Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Subject: search.filters.subject.Genetic engineering

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Characterisation of malate-dependent mutants of the yeast Schizosaccharomyces malidevorans : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Genetics at Massey University
    (Massey University, 1991) Hansen, Nicolette Olivia
    The phenotypes of several UV induced malate-dependent mutants of Schizosaccharomyces malidevorans were characterised and compared to the previously characterised malate-dependent strain, S. malidevorans #11. This strain uses less glucose than the wild type, has an extended life in liquid media, does not sporulate readily and turns indicator medium blue. The malate-dependent mutant strains were analysed for their fermentation characteristics, their complementation groups and their chromosomal patterns on a transverse alternating field electrophoresis apparatus (TAFE). The fermentation patterns of all of the strains were similar to #11. There appear to be three complementation groups involved in the malate-dependent phenotype. The TAFE patterns and subsequent Southern Hybridisation showed that the malate­ dependent mutants had a decreased mobility of chromosome II, while chromosomes I and III were not altered. The chromosome II alteration varied between the different malate-dependent mutants but fell into a small number of discrete patterns.
  • Thumbnail Image
    Item
    Light-induced anthocyanin pigmentation in transgenic Lc petunia : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2006) Albert, Nick William
    Introduction of Leaf colour (Lc). a bHLH transcription factor from maize, under the control of the CaMV35S promoter into petunia (cv. Mitchell) plants resulted in enhanced anthocyanin pigmentation in vegetative tissues. Anthocyanin biosynthesis was observed to be dependent on the level of light the plants were grown under: plants grown in a plastic greenhouse remained green, while plants exposed to high-light were dark purple. The nature of this response to light and the associated molecular mechanisms were the focus of this investigation. Molecular analysis of gene expression in Mitchell petunia showed that light induced the expression of the early flavonoid structural genes, as well as flavonol synthase (FLS) required for flavonol production. Light induced both the early and late structural genes required for anthocyanin biosynthesis in the transgenic Lc Mitchell petunia plants, but reduced the expression of FLS. Light-induced flavonoid gene expression was examined under three light treatments: shade (50 - 350 µmol m -2 sec -1 ); ambient-greenhouse (300 - 750 µmol m -2 sec -1 ) and high-light (750 µmol m -2 sec -1 ). The level of flavonoid gene expression was dependent upon light intensity. High-light was required to maximally activate anthocyanin pigmentation in Lc petunia. Expression of the Lc transgene remained unchanged irrespective of light intensity, indicating that the light-induced changes in anthocyanin synthesis were not due to variable expression of the transgene. Anthocyanin regulation occurs primarily at the transcriptional level, and two classes of transcription factors. Myb and bHLH. are generally involved. Transient expression studies using several exogenous Myb transcription were carried out using shade-grown (non-induced) Lc petunia material. The induction of coloured cells in the treated tissue supports the idea that the bHLH transgene (LC) is interacting with an endogenous Myb under high-light conditions, resulting in the activation of the flavonoid biosynthetic pathway and accumulation of anthocyanin pigments. A partial sequence of a candidate endogenous Myb transcription factor from petunia was cloned. It was light-induced and shares structural features with other anthocyanin-regulating Myb transcription factors, particularly An2 from petunia. This Myb in combination with LC may be responsible for the light-induced anthocyanin pigmentation observed in Lc petunia.
  • Thumbnail Image
    Item
    The environmental ethics of the corporatization of agriculture and crop genetic engineering : a thesis presented in partial fulfilment of the requirements for the degree of Master of Environmental Management at Massey University, Palmerston North, New Zealand
    (Massey University, 2017) Walker, Anna
    The corporatization of agriculture has resulted in significant implications for the environment and consequently environmental management. In particular, corporate application of genetic engineering (GE) has resulted in increased and unnecessary environmental risks through inappropriate applications of GE and increased pesticide use. GE technology has in turn allowed for the agriculture industry to become further corporatized. Current environmental management procedures with regard to risk assessment and the regulatory processes of GE crops have proven inadequate in light of such corporate involvement. The research aim of this thesis was to establish whether the corporatization of agriculture, and the consequent corporate application of GE crops, results in breaches of environmental ethics, as defined by the worldviews of biocentrism and ecocentrism. This aim was achieved through the application of a structured literature review, using an interpretive approach within the paradigm of hermeneutics. The literature analysis was carried out on peer-reviewed journal articles from the last 10 year period, within which selected articles were asked a series of interview questions in order to fulfil the research objectives, and consequently the aim. The extracted information was critically considered within the framework of environmental ethics and the contrasting worldviews of anthropocentrism, technocentrism, biocentrism and ecocentrism. The key issue identified was the lack of consideration of biocentric and ecocentric values in the arguments made by corporations and proponents of GE crops as a result of a dominance of anthropocentric and technocentric worldviews. The lack of such values on the part of corporations ensures that both sides of the debate are arguing from different perspectives and as such it seems unlikely that they will ever be able to reach a resolution. This thesis concludes that for progress to be made in the debate on GE agriculture and corporatization, and for appropriate precaution to be employed with regard to risk assessment, the worldview held by agrochemical corporations and proponents of GE needs to shift towards a biocentric and ecocentric understanding of the environment. However, as a complete shift of worldviews on the part of corporations is unlikely, this thesis recommends that attention be shifted away from the polarized controversy in favour of a discussion on coexistence.
