title: Gene expression underlying ferret hair growth initiation induced by melatonin and modified by steroids

authors: Yu, Zhidong

abstract: Synchronised ferret winter pelage development induced by melatonin was utilised as an in vivo model for studying gene expression associated with the hair growth cycle.
The effects of melatonin and steroids on hair follicle growth initiation in flank skin samples were monitored by histology and immunocytochemistry. Melatonin implantation initiated hair growth within 10 days. Exogenous steroids delivered by slow-release subcutaneous implants had mainly inhibitory effects on spontaneous and melatonin-initiated hair growth, either when given simultaneously or prior to melatonin administration. 17β-oestradiol totally suppressed hair follicle growth in all circumstances, while the inhibitory effects of dexamethasone, testosterone and deoxycorticosterone were weaker and attenuated by melatonin. Progesterone given simultaneously with melatonin inhibited hair growth in males, but did not significantly affect female hair growth initiated by melatonin.

Gene expression underlying ferret hair growth was studied using an optimised differential display technique using two sets of complementary skin samples covering all growth initiation stages. The differential display band patterns for approximately 8% of all skin transcripts suggested that more than a thousand genes are required for hair follicle growth. Of the differentially expressed genes detected in a set of flank skin samples covering all proanagen stages, up to a half are likely to be specifically associated with hair growth.

The 150 expressed sequence tags (ESTs) discovered represented 112 unique sequences. Forty-two of these were aligned by sequence homology to known genes, while the remainder are likely to represent novel genes. Differential expression through the follicle growth cycle or after the treatments was confirmed for 21 out of 23 genes whose mRNAs were detectable by Northern blot hybridisation. Overall, expression alteration for most of these ESTs occurred prior to morphological changes in the skin associated with hair follicle reactivation. All the ESTs whose expression sites were detected by in situ hybridisation were localised to hair follicles. Some were detected only in certain stages of the hair follicle cycle, others in all growth stages, but at different levels. Classification of the identified ESTs suggested that apoptosis as well as fatty acid synthesis and cholesterol metabolism were closely associated with hair growth initiation, while cell interaction and motility were also particular prominent processes in hair follicle regrowth.

Additional DNA sequence information was obtained for ferret hair acidic keratin 8 (fHa8) and ferret cyclin D-interacting myb-like protein 1 (fDMP1). Both of these genes were expressed only in cortical cells in the keratogenous zone from mid-proanagen. fHa8 was expressed only in one side of the cortex, a feature has not previously been reported for other type I intermediate hair keratins. The restricted expression of fDMP1 and its smaller size suggested that it was an alternatively spliced form of the human and mouse homologues with a specialised function in the regulation of cortical cell proliferation and differentiation. Further studies on the expression regulation and function of the genes represented by the ESTs identified in this study promise to considerably advance our understanding of hair follicle growth control.

text: Gene expression underlying ferret hair growth initiation induced by melatonin and modified by steroids Synchronised ferret winter pelage development induced by melatonin was utilised as an in vivo model for studying gene expression associated with the hair growth cycle.
The effects of melatonin and steroids on hair follicle growth initiation in flank skin samples were monitored by histology and immunocytochemistry. Melatonin implantation initiated hair growth within 10 days. Exogenous steroids delivered by slow-release subcutaneous implants had mainly inhibitory effects on spontaneous and melatonin-initiated hair growth, either when given simultaneously or prior to melatonin administration. 17β-oestradiol totally suppressed hair follicle growth in all circumstances, while the inhibitory effects of dexamethasone, testosterone and deoxycorticosterone were weaker and attenuated by melatonin. Progesterone given simultaneously with melatonin inhibited hair growth in males, but did not significantly affect female hair growth initiated by melatonin.

Gene expression underlying ferret hair growth was studied using an optimised differential display technique using two sets of complementary skin samples covering all growth initiation stages. The differential display band patterns for approximately 8% of all skin transcripts suggested that more than a thousand genes are required for hair follicle growth. Of the differentially expressed genes detected in a set of flank skin samples covering all proanagen stages, up to a half are likely to be specifically associated with hair growth.

The 150 expressed sequence tags (ESTs) discovered represented 112 unique sequences. Forty-two of these were aligned by sequence homology to known genes, while the remainder are likely to represent novel genes. Differential expression through the follicle growth cycle or after the treatments was confirmed for 21 out of 23 genes whose mRNAs were detectable by Northern blot hybridisation. Overall, expression alteration for most of these ESTs occurred prior to morphological changes in the skin associated with hair follicle reactivation. All the ESTs whose expression sites were detected by in situ hybridisation were localised to hair follicles. Some were detected only in certain stages of the hair follicle cycle, others in all growth stages, but at different levels. Classification of the identified ESTs suggested that apoptosis as well as fatty acid synthesis and cholesterol metabolism were closely associated with hair growth initiation, while cell interaction and motility were also particular prominent processes in hair follicle regrowth.

