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Search Results: 1 - 10 of 1107 matches for " Matthieu Reymond "
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Natural Variation in Arabidopsis thaliana Revealed a Genetic Network Controlling Germination Under Salt Stress
Navot Galpaz,Matthieu Reymond
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015198
Abstract: Plant responses to environmental stresses are polygenic and complex traits. In this study quantitative genetics using natural variation in Arabidopsis thaliana was used to investigate the genetic architecture of plant responses to salt stress. Eighty seven A. thaliana accessions were screened and showed a large variation for root development and seed germination under 125 and 200 mM NaCl, respectively. Twenty two quantitative trait loci for these traits have been detected by phenotyping two recombinants inbred line populations, Sha x Col and Sha x Ler. Four QTLs controlling germination under salt were detected in the Sha x Col population. Interestingly, only one allelic combination at these four QTLs inhibits germination under salt stress, implying strong epistatic interactions between them. In this interacting context, we confirmed the effect of one QTL by phenotyping selected heterozygous inbred families. We also showed that this QTL is involved in the control of germination under other stress conditions such as KCl, mannitol, cold, glucose and ABA. Our data highlights the presence of a genetic network which consists of four interacting QTLs and controls germination under limiting environmental conditions.
Energy Values of Registered Corn Forage Hybrids in France over the Last 20 Years Rose in a Context of Maintained Yield Increase  [PDF]
Aurélie Baldy, Marie-Pierre Jacquemot, Yves Griveau, Cyril Bauland, Matthieu Reymond, Valérie Mechin
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.86099
Abstract: The cultivation of corn silage has developed in France since the 1970s to reach 1.5 million of hectares nowadays. Since 1998, a feeding value criterion (namely UFL for “Unité Fourrage Laitière”) has been taken into account to register forage varieties in the French forage maize hybrids catalog in addition to other criteria related to plant agronomical performances such as yield, earliness and lodging resistance. It is frequently stated that the improvement of plant’s agronomic performances would led to a decline in forage energy value. Decline of “Unité Fourrage Laitière” values has been repeatedly reported and the expected increase was not yet visible in 2002. In the present study, a set 47 early and mid-early hybrids commercialized in France between 1958 and 2015 has been cultivated in 3 locations in France. “Unité Fourrage Laitière” values and yield have been estimated in order to shed light on the evolution of feeding value criteria during this period and to conclude on the evolution of “Unité Fourrage Laitière” values since the introduction of this criterion for registration. Results obtained in our study demonstrated a recent rise in “Unité Fourrage Laitière” value in a context of strong yield increase. This increase was not necessarily attributable to high cob proportion in the harvested silage. Breeder’s work since the 2000’s has succeeded to offer hybrids that recover “Unité Fourrage Laitière” values similar to the ones of hybrids from the 1960’s (Royal, 1960, 91 UFL/100
Variation in Seed Dormancy Quantitative Trait Loci in Arabidopsis thaliana Originating from One Site
Rebecca A. Silady,Sigi Effgen,Maarten Koornneef,Matthieu Reymond
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0020886
Abstract: A Quantitative Trait Locus (QTL) analysis was performed using two novel Recombinant Inbred Line (RIL) populations, derived from the progeny between two Arabidopsis thaliana genotypes collected at the same site in Kyoto (Japan) crossed with the reference laboratory strain Landsberg erecta (Ler). We used these two RIL populations to determine the genetic basis of seed dormancy and flowering time, which are assumed to be the main traits controlling life history variation in Arabidopsis. The analysis revealed quantitative variation for seed dormancy that is associated with allelic variation at the seed dormancy QTL DOG1 (for Delay Of Germination 1) in one population and at DOG6 in both. These DOG QTL have been previously identified using mapping populations derived from accessions collected at different sites around the world. Genetic variation within a population may enhance its ability to respond accurately to variation within and between seasons. In contrast, variation for flowering time, which also segregated within each mapping population, is mainly governed by the same QTL.
