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At least 145 records · Page 8Linked to original sources
PubMed2002

Molecular dissection of complex traits in autopolyploids: mapping QTLs affecting sugar yield and related traits in sugarcane.

Mapping quantitative trait loci (QTLs) for sugar yield and related traits will provide essential information for sugarcane improvement through marker-assisted selection. Two sugarcane segregating populations derived from interspecific crosses between Saccharum offinarum and Saccharum spontaneum with 264 and 239 individuals, respectively, were evaluated in three replications each for field performance from 1994 to 1996 at Weslaco, Texas. These two populations were analyzed for a total of 735 DNA marker loci to seek QTLs for sugar yield, pol, stalk weight, stalk number, fiber content and ash content. Among the 102 significant associations found between these six traits and DNA markers, 61 could be located on sugarcane linkage maps, while the other 41 were associated with unlinked DNA markers. Fifty of the 61 mapped QTLs were clustered in 12 genomic regions of seven sugarcane homologous groups. Many cases in which QTLs from different genotypes mapped to corresponding locations suggested that at least some of the QTLs on the same cluster might be different allelic forms of the same genes. With a few exceptions that explained part of the transgressive segregation observed for particular traits, the allele effects of most QTLs were consistent with the parental phenotype from which the allele was derived. Plants with a high sugar yield possessed a large number of positive QTLs for sugar yield components and a minimal number of negative QTLs. This indicates the potential effectiveness of marker-assisted selection for sugar yield in sugarcane.

Journal Article↗
PubMed2000

The high oleate trait in the cultivated peanut [Arachis hypogaea L]. II. Molecular basis and genetics of the trait.

A peanut variety with high oleate content has previously been described. When this high oleate variety was used in breeding crosses, the F2 segregation ratio of high oleate to normal oleate progeny was 3:1 or 15:1 depending on the normal oleate varieties used in the crosses. These data suggested that the high oleate trait is controlled by two recessive genes, and some peanut varieties differ from the high oleate variety by mutations in one gene, while others differ by mutations in two genes. The objective of this study was to understand the molecular nature of the high oleate trait and the various segregation patterns. In the previous paper in this issue, we reported that the level of transcripts expressed by one (ahFAD2B) of two homoeologous genes for oleoyl-PC desaturases in cultivated peanut is significantly reduced in high oleate varieties. In this report, we examined gene expression by RT-PCR/restriction digestion in a cross that shows a one-gene segregation pattern for the high oleate trait. Our data showed that the severely reduced level of ahFAD2B transcript correlates absolutely with the high oleate phenotype in this cross, suggesting that the single gene difference is correlated with the ahFAD2B transcript level. When we tested the enzyme activity of the proteins encoded by ahFAD2A and ahFAD2B by expression of the cloned sequences in yeast, only the ahFAD2B gene product showed significant oleoyl-PC desaturase activity. These data, combined with the observation that ahFAD2A shows a change (D150N) in a residue that is absolutely conserved among other desaturases, raised the possibility that the ahFAD2A in these normal and high oleate lines is a mutant allele. In support of this hypothesis, we found that another ahFAD2A allele in a normal oleate peanut line does not have the D150N change. This peanut line displays a two-gene-segregation pattern for the high oleate trait. In conclusion, our results suggest that a mutation in ahFAD2A and a significant reduction in levels of the ahFAD2B transcript together cause the high oleate phenotype in peanut varieties, and that one expressed gene encoding a functional enzyme appears to be sufficient for the normal oleate phenotype.

Alleles↗
PubMedDate not supplied

The State-Trait Anxiety Inventory, Trait version: structure and content re-examined.

