title: The Chthonomonas calidirosea genome is highly conserved across geographic locations and distinct chemical and microbial environments in New Zealand's Taupo Volcanic Zone

authors: Lee, Kevin C.

abstract: Chthonomonas calidirosea T49T is a low-abundance, carbohydrate-scavenging, and thermophilic soil bacterium with a seemingly disorganized genome. We hypothesized that the C. calidirosea genome would be highly responsive to local selection pressure, resulting in the divergence of its genomic content, genome organization, and carbohydrate utilization phenotype across environments. We tested this hypothesis by sequencing the genomes of four C. calidirosea isolates obtained from four separate geothermal fields in the Taupō Volcanic Zone, New Zealand. For each isolation site, we measured physicochemical attributes and defined the associated microbial community by 16S rRNA gene sequencing. Despite their ecological and geographical isolation, the genome sequences showed low divergence (maximum, 1.17%). Isolate-specific variations included single-nucleotide polymorphisms (SNPs), restriction-modification systems, and mobile elements but few major deletions and no major rearrangements. The 50-fold variation in C. calidirosea relative abundance among the four sites correlated with site environmental characteristics but not with differences in genomic content. Conversely, the carbohydrate utilization profiles of the C. calidirosea isolates corresponded to the inferred isolate phylogenies, which only partially paralleled the geographical relationships among the sample sites. Genomic sequence conservation does not entirely parallel geographic distance, suggesting that stochastic dispersal and localized extinction, which allow for rapid population homogenization with little restriction by geographical barriers, are possible mechanisms of C. calidirosea distribution. This dispersal and extinction mechanism is likely not limited to C. calidirosea but may shape the populations and genomes of many other low-abundance free-living taxa.

text: The Chthonomonas calidirosea genome is highly conserved across geographic locations and distinct chemical and microbial environments in New Zealand's Taupo Volcanic Zone Chthonomonas calidirosea T49T is a low-abundance, carbohydrate-scavenging, and thermophilic soil bacterium with a seemingly disorganized genome. We hypothesized that the C. calidirosea genome would be highly responsive to local selection pressure, resulting in the divergence of its genomic content, genome organization, and carbohydrate utilization phenotype across environments. We tested this hypothesis by sequencing the genomes of four C. calidirosea isolates obtained from four separate geothermal fields in the Taupō Volcanic Zone, New Zealand. For each isolation site, we measured physicochemical attributes and defined the associated microbial community by 16S rRNA gene sequencing. Despite their ecological and geographical isolation, the genome sequences showed low divergence (maximum, 1.17%). Isolate-specific variations included single-nucleotide polymorphisms (SNPs), restriction-modification systems, and mobile elements but few major deletions and no major rearrangements. The 50-fold variation in C. calidirosea relative abundance among the four sites correlated with site environmental characteristics but not with differences in genomic content. Conversely, the carbohydrate utilization profiles of the C. calidirosea isolates corresponded to the inferred isolate phylogenies, which only partially paralleled the geographical relationships among the sample sites. Genomic sequence conservation does not entirely parallel geographic distance, suggesting that stochastic dispersal and localized extinction, which allow for rapid population homogenization with little restriction by geographical barriers, are possible mechanisms of C. calidirosea distribution. This dispersal and extinction mechanism is likely not limited to C. calidirosea but may shape the populations and genomes of many other low-abundance free-living taxa.

year: 2016

title: Elucidating the sugar import pathway into developing kiwifruit berries (Actinidia deliciosa)

authors: Gould, Nick

subjects: carbon-14

abstract: The aim of this work was to investigate the roles of the apoplasmic and symplasmic pathways in the delivery of solutes to the outer pericarp of developing green-fleshed kiwifruit berries (Actinidia deliciosa [A. Chev.] C. F. Liang et A. R. Ferguson var. deliciosa ‘Hayward’). Experiments with the symplasmic tracer 5(6)-carboxyfluorescein (CF) showed symplasmic movement of dye during the initial rapid growth stage of the fruit, but as fruit growth slowed and starch content increased, a reduction in symplasmic spread of CF was observed (+126 DAA [days after anthesis]). Measurements of sugar uptake rates from the apoplasm were sufficient to account for the dry matter accumulation in growing fruit at each stage of fruit growth, and could potentially operate alongside a symplasmic pathway for post-phloem unloading of sugars during the rapid growth period. Energy requirements driving uptake from the apoplasm appear to depend on the sugar concentration gradients across the cell membrane throughout fruit development. Together, these data suggest: 1) the post-phloem symplasmic pathway is important during the fruit rapid growth stage, 2) the uptake of sugars from the apoplasm has a role in the transport of carbohydrates in the fruit, especially later in fruit development when the symplasmic pathway is reduced, and 3) apoplasmic sugar has an important role in the flow of water into the apoplasm of the fruit, providing a mechanism to maintain hydrostatic pressure gradients along the phloem supplying the fruit.