Global gene expression patterns in rice
Philippe Reymond
Genome Biology , 2000, DOI: 10.1186/gb-2000-1-1-reports010
Abstract: The authors used 10 rice cDNA libraries represented in dbEST: database of expressed sequence tags. Each library contained at least 890 ESTs and was, in most cases, prepared from a different tissue or developmental stage. ESTs were organized into clusters and contig sequences, and expression profiles (EST counts) were derived for each of 707 contigs containing five or more constituent ESTs. In order to identify genes exhibiting a similar expression pattern, a statistical method (Pearson correlation coefficient) was used to calculate similarity between pairs of genes. These pairs of contigs were then organized into mutually matching clusters. The authors show, for example, that genes encoding storage proteins are clustered together and are predominantly found in libraries prepared from immature seed and panicle at ripening stage. The method is also successfully used to assess pairwise similarity between whole cDNA libraries and shows that two tissues expressing a similar complement of genes are clustered together. Finally, a two-dimensional graphical representation of expression measurements is presented which allows a rapid visualization of clusters of genes obeying similar expression patterns in different conditions (different libraries).A method for EST quality control and generation of contigs can be found at the Structural and genetic information server.Convincing evidence is provided that a rigorous statistical analysis of EST libraries allows fine-scale identification of sequences with correlated expression profiles. The application of this approach to a large collection of cDNA libraries prepared from different organisms at different developmental stages will certainly provide a valuable alternative to cDNA microarray studies in generating gene expression data. A limitation of such a technique is the need for standardization of the preparation of cDNA libraries to ensure that EST frequency tightly correlates with transcript abundance. As the method relies on t
Finding flavor genes
Philippe Reymond
Genome Biology , 2000, DOI: 10.1186/gb-2000-1-2-reports0057
Abstract: Aharoni et al. randomly isolated 1,701 cDNA clones from a strawberry fruit cDNA library and 480 clones from petunia corolla (as control) and printed the PCR-amplified clones on chemically modified glass slides using a robotic device. They used these microarrays to monitor changes in gene expression at three fruit developmental stages (from green to red). Using a rigorous statistical analysis, the authors found that 401 clones were differentially expressed between all three stages, with 177 clones being upregulated between the green and red stages. Sequences of the latter group of genes revealed that more than 50% were related to primary and secondary metabolism. From the other sequences potentially involved in flavor formation, Aharoni et al. identified a novel gene (SAAT) for an alcohol acetyltransferase, an enzyme that catalyzes the final step in the synthesis of volatile esters. This gene shows 16-fold greater expression during the red stage than the green stage of fruit development. The authors expressed recombinant SAAT in Escherichia coli and confirmed that the enzyme has alcohol acetyltransferase activity. Analysis of a series of potential substrates suggests that SAAT is responsible for formation of the predominant esters found in ripe strawberries.Access to Arabidopsis cDNA microarrays is provided by the Arabidopsis Functional Genomics Consortium (AFGC). Links to information on plant microarrays can also be found via the Virtual library: plant-arrays.Large-scale cDNA microarrays are now used with model systems to investigate global patterns of gene expression at the level of the whole organism. The utility of microarrays that cover a restricted portion of the genome, like that described in this paper, will become increasingly recognized, however. This paper is a first example of the use of customized plant cDNA microarrays from a non-model system. It provides a good example of how a small selected array can be used to study a particular developmental proces
The future is genome-wide
Samuel Deutsch, Alexandre Reymond
Genome Biology , 2006, DOI: 10.1186/gb-2006-7-8-324
Abstract: More than 1,700 human geneticists from 59 countries congregated in Amsterdam in May for this year's meeting of the European Society of Human Genetics, which mainly focused on the use of post-genome analysis tools to dissect the causes of and mechanisms governing complex traits. Many of the exciting studies presented were based on two technologies: array-based methods for genome-wide genotyping or technologies for high-density comparative genome hybridization (CGH). A highlight of the meeting was the keynote lecture by Nobel laureate Sydney Brenner (Salk Institute for Biological Studies, La Jolla, USA) on 'humanity's genes', which focused on the challenges we face in transforming the information from the human genome into concrete benefits for our societies.This year has seen the success of several whole-genome association studies using genotyping for single-nucleotide polymorphisms (SNPs) to identify genes responsible for some common complex phenotypes for both discrete and quantitative traits. A plenary lecture by Kari Stefansson (deCODE Genetics, Reykjavik, Iceland) highlighted the tremendous potential of this approach. Several examples were discussed in which new genes have recently been identified using a combination of linkage and association analysis approaches. One example is a locus on human chromosome 8p12 that confers susceptibility to schizophrenia. Although nucleotide variation around the NRG1 gene has been known to be associated with schizophrenia for the past 4 years, the mechanism of action of the associated SNPs, located in noncoding regions 53 to the gene, has remained unclear. Recent evidence strongly suggests that these variants might influence the level of NRG1 expression. Stefansson suggested that many SNPs involved in the etiology of complex phenotypes are likely to affect gene expression or splicing, and that these variants are under strong selective pressure. A second, more recent, example presented by Stefansson concerns the genetics of myoc
Carto-humeur, Carto humour. Avec mon petit atlas…
Mappemonde , 1989,
Morphological Conservation in Human-Animal Hybrids in Science Fiction and Fantasy Settings: Is Our Imagination as Free as We Think It Is?  [PDF]
Matthieu J. Guitton
Advances in Anthropology (AA) , 2013, DOI: 10.4236/aa.2013.33021

The question of whether human imagination knows no boundaries or is, alternatively, constrained by conscious or unconscious cognitive templates is a key issue in defining human mind. We try here to address this extremely large question by focusing on one particular element of imaginary creations, the specific case of human-animal hybrids. Human-animal hybrids are common inhabitants of human imaginary spaces, being regularly encountered across numerous mythologies, as well as in modern popular culture. If human imagination was unconstrained, it would be expected that such hybrid creatures would display roughly half human and half animalistic features. Using several different popular science fiction and fantasy settings, we conducted an analysis of the morphological traits of human-animal hybrids, both anatomical and phenotypic. Surprisingly, we observed extremely high conservation of human morphological traits in human-animal hybrids, with a contrasting high use of phenotypic (“cosmetic”) alterations, and with highly stereotyped patterns of morphological alterations. While these alterations were independent of the setting considered, shape alterations were setting-dependent and used as a way to increase internal coherence. Finally, important gender differences were observed, as female human-animal hybrids retained significantly more human traits than males did, suggesting that conservation of female appearance may bear essential evolutionary importance. Taken together, these results demonstrate the existence of strong cognitive templates which frame and limit the expression of the capacity of human imagination, and unveil some of the psychological mechanisms which constrain the emergence of imaginary spaces.

