title: Stratigraphy and chronology of a 15ka sequence of multi-sourced silicic tephras in a montane peat bog, eastern North Island, New Zealand.

authors: Lowe, David J.

subjects: tephra

abstract: We document the stratigraphy, composition, and chronology of a succession of 16 distal, silicic tephra layers interbedded with lateglacial and Holocene peats and muds up to c. 15 000 radiocarbon years (c. 18 000 calendar years) old at a montane site (Kaipo Bog) in eastern North Island, New Zealand. Aged from 665 +/- 15 to 14 700 +/- 95 14C yr BP, the tephras are derived from six volcanic centres in North Island, three of which are rhyolitic (Okataina, Taupo, Maroa), one peralkaline (Tuhua), and two andesitic (Tongariro, Egmont). Correlations are based on multiple criteria: field properties and stratigraphic interrelationships, ferromagnesian silicate mineral assemblages, glass-shard major element composition (from electron microprobe analysis), and radiocarbon dating. We extend the known distribution of tephras in eastern North Island and provide compositional data that add to their potential usefulness as isochronous markers. The chronostratigraphic framework established for the Kaipo sequence, based on both site-specific and independently derived tephra-based radiocarbon ages, provides the basis for fine-resolution paleoenvironmental studies at a climatically sensitive terrestrial site from the mid latitudes of the Southern Hemisphere. Tephras identified as especially useful paleoenvironmental markers include Rerewhakaaitu and Waiohau (lateglacial), Konini (lateglacial-early Holocene), Tuhua (middle Holocene), and Taupo and Kaharoa (late Holocene).

text: Stratigraphy and chronology of a 15ka sequence of multi-sourced silicic tephras in a montane peat bog, eastern North Island, New Zealand. We document the stratigraphy, composition, and chronology of a succession of 16 distal, silicic tephra layers interbedded with lateglacial and Holocene peats and muds up to c. 15 000 radiocarbon years (c. 18 000 calendar years) old at a montane site (Kaipo Bog) in eastern North Island, New Zealand. Aged from 665 +/- 15 to 14 700 +/- 95 14C yr BP, the tephras are derived from six volcanic centres in North Island, three of which are rhyolitic (Okataina, Taupo, Maroa), one peralkaline (Tuhua), and two andesitic (Tongariro, Egmont). Correlations are based on multiple criteria: field properties and stratigraphic interrelationships, ferromagnesian silicate mineral assemblages, glass-shard major element composition (from electron microprobe analysis), and radiocarbon dating. We extend the known distribution of tephras in eastern North Island and provide compositional data that add to their potential usefulness as isochronous markers. The chronostratigraphic framework established for the Kaipo sequence, based on both site-specific and independently derived tephra-based radiocarbon ages, provides the basis for fine-resolution paleoenvironmental studies at a climatically sensitive terrestrial site from the mid latitudes of the Southern Hemisphere. Tephras identified as especially useful paleoenvironmental markers include Rerewhakaaitu and Waiohau (lateglacial), Konini (lateglacial-early Holocene), Tuhua (middle Holocene), and Taupo and Kaharoa (late Holocene).

year: 1999-12-01

title: Identifying the signalling pathway of a novel  Myostatin Splice Variant (MSV)

