(1/858) Inheritance of flower color in periwinkle: orange-red corolla and white eye.
The commonly found flower colors in periwinkle (Catharanthus roseus)--pink, white, red-eyed, and pale pink center--are reported to be governed by the epistatic interaction between four genes--A, R, W, and I. The mode of inheritance of an uncommon flower color, orange-red corolla and white eye, was studied by crossing an accession possessing this corolla color with a white flowered variety (Nirmal). The phenotype of the F(1) plants and segregation data of F(2) and backcross generations suggested the involvement of two more interacting and independently inherited genes, one (proposed symbol E) determining the presence or absence of red eye and another (proposed symbol O) determining orange-red corolla. (+info)
(2/858) Inheritance and linkage of allozymes in a Balkan endemic, Pinus peuce Griseb.
This article presents a study of isozyme variation in Pinus peuce Griseb., a Balkan endemic. Among the enzyme systems studied, five were monomorphic and eight were polymorphic in at least one locus. The segregation analysis of the polymorphic loci were consistent with a Mendelian mode of inheritance. No significant deviation from the expected ratio was observed both at the individual and pooled segregation data levels. Segregation patterns were homogeneous across individuals. Two significant linkage groups were found in P. peuce: FEST-2:LAP-2 and 6PG-1:6PG-2, which correspond to the results obtained for other pine species. (+info)
(3/858) Dopaminergic system genes in ADHD: toward a biological hypothesis.
Converging evidence has implicated abnormalities of dopamine neurotransmission to the pathology of attention deficit hyperactivity disorder (ADHD). Several genetic association studies have been published, but so far, no DNA variants have been unequivocally demonstrated as contributing to ADHD susceptibility. Four dopamine related gene loci have been implicated, however: DAT 1, DRD 4, DBH, and DRD 5. Each of these may influence the liability of ADHD to a small degree. Notably, all are involved in signal transduction at the neuronal synapse. In this article, we investigate as candidate genes for ADHD, DNA polymorphisms at dopamine receptors, the dopamine transporter, and genes known to be involved in dopamine synthesis and metabolism. In a recent article, we confirmed the previously reported association of DAT 1 (480 bp allele) with ADHD and identified polymorphisms at two additional loci showing preferential transmission to ADHD children of alleles at DRD 5 (148 bp allele) and at DBH (allele 2, Taq I polymorphism). Increased transmission of the 4 bp deletion in the untranslated exon 1 of the DOPA decarboxylase gene was also observed but was of marginal significance. Nonsignificant trends of association were found for TH (allele 2) and DRD2 (Ser-311). No preferential transmission of alleles to ADHD children was observed for polymorphisms at DRD 1, DRD 2 (Taq I), DRD 3, DRD 4, and COMT. Analyzing the data by sex of transmitting parent showed significant preferential paternal transmission of alleles at TH (allele 2) and a nonsignificant trend for paternal transmission for DRD 2 (Ser-311). We attempt to put these findings together with what is known of the function of the particular proteins, and suggest working hypotheses. (+info)
(4/858) Simulating complex traits influenced by genes with fuzzy-valued effects in pedigreed populations.
MOTIVATION: Methods involving fuzzy theory have been rarely applied to genetics. We present an open platform for experimentation with fuzzy numbers as a tool to represent imprecise phenotypes in genetic modeling. RESULTS: A C++ library for simulation of genetic information transmission is introduced. The study of genetic linkage was its first goal, though a design so general as possible has been meant. Fuzzy-valued phenotypes are handled by means of fuzzy numbers. AVAILABILITY: ftp://carleos.etsiig.uniovi.es/pub/falin ftp://fisher.ciencias.uniovi.es/pub/falin ftp://bellman.ciencias.uniovi.es/pub/falin Licensed under the GNU General Public License version 2 (see http://www.gnu.org/licenses/gpl.html). (+info)
(5/858) Genetic biases for showy males: are some genetic systems especially conducive to sexual selection?
