Effects of dietary polyunsaturated fatty acid supplementation on fatty acid composition in muscle and subcutaneous adipose tissue of lambs

Lambs (n = 48) were used in a 2 × 2 factorial arrangement of treatments to evaluate effects of inclusion of oil containing PUFA in high-concentrate diets (with or without) and duration of oil supplementation (pre- vs. postweaning) on CLA concentration of muscle and adipose tissue. Lambs were fed preweaning creep diets (with or without oil) corresponding to the dietary lactation treatment diet (with or without oil) of the dam. Dams blocked by lambing date and rearing type were randomly assigned to 1 of 2 lactation dietary treatments with or without oil supplementation. Creep diets contained approximately 70% concentrate and 30% roughage and were provided to lambs for ad libitum intake. At weaning (58.7 ± 2.5 d of age), lambs (n = 48) were randomly assigned within preweaning treatment groups to 1 of 2 postweaning dietary treatments (with or without oil) and 16 pens in a randomized block design, blocked by sex and BW. Postweaning diets were formulated to contain approximately 80% concentrate and 20% roughage and were fed once daily for ad libitum intake. Soybean and linseed oil (2:1, respectively) replaced ground corn and provided 3% additional fat in pre- and postweaning diets. Lambs were slaughtered at 60.3 ± 4.2 kg of BW. A subcutaneous fat (SQ) sample was obtained within 1 h postmortem and a LM sample at the 12th rib was obtained 24 h postmortem, and both were analyzed for fatty acid profile. Feedlot performance and carcass measurements were not affected (P ≥ 0.26) by oil supplementation. Total CLA content of LM and SQ was not affected (P ≥ 0.08) by oil supplementation pre- or postweaning, but trans-10, cis-12 CLA was greater (P = 0.02) in SQ from lambs supplemented with oil postweaning. Total PUFA content in LM was greater (P = 0.02) in lambs supplemented with oil pre- or postweaning as a result of increased concentrations of 18:2cis-9, cis-12 and longer chain PUFA. Conversely, pre- and postweaning oil supplementation resulted in less (P = 0.04) MUFA content in LM. Only postweaning oil supplementation increased (P = 0.001) SQ PUFA content. Feeding oils containing PUFA to lambs pre- and postweaning did not increase CLA content of muscle, whereas postweaning oil supplementation minimally increased CLA concentration of SQ fat. Inclusion of soybean and linseed oil in pre- and postweaning diets increased total PUFA content of SQ fat and muscle tissue without adversely affecting growth performance or carcass characteristics.

Effect of the growth promoter avilamycin on emergence and persistence of antimicrobial resistance in enteric bacteria in the pig

Aim: To assess the effect of the growth promoter avilamycin on emergence and persistence of resistance in enteric bacteria in the pig. Methods and Results: Pigs ( treated with avilamycin for 3 months and controls) were challenged with multiresistant Salmonella Typhimurium DT104 and faecal counts were performed for enterococci, Escherichia coli, S. Typhimurium and Campylobacter ( before, during and 5 weeks post-treatment). Representative isolates were tested for antibiotic resistance and for the presence of resistance genes. Avilamycin-resistant Enterococci faecalis (speciated by PCR) were isolated from the treated pigs and continued to be detected for the first week after treatment had ceased. The avilamycin- resistance gene was characterized by PCR as the emtA gene and speciation by PCR. MIC profiling confirmed that more than one strain of Ent. faecalis carried this gene. There was no evidence of increased antimicrobial resistance in the E. coli, Salmonella and Campylobacter populations, although there was a higher incidence of tetB positive E. coli in the treated pigs than the controls. Conclusion: Although avilamycin selects for resistance in the native enterococci population of the pig, no resistant isolates were detected beyond 1 week post-treatment. This suggests that resistant isolates were unable to persist once selective pressure was removed and were out-competed by the sensitive microflora. Significance and Impact of the Study: Our data suggest the risk of resistant isolates becoming carcass contaminants and infecting humans could be minimized by introducing a withdrawal period after using avilamycin and prior to slaughter.

