The Experts below are selected from a list of 2394 Experts worldwide ranked by ideXlab platform
Jeanchristophe Simon - One of the best experts on this subject based on the ideXlab platform.
-
genetic characterisation of new host specialised biotypes and novel associations with bacterial symbionts in the pea aphid complex
Insect Conservation and Diversity, 2015Co-Authors: Jean Peccoud, Manon De La Huerta, Cindy Laurence, Frédérique Mahéo, Jeanchristophe SimonAbstract:1. The pea aphid, Acyrthosiphon pisum Harris, constitutes a complex of sympatric populations that are specialised to distinct species of Fabaceae. So far, 12 such populations have been characterised genetically as genetic clusters associated with one or few legumes species. These clusters form a continuum of genetic divergence linking host-associated races, which show moderate hybridization, to nascent species. They are also known to be associated with different species of endosymbiotic bacteria, which have environmentally dependent effects on aphid fitness2. Here, we report on the genetic characterisation of new host-associated populations in this species complex. We sampled pea aphids in eastern France on Genista tinctoria, G. sagittalis, Onobrychis viciifolia, and Hippocrepis comosa. Bayesian clustering methods based on genotypes obtained at 25 microsatellite loci showed that each sampled plant species hosted a specific pea aphid population. Comparison with previously characterised biotypes showed that the population associated with Hippocrepis comosa was no different from that on Securigera varia. Migrant aphids from other host plants and hybrids were found at various frequencies on the newly sampled plant species. They were particularly frequent on Onobrychis viciifolia, occasional between the two Genista-associated populations, and rare on Hippocrepis comosa.3. PCR-based screening of bacterial species revealed new associations between aphid biotypes and facultative endosymbionts, chiefly the combination of Serratia symbiotica and Hamiltonella defensa within most individuals collected on Genista.4. The newly identified biotypes, which add up to a total of 15 within the pea aphid complex, offer new material to study the mechanisms and genetic bases of host-specialisation and ecological speciation in this model aphid.
-
Genetic characterisation of new host‐specialised biotypes and novel associations with bacterial symbionts in the pea aphid complex
Insect Conservation and Diversity, 2015Co-Authors: Jean Peccoud, Manon De La Huerta, Cindy Laurence, Frédérique Mahéo, Jeanchristophe SimonAbstract:1. The pea aphid, Acyrthosiphon pisum Harris, constitutes a complex of sympatric populations that are specialised to distinct species of Fabaceae. So far, 12 such populations have been characterised genetically as genetic clusters associated with one or few legumes species. These clusters form a continuum of genetic divergence linking host-associated races, which show moderate hybridization, to nascent species. They are also known to be associated with different species of endosymbiotic bacteria, which have environmentally dependent effects on aphid fitness2. Here, we report on the genetic characterisation of new host-associated populations in this species complex. We sampled pea aphids in eastern France on Genista tinctoria, G. sagittalis, Onobrychis viciifolia, and Hippocrepis comosa. Bayesian clustering methods based on genotypes obtained at 25 microsatellite loci showed that each sampled plant species hosted a specific pea aphid population. Comparison with previously characterised biotypes showed that the population associated with Hippocrepis comosa was no different from that on Securigera varia. Migrant aphids from other host plants and hybrids were found at various frequencies on the newly sampled plant species. They were particularly frequent on Onobrychis viciifolia, occasional between the two Genista-associated populations, and rare on Hippocrepis comosa.3. PCR-based screening of bacterial species revealed new associations between aphid biotypes and facultative endosymbionts, chiefly the combination of Serratia symbiotica and Hamiltonella defensa within most individuals collected on Genista.4. The newly identified biotypes, which add up to a total of 15 within the pea aphid complex, offer new material to study the mechanisms and genetic bases of host-specialisation and ecological speciation in this model aphid.
Paloma Cubas - One of the best experts on this subject based on the ideXlab platform.
