Talk abstracts


Thursday 15 March, 9:20am

Asymmetries and symmetries in the mouse oocyte and zygote

Verlhac MH (PhD)¹, Chaigne A (PhD)¹, Campillo C (PhD)², Voituriez R (PhD)³, Gov NS (PhD)⁴, Sykes C (PhD)⁵, Terret ME (PhD)¹

¹ CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Paris F-75005, France

² Université Evry Val d’Essonne, LAMBE, Boulevard F Mitterrand, Evry 91025, France

³ UMR7600-CNRS/UPMC, 4 Place Jussieu, Paris F-75005, France

⁴ Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel

⁵ Institut Curie, CNRS-UMR168, Paris F-75248, France


Abstract: Mammalian oocytes grow periodically after puberty thanks to the dialogue with their niche in the follicle. This communication between somatic and germ cells promotes the accumulation, inside the oocyte, of maternal RNAs, proteins and other molecules that will sustain the two gamete divisions and early embryo development up to its implantation. In order to preserve their stock of maternal products, oocytes from all species divide twice minimizing the volume of their daughter cells to their own benefit. For this, they undergo asymmetric divisions in size where one main objective is to locate the division spindle with its chromosomes off-centred. In this talk, we will review how this main objective is reached with an emphasis on the role of cortical actin mechanics in this process in mouse oocytes, the most studied example in mammals [1]. We will also discuss how actin mechanics promote the switch from asymmetric to symmetric divisions at the oocyte to zygotic transition [2].

References:


Thursday 15 March, 10:10am

Symmetry, asymmetry, and dissymmetry in science and art

Dénes Nagy (President, Dr. h. c.)

International Symmetry Society, Budapest, Hungary & Melbourne, Australia


Dénes Nagy's “dissymmetric signature” that has two-fold rotation (but no mirror symmetry); note that Dénes (five letters) is going into Nagy (four letters) and vice versa – it was a gift by Douglas Hofstadter (the author of Gödel, Escher, Bach).

Abstract: The Greek terms symmetria vs. asymmetria were coined, with great probability, together in connection with the discovery of commensurability vs. incommensurability of pairs of lengths by the Pythagoreans, which undermined their earlier idea that everything can be expressed as the ratio of integers (cf., irrational numbers). This also contributed to the birth of abstract mathematics as a deductive science: the fact that the ratio of a diagonal and a side of a square (or a regular pentagon) is asymmetron mêkei (incommensurable in length), while symmetron dynamei (commensurable in square), required a sophisticated mathematical proof and the manipulation of non-existing objects (reductio ad absurdum). The expressions symmetria vs. asymmetria were adopted into art and aesthetics very quickly in the sense of good proportion vs. the lack of this. However, this terminology disappeared in ancient Latin (cf., commensura and proportio). Still, symmetria survived in Vitruvius’ De architectura. The term symmetria became an empty niche in science, but was later gained a special importance in mathematics in the sense of mirror arrangement (common measure of two halves) and was generalized as rotational symmetry, crystallographic symmetry, and, in general, invariance of some physical properties, while asymmetry referred to the opposite cases. The concept symmetry gained a special importance for listing all of the possible structures in a given class and even predicting new ones (crystals, molecules, elementary particles, and also musical themes, ornamental compositions, etc.) Pasteur solved a major problem in chemistry, which also led the birth of stereochemistry: the optical activity is related to the existence of left- or right-handed molecules, which requires the lack of some elements of symmetry. The latter can be called dissymmetry, while asymmetry is the lack of all the possible elements of symmetry. Dissymmetry or symmetry breaking could be related to the origins of life. It is also interesting to see symmetry vs. asymmetry in mega, macro, and micro levels, from cosmic objects to elementary particles, as well as in art and technology. We may agree with Pierre Curie: The dissymmetry makes the phenomenon. (Also see the proceedings of the ten interdisciplinary symmetry congresses: Budapest, 1989; Hiroshima, 1992; Washington, D.C., 1995; Haifa, 1998; Sydney, 2001; Tihany at lake Balaton, 2004; Buenos Aires, 2007; Gmünd, near Salzburg, 2010; Crete, 2013; Adelaide, 2016).


Thursday 15 March, 11:20am

Structural and behavioural asymmetries as the norm of market economies

Pr. Albert Marouani

UCA/Université Nice-Sophia Antipolis/GREDEG

Abstract: In the dominant neo-classical theory, the markets’ way of functioning is generally presented as a balance of symmetric forces such as supply and demand. This balance is a stable state that plays as a benchmark for economic policy-making or the result of a process of equilibration or "market recall forces" that leads to price formation. The latter are supposed to be reliable signals of the state of rarity from which agents will be able to realize their plans of production, consumption, investment, borrowing or lending, or labour supply or demand. We take the opposite view to show that markets are inherently asymmetric and that prices reflect these asymmetries of structures, behaviour and agents. These asymmetries are linked to the radical uncertainty that characterizes the behaviours of the agents or to the nature and the always unequal and conflicting position of the agents on the markets. As a result, market adjustments are made by trial and error and therefore erratic, leading to increasingly serious, real and financial periodic crises. Hence the need to rehabilitate the role of the State, not to reduce asymmetries but to put them at the service of long-term economic and social development projects that are inclusive; reducing uncertainty and inequalities and respecting the environment.


Thursday 15 March, 11:40am

Urban asymmetries in terms of actor-network theory, social (geo)participation, and multi-agent modelling

prof. Robert Olszewski¹, dr Agnieszka Turek¹, dr Bogna Kietlińska², dr Piotr Pałka³, prof. Tadeusz Płatkowski⁴

¹ Faculty of Geodesy and Cartography, Warsaw University of Technology, Warsaw, Poland

² Institute of Applied Social Sciences, University of Warsaw, Warsaw, Poland

³ Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland

⁴ Faculty of Mathematics, Informatics, and Mechanics, University of Warsaw, Warsaw, Poland

Abstract: Asymmetry can be described as an inherent structural trait of most of the cities, regardless of the time of their establishment, and it constitutes the basic rule for producing the majority of urban relations. Bruno Latour’s actor-network theory may be the starting point for discussing the urban relations. According to Latour’s theory, an actant is the basic ingredient of all the networks, namely a factor influencing all the other factors. An actant may be a person or a group of residents, a non-governmental organization, a municipal office, a building, a boulevard, or a district that is being designed. These factors influence each other, forming a system of actors and networks. Such a structure of an urban network can be modelled, e.g. using Fuzzy Cognitive Maps(FCM), game theory tools or the market mechanisms theory. The crucial element of studying the development of a city and the way the urban network works by means of the (broadly defined) game theory is determining whether the knowledge of individual players is symmetrical or if there is an information asymmetry. The so-called Bayesian games or “Stackelberg duopoly” are the examples of games that make use of such an asymmetry. This game presupposes that the players are differentiated in terms of their knowledge. In economics, and particularly in industrial organization, a subject with more information has the “market power” which, in turn, gives him/her an advantage over the others. The multi-agent systems, in which every agent is an independent software element that makes decisions based on private information and that interacts with other agents, are some of the modelling tools used not only in the game theory, but also in the market mechanisms theory and economics. The information asymmetry phenomenon is easily modelled in a multi-agent system, where every agent has a piece of information and its level may be varied.

