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Genetic Variation (genetic + variation)
Kinds of Genetic Variation Selected AbstractsQUANTITATIVE GENETIC VARIATION IN POPULATIONS OF AMSINCKIA SPECTABILIS THAT DIFFER IN RATE OF SELF-FERTILIZATIONEVOLUTION, Issue 5 2009Magdalena P. Bartkowska Self-fertilization is expected to reduce genetic diversity within populations and consequently to limit adaptability to changing environments. Little is known, however, about the way the evolution of self-fertilization changes the amount or pattern of the components of genetic variation in natural populations. In this study, a reciprocal North Carolina II design and maximum-likelihood methods were implemented to investigate the genetic basis of variation for 15 floral and vegetative traits in four populations of the annual plant Amsinckia spectabilis (Boraginaceae) differing in mating system. Six variance components were estimated according to Cockerham and Weir's "bio" model c. Compared to the three partially selfing populations, we found significantly lower levels of nuclear variance for several traits in the nearly completely self-fertilizing population. Furthermore, for 11 of 15 traits we did not detect nuclear variation to be significantly greater than zero. We also found high maternal variance in one of the partially selfing populations for several traits, and little dominance variance in any population. These results are in agreement with the evolutionary dead-end hypothesis for highly self-fertilizing taxa. [source] PATTERNS OF PHENOTYPIC AND GENETIC VARIATION FOR THE PLASTICITY OF DIAPAUSE INCIDENCEEVOLUTION, Issue 7 2007Wade E. Winterhalter Phenotypic plasticity describes an organism's ability to produce multiple phenotypes in direct response to its environmental conditions. Over the past 15 years empiricists have found that this plasticity frequently exhibits geographic variation and often possesses a significant heritable genetic basis. However, few studies have examined both of these aspects of plasticity simultaneously. Here, we examined both the geographic and genetic variations of the plasticity for diapause incidence (the proportion of eggs that enter an arrested state of development capable of surviving over the winter) relative to temperatures and photoperiods associated with long and short season environments across six populations of the striped ground cricket, Allonemobius socius, using a half-sibling split brood quantitative genetic design. We found that plasticity, as measured by the slope of the reaction norm, was greater in the southern-low altitude region (where populations are bivoltine) relative to the southern-high and northern-low altitude regions (where populations are univoltine). However, the heritability of plasticity was only significantly different from zero in univoltine populations that experienced "intermediate" natal season lengths. These patterns suggest that selection may favor the plasticity of diapause incidence in bivoltine regions, but act against plasticity in regions in which populations are univoltine. Furthermore, our data suggest that under "intermediate" natal season length conditions, the interplay between local adaptation and gene flow may keep the plasticity of diapause incidence low (but still significant) while maintaining its genetic variation. As such, this study not only provides a novel observation into the geographic variation of phenotypic plasticity, but also provides much needed groundwork for tests of its adaptive significance. [source] EVOLUTIONARY ANALYSIS OF A KEY FLORAL TRAIT IN AQUILEGIA CANADENSIS (RANUNCULACEAE): GENETIC VARIATION IN HERKOGAMY AND ITS EFFECT ON THE MATING SYSTEMEVOLUTION, Issue 7 2007Christopher R. Herlihy The mating system of flowering plant populations evolves through selection on genetically based phenotypic variation in floral traits. The physical separation of anthers and stigmas within flowers (herkogamy) is expected to be an important target of selection to limit self-fertilization. We investigated the pattern of phenotypic and genetic variation in herkogamy and its effect of self-fertilization in a broad sample of natural populations of Aquilegia canadensis, a species that is highly selfing despite strong inbreeding depression. Within natural populations, plants exhibit substantial phenotypic variation in herkogamy caused primarily by variation in pistil length rather than stamen length. Compared to other floral traits, herkogamy is much more variable and a greater proportion of variation is distributed among rather than within individuals. We tested for a genetic component of this marked phenotypic variation by growing naturally pollinated seed families from five populations in a common greenhouse environment. For three populations, we detected a significant variation in herkogamy among families, and a positive regression between parental herkogamy measured in the field and progeny herkogamy in the greenhouse, suggesting that there is often genetic variation in herkogamy within natural populations. We estimated levels of self-fertilization for groups of flowers that differed in herkogamy and show that, as expected, herkogamy was associated with reduced selfing in 13 of 19 populations. In six of these populations, we performed floral emasculations to show that this decrease in selfing is due to decreased autogamy (within-flower selfing), the mode of selfing that herkogamy should most directly influence. Taken together, these results suggest that increased herkogamy should be selected to reduce the production of low-quality selfed seed. The combination of high selfing and substantial genetic variation for herkogamy in A. canadensis is enigmatic, and reconciling this observation will require a more integrated analysis of how herkogamy influences not only self-fertilization, but also patterns of outcross pollen import and export. [source] THE CHANGE IN QUANTITATIVE GENETIC VARIATION WITH INBREEDINGEVOLUTION, Issue 12 2006Josh Van Buskirk Abstract Inbreeding is known to reduce heterozygosity of neutral genetic markers, but its impact on quantitative genetic variation is debated. Theory predicts a linear decline in additive genetic variance (VA) with increasing inbreeding coefficient (F) when loci underlying the trait act additively, but a nonlinear hump-shaped relationship when dominance and epistasis are important. Predictions for heritability (h2) are similar, although the exact shape depends on the value of h2 in the absence of inbreeding. We located 22 published studies in which the level of genetic variation in [source] BALANCING SELECTION, RANDOM GENETIC DRIFT, AND GENETIC VARIATION AT THE MAJOR HISTOCOMPATIBILITY COMPLEX IN TWO WILD POPULATIONS OF GUPPIES (POECILIA RETICULATA)EVOLUTION, Issue 12 2006Cock van Oosterhout Abstract Our understanding of the evolution of genes of the major histocompatibility complex (MHC) is rapidly increasing, but there are still enigmatic questions remaining, particularly regarding the maintenance of high levels of MHC polymorphisms in small, isolated populations. Here, we analyze the