title: The biology of Asparagopsis armata for closed-life cycle cultivation in New Zealand

authors: Mihaila, Alisa Andrea

abstract: The red seaweed Asparagopsis armata is a target species for aquaculture due to its efficacy as an anti-methanogenic ruminant feed additive. However, limited knowledge regarding its reproductive biology and methods for closed-life cycle cultivation has delayed adoption of this method in aquaculture. This thesis therefore aimed to address these knowledge gaps by investigating (1) reproductive phenology, (2) techniques for inducing life-cycle transitions, (3) nursery requirements, and (4) internal mechanisms regulating reproductive processes in A. armata. 
A comparative analysis of A. armata reproductive phenology in New Zealand from 2021 to 2022, compared to 1978 to 1981, identified potential climate-driven shifts in phenology. Specifically, the occurrence period of gametophytes was shorter, and cystocarp production and viable carpospore release were delayed in comparison to 1978–1981. Discoloration, low reproductive output, and low survival rates in 2022 were likely caused by heat stress. These findings will help guide aquaculture practises and advance our understanding of climate change effects on seaweed reproductive phenology through future comparative studies.
Mass production and release of tetraspores in domesticated A. armata tetrasporophytes was demonstrated through a 14-day exposure to a reduced critical photoperiod of 8 h L:16 h D. Increasing the temperature from 15 to 18 °C resulted in a marked increase in tetraspore release, whereas exposure to 11 and 13 °C, along with lower light intensities and nutrient concentrations, did not initiate tetrasporogenesis. These results highlight the importance of temperature, among other environmental factors, in controlling reproductive output. A distinct bimodal pattern in tetraspore release was observed, and tetrasporogenesis could be re-induced in the same biomass by adjusting key environmental parameters. These findings collectively offer precise control over tetrasporogenesis, facilitating commercial hatchery production. 
Key parameters for enhancing the growth and development of juvenile gametophytes of A. armata were identified, notably moderate temperature and water flow, which resulted in substantial biomass productivity increases. Gametophytes developed more rapidly under a 12h L:12h D photoperiod, while growth was enhanced under lower irradiances. Additionally, lowering nutrient concentrations resulted in cleaner cultures without compromising growth. These results elucidate the influence of environmental factors during the early life stages of A. armata, providing essential insights to enable large-scale nursery operations. 
Finally, an analysis of metabolomic and transcriptomic dynamics during induction of tetrasporogenesis identified marked changes in gene expression. While metabolomic changes were less prominent, accumulation of several metabolites occurred. Multiple pathways and genes, such as those related to polyamine and steroid hormone production, environmental signalling, and carbon metabolism, were upregulated during induction. These results demonstrate a dynamic biochemical and molecular response, particularly in the early stages of initiating tetrasporogenesis, laying the groundwork for identifying candidate genes and metabolites that regulate this process.  
In summary, this thesis significantly advances the science and knowledge required for the successful cultivation of A. armata by creating foundations to (1) guide the selection of cultivation techniques, (2) develop climate-resilient management strategies, (3) enable the implementation of streamlined commercial hatcheries and nurseries, and (4) direct future research aimed at deciphering the fundamental internal mechanisms of reproductive transitions in seaweed.

