Major Genes (major + gene)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Absence of residual effects of a defeated resistance gene in poplar

FOREST PATHOLOGY, Issue 2 2003
K.-S. Woo
Summary In a few plant pathosystems, defeated major genes have been shown to contribute to partial resistance to disease. This hypothesis has never been tested before in a forest tree, but pathogenic variation associated with recent hybridization in poplar rust in the Pacific northwest provided an opportunity. An F2 progeny of 256 poplar clones in the field near Corvallis, Oregon, USA, has been monitored for rust severity and infection type since the advent of the new hybrid rust, Melampsora × columbiana, in the mid-1990s. All 256 clones displayed a susceptible infection type in 1997 and again in 2000, and yet variation in uredinial density (i.e. partial resistance) was still observed. To determine which clones possessed a defeated resistance gene, a greenhouse inoculation was performed with an isolate of M. medusae, one of the parents of M. × columbiana. Clones that would have been resistant to M. medusae, prior to the advent of M. × columbiana, were thus identified. The inoculation resulted in a 1 : 1 segregation (,2=0.772; p=0.38) for resistance, indicating the presence of a major gene. However, the F2 clones possessing the defeated resistance gene displayed the same level of partial resistance in the field in both 1997 and 2000 as their full siblings lacking the gene. Résumé Chez quelques pathosystèmes végétaux, il a été montré que le contournement de gènes majeurs de résistance contribue à une résistance partielle envers la maladie. Cette hypothèse n'a encore jamais été testée chez un arbre forestier, mais le changement de pouvoir pathogène associéà l'hybridation récente de la rouille du peuplier dans le nord-ouest des USA en a fourni l'occasion. Une descendance F2 de 256 clones de peuplier a été suivie au champ près de Corvallis, Oregon, USA, pour la gravité de la rouille et le type d'infection, depuis l'apparition du nouvel hybride Melampsora x columbiana, dans les années 1990. Tous les 256 clones se sont montrés sensibles en 1997 et à nouveau en 2000, et une variation dans la densité des urédies (résistance partielle) a aussi été observée. Pour déterminer quels clones présentaient une résistance contournée, des inoculations ont été réalisées en serre avec un isolat de Melampsora medusae originaire du Kentucky. Des clones qui étaient résistants àM. medusae avant l'apparition de M. x columbiana ont ainsi été identifiés. Les inoculations ont abouti à une ségrégation 1 :1 (,2 = 0,772; P = 0,38) pour la résistance, ce qui indique la présence d'un gène majeur. Cependant, les clones F2 possédant le gène de résistance contourné montraient le même niveau de résistance partielle au champ en 1997 et 2000 que leurs plein-frères qui n'avaient pas ce gène. Zusammenfassung Für einige Pflanzen-Pathosysteme wurde gezeigt, dass unwirksam gewordene Haupt-Resistenzgene immer noch zu einer teilweisen Resistenz beitragen. Für Waldbäume wurde diese Hypothese bisher nie überprüft. Dies wurde jetzt im pazifischen Nordwesten möglich, wo der Pappelrost nach einem rezenten Hybridisierungsereignis stark variierte. An den F2-Nachkommenschaften von 256 Pappelklonen, die unter Freilandbedingungen in der Nähe von Corvallis, Oregon, USA wuchsen, wurde nach dem Auftreten des neuen Hybridrostes (Melampsora × columbiana) ab ca. 1990 die Krankheitsintensität und der Infektionstyp registriert. Alle 256 Klone zeigten einen anfälligen Infektionstyp im Jahre 1997 und dann wieder im Jahre 2000. Dabei wurde eine Variation in der Urediendichte (d.h. partielle Resistenz) beobachtet. Um zu bestimmen, welche Klone ein unwirksam gewordenes Resistenzgen besitzen, wurden Inokulationen im Gewächshaus mit einem Isolat von M. medusae, einem Elter von M. × columbiana, durchgeführt. Damit wurden Klone identifiziert, die vor dem Auftreten von M. × columbiana gegen M. medusae resistent waren. Der Infektionsversuch führte zu einer 1:1 Segregation (,2=0,772; P=0,38) für die Resistenz, was auf das Vorliegen eines Hauptgens hinweist. Die F2-Klone, welche dieses überwundene Resistenzgen besitzen, zeigten jedoch unter Feldbedingungen in den Jahren 1997 und 2000 den gleichen Grad einer Teilresistenz wie ihre Vollgeschwister, welchen dieses Gen fehlt. [source]


Genetics of the apnea hypopnea index in Caucasians and African Americans: I. Segregation analysis

GENETIC EPIDEMIOLOGY, Issue 3 2002
Sarah G. Buxbaum
Abstract Differences in age of presentation and anatomic risk factors for obstructive sleep apnea (OSA) in Caucasians and African Americans suggest possible racial differences in the genetic underpinnings of the disorder. In this study, we assess transmission patterns in a Caucasian sample consisting of 177 families (N = 1,195) and in an African American sample consisting of 125 families (N = 720) for two variables: 1) apnea hypopnea index (AHI) log transformed and adjusted for age, and 2) AHI log transformed and adjusted for age and body mass index (BMI). We allowed for residual familial correlations and sex-specific means in all models. Analysis of the Caucasian sample showed transmission patterns consistent with that of a major gene that were stronger in the age-adjusted variable than in the age- and BMI-adjusted variable. However, in the African American families, adjusting for BMI in addition to age gave stronger evidence for segregation of a codominant gene with an allele frequency of 0.14, accounting for 35% of the total variance. These results provide support for an underlying genetic basis for OSA that in African Americans is independent of the contribution of BMI. Genet. Epidemiol. 22:243,253, 2002. © 2002 Wiley-Liss, Inc. [source]


