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Detection and characterization of quantitative trait loci for meat quality traits in pigs.

In an experimental cross between Meishan and Dutch Large White and Landrace lines, 785 F2 animals with carcass information and their parents were typed for molecular markers covering the entire porcine genome. Linkage was studied between these markers and eight meat quality traits. Quantitative trait locus analyses were performed using interval mapping by regression under two genetic models: 1) the line-cross approach, where the founder lines were assumed to be fixed for different QTL alleles and 2) a half-sib model where a unique allele substitution effect was fitted within each of the 38 half-sib families. The line-cross approach included tests for genomic imprinting and sex-specific QTL effects. In total, three genome-wide significant and 26 suggestive QTL were detected. The significant QTL on chromosomes 3, 4, and 13, affecting meat color, were only detected under the half-sib model. Failure of the line-cross approach to detect the meat color QTL suggests that the founder lines have similar allele frequencies for these QTL. This study provides information on new QTL affecting meat quality traits. It also shows the benefit of analyzing experimental data under different genetic and statistical models.

Alleles↗

Detection of quantitative trait loci influencing dairy traits using a model for longitudinal data.

A longitudinal-linkage analysis approach was developed and applied to an outbred population. Nonlinear mixed-effects models were used to describe the lactation patterns and were extended to include marker information following single-marker and interval mapping models. Quantitative trait loci (QTL) affecting the shape and scale of lactation curves for production and health traits in dairy cattle were mapped in three U.S. Holstein families (Dairy Bull DNA Repository families one, four, and five) using the granddaughter design. Information on 81 informative markers on six Bos taurus autosomes (BTA) was combined with milk yield, fat, and protein percentage and somatic cell score (SCS) test-day records. Six percent of the single-marker tests surpassed the experiment-wise significance threshold. Marker BL41 on BTA3 was associated with decrease in milk yield during mid-lactation in family one. The scale and shape of the protein percentage lactation curve in family four varied with BMC4203 (BTA6) allele that the son received from the grandsire. Some map locations were associated with variation in the lactation pattern of multiple traits. In family four, the marker HUJI177 (BTA3) was associated with changes in the milk yield and protein percentage curves suggesting a QTL with pleiotropic effects or multiple QTL in the region. The interval mapping model uncovered a QTL on BTA7 associated with variation in milk-yield pattern in family four and a QTL on BTA21 affecting SCS in family five. The developed approach can be extended to random regressions, covariance functions, spline, gametic and variance component models. The results from the longitudinal-QTL approach will help to understand the genetic factors acting at different stages of lactation and will assist in positional candidate gene research. Identified positions can be incorporated into marker-assisted selection decisions to alter the persistency and peak production or the fluctuation of SCS during a lactation.

Animals↗

Detection of quantitative trait loci affecting milk production traits on bovine chromosome 6 in a Chinese Holstein population by the daughter design.

Fourteen microsatellite markers with a coverage of 63.5 cM on bovine chromosome 6 were selected, and 26 sire families with 2,260 daughters were analyzed for mapping quantitative trait loci (QTL) affecting 5 milk production traits in a Chinese Holstein population. In the analyses across 26 families and within the largest significant families with a one-QTL model fitted, a QTL near BMS470 was detected that affected fat yield at the 5% experiment-wide significance level. When a 2-QTL model was fitted in the across-family analysis, it was found that there might exist 2 QTL affecting the 3 yield traits, although the exact or empirical thresholds for the significance testing were unknown. In all analyses, the results for milk yield and protein yield were generally consistent, which might have resulted from the same genetic background for milk and protein yield.

Animals↗

Multitrait quantitative trait Loci mapping for milk production traits in danish Holstein cattle.

