THE APPLICATION OF TWO FREE-CHOICE PROFILE METHODS TO INVESTIGATE THE SENSORY CHARACTERISTICS OF CHOCOLATE

The concept of free-choice profiling allows untrained assessors to participate in sensory profiling. However, it is sometimes the case that such individuals are unable to describe what they perceive when the samples are presented in the isolation of the sensory testing booths. This paper reports an experiment to compare the usual free-choice profile procedure, with a more structured approach based on Kelly's repertory grid method. Generalized Procrustes analysis was used to analyse the data. The sample configurations obtained from both approaches were very similar, as were the interpretations of the main perceptual dimensions.     

Surface nitrogen and plankton in Skaha Lake, British Columbia (Canada)

This study (1970–71) of an oligotrophic lake subject to cultural enrichment indicates the presence of complex interrelations between plankton and nitrogen levels in surface waters. Generally inorganic nitrogen was high in the winter (0.4–0.5 ppm) and Iow in summer (less than 0-1 ppm). However, in late July and August a large increase in nitrogen (1.5 ppm) was recorded. This correlated with the Gloeotrichia echinulata J. E. Smith ex P. Richt. bloom (Cyanophyceae) and the increase in nitrogen fixation, or nitrogenase activity (measured as acetylene reduction). It was calculated that the cyanophyte bloom could have contributed a minimum of 2350 kg nitrogen to the lake in August 1970 which is c. 62% of the nitrate-nitrogen occurring at any time.     

Importance of denitrifiers lacking the genes encoding the nitrous oxide reductase for N2O emissions from soil

Analyses of the complete genomes of sequenced denitrifying bacteria revealed that approximately 1/3 have a truncated denitrification pathway, lacking the nosZ gene encoding the nitrous oxide reductase. We investigated whether the number of denitrifiers lacking the genetic ability to synthesize the nitrous oxide reductase in soils is important for the proportion of N₂O emitted by denitrification. Serial dilutions of the denitrifying strain Agrobacterium tumefaciens C58 lacking the nosZ gene were inoculated into three different soils to modify the proportion of denitrifiers having the nitrous oxide reductase genes. The potential denitrification and N₂O emissions increased when the size of inoculated C58 population in the soils was in the same range as the indigenous nosZ community. However, in two of the three soils, the increase in potential denitrification in inoculated microcosms compared with the noninoculated microcosms was higher than the increase in N₂O emissions. This suggests that the indigenous denitrifier community was capable of acting as a sink for the N₂O produced by A. tumefaciens. The relative amount of N₂O emitted also increased in two soils with the number of inoculated C58 cells, establishing a direct causal link between the denitrifier community composition and potential N₂O emissions by manipulating the proportion of denitrifiers having the nosZ gene. However, the number of denitrifiers which do not possess a nitrous oxide reductase might not be as important for N₂O emissions in soils having a high N₂O uptake capacity compared with those with lower. In conclusion, we provide a proof of principle that the inability of some denitrifiers to synthesize the nitrous oxide reductase can influence the nature of the denitrification end products, indicating that the extent of the reduction of N₂O to N₂ by the denitrifying community can have a genetic basis.     

Agricultural land use and Skylark Alauda arvensis: a case study linking a habitat association model to spatially explicit change scenarios

The development of forward scenarios is a useful method of envisaging the environmental implications of potential changes in land use, as a tool for policy development. In this paper, a spatially explicit case study is used to provide insight into the environmental impacts of Common Agricultural Policy reform on Skylark Alauda arvensis, a species which is widespread on arable farmland, breeds in crops and has declined in recent decades. A generalized linear mixed model was used to estimate Skylark breeding population densities in different crops, using survey data collected from farms in the east of England, supplemented by the literature. Model outputs were then used to predict Skylark densities in an East Anglian Joint Character Area dominated by arable cropping. Predicted densities were mapped at field level using GIS, based on actual cropping derived from Integrated Administration and Control System data collected for the administration of subsidy payments. Three future scenarios were then created, based on expert opinion of potential changes in cropping over the next 5 years, and potential changes in Skylark density mapped on the basis of the predicted changes in cropping patterns. Overall, Skylark densities were predicted to decrease on average by 11–14% under ‘market‐led’ (increasing wheat and oilseed rape, reduced set‐aside) and ‘energy crop’ (5% area under short rotation coppice) scenarios, but remained virtually unchanged under an ‘environment‐led’ (diverse cropping) scenario. The ‘market‐led’ scenario is closest to short‐term agricultural trajectories, but wider cultivation of biomass energy crops as modelled under the ‘energy crop’ scenario could occur in the medium term if energy policies are favourable. Appropriate mitigation strategies therefore need to be implemented if a continued decline in the Skylark population on lowland arable farmland is to be averted. The results provide a readily accessible visualization of the potential impacts of land‐use change for policy‐makers; similar techniques could be applied to visualize effects of changes arising through other drivers, including climate change.     

