Project acronym AttentionCircuits
Project Modulation of neocortical microcircuits for attention
Researcher (PI) Johannes Jakob Letzkus
Host Institution (HI) MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary At every moment in time, the brain receives a vast amount of sensory information about the environment. This makes attention, the process by which we select currently relevant stimuli for processing and ignore irrelevant input, a fundamentally important brain function. Studies in primates have yielded a detailed description of how attention to a stimulus modifies the responses of neuronal ensembles in visual cortex, but how this modulation is produced mechanistically in the circuit is not well understood. Neuronal circuits comprise a large variety of neuron types, and to gain mechanistic insights, and to treat specific diseases of the nervous system, it is crucial to characterize the contribution of different identified cell types to information processing. Inhibition supplied by a small yet highly diverse set of interneurons controls all aspects of cortical function, and the central hypothesis of this proposal is that differential modulation of genetically-defined interneuron types is a key mechanism of attention in visual cortex. To identify the interneuron types underlying attentional modulation and to investigate how this, in turn, affects computations in the circuit we will use an innovative multidisciplinary approach combining genetic targeting in mice with cutting-edge in vivo 2-photon microscopy-based recordings and selective optogenetic manipulation of activity. Importantly, a key set of experiments will test whether the observed neuronal mechanisms are causally involved in attention at the level of behavior, the ultimate readout of the computations we are interested in. The expected results will provide a detailed, mechanistic dissection of the neuronal basis of attention. Beyond attention, selection of different functional states of the same hard-wired circuit by modulatory input is a fundamental, but poorly understood, phenomenon in the brain, and we predict that our insights will elucidate similar mechanisms in other brain areas and functional contexts.
Summary
At every moment in time, the brain receives a vast amount of sensory information about the environment. This makes attention, the process by which we select currently relevant stimuli for processing and ignore irrelevant input, a fundamentally important brain function. Studies in primates have yielded a detailed description of how attention to a stimulus modifies the responses of neuronal ensembles in visual cortex, but how this modulation is produced mechanistically in the circuit is not well understood. Neuronal circuits comprise a large variety of neuron types, and to gain mechanistic insights, and to treat specific diseases of the nervous system, it is crucial to characterize the contribution of different identified cell types to information processing. Inhibition supplied by a small yet highly diverse set of interneurons controls all aspects of cortical function, and the central hypothesis of this proposal is that differential modulation of genetically-defined interneuron types is a key mechanism of attention in visual cortex. To identify the interneuron types underlying attentional modulation and to investigate how this, in turn, affects computations in the circuit we will use an innovative multidisciplinary approach combining genetic targeting in mice with cutting-edge in vivo 2-photon microscopy-based recordings and selective optogenetic manipulation of activity. Importantly, a key set of experiments will test whether the observed neuronal mechanisms are causally involved in attention at the level of behavior, the ultimate readout of the computations we are interested in. The expected results will provide a detailed, mechanistic dissection of the neuronal basis of attention. Beyond attention, selection of different functional states of the same hard-wired circuit by modulatory input is a fundamental, but poorly understood, phenomenon in the brain, and we predict that our insights will elucidate similar mechanisms in other brain areas and functional contexts.
Max ERC Funding
1 466 505 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym C.o.C.O.
