Thesis (MScMed)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (M.A.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 87-96). Also available on the World Wide Web.

Thesis (Ph.D.)(Agricultural Economics)--University of Pretoria, 2007. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (MScFor (Forest and Wood Science))--Stellenbosch University, 2008. / This study sought to examine the effects of soil fertility replenishment (SFR) adoption on household security and poverty reduction in smallholder farming households of central and southern Malawi by assessing food security, asset status, and household income generating activities in Kasungu and Machinga Districts during 2007. The results showed that households had been able to significantly increase maize production by an extra 382 kg per year in Kasungu and 242 kg per year in Machinga Districts, which constitutes approximately 35% and 22% of average household maize requirements for the year for each district, respectively. This reduced the critical annual hunger periods from 3.46 months to 2.80 months per year in Kasungu and from 4.31 months to 3.75 months in Machinga. Respondents also reported a significant increase in assets and an increase in income. Despite these positive changes, households were found to still be living in extreme poverty. Selling physical assets was the most common response to shocks and any increase in income was allocated to the purchase of food, household supplies, and other items necessary to immediate survival. This study revealed that while food security is paramount to the sustainable livelihoods of smallholder farmers, livelihood security and poverty reduction depend on more than increased food production. SFR technologies are fulfilling their primary role as a means to food security, but their adoption does not lead to significant livelihood improvements. Achieving lasting impacts requires that initiatives take an integrated approach and address not only household food production, but the multifaceted dynamics of social institutions, markets/economy, and policy. The long-term impacts of the current agroforestry programs in the study areas will emerge only with time. Livelihood improvements will depend on several factors. First, market inefficiencies must be remedied and economic barriers must be broken down. Second, the challenges identified by the respondents, especially access to resources and training, need to be addressed in a participatory way that promotes education and empowerment. As these two issues are tackled, households will become better equipped to manage the complexities that arise from SFR adoption and livelihood diversification. It is recommended that future research and initiatives should focus on identifying and removing economic barriers to markets, addressing farmeridentified challenges such as access to seed, water, and education and training, supporting households in managing multiple livelihood strategies, and continuing research to identify appropriate agroforestry species and technologies.

Orientador: Anaglória Pontes / Resumo: O câncer de mama é uma doença maligna relativamente comum em mulheres adultas jovens, justificando a preocupação com a potencial toxicidade gonadal relacionada à quimioterapia. É importante considerar o encaminhamento precoce de pacientes jovens com câncer de mama que tenham desejos reprodutivos para especialistas, a fim de discutir sobre a preservação da fertilidade. A criopreservação de embriões ou de oócitos estão entre os principais métodos à disposição, e para conseguir isso, estimulação ovariana controlada (EOC) é o primeiro passo a ser considerado. O presente estudo tem como objetivo apresentar protocolo de estimulação ovariana em para preservação da fertilidade em pacientes com câncer de mama. De novembro de 2014 a dezembro de 2016, 109 pacientes com câncer de mama com menos de 40 anos de idade foram selecionadas para preservar seu potencial reprodutivo. Elas foram divididas de acordo com a fase do ciclo menstrual em que o estímulo ovariano foi iniciado: fase folicular inicial, fase folicular tardia e fase lútea. Para reduzir o tempo necessário da obtenção dos oócitos, este estudo utilizou o princípio do início aleatório, no qual a EOC pode ser iniciada durante qualquer período do ciclo menstrual sem consequências negativas. O letrozol foi utilizado durante toda a estimulação para diminuir as concentrações de estradiol, independentemente da imunohistoquímica tumoral. Na presença de tumores positivos ao estradiol, e indicação de quimioterapia neoadjuvante, o tamoxi... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Breast cancer is a relatively common malignancy in young adult women, justifying the concern about the potential gonadal toxicity related to chemotherapy. It is important to consider early referral of young breast cancer patients with reproductive desires to fertility specialists, in order to discuss the fertility preservation. Embryos or oocytes cryopreservation are among the main methods available, and to achieve that, controlled ovarian stimulation (COS) is the first step to be considered. From November 2014 to December 2016, 109 breast cancers patients under 40 years were enrolled to preserve their reproductive potential. They were divided according to the menstrual cycle status in: initial follicular phase, late follicular phase and luteal phase. In order to reduce the time necessary to obtain the oocytes, this study used the principle of random start, in which the COS can be initiated during any period of the menstrual cycle without negative consequences. Letrozole was used during all stimulation to reduce estradiol concentrations, regardless of tumor immunohistochemistry. In the presence of estradiol positive tumors, and indication of neoadjuvant chemotherapy, tamoxifen was administerd as an additional protective measure. A GnRH agonist was used to trigger ovulation, in order to mitigate the risk of ovarian hyperstimulation syndrome. The following parameters were analyzed: age, day of COS start, number of days required to COS, total FSH dosage, estradiol levels at fi... (Complete abstract click electronic access below) / Mestre

No description available.

