-pretreated rats did not reverse the alteration of the steroid distribution induced by ND. Administration of ND decreased the weight of the thymus, and addition of rhGH did not reverse this reduction. However, rhGH administration induced an enlargement of thymus. Taken together, the plasma steroid profile differed in the four groups, i.e. control, AAS, rhGH and the combination of AAS and rhGH treatment.     

Negative Effects of Conspecific Floral Density on Fruit Set of Two Neotropical Understory Plants

Plant reproductive success is usually positively related to conspecific floral density, but neutral or negative effects of floral density on reproduction have also been reported. Differences in the relationship between reproduction and floral density largely originate from a trade‐off between increasing attractiveness versus increasing competition for pollinators at high floral densities. Although floral densities strongly vary in the understory of tropical forests, for instance, due to variation in light availability, little is known about the density dependence of reproduction in tropical understory plants. We used path analyses to disentangle direct and indirect effects of canopy openness and floral density on fruit set and analyzed the relationship between pollen load and floral density for two Neotropical understory plants, Heliconia metallica and Besleria melancholica. In both species, fruit set was not directly related to canopy openness, but decreased with increasing floral density. In H. metallica, canopy openness had an indirect negative effect on reproduction mediated by its effects on floral density. Effects of floral density on pollen loads were species‐specific. In B. melancholica, pollen loads linearly decreased with increasing floral density, indicating competition for pollinators at high densities. In H. metallica, pollen loads were reduced at both low and high densities, indicating an interplay of facilitative and competitive effects of floral density on pollen deposition. In contrast to other studies, we found negative density dependence of reproduction in both understory species. Negative effects of floral density on reproduction appear to be related to pollinator‐mediated effects on reproduction rather than to variation in abiotic conditions.     

Synthesis and evaluation of a 125I-labeled iminodihydroquinoline-derived tracer for imaging of voltage-gated sodium channels

In vivo imaging of voltage-gated sodium channels (VGSCs) can potentially provide insights into the activation of neuronal pathways and aid the diagnosis of a number of neurological diseases. The iminodihydroquinoline WIN17317-3 is one of the most potent sodium channel blockers reported to date and binds with high affinity to VGSCs throughout the rat brain. We have synthesized a ¹²⁵I-labeled analogue of WIN17317-3 and evaluated the potential of the tracer for imaging of VGSCs with SPECT. Automated patch clamp studies with CHO cells expressing the Na_v1.2 isoform and displacement studies with [³H]BTX yielded comparable results for the non-radioactive iodinated iminodihydroquinoline and WIN17317-3. However, the ¹²⁵I-labeled tracer was rapidly metabolized in vivo, and suffered from low brain uptake and high accumulation of radioactivity in the intestines. The results suggest that iminodihydroquinolines are poorly suited for tracer development.     

Synthesis and biological evaluation of potential threonine synthase inhibitors: Rhizocticin A and Plumbemycin A

Rhizocticins and Plumbemycins are natural phosphonate antibiotics produced by the bacterial strains Bacillus subtilis ATCC 6633 and Streptomyces plumbeus, respectively. Up to now, these potential threonine synthase inhibitors have only been synthesized under enzymatic catalysis. Here we report the chemical stereoselective synthesis of the non-proteinogenic (S,Z)-2-amino-5-phosphonopent-3-enoic acid [(S,Z)-APPA] and its use for the synthesis of Rhizocticin A and Plumbemycin A. In this work, (S,Z)-APPA was synthesized via the Still–Gennari olefination starting from Garner’s aldehyde. The Michaelis–Arbuzov reaction was used to form the phosphorus–carbon bond. Oligopeptides were prepared using liquid phase peptide synthesis (LPPS) and were tested against selected bacteria and fungi.     

Inferring the ecology of willow warblers during their winter moult by sequential stable isotope analyses of remiges

We present a comparison of feather stable isotope (δ¹³C, δ¹⁵N) patterns representing the habitat and diet conditions for two subspecies of willow warblers Phylloscopus trochilus that breed in parapatry, but winter in different regions of sub‐Saharan Africa. Previous analyses have shown that on average winter moulted innermost primaries (P1) show subspecific differences in δ¹⁵N values, although individuals show substantial variation for both δ¹³C and δ¹⁵N within the subspecies. We examined whether corresponding variation in the timing of the winter moult, as reflected by consistent intra‐wing correlations for individual's δ¹³C and δ¹⁵N values, could explain some of the previously observed isotopic variation. Further, differential subspecific adaptations to winter precipitation patterns across Africa might result in a variable degree of site fidelity or itinerancy during moult. We found no consistent trend in isotopic values from innermost to outermost primaries, thus inter‐individual variation in the timing of moult does not explain the subspecific isotopic variation for P1. Patterns in wing feather δ¹³C and δ¹⁵N values indicated that 41% of the individuals from both subspecies shifted their diet or habitats during winter moult. Importantly, despite well‐documented itinerancy in willow warblers during the winter, 59% of the individuals had feather isotope values consistent with stable use of habitats or diets during winter moult. Repeatability analyses suggest that individuals of both subspecies initiate moult in similar habitats from year‐to‐year while feeding on isotopically similar diets.     

Dynamics of agricultural use differentially affect soil properties and crop response in East African wetlands

Agricultural land use changes differentially affect soil fertility and crop production potential of wetlands. We studied East African wetlands with contrasting hydro-geological characteristics (high- and lowland floodplains and valley swamps). Land uses ranged from no use and grazing over crop production in flooded and drained fields to abandonment. We classified the dynamics of wetlands’ conversion into agricultural sites and assessed selected soil fertility attributes associated with land use changes, and their effect on the crop production potential in aerobic and anaerobic soils. A conversion of pristine wetlands, differing in soil physical and chemical attributes, into sites of production tended to negatively affect soil total C and N. Effects were stronger with soil drainage and in the coarse-textured soils of the lowland floodplain and the mid-hill valleys. Mineral P application in drained valleys significantly increased available soil P. Crop response followed these patterns with usually higher biomass accumulation and nutrient uptake in flooded than aerobic soils. Wetlands of fine soil texture in the highlands appeared more resilient than coarse-textured soils, particularly when drained. Enhanced crop performance in flooded soils indicates the possibility for partial recovery of the production potential and the rehabilitation of some wetlands.     

Hippocampal Neuroligin-2 Overexpression Leads to Reduced Aggression and Inhibited Novelty Reactivity in Rats

Disturbances of the excitation/inhibition (E/I) balance in the brain were recently suggested as potential factors underlying disorders like autism and schizophrenia resulting in associated behavioral alterations including changes in social and emotional behavior as well as abnormal aggression. Neuronal cell adhesion molecules (nCAMs) and mutations in these genes were found to be strongly implicated in the pathophysiology of these disorders. Neuroligin2 (nlgn2) is a postsynaptic cell adhesion molecule, which is predominantly expressed at inhibitory synapses and required for synapse specification and stabilization. Changes in the expression of nlgn2 were shown to result in alterations of social behavior as well as altered inhibitory synaptic transmission, hence modifying the E/I balance. In our study, we focused on the role of nlgn2 in the dorsal hippocampus in the regulation of emotional and social behaviors. To this purpose, we injected an AAV construct overexpressing nlgn2 in the hippocampus of rats and investigated the effects on behavior and on markers for the E/I ratio. We could show an increase in GAD65, a GABA-synthesizing protein in neuronal terminals, and furthermore, reduced exploration of novel stimuli and less offensive behavior. Our data suggest nlgn2 in the hippocampus to be strongly implicated in maintaining the E/I balance in the brain and thereby modulating social and emotional behavior.