Although the State-Trait Anxiety Inventory (STAI) is a popular measure of anxiety, some previous research suggests that the trait scale may assess depression, as well as anxiety. The factor structure of the trait items was initially examined using factor analytic procedures. Confirmatory factor analytic methods suggested that a hierarchical solution best fit the data, with one overall factor and two lower order factors. The lower order subscales created from this factor solution were examined in a sample of individuals diagnosed with an anxiety disorder. Overall, the results offered good support for the notion that the trait scale of the STAI assesses depression, as well as anxiety. One set of items appeared to assess anxiety and worry, whereas the other assessed sadness and self-deprecation. The two subscales correlated differentially with other measures of anxiety and depression in a manner that was consistent with their content. Finally, diagnostic groups and controls could be meaningfully distinguished on these subscales. Implications for the use of this measure are discussed.

Adult↗
PubMed2003

A psychometric evaluation of the parent report form of the State-Trait Anxiety Inventory for Children--Trait Version.

We examined the psychometric characteristics of the State-Trait Anxiety Inventory for Children-Parent Report-Trait Version (STAIC-P-T) [Strauss, C. (1987). Modification of trait portion of State-Trait Anxiety Inventory for Children-Parent Form. Gainesville, FL: University of Florida], a brief, parent report paper-and-pencil measure of child chronic anxiety, in a large clinic-referred sample. Internal consistency coefficients were high and retest reliability coefficients were in the moderate range. Convergent validity evidence was mixed in its support for the measure, with evidence most supportive within reporter and within parental dyad. Divergent validity evidence provided less support for the measure, but was largely consistent with past research. Regression analyses indicated that parent reports on the STAIC-P-T were not significantly related to a parent's own level of symptomatology. Overall, the study provides mixed support for the psychometrics of the STAIC-P-T.

Adolescent↗
PubMed1996

Genetic mapping of quantitative trait loci controlling growth and wood quality traits in Eucalyptus grandis using a maternal half-sib family and RAPD markers.

Quantitative trait loci (QTL) mapping of forest productivity traits was performed using an open pollinated half-sib family of Eucalyptus grandis. For volume growth, a sequential QTL mapping approach was applied using bulk segregant analysis (BSA), selective genotyping (SG) and cosegregation analysis (CSA). Despite the low heritability of this trait and the heterogeneous genetic background employed for mapping, BSA detected one putative QTL and SG two out of the three later found by CSA. The three putative QTL for volume growth were found to control 13.7% of the phenotypic variation, corresponding to an estimated 43.7% of the genetic variation. For wood specific gravity five QTL were identified controlling 24.7% of the phenotypic variation corresponding to 49% of the genetic variation. Overlapping QTL for CBH, WSG and percentage dry weight of bark were observed. A significant case of digenic epistasis was found, involving unlinked QTL for volume. Our results demonstrate the applicability of the within half-sib design for QTL mapping in forest trees and indicate the existence of major genes involved in the expression of economically important traits related to forest productivity in Eucalyptus grandis. These findings have important implications for marker-assisted tree breeding.

Chromosome Mapping↗
PubMed1996

Quantitative trait loci analysis for five milk production traits on chromosome six in the Dutch Holstein-Friesian population.

Twenty Dutch Holstein-Friesian families, with a total of 715 sires, were evaluated in a granddaughter experiment design for marker-QTL associations. Five traits-milk, fat and protein yield and fat and protein percent-were analyzed. Across-family analysis was undertaken using multimarker regression principles. One and two QTL models were fitted. Critical values for the test statistic were calculated empirically by permuting the data. Individual trait distributions of permuted test statistics differed and, thus distributions, had to be calculated for each trait. Experimentwise critical values, which account for evaluating marker-QTL associations on all 29 autosomal-bovine chromosomes and for five traits, were calculated. A QTL for protein percent was identified in one, and two QTL models and was significant at the 1 and 2% level, respectively. Extending the multimarker regression approach to an analysis including two QTL was limited by families not being informative at all markers, which resulted in singularity. Below average heterozygosity for the first and last marker lowered information content for the first and last marker bracket. Highly informative markers at the ends of the mapped chromosome would overcome the decrease in information content in the first and last marker bracket and singularity for the two QTL model.

Animals↗
PubMed2004

Are secondary sex traits, parasites and immunity related to variation in primary sex traits in the Arctic charr?

