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One Genotype (one + genotype)
Selected AbstractsGenetic identity of interspecific neighbours mediates plant responses to competition and environmental variation in a species-rich grasslandJOURNAL OF ECOLOGY, Issue 5 2007JASON D. FRIDLEY Summary 1Although outbreeding populations of many grassland plants exhibit substantial genetic and phenotypic variation at fine spatial scales (< 100 m2), the implications of local genetic diversity for community structure are poorly understood. Genetic diversity could contribute to local species diversity by mediating the effects of competition between species and by enhancing species persistence in the face of environmental variation. 2We assayed the performance of three genotypes each of a dominant tussock grass (Koeleria macrantha [Ledeb.] J.A. Schultes) and dominant sedge (Carex caryophyllea Lat.) derived from a single 10 × 10 m quadrat within a limestone grassland in Derbyshire, UK. Genotypes were grown in monoculture and grass,sedge mixtures of different genetic composition in two environments of contrasting fertility. Species mixtures also included one genotype of the subordinate forb Campanula rotundifolia L. 3When grown without neighbours, intraspecific genotypes responded similarly to environmental treatments. One genotype of the sedge performed worse in both environments than the other two sedge genotypes. 4When grown in species mixtures, genotype performance was significantly influenced by the genetic identity of the neighbouring species for both the sedge and the grass. At high fertility, differential genotype performance was not sufficient to alter the expectation of competitive exclusion of the sedge by the grass. However, at low fertility, the competitive dominant depended on the genetic identity of both the grass and the sedge. In addition, each genotype of the grass performed best next to a different genotype of the sedge, and the identity of the best genotype pairings switched with environment. 5Performance of a single genotype of the subordinate Campanula was not predictable by fertility alone, but by how fertility interacted with different neighbouring genotypes of both the grass and the sedge. 6Results support the hypothesis that the genetic identity of interspecific neighbours influences plant performance in multispecies assemblages and mediates species' responses to environmental variation. Such interactions could be a key factor in the contribution of local intraspecific genetic diversity to species diversity. [source] Evaluation of Gossypium species for resistance to cotton leaf curl Burewala virusANNALS OF APPLIED BIOLOGY, Issue 1 2010K.P. Akhtar Cotton leaf curl disease (CLCuD), caused by cotton leaf curl Burewala virus (CLCuBV), has emerged as a major threat to cotton production in Pakistan. Resistance to CLCuBV was evaluated in cultivated and wild cotton genotypes representing six Gossypium species by visual symptom scoring and virus assessment using PCR tests. Considerable variation in responses was observed when using whitefly and graft transmission to inoculate Gossypium genotypes with CLCuBV in field and greenhouse experiments. Under field evaluation, all cultivated genotypes of Gossypium hirsutum and three genotypes of G. barbadense were susceptible. Eleven genotypes that represented six wild and cultivated Gossypium species were considered to be highly resistant as they were free from infection. Similar results were obtained when these genotypes were tested using whitefly transmission. To verify these findings, 132 cultivated and wild genotypes were tested by graft inoculation. All G. hirsutum genotypes (116 cultivated, 1 wild, 1 transgenic Coker-312 and 1 non-transgenic Coker-312), three G. barbadense genotypes and one G. thurberi genotype were highly susceptible and exhibited symptoms 9,12 days after grafting. Four genotypes of G. arboreum and one genotype of G. anomalum did not express symptoms but had a detectable level of virus. One genotype of G. herbaceum and three wild genotypes of G. hirsutum showed mild symptoms (severity indexes of 1,2) and exhibited delayed disease development. These genotypes were classified as moderately resistant to resistant. Resistant genotypes that were identified in this study will be useful sources for exploitation of breeding programmes aimed at developing CLCuBV-resistant varieties and increasing genetic diversity. [source] Cognitive profile in a large french cohort of adults with Prader,Willi syndrome: differences between genotypesJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 3 2010P. Copet Abstract Background Prader,Willi syndrome (PWS) is a rare genetic disorder characterised by developmental abnormalities leading to somatic and psychological symptoms. These include dysmorphic features, impaired growth and sexual maturation, hyperphagia, intellectual delay, learning disabilities and maladaptive behaviours. PWS is caused by a lack of expression of maternally imprinted genes situated in the 15q11-13 chromosome region. The origin is a ,de novo' deletion in the paternal chromosome in 70% of the cases and a maternal uniparental