Project Circuits of con-specific observation
Researcher (PI) Marta De Aragao Pacheco Moita
Host Institution (HI) FUNDACAO D. ANNA SOMMER CHAMPALIMAUD E DR. CARLOS MONTEZ CHAMPALIMAUD
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary A great deal is known about the neural basis of associative fear learning. However, many animal species are able to use social cues to recognize threats, a defence mechanism that may be less costly than learning from self-experience. We have previously shown that rats perceive the cessation of movement-evoked sound as a signal of danger and its resumption as a signal of safety. To study transmission of fear between rats we assessed the behavior of an observer while witnessing a demonstrator rat display fear responses. With this paradigm we will take advantage of the accumulated knowledge on learned fear to investigate the neural mechanisms by which the social environment regulates defense behaviors. We will unravel the neural circuits involved in detecting the transition from movement-evoked sound to silence. Moreover, since observer rats previously exposed to shock display observational freezing, but naive observer rats do not, we will determine the mechanism by which prior experience contribute to observational freezing. To this end, we will focus on the amygdala, crucial for fear learning and expression, and its auditory inputs, combining immunohistochemistry, pharmacology and optogenetics. Finally, as the detection of and responses to threat are often inherently social, we will study these behaviors in the context of large groups of individuals. To circumvent the serious limitations in using large populations of rats, we will resort to a different model system. The fruit fly is the ideal model system, as it is both amenable to the search for the neural mechanism of behavior, while at the same time allowing the study of the behavior of large groups of individuals. We will develop behavioral tasks, where conditioned demonstrator flies signal danger to other naïve ones. These experiments unravel how the brain uses defense behaviors as signals of danger and how it contributes to defense mechanisms at the population level.
Summary
A great deal is known about the neural basis of associative fear learning. However, many animal species are able to use social cues to recognize threats, a defence mechanism that may be less costly than learning from self-experience. We have previously shown that rats perceive the cessation of movement-evoked sound as a signal of danger and its resumption as a signal of safety. To study transmission of fear between rats we assessed the behavior of an observer while witnessing a demonstrator rat display fear responses. With this paradigm we will take advantage of the accumulated knowledge on learned fear to investigate the neural mechanisms by which the social environment regulates defense behaviors. We will unravel the neural circuits involved in detecting the transition from movement-evoked sound to silence. Moreover, since observer rats previously exposed to shock display observational freezing, but naive observer rats do not, we will determine the mechanism by which prior experience contribute to observational freezing. To this end, we will focus on the amygdala, crucial for fear learning and expression, and its auditory inputs, combining immunohistochemistry, pharmacology and optogenetics. Finally, as the detection of and responses to threat are often inherently social, we will study these behaviors in the context of large groups of individuals. To circumvent the serious limitations in using large populations of rats, we will resort to a different model system. The fruit fly is the ideal model system, as it is both amenable to the search for the neural mechanism of behavior, while at the same time allowing the study of the behavior of large groups of individuals. We will develop behavioral tasks, where conditioned demonstrator flies signal danger to other naïve ones. These experiments unravel how the brain uses defense behaviors as signals of danger and how it contributes to defense mechanisms at the population level.
Max ERC Funding
1 412 376 €
Duration
Start date: 2013-12-01, End date: 2018-11-30
Project acronym CeMoMagneto
Project The Cellular and Molecular Basis of Magnetoreception
Researcher (PI) David Anthony Keays
Host Institution (HI) FORSCHUNGSINSTITUT FUR MOLEKULARE PATHOLOGIE GESELLSCHAFT MBH
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary Each year millions of animals undertake remarkable migratory journeys, across oceans and through hemispheres, guided by the Earth’s magnetic field. The cellular and molecular basis of this enigmatic sense, known as magnetoreception, remains an unsolved scientific mystery. One hypothesis that attempts to explain the basis of this sensory faculty is known as the magnetite theory of magnetoreception. It argues that magnetic information is transduced into a neuronal impulse by employing the iron oxide magnetite (Fe3O4). Current evidence indicates that pigeons employ a magnetoreceptor that is associated with the ophthalmic branch of the trigeminal nerve and the vestibular system, but the sensory cells remain undiscovered. The goal of this ambitious proposal is to discover the cells and molecules that mediate magnetoreception. This overall objective can be divided into three specific aims: (1) the identification of putative magnetoreceptive cells (PMCs); (2) the cellular characterisation of PMCs; and (3) the discovery and functional ablation of molecules specific to PMCs. In tackling these three aims this proposal adopts a reductionist mindset, employing and developing the latest imaging, subcellular, and molecular technologies.