genetic variation at eight microsatellite loci and sequence variation at exon 2 of the MHC class IIB (DAB) genes in two wild populations of the Trinidadian guppy, Poecilia reticulata. We compare the genetic variation of a small (Ne, 100) and relatively isolated upland population to that of its much larger (Ne, 2400) downstream counterpart. As predicted, microsatellite diversity in the upland population is significantly lower and highly differentiated from the population further downstream. Surprisingly, however, these guppy populations are not differentiated by MHC genetic variation and show very similar levels of allelic richness. Computer simulations indicate that the observed level of genetic variation can be maintained with overdominant selection acting at three DAB loci. The selection coefficients differ dramatically between the upland (s 0.2) and lowland (s, 0.01) populations. Parasitological analysis on wild-caught fish shows that parasite load is significantly higher on upland than on lowland fish, which suggests that large differences in selection intensity may indeed exist between populations. Based on the infection intensity, a substantial proportion of the upland fish would have suffered direct or indirect fitness consequences as a result of their high parasite loads. Selection by parasites plays a particularly important role in the evolution of guppies in the upland habitat, which has resulted in high levels of MHC diversity being maintained in this population despite considerable genetic drift. [source] FROM MICRO- TO MACROEVOLUTION THROUGH QUANTITATIVE GENETIC VARIATION: POSITIVE EVIDENCE FROM FIELD CRICKETSEVOLUTION, Issue 10 2004Mattieu Bégin Abstract . -Quantitative genetics has been introduced to evolutionary biologists with the suggestion that microevolution could be directly linked to macroevolutionary patterns using, among other parameters, the additive genetic variance/ covariance matrix (G) which is a statistical representation of genetic constraints to evolution. However, little is known concerning the rate and pattern of evolution of G in nature, and it is uncertain whether the constraining effect of G is important over evolutionary time scales. To address these issues, seven species of field crickets from the genera Gryllus and Teleogryllus were reared in the laboratory, and quantitative genetic parameters for morphological traits were estimated from each of them using a nested full-sibling family design. We used three statistical approaches (T method, Flury hierarchy, and Mantel test) to compare G matrices or genetic correlation matrices in a phylogenetic framework. Results showed that G matrices were generally similar across species, with occasional differences between some species. We suggest that G has evolved at a low rate, a conclusion strengthened by the consideration that part of the observed across-species variation in G can be explained by the effect of a genotype by environment interaction. The observed pattern of G matrix variation between species could not be predicted by either morphological trait values or phylogeny. The constraint hypothesis was tested by comparing the multivariate orientation of the reconstructed ancestral G matrix to the orientation of the across-species divergence matrix (D matrix, based on mean trait values). The D matrix mainly revealed divergence in size and, to a much smaller extent, in a shape component related to the ovipositor length. This pattern of species divergence was found to be predictable from the ancestral G matrix in agreement with the expectation of the constraint hypothesis. Overall, these results suggest that the G matrix seems to have an influence on species divergence, and that macroevolution can be predicted, at least qualitatively, from quantitative genetic theory. Alternative explanations are discussed. [source] GENETIC VARIATION IN MALE EFFECTS ON FEMALE REPRODUCTION AND THE GENETIC COVARIANCE BETWEEN THE SEXESEVOLUTION, Issue 6 2003MARY ELLEN CZESAK Abstract., Males of many insect species increase the fecundity and/or egg size of their mates through the amount or composition of their nuptial gifts or ejaculate. The genetic bases of such male effects on fecundity or egg size are generally unknown, and thus their ability to evolve remains speculative. Likewise, the genetic relationship between male and female investment into reproduction in dioecious species, which is expected to be positive if effects on fecundity are controlled by at least some of the same genes in males and females, is also unknown. Males of the seed beetle Stator limbatus contribute large ejaculates to females during mating, and the amount of donated ejaculate is positively correlated with male body mass. Females mated to large males lay more eggs in their lifetime than females mated to small males. We describe an experiment in which we quantify genetic variation in the number of eggs sired by males (mated to a single female) and found that a significant proportion of the phenotypic variance in the number of eggs sired by males was explained by their genotype. Additionally, the number of eggs sired by a male was highly positively genetically correlated with his body mass. The between-sex genetic correlation, that is, the genetic correlation between the number of eggs sired by males and the number of eggs laid by females, was highly positive when eggs were laid on Acacia greggii seeds. This indicates that males that sire many eggs have sisters that lay many eggs. Thus, some of the genes that control male ejaculate size (or some other fecundity-enhancing factor) when expressed in males appear to control fecundity when expressed in females. We found no significant interaction between male and female genotype on fecundity. [source] PATHOGEN RESISTANCE AND GENETIC VARIATION AT MHC LOCIEVOLUTION, Issue 10 2002Philip W. Hedrick Abstract., Balancing selection in the form of heterozygote advantage, frequency-dependent selection, or selection that varies in time and/or space, has been proposed to explain the high variation at major histocompatibility complex (MHC) genes. Here the effect of variation of the presence and absence of pathogens over time on genetic variation at multiallelic loci is examined. In the basic model, resistance to each pathogen is conferred by a given allele, and this allele is assumed to be dominant. Given that s is the selective disadvantage for homozygotes (and heterozygotes) without the resistance allele and the proportion of generations, which a pathogen is present, is e, fitnesses for homozygotes become (1 ,s)(n-1)e and the fitnesses for heterozygotes become (1 ,s)(n-2)e, where n is the number of alleles. In this situation, the conditions for a stable, multiallelic polymorphism are met even though there is no intrinsic heterozygote advantage. The distribution of allele frequencies and consequently heterozygosity are a function of the autocorrelation of the presence of the pathogen in subsequent generations. When there is a positive autocorrelation over generations, the observed heterozygosity is reduced. In addition, the effects of lower