scholarly journals Statistical model for characterizing epistatic control of triploid endosperm triggered by maternal and offspring QTLs

2005 ◽  
Vol 86 (1) ◽  
pp. 65-75 ◽  
Author(s):  
YUEHUA CUI ◽  
RONGLING WU
Keyword(s):  
Statistical Model ◽  
Genetic Research ◽  
Expectation Maximization Algorithm ◽  
Endosperm Development ◽  
Additive Effect ◽  
Sampling Strategies ◽  
Accuracy And Precision ◽  
Trait Locus ◽  
Hierarchical Statistical Model ◽  
Action Modes

To study the effects of maternal and endosperm quantitative trait locus (QTL) interaction on endosperm development, we derive a two-stage hierarchical statistical model within the maximum-likelihood context, implemented with an expectation-maximization algorithm. A model incorporating both maternal and offspring marker information can improve the accuracy and precision of genetic mapping. Extensive simulations under different sampling strategies, heritability levels and gene action modes were performed to investigate the statistical properties of the model. The QTL location and parameters are better estimated when two QTLs are located at different intervals than when they are located at the same interval. Also, the additive effect of the offspring QTLs is better estimated than the additive effect of the maternal QTLs. The implications of our model for agricultural and evolutionary genetic research are discussed.

scholarly journals Genetic Architecture of a Morphological Shape Difference Between Two Drosophila Species

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 299-310 ◽  
Author(s):  
Zhao-Bang Zeng ◽  
Jianjun Liu ◽  
Lynn F Stam ◽  
Chen-Hung Kao ◽  
John M Mercer ◽  
...  
Keyword(s):  
Interval Mapping ◽  
Additive Effect ◽  
Parameter Estimates ◽  
Effect Estimate ◽  
Interspecific Difference ◽  
Posterior Lobe ◽  
Complete Dominance ◽  
Backcross Populations ◽  
History Of ◽  
Trait Locus

AbstractThe size and shape of the posterior lobe of the male genital arch differs dramatically between Drosophila simulans and D. mauritiana. This difference can be quantified with a morphometric descriptor (PC1) based on elliptical Fourier and principal components analyses. The genetic basis of the interspecific difference in PC1 was investigated by the application of quantitative trait locus (QTL) mapping procedures to segregating backcross populations. The parental difference (35 environmental standard deviations) and the heritability of PC1 in backcross populations (>90%) are both very large. The use of multiple interval mapping gives evidence for 19 different QTL. The greatest additive effect estimate accounts for 11.4% of the parental difference but could represent multiple closely linked QTL. Dominance parameter estimates vary among loci from essentially no dominance to complete dominance, and mauritiana alleles tend to be dominant over simulans alleles. Epistasis appears to be relatively unimportant as a source of variation. All but one of the additive effect estimates have the same sign, which means that one species has nearly all plus alleles and the other nearly all minus alleles. This result is unexpected under many evolutionary scenarios and suggests a history of strong directional selection acting on the posterior lobe.

scholarly journals A hierarchical statistical model for estimating population properties of quantitative genes

BMC Genetics ◽  
2002 ◽  
Vol 3 (1) ◽  
Author(s):  
Samuel S Wu ◽  
Chang-Xing Ma ◽  
Rongling Wu ◽  
George Casella
Keyword(s):  
Statistical Model ◽  
Hierarchical Statistical Model

scholarly journals Molecular studies of identification of genes for osteoporosis: the 2002 update

2003 ◽  
Vol 177 (2) ◽  
pp. 147-196 ◽  
Author(s):  
YZ Liu ◽  
YJ Liu ◽  
RR Recker ◽  
HW Deng
Keyword(s):  
Association Studies ◽  
Molecular Genetic ◽  
Genetic Research ◽  
Large Body ◽  
Current Status ◽  
Vdr Gene ◽  
Genetic Studies ◽  
Retrospective View ◽  
Genetics Of Osteoporosis ◽  
Trait Locus

We aim to give a comprehensive review, updated to 2002, of the most important and representative molecular genetic studies, performed mainly within the past decade, that aimed to identify the gene(s) involved in osteoporosis. Early reviews were largely confined to association studies in humans, but we review here, separately, the results of both association and linkage studies in humans, and quantitative trait locus (QTL) mapping in animal models. The main results of all the studies are tabulated for comparison and ease of reference, and to provide a comprehensive retrospective view of molecular genetics studies of osteoporosis. The most striking findings and the most representative studies are singled out for comment regarding the immediacy of their influence on present understanding of the genetics of osteoporosis and on the current status of genetic research in osteoporosis. This is particularly relevant for studies on the association of the vitamin D receptor (VDR) gene, for which there has been a large body of studies and reviews published. The format adopted by this review should be ideal for accommodating future new advances and studies in a fairly young field that is still developing rapidly.

scholarly journals Mapping Quantitative Trait Loci Using Distorted Markers

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Shizhong Xu ◽  
Zhiqiu Hu
Keyword(s):  
Qtl Mapping ◽  
Segregation Distortion ◽  
Quantitative Trait ◽  
Expectation Maximization Algorithm ◽  
Real Life ◽  
Segregation Ratio ◽  
Joint Analysis ◽  
Mendelian Segregation ◽  
Real Life Data ◽  
Trait Locus

Quantitative trait locus (QTL) mapping is usually performed using markers that follow a Mendelian segregation ratio. We developed a new method of QTL mapping that can use markers with segregation distortion (non-Mendelian markers). An EM (expectation-maximization) algorithm is used to estimate QTL and SDL (segregation distortion loci) parameters. The joint analysis of QTL and SDL is particularly useful for selective genotyping. Application of the joint analysis is demonstrated using a real life data from a wheat QTL mapping experiment.

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