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    A guide towards recombinant protein expression

    Date:
    04
    Thursday
    April
    2024
    Lecture / Seminar
    Time: 09:00-10:00
    Title: Fluorescence Labeling of Cancer Cells Using Chemically Modified Bacteria
    Location: Max and Lillian Candiotty Building
    Lecturer: Dr. Tamar Unger & Prof. David Margulies
    Organizer: Department of Life Sciences Core Facilities
    Contact: tamar.unger@weizmann.ac.il

    The Clore Center for Biological Physics

    Date:
    03
    Sunday
    March
    2024
    Lecture / Seminar
    Time: 13:15-14:30
    Title: A Statistical Physics Approach to Bacteria under Strong Perturbations
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Prof. Nathalie Q. Balaban
    Organizer: Clore Center for Biological Physics
    Contact: debbie.hen@weizmann.ac.il
    Details: refreshments will be served at 12:45
    Abstract: Statistical physics successfully accounts for phenomena involving a large number ... Read more Statistical physics successfully accounts for phenomena involving a large number of components using a probabilistic approach with predictions for collective properties of the system. While biological cells contain a very large number of interacting components, (proteins, RNA molecules, metabolites, etc.), the cellular network is understood as a particular, highly specific, choice of interactions shaped by evolution, and therefore difficultly amenable to a statistical physics description. Here we show that when a cell encounters an acute but non-lethal stress, its perturbed state can be modelled as random network dynamics. Strong perturbations may therefore reveal the dynamics of the underlying network that are amenable to a statistical physics description. We show that our experimental measurements of the recovery dynamics of bacteria from a strong perturbation can be described in the framework of physical aging in disordered systems (Kaplan Y. et al, Nature 2021). Further experiments on gene expression confirm predictions of the model. The predictive description of cells under and after strong perturbations should lead to new ways to fight bacterial infections, as well as the relapse of cancer after treatment.
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    The Clore Center for Biological Physics

    Date:
    28
    Sunday
    January
    2024
    Lecture / Seminar
    Time: 13:15-14:15
    Title: Some organizing principles behind microbial community dynamics
    Location: Nella and Leon Benoziyo Physics Building
    Lecturer: Dr. Amir Erez -Racah
    Organizer: Clore Center for Biological Physics
    Contact: malka.avraham@weizmann.ac.il
    Details: Lunch at 12:45
    Abstract: Microbial ecosystems, pivotal in global ecological stability, display a diverse ... Read more Microbial ecosystems, pivotal in global ecological stability, display a diverse array of species, influenced by complex interactions. When considering environments with changing nutrient levels, we have recently suggested an 'early bird' effect. This phenomenon, which results from changing nutrient levels, initial and fast uptake of resources confers an advantage, significantly altering microbial growth dynamics. In serial dilution cultures with varying nutrient levels, this effect leads to shifts in diversity, demonstrating that microbial communities do not adhere to a universal nutrient-diversity relationship. Using a consumer-resource, serial dilution modeling framework, we simulate scenarios of changing nutrient balance, such as variations in phosphorous availability in rainforest soils, to predict a possible lag in ecosystems response near a loss of diversity transition point. Lastly, we explore the notion of 'microbial debt', a form of the early bird advantage, where microbes initially grow rapidly at the cost of later growth or increased mortality. This dynamic, exemplified in both classical chemostat and serial dilution cultures, reveals that such debt can convey an advantage, with varying outcomes on community structure depending on the nature of the trade-off involved. Together, these studies illuminate some organizing principles behind microbial dynamics, balancing growth and survival in changing environments.
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    How Do Muscle Fibers Grow and Regenerate?