A lack of symmetry in the way an urban network works and develops, or an unequal distribution of power and influence are manifested in almost all of the layers of the polysemous entity that is a city. Starting with the right to decide, the level of capital (social, economic, cultural or symbolic) of the individual users of the urban space, through the (urban) planning solutions that may result in environmental planning or in ghettoization or a spatial exclusion of particular groups of residents.

When interpreting the idea of “the right to the city,” David Harvey emphasizes that it is not only about the right to access the city’s resources, but also about the right to decide jointly on its directions for development. A smart and sustainable city engages all of its residents in the most important decision-making processes, socializes the process of environmental planning and encourages the development of deliberative and participatory democracy.

The authors intend to devise a concept of a decision support system that makes use of gamification, game theory, multi-agent systems, fuzzy inference systems, and market programming models to support the “weakest link” in an asymmetric network, meaning the residents of the city. During the conference in Nice, we want to discuss a system that embodies Václav Havel’s idea from the essay “The Power of the Powerless”: a system that provides the urban gamification participants with a tool for actual social (geo)participation in the process of forming a smart city.


Thursday 15 March, 12:00pm

Non-stochastic spontaneous symmetry breaking: What kind of weak asymmetric forces is propelling?

Dr. Thomas Buhse¹, Dr. José-Manuel Cruz¹, María E. Noble-Terán¹, and Dr. Jean-Claude Micheau²

¹ Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209 Cuernavaca, Morelos, Mexico

² Laboratoire des IMRCP, UMR au CNRS No. 5623, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse Cedex, France

Abstract: Spontaneous mirror-symmetry breaking is a fascinating phenomenon that has been manifested predominantly in two prominent systems: the crystallization of conglomerates such as sodium chlorate or bromate [1] and the addition of diisopropylzinc to pyrimidine carbaldehydes, also referred to as the “Soai reaction” [2].

Both systems can be described by an autocatalytic and highly stereoselective Frank- type kinetic model [3]. They are therefore relevant to the dynamics of the spontaneous generation of chiral asymmetries, amplification of enantiomeric excess, and extreme sensitivity to chiral additives or to so-called weak asymmetric forces.

ghettoization or a spatial exclusion of particular groups of residents.

Here we present our recent research in respect to a quantification of the Soai reaction [4] taking into account kinetic and structural characteristics as well as several experimental observations in the crystallization of sodium chlorate that indicate the influence of still unexplained but supposed cryptochiral effects, unexpectedly leading to chirally biased crystal populations.

The authors intend to devise a concept of a decision support system that makes use of gamification, game theory, multi-agent systems, fuzzy inference systems, and market programming models to support the “weakest link” in an asymmetric network, meaning the residents of the city. During the conference in Nice, we want to discuss a system that embodies Václav Havel’s idea from the essay “The Power of the Powerless”: a system that provides the urban gamification participants with a tool for actual social (geo)participation in the process of forming a smart city.

References:


Thursday 15 March, 12:20pm

Asymmetric Syntheses and Properties of Odorant Molecules

Pr. Véronique Michelet

University Nice Sophia Antipolis, Institut de Chimie de Nice, UMR 7272 CNRS, Valrose Park, Faculty of Sciences, 06108, Nice Cedex 2, France


Abstract: Natural chiral molecules such as amino acids or sugars exist in the natural state as single enantiomers. This property determines the biological and physiological functions of the proteins, receptors and different nucleic acids of living organisms, which can interact in a radically different way with one or other of the enantiomers of a chiral compound. These properties may be different and / or opposite in several areas such as pharmacy, agrochemicals, cosmetics and perfumery [1].

In 1961 Ohloff published the first data regarding the enantioselective perception of (+)-citronellol with a typical citronella odor, compared to its enantiomer with a geranium type odor [2]. Control of the absolute stereochemistry of a transformation to obtain chiral molecules is therefore a crucial issue and one of the most studied aspects in organic synthesis chemistry [3].

This presentation will give historical and recent examples from Firmenich, Givaudan or Takasago companies on the synthesis of chiral odorant molecules and on the phenomena of enantioselective perception of these chiral fragrances employed in fine and functional perfumery. Differences between enantiomers both in odor quality and strength will also be considered.

References:


Thursday 15 March, 2:10pm

Scaling Law and Tobler's Law for Characterizing Asymmetries in Geography

Bin Jiang, Professor in Computational Geography

Faculty of Engineering and Sustainable Development, Division of GIScience, University of Gävle, SE-801 76 Gävle, Sweden


Abstract: Geographic space, or the Earth’s surface in general, is full of asymmetries or asymmetry related phenomena, such as coastlines, terrain surfaces, lakes and fractal cities, and they demonstrate incredibly beautiful scaling or fractal structure (Mandelbrot 1982). Fractal has been re-defined as a set or pattern in which the scaling of far more small things than large ones recurs multiple times (Jiang and Yin 2014), a relaxed definition, so called the third definition of fractal. This new fractal resembles the living structure – a recursive structure that is defined mathematically, exists in space and matter physically, and reflects in our minds and cognition psychologically (Alexander 2002-2005). The term asymmetry is therefore synonymous to a series of others, such as scaling, fractal, nonlinearity, life, beauty, wholeness, and living structure. Under the third definition, a highway is also fractal, because it contains far more small bends than large ones, and the small bends are embedded recursively in the large bends. As a matter of fact, there are no geographic features that are not fractal, given a right scope and perspective. In this presentation, I will use all kinds of geographic features both natural and artificial to illustrate their fractal nature. The phenomenon of far more small things than large ones or the disproportionality like 80/20 has been formulated as a scaling law, which is available across all scales ranging from the smallest to the largest (Jiang 2015). Available at an individual scale, there is Tobler’s law, implying that nearby things tend to be more or less similar (Tobler 1970). This notion of more or less similar things reflects local symmetries or the proportionality like 50/50. These two fundamental laws – scaling law and Tobler’s law – help well characterize the Earth’s surface in terms of geographic forms and processes.

Geography as a science has three fundamental issues to address regarding geographic space: how it looks, how it works, and what it ought to be. This presentation will focus primarily on understanding geographic forms and processes – the first two issues, and further discuss on how to make geographic forms (or urban structure in particular) more coherent or more whole – the issue of what it ought to be. I will go beyond the understanding of morphology and underlying mechanisms, towards the making – how to make built environments more livable, sustainable, and smart.

References:

Biosketch of the speaker: Dr. Bin Jiang is Professor in GeoInformatics and Computational Geography at University of Gävle, Sweden. He is also affiliated to Royal Institute of Technology (KTH) at Stockholm via KTH Research School. He worked in the past with The Hong Kong Polytechnic University, and the University College London’s Centre for Advanced Spatial Analysis. He is the primary developer of the software tool Axwoman for topological analysis (http://fromto.hig.se/~bjg/axwoman/). He invented the new classification scheme head/tail breaks for scaling analysis (https://en.wikipedia.org/wiki/Head/tail_Breaks). He is the founding chair of the International Cartographic Association Commission on Geospatial Analysis and Modeling. He used to be Associate Editor of international journal Computer, Environment and Urban Systems (2009-2014), and is currently Academic Editor of open access journal PLOS ONE, and Associate Editor of Cartographica. His research interests center on geospatial analysis and modeling of urban structure and dynamics, e.g., agent-based modeling, scaling hierarchy, and topological analysis applied to street networks, cities, and geospatial big data. Inspired by Christopher Alexander’s work, he developed a mathematical model of beauty, which helps address not only why a design is beautiful, but also how much beauty the design has. One can refer to his ResearchGate and Google Scholar pages for more details on what he specializes in.