Summary
Each year millions of animals undertake remarkable migratory journeys, across oceans and through hemispheres, guided by the Earth’s magnetic field. The cellular and molecular basis of this enigmatic sense, known as magnetoreception, remains an unsolved scientific mystery. One hypothesis that attempts to explain the basis of this sensory faculty is known as the magnetite theory of magnetoreception. It argues that magnetic information is transduced into a neuronal impulse by employing the iron oxide magnetite (Fe3O4). Current evidence indicates that pigeons employ a magnetoreceptor that is associated with the ophthalmic branch of the trigeminal nerve and the vestibular system, but the sensory cells remain undiscovered. The goal of this ambitious proposal is to discover the cells and molecules that mediate magnetoreception. This overall objective can be divided into three specific aims: (1) the identification of putative magnetoreceptive cells (PMCs); (2) the cellular characterisation of PMCs; and (3) the discovery and functional ablation of molecules specific to PMCs. In tackling these three aims this proposal adopts a reductionist mindset, employing and developing the latest imaging, subcellular, and molecular technologies.
Max ERC Funding
1 499 752 €
Duration
Start date: 2014-04-01, End date: 2019-03-31
Project acronym CHEMOSENSORYCIRCUITS
Project Function of Chemosensory Circuits
Researcher (PI) Emre Yaksi
Host Institution (HI) NORGES TEKNISK-NATURVITENSKAPELIGE UNIVERSITET NTNU
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary Smell and taste are the least studied of all senses. Very little is known about chemosensory information processing beyond the level of receptor neurons. Every morning we enjoy our coffee thanks to our brains ability to combine and process multiple sensory modalities. Meanwhile, we can still review a document on our desk by adjusting the weights of numerous sensory inputs that constantly bombard our brains. Yet, the smell of our coffee may remind us that pleasant weekend breakfast through associative learning and memory. In the proposed project we will explore the function and the architecture of neural circuits that are involved in olfactory and gustatory information processing, namely habenula and brainstem. Moreover we will investigate the fundamental principles underlying multimodal sensory integration and the neural basis of behavior in these highly conserved brain areas.
To achieve these goals we will take an innovative approach by combining two-photon calcium imaging, optogenetics and electrophysiology with the expanding genetic toolbox of a small vertebrate, the zebrafish. This pioneering approach will enable us to design new types of experiments that were unthinkable only a few years ago. Using this unique combination of methods, we will monitor and perturb the activity of functionally distinct elements of habenular and brainstem circuits, in vivo. The habenula and brainstem are important in mediating stress/anxiety and eating habits respectively. Therefore, understanding the neural computations in these brain regions is important for comprehending the neural mechanisms underlying psychological conditions related to anxiety and eating disorders. We anticipate that our results will go beyond chemical senses and contribute new insights to the understanding of how brain circuits work and interact with the sensory world to shape neural activity and behavioral outputs of animals.
Summary
Smell and taste are the least studied of all senses. Very little is known about chemosensory information processing beyond the level of receptor neurons. Every morning we enjoy our coffee thanks to our brains ability to combine and process multiple sensory modalities. Meanwhile, we can still review a document on our desk by adjusting the weights of numerous sensory inputs that constantly bombard our brains. Yet, the smell of our coffee may remind us that pleasant weekend breakfast through associative learning and memory. In the proposed project we will explore the function and the architecture of neural circuits that are involved in olfactory and gustatory information processing, namely habenula and brainstem. Moreover we will investigate the fundamental principles underlying multimodal sensory integration and the neural basis of behavior in these highly conserved brain areas.
