scholarly journals Evidence for a new major gene influencing meat quality in pigs

1990 ◽  
Vol 55 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Pascale Le Roy ◽  
J. Naveau ◽  
J. M. Elsen ◽  
P. Sellier
Keyword(s):  
Major Gene ◽  
Maximum Likelihood Estimates ◽  
Quality Trait ◽  
Likelihood Ratios ◽  
Common Component ◽  
Polygenic Inheritance ◽  
Complete Dominance ◽  
Unfavourable Effect ◽  
The Difference ◽  
Foundation Stock

SummaryThe present investigation primarily deals with the inheritance of a pigmeat quality trait, the Napole technological yield (RTN), a measure of cooked weight to fresh weight. This trait as well as lean percentage at 100 kg liveweight and fattening length from 20 to 100 kg liveweight were recorded on 3459 offspring from 67 sires and 433 dams, and 3052 offspring from 64 sires and 405 dams in Penshire (P66) and Pen Ar Lan (P77) composite lines respectively. The hypothesis of a major 2-allele locus contributing to RTN was tested by use of a segregation analysis method. Highly significant likelihood ratios (mixed vs. polygenic transmission models) lead us to conclude that a major gene RN− exerting an unfavourable effect on RTN is segregating in both lines. Maximum likelihood estimates of the parameters under the hypothesis of mixed (monogenic + polygenic) inheritance show that the difference between the means of the 2 homozygotes amounts to about 3 phenotypic standard deviations of the trait, whereas the complete dominance of RN− cannot be rejected. The frequency of RN− is about 0·6 in both lines. These results are discussed in connection with the previously reported ‘Hampshire effect’ on pigmeat quality, as the Hampshire breed is a common component of the foundation stock of the 2 composite lines under study.

scholarly journals Combining superior alleles from two homozygous populations in a cross-fertilizing species

1980 ◽  
Vol 36 (3) ◽  
pp. 277-287 ◽  
Author(s):  
Y. T. Ho ◽  
R. E. Comstock
Keyword(s):  
Real Life ◽  
The Other ◽  
Relative Fitness ◽  
Source Population ◽  
Effective Population ◽  
Complete Dominance ◽  
Selection Limit ◽  
The Difference ◽  
Source Populations ◽  
Foundation Stock

SUMMARYThe issue of incorporating the good alleles from two homozygous populations of a cross-fertilizing species into a single improved population was investigated assuming independent assortment, no epistasis, and either complete dominance (of the favourable or the unfavourable alleles) or additive genes. The selection limit in the foundation stock is a function of the effective population size (N), the proportion (x) contributed by the better source population (P1), the difference in relative fitness between single locus homozygotes and the proportion of loci (that will segregate in the foundation stock) fixed favourably in P1. In real life the last two of these are never known. We therefore focused on the response limits given x = 0·5, 0·75, 0·875 or the optimum value of x (which is a function of the other three parameters). Our general finding was that in situations where N is large enough so that a major portion of the potential can be achieved, the F2 population should be used as the foundation stock when the two source populations do not differ greatly in performance; but when one population performs considerably better than the other, the first backcross (but not second backcross) would be the choice.

Curved Exponential Models in Econometrics

1997 ◽  
Vol 13 (6) ◽  
pp. 771-790 ◽  
Author(s):  
Kees Jan van Garderen
Keyword(s):  
Structural Equation ◽  
Equation Model ◽  
Econometric Models ◽  
Demand Systems ◽  
Likelihood Ratios ◽  
Sufficient Statistics ◽  
Sufficient Statistic ◽  
Exponential Models ◽  
Minimal Sufficient Statistic ◽  
The Difference

Curved exponential models have the property that the dimension of the minimal sufficient statistic is larger than the number of parameters in the model. Many econometric models share this feature. The first part of the paper shows that, in fact, econometric models with this property are necessarily curved exponential. A method for constructing an explicit set of minimal sufficient statistics, based on partial scores and likelihood ratios, is given. The difference in dimension between parameterand statistic and the curvature of these models have important consequences for inference. It is not the purpose of this paper to contribute significantly to the theory of curved exponential models, other than to show that the theory applies to many econometric models and to highlight some multivariate aspects. Using the methods developed in the first part, we show that demand systems, the single structural equation model, the seemingly unrelated regressions, and autoregressive models are all curved exponential models.