Thursday 15 March, 3:00pm

Asymmetry in lipids and in proteins for proper material exchange between membranes

Bruno Antonny

Institut de Pharmacologie Moléculaire et Cellulaire, Université Côte d’Azur et CNRS, 660 route des lucioles, 06560 Valbonne, France

Abstract: Within cells, membrane-bound compartments exchange materials through transport vesicles and through contact sites. The former and tiny spheres of about 100 nm in diameter that constantly bud off and fuse between membranes. The latter are 20 nm wide junctions between two apposed and parallel membranes in which transfer proteins exchange molecules. Here, I will discuss how and why the asymmetry of molecules such as lipids or proteins matters to make these exchange processes efficient (e.g. fast and vectorial). Specifically, I will discuss (i) the tethering of transport vesicles by an asymmetric long string-like protein [1]; (ii) the formation of asymmetric contact sites by a cholesterol transfer protein [2]; (iii) the importance of the asymmetric chemistry of lipids for efficient vesicle formation.

References:


Thursday 15 March, 3:20pm

Understanding in vivo axonal development as an inherently asymmetric process

Eng. Agustina Razetti¹, PhD Caroline Medioni², PhD Florence Besse², PhD Xavier Descombes¹

¹ Université Côte d'Azur, INRIA, CNRS, I3S, France

² Université Côte d'Azur, CNRS, Inserm, iBV, France

Abstract: During development, neurons in our nervous system extend their axonal trees in order to reach target neurons or structures, and stablish complex networks that allow the correct functioning of the body and the mind. Even though bibliography on axon outgrowth is vast and axonal chemical guidance has been largely described mostly in vitro [1] , recent work shows that axons are not only capable of sensing and responding to external chemical signals, but are also guided by local changes in the mechanical properties of their surroundings [2,3,4]. These effects should be determinant in vivo, where the axon develops collectively, surrounded by other axons and in mechanically constrained spaces. Thus, to better understand axonal population growth as a whole, one needs to understand the behavior of single constituent neurons, and how they locally interact and influence themselves to produce global growth.

This work sheds light on the effects that intra-population axon-axon mechanical interactions and space confinement during development have on the complexity and intrinsic variability of axonal final morphologies. For this purpose, we developed a stochastic model of 3D axon growth based on Markov chains that takes into account spatial environmental constraints, physical interactions between neighboring axons, and branch formation.

Interestingly, this highly interdisciplinary study unveils collective axon growth as an intriguing physical process, regarding thermodynamics, mechanics, and non-identical geometry generation. In particular, we showcase how this process is integrally asymmetric. From the very well described growth cone asymmetric sensing that allows axonal pathfinding, to less characterized effects like the conditioning imposed by the asymmetric environment and attractive chemical field on overall axonal collective elongation, which directly forces axons to adopt strategies to attain adult morphologies. We also study emergent asymmetric aspects, like the branch angle distributions, the non-reversible entropy of the process and, naturally, the highly asymmetric axonal morphologies, between others.

References:


Thursday 15 March, 3:40pm

Asymmetric bronchi tree model: does pruning bear fruit?

Jonathan Stéphano, Benjamin Mauroy, etc.

Laboratoire J-A. Dieudonné, Nice, France

Abstract: The lung is a complex system consisting in a tree-like network of bronchi whose sizes are decreasing more or less strongly when the distance from the first bronchus -the trachea- increases.

Although lung's bifurcations are asymmetric, many studies on this subject use a bronchial tree model where each bronchus divides into two smaller identical bronchi, we talk of a symmetric tree model [1]. Because they are more difficult to handle, asymmetric studies remain rare. However, it has been shown in [2] that an asymmetric tree with noisy bronchi sizes is more robust in term of resistance to airflow. However, this study used an asymmetric model which is not realistic for terminal bronchi sizes. Terminal bronchi have similar sizes in the lung but not in the model presented in [2], where some bronchi are too small.

What if this model is made more realistic, pruning the tree by cutting the bronchi that are too small? In this case, are we able to increase the tree's viability? What kind of tree would optimize ventilation performance?

We developed an original description of asymmetric trees using suitable parameters that are linked to the maximum and minimum numbers of successive bifurcations along a tree.

In our study, we search for configurations that optimize the network resistance to airflow for a given lung volume. Our goal is to improve our understanding of how evolution might have selected lung's geometry.

The study is still in progress. However, the first results show that the asymmetry effects on the volume and on the resistance are higher than those predicted in the previous study [2].

References:


Thursday 15 March, 4:30pm

A Short History of the Investigation of the Origin of Homochirality in the Terrestrial Biosphere

Wolfram Hans-Peter Thiemann

FB 02, Universität Bremen, Germany

Abstract: The topic of a puzzling strong asymmetry in molecular biology attracted my attention already as far back as in the year 1957, when I joined the undergraduate program in the subject chemistry at the Ludwig-Maximilian-University in München. My teacher at that time, Prof. Huisgen taught us the so called „Strecker“ synthesis of the second simplest amino acid alanine from the basic molecules water, ammonia, and acetaldehyde, whereas he mentioned the fact that a „racemic mixture“ of the enantiomers L- and D-alanine would be always produced, exactly like the two mirror images of the products in an exact relation of strictly a 1 : 1 mixture. A few weeks later though, at the end of the semester he reported on the biomolecules of amino acids (making up the proteins) and sugars (making up the DNS and RNS), existing in our biomatter almost exclusively in the pure form of the L-(in the case of amino acids) resp. the D-enantiomers(in the case of the ribose).

There it was, it struck my mind, a case of a „parity violation“ in biology! Normally, in the view of an average scientist, symmetry in the laws of nature would be a tacit assumption, broken symmetries were almost a sort of an ever avoidable tabu. This puzzle has haunted me all my scientific lifetime, with interruptions I have been privileged to follow this fascinating puzzle throughout my professional career, sometimes touching the project only occasionally by some theoretical, sometimes by some zig-zagging experimental attempts.

Throughout the years, ideas were followed by assuming an effect of an influence of the so called infamous „Parity Violation in Weak Interaction“ on this „Biological Symmetry Break“, occasionally a potential effect of Earth' magnetic field was studied, the impact of circularly polarized radiation causing a stereoselective synthesis was followed, and the power of a spontaneous, accidentally stereoselective „Ur“-synthesis of the first biomolecules – with an amplification mechanism through nonlinear chain reactions – was discussed. To my knowledge it was 1973, when a first „Asymmetry in Chemical Systems“ was organized in the KFA Jülich by the author, where the hitherto very small number of scientists working worldwide actively in this field assembled and exchanged their ideas.

