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Allelic Combinations (allelic + combination)
Selected AbstractsMutation spectrum of Meckel syndrome genes: one group of syndromes or several distinct groups?,HUMAN MUTATION, Issue 8 2009Jonna Tallila Abstract Meckel syndrome (MKS) is a lethal malformation syndrome that belongs to the group of disorders that are associated with primary cilia dysfunction. Total of five genes are known to be involved in the molecular background of MKS. Here we have systematically analyzed all these genes in a total of 29 MKS families. Seven of the families were Finnish and the rest originated from elsewhere in Europe. We found 12 novel mutations in 13 families. Mutations in the MKS genes are also found in other syndromes and it seems reasonable to assume that there is a correlation between the syndromes and the mutations. To obtain some supportive information, we collected all the previously published mutations in the genes to see whether the different syndromes are dictated by the nature of the mutations. Based on this study, mutations play a role in the clinical phenotype, given that the same allelic combination of mutations has never been reported in two clinically distinct syndromes. © 2009 Wiley-Liss, Inc. [source] Perceptual considerations in the use of colored photographic and video stimuli to study nonhuman primate behaviorAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2006Corri Waitt Abstract The use of photographs, slides, computerized images, and video to study behavior is increasingly being employed in nonhuman primates. However, since these mediums have been designed to simulate natural coloration for normal trichromatic human vision, they can fail to reproduce color in meaningful and accurate ways for viewers with different visual systems. Given the range of color perception that exists both across and within different species, it is necessary to consider this variation in order to discern the suitability of these mediums for experimental use. Because of the high degree of visual similarity among humans, Old World monkeys, and apes, the use of photographic and video stimuli should be acceptable in terms of replicating naturalistic coloration and making noticeable color manipulations. However, among New World primates and prosimians, there exists a considerable degree of variation in color perceptual abilities depending on the species, sex, and allelic combination of the animals involved. Therefore, the use of these mediums to study behavior is problematic for these species, and should be done with caution. Am. J. Primatol. 68:1054,1067, 2006. © 2006 Wiley-Liss, Inc. [source] Haplotypes of the Human RET Proto-oncogene Associated with Hirschsprung Disease in the Italian Population Derive from a Single Ancestral Combination of AllelesANNALS OF HUMAN GENETICS, Issue 1 2006F. Lantieri Summary The RET proto-oncogene is the major gene involved in the complex genetics of Hirschsprung disease (HSCR), or aganglionic megacolon, showing causative loss-of-function mutations in 15,30% of the sporadic cases. Several RET polymorphisms and haplotypes have been described in association with the disease, suggesting a role for this gene in HSCR predisposition, also in the absence of mutations in the coding region. Finally, the presence of a functional variant in intron 1 has repeatedly been proposed to explain such findings. Here we report a case-control study conducted on 97 Italian HSCR sporadic patients and 85 population matched controls, using 13 RET polymorphisms distributed throughout the gene, from the basal promoter to the 3,UTR. Linkage disequilibrium and haplotype analyses have shown increased recombination between the 5, and 3, portions of the gene and an over-representation, in the cases studied, of two haplotypes sharing a common allelic combination that extends from the promoter up to intron 5. We propose that these two disease-associated haplotypes derive from a single founding locus, extending up to intron 19 and successively rearranged in correspondence with a high recombination rate region located between the proximal and distal portions of the gene. Our results suggests the possibility that a common HSCR predisposing variant, in linkage disequilibrium with such haplotypes, is located further downstream than the previously suggested interval encompassing intron 1. [source] The Characterization and Geographical Distribution of the Genes Responsible for Vernalization Requirement in Chinese Bread WheatJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Qing-Ming Sun Abstract The frequency and distribution of the major vernalization requirement genes and their effects on growth habits were studied. Of the 551 bread wheat genotypes tested, seven allelic combinations of the three Vrn-1 genes were found to be responsible for the spring habit, three for the facultative habit and one for the winter habit. The three Vrn-1 genes behaved additively with the dominant allele of Vrn-A1 exerting the strongest effect. The allele combinations of the facultative genotypes and the discovery of spring genotypes with "winter" allele of Vrn-1 implied the presence of as yet unidentified alleles/genes for vernalization response. The dominant alleles of the three Vrn-1 genes were found in all ten ecological regions where wheat is cultivated