-
Molecular phylogeny and systematics of Genista (Leguminosae) and related genera based on nucleotide sequences of nrDNA (ITS region) and cpDNA (trnL-trnF intergenic spacer)
Plant Systematics and Evolution, 2004Co-Authors: Cristina Pardo, Paloma Cubas, Hikmat TahiriAbstract:Phylogenetic relationships of Genista and related genera (Teline, Chamaespartium, Pterospartum, Echinospartum, Ulex, Stauracanthus and Retama) were assessed by the analysis of sequences of the nrDNA internal transcribed spacer (ITS region), and the cpDNA trnL-trnF intergenic spacer. The tree obtained by combining both sets of data indicates the existence of three lines of diversification within Genista, that correspond to three subgenera: Genista, Phyllobotrys and Spartocarpus, however, each of these lineages encompass also species of the related genera Echinospartum, Teline, Retama, Chamaespartium, Pterospartum, Ulex, Stauracanthus. The molecular data do not support division of these subgenera into taxonomical units at the sectional level; only sections Genista and Spartocarpus are monophyletic groups. The sequences of both regions are also informative at the specific level, grouping morphologically related species (e.g. the G. cinerea aggregate). The molecular data have also helped to clarify the position of taxa whose relationships were not well established (e.g. G. valdes-bermejoi). The relationships of related genera that belong to the Genista lines of diversification have also been investigated. Echinospartum splits into two separate clades matching the separation of two ecological and caryological differentiated groups. Teline also forms two groups, both placed near to Genista subgenus Genista, but that separated from the main core of the group. Retama, morphologically well differentiated from Genista, is close to Genista subgenus Spartocarpus. Chamaespartium and Pterospartum do not form a monophyletic group. Chamaespartium is closer to Genista subgenus Genista, whereas Pterospartum stands close to: 1) Genista subgenus Spartocarpus (particularly, sect. Cephalospartum); and 2) the Ulex-Stauracanthus clade (a terminal derivative of Genista subgenus Spartocarpus). Cases of incongruence (e.g. Echinospartum, Chamaespartium, Teline) between the trees obtained from the two molecular markers, may be indicating hybridisation and/or introgression between different lines of Genisteae.
-
molecular approach to the phylogeny and systematics of cytisus leguminosae and related genera based on nucleotide sequences of nrdna its region and cpdna trnl trnf intergenic spacer
Plant Systematics and Evolution, 2002Co-Authors: Paloma Cubas, Cristina Pardo, Hikmat TahiriAbstract:Phylogenetic relationships of Cytisus and allied genera (Argyrocytisus, Calicotome, Chamaecytisus, Cytisophyllum, and Spartocytisus) were assessed by analysis of sequences of the nrDNA internal transcribed spacer (ITS) and the cpDNA trnL-trnF intergenic spacer. Genera of the Genista-group (Chamaespartium, Echinospartum, Genista, Pterospartum, Spartium, Teline and Ulex) were included to check the position of Cytisus species transferred to Teline. The tree obtained by combining both sets of data indicates that the Genista and Cytisus groups form two separate clades. Cytisus heterochrous and C. tribracteolatus are more closely related to the Cytisus-group, thus their transfer to Teline is not supported by molecular data. Cytisus fontanesii (syn. Chronanthos biflorus) groups with Cytisophyllum sessilifolium and Cytisus heterochrous within the Cytisus-group. Similarly, Argyrocytisus battandieri falls within the Cytisus-group as a well differentiated taxon. All these taxa seem to have early diverged from the Cytisus-group. Their taxonomic rank should be reconsidered to better reflect their phylogenetic separation from Cytisus. On the contrary, Chamaecytisus proliferus and Spartocytisus supranubius enter in the main core of Cytisus, and they should better be included in sections of Cytisus (sect. Tubocytisus and Oreosparton, respectively). Sect. Spartopsis is not monophyletic and the position of several species, currently included in this section, deserves reevaluation: C. arboreus aggregate is closely related to C. villosus (sect. Cytisus) and to Calicotome; C. striatus is closely related to Cytisus sect. Alburnoides; and the position of C. commutatus (incl. C. ingramii) remains unclear. The relationships and positioning of several minor taxa (C. transiens, C. megalanthus, and C. maurus) are also discussed.
