The effect of an acidified-gypsum mixture on broiler litter urease-producing bacteria and nitrogen mineralization.

Ammonia (NH3 ) volatilization from broiler (Gallus gallus domesticus) litter is a microbially mediated process that can decrease bird productivity and serves as an environmental pollutant. The release of NH3 is strongly influenced by the pH of litter. Flue-gas desulfurization gypsum (FGDG) has been suggested as a potential amendment to reduce NH3 volatilization due to the pH buffering capacity of calcium carbonate (CaCO3 ) precipitation. However, its effect on litter pH is not as pronounced as acidifying agents, such as aluminum sulfate (alum). The main objective of our study was to develop an acidified-FGDG amendment that has a more pronounced effect on litter pH and NH3 volatilization than FGDG alone. We conducted a 33-d incubation in which litter pH, NH3 volatilization, nitrogen mineralization, PLUP-ureC gene abundance, and CaCO3 precipitation were measured. Treatments in the study included: broiler litter (BL), broiler litter + 20% FGDG (BL+FGDG), broiler litter + FGDG-alum mixture (BL+FGDG+A6), broiler litter + 6% alum (BL+A6), and broiler litter + 10% alum (BL+A10). Our FGDG+alum amendment decreased litter pH (0.68 pH units) and PLUP-ureC gene abundance (>1 log) compared with FGDG alone and the control (p < .05). This led to a 25% decrease in cumulative NH3 loss after 33 d. The addition of FGDG alone did not have an effect on litter pH (p = .36) or cumulative NH3 loss (p = .29) due to a lack of significant CaCO3 precipitation. Treating litter with 6 and 10% alum was the most effective amendment for reducing pH and cumulative NH3 loss.

Type II Fusarium head blight susceptibility conferred by a region on wheat chromosome 4D.

Fusarium head blight (FHB) causes significant grain yield and quality reductions in wheat and barley. Most wheat varieties are incapable of preventing FHB spread through the rachis, but disease is typically limited to individually infected spikelets in barley. We point-inoculated wheat lines possessing barley chromosome introgressions to test whether FHB resistance could be observed in a wheat genetic background. The most striking differential was between 4H(4D) substitution and 4H addition lines. The 4H addition line was similarly susceptible to the wheat parent, but the 4H(4D) substitution line was highly resistant, which suggests that there is an FHB susceptibility factor on wheat chromosome 4D. Point inoculation of Chinese Spring 4D ditelosomic lines demonstrated that removing 4DS results in high FHB resistance. We genotyped four Chinese Spring 4DS terminal deletion lines to better characterize the deletions in each line. FHB phenotyping indicated that lines del4DS-2 and del4DS-4, containing smaller deletions, were susceptible and had retained the susceptibility factor. Lines del4DS-3 and del4DS-1 contain larger deletions and were both significantly more resistant, and hence had presumably lost the susceptibility factor. Combining the genotyping and phenotyping results allowed us to refine the susceptibility factor to a 31.7 Mbp interval on 4DS.

Yield reduction historically associated with the Aegilops ventricosa 7DV introgression is genetically and physically distinct from the eyespot resistance gene Pch1.

KEY MESSAGE: Yield penalty and increased grain protein content traits associated with Aegilops ventricosa 7D introgression have been mapped for the first time, and they are physically distinct from the eyespot resistance locus Pch1. Wheat wild relatives represent an important source of genetic variation, but introgression of agronomically relevant genes, such as for disease resistance, may lead to the simultaneous introduction of genetically linked deleterious traits. Pch1 is a dominant gene, conferring resistance to eyespot and was introgressed to wheat from Aegilops ventricosa as part of a large segment of the 7DV chromosome. This introgression has been associated with a significant yield reduction and a concomitant increase in grain protein content. In this study, we evaluated both traits and their relationship to the location of the Pch1 gene. We found that both QTLs were clearly distinct from the Pch1 gene, being located on a different linkage group to Pch1. In addition, we found that the QTL for increased grain protein content was strong and consistent across field trials, whereas the yield penalty QTL was unstable and environmentally dependent. The yield and grain protein content QTLs were genetically linked and located in the same linkage group. This finding is due in part to the small size of the population, and to the restricted recombination between wheat 7D and Ae. ventricosa 7Dv chromosomes. Although recombination in this interval is rare, it does occur. A recombinant line containing Pch1 and 7D_KASP6, the marker associated with increase in grain protein content, but not Xwmc221, the marker associated with the yield penalty effect, was identified.

Urea Hydrolysis and Calcium Carbonate Precipitation in Gypsum-Amended Broiler Litter.