It is extremely satisfying to see today that the number of scientists has multiplied since, squeezing their brains to solve the intriguing puzzle of the observed homochirality of living matter, - including the search for life beyond Earth, a signature of biomatter in general? Whether a final answer will ever be found, I don't dare to speculate. The possibility of finding one day in the near future perhaps a living species with a homochiral architecture somewhere in space (Mars, Europa, Titan, Enceladus, some recently discovered exoplanet, who knows?) would bring us nearer to the answer, but still not prove the specific origin of this parity violation! A never ending fascinating story!The lung is a complex system consisting in a tree-like network of bronchi whose sizes are decreasing more or less strongly when the distance from the first bronchus -the trachea- increases.


Thursday 15 March, 4:50pm

Interstellar ices: a possible scenario for symmetry breaking of extraterrestrial chiral organic molecules of prebiotic interest

Louis L.S. d’Hendecourt¹², Cornelia Meinert³, Laurent Nahon⁴, Uwe J. Meierhenrich³

¹ PIIM-CNRS, Université d’Aix-Marseille, UMR 7345 & ² IAS-CNRS, Université ParisSud, UMR 8617, France

³ Université Côte d’Azur, CNRS, ICN UMR 7272, Nice, France

⁴ Synchrotron SOLEIL, F-91192, Gif sur Yvette, France

Abstract: Interstellar ices, made of simple hydrides of cosmically abundant and semi refractory elements (O, C and N) [1] are widely observed in the infrared spectra of protostars out of which stars, protoplanetary disks, planets and various debris (asteroids and comets) form. Ices represent the major fraction of molecular materials present in these environments. Laboratory simulations involving matrix isolation spectroscopy methods, particularly in the vibrational infrared, have since long, been carried out to assess the importance of ices in the chemical evolution of the interstellar matter [2, 3]. Their photo- and thermochemistry provide a complex organic material reminiscent of the organic matter detected in primitive carbonaceous meteorites [4].

Among the organic material obtained in the laboratory, many chiral amino acids are detected [5]. Recent studies also reveal the presence of aldehydes and sugars such as glycolaldehyde and the chiral glyceraldehyde [6] and higher sugars like aldopentoses including ribose [7]. Carbonaceous chondrites do not only contain similar organic matter but also show various enantiomeric excesses (e.e’s), almost exclusively of the L - form, in some amino acids (see [8] for a recent review). Because of the presence of circularly polarized light (UV-CPL) in star formation regions and the possible connection between interstellar ices and Solar System organics, we have simulated this process using the synchrotron SOLEIL beamline DESIRS and checked that UV-CPL does indeed produce small but significant (up to 2%) ee’s of the same sign in five amino acids, starting from an achiral ice mixtures [9, 10]. Results will be presented and the interpretation, in terms of astrophysical, astrochemical and astrobiological implications, discussed.

References:


Thursday 15 March, 5:10pm

Philae Landing on Comet 67P/Churyumov Gerasimenko, planned chirality measurements and ideas for the future

Dr. Stephan Ulamec¹, Prof. Dr. Uwe Meierhenrich², Dr. Fred Goesmann³

¹ German Aerospace Center, DLR, Cologne, Germany

² Université Nice Sophia Antipolis, Nice, France

³ Max Planck Institute for Solar System Research, MPS, Göttingen, Germany

Abstract: Philae is a comet Lander, part of the ESA Rosetta Mission to comet 67P/Churyumov- Gerasimenko. After a ten year cruise through the solar system it successfully landed on the nucleus of the comet on November 12 th , 2014.

Philae's payload consists of ten scientific instruments [1], including COSAC, an evolved gas analyser with the capability to differentiate chiral molecules [2,3]. After the touchdown of Philae, the anchoring harpoons, which were expected to fix the lander to ground, did not work, Philae bounced in the low gravity environment, and only came to rest after a 2 hours “hop” in an unforeseen area on the comet surface [4]. Although, the scientific instruments, including cameras, mass spectrometers (including the one of COSAC [5]), a magnetometer and a radar instrument could be operated, and fascinating, unprecedented scientific results have been obtained, it was not possible to collect a sample of the surface material and no gas chromatography measurement could be performed. Thus, the measurement of the chirality of molecules on comets, is still to be done in the future.

The paper will describe the Philae mission and the attempts to measure chiral molecules with COSAC, but also suggest future measurements with returned samples from the primitive asteroids (162173)Ryugu and (101955)Bennu with the spacecraft Hayabusa 2 (JAXA) and OSIRIS-REx (NASA), respectively. Both will reach their targets in 2018.

Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae Lander is provided by a consortium led by DLR, MPS, CNES and ASI with additional contributions from Hungary, UK, Finland, Ireland and Austria.

References:


Thursday 15 March, 5:30pm

Processes to separate enantiomers

Prof. Dr.-Ing. Andreas Seidel-Morgenstern

Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstrasse 1, D-39106 Magdeburg, Germany

seidel-morgenstern@mpi-magdeburg.mpg.de


Abstract: Many organic molecules exist in two forms which are non-superimposable mirror images. These stereoisomers are called enantiomers. They are designated as D (dexter) and L (laevus) or as R (rectus) and S (sinister) [1]. There is still no final answer to the fundamental question why life on earth is constructed using only L-amino acids as building blocks [2,3].

Due to the “homochirality of life” there is tremendous interest in the provision of pure enantiomers, in particular in the pharmaceutical industry. Nowadays, there is clear evidence that often only one enantiomer of a chiral drug provides the desired physiological effect. In many cases, the other enantiomer has no effect or is even harmful. Thus, regulators increasingly demand that chiral drugs are administered in an optically pure form. This problem is also of relevance for the food and agrochemical industries. For this reason there are intensive efforts in academic and industrial research to develop techniques which are capable of producing pure enantiomers. The two main approaches tackling this difficult problem are :

Extending classical work [4], asymmetric synthesis has achieved tremendous progress in the last years. The basic concept is distinct to classical non-selective chemical synthesis, which provides 50:50 (racemic) mixtures. However, focusing on a specific new target molecule still remains a challenge and the concepts available are not universal applicable.

Alternative separations of mixtures of enantiomers exploit dedicated enantiopure additives The lecture will describe several concepts and possible related processes [5]. Due to its wide applicability and efficiency, a first focus will be set on preparative chromatography using chiral stationary phases. Then, as a second option, various crystallization based possibilities will be presented. The rivaling concepts will be illustrated and compared for different target molecules based on investigations carried out in the frame of two larger European projects. Finally new options of hybrid separation processes will be discussed along with the attractive possibility to racemize and recycle the unwanted counter-enantiomer.

References:


Thursday 15 March, 8:00pm

Orchestration in asymmetry

Casa’rmonie de Valbonne

40 amateur musicians directed by Fred Borri


Abstract: “We love patterns; we love it when things fall into place, when the last piece of a puzzle fits in, when a piece of music returns triumphantly to the tonic. But we also love to be surprised. We love to see the rules get broken, for the pattern to shift beneath our feet, for the puzzle to refuse to fit together until we look at it from a new angle. This tension between pattern and surprise keeps our ears perked up, it gives us enough to hold on to, it keeps us on our toes.” said Dr. Cris Moore, physicist and mathematician at The Santa Fe Institute The Majesty of Music + Math.