The aims of this study were (1) to confirm previously identified quantitative trait loci (QTL) on bovine chromosomes 6, 11, 14, and 23 in the Danish Holstein cattle population, (2) to assess the pleiotropic nature of each QTL on milk production traits by building multitrait and multi-QTL models, and (3) to include pedigree information on nongenotyped individuals to improve the estimation of genetic parameters underlying the random QTL model. Nineteen grandsire families were analyzed by single-trait (ST) and multitrait (MT) QTL mapping methods. The variance component-based QTL mapping model was implemented via restricted maximum likelihood (REML) to estimate QTL position and parameters. Segregation of the previously identified QTL was confirmed on bovine chromosomes 6, 11, and 14, but not on 23. A highly significant (1% chromosome-wise level) QTL was found on chromosome 6, between 37 and 73 cM. This QTL had a strong effect on protein percentage (PP) and fat percentage (FP) according to ST analyses, and effects on PP, FP, milk yield (MY), fat yield (FY), and protein yield (PY) in MT analyses. A QTL affecting PP was detected on chromosome 11 (at 70 cM) using ST analysis. The MT analysis revealed a second QTL (at 67 cM) approaching significance with an effect on MY. The ST analysis identified a QTL for MY and FP on chromosome 14, between 10 and 24 cM. The extended pedigree (nongenotyped animals) was included to estimate genetic parameters underlying the random QTL model; that is, additive polygenic and QTL variances. In general, the estimates of the QTL variance components were smaller but more precise when the extended pedigree was considered in the analysis.

Animals↗

Estimation of genetic parameters for quantitative trait loci for dairy traits in the French Holstein population.

A marker-assisted selection program (MAS) has been implemented in dairy cattle in France. The efficiency of such a selection program depends on the use of correct genetic parameters for the marked quantitative trait loci (QTL). Therefore, the objective of this study was to estimate the proportion of genetic variance explained by 4 QTL described in previous studies (these QTL are segregating on chromosomes 6, 14, 20, and 26). Genotypes for 11 markers were available for 3,974 bulls grouped within 54 sire families of the French Holstein population undergoing MAS. The parameters were estimated for 4 QTL and 5 dairy traits: milk, fat and protein yields, and fat and protein percentages. The proportion of genetic variance explained by the QTL ranged from as low as 0.03 to 0.36%. Both lack of marker informativity and poor monitoring of QTL transmission might limit the accuracy of estimation. The QTL explained a larger proportion of genetic variance for milk composition traits. The QTL on chromosome 14 and chromosomes 6 and 20 have their largest influence on fat and protein percentages, respectively. The overall proportions of genetic variance explained by the QTL were 27.0, 30.7, 24.1, 48.2, and 33.6% for milk, fat and protein yields, and fat and protein percentages, respectively. These results clearly indicated that a large part of the genetic variance is explained by a small number of QTL and that their use in MAS might be beneficial for dairy cattle breeding programs.

Animals↗

Novel quantitative trait loci for blood pressure and related traits on rat chromosomes 1, 10, and 18.

Hypertension and diabetes mellitus are known to be frequently associated. The genetic dissection of diseases such as hypertension or diabetes mellitus is possible by using experimental crosses, which allow identification of loci influencing phenotypic traits (quantitative trait loci - QTLs). In this study the spontaneously hypertensive rat (SHR) and spontaneously diabetic, but normotensive rat (BB/OK) were crossed and the F2 population was analysed in order to search for QTLs on selected chromosomes (1, 10, 18) for blood pressure and some metabolic traits related to diabetes, renal function and hypertension. There were 3 regions found on chromosome 1 which showed linkage to blood pressure. The strongest evidence for linkage was observed between loci Igf2 and D1Mgh12. On chromosome 10 there was a QTL for blood pressure found between Ppy and Abp and on chromosome 18 there were three regions (Ttr-Grl, Tilp-Gja1, Olf-D18Mit9) with linkage to blood pressure. Since the 24 hr albumin and phosphate excretion correlated with blood pressure in F2 hybrids, the same regions were linked to both parameters. Region with linkage to serum concentrations of cholesterol (probably located beyond the terminal marker Ttr of the linkage group) were also found. The results of this study with a new F2(BB x SHR) population confirm the existence of previously described blood pressure loci (Sa and Bp2) and showed novel QTLs on chromosomes 1, 10 and 18.

Albuminuria↗

[Temperament- and character traits as well as trait patterns in alcoholic men and controls].