in China, with Vrn-D1 as the most common allele in nine and Vrn-A1 in one. The combination of vrn-A1vrn-B1Vrn-D1 was the predominant genotype in seven of the regions. Compared with landraces, improved varieties contain a higher proportion of the spring type. This was attributed by a higher frequency of the dominant Vrn-A1 and Vrn-B1 alleles in the latter. Correlations between Vrn-1 allelic constitutions and heading date, spike length, plant type as well as cold tolerance were established. [source] The genetic architecture of disease resistance in plants and the maintenance of recombination by parasitesMOLECULAR ECOLOGY, Issue 1 2001Paula X. Kover Abstract Parasites represent strong selection on host populations because they are ubiquitous and can drastically reduce host fitness. It has been hypothesized that parasite selection could explain the widespread occurrence of recombination because it is a coevolving force that favours new genetic combinations in the host. A review of deterministic models for the maintenance of recombination reveals that for recombination to be favoured, multiple genes that interact with each other must be under selection. To evaluate whether parasite selection can explain the maintenance of recombination, we review 85 studies that investigated the genetic architecture of plant disease resistance and discuss whether they conform to the requirements that emerge from theoretical models. General characteristics of disease resistance in plants and problems in evaluating resistance experimentally are also discussed. We found strong evidence that disease resistance in plants is determined by multiple loci. Furthermore, in most cases where loci were tested for interactions, epistasis between loci that affect resistance was found. However, we found weak support for the idea that specific allelic combinations determine resistance to different host genotypes and there was little data on whether epistasis between resistance genes is negative or positive. Thus, the current data indicate that it is possible that parasite selection can favour recombination, but more studies in natural populations that specifically address the nature of the interactions between resistance genes are necessary. The data summarized here suggest that disease resistance is a complex trait and that environmental effects and fitness trade-offs should be considered in future models of the coevolutionary dynamics of host and parasites. [source] Quantitative trait loci and epistatic interactions in barley conferring resistance to net type net blotch (Pyrenophora teres f. teres) isolatesPLANT BREEDING, Issue 4 2010S. Gupta With 2 figures and 5 tables Abstract Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, with significant yield reduction. This trait is important in selection along with other traits of quality and agronomic value. Two-hundred doubled-haploid lines were generated through anther culture from a cross between ,Pompadour' and ,Stirling'. Quantitative trait loci (QTL) were identified against five isolates of Pyrenophora teres f. teres, which represent virulences across Australia. QTL were mapped on chromosomes 3H and 6H using simple sequence repeat (SSR) markers. The resistance locus on 6H was detected with all isolates while the 3H locus was detected with two isolates. The 6H QTL from ,Pompadour' contributed resistance to isolates 97NB1, 95NB100 and NB81, whereas 6H QTL from ,Stirling' contributed resistance to isolates NB50 and NB52B. The 3H QTL from ,Pompadour' contributed resistance to NB50 and NB52B. Significant epistatic interactions were detected between QTL on 3H and 6H. These resistance QTL are a useful resource and identifying closely linked SSR markers with allelic combinations will facilitate in marker-assisted selection to develop NTNB resistant breeding lines. [source] Prospects for molecular breeding of barleyANNALS OF APPLIED BIOLOGY, Issue 1 2003W T B THOMAS Summary Data from UK Recommended List Trials showed that the introduction of new cultivars of spring and winter barley has maintained a significant increase in yield over time, whereas there has been no significant improvement in hot water extract, the major determinant of good malting quality, in either crop. Commercial barley breeding is based upon phenotypic selection, and the introduction of molecular breeding methods must either increase the rate of advance, or offer an improvement in the cost-effectiveness of breeding programmes. Molecular breeding can be applied to either single gene or polygenic characters but is not widely used in commercial barley breeding, other than as a marker for resistance to the Barley Yellow Mosaic Virus complex. There are many reports of potential targets for use in molecular breeding but the few validation studies that have been carried out to date are disappointing. Results from genomics studies are likely to lead to the identification of key candidate genes, which can be associated with economically important characters through co-location on certain chromosomal regions. Associations between candidate gene sequence haplotypes and phenotypic characteristics is expected to identify allelic combinations, which are most frequently observed in successful cultivars, that can be used in molecular breeding of barley on a commercial scale. [source] | ||||||||||