authors: Hennebry, Alex

subjects: myostatin

abstract: Myostatin (Mstn), a member of the transforming growth factor-β super family, is a potent negative regulator of skeletal muscle mass. Studies delineating the function of Mstn have identified multiple signal transduction pathways that convey the Mstn signal. Mstn has been shown to influence canonical TGF-β, mitogen activated protein kinase (MAPK) and the PI3K/AKT signal transduction cascades. The discovery in our laboratory of a novel splice variant of Mstn (MSV) that opposes Mstn and stimulates the proliferation of myoblasts provided the impetus for the investigations in this thesis. The splicing of MSV was restricted to the Cetartiodactyl clade of mammals, and MSV may represent an intragenic regulator of Mstn. Thus, the studies undertaken in this thesis were to delineate the signalling pathways used by Mstn and MSV in order to understand how their opposing roles in myoblasts regulate myogenesis.
Initially, microarray analysis was used to investigate the transcriptional responses of ovine myoblasts following exposure to recombinant Mstn (eukaryotic) and MSV (prokaryotic) protein. Mstn treatment induced changes in number of transcripts, with changes consistent with previous investigations, for example increased interlukin-6 (IL6) and decreased MyoD. In addition, a novel transcriptional target of Mstn, the β1 subunit of the Na⁺-K⁺-ATPase was discovered. Treatment of ovine myoblasts with recombinant MSV induced a plethora of transcriptional responses. IPA analysis suggested a number of these were due to LPS (endotoxin) contamination, which could be attributed to the production of this protein in E. coli. This was confirmed using the Limulus amebocyte lysate assay. Phase separation using Triton-X 114 proved an effective method for the removal of LPS from the MSV preparation.
Western blot analysis was performed following the treatment of ovine myoblasts with Mstn and purified MSV. Consistent with previous myoblast studies Mstn stimulated canonical TGF-β (Smad) signalling and the p38 and ERK components of the MAPK signalling cascade. In contrast to previous studies, Mstn also stimulated AKT signalling, with specific phosphorylation of serine 473 (AKTS⁴⁷³). In addition, Mstn altered the abundance of multiple myogenic transcription factors (MyoD, Myf5, MRF4, Pax7 and Mef2) and the abundance and/or the phosphorylation of targets that have a metabolic role in skeletal muscle (rps6, 4EBP1 and p70S6K). Treatment with MSV increased the abundance of Smad 3, Myf5, 4EBP1 and stimulated AKTS⁴⁷³and 4EBP1 phosphorylation. These data provided the foundation for confirmation of these pathways targeted by MSV in C₂C₁₂ myoblasts that stably expressed MSV.
C₂C₁₂ cells expressing MSV had an increased proliferative capacity and showed increased mitochondrial activity (EZ4U assay) as compared to controls. These cells showed an increased abundance of the MRFs MyoD, MRF4 and Myogenin and an increased abundance or phosphorylation of signalling targets involved in canonical TGF-β, MAPK and PI3K/AKT signalling cascades. In addition, cells expressing MSV had an increased abundance and phosphorylation of acetyl co-enzyme A carboxylase (ACC) and 4EBP1, which have established roles in regulating metabolism and the synthesis of protein.
The significant overlap of processes influenced by the Na⁺ , K⁺ ATPase complex and Mstn prompted an investigation on how Mstn regulates the β1 subunit of the Na⁺ , K⁺ ATPase. This transcriptional response was found to be dependent on the Smad pathway. In addition, these studies also show that Na⁺ K⁺ ATPase activity plays a role in proliferation and differentiation of ovine myoblasts and suggest that Mstn inhibits ion flow controlled through the function of this enzyme complex. 
In conclusion, these studies show that Mstn and MSV share a number of common signalling targets. In contrast to previous studies of Mstn, the stable expression MSV increases the activation of AKT signalling and increases the abundance of key myogenic transcription factors. In addition, MSV increases the abundance and phosphorylation of ACC and 4EBP1, molecules involved regulating the synthesis of protein and fatty acids. In addition, the β1 subunit of the Na⁺ K⁺ ATPase, was identified as a novel transcriptional target of Mstn, with this regulation controlled through a Smad dependant mechanism. These data confirm the postulate that Mstn and MSV have divergent signalling functions and suggest a role for MSV in the control of oxidative metabolism.

