Dissertations / Theses on the topic 'Quantitative traits'
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Raska, Paola. "Co-morbidities as quantitative traits." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1275586082.
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Polineni, Pavana. "Developing a web accessible integrated database and visualization tool for bovine quantitative trait loci." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2449.
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A quantitative trait locus (QTL) is the location of a gene that affects a trait that is measured on a quantitative (linear) scale. Many important agricultural traits such as weight gain, milk fat content and intramuscular fat in cattle are quantitative traits. There is a need to integrate genomic sequence data with QTL data and to develop an analytical tool to visualize the data. Without integration, application of this data to agricultural enterprise productivity will be slow and inefficient. My thesis presents a web-accessible tool called the Bovine QTL Viewer developed to solve this problem. It consists of an integrated database of bovine QTL and the QTL viewer to view the QTL and their relative chromosomal position. This tool generates dynamic and interactive images and supports research in the field of genomics. For this tool, the data is modeled and the QTL viewer is developed based on the requirements and feedback of experts in the field of bovine genomics.
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Somorjai, Ildikó M. L. "Quantitative trait loci for fitness traits in Arctic charr, conservation in rainbow trout and correlations among traits." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61949.pdf.
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Podisi, Baitsi Kingsley. "Quantitative trait loci mapping of sexual maturity traits applied to chicken breeding." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5561.
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Many phenotypes are controlled by factors which include the genes, the environment, interactions between genes and interaction between the genotypes and the environment. Great strides have been made to understand how these various factors affect traits of agricultural, medical and environmental importance. The chicken is regarded as a model organism whose study would not only assist efforts towards increased agricultural productivity but also provide insight into the genetic determination of traits with potential application in understanding human health and disease. Detection of genomic regions or loci responsible for controlling quantitative traits (QTL) in poultry has focussed mainly on growth and production traits with limited information on reproductive traits. Most of the reported results have used additive-dominance models which are easy to implement because they ignore epistatic gene action despite indications that it may be important for traits with low heritability and high heterosis. The thesis presents results on the detection of loci and genetic mechanisms involved in sexual maturity traits through modelling both additive-dominance gene actions and epistasis. The study was conducted on an F2 broiler x White Leghorn layer cross for QTL detection for age, weight, abdominal fat, ovary weight, oviduct weight, comb weight, number of ovarian yellow follicles, a score for the persistence of the right oviduct and bone density. In addition, body weight QTL at 3, 6, 12, 24, 48 and 72 weeks of age, QTL for growth rate between the successive ages and QTL for the parameters of the growth curve were also detected. Most of the QTL for traits at sexual maturity acted additively. A few of the QTL explained a modest proportion of the phenotypic variation with most of the QTL explaining a small component of the cumulative proportion of the variation explained by the QTL. Body weight QTL were critical in determining the attainment of puberty. The broiler allele had positive effects on weight at first egg and negative effects on age at first egg. Most QTL affecting weight at first egg overlapped with QTL for age at first egg and for early growth rate (6-9 weeks) suggesting that growth rate QTL are intimately related to the onset of puberty. Specific QTL for early and adult growth were detected but most QTL had varying influence on growth throughout life. Chromosome 4 harboured most of QTL for the assessed traits which explained the highest proportion of the phenotypic variation in the traits confirming its critical role in influencing traits of economic importance. There was no evidence for epistasis for almost all the studied traits. Evidence for role of epistasis was significant for ovary weight and suggestive for both growth rate and abdominal fat.
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Lu, Yue. "Genetic mapping of quantitative trait loci for slow-rusting traits in wheat." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32179.
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Doctor of PhilosophyDepartment of Agronomy
Guihua Bai
Allan K. Fritz
Wheat leaf rust, caused by Puccinia triticina, is an important fungal disease worldwide. Growing resistant cultivars is an effective practice to reduce the losses caused by the disease, and using slow-rusting resistance genes can improve the durability of rust resistance in the cultivars. CI13227 is a winter wheat line that shows a high level of slow-rusting resistance to leaf rust and has been studied extensively. In this research, two recombinant inbreed line (RIL) populations derived from CI13227 x Suwon (104 RILs) and CI13227 x Everest (184 RILs) and one doubled haploid (DH) population derived from CI13227 x Lakin with 181 lines were used to identify quantitative trait loci (QTLs) for slow leaf rusting resistance. Each population and its parents were evaluated for slow-rusting traits in two greenhouse experiments. A selected set of 384 simple sequence repeat markers (SSRs), single nucleotide polymorphism markers (SNPs) derived from genotyping-by-sequencing (GBS-SNPs) or 90K-SNP chip (90K-SNPs) were analyzed in the three populations. Six QTLs for slow-rusting resistance, QLr.hwwgru-2DS, QLr.hwwgru-7BL, QLr.hwwgru-7AL, QLr.hwwgru-3B_1, QLr.hwwgru-3B_2, and QLr.hwwgru-1D were detected in the three populations with three stable QTLs, QLr.hwwgru-2DS, QLr.hwwgru-7BL and QLr.hwwgru-7AL. These were detected and validated by Kompetitive Allele-Specific PCR (KASP) markers converted from GBS-SNPs and 90K-SNPs in at least two populations. Another three QTLs were detected only in a single population, and either showed a minor effect or came from the susceptible parents. The KASP markers tightly linked to QLr.hwwgru-2DS (IWB34642, IWB8545 and GBS_snpj2228), QLr.hwwgru-7BL (GBS_snp1637 and IWB24039) and QLr.hwwgru-7AL (IWB73053 and IWB42182) are ready to be used in marker-assisted selection (MAS) to transfer these QTLs into wheat varieties to improve slow-rusting resistance in wheat.
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Clevinger, Elizabeth. "Mapping Quantitative Trait Loci for Soybean Quality Traits from Two Different Sources." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33468.
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Soybeans are economically and agriculturally the most important legume in the world, providing protein and oil to the food and animal feed industries and base ingredients for hundreds of chemical products. Their value could be enhanced, however, if the oil and protein content remained high and the oligosaccharide and phytate contents were lowered to make soybeans more acceptable for human and animal consumption.