Additional DNA sequence information was obtained for ferret hair acidic keratin 8 (fHa8) and ferret cyclin D-interacting myb-like protein 1 (fDMP1). Both of these genes were expressed only in cortical cells in the keratogenous zone from mid-proanagen. fHa8 was expressed only in one side of the cortex, a feature has not previously been reported for other type I intermediate hair keratins. The restricted expression of fDMP1 and its smaller size suggested that it was an alternatively spliced form of the human and mouse homologues with a specialised function in the regulation of cortical cell proliferation and differentiation. Further studies on the expression regulation and function of the genes represented by the ESTs identified in this study promise to considerably advance our understanding of hair follicle growth control.

year: 2001

title: Motivation, constraint and association: an analysis of Killeen's (1994) mathematical principles of reinforcement.

authors: Armstrong, Rebecca Theresa

subjects: mathematical principles of reinforcement

abstract: Mathematical principles of reinforcement (MPR; Killeen, 1994) is a useful model for predicting and describing behaviour. MPR is based upon three general principles represented by three independent parameters in the model: (1) incentives elicit responses and the quality or amount of a reinforcer will effect organisms arousal and motivation to work for that particular reinforcer (specific activation; a in the model), (2) there are time and energy constraints on responding resulting in ceilings on response rates (constraint; δ), and (3) reinforcement only occurs to the extent that responses are associated with reinforcers (Coupling; c.). This experiment tested the ability of MPR to predict response rates when the minimum force requirement to make a response and the reinforcer duration was increased. Five hens responded on a geometric fixed ratio (FR) schedule in three conditions; low force requirement, small reinforcer (0.24 N, 2-s access), high force requirement, small reinforcer (1.1 N, 2-s access) and high force requirement, large reinforcer (1.1 N, 4-s access). Response rates were well described by a bitonic function as predicted. Response rates were higher and the hens ceased responding at higher FR values when the force requirement was low. Constraint (δ) was not significantly affected by the increase in force requirement. Interestingly, estimates of a were most effected by the increase in force requirement. Estimates of a were not affected by the increase in the magnitude of the reinforcer. It was concluded that doubling the incentive value may require more than doubling the amount of reinforcement. Additionally, there may be a need to distinguish between time to make a response and effort required with the latter impacting more on the motivation of the organism.

text: Motivation, constraint and association: an analysis of Killeen's (1994) mathematical principles of reinforcement. Mathematical principles of reinforcement (MPR; Killeen, 1994) is a useful model for predicting and describing behaviour. MPR is based upon three general principles represented by three independent parameters in the model: (1) incentives elicit responses and the quality or amount of a reinforcer will effect organisms arousal and motivation to work for that particular reinforcer (specific activation; a in the model), (2) there are time and energy constraints on responding resulting in ceilings on response rates (constraint; δ), and (3) reinforcement only occurs to the extent that responses are associated with reinforcers (Coupling; c.). This experiment tested the ability of MPR to predict response rates when the minimum force requirement to make a response and the reinforcer duration was increased. Five hens responded on a geometric fixed ratio (FR) schedule in three conditions; low force requirement, small reinforcer (0.24 N, 2-s access), high force requirement, small reinforcer (1.1 N, 2-s access) and high force requirement, large reinforcer (1.1 N, 4-s access). Response rates were well described by a bitonic function as predicted. Response rates were higher and the hens ceased responding at higher FR values when the force requirement was low. Constraint (δ) was not significantly affected by the increase in force requirement. Interestingly, estimates of a were most effected by the increase in force requirement. Estimates of a were not affected by the increase in the magnitude of the reinforcer. It was concluded that doubling the incentive value may require more than doubling the amount of reinforcement. Additionally, there may be a need to distinguish between time to make a response and effort required with the latter impacting more on the motivation of the organism.

