Éditeur(s) : HAL CCSD
Résumé : International audience
BIOLOGICAL IDENTITY IS NOT ONLY GENETICAL IDENTITY : A CHALLENGE FOR A CITIZEN TEACHING. The 20 th century marked the success of the genetics. The beginning 21 th century is aware of the limits of the " all-genetics ". Nevertheless, the curricula of the secondary school are not yet modified in this way. The present work analyses the conceptions of 33 future Biology teachers, and analyses also, in 3 scholar textbooks (for pupils 16 years old), the chapters related to the notion of " biological identity ". The results show that this notion is reduced to the notion of " genetical program " , and associated with a model of linear causal determinism of the phenotype by the genotype. The scientific and citizen dangers of this model are discussed. The challenge is now to teach a new model with interactions between the genotype and its environment : the epigenesis, and particularly the cerebral epigenesis. KEYWORDS : Biology Education – Genetics – Genetical determinism – Phenotype – Cerebral epigenesis-Conceptions of teachers – Curricula – Scholar textbooks-RÉSUMÉ : Alors que le 20 ème siècle est celui du succès de la génétique, le 21 ème siècle s'ouvre avec la conscience des limites du " tout-génétique ". Cependant les programmes de Biologie au Lycée tardent à se modifier dans ce sens. Le présent travail analyse les conceptions de 33 futurs enseignants de Biologie, ainsi que, dans 3 manuels scolaires de la classe de Première S, les chapitres relatifs à la notion d'identité biologique. Il en ressort que celle-ci est limitée à la notion de programme génétique, avec un modèle de déterminisme causal linéaire du phénotype par le génotype.
Bioed2000 the challenge of the next century
Paris, France

Droits : info:eu-repo/semantics/OpenAccess
hal-01620726
https://hal.univ-antilles.fr/hal-01620726
https://hal.univ-antilles.fr/hal-01620726/document
https://hal.univ-antilles.fr/hal-01620726/file/clementforissierBioEd2001.pdf

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
A hallmark of living systems is the management and the storage of information through genetic and epigenetic mechanisms. Although the notion of epigenetics was originally given to any regulation beyond DNA sequence, it has often been restricted to chromatin modifications, supposed to behave as cis-markers, specifying the sets of genes to be expressed or repressed. This definition does not take into account the initial view of epigenetics, based on nonlinear interaction networks whose "attractors" can remain stable without need for any chromatin mark. In addition, most chromatin modifications are the steady state resultants of highly dynamic modification and de-modification activities and, as such, seem poorly appropriate to work as long-term memory keepers. Instead, the basic support of epigenetic memory could remain the attractors, to which chromatin modifications belong as do many other components. The influence of chromatin modifications in memory is highly questionable when envisioned as static structural marks, but can be recovered under the dynamic circuitry perspective, thanks to their self-templating properties. Beside their standard repressive or permissive functions, chromatin modifications can also influence transcription in multiple ways such as: (1) by randomizing or inversely stabilizing gene expression, (2) by mediating cooperativity between pioneer and secondary transcription factors, and (3) in the hysteresis and the ultrasensitivity of gene expression switches, allowing the cells to take unambiguous transcriptional decisions.
ISSN: 1420-682X

hal-01063617
https://hal.archives-ouvertes.fr/hal-01063617
DOI : 10.1007/s00018-012-0923-7
PUBMED : 22331281

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The separation of the germ line from the soma is a classic concept in animal biology, and depending on species is thought to involve fate determination either by maternally localized germ plasm (''preformation'' or ``maternal inheritance'') or by inductive signaling (classically termed ``epigenesis'' or ``zygotic induction''). The latter mechanism is generally considered to operate in non-bilaterian organisms such as cnidarians and sponges, in which germ cell fate is determined at adult stages from multipotent stem cells. We have found in the hydrozoan cnidarian Clytia hemisphaerica that the multipotent ``interstitial'' cells (i-cells) in larvae and adult medusae, from which germ cells derive, express a set of conserved germ cell markers: Vasa, Nanos1, Piwi and PL10. In situ hybridization analyses unexpectedly revealed maternal mRNAs for all these genes highly concentrated in a germ plasm-like region at the egg animal pole and inherited by the i-cell lineage, strongly suggesting i-cell fate determination by inheritance of animal-localized factors. On the other hand, experimental tests showed that i-cells can form by epigenetic mechanisms in Clytia, since larvae derived from both animal and vegetal blastomeres separated during cleavage stages developed equivalent i-cell populations. Thus Clytia embryos appear to have maternal germ plasm inherited by i-cells but also the potential to form these cells by zygotic induction. Reassessment of available data indicates that maternally localized germ plasm molecular components were plausibly present in the common cnidarian/bilaterian ancestor, but that their role may not have been strictly deterministic.
ISSN: 0012-1606

hal-01544487
https://hal.archives-ouvertes.fr/hal-01544487
DOI : 10.1016/j.ydbio.2012.01.018

Éditeur(s) : HAL CCSD Taylor & Francis (Routledge)
Résumé : International audience
‘Biological identity’ is the result of interactions between the environment and the genome. These interactions, however, were not taught before 2001. In the French syllabus for 16-year-old students, two of the five sections on genetics deal with biological identity. We analysed the texts and images of the chapters relating to these two sections in the three most commonly used textbooks. The results showed that, using strategies specific to each textbook, all focused predominantly on the genetic determination of the phenotype, and on the idea of the ‘genetic code’. We then analysed the conceptions of 35 trainee Biology teachers, using their answers to a questionnaire. For most of them, psychological identity does not illustrate the notion of biological identity: the Cartesian dualism of body/ soul is very influential. The analysis of the trainee teachers' conceptions showed their poor understanding of genome/ environment interactions and of the process of epigenesis. Fortunately, since 2001, in France genome/ environment interactions have been introduced into the new Biology syllabus.
ISSN: 0021-9266

hal-01537729
https://hal.univ-antilles.fr/hal-01537729
DOI : 10.1080/00219266.2003.9655857