A soybean population of 55 families segregating for genes controlling quality traits was chosen for this study. Both parental lines have high sucrose and low stachyose. The former contains a high level of phytate while the latter is low phytate. The objective of this experiment was to determine whether or not both parents had the same gene(s) for low stachyose. An additional objective was to determine quantitative trait loci (QTL) controlling quality traits: sucrose, stachyose and phytate. An acetonitrile precipitation method and a modified colorimetric method were used to determine amounts of sugars and phytate, respectively. The phenotypic data for stachyose was analyzed and it was determined that two recessive genes control low stachyose content in this population. A map was constructed using 141 SSR markers and 15 molecular linkage groups (MLGs) were identified. After analyzing trait and marker data in QTL Cartographer, potential QTL were found on MLGs: B1, C2, D1b, F, M and N. Sucrose and stachyose QTL were identified on B1, C2, M and N. Phytate QTL were observed on B1, D1b, F and N. The markers identified for quality traits in this population may be useful in marker-assisted selection and the germplasm should be useful for the development of a cultivar.Master of Science
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Randall, Joshua Charles. "Large-scale genetic analysis of quantitative traits." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:addfb69d-602c-43e3-ab18-6e6d3b269076.
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Recent advances in genotyping technology coupled with an improved understanding of the architecture of linkage disequilibrium across the human genome have resulted in genome-wide association studies (GWAS) becoming a useful and widely applied tool for discovering common genetic variants associated with both quantitative traits and disease risk. After each GWAS was completed, it left behind a set of genotypes and phenotypes, often including anthropometric measures used as covariates. Genetic associations with anthropometric measures are not well characterized, perhaps due to lack of power to detect them in the sample sizes of individual studies. To improve power to detect variants associated with complex phenotypes such as anthropometric traits, data from multiple GWAS can be combined. This thesis describes the methods and results of several such analyses performed as part of the Genome-wide Investigation of ANThropemtric measures (GIANT) consortium, and compares various different methods that can be used to perform combined analyses of GWAS. In particular, the comparisons focus on comparing differences between meta-analysis methods, in which only summary statistics that result from within-study association testing are shared between studies, and mega-analysis methods in which individual-level genotype and phenotype data is analysed together. Finally, a brief discussion of technological means that have the potential to help overcome some of the challenges associated with performing mega-analyses is offered in order to suggest future work that could be undertaken in this area.
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Shimomura, Koichiro. "Quantitative trait locus analysis of agronomic traits in weedy cucumber lines for breeding." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263362.
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Scherff, Aline D. "Adolescent autistic traits and internalising traits : quantitative genetic investigations of co-occurrence patterns." Thesis, Birkbeck (University of London), 2014. http://bbktheses.da.ulcc.ac.uk/78/.
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Autism spectrum disorders (ASD) are characterised by social-communication difficulties and non-social symptoms such as restricted and repetitive behaviours and interests. ASD characteristics can be investigated at the subclinical trait level within the general population, and these quantitative autistic traits have been shown to have a smooth distribution. Adolescence is an important developmental stage, particularly for the emergence of internalising problems. However, few studies to date have investigated the causes of co-occurring autistic traits and internalising traits during adolescence. The aim of this thesis is to explore the aetiological causes of this trait association between the ages of 12 to 16 years using a quantitative genetic approach. This thesis employs a classic twin design and the sample came from the Twins Early Development Study (TEDS). The causes of the association between autistic and internalising traits in early adolescence are the first focus of this thesis. The analyses in Chapter 4 explore this aetiological association at ages 12-14 years, revealing a moderate phenotypic trait association and at the aetiological level moderate genetic overlap, substantial shared environmental and modest nonshared environmental overlap. Teasing apart these associations further, Chapter 5 identifies specific autistic-like behaviours by means of factor analysis. Relating these factor-derived autistic trait subdomains to the internalising trait measure demonstrated distinguishable patterns of phenotypic and aetiological associations. A factor named autistic-like ‘Social Unease’ showed the most phenotypic and genetic overlap with internalising traits. Secondly, this thesis investigates in Chapter 6 the role of childhood nonshared environment on internalising and autistic traits in early adolescence using the monozygotic twin differences design. Analyses showed that birth weight, childhood hyperactivity and peer problems played a role, via the nonshared environment, in influencing individual differences in internalising and autistic traits in early adolescence. Finally, Chapter 7 presents findings on later adolescence, at age 16 years, exploring the association of autistic traits with anxiety traits and depression traits separately and drawing on both parent and self ratings. The implications of these findings, their limitations and their contribution to the current literature are considered in the Discussion (Chapter 8).
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Loredo-Osti, J. Concepción. "Analysis of quantitative traits, segregation and conditional linkage." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0015/NQ49278.pdf.
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Keith, Deborah J. "Genetic analysis of quantitative traits in Brassica napus." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296926.
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Benyamin, Beben. "Genetic analyses of quantitative traits in human twins." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/10786.
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The aim of this thesis is to understand the genetic basis of the variation of human quantitative traits using data from twins and (to some extent) their families. Traits investigated include behavioural traits (intelligence), clinical traits (the metabolic syndrome) and anthropometric measures (height). The importance of human twins for understanding genetic variation in human quantitative traits is reviewed. The use of a novel finite mixture distribution model to partition phenotypic co(variance) of a trait into underlying genetic and environmental factors from twins of unknown zygosity is presented. The Scottish Mental Surveys of 1st June 1932 and 4th June 1947, respectively, administered the same validated verbal reasoning test (the Moray House Test) to almost everyone born in 1921 or 1936 and attending school in Scotland. Information on zygosity was unavailable. A novel application of a finite mixture distribution model estimated a large and consistent heritability of cognitive ability of about ~0/7. This study is the first to estimate genetic and environmental components of cognitive ability in entire school-attending populations and implies that large (national) data collections can provide sufficient information on twin pairs to estimate genetic parameters, even without known zygosity. The precision and bias of the finite mixture distribution model were assessed using computer simulations and application to IQ measures from a large sample of known zygosity twins (i.e. twins from the UK Twins’ Early Development Studies). It is shown that the mixture distribution is unbiased provided that the twins’ trait values are (bivariate) normally distributed and the sample size is large. However, it the bivariate normality assumption is violated, then the mixture distribution provides biased estimates. The extension of the model to multivariate analysis is discussed. The simulations show that multivariate analysis decreases the standard error of the variance component estimates. Another statistical model, a mixed linear model is used to partition the phenotypic (co)variances of traits into genetic and environmental factors from twins of known zygosity (twins from the Danish Twin Registry). Its application to understand underlying genetic and environmental aetiology showed that endophenotypes associated with the metabolic syndrome do not appear to share a substantial common genetic or familial environmental background. Finally, a genome-wide linkage analysis to identify gene/chromosomal regions associated with adult height reveals several chromosomal regions that showed a modest linkage to adult height. This analysis provides further evidence for the polygenic nature of body height.
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Olatoye, Olalere Marcus. "Quantitative genomic analysis of agroclimatic traits in sorghum." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38251.
