title: Geochemically defined space-for-time transects successfully capture microbial dynamics along lacustrine chronosequences in a polar desert

authors: Monteiro, Maria R.

subjects: Science & Technology

abstract: The space-for-time substitution approach provides a valuable empirical assessment to infer temporal effects of disturbance from spatial gradients. Applied to predict the response of different ecosystems under current climate change scenarios, it remains poorly tested in microbial ecology studies, partly due to the trophic complexity of the ecosystems typically studied. The McMurdo Dry Valleys (MDV) of Antarctica represent a trophically simple polar desert projected to experience drastic changes in water availability under current climate change scenarios. We used this ideal model system to develop and validate a microbial space-for-time sampling approach, using the variation of geochemical profiles that follow alterations in water availability and reflect past changes in the system. Our framework measured soil electrical conductivity, pH, and water activity in situ to geochemically define 17 space-for-time transects from the shores of four dynamic and two static Dry Valley lakes. We identified microbial taxa that are consistently responsive to changes in wetness in the soils and reliably associated with long-term dry or wet edaphic conditions. Comparisons between transects defined at static (open-basin) and dynamic (closed-basin) lakes highlighted the capacity for geochemically defined space-for-time gradients to identify lasting deterministic impacts of historical changes in water presence on the structure and diversity of extant microbial communities. We highlight the potential for geochemically defined space-for-time transects to resolve legacy impacts of environmental change when used in conjunction with static and dynamic scenarios, and to inform future environmental scenarios through changes in the microbial community structure, composition, and diversity.

text: Geochemically defined space-for-time transects successfully capture microbial dynamics along lacustrine chronosequences in a polar desert The space-for-time substitution approach provides a valuable empirical assessment to infer temporal effects of disturbance from spatial gradients. Applied to predict the response of different ecosystems under current climate change scenarios, it remains poorly tested in microbial ecology studies, partly due to the trophic complexity of the ecosystems typically studied. The McMurdo Dry Valleys (MDV) of Antarctica represent a trophically simple polar desert projected to experience drastic changes in water availability under current climate change scenarios. We used this ideal model system to develop and validate a microbial space-for-time sampling approach, using the variation of geochemical profiles that follow alterations in water availability and reflect past changes in the system. Our framework measured soil electrical conductivity, pH, and water activity in situ to geochemically define 17 space-for-time transects from the shores of four dynamic and two static Dry Valley lakes. We identified microbial taxa that are consistently responsive to changes in wetness in the soils and reliably associated with long-term dry or wet edaphic conditions. Comparisons between transects defined at static (open-basin) and dynamic (closed-basin) lakes highlighted the capacity for geochemically defined space-for-time gradients to identify lasting deterministic impacts of historical changes in water presence on the structure and diversity of extant microbial communities. We highlight the potential for geochemically defined space-for-time transects to resolve legacy impacts of environmental change when used in conjunction with static and dynamic scenarios, and to inform future environmental scenarios through changes in the microbial community structure, composition, and diversity.

year: 2022

title: Mass Spectral Characterisation of Three New Groups  of Algal Toxins

authors: Knudsen, Brent Kevin

subjects: pectenotoxin

abstract: This thesis reports the mass spectral identification and characterisation of three new groups of algal compounds.

A series of novel pectenotoxins (PTXs) were identified in retained sub-samples of Irish mussel extracts that had previously been utilised to obtain bulk quantities of some other algal toxins. The first eluting of the novel pectenotoxins, when analysed on a C-18 column using an MeCN-H2O gradient, afforded MNH4+ and MNa+ ions at m/z 864 and 869 respectively. This compound was designated as PTX-i. Three minor isomers (possibly storage artefacts) of the dominant PTX-i compound were also detected in the retained extracts, together with several later eluting sulfonated and sulfonated fatty acid ester analogues of PTX-i. The dominant fatty acid analogues were found to be the 16:0 esters. Sulfonated PTX-i isomers and their 16:0 fatty acid ester analogues showed strong m/z 925 and 1163 ion responses respectively in negative ion mode. High resolution mass spectrometry (HRMS) data showed the atomic composition of the m/z 925 ion to be C47H69O17S. Full scan, MS2, MS3 and MS4 mass spectral data determined in both positive and negative ion modes for the three series of PTX-i compounds was consistent with the proposal that they possessed a C5H11O3 side chain attached to C-35, rather than a 36-hemiacetal ring system as found in other known pectenotoxins, and that the sulfate and fatty acid residues were attached to two of the hydroxyl groups believed to present in the C5H11O3 side chain.

