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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Genotypic and phenotypic chacterization of maize testcross hybrids under stressed and non stressed conditions

Ganunga, Rosan Paterson 25 April 2007 (has links)
Drought and low soil nitrogen are major factors limiting maize production in Sub-Saharan Africa. Genotypic and phenotypic characterization of maize testcross hybrids developed from four biparental populations: CML441 x CML444, CML440 x COMPE, CML444 x K64R and CML312 x NAW was conducted. The objectives were (a) to evaluate the performance of F2:3 line testcrosses across stressed and non-stress conditions, (b) to estimate heritabilities for grain yield and secondary traits, (c) to assess the relationship between testing environments, (d) to estimate genetic correlations among relevant traits, (e) to estimate direct and indirect genetic gain from selection, and (e) to have a preliminary assessment of the efficiency of marker-assisted selection. Studies were conducted under no nitrogen fertilization, low nitrogen, drought, well- watered and high nitrogen in Malawi and Zimbabwe. About 100 entries from each population were tested using an alpha lattice design with two replications at all locations. Traits measured were grain yield, plant height, anthesis date, anthesis-silking interval, ears per plant, grain moisture at harvest and leaf senescence. Highest grain yield across environments was obtained from population CML444 x K64R (3.82 Mg ha-1) and the lowest from CML440 x COMPE (3.64 Mg ha-1). Testcrosses from CML441 x CML444 and CML444 x K64R had higher heritability estimates compared to CML440 x COMPE and CML312 x NAW. Drought and high nitrogen environments had higher heritability estimates than low nitrogen and well-watered conditions. Drought and well-watered environments discriminated testcrosses in a similar manner as well as high and low nitrogen environments. All populations had negative correlations between grain yield and anthesis silking interval, while positive correlations were observed between grain yield and ears per plant. No consistent differences were observed between overall means of best and worst marker based selected line testcrosses across populations and environments. Highest direct expected genetic gains were observed from high nitrogen environments. Direct selection under specific environments (e.g. drought ) was estimated to be more beneficial than indirect selection in other environments.
2

Genotypic and phenotypic chacterization of maize testcross hybrids under stressed and non stressed conditions

Ganunga, Rosan Paterson 25 April 2007 (has links)
Drought and low soil nitrogen are major factors limiting maize production in Sub-Saharan Africa. Genotypic and phenotypic characterization of maize testcross hybrids developed from four biparental populations: CML441 x CML444, CML440 x COMPE, CML444 x K64R and CML312 x NAW was conducted. The objectives were (a) to evaluate the performance of F2:3 line testcrosses across stressed and non-stress conditions, (b) to estimate heritabilities for grain yield and secondary traits, (c) to assess the relationship between testing environments, (d) to estimate genetic correlations among relevant traits, (e) to estimate direct and indirect genetic gain from selection, and (e) to have a preliminary assessment of the efficiency of marker-assisted selection. Studies were conducted under no nitrogen fertilization, low nitrogen, drought, well- watered and high nitrogen in Malawi and Zimbabwe. About 100 entries from each population were tested using an alpha lattice design with two replications at all locations. Traits measured were grain yield, plant height, anthesis date, anthesis-silking interval, ears per plant, grain moisture at harvest and leaf senescence. Highest grain yield across environments was obtained from population CML444 x K64R (3.82 Mg ha-1) and the lowest from CML440 x COMPE (3.64 Mg ha-1). Testcrosses from CML441 x CML444 and CML444 x K64R had higher heritability estimates compared to CML440 x COMPE and CML312 x NAW. Drought and high nitrogen environments had higher heritability estimates than low nitrogen and well-watered conditions. Drought and well-watered environments discriminated testcrosses in a similar manner as well as high and low nitrogen environments. All populations had negative correlations between grain yield and anthesis silking interval, while positive correlations were observed between grain yield and ears per plant. No consistent differences were observed between overall means of best and worst marker based selected line testcrosses across populations and environments. Highest direct expected genetic gains were observed from high nitrogen environments. Direct selection under specific environments (e.g. drought ) was estimated to be more beneficial than indirect selection in other environments.
3

A family-based study investigating the genetic basis of calcium-containing kidney stones

Griffin, Damian Gerard January 2001 (has links)
No description available.
4

Variabilidade genética para o teor de óleo entre progênies autofecundadas de mamona (Ricinus cummunis L.) da cultivar guarani