text: The biology of Asparagopsis armata for closed-life cycle cultivation in New Zealand The red seaweed Asparagopsis armata is a target species for aquaculture due to its efficacy as an anti-methanogenic ruminant feed additive. However, limited knowledge regarding its reproductive biology and methods for closed-life cycle cultivation has delayed adoption of this method in aquaculture. This thesis therefore aimed to address these knowledge gaps by investigating (1) reproductive phenology, (2) techniques for inducing life-cycle transitions, (3) nursery requirements, and (4) internal mechanisms regulating reproductive processes in A. armata. 
A comparative analysis of A. armata reproductive phenology in New Zealand from 2021 to 2022, compared to 1978 to 1981, identified potential climate-driven shifts in phenology. Specifically, the occurrence period of gametophytes was shorter, and cystocarp production and viable carpospore release were delayed in comparison to 1978–1981. Discoloration, low reproductive output, and low survival rates in 2022 were likely caused by heat stress. These findings will help guide aquaculture practises and advance our understanding of climate change effects on seaweed reproductive phenology through future comparative studies.
Mass production and release of tetraspores in domesticated A. armata tetrasporophytes was demonstrated through a 14-day exposure to a reduced critical photoperiod of 8 h L:16 h D. Increasing the temperature from 15 to 18 °C resulted in a marked increase in tetraspore release, whereas exposure to 11 and 13 °C, along with lower light intensities and nutrient concentrations, did not initiate tetrasporogenesis. These results highlight the importance of temperature, among other environmental factors, in controlling reproductive output. A distinct bimodal pattern in tetraspore release was observed, and tetrasporogenesis could be re-induced in the same biomass by adjusting key environmental parameters. These findings collectively offer precise control over tetrasporogenesis, facilitating commercial hatchery production. 
Key parameters for enhancing the growth and development of juvenile gametophytes of A. armata were identified, notably moderate temperature and water flow, which resulted in substantial biomass productivity increases. Gametophytes developed more rapidly under a 12h L:12h D photoperiod, while growth was enhanced under lower irradiances. Additionally, lowering nutrient concentrations resulted in cleaner cultures without compromising growth. These results elucidate the influence of environmental factors during the early life stages of A. armata, providing essential insights to enable large-scale nursery operations. 
Finally, an analysis of metabolomic and transcriptomic dynamics during induction of tetrasporogenesis identified marked changes in gene expression. While metabolomic changes were less prominent, accumulation of several metabolites occurred. Multiple pathways and genes, such as those related to polyamine and steroid hormone production, environmental signalling, and carbon metabolism, were upregulated during induction. These results demonstrate a dynamic biochemical and molecular response, particularly in the early stages of initiating tetrasporogenesis, laying the groundwork for identifying candidate genes and metabolites that regulate this process.  
In summary, this thesis significantly advances the science and knowledge required for the successful cultivation of A. armata by creating foundations to (1) guide the selection of cultivation techniques, (2) develop climate-resilient management strategies, (3) enable the implementation of streamlined commercial hatcheries and nurseries, and (4) direct future research aimed at deciphering the fundamental internal mechanisms of reproductive transitions in seaweed.