This study is on the personality of alcoholics, an empirical investigation based on Cloninger's biopsychological temperament- and character-traits. His Temperament and Character Inventory (TCI) was applied to 94 detoxified men suffering from primary alcohol dependence as well as to controls matched for sex and sociodemographic data. The following questions were the matter of interest: (1) Do alcoholics and controls differ in their personality as reflected by the TCI and (2) are there indicators based on personality with potential relevance for differential therapies? A multiple univariate statistical comparison yielded significant differences between alcoholics and controls on only 2 subscales (Sentimentality, Resourcefulness). A multivariate analysis of the TCI temperament traits using two-sample configural frequency analysis revealed no statistically significant difference between the two groups. Temperament patterns associated with Cloninger's Type-I/Type-II alcoholics could not be demonstrated. Analyzing the temperament and character traits of the alcohol dependent subjects with a log-linear model revealed two bivariate temperament-/character classifications on the scales "Harm Avoidance" and "Self-Directedness" as well as "Reward Dependence" and "Self Transcendence"-both making it possible to define subgroups which may be relevant for different therapeutical approaches. Taken together, the results of this study suggest that it may be useful to closer investigate the personality of alcoholics even if it is not principally different from that of control subjects.

Adult↗

An AFLP and RFLP linkage map and quantitative trait locus (QTL) analysis of growth traits in Salix.

A genetic linkage map of Salix (2n = 38), composed of 325 AFLP and 38 RFLP markers has been constructed. The map was based on a population ( n = 87) derived from a cross between the male hybrid clone "Björn" ( Salix viminalis x Salix schwerinii) and the female clone "78183" ( S. viminalis). Three hundred fifty seven AFLPs corresponding to DNA polymorphisms heterozygous in one parent and null in the other were scored. A total of 87 RFLP probes, most (83) derived from the Populus genome, yielded 39 and 11 polymorphic loci segregating in a 1:1 and 1:2:1 ratio respectively. Two maps, one for each parent, were constructed according to the "two-way pseudo-testcross" mapping strategy. The S. viminalis x S. schwerinii map (2,404 cM) included 217 markers and formed 26 major linkage groups while S. viminalis (1,844 cM) consisted of 146 markers placed on 18 major groups. In addition, eight and 14 additional minor linkage groups composed of less than four markers (doubles and triplets) were obtained in the S. viminalis x S. schwerinii and the S. viminalis maps, respectively. Both maps provided 70-80% genome coverage with an average density of markers of 14 cM. To investigate possible homologies between the parental maps, 20 AFLPs and 11 RFLPs segregating in 3:1 or 1:2:1 ratios were included in the linkage analysis. Eight linkage groups homologous between the two maps were detected. The present genetic map was used to identify quantitative trait loci (QTLs) affecting growth-related traits. Eleven QTLs were identified; seven QTLs for height growth, one QTL for stem diameter, one QTL for the height: diameter ratio, one QTL for the number of vegetative buds during flowering time and one QTL for the number of shoots. The estimated magnitude of the QTL effect ranged from 14 to 22% of the total phenotypic variance. One QTL associated with height growth and one affecting the height: diameter ratio were overlapping in the same marker interval with the QTL affecting stem diameter. QTL stability over years was estimated for traits measured in multiple years. Generally, QTLs were only significant in a single year although two QTLs for height growth were close to reaching the significance level in 2 consecutive years.

Journal Article↗

Age-age and trait-trait correlations for Eucalyptus grandis Hill ex Maiden and their implications for optimal selection age and design of clonal trials.

Previous results from seven locations of Eucalyptus grandis clonal trials in Colombia supported the a priori contention of sub-dividing them into three different environmental zones for testing and deployment. Within these zones, the determination of age-age genetic correlations for both height and mean annual increment (MAI) showed that strong age-age correlations are present for a rotation age of 6 years starting at 3 years age and, thereafter, suggesting this age as appropriate for selection. This biological selection age coincides with an "economical" age for selection based on discounted selection efficiency in perpetuity, considering a range of interest rates between 10% and 20%. High genetic correlations between wood density at 3 years and 6 years as well as the lack of genetic correlation between this trait and growth traits, also favors selection at age 3 and facilitates breeding strategies that consider the utilization of both traits for improvement. A simulation of optimal clonal test designs indicated that by using six locations and six blocks per location in a single-tree plot design, between 80% and 90% of the maximum selection efficiency could be obtained. This type of design allows testing of a large number of genotypes across a reasonable number of locations in a cost-effective manner.