-
Karyological and taxonomic notes on Genista L. (Papilionoideae, Leguminosae) from the Iberian Peninsula
Botanical Journal of the Linnean Society, 1998Co-Authors: Paloma Cubas, C. Pardo, D. Sánchez-mata, Paloma CantóAbstract:Abstract Karyological information about Iberian Genista species is limited because of their wide geographical distribution. It is a major factor in the understanding of a genus whose genetic evolution is mostly related to aneuploidy and euploidy. The chromosome numbers of the following taxa have been counted G. carpetana subsp. carpetana ( n =20), G. cinerascens ( n =12), G. micrantha ( n =18), G. mugronensis subsp. rigidissima ( n =18), G. ramosissima (2 n =48) and G. tinctoria ( n =24). The previously-assumed uniformity of chromosome number ( n =24) for all the subspecies of G. cinerea is supported here by data from subspp. murcica and speciosa . In G. florida , a new chromosome number, n =23, has been found for both subspecies ( florida and polygaliphylla ). A discussion of the discrepancies between these data and previous ones is included. A new level of ploidy has been found in G. tournefortii subsp. tournefortii ( n =32). The data stress the necessity of obtaining chromosomal information from a number of plants of a taxon before its characteristic number is clear, and indicate that more chromosomal data will help the understanding of the cytological diversity within taxa in Genista .
Jean Peccoud - One of the best experts on this subject based on the ideXlab platform.
-
genetic characterisation of new host specialised biotypes and novel associations with bacterial symbionts in the pea aphid complex
Insect Conservation and Diversity, 2015Co-Authors: Jean Peccoud, Manon De La Huerta, Cindy Laurence, Frédérique Mahéo, Jeanchristophe SimonAbstract:1. The pea aphid, Acyrthosiphon pisum Harris, constitutes a complex of sympatric populations that are specialised to distinct species of Fabaceae. So far, 12 such populations have been characterised genetically as genetic clusters associated with one or few legumes species. These clusters form a continuum of genetic divergence linking host-associated races, which show moderate hybridization, to nascent species. They are also known to be associated with different species of endosymbiotic bacteria, which have environmentally dependent effects on aphid fitness2. Here, we report on the genetic characterisation of new host-associated populations in this species complex. We sampled pea aphids in eastern France on Genista tinctoria, G. sagittalis, Onobrychis viciifolia, and Hippocrepis comosa. Bayesian clustering methods based on genotypes obtained at 25 microsatellite loci showed that each sampled plant species hosted a specific pea aphid population. Comparison with previously characterised biotypes showed that the population associated with Hippocrepis comosa was no different from that on Securigera varia. Migrant aphids from other host plants and hybrids were found at various frequencies on the newly sampled plant species. They were particularly frequent on Onobrychis viciifolia, occasional between the two Genista-associated populations, and rare on Hippocrepis comosa.3. PCR-based screening of bacterial species revealed new associations between aphid biotypes and facultative endosymbionts, chiefly the combination of Serratia symbiotica and Hamiltonella defensa within most individuals collected on Genista.4. The newly identified biotypes, which add up to a total of 15 within the pea aphid complex, offer new material to study the mechanisms and genetic bases of host-specialisation and ecological speciation in this model aphid.
-
Genetic characterisation of new host‐specialised biotypes and novel associations with bacterial symbionts in the pea aphid complex
Insect Conservation and Diversity, 2015Co-Authors: Jean Peccoud, Manon De La Huerta, Cindy Laurence, Frédérique Mahéo, Jeanchristophe SimonAbstract:1. The pea aphid, Acyrthosiphon pisum Harris, constitutes a complex of sympatric populations that are specialised to distinct species of Fabaceae. So far, 12 such populations have been characterised genetically as genetic clusters associated with one or few legumes species. These clusters form a continuum of genetic divergence linking host-associated races, which show moderate hybridization, to nascent species. They are also known to be associated with different species of endosymbiotic bacteria, which have environmentally dependent effects on aphid fitness2. Here, we report on the genetic characterisation of new host-associated populations in this species complex. We sampled pea aphids in eastern France on Genista tinctoria, G. sagittalis, Onobrychis viciifolia, and Hippocrepis comosa. Bayesian clustering methods based on genotypes obtained at 25 microsatellite loci showed that each sampled plant species hosted a specific pea aphid population. Comparison with previously characterised biotypes showed that the population associated with Hippocrepis comosa was no different from that on Securigera varia. Migrant aphids from other host plants and hybrids were found at various frequencies on the newly sampled plant species. They were particularly frequent on Onobrychis viciifolia, occasional between the two Genista-associated populations, and rare on Hippocrepis comosa.3. PCR-based screening of bacterial species revealed new associations between aphid biotypes and facultative endosymbionts, chiefly the combination of Serratia symbiotica and Hamiltonella defensa within most individuals collected on Genista.4. The newly identified biotypes, which add up to a total of 15 within the pea aphid complex, offer new material to study the mechanisms and genetic bases of host-specialisation and ecological speciation in this model aphid.