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Doctor of PhilosophyDepartment of Agronomy
Geoffrey Morris
Climate change has been anticipated to affect agriculture, with most the profound effect in regions where low input agriculture is being practiced. Understanding of how plants evolved in adaptation to diverse climatic conditions in the presence of local stressors (biotic and abiotic) can be beneficial for improved crop adaptation and yield to ensure food security. Great genetic diversity exists for agroclimatic adaptation in sorghum (Sorghum bicolor L. Moench) but much of it has not been characterized. Thus, limiting its utilization in crop improvement. The application of next-generation sequencing has opened the plant genome for analysis to identify patterns of genome-wide nucleotide variations underlying agroclimatic adaptation. To understand the genetic basis of adaptive traits in sorghum, the genetic architecture of sorghum inflorescence traits was characterized in the first study. Phenotypic data were obtained from multi-environment experiments and used to perform joint linkage and genome-wide association mapping. Mapping results identified previously mapped and novel genetic loci underlying inflorescence morphology in sorghum. Inflorescence traits were found to be under the control of a few large and many moderate and minor effect loci. To demonstrate how our understanding of the genetic basis of adaptive traits can facilitate genomic enabled breeding, genomic prediction analysis was performed with results showing high prediction accuracies for inflorescence traits. In the second study, the sorghum-nested association mapping (NAM) population was used to characterize the genetic architecture of leaf erectness, leaf width, and stem diameter. About 2200 recombinant inbred lines were phenotyped in multiple environments. The obtained phenotypic data was used to perform joint linkage mapping using ~93,000 markers. The proportion of phenotypic variation explained by QTL and their allele frequencies were estimated. Common and moderate effects QTL were found to underlie marker-trait associations. Furthermore, identified QTL co-localized with genes involved in both vegetative and inflorescence development. Our results provide insights into the genetic basis of leaf erectness and stem diameter in sorghum. The identified QTL will also facilitate the development of genomic-enable breeding tools for crop improvement and molecular characterization of the underlying genes Finally, in a third study, 607 Nigerian accessions were genotyped and the resulting genomic data [about 190,000 single nucleotide polymorphisms (SNPs)] was used for downstream analysis. Genome-wide scans of selection and genome-wide association studies (GWAS) were performed and alongside estimates of levels of genetic differentiation and genetic diversity. Results showed that phenotypic variation in the diverse germplasm had been shaped by local adaptation across climatic gradient and can provide plant genetic resources for crop improvement.
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Kadarmideen, Haja Najeemudin. "Statistical methods to map quantitative trait loci for binary traits in half-sib populations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ33306.pdf.
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Townson, Paul Donald. "The use of substitution lines to dissect genetically complex traits in Arabidopsis thaliana." Thesis, Oxford Brookes University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289248.
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Mortimore, Sally Ruth. "Chromosomal location of factors controlling quantitative traits in barley." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385459.
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Bigdeli, T. Bernard. "Quantitative Genetic Methods to Dissect Heterogeneity in Complex Traits." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2651.
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Etiological models of complex disease are elusive[46, 33, 9], as are consistently replicable findings for major genetic susceptibility loci[54, 14, 15, 24]. Commonly-cited explanations invoke low-frequency genomic variation[41], allelic heterogeneity at susceptibility loci[33, 30], variable etiological trajectories[18, 17], and epistatic effects between multiple loci; these represent among the most methodologically-challenging issues in molecular genetic studies of complex traits. The response has been con- sistently reactionary—hypotheses regarding the relative contributions of known func- tional elements, or emphasizing a greater role of rare variation[46, 33] have undergone periodic revision, driving increasingly collaborative efforts to ascertain greater numbers of participants and which assay a rapidly-expanding catalogue of human genetic variation. Major deep-sequencing initiatives, such as the 1,000 Genomes Project, are currently identifying human polymorphic sites at frequencies previously unassailable and, not ten years after publication of the first major genome-wide association find- ings, re-sequencing has already begun to displace GWAS as the standard for genetic analysis of complex traits. With studies of complex disease primed for an unprecedented survey of human genetic variation, it is essential that human geneticists address several prominent, problematic aspects of this research. Realizations regarding the boundaries of human traits previously considered to be effectively disparate in presentation[44, 39, 35, 27, 25, 12, 4, 13], as well as profound insight into the extent of human genetic diversity[23, 22] are not without consequence. Whereas the resolution of fine-mapping studies have undergone persistent refinement, recent polygenic findings suggest a less discriminant basis of genetic liability, raising the question of what a given, unitary association finding actually represents. Furthermore, realistic expectations regarding the pattern of findings for a particular genetic factor between or even within populations remain unclear. Of interest herein are methodologies which exploit the finite extent of genomic variability within human populations to distinguish single-point and cumulative group differences in liability to complex traits, the range of allele frequencies for which common association tests are appropriate, and the relevant dimensionality of common genetic variation within ethnically-concordant but differentially ascertained populations. Using high-density SNP genotype data, we consider both hypothesis-driven and agnostic (genome-wide) approaches to association analysis, and address specific issues pertaining to empirical significance and the statistical properties of commonly- applied tests. Lastly, we demonstrate a novel perspective of genome-wide genetic “background” through exhaustive evaluation of fundamental, stochastic genetic processes in a sample of matched affected and unaffected siblings selected from high- density schizophrenia families.
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Ye, Chun. "Statistical methods for the analysis of expression quantitative traits." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3386752.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed February 11, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 156-169).
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Morrill, Benson H. "Quantitative Genetic Analysis of Reproduction Traits in Ball Pythons." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1005.
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Although the captive reproduction of non-avian reptiles has increased steadily since the 1970’s, a dearth of information exists on successful management practices for large captive populations of these species. The data reported here come from a captive population of ball pythons (Python regius) maintained by a commercial breeding company, The Snake Keeper, Inc. (Spanish Fork, UT). Reproductive data are available for 6,480 eggs from 937 ball python clutches. The data presented suggest that proper management practices should include the use of palpation and/or ultrasound to ensure breeding occurs during the proper time of the female reproductive cycle, and that maintenance of proper humidity during the incubation of eggs is vitally important.
Ball python reproduction traits (clutch size, clutch mass, relative clutch mass, egg mass, hatch rate, egg length, egg width, hatchling mass, healthy offspring per clutch, week laid, and days of incubation) were recorded for the clutches laid during this study. For the 937 clutches, the identity of the dam and sire were known for 862 (92%) and 777 (83%) of the clutches, respectively. A multivariate model that included nine of the 11 traits listed above was compiled. Heritability and genetic and phenotypic correlations were calculated from the multivariate analysis. The trait that showed the most promise for use in artificial selection to increase reproduction rates was clutch size due to considerable genetic variation, high heritability, and favorable genetic correlations with other reproduction traits.