To achieve these goals we will take an innovative approach by combining two-photon calcium imaging, optogenetics and electrophysiology with the expanding genetic toolbox of a small vertebrate, the zebrafish. This pioneering approach will enable us to design new types of experiments that were unthinkable only a few years ago. Using this unique combination of methods, we will monitor and perturb the activity of functionally distinct elements of habenular and brainstem circuits, in vivo. The habenula and brainstem are important in mediating stress/anxiety and eating habits respectively. Therefore, understanding the neural computations in these brain regions is important for comprehending the neural mechanisms underlying psychological conditions related to anxiety and eating disorders. We anticipate that our results will go beyond chemical senses and contribute new insights to the understanding of how brain circuits work and interact with the sensory world to shape neural activity and behavioral outputs of animals.
Max ERC Funding
1 499 471 €
Duration
Start date: 2014-04-01, End date: 2019-03-31
Project acronym COGOPTO
Project The role of parvalbumin interneurons in cognition and behavior
Researcher (PI) Eva Marie Carlen
Host Institution (HI) KAROLINSKA INSTITUTET
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary Cognition is a collective term for complex but sophisticated mental processes such as attention, learning, social interaction, language production, decision making and other executive functions. For normal brain function, these higher-order functions need to be aptly regulated and controlled, and the physiology and cellular substrates for cognitive functions are under intense investigation. The loss of cognitive control is intricately related to pathological states such as schizophrenia, depression, attention deficit hyperactive disorder and addiction.
Synchronized neural activity can be observed when the brain performs several important functions, including cognitive processes. As an example, gamma activity (30-80 Hz) predicts the allocation of attention and theta activity (4-12 Hz) is tightly linked to memory processes. A large body of work indicates that the integrity of local and global neural synchrony is mediated by interneuron networks and actuated by the balance of different neuromodulators.
However, much knowledge is still needed on the functional role interneurons play in cognitive processes, i.e. how the interneurons contribute to local and global network processes subserving cognition, and ultimately play a role in behavior. In addition, we need to understand how neuro-modulators, such as dopamine, regulate interneuron function.
The proposed project aims to functionally determine the specific role the parvalbumin interneurons and the neuromodulator dopamine in aspects of cognition, and in behavior. In addition, we ask the question if cognition can be enhanced.
We are employing a true multidisciplinary approach where brain activity is recorded in conjunctions with optogenetic manipulations of parvalbumin interneurons in animals performing cognitive tasks. In one set of experiments knock-down of dopamine receptors specifically in parvalbumin interneurons is employed to probe how this neuromodulator regulate network functions.
Summary
Cognition is a collective term for complex but sophisticated mental processes such as attention, learning, social interaction, language production, decision making and other executive functions. For normal brain function, these higher-order functions need to be aptly regulated and controlled, and the physiology and cellular substrates for cognitive functions are under intense investigation. The loss of cognitive control is intricately related to pathological states such as schizophrenia, depression, attention deficit hyperactive disorder and addiction.
Synchronized neural activity can be observed when the brain performs several important functions, including cognitive processes. As an example, gamma activity (30-80 Hz) predicts the allocation of attention and theta activity (4-12 Hz) is tightly linked to memory processes. A large body of work indicates that the integrity of local and global neural synchrony is mediated by interneuron networks and actuated by the balance of different neuromodulators.
However, much knowledge is still needed on the functional role interneurons play in cognitive processes, i.e. how the interneurons contribute to local and global network processes subserving cognition, and ultimately play a role in behavior. In addition, we need to understand how neuro-modulators, such as dopamine, regulate interneuron function.
The proposed project aims to functionally determine the specific role the parvalbumin interneurons and the neuromodulator dopamine in aspects of cognition, and in behavior. In addition, we ask the question if cognition can be enhanced.
We are employing a true multidisciplinary approach where brain activity is recorded in conjunctions with optogenetic manipulations of parvalbumin interneurons in animals performing cognitive tasks. In one set of experiments knock-down of dopamine receptors specifically in parvalbumin interneurons is employed to probe how this neuromodulator regulate network functions.