text: Elucidating the sugar import pathway into developing kiwifruit berries (Actinidia deliciosa) The aim of this work was to investigate the roles of the apoplasmic and symplasmic pathways in the delivery of solutes to the outer pericarp of developing green-fleshed kiwifruit berries (Actinidia deliciosa [A. Chev.] C. F. Liang et A. R. Ferguson var. deliciosa ‘Hayward’). Experiments with the symplasmic tracer 5(6)-carboxyfluorescein (CF) showed symplasmic movement of dye during the initial rapid growth stage of the fruit, but as fruit growth slowed and starch content increased, a reduction in symplasmic spread of CF was observed (+126 DAA [days after anthesis]). Measurements of sugar uptake rates from the apoplasm were sufficient to account for the dry matter accumulation in growing fruit at each stage of fruit growth, and could potentially operate alongside a symplasmic pathway for post-phloem unloading of sugars during the rapid growth period. Energy requirements driving uptake from the apoplasm appear to depend on the sugar concentration gradients across the cell membrane throughout fruit development. Together, these data suggest: 1) the post-phloem symplasmic pathway is important during the fruit rapid growth stage, 2) the uptake of sugars from the apoplasm has a role in the transport of carbohydrates in the fruit, especially later in fruit development when the symplasmic pathway is reduced, and 3) apoplasmic sugar has an important role in the flow of water into the apoplasm of the fruit, providing a mechanism to maintain hydrostatic pressure gradients along the phloem supplying the fruit.

year: 2013

title: A reflective account of successful leadership: Māori special character secondary boarding schools.

authors: McAllister, Theresa

abstract: This thesis explores the leadership and Māori student achievement in Māori boarding schools taking into account cultural contexts, environments and the leadership ideologies around educational leadership. What are the leadership practices in Māori boarding schools that have made a difference for Māori student achievement? I argue that, Māori secondary boarding schools continue to offer an educational framework whereby Māori students achieve as Maori.
In order to better understand the philosophies and goals of those early Māori boarding school leaders through to the present time I have researched a sample of current leaders within those boarding schools. This research interest arose many years ago when I first realised that there was a significant gap in Māori student educational achievement compared to non-Māori. What was also realised was that few people understood the contribution that Māori boarding schools have played in Māori student achievement and success over many decades. While some people had heard of Māori boarding schools, not a great deal was really known about what Māori boarding schools delivered in terms of education for Māori and Māori culture. What is apparent from an historical perspective is that Māori boarding schools have contributed to the retention of Māori culture, language and identity resulting in student achievement. This is a result of what successful leadership has provided for Māori students to achieve.
Student achievement is a direct result of leadership. In a Māori boarding school setting, achievement is multifaceted. For Māori secondary boarding schools, achievement is taken from three perspectives: Christian, Māori and Academic. Flowing down from those three perspectives is the holistic wellbeing of students’, mind, body and soul, while recognizing and including whānau, hapū and iwi. Therefore, this research investigates the leadership practices in Māori boarding schools that have made a difference for Māori student achievement.

text: A reflective account of successful leadership: Māori special character secondary boarding schools. This thesis explores the leadership and Māori student achievement in Māori boarding schools taking into account cultural contexts, environments and the leadership ideologies around educational leadership. What are the leadership practices in Māori boarding schools that have made a difference for Māori student achievement? I argue that, Māori secondary boarding schools continue to offer an educational framework whereby Māori students achieve as Maori.
In order to better understand the philosophies and goals of those early Māori boarding school leaders through to the present time I have researched a sample of current leaders within those boarding schools. This research interest arose many years ago when I first realised that there was a significant gap in Māori student educational achievement compared to non-Māori. What was also realised was that few people understood the contribution that Māori boarding schools have played in Māori student achievement and success over many decades. While some people had heard of Māori boarding schools, not a great deal was really known about what Māori boarding schools delivered in terms of education for Māori and Māori culture. What is apparent from an historical perspective is that Māori boarding schools have contributed to the retention of Māori culture, language and identity resulting in student achievement. This is a result of what successful leadership has provided for Māori students to achieve.
Student achievement is a direct result of leadership. In a Māori boarding school setting, achievement is multifaceted. For Māori secondary boarding schools, achievement is taken from three perspectives: Christian, Māori and Academic. Flowing down from those three perspectives is the holistic wellbeing of students’, mind, body and soul, while recognizing and including whānau, hapū and iwi. Therefore, this research investigates the leadership practices in Māori boarding schools that have made a difference for Māori student achievement.

year: 2016