Although large datasets have been published for twinning in avian species, relatively few are available for non-avian reptiles. Reported here are 14 sets of twins produced from 6,480 eggs from 937 ball python clutches. The survival rate for twins during the first 3 months of life in our study was 97%. Interestingly, 11 of the sets of twins were identical in sex and phenotype, and additional genetic data suggested the rate of monozygotic twinning within this captive population of ball pythons was higher than that of dizygotic twinning. Further, using microsatellite analysis we were able to generate data that shows three sets of python twins were genetically identical.
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Brasier, Kyle Geoffrey. "Physiological Traits and Quantitative Trait Loci Associated with Nitrogen Use Efficiency in Soft Red Winter Wheat." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89216.
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Development of winter wheat (Triticum aestivum L.) cultivars capable of more efficient uptake and utilization of applied nitrogen (N) has the potential to increase grower profitability and reduce negative environmental consequences associated with N lost from the plant-soil system. The first study sought to evaluate genotypic variation for N use efficiency (NUE) and identify lines consistently expressing high or low NUE under two or more N rates in a total of 51 N-environments. The results indicated that significant genotype by N rate interactions were frequently observed when trials utilized at least three N rates and identified wheat lines with high and stable yield potential that varied in performance under low N conditions. In addition, NUE was associated with above-ground biomass at physiological maturity were found to be both highly heritable across multiple N supplies. In the second study, two bi-parental mapping populations having a common low ('Yorktown') and two high (VA05W-151 and VA09W-52) NUE parents were characterized to dissect the genetics underlying N response. The populations were evaluated in eight N-environments and genotyped using single-nucleotide polymorphism data derived from a genotyping-by-sequencing protocol to identify quantitative trait loci (QTL) associated with high NUE. Six QTL for NUE were identified on chromosomes 1D, 2D, 4A, 6A, 7A, and 7D that were associated with N use efficiency. The QTL on 2D and 4A co-localized with known loci governing photoperiod sensitivity and resistance to Fusarium head blight (caused by the fungal pathogen Fusarium graminearum Schwabe), respectively. Three of the identified QTL (6A, 7A, and 7D) were associated with NUE in previous investigations, while the QTL on 1D was novel. The final experiment employed a small panel of soft red winter wheat lines to study the effects of photoperiod alleles on chromosome 1D (Ppd-D1) on yield-related traits under three or five N rates that were variably split over two growth stages in eight environments. The results validated the effect of a photoperiod sensitive allele (Ppd-D1b) that was associated with increased grain yield across N rates in half of the Virginia testing environments and under low N rates in all Ohio testing sites at the expense of grain N content. Yield advantages conferred by the Ppd-D1b allele were attributable to increased floret fertility and kernel number per spike. The findings from these studies have direct application for winter wheat breeding programs targeting NUE improvements.Doctor of Philosophy
Wheat (Triticum aestivum L.) products account for a significant percentage of the total dietary calories and protein consumed globally. To meet production demands, wheat requires efficient nitrogen (N) management to ensure continued grower profitability and to reduce negative environmental impacts of N lost from agricultural systems. This dissertation sought to evaluate variation among wheat lines for N use efficiency (NUE), assess the performance of wheat lines under multiple N supplies, validate traits that are associated with NUE, investigate the role of photoperiod sensitivity genes on N response, and identify regions of the wheat genome associated with high N use efficiency. These studies were conducted using panels of winter wheat lines grown under two or more N conditions over a combined 32 location-years. Results of Chapter I identified variation in cultivar response to N rates was more frequently observed when a greater number of N rates were used in trials of wheat N response. The first chapter also identified variation among wheat lines for NUE and identified lines that consistently produce high grain yields over N-location-years. In addition, above-ground biomass at physiological maturity was found to be strongly associated with grain yield under all N rates and was highly heritable in both studies. Chapter II utilized a combination of genetic and observable trait data to perform genetic analysis in two bi-parental populations grown in eight Nlocation-years. The study identified reproducible and significant genetic markers associated with NUE for application in wheat breeding programs. Upon analysis of photoperiod sensitive versus insensitive wheat lines in Chapter III, photoperiod sensitive wheat lines had a significant yield advantage under N-limited conditions in Ohio and across N treatments in half of the Virginia testing location-years. This resulted from an increased number of kernels per spike and fertile florets in photoperiod sensitive wheat lines. Results from this dissertation suggest that active breeding and selection for N response may be achieved through the employment of high NUE genes and the continued identification of adapted high NUE wheat parental lines.
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McClure, Matthew Charles Taylor J. "Genome scan in commercial angus cattle for quantitative trait loci influencing growth, carcass, and reproductive traits." Diss., Columbia, Mo. : University of Missouri-Columbia, 2009. http://hdl.handle.net/10355/7006.
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The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on January 6, 2010). Vita. Thesis advisor: Jeremy Taylor. "July 2009" Includes bibliographical references.
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Jayawardena, Mahen. "An e-Science Approach to Genetic Analysis of Quantitative Traits." Doctoral thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-111597.
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Many important traits in plants, animals and humans are quantitative, and most such traits are generally believed to be affected by multiple genetic loci. Standard computational tools for mapping of quantitative traits (i.e. for finding Quantitative Trait Loci, QTL, in the genome) use linear regression models for relating the observed phenotypes to the genetic composition of individuals in an experimental population. Using these tools to simultaneously search for multiple QTL is computationally demanding. The main reason for this is the complex optimization landscape for the multidimensional global optimization problems that must be solved. This thesis describes parallel algorithms, implementations and tools for simultaneous mapping of several QTL. These new computational tools enable genetic analysis exploiting new classes of multidimensional statistical models, potentially resulting in interesting results in genetics. We first describe how the standard, brute-force algorithm for global optimization in QTL analysis is parallelized and implemented on a grid system. Then, we also present a parallelized version of the more elaborate global optimization algorithm DIRECT and show how this can be efficiently deployed and used on grid systems and other loosely-coupled architectures. The parallel DIRECT scheme is further developed to exploit both coarse-grained parallelism in grid systems or clusters as well as fine-grained, tightly-coupled parallelism in multi-core nodes. The results show that excellent speedup and performance can be archived on grid systems and clusters, even when using a tightly-coupled algorithm such as DIRECT. Finally, we provide two distinctly different front-ends for our code. One is a grid portal providing a graphical front-end suitable for novice users and standard forms of QTL analysis. The other is a prototype of an R-based grid-enabled problem solving environment. Both of these front-ends can, after some further refinement, be utilized by geneticists for performing multidimensional genetic analysis of quantitative traits on a regular basis.eSSENCE
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Jayawardena, Mahen. "Parallel algorithms and implementations for genetic analysis of quantitative traits." Licentiate thesis, Uppsala universitet, Avdelningen för teknisk databehandling, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-85815.