Max ERC Funding
1 400 000 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym DARKSIDE
Project Harnessing the Dark Side of Protein Folding: Manipulating Aggregation for Recombinant Protein Production
Researcher (PI) Daniel Kaganovich
Host Institution (HI) UNIVERSITAETSMEDIZIN GOETTINGEN - GEORG-AUGUST-UNIVERSITAET GOETTINGEN - STIFTUNG OEFFENTLICHEN RECHTS
Call Details Starting Grant (StG), LS9, ERC-2013-StG
Summary Nearly all desirable biological activities, whether for the purposes of nutrition, pharmacology, biofuel production, or waste disposal, can be carried out by proteins. Nature has furnished a vast array of bioactive and biocatalytic tools, and with the advent of rational protein design nearly any imaginable bioactivity is at our fingertips. There is, therefore, a pressing need for cost-effective, safe, and easily scalable strategies for generating Recombinant Proteins (rProteins). The main bottleneck for mass-producing a whole host of valuable biologically active rProteins is the difficulty of recovering functional proteins from expression hosts.
This difficulty stems largely from the lack of sufficient know-how for manipulating protein biogenesis in the cell. The key component of protein biology, whether in the context of rProtein production or cell viability, is enabling a protein to achieve its proper folding state. Most proteins do not fold on their own – they require the assistance of a vast network of folding managers, or chaperones. The cellular chaperone machinery not only assists protein folding, it also carries out quality control, ensuring that proteins that are damaged or unable to fold for other reasons are properly disposed of through degradation or protective aggregation.
The aim of this proposal is to understand the protein biosynthetic pathway in sufficient detail, so as to be able to manipulate its overall function. My eventual goal is to exert control over folding and aggregation in order to produce higher yields of functional rProteins in eukaryotes. The biotechnological strategy will consist of: 1. Manipulating aggregation to remove damaged endogenous proteins from the folding proteome, thus diverting more resources to the folding of rProteins; 2. Manipulating the allocation of cellular chaperone resources between folding, degradation, and aggregation; 3. Utilizing aggregates to produce substantially higher amounts of functional rProteins.
Summary
Nearly all desirable biological activities, whether for the purposes of nutrition, pharmacology, biofuel production, or waste disposal, can be carried out by proteins. Nature has furnished a vast array of bioactive and biocatalytic tools, and with the advent of rational protein design nearly any imaginable bioactivity is at our fingertips. There is, therefore, a pressing need for cost-effective, safe, and easily scalable strategies for generating Recombinant Proteins (rProteins). The main bottleneck for mass-producing a whole host of valuable biologically active rProteins is the difficulty of recovering functional proteins from expression hosts.
This difficulty stems largely from the lack of sufficient know-how for manipulating protein biogenesis in the cell. The key component of protein biology, whether in the context of rProtein production or cell viability, is enabling a protein to achieve its proper folding state. Most proteins do not fold on their own – they require the assistance of a vast network of folding managers, or chaperones. The cellular chaperone machinery not only assists protein folding, it also carries out quality control, ensuring that proteins that are damaged or unable to fold for other reasons are properly disposed of through degradation or protective aggregation.
The aim of this proposal is to understand the protein biosynthetic pathway in sufficient detail, so as to be able to manipulate its overall function. My eventual goal is to exert control over folding and aggregation in order to produce higher yields of functional rProteins in eukaryotes. The biotechnological strategy will consist of: 1. Manipulating aggregation to remove damaged endogenous proteins from the folding proteome, thus diverting more resources to the folding of rProteins; 2. Manipulating the allocation of cellular chaperone resources between folding, degradation, and aggregation; 3. Utilizing aggregates to produce substantially higher amounts of functional rProteins.
Max ERC Funding
1 639 400 €
Duration
Start date: 2013-11-01, End date: 2019-10-31
Project acronym ErgOX
Project Enzymology of oxidative sulfur transfers
Researcher (PI) Florian Peter Seebeck
Host Institution (HI) UNIVERSITAT BASEL
Call Details Starting Grant (StG), LS9, ERC-2013-StG
Summary Oxidative stress causes cancer, cardiovascular, neurodegenerative and infective disease. Much of cellular oxidative stress is mediated, communicated, mitigated or amplified by a complex system of sulphur containing small metabolites or protein based cysteines. Characterization of key players and reactions in this network is crucial for preventive and therapeutic interventions.