Analysis of Proteins Binding to the ITAM Motif of the β-Subunit of the High-Affinity Receptor for IgE (FcεRI)

Aggregation of the multichain (α β γ₂) high-affinity IgE receptor (Fcε RI) initiates a signaling cascade that results in the release of allergic mediators. The cytoplasmic tails of the Fcε RI-β and -γ subunits contain immunoreceptor tyrosine-based activation motifs (ITAMs). Phosphorylation of the γ ITAM mediates activation of Syk kinase and is sufficient for triggering the responses induced by Fcε RI crosslinking. Phosphorylation of the β ITAM is insufficient to mediate cell activation. The rat β ITAM contains three tyrosines (Tyr²¹⁸, Tyr²²⁴, and Tyr²²⁸) with an intermediate noncanonical tyrosine. Synthetic peptides based on the ITAM of the Fcε RI-β subunit were used to investigate the role of each phosphotyrosine in the binding of signaling proteins to this motif. Among the proteins that bind to phosphorylated β ITAM are Syk, Grb2, Shc, SHIP, and SHP-1, and binding does not depend on previous cell activation. Nonphosphorylated peptides do not bind these proteins. Syk binding to β -peptides is dependent on the number and position of phosphotyrosines in the ITAM. Phosphorylation of Tyr²¹⁸ seems to be most important for Syk binding. Recruitment of Syk and other signaling proteins to the β -subunit might be important for its amplifier role.     

Hippuric acid and benzoic acid inhibition of urine derived N2O emissions from soil

Atmospheric concentrations of the greenhouse gas nitrous oxide (N₂O) have continued to rise since the advent of the industrial era, largely because of the increase in agricultural land use. The urine deposited by grazing ruminant animals is a major global source of agricultural N₂O. With the first commitment period for reducing greenhouse gas emissions under the Kyoto Protocol now underway, mitigation options for ruminant urine N₂O emissions are urgently needed. Recent studies showed that increasing the urinary concentration of the minor urine constituent hippuric acid resulted in reduced emissions of N₂O from a sandy soil treated with synthetic bovine urine, due to a reduction in denitrification. A similar effect was seen when benzoic acid, a product of hippuric acid hydrolysis, was used. This current laboratory experiment aimed to investigate these effects using real cow urine for the first time. Increased concentrations of hippuric acid or benzoic acid in the urine led to reduction of N₂O emissions by 65% (from 17% to <6% N applied), with no difference between the two acid treatments. Ammonia volatilization did not increase significantly with increased hippuric acid or benzoic acid concentrations in the urine applied. Therefore, there was a net reduction in gaseous N loss from the soil with higher urinary concentrations of both hippuric acid and benzoic acid. The results show that elevating hippuric acid in the urine had a marked negative effect on both nitrification and denitrification rates and on subsequent N₂O fluxes. This study indicates the potential for developing a novel mitigation strategy based on manipulation of urine composition through ruminant diet.     

Environmental control of fine root dynamics in a northern hardwood forest

Understanding how exogenous and endogenous factors control the distribution, production and mortality of fine roots is fundamental to assessing the implications of global change, yet our knowledge of control over fine root dynamics remains rudimentary. To improve understanding of these processes, the present study developed regression relationships between environmental variables and fine root dynamics within a northern hardwood forest in New Hampshire, USA, which was experimentally manipulated with a snow removal treatment. Fine roots (< 1 mm diameter) were observed using minirhizotrons for 2 years in sugar maple and yellow birch stands and analyzed in relation to temperature, water and nutrient availability. Fine root dynamics at this site fluctuated seasonally, with growth and mortality peaking during warmer months. Monthly fine root production was strongly associated with mean monthly air temperature and neither soil moisture nor nutrient availability added additional predictive power to this relationship. This relationship exhibited a seasonal temperature hysteresis, which was altered by snow removal treatment. These results suggest that both exogenous and endogenous cues may be important in controlling fine root growth in this system. Proportional fine root mortality was directly associated with mean monthly soil temperature, and proportional fine root mortality during the over‐winter interval was strongly related to whether the soil froze. The strong relationship between fine root production and air temperature reported herein contrasts with findings from some hardwood forest sites and indicates that controls on fine root dynamics vary geographically. Future research must more clearly distinguish between endogenous and exogenous control over fine root dynamics in various ecosystems.