title: Development of immunoaffinity columns and immunoassays for the collection, partial purification and measurement of sporidesmin A and its metabolites

authors: Briggs, Lyn R.

abstract: Monoclonal and polyclonal antibodies were produced for the development of competitive enzyme-linked immunosorbent assays (cELISA) for sporidesmin A, the mycotoxin that causes facial eczema in grazing livestock. Derivatives of sporidesmin conjugated to a number of proteins were used as immunising antigens and plate-coating antigens for cELISA. Two immunoassays, each detecting the presence of a different region of the sporidesmin A molecule have been developed. They allow the two major sporidesmins found in grass or in Pithomyces chartarum cultures to be distinguished. Organic solvent extraction of samples was avoided so that water-soluble metabolites could also be detected.

To assist in the selection of animals resistant to facial eczema, the cELISAs were applied to a study of the metabolism of sporidesmin A in sheep. The cELISAs distinguish between sporidesmin A and its metabolites, as one antibody detects only sporidesmin A and the other detects sporidesmin A and metabolites. After sheep were dosed with sporidesmin A it was possible to monitor the excretion of the toxin in bile and its metabolite(s) in both bile and urine using the appropriate cELISA. There were no differences between resistant and susceptible sheep in the cumulative totals or excretion rates of immunoreactive metabolite in animals dosed with sporidesmin A.

The detection of sporidesmin metabolites in sheep urine by cELISA was shown to have potential as a biomarker for measuring exposure to toxic pastures which could give early warning of the risk of facial eczema.

An immunoaffinity chromatography matrix was prepared by coupling antibody to cyanogen bromide-activated Sepharose. The matrix bound sporidesmin A and immunoreactive metabolites from urine, and bound analytes were eluted with 40% methanol in water. The matrix capacity for sporidesmin A was 900 ng of sporidesmin A bound per mL of matrix, and for sporidesmin metabolites from urine it was approximately 500 ng of sporidesmin A immunoreactive equivalents per mL of matrix.

A method was developed for the preparation of milk for immunoaffinity chromatography so that blocking of columns by milk fats was avoided. Sample concentration obtained using the immunoaffinity chromatography lowered the limit of quantification for the previously developed cELISA for sporidesmin A in milk by a factor of 100.

A trial was carried out to determine whether sporidesmin residues appeared in milk following experimental ingestion of the toxin. Using the cELISA, sporidesmin metabolites were detected in milk samples collected after dosing. Further evidence for the presence of immunoreactive material was obtained by using immunoaffinity chromatography to recover the material from milk. Positive results in the sporidesmin A specific cELISA suggest the presence of free sporidesmin A at picogram levels. Purification from a much larger sample, and analyses by HPLC and mass spectrometry are needed to confirm this result.

It should now be possible to use the anti-sporidesmin antibodies in immunochemical technologies and formats which are suitable for on-farm use. These could be used to help minimise exposure to sporidesmin A and provide an important advance in animal health.

text: Development of immunoaffinity columns and immunoassays for the collection, partial purification and measurement of sporidesmin A and its metabolites Monoclonal and polyclonal antibodies were produced for the development of competitive enzyme-linked immunosorbent assays (cELISA) for sporidesmin A, the mycotoxin that causes facial eczema in grazing livestock. Derivatives of sporidesmin conjugated to a number of proteins were used as immunising antigens and plate-coating antigens for cELISA. Two immunoassays, each detecting the presence of a different region of the sporidesmin A molecule have been developed. They allow the two major sporidesmins found in grass or in Pithomyces chartarum cultures to be distinguished. Organic solvent extraction of samples was avoided so that water-soluble metabolites could also be detected.

To assist in the selection of animals resistant to facial eczema, the cELISAs were applied to a study of the metabolism of sporidesmin A in sheep. The cELISAs distinguish between sporidesmin A and its metabolites, as one antibody detects only sporidesmin A and the other detects sporidesmin A and metabolites. After sheep were dosed with sporidesmin A it was possible to monitor the excretion of the toxin in bile and its metabolite(s) in both bile and urine using the appropriate cELISA. There were no differences between resistant and susceptible sheep in the cumulative totals or excretion rates of immunoreactive metabolite in animals dosed with sporidesmin A.

The detection of sporidesmin metabolites in sheep urine by cELISA was shown to have potential as a biomarker for measuring exposure to toxic pastures which could give early warning of the risk of facial eczema.