Primary and secondary sex traits are influenced by the same sex hormones, and the expression of secondary sex traits may consequently signal males' capacity for sperm production. Sperm quality may also be influenced by immune activity, as sperm are non-self to the male. Parasite infections alter immune activity and may thus reduce ejaculate quality. In the Arctic charr (Salvelinus alpinus) the red abdominal colour is considered an ornament that signals important information in mate choice. We captured and individually caged sexually mature male Arctic charr during the spawning period. Afterwards we estimated abdominal colour, parasite infections, gonad mass and several spermatological and immunological variables. Intensity of abdominal colour was positively correlated to testes mass, milt mass and sperm cell numbers produced. Additionally, males with low parasite intensities had high testes mass and produced milt with high sperm density, indicating a trade-off between parasite resistance and development of primary sex traits. Our measures of immunity were, however, not related to primary sex traits. We conclude that females evaluating male abdominal coloration may obtain information about differences between males in fertilization potential and parasite resistance.

Animals↗
PubMed1984

The fate of excess beta-globin chains within erythropoietic cells in alpha-thalassaemia 2 trait, alpha-thalassaemia 1 trait, haemoglobin H disease and haemoglobin Q-H disease: an electron microscope study.

Electron microscope studies have been performed on bone marrow cells from individuals with various alpha-thalassaemia syndromes. Globin chain precipitates were rarely found in the erythropoietic cells of a subject with alpha-thalassaemia 2 trait. By contrast, such precipitates were found in 0.6 - 1.3% of the erythroblast and marrow reticulocyte profiles in two cases of alpha-thalassaemia 1 trait, 2.1 - 13.7% of profiles in five patients with haemoglobin H (HbH) disease and 6.2% of profiles in one patient with haemoglobin Q-H (HbQ-H) disease. In the patient with HbQ-H disease, but not in the others, the nuclei of some erythroblasts displayed the 'Swiss cheese' appearance which has been reported in some forms of congenital dyserythropoietic anaemia. It is proposed that in alpha-thalassaemia 2 trait, where the degree of excess of beta-chains is slight, most of the excess chains are degraded by proteolysis. In alpha-thalassaemia 1 trait, where there is a greater excess of beta-chains, the excess chains can undergo either proteolysis or precipitation, but there is little or no tetramerization to form soluble HbH. Finally, in HbH disease, where the degree of excess is considerable, the excess beta-chains may be subject to proteolysis, precipitation and tetramerization.

Adult↗
PubMed1979

A factor analysis of traits as measured by COCSTOC-MOT to identify occlusal trait combinations.

Occlusal conditions which vary significantly from accepted social norms for dental appearance may socially handicap an individual. An instrument is required by which socially unacceptable occlusal conditions can be identified by members of the public who have internalized society's norms for acceptable dental appearance. The factors identified in this paper make it possible to select a reasonable number (100) of models for constructing a measurement instrument which depicts the full range of occlusal patterns found in a natural population for use in assessing the social acceptability of occlusal conditions. This paper presents the methodology and process used to identify individual occlusal traits which tend to occur together in trait combinations or independently and their range from "normal" to extreme. Data on the frequency distribution of the individual COCSTOC measurements found in a natural population was subjected to a factor analysis which identified 18 occlusal patterns (combinations of traits) and five unique or independent traits or anomalies.

Adolescent↗
PubMedDate not supplied

Multiple trait model combining random regressions for daily feed intake with single measured performance traits of growing pigs.

