Prospects for Gene lntrogression from Hordeum bulbosum L. into Barley (H. vulgare L.).

Hybridizations between Hordeum vulgare L. (cultivated barley) and H. bulbosum L. have been performed over many years with two aims. First, the production of doubled haploid barley cultivars (Kasha and Kao 1970); second, the transfer of desirable traits such as resistance to fungal and viral pathogens from the wild species into barley. Apart from the report of an occasional recombinant (Xu and Kasha 1992; Pickering et al 1994), successful gene introgression has been hampered by several barriers. In this report we will describe recent progress in overcoming these barriers

Assessing the Health of Richibucto Estuary with the Latent Health Factor Index

The ability to quantitatively assess the health of an ecosystem is often of great interest to those tasked with monitoring and conserving ecosystems. For decades, research in this area has relied upon multimetric indices of various forms. Although indices may be numbers, many are constructed based on procedures that are highly qualitative in nature, thus limiting the quantitative rigour of the practical interpretations made from these indices. The statistical modelling approach to construct the latent health factor index (LHFI) was recently developed to express ecological data, collected to construct conventional multimetric health indices, in a rigorous quantitative model that integrates qualitative features of ecosystem health and preconceived ecological relationships among such features. This hierarchical modelling approach allows (a) statistical inference of health for observed sites and (b) prediction of health for unobserved sites, all accompanied by formal uncertainty statements. Thus far, the LHFI approach has been demonstrated and validated on freshwater ecosystems. The goal of this paper is to adapt this approach to modelling estuarine ecosystem health, particularly that of the previously unassessed system in Richibucto in New Brunswick, Canada. Field data correspond to biotic health metrics that constitute the AZTI marine biotic index (AMBI) and abiotic predictors preconceived to influence biota. We also briefly discuss related LHFI research involving additional metrics that form the infaunal trophic index (ITI). Our paper is the first to construct a scientifically sensible model to rigorously identify the collective explanatory capacity of salinity, distance downstream, channel depth, and silt-clay content --- all regarded a priori as qualitatively important abiotic drivers --- towards site health in the Richibucto ecosystem.Comment: On 2013-05-01, a revised version of this article was accepted for publication in PLoS One. See Journal reference and DOI belo

Single-molecule techniques in biophysics : a review of the progress in methods and applications

Single-molecule biophysics has transformed our understanding of the fundamental molecular processes involved in living biological systems, but also of the fascinating physics of life. Far more exotic than a collection of exemplars of soft matter behaviour, active biological matter lives far from thermal equilibrium, and typically covers multiple length scales from the nanometre level of single molecules up several orders of magnitude to longer length scales in emergent structures of cells, tissues and organisms. Biological molecules are often characterized by an underlying instability, in that multiple metastable free energy states exist which are separated by energy levels of typically just a few multiples of the thermal energy scale of kBT, where kB is the Boltzmann constant and T the absolute temperature, implying complex, dynamic inter-conversion kinetics across this bumpy free energy landscape in the relatively hot, wet environment of real, living biological matter. The key utility of single-molecule biophysics lies in its ability to probe the underlying heterogeneity of free energy states across a population of molecules, which in general is too challenging for conventional ensemble level approaches which measure mean average properties. Parallel developments in both experimental and theoretical techniques have been key to the latest insights and are enabling the development of highly-multiplexed, correlative techniques to tackle previously intractable biological problems. Experimentally, technological developments in the sensitivity and speed of biomolecular detectors, the stability and efficiency of light sources, probes and microfluidics, have enabled and driven the study of heterogeneous behaviours both in vitro and in vivo that were previously undetectable by ensemble methods..