disomy in 25%. The two main genotypes show differences, notably regarding cognitive and behavioural features, but the mechanisms are not clear. This study assessed cognitive impairment in a cohort of adults with genetically confirmed PWS, analysed their profiles of cognitive strengths and weaknesses, and compared the profiles in terms of genotype. Methods Ninety-nine male and female adults participated, all inpatients on a specialised unit for the multidisciplinary care of PWS. The Wechsler Adult Intelligence Scale (WAIS-III) was administered to all patients in identical conditions by the same psychologist. Eighty-five patients were able to cope with the test situation. Their scores were analysed with non-parametric statistical tools. The correlations with sex, age and body mass index were explored. Two genotype groups were compared: deletion (n = 57) and non-deletion (n = 27). Results The distribution of intelligence quotients in the total cohort was non-normal, with the following values (medians): Full Scale Intelligence Quotient (FSIQ): 52.0 (Q1:46.0; Q3:60.0), Verbal Intellectual Quotient (VIQ): 53.0 (Q1:48; Q3:62) and Performance Intellectual Quotient (PIQ): 52.5 (Q1:48; Q3:61). No correlation was found with sex, age or body mass index. Comparison between groups showed no significant difference in FSIQ or VIQ. PIQ scores were significantly better in the deletion group. The total cohort and the deletion group showed the VIQ = PIQ profile, whereas VIQ > PIQ was observed in the non-deletion group. The subtest scores in the two groups showed significant differences, with the deletion group scoring better in three subtests: object assembly, picture arrangement and digit symbol coding. Some relative strengths and weaknesses concerned the total cohort, but others concerned only one genotype. Discussion We documented a global impairment in the intellectual abilities of a large sample of French PWS patients. The scores were slightly lower than those reported in most other studies. Our data confirmed the previously published differences in the cognitive profiles of the two main PWS genotypes and offer new evidence to support this hypothesis. These results could guide future neuropsychological studies to determine the cognitive processing in PWS. This knowledge is essential to improve our understanding of gene-brain-behaviour relationships and to open new perspectives on therapeutic and educational programmes. [source] HCV genotypes in Sicily: Is there any evidence of a shift?JOURNAL OF MEDICAL VIROLOGY, Issue 6 2009Paola Pizzillo Abstract The distribution of HCV strains in any area is characterized by a relative prevalence of one genotype, and a number of less prevalent types. In some Western countries a change from the prevalent HCV genotype 1 to genotypes 3 and 4 has been reported in the last decade. In order to assess possible variations of the distribution of HCV genotypes in Sicily, a southern region of Italy, a hospital-based cohort, collected prospectively, of 3,209 subjects with chronic HCV infection was surveyed, comparing the distribution of HCV genotypes during two consecutive periods, from 1997 to 2002 and from 2003 to 2007, according to age and gender. The results show that genotype 1b, which has been historically the most prevalent in Sicily, is still predominant, followed more distantly by genotypes 2 and 3a. However, a cohort effect for these genotypes was seen when comparing the two time periods. Genotype 1b decreased slowly over the last decade, due to the death of the people infected, leading to a proportional increase of the other genotypes. No evidence was found in support of a major increase in the prevalence of other genotypes, such as genotype 4, in relation to migration patterns. J. Med. Virol. 81:1040,1046, 2009. © 2009 Wiley-Liss, Inc. [source] Prevalence of HBV genotypes in Central and Eastern EuropeJOURNAL OF MEDICAL VIROLOGY, Issue 10 2008Katja Deterding Abstract The importance of hepatitis B virus (HBV) genotypes for disease progression and response to interferon-alpha-based treatment is well established. While almost all patients in the Mediterranean area are infected with HBV genotype D, HBV genotype A is dominant in Northern Europe. However, the distribution of HBV genotypes is unknown for several Central and Eastern European countries. Data are described of 1313 HBsAg-positive patients recruited at 14 referral centers in eight countries. There were only very few cases of HBV genotype B, C, E, F, and H infection while HBV genotypes A and D were found in 42% and 48% of patients, respectively. Eight percent of patients had positive bands for more than one genotype using the hybridization assay. The frequency of genotype A was higher in Poland (77%) and the Czech Republic (67%) as compared to Hungary (47%), Lithuania (41%), Croatia (8%), and Germany (32%). In contrast, HBV genotype D was most frequent in Croatian, Romanian, and Russian patients with 80%, 67%, and 93% of cases, respectively. In conclusion, HBV genotype A versus D showed significantly different distribution patterns in Central and Eastern Europe which deserves consideration for national guidelines and treatment decisions. J. Med. Virol. 