  • Thumbnail Image
    Item
    Genetic engineering and organic agriculture : perceptions of organice exporters, producers, and consumers : a thesis presented in partial fulfillment of the requirements for the degree of Master of Applied Science in Natural Resource Management
    (Massey University, 2000) Wreford, Anita Barbara
    Genetic engineering technology is becoming increasingly widespread throughout the world. Since the late 1990s there has been intense controversy regarding its use in food production. Organic agriculture could lose or gain significantly from consumer uncertainty and apprehension regarding the genetic engineering of food products. Concerns about genetic engineering spread across the world, and organic agriculture is in a strong position to exploit consumer concerns about genetically engineered food. However, organic farming is also at risk from the cross-contamination of engineered crops, pest-resistance exacerbated by the technology, and the corruption of organic seedlines. In addition, there has been debate as to whether organic standards should be altered to permit the use of genetically engineered crops. This study attempts to gauge the attitudes of three key sectors of the organic industry in New Zealand towards genetic engineering, namely producers, exporters and consumers of organic food in New Zealand. Producers of organic food in New Zealand were questioned regarding their views on genetic engineering, and whether they would consider incorporating genetically engineered crops in their food production. Exporters of New Zealand organic produce were questioned on the international organic markets and the exporters own opinions of consumer concerns towards genetically engineered food. Consumers of organic food were surveyed on their attitudes and beliefs about genetic engineering, and the possibility of genetically engineered organic food. Results for each survey sample were analysed using the statistical package SPSS. The results show conclusively that organic exporters, producers and consumers do not want to eat or grow genetically engineered organic food. This appears to be based on intrinsic and ethical concerns as much as environmental and health concerns. Even if reassured about the safety of genetically engineered food to the environment and to human health, most organic consumers claim they would not eat it. It is concluded that there is no future for genetic engineering in the organic industry. The industry would be wise to take advantage of the general consumer unease towards genetic engineering. Research into alternative methods of pest control would also be advised. Keywords: Organic agriculture, Genetic engineering, Genetically modified organism, Consumer perception.
  • Thumbnail Image
    Item
    Transformation and gene targeting in Aspergillus nidulans : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Molecular Genetics at Massey University, Palmerston North
    (Massey University, 1996) Bird, Dianne Maria
    Transformation of a haploid Aspergillus nidulans pyrG auxotrophic strain (1-85) was optimised for the vector pGM32 containing the heterologous Neurospora crassa pyr4 gene. The resulting uracil-independent transformants could be classified into two main groups based on morphology. The minority were morphologically very similar to the parental strain, easily purified and mitotically stable. The majority (10 times more frequent) were irregular in shape and shown to be heterokaryons that could not be resolved into transformed homokaryons. Analysis of the transformant types suggested regulation of multiple copies of the gene for OMPdecase (pyr4 and pyrG) resulted in the titration/inactivation of essential trans-acting factors. The heterokaryon state was therefore a requirement for the survival of transformants containing multiple copies of the integrated vector. The effect of altering the conditions of transformation on the efficiency of gene targeting in filamentous fungi was studied. The A. nidulans niaD and amdS genes, both involved in nitrogen source utilisation, were selected as target loci. Insertional inactivation vectors were constructed (based on pGM32) and parameters shown to have an effect on the targeting frequency at the niaD locus were subsequently tested at the amdS locus. A dramatic difference in targeting was observed between the niaD and amdS loci with targeting of niaD being much more efficient than amdS for the parameters tested. The level of gene targeting using circular DNA was found to correlate with the size of the homologous segment at both loci. Similarly the level of targeting was shown to increase at both loci when vectors were linearised within the region of homology. Unexpectedly the level of targeting was unaltered at the niaD locus when transcription was induced at different stages in the transformation procedure. Likewise targeting was unaffected by altering the amount of DNA in the reaction mix. The regeneration temperature, however, did appear to have an effect on targeting, with enhanced targeting observed at the lower temperature. Gene replacement by transformation was used to disrupt the cycA gene in diploid and haploid A. nidulans strains. The first completely deficient cyc mutant in a filamentous fungus was isolated and shown to be non-lethal. Haploidisation analysis of the diploid transformant localised the chromosomal position of cycA to chromosome I.