Broiler () litter is subject to ammonia (NH) volatilization losses. Previous work has shown that the addition of gypsum to broiler litter can increase nitrogen mineralization and decrease NH losses due to a decrease in pH, but the mechanisms responsible for these effects are not well understood. Therefore, three laboratory studies were conducted to evaluate the effect of gypsum addition to broiler litter on (i) urease activity at three water contents, (ii) calcium carbonate precipitation, and (iii) pH. The addition of gypsum to broiler litter increased ammonium concentrations ( < 0.0033) and decreased litter pH by 0.43 to 0.49 pH units after 5 d ( < 0.0001); however, the rate of urea hydrolysis in treated litter only increased on Day 0 for broiler litter with low (0.29 g HO g) and high (0.69 g HO g) water contents, and on Day 3 for litter with medium (0.40 g HO g) water content ( < 0.05). Amending broiler litter with gypsum also caused an immediate decrease in litter pH (0.22 pH units) due to the precipitation of calcium carbonate (CaCO) from gypsum-derived calcium and litter bicarbonate. Furthermore, as urea was hydrolyzed, more urea-derived carbon precipitated as CaCO in gypsum-treated litter than in untreated litter ( < 0.001). These results indicate that amending broiler litter with gypsum favors the precipitation of CaCO, which buffers against increases in litter pH that are known to facilitate NH volatilization.

Flue-gas desulfurization gypsum effects on urea-degrading bacteria and ammonia volatilization from broiler litter.

A major concern of the broiler industry is the volatilization of ammonia (NH3) from the mixture of bedding material and broiler excretion that covers the floor of broiler houses. Gypsum has been proposed as a litter amendment to reduce NH3 volatilization, but reports of NH3 abatement vary among studies and the mechanism responsible for decreasing NH3 volatilization is not well understood. The goal of this study was to evaluate the effect of adding 20 or 40% flue-gas desulfurization gypsum (FGDG) to broiler litter on pH, electrical conductivity (EC), water potential, urea-degrading bacteria abundance, NH3 and carbon dioxide (CO2) evolution, and nitrogen (N) mineralization in several 21-d experiments. The addition of FGDG to broiler litter increased EC by 24 to 33% (P < 0.0001), decreased urea-degrading bacteria by 48 to 57% (P = 0.0001) and increased N mineralization by 10 to 11% (P = 0.0001) as compared to litters not amended with FGDG. Furthermore, the addition of FGDG to broiler litter decreased NH3 volatilization by 18 to 28% (P < 0.0001), potentially resulting from the significantly lower litter pH values compared to un-amended litter (P < 0.0001). Findings of this study indicate that amending broiler litter with 20% FGDG can decrease NH3 volatilization and increase the fertlizer value of broiler litter.

Differential effects of lesion mimic mutants in barley on disease development by facultative pathogens.

Lesion mimic mutants display spontaneous necrotic spots and chlorotic leaves as a result of mis-regulated cell death programmes. Typically these mutants have increased resistance to biotrophic pathogens but their response to facultative fungi that cause necrotrophic diseases is less well studied. The effect of altered cell death regulation on the development of disease caused by Ramularia collo-cygni, Fusarium culmorum and Oculimacula yallundae was explored using a collection of barley necrotic (nec) lesion mimic mutants. nec8 mutants displayed lower levels of all three diseases compared to nec9 mutants, which had increased R. collo-cygni but decreased F. culmorum disease symptoms. nec1 mutants reduced disease development caused by both R. collo-cygni and F. culmorum. The severity of the nec1-induced lesion mimic phenotype and F. culmorum symptom development was reduced by mutation of the negative cell death regulator MLO. The significant reduction in R. collo-cygni symptoms caused by nec1 was completely abolished in the presence of the mlo-5 allele and both symptoms and fungal biomass were greater than in the wild-type. These results indicate that physiological pathways involved in regulation of cell death interact with one another in their effects on different fungal pathogens.

Contribution of the drought tolerance-related stress-responsive NAC1 transcription factor to resistance of barley to Ramularia leaf spot.

NAC proteins are plant transcription factors that are involved in tolerance to abiotic and biotic stresses, as well as in many developmental processes. Stress-responsive NAC1 (SNAC1) transcription factor is involved in drought tolerance in barley and rice, but has not been shown previously to have a role in disease resistance. Transgenic over-expression of HvSNAC1 in barley cv. Golden Promise reduced the severity of Ramularia leaf spot (RLS), caused by the fungus Ramularia collo-cygni, but had no effect on disease symptoms caused by Fusarium culmorum, Oculimacula yallundae (eyespot), Blumeria graminis f. sp. hordei (powdery mildew) or Magnaporthe oryzae (blast). The HvSNAC1 transcript was weakly induced in the RLS-susceptible cv. Golden Promise during the latter stages of R. collo-cygni symptom development when infected leaves were senescing. Potential mechanisms controlling HvSNAC1-mediated resistance to RLS were investigated. Gene expression analysis revealed no difference in the constitutive levels of antioxidant transcripts in either of the over-expression lines compared with cv. Golden Promise, nor was any difference in stomatal conductance or sensitivity to reactive oxygen species-induced cell death observed. Over-expression of HvSNAC1 delayed dark-induced leaf senescence. It is proposed that mechanisms controlled by HvSNAC1 that are involved in tolerance to abiotic stress and that inhibit senescence also confer resistance to R. collo-cygni and suppress RLS symptoms. This provides further evidence for an association between abiotic stress and senescence in barley and the development of RLS.