80:1707,1711, 2008. © 2008 Wiley-Liss, Inc. [source] Adaptive microclimatic structural and expressional dehydrin 1 evolution in wild barley, Hordeum spontaneum, at ,Evolution Canyon', Mount Carmel, IsraelMOLECULAR ECOLOGY, Issue 9 2009ZUJUN YANG Abstract ,Evolution Canyon' (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unravelling evolution in action highlighting the twin evolutionary processes of adaptation and speciation. A major model organism in ECI is wild barley, Hordeum spontaneum, the progenitor of cultivated barley, which displays dramatic interslope adaptive and speciational divergence on the ,African' dry slope (AS) and the ,European' humid slope (ES), separated on average by 200 m. Here we examined interslope single nucleotide polymorphism (SNP) sequences and the expression diversity of the drought resistant dehydrin 1 gene (Dhn1) between the opposite slopes. We analysed 47 plants (genotypes), 4,10 individuals in each of seven stations (populations) in an area of 7000 m2, for Dhn1 sequence diversity located in the 5, upstream flanking region of the gene. We found significant levels of Dhn1 genic diversity represented by 29 haplotypes, derived from 45 SNPs in a total of 708 bp sites. Most of the haplotypes, 25 out of 29 (= 86.2%), were represented by one genotype; hence, unique to one population. Only a single haplotype was common to both slopes. Genetic divergence of sequence and haplotype diversity was generally and significantly different among the populations and slopes. Nucleotide diversity was higher on the AS, whereas haplotype diversity was higher on the ES. Interslope divergence was significantly higher than intraslope divergence. The applied Tajima D rejected neutrality of the SNP diversity. The Dhn1 expression under dehydration indicated interslope divergent expression between AS and ES genotypes, reinforcing Dhn1 associated with drought resistance of wild barley at ,Evolution Canyon'. These results are inexplicable by mutation, gene flow, or chance effects, and support adaptive natural microclimatic selection as the major evolutionary divergent driving force. [source] Three-dimensional fine-scale genetic structure of the neotropical epiphytic orchid, Laelia rubescensMOLECULAR ECOLOGY, Issue 5 2004Dorset W. Trapnell Abstract Epiphytic plants occupy three-dimensional space, which allows more individuals to be closely clustered spatially than is possible for populations occupying two dimensions. The unique characteristics of epiphytes can act in concert to influence the fine-scale genetic structure of their populations which can, in turn, influence mating patterns and other population phenomena. Three large populations of Laelia rubescens (Orchidaceae) in the Costa Rican seasonal dry forest were sampled at two levels of intensity to determine: (i) whether individual clusters contain more than one genotype, and (ii) the spatial distribution and fine-scale genetic structure of genotypes within populations. Samples were assayed for their multilocus allozyme genotypes and spatial autocorrelation analyses were performed. High levels of genetic diversity, high genotypic diversity and low among-population variation were found. In the larger clusters, multiple genets per cluster were common with discrete clusters containing up to nine genotypes. Spatial autocorrelation analyses indicated significant positive genetic structure at distances of , 45 cm. This result is likely due to the formation of discrete clusters by vegetative reproduction, as well as the establishment of sexually derived progeny within and near maternal clusters. [source] Alteration of the genomic composition of Solanum nigrum (+) potato backcross derivatives by somatic hybridization: selection of fusion hybrids by DNA measurements and GISHPLANT BREEDING, Issue 3 2001K. Horsman Abstract Fusion experiments were performed with a first (BC1 -6738) and a second (BC2 -9017) generation backcross hybrid of 6x Solarium nigrum (+) 2x potato somatic hybrids with potato cultivars. Because no progeny was obtained from the BC2 genotypes, alternative approaches were sought to overcome the sexual crossing barrier. Five potato genotypes, one of which contains the hygromycin resistance gene, were used in the fusion experiments. All vigorous regenerants were used for the estimation of nuclear DNA content using flow cytometry. Plants with a DNA content higher than that of the BC1 -6738 or BC2 genotypes were considered potential somatic hybrids. Forty-nine potential somatic hybrids resulted from fusion experiments with BC1 -6738, from which 20 grew vigorously in the greenhouse and flowered. After pollination with several 4x potato cultivars, eight genotypes produced seeded berries and five genotypes gave seedless berries. In addition, 11 of these 13 somatic hybrids were selected for genomic in situ hybridization (GISH) analysis to determine their genomic composition. Nine had exactly or approximately the expected number of 36 S. nigrum and 60 potato chromosomes. In one genotype, only 22 instead of 36 S. nigrum chromosomes were found and one potato chromosome was possibly missing. Only five potential