Myczkowski, Mirina Luiza [UNESP] January 2003 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T19:27:26Z : No. of bitstreams: 1 myczkowski_ml_me_botfca.pdf: 94102 bytes, checksum: acf2ae8422a1d023a113297ec3036a90 (MD5) / O presente trabalho teve como objetivo avaliar a variabilidade genética para teor de óleo entre progênies autofecundadas da cultivar de mamona Guarani. O material utilizado foi constituído de 135 progênies obtidas de plantas individuais, por meio de autofecundações artificiais, divididas em três experimentos e parcelas com 10m2. As avaliações foram realizadas em duas localidades, em Araçatuba - SP e em São Manuel - SP, na Fazenda Experimental São Manuel, da Faculdade de Ciências Agronômicas – UNESP/Botucatu. Foi avaliado o teor de óleo obtido por meio do método químico Soxhlet. Para cada localidade foram realizadas análises estatísticas segundo o delineamento de blocos ao acaso e também uma análise conjunta para os dois locais. Foram determinados os parâmetros genéticos, variância genética e coeficiente de herdabilidade. Os quadrados médios da interação de progênies por locais avaliadas na análise conjunta foram significativos a 5% de probabilidade pelo teste F em todos os experimentos, o que define a existência de comportamento diferencial de progênies em relação aos locais quanto ao teor de óleo. Os quadrados médios da análise de variância entre progênies dentro de locais apresentaram significância a 5% de probabilidade pelo teste F em todos os experimentos de Araçatuba, mostrando a existência de diferenças genéticas entre progênies, já nos experimentos de São Manuel os quadrados médios não foram significativos indicando assim ausência ou baixa variabilidade genética para teor de óleo. A média de teor de óleo, em São Manuel foi 43,22%, variando de 34,87% a 49,24%. Em Araçatuba, a média foi 43,59%, variando de 30,24% a 53,60%. A variância genética e o coeficiente de herdabilidade foram, respectivamente 0.32 e 0,10 para São Manuel e 4,87 e 0,44 para Araçatuba. Estes valores mostram a possibilidade de sucesso na seleção para teor de óleo nas condições de Araçatuba. / The purpose of the research was to evaluate the genetic variability for oil content among lines of castor bean, cv. Guarani. Using artificial self- fertilizations, 135 lines were obtained from individual plants and tested in two locations in the state of São Paulo : Araçatuba and São Manuel, utilizing randomized block design with three replications and plots with 10m2. Oil content was determined by the Soxhlet chemical method. Individual and joint analysis of variance were made to estimate genetic parameters. The mean squares of the line x location interaction were significant by the F test with 5% of probability, that demonstrated the existence of differential behavior of lines due locations for oil content. The mean squares of the variance analysis among lines were significant by the F test with 5% of probability in Araçatuba, showing the existence of genetic differences among lines. However, in São Manuel, the mean squares were not significant, showing absence or low genetic variability for oil content. Average of line oil content, in São Manuel was 43.22% (from 34.87% to 49.24%). In Araçatuba the oil content mean was 43.59% (from 30.24% to 53.6%). Genetic variance and heritability coefficients were respectively 0.32 and 0.10 for São Manuel and 4.87 and 0.44 for Araçatuba. Those values show the possibility to improve the oil content by selection in Araçatuba conditions.
5

Genetic variation in somatic embryogenesis of Rosa Hybrida L.

Burrell, Anna Mildred 30 September 2004 (has links)
An in vitro technique was adapted for screening the ability of Rosa hybrida L. genotypes to form embryogenic callus to elucidate the inheritance of this ability. Filament and leaf petiole explants of modern rose cultivars 'Tournament of Roses' and 'Baby Love' were cultured on somatic embryogenesis induction media and evaluated for the ability to produce embryogenic callus. Cultures of 'Tournament of Roses' produced somatic embryos at a much higher frequency versus 'Baby Love' that produced no embryos. Subsequently, filament explants of eleven 'Tournament of Roses' x 'Baby Love' progeny genotypes were cultured on somatic embryogenesis induction media and evaluated for the ability to undergo somatic embryogenesis. The progeny genotypes produced somatic embryos at varied frequencies. The results obtained indicated that the ability to undergo embryogenesis in Rosa hybrida L. is heritable in an additive fashion with the involvement of more than one gene.
6

Development Of High Throughput Epigenomic Profiling Technologies And Their Application To Twin Based DNA Methylation Studies