Assessment of coastal management options by means of multilayered ecosystem models

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of the main forcing functions, such as catchment loading and aquaculture activities. This approach was developed as a tool for sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed in conjunction with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay were predicted to exceed the thresholds for poor quality defined by Chinese seawater quality legislation. For all scenarios there is still a Moderate High to High nutrient loading from the catchment, so further reductions might be enacted, together with additional decreases in fish cage culture. The model predicts that overall, shellfish production decreases by 10%–28% using any of these development scenarios, principally because shellfish growth is being sustained by the substances to be reduced for improvement of water quality. The model outcomes indicate that this may be counteracted by zoning of shellfish aquaculture at the ecosystem level in order to optimize trade-offs between productivity and environmental effects. The present case study exemplifies the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and may be particularly useful for the application of coastal management regulation, for instance in the implementation of the European Marine Strategy Framework Directive

Studies on net blotch of ryegrass caused by Drechslera dictyoides

Three species of Drechslera were isolated from ryegrass; D. dictyoides f. sp. perenne; D. siccans and D. nobleae. The species were distinguishable by taxonomic characters; conidiophore length, arrangement of conidia, conidial shape, the manner of germination and cultural characters; morphology and growth rate. D. dictyoides was characterised by tapered conidia produced at intervals on the conidiophore. Germination was predominantly from the basal cell of the conidium and growth in culture was slower than that of the other two species. The life history of D. dictyoides on L. perenne was investigated using optical and electron microscopy. Changes in the ultrastructure of the host and pathogen were followed during infection. The vegetative fungal wall consisted of two layers but modifications, usually involving reductions in one or more of these layers, during infection were important in the successful establishment of a parasitic relationship with the host. Appressoria formed predominantly over the anticlinal wall of the host epidermis but germ tube length was variable. Penetration was usually into an epidermal cell but subcuticular infection was common. In the period of lesion development, hyphae spread intercellularly with limited host reaction until host senescence began, at which time intracellular hyphae were again found. D. dictyoides was interpreted as a hemibiotrophic pathogen and formed a close nutritional relationship with its host. Intrahyphal hyphae were occasionally found within lesions. Conidium development was interpreted as holoblastic and discussed in relation to theories concerning 'blastic' ontogeny. A field trial indicated the presence of a wide variation in resistance of perennial ryegrass lines to net blotch. Drought conditions were experienced during much of the field trial, but increases in disease intensity usually followed periods of rain, with a major increase occurring in March 1982. The ryegrass epidermis was examined in relation to the effect on net blotch development. Epicuticular wax projections were present on the adaxial surface but absent on the abaxial surface and this resulted in greater spore accumulation on the latter. In contrast, the outer wall of the adaxial epidermis was approximately half as thick as that of the abaxial epidermis. Given sufficient moisture, penetration of the adaxial surface was more rapid than that of the abaxial surface. Host nuclei migrated towards the site of attempted penetration of the leaf and cytoplasm accumulated in this region. Glasshouse and laboratory assessments of the effect of leaf age showed that infection was greater on older leaves. The interaction of exposure time and leaf senescence was responsible for the observed differences. Infection was possible over a wide temperature range but the optimum was close to 20°C. The Lolium endophyte was present in most perennial ryegrass plants but appeared to have no affect on net blotch disease even when hyphae of both fungi were closely associated within a leaf lesion. Spore accumulation on the leaves of susceptible trap plants was greater than on those of more resistant lines, resulting in a higher density of infections on leaves of susceptible lines which was compounded over several disease cycles. This appeared to be largely responsible for the difference in disease intensity between lines in the field

Pathogenicity of Gaeumannomyces graminis var. tritici increased by nitrogen applied to soil to enhance the decomposition rate of wheat residues

Soil cores removed after harvest of a wheat crop infected with the fungus, Gaeumannomyces graminis var. tritici (Ggt), were amended with nitrogen and fungal saprophytes to increase decay of crop residues and subsequently reduce soil inoculum. The cores were treated with one application of 50 kg nitrogen (N) per ha, Trichoderma strains, or both. Cores were assessed 0, 2, 4 and 7 months after harvest. At 7 months, the crop residues had decayed to a third of their original mass, with the decay not influenced by the treatments. DNA analysis confirmed Ggt DNA was present in the stubble stems, crowns and roots. The pathogenicity of Ggt was increased by N, as shown by a 5 to 8-fold increase in take-all severity in indicator wheat seedlings planted in the N-treated cores 2 to 4 months after harvest, compared with those without N. Ggt remained viable in all treatments to infect wheat seedlings 7 months after harvest