I propose a new perspective on sulphur biochemistry. The reactivity of sulphur with the oxidative stressors superoxide, peroxides or hydroxyl radicals is well established, but far less is known about reactions between sulphur and molecular oxygen. I shall demonstrate that this reaction is fundamental to cellular life, and how advances in this field provide new options in medicine, biotechnology and the food industry.
Assisted by a team of three PhD students and a postdoctoral researcher I intend to establish this new research field by identification, characterization and engineering of enzymatic activities which catalyse oxidative carbon-sulfur bond formation and cleavage. Specific systems in this study include the biosynthetic enzymes for ergothioneine, sparsomycine and alliin, all of which are sulphur containing secondary metabolites with potent activities on cellular functions.
Summary
Oxidative stress causes cancer, cardiovascular, neurodegenerative and infective disease. Much of cellular oxidative stress is mediated, communicated, mitigated or amplified by a complex system of sulphur containing small metabolites or protein based cysteines. Characterization of key players and reactions in this network is crucial for preventive and therapeutic interventions.
I propose a new perspective on sulphur biochemistry. The reactivity of sulphur with the oxidative stressors superoxide, peroxides or hydroxyl radicals is well established, but far less is known about reactions between sulphur and molecular oxygen. I shall demonstrate that this reaction is fundamental to cellular life, and how advances in this field provide new options in medicine, biotechnology and the food industry.
Assisted by a team of three PhD students and a postdoctoral researcher I intend to establish this new research field by identification, characterization and engineering of enzymatic activities which catalyse oxidative carbon-sulfur bond formation and cleavage. Specific systems in this study include the biosynthetic enzymes for ergothioneine, sparsomycine and alliin, all of which are sulphur containing secondary metabolites with potent activities on cellular functions.
Max ERC Funding
1 497 202 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym HigherVision
Project The function of higher-order cortical and thalamic pathways during vision
Researcher (PI) Sonja Birgit Hofer
Host Institution (HI) UNIVERSITAT BASEL
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary When interacting with the environment we depend on our perception of the world around us. Visual perception relies on information flow from the eye to the visual cortex, where it is relayed and transformed via a series of cortical processing stages. Most research so far has focused on feedforward processing of visual information. However, it is increasingly obvious that perception crucially depends on how sensory input is interpreted in the context of an animal’s behavioural state, goals and actions. These non-sensory signals may be relayed by prominent long-range projections from higher-order cortical and thalamic areas, whose contribution to vision remains largely unexplored. Recent advances in imaging techniques and genetic tools for visualizing and manipulating neuronal activity enable us for the first time to study directly what information is conveyed through these major alternative visual pathways in the behaving animal and how they influence the processing of feedforward sensory information to allow us to actively perceive and interpret the environment.
Using state-of-the-art methodology combining in vivo imaging, electrophysiology, animal behaviour, virtual reality, genetic tools and targeted optogenetics using advanced optics, we will determine the functional role of (i) cortical feedback and (ii) higher-order thalamic signals during cortical processing of visual information in the behaving mouse. Specifically, we will investigate what information these projections convey to the visual cortex in anaesthetized and awake mice, whether they provide signals mediating the increased saliency of behaviourally relevant stimuli, and whether they enable the integration of sensory and motor information during locomotion and navigation. Together, the proposed work will answer fundamental questions about the role of these important but poorly understood visual pathways in active processing of visual input as animals interact with their environment.