text: Identifying the signalling pathway of a novel  Myostatin Splice Variant (MSV) Myostatin (Mstn), a member of the transforming growth factor-β super family, is a potent negative regulator of skeletal muscle mass. Studies delineating the function of Mstn have identified multiple signal transduction pathways that convey the Mstn signal. Mstn has been shown to influence canonical TGF-β, mitogen activated protein kinase (MAPK) and the PI3K/AKT signal transduction cascades. The discovery in our laboratory of a novel splice variant of Mstn (MSV) that opposes Mstn and stimulates the proliferation of myoblasts provided the impetus for the investigations in this thesis. The splicing of MSV was restricted to the Cetartiodactyl clade of mammals, and MSV may represent an intragenic regulator of Mstn. Thus, the studies undertaken in this thesis were to delineate the signalling pathways used by Mstn and MSV in order to understand how their opposing roles in myoblasts regulate myogenesis.
Initially, microarray analysis was used to investigate the transcriptional responses of ovine myoblasts following exposure to recombinant Mstn (eukaryotic) and MSV (prokaryotic) protein. Mstn treatment induced changes in number of transcripts, with changes consistent with previous investigations, for example increased interlukin-6 (IL6) and decreased MyoD. In addition, a novel transcriptional target of Mstn, the β1 subunit of the Na⁺-K⁺-ATPase was discovered. Treatment of ovine myoblasts with recombinant MSV induced a plethora of transcriptional responses. IPA analysis suggested a number of these were due to LPS (endotoxin) contamination, which could be attributed to the production of this protein in E. coli. This was confirmed using the Limulus amebocyte lysate assay. Phase separation using Triton-X 114 proved an effective method for the removal of LPS from the MSV preparation.
Western blot analysis was performed following the treatment of ovine myoblasts with Mstn and purified MSV. Consistent with previous myoblast studies Mstn stimulated canonical TGF-β (Smad) signalling and the p38 and ERK components of the MAPK signalling cascade. In contrast to previous studies, Mstn also stimulated AKT signalling, with specific phosphorylation of serine 473 (AKTS⁴⁷³). In addition, Mstn altered the abundance of multiple myogenic transcription factors (MyoD, Myf5, MRF4, Pax7 and Mef2) and the abundance and/or the phosphorylation of targets that have a metabolic role in skeletal muscle (rps6, 4EBP1 and p70S6K). Treatment with MSV increased the abundance of Smad 3, Myf5, 4EBP1 and stimulated AKTS⁴⁷³and 4EBP1 phosphorylation. These data provided the foundation for confirmation of these pathways targeted by MSV in C₂C₁₂ myoblasts that stably expressed MSV.
C₂C₁₂ cells expressing MSV had an increased proliferative capacity and showed increased mitochondrial activity (EZ4U assay) as compared to controls. These cells showed an increased abundance of the MRFs MyoD, MRF4 and Myogenin and an increased abundance or phosphorylation of signalling targets involved in canonical TGF-β, MAPK and PI3K/AKT signalling cascades. In addition, cells expressing MSV had an increased abundance and phosphorylation of acetyl co-enzyme A carboxylase (ACC) and 4EBP1, which have established roles in regulating metabolism and the synthesis of protein.
The significant overlap of processes influenced by the Na⁺ , K⁺ ATPase complex and Mstn prompted an investigation on how Mstn regulates the β1 subunit of the Na⁺ , K⁺ ATPase. This transcriptional response was found to be dependent on the Smad pathway. In addition, these studies also show that Na⁺ K⁺ ATPase activity plays a role in proliferation and differentiation of ovine myoblasts and suggest that Mstn inhibits ion flow controlled through the function of this enzyme complex. 
In conclusion, these studies show that Mstn and MSV share a number of common signalling targets. In contrast to previous studies of Mstn, the stable expression MSV increases the activation of AKT signalling and increases the abundance of key myogenic transcription factors. In addition, MSV increases the abundance and phosphorylation of ACC and 4EBP1, molecules involved regulating the synthesis of protein and fatty acids. In addition, the β1 subunit of the Na⁺ K⁺ ATPase, was identified as a novel transcriptional target of Mstn, with this regulation controlled through a Smad dependant mechanism. These data confirm the postulate that Mstn and MSV have divergent signalling functions and suggest a role for MSV in the control of oxidative metabolism.

year: 2014

title: Tīhei Mauri Ora: Negotiating primary school teachers' personal and professional identities as Māori

authors: Gilgen, Renée

subjects: Professional Learning and Development for teachers

abstract: Colonial attitudes that positioned Māori language, knowledge and pedagogy as inferior and deficient continue to impact on 21st century primary school contexts in Aotearoa/New Zealand. They continue to impact particularly on the personal and professional identities and experiences of Māori teachers in contemporary English-medium schools. Just as, historically, Māori students were expected to leave their language and culture at the 19th century colonial school gates, so too are many contemporary Māori teachers in mainstream schools expected to set aside their language and culture and engage with the curriculum and pedagogy of the school where they work. Ironically, at the same time, these teachers are often expected to guide and assist their school to meet its requirements under Te Tiriti o Waitangi/Treaty of Waitangi to ensure that its Māori students will succeed as Māori.