Comparative linkage map development and identification of an autosomal locus for insensitive acetylcholinesterase-mediated insecticide resistance in Culex tritaeniorhynchus

INSECT MOLECULAR BIOLOGY, Issue 3 2001
A. Mori
Abstract A comparative linkage map for Culex tritaeniorhynchus was constructed based on restriction fragment length polymorphism markers using cDNAs from Aedes aegypti. Linear orders of marker loci in Cx. tritaeniorhynchus were identical to Culex pipiens wherein chromosomes 2 and 3 reflect whole-arm rearrangements compared to A. aegypti. However, the sex determination locus in Cx. tritaeniorhynchus maps to chromosome 3, in contrast to Cx. pipiens and Ae. aegypti where it is located on chromosome 1. Our results indicate that insensitive acetylcholinesterase (AChE)-mediated organophosphate resistance is controlled by a single major gene (AChER) on chromosome 2, while the AChE structural gene (Ace) is located on chromosome 1. No evidence for a second Ace gene was observed, even under very low stringency hybridization conditions. [source]


Very high conservation between Cyp6a2 from Drosophila melanogaster and its ortholog Cyp6a26 from D. simulans

INSECT SCIENCE, Issue 1 2007
SOPHIE TARÈS
Abstract Although Drosophila simulans is closely related to D. melanogaster, very few cytochrome P450 genes have been studied in this species until now. As Cyp6a2 from D. melanogaster is a major gene implicated in the detoxification of xenobiotic molecules, we decided to look for its ortholog in D. simulans. The isolated gene, Cyp6a26, presents structural characteristics very similar to those of Cyp6a2: an identical size of 1 590-bp comprising two exons separated by a 69-bp intron and a nucleotide sequence homology of 95%. Many putative transcriptionally important motifs were identified in the upstream DNAs of the two genes but only 16 elements are in common positions. Treatment of flies with phenobarbital leads to an increased production of Cyp6a26 mRNAs. The expression of Cyp6a26 mRNAs varies following developmental stages in the same manner as Cyp6a2. Immunohistochemistry experiments of phenobarbital-treated adult drosophila show that the spatial expression pattern of the two proteins is also conserved between the two species. All these data argue in favor of the conservation of the function of these homologous genes between the two Drosophila species. [source]


Implications of a fossil stickleback assemblage for Darwinian gradualism

JOURNAL OF FISH BIOLOGY, Issue 8 2009
M. A. Bell
Darwin postulated that a complete fossil record would contain numerous gradual transitions between ancestral and descendant species, but 150 years after publication of The Origin of Species, few such transitions have materialized. The fossil stickleback Gasterosteus doryssus and the deposit in which it occurs provide excellent conditions to detect such transitions. Abundant, well-preserved fossils occur in a stratigraphic setting with fine temporal resolution. The paleoecology of G. doryssus resembles the ecology of modern lakes that harbour the phenotypically similar three-spined stickleback Gasterosteus aculeatus. Gasterosteus aculeatus are primitively highly armoured, but G. doryssus comprised two contemporaneous biological species with relatively weak armour, including a near-shore, benthic feeder (benthic) and an offshore planktivore (limnetic). The benthic species expanded its range into the limnetic zone of the lake, where it apparently switched to planktivory and evolved reduced armour within c. 5000 years in response to directional selection. Although gradual evolution of mean phenotypes occurred, a single major gene caused much of evolutionary change of the pelvic skeleton. Thus, Darwin's expectation that transitions between species in the fossil record would be gradual was met at a fine time scale, but for pelvic structure, a well-studied trait, his expectation that gradual change would depend entirely on numerous, small, heritable differences among individuals was incorrect. [source]


TIMP-1 as candidate gene for embryo survival in two divergent lines selected for uterine capacity in rabbits,

MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 6 2006
Jordi Estellé
Abstract Selection on uterine capacity has been used in animal breeding as a way to improve the litter size. A divergent selection experiment for uterine capacity was performed in rabbits during ten generations. After the first generations of selection, large differences in number of implanted embryos were obtained between high and low lines. The major part of the differences between lines was due to embryo survival. A segregation analysis suggested the presence of a major gene affecting the reproductive traits. The objective of this work was to test the TIMP-1 gene as a candidate gene for embryo survival in rabbits since it stands up as a target for the investigation of reproductive problems in humans. We have analyzed the parental generation of a F2 cross which consists of 8 and 14 animals from the high and low uterine capacity lines, respectively. The rabbit TIMP-1 gene structure and sequence has been determined, including the proximal promoter region. Despite of the absence of polymorphism between lines in the screened regions (CDS, proximal promoter, exon 1, intron 1, and exon 2), a real-time RT-PCR quantification of the TIMP-1 mRNA in oviduct has shown significant differences between high and low lines at 62 hr of gestation, just when rabbit embryos are located in the oviduct, postulating TIMP-1 as an interesting candidate gene to be involved in the phenotypic differences between the two rabbit lines. Mol. Reprod. Dev. © 2006 Wiley-Liss, Inc. [source]