year: 2024

title: Molecular Studies of House Mice in Southern New Zealand

authors: McCormick, Helen Margaret

subjects: mus musculus

abstract: The house mouse, Mus Musculus, was first introduced into New Zealand in significant numbers in the mid nineteenth century. Earlier research suggests that multiple introductions of the three subspecies of house mouse M. m. domesticus, M. m. musculus and M. m. castaneus occurred at this time. While M. m. domesticus is widely distributed in New Zealand with M. m. musculus somewhat less so, the only extant evidence found to date for M. m. castaneus is in hybrid mice found principally in the southern half of the South Island. In this study, the hybrid population of mice in the South Island was examined in detail using a variety of molecular techniques. The extent of the hybrid zone was first established using a simple polymerase chain reaction (PCR) technique that enabled rapid identification of mitochondrial genomes as being M. m. domesticus, castaneus or musculus in nature. In the second part of the study, four representative mice from the hybrid zone and three M. m. domesticus from north of this zone were subjected to high density (600K) single nucleotide polymorphism (SNP) analyses in order to pinpoint regions of the genomes that differed in a significant manner between the two groups. In a refinement of these analyses, regions of each genome were identified as being domesticus-, castaneus- or musculus-like, using diagnostic SNP alleles for each sub-species. Some 170 mice, principally collected in the Southern South Island, were screened using the rapid PCR technique. In the coastal regions, all mice further south than 44oS had M. m. castaneus mtDNA whereas those north of 43oS had M. m. domesticus mtDNA. Between the two, there is a ‘contact zone’ in which both subspecies were found, sometimes in the same building. The contact zone extends approximately 50km north to south and some 30km inland. Classical tests with three nuclear DNA markers confirmed earlier work, namely, that the nuclear genomes of all mice appeared to be predominantly domesticus-like. Although there is no obvious geographical, ecological or land-use features that characterise this contact zone it may be relevant that there is the distinct change to a wetter colder climate in the south and inland of the contact zone, especially in winter. The inability to identify obvious defining features is not surprising, given that much research over many years worldwide has failed to yield an explanation for distinct mouse hybrid zones. The high density SNP analyses demonstrated that the nuclear genomes of all seven representative mice were very similar and largely (approximately 95%+) domesticus-like in nature. Despite this similarity, clusters of SNPs did reveal differences throughout the genome, often just extending over a few haplotype blocks and often encompassing much less than a million basepairs (Mb). Some of these were of biological interest, for example clusters of vomeronasal receptor genes and also genes believed to be involved in maternal-fetal conflict, which are known to vary markedly between species. The diagnostic SNP analyses confirmed that no marked differences exist between the genomes of the hybrid and M. m. domesticus mice. As stated above, the genomes were predominantly domesticus-like but small regions (~1Mb) of castaneus-like and musculus-like genome were found scattered throughout all mice but, contrary to initial expectations, there was no preponderance of castaneus-like regions in the hybrid mice. The one exception to the largely identical genomic SNP patterns, were those from the mouse collected in Hamilton. This was quite bizarre, in that its genome contains large (up to 10Mb) musculus-like regions that correspond exactly to the same regions in a common laboratory strain of mouse, C57BL/6J. I conclude that if pure M. m. castaneus mice did originally reach New Zealand, extensive ‘backcrossing’ with M. m. domesticus has virtually eliminated the castaneus genome, with just a few remnants remaining that may or may not confer some selective advantage, but could just as likely represent segregation of recognition factors that give rise to assortative mating. Thus, the most obvious and consistent genetic difference between the mice remains the original observation concerning their mitochondrial genomes and these should be examined in more detail. In future research aimed at identifying potential selective advantages that have allowed the hybrid mice to exclusively populate the southern South Island factors that relate to climate should be considered. Specifically, the fact that, in humans, some mitochondrial haplotypes are believed to confer a selective advantage in colder climates immediately suggests that examining variants of key genes involved in energy metabolism such as NADH-dehydrogenase-subunit-3 ( ND3 ) in the hybrid mice could be a profitable line of future research.

text: Molecular Studies of House Mice in Southern New Zealand The house mouse, Mus Musculus, was first introduced into New Zealand in significant numbers in the mid nineteenth century. Earlier research suggests that multiple introductions of the three subspecies of house mouse M. m. domesticus, M. m. musculus and M. m. castaneus occurred at this time. While M. m. domesticus is widely distributed in New Zealand with M. m. musculus somewhat less so, the only extant evidence found to date for M. m. castaneus is in hybrid mice found principally in the southern half of the South Island. In this study, the hybrid population of mice in the South Island was examined in detail using a variety of molecular techniques. The extent of the hybrid zone was first established using a simple polymerase chain reaction (PCR) technique that enabled rapid identification of mitochondrial genomes as being M. m. domesticus, castaneus or musculus in nature. In the second part of the study, four representative mice from the hybrid zone and three M. m. domesticus from north of this zone were subjected to high density (600K) single nucleotide polymorphism (SNP) analyses in order to pinpoint regions of the genomes that differed in a significant manner between the two groups. In a refinement of these analyses, regions of each genome were identified as being domesticus-, castaneus- or musculus-like, using diagnostic SNP alleles for each sub-species. Some 170 mice, principally collected in the Southern South Island, were screened using the rapid PCR technique. In the coastal regions, all mice further south than 44oS had M. m. castaneus mtDNA whereas those north of 43oS had M. m. domesticus mtDNA. Between the two, there is a ‘contact zone’ in which both subspecies were found, sometimes in the same building. The contact zone extends approximately 50km north to south and some 30km inland. Classical tests with three nuclear DNA markers confirmed earlier work, namely, that the nuclear genomes of all mice appeared to be predominantly domesticus-like. Although there is no obvious geographical, ecological or land-use features that characterise this contact zone it may be relevant that there is the distinct change to a wetter colder climate in the south and inland of the contact zone, especially in winter. The inability to identify obvious defining features is not surprising, given that much research over many years worldwide has failed to yield an explanation for distinct mouse hybrid zones. The high density SNP analyses demonstrated that the nuclear genomes of all seven representative mice were very similar and largely (approximately 95%+) domesticus-like in nature. Despite this similarity, clusters of SNPs did reveal differences throughout the genome, often just extending over a few haplotype blocks and often encompassing much less than a million basepairs (Mb). Some of these were of biological interest, for example clusters of vomeronasal receptor genes and also genes believed to be involved in maternal-fetal conflict, which are known to vary markedly between species. The diagnostic SNP analyses confirmed that no marked differences exist between the genomes of the hybrid and M. m. domesticus mice. As stated above, the genomes were predominantly domesticus-like but small regions (~1Mb) of castaneus-like and musculus-like genome were found scattered throughout all mice but, contrary to initial expectations, there was no preponderance of castaneus-like regions in the hybrid mice. The one exception to the largely identical genomic SNP patterns, were those from the mouse collected in Hamilton. This was quite bizarre, in that its genome contains large (up to 10Mb) musculus-like regions that correspond exactly to the same regions in a common laboratory strain of mouse, C57BL/6J. I conclude that if pure M. m. castaneus mice did originally reach New Zealand, extensive ‘backcrossing’ with M. m. domesticus has virtually eliminated the castaneus genome, with just a few remnants remaining that may or may not confer some selective advantage, but could just as likely represent segregation of recognition factors that give rise to assortative mating. Thus, the most obvious and consistent genetic difference between the mice remains the original observation concerning their mitochondrial genomes and these should be examined in more detail. In future research aimed at identifying potential selective advantages that have allowed the hybrid mice to exclusively populate the southern South Island factors that relate to climate should be considered. Specifically, the fact that, in humans, some mitochondrial haplotypes are believed to confer a selective advantage in colder climates immediately suggests that examining variants of key genes involved in energy metabolism such as NADH-dehydrogenase-subunit-3 ( ND3 ) in the hybrid mice could be a profitable line of future research.