levels of selection and dominance and the influence of genetic drift were examined. These effects were compared to the observed heterozygosity for two MHC genes in several South American Indian samples. Overall, resistance conferred by specific alleles to temporally variable pathogens may contribute to the observed polymorphism at MHC genes and other similar host defense loci. [source] POSTGLACIAL DISPERSAL OF THE EUROPEAN RABBIT (ORYCTOLAGUS CUNICULUS) ON THE IBERIAN PENINSULA RECONSTRUCTED FROM NESTED CLADE AND MISMATCH ANALYSES OF MITOCHONDRIAL DNA GENETIC VARIATIONEVOLUTION, Issue 4 2002Madalena Branco Abstract Nested clade analysis was applied to cytochrome b restriction site data previously obtained on 20 natural populations of the European rabbit across the Iberian Peninsula to test the hypothesis of postglacial dispersal from two main refugia, one in the northeast and the other in the southwest. Apart from historical fragmentation that resulted in geographic discontinuity of two distinct mitochondrial DNA (mtDNA) clades A and B, patterns of haplotype genetic variability have been shaped mostly by restricted gene flow via isolation by distance. The distribution of tip versus interior haplotypes suggests that dispersal occurred from both the southwestern and northeastern groups. Dispersal from the southwest had a north and northwest direction, whereas from the northeast it had mostly a western and southern orientation, with subsequent overlap in a southeastern-northwestern axis across the Iberian Peninsula. The analysis of the pairwise mismatch distribution of a 179,181-bp fragment of the mtDNA control region, for seven of those populations, further supports the idea that major patterns of dispersal were in the direction of central Iberia. Additionally, rabbit populations do not show signs of any significant loss of genetic diversity in the recent past, implying that they maintained large population sizes and structure throughout the ice ages. This is congruent with the fact that the Iberian Peninsula was itself a glacial refugium during Quaternary ice ages. Nonetheless, climatic oscillations of this period, although certainly milder than in northern Europe, were sufficient to affect the range distributions of Iberian organisms. [source] THE HISTORICAL BIOGEOGRAPHY OF TWO CARIBBEAN BUTTERFLIES (LEPIDOPTERA: HELICONIIDAE) AS INFERRED FROM GENETIC VARIATION AT MULTIPLE LOCIEVOLUTION, Issue 3 2002Neil Davies Abstract Mitochondrial DNA and allozyme variation was examined in populations of two Neotropical butterflies, Heliconius charithonia and Dryas iulia. On the mainland, both species showed evidence of considerable gene flow over huge distances. The island populations, however, revealed significant genetic divergence across some, but not all, ocean passages. Despite the phylogenetic relatedness and broadly similar ecologies of these two butterflies, their intraspecific biogeography clearly differed. Phylogenetic analyses of mitochondrial DNA sequences revealed that populations of D. iulia north of St. Vincent are monophyletic and were probably derived from South America. By contrast, the Jamaican subspecies of H. charithonia rendered West Indian H. charithonia polyphyletic with respect to the mainland populations; thus, H. charithonia seems to have colonized the Greater Antilles on at least two separate occasions from Central America. Colonization velocity does not correlate with subsequent levels of gene flow in either species. Even where range expansion seems to have been instantaneous on a geological timescale, significant allele frequency differences at allozyme loci demonstrate that gene flow is severely curtailed across narrow ocean passages. Stochastic extinction, rapid (re)colonization, but low gene flow probably explain why, in the same species, some islands support genetically distinct and nonexpanding populations, while nearby a single lineage is distributed across several islands. Despite the differences, some common biogeographic patterns were evident between these butterflies and other West Indian taxa; such congruence suggests that intraspecific evolution in the West Indies has been somewhat constrained by earth history events, such as changes in sea level. [source] GENETIC VARIATION OF KOGIA SPP.MARINE MAMMAL SCIENCE, Issue 4 2005WITH PRELIMINARY EVIDENCE FOR TWO SPECIES OF KOGIA SIMA Abstract Concordance between mitochondrial DNA (mtDNA) markers and morphologically based species identifications was examined for the two currently recognized Kogia species. We sequenced 406 base pairs of the control region and 398 base pairs of the cytochrome b gene from 108 Kogia breviceps and 47 K. sima samples. As expecred, the two sister species were reciprocally monophyletic to each other in phylogenetic reconstructions, but within K. sima, we unexpectedly observed another reciprocally monophyletic relationship. The two K. sima clades resolved were phylogeographically concordant with all of the haplotypes in one clade observed solely among specimens sampled from the Atlantic Ocean and with those in the other clade observed solely among specimens sampled from the Indo-Pacific Ocean. These apparently allopatric clades were observed in all phylogenetic reconstructions using the maximum parsimony, maximum likelihood, and neighborjoining algorithms, with the mtDNA gene sequences analyzed separately and combined. The nucleotide diversity for the combined gene sequence haplotypes of the two K. sima clades resolved in our analyses was 0.58% and 1.03% for the Atlantic and Indo-Pacific, respectively, whereas for the two recognized sister species, nucleotide diversity was 1.65% and 4.02% for K. breviceps and K. sima, respectively. The combined gene sequence haplotypes have accumulated 44 fixed base pair differences between the two K. sima clades compared to 20 fixed base pair differences between the two recognized sister species. Although our results are consistent with species-level differences between the two K. sima clades, recognition of a third Kogia species awaits supporting evidence that these two apparently allopatric clades represent reproductively isolated groups of animals. [source] Population Size, Genetic Variation, and Reproductive Success in a Rapidly Declining, Self-Incompatible Perennial (Arnica montana) in The NetherlandsCONSERVATION BIOLOGY, Issue 6 2000Sheila H. Luijten In 26 populations in The Netherlands we investigated the relationship between population size and genetic variation using allozyme markers. Genetic variation was low in A. montana ( He = 0.088). There were positive correlations between population size and the proportion of polymorphic loci, the number of effective alleles, and expected heterozygosity, but not with observed heterozygosity. There was a significantly positive correlation between population size and the inbreeding coefficient. Generally, small populations showed heterozygote excess, which decreased with increasing population size. Possibly, the heterozygous individuals in small populations are survivors from the formerly larger populations with relatively high