    Date:
    16
    Tuesday
    January
    2024
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Sharon Havusha-Laufer
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: The skeletal muscle tissue that allows our bodies to move, is comprised of enorm ... Read more The skeletal muscle tissue that allows our bodies to move, is comprised of enormous muscle fibers, termed myofibers. Myofibers must grow with our body and adapt to its needs throughout life. This is accomplished by adding nuclei via cell-to-cell fusion. However, the fusion mechanism is poorly understood. To gain a better understanding of the fusion and repair mechanisms I recapitulated myoblast-to-myofiber fusion in culture, which allowed me for the first time to visualize the fusion and regeneration processes at high resolution, generating the seminal observations that form the central hypothesis for my PhD.
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    Seminar for PhD thesis defense

    Date:
    23
    Thursday
    November
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Title: “Interactions between bacteria and their viruses”
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Avigail Stokar Avihail
    Organizer: Department of Molecular Genetics
    Contact: evi.ben-ami@weizmnn.ac.il

    Ultra-Repellent Aerophilic Surfaces Underwater”

    Date:
    30
    Wednesday
    August
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Alexander B. Tesler
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Wetting describes the ability of liquids to maintain contact with a solid surfac ... Read more Wetting describes the ability of liquids to maintain contact with a solid surface, a phenomenon that is ubiquitous in nature.1 However, in engineering and medical applications, contact of solid surfaces with aqueous media leads to undesirable phenomena such as corrosion, chemo- and biofouling, which have extremely negative economic, health, and environmental impacts. Therefore, control of wetting on solid surfaces is key to mitigating its detrimental effects. The latter can be achieved by minimizing the contact of the solid substrate with aqueous media, so-called superhydrophobic surfaces (SHS). Although SHS have been studied for decades to overcome wetting challenges,2 they are still rarely used in engineering applications. When immersed underwater, a special type of SHS can trap air on its surface, so-called air plastron, also known as an aerophilic surface. To date, plastrons have been reported to be impractical for underwater engineering due to their short lifetime. Here, I will describe aerophilic surfaces made of titanium alloy (Ti) with an extended lifetime of plastron conserved for months underwater.3 The extended methodology was developed to unambiguously describe the wetting regime on such aerophilic surfaces since conventional goniometric measurements are simply impractical. My aerophilic surfaces drastically reduce the adhesion of blood, and when immersed in aqueous media, prevent the adhesion of bacteria, and marine organisms such as barnacles, and mussels. Applying thermodynamic stability theories, we describe a generic strategy to achieve long-term stability of plastron on aerophilic surfaces for demanding and hitherto unattainable applications. (1) Quéré, D. Wetting and Roughness. Annual Review of Materials Research 2008, 38 (1), 71-99. (2) Cassie, A. B. D.; Baxter, S. Wettability of porous surfaces. Transactions of the Faraday Society 1944, 40, 546-551. (3) Tesler, A.B.;* Kolle, S.; Prado, L.H.; Thievessen, I.; Böhringer, D.; Backholm, M.; Karunakaran, B.; Nurmi, H.A.; Latikka, M.; Fischer, L.; Stafslien, S.; Cenev, Z.M.; Timonen, J.V.I.; Bruns, M.; Mazare, A.; Lohbauer, U.; Virtanen, S.; Fabry, B.; Schmuki, P.; Ras, R.H.A.; Aizenberg, J.; Goldmann, W.H. Long-Lasting Aerophilic Metallic Surfaces Underwater. Nature Materials 2023, accepted. *Corresponding author
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    Microbes in Cancer

    Date:
    17
    Monday
    July
    2023
    Lecture / Seminar
    Time: 11:15-13:00
    Location: Wolfson Building for Biological Research
    Lecturer: Dr. Ilana Livyatan
    Organizer: Life Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Details: Lab of Ravid Straussman, Dept. of Molecular Cell Biology Within the FGS cours ... Read more Lab of Ravid Straussman, Dept. of Molecular Cell Biology Within the FGS course on Translational Cancer Research Host: Zvi Livneh
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    Solar Panels for Light-to-Chemical Conversion

