Chevalier G

References (4)

Title : Perigord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis - Martin_2010_Nature_464_1033
Author(s) : Martin F , Kohler A , Murat C , Balestrini R , Coutinho PM , Jaillon O , Montanini B , Morin E , Noel B , Percudani R , Porcel B , Rubini A , Amicucci A , Amselem J , Anthouard V , Arcioni S , Artiguenave F , Aury JM , Ballario P , Bolchi A , Brenna A , Brun A , Buee M , Cantarel B , Chevalier G , Couloux A , Da Silva C , Denoeud F , Duplessis S , Ghignone S , Hilselberger B , Iotti M , Marcais B , Mello A , Miranda M , Pacioni G , Quesneville H , Riccioni C , Ruotolo R , Splivallo R , Stocchi V , Tisserant E , Viscomi AR , Zambonelli A , Zampieri E , Henrissat B , Lebrun MH , Paolocci F , Bonfante P , Ottonello S , Wincker P
Ref : Nature , 464 :1033 , 2010
Abstract : The Perigord black truffle (Tuber melanosporum Vittad.) and the Piedmont white truffle dominate today's truffle market. The hypogeous fruiting body of T. melanosporum is a gastronomic delicacy produced by an ectomycorrhizal symbiont endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal Laccaria bicolor, the expansion of gene families may have acted as a 'symbiosis toolbox'. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of T. melanosporum, which at approximately 125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for approximately 58% of the genome. In contrast, this genome only contains approximately 7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that T. melanosporum degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both L. bicolor and T. melanosporum, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis-'the symbiosis toolbox'-evolved along different ways in ascomycetes and basidiomycetes.
ESTHER : Martin_2010_Nature_464_1033
PubMedSearch : Martin_2010_Nature_464_1033
PubMedID: 20348908
Gene_locus related to this paper: 9pezi-d5g8f4 , 9pezi-d5gi84 , 9pezi-d5gph4 , tubmm-d5g4w2 , tubmm-d5g4w3 , tubmm-d5g4w6 , tubmm-d5g5r5 , tubmm-d5g8z4 , tubmm-d5g938 , tubmm-d5ga65 , tubmm-d5gcz1 , tubmm-d5giz0 , tubmm-d5gkr8 , tubmm-d5glm4 , tubmm-d5gnw0 , tubmm-dapb , tubmm-d5gfj1 , tubmm-d5gpf4 , tubmm-TmEst2 , tubmm-TmEst1 , tubmm-TmEst3 , 9pezi-a0a292py12 , tubmm-kex1

Title : Honeycomb-like structure of the intermediate layers of the rat superior colliculus: afferent and efferent connections - Mana_2001_Neurosci_103_673
Author(s) : Mana S , Chevalier G
Ref : Neuroscience , 103 :673 , 2001
Abstract : There is increasing evidence that acetylcholinesterase is organised in a lattice-like fashion in the intermediate layers of the mammalian superior colliculus. In a recent study, we described this organisation in rat by showing that it comprises a well formed honeycomb-like lattice with about 100 cylindrical compartments or modules occupying both the intermediate collicular layers. Considering this enzyme domain as a reference marker for comparing the organisation of collicular input-output systems, the present study investigates whether the principal sensori-motor systems in intermediate layers also have honeycomb-like arrangements. In 33 animals, the distributions of afferents (visual from extrastriate cortex; somatic from the primary somatosensory cortex, the trigeminal nucleus and the cervical spinal cord) and efferents (cells of origin of the crossed descending bulbospinal tract and uncrossed pathway to the pontine gray, the ascending system to the medial dorsal thalamus) were examined in a tangential plane following applications of horseradish peroxidase-wheatgerm agglutinin conjugate (used as an anterograde and retrograde tracer). In 22 of the 33 rats, axonal tracing was made within single tangential sections also stained for cholinesterasic activity in order to compare the neuron profiles with the cholinesterasic lattice.The results show that these afferent and efferent systems are also organised in honeycomb-like networks. Moreover, those related to the cortical, trigeminal and some of the spinal afferents are aligned with the cholinesterasic lattice. Likewise most of colliculo-pontine, colliculo-bulbospinal and half of colliculo-diencephalic projecting cells also tend to be in spatial register with the enzyme lattice. This indicates that the honeycomb-like arrangement is a basic architectural plan in the superior colliculus for the organisation of both acetylcholinesterase and major sensori-motor systems for orientation.
ESTHER : Mana_2001_Neurosci_103_673
PubMedSearch : Mana_2001_Neurosci_103_673
PubMedID: 11274787