fitness. The F statistics showed a moderately high level of differentiation among populations ( FST = 0.140 ± 0.02), implying a low level of gene flow. For three out of four allozyme loci, we found significant inbreeding ( FIS = 0.104 ± 0.03). Only 14 of 26 populations were in Hardy-Weinberg equilibrium at all four polymorphic loci. In a subset of 14 populations of various size, we investigated natural seed production and offspring fitness. Population size was positively correlated with seed set, seedling size, number of flowering stems and flowerheads, adult survival, and total relative fitness, but not with the number of florets per flowerhead, germination rate, or the proportion of germination. Offspring performance in the greenhouse was not associated with genetic diversity measured on their mothers in the field. We conclude that the fitness of small populations is significantly reduced, but that there is as yet no evidence that this was caused by inbreeding. Possibly, the self-incompatibility system of A. montana has been effective in reducing selfing rates and inbreeding depression. Resumen:Arnica montana es una especie de planta rara, en declinación rápida y autoincompatible. En 26 poblaciones de los Países Bajos investigamos la relación entre el tamaño poblacional y la variación genética mediante el uso de alozimas marcadoras. La variación genética fue baja en A. montana ( He = 0.088). Existió una correlación positiva entre el tamaño poblacional y la proporción de emplazamientos polimórficos, el número de alelos efectivos y la heterocigocidad esperada, pero no con la heterocigocidad observada. Existió una correlación positiva significativa entre el tamaño poblacional y el coeficiente de endogamia. Generalmente, las poblaciones pequeñas mostraron una heterocigocidad excesiva con disminuciones en el tamaño poblacional. Posiblemente, los individuos heterocigóticos de poblaciones pequeñas son sobrevivientes de poblaciones anteriormente grandes con una adaptabilidad relativamente alta. Las pruebas de F mostraron un nivel de diferenciación moderadamente alto entre poblaciones ( FST = 0.140 ± 0.02) lo que implica un nivel bajo de flujo de genes. Para tres de cuatro de los emplazamientos de alozimas encontramos una endogamia significativa ( FIS = 0.104 ± 0.03). Solamente 14 de las 26 poblaciones estuvieron en equilibrio Hardy-Weinberg para los cuatro emplazamientos polimórficos. En un subconjunto de 14 poblaciones de varios tamaños, investigamos la producción natural de semillas y la adaptabilidad de la descendencia. El tamaño poblacional estuvo positivamente correlacionado con el juego de semillas, el tamaño del almácigo, el número de tallos en flor y de inflorescencias, la supervivencia de adultos y la adaptabilidad total relativa, pero no con el número de flores por inflorescencia, la tasa de germinación ni la proporción de la germinación. El rendimiento de la descendencia en invernaderos no estuvo asociado con la diversidad genética medida en sus madres en el campo. Concluimos que la adaptabilidad de poblaciones pequeñas está significativamente reducida, pero no existe aún evidencia de que esto sea ocasionado por endogamia. Es posible que el sistema de autoincompatibilidad de A. montana haya sido efectivo en la reducción de tasas de autofecundación y depresión de la endogamia. [source] GOOD GIFTS FOR THE COMMON GOOD: Blood and Bioethics in the Market of Genetic ResearchCULTURAL ANTHROPOLOGY, Issue 3 2007DEEPA S. REDDY This article is based on ethnographic fieldwork conducted with the Indian community in Houston, as part of a NIH,NHGRI-sponsored ethics study and sample collection initiative entitled "Indian and Hindu Perspectives on Genetic Variation Research." At the heart of this research is one central exchange,blood samples donated for genetic research,that draws both the Indian community and a community of researchers into an encounter with bioethics. I consider the meanings that come to be associated with blood donation as it passes through various hands, agendas, and associated ethical filters on its way to the lab bench: how and why blood is solicited, how the giving and taking of blood is rationalized, how blood as material substance is alienated, processed, documented, and made available for the promised ends of basic science research. Examining corporeal substances and asking what sorts of gifts and problems these represent, I argue, sheds some light on two imbricated tensions expressed by a community of Indians, on the one hand, and of geneticists and basic science researchers, on the other hand: that gifts ought to be free (but are not), and that science ought to be pure (but is not). In this article, I explore how experiences of bioethics are variously shaped by the histories and habits of Indic giving, prior sample collection controversies, commitments to "good science" and the common "good of humanity," and negotiations of the sites where research findings circulate. [source] Genetic Variation for Penta D and Penta E in a Northeast Colombian Population (Department of Santander)JOURNAL OF FORENSIC SCIENCES, Issue 2 2006Clara Inés Vargas M.D., M.Sc. POPULATION: Department of Santander, Colombia (n=104). [source] Assessment of Genetic Variation Within Indian Mustard (Brassica juncea) Germplasm Using Random Amplified Polymorphic DNA MarkersJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2008Muhammad Ayub Khan Abstract Genetic diversity among 45 Indian mustard (Brassica juncea L.) genotypes comprising 37 germplasm collections, five advance breeding lines and three improved cultivars was investigated at the DNA level using the random amplified polymorphic DNA (RAPD) technique. Fifteen primers used generated a total of 92 RAPD fragments, of which 81 (88%) were polymorphic. Of these, 13 were unique to accession ,Pak85559'. Each primer produced four to nine amplified products with an average of 6.13 bands per primer. Based on pairwise comparisons of RAPD amplification products, Nei and Li's similarity coefficients were calculated to evaluate the relationships among the accessions. Pairwise similarity indices were higher among the oilseed accessions and cultivars showing narrow ranges of 0.77,0.99. An unweighted pair-group method with arithmetic averages cluster analysis based on these genetic similarities placed most of the collections and oilseed cultivars close to each other, showing a low level of polymorphism between the accessions used. However, the clusters formed by oilseed collections and cultivars were comparatively distinct from that of advanced breeding lines. Genetically, all of the accessions were classified into a few major groups and a number of individual accessions. Advanced breeding lines were relatively divergent from the rest of the accessions and formed independent clusters. Clustering of the accessions did not show any pattern of association between the RAPD markers and the collection sites. A low level of genetic variability of oilseed mustard was attributed to the selection for similar traits and horticultural uses. Perhaps close parentage of these accessions further contributed