Inheritance of resistance of wheat to eyespot at the adult stage

PLANT BREEDING, Issue 6 2002
H. Muranty
Abstract Moderate resistance to eyespot was first incorporated in the variety Cappelle-Desprez (CD). Later the gene Pch1, which could confer a higher level of resistance, was introduced from Aegilops ventricosa. However Pch1 -carrying varieties can sustain significant eyespot-induced yield losses in severe attack situations. A strategy to further enhance the resistance of wheat is by pyramiding Pch1 and the genes for resistance in CD. The first requirement to achieve this is a better understanding of the genetics of resistance in CD. The resistance of the 21 Cappelle-Desprez (Bezostaya) disomic substitution lines was evaluated. Chromosome 7A was confirmed as carrying a major gene for resistance to eyespot at the seedling stage. However, this study demonstrates that this chromosome has no effects at the adult stage. Chromosome 5A was shown to carry a major gene for resistance to eyespot at the adult stage, which was stably expressed each year of testing. Chromosomes 1A and 2B had significant effects for only two years among four. [source]


Fine mapping of the FecL locus influencing prolificacy in Lacaune sheep

ANIMAL GENETICS, Issue 6 2009
L. Drouilhet
Summary In the Lacaune sheep population, two major loci influencing ovulation rate are segregating: FecX and FecL. The FecXL mutation is a non-conservative substitution (p.Cys53Tyr) in BMP15 that prevents the processing of the protein. Using a statistical approach, FecL has been shown to be an autosomal major gene. A full genome scan localized the FecL locus on sheep chromosome 11. Fine mapping reduced the interval containing FecL to markers BM17132 and FAM117A, corresponding to a synteny block of 1.1 megabases on human chromosome 17, which encompasses 20 genes. The expression of 16 genes from this interval was observed in tissues of the reproductive axis, but expression was not affected in homozygous FecLL females. In this interval, a unique haplotype was associated with the FecLL mutation. This particular haplotype could be predicted by the DLX3:c.*803A>G SNP in the 3, UTR sequence of the DLX3 gene. This SNP provided accurate classification of animals (99.5%) as carriers or non-carriers of the mutation and therefore maybe useful in marker assisted selection. A synergistic action of FecLL and FecXL mutations on both ovulation rate and litter size was demonstrated. Until now, all the Fec genes identified in sheep belong to the bone morphogenetic protein (BMP) system. Based on the human orthologous region, none of the 20 genes in the FecL region corresponds to known molecules in the BMP system. The identification of the FecLL mutation could lead to the discovery of a new pathway involved in the regulation of ovulation rate. [source]


MQScore_SNP Software for Multipoint Parametric Linkage Analysis of Quantitative Traits in Large Pedigrees

ANNALS OF HUMAN GENETICS, Issue 3 2010
Tatiana I. Axenovich
Summary We describe software for multipoint parametric linkage analysis of quantitative traits using information about SNP genotypes. A mixed model of major gene and polygene inheritance is implemented in this software. Implementation of several algorithms to avoid computational underflow and decrease running time permits application of our software to the analysis of very large pedigrees collected in human genetically isolated populations. We tested our software by performing linkage analysis of adult height in a large pedigree from a Dutch isolated population. Three significant and four suggestive loci were identified with the help of our programs, whereas variance-component-based linkage analysis, which requires the pedigree fragmentation, demonstrated only three suggestive peaks. The software package MQScore_SNP is available at http://mga.bionet.nsc.ru/soft/index.html. [source]


Haplotypes of the Human RET Proto-oncogene Associated with Hirschsprung Disease in the Italian Population Derive from a Single Ancestral Combination of Alleles

ANNALS OF HUMAN GENETICS, Issue 1 2006
F. 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]


A Maximum Likelihood-Based Method for Mining Major Genes Affecting a Quantitative Character

BIOMETRICS, Issue 3 2001
Rongling Wu
Summary. In this article, we present a maximum likelihood-based analytical approach for detecting a major gene of large effect on a quantitative trait in a progeny population derived from a mating design. Our analysis is based on a mixed genetic model specifying both major gene and background polygenic inheritance. The likelihood of the data is formulated by combining the information about population behaviors of the major gene during hybridization and its phenotypic distribution densities. The EM algorithm is implemented to obtain maximum likelihood estimates for population and quantitative genetic parameters of the major locus. This approach is applied to detect an overdominant gene governing stem volume growth in a factorial mating design of aspen trees. It is suggested that further molecular genetic research toward mapping single genes affecting aspen growth and production based on the same experimental data has a high probability of success. [source]


From epidemiology to lysyl oxidase like one (LOXL1) polymorphisms discovery: phenotyping and genotyping exfoliation syndrome and exfoliation glaucoma in Iceland

ACTA OPHTHALMOLOGICA, Issue 5 2009
Fridbert Jonasson
Abstract. The first Icelandic articles on exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) appeared some 35 years ago in 1974. Articles since then have included epidemiology, pedigree-based and twin-studies as well as investigations into XFG response to medical therapy and XFS/XFG genetics. All studies found XFS/XFG to be common in Iceland and to be age-related. The Reykjavik Eye Study (RES), a population-based epidemiological study, was first conducted in 1996. The RES found that XFS and XFG prevalence in patients aged 50 years and older was 11% and that XFS/XFG was more common in women than in men. These results were confirmed in 5- and 12-year incidence studies that also suggested that detailed characterization of the phenotype is important, including pupil dilation. In the RES, eyes with XFS were found to be clinically unilateral in about half of cases and to have higher mean intraocular pressure (IOP) than non-XFS eyes. However, XFS was not found to be associated with central corneal thickness, corneal curvature, anterior chamber depth, lens thickness, lens opacification or optic disc morphology. About 15% of persons with XFS had XFG, and XFG eyes had higher risk of developing visual impairment and blindness than eyes with primary open-angle glaucoma. The first genetic studies on Icelanders, conducted about 12 years ago, were linkage studies and were unsuccessful in discovering the genetics behind XFS/XFG. However, in 2007 a genome-wide association study in Iceland using more than 300 000 markers [single nucleotide polymorphisms (SNPs)] on a relatively small number of patients did discover that lysyl oxidase like 1 (LOXL1) on chromosome 15q24 is a major gene for XFS/XFG. These results have now largely been replicated world-wide. [source]