Diana Ordoñez-rueda - One of the best experts on this subject based on the ideXlab platform.
-
The transcriptional repressor Gfi1 prevents lupus autoimmunity by restraining TLR7 signaling
European Journal of Immunology, 2016Co-Authors: Benoit Desnues, Diana Ordoñez-rueda, Amanda Macedo, Annie Roussel-queval, Bernard Malissen, Pierre Bruhns, Marie Malissen, Lena AlexopoulouAbstract:The transcriptional repressor growth factor independence 1 (Gfi1) is important in myeloid and lymphoid differentiation. In the current study we evaluated the involvement of Gfi1 in systemic lupus erythematosus (SLE). We found that Genista mice, which carry a hypomorphic mutation in the gfi1 gene or Gfi1‐deficient (Gfi1−/−) mice develop signs of spontaneous lupus autoimmunity, including increased serum levels of IgM and IgG2a, autoantibodies against RNA and DNA, glomerular immunodeposits and increased frequencies of plasmablasts, germinal center (GC) B cells and age‐associated B cells (ABCs). On the contrary, Genista mice deprived of TLR7 did not show any of these phenotypes, suggesting that the observed lupus autoimmunity in Genista mice is TLR7‐dependent. Moreover, Genista mice showed an increased activation of dendritic cells (DCs), B and T cells that was dependent on TLR7 for DCs and B cells, but not for T cells. Upon TLR7 or TLR4 stimulation Genista DCs produced increased amounts of TNF, IL‐6 and IFN‐β and showed increased NF‐κB phosphorylation and IRF7 nuclear translocation, suggesting that Gfi1 controls the NF‐κB and type I IFN signaling pathway downstream of TLRs. Our data reveal that Gfi1 plays a critical role in the prevention of spontaneous lupus autoimmunity by negatively regulating TLR7 signaling.
-
A hypomorphic mutation in the Gfi1 transcriptional repressor results in a novel form of neutropenia
European Journal of Immunology, 2012Co-Authors: Diana Ordoñez-rueda, David A. Mancardi, Aurélie Malzac, Elodie Bertosio, Pierre Grenot, Veronique Blanquet, Friederike Jonsson, Yinming Liang, Weidong Zhao, Sybille SabrautzkiAbstract:Using N-ethyl-N-nitrosourea-induced mutagenesis, we established a mouse model with a novel form of neutropenia resulting from a point mutation in the transcriptional repressor Growth Factor Independence 1 (Gfi1). These mice, called Genista, had normal viability and no weight loss, in contrast to mice expressing null alleles of the Gfi1 gene. Furthermore, the Genista mutation had a very limited impact on lymphopoiesis or on T- and B-cell function. Within the bone marrow (BM), the Genista mutation resulted in a slight increase of monopoiesis and in a block of terminal granulopoiesis. This block occurred just after the metamyelocytic stage and resulted in the generation of small numbers of atypical CD11b + Ly-6G int neutrophils, the nuclear morphology of which resembled that of mature WT neutrophils. Unexpectedly, once released from the BM, these atypical neutrophils contributed to induce mild forms of autoantibody-induced arthritis and of immune complex-mediated lung alveolitis. They additionally failed to provide resistance to acute bacterial infection. Our study demonstrates that a hypomorphic mutation in the Gfi1 transcriptional repressor results in a novel form of neutropenia characterized by a split pattern of functional responses, reflecting the distinct thresholds required for eliciting neutrophil-mediated inflammatory and anti-infectious responses.