    Date:
    29
    Monday
    May
    2023
    Colloquium
    Time: 11:00-12:15
    Title: 2023 G.M.J. SCHMIDT MEMORIAL LECTURE
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Erwin Reisner
    Organizer: Faculty of Chemistry
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: Solar panels are well known to produce electricity, but they are also in early-s ... Read more Solar panels are well known to produce electricity, but they are also in early-stage development for the production of sustainable fuels and chemicals. These panels mimic plant leaves in shape and function as demonstrated for overall solar water splitting to produce green H2 by the laboratories of Nocera and Domen.1,2 This presentation will give an overview of our recent progress to construct prototype solar panel devices for the conversion of carbon dioxide and solid waste streams into fuels and higher-value chemicals through molecular surface-engineering of solar panels with suitable catalysts. Specifically, a standalone ‘photoelectrochemical leaf’ based on an integrated lead halide perovskite-BiVO4 tandem light absorber architecture has been built for the solar CO2 reduction to produce syngas.3 Syngas is an energy-rich gas mixture containing CO and H2 and currently produced from fossil fuels. The renewable production of syngas may allow for the synthesis of renewable liquid oxygenates and hydrocarbon fuels. Recent advances in the manufacturing have enabled the reduction of material requirements to fabricate such devices and make the leaves sufficiently light weight to even float on water, thereby enabling application on open water sources.4 The tandem design also allows for the integration of biocatalysts and the selective and bias-free conversion of CO2-to-formate has been demonstrated using enzymes.5 The versatility of the integrated leaf architecture has been demonstrated by replacing the perovskite light absorber by BiOI for solar water and CO2 splitting to demonstrate week-long stability.6 An alternative solar carbon capture and utilisation technology is based on co-deposited semiconductor powders on a conducting substrate.2 Modification of these immobilized powders with a molecular catalyst provides us with a photocatalyst sheet that can cleanly produce formic acid from aqueous CO2.7 CO2-fixing bacteria grown on such a ‘photocatalyst sheet’ enable the production of multicarbon products through clean CO2-to-acetate conversion.8 The deposition of a single semiconductor material on glass gives panels for the sunlight-powered conversion plastic and biomass waste into H2 and organic products, thereby allowing for simultaneous waste remediation and fuel production.9 The concept and prospect behind these integrated systems for solar energy conversion,10 related approaches,11 and their relevance to secure and harness sustainable energy supplies in a fossil-fuel free economy will be discussed.
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    Solar Panels for Light-to-Chemical Conversion Colloquium website

    An Innate Immunity Pathway Against Invading Microbes Targets the Paternal Mitochondria for Destruction after Fertilization

    Date:
    10
    Wednesday
    May
    2023
    Lecture / Seminar
    Time: 10:00-11:15
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Prof. Eli Arama
    Organizer: Department of Brain Sciences
    Contact: naomi.moses@weizmann.ac.il

    Animal and Microbial Rhodopsins

    Date:
    08
    Monday
    May
    2023
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Hideki Kandori
    Organizer: Faculty of Chemistry
    Contact: sarah.amzallag@weizmann.ac.il
    Details: Schmidt Auditorium
    Abstract: Rhodopsins are photoreceptive membrane proteins containing a retinal chromophore ... Read more Rhodopsins are photoreceptive membrane proteins containing a retinal chromophore in animals and microbes. Animal and microbial rhodopsins possess 11-cis and all-trans retinal, respectively, and undergo isomerization into all-trans and 13-cis retinal by light. While animal rhodopsins are G protein coupled receptors, the function of microbial rhodopsins is highly divergent, including light-driven ion pumps, light-gated ion channels, photosensors, and light-activated enzymes. Microbial rhodopsins have been the main tools in optogenetics. Function of rhodopsins starts in 10-15 sec, and activation of rhodopsins occurs in the protein environment that has been optimized during evolution (1015 sec). We thus need various methods to understand these events of 30 orders of magnitude in time. We have studied molecular mechanism of rhodopsins by use of spectroscopic methods. Using ultrafast spectroscopy, we showed the primary event in our vision being retinal photoisomerization. In rhodopsins, photoisomerization of retinal, the shape-changing reaction, occurs even at 77 K. Using low-temperature infrared spectroscopy, we detected protein-bound water molecules of rhodopsins before X-ray crystallography. Detailed vibrational analysis provided structural information such as our color discrimination mechanism. I will talk about our spectroscopic study of animal and microbial rhodopsins. Recent unexpected findings such as unusual isomerization pathways and temperature effects are also presented.
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    Animal and Microbial Rhodopsins Colloquium website

    Shigella flexneri vacuolar rupture : Near-native in cellulo structure-function analysis