The moderating effect of control over work scheduling and overtime on the relationship between workload demands and perceived job risk.

BACKGROUND: This study investigated the impact of workload demands on perceived job risk using the Job Demand-Control model as a research framework. OBJECTIVE: The primary objective was to test the hypothesis that employee control over work scheduling and overtime would moderate the relationship between workload demands and perceived job risk. METHOD: Ninety-six participants working in a variety of industries completed measures of workload demands, and of control over work scheduling and overtime, and a measure of perceived job risk. RESULTS: Workload demands predicted higher perceptions of job risk. However, the results also suggest that control over overtime moderated this relationship, where those with the combination of high workload demands and low control over overtime reported higher levels of perceived risk. The results indicate that the JDC model is applicable to safety research. CONCLUSIONS: The results suggest that employee control over workload demands is an important variable to consider in terms of managing workplace safety. The present study also points to important areas for future research to explore in order to further understand the connection between demands and safety.

The relationship between recruitment processes, familiarity, trust, perceived risk and safety.

INTRODUCTION AND METHOD: Participants' perceptions of the safety-related aspects of their organization's recruitment processes were examined, as were their perceptions of safety aspects associated with new recruits. RESULTS: One hundred and fifty-four professional fire fighters indicated the trust they held in the safety-related aspects of their organizations' selection and pre-start training. Perceived trust in pre-start training was negatively correlated (r=-.24, p<.01) with the risk associated with new recruits, and positively correlated (r=.50, p<.01) with ratings of trust in recruits to immediately work safely. Furthermore, trust in recruits to immediately work safely was negatively correlated (r=-.21, p<.01) with crews' safety behavior toward recruits. CONCLUSIONS: These results are interpreted as particularly dangerous for workers, as new recruits lack familiarity with aspects of their new workplace that cannot be addressed by either selection or pre-start training, making them a risk. IMPACT ON INDUSTRY: Organizations should actively identify new recruits, and encourage existing team members not to immediately trust new recruits to work safely.

Investigating the structure of autobiographical memory using reaction times.

The study investigated the structure of autobiographical memory using reaction time measures. A total of 18 participants took photographs over their summer holidays and then reacted to pairs of these photographs displayed via a computer. They also subsequently sorted their photographs according to the autobiographical themes and events with which they were associated. When photographic sequence and the physical similarities in the photographs were controlled for by considering the results of "stranger" participants who were unfamiliar with the photographs, reaction times were significantly faster to pairs of photographs from the same theme or event. The results are consistent with currently held assumptions about the structure of autobiographical memory. Furthermore, the results suggest that reaction time measures may provide a valuable means by which aspects of autobiographical memory can be explored.

The identification of candidate genes associated with Pch2 eyespot resistance in wheat using cDNA-AFLP.

Eyespot is a fungal disease of the stem base of cereal crops and causes lodging and the premature ripening of grain. Wheat cultivar Cappelle Desprez contains a highly durable eyespot resistance gene, Pch2 on the long arm of chromosome 7A. A cDNA-amplified fragment length polymorphism (AFLP) platform was used to identify genes differentially expressed between the eyespot susceptible variety Chinese Spring (CS) and the CS chromosome substitution line Cappelle Desprez 7A (CS/CD7A) which contains Pch2. Induced and constitutive gene expression was examined to compare differences between non-infected and plants infected with Oculimacula acuformis. Only 34 of approximately 4,700 cDNA-AFLP fragments were differentially expressed between CS and CS/CD7A. Clones were obtained for 29 fragments, of which four had homology to proteins involved with plant defence responses. Fourteen clones mapped to chromosome 7A and three of these mapped in the region of Pch2 making them putative candidates for involvement in eyespot resistance. Of particular importance are two fragments; 4CD7A8 and 19CD7A4, which have homology to an Oryza sativa putative callose synthase protein and a putative cereal cyst nematode NBS-LRR disease resistance protein (RCCN) respectively. Differential expression associated with Pch2 was examined by semi-quantitative RT-PCR. Of those genes tested, only four were differentially expressed at 14 days post inoculation. We therefore suggest that a majority of the differences in the cDNA-AFLP profiles are due to allelic polymorphisms between CS and CD alleles rather than differences in expression.