Indigenous agroforestry systems, or the intentional use of trees and livestock in croplands, have a long history in the West African Sahel. In many locations, they have long contributed to food security and climate change resilience. But a century or more of cash cropping and use of modern agricultural inputs and tools has meant that no such agroforestry systems remain intact, and many are extinct, including in west-central Senegal, where the Serer historic mixed farming and pastoral strategies previously provided resilience to cyclical droughts and colonial-era agricultural and economic change but are now neither intact nor extinct. This study examines the current state of Serer agroecosystems, considering who uses what elements of the old systems, who has introduced what elements of nonindigenous farming systems, and whether this combination of local and imported farming systems is a coherent and sustainable fusion, or an incoherent pastiche leading toward agrarian collapse. I argue that, depending on how farmers integrate new models with the technical and cultural elements of the old system, a coherent fusion may result, with positive implications for sustainability, climate change adaptation, soil replenishment, crop yield, and livelihood resilience. This mixed-methods study draws upon literature from cultural ecology, agroecology, socioecological resilience, and history to interpret farmers’ accounts of changing agrarian practices. The study links ethnographic findings to empirical analysis of soil conditions and land use change. With these tools, my research sheds new light on the evolving role of local techniques and knowledge in the struggle to maintain agricultural productivity, as Sahelian communities confront soil fertility depletion, food insecurity, and climate change. The study finds that farming communities in this region can strengthen their livelihood resilience and enhance crop yields if they update elements of the well-adapted historic farming system, employ new techniques and tools, and in the process, forge coherent farming systems that still make cultural sense to farmers. / 10000-01-01

The maintenance of genomic stability through suppression of retrotransposon activity is vital for the avoidance of potentially mutagenic genomic disruption caused by retrotransposition. Germline development is a particularly important phase for retrotransposon silencing as retrotransposition events here have the potential for transmission to the entire embryo, threatening the health of offspring. A collection of germline genome defence genes are required for the suppression of retrotransposons in the developing germline of male mice (e.g. Tex19.1, Dazl, Mili, Miwi2, Gasz, Mov10l1, Mael, Dnmt3l), all of which trigger meiotic prophase arrest when mutated. I have analysed the meiotic defects which arise in Tex19.1-/- male mice to contribute to the understanding of the fundamental mechanisms required for successful completion of meiosis and to investigate the involvement of retrotransposon silencing in this process. The absence of TEX19.1 in male mice causes infertility; with failed chromosome synapsis in ~50% of pachytene nuclei and associated apoptosis, as well as individual univalent chromosomes in 67% of remaining nuclei progressing to metaphase I. Where studied, failed chromosome synapsis is a common feature of germline genome defence mutant spermatocytes. One aim of my studies has been to better understand the mechanism responsible for this failed chromosome synapsis. I have demonstrated that unlike Mael-/- spermatocytes, additional SPO11-independent DNA damage potentially attributable to retrotransposition is not detectable in Tex19.1-/- spermatocytes. Rather, the formation of meiotic DNA double strand breaks (DSBs) is dramatically reduced in early prophase to around 50%, resulting in a reduction in nuclear γH2AX signal, production of SPO11- oligonucleotide complexes and foci formation by early recombination proteins RPA, DMC1 and RAD51. Despite this early reduction, DSB frequency recovers to more normal levels shortly after in zygotene. I have shown that defective pairing of homologous chromosomes by meiotic recombination is likely responsible for the asynapsis previously reported. The initial reduction in DSB frequency could be sufficient to cause failed chromosome synapsis in this mutant, assuming that late-forming DSBs cannot participate effectively in promoting homologous pairing. Alternative hypotheses include altered positioning of DSBs in response to altered chromatin organisation relating to retrotransposon upregulation, misguiding the pairing of homologous chromosomes. Such a model of disruption could also extend to other germline genome defence mutants. I have demonstrated that despite successful pairing of homologous chromosomes in a sub-population of Tex19.1-/- spermatocytes, subsequent progression of these cells through pachytene is delayed. Numerous diverse features of progression are all delayed, including recombination, ubiquitination on autosomes and sex chromosomes, expression of the mid-pachytene marker H1t, and chromosome organisation. The delay identified is related to recombination therefore this feature is likely to stem from the initial defect in DSB formation early in prophase. While some delayed features are probably directly related to recombination, others are not. The coordinated delay observed may suggest the presence of a recombination-sensitive cell-cycle checkpoint operating to regulate progression through pachytene. My research has also aimed to establish the cause of elevated univalent chromosomes not connected by chiasmata in metaphase I Tex19.1-/- spermatocytes. I have demonstrated that that absence of chiasmata is not due to failed crossover formation between synapsed chromosomes. Rather, the frequent observation of individual unsynapsed chromosomes during crossover formation suggests that some spermatocytes with low-level asynapsis are leaking through meiotic checkpoints and are unable to form a crossover before reaching metaphase. Therefore, again this later meiotic defect appears to stem from the initial defect in meiotic DSB formation, the consequences of which vary widely in severity. Remarkably the unsynapsed chromosomes present during crossover formation include both sex chromosomes, and autosomes. Tolerance of an unsynapsed autosome from pachytene into metaphase is an unusual observation in mice and this observation may aid the understanding of spermato cyte quality control mechanisms during this progression. Together these findings have greatly advanced the understanding of the infertility incurred during meiosis in Tex19.1-/- male mice. These findings may also extend to benefit the understanding of other germline genome defence mutants. Diverse observations made during my investigations also reveal a potential system of coordinated progression through pachytene relating to meiotic recombination. The variable severity of the synapsis defects incurred in this mutant appears to have variable effects on spermatocyte survival and could also inform the understanding of meiotic checkpoint sensitivity.