Chromosome Mapping↗

Personality traits in Sardinia: testing founder population effects on trait means and variances.

Potential founder population effects on personality trait means and variances were examined in a large, genetically homogeneous sample (N=5,669) from the Ogliastra, an isolated region within Sardinia, Italy. The Italian version of the Revised NEO Personality Inventory showed good psychometric properties: Internal consistency reliabilities ranged from 0.80 to 0.87; the factor structure replicated the American normative structure; and associations with education and gender replicated cross-cultural patterns. The hypothesis that mean trait levels in the Sardinian founder population would differ from mainland Italian values was not supported. Phenotypic variation in this founder population was within the range found in other cultures. However, the hypothesis of restricted phenotypic variation was supported for all five factors and 28 of the 30 facets when a Sardinian subsample matched on age, sex, and education was compared to a mainland Italian sample. The genetic homogeneity effect on the phenotypic expression of complex traits merits further exploration.

Analysis of Variance↗

Variables associated with peripartum traits in dairy cows. III. Effect of diets and disorders on certain blood traits.

BLood samples were collected from 89 Holstein cows on days 220 and 250 of gestation, within 24 hr prepartum and postpartum and on day 30 postpartum. Balanced diets which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were fed from day 220 of gestation to day 30 postpartum. The purpose was to determine if variations in certain blood traits were indicative of peripartum and postpartum disorders. The blood traits evaluated were concentrations of plasma total protein, whole blood hemoglobin, packed cell volume, and white blood cells, and serum glutamic oxalacetic transaminase (SGOT), glucose, urea nitrogen, calcium, inorganic phosphorus, magnesium, potassium and sodium. No blood trait was useful to predict a disorder prior to its visual signs with one possible exception. Serum glucose and calcium were lower and SGOT and magnesium were higher peripartum which was prior to death of three cows from fat cow syndrome.

Journal Article↗

MCMI-II personality traits and symptom traits in parents of children with selective mutism: a case-control study.

The etiology of selective mutism (SM) in children is unknown but is regarded as multifactorial. SM is frequently associated with social anxiety and language disorder or delay. The present study addresses SM and social anxiety as a familial phenomenon by comparing self-reported personality traits and symptom traits (Millon Clinical Multiaxial Inventory) in parents of 50 SM children with control parents. Personality and symptom traits reflecting social anxiety are also explored separately in the parents of SM children with and without a comorbid communication disorder. The results confirm SM and social anxiety as a familial phenomenon. Assessment and treatment planning should take this into account. The family data also suggest different family transmissions of SM and social anxiety in the SM group with and without a comorbid communication disorder.

Case-Control Studies↗

Does trait coping exist? A momentary assessment approach to the evaluation of traits.

This study investigated the extent to which momentary reports of coping are a traitlike phenomenon and the validity of a questionnaire assessment of coping style. Participants (N = 96) completed the questionnaire, then monitored stressful events and coping activities for 2 days using a hand-held computer that administered a brief assessment every 40 min. Momentary reports exhibited a sizable traitlike component: Individual differences accounted for 42% of the variance for 2 coping items and 15-30% of the variance for 15 items. The questionnaire assessment of coping style was a poor predictor of average momentary coping; the coping style measure and the aggregated momentary measure of trait coping shared 23% of their variance for religion and 0-12% for the 16 other coping measures. Self-report assessments of trait coping are poor measures of the trait component of momentary coping and very poor predictors of coping in specific situations.

Adaptation, Psychological↗

Empirical and conceptual problems with longitudinal trait-state models: introducing a trait-state-occasion model.

The latent trait-state-error model (TSE) and the latent state-trait model with autoregression (LST-AR) represent creative structural equation methods for examining the longitudinal structure of psychological constructs. Application of these models has been somewhat limited by empirical or conceptual problems. In the present study, Monte Carlo analysis revealed that TSE models tend to generate improper solutions when N is too small, when waves are too few, and when occasion factor stability is either too large or too small. Mathematical analysis of the LST-AR model revealed its limitation to constructs that become more highly auto-correlated over time. The trait-state-occasion model has fewer empirical problems than does the TSE model and is more broadly applicable than is the LST-AR model.