Processing gravity gradient data

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. I33-I47 ◽  
Author(s):  
Gary Barnes ◽  
John Lumley
Keyword(s):  
Measurement Data ◽  
Gravity Gradient ◽  
Common Source ◽  
Common Component ◽  
Equivalent Source ◽  
Commercial Practice ◽  
Useful Signal ◽  
Geologic Model ◽  
The Difference ◽  
Using Data

As the demand for high-resolution gravity gradient data increases and surveys are undertaken over larger areas, new challenges for data processing have emerged. In the case of full-tensor gradiometry, the processor is faced with multiple derivative measurements of the gravity field with useful signal content down to a few hundred meters’ wavelength. Ideally, all measurement data should be processed together in a joint scheme to exploit the fact that all components derive from a common source. We have investigated two methods used in commercial practice to process airborne full-tensor gravity gradient data; the methods result in enhanced, noise-reduced estimates of the tensor. The first is based around Fourier operators that perform integration and differentiation in the spatial frequency domain. By transforming the tensor measurements to a common component, the data can be combined in a way that reduces noise. The second method is based on the equivalent-source technique, where all measurements are inverted into a single density distribution. This technique incorporates a model that accommodates low-order drift in the measurements, thereby making the inversion less susceptible to correlated time-domain noise. A leveling stage is therefore not required in processing. In our work, using data generated from a geologic model along with noise and survey patterns taken from a real survey, we have analyzed the difference between the processed data and the known signal to show that, when considering the Gzz component, the modified equivalent-source processing method can reduce the noise level by a factor of 2.4. The technique has proven useful for processing data from airborne gradiometer surveys over mountainous terrain where the flight lines tend to be flown at vastly differing heights.

The Genetics of Bipolar Disorder

1993 ◽  
Vol 27 (4) ◽  
pp. 560-580 ◽  
Author(s):  
Philip Mitchell ◽  
Andrew Mackinnon ◽  
Brent Waters
Keyword(s):  
Bipolar Disorder ◽  
Psychiatric Disorders ◽  
Dna Markers ◽  
Major Gene ◽  
Adoption Studies ◽  
Polygenic Inheritance ◽  
Current State ◽  
Number Of Genes ◽  
Mode Of Transmission ◽  
Molecular Biological Techniques

Growing interest in the application of molecular biological techniques to psychiatric disorders has reinvigorated interest in the genetics of the psychoses. It is therefore timely to review the current state of knowledge of the genetics of bipolar disorder. Family, twin and adoption studies are all consistent in confirming the strongly heritable nature of this condition. As segregation analyses have been unable to determine the mode of transmission of bipolar disorder, ongoing linkage analyses using DNA markers will be crucial in determining whether this condition is due to a single major gene, a small number of genes, or multifactorial polygenic inheritance.

REACTION OF WHEAT TO COMMON ROOT ROT: LINKAGE OF A MAJOR GENE, Crr, WITH THE CENTROMERE OF CHROMOSOME 5B

1982 ◽  
Vol 24 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Ruby I. Larson ◽  
T. G. Atkinson
Keyword(s):  
Root Rot ◽  
Recombination Frequency ◽  
Major Gene ◽  
Recessive Gene ◽  
Triticum Aestivum L ◽  
Common Root ◽  
Telocentric Chromosome ◽  
Chromosome 5B ◽  
The Difference ◽  
Moderate Resistance