An algal water sample collected from Vigo, Spain (Dinophysis acuta, 12/12/05), that had previously been extracted with CH2Cl2 and Et2O, was found to contain low levels of two new pectenotoxin-2 seco acid (PTX-2SA) analogues that showed MNH4+ and MNa+ ions at m/z 896 and 901 respectively. Full scan, MS2, MS3 and MS4 mass spectral data determined in positive ion mode, in combination with NaBH4 and NaBD4 reduction reaction product data determined for PTX-2SA and the two new compounds, established that the new compounds were 14-hydroxy analogues of PTX-2SA.
The Spanish algal water sample also found to contain an appreciable level of two glycosides which were identified from a combination of full scan, MS2, MS3 and MS4 mass spectral data determined in both positive and negative ion modes as either 7- or 24-O-glycosides of okadaic acid (OA) and dinophysistoxin-2 (DTX-2), as MSn data excluded C-2 or C-27 O-glycosylation. 1D and 2D-1H NMR, obtained by co-workers while the mass spectral investigations reported in this thesis were in progress, showed that the glycosides were the 24-β-O-glucopyranosyl analogues of OA and DTX-2.

A set of three New Zealand derived algal water extracts, two from West Coast, South Island (Dinophysis acuta) and one from Akaroa Harbour (Dinophysis acuminata), were prepared and analysed for the three groups of new algal compounds reported in this thesis. PTX-i and its analogues were not detected in any of the New Zealand samples, the two 14-hydroxy PTX-2SA compounds were detected in one of the West Coast samples and the Akaroa Harbour samples and 24-O-glucoside OA and DTX-2 analogues were only detected in the Akaroa Harbour sample.

text: Mass Spectral Characterisation of Three New Groups  of Algal Toxins This thesis reports the mass spectral identification and characterisation of three new groups of algal compounds.

A series of novel pectenotoxins (PTXs) were identified in retained sub-samples of Irish mussel extracts that had previously been utilised to obtain bulk quantities of some other algal toxins. The first eluting of the novel pectenotoxins, when analysed on a C-18 column using an MeCN-H2O gradient, afforded MNH4+ and MNa+ ions at m/z 864 and 869 respectively. This compound was designated as PTX-i. Three minor isomers (possibly storage artefacts) of the dominant PTX-i compound were also detected in the retained extracts, together with several later eluting sulfonated and sulfonated fatty acid ester analogues of PTX-i. The dominant fatty acid analogues were found to be the 16:0 esters. Sulfonated PTX-i isomers and their 16:0 fatty acid ester analogues showed strong m/z 925 and 1163 ion responses respectively in negative ion mode. High resolution mass spectrometry (HRMS) data showed the atomic composition of the m/z 925 ion to be C47H69O17S. Full scan, MS2, MS3 and MS4 mass spectral data determined in both positive and negative ion modes for the three series of PTX-i compounds was consistent with the proposal that they possessed a C5H11O3 side chain attached to C-35, rather than a 36-hemiacetal ring system as found in other known pectenotoxins, and that the sulfate and fatty acid residues were attached to two of the hydroxyl groups believed to present in the C5H11O3 side chain.

An algal water sample collected from Vigo, Spain (Dinophysis acuta, 12/12/05), that had previously been extracted with CH2Cl2 and Et2O, was found to contain low levels of two new pectenotoxin-2 seco acid (PTX-2SA) analogues that showed MNH4+ and MNa+ ions at m/z 896 and 901 respectively. Full scan, MS2, MS3 and MS4 mass spectral data determined in positive ion mode, in combination with NaBH4 and NaBD4 reduction reaction product data determined for PTX-2SA and the two new compounds, established that the new compounds were 14-hydroxy analogues of PTX-2SA.
The Spanish algal water sample also found to contain an appreciable level of two glycosides which were identified from a combination of full scan, MS2, MS3 and MS4 mass spectral data determined in both positive and negative ion modes as either 7- or 24-O-glycosides of okadaic acid (OA) and dinophysistoxin-2 (DTX-2), as MSn data excluded C-2 or C-27 O-glycosylation. 1D and 2D-1H NMR, obtained by co-workers while the mass spectral investigations reported in this thesis were in progress, showed that the glycosides were the 24-β-O-glucopyranosyl analogues of OA and DTX-2.

A set of three New Zealand derived algal water extracts, two from West Coast, South Island (Dinophysis acuta) and one from Akaroa Harbour (Dinophysis acuminata), were prepared and analysed for the three groups of new algal compounds reported in this thesis. PTX-i and its analogues were not detected in any of the New Zealand samples, the two 14-hydroxy PTX-2SA compounds were detected in one of the West Coast samples and the Akaroa Harbour samples and 24-O-glucoside OA and DTX-2 analogues were only detected in the Akaroa Harbour sample.

year: 2009

title: Weaving Mātauranga Māori into climate change education with primary school students in New Zealand

authors: Jackson, Ryan

abstract: This thesis explores the integration of Indigenous knowledge, specifically mātauranga Māori, into climate change education for primary school children in Aotearoa (New Zealand). It engages with pūrākau (verbal narratives that encode knowledge) gifted by the local hapū (Rangitāne sub-tribe) to a kura (school). The study contributes to the growing body of research that addresses a gap in research and teaching practice, which, despite global calls for action, remains inconsistent in teaching at this age level or lacks direct curriculum guidance in Aotearoa.