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Many important traits in plants, animals and humans are quantitative, and most such traits are generally believed to be regulated by multiple genetic loci. Standard computational tools for analysis of quantitative traits use linear regression models for relating the observed phenotypes to the genetic composition of individuals in a population. However, using these tools to simultaneously search for multiple genetic loci is very computationally demanding. The main reason for this is the complex nature of the optimization landscape for the multidimensional global optimization problems that must be solved. This thesis describes parallel algorithms and implementation techniques for such optimization problems. The new computational tools will eventually enable genetic analysis exploiting new classes of multidimensional statistical models, potentially resulting in interesting results in genetics. We first describe how the algorithm used for global optimization in the standard, serial software is parallelized and implemented on a grid system. Then, we also describe a parallelized version of the more elaborate global optimization algorithm DIRECT and show how this can be deployed on grid systems and other loosely-coupled architectures. The parallel DIRECT scheme is further developed to exploit both coarse-grained parallelism in grid or clusters as well as fine-grained, tightly-coupled parallelism in multi-core nodes. The results show that excellent speedup and performance can be archived on grid systems and clusters, even when using a tightly-coupled algorithms such as DIRECT. Finally, a pilot implementation of a grid portal providing a graphical front-end for our code is implemented. After some further development, this portal can be utilized by geneticists for performing multidimensional genetic analysis of quantitative traits on a regular basis.
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Bettgenhaeuser, Jan. "Deciphering the genetic basis of quantitative traits in Brachypodium distachyon." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/63532/.
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The domestication of plants and animals has been a powerful force in the development of human societies over the past millennia. Domestication of plants is underscored by the selection of agriculturally favourable traits, such as flowering time and disease resistance, which are often inherited in a quantitative manner. Advances in techniques relating to the study of quantitative traits over the past decades enable the dissection of the genetic architecture and molecular basis of these traits. In this thesis, I discuss the natural diversity governing flowering time and intermediate nonhost resistance in the non-domesticated grass Brachypodium distachyon. Three major loci were found to govern flowering time, two of which colocalise with the B. distachyon homologs of major flowering pathway genes identified in crop species. However, the identification of additional loci suggests that greater complexity underlies flowering time in this non-domesticated system. In contrast, a natural stack of three resistance genes protects B. distachyon against colonisation by Puccinia striiformis and highlights a relatively simple genetic architecture for intermediate nonhost resistance. One broad spectrum major effect locus was narrowed down to genes that are commonly associated with isolate-specific host resistance While it has been proposed that nonhost and host resistance are inherently different, the genetic architecture and molecular basis of resistance in this intermediate nonhost system is reminiscent of a host system, which suggests that the genetic architectures of host and nonhost systems are structurally coupled and share conserved components. Studying the genetic basis of these quantitative traits in B. distachyon elucidates the way humans have utilised the natural variation present in grasses to create modern temperate cereals. Additionally, exploring the interaction between B. distachyon and P. striiformis has provided an ideal system to investigate the transfer of resistance genes from wild relatives to agronomically important crops.
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Prashant, R. "Study of quantitative traits governing wheat grain quality molecular approaches." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2011. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2116.
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Awad, Ashraf Fathy Said. "Mapping of Quantitative Trait Loci for Milk Yield Traits on Bovine Chromosome 5 in the Fleckvieh Cattle." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-126921.
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Conde-Martinez, F. Victor. "Quantitative trait loci and bulk segregant analysis to identify drought-related traits in maize (Zea mays L.)." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432430.
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Harilal, Vibin Eranezhath. "Genetics and Quantitative Trait Loci Mapping of Septoria Tritici Blotch Resistance, Agronomic, and Quality Traits in Wheat." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/26478.
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Most breeding programs aim at developing superior germplasm and better cultivars that combine high yield, disease and pest resistance, and end-use quality to satisfy the requirements of the growers as well as industry. A population, consisting of 138 F2-8 recombinant inbred lines (RILs) derived from a cross between ‘Steele-ND’ and ND 735, was evaluated to study the inheritance pattern of the septoria tritici blotch (STB)-resistant genes, agronomic and quality traits. The framework map made of 392 markers, including 28 simple sequence repeat (SSR) markers and 364 DArT markers, spanned a total distance of 1789.3 cM and consisted of 17 linkage groups. The map position of quantitative trait loci (QTL) found in this study coincided with the map position of durable STB resistance genes, Stb1. Thirteen QTL were detected for agronomic and quality traits. More saturation of the current map is needed to explore more QTL for this population.
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Yao, Ping. "Quantitative trait loci mapping and candidate gene analysis for growth and carcass traits on two bovine chromosomes." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4576.
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Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 7, 2009) Includes bibliographical references.
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Abdel-Haleem, Hussein Ahmed. "Genetics and mapping of quantitative trait loci of feed quality-related traits in barley (Hordeum vulgare L.)." Diss., Montana State University, 2005. http://etd.lib.montana.edu/etd/2004/abdel-haleem/Abdel-HaleemH0505.pdf.
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Karunaratne, Vidarshi Kumudu Kumari. "Quantitative traits related to primary open angle glaucoma in the Scottish population isolate of Orkney." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/9708.
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The aetiology and pathogenesis of primary open angle glaucoma (POAG), the second most common cause of irreversible visual loss in the United Kingdom, remains a conundrum for contemporary ophthalmology. Evidence suggests that glaucoma is a complex disorder, where multiple genes interact with each other and with factors in the environment. However, the aetiological heterogeneity of glaucoma coupled with its varied clinical presentation and course has made the study of glaucoma genes problematic. We established the Orcades Eye Study, a cross sectional family based genetic study, to explore the inheritance of primary open angle glaucoma (POAG). As POAG is a disease of late onset and low prevalence, rather than study disease per se we chose to study quantitative traits (QTs) related to POAG, in an isolated population in the northern Scottish archipelago of Orkney. A number of factors in this population, including reduced genetic heterogeneity and more homogenous environmental effects, confer certain advantages over more admixed urban populations in complex disease gene mapping. Preliminary analysis of the procured quantitative trait data (n=256) has demonstrated that the values obtained for the POAG related QTs of intraocular pressure (IOP), central corneal thickness and a number of optic disc parameters including optic cup area, disc area, retinal nerve fiber thickness, vertical cup to disc ratio and peripapillary atrophy are not dissimilar to other published White Caucasian populations. We also found that intraocular pressure shows an increase with age and is influenced by central corneal thickness but found no relationship between IOP and gender or IOP and other ocular biometric variables including optic nerve head parameters and refractive components. Neither central corneal thickness nor optic nerve head parameters had a statistically significant relationship to age, gender or other tested ocular biometric parameters. These findings are clinically important as these factors should be taken into consideration when evaluating intraocular pressure and other ocular biometric traits in the investigation of glaucoma and other ocular diseases in the population of Orkney. Data collection is ongoing, and with time, an increased sample size and a meaningful genetic analysis, the Orcades Eye Study will hopefully identify genes and regions of the genome associated with primary open angle glaucoma susceptibility in the Scottish Population Isolate of Orkney. To our knowledge, the only other population based study which has investigated as large a number of glaucoma related QTs is the Beijing Eye Study.
