Les enseignants: à la recherche de leur profession

Les Enseignants: à la recherche de leur profession reprend les idées centrales présentées à la Conférence donnée, sur l'invitation de l'ATEE, au Séminaire de Barcelone, en 1993. Cet article est la reproduction du texte de support à la Conférence. Étant donné l'espace disponible, il n'a pas été possible de le travailler dans le sens d'une plus grande problématisation et élaboration théorique

A high-resolution map of the Nile tilapia genome: a resource for studying cichlids and other percomorphs

Background: The Nile tilapia (Oreochromis niloticus) is the second most farmed fish species worldwide. It is also an important model for studies of fish physiology, particularly because of its broad tolerance to an array of environments. It is a good model to study evolutionary mechanisms in vertebrates, because of its close relationship to haplochromine cichlids, which have undergone rapid speciation in East Africa. The existing genomic resources for Nile tilapia include a genetic map, BAC end sequences and ESTs, but comparative genome analysis and maps of quantitative trait loci (QTL) are still limited. Results: We have constructed a high-resolution radiation hybrid (RH) panel for the Nile tilapia and genotyped 1358 markers consisting of 850 genes, 82 markers corresponding to BAC end sequences, 154 microsatellites and 272 single nucleotide polymorphisms (SNPs). From these, 1296 markers could be associated in 81 RH groups, while 62 were not linked. The total size of the RH map is 34,084 cR3500 and 937,310 kb. It covers 88% of the entire genome with an estimated inter-marker distance of 742 Kb. Mapping of microsatellites enabled integration to the genetic map. We have merged LG8 and LG24 into a single linkage group, and confirmed that LG16-LG21 are also merged. The orientation and association of RH groups to each chromosome and LG was confirmed by chromosomal in situ hybridizations (FISH) of 55 BACs. Fifty RH groups were localized on the 22 chromosomes while 31 remained small orphan groups. Synteny relationships were determined between Nile tilapia, stickleback, medaka and pufferfish. Conclusion:The RH map and associated FISH map provide a valuable gene-ordered resource for gene mapping and QTL studies. All genetic linkage groups with their corresponding RH groups now have a corresponding chromosome which can be identified in the karyotype. Placement of conserved segments indicated that multiple inter-chromosomal rearrangements have occurred between Nile tilapia and the other model fishes. These maps represent a valuable resource for organizing the forthcoming genome sequence of Nile tilapia, and provide a foundation for evolutionary studies of East African cichlid fishes.Additional co-authors: Thomas D Kocher, Catherine Ozouf-Costaz, Jean Francois Baroiller and Francis Galiber

Comparative physical maps derived from BAC end sequences of tilapia (Oreochromis niloticus)

Background: The Nile tilapia is the second most important fish in aquaculture. It is an excellent laboratory model, and is closely related to the African lake cichlids famous for their rapid rates of speciation. A suite of genomic resources has been developed for this species, including genetic maps and ESTs. Here we analyze BAC endsequences to develop comparative physical maps, and estimate the number of genome rearrangements, between tilapia and other model fish species. Results: We obtained sequence from one or both ends of 106,259 tilapia BACs. BLAST analysis against the genome assemblies of stickleback, medaka and pufferfish allowed identification of homologies for approximately 25,000 BACs for each species. We calculate that rearrangement breakpoints between tilapia and these species occur about every 3 Mb across the genome. Analysis of 35,000 clones previously assembled into contigs by restriction fingerprints allowed identification of longer-range syntenies. Conclusions: Our data suggest that chromosomal evolution in recent teleosts is dominated by alternate loss of gene duplicates, and by intra-chromosomal rearrangements (~one per million years). These physical maps are a useful resource for comparative positional cloning of traits in cichlid fishes. The paired BAC end sequences from these clones will be an important resource for scaffolding forthcoming shotgun sequence assemblies of the tilapia genome. (Résumé d'auteur

Razão, religião e revolução: luzes e sombras nas telas de Jacques-Louis David

O artigo analisa a produção pictórica de Jacques-Louis David entre o final da década de 1770 e 1793, destacando o entrelaçamento entre arte, religião e política nas obras do artista francês. Em sua luta contra o Antigo Regime, “filósofos artistas”, como Jacques-Louis David, apossaram-se das armas que eram manipuladas, há séculos, por um de seus principais inimigos: a Igreja. A transmissão do ideário iluminista não poderia ficar restrita à “aridez” dos textos acadêmicos, devendo buscar na religião e nas artes o “encantamento” indispensável à conquista de olhos, ouvidos, cérebros e corações. Depois de recorrer aos heróis das antigas Grécia e Roma, Jacques-Louis David debruçou-se sobre os homens do seu tempo: os deputados de O juramento do jogo de pela e os mártires que sacrificaram suas vidas em prol da revolução. Entrelaçando a arte clássica com a cristã, razão, revolução e religião, Jacques-Louis David forjou estratégias que seriam mobilizadas na propagação de líderes e ideários políticos nos séculos XIX e XX.The article analyzes the pictorial production of Jacques-Louis David between the late 1770s and 1793, highlighting the links between art, religion and politics in the works of the French artist. In their struggle against the Old Regime “philosophers artists,” as Jacques-Louis David, they took possession of the weapons that were manipulated for centuries by one of its main enemies: the Church. The transmission of Enlightenment ideas could not be restricted to “aridity” of academic papers and should seek in religion and the arts the “enchantment” indispensable to the conquest of eyes, ears, brains and hearts. After resorting to the heroes of ancient Greece and Rome, Jacques-Louis David leaned across the men of his time: the deputies of Tennis Court Oath and the martyrs who sacrificed their lives for the sake of revolution. Interweaving classical art with Christian art, reason, revolution and religion, Jacques-Louis David forged strategies that would be mobilized in the spread of political leaders and ideologies in the nineteenth and twentieth centuries

Cytogenetic variation of repetitive DNA elements in Hoplias malabaricus (Characiformes - Erythrinidae) from white, black and clear water rivers of the Amazon basin

Abstract Hoplias malabaricus is a common fish species occurring in white, black and clear water rivers of the Amazon basin. Its large distribution across distinct aquatic environments can pose stressful conditions for dispersal and creates possibilities for the emergence of local adaptive profiles. We investigated the chromosomal localization of repetitive DNA markers (constitutive heterochromatin, rDNA and the transposable element REX-3) in populations from the Amazonas river (white water), the Negro river (black water) and the Tapajós river (clear water), in order to address the variation/association of cytogenomic features and environmental conditions. We found a conserved karyotypic macrostructure with a diploid number of 40 chromosomes (20 metacentrics + 20 submetacentrics) in all the samples. Heteromorphism in pair 14 was detected as evidence for the initial differentiation of an XX/XY system. Minor differences detected in the amount of repetitive DNA markers are interpreted as possible signatures of local adaptations to distinct aquatic environments