'Cadet' (C), a cultivar of Triticum aestivum L., carries the major recessive gene, Crr, for moderate resistance to common root incited by Cochliobolus sativus (Ito and Kurib.) Drechs. ex Dastur, on the long arm of chromosome 5B. The highly susceptible cultivar, 'Rescue' (R), has the dominant, epistatic allele, crr. The crossover distance from the centromere to this gene was estimated in the genetic background of both Cadet and Rescue. The ditelosomic for the long arm of each of the lines Ct"5BL (Crr) and Rt"5BL (crr) was crossed by the corresponding reciprocal chromosome 5B substitutions, C-R5B (crr) and R-C5B (Crr). The F1's, heterozygous for both the telocentric and the alleles, were then backcrossed by the appropriate recessive lines, Cadet and R-C5B. Each backcross plant was tested for its reaction to root rot and examined cytologically for the presence of a telocentric chromosome. The recombination frequency of the centromere, marked by the presence or absence of the telocentric, with alleles at the Crr locus was 42.9 ± 3.4% in the Cadet background. In the Rescue background, the recombination frequency was 36.1 ± 3.3%. The difference is attributed to a generally lower chiasma frequency in Rescue than in Cadet.

scholarly journals Genetic polymorphism for human platelet thermostable phenol sulfotransferase (TS PST) activity.

Genetics ◽  
1989 ◽  
Vol 122 (4) ◽  
pp. 905-914
Author(s):  
R A Price ◽  
R S Spielman ◽  
A L Lucena ◽  
J A Van Loon ◽  
B L Maidak ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Familial Aggregation ◽  
Major Gene ◽  
Polygenic Inheritance ◽  
Nuclear Families ◽  
Basal Activity ◽  
Drug Metabolizing Enzyme ◽  
Phenol Sulfotransferase ◽  
Multiple Component ◽  
Metabolizing Enzyme

Abstract Platelet TS PST basal activity and thermal stability were measured in blood samples from 237 individuals in 50 nuclear families. Significant correlations were found among first degree relatives, confirming the previously reported familial aggregation of TS PST basal activity and thermal stability. Commingling analysis of basal TS PST activity provided evidence for multiple component distributions, and after transformation to remove skewness, segregation analysis supported a major gene hypothesis. For TS PST thermal stability, commingling analysis also provided evidence for multiple component distributions. However, segregation analyses were equivocal with regard to the presence of a major gene for thermal stability, since support for a major gene model depended on skewness. Bivariate commingling analysis, which examined thermal stability by simultaneously considering basal activity and activity after heating, suggested that genotypes, as defined by the inferred component distributions for TS PST activity, differ in thermal stability. A three-allele model is proposed as one hypothesis that may account for the combined results of basal activity and thermal stability. The results of this study indicate that a major gene polymorphism in conjunction with polygenic inheritance plays an important role in the regulation of both level of activity and thermal stability of this important drug-metabolizing enzyme in humans.

scholarly journals Simple penalties on maximum likelihood estimates of genetic parameters to reduce sampling variation

2015 ◽  
Author(s):  
karin meyer
Keyword(s):  
Maximum Likelihood ◽  
Genetic Parameters ◽  
Likelihood Function ◽  
Maximum Likelihood Estimates ◽  
Data Sets ◽  
Simple Modification ◽  
Scale Free ◽  
Wide Range ◽  
Sampling Variation ◽  
The Difference

Multivariate estimates of genetic parameters are subject to substantial sampling variation, especially for smaller data sets and more than a few traits. A simple modification of standard, maximum likelihood procedures for multivariate analyses to estimate genetic covariances is described, which can improve estimates by substantially reducing their sampling variances. This is achieved maximizing the likelihood subject to a penalty. Borrowing from Bayesian principles, we propose a mild, default penalty -- derived assuming a Beta distribution of scale-free functions of the covariance components to be estimated -- rather than laboriously attempting to determine the stringency of penalization from the data. An extensive simulation study is presented demonstrating that such penalties can yield very worthwhile reductions in loss, i.e. the difference from population values, for a wide range of scenarios and without distorting estimates of phenotypic covariances. Moreover, mild default penalties tend not to increase loss in difficult cases and, on average, achieve reductions in loss of similar magnitude than computationally demanding schemes to optimize the degree of penalization. Pertinent details required for the adaptation of standard algorithms to locate the maximum of the likelihood function are outlined.