This thesis sought to understand how a small cohort of experienced Māori teachers, positioned within 21st century English-medium primary schools, perceived and negotiated the challenges to their personal and professional identities as Māori, and as Māori teachers. The thesis employed a qualitative participant narrative methodology, framed with kaupapa Māori theory. The teachers participated in individual interviews and in a series of hui kōrero (focused conversations) that assisted them to reflect critically on sociohistorical and educational factors that influenced the formation and maintenance of their identities as Māori.

The teachers’ narratives that emerged from individual and collaborative hui kōrero revealed that (1) being raised within urban environments and being themselves educated in monocultural schools during the 1960s and 1970s strongly impacted on how their Māori identities were shaped and, (2) their teaching experiences within English-medium primary schools and classrooms were culturally isolating and destructive, and largely unsupportive of the diverse realities that exists for some Māori teachers.

I offer two key strategic responses to these findings. Firstly, I offer a self-identity continuum that seeks to respect and affirm Māori identity by taking into account the different levels and contexts of experience some Māori teachers may have with Māori cultural concepts and practices. Secondly, I assert the need for a culturally located and relational space within English-medium school contexts for Māori teachers to engage with, and draw on the support of other Māori teachers in order to affirm their varying personal and professional identities as Māori. Meeting this need is understood as a Tiriti o Waitangi/Treaty-honouring response, required of all schools.

text: Tīhei Mauri Ora: Negotiating primary school teachers' personal and professional identities as Māori Colonial attitudes that positioned Māori language, knowledge and pedagogy as inferior and deficient continue to impact on 21st century primary school contexts in Aotearoa/New Zealand. They continue to impact particularly on the personal and professional identities and experiences of Māori teachers in contemporary English-medium schools. Just as, historically, Māori students were expected to leave their language and culture at the 19th century colonial school gates, so too are many contemporary Māori teachers in mainstream schools expected to set aside their language and culture and engage with the curriculum and pedagogy of the school where they work. Ironically, at the same time, these teachers are often expected to guide and assist their school to meet its requirements under Te Tiriti o Waitangi/Treaty of Waitangi to ensure that its Māori students will succeed as Māori.

This thesis sought to understand how a small cohort of experienced Māori teachers, positioned within 21st century English-medium primary schools, perceived and negotiated the challenges to their personal and professional identities as Māori, and as Māori teachers. The thesis employed a qualitative participant narrative methodology, framed with kaupapa Māori theory. The teachers participated in individual interviews and in a series of hui kōrero (focused conversations) that assisted them to reflect critically on sociohistorical and educational factors that influenced the formation and maintenance of their identities as Māori.

The teachers’ narratives that emerged from individual and collaborative hui kōrero revealed that (1) being raised within urban environments and being themselves educated in monocultural schools during the 1960s and 1970s strongly impacted on how their Māori identities were shaped and, (2) their teaching experiences within English-medium primary schools and classrooms were culturally isolating and destructive, and largely unsupportive of the diverse realities that exists for some Māori teachers.

I offer two key strategic responses to these findings. Firstly, I offer a self-identity continuum that seeks to respect and affirm Māori identity by taking into account the different levels and contexts of experience some Māori teachers may have with Māori cultural concepts and practices. Secondly, I assert the need for a culturally located and relational space within English-medium school contexts for Māori teachers to engage with, and draw on the support of other Māori teachers in order to affirm their varying personal and professional identities as Māori. Meeting this need is understood as a Tiriti o Waitangi/Treaty-honouring response, required of all schools.

year: 2016