An immunoaffinity chromatography matrix was prepared by coupling antibody to cyanogen bromide-activated Sepharose. The matrix bound sporidesmin A and immunoreactive metabolites from urine, and bound analytes were eluted with 40% methanol in water. The matrix capacity for sporidesmin A was 900 ng of sporidesmin A bound per mL of matrix, and for sporidesmin metabolites from urine it was approximately 500 ng of sporidesmin A immunoreactive equivalents per mL of matrix.

A method was developed for the preparation of milk for immunoaffinity chromatography so that blocking of columns by milk fats was avoided. Sample concentration obtained using the immunoaffinity chromatography lowered the limit of quantification for the previously developed cELISA for sporidesmin A in milk by a factor of 100.

A trial was carried out to determine whether sporidesmin residues appeared in milk following experimental ingestion of the toxin. Using the cELISA, sporidesmin metabolites were detected in milk samples collected after dosing. Further evidence for the presence of immunoreactive material was obtained by using immunoaffinity chromatography to recover the material from milk. Positive results in the sporidesmin A specific cELISA suggest the presence of free sporidesmin A at picogram levels. Purification from a much larger sample, and analyses by HPLC and mass spectrometry are needed to confirm this result.

It should now be possible to use the anti-sporidesmin antibodies in immunochemical technologies and formats which are suitable for on-farm use. These could be used to help minimise exposure to sporidesmin A and provide an important advance in animal health.

year: 1997

title: The effects of climate change on the benthic community in a temperate fjord

authors: Shellem, Claire T.

abstract: Climate change exerts a profound impact on marine ecosystems, with coastal environments uniquely affected by both oceanic and terrestrial influences. In coastal areas, oceanic drivers, such as rising temperatures and altered circulation patterns, combine with terrestrial inputs like changes in freshwater inflow to create unique environmental conditions. Beyond the gradual warming of ocean temperatures, the increasing occurrence of extreme temperature anomalies poses considerable threats to ecosystem stability, necessitating detailed investigations into their underlying mechanisms and ecological consequences. This thesis focuses on how climate change manifests in Doubtful Sound, a temperate fjord characterized by rocky subtidal benthic communities.
First, using an 18-year high resolution dataset, I investigate the spatiotemporal trends in temperature and salinity throughout Doubtful Sound. I analyse the fjord’s temperature dynamics spatially, spanning from 0.5 m to 19 m and from the inner fjord to outer fjord. Linked with climate change, I identify increasing mean temperatures and increases in temperature anomalies. Furthermore, I report the occurrence of two marine heatwaves in Doubtful Sound. Lastly, I note a deepening of the low salinity layer, a key physical feature that drives the structure and stability of benthic communities in this fjord.
Coupled with these oceanographic analyses, I explore spatial and temporal drivers of the benthic communities in Doubtful Sound. I document higher diversity and variability in the outer sites as compared to the inner sites. Additionally outer fjord communities show significant shifts in benthic community composition through time, while the inner fjord communities remain largely constant. Though a range of factors influence the abundance of benthic organisms including biotic interactions, salinity levels and physical disturbance, thermal profiles provide insights into the potential sensitivity of taxa to warming oceans. By linking benthic abundance with temperature trends, I identify potential thermal thresholds for several key taxa. In the shallow waters for example, barnacles and mussels peak in abundance at 15.5-16 °C and sharply decline in higher temperatures. Conversely, encrusting sponges increase dramatically in response to warming temperatures. Lastly, I investigate the role of the 2018 Tasman Sea marine heatwave in structuring the benthic community in Doubtful Sound. Minimal impacts on the benthic community after the heatwave were recorded, although notable increases in green algae and encrusting sponge were observed at two sites.
The final chapter of this thesis investigates how environmental changes associated with climate change, specifically increased temperature and decreased salinity, influence the fitness of Coscinasterias muricata, a keystone predator in Fiordland’s subtidal ecosystems. I designed a laboratory experiment to identify the effects of temperature, salinity, and the interaction between the two on the fitness of C. muricata. Righting trials, a well-established proxy for fitness, were carried out to investigate the effects of altered physical conditions. Interestingly, only salinity had a significant effect on C. muricata fitness, highlighting the potential of low salinity events to affect benthic communities in estuarine environments.
Overall, this thesis underscores the multifaceted impacts of climate change on fjord ecosystems, emphasizing the importance of physical anomalies beyond increases in mean temperature. These findings highlight how increasing anomalies and shifts in temperature and salinity regimes can profoundly influence the structure and dynamics of benthic communities. By integrating long term environmental data with experimental insights, this work advances our understanding of the complex interactions between climatic drivers and ecological responses, providing critical perspectives on the vulnerability and resilience of temperate fjord ecosystems under changing physical conditions.