scholarly journals GENETIC LINKAGE BETWEEN THE AH LOCUS AND A MAJOR GENE THAT INHIBITS SUSCEPTIBILITY TO AUDIOGENIC SEIZURES IN MICE

Genetics ◽  
1981 ◽  
Vol 99 (1) ◽  
pp. 117-126
Author(s):  
Thomas N Seyfried ◽  
Gilbert H Glaser
Keyword(s):  
Genetic Linkage ◽  
Major Gene ◽  
Inbred Strains ◽  
Audiogenic Seizures ◽  
Aryl Hydrocarbon Hydroxylase ◽  
Dominant Trait ◽  
Backcross Generation ◽  
Aryl Hydrocarbon ◽  
The Difference ◽  
Random Survey

ABSTRACT Mice of the DBA/2 (D2) strain are highly susceptible to sound-induced seizures at 21 days of age; whereas, mice of the C57BL/6 (B6) strain are resistant to these seizures. Although the difference in susceptibility to audiogenic seizures (ASs) between these two strains is inherited as a multiple-factor trait, an association was observed between susceptibility to ASs and the Ah locus. The Ah locus controls the inducibility of aryl hydrocarbon hydroxylase (AHH) activity by a number of aromatic hydrocarbons. B6 mice carry the Ahb allele and have inducible AHH activity; whereas, D2 mice carry the Ah  d allele and have noninducible activity. Inducibility is inherited as a Mendelian dominant trait in crosses between these strains. Mice carrying the Ahb allele are generally less susceptible to ASs at 21 days of age than are mice carrying the Ahd allele. The combined results from B6 x D2 recombinant inbred strains, congenic strains (where the Ahb allele was placed into the D2 genome and the Ahd allele placed into the B6 genome), the B6D2F1 × D2 backcross generation, and a random survey of various inbred strains, suggest that the association between these two traits is due to genetic linkage, rather than to pleiotrophy or to chance. A major gene that inhibits susceptibility to ASs appears to be closely linked to the Ah locus. This gene has been designated Ias, for inhibition of ASs. A large portion of the genetic variability of AS susceptibility may be due to the segregation of Ias.

scholarly journals A comparative genetical study on DDT resistance in adults and larvae of the mosquito Aedes aegypti L

1967 ◽  
Vol 10 (3) ◽  
pp. 219-228 ◽  
Author(s):  
R. J. Wood
Keyword(s):  
Linkage Group ◽  
Developmental Stages ◽  
Major Gene ◽  
Group Iii ◽  
Group I ◽  
Fourth Larval Stage ◽  
Ddt Resistance ◽  
Group Ii ◽  
The Difference ◽  
Two Stages

Inheritance of DDT resistance has been studied in crosses between the highly resistant ‘T’ strain of A. aegypti (constituted by inbreeding from the TRINIDAD DDT-resistant stock) and the ‘64’ susceptible strain.Larval DDT resistance derives from a major gene RDDT1 on linkage group II, the order being RDDT1–s–y. Linkage group III may also contribute to larval resistance. Linkage group I makes no contribution.Adult DDT resistance derives from a major gene RDDT2, 18·2 ± 2·1 units from the market blt on linkage group III. Linkage group II has no influence on adult resistance.Selection with DDT to retain only RDDT1/+ segregants in larvae of backcrosses RDDT1/+×+/+ did not increase resistance in resulting adults, confirming the difference in genetic mechanism at the two stages.The F1 progenies from reciprocal crosses between ‘T’ and ‘64’ differed slightly but significantly in larval resistance, modifying the influence of the major gene RDDT1 in the heterozygote.The early developmental stages of the RDDT1/+ phenotype (up to the fourth larval stage) were more viable than the +/+ phenotype in backcross segregation. The difference in mortality probably exceeded 30%.

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