published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

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This study analyzes the economic impact of a recent gene marker innovation for seedstock selection in beef cattle. Gene markers are being developed for many beef cattle attributes; this study focused on the tenderness quality of beef using two categories: tender and tough. The study begins by describing conventional procedures for seedstock selection, the science which underlies selection by gene markers and other non-genetic procedures currently being used to improve beef tenderness. After describing the commercialization of the gene marker innovation, a stylized model of a beef supply chain is constructed. The supply chain consists of a representative consumer, a producer/processor group and a monopolist supplier of the patented technology. Welfare changes resulting from the adoption of the innovation were simulated using four sets of demand elasticity data from literatures. An important focus of this research is determining how the economic surplus from the innovation will be shared by consumers, producers and the gene marker monopolist. The consumer and gene marker monopolist benefit from the technology unless the marginal and fixed cost variables (not estimated in this study) of the monopolist, are excessively high. Producer surplus was simulated as positive with three of the four elasticity data sets. The share of surplus capture by producers is generally low relative to the gains captured by consumers and the gene marker monopolist. Comparative static analysis reveal that the benefit from the innovation varies across breeds, being higher for breeds in which the favorable form of the marker gene is more likely to be present. Despite the apparent benefits of the innovation for beef supply chain participants, reported interviews with industry scientists reveal that markers should not be viewed as a replacement for conventional selection techniques. Indeed, selecting seedstock on the basis of a small number of available markers is not likely to produce the benefits that are currently being promised by life science companies. Consequently, this study recommends that the innovation be incorporated into existing seedstock selection practices. Much more analysis is needed to understand the full economic impact of gene markers for beef tenderness and for other beef quality attributes.

The present study is concerned with the issue of discourse markers as text forming devices in the English discourse. We base our research on the following hypotheses: - discourse markers are indispensable in all registers - though some discourse markers can be met across several registers and their functions may overlap, the register itself determines the choice of discourse marker On the basis of the existing and available researches on discourse markers we aim to define the functions discourse markers play in a coherent text. On the basis of quantitative and qualitative approaches to the obtained data we aim to reveal distribution of discourse markers in certain registers. The research is based on the analysis of the texts of four different registers: drama, which is considered to be closest to spoken discourse, academic prose, legal documents and newspaper articles. The scope of the research material is fifty pages of each text. The paper is divided into three parts: •PART 1 examines some basic notions in text linguistics. It provides an overview of the concepts of discourse, cohesion, textuality, cohesive devices and the notion of register and its components. •PART 2 of the paper gives a closer outlook of discourse markers. It presents points of view of such linguists as Halliday and Hasan (1992), Schiffrin (1987), Blakemore (1987), Fraser (1996), Trujillo Saez (2003) on the definition and delimitation of these particles. Also, the discussion of the functions of these... [to full text]

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Genetic variation within and between two cultivars of red clover (Trifolium pratense L.), Essi from Europe and Ottawa from Canada was estimated using morphological, isozyme and random amplified polymorphic DNA (RAPD) markers. A total of 21 enzyme-coding loci with 43 alleles was detected using twelve enzyme systems. The mean number of alleles per locus was 1.81 in Essi and 1.67 in Ottawa. Nine 10-mer primers were used to assay 20 individuals from each cultivar for RAPD markers. Each primer gave from 7 to 20 amplified bands with an average of 14.8 bands per primer. High within-cultivar variation was observed in both cultivars using both isozyme and RAPD markers. The mode of inheritance of seven isozyme loci: Aat-2, Amy-1, Est-4, Est-7, Pgd-1, Pgd-2 and Skd-1, in red clover was verified. The genetic basis of banding patterns for 16 other isozyme loci: Aat-3, Adh-1, Dia-1, Dia-2, Dia-3, Est-1, Est-2, Gpi-2, Idh-1, Mdh-1, Mdh-2, Mdh-3, Mdh-4, Me-1, Me-2 and Pgm-2, was also postulated, based on the segregation patterns observed within cultivars. Two pairs of linked enzyme-coding loci, Est-4/Est-7 and Pgd-2/Skd-1, were found with joint segregation analysis. Estimates of genetic variability of 15 red clover cultivars from three different origins indicated that within-cultivar variation was much higher than between-cultivar variation. Allele frequencies of these isozymes could discriminate the five North American cultivars assayed, but they could not differentiate cultivars from Europe and Japan. The use of RAPD markers obtained from bulked samples was investigated for cultivar identification in red clover. Pooled samples were examined in order to minimize variation within cultivars. Twenty was found to be an appropriate number of red clover individuals per bulk for homogenizing genetic variation within cultivars. Fourteen 10-mer primers were used to amplify genomic DNA from combined leaf samples of 15 red clover cultivars from European, Japanese and North American origin

Ancient DNA (aDNA) was isolated from the bones of 290 individuals and four species of extinct New Zealand moa. All sampled bones had been recovered from a small geographic area (~10 km radius) near Waikari in North Canterbury. A total of 217 specimens were 14C-AMS dated, providing a temporal framework for the genetic analyses and an unprecedented opportunity to study extinct megafauna at the population level. Taxon and sex were determined for each individual, using aDNA technology. This revealed a large excess of females (overall ♂:♀ = 1:5.1), and significant compositional differences for the moa assemblages between fossil sites. Balanced sex ratios were observed among juvenile moa, suggesting that a gender-bias developed as the birds matured, probably as a result of higher male mortality. Female territoriality and ecological niche-separation are discussed in this context. Mitochondrial DNA (mtDNA), amplified using a quantitative PCR procedure, provided a measure of DNA preservation in each radiocarbon-dated fossil. This assessment showed that DNA degrades over thousands of years according to an exponential decay model, and the average molecular half-life for the here targeted DNA fragment was estimated to be 521 years. By using high-throughput sequencing, six polymorphic moa microsatellite markers were identified and characterised. These are the first microsatellite primers developed exclusively for extinct taxa. A high-resolution genetic study of the four sympatric moa populations was carried out, combining information from mtDNA, microsatellites, sex-identification, and radiocarbon age. Genetic diversity, past demography, kinship, and other aspects of moa biology were analysed. The populations showed a remarkable extent of genetic stability throughout the 3000-4000 years preceding their extinction, suggesting that they were large and viable before suddenly disappearing. The results represent significant advances in aDNA research and thanks to the high resolution in microsatellite markers, moa have here been studied, almost as if they were still alive.