towards their little diversity. The study demonstrated that RAPD is a simple and fast technique to compare the genetic relationship and pattern of variation among the gene pool of this crop. [source] Genetic Variation of the Ghrelin Signaling System in Females With Severe Alcohol DependenceALCOHOLISM, Issue 9 2010Sara Landgren Introduction:, Central ghrelin signaling is required for the rewarding effects of alcohol in mice. Because ghrelin is implied in other addictive behaviors such as eating disorders and smoking, and because there is co-morbidity between these disorders and alcohol dependence, the ghrelin signaling system could be involved in mediating reward in general. Furthermore, in humans, single nucleotide polymorphisms (SNPs) and haplotypes of the pro-ghrelin gene (GHRL) and the ghrelin receptor gene (GHSR) have previously been associated with increased alcohol consumption and increased body weight. Known gender differences in plasma ghrelin levels prompted us to investigate genetic variation of the ghrelin signaling system in females with severe alcohol dependence (n = 113) and in a selected control sample of female low-consumers of alcohol from a large cohort study in southwest Sweden (n = 212). Methods:, Six tag SNPs in the GHRL (rs696217, rs3491141, rs4684677, rs35680, rs42451, and rs26802) and four tag SNPs in the GHSR (rs495225, rs2232165, rs572169, and rs2948694) were genotyped in all individuals. Results:, We found that one GHRL haplotype was associated with reports of paternal alcohol dependence as well as with reports of withdrawal symptoms in the female alcohol-dependent group. Associations with 2 GHSR haplotypes and smoking were also shown. One of these haplotypes was also negatively associated with BMI in controls, while another haplotype was associated with having the early-onset, more heredity-driven, type 2 form of alcohol dependence in the patient group. Conclusion:, Taken together, the genes encoding the ghrelin signaling system cannot be regarded as major susceptibility genes for female alcohol dependence, but is, however, involved in paternal heritability and may affect other reward- and energy-related factors such as smoking and BMI. [source] Use of RAPD and ISSR Markers in Detection of Genetic Variation and Population Structure among Fusarium oxysporum f. sp. ciceris Isolates on Chickpea in TurkeyJOURNAL OF PHYTOPATHOLOGY, Issue 3 2008H. Bayraktar Abstract Genetic variation among the isolates of Fusarium oxysporum f. sp. ciceris, the causal agent of chickpea wilt worldwide, was analysed using pathogenicity tests and molecular markers , random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) polymorphism. Hundred and eight isolates were obtained from diseased chickpea plants in 13 different provinces of Turkey, out of which 74 isolates were assessed using 30 arbitrary decamer primers and 20 ISSR primers. Unweighted pair-grouped method by arithmetic average cluster analysis of RAPD, ISSR and RAPD + ISSR datasets provided a substantially similar discrimination among Turkish isolates and divided into three major groups. Group 1, 2 and 3 consisted of 41, 18 and 15 isolates, respectively. These methods revealed a considerable genetic variation among Turkish isolates, but no correlation with regard to the clustering of isolates from different geographic regions. Analysis of molecular variance confirmed that most genetic variability resulted from the differences among isolates within regions. Our results also indicated that the low-genetic differentiation (FST) and high gene flow (Nm) among populations had a significant effect on the emergence and evolutionary development of F. oxysporum f. sp. ciceris. This is the first report on genetic diversity and population structure of F. oxysporum isolates on chickpea in Turkey. [source] Sources of Phenotypic and Genetic Variation for Seawater Growth in Five North American Atlantic Salmon, Salmo salar, StocksJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2010William R. Wolters In 2003, pedigreed families were obtained from two St. John's River sources, Penobscot River, Gaspè, and landlocked salmon stocks. Eyed eggs were disinfected upon arrival, and incubated in separate hatching jars. Fry were transferred prior to first feeding into individual 0.1-m3 tanks receiving 8 L/min of oxygen-saturated freshwater from a recirculating biological filtration system. At approximately 30 d after the initiation of feeding, fish densities were equalized to 250 fish/tank, fed 5% of the tank's total biomass in 3,4 daily feedings. When the fish were approximately 40 g, approximately 30 fish from each family were pit tagged and stocked communally into three replicated 10-m3 smolt tanks. Approximately 1 mo prior to stocking into sea cages for performance evaluations, evaluations of serum chloride levels and gill Na+, K+ -ATPase activity were measured on subsamples from all stocks in freshwater and following seawater challenge. Smolts were stocked into sea cages in June 2005, harvested in February 2007, and evaluated for carcass weight, sex, and stage of sexual maturity. Data were analyzed by the mixed model ANOVA to determine the random effects of sire and dam (sire), and the fixed effects of sex, salmon stock, ploidy level, and replicate smolt tank on carcass weight with smolt weight as a covariate. Sire and dam variance components were significantly different from zero, and the fixed effects of salmon stock, sex × stock interaction, and smolt weight at stocking were significant (P < 0.05). There were no significant differences among sexes, replicate smolt tank, or ploidy level for carcass weight. Overall, St. John's River fish had the fastest growth with a carcass weight >4.1 kg compared with the slowest growth in landlocked fish at 1.7 kg. Grilsing was also highest in St. John's River fish (ca. 4,6%) and lowest in Penobscot River fish (0%). The sire heritability for carcass weight calculated from the sire variance component using the mixed model ANOVA or MTDFREML was 0.26 ± 0.14. Data were used to calculate breeding values on captive sibling adult brood fish, and a line selected for carcass weight was spawned in the fall of 2007, and eggs from these fish were released to industry. [source] Genetic Variation and Differentiation Within a Natural Community of Five Oak Species (Quercus spp.)PLANT BIOLOGY, Issue 1 2007A. L. Curtu Abstract: Chloroplast DNA and two categories of nuclear markers - isozymes and microsatellites - were used to examine a very rich natural community of oaks (Quercus spp.) situated in west-central Romania. The community consists of five oak species: Q. robur, Q. petraea, Q. pubescens, and Q. frainetto - that are closely related -, and Q. cerris. A total of five chloroplast haplotypes was identified. Q. cerris was fixed for a single haplotype. The other four species shared the two most common haplotypes. One haplotype was confined to Q. robur and a very rare one was restricted to Q. petraea. Both types of nuclear markers revealed a larger genetic variation for Q. pubescens and Q. petraea than for Q. frainetto and Q. robur, although