Home > Research > Talks & Conferences > Talks Given at LIPhy
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These talks are given by invited speakers at LIPhy. The intended audience is the whole LIPhy. A large general introduction intended for non-specialist is usually provided.
Typical talk duration is around one hour and includes about 15 mn of questions. The talks are scheduled usually every Monday at 2PM. The place is at the conference room, second floor.
Access to the lab can be obtained by calling Nadine D’Andréa or Chantal Reignier through the intercom at the main entrance.
Résumé : Contact: Romain Mari
Résumé : New coding genes that evolved from the non-genic region are called de novo evolved genes, which encode functional proteins in taxonomically restricted species and characterize their lineage/species-specific phenotypes. In contrast to new genes that originated from pre-existing genes by duplication, de novo genes do not have known functional motifs or domains and show random-like amino acid sequences. We have previously found that NCYM, an antisense gene of the oncogene MYCN, encodes a de novo evolved gene product that stabilizes MYCN and promotes metastasis of neuroblastoma, a human pediatric tumor. Since NCYM is registered in the database as a non-coding RNA, it is possible that there are many unknown de novo evolved genes that are misclassified as non-coding RNAs. Therefore, there is a need to identify new factors that determine the coding potential.
Recently, we discovered a mathematical structure that distinguishes non-coding RNAs from coding RNAs, which we named the PTI (potential translated island) score. This PTI score can be uniquely calculated from RNA sequences, and when calculated for all human transcripts, the relationship with coding potential was approximated by a linear function passing through the origin. Human noncoding RNAs with high coding potential were predicted to be associated with cerebral development and cancer. Furthermore, we calculated more than 3.4 million transcripts of 100 species and found that PTI is commonly associated with coding potential in cellular organisms.
To investigate the relationship between structure and function of de novo evolved proteins, we analyzed the secondary structure of NCYM by vacuum ultraviolet circular dichroism and identified the amino acids involved in MYCN stabilization. These results suggest that the combination of structural and evolutionary analyses of de novo proteins is useful for elucidating the mechanism of new gene birth.
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Contact: Judith Peters
Résumé : Active-matter physics describes the mesmerizing dynamics of interacting motile bodies: from bird flocks and cell colonies, to collections of synthetic units independently driven far from equilibrium. When motile units self-assemble into flocks where all particles propel along the same direction, they realize one of the most robust ordered phase observed in Nature. But, after twenty five years of intense research the very mechanism controlling the ordering dynamics of both living and artificial flocks has remained unsettled.
In this talk, building on model experiments based on Quincke rollers, I will first explain how a flock suppresses its singularities to form an ordered spontaneous flow. Combining experiments, simulations and theory I will show how to elucidate the elementary excitations of 2D polar active matter and explain their phase ordering dynamics as a self-similar process emerging from the annihilation of +/- 1 defects along a filamentous network of domain walls with no counterparts in passive systems (https://journals.aps.org/prx/abstract/10.1103/PhysRevX.11.031069).
In a second part, I will address the robustness of long range order and discuss the stabilization of topological defects in a polar active fluid through disordered media. Combining experiments and theory, I will show that colloidal flocks collectively cruise through disorder without relaxing the topological singularities of their flows, unlike in pure systems. Introducing colloidal flocks in micro patterned circular chambers, we reveal a state of strongly disordered active matter with no counterparts in equilibrium: a dynamical vortex glass. The resulting state is highly dynamical but the flow patterns, shaped by a finite density of frozen vortices, are stationary and exponentially degenerate (https://www.pnas.org/content/118/10/e2018218118).
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Contact: Salima Rafai
Résumé : Contact: Romain Mari
Notes de dernières minutes :
Résumé : contact: Romain Mari
Résumé : Contact: Benjamin Dollet
Résumé : Contact: Aurélie Dupont / Philippe Peyla
Résumé : Contact: Cyril Picard
Résumé : Dérivations de modèles constitutifs: de la microstructure à la rhéologie des suspensions denses molles
Jury:
Lieu : Salle de conférence LIPhy