Allocating time to future tasks: the effect of task segmentation on planning fallacy bias.

The scheduling component of the time management process was used as a "paradigm" to investigate the allocation of time to future tasks. In three experiments, we compared task time allocation for a single task with the summed time allocations given for each subtask that made up the single task. In all three, we found that allocated time for a single task was significantly smaller than the summed time allocated to the individual subtasks. We refer to this as the segmentation effect. In Experiment 3, we asked participants to give estimates by placing a mark on a time line, and found that giving time allocations in the form of rounded close approximations probably does not account for the segmentation effect. We discuss the results in relation to the basic processes used to allocate time to future tasks and the means by which planning fallacy bias might be reduced.

A test of the peak-end rule with extended autobiographical events.

Forty-nine students went on vacation for an average of 7 days and sent daily text messages about the happiness they had experienced over the previous 24 h. After their vacation, they were questioned on the overall happiness they had experienced and were asked to recall the daily record of their happiness. The duration of the vacation had no effect on the subsequent evaluations, and participants were not able to recall the detail of their day-to-day changes in happiness. A number of summary measures provided reasonable prediction of the recalled overall happiness of the vacation. The peak-end rule was not an outstandingly good predictor. Overall, the results indicate much reconstruction of the affective states.

Ordering the components of autobiographical events.

Memory for the temporal order of the components of autobiographical events was examined in two experiments. Experiments 1 and 2 examined the relationship between reaction times to recognise photographs of the components of events and ordering of these photographs. Reaction times were not related to true event position, nor to assigned temporal position, in a manner consistent with an activation strength model of temporal ordering. In contrast, ordering performance was found to be related to event vividness ratings, ability to classify a photograph as one the participant had taken, and retention interval. These findings are all consistent with the hypothesis that the order of an autobiographical event's components is determined by the associative structure that links each component to its general event memory. Overall, memory for the order of the components of autobiographical events may be initially based on associations between the event components and their general event memory representation. These associations appear to decay rapidly leaving only reconstructive ability as the determinant of event component order.

Memories of uncertain origin: dreamt or real?

The existence of a memory whose origin, real or dreamt, was uncertain was reported by just over half of an undergraduate sample of 358. Each respondent described one such memory if they had one. The memories were typically of mundane events, although 10 respondents described possible crimes. Respondents were often concerned to resolve the origin of these memories. Their plausibility, vividness, and how well the events fitted into one's life were often considered by the respondents, but where resolution occurred it was frequently based on evidence obtained from the physical or social environment. The reported qualities of the event did not correlate with whether the respondent thought it more likely to have been originally a dream or a real event.

Memory for true and false autobiographical event descriptions.

This study examined how participants respond to different types of false autobiographical event descriptions. Three attributes of autobiographical events (participant, location, and activity) were systematically altered to create different forms of false event description and these were examined, along with true events, to see if participants were more or less likely to rate the experience as remembered. The event attributes manipulated within false events systematically influenced the participant's memory ratings, and completely false events were the least likely to be identified as false. Mechanisms associated with access to autobiographical memory knowledge bases by which event attributes might cue an event as true or false are discussed.

Experimental manipulations of the phenomenology of memory.

We investigated the effects of visual input at encoding and retrieval on the phenomenology of memory. In Experiment 1, participants took part in events with and without wearing blindfolds, and later were shown a video of the events. Blindfolding, as well as later viewing of the video, both tended to decrease recollection. In Experiment 2, participants were played videos, with and without the visual component, of events involving other people. Events listened to without visual input were recalled with less recollection; later adding of the visual component increased recollection. In Experiment 3, participants were provided with progressively more information about events that they had experienced, either in the form of photographs that they had taken of the events or narrative descriptions of those photographs. In comparison with manipulations at encoding, the addition of more visual or narrative cues at recall had similar but smaller effects on recollection.

Themes, events, and episodes in autobiographical memory.

The process by which experience is divided into events was examined. Experiment 1 involved diarists recording their experiences over a 3-month period. Diary entries were later transcribed onto cards and the diarists arranged their cards so as to define events they had experienced, and in a separate phase arranged their cards so as to describe the themes that reflected their life. Examination of event- and theme-building strategies indicated that boundaries were frequently used, and events and themes were often formed from clusters of experience combined using content association rather than temporal sequence. Experiment 2 involved photographs taken by the participants, employed the same procedures as in Experiment 1, and revealed event- and theme-building strategies similar to those identified in Experiment 1. In Experiment 3 the size of the stimulus set from which events and themes were constructed was manipulated; this did not influence construction strategies. Overall, the experiments show that both autobiographical events and themes frequently consist of episodes taken from more than 1 day.