the differences between species are in most cases not significant. At the nuclear level, Q. cerris could be clearly separated from the other four oak species confirming the taxonomic classification. Regardless of the estimate used, the levels of polymorphism revealed by microsatellites were much higher than those based on isozymes. For the four closely related species the overall genetic differentiation was significant at both categories of nuclear markers. Several loci, such as Acp-C for isozymes, and ssrQpZAG36 and ssrQrZAG96 for microsatellites were very useful to discriminate among species. However, the level of differentiation varied markedly between pairs of species. The genetic affinities among the species may reflect different phylogenetic distances and/or different rates of recurrent gene flow at this site. [source] Genetic Variation in the Indoleamine 2,3-Dioxygenase Gene in Pre-eclampsiaAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2010Haruki Nishizawa Citation Nishizawa H, Kato T, Ota S, Nishiyama S, Pryor-Koishi K, Suzuki M, Tsutsumi M, Inagaki H, Kurahashi H, Udagawa Y. Genetic variation in the indoleamine 2,3-Dioxygenase gene in pre-eclampsia. Am J Reprod Immunol 2010; 64: 68,76 Problem, To investigate the contribution of genomic variations in the indoleamine 2,3-dioxygenase (IDO) gene to the onset of pre-eclampsia. Method of study, We examined sequence variations in the IDO1 gene using placental genomic DNA from 35 pre-eclamptic patients and 32 normotensive pregnant women. Results, A case,control study revealed that none of the common variants influences the risk of disease. Sequencing of each IDO1 exon in diseased subjects revealed rare variants. This variation, c.-147_150delGAAA, was located within the 5,-untranslated region of the IDO1 gene, and its homozygote was identified only in pre-eclamptic subjects. However, despite the low levels of IDO expression and enzyme activity in the c.-147_150delGAAA homozygote, reporter assays indicated that this variation does not affect gene expression. Conclusion, Our findings indicate that genetic alteration of fetal IDO gene does not appear to be a primary cause of pre-eclampsia. [source] Cholesteryl Ester Transfer Protein (CETP) Genetic Variation and Early Onset of Non-Fatal Myocardial InfarctionANNALS OF HUMAN GENETICS, Issue 6 2008V. Meiner Summary Although Cholesteryl Ester Transfer Protein (CETP) mediates the transfer of cholesteryl esters and triglycerides between lipoprotein particles and thus plays a crucial role in reverse cholesterol transport, the association of variations in the CETP gene with acute myocardial infarction (MI) remains unclear. In this study we examined whether common genetic variation in the CETP gene is related to early-onset non-fatal MI risk in a population-based case-control study from western Washington State. Genotyping for the CETP ,2708 G/A, ,971 A/G, ,629 A/C, Intron-I TaqI G/A and exon-14 A/G (I405V) SNPs was performed in 578 cases with first acute non-fatal MI and in 666 demographically similar controls, free of clinical cardiovascular disease, identified randomly from the community. In-person interviews and non-fasting blood specimens provided data on coronary heart disease risk factors. In men, there was little evidence for an association between single SNPs and MI risk, but in women the age- and race-adjusted OR was found to be significant in 4 out of the 5 CETP single variants. Haplotype analysis revealed two haplotypes associated with MI risk among men. As compared to men homozygous for the most common haplotype D (,2708 G, ,971 G, ,629 C, TaqI G and exon-14 A), the fully-adjusted multiplicative model identified haplotype G (,2708 G, ,971 A, ,629 A, TaqI G and exon-14 G) was associated with a 4.0-6.0-fold increased risk of MI for each additional copy; [95%CI 2.4,14.8] and haplotype B (,2708 G, ,971 G, ,629 A, TaqI A and exon-14 A) showed a significant decreased risk for early onset MI [OR = 0.18; 95%CI 0.04 , 0.75]. An evolutionary-based haplotype analysis indicated that the two haplotypes associated with the MI risk are most evolutionarily divergent from the other haplotypes. Variation at the CETP gene locus is associated with the risk of early-onset non-fatal MI. This association was found to be independent of HDL-C levels. These data and the sex-specific findings require confirmation in other populations. [source] Genetic Variation in the Paraoxonase-3 (PON3) Gene is Associated with Serum PON1 ActivityANNALS OF HUMAN GENETICS, Issue 1 2008Dharambir K. Sanghera Summary Low serum paraoxonase1 (PON1) activity determined by paraoxon substrate is associated with coronary heart disease (CHD), diabetes and systemic lupus erythematosus (SLE) risk. In this investigation, we have examined the role of genetic variation in the PON3 gene in relation to PON1 activity and SLE risk in a biracial sample comprising 377 SLE patients and 482 controls from US whites and blacks. We genotyped six PON3 tagging single nucleotide polymorphisms (tagSNPs) and examined their associations with PON1 activity, SLE risk, antiphopholipid autoantibodies (APA), lupus nephritis, carotid vascular disease, and inflammation. With the exception of PON1 activity, no other significant associations were found with PON3 SNPs. Multiple regression analysis including all six PON3 tagSNPs and PON1/Q192R and L55M SNPs revealed significant association of PON1 activity with 4 SNPs: PON3/A10340C (p < 0.0001), PON3/A2115T (p = 0.002), PON1/L55M (p < 0.0001) and PON1/Q192R (p < 0.0001). These four SNPs explained 2%, 1%, 8% and 19% of the variation in PON1 activity, respectively. In summary, our new data indicate that genetic variation in the PON3 gene influences serum PON1 activity independently of the known effect of PON1 genetic variation. To our knowledge, this is the first study reporting the association of the PON3 gene variants with PON1 activity. [source] Influence of Genetic Variation in the C-Reactive Protein Gene on the Inflammatory Response During and After Acute Coronary IschemiaANNALS OF HUMAN GENETICS, Issue 6 2006J. Suk Danik Summary The aim of this research was to assess whether common genetic variants within the C-reactive protein gene (CRP) are related to the degree of acute rise in plasma C-reactive protein (CRP) levels following an acute coronary syndrome (ACS). While polymorphisms within CRP are associated with basal CRP levels in healthy men and women, less is known about the relationship of such genetic variants and the degree of CRP rise during and after acute ischemia. Plasma CRP is associated with increased rates of recurrent coronary events. We evaluated seven common genetic variants within CRP and assessed their relationship to the degree of rise in CRP levels immediately following an acute coronary syndrome in 1827 European American patients. Variants in the putative promoter region, ,757T > C and ,286C > T > A, were associated with the highest CRP elevations after ACS. Patients with two copies of the A allele of SNP ,286C > T > A had median CRP values of 76.6 mg/L, compared to 11.1 mg/L in patients with no copies of