A random regression model for daily feed intake and a conventional multiple trait animal model for the four traits average daily gain on test (ADG), feed conversion ratio (FCR), carcass lean content and meat quality index were combined to analyse data from 1449 castrated male Large White pigs performance tested in two French central testing stations in 1997. Group housed pigs fed ad libitum with electronic feed dispensers were tested from 35 to 100 kg live body weight. A quadratic polynomial in days on test was used as a regression function for weekly means of daily feed intake and to describe its residual variance. The same fixed (batch) and random (additive genetic, pen and individual permanent environmental) effects were used for regression coefficients of feed intake and single measured traits. Variance components were estimated by means of a Bayesian analysis using Gibbs sampling. Four Gibbs chains were run for 550000 rounds each, from which 50000 rounds were discarded from the burn-in period. Estimates of posterior means of covariance matrices were calculated from the remaining two million samples. Low heritabilities of linear and quadratic regression coefficients and their unfavourable genetic correlations with other performance traits reveal that altering the shape of the feed intake curve by direct or indirect selection is difficult.

Analysis of Variance↗
PubMed2004

Coping skills: role of trait sport confidence and trait anxiety.

The current research assesses relationships among coping skills, trait sport confidence, and trait anxiety. Two samples (n=47 and n=77) of international competitors from surf life saving (M=23.7 yr.) and touch rugby (M=26.2 yr.) completed the Athletic Coping Skills Inventory, Trait Sport Confidence Inventory, and Sport Anxiety Scale. Analysis yielded significant correlations amongst trait anxiety, sport confidence, and coping. Specifically confidence scores were positively associated with coping with adversity scores and anxiety scores were negatively associated. These findings support the inclusion of the personality characteristics of confidence and anxiety within the coping model presented by Hardy, Jones, and Gould, Researchers should be aware that confidence and anxiety may influence the coping processes of athletes.

Adaptation, Psychological↗
PubMed2002

Effects of vascular infusion with a solution of saccharides; sodium chloride; phosphates; and vitamins C, E, or both on carcass traits, Warner-Bratzler shear force, and palatability traits of steaks and ground beef.

Three groups of 12 high percentage Charolais steers were slaughtered on three dates. Steers (n = 27) were infused immediately after exsanguination at 10% of BW with a solution containing saccharides, NaCl, and phosphates (MPSC solution; MPSC, Inc., St. Paul, MN) plus either 500 ppm vitamin C (MPSC+C), 500 ppm vitamin E (MPSC+E), or 500 ppm vitamin C plus 500 ppm vitamin E (MPSC+C+E). Noninfused controls (CON) were 9 steers. The longissimus thoracis (LT), semitendinosus (ST), and quadriceps femoris muscles were removed at 48-h postmortem, vacuum-packaged, and aged until 14-d postmortem. Steaks 2.54-cm thick were cut from the LT and ST. The quadriceps was utilized for ground-beef production. Infused steers had higher dressing percentages and heavier heart and liver weights (P < 0.05) than CON. Vascular infusion with vitamins C, E, or C plus E had no effect (P > 0.05) on USDA yield and quality-grade traits, LT and ST Warner-Bratzler shear force, descriptive-attribute traits, and freshly cooked steak flavor-profile traits. Vascular infusion had little effect on the flavor-profile traits of warmed-over steaks. Therefore, the results of our study indicate that vascular infusion with vitamins C, E, or C plus E can increase dressing percentage and organ weights, but have minimal effects on descriptive-attribute and flavor-profile sensory panel ratings.

Animals↗
PubMed1980

Artificial insemination of individually caged broiler breeders. II. The relationships of juvenile male traits with subsequent reproductive traits.

The relationship of the reproductive performance and semen characteristics of commerical broiler parent males with their body weight at 6, 8, 10, and 12 weeks of age, keel length, shank length, breast angle at 8 weeks of age, and packed erythrocyte volume at 6 and 8 weeks of age were examined. Phenotype correlations of juvenile traits with subsequent reproductive traits were generally of low magnitude, except for the significant positive correlations of 6- and 8-week body weight with fertility. Positive correlations existed between fertility and semen quality traits which were significant in some cases. Six-week body weight and spermatozoal motility appeared to be the most useful traits in predicting a male's fertility.

Animals↗
PubMed1993

Association of dominant marker traits and metric traits in chickens.