A region on equine chromosome 13 is linked to recurrent airway obstruction in horses

EQUINE VETERINARY JOURNAL, Issue 3 2007
U. JOST
Summary Reasons for study: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor , chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. Methods: The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood halfsib families. Based on a history of clinical signs (coughing, nasal discharge, abnormal breathing and poor performance), horses were classified in a horse owner assessed respiratory signs index (HOARSI 1,4: from healthy, mild, moderate to severe signs). Four microsatellite markers (AHT133, LEX041, VHL47, ASB037) were analysed in the offspring of Sire 1 (48 unaffected HOARSI 1 vs. 59 affected HOARSI 2,4) and Sire 2 (35 HOARSI 1 vs. 50 HOARSI 2,4), age ,7 years. Results: For both sires haplotypes could be established in the order AHT133-LEX047-VHL47-ASB37. The distances in this order were estimated to be 2.9, 0.9 and 2.3 centiMorgans, respectively. Haplotype association with mild to severe clinical signs of chronic lower airway disease (HOARSI 2,4) was significant in the offspring of Sire 1 (P = 0.026) but not significant for the offspring of Sire 2 (P = 0.32). Linkage analysis showed the ECA13q13 region containing IL4RA to be linked to equine chronic lower airway disease in one family (P<0.01), but not in the second family. Conclusions: This supports a genetic background for equine RAO and indicates that IL4RA is a candidate gene with possible locus heterogeneity for this disease. Potential relevance: Identification of major genes for RAO may provide a basis for breeding and individual prevention for this important disease. [source]


Absence of residual effects of a defeated resistance gene in poplar

FOREST PATHOLOGY, Issue 2 2003
K.-S. Woo
Summary In a few plant pathosystems, defeated major genes have been shown to contribute to partial resistance to disease. This hypothesis has never been tested before in a forest tree, but pathogenic variation associated with recent hybridization in poplar rust in the Pacific northwest provided an opportunity. An F2 progeny of 256 poplar clones in the field near Corvallis, Oregon, USA, has been monitored for rust severity and infection type since the advent of the new hybrid rust, Melampsora × columbiana, in the mid-1990s. All 256 clones displayed a susceptible infection type in 1997 and again in 2000, and yet variation in uredinial density (i.e. partial resistance) was still observed. To determine which clones possessed a defeated resistance gene, a greenhouse inoculation was performed with an isolate of M. medusae, one of the parents of M. × columbiana. Clones that would have been resistant to M. medusae, prior to the advent of M. × columbiana, were thus identified. The inoculation resulted in a 1 : 1 segregation (,2=0.772; p=0.38) for resistance, indicating the presence of a major gene. However, the F2 clones possessing the defeated resistance gene displayed the same level of partial resistance in the field in both 1997 and 2000 as their full siblings lacking the gene. Résumé Chez quelques pathosystèmes végétaux, il a été montré que le contournement de gènes majeurs de résistance contribue à une résistance partielle envers la maladie. Cette hypothèse n'a encore jamais été testée chez un arbre forestier, mais le changement de pouvoir pathogène associéà l'hybridation récente de la rouille du peuplier dans le nord-ouest des USA en a fourni l'occasion. Une descendance F2 de 256 clones de peuplier a été suivie au champ près de Corvallis, Oregon, USA, pour la gravité de la rouille et le type d'infection, depuis l'apparition du nouvel hybride Melampsora x columbiana, dans les années 1990. Tous les 256 clones se sont montrés sensibles en 1997 et à nouveau en 2000, et une variation dans la densité des urédies (résistance partielle) a aussi été observée. Pour déterminer quels clones présentaient une résistance contournée, des inoculations ont été réalisées en serre avec un isolat de Melampsora medusae originaire du Kentucky. Des clones qui étaient résistants àM. medusae avant l'apparition de M. x columbiana ont ainsi été identifiés. Les inoculations ont abouti à une ségrégation 1 :1 (,2 = 0,772; P = 0,38) pour la résistance, ce qui indique la présence d'un gène majeur. Cependant, les clones F2 possédant le gène de résistance contourné montraient le même niveau de résistance partielle au champ en 1997 et 2000 que leurs plein-frères qui n'avaient pas ce gène. Zusammenfassung Für einige Pflanzen-Pathosysteme wurde gezeigt, dass unwirksam gewordene Haupt-Resistenzgene immer noch zu einer teilweisen Resistenz beitragen. Für Waldbäume wurde diese Hypothese bisher nie überprüft. Dies wurde jetzt im pazifischen Nordwesten möglich, wo der Pappelrost nach einem rezenten Hybridisierungsereignis stark variierte. An den F2-Nachkommenschaften von 256 Pappelklonen, die unter Freilandbedingungen in der Nähe von Corvallis, Oregon, USA wuchsen, wurde nach dem Auftreten des neuen Hybridrostes (Melampsora × columbiana) ab ca. 1990 die Krankheitsintensität und der Infektionstyp registriert. Alle 256 Klone zeigten einen anfälligen Infektionstyp im Jahre 1997 und dann wieder im Jahre 2000. Dabei wurde eine Variation in der Urediendichte (d.h. partielle Resistenz) beobachtet. Um zu bestimmen, welche Klone ein unwirksam gewordenes Resistenzgen besitzen, wurden Inokulationen im Gewächshaus mit einem Isolat von M. medusae, einem Elter von M. × columbiana, durchgeführt. Damit wurden Klone identifiziert, die vor dem Auftreten von M. × columbiana gegen M. medusae resistent waren. Der Infektionsversuch führte zu einer 1:1 Segregation (,2=0,772; P=0,38) für die Resistenz, was auf das Vorliegen eines Hauptgens hinweist. Die F2-Klone, welche dieses überwundene Resistenzgen besitzen, zeigten jedoch unter Feldbedingungen in den Jahren 1997 und 2000 den gleichen Grad einer Teilresistenz wie ihre Vollgeschwister, welchen dieses Gen fehlt. [source]