the rare variant (p-value <0.0001), post ACS. The lowest CRP values were found for patients with minor alleles of the exonic 1059G > C and the 3,untranslated region 1846G > A SNPs. For example, patients homozygous for the minor allele of 1059G > C had 71% lower median CRP values than those homozygous for the major allele [3.5 vs 12.0 mg/L, p < 0.0001]. These trends persisted in the chronic stable phase after ischemia had resolved, and after adjustment for infarct size by peak creatinine kinase levels and clinical status by Killip class. Assessment of CRP genetic variants identified patients with higher and lower CRP elevation after acute coronary syndrome. [source] Genetic Variation in Fragmented Forest Stands of the Andean Oak Quercus humboldtii Bonpl. (Fagaceae),BIOTROPICA, Issue 1 2007Juan F. Fernández-M. ABSTRACT Quercus humboldtii is a montane forest dominant species in Colombia, which has experienced significant habitat loss. Using three microsatellite loci, we compared the genetic diversity of adults and seedlings in fragments of small and large size. Results show high genetic diversity, comparable to other temperate oak species (Ho= 0.813, He= 0.780, and f=,0.044). However, allelic richness reduction in seedlings of the most fragmented part of the landscape, suggested restricted gene flow and risk of future genetic bottlenecks, if larger tracts of forest disappear. RESUMEN Quercus humboldtii es una especie dominante de las montañas colombianas que ha sufrido una importante perdida de hábitat. Usando marcadores microsatélites, comparamos la diversidad genética de adultos y plántulas en fragmentos pequeños y grandes. Encontramos una alta diversidad genética, comparable a las especies de robles de zonas templadas (Ho= 0.813, He= 0.780 y f=,0.044). Sin embargo, existe una reducción en la riqueza alélica de las plántulas de la zona más fragmentada, sugiriendo que deben conservarse grandes áreas boscosas para evitar riesgos futuros de pérdida de la diversidad genética. [source] ORIGINAL ARTICLE: Genetic Predisposition to Idiopathic Recurrent Spontaneous Abortion: Contribution of Genetic Variations in IGF-2 and H19 Imprinted GenesAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2008a Ostoji Problem, Recurrent spontaneous abortion (RSA) is a common clinical problem with a complex etiology of genetic and non-genetic causes, which remains to be fully determined. IGF-2 stimulates trophoblast invasion, proliferation and maturation of placenta, while H19 RNA suppresses growth. As genomic imprinting plays a critical role in the development of placenta and embryo, our aim was to evaluate the possible role of variations in IGF-2 and H19 imprinted genes as factors of predisposition for RSA. Method of study, A case,control study was conducted to determine the association between IGF-2 and H19 gene polymorphisms and the susceptibility to RSA in 113 couples with RSA and 226 controls. PCR/RFLP were performed to analyze IGF-2 ApaI and H19 HhaI polymorphisms. Results, We found a statistically significant difference in the genotype frequency distribution of IGF-2 ApaI polymorphism between males from couples with RSA and healthy males (,2(2) = 45.12; P < 0.0001). There were no differences in the genotype and allele distribution of H19 polymorphism frequencies, or for the IGF-2 ApaI polymorphism between female groups. Conclusion, The presence of IGF-2 ApaI polymorphism in partners of RSA women could affect IGF-2 level of expression in placenta and embryo and represent a risk factor for RSA susceptibility. [source] Population Size, Genetic Variation, and Reproductive Success in a Rapidly Declining, Self-Incompatible Perennial (Arnica montana) in The NetherlandsCONSERVATION BIOLOGY, Issue 6 2000Sheila H. Luijten In 26 populations in The Netherlands we investigated the relationship between population size and genetic variation using allozyme markers. Genetic variation was low in A. montana ( He = 0.088). There were positive correlations between population size and the proportion of polymorphic loci, the number of effective alleles, and expected heterozygosity, but not with observed heterozygosity. There was a significantly positive correlation between population size and the inbreeding coefficient. Generally, small populations showed heterozygote excess, which decreased with increasing population size. Possibly, the heterozygous individuals in small populations are survivors from the formerly larger populations with relatively high fitness. The F statistics showed a moderately high level of differentiation among populations ( FST = 0.140 ± 0.02), implying a low level of gene flow. For three out of four allozyme loci, we found significant inbreeding ( FIS = 0.104 ± 0.03). Only 14 of 26 populations were in Hardy-Weinberg equilibrium at all four polymorphic loci. In a subset of 14 populations of various size, we investigated natural seed production and offspring fitness. Population size was positively correlated with seed set, seedling size, number of flowering stems and flowerheads, adult survival, and total relative fitness, but not with the number of florets per flowerhead, germination rate, or the proportion of germination. Offspring performance in the greenhouse was not associated with genetic diversity measured on their mothers in the field. We conclude that the fitness of small populations is significantly reduced, but that there is as yet no evidence that this was caused by inbreeding. Possibly, the self-incompatibility system of A. montana has been effective in reducing selfing rates and inbreeding depression. Resumen:Arnica montana es una especie de planta rara, en declinación rápida y autoincompatible. En 26 poblaciones de los Países Bajos investigamos la relación entre el tamaño poblacional y la variación genética mediante el uso de alozimas marcadoras. La variación genética fue baja en A. montana ( He = 0.088). Existió una correlación positiva entre el tamaño poblacional y la proporción de emplazamientos polimórficos, el número de alelos efectivos y la heterocigocidad esperada, pero no con la heterocigocidad observada. Existió una correlación positiva significativa entre el tamaño poblacional y el coeficiente de endogamia. Generalmente, las poblaciones pequeñas mostraron una heterocigocidad excesiva con disminuciones en el tamaño poblacional. Posiblemente, los individuos heterocigóticos de poblaciones pequeñas son sobrevivientes de poblaciones anteriormente grandes con una adaptabilidad relativamente alta. Las pruebas de F mostraron un nivel de diferenciación moderadamente alto entre poblaciones ( FST = 0.140 ± 0.02) lo que implica un nivel bajo de flujo de genes. Para tres de cuatro de los emplazamientos de alozimas encontramos una endogamia significativa ( FIS = 0.104 ± 0.03). Solamente 14 de las 26 poblaciones estuvieron en equilibrio Hardy-Weinberg para los cuatro emplazamientos polimórficos. En un subconjunto de 14 poblaciones de varios tamaños, investigamos la producción natural de semillas y la adaptabilidad de la descendencia. El tamaño poblacional estuvo positivamente correlacionado con el juego de semillas, el