Dr. Moreno Andreatta, CNRS Director of Research at IRCAM, demonstrates that a vast majority of our music is based in symmetries “from Bach to Paolo Conte”. So what is asymmetry in music? Is it occurring in rhythm? In harmony? In melody? In form? In orchestration?

We, poor musicians, are not sure about all those principles, but we surely know how to play patterns and to surprise our audience. And perhaps, here and then, using prime numbers, ratios, and the entire math that are hiding in music, will we bring you a little piece of asymmetry.

References:


Friday 16 March, 9:00am

Symmetry and Asymmetry: from Molecules to Nanodevices

Prof. David J Wales

University Chemical Laboratories, Lensfield Road, Cambridge, CB2 1EW, United Kingdom


Abstract: Understanding how symmetry and asymmetry determine structure, dynamics and thermodynamics is a key theme in chemical physics [1]. The principle of maximum symmetry [1,2] can be used to guide structure prediction via global optimisation [3], but configurations with high symmetry content may actually be high in energy. Symmetric and asymmetric degenerate rearrangements can lead to observable tunnelling effects, observable in high resolution spectroscopy. The splitting patterns depend upon the feasible pathways connecting permutation-inversion isomers [4], but predicting the magnitude of these effects requires a treatment of quantum dynamics [5]. The geometrical symmetry selection rules permit highly cooperative motions in atomic clusters [1,6], with symmetry-breaking effects in larger systems. For particles interacting via short-range potentials symmetry-breaking is directly quantifiable, and plays a key role in determining the favoured morphologies of colloidal clusters [7]. The final examples in this contribution will focus on helical motifs in proteins, nucleic acids, and mesoscopic systems, which are promising candidates for design of novel nanodevices [8].

References:


Friday 16 March, 9:50am

Comme ceux qui font de fausses fenêtres pour la symétrie : La Fontaine architecte de ses Fables

Pr. Christine Noille

Université Grenoble Alpes


Abstract: Une des plus fameuses « Pensées » de Blaise Pascal (1623-1662) dit ceci :

Ceux qui font les antithèses en forçant les mots font comme ceux qui font de fausses fenêtres pour la symétrie : leur règle n’est pas de parler juste, mais de faire des figures justes [1].

Nous voudrions appliquer cette image architecturale des symétries illusoires à l’art de la composition déployé par La Fontaine dans la constitution de son recueil.

La Fontaine en effet exhibe à la fois un principe général de décohésion et de dispersion (la fameuse « variété »), tout en travaillant à des dispositifs de cohésion locale et modulaire. La structure du recueil des Fables fait ainsi le double pari de l’asymétrie systématique et de la symétrie accidentelle.

Elle alimente ce faisant un double plaisir pour le lecteur, le plaisir du changement et le plaisir de la reconnaissance : « ça peut toujours revenir » est alors la formule de cet art non classique de la composition dissymétrique.

References:


Friday 16 March, 11:00am

Symmetries and asymmetries with photons and lasers

T. Wang¹², H. Vergnet¹³, G.P. Puccioni⁴, and G.L. Lippi¹

¹ Université Côte d’Azur, INPHYNI, UMR 7010 CNRS, France

² Currently at: School of Physics and Electronic Science, Hunan University of Science and Technology, Xiangtan 411201, China

³ Currently at: Laboratoire Pierre Aigrain, École Normale Supérieure Paris, France

⁴ Istituto dei Sistemi Complessi, CNR, Italy

Abstract: Photons, one of the fundamental elements of nature, are the building blocks of the electromagnetic field in all its forms, from radiofrequencies, through the InfraRed, visible and UltraViolet spectrum until X- and gamma-rays. Because of their massless nature, they possess only two possible states of polarization, which represent the symmetries: right-handed corkscrew ↺, and left-handed corkscrew ↻ (i.e., helicity = ± 1 in adequate units) . Their intrinsic lack of symmetry (either left or right) implies that the asymmetry intrinsic to the photon is transmitted to matter at every interaction. Photons emitted in pairs can be combined to “cancel” the handedness, but a trace of the symmetry break remains in the relative phase between the two directions, leading to a state which is aligned either of two orthogonal directions (say horizontal ↔ or vertical ↕) – thus again a symmetry break. These symmetry breaks are fundamental in science but also find innumerable technological applications and are exploited (or circumvented, with great effort) in most applications, among others telecommunications.

Laser light is by its nature entirely polarized since the concept of one prevailing photon mode, which translates into collimated beam emission, also imposes the choice of one polarization over the other (whether circular or linear). Laser emission corresponds therefore to the complete breaking of the right-left (or horizontal-vertical) symmetry in polarization. “Thermal light” instead, such as emitted by a lamp or the sun, does not select any particular mode and photons are present in equal measure in both states. This equilibrium can be naïvely interpreted as a state of symmetry, although it is simply the average over a uniform distribution of asymmetric states.

The development of nanotechnologies has influenced the field of lasers with the promise of building devices with ultralow power consumption and excellent integrability (typical size 1 µm³), which would make them the ideal candidates for photonic circuits (in analogy and as future replacement of electronic circuits), but also as minimally invasive probes (e.g., in medical devices). The volume reduction is accompanied by a larger presence of “thermal photons” in the light emitted by such devices, thus by a degradation in some the laser performances. The influence of thermal photons on smaller lasers can be visualized by looking at the statistical distribution of handedness of the emitted photons and at their probability of occurrence when the laser is repeatedly turned on and off. We have recently obtained nontrivial distributions which give information on the competition between the two photon states during the buildup of laser emission.


Friday 16 March, 11:20am

Dynamically encircling an exceptional point for asymmetric mode switching

Ulrich Kuhl³, Jörg Doppler¹, Alexei A. Mailybaev², Julian Böhm³, Adrian Girschik¹, Florian Libisch¹, Thomas J. Milburn⁴, Peter Rabl⁴, Nimrod Moiseyev⁵ & Stefan Rotter⁵

¹ Institute for Theoretical Physics, Vienna University of Technology (TU Wien), Vienna, A-1040, Austria

² Instituto Nacional de Matemática Pura e Aplicada—IMPA, 22460-320 Rio de Janeiro, Brazil

³ Laboratoire de Physique de la Matière Condensée, CNRS UMR 7336, Université Nice Sophia Antipolis, 06108 Nice, France

⁴ Vienna Center for Quantum Science and Technology, Atominstitut, Vienna University of Technology (TU Wien), Vienna A-1020, Austria

⁵ Schulich Faculty of Chemistry and Faculty of Physics, Technion—Israel Institute of Technology, Haifa, 32000, Israel

Abstract: Physical systems with loss or gain have resonant modes that decay or grow exponentially with time. Whenever two such modes coalesce both in their resonant frequency and their rate of decay or growth, an ‘exceptional point’ occurs, giving rise to fascinating phenomena that defy our physical intuition. Particularly intriguing behaviour is predicted to appear when an exceptional point is encircled sufficiently slowly, such as a state-flip or the accumulation of a geometric phase. The topological structure of exceptional points has been experimentally explored, but a full dynamical encircling of such a point and the associated breakdown of adiabaticity have remained out of reach of measurement. Here we demonstrate that a dynamical encircling of an exceptional point is analogous to the scattering through a two-mode waveguide with suitably designed boundaries and losses. We present experimental results from a corresponding waveguide structure that steers incoming waves around an exceptional point during the transmission process. In this way, mode transitions are induced that transform this device into a robust and asymmetric switch between different waveguide modes. This work will enable the exploration of exceptional point physics in system control and state transfer schemes at the crossroads between fundamental research and practical applications.