Kaminsky, Zachary 24 September 2009 (has links)
Epigenetic studies hold the promise of addressing some of the fundamental questions of human biology including development, cell differentiation, and the aetiological mechanisms of complex disease. Over the last years, several new large scale high throughput technologies have been developed to allow genome wide profiling of epigenetic signals such as DNA methylation and histone modifications. Two of such technologies were developed in our laboratory enabling a genome wide microarray based profiling of DNA methylation signatures and a high throughput method for the site specific interrogation of the density of methylated cytosine. Using these techniques, we identified a DNA methylation difference in the 3’UTR of the DLX1 gene with potentially functional implications to discordance in risk taking behavior in a single pair of MZ twins. We modeled a power analysis on the effect size of the detected difference and determined that approximately 6~25 discordant twin pairs will be adequate to yield 80% power across the entire 12 K CpG island microarray platform using our epigenomic microarray profiling technique. We performed a DNA methylome analysis of MZ twins in white blood cells (WBC), buccal epithelial cells, and gut (rectum) biopsies (N=57 pairs in total) using 12K CpG island microarrays providing the basis for the first annotation of epigenetic metastability of ~6,000 unique genomic regions in MZ twins. We performed a classical twin study on DNA methylation differences in WBC and buccal epithelial cells from 39 pairs of MZ twins to 40 pairs of DZ twins. DZ co-twins exhibited significantly higher epigenetic difference compared to the MZ co-twins in buccal cells (p=1.2x10-294). While such higher epigenetic discordance in DZ twins can result from DNA sequence differences, our in silico SNP analyses and comparison of methylomes in inbred vs. outbred mice favour the hypothesis that this is due to epigenomic differences in the zygotes. This study suggests that molecular mechanisms of heritability may not be limited to DNA sequence differences.
7

Development Of High Throughput Epigenomic Profiling Technologies And Their Application To Twin Based DNA Methylation Studies

Kaminsky, Zachary 24 September 2009 (has links)
Epigenetic studies hold the promise of addressing some of the fundamental questions of human biology including development, cell differentiation, and the aetiological mechanisms of complex disease. Over the last years, several new large scale high throughput technologies have been developed to allow genome wide profiling of epigenetic signals such as DNA methylation and histone modifications. Two of such technologies were developed in our laboratory enabling a genome wide microarray based profiling of DNA methylation signatures and a high throughput method for the site specific interrogation of the density of methylated cytosine. Using these techniques, we identified a DNA methylation difference in the 3’UTR of the DLX1 gene with potentially functional implications to discordance in risk taking behavior in a single pair of MZ twins. We modeled a power analysis on the effect size of the detected difference and determined that approximately 6~25 discordant twin pairs will be adequate to yield 80% power across the entire 12 K CpG island microarray platform using our epigenomic microarray profiling technique. We performed a DNA methylome analysis of MZ twins in white blood cells (WBC), buccal epithelial cells, and gut (rectum) biopsies (N=57 pairs in total) using 12K CpG island microarrays providing the basis for the first annotation of epigenetic metastability of ~6,000 unique genomic regions in MZ twins. We performed a classical twin study on DNA methylation differences in WBC and buccal epithelial cells from 39 pairs of MZ twins to 40 pairs of DZ twins. DZ co-twins exhibited significantly higher epigenetic difference compared to the MZ co-twins in buccal cells (p=1.2x10-294). While such higher epigenetic discordance in DZ twins can result from DNA sequence differences, our in silico SNP analyses and comparison of methylomes in inbred vs. outbred mice favour the hypothesis that this is due to epigenomic differences in the zygotes. This study suggests that molecular mechanisms of heritability may not be limited to DNA sequence differences.
8

Genetic variation in somatic embryogenesis of Rosa Hybrida L.

Burrell, Anna Mildred 30 September 2004 (has links)
An in vitro technique was adapted for screening the ability of Rosa hybrida L. genotypes to form embryogenic callus to elucidate the inheritance of this ability. Filament and leaf petiole explants of modern rose cultivars 'Tournament of Roses' and 'Baby Love' were cultured on somatic embryogenesis induction media and evaluated for the ability to produce embryogenic callus. Cultures of 'Tournament of Roses' produced somatic embryos at a much higher frequency versus 'Baby Love' that produced no embryos. Subsequently, filament explants of eleven 'Tournament of Roses' x 'Baby Love' progeny genotypes were cultured on somatic embryogenesis induction media and evaluated for the ability to undergo somatic embryogenesis. The progeny genotypes produced somatic embryos at varied frequencies. The results obtained indicated that the ability to undergo embryogenesis in Rosa hybrida L. is heritable in an additive fashion with the involvement of more than one gene.
9

Variabilidade genética para o teor de óleo entre progênies autofecundadas de mamona (Ricinus cummunis L.) da cultivar guarani /