This study was initiated to determine whether an allelic substitution of a dominant marker gene would identify a region close to a locus affecting expression in a metric trait. The rationale for the experiment was to utilize disequilibrium between a multiple recessive randombred Rhode Island Red (RRc) stock previously selected for quantitative trait performance and an unimproved dominant marker stock (MDM). The reporter genes in the MDM were: barring (B), silver (S), creeper (Cp), rose comb (R), double uropygial gland (U), crest (Cr), dominant white (I), frizzle (F), duplex comb (D), multiple spurs (M), polydactyly (Po), blue egg (O), pea comb (P), naked neck (Na), extended black (E), white skin (W+), muffs and beard (Mb), and feathered shanks (Fsh). Appropriate reciprocal crosses of MDM with RRc and F1 to RRc produced segregating full sibs that were evaluated for association with reporter traits. Carriers of Cr, I, and F were significantly later in sexual maturity than their recessive full sibs. The pleiotropic effects of F are believed to account for the later maturity. None of the marker traits had a significant association with egg numbers or egg weight. Birds expressing E were distinctly heavier at 8 and 32 wk. There is no obvious explanation for the significant larger size for the E phenotype. The CR-I-F phenotypes were significantly smaller at 32 wk than noncarrier full sibs.

Alleles↗
PubMed2002

Platelet adenylyl cyclase activity as a state or trait marker in alcohol dependence: results of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence.

BACKGROUND: There has been considerable interest in identifying biochemical markers indicative of a genetic predisposition to alcohol dependence ("trait markers"), as well as biochemical markers of recent alcohol drinking ("state markers"). Platelet adenylyl cyclase activity has been suggested as a trait and/or as a state marker related to alcohol dependence. We have now measured platelet adenylyl cyclase activity in more than 1400 well-characterized subjects, which allows us to investigate the influence of a broad range of factors on this activity. METHODS: Subjects were recruited as part of the WHO/ISBRA Study on State and Trait Markers of Alcohol Use and Dependence and were interviewed by using the WHO/ISBRA Interview Schedule. Adenylyl cyclase activity (basal, cesium fluoride [CsF]-, forskolin- and Gpp(NH)p-stimulated activities) was measured in platelet samples that were obtained at the time of interview. Data were analyzed by multivariate regression analyses. RESULTS: The multivariate analyses revealed that recent abstinence from alcohol was associated with diminutions in platelet adenylyl cyclase activities. A positive family history of alcohol dependence was associated with higher levels of adenylyl cyclase activities, and there was a significant interaction between the effect of alcohol consumption in the past month and family history of alcohol dependence; that is, the influence of alcohol consumption depended on whether the individual had a positive family history. A history of marijuana abuse also was associated with higher levels of platelet adenylyl cyclase activities, and a history of major depression was associated with lower levels of forskolin- and CsF-stimulated activities. Sex, race, and site of recruitment also affected some adenylyl cyclase activities, but there was no significant association of alcohol dependence or abuse with any of the platelet adenylyl cyclase activities. DISCUSSION: The large population and extensive characterization of subjects in this study provided an advantage over previous studies in which only the association of a few individual factors with adenylyl cyclase activity was investigated. The results demonstrate that although platelet adenylyl cyclase activity could be useful as a trait marker of alcohol dependence, its reliability in this regard is diminished by the influence of recent alcohol drinking and other variables. The associations between platelet adenylyl cyclase activities and marijuana abuse, as well as a history of depression, suggest that it may be worthwhile to study the genetic association of adenylyl cyclases (e.g., polymorphisms in the genes that code for particular adenylyl cyclase isoforms) with a predisposition to depression as well as to alcohol or marijuana abuse/dependence.

Adenylyl Cyclases↗
PubMed2005

Methodology of mapping quantitative trait loci for ordinal traits of disease resistance in livestock.

