title: Investigation into the Effects of Oxidative Stress on Reproductive Development.

authors: Collins, Tracey Helen

subjects: oxidative stress

abstract: Nuclear transfer (NT), or cloning, which is the transfer of a donor nucleus to a recipient enucleated oocyte, has been successfully achieved to produce viable offspring in many species.  The process is very inefficient, as reprogramming of the donor nucleus is required, and losses are high throughout development.  Placentation abnormalities are a common feature amongst cloned animals.  Incomplete nuclear reprogramming and erroneous epigenetic imprinting may contribute to aberrant protein transcription and DNA mutations, affecting mitochondrial metabolism and inducing cellular stress.  In vitro produced embryos under high oxygen culture conditions may also suffer oxidative stress, with the resulting reactive oxygen species causing mitochondrial DNA mutations and cellular stress similar to clones.

In this study, expression of oxidative stress protein markers (Hsp60, SOD2, Hsp70) in NT cotyledons were compared to artificial insemination (AI) at different time points of gestation (days 50, 100, and 150).  As a continuum of the oxidative stress investigation in cloned cotyledons, in vitro produced embryos were cultured under 20% oxygen compared to the control 7% oxygen laboratory standard culture, with oxidative stress protein markers examined between the groups at blastocyst stage (day 7) and day 15.  Embryo morphology was also observed to determine apparent physiological differences between the treatment and control embryos.  No previous studies to date have investigated the developmental effects of oxidative stress in day 15 bovine embryos.
 
The significant differences in oxidative stress proteins observed at several time points in the NT and AI groups were not repeatable, possibly due to sample freeze/thaw degradation.  Morphological differences observed between embryos cultured in 20% oxygen and control groups were visually apparent, although not quantified.  At day 15 manganese superoxide dismutase expression was significantly lower in the 20% group compared to control.  The 20% oxygen group did not show higher heat shock protein 60 expression than control, however the same results have been observed in another study at blastocyst stage.  The results of this study suggest that the effect of oxidative stress on embryonic development is evident yet inconclusive in bovine NT cotyledons, however does not appear apparent in day 15 embryos following culture in 20% oxygen.

text: Investigation into the Effects of Oxidative Stress on Reproductive Development. Nuclear transfer (NT), or cloning, which is the transfer of a donor nucleus to a recipient enucleated oocyte, has been successfully achieved to produce viable offspring in many species.  The process is very inefficient, as reprogramming of the donor nucleus is required, and losses are high throughout development.  Placentation abnormalities are a common feature amongst cloned animals.  Incomplete nuclear reprogramming and erroneous epigenetic imprinting may contribute to aberrant protein transcription and DNA mutations, affecting mitochondrial metabolism and inducing cellular stress.  In vitro produced embryos under high oxygen culture conditions may also suffer oxidative stress, with the resulting reactive oxygen species causing mitochondrial DNA mutations and cellular stress similar to clones.

In this study, expression of oxidative stress protein markers (Hsp60, SOD2, Hsp70) in NT cotyledons were compared to artificial insemination (AI) at different time points of gestation (days 50, 100, and 150).  As a continuum of the oxidative stress investigation in cloned cotyledons, in vitro produced embryos were cultured under 20% oxygen compared to the control 7% oxygen laboratory standard culture, with oxidative stress protein markers examined between the groups at blastocyst stage (day 7) and day 15.  Embryo morphology was also observed to determine apparent physiological differences between the treatment and control embryos.  No previous studies to date have investigated the developmental effects of oxidative stress in day 15 bovine embryos.
 
The significant differences in oxidative stress proteins observed at several time points in the NT and AI groups were not repeatable, possibly due to sample freeze/thaw degradation.  Morphological differences observed between embryos cultured in 20% oxygen and control groups were visually apparent, although not quantified.  At day 15 manganese superoxide dismutase expression was significantly lower in the 20% group compared to control.  The 20% oxygen group did not show higher heat shock protein 60 expression than control, however the same results have been observed in another study at blastocyst stage.  The results of this study suggest that the effect of oxidative stress on embryonic development is evident yet inconclusive in bovine NT cotyledons, however does not appear apparent in day 15 embryos following culture in 20% oxygen.

year: 2007

title: Vegetation studies in the Taranaki land district, New Zealand

authors: Clarkson, Bruce D.

abstract: Sampling of the indigenous vegetation of the Taranaki Land District was carried out to describe and explain significant features of vegetational change along environmental gradients. Five major locations were sampled; the three volcanic mountains of Egmont National Park (Egmont, Pouakai and Kaitake), the associated volcanic ring plain and the Taranaki Upland. The sampling which was mainly along altitudinal and moisture gradients involved the collection of both quantitative and semi-quantitative plot data.