Paloma Cantó - One of the best experts on this subject based on the ideXlab platform.
-
Line-scatter plots in chemotaxonomy of Genista L. Section Spartioides Spach in Western Europe
Biochemical Systematics and Ecology, 1999Co-Authors: I. Van Rensen, Markus Veit, Paloma Cantó, Roland Greinwald, Ulrich Röhner-van Rensen, Herbert Vogt, Franz-christian CzyganAbstract:Abstract Isoflavone patterns of Genista species from the section Spartioides in west Europe were reported. Orobol-8- C -glucoside, isoprunetin-7- O -glucoside, genistein-8- C -glucoside, genistein-6- C -glucoside, genistein-7- O -glucoside and a further, unknown isoflavone glycoside were detected in different amounts and proportions in most of the analysed Genista species. Line-scatter plots were developed to visualise the chemotaxonomic significance of the detected isoflavone glycosides. With these plots the influence of up to six characters could be demonstrated in one diagram. Line-scatter plots fill a gap between the widely used scatter plots and graphical presentations based on multivariate analysis of a large number of characters. The isoflavone patterns of the Genista specimens presented in line-scatter plots showed small intraspecific variation compared to their interspecific variation. In Genista chemotaxonomy, isoflavone patterns are useful additional characters on the species and partly on the subspecies level. This was confirmed in discriminant analysis. Together with other chemotaxonomic data (quinolizidine alkaloids), morphological, cytological, biogeographical and phytosociological characters, isoflavone patterns provided data for a species concept within the section. Further-more, the proposed subdivision of the section into the subsections Chamaespartum and Spartioides was supported by the clear differences of their isoflavone patterns. Isoflavones allowed a more detailed subdivision of the section Spartioides than alkaloid data.
-
Karyological and taxonomic notes on Genista L. (Papilionoideae, Leguminosae) from the Iberian Peninsula
Botanical Journal of the Linnean Society, 1998Co-Authors: Paloma Cubas, C. Pardo, D. Sánchez-mata, Paloma CantóAbstract:Abstract Karyological information about Iberian Genista species is limited because of their wide geographical distribution. It is a major factor in the understanding of a genus whose genetic evolution is mostly related to aneuploidy and euploidy. The chromosome numbers of the following taxa have been counted G. carpetana subsp. carpetana ( n =20), G. cinerascens ( n =12), G. micrantha ( n =18), G. mugronensis subsp. rigidissima ( n =18), G. ramosissima (2 n =48) and G. tinctoria ( n =24). The previously-assumed uniformity of chromosome number ( n =24) for all the subspecies of G. cinerea is supported here by data from subspp. murcica and speciosa . In G. florida , a new chromosome number, n =23, has been found for both subspecies ( florida and polygaliphylla ). A discussion of the discrepancies between these data and previous ones is included. A new level of ploidy has been found in G. tournefortii subsp. tournefortii ( n =32). The data stress the necessity of obtaining chromosomal information from a number of plants of a taxon before its characteristic number is clear, and indicate that more chromosomal data will help the understanding of the cytological diversity within taxa in Genista .
-
Ester alkaloids of Genista cinerea subspecies Cinerea
Phytochemistry, 1994Co-Authors: I. Van Rensen, Markus Veit, Victor Wray, Ludger Witte, Paloma Cantó, Roland Greinwald, Gerhard Veen, Franz-christian CzyganAbstract:Abstract Two ester alkaloids, cineverine and a new compound, for which we suggest the name cineroctine, were isolated from twigs of Genista cinerea subsp. cinerea . Their structures were determined by spectroscopic methods to be 13α-(3′, 4′-dimethoxybenzoyl)oxylupanine (cineverine) and 13α-(3-hydroxy- cis -oct-5-enoyl)oxylupanine (cineroctine), 13- O -axial derivatives of lupanine. The distribution of these ester alkaloids amongst the different species of the section Spartioides of the genus Genista is recorded.