The effect of acidosis on the labelling of urinary ammonia during infusion of [amide-15N]glutamine in human subjects

In three experiments [amide-15N]glutamine was infused intravenously in male volunteers. After 4-8 h of infusion acidosis was achieved by an oral dose of CaCl2 (1 mmol/kg). In one subject acidosis was maintained for 5 d. The acid load produced an approximately 3-fold increase in urinary NH3 excretion, with a small (approximately 20%) and transient increase in the isotope abundance of urinary NH3 Estimates of glutamine production rate (flux) were obtained in two experiments. There was no evidence that it was increased in acidosis. The extra NH3 production by the kidney represented only a very small part, about 3%, of the total glutamine production rat

Survey of Barley and Wheat Diseases in the Central Highlands of Eritrea

Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surveys covered six zones of the central highlands where barley and wheat are grown. The main diseases of barley were netform net blotch, spot-form net blotch, leaf rust and scald. Other, less important diseases were loose smut, covered smut, barley stripe and septoria leaf blotch. Wheat was mainly affected by yellow rust and leaf rust. Loose smut, septoria leaf spot and tan spot diseases were less prevalent. The average incidence of these diseases varied according to the zone. Among barley diseases, net blotch incidence was high in four of the six zones surveyed. Leaf rust occurred at medium incidence in five zones. Loose smut was more severe in the southern highland plains, while covered smut was more common in the south-eastern highland terraces. For wheat, yellow rust incidence was high in two zones. Areas with a high incidence of yellow rust were not necessarily those with a high incidence of leaf rust. Leaf rust was important in the south-eastern and western highland terraces and in the western highland plains. The number of diseases found in the same field varied from 2 to 5. The south eastern highland terraces, the western highland terraces and the northern highland terraces had the highest proportions of individual barley fields with three or more diseases

GWAS of Barley Phenotypes Established Under Future Climate Conditions of Elevated Temperature, CO2, O3 and Elevated Temperature and CO2 Combined

AbstractClimate change is likely to decrease crop yields worldwide. Developing climate resilient cultivars is one way to combat this production scarcity, however, little is known of crop response to future climate conditions and in particular the variability within crops.In Scandinavia, barley is widely cultivated, but yields have stagnated since the start of this century. In this study we cultivated 138 spring barley accessions in a climate phytotron under four treatments mimicking forecasted levels of temperature, carbon dioxide concentration ([CO2]) and ozone ([O3]) at the end of the 21st century1. The ambient control had 19/12°C (day/night) and [CO2] at 385ppm. Three single-factor treatments had elevated temperature +5°C day/night, [CO2] at 700ppm or [O3] at 120 ppb, and in a two-factor treatment the combination of elevated temperature and [CO2] was applied.Treatment effects were assessed on grain yield, grain protein concentration, grain protein harvested, number of grains, number of ears, aboveground vegetative biomass and harvest index. In addition, stability of the production was calculated over the applied treatments for the assessed parameters.In the climate scenario of elevated temperature and [CO2] the grain yield of barley decreased 29% and harvested grain protein declined 22%. Vast variation was identified among the individual barley accessions, which should be exploited by plant breeders in the development of climate resilient cultivars.A genome-wide association study (GWAS) of recorded phenotypes and 3967 SNP-markers identified 60 marker-trait associations (-logp>2.95)2. Markers were found associated with grain yield under all three single factor treatments temperature, [CO2] and [O3], as well as with stability over treatments.To our knowledge, this is the first study that evaluates numerous barley accessions under future climate conditions and identifies candidate markers for abiotic stress tolerance - markers that could be used in the development of cultivars to secure future primary production

The Interaction of N-Acylhomoserine Lactone Quorum Sensing Signaling Molecules with Biological Membranes: Implications for Inter-Kingdom Signaling

The long chain N-acylhomoserine lactone (AHL) quorum sensing signal molecules released by Pseudomonas aeruginosa have long been known to elicit immunomodulatory effects through a process termed inter-kingdom signaling. However, to date very little is known regarding the exact mechanism of action of these compounds on their eukaryotic targets.The use of the membrane dipole fluorescent sensor di-8-ANEPPS to characterise the interactions of AHL quorum sensing signal molecules, N-(3-oxotetradecanoyl)-L-homoserine lactone (3-oxo-C14-HSL), N-(3-oxododecanoyl)homoserine-L-lactone (3-oxo-C12-HSL) and N-(3-oxodecanoyl) homoserine-L-lactone (3-oxo-C10 HSL) produced by Pseudomonas aeruginosa with model and cellular membranes is reported. The interactions of these AHLs with artificial membranes reveal that each of the compounds is capable of membrane interaction in the micromolar concentration range causing significant modulation of the membrane dipole potential. These interactions fit simple hyperbolic binding models with membrane affinity increasing with acyl chain length. Similar results were obtained with T-lymphocytes providing the evidence that AHLs are capable of direct interaction with the plasma membrane. 3-oxo-C12-HSL interacts with lymphocytes via a cooperative binding model therefore implying the existence of an AHL membrane receptor. The role of cholesterol in the interactions of AHLs with membranes, the significance of modulating cellular dipole potential for receptor conformation and the implications for immune modulation are discussed.Our observations support previous findings that increasing AHL lipophilicity increases the immunomodulatory activity of these quorum compounds, while providing evidence to suggest membrane interaction plays an important role in quorum sensing and implies a role for membrane microdomains in this process. Finally, our results suggest the existence of a eukaryotic membrane-located system that acts as an AHL receptor