somatic hybrids were detected among the 79 regenerants from BC2 -9017 (+) 2x potato fusion experiments that were analysed by flow cytometry. Two of these hybrids were rather vigorous and did flower, but pollinations with potato have not yet set any berries. [source] Water relations under root chilling in a sensitive and tolerant tomato speciesPLANT CELL & ENVIRONMENT, Issue 8 2004A. J. BLOOM ABSTRACT The shoots of cultivated tomato (Lycopersicon esculentum cv. T5) wilt if their roots are exposed to chilling temperatures of around 5 °C. Under the same treatment, a chilling-tolerant congener (Lycopersicon hirsutum LA 1778) maintains shoot turgor. To determine the physiological basis of this differential response, the effect of chilling on both excised roots and roots of intact plants in pressure chambers were investigated. In excised roots and intact plants, root hydraulic conductance declined with temperature to nearly twice the extent expected from the temperature dependence of the viscosity of water, but the response was similar in both species. The species differed markedly, however, in stomatal behaviour: in L. hirsutum, stomatal conductance declined as root temperatures were lowered, whereas the stomata of L. esculentum remained open until the roots reached 5 °C, and the plants became flaccid and suffered damage. Grafted plants with the shoots of one genotype and roots of another indicated that the differential stomatal behaviour during root chilling has distinct shoot and root components. [source] Importance of secondary inoculum of Plasmopara viticola to epidemics of grapevine downy mildewPLANT PATHOLOGY, Issue 4 2005D. Gobbin To quantify the magnitude and the spatial spread of grapevine downy mildew secondary sporangia, 4685 Plasmopara viticola single lesion samples were collected from 18 plots spread across central Europe. Disease symptoms were collected on two to 22 sampling dates per plot between 2000 and 2002. Four multiallelic microsatellite markers were used for genotypic identification of pathogen samples. Genetic analysis showed more than 2300 site-specific P. viticola genotypes, indicating that populations are genetically rich demographic units. Approximately 70% of the genotypes were sampled once and 14% were sampled twice throughout the various epidemics. In the 18 populations only seven genotypes (0.3%) were identified more than 50 times. Three genotypes particularly successful in causing disease through secondary cycles showed mainly a clustered distribution. The distance of sporangial migration per secondary cycle was less than 20 m and their plot colonization rate was calculated at around 1,2 m2 day,1. Downy mildew epidemics of grapevine are therefore the result of the interaction of a multitude of genotypes, each causing limited (or a few) lesions, and of a dominant genotype able to spread stepwise at plot-scale. These findings contrast with current theories about grapevine downy mildew epidemiology, which postulate that there is massive vineyard colonization by one genotype and long-distance migration of sporangia. [source] Presence of beta human papillomaviruses in nonmelanoma skin cancer from organ transplant recipients and immunocompetent patients in the West of ScotlandBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2009L.J. Mackintosh Summary Background, Nonmelanoma skin cancer (NMSC) has been linked to cutaneous human papillomaviruses of the genus beta (betaPV). Objectives, We sought to assess the presence of betaPV in NMSC biopsies from a group of Scottish skin cancer patients, both immunocompetent (IC) patients and immunosuppressed (IS) organ transplant recipients. Methods, One hundred and twenty-one paraffin-embedded skin tumours (27 actinic keratosis, 41 intraepidermal carcinoma, 53 squamous cell carcinoma) and 11 normal skin samples were analysed for the presence of betaPV by a polymerase chain reaction,reverse hybridization assay designed to detect the presence of the 25 known betaPV genotypes. Results, In IC patients, betaPV was detected in 30 of 59 (51%) tumours and two of 11 (18%) normal skin samples (P = 0·046). In IS patients, betaPV was found in 27 of 62 (44%) tumours; no normal skin samples were available for comparison. The most frequently found genotypes were HPV-24, HPV-15 and HPV-38. Of those tumours infected with betaPV, 28 of 57 (49%) were infected with more than one genotype (range 2,8). Tumours from IS patients were from a younger age group (mean age 57·4 years) than IC patients (mean age 73·8 years). Multiple infections were more common in tumours from IC patients (21 of 30; 70%) compared with those from IS patients (seven of 27; 26%) (P < 0·001). In the IC group, age did not appear to influence the distribution of single and multiple infections whereas in IS patients the proportion of multiple infections to single infections increased with age. There were no multiple infections in normal skin. Conclusions, A wide spectrum of betaPV types was detected in our samples. Further characterization of betaPV in vivo is needed in order to determine the mechanisms by which the virus contributes to cutaneous carcinogenesis. [source] | |||||||||||||