Empirical Research↗

Separating trait effects from trait-specific method effects in multitrait-multimethod models: a multiple-indicator CT-C(M-1) model.

An overview of several models of confirmatory factor analysis for analyzing multitrait-multimethod (MTMM) data and a discussion of their advantages and limitations are provided. A new class of multi-indicator MTMM models combines several strengths and avoids a number of serious shortcomings inherent in previously developed MTMM models. The new models enable researchers to specify and to test trait-specific-method effects. The trait and method concepts composing these models are explained in detail and are contrasted with those of previously developed MTMM models for multiple indicators. The definitions of the models are explained step by step, and a practical empirical application of the models to the measurement of 3 traits x 3 methods is used to demonstrate their advantages and limitations.

Affect↗

A linkage strategy for detection of human quantitative-trait loci. I. Generalized relative risk ratios and power of sib pairs with extreme trait values.

We generalize the concept of the relative risk ratio (lambda) to the case of quantitative traits, to take into account the various trait outcomes of a relative pair. Formulas are derived to express the expected proportions of genes shared identical by descent by a sib pair, in terms of the generalized lambda's for sib pairs (lambda S), parent-offspring pairs (lambda O), and monozygotic twins (lambda M) and in terms of the recombination fraction, with the assumption of no residual correlations. If residual correlations are nonzero among relative pairs, we assume that they are the same among sib pairs, parent-offspring pairs, and monozygotic twins, and we employ a slightly different definition for the generalized lambda so that the same set of formulas still hold. The power (or, the sample size necessary) to detect quantitative-trait loci (QTLs) by use of extreme sib pairs (ESPs) is shown to be a function of the three generalized lambda's. Since lambda M can be derived by use of values of lambda S and lambda O, estimates of the latter two lambda's will suffice for the analysis of power and the necessary sample sizes of ESPs, for a QTL linkage study.

Female↗

The effects of spontaneous mutation on quantitative traits. I. Variances and covariances of life history traits.

We have accumulated spontaneous mutations in the absence of natural selection in Drosophila melanogaster by backcrossing 200 heterozygous replicates of a single high fitness second chromosome to a balancer stock for 44 generations. At generations 33 and 44 of accumulation, we extracted samples of chromosomes and assayed their homozygous performance for female fecundity early and late in adult life, male and female longevity, male mating ability early and late in adult life, productivity (a measure of fecundity times viability) and body weight. The variance among lines increased significantly for all traits except male mating ability and weight. The rate of increase in variance was similar to that found in previous studies of egg-to-adult viability, when calculated relative to trait means. The mutational correlations among traits were all strongly positive. Many correlations were significantly different from 0, while none was significantly different from 1. These data suggest that the mutation-accumulation hypothesis is not a sufficient explanation for the evolution of senescence in D. melanogaster. Mutation-selection balance does seem adequate to explain a substantial proportion of the additive genetic variance for fecundity and longevity.

Animals↗

Mapping quantitative trait loci affecting life history traits in the nematode Caenorhabditis elegans.

We have identified chromosomal regions containing quantitative trait loci (QTLs) specifying life history traits in recombinant-inbred strains of the nematode Caenorhabditis elegans. This approach also allows us to examine epistatic interactions between loci and pleiotropic effects on different traits at specific loci. QTLs for mean life span were identified on chromosomes II (near stP101), IV (stP5) and the X (stP61), and QTLs for fertility were identified on II (maPI), III (stP19) and IV (stP51). The QTLs for mean life span accounted for 90% of the genetic component of variance. The loci for mean fertility accounted for 88% of the genetic component of variance. Additional QTLs for temperature-sensitive fertility [II (stP36) and V (stP6)] and internal hatching [IV (stP5)] were also mapped in these crosses. We found evidence for epistatic effects on mean life span between maP1 and bP1 (V), and for epistatic effects on mean fertility between stP36 and stP6, between stP98 (II) and stP192 (V), between maP1 and stP127 (III), between maP1 and stP103 (X), and between stP5 and stP6. Negatively correlated, pleiotropic effects on mean life span and internal hatching were found linked to stP5.

Animals↗