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Wood, Andrew Robert. "Next generation genome-wide association studies in complex human quantitative traits." Thesis, University of Exeter, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574245.
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Since 2005, genome-wide association (GWA) studies have dominated the field of complex traits. Genetic and environmental factors play a role in causing disease and influencing the variance of a quantitative trait. GWA is a hypothesis-free approach that follows on from candidate gene and linkage studies and has markedly increased the number of loci associated with complex traits. Despite the relative success of GWA studies in identifying several hundreds of phenotypic associations, the genetic component of most complex traits remains largely unaccounted for. The field has now begun to focus its, efforts on the "missing heritability" to enhance the understanding of genetics and the associated biological pathways that underlie the aetiology of complex phenotypes. This thesis presents a series of studies that attempt to address this issue by exploring other sources of variation and statistical models that have not been extensively addressed in GWA studies to date. Chapter 1 is an introduction to genome-wide association studies. In particular it describes the origins of these studies, what we have learnt from them as well as their limitations. Chapter 2 describes a study that shows how multiple signals within a single locus can explain more of the genetic component of a complex trait, using gene expression as a model trait. 2 Chapter 3 describes a study that tests for deviation from additivity (additivity is an assumption of most GWA studies to date) through dominant, recessive and gene-gene interaction analyses using height, body mass index, and waist-hip ratio (adjusted for BMI) as model phenotypes. Chapter 4 describes a study that examines how more signals may be identified by increasing the density of variants through 1000 Genomes based imputation compared to HapMap based imputation. I use 93 phenotypes, all circulating factors, including proteins, ions and vitamins. Chapter 5 describes a study that tests whether more association signals can be discovered through low-coverage whole-genome sequencing. In particular, I compare association testing based on 1000 Genomes based imputation and sequencing. I use gene expression as a model trait. Chapter 6 discusses the research findings from the previous chapters, presents conclusions, and describes future research plans in the field of complex traits for a fuller understanding of the role of genetics. 3
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Semikhodskii, Andrei G. "Mapping quantitative traits for salinity responses in wheat (Triticum aestivum L.)." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302054.
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Koerhuis, Alphonsus Nicolaas Maria. "Quantitative genetic studies on growth and reproductive traits in broiler chickens." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/11003.
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This thesis considers three major quantitative genetic topics characteristic of growth and reproductive traits in broiler breeding, i.e. (1) the estimation of maternal effects in juvenile body weight (JBWT), (2) selection for food conversion into growth defined as a ratio (FCR), and (3) non-normality and curvilinearity of heritability of egg production distributions and the genetic relationships of those reproductive traits with juvenile growth. Restricted maximum likelihood (REML) methods based on the individual animal model were utilised in the estimation of variance components to make optimum use of the data and take account of selection. Estimates of the maternal additive genetic variation were small relative to the direct additive genetic variation of JBWT for two broiler populations investigated. The negative estimates of the direct-maternal genetic correlation (rAM) were unexpected and prompted the investigation of more appropriate and detailed statistical models taking account of direct-maternal environmental covariation, estimated either as the covariance between the environmental maternal and the environmental residual effects or as a maternal phenotypic effect through regression on the mother's phenotype. Whilst the goodness-of-fit of these alternative models was superior, the estimates of rAM were not much affected. The choice of the fixed effect structure was shown to be paramount in the estimation of maternal effects. Thus far, maternal effects were lumped together into a single component. Next, the results were described of an experiment conducted to identify individual pathways related to the egg causing maternal variation in JBWT and to establish their effect on offspring-parental regressions. Antagonistic maternal pathways of egg weight at the start and at the 18th day of incubation were observed. Their effects largely offset each other and hence biased the offspring-dam regression only slightly. A high loss in egg weight during incubation, indicative of poor egg shell quality, was identified as the likely cause for the negative estimates of rAM.
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Heath, Simon Charles. "Inferences on the genetic control of quantitative traits from selection experiments." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/14040.
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The main aim of this thesis is the development of methods for analysing data from selection experiments to make inferences about the genetic control of the selected trait. A series of methods for data analysis are developed and applied to both simulated and experimental datasets under infinitesimal (polygenic) genetic models, discrete locus models and mixed inheritance models (which are a combination of polygenic and discrete locus models). The experimental dataset is from a replicated selection experiment on mice in which an F2 population formed from an inbred cross was divergently selected on body weight for 20 generations. The experimental data are initially analysed assuming the infinitesimal model using a Derivative Free Restricted Maximum Likelihood package (Meyer) to produce estimates of genetic parameters. An extension to the package is then developed to allow the variance components of change continuously over time, in effect regressing the variance components on generation number. This method allows for changes to variance components over and above what would be predicted from the infinitesimal model, thereby detecting deviations from the model. When applied to simulated data the method detects no change in additive genetic variance when a polygenic model with a large number of genes (16384) is simulated, but detects significant decreases in the additive variance, as expected, when a smaller number (32) are used. Analysis of the experimental data indicates that the additive and environment variance components increase over the course of the experiment, significantly so in the Low selected lines. Overall there is an estimated increase in phenotype variance of 56% in the Low lines and 14% in the High lines.
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Linney, Yvonne. "A quantitative genetic analysis of schizotypal personality traits and neuropsychological functioning." Thesis, King's College London (University of London), 2001. http://kclpure.kcl.ac.uk/portal/en/theses/a-quantitative-genetic-analysis-of-schizotypal-personality-traits-and-neuropsychological-functioning(cdce6371-4dd0-401e-873d-75fc5571afc1).html.
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Dholakia, B. B. "Molecular approaches to decipher quantitative traits governing grain quality in wheat." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2001. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2311.
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Santos, Laura Viviana [Verfasser]. "Quantitative genetic analyses for dairy cow behavior traits and traits reflecting human-animal-technic interactions / Laura Viviana Santos." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1161339450/34.
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Santos, Laura [Verfasser]. "Quantitative genetic analyses for dairy cow behavior traits and traits reflecting human-animal-technic interactions / Laura Viviana Santos." Gießen : Universitätsbibliothek, 2018. http://d-nb.info/1161339450/34.