Title : The fine organization of nigro-collicular channels with additional observations of their relationships with acetylcholinesterase in the rat - Mana_2001_Neurosci_106_357
Author(s) : Mana S , Chevalier G
Ref : Neuroscience , 106 :357 , 2001
Abstract : The nigro-collicular pathway that links the basal ganglia to the sensorimotor layers of superior colliculus plays a crucial role in promoting orienting behaviors. This connection originating in the pars reticulata and lateralis of the substantia nigra has been shown in rat and cat to be topographically organized. In rat, a functional compartmentalization of the substantia nigra has also been shown reflecting that of the striatum. In light of this, we reinvestigated the topographical arrangement of the nigro-collicular pathway by examining the innervation of each nigral functional zone. We performed small injections of either biocytin or wheatgerm agglutinin conjugated with horseradish peroxidase restricted to identified somatic, visual and auditory nigral zones. Frontally cut sections showed that innervations provided by the three main nigral zones form a mosaic of complementary domains stratified from the stratum opticum to the ventral part of the intermediate collicular layers, with the somatic afferents sandwiched between the visual and the auditory ones. When reconstructed from semi-horizontal sections, nigral innervations organized in the form of a honeycomb-like array composed of 100 cylindrical modules covering three-quarters of the collicular surface. Such a modular architecture is reminiscent of the acetylcholinesterase lattice we previously described in rat intermediate collicular layers. In the enzyme lattice, the surroundings of the cylindrical modules are composed of a mosaic of dense and diffuse enzyme subdomains. Thus, we compared the distribution of the overall nigral projection and of its constituent channels with the acetylcholinesterase lattice. The procedure combined axonal labelling with histochemistry on single sections for acetylcholinesterase activity. The results demonstrate that the overall nigral projection overlaps the acetylcholinesterase lattice and its constituent channels converge with either the dense or the diffuse enzyme subdomains. The stereometric arrangement of the nigro-collicular pathway is suggestive of an architecture promoting the selection of collicular motor programs for different classes of orienting behavior.
ESTHER : Mana_2001_Neurosci_106_357
PubMedSearch : Mana_2001_Neurosci_106_357
PubMedID: 11566506

Title : Honeycomb-like structure of the intermediate layers of the rat superior colliculus, with additional observations in several other mammals: AChE patterning - Chevalier_2000_J.Comp.Neurol_419_137
Author(s) : Chevalier G , Mana S
Ref : Journal of Comparative Neurology , 419 :137 , 2000
Abstract : The aim of the present study was to reinvestigate the stereometric pattern of acetylcholinesterase (AChE) activity staining in the intermediate layers of the superior colliculus in several mammalian species. A pioneering study in the cat and the monkey by Graybiel (1978) stressed the regular arrangement of AChE staining in the deep collicular layers. According to her description, made in the frontal plane, the enzyme was arranged in a mediolateral series of patches, the cores of which tended to line up in the longitudinal axis of the structure, so they formed roughly parallel bands. As exhaustive a description as possible of the AChE distribution was undertaken in the rat by compiling observations in the frontal, sagittal, and tangential planes. It emerged that AChE-positive elements are organized in the form of a conspicuous honeycomb-like network that is divided into about 100 rounded compartments, over virtually the full extent of the intermediate layers. The generality of the rat model was then tested in other rodents such as mouse and hamster and also in cat and monkey. For these species we resorted to a single tangential cutting plane, which proved to be more appropriate for disclosing such a modular arrangement. The data revealed that in all species AChE staining followed the same architectural plan and identified the striking similarity in the number of compartments that compose the various honeycomb-like lattices. In conclusion, the present findings support a unified model of the AChE arrangement within the intermediate layers of the mammalian colliculus; the model comprehensively incorporates the classical description of the patchy and stripy features of the enzyme distribution. We hypothesize here that the modular AChE arrangement might be the anatomical basis for collicular vectorial encoding of orienting movements.
ESTHER : Chevalier_2000_J.Comp.Neurol_419_137
PubMedSearch : Chevalier_2000_J.Comp.Neurol_419_137
PubMedID: 10722995