title: Lignin oxidation products in soil, dripwater and speleothems from four different sites in New Zealand

authors: Heidke, Inken

abstract: Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, Σ8, provides information on the abundance of vegetation, while the ratios C/V and S/V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C/V and S/V ratios, and thus complicate their interpretation in terms of past vegetation changes. We analyzed LOPs in leaf litter and different soil horizons as well as dripwater and flowstone samples from four different cave sites from different vegetation zones in New Zealand using ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry. We test whether the original source-dependent LOP signal of the overlying vegetation is preserved and can be recovered from flowstone samples and investigate how the signal is altered by the transport from the soil to the cave. The LOP concentrations range from mg g−1 in the soil to ng g−1 in the flowstones. Our results demonstrate that, from the soil to the flowstone, the C/V and S/V ratios both increase, while the total lignin content, Σ8, strongly decreases. This shows that the LOP signal is strongly influenced by both transport and degradation processes. Nevertheless, the relative LOP signal from the overlying soil at the different cave sites is preserved in the flowstone. We emphasize that for the interpretation of C/V and S/V ratios in terms of past vegetation changes, it is important to compare only samples of the same type (e.g., speleothem, dripwater or soil) and to evaluate only relative variations.

text: Lignin oxidation products in soil, dripwater and speleothems from four different sites in New Zealand Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, Σ8, provides information on the abundance of vegetation, while the ratios C/V and S/V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C/V and S/V ratios, and thus complicate their interpretation in terms of past vegetation changes. We analyzed LOPs in leaf litter and different soil horizons as well as dripwater and flowstone samples from four different cave sites from different vegetation zones in New Zealand using ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry. We test whether the original source-dependent LOP signal of the overlying vegetation is preserved and can be recovered from flowstone samples and investigate how the signal is altered by the transport from the soil to the cave. The LOP concentrations range from mg g−1 in the soil to ng g−1 in the flowstones. Our results demonstrate that, from the soil to the flowstone, the C/V and S/V ratios both increase, while the total lignin content, Σ8, strongly decreases. This shows that the LOP signal is strongly influenced by both transport and degradation processes. Nevertheless, the relative LOP signal from the overlying soil at the different cave sites is preserved in the flowstone. We emphasize that for the interpretation of C/V and S/V ratios in terms of past vegetation changes, it is important to compare only samples of the same type (e.g., speleothem, dripwater or soil) and to evaluate only relative variations.

year: 2021

title: Enzyme activity and flexibility at very low hydration

authors: Kurkal, Vandana

abstract: Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. This raises the question of whether hydration-induced enzyme flexibility is important for activity. Here, to address this, picosecond dynamic neutron scattering experiments are performed on pig liver esterase powders at 0%, 3%, 12%, and 50% hydration by weight and at temperatures ranging from 120 to 300 K. At all temperatures and hydrations, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases, a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. The implication of these results is that, although the additional hydration-induced diffusive motion in the protein detected here may be related to increased activity, it is not required for the enzyme to function.

text: Enzyme activity and flexibility at very low hydration Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. This raises the question of whether hydration-induced enzyme flexibility is important for activity. Here, to address this, picosecond dynamic neutron scattering experiments are performed on pig liver esterase powders at 0%, 3%, 12%, and 50% hydration by weight and at temperatures ranging from 120 to 300 K. At all temperatures and hydrations, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases, a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. The implication of these results is that, although the additional hydration-induced diffusive motion in the protein detected here may be related to increased activity, it is not required for the enzyme to function.

year: 2005-05

title: Wāhine Māori engagement with literacies

authors: Masters-Awatere, Bridgette

subjects: Literacy

abstract: Wāhine Māori engagement with literacies (2023) is a case study report in collaboration with Te Whakaruruhau. It has been undertaken as part of a larger project, The expression, experience and transcendence of low skills in Aotearoa New Zealand (2019–2024), the aim of which is to provide policy recommendations to improve life-course trajectories and socio-economic outcomes for adults with low literacy and numeracy skills in Aotearoa New Zealand. Broadly speaking, Wāhine Māori engagement with literacy examines the framing and application of literacy measures in contemporary New Zealand culture. More specifically, it is about the lives and learning of wāhine (women) Māori (the indigenous peoples of Aotearoa New Zealand) within that culture and their attitudes towards, and complex relationships with, literacy as it is defined in their own lives and in the current setting. The study aims for a holistic understanding of lived literacies in driving the development of educational policies by public institutions and private groups. Reframing literacy as literacies is posited as a means to empower marginalised groups and to challenge the dominance of the Eurocentric education paradigm. Formal learning in English-language schools cannot be the extent of national literacy standards as it disregards Māori epistemological and ontological realities and can discount wāhine, many of whom may prioritise other modes of literacy. Centring their perspectives will bring about a more culturally inclusive future, one that makes space for the development of emotional and cultural literacies—as well as other forms such as digital, media, visual, financial, and health literacies—alongside the conventional version of literacy that has a monopoly in the present system.

text: Wāhine Māori engagement with literacies Wāhine Māori engagement with literacies (2023) is a case study report in collaboration with Te Whakaruruhau. It has been undertaken as part of a larger project, The expression, experience and transcendence of low skills in Aotearoa New Zealand (2019–2024), the aim of which is to provide policy recommendations to improve life-course trajectories and socio-economic outcomes for adults with low literacy and numeracy skills in Aotearoa New Zealand. Broadly speaking, Wāhine Māori engagement with literacy examines the framing and application of literacy measures in contemporary New Zealand culture. More specifically, it is about the lives and learning of wāhine (women) Māori (the indigenous peoples of Aotearoa New Zealand) within that culture and their attitudes towards, and complex relationships with, literacy as it is defined in their own lives and in the current setting. The study aims for a holistic understanding of lived literacies in driving the development of educational policies by public institutions and private groups. Reframing literacy as literacies is posited as a means to empower marginalised groups and to challenge the dominance of the Eurocentric education paradigm. Formal learning in English-language schools cannot be the extent of national literacy standards as it disregards Māori epistemological and ontological realities and can discount wāhine, many of whom may prioritise other modes of literacy. Centring their perspectives will bring about a more culturally inclusive future, one that makes space for the development of emotional and cultural literacies—as well as other forms such as digital, media, visual, financial, and health literacies—alongside the conventional version of literacy that has a monopoly in the present system.

year: 2023-09-28