year: 2011

title: Te Mata Ono-The six faces of Māori broadcasting

authors: Kaire-Melbourne, Kimiora

subjects: Māori broadcasting

abstract: Māori have always been involved in media communication and from a traditional viewpoint karanga, whaikōrero, taonga pūoro, haka, waiata and mōteatea are all mediums used to share messages across a mass audience. Since the arrival of European settlers, we have seen Māori content disseminated through platforms such as newspaper, radio, and more recently via the medium of television. This particular study is concerned with the way that Māori are represented and information is shared via indigenous broadcaster, Māori Television. Using a theoretical model made up of six key components, this thesis asserts that Te Mata Ono could not only help to improve the production of Māori content but also reshape and modify the medium of television itself, to become more culturally appropriate. Ultimately, this model could guide Māori Television, outlining a Māori specific approach to broadcasting. This study is one part of a two-part study. Due to the limitations of a four-paper masters thesis, I will only be examining three elements of Te Mata Ono, which are Mata Māori, Mata ō-tua and Mata Pākehā. Another thesis that was conducted simultaneously by Te Aorere Pewhairangi explores the remaining three elements of the same model, Mata Iwi, Mata Ako and Mata Tikanga. Te Mata Ono could be applied to Māori Television, making a positive contribution to the future development of Māori broadcasting.

text: Te Mata Ono-The six faces of Māori broadcasting Māori have always been involved in media communication and from a traditional viewpoint karanga, whaikōrero, taonga pūoro, haka, waiata and mōteatea are all mediums used to share messages across a mass audience. Since the arrival of European settlers, we have seen Māori content disseminated through platforms such as newspaper, radio, and more recently via the medium of television. This particular study is concerned with the way that Māori are represented and information is shared via indigenous broadcaster, Māori Television. Using a theoretical model made up of six key components, this thesis asserts that Te Mata Ono could not only help to improve the production of Māori content but also reshape and modify the medium of television itself, to become more culturally appropriate. Ultimately, this model could guide Māori Television, outlining a Māori specific approach to broadcasting. This study is one part of a two-part study. Due to the limitations of a four-paper masters thesis, I will only be examining three elements of Te Mata Ono, which are Mata Māori, Mata ō-tua and Mata Pākehā. Another thesis that was conducted simultaneously by Te Aorere Pewhairangi explores the remaining three elements of the same model, Mata Iwi, Mata Ako and Mata Tikanga. Te Mata Ono could be applied to Māori Television, making a positive contribution to the future development of Māori broadcasting.

year: 2019