Novel MLH1 mutations and a novel MSH2 polymorphism identified by SSCP and DHPLC in Portuguese HNPCC families,,

HUMAN MUTATION, Issue 5 2003
G. Isidro
Abstract Mismatch repair genes MSH2 and MLH1 are the two major genes implicated in hereditary nonpolyposis colorectal cancer. For the past years, we have successfully searched for mutations in both genes in affected Portuguese families, by SSCP and DNA sequencing analysis but because of the advantages that DHPLC offers, we have established conditions in our laboratory to use this new method. While screening for mutations by both methods, in 35 individuals belonging to HNPCC Portuguese families, 4 novel MLH1 mutations (c.307-1G>C; c.1023delG [p.R341fsX366]; c.2154_2155delCA [p.H718fsX721], c.2154_2155dupCA [p.I719fsX782]), an unclassified variant (c.-28A>T) and one silent MSH2 polymorphism (c.2766T>C) have been identified. © 2003 Wiley-Liss, Inc. [source]


Primitive complement system of invertebrates

IMMUNOLOGICAL REVIEWS, Issue 1 2004
Masaru Nonaka
Summary:, Most components of the human complement system have unmistakable domain architectures, making evolutionary tracing feasible. In contrast to the major genes of the adaptive immune system, which are present only in jawed vertebrates, complement component genes with unique domain structures are present not only in jawed vertebrates but also in jawless fish and non-vertebrate deuterostomes. Recent progress in genome analysis in several eukaryotes, occupying the phylogenetically critical positions, showed that most individual domains found in the complement components are metazoa specific, being found both in deuterostomes and in protostomes but not in yeast or plant. However, unique domain architecture of complement components is not present in protostomes, suggesting that the complement system has been established in the deuterostome lineage not by invention of new domains but by innovation of unique combination of the pre-existing domains. The recently assembled Ciona intestinalis draft genome contained the most modular complement genes, except for factor I. However, some possible C. intestinalis complement components show critical structural divergence from the mammalian counterparts, casting doubt on their mutual interaction. Thus, another integrative step seems to have been required to establish the modern complement system of higher vertebrates. [source]


Genetic aspects concerning drip loss and water-holding capacity of porcine meat

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2007
D. G. J. Jennen
Summary The amount and distribution of water inside the meat has a considerable influence on its properties. High losses of fluid in the form of drip may affect financial output, nutritional value, consumer appeal and/or technological properties of porcine meat. Therefore, a deeper insight into the traits water-holding capacity (WHC) and drip is favourable on behalf of producers, industry and consumers. Similar to most meat quality traits, WHC and drip loss (DRIP) are moderately heritable. The genetic correlation between these two traits is high. Correlation to other meat quality traits, such as pH value, cooking loss, reflectance, etc. is existent as predictable. Two major genes are known, RYR1 on chromosome 6 and RN on chromosome 15, to influence meat quality in general and WHC in particular. Furthermore, a number of candidate genes exist, e.g. phosphoglycerate mutase 2. Within the variety of quantitative trait loci (QTL) experiments, a number of QTL have been identified. QTL for DRIP and/or WHC have been found on chromosome 1, 2, 4, 5, 6, 11, 13, 14, 15, 18; for cooking loss on 7, 14 and18, and for pH value on nearly all chromosomes. Recently, a QTL study for meat quality and body composition traits in a Duroc,Pietrain (DUPI) resource population has been conducted at the University of Bonn, Germany. Four QTL for DRIP were identified on chromosomes 2, 3, 5 and 18. The QTL regions are in agreement with previously published QTL for this and other related traits. Further research and finemapping has begun and candidate genes located within the QTL regions are currently under investigation. Combination and comparison of results should lead to deeper insights in the genetic background of meat quality and DRIP. [source]


Frequency distribution of a Cys430Ser polymorphism in peroxisome proliferator-activated receptor-gamma coactivator-1 (PPARGC1) gene sequence in Chinese and Western pig breeds