Friday 16 March, 11:40am

N-Methyl-D-Aspartate receptor (NMDAR) regulates cell competition

Agnes Regina Banreti and Pascal Meier

The Breast Cancer Now Toby Robins Research Centre, Institute of Cancer Research, Mary-Jean Mitchell Green Building, Chester Beatty Laboratories, Fulham Road, London SW3 6JB, UK

Abstract: In a certain cellular microenvironment a Darwinian-like selection between adjacent cell populations leads to the growth of the stronger population at the expense of the weaker. This physiological phenomena -termed cell competition- has important roles in the maintenance of tissue integrity and ensures optimal organ fitness by eliminating potentially dangerous malfunctioning cells.

Such context-dependent elimination of relatively weaker cells can be modelled by differential local expression of oncoproteins*: More competitive “winner” cells eliminate wild-type “loser” cells, via inducing their death and replace them through compensatory proliferation.

N-Methyl-D-Aspartate receptor (NMDAR) is best known for its role in associative learning and long-term memory formation. We now find that the evolutionary conserved NMDAR of the brain is surprisingly also expressed in the fruit fly epithelia and responsible for the maintenance of epithelial tissue integrity via regulating cell competition.

While down-regulation of NMDAR has no deleterious effect in a homotypic context, in a heterotypic context depletion of NMDAR results in cell death and elimination. Furthermore, we show that tumorous cells require intact NMDAR for their survival. Consequently, they are killed by their wild-type neighbours when fail to express NMDAR.

Importantly, NMDAR is activated by various amino acids and to date, it is the only known receptor that has enantioselective binding affinity for endogenous ligands including L-Glutamate, D-Serine and D-Aspartate. We show that treatment with the endogenous ligand D-Aspartate induces the selective elimination of cells expressing oncogene. Our time-laps studies on ex vivo developing organs suggest that D- Aspartate might inhibit nuclear Ca 2+ -signalling.

Our current findings provide a better understanding of the molecular events that govern the complex interplay between adjacent cells to maintain epithelial fitness. Further, we aim to use our knowledge to manipulate NMDAR to turn cancerous cells into losers, assisting their elimination by neighbouring normal cells.

* Oncoprotein: any protein that is encoded by an oncogene and contributes to the conversion of a normal cell into a cancerous cell when expressed at high levels.


Friday 16 March, 12:00pm

Probing molecular chirality, learning about solvation

Dr. Christian Merten

Ruhr-University Bochum, Organic Chemistry 2, 44801 Bochum


Abstract: Molecular asymmetry can be probed by a variety of experimental techniques, which all rely on the different interaction of chiral matter with circular polarized light. These chiroptical spectroscopies can distinguish the two mirror imaged forms of chiral molecules, but are also generally much more sensitive to the three-dimensional structures of chiral molecules than techniques using non-polarized (“achiral”) light. As the chiral molecules are typically characterized in solution, their asymmetric shape also extends towards the first layer of solvent molecules, the first solvation-shell. The optical rotation of propylene oxide, for instance, has been shown to depend strongly on the solvent. [1] This solvent-dependence originates from the chiral spatial arrangement which the solvent molecules adopt around the asymmetric solute. [2]

Modern chiroptical methods like vibrational circular dichroism (VCD) spectroscopy, which measures the difference in the absorbance of left- and right-circularly polarized light during vibrational transitions, have unraveled many more interesting solvent effects. The most intriguing example is the induction of vibrational optical activity to solvent molecules. Due to strong intermolecular interactions, the solvent molecules become, for a short period of time, part of a chiral entity, which in turn results in the generation of a VCD signal for their vibrations. [3]

In this talk, I will give a short introduction to VCD spectroscopy, and introduce some examples which highlight how probing the asymmetry of the solute can help us to understand both the structure of the solute in the solvent and the interactions of the solvent with the solute. [4]

References:


Friday 16 March, 1:40pm

Topological Asymmetries

Prof. Dr. Eric Akkermans

Physics Department, Technion, Haifa, Israel


Abstract: A well spread tendency often mixes the notions of symmetry and of topology. Although topological ideas are better understandable when presented on highly symmetric objects, topology is precisely what remains once most of these symmetries have been washed out while leaving asymmetric structures. It is this specific strength of topology which underlies a large part of its relevance and interest in physics. We shall discuss some emblematic phenomena such as the quantum Hall effect and quantum anomalies at an elementary level to exemplify some of these fascinating topological features.

 


Friday 16 March, 2:30pm

Left-Right asymmetry in Drosophila: from molecular to organism chirality

Dr. Stéphane Noselli

Institute of Biology Valrose iBV Nice, Université Côte d’Azur, CNRS, Inserm, Parc Valrose, 06108 Nice

Abstract: Breaking Left-Right (LR) symmetry in Bilateria embryos is a major event in body plan organization. Establishment of LR asymmetry is essential for body handedness, directional looping of internal organs (heart, gut...) and differentiation of the heart and brain. Many syndromes and defects are associated with aberrant LR asymmetry in human.

We have characterized the LR body axis in Drosophila through the identification of myosin ID (myoID) as a unique situs inversus gene. The myoID (aka Myo31F) gene is a major LR determinant in flies that is required for dextral coiling of organs (genitalia, hindgut, testis). In the absence of myoID, flies show an inverted phenotype with organs undergoing sinistral morphogenesis. Our recent work revealed a direct coupling between the LR determinant MyoID and the atypical cadherin Dachsous for propagation of LR information to target tissues, providing the first evidence for a role of the Fat/Ds PCP pathway in LR asymmetry.

Our ongoing work aims at addressing the following questions: i) what is the molecular and cellular function of myoID, ii) what is the nature of the molecular coupling between the myoID LR determinant and Dachsous/PCP?, and, iii) what is the evolutionary conservation of myoID function in vertebrates (zebrafish, xenopus) LR asymmetry?

I will present novel results showing that myoID is not only necessary for establishing LR asymmetry but is also sufficient to generate de novo LR asymmetry, making it a true LR determinant. Furthermore, molecular studies show that MyoID interaction with actin is chiral, and that its function is conserved in vertebrates. Altogether, our results reveal that the MyoID system is a major chirality determinant essential for orienting the LR axis in both vertebrates and invertebrates.

References:


Friday 16 March, 3:30pm

Scale and asymmetry in spatial analysis

Didier Josselin

CNRS UMR ESPACE 7300, Université d'Avignon et des Pays de Vaucluse, 74, rue Louis Pasteur, 84000 Avignon cedex

Abstract: One of the main goals of geography is to identify simple or complex objects (from cities to houses, from forests to trees, from mountains to buttes...) and their spatial organisation at a given scale. More precisely, scale has two main meanings. The first meaning is the ratio between the size of the geographical objects on the map or the screen and their real size in the field. The second meaning is the accuracy with which those objects are described and delineated. It can be the minimal grain below which the geographical object becomes indivisible or can be identified as a whole and unique entity, at least with this measurement at this scale. Moreover, scale can be appraised in two complementary dimensions. It can be fixed by a value as explained above. But also it can vary through a set of different scale values. Somehow, the (global) scale is a ladder with a series of steps, where each step is also condidered as a (local) scale.

