Modelling catchment management impact on in-stream phosphorus loads in northern Victoria.

Phosphorus pollution severely impairs the water quality of rivers in Australia and worldwide. Conceptual models have proved useful to assess management impact on phosphorus loads, particularly in data-sparse environments. This paper develops and evaluates the coupling of a point-scale model (HowLeaky2008) to a catchment scale model (CatchMODS) to enhance modelling of farm management impacts on in-stream phosphorus loads. The model was tested in two adjacent catchments in northern Victoria (Avon-Richardson and Avoca), Australia. After calibration of the in-stream attenuation parameter against measurements at gauging stations, the model simulated specific annual phosphorus loads across the catchments well (Nash-Sutcliffe model efficiency of 0.52 in the Avon-Richardson and 0.83 for the Avoca catchment). Phosphorus loads at both catchment outlets under current conditions were estimated at 7 t y(-1) and were dominated by field exports. Changes to farm management practices, i.e. the use of perennial pastures in grazing systems and zero-tillage in cropping systems were estimated to reduce phosphorus load by 31% in the Avon-Richardson catchment and 19% in the Avoca catchment, relative to current practices (annual pasture and minimum tillage). The model afforded a major improvement in conceptual modelling by explicit simulation of the impacts of soil and climatic conditions on field-scale exports and by placing them in the context of landscape processes.

Measurement of IgE antibodies against purified grass pollen allergens (Lol p 1, 2, 3 and 5) during immunotherapy.

BACKGROUND: IgE titres tend to rise early after the start of immunotherapy, followed by a decline to pre-immunotherapy levels or lower. OBJECTIVES: We were interested to know whether the early increase in IgE antibodies includes new specificities of IgE, and whether these responses persist. METHODS: Sera of 64 patients undergoing grass pollen immunotherapy were tested for IgE against four purified grass pollen allergens: Lol p 1, 2, 3, and 5. At least two serum samples were taken, one before the start of therapy and one between 5 and 18 months after the first immunization (mean: 10 months). RESULTS: The mean IgE responses to Lol p 1, 2 and 3 showed a moderate but not significant increase. In contrast, the mean IgE response to Lol p 5 showed a significant decrease of > 30%. IgE against total Lohum perenne pollen extract moderately increased (> 20%), showing that a RAST for total pollen is not always indicative for the development of IgE against its major allergens. For > 40% of the patients it was found that IgE against one or more of the four allergens increased, while IgE against the remaining allergen(s) decreased. For 10 sera the ratio of IgE titres against at least two allergens changed by at least a factor of 5. The changes in specific IgE also included conversions from negative (< 0.1 RU) to positive (0.6 to 5.0 RU) for five patients. For two patients, the induction of these 'new' IgE antibodies against major allergens was shown to result in a response that was persistent over several years. CONCLUSION: Although active induction of new IgE specificities by immunotherapy was not really proven, the observations in this study indicate that monitoring of IgE against purified (major) allergens is necessary to evaluate changes in specific IgE in a reliable way.

Nucleotide sequence of cDNA encoding the group II allergen of cocksfoot/orchard grass (Dactylis glomerata), Dac g II.

Cocksfoot/orchard grass (Dactylis glomerata) anther cDNA clones encoding the group II allergen Dac g II were previously isolated on the basis of immunoreactivity of human, rabbit, and murine antibodies with a 24-kDa protein expressed as a fusion protein with beta-galactosidase. Nucleotide sequencing reveals an open reading frame predicting expression of a 98-amino-acid (11-kDa) polypeptide exhibiting > 90% homology with the group II allergen of Lolium perenne, Lol p II. In vitro translation of different sized clone fragments generated by polymerase chain amplification confirms eukaryotic expression of a 10-12-kDa polypeptide by SDS-PAGE and the position of a translational stop apparently unrecognized during expression of lambda gt11 in E. coli. The unusual characteristics of the prokaryote-expressed fusion proteins may be exerting conformational alterations in Dac g II, as reflected by previous demonstrations of differences in human IgE immunoreactivity. Northern blot analysis using PCR-generated partial and full-length probes suggests that group II allergens may be encoded by a different family or families of temporally expressed genes from those encoding group I major allergens, although a group I gene may have been the progenitor.

Recombinant pollen allergens from Dactylis glomerata: preliminary evidence that human IgE cross-reactivity between Dac g II and Lol p I/II is increased following grass pollen immunotherapy.

We previously described the isolation of three identical complementary DNA (cDNA) clones, constructed from Orchard/Cocksfoot grass (Dactylis glomerata) anther messenger RNA (mRNA), expressing a 140,000 MW beta-galactosidase fusion protein recognized by IgE antibodies in atopic sera. Partial nucleotide sequencing and inferred amino acid sequence showed greater than 90% homology with the group II allergen from Lolium perenne (Lol II) indicating they encode the group II equivalent, Dac g II. Western blot immunoprobing of recombinant lysates with rabbit polyclonal, mouse monoclonal and human polyclonal antisera demonstrates immunological identity between recombinant Dac g II, Lol p I and Lol p II. Similar cross-identity is observed with pollen extracts from three other grass species: Festuca rubra, Phleum pratense and Anthoxanthum odoratum. Recombinant Dac g II was recognized by species- and group-cross-reactive human IgE antibodies in 33% (4/12) of sera randomly selected from grass-sensitive individuals and in 67% (14/21) of sera from patients receiving grass pollen immunotherapy, whilst 0/4 sera from patients receiving venom immunotherapy alone contained Dac g II cross-reactive IgE. Cross-reactive IgG4 antibodies were detectable in 95% of sera from grass pollen immunotherapy patients. These preliminary data suggest that conventional grass pollen allergoid desensitization immunotherapy may induce IgE responses to a cross-reactive epitope(s) co-expressed by grass pollen groups I and II (and possibly group III) allergens.

N-terminal amino acid sequence homologies of group V grass pollen allergens.

In an earlier study, we presented data regarding the immunoaffinity purification and N-terminal sequencing of a major pollen allergen from orchard/cocks-foot grass (Dactylis glomerata), now identified as the group V allergen Dac g V. In this paper, we have extended our investigations to include group V allergens from other grass species. Our data confirm the presence of group V-restricted characteristic N-terminal amino acid sequences containing a high alanine and hydroxyproline (P') rather than proline (P) content, and based upon two conserved elements (ADAGY and TPA/TP'A).