Myczkowski, Mirina Luiza, 1978- January 2003 (has links)
Orientador: Maurício Dutra Zanotto / Resumo: O presente trabalho teve como objetivo avaliar a variabilidade genética para teor de óleo entre progênies autofecundadas da cultivar de mamona Guarani. O material utilizado foi constituído de 135 progênies obtidas de plantas individuais, por meio de autofecundações artificiais, divididas em três experimentos e parcelas com 10m2. As avaliações foram realizadas em duas localidades, em Araçatuba - SP e em São Manuel - SP, na Fazenda Experimental São Manuel, da Faculdade de Ciências Agronômicas - UNESP/Botucatu. Foi avaliado o teor de óleo obtido por meio do método químico Soxhlet. Para cada localidade foram realizadas análises estatísticas segundo o delineamento de blocos ao acaso e também uma análise conjunta para os dois locais. Foram determinados os parâmetros genéticos, variância genética e coeficiente de herdabilidade. Os quadrados médios da interação de progênies por locais avaliadas na análise conjunta foram significativos a 5% de probabilidade pelo teste F em todos os experimentos, o que define a existência de comportamento diferencial de progênies em relação aos locais quanto ao teor de óleo. Os quadrados médios da análise de variância entre progênies dentro de locais apresentaram significância a 5% de probabilidade pelo teste F em todos os experimentos de Araçatuba, mostrando a existência de diferenças genéticas entre progênies, já nos experimentos de São Manuel os quadrados médios não foram significativos indicando assim ausência ou baixa variabilidade genética para teor de óleo. A média de teor de óleo, em São Manuel foi 43,22%, variando de 34,87% a 49,24%. Em Araçatuba, a média foi 43,59%, variando de 30,24% a 53,60%. A variância genética e o coeficiente de herdabilidade foram, respectivamente 0.32 e 0,10 para São Manuel e 4,87 e 0,44 para Araçatuba. Estes valores mostram a possibilidade de sucesso na seleção para teor de óleo nas condições de Araçatuba. / Abstract: The purpose of the research was to evaluate the genetic variability for oil content among lines of castor bean, cv. Guarani. Using artificial self- fertilizations, 135 lines were obtained from individual plants and tested in two locations in the state of São Paulo : Araçatuba and São Manuel, utilizing randomized block design with three replications and plots with 10m2. Oil content was determined by the Soxhlet chemical method. Individual and joint analysis of variance were made to estimate genetic parameters. The mean squares of the line x location interaction were significant by the F test with 5% of probability, that demonstrated the existence of differential behavior of lines due locations for oil content. The mean squares of the variance analysis among lines were significant by the F test with 5% of probability in Araçatuba, showing the existence of genetic differences among lines. However, in São Manuel, the mean squares were not significant, showing absence or low genetic variability for oil content. Average of line oil content, in São Manuel was 43.22% (from 34.87% to 49.24%). In Araçatuba the oil content mean was 43.59% (from 30.24% to 53.6%). Genetic variance and heritability coefficients were respectively 0.32 and 0.10 for São Manuel and 4.87 and 0.44 for Araçatuba. Those values show the possibility to improve the oil content by selection in Araçatuba conditions. / Mestre
10

Genetics of resistance to Haemonchus contortus infections in sheep

Vanimisetti, Hima Bindu 04 April 2003 (has links)
Genetic control of resistance to H. contortus was assessed in 198 ewes and 386 lambs of 50% Dorset, 25% Rambouillet and 25% Finnsheep breeding in fall and spring over 2 yr. After deworming, lambs that were approximately 120 d old and ewes that had weaned their lambs at 60 d and dried off were individually dosed with approximately 10,000 infective larvae. After infection, body weight (BW), fecal egg counts (FEC) and packed cell volume (PCV) were measured weekly for 7 wk in lambs and fortnightly for eleven wk in ewes. Summary traits were defined as initial PCV, mean BW (MBW) across all times, and means for FEC, log-transformed FEC (MLFEC), and PCV (MPCV) at wk 3 to 7 post-infection for lambs and wk 3 to 11 post-infection for ewes. No consistent seasonal variation in FEC was observed. Younger ewes were more susceptible to infection than older ewes. Sex differences in FEC were not observed in lambs. Heritabilities for summary traits were estimated from a REML analysis that included fixed effects of year and season plus effects of either sex (for lambs) or age category (for ewes). Heritability estimates for MBW, MPCV, and MLFEC were 0.74, 0.57, and 0.27 respectively (all P < 0.01), in lambs, and 0.24 (P < 0.1), 0.25 (P < 0.05) and 0.55 (P < 0.01), respectively, in ewes. Across-year repeatability estimates in ewes for MBW, MPCV, and MLFEC were 0.83, 0.54 and 0.56, respectively (all P < 0.01). Resistance was antagonistically associated with estimated breeding values for growth in ewes but not in lambs. Fertility and prolificacy in ewes were not related to resistance. Breed differences in resistance to H. contortus were also evaluated in 4 to 6-mo-old crossbred Dorset and Dorper, straightbred Katahdin, and Barbados Blackbelly x St. Croix lambs. Dorpers were not more resistant than Dorsets but appeared to cope better, with higher PCV and similar BW during infection compared to Dorsets. Katahdin and Barbados Blackbelly x St. Croix lambs were more resistant with lower FEC. / Master of Science

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