Molecular targets underlying SUMO-mediated neuroprotection in brain ischemia

SUMOylation (small ubiquitin-like modifier conjugation) is an important post-translational modification which is becoming increasingly implicated in the altered protein dynamics associated with brain ischemia. The function of SUMOylation in cells undergoing ischemic stress and the identity of small ubiquitin-like modifier (SUMO) targets remain in most cases unknown. However, the emerging consensus is that SUMOylation of certain proteins might be part of an endogenous neuroprotective response. This review brings together the current understanding of the underlying mechanisms and downstream effects of SUMOylation in brain ischemia, including processes such as autophagy, mitophagy and oxidative stress. We focus on recent advances and controversies regarding key central nervous system proteins, including those associated with the nucleus, cytoplasm and plasma membrane, such as glucose transporters (GLUT1, GLUT4), excitatory amino acid transporter 2 glutamate transporters, K+ channels (K2P1, Kv1.5, Kv2.1), GluK2 kainate receptors, mGluR8 glutamate receptors and CB1 cannabinoid receptors, which are reported to be SUMO-modified. A discussion of the roles of these molecular targets for SUMOylation could play following an ischemic event, particularly with respect to their potential neuroprotective impact in brain ischemia, is proposed.

Surface chemistry of alanine on Cu{111}: Adsorption geometry and temperature dependence

Adsorption of l-alanine on the Cu{111} single crystal surface was investigated as a model system for interactions between small chiral modifier molecules and close-packed metal surfaces. Synchrotron-based X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy are used to determine the chemical state, bond coordination and out-of-plane orientation of the molecule on the surface. Alanine adsorbs in its anionic form at room temperature, whilst at low temperature the overlayer consists of anionic and zwitterionic molecules. NEXAFS spectra exhibit a strong angular dependence of the π ⁎ resonance associated with the carboxylate group, which allows determining the tilt angle of this group with respect to the surface plane (48° ± 2°) at room temperature. Low-energy electron diffraction (LEED) shows a p(2√13x2√13)R13° superstructure with only one domain, which breaks the mirror symmetry of the substrate and, thus, induces global chirality to the surface. Temperature-programmed XPS (TP-XPS) and temperature-programmed desorption (TPD) experiments indicate that the zwitterionic form converts into the anionic species (alaninate) at 293 K. The latter desorbs/decomposes between 435 K and 445 K.

Observing the in situ chiral modification of Ni nanoparticles using scanning transmission X-ray microspectroscopy

Enantioselective heterogeneous hydrogenation of Cdouble bond; length as m-dashO bonds is of great potential importance in the synthesis of chirally pure products for the pharmaceutical and fine chemical industries. One of the most widely studied examples of such a reaction is the hydrogenation of β-ketoesters and β-diketoesters over Ni-based catalysts in the presence of a chiral modifier. Here we use scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) to investigate the adsorption of the chiral modifier, namely (R,R)-tartaric acid, onto individual nickel nanoparticles. The C K-edge spectra strongly suggest that tartaric acid deposited onto the nanoparticle surfaces from aqueous solutions undergoes a keto-enol tautomerisation. Furthermore, we are able to interrogate the Ni L2,3-edge resonances of individual metal nanoparticles which, combined with X-ray diffraction (XRD) patterns showed them to consist of a pure nickel phase rather than the more thermodynamically stable bulk nickel oxide. Importantly, there appears to be no “particle size effect” on the adsorption mode of the tartaric acid in the particle size range ~ 90–~ 300 nm.

Emulation of chiral hydrogenation catalysts by adsorbtion of small molecules onto Ni surfaces

Adsorption of small molecules on the Ni{111} and NiO{111} surfaces is investigated under UHV and elevated pressures (~10-1 mbar) of hydrogen and water. The molecules considered are chosen for their relevance to understanding the mechanism of enantioselective hydrogenation on Raney Nickel modified by chiral molecules. Adsorption of water onto, and its subsequent reaction with, oxygen-covered Ni{111} is dependent on the initial atomic oxygen coverage. An OH species (O1s binding energy 531.5eV), oriented perpendicular to the surface, forms at atomic oxygen coverages <0.25ML. The reaction does not consume all the adsorbed oxygen for coverages ≥0.12ML. The p(2×2) atomic oxygen uperstructure is unreactive, while an OH species is formed on the p(√3×√3) superstructure at binding energy 530.9eV. L-alanine is adsorbed on Ni{111} as a model chiral modifier molecule. At low coverages, alanine forms a presumed tridentate alaninate species for coverages ≥0.11ML at 250K. A minority, bidentate zwitterionic species forms at coverages >0.11ML, but was not observed at 300K. Saturation occurs at 0.25ML. At high alanine coverages (≥0.19ML) and H2 pressure (≥1×10-2 mbar), the tridentate L-alaninate converts to bidentate zwitterionic L-alanine at 300K. Thermal evolution of L-alanine on Ni{111} under varying hydrogen pressures is examined. Adsorption of L-alanine onto hydroxylated NiO{111} at 300K in UHV, mimicking a catalyst surface under aqueous conditions, yields the tridentate alaninate which is immune to the effects of elevated hydrogen pressure. Exposing the L-alanine/Ni{111} adsorption system to water (≤10-1 mbar) oxidises the surface and recreates the L-alanine/hydroxylated NiO{111} system. Pyruvic acid on Ni{111} is examined as a model for hydrogenation substrate adsorption. Behaviour is coverage dependent and several conformations are possible at low coverages (≤0.1ML). Annealing at coverages <0.2ML causes a condensation reaction, releasing water onto the surface. High coverages do not condense and a saturation coverage of ~0.35ML is found.

Temperature affects microbial decomposition of cadavers (Rattus rattus) in contrasting soils

The ecology of soils associated with dead mammals (i.e. cadavers) is poorly understood. Although temperature and soil type are well known to influence the decomposition of other organic resource patches, the effect of these variables on the degradation of cadavers in soil has received little experimental investigation. To address this, cadavers of juvenile rats (Rattus rattus) were buried in one of three contrasting soils (Sodosol, Rudosol, and Vertosol) from tropical savanna ecosystems in Queensland, Australia and incubated at 29 °C, 22 °C, or 15 °C in a laboratory setting. Cadavers and soils were destructively sampled at intervals of 7 days over an incubation period of 28 days. Measurements of decomposition included cadaver mass loss, carbon dioxide–carbon (CO2–C) evolution, microbial biomass carbon (MBC), protease activity, phosphodiesterase activity, and soil pH, which were all significantly positively affected by cadaver burial. A temperature effect was observed where peaks or differences in decomposition that at occurred at higher temperature would occur at later sample periods at lower temperature. Soil type also had an important effect on some measured parameters. These findings have important implications for a largely unexplored area of soil ecology and nutrient cycling, which are significant for forensic science, cemetery planning and livestock carcass disposal.

SUMOylation: novel neuroprotective approach for Alzheimer's disease?

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized in the brain by the formation of amyloid-beta (Aβ)-containing plaques and neurofibrillary tangles containing the microtubule-associated protein tau. Neuroinflammation is another feature of AD and astrocytes are receiving increasing attention as key contributors. Although some progress has been made, the molecular mechanisms underlying the pathophysiology of AD remain unclear. Interestingly, some of the main proteins involved in AD, including amyloid precursor protein (APP) and tau, have recently been shown to be SUMOylated. The post-translational modification by SUMO (small ubiquitin-like modifier) has been shown to regulate APP and tau and may modulate other proteins implicated in AD. Here we present an overview of recent studies suggesting that protein SUMOylation might be involved in the underlying pathogenic mechanisms of AD and discuss how this could be exploited for therapeutic intervention.