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 1 2005
T. Kunej
Summary Identification of major genes, that genetically impact fat tissue formation is important for successful selection of lean animals with good meat quality. Because of its central role in fat cell differentiation and muscle fibre type determination, PPARGC1 is a potential candidate gene affecting fattening traits and pig meat quality. In this study, a T/A substitution at position 1378 (GenBank accession no. AY346131) in the porcine PPARGC1 gene causing a Cys430Ser amino acid substitution at position 430 was genotyped on a total of 239 animals, including 101 from seven Chinese and 138 from six Western pig breeds. Bayesian analysis revealed that the mean frequency of allele T (Cys) was 92.64 ± 4.82% in Chinese pigs, and 45.99 ± 4.13% in Western pigs. The 95% interval of the posterior mean frequency of allele T was 0.82,1.00 in Chinese pigs and 0.38,0.54 in Western pigs, indicating these two groups of pigs diverged at this locus during genetic evolution of the breed. Because marked differences in fat and lean tissue deposition exist between Western and Chinese pig breeds, this Cys430Ser exchange in the PPARGC1 gene deserves further evaluation to determine its phenotypic effect on fattening and carcass traits in commercial pig populations. [source]


Consistency of resistance to attack by the green spruce aphid (Elatobium abietinum Walker) in different ontogenetic stages of Sitka spruce

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2003
S. Harding
Abstract 1,The susceptibility of different genotypes of 29-year-old Sitka spruce to damage by the green spruce aphid, Elatobium abietinum, was investigated in a progeny trial where aphid damage on individual trees had previously been assessed twice in an earlier stage of ontogenetic development. The progeny trial comprised 14 open-pollinated families originating from a clonal seed orchard that had been established using mature spruce trees selected for aphid resistance. 2,Previous investigations had demonstrated that resistance was inherited by the offspring, and that differences in resistance between progenies of the individual orchard clones were highly significant. 3,Susceptibility to aphid attack was recorded as the percentage loss of previous year's needles. Differences in susceptibility recorded between the juvenile trees were found to persist after the trees had developed into the closed-canopy, sexually reproducing stage. Needle loss of the families was significantly less than that of the reference population of Sitka spruce. 4,Hybrids between Sitka spruce and white spruce were defoliated more heavily than pure Sitka spruce, and the difference increased with age. 5,Family heritability of resistance was estimated as 0.60 compared to 0.73 when the trees were assessed in the juvenile stage. The genetic correlation based on family means between damage in the juvenile and sexually reproducing stand was high (0.83), indicating a high consistency of resistance to the aphid over years and ontogenetic stages. 6,A skewed distribution of defoliation indicated that major genes are involved in the expression of resistance, and that the genetics behind resistance has a nonadditive component. [source]


Genotyping the Heading Date of Male-Sterile Rice Line II-32A

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2006
Jun-Feng Xu
Abstract II-32A, an elite male-sterile line of rice (Oryza sativa L.), has been widely used for the production of hybrid rice seed in China. Heading date in most combinations using II-32A shows transgressive inheritance or similarity to the latter parent, but the genotype of II-32A with respect to major genes for heading time is unknown. This limits the further exploitation of this sterile line in breeding and hybrid seed production. Using a number of major gene heading date isogenic lines and heading date QTL near-isogenic lines, we genetically analyzed II-32B under both long- and short-day conditions. We show that II-32B carries two photoperiod-sensitive genes, E1 and E3, a recessive late-heading gene, ef-1, and a photoperiod-sensitive allele, Se-1u. In addition we identified in II-32B a recessive inhibitor for E1 or Se-1n and other modified photoperiod-sensitive genes. The heading-date constitution of II-32A was determined to be E1e2E3Se-1uef-1i-Se-1. (Managing editor: Li-Hui Zhao) [source]


Virulence Frequences of Puccinia triticina in Germany and the European Regions of the Russian Federation

JOURNAL OF PHYTOPATHOLOGY, Issue 1 2007
V. Lind
Abstract From 2001 to 2003, leaf rust was collected in different regions of Germany and the Russian Federation to generate single spore isolates and to study the structure of the pathogen populations by analyses of virulence. The virulence of isolates was tested with 38 near-isogenic lines each carrying a different resistance gene. The analyses of variance revealed significant effects for the frequency of virulent isolates, the regions and most interactions with years and regions, but no significance was found for the effects of years. In Germany, an increase of virulence frequencies was detected for Lr1 and Lr2a while a decrease was found for Lr3a, Lr3bg and Lr3ka. Such clear trends did not occur in Russia which may be due to the great agroclimatic differences between regions. The variance of the frequency of virulent isolates was used to estimate adequate sample sizes for the analysis of regional populations of leaf rust. This procedure resulted in more reliable information about the dynamic processes within the pathogen populations. In 2002 and 2003, all pathotypes in Germany had a combined virulence to Lr1, Lr2a, Lr2b, Lr15, Lr17 and Lr20 supplemented by a few other genes. The complexity of virulence was lower in the most frequent pathotypes. In Russia virulence to the alleles at locus Lr3 was very common. Using detached leaf segments in Germany and Russia it turned out that the most virulent pathotypes carry 34 and 32 virulence genes, respectively. Virulence to Lr9, Lr19, Lr24 and Lr38 was rare or even absent. The use of major genes, not overcome by corresponding virulent pathotypes, may contribute to more durable types of resistance in case they are combined with genes having different effects, e.g. adult plant resistance. [source]