Related to these definitions, geographers and spatial analysts use to study objects through scales by downscaling, upscaling or mixing spatial partitions at a given local scale. In all these analysis processes, the object shapes, but also the different spatial statistics used to describe them, change significantly along the scales. Depending on scale, objects alternate between symmetry to asymmetry. More strangely, associated statistics can follow the same balancing trend and infer opposite results and statements according to the encompassed data and the given scale.

So called ecological inference fallacy, this issue [1], basically a (re)sampling problem, has different faces: Simpson's paradox in economy, Robinson's ecological inference in sociology [6], aggregation and ecological effect in environmental science and statistics, Modifiable Areal Unit Problem (MAUP [5]) in geography. All those problems may be comprised within a conceptual umbrella: the Change Of Support Problem (COSP [2,4]) that induces many sets of data clusters. Until today there does not exist any proven solution to this problem [3], generalized to all sciences, including social science, especially geography and spatial analysis. Indeed, it has a major impact in spatial planning, because geographers mainly handle data spread over territories that can be partitioned in so many ways.

Our presentation will deal with this problem, will show how strong can be the balancing process from symmetry to asymmetry in space and statistics and how, at least we can be aware of, even use it in spatial analysis.

References:


Friday 16 March, 3:50pm

Asymmetry along the way. Applications and conceptualizations for the morphology of urban fabrics

Giovanni Fusco¹, Alessandro Araldi¹, Stefano Borgo², Rossella Stufano³

¹ Université Côte d’Azur, CNRS, ESPACE, France

² Laboratory for Applied Ontology, ISTC CNR, Trento, Italy

³ Politecnico di Bari, Bari, Italy

Abstract: This contribution is an inter-disciplinary work between urban geographers, architects and computer scientists. It highlights the interest of morphological asymmetry in the study of urban form, presents a real-world case study where asymmetries are detected and quantified through a geoprocessing approach, and proposes a more general conceptualization of the use of morphological asymmetry. It will be shown that the methodology used for detecting morphological asymmetries derives from one possible conceptualization and that other options are open to the analysis of urban form.

Urban form is the expression of a society. The design producing it incrementally is the expression of the society which lives it, an organic sum of the invariant morphological features of a group of buildings and street arrangements from the same time period and cultural area. Saverio Muratori called this principle "a common creative effort" [1], that interact with the peculiarities of the environmental region and produces specific urban fabrics. Interactions between man-made features and physical features (topography, water bodies, etc.) can produce geometric asymmetries in urban fabrics, even when the analysis is carried out at the scale of urban fragments (morphological analysis) without considering details of architectural design of individual buildings (typological analysis). Other asymmetries are more man-made: they can result from the insertion of exceptional urban objects in a given fabric or from the juxtaposition of different urban fabrics. Geometric asymmetry in urban form can thus be an interesting input in morphological analysis, revealing the effort that a given society puts in producing, maintaining or absorbing symmetries and asymmetries.

A new geoprocessing method has recently been proposed [2,3] for the identification of the form of urban fabrics through geoprocessing of morphological indicators in proximity bands around street segments: Multiple Fabric Assessment (MFA). The core of MFA is the analysis of perceivable urban morphologies by pedestrians moving on the street. The MFA framework can be used also to identify asymmetries in urban fabrics. For many morphological indicators, it is indeed possible to calculate separate values for the two proximity bands on each side of a street segment. We can thus evaluate, for each indicator, the degree of geometric asymmetry characterizing urban forms between the two sides of the street.

In order to calculate an overall asymmetry score, the values of each morphological difference on the two sides of the same street segment must be normalized following different conceptualizations of the asymmetry within its context of detection:

  1. the street segment itself surrounding the pedestrian (hyperlocal context);
  2. the neighboring streets that can be explored by the pedestrian (local context);
  3. the city as a whole (global context).

The empirical results from the French Riviera show that normalization through hyperlocal values seems more capable of identifying discontinuities in the urban morphological landscape. On the contrary, normalization through global values highlights the many asymmetric features characterizing dense and traditional urban fabrics.

A general conceptualization of geometric asymmetries in urban form can be proposed. Its aim is to identify the conceptualization of urban space and geometric asymmetries underlying the MFA application.

The opposing notions of symmetry and asymmetry (S/A) are an informational characteristic that we use to understand/simplify a more complex system (here the urban morphological system). As Brading and Castellani put it: “One of the most important roles played by symmetry is that of classification” [4]. S/A relations are always applied to the parts of a system, i.e., to a system seen as a complex entity, since they are essentially comparison relations. System partitioning (via the distinction of subparts, or of a center and its surrounding areas) is thus a necessary phase to characterize the system through S/A relations. Three kinds of S/A relations could be proposed for analysis of the (static) urban system:

MFA analysis is based on a partitioning of urban space in proximity bands around street segments. The pedestrian is supposed to move along an ideal centerline looking left and right as he explores urban space. The analysis of Axial S/A is thus natural in the MFA approach, even if the axis is not necessarily a straight line (it follows the pedestrian path) and the detected S/A is not necessarily geometric but deals more often with object spatial distribution and object attributes S/A.

The perception of urban morphologies from more planar features (like public squares and gardens) is not well taken care of by the MFA approach. Point S/A relations could be more convenient to detect the morphological characteristics around these features.

References:


Friday 16 March, 4:40pm

Asymmetries in Astrophysics Arising on the Path to the Search for Life in the Universe

Dr. William C. Danchi¹, Dr. Bruno Lopez²

¹ NASA Goddard Space Flight Center, USA

² Observatoire de la Côte d’Azur, Nice, FR

Abstract: The search for life around exoplanets in nearby solar-type stars is a complex interdisciplinary enterprise. Asymmetries arise in many ways. One example is how the morphology of disks around young stars is modified by the presence of a yet unseen exoplanet. Another example is the extreme difference in the mass and luminosity of the host star of an exoplanet and an exoplanet itself. Such an extreme asymmetry can yield an exoplanet full of life, like the Earth, if viewed from another nearby star, or the exoplanet can be a burned out lifeless husk, depending on a variety of phenomena including the activity of the host star, its evolution, and material the star ejects such as energetic protons and electrons, among other factors. These energetic particles penetrate the atmosphere of an exoplanet and modify the chemistry of the atmosphere, enhancing the production of molecules that are the building blocks of life.

In this talk we give a broad overview of several astrophysical phenomena relevant to the question of whether or not life exists in planets in nearby stellar systems. We highlight the interdisciplinary nature of current investigations across multiple fields, including astrophysics, heliophysics, planetary science, and Earth science.