    Date:
    12
    Sunday
    March
    2023
    Lecture / Seminar
    Time: 13:30-14:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Léa SWISTAK
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: Shigella flexneri is a bacterial entero-invasive pathogen transmitted through th ... Read more Shigella flexneri is a bacterial entero-invasive pathogen transmitted through the fecal/oral route causing bacillary dysentery in humans. Shigella pathogenicity solely relies on a needle-like molecular syringe, the Type 3 Secretion System (T3SS) that injects more than 20 bacterial effectors to infect colonic epithelial cells. The T3SS is composed of a basal body that controls and initiates effector secretion and a needle complex that acts as a conduit for effector delivery. The needle is capped by a tip complex that regulates whether the needle is closed or whether it secretes. Sensing of host cells by the needle tip complex induces a conformational switch that remodels the tip and activates the T3SS to form a channel, the translocon pore at the distal end. Effectors are then actively secreted, promoting cell invasion and endocytosis of the bacteria in a tight vacuole derived from the host plasma membrane called Bacteria Containing Vacuole (BCV). Quickly after entry, the pathogen ruptures its BCV and establish a replicative cytosolic niche. Vacuolar rupture consists of a first step of BCV breakage followed by BCV remnants unpeeling. The team has identified bacterial effectors promoting efficient vacuole unpeeling but the direct role of the T3SS in membrane destabilization is not clear. I have overcome these limitations by investigating the T3SS/vacuole interactions at the onset of vacuolar rupture using a novel cryo-Correlative Light Electron Microscopy (CLEM) workflow applied in situ, during the host-pathogen crosstalk. Cryo-CLEM allows the combination of high-resolution information in 3D, accessed via cryo-Electron Tomography (cryo-ET) to functional information brought by light microscopy. This pipeline benefits from in-house custom-built genetically encoded reporter cell lines which are used to identify precise steps of the infection at high spatiotemporal resolution. Using this workflow, I collected cryo-ET data on Shigella-infected epithelial cells. I have been able to visualize the Shigella T3SS at molecular resolution providing unprecedented information. Particularly, I am looking at (i) the contact sites between T3SS and BCV membrane; (ii) T3SS morphologies depending on its activation state. Together this work will allow to precisely describe the interplay between host and bacteria processes.
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    High resolution in vivo NMR spectroscopy: A tale about cells, a fish and a worm

    Date:
    23
    Thursday
    February
    2023
    Lecture / Seminar
    Time: 09:30-10:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Andrés Binolfi
    Organizer: The Helen and Martin Kimmel Institute for Magnetic Resonance Research
    Contact: ana.naamat@weizmann.ac.il
    Abstract: To understand the functional properties of biomolecules, such a small metabolite ... Read more To understand the functional properties of biomolecules, such a small metabolites, protein or nucleic acids, we ought to study them with high resolution in their native context. NMR spectroscopy allows the direct observation of NMR-active nuclei in complex, undefined environments and can thus be employed to investigate isotopically enriched molecules inside live cells. This methodology is known as In-cell NMR and has been used to evaluate the structural properties of proteins, nucleic acids and other biomolecules in physiological environments and to resolve their functional characteristics in a cellular context. These methods have been applied to bacteria, yeasts or cultured mammalian cells. However these cells are clonally grown at high densities in artificial media, lacking the complex tissue context present in higher organisms and its associated biological activities. We funnel our efforts to extend In-cell NMR applications to in vivo conditions using zebrafish embryos and the nematode C. elegans as model organisms. We deliver 15N-isotopically enriched biomolecules, such as small compounds and proteins into fish embryos to delineate their conformational properties and enzymatic conversions. We also enrich live C. elegans with 13C atoms to directly interrogate about their metabolic compositions and enzymatic activities. Combined, these studies provide methodological advancements with regard to high resolution in vivo NMR applications.
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    Between Southern Caucasus and Near East: The Kura-Araxes culture in a wider context

    Date:
    26
    Thursday
    January
    2023
    Lecture / Seminar
    Time: 13:30
    Location: Room 590, Benoziyo Building for Biological Science, Weizmann Institute of Science
    Lecturer: Dr. Elena Rova
    Contact: harsh.raj@weizmann.ac.il
    Details: Please follow the link or Zoom ID to join remotely. Join Zoom Meeting: https:/ ... Read more Please follow the link or Zoom ID to join remotely. Join Zoom Meeting: https://weizmann.zoom.us/j/4845901524?pwd=dkYybWIvTXVSaW40YmF2TEVxVFg0UT09 Meeting ID: 484 590 1524 Meeting password: 045940
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    The Kura-Araxes culture between Caucasus and Near East: An Introduction Part 1