Summary
When interacting with the environment we depend on our perception of the world around us. Visual perception relies on information flow from the eye to the visual cortex, where it is relayed and transformed via a series of cortical processing stages. Most research so far has focused on feedforward processing of visual information. However, it is increasingly obvious that perception crucially depends on how sensory input is interpreted in the context of an animal’s behavioural state, goals and actions. These non-sensory signals may be relayed by prominent long-range projections from higher-order cortical and thalamic areas, whose contribution to vision remains largely unexplored. Recent advances in imaging techniques and genetic tools for visualizing and manipulating neuronal activity enable us for the first time to study directly what information is conveyed through these major alternative visual pathways in the behaving animal and how they influence the processing of feedforward sensory information to allow us to actively perceive and interpret the environment.
Using state-of-the-art methodology combining in vivo imaging, electrophysiology, animal behaviour, virtual reality, genetic tools and targeted optogenetics using advanced optics, we will determine the functional role of (i) cortical feedback and (ii) higher-order thalamic signals during cortical processing of visual information in the behaving mouse. Specifically, we will investigate what information these projections convey to the visual cortex in anaesthetized and awake mice, whether they provide signals mediating the increased saliency of behaviourally relevant stimuli, and whether they enable the integration of sensory and motor information during locomotion and navigation. Together, the proposed work will answer fundamental questions about the role of these important but poorly understood visual pathways in active processing of visual input as animals interact with their environment.
Max ERC Funding
1 499 194 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym HNAEPISOME
Project Directed evolution of a synthetic episome based on hexitol nucleic acids (HNA)
Researcher (PI) Vitor Bernardo Bernardes Pinheiro
Host Institution (HI) UNIVERSITY COLLEGE LONDON
Call Details Starting Grant (StG), LS9, ERC-2013-StG
Summary A long term goal of synthetic biology is the assembly of a cell from its individual components. A genetic element based on synthetic nucleic acids capable of stable propagation, a synthetic episome, is the minimal genetic element required for the systematic development of all cellular components of a synthetic organism based on artificial nucleic acids. Recent progress in DNA polymerase engineering has successfully isolated variants with expanded substrate spectra capable of efficiently synthesising hexitol nucleic acids (HNA) from DNA templates, and capable of synthesising DNA from HNA templates. Together, they demonstrate that HNA can serve as a genetic material. However, the unavoidable DNA intermediate in HNA replication and their limited processivity greatly limit the potential of these polymerases for the development of an HNA episome.
To establish an HNA episome, processive HNA-directed HNA polymerases as well as accessory proteins to support episome maintenance and replication are required. The bacteriophage phi29 requires only four proteins (including polymerase, terminal protein, single-stranded and double-stranded DNA binding proteins) and two DNA elements (origin of replication and high affinity sites for its double-stranded DNA binding protein) to replicate and maintain its linear genome, making it a suitable starting point for the development of an HNA episome.
We propose to develop novel in vitro selection methodologies that will allow the directed evolution of a minimal HNA episome based on the phi29 system – including the isolation of an HNA-dependent HNA polymerase, a modified terminal protein and single-stranded as well as double-stranded HNA binding proteins. In addition to being a landmark result in synthetic biology, such HNA episome can form the basis of safer genetically modified organisms, in which the traits are encoded outside biology in an HNA episome dependent on the continued supply of artificial substrates for its maintenance.
Summary
A long term goal of synthetic biology is the assembly of a cell from its individual components. A genetic element based on synthetic nucleic acids capable of stable propagation, a synthetic episome, is the minimal genetic element required for the systematic development of all cellular components of a synthetic organism based on artificial nucleic acids. Recent progress in DNA polymerase engineering has successfully isolated variants with expanded substrate spectra capable of efficiently synthesising hexitol nucleic acids (HNA) from DNA templates, and capable of synthesising DNA from HNA templates. Together, they demonstrate that HNA can serve as a genetic material. However, the unavoidable DNA intermediate in HNA replication and their limited processivity greatly limit the potential of these polymerases for the development of an HNA episome.