year: 2015

title: Ngā niho tēte o Pekehāua: An indigenous articulation of governance

authors: Mahuika, Rangimarie

subjects: Indigenous Governance

abstract: This thesis originally set out to examine the structures and models available within New Zealand for a post-settlement tribal governance framework that would meet the Office of Treaty Settlements requirements while empowering the needs and aspirations of Ngāti Rangiwewehi. During the course of the study, as a result of the fast-tracking of our tribal settlement this emphasis changed. With Ngāti Rangiwewehi electing to utilise the government recommended templates for the post-settlement entity, the research shifted to consider the evolution of governance within the tribe, looking at the ways tribal governance had developed from traditional practices to our current governance frameworks. It was anticipated that gaining a deeper understanding of the factors that have shaped and influenced our governance would also give us the necessary insights to adapt the Crown model the tribe had adopted to ensure it was able to meet Ngāti Rangiwewehi’s future aspirations. This belief was grounded in an understanding that prior to the arrival of Pākehā to Aotearoa/New Zealand Ngāti Rangiwewehi, along with all other iwi Māori, had their own systems of Governance. Our governance frameworks, encapsulated within our tikanga and kawa, operated to produce a strong, vibrant, and self-determining society. Through colonisation, and its imposed Western frameworks for governance within Aotearoa New Zealand, traditional Māori frameworks for law and governance were undermined, deconstructed, or marginalised to make way for the civilizing discourses and structures of the Settler, as enforced by the British Crown. Although the dominant system of law and frameworks for governance may have changed, Ngāti Rangiwewehi and Māori desires for self-determination have not.
Against this background the central question of this study has itself evolved, initially contemplating to what extent Ngāti Rangiwewehi might be able to remain self-determining in and through their post-settlement governance arrangements. The overwhelming conclusion the study could not avoid was that any governance approach drawn from the settler-colonial Eurocentric system currently dominant in New Zealand would be incapable of supporting tribal aspirations for self-determination. What was equally evident was the continued determination that the tribe, collectively and individually, maintained to mediate the imposed governance frameworks that interfere in our ability to fully exercise our tino rangatiratanga, or in our iwi-specific context, our tino Rangiwewehitanga. This observation led to the final iteration of the thesis question which asks what frameworks for governance would best empower Ngāti Rangiwewehi to be self-determining in and beyond this post-settlement governance era? Throughout the research what became apparent was the potential to utilise our traditional frameworks for governance, described and encapsulated within this study as Rangiwewehitanga, a decolonial paradigm for tribal governance. Viewed in this way, Rangiwewehitanga expands our understanding of governance beyond the limited perspectives imposed through colonization and requires our people to recognise and return to the wisdom of our ancestral teachings to craft the most appropriate pathways forward.

text: Ngā niho tēte o Pekehāua: An indigenous articulation of governance This thesis originally set out to examine the structures and models available within New Zealand for a post-settlement tribal governance framework that would meet the Office of Treaty Settlements requirements while empowering the needs and aspirations of Ngāti Rangiwewehi. During the course of the study, as a result of the fast-tracking of our tribal settlement this emphasis changed. With Ngāti Rangiwewehi electing to utilise the government recommended templates for the post-settlement entity, the research shifted to consider the evolution of governance within the tribe, looking at the ways tribal governance had developed from traditional practices to our current governance frameworks. It was anticipated that gaining a deeper understanding of the factors that have shaped and influenced our governance would also give us the necessary insights to adapt the Crown model the tribe had adopted to ensure it was able to meet Ngāti Rangiwewehi’s future aspirations. This belief was grounded in an understanding that prior to the arrival of Pākehā to Aotearoa/New Zealand Ngāti Rangiwewehi, along with all other iwi Māori, had their own systems of Governance. Our governance frameworks, encapsulated within our tikanga and kawa, operated to produce a strong, vibrant, and self-determining society. Through colonisation, and its imposed Western frameworks for governance within Aotearoa New Zealand, traditional Māori frameworks for law and governance were undermined, deconstructed, or marginalised to make way for the civilizing discourses and structures of the Settler, as enforced by the British Crown. Although the dominant system of law and frameworks for governance may have changed, Ngāti Rangiwewehi and Māori desires for self-determination have not.
Against this background the central question of this study has itself evolved, initially contemplating to what extent Ngāti Rangiwewehi might be able to remain self-determining in and through their post-settlement governance arrangements. The overwhelming conclusion the study could not avoid was that any governance approach drawn from the settler-colonial Eurocentric system currently dominant in New Zealand would be incapable of supporting tribal aspirations for self-determination. What was equally evident was the continued determination that the tribe, collectively and individually, maintained to mediate the imposed governance frameworks that interfere in our ability to fully exercise our tino rangatiratanga, or in our iwi-specific context, our tino Rangiwewehitanga. This observation led to the final iteration of the thesis question which asks what frameworks for governance would best empower Ngāti Rangiwewehi to be self-determining in and beyond this post-settlement governance era? Throughout the research what became apparent was the potential to utilise our traditional frameworks for governance, described and encapsulated within this study as Rangiwewehitanga, a decolonial paradigm for tribal governance. Viewed in this way, Rangiwewehitanga expands our understanding of governance beyond the limited perspectives imposed through colonization and requires our people to recognise and return to the wisdom of our ancestral teachings to craft the most appropriate pathways forward.

year: 2019