The Integration of Formal and Non-formal Education: The Dutch “brede school”
du Bois-Reymond, Manuela
Social Work and Society , 2009,
Abstract: The Dutch “brede school” (BS) development originates in the 1990s and has spread unevenly since: quicker in the primary than secondary educational sector. In 2007, there were about 1000 primary and 350 secondary BS schools and it is the intention of the government as well as the individual municipalities to extend that number and make the BS the dominant school form of the near future. In the primary sector, a BS cooperates with crèche and preschool facilities, besides possible other neighborhood partners. The main targets are, first, to enhance educational opportunities, particularly for children with little (western-) cultural capital, and secondly to increase women’s labor market participation by providing extra familial care for babies and small children. All primary schools are now obliged to provide such care. In the secondary sector, a BS is less neighborhood-orientated than a primary BS because those schools are bigger and more often located in different buildings. As in the primary sector, there are broad and more narrow BS, the first profile cooperating with many non-formal and other partners and facilities and the second with few. On the whole, there is a wide variety of BS schools, with different profiles and objectives, dependent on the needs and wishes of the initiators and the neighborhood. A BS is always the result of initiatives of the respective school and its partners: parents, other neighborhood associations, municipality etc. BS schools are not enforced by the government although the general trend will be that existing school organizations transform into BS. The integration of formal and non-formal education and learning is more advanced in primary than secondary schools. In secondary education, vocational as well as general, there is a clear dominance of formal education; the non-formal curriculum serves mainly two lines and objectives: first, provide attractive leisure activities and second provide compensatory courses and support for under-achievers who are often students with migrant background. In both sectors, primary and secondary, it is the formal school organization with its professionals which determines the character of a BS; there is no full integration of formal and non-formal education resulting in one non-disruptive learning trajectory, nor is there the intention to go in that direction. Non-formal pedagogues are partly professionals, like youth- and social workers, partly volunteers, like parents, partly non-educational partners, like school-police, psycho-medical help or commercial leisure providers. Besides that, t
On some Prosobranchia from the coast of S?o Paulo
Marcus, Eveline du Bois-Reymond;
Boletim do Instituto Oceanográfico , 1956, DOI: 10.1590/S0373-55241956000100001
Abstract: ao gênero paraseptaria risbec, 1942, baseado em p. parva risb. da nova caled?nia, foi atribuída p. panqueca, sp. n., do litoral de s?o paulo. o gênero, sem área parietal (columelar) e com opérculo, externo em parva, interno em panqueca, reúne caracteres das phenacolepadidae e neritidae, concordando o aparelho feminino mais com o das últimas. o opérculo interno da nova espécie sugere a possibilidade de terem sido atribuídas a phenacolepas espécies n?o examinadas a respeito, p. e., acmaea hamillei e scutellina antillarum. lamellaria perspicua mopsicolor, f. n., da costa de s?o paulo e do cabo frio, é a primeira espécie da subordem lamellariacea verificada no litoral brasileiro. o ctenídio da fêmea é três vezes maior que o do macho. em seis exemplares, cuja rádula foi preparada, o dente central de todas as séries possui dentículos somente no lado direito da cúspide. isto constitui o caráter principal da forma mopsicolor. na praia de ilhabela as 4 espécies de ianthina conhecidas do atlantico meridional (laursen 1953) s?o ocasionalmente arrastadas à praia: janthina, exigua, prolongata e umbilicata. ultimamente muitas conchas relativamente baixas de i. janthina foram encontradas, cujas protoconchas diferem, quanto à escultura, do material de laursen. nesta espécie e em i. exigua ocorrem olhos e estatocistos. i. janthina tem 3 pares de glandulas faríngeas, cujos dutos se abrem separadamente. o aspecto dos dentes da rádula difere dentro da mesma série transversal, de maneira que a diferen?a n?o pode provir do gasto. as laminas externas e internas das cartilagens bucais de i. janthina e i. exigua s?o unidas atrás da faringe; as mandíbulas homogêneas e incolores s?o estruturas independentes das cartilagens. uma nova figura da balsa de i. janthina é apresentada (fig. 23).
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