A novel form of resistance in rice to the angiosperm parasite Striga hermonthica

NEW PHYTOLOGIST, Issue 1 2006
A. L. Gurney
Summary ,,The root hemiparasitic weed Striga hermonthica is a serious constraint to grain production of economically important cereals in sub-Saharan Africa. Breeding for parasite resistance in cereals is widely recognized as the most sustainable form of long-term control; however, advances have been limited owing to a lack of cereal germplasm demonstrating postattachment resistance to Striga. ,,Here, we identify a cultivar of rice (Nipponbare) that exhibits strong postattachment resistance to S. hermonthica; the parasite penetrates the host root cortex but does not form parasite,host xylem,xylem connections. ,,In order to identify the genomic regions contributing to this resistance, a mapping population of backcross inbred lines between the resistant (Nipponbare) and susceptible (Kasalath) parents were evaluated for resistance to S. hermonthica. ,,Composite interval mapping located seven putative quantitative trait loci (QTL) explaining 31% of the overall phenotypic variance; a second, independent, screen confirmed four of these QTL. Relative to the parental lines, allelic substitutions at these QTL altered the phenotype by at least 0.5 of a phenotypic standard deviation. Thus, they should be regarded as major genes and are likely to be useful in breeding programmes to enhance host resistance. [source]


Orange, yellow and white-cream: inheritance of carotenoid-based colour in sunflower pollen

PLANT BIOLOGY, Issue 1 2010
M. Fambrini
Abstract Inheritance of pollen colour was studied in sunflower (Helianthus annuus L.) using three distinct pollen colour morphs: orange, yellow and white-cream. Orange is the most common colour of sunflower pollen, while the yellow morph is less frequent. These two types were observed in the inbred lines F11 and EF2L, respectively. White-cream pollen is a rare phenotype in nature, and was identified in a mutant, named white-cream pollen, recovered in the R2 generation of an in vitro regenerated plant. The F11 inbred line was used as starting material for in vitro regeneration. The carotenoid content of these three pollen morphs differed, and was extremely reduced in white-cream pollen. The phenotype of F1 populations obtained by reciprocal crosses revealed that the orange trait was dominant over both white-cream and yellow. Segregation of F2 populations of both crosses, orange × yellow and orange × white-cream, approached a 3:1 ratio, indicating the possibility of simple genetic control. By contrast, a complementation cross between the two lines with white-cream and yellow pollen produced F1 plants with orange pollen. The F2 populations of this cross-segregated as nine orange: four white-cream: four yellow. A model conforming to the involvement of two unlinked genes, here designated Y and O, can explain these results. Accessions with yellow pollen would have the genotype YYoo, the white-cream pollen mutant would have yyOO and the accession with orange pollen would have YYOO. Within F2 populations of the cross white-cream × yellow a new genotype, yyoo, with white-cream pollen was scored. The results of the cross yyoo × YYoo produced only F1 plants with yellow pollen, supporting a recessive epistatic model of inheritance between two loci. In this model, yy is epistatic on O and o. In F2 populations, the distributions of phenotypic classes suggested that the genetic control of carotenoid content is governed by major genes, with large effects segregating in a background of polygenic variation. These three pollen morphs can provide insight into the sequence in which genes act, as well into the biochemical pathway controlling carotenoid biosynthesis in anthers and the transfer of these different pigments into pollenkitt. [source]


Genetic counseling and "molecular" prenatal diagnosis of holoprosencephaly (HPE),

AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 1 2010
Sandra Mercier
Abstract Holoprosencephaly (HPE) is a structural anomaly of the developing brain in which the forebrain fails to divide into two separate hemispheres and ventricles. The poor prognosis in the most severe forms justifies the importance of genetic counseling in affected families. The genetic counseling requires a thorough clinical approach given the extreme variability of phenotype and etiology. The karyotype is an essential diagnostic tool. Since mutations in the four major genes (SHH, ZIC2, SIX3, and TGIF) have been identified in HPE patients, molecular study is performed routinely in nonsyndromic HPE. New molecular tools, such as array-CGH analysis, are now part of the diagnostic process. Prenatal diagnosis is based primarily on fetal imaging, but "molecular" prenatal diagnosis can be performed if a mutation has been previously identified in a proband. Interpretations of molecular diagnosis must be given with caution, given the lack of strict genotype,phenotype correlation, and should be offered in addition to fetal imaging, using ultrasound followed by fetal MRI. We report on our experience of 15 molecular prenatal diagnoses from chorionic villi or amniotic fluid sampling. In eight instances, we were able to reassure the parents after taking into account the absence of the mutation in the fetus, previously identified before in a parent and/or a proband. Fetal RMI was normal later in pregnancy, and no child had medical problems after birth. The mutation was found in the seven other cases: four children were born, either without brain malformation and asymptomatic, or had a less severe form than the index case. © 2010 Wiley-Liss, Inc. [source]


Tissue-dependent limited pleiotropy affects gene expression in barley

THE PLANT JOURNAL, Issue 2 2008
Elena Potokina
Summary Non-synonymous coding mutations in a gene change the resulting protein, no matter where it is expressed, but the effects of cis -regulatory mutations could be spatially or temporally limited , a phenomenon termed limited pleiotropy. Here, we report the genome-wide occurrence of limited pleiotropy of cis -regulatory mutations in barley (Hordeum vulgare L.) using Affymetrix analysis of 22 840 genes in a population of 139 doubled haploid lines derived from a cross between the cultivars Steptoe (St) and Morex (Mx). We identified robust cis -acting expression regulators that segregate as major genes in two successive ontogenetic stages: germinating embryo tissues and seedling leaves from the embryonic axis. We show that these polymorphisms may be consistent in both tissues or may cause a dramatic change in transcript abundance in one tissue but not in another. We also show that the parental allele that increases expression can vary with the tissue, suggesting nucleotide polymorphism in enhancer sequences. Because of the limited pleiotropy of cis -regulating mutations, the number of cis expression quantitative trait loci (cis -eQTLs) discovered by ,genetical genomics' is strongly affected by the particular tissue or developmental stage studied. Given that limited pleiotropy is a common feature of cis -regulatory mutations in barley, we predict that the phenomenon would be relevant to developmental and/or tissue-specific interactions across wide taxonomic boundaries in both plants and animals. [source]