    Date:
    19
    Thursday
    January
    2023
    Lecture / Seminar
    Time: 13:30
    Location: Room 590, Benoziyo Building for Biological Science, Weizmann Institute of Science
    Lecturer: Dr. Elena Rova
    Contact: harsh.raj@weizmann.ac.il
    Details: Join Zoom Meeting: https://weizmann.zoom.us/j/4845901524?pwd=dkYybWIvTXVSaW40Ym ... Read more Join Zoom Meeting: https://weizmann.zoom.us/j/4845901524?pwd=dkYybWIvTXVSaW40YmF2TEVxVFg0UT09 Meeting ID: 484 590 1524 Meeting password: 045940
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    Biosynthesis of Plant Natural Products: from the Colours of Beet to Defences in Wheat

    Date:
    27
    Tuesday
    December
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Guy Polturak
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il
    Abstract: Plants produce a vast range of specialized metabolites that serve various roles, ... Read more Plants produce a vast range of specialized metabolites that serve various roles, including mediating interactions with their immediate environments and providing defence against (a)biotic stresses. The ‘omics era’ has brought a new golden age for plant specialized metabolism research, vastly accelerating the discovery of novel metabolites and our understanding of their biosynthesis, roles and regulation. Two studies exemplifying omics-driven discovery of metabolic pathways, in beet and in wheat, will be presented: 1. Betalains are red-violet and yellow pigments restricted to order Caryophyllales, which have attracted interest due to their health-promoting properties and use as food colorants. Transcriptomics-led discovery of enzymes catalyzing the last unknown step in betalain biosynthesis in red beet enabled us to heterologously produce these pigments in plants and microbes, providing a valuable platform for studying their in-planta roles and enabling their subsequent utilization as reporter genes and plant transformation markers. 2. Wheat is one of the most widely grown crops in the world but is susceptible to numerous pests and pathogens, leading to major annual losses. Despite its agricultural importance, current knowledge of wheat chemical defenses remains very limited. Using a genome mining approach we uncovered six previously unknown pathogen-induced metabolic pathways in hexaploid bread wheat, which produce a diverse set of molecules and are encoded by biosynthetic gene clusters. Discovery and characterization of these cluster-encoded metabolic pathways provides key insights into the molecular basis of biotic stress responses in wheat, thus opening new potential avenues for improvement of this major food crop.
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    Beneficial microbe-plant interactions in milpa traditional agroecosystems and the effect of human intervention

    Date:
    15
    Tuesday
    November
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Jorge Rocha
    Organizer: Department of Plant and Environmental Sciences
    Contact: einat.segev@weizmann.ac.il
    Details: Host: Dr. Einat Segev
    Abstract: The health of plants depends largely on their interactions with microbes. Howeve ... Read more The health of plants depends largely on their interactions with microbes. However, crop modernization affects these interactions, resulting in plants that rely on excessive inputs such as fertilizers, pesticides, irrigation, etc. Milpas are rain-fed polyculture agroecosystems found in Mesoamerica, where native maize landraces are grown in association with other species. Plant health in milpas is achieved with traditional practices and, therefore, plant-microbe beneficial interactions play an essential role in productivity. Milpas are central to the lives people in rural populations, as local or even familiar traditions, festivities and food preferences influence agricultural practices, resulting in unique characteristics of each parcel that potentially generates a wide diversity of beneficial plant-microbe interactions. In this seminar, we will review our recent progress in the study of beneficial microbe-plant interactions in milpas, including: 1) abundance, functions and structure of maize seed-endophytic communities comparing native vs. modern hybrid varieties, where the effect of modernization can be analyzed; and 2) the contribution of microbes for drought tolerance of native maize landraces adapted to arid regions, to explore the selection of microbes with specific beneficial functions as a result of the farmers’ preferences.
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    “The immune system of bacteria: Beyond CRISPR”

    Date:
    08
    Tuesday
    November
    2022
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Rotem Sorek
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: The arms race between bacteria and phages led to the development of sophisticate ... Read more The arms race between bacteria and phages led to the development