Direct and indirect gradient analyses were then carried out on the data; the techniques employed included graphing, ordination and classification. Analysis enabled the definition of the main vegetation types at each of the sampling locations and of the important environmental factors associated with the vegetation pattern. 

Comparison of the results obtained at each of the sampling locations revealed differences in the structure and composition of the vegetation and in the pattern of vegetational change along the gradients. The three volcanic mountains within Egmont National Park show differences in the vegetation consistent with the sequence of volcanic activity (the Taranaki Volcanic Succession). Sectors of Mt Egmont exhibit differences which relate closely to the pattern of recent eruptions particularly the Burrell eruption of 1655 A.D. The vegetation at equivalent altitudes on Pouakai, an older more eroded volcanic remnant, is at a more advanced stage of development. A complex pattern of species (woody species and tree ferns) distribution on the three mountains (Egmont, Pouakai and Kaitake) is outlined and attributed in some instances to the changing availability of habitats on each mountain. This is associated with the sequence of mountain building, erosion and dissection. The vegetation pattern of the Taranaki Upland by contrast more closely reflects the pattern of topography and substrate and the forests are richer in vascular species. Analysis of the distribution of species (woody species and tree ferns) shows that inland Taranaki was the probable source for almost all of the species found in the forests of Egmont National Park. 

Comparisons of the pattern of vegetational change along altitudinal gradients of the mountains of Egmont National Park and some other southern hemisphere mountains reveal certain similarities. With respect to other North Island (New Zealand) volcanic mountains examined the similarities are marked. Like Mt Egmont, Pouakai and Kaitake these mountains all support podocarp-broadleaved forests from which the beech species (Nothofagus spp.) are absent. The forests of Egmont National Park are interpreted as illustrating stages of a landscape and vegetation succession apparent on volcanic mountains throughout the North Island. Features which characterise the present stage of development of the forests of Mt Egmont include the overwhelming dominance of kamahi (Weinmannia racemosa var. racemose), the absence of forest tree species such as quintinia (Quintinia serrata) and the relatively low altitude tree-line.

text: Vegetation studies in the Taranaki land district, New Zealand Sampling of the indigenous vegetation of the Taranaki Land District was carried out to describe and explain significant features of vegetational change along environmental gradients. Five major locations were sampled; the three volcanic mountains of Egmont National Park (Egmont, Pouakai and Kaitake), the associated volcanic ring plain and the Taranaki Upland. The sampling which was mainly along altitudinal and moisture gradients involved the collection of both quantitative and semi-quantitative plot data.

Direct and indirect gradient analyses were then carried out on the data; the techniques employed included graphing, ordination and classification. Analysis enabled the definition of the main vegetation types at each of the sampling locations and of the important environmental factors associated with the vegetation pattern. 

Comparison of the results obtained at each of the sampling locations revealed differences in the structure and composition of the vegetation and in the pattern of vegetational change along the gradients. The three volcanic mountains within Egmont National Park show differences in the vegetation consistent with the sequence of volcanic activity (the Taranaki Volcanic Succession). Sectors of Mt Egmont exhibit differences which relate closely to the pattern of recent eruptions particularly the Burrell eruption of 1655 A.D. The vegetation at equivalent altitudes on Pouakai, an older more eroded volcanic remnant, is at a more advanced stage of development. A complex pattern of species (woody species and tree ferns) distribution on the three mountains (Egmont, Pouakai and Kaitake) is outlined and attributed in some instances to the changing availability of habitats on each mountain. This is associated with the sequence of mountain building, erosion and dissection. The vegetation pattern of the Taranaki Upland by contrast more closely reflects the pattern of topography and substrate and the forests are richer in vascular species. Analysis of the distribution of species (woody species and tree ferns) shows that inland Taranaki was the probable source for almost all of the species found in the forests of Egmont National Park. 

Comparisons of the pattern of vegetational change along altitudinal gradients of the mountains of Egmont National Park and some other southern hemisphere mountains reveal certain similarities. With respect to other North Island (New Zealand) volcanic mountains examined the similarities are marked. Like Mt Egmont, Pouakai and Kaitake these mountains all support podocarp-broadleaved forests from which the beech species (Nothofagus spp.) are absent. The forests of Egmont National Park are interpreted as illustrating stages of a landscape and vegetation succession apparent on volcanic mountains throughout the North Island. Features which characterise the present stage of development of the forests of Mt Egmont include the overwhelming dominance of kamahi (Weinmannia racemosa var. racemose), the absence of forest tree species such as quintinia (Quintinia serrata) and the relatively low altitude tree-line.

year: 1981

title: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability

authors: Morad, Munir

subjects: postcolonialism

abstract: New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

text: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

year: 2003