text: The effects of climate change on the benthic community in a temperate fjord Climate change exerts a profound impact on marine ecosystems, with coastal environments uniquely affected by both oceanic and terrestrial influences. In coastal areas, oceanic drivers, such as rising temperatures and altered circulation patterns, combine with terrestrial inputs like changes in freshwater inflow to create unique environmental conditions. Beyond the gradual warming of ocean temperatures, the increasing occurrence of extreme temperature anomalies poses considerable threats to ecosystem stability, necessitating detailed investigations into their underlying mechanisms and ecological consequences. This thesis focuses on how climate change manifests in Doubtful Sound, a temperate fjord characterized by rocky subtidal benthic communities.
First, using an 18-year high resolution dataset, I investigate the spatiotemporal trends in temperature and salinity throughout Doubtful Sound. I analyse the fjord’s temperature dynamics spatially, spanning from 0.5 m to 19 m and from the inner fjord to outer fjord. Linked with climate change, I identify increasing mean temperatures and increases in temperature anomalies. Furthermore, I report the occurrence of two marine heatwaves in Doubtful Sound. Lastly, I note a deepening of the low salinity layer, a key physical feature that drives the structure and stability of benthic communities in this fjord.
Coupled with these oceanographic analyses, I explore spatial and temporal drivers of the benthic communities in Doubtful Sound. I document higher diversity and variability in the outer sites as compared to the inner sites. Additionally outer fjord communities show significant shifts in benthic community composition through time, while the inner fjord communities remain largely constant. Though a range of factors influence the abundance of benthic organisms including biotic interactions, salinity levels and physical disturbance, thermal profiles provide insights into the potential sensitivity of taxa to warming oceans. By linking benthic abundance with temperature trends, I identify potential thermal thresholds for several key taxa. In the shallow waters for example, barnacles and mussels peak in abundance at 15.5-16 °C and sharply decline in higher temperatures. Conversely, encrusting sponges increase dramatically in response to warming temperatures. Lastly, I investigate the role of the 2018 Tasman Sea marine heatwave in structuring the benthic community in Doubtful Sound. Minimal impacts on the benthic community after the heatwave were recorded, although notable increases in green algae and encrusting sponge were observed at two sites.
The final chapter of this thesis investigates how environmental changes associated with climate change, specifically increased temperature and decreased salinity, influence the fitness of Coscinasterias muricata, a keystone predator in Fiordland’s subtidal ecosystems. I designed a laboratory experiment to identify the effects of temperature, salinity, and the interaction between the two on the fitness of C. muricata. Righting trials, a well-established proxy for fitness, were carried out to investigate the effects of altered physical conditions. Interestingly, only salinity had a significant effect on C. muricata fitness, highlighting the potential of low salinity events to affect benthic communities in estuarine environments.
Overall, this thesis underscores the multifaceted impacts of climate change on fjord ecosystems, emphasizing the importance of physical anomalies beyond increases in mean temperature. These findings highlight how increasing anomalies and shifts in temperature and salinity regimes can profoundly influence the structure and dynamics of benthic communities. By integrating long term environmental data with experimental insights, this work advances our understanding of the complex interactions between climatic drivers and ecological responses, providing critical perspectives on the vulnerability and resilience of temperate fjord ecosystems under changing physical conditions.

year: 2025

title: Niupepa: A historical newspaper collection

authors: Apperley, Mark

abstract: Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

text: Niupepa: A historical newspaper collection Niupepa is a collection of 42 newspaper titles published in New Zealand from 1842-1933, comprising a total of 21,000 pages in 1,750 issues. This collection forms a unique historical record of the language of the indigenous Mãori people, the evolution of the written form of this language, and of events and developments during the formative colonial history of our country. Using the Greenstone software from the New Zealand Digital Library this collection is now publicly available with full-text search capability.

year: 2001-05-01