Male secondary sexual characters (conspicuous ornaments, signals, colors) are among nature's most striking features. Yet, it is unclear why certain groups of organisms are more likely than others to evolve these traits. One explanation for such taxonomic biases is that some genetic systems may be especially conducive to sexual selection. Here, we present theory and simulation results demonstrating that rare alleles encoding either male ornaments or female preferences for those ornaments are better protected against random loss in species with ZZZW or ZZZO sex chromosome systems (male homogamety) than in species with XXXY or XXXO systems (male heterogamety). Moreover, this protection is much stronger in diploid than haplodiploid species. We also present empirical data showing that male secondary sexual characters are better developed in diploid than haplodiploid species and in diploid species with male homogamety than in those with male heterogamety. Thus, taxonomic biases for showy males may stem from differences in sex chromosome systems. (+info)
(6/858) Inheritance of a novel flaccid mutant in Capsicum annuum.
A mutant that causes a novel flaccidity phenotype in bell pepper (Capsicum annuum L.) was generated by treating seeds with ethyl methanesulfonate (EMS). Inheritance studies indicated that the mutant was controlled by a single recessive gene. It is proposed that the gene designation representing this mutation be flc (flaccid). The mutation may be useful for investigations of the genetic basis for turgor maintenance and drought stress physiology. (+info)
(7/858) A family-based test for correlation between gene expression and trait values.
Advances in microarray technology have made it attractive to combine information on clinical traits, marker genotypes, and comprehensive gene expression from family studies to dissect complex disease genetics. Without accounting for family structure, methods that test for association between a trait and gene-expression levels can be misleading. We demonstrate that the standard unstratified test based on Pearson's correlation coefficient can produce spurious results when applied to family data, and we present a stratified family expression association test (FEXAT). We illustrate the utility of the FEXAT via simulation and an application to gene-expression data from lymphoblastoid cell lines from four CEPH families. The FEXAT has a smaller estimated false-discovery rate than the standard test when within-family correlations are of interest, and it detects biologically plausible correlations between beta catenin and genes in the WNT-activation pathway in humans that the standard test does not. (+info)
(8/858) Consistency of genetic inheritance mode and heritability patterns of triglyceride vs. high density lipoprotein cholesterol ratio in two Taiwanese family samples.
BACKGROUND: Triglyceride/HDL cholesterol ratio (TG/HDL-C) is considered as a risk factor for cardiovascular events. Genetic components were important in controlling the variation in western countries. But the mode of inheritance and family aggregation patterns were still unknown among Asian-Pacific countries. This study, based on families recruited from community and hospital, is aimed to investigate the mode of inheritance, heritability and shared environmental factors in controlling TG/HDL-C. RESULTS: Two populations, one from community-based families (n = 988, 894 parent-offspring and 453 sibling pairs) and the other from hospital-based families (n = 1313, 76 parent-offspring and 52 sibling pairs) were sampled. The population in hospital-based families had higher mean age values than community-based families (54.7 vs. 34.0). Logarithmic transformed TG/ HDL-C values, after adjusted by age, gender and body mass index, were for genetic analyses. Significant parent-offspring and sibling correlations were also found in both samples. The parent-offspring correlation coefficient was higher in the hospital-based families than in the community-based families. Genetic heritability was higher in community-based families (0.338 +/- 0.114, p = 0.002), but the common shared environmental factor was higher in hospital-based families (0.203 +/- 0.042, p < 0.001). Commingling analyses showed that more than one-component distribution models were the best-fit models to explain the variance in both populations. Complex segregation analysis by regressive models revealed that in both samples the best-fit model of TG/HDL-C was the model of environmental effects plus familial correlation, in which significant parent-offspring and sibling correlations were demonstrated. Models of major gene effects were rejected in both samples. CONCLUSION: Variations of TG/HDL-C in the normal ranges were likely to be influenced by multiple factors, including environmental and genetic components. Higher genetic factors were proved in younger community-based families than in older hospital-based families. (+info)