Methodology of QTL mapping for ordinal traits of disease resistance based on the framework of a generalized linear model (GLM) was presented. The location and effect parameters of putative QTL were estimated using maximum likelihood method. The efficiency and power were compared with the linear model (LM). The factors influencing QTL detection efficiency (e.g. QTL effect and heritability) were simulated in our study too. Daughter design with multiple families was applied,and the number of segregating population was 500. Results showed that the threshold model has a certain advantage in location estimation and power of QTL mapping, and has efficiency and accuracy for ordinal traits. In addition,the accuracy of QTL mapping depends on the effect of putative quantitative trait loci and the value of heritability. With the increase of QTL effect and heritability, the accuracy of QTL mapping improves slightly.

Animals↗
PubMed2002

Mapping and analysis of quantitative trait loci for grain oil content and agronomic traits using AFLP and SSR in sunflower ( Helianthus annuus L.).

Crosses were made between two inbred lines of sunflower. Parents and 118 F(3) families were planted in the field in a randomized complete block design in two replications. Genetic control for some agronomical traits: grain weight by plant (GWP), 1,000-grain weight (TGW), percentage of oil in grain (POG) and sowing to flowering date (STF) was investigated in F(3) families and their parents. Genetic variability was observed among the 118 F(3) families for all the traits studied. Genetic gain was obtained when the best F(3) family, or the mean of 10% of the selected families was compared with the best parent for GWP, TWG and POG. Heritability was 0.23 for GWP, 0.55 for TGW, 0.57 for POG and 0.32 for STF. A set of 244 F(3) families from the same cross, including the above 118 mentioned families and their two parents, were screened with 276 AFLP and microsatellite markers and a linkage map was constructed based on 170 markers. Two putative QTLs for the GWP trait ( gmp), one QTL for TGW ( tgw), six QTLs for POG ( pog) and two for STF ( stf) were detected. The percentage of phenotypic variance explained by each QTL ranged from 2.6% to 70.9%. The percentage of total phenotypic variance explained was 50.7% for GWP, 5.4% for TGW, 90.4% for POG and 89.3% for STF. Although these regions need to be more-precisely mapped, the information obtained should help in marker-assisted selection.

Chromosome Mapping↗
PubMed2006

Detection of quantitative trait loci for seminal root traits in maize (Zea mays L.) seedlings grown under differential phosphorus levels.

Suboptimal phosphorus availability is a primary constraint for terrestrial plant growth. Seminal roots play an important role in acquisition of nutrients by plant seedlings. The length and number of seminal roots may be particularly important in acquisition of immobile nutrients such as phosphorus by increasing soil exploration. The objective of this study was to identify quantitative trait loci (QTL) controlling seminal root growth in response to phosphorus stress in maize, and to characterize epistatic interactions among QTL. Seminal root length and number were evaluated in 162 recombinant inbred lines derived from a cross between B73 and Mo17 in seedlings grown in a controlled environment. B73 and Mo17 significantly differed for seminal root length under low phosphorus, but not under adequate phosphorus conditions. Seminal root length of the population grown under low phosphorus ranged from 0 to 79.2 cm with a mean of 32.3 cm; while seminal root length of plants grown under high phosphorus ranged from 0.67 to 59.0 cm with a mean of 23.4 cm. Under low phosphorus, one main-effect QTL was associated with seminal root length and three QTL with seminal root number; under high phosphorus, two QTL with seminal root length and three QTL for seminal root number. These accounted for 11, 25.4, 22.8, and 24.1% of the phenotypic variations for seminal root length and number at low phosphorus, and seminal root length and number at high phosphorus, respectively. Di-genic epistatic loci were detected for seminal root length at low phosphorus (two pairs) seminal root number at low phosphorus (eight pairs), seminal root length at high phosphorus (four pairs), and seminal root number at high phosphorus (two pairs), which accounted for 23.2, 50.6, 32.2, and 20.3% of the total variations, respectively. Seminal root traits observed here were positively yet weakly correlated with shoot biomass in the field under low phosphorus, although no coincident QTL were detected. These results suggest that epistatic interactions are important in controlling genotypic variation associated with seedling seminal root traits.

Chromosome Mapping↗