The main question for this study was: In what ways can Rangitāne pūrākau engage and further the understanding of Year five and six ākonga (learners) in learning about climate change within a kura in the lower North Island of Aotearoa?

This research used a mix of different research methods to explore this question. A learning intervention wove a pūrākau, climate change concepts and kai (food) together to create a ten-week learning programme. This learning intervention was then implemented by a kaiako (teacher) with a group of 21 Year five and six ākonga. Data were collected using pre- and post-tests to assess what students learned during the learning intervention, a group interview with the ākonga to hear their voices in the study, and an interview with their kaiako to gain insights into how engaged the ākonga were, their opinion on their understandings, and how aspects of the intervention went.

Analysis of the findings shows that the use of pūrākau and other forms of mātauranga Māori helped ākonga connect deeply with the material, which contributed positively to their engagement and to them gaining a sound understanding of complex climate change concepts. The research suggests that presenting scientific information through a familiar cultural lens contributed to making the topic less confusing and easier for the ākonga to grasp. This approach not only helped to improve their understanding but also enhanced the mana of ākonga Māori and their connection to the whenua (the land).

This research has several main implications. The findings provide evidence that incorporating Indigenous knowledge has wider educational benefits in climate change education, supporting the body of research that states what works well for ākonga Māori works well for all learners. The research also highlighted the importance of the concept of ako, literally meaning ‘to teach and learn,’ as the kaiako showed strength in being able to learn alongside ākonga. The thesis supports the use of Indigenous knowledge systems such as pūrākau alongside Western knowledge systems to develop holistic learning experiences. A recommendation from this thesis is to further explore the development of a climate change education model, relevant to the context of Aotearoa, which would centralise Indigenous knowledge. This could be modelled in the form of a waka hourua (double hulled ocean voyaging canoe) with the tohunga (knowledge holder and expert) on board signifying the use of Indigenous knowledge systems, with narratives such as pūrākau, playing a part in climate change education.

text: Weaving Mātauranga Māori into climate change education with primary school students in New Zealand This thesis explores the integration of Indigenous knowledge, specifically mātauranga Māori, into climate change education for primary school children in Aotearoa (New Zealand). It engages with pūrākau (verbal narratives that encode knowledge) gifted by the local hapū (Rangitāne sub-tribe) to a kura (school). The study contributes to the growing body of research that addresses a gap in research and teaching practice, which, despite global calls for action, remains inconsistent in teaching at this age level or lacks direct curriculum guidance in Aotearoa.

The main question for this study was: In what ways can Rangitāne pūrākau engage and further the understanding of Year five and six ākonga (learners) in learning about climate change within a kura in the lower North Island of Aotearoa?

This research used a mix of different research methods to explore this question. A learning intervention wove a pūrākau, climate change concepts and kai (food) together to create a ten-week learning programme. This learning intervention was then implemented by a kaiako (teacher) with a group of 21 Year five and six ākonga. Data were collected using pre- and post-tests to assess what students learned during the learning intervention, a group interview with the ākonga to hear their voices in the study, and an interview with their kaiako to gain insights into how engaged the ākonga were, their opinion on their understandings, and how aspects of the intervention went.

Analysis of the findings shows that the use of pūrākau and other forms of mātauranga Māori helped ākonga connect deeply with the material, which contributed positively to their engagement and to them gaining a sound understanding of complex climate change concepts. The research suggests that presenting scientific information through a familiar cultural lens contributed to making the topic less confusing and easier for the ākonga to grasp. This approach not only helped to improve their understanding but also enhanced the mana of ākonga Māori and their connection to the whenua (the land).

This research has several main implications. The findings provide evidence that incorporating Indigenous knowledge has wider educational benefits in climate change education, supporting the body of research that states what works well for ākonga Māori works well for all learners. The research also highlighted the importance of the concept of ako, literally meaning ‘to teach and learn,’ as the kaiako showed strength in being able to learn alongside ākonga. The thesis supports the use of Indigenous knowledge systems such as pūrākau alongside Western knowledge systems to develop holistic learning experiences. A recommendation from this thesis is to further explore the development of a climate change education model, relevant to the context of Aotearoa, which would centralise Indigenous knowledge. This could be modelled in the form of a waka hourua (double hulled ocean voyaging canoe) with the tohunga (knowledge holder and expert) on board signifying the use of Indigenous knowledge systems, with narratives such as pūrākau, playing a part in climate change education.

year: 2025