To establish an HNA episome, processive HNA-directed HNA polymerases as well as accessory proteins to support episome maintenance and replication are required. The bacteriophage phi29 requires only four proteins (including polymerase, terminal protein, single-stranded and double-stranded DNA binding proteins) and two DNA elements (origin of replication and high affinity sites for its double-stranded DNA binding protein) to replicate and maintain its linear genome, making it a suitable starting point for the development of an HNA episome.
We propose to develop novel in vitro selection methodologies that will allow the directed evolution of a minimal HNA episome based on the phi29 system – including the isolation of an HNA-dependent HNA polymerase, a modified terminal protein and single-stranded as well as double-stranded HNA binding proteins. In addition to being a landmark result in synthetic biology, such HNA episome can form the basis of safer genetically modified organisms, in which the traits are encoded outside biology in an HNA episome dependent on the continued supply of artificial substrates for its maintenance.
Max ERC Funding
1 188 594 €
Duration
Start date: 2014-02-01, End date: 2019-01-31
Project acronym IntraSpace
Project An intracellular approach to spatial coding in the hippocampus
Researcher (PI) Jérôme Gaetan Epsztein
Host Institution (HI) INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE
Call Details Starting Grant (StG), LS5, ERC-2013-StG
Summary The hippocampus is an important structure for spatial memory in rodents and episodic memory in humans. The hippocampus uses a sparse coding scheme where a given environment is represented by the place selective firing of a small group of cells, (called place cells) among a larger population of silent neurons. Thus a given environment is not only coded by the firing rate and timing of active cells but also by the very identity of these cells that fire or stay silent in that environment. Similarly, in humans, specific items or episodes are coded by the selective firing of particular cells in the temporal lobe among a larger population of silent neurons. Thus understanding the mechanisms involved in the selection of which cells will be active in a particular environment is one of the most important to understand the formation of spatial memories in rodents and episodic memories in humans. This question is at the core of our research project. Place cells have been extensively studied at the system level using extracellular recording which can only record the spiking output of neurons but not the intracellular mechanisms leading to that spiking. This is why I recently contributed to the development of a new technique allowing intracellular recordings in freely behaving animals. Using this technique we found an important role for intrinsic neuronal properties in the distinction between place and silent cells. Intriguingly, these differences were observed even before the new exploration began. Based on these findings we will address three objectives: 1) determine the role of intrinsic excitability in the initial selection of place cells, 2) test whether a similar coding scheme are valid for the other major hippocampal area for spatial coding: the CA3 area and last 3) determine whether these intrinsic mechanisms play a role in another major function of the hippocampus the remapping.
Summary
The hippocampus is an important structure for spatial memory in rodents and episodic memory in humans. The hippocampus uses a sparse coding scheme where a given environment is represented by the place selective firing of a small group of cells, (called place cells) among a larger population of silent neurons. Thus a given environment is not only coded by the firing rate and timing of active cells but also by the very identity of these cells that fire or stay silent in that environment. Similarly, in humans, specific items or episodes are coded by the selective firing of particular cells in the temporal lobe among a larger population of silent neurons. Thus understanding the mechanisms involved in the selection of which cells will be active in a particular environment is one of the most important to understand the formation of spatial memories in rodents and episodic memories in humans. This question is at the core of our research project. Place cells have been extensively studied at the system level using extracellular recording which can only record the spiking output of neurons but not the intracellular mechanisms leading to that spiking. This is why I recently contributed to the development of a new technique allowing intracellular recordings in freely behaving animals. Using this technique we found an important role for intrinsic neuronal properties in the distinction between place and silent cells. Intriguingly, these differences were observed even before the new exploration began. Based on these findings we will address three objectives: 1) determine the role of intrinsic excitability in the initial selection of place cells, 2) test whether a similar coding scheme are valid for the other major hippocampal area for spatial coding: the CA3 area and last 3) determine whether these intrinsic mechanisms play a role in another major function of the hippocampus the remapping.
Max ERC Funding
1 497 163 €
Duration
Start date: 2014-09-01, End date: 2019-08-31