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Smitchger, Jamin A. "Quantitative Trait Loci Associated with Lodging, Stem Strength, Yield, and Other Important Agronomic Traits in Dry Field Peas." Thesis, Montana State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10607937.
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In pea, lodging changes canopy structure, increases disease pressure, reduces yield, and reduces harvest efficiency. In order to discover the quantitative trait loci (QTLs) influencing lodging resistance and other important agronomic traits in pea, a recombinant inbred line (RIL) population was created from a relatively wide cross between the commercial variety Delta and an unnamed pea variety. The RIL population was grown for 6 site-years in Bozeman and Moccasin, MT, USA, and phenotypic data was collected for 22 quantitative morphological traits and seven categorical traits which were thought to be associated with lodging resistance. Genotypic data was derived from genotype by sequencing, microsattelite markers, and cleaved amplified sequence tagged sites.
QTL analysis identified a total of 135 putative QTLs for the 22 traits examined in the study. There were 12 specific regions where 115 QTLs co-located, indicating that as few as 12 genes may be responsible for multiple pleiotropic effects. Ten QTLs were found for lodging resistance. Due to the large amount of phenotypic data collected, the putative mechanism of lodging resistance was determined for each QTL. In nearly every case, lodging resistance was associated with reduced plant height, a change in tendril number, or increased stem strength. This conclusion was supported by mathematical modeling. Branch number, which determines the number of tendrils per plant, was also positively associated with lodging resistance during all site-years, indicating that increasing tendril number also increases lodging resistance.
Yield was controlled by eight QTLs. All QTLs for yield had pleiotropic effects on lodging resistance and yield per plant. Seed size was not correlated with yield, and a model was created which explained why no association between yield and seed size was found.
The pleiotropic effects and utility of the QTLs discovered in this study are discussed. The results of this study further refine the ideotype for pea, and can be used for marker assisted selection in this crop.
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Kunert, Antje [Verfasser]. "Quantitative trait loci for agronomic and quality traits in two advanced backcross populations of winter wheat / Antje Kunert." Aachen : Shaker, 2007. http://d-nb.info/1170528260/34.
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Clarke, Jasper. "Quantitative trait locus mapping of oil yield and oil quality related traits in the biofuel crop Jatropha curcas." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/16007/.
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Jatropha curcas is a perennial shrub from the Euphorbiacea family. It is known for its stress resilience and high seed oil content, however little selective breeding has been carried out to fully domesticate this species. The aim of this project is to identify and map quantitative trait loci (QTL) for seed oil content, seed oil composition (oil quality), and oil yield, in order to identify loci suitable for introgression into an economically viable cultivar. In this study, an F2 population (G51xCV) consisting of 229 plants for linkage analysis, and 145 plants for QTL analysis, was used to identify and position 312 genetic markers and 8 quantitative traits onto a genetic linkage and QTL map. Over 288 short sequence repeat (SSR) markers were mined from genome sequence to complement single nucleotide polymorphism (SNP) markers from genomic and transcribed DNA. 132 of the mined SSRs were physically linked to candidate genes, leading to the mapping of a substantial portion of genes that form the seed oil biosynthetic pathway in Jatropha curcas. Integration of phenotypic datasets collected over 2 independent years, enabled the identification of 15 QTL regulating seed oil content (2QTL), seed oil composition; palmitate, stearate, oleate, linoleate content (10 QTL), seed weight (1 QTL), number of branches (1 QTL) and seed yield (1QTL). Combined PVE for these QTL accounted for between 9.34 % (palmitate content year 2) to 32.26 % (seed oil content Year 2) of observed variation. Analysis of final oil yield per plant, showed that seed yield (number of seeds) was most important for regulating oil yield in this mapping population, however seed oil content and seed weight were also important traits, highlighting that selection of both seed oil and vegetative traits are of utmost importance for optimising oil yield in Jatropha curcas.
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Thumma, Bala Reddy. "QTL analysis of physiological and biochemical traits contributing to drought resistance in stylosanthes /." [St. Lucia, Qld.], 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16386.pdf.
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Klemmer, Daniel [Verfasser], Michael [Gutachter] Lässig, and Thomas [Gutachter] Wiehe. "Quantitative Traits and Phenotypic Interference / Daniel Klemmer ; Gutachter: Michael Lässig, Thomas Wiehe." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1175091596/34.
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Vaez, Torshizi Rasoul. "Quantitative genetic analyses of production and reproduction traits in Australian merino sheep." Thesis, The University of Sydney, 1996. https://hdl.handle.net/2123/27593.
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Restricted Maximum Likelihood (REML) procedures based on a derivative-free algorithm using the Simplex method and fitting an animal model were used to estimate variance and covariance components for several performances of productive traits, namely, body weight measured at birth, weaning, 10 month, 16 month and 22 months of age, greasy fleece average daily gain to 4, 10, 16 and 22 months of age, clean fleece average daily gain to 10, 16, 22 months of age and mean fibre diameter measured at 10, 16 and 22 months of age. For these traits, the importance of maternal effects, either additive genetic or environmental, were investigated. The interrelationship among the performances of each trait were studied, and then were used to determine the efficiencies of indirect selection at early ages compared with later ages for improvement of an animal's lifetime production.
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Veloso, Rogério de Carvalho. "Effects of nutritional plans and genetic groups on quantitative traits of pigs." Universidade Federal de Viçosa, 2016. http://www.locus.ufv.br/handle/123456789/9220.