  • Thumbnail Image
    Item
    A nopaline-type overdrive element, and its influence upon Agrobacterium-mediated transformation frequency and T-DNA copy number in Nicotiana tabacum : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Molecular Genetics at Massey University, Palmerston North, New Zealand/Aotearoa
    (Massey University, 1996) Griffiths, Andrew Gilbert
    Overdrive is an enhancer element located outside and adjacent to the right border of the T-DNA in Agrobacterium tumefaciens octopine-type tumour-inducing (Ti) plasmids. This element is necessary for maximal enhancement of T-strand production and subsequent A. tumefaciens-mediated plant transformation frequency, and only the octopine-type overdrive had been characterised in any detail. A putative overdrive has been identified in the nopaline-type Ti-plasmid pTiT37 on the basis of its homology with known octopine-type overdrive sequences, particularly the eight base-pair so-called overdrive consensus core. The putative nopaline-type overdrive core, however, is only 75% homologous to that of all known overdrive core regions. Furthermore, as there are other sequences throughout the nopaline-type T-region that share 75% homology with the overdrive consensus core, the precise location of the nopaline-type overdrive is undetermined, although all nopaline-type T-region fragments exhibiting overdrive-like activity contained the putative overdrive core adjacent to the right border. The role of this particular putative core in T-DNA transfer has never been established. Deletions were made in the putative nopaline-type overdrive consensus core adjacent to the right border of a binary plant transformation vector derived from pTiT37. This was to establish whether this putative overdrive core does have a role as a transmission enhancer as proposed (Peralta et al., 1986; Van Haaren et al., 1988; Culianez-Macia and Hepburn, 1988). Two deletions were selected for the full study. The first encompassed the putative nopaline-type overdrive core flanked by 3 bp (5') upstream, and 4 bp (3') downstream, and was located in pANDY9. The other, located in pANDY10, encompassed the putative consensus core plus the entire region sharing homology with the octopine-type overdrive. This second deletion was to determine whether the core alone could account for overdrive-like activity, or whether further sequences are necessary to produce the effect. The vector with no deletions in the putative nopaline-type overdrive region was pANDY8. As determined by quantitative Nicotiana tabacum transformation assays, both deletions of the putative nopaline-type overdrive core (pANDY9, pANDY10) equally decreased the rate at which calli appeared, and equally decreased transformation frequency by 47% compared with that of pANDY8. That deletion of the putative core influenced plant transformation frequency provided strong evidence that it was indeed an overdrive-like core. Furthermore, in a virC2 mutant environment, the plant transformation frequency was reduced markedly for all three plasmids (approximately 90% reduction compared to when in the wild-type vir environment). However, there was no difference in the plant transformation frequencies of the pANDY8-10 series in a virC2 environment. This indicated that the mechanism by which the deletions influenced plant transformation frequency did not act independently of the virC operon, which is further evidence of overdrive-like activity. The type of vir regulon influenced the effect of the deletions in the putative overdrive. The transformation frequency of the plasmid with the intact putative overdrive region (pANDY8) was very similar in both an octopine-type vir environment (21.7 organogenic calli per 10 leaf discs in LBA4404) and a nopaline-type vir environment (18.7 organogenic calli per 10 leaf discs). However, in an octopine-type vir environment, deletions in the putative core resulted in a 47% decrease in transformation frequency, whereas in a nopaline-type vir environment the deletions had no effect upon transformation frequency. This may be due to a higher level of vir gene products (a feature associated with nopaline-type vir regulons), particularly VirDl and VirD2 compensating for the lack of a fully active putative overdrive. Southern analysis of plants arising from the transformation experiments (in an octopine-type vir environment) revealed that removal of the putative nopaline-type overdrive core halved the incidence of multiple T-DNA insertion events from 34.7% (pANDY8, intact nopaline-type overdrive) to 12.2% (pANDY9) and 14.3% (pANDY10). Deletion of the nopaline-type overdrive core also restricted the insert number to a maximum of two, rather than four or more. This is the first time that deletions in the regions outside the T-DNA have been shown to influence T-DNA copy number.
  • Thumbnail Image
    Item
    Making resistance politics : the opposition to genetic engineering in Aotearoa New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Sociology
    (Massey University, 2011) Tucker, Corrina Adele
    The politics making of genetic engineering resistance in Aotearoa New Zealand involves a complex interplay between a diverse core of movement network actors and a broad, mediated collective identity. The movement’s organisational structure and cultural meanings comprise both diversity and cohesion, which enhance each other, making for successful politics making. This thesis demonstrates how these seemingly contradictory movement features were able to coexist. Drawing on in-depth interviews with 18 key activists, this research investigated how the movement was structurally and culturally organised. Previous social movement analyses have tended to separate structure from culture, resulting in one-sided interpretations that have not adequately addressed the role both elements play in making politics. To overcome this shortcoming, this thesis developed a complementary approach to methodology and analysis that drew on social network analysis to investigate organisational structure, and framing to explore meaning-making and the achievement of collective identity. The network structure of the movement is decentralised, non-hierarchical, flexible and complex. This has enabled both diversity (seen in movement sub-groups, strategic and tactical disparities), and coordination (seen in the significant overlap of relational ties and the convergence of actors in mass mobilisations), to exist at the same time. The same kinds of characteristics are evident when looking to framing and movement collective identity. Activists relayed a broad range of oppositions to genetic engineering, but at the same time their concerns were shared at an elementary level, and were posed as challenging common understandings of Aotearoa New Zealand. The movement was therefore deeply engaged with and embedded in the wider cultural context of this country. The characteristics of flexibility and embeddedness displayed in this movement are a powerful combination for movement mobilisation and endurance. Until there is a commercial release of a genetically engineered crop in this country, the potential for future mobilisation remains.