The aim of this study is to evaluate the reproductive and productive indicators of Landrace pig breeding. Sows of basic herd and breeding nucleus are divid into four groups according to the age of the gilts, sows at risk litters, the sows producing litters and sows for 6 or more litters. Reproductive indicators of sows, fertility (number of piglets born, number of piglets born alive, number of piglets weaned) and milk production, are evaluat. Comparing the results of the observed Landrace pig herd population in the Czech Republic, it found that better results are achieved by breeding Landrace population. The achievement in the observed enterprise is 15.8 ? 2.2 units of all piglets born in a litter, 14.4 ? 2.3 units of piglets born alive per litter and number of piglets wean per litter is 9.4 ? 1.6 piglets. Population reaches fewer piglets born in a litter and more of the preserv. This proves that breeding must seek to reduce differences between piglets born and preserv. This is relat to milk production of sows, which is also below the average for the whole population. Furthermore, the results of the performance of gilts and male pigs according to the methodology for field testing are evaluat. For performance testing the average backfat thickness (mm) of lean meat (%) and average daily gain (g) in the unified testing are assessed. Population achieves better results in the proportion of lean muscle in both gilts and male pigs for both monitoring years. The greatest difference is reach in 2013 with male pigs and that is about 7%. Backfat thickness is on average about 1 mm higher than the reference breeding population. Nowadays the interest in breeding animals is decreasing. In 2013, 3 male pigs and 88 gilts were sold.

The aim of the paper is to evaluate the status of breeding work in the reserve stock for selective breeding in Czech Landrace pigs. Evaluation covers the reproductive and productive indicators. The sows of the base stock are split into four groups by age structure: gilts, sows with risk litters, sows with production litters and sows with litter 6 or more. Evaluation covers reproductive indicators, i.e. fertility (number of piglets born, number of live-born piglets and number of surviving piglets) and milk production. The enterprise under evaluation achieved an average of 13 live-born piglets and 11 surviving piglets per sow and litter; the farrowing interval is seven days longer compared with what is normally reported as the best time. Evaluation covers the results of individual performance in gilts and male pigs according to the methodology for field tests. For individual performance, the assessment covers the average daily gain (g), the average backfat thickness (mm) and lean meat percentage (%). The herd shows a smaller gain, while backfat thickness and lean meat percentage is comparable with the population. Key words: Number of piglets, sow, fertility, performance