A genome-wide scan for signatures of recent selection in Holstein cattle

ANIMAL GENETICS, Issue 4 2010
S. Qanbari
Summary The data from the newly available 50 K SNP chip was used for tagging the genome-wide footprints of positive selection in Holstein,Friesian cattle. For this purpose, we employed the recently described Extended Haplotype Homozygosity test, which detects selection by measuring the characteristics of haplotypes within a single population. To assess formally the significance of these results, we compared the combination of frequency and the Relative Extended Haplotype Homozygosity value of each core haplotype with equally frequent haplotypes across the genome. A subset of the putative regions showing the highest significance in the genome-wide EHH tests was mapped. We annotated genes to identify possible influence they have in beneficial traits by using the Gene Ontology database. A panel of genes, including FABP3, CLPN3, SPERT, HTR2A5, ABCE1, BMP4 and PTGER2, was detected, which overlapped with the most extreme P -values. This panel comprises some interesting candidate genes and QTL, representing a broad range of economically important traits such as milk yield and composition, as well as reproductive and behavioural traits. We also report high values of linkage disequilibrium and a slower decay of haplotype homozygosity for some candidate regions harbouring major genes related to dairy quality. The results of this study provide a genome-wide map of selection footprints in the Holstein genome, and can be used to better understand the mechanisms of selection in dairy cattle breeding. [source]


Genome-Wide Association Study Confirms SNPs in SNCA and the MAPT Region as Common Risk Factors for Parkinson Disease

ANNALS OF HUMAN GENETICS, Issue 2 2010
Todd L. Edwards
Summary Parkinson disease (PD) is a chronic neurodegenerative disorder with a cumulative prevalence of greater than one per thousand. To date three independent genome-wide association studies (GWAS) have investigated the genetic susceptibility to PD. These studies implicated several genes as PD risk loci with strong, but not genome-wide significant, associations. In this study, we combined data from two previously published GWAS of Caucasian subjects with our GWAS of 604 cases and 619 controls for a joint analysis with a combined sample size of 1752 cases and 1745 controls. SNPs in SNCA (rs2736990, p-value = 6.7 × 10,8; genome-wide adjusted p = 0.0109, odds ratio (OR) = 1.29 [95% CI: 1.17,1.42] G vs. A allele, population attributable risk percent (PAR%) = 12%) and the MAPT region (rs11012, p-value = 5.6 × 10,8; genome-wide adjusted p = 0.0079, OR = 0.70 [95% CI: 0.62,0.79] T vs. C allele, PAR%= 8%) were genome-wide significant. No other SNPs were genome-wide significant in this analysis. This study confirms that SNCA and the MAPT region are major genes whose common variants are influencing risk of PD. [source]


The influence of human leucocyte antigen (HLA) genes on autoimmune thyroid disease (AITD): results of studies in HLA-DR3 positive AITD families

CLINICAL ENDOCRINOLOGY, Issue 1 2002
Yoshiyuki Ban
Summary objective Population-based, case,control studies have consistently shown association of Graves' disease (GD) with human leucocyte antigen (HLA)-DR3 in Caucasian populations. HLA association studies in Hashimoto's thyroiditis (HT) have also suggested an association with DR3, as well as with other HLA alleles. In contrast, HLA linkage studies in autoimmune thyroid disease (AITD) have been largely negative. The aim of the present study was to investigate the role of HLA in AITD and to explain the observed associations, but lack of linkage, by examining only AITD families with the associated allele, DR3. patients We studied 99 probands (60 with GD and 39 with HT) from 99 multiplex, multigenerational Caucasian AITD families, and 135 age- and sex-matched Caucasian controls in association studies. In addition, a dataset of 34 Caucasian AITD families (out of the 99 families) with HLA-DR3 positive probands were analysed in linkage studies. design HLA typing was performed using the technique of group-specific polymerase chain reaction-amplification with restriction enzyme digestion. Whole genome screening was performed using the ABI microsatellite panels. For fine mapping of the HLA region, we used the following markers: D6S276, D6S464, D6S439, D6S273, tumour necrosis factor , and D6S1610. LOD scores were calculated using the LIPED and GeneHunter programs. results Case,control association analyses using the probands from our 99 Caucasian families showed an association of GD with DRB1*03 [P = 0·00032, relative risk (RR) = 3·4]. Linkage analysis for the HLA region in the 34 DR3 positive AITD families showed negative LOD scores throughout the region. The two-point LOD score at marker D6S273 (the closest to HLA-DRB1) was ,3·0, and the multipoint LOD score was ,7·6, demonstrating strong evidence against linkage to the HLA region in the subset of DR3 positive families. Whole genome screening in the subset of 34 DR3 positive families revealed one locus showing evidence for linkage to AITD: D3S1580 on chromosome 3q27 with a maximum two-point LOD score of 2·1. conclusions The HLA locus did not cosegregate with disease in DR3 positive families, suggesting that HLA genes are not major genes for AITD expression even within DR3 positive families; Hence, although HLA-DR3 was associated with GD in the probands, it was most likely a modulating gene and not causative; and, as the DR3 positive families showed evidence for linkage with D3S1580, it may imply that the DR3 gene modulated the effect of a susceptibility gene within the D3S1580 locus. [source]