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A seleção de genótipos para alto desempenho teve como consequência redução do teor gordura e perda na qualidade da carne. Uma alternativa para melhorar a qualidade da carne é o cruzamento de raças locais, como o Piau, com raças melhoradas como Duroc, Pietrain e Large White. Contudo, as diferenças nas taxas de crescimento e de deposição de gordura apresentadas pelos suínos indicam que os grupos genéticos tenham diferentes necessidades nutricionais. A genética e o ambiente são importantes na expressão das características de desempenho e qualidade da carne, principalmente quando há variações nas taxas de deposição de tecido magro e gordo. Essas variações podem causar interferência no perfil de expressão dos genes que atuam nas vias metabólicas ou hormonais das características relacionadas à qualidade da carne. Objetivou-se, com este trabalho, avaliar o efeito do grupo genético paterno (Piau, Base-Duroc e Pietrain) e dos planos nutricionais contendo diferentes níveis de lisina digestível (Baixo, Médio e Alto) sobre as características de desempenho, carcaça e qualidade da carne; o padrão de expressão gênica das isoformas da cadeia pesada da miosina (MyHC) nos músculos Longissimus e Psoas; e a expressão diferencial dos genes relacionados com o metabolismo lipídico (FAS, H-FABP, SCD, PRKAG1, PRKAG3 e HSL) no músculo Longissimus de suínos. Os machos castrados e as fêmeas cruzadas Pietrain e Duroc foram similares nas características de desempenho e carcaça e tiveram os melhores valores em comparação aos suínos cruzados Piau. Com relação à qualidade da carne, a perda por gotejamento foi maior nos machos castrados e fêmeas cruzadas Pietrain em comparação com os suínos cruzados Duroc e Pietrain. O consumo diário de lisina digestível dos animais foi maior no plano nutricional Alto, em relação aos planos nutricionais Médio e Baixo. A maioria das características de desempenho, carcaça e qualidade da carne avaliadas nos machos castrados e fêmeas não foram afetadas pelos planos nutricionais. Os níveis de expressão do H-FABP e SCD foram maiores nos suínos Duroc e Pietrain. Maior expressão do gene PRKAG3 foi observada nos machos castrados cruzados alimentados com o plano nutricional Baixo em comparação com os suínos alimentados com plano nutricional Médio e Alto. Houve maior expressão do gene MyHC IIb no músculo Longissimus dos suínos alimentados com os planos nutricionais contendo maiores níveis de lisina digestível em relação aos suínos cruzados que receberam plano nutricional contendo menores níveis de lisina digestível. Os níveis de expressão do gene MyHC IIb no músculo Longissimus foi maior nos machos castrados cruzados Duroc e Pietrain em comparação aos machos castrados cruzados Piau (P < 0,05). Em geral, os suínos cruzados Duroc e Pietrain tiveram melhor desempenho e rendimento de carcaça em comparação aos cruzados Piau. O atual estudo indica que o genótipo tem forte influencia sobre a deposição do conteúdo de gordura intramuscular, principalmente pela regulação da expressão gênica lipogênica intramuscular. A expressão diferencial das isoformas MyHC nos músculos podem ser os fatores mais importantes que influenciam o conteúdo de gordura intramuscular e a perda por gotejamento em suínos. Estes resultados podem fornecer informações valiosas para o entendimento das diferenças na qualidade da carne de diferentes grupos genéticos de suínos.
Selection of genotypes for high performance led to a fat level reduction and loss of meat quality as consequence. An alternative to improve meat quality is the crossbreeding of non-selected local pig breed, such as Piau, with improved breeds such as Duroc, Pietrain and Large White. However, growth rate and fat deposition differences in pigs indicate that genetic groups have different nutritional needs. Genetic and environment are important in expression of performance and meat quality traits, mainly when variations in deposition of lean and fat tissue rates are observed. These variations may affect genes expression profile that acts in metabolic or hormonal pathways of meat quality related traits. In this work, we aimed to evaluate the effects of paternal genetic group (Piau, Duroc-based and Pietrain) and nutritional plans with different digestible lysine levels (Low, Medium and High) on performance, carcass and meat quality traits; gene expression pattern of myosin heavy chain isoforms (MyHC) in Longissimus and Psoas muscles; and differential expression of lipid metabolism-related genes (FAS, H-FABP, SCD, PRKAG1, PRKAG3 and HSL) in Longissimus muscle of pigs. Pietrain and Duroc crossbred barrows and gilts were similar in performance and carcass traits and had greatest values compared to Piau crossbred pigs. Regarding the meat quality, drip loss was greater in Pietrain crossbred barrows and gilts compared to Duroc and Piau crossbred pigs. Daily digestible lysine intake was greater in High nutritional plan animals in relation to Medium and Low nutritional plans. Most of performance, carcass and meat quality traits evaluated in barrows and gilts were not affected by nutritional plans. Expression levels of H-FABP and SCD were higher in Duroc and Pietrain pigs. Higher expression of PRKAG3 gene in barrows fed with Low nutritional plan compared with pigs fed with Medium and High nutritional plan was observed. There was a higher expression of MyHC IIb gene in Longissimus muscle of crossbred barrows fed with greater digestible lysine levels compared to crossbred barrows that received nutritional plan with lower digestible lysine levels. The mRNA expression levels of MyHC IIb in Longissimus muscle was higher in Duroc and Pietrain crossbred compared to Piau crossbred barrows (P < 0.05). In general, Duroc and Pietrain crossbred pigs had greater performance and carcass rate compared to Piau crossbred pigs. The present study indicated that genotype has a strong effect on intramuscular fat content deposition mainly by up-regulation of intramuscular lipogenic gene expression. The differentially expression of MyHC isoforms in muscles may be the most important factors affecting intramuscular fat content and drip loss in pig. These results may provide valuable information to the understanding of meat quality differences in divergent genetic groups of pigs.
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Nagy, Réka. "Genetic analysis using family-based populations." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28978.
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Most human traits are influenced by a combination of genetic and environmental effects. Heritability expresses the proportion of trait variance that can be explained by genetic factors, and the 1980s heralded the beginning of studies that aimed to pinpoint genetic loci that contribute to trait variation, also known as quantitative trait loci (QTLs). Subsequently, the availability of cheap, high-resolution genotyping chips ushered in the era of genome-wide association studies (GWAS). These genetic studies have discovered many associations between single-nucleotide polymorphisms (SNPs) and complex traits, but these associations do not explain the genetic component of these traits entirely. This is known as the ‘missing heritability’ problem. Within this thesis, 40 medically-relevant human complex traits are studied in order to identify new QTLs. These traits include eye biometric traits, blood biochemical traits and anthropometric traits measured in approximately 28,000 individuals belonging to family-based samples from the general Scottish population (the Generation Scotland study) or from population isolates from Croatian (Korčula, Vis) or Scottish (Shetland, Orkney) islands. These individuals had been genotyped using commercially-available arrays, and unobserved genotypes were imputed using the Haplotype Reference Consortium (HRC) dataset. In parallel to standard GWAS, these traits are analysed using two other statistical genetics approaches: variance component linkage analysis and regional heritability (RH) mapping. Each study is analysed separately, in order to detect study-specific genetic effects that may not generalise across populations. At the same time, because most traits are available in several studies, this also enables meta-analysis, which boosts the power of discovery and can reveal cross-study genetic effects. These methods are a priori complementary to each other, exploiting different aspects of human genetic variation, such as the segregation of variants within families (identity by descent, IBD), or the presence of the same variant throughout the general population (identity by state, IBS). The strengths and weaknesses of these methods are systematically assessed by applying them to real and simulated datasets.
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Li, Jingzhao. "Mapping of new microsatellite markers and molecular identification of quantitative trait locus (QTL) for agronomically important traits in barley." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97412141X.
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Banerjee, Samprit. "Bayesian genome-wide QTL mapping for multiple traits." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/banerjee.pdf.
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Goddard, Katrina Blouke. "Study design issues in the analysis of complex genetic traits /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9565.
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