tamaño del almácigo, el número de tallos en flor y de inflorescencias, la supervivencia de adultos y la adaptabilidad total relativa, pero no con el número de flores por inflorescencia, la tasa de germinación ni la proporción de la germinación. El rendimiento de la descendencia en invernaderos no estuvo asociado con la diversidad genética medida en sus madres en el campo. Concluimos que la adaptabilidad de poblaciones pequeñas está significativamente reducida, pero no existe aún evidencia de que esto sea ocasionado por endogamia. Es posible que el sistema de autoincompatibilidad de A. montana haya sido efectivo en la reducción de tasas de autofecundación y depresión de la endogamia. [source] Genetic variation in D7S1875 repeat polymorphism of leptin gene is associated with increased risk for depression: a case-control study from IndiaDEPRESSION AND ANXIETY, Issue 9 2009Manav Kapoor M.Sc. Abstract Background: Epidemiologic data suggest an association between obesity and depression, however findings vary considerably across different studies. Both depression and obesity are disabling disorders associated with loss over appetite control, influenced by genetic and environmental factors and are risk factors for diseases like hypertension, cardiovascular disorders, etc. This study attempts to establish a link between the symptoms of depression, metabolic disorders, and obesity, to unravel the underlying association/s. Methods: This exploratory case,control study comprises 133 clinically diagnosed depressed individuals and 136 age matched controls. DNA from all 269 subjects was genotyped for D7S1875 repeat polymorphism in the promoter region of Leptin (LEP) gene using polymerase chain reaction. Results: Frequency of the shorter allele of D7S1875 (<208,bp) was 0.73 in the depressive group versus 0.67 in the control group (P=.01). Cases homozygous for D7S1875,208,bp alleles had significantly higher value of systolic (130 versus 122; P<.009) and diastolic (85.4 versus 81; P=.01) blood pressure (SBP and DBP) than the individuals homozygous for<208,bp allele. A similar trend was observed for SBP (127.8 versus 123.6; P=.03) among controls homozygous for the longer or the shorter allele. Thus, the LEP gene appears to be an important genetic determinant for susceptibility to depression in the Indian population (OR=1.4913, 95% CI=1.0334,2.1522; P=.04). Conclusions: Our findings suggest that LEP gene variants could be related to depression and associated co-morbidities such as hypertension. Depression and Anxiety, 2009. © 2009 Wiley-Liss, Inc. [source] Genetic variation and decreased risk for obesity in the Atherosclerosis Risk in Communities StudyDIABETES OBESITY & METABOLISM, Issue 4 2007M. L. Hart Sailors Aim:, To investigate the effects of variation in the leptin [LEP (19A>G)] and melanocortin-4 receptor [MC4R (V103I)] genes on obesity-related traits in 13,405 African-American (AA) and white participants from the Atherosclerosis Risk in Communities (ARIC) Study. Methods:, We tested the association between the single-locus and multilocus genotypes and obesity-related measures [body mass index (BMI), body weight (BW), waist,hip ratio, waist circumference and leptin levels], adjusted for age, physical activity level, smoking status, diabetic status, prevalence of coronary heart disease, hypertension, stroke or transient ischaemic attack. Results:, AA and white female carriers of the MC4R I103 allele exhibited significantly lower BW than non-carriers of this allele (p < 0.05 and p < 0.01 respectively). AA female carriers of both the LEP A19 allele and the MC4R I103 allele were 63% [odds ratio (OR) = 0.37, 95% confidence interval (CI) (0.18,0.78)] less likely to be obese, and white female carriers of the same two alleles were 46% [OR = 0.54, 95% CI (0.32,0.91)] less likely to be obese, than non-carriers of the variant alleles. Female carriers of both the LEP A19 and MC4R I103 alleles had significantly lower BW (p < 0.05), BMI (p < 0.05) and plasma leptin (p < 0.01) than the non-carriers of both the alleles. Carriers of the two variant alleles had lower BMI over the 9-year course of the ARIC study and significantly lower weight gain from age 25 years. No significant joint effect of these two variants was observed in males. Conclusion:, These results suggest that variation within the LEP and MC4R genes is associated with reduced risk for obesity in females. [source] Association analysis of genes in the renin-angiotensin system with subclinical cardiovascular disease in families with Type 2 diabetes mellitus: The Diabetes Heart StudyDIABETIC MEDICINE, Issue 3 2006K. P. Burdon Abstract Aims Cardiovascular disease (CVD) is a major complication of Type 2 diabetes mellitus. The renin-angiotensin system (RAS) and nitric oxide production are both important regulators of vascular function and blood pressure. Genes encoding proteins involved in these pathways are candidates for a contribution to CVD in diabetic patients. We have investigated variants of the angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AT1R) and endothelial nitric oxide synthase (NOS3) genes for association with subclinical measures of CVD in families with Type 2 diabetes mellitus (T2DM). Methods Atherosclerosis was measured by carotid intima-media thickness and calcification of the carotid and coronary arteries in 620 European Americans and 117 African Americans in the Diabetes Heart Study. Because of the role of these systems in blood pressure regulation, blood pressure was also investigated. Results Compelling evidence of association was not detected with any of the SNPs with any outcome measures after adjustments for covariates despite sufficient power to detect relatively small differences in traits for specific genotype combinations. Conclusions Genetic variation of the RAS and NOS3 genes do not appear to strongly influence subclinical cardiovascular disease or blood pressure in this diabetic population. [source] Genetic variation in Myzus persicae populations associated with host-plant and life cycle categoryENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2001Kiriaki Zitoudi Abstract Random amplified polymorphic DNA (RAPD) analysis was applied on 96 clones of Myzus persicae (Sulzer) (Homoptera: Aphididae) representing seven populations collected from different host-plants and regions of Greece. Ten decamer random primers were used to evaluate genetic variation among the examined samples. Despite the variability found between clones, no specific RAPD marker was detected to discriminate the different populations. A significant finding was that aphids from peach and pepper, which were collected far away from tobacco-growing regions, especially those from peach, showed genetic divergence from the tobacco-feeding clones. Moreover, data analysis revealed a significant genetic divergence between holocyclic and anholocyclic populations from tobacco. Lastly, holocyclic clones showed higher level of estimated heterozygosity than the nonholocyclic (anholocyclic, androcyclic and intermediate) ones. [source] | ||||||||||||||||||||||||||||||||||||||||||||||