Friday 16 March, 5:00pm

On the Origin of Hemispheric Specialization for Language: Gestural and Brain Asymmetries in Primates

Adrien Meguerditchian

Laboratoire de Psychologie Cognitive UMR7290, CNRS, Aix-Marseille Univ, Brain and Language Research Institute (BLRI), Institute of Lang

Abstract: Language is an unique system of communication in humans and involve complex hemispheric specialization of the brain. Among such a neural network, some regions play a key-role such as the motor cortex, Broca area and the Planum Temporale. Given the phylogenetic proximity between humans and nonhuman primate species, the investigation of the lateralization of communicative system as well as the cortical organization in apes and monkeys within a comparative approach might enable detecting the potential precursors of hemispheric specialization for language processing in our common ancestors. Most of these comparative studies have focused on great apes, particularly chimpanzees and have reported, similarly than in humans, leftward asymmetries of the planum temporale, but not in non- hominidae species.

In previous studies we found that both chimpanzees and baboons - a non-hominidae Old World monkey species - showed a robust predominance of right-hand use for communicative manual gestures specifically, indicating that the left-hemisphere might be dominant for the control of gestural communication.

In follow up brain studies using MRI, we investigate the anatomical brain asymmetries of some of these key-cortical regions for language in olive baboons (Papio anubis). At the Centre IRMf of Marseille, 96 anatomical images were acquired in vivo from anesthetized baboons housed in social groups at the Station de Primatologie CNRS. The depths of the central sulcus (CS) following the motor cortex and of the superior temporal sulcus (STS) in the auditory cortex have been quantified in both hemispheres in each subject using automatic BrainVisa procedures. For the planum temporale (PT), the surface areas of this region were manually traced on a computer in both hemispheres. We found, for the first time in a non-hominidae species, human-like significant neuroanatomical asymmetries toward the left hemisphere for the PT surface and toward the right hemisphere for the STS depth. Interestingly, inter-hemispheric asymmetries of the CS depth were shown to be significantly driven by the contralateral direction of handedness (i.e., left- or right- hand), which were previously assessed in those individuals using a bimanual coordinated task.

These collective findings suggest that the continuity of hemispheric specialization between apes and humans extend to baboons for key structures of language and handedness. These findings argue that prerequisites of hemispheric specialization for language and handedness might be dated back, not to the common ancestor of hominidae at 14-17 million years ago, but to the common ancestor of Catarrhini at 30-40 million years ago.


Friday 16 March, 5:40pm

Asymmetry of Inositol Phosphates

Prof. Dr. Henning Jessen

Albert-Ludwigs University of Freiburg, Department of Chemistry and Pharmacy, Albertstrasse 21, 79104 Freiburg, Germany


Abstract: Inositol phosphates (InsP) and their derived lipids (PtdInsP) play several key roles in cellular biology as signals. They are involved, for example, in the release of calcium ions from intracellular stores to amplify and shape signals, but also in the regulation of body weight, glucose uptake, and insulin secretion. [1]

The myo-inositol scaffold has an internal plane of symmetry (blue) that dissects the 2/5 position of the inositol ring. Such molecules are referred to as meso-compounds and have several interesting stereochemical features. Phosphorylation in a position not lying within the plane of symmetry leads to desymmetrization and the generation of mirror images called enantiomers that can have different biological activities. [2, 3]

The desymmetrization of inositol using chemical approaches is still a challenge. Moreover, the correct assignment of different isomers, especially enantiomers, is a difficult task requiring special techniques. Yet, to correctly assign biological functions to the several possible isomers and to chemically synthesize tools to study the biology of these compounds, new desymmetrization techniques and approaches for correct stereochemical assignments are required.

This study reports on new approaches for the asymmetric chemical synthesis of inositol phosphates and their derivatives. Moreover, a new method how the absolute configuration can be assigned using 31 P NMR spectroscopy and chiral solvating agents will be discussed. [4] Finally, the biological relevance of several natural and unnatural inositol phosphates will be discussed in the context of their symmetry. [5, 6]

References:


Friday 16 March, 6:00pm

Particularities about brain asymmetry and lexicosemantic processing in giftedness: a trans-disciplinary approach

Marie-Noële Magnié-Mauro, Assoc. Prof., MD-PhD¹ and Olivier Meste, Prof., PhD², Hervé Rix, Prof., PhD², Lucile Chanquoy, Prof., PhD¹, Sophie Guetat, PhD Student¹, Balkine Khaddoumi, Assoc. Prof., PhD³

¹ BCL, UMR 7320 UNS CNRS, UCA

² I3S, UMR 7271 UNS CNRS, UCA

³ ENSIT, University of Tunis, Tunisia

Abstract: Asymmetry in hemispheric specialization of brain is nowadays well known with classically a specialization of the left hemisphere for linguistic processes and a specialization of the right hemisphere for the visuospatial processes in right-handers. Giftedness is associated with particularities not only in cognitive style but also in lexicosemantic processing.

The developmental Event-Related Potentials (ERP) studies showed arguments in line not only with an accelerated cognitive maturation in gifted children but also in favour of hemispheric specialization particularities with an enhanced involvement of the right hemisphere during both verbal and non-verbal tasks [1].

This unusual asymmetry in hemispheric specialization is far from being understood even if it seems to be related to particularities in semantic processing.

To further track the lexicosemantic particularities in giftedness, a trans-disciplinary approach is used to optimize the ERP analysis, and especially of the N400 component. We used the new methods developed by the SIS Team of I3S for the processing, analysis and modelling of biomedical signals connected to Functional Data Analysis, channel-by-channel: Integral Shape Averaging (ISA) [2] and alternative methods (CISA, Core Shape to extract and model the ERP shape and its variability.

The collaboration between the researchers in psycholinguistic and in biomedical signal processing allowed to better characterize the neurophysiological events in gifted children in order to better understand the complex relationships between the unusual asymmetry-related lexicosemantic particularities in giftedness.

References:


Friday 16 March, 6:20pm

Left brain, right brain: lessons from neuroimaging

Emmanuel Mellet, MD, PhD.

Institut des Maladies Neurodégénératives IMN, UMR 5293, Univ. Bordeaux, CNRS, CEA 33000 Bordeaux France


Abstract: Asymmetry is a fundamental characteristic of the brain organization. It concerns both its anatomy and its functions and gives birth to the concept of hemispheric specialization (HS). HS is widespread among vertebrates, but in Humans, it gives rise to specific features including a high prevalence of right-handers and the capacity to acquire language. HS also includes the mechanisms that enable the inter-hemispheric communication and coordination.

HS is characterized by an inter-subject variability but the factors explaining this variability are still largely unknown. In this presentation, I propose to illustrate how neuroimaging have shed light on the asymmetric organization of the human brain and on its variability. In particular, our team has acquired a neuroimaging database (BIL&GIN), which included 300 participants balanced for sex and handedness (Mazoyer et al, 2016). In addition to Magnetic Resonance Imaging (MRI) of brain structures, this database comprised MRI functional acquisitions during various tasks of language, visuospatial and motor tasks (Figure 1). It also included an extensive assessment of participant’s cognitive performances in various domains. It thus constitutes a specifically designed and valuable tool to investigate the asymmetries and their variability in healthy subjects.

References:
Mazoyer, B, Mellet, E, Perchey, G, Zago, L, Crivello, F, Jobard, G, Delcroix, N, Vigneau, M, Leroux, G, Petit, L, Joliot, M, Tzourio-Mazoyer, N (2016) BIL&GIN: A neuroimaging, cognitive, behavioral, and genetic database for the study of human brain lateralization. Neuroimage, 124:1225–1231.