Multiple micronutrient deficiencies are widespread in Ethiopia. However, the distribution of Se and Zn deficiency risks has previously shown evidence of spatially dependent variability, warranting the need to explore this aspect for wider micronutrients. Here, blood serum concentrations for Ca, Mg, Co, Cu and Mo were measured (n 3102) on samples from the Ethiopian National Micronutrient Survey. Geostatistical modelling was used to test spatial variation of these micronutrients for women of reproductive age, who represent the largest demographic group surveyed (n 1290). Median serum concentrations were 8·6 mg dl−1 for Ca, 1·9 mg dl−1 for Mg, 0·4 µg l−1 for Co, 98·8 µg dl−1 for Cu and 0·2 µg dl−1 for Mo. The prevalence of Ca, Mg and Co deficiency was 41·6 %, 29·2 % and 15·9 %, respectively; Cu and Mo deficiency prevalence was 7·6 % and 0·3 %, respectively. A higher prevalence of Ca, Cu and Mo deficiency was observed in north western, Co deficiency in central and Mg deficiency in north eastern parts of Ethiopia. Serum Ca, Mg and Mo concentrations show spatial dependencies up to 140–500 km; however, there was no evidence of spatial correlations for serum Co and Cu concentrations. These new data indicate the scale of multiple mineral micronutrient deficiency in Ethiopia and the geographical differences in the prevalence of deficiencies suggesting the need to consider targeted responses during the planning of nutrition intervention programmes.

Nitrous oxide (N2O) is a potent greenhouse gas with implication for climate change. Agriculture accounts for 10% of all greenhouse gas emissions in the United States, but 75% of the country's N2O emissions. In the absence of PRE herbicides, weeds compete with soybean for available soil moisture and inorganic N, and may reduce N2O emissions relative to a weed-free environment. However, after weeds are killed with a POST herbicide, the dead weed residues may stimulate N2O emissions by increasing soil moisture and supplying carbon and nitrogen to microbial denitrifiers. Wider soybean rows often have more weed biomass, and as a result, row width may further impact how weeds influence N2O emissions. To determine this relationship, field studies were conducted in 2013 and 2014 in Arlington, WI. A two-by-two factorial treatment structure of weed management (PRE + POST vs. POST-only) and row width (38 or 76 cm) was arranged in a randomized complete block design with four replications. N2O fluxes were measured from static gas sampling chambers at least weekly starting 2 wk after planting until mid-September, and were compared for the periods before and after weed termination using a repeated measures analysis. N2O fluxes were not influenced by the weed by width interaction or width before termination, after termination, or for the full duration of the study at P ≤ 0.05. Interestingly, we observed that POST-only treatments had lower fluxes on the sampling day immediately prior to POST application (P = 0.0002), but this was the only incidence where weed influenced N2O fluxes, and overall, average fluxes from PRE + POST and POST-only treatments were not different for any period of the study. Soybean yield was not influenced by width (P = 0.6018) or weed by width (P = 0.5825), but yield was 650 kg ha−1 higher in the PRE + POST than POST-only treatments (P = 0.0007). These results indicate that herbicide management strategy does not influence N2O emissions from soybean, and the use of a PRE herbicide prevents soybean yield loss.

Mutations in the gatB gene as well as mutations in the putative structural gene gatA and the positive acting regulatory gene intA can affect γ-amino-n-butyrate (GABA) transaminase (EC 2.6.1.19) levels in the ascomycete fungus Aspergillus nidulans. Partial or complete loss of function mutations in gatA, gatB and ssuA, which specifies succinic semialdehyde dehydrogenase, can lead to accumulation of ω-amino acids resulting in pseudo-constitutivity and elevated expression of (retained) activities under intA control. These regulatory effects underlie selective methods for gatB−, ssuA− and leaky gatA− mutations. However, all three gatB− alleles which have been selected lead only to partial loss of GABA transaminase activity as judged by both in vivo and in vitro criteria. It has not been established whether the leakiness of these three gatB− mutations is an allele-specific or a locus-specific effect and whether or not the GABA transaminase present in gatB− strains differs from the wild type enzyme. Thus the role of the gatB product remains to be elucidated. The gatB gene is not closely linked to any other gene involved in ω-amino metabolism or related pathways.

Interest in the selection of mutations affecting L-proline catabolism in Aspergillus nidulans is heightened by the involvement of one of the very few examples of a cluster of functionally related genes in an eukaryote and by an increasing awareness of the biological phenomena in which proline and proline catabolism participate. The sasA-60 (semialdehyde sensitive) mutation in A. nidulans results in toxicity of catabolic precursors of L-glutamic γ-semialdehyde (or its internal Schiff base L-Δ1-pyrroline-5-carboxylate) and succinic semialdehyde, apparently without affecting the catabolic pathways concerned. As sasA-60 is unlinked to the prn gene cluster, specifying the gene products necessary for L-proline catabolism and as L-proline, a precursor of L-glutamic γ-semialdehyde, is highly toxic to sasA-60 strains, this forms the basis of a powerful positive selection technique for obtaining a number of types of prn mutations. Many of these prn mutations can be directly classified according to the gene product(s) affected on the basis of growth phenotype with respect to L-arginine and L-ornithine utilization, proline-dependent resistance to certain toxic amino acid analogues and effect on supplementation of proline auxotrophies. The availability of both a positive selection technique and an extensive nutritional screening system has enabled the identification of fourteen spontaneous deletion mutations, recognized as extending into the prnB gene, specifying the principal L-proline permease, and into at least one other prn gene. These deletion mutations have been partially characterized both genetically and biochemically. In particular their use has greatly facilitated fine-structure mapping of the prn cluster and aided studies of the regulation of prn gene expression.

Immunoblotting combined with computer imaging and a simple, non-linear mathematical model were used to demonstrate the potential of a technique for non-destructive visualisation and analysis of fungal growth of Rhizoctonia solani over the surface of non-sterile sand. Immunoblotting detected actively growing regions of mycelium enabling visualisation of individual hyphae at the colony edge. A zone of active growth was detected expanding radially over time. Active growth did not continue in the centre of the fungal colony leading to the development of a ring of mycelium surrounding the inoculum. Change in the density of actively growing mycelium with distance from the inoculum unit was summarised for each colony at each time by a Gaussian function, describing a wave of actively growing mycelium, symmetrical in density about its centre but differing amongst replicate colonies. The effectiveness of the immunoblotting technique to detect differences in colony growth was tested by comparing the growth of replicate colonies for two contrasting isolates of R. solani. When both isolates of R. solani were grown at 23 °C the amplitude of the wave increased to a maximum and then decayed over time, the location of the centre of the wave moved outwards at a constant rate, whilst the width of the wave increased. Increasing the temperature to 28 °, accelerated this intrinsic growth process for one isolate, but retarded growth of the other.

In seeking to understand at a microscopic level the response of dislocations to stress we have undertaken to study as completely as possible the simplest case: a single dislocation in a two dimensional crystal. The intention is that results from this study will be used as input parameters in larger length scale simulations involving many defects. We present atomistic simulations of defect motion in a two-dimensional material consisting of atoms interacting through a modified Lennard-Jones potential. We focus on the regime where the shear stress is smaller than its critical value, where there is a finite energy barrier for the dislocation to hop one lattice spacing. In this regime motion of the dislocation will occur as single hops through thermal activation over the barrier. Accurate knowledge of the barrier height is crucial for obtaining the rates of such processes. We have calculated the energy barrier as a function of two components of the stress tensor in a small system, and have obtained good fits to a functional form with only a few adjustable parameters.