Incorporation of palmitic acid or oleic acid into macrophage membrane lipids exerts differential effects on the function of normal mouse peritoneal macrophages

Normal mouse peritoneal macrophages were enriched with either palmitic acid (16:0) or oleic acid (18:1). Normal or oleic acid-enriched macrophages showed 3-4-fold greater erythrophagocytic capacity as compared to palmitic acid-enriched macrophages. Staphylococcus aureus uptake was only moderately decreased in palmitic acid-enriched macrophages. Fatty acid modifications did not influence the ability of macrophages to kill intracellular bacteria or to generate superoxide anions after stimulation with phorbol myristate acetate or opsonized zymosan.     

A telemedicine instrument for remote evaluation of tremor: design and initial applications in fatigue and patients with Parkinson's Disease

Introduction  

A novel system that combines a compact mobile instrument and Internet communications is presented in this paper for remote evaluation of tremors. The system presents a high potential application in Parkinson's disease and connects to the Internet through a TCP/IP protocol. Tremor transduction is carried out by accelerometers, and the data processing, presentation and storage were obtained by a virtual instrument. The system supplies the peak frequency (fp), the amplitude (Afp) and power in this frequency (Pfp), the total power (Ptot), and the power in low (1-4 Hz) and high (4-7 Hz) frequencies (Plf and Phf, respectively).     

Bacteria on leaves: a previously unrecognised source of N2O in grazed pastures

Nitrous oxide (N₂O) emissions from grazed pastures are a product of microbial transformations of nitrogen and the prevailing view is that these only occur in the soil. Here we show this is not the case. We have found ammonia-oxidising bacteria (AOB) are present on plant leaves where they produce N₂O just as in soil. AOB (Nitrosospira sp. predominantly) on the pasture grass Lolium perenne converted 0.02–0.42% (mean 0.12%) of the oxidised ammonia to N₂O. As we have found AOB to be ubiquitous on grasses sampled from urine patches, we propose a ‘plant'' source of N₂O may be a feature of grazed grassland.In terms of climate forcing, nitrous oxide (N₂O) is the third most important greenhouse gas (Blunden and Arndt, 2013). Agriculture is the largest source of anthropogenic N₂O (Reay et al., 2012) with about 20% of agricultural emissions coming from grassland grazed by animals (Oenema et al., 2005).Grazed grassland is a major source of N₂O because grazers harvest nitrogen (N) from plants across a wide area but recycle it back onto the pasture, largely as urine, in patches of very high N concentration. The N in urine patches is often in excess of what can be used by plants resulting in losses through leaching as nitrate, as N₂O and through volatilisation as ammonia (NH₃) creating a high NH₃ environment in the soil and plant canopy; an important point that we will return to later. The established wisdom is that N₂O is generated exclusively by soil-based microbes such as ammonia-oxidising bacteria (AOB). This soil biology is represented in models designed to simulate N₂O emissions and the soil is a target for mitigation strategies such as the use of nitrification inhibitors.We have previously shown that pasture plants can emit N₂O largely through acting as a conduit for emissions generated in the soil, which are themselves controlled to some degree by the plant (Bowatte et al., 2014). In this case the origin of the emission is still the soil microbes. However, AOB have been found on the leaves of plants, for example, Norway spruce (Papen et al., 2002; Teuber et al., 2007) and weeds in rice paddies (Bowatte et al., 2006), prompting us to ask whether AOB might be present on the leaves of pasture species and contribute to N₂O emissions as they do in soil.We looked for AOB on plants in situations where NH₃ concentrations were likely to be high, choosing plants from urine patches in grazed pastures and plants from pastures surrounding a urea fertiliser manufacturing plant. DNA was extracted from the leaves (including both the surface and apoplast) and the presence of AOB tested using PCR. AOB were present in all the species we examined—the grasses Lolium perenne, Dactylis glomerata, Anthoxanthum odoratum, Poa pratensis, Bromus wildenowii and legumes Trifolium repens and T. subterraneum.To measure whether leaf AOB produce N₂O, we used intact plants of ryegrass (L. perenne) lifted as cores from a paddock that had been recently grazed by adult sheep. The cores were installed in a chamber system designed to allow sampling of above- and belowground environments separately (Bowatte et al., 2014). N₂O emissions were measured from untreated (control) plants and from plants where NH₃ was added to the aboveground chamber and leaves were either untreated or sterilised by wiping twice with paper towels soaked in 1% hypoclorite (Sturz et al., 1997) and then with sterile water. We tested for the presence and abundance of AOB on the leaves by extracting DNA and using PCR and real-time PCR targeting the ammonia monoxygenase A (amoA) gene, which is characteristic of AOB. AOB identity was established using cloning and DNA sequencing. Further details of these experiments can be found in the Supplementary Information.The addition of NH₃ to untreated plants significantly stimulated N₂O emissions (P<0.001) compared with the controls; by contrast, the plants with sterilised leaves produced significantly less N₂O than controls (P<0.001) even with NH₃ added (Figure 1) providing strong evidence for emissions being associated with bacteria on the leaves. Control plants did emit N₂O suggesting there was either sufficient NH₃ available for bacterially generated emissions and/or other plant-based mechanisms were involved (Bowatte et al., 2014).Open in a separate windowFigure 1Effect of an elevated NH₃ atmosphere and surface sterilisation of leaves on leaf N₂O emissions measured over 1-h periods on three occasions during the day. Values are means (s.e.m.), where n=7.The major AOB species identified was Nitrosospira strain III7 that has been previously shown to produce N₂O (Jiang and Bakken, 1999). We measured 10⁹ AOB cells per m² ryegrass leaf, assuming a specific leaf area of 250 cm² g⁻¹ leaf.The rate of production of N₂O (0.1–0.17 mg N₂O-N per m² leaf area per hour) can be translated to a field situation using the leaf area index (LAI)—1 m² leaf per m² ground would be an LAI of 1. LAI in a pasture can vary from <1 to >6 depending on the management (for example, Orr et al., 1988). At LAI of 1, the AOB leaf emission rate would equate to a N₂O emission rate of about 0.1–0.3 mg N₂O-N per m² ground per hour. By comparison, the emission rates measured after dairy cattle urine (650 kg N ha⁻¹) was applied to freely and poorly drained soil were 0.024–1.55 and 0.048–3.33 mg N₂O-N per m² ground per hour, respectively (Li and Kelliher, 2005).The fraction of the NH₃ that was converted to N₂O by the leaf AOB was 0.02–0.42% (mean 0.12%). The mean value is close to that measured for Nitrosospira strains including strain III7 isolated from acidic, loamy and sandy soils where values ranged from 0.07 to 0.10% (Jiang and Bakken, 1999). This is good evidence that the AOB on leaves have the capacity to produce N₂O at the same rate as AOB in soils. We do not suggest that leaf AOB will produce as much N₂O as soil microbes; however, because leaf AOB have access to a source of substrate—volatilised NH₃—that is unavailable to soil microbes and may constitute 26% (Laubach et al., 2013) to 40% (Carran et al., 1982) of the N deposited in the urine, N₂O emissions from these aboveground AOB are additional to soil emissions. Further research is required to identify the situations in which leaf AOB contribute to total emissions and to quantify this contribution.     

Microbial diversity and complexity in hypersaline environments: A preliminary assessment

The microbial communities in solar salterns and a soda lake have been characterized using two techniques: BIOLOG, to estimate the metabolic potential, and amplicon length heterogeneity analysis, to estimate the molecular diversity of these communities. Both techniques demonstrated that the halophilic Bacteria and halophilic Archaea populations in the Eilat, Israel saltern are dynamic communities with extensive metabolic potentials and changing community structures. Halophilic Bacteria were detected in Mono Lake and the lower salinity ponds at the Shark Bay saltern in Western Australia, except when the crystallizer samples were stressed by exposure to Acid Green Dye #9899. At Shark Bay, halophilic Archaea were found only in the crystallizer samples. These data confirm both the metabolic diversity and the phylogenetic complexity of the microbial communities and assert the need to develop more versatile media for the cultivation of the diversity of bacteria in hypersaline environments. Journal of Industrial Microbiology & Biotechnology (2002) 28, 48–55 DOI: 10.1038/sj/jim/7000175 Received 20 May 2001/ Accepted in revised form 15 June 2001     

Molecular population genetics of the alcohol dehydrogenase locus in the Hawaiian drosophilid D. mimica

Sequence variation among 10 alleles of the alcohol dehydrogenase (Adh) gene of the Hawaiian drosophilid D. mimica was analyzed with reference to the evolutionary history of the Hawaiian subgroup as well as to levels and patterns of polymorphism of the Adh gene in continental drosophilid species. The Adh gene of D. mimica is less polymorphic than that of other drosophilid species, and no replacement substitutions were found. Statistical analyses of the Adh alleles suggested the action of balancing selection and revealed significant linkage disequilibrium among three of the variable sites. The effective population size was estimated to be only slightly smaller than that of continental species and, surprisingly, on the same order of magnitude as the actual size.      

Preliminary studies on the induction of a 120 000 molecular weight protein in resident peritoneal macrophages by arachidonic acid

Exogenous arachidonic acid induced the synthesis of a 120 000 molecular weight protein in resident peritoneal macrophages. The induction of this protein is specific to the presence of arachidonic acid in the culture medium and is not induced by the presence of other fatty acids, irrespective of their chain length or degree of unsaturation. The protein induced is not a secretory protein and is not formed as a result of the processing of preexisting proteins in macrophages. In addition to arachidonic acid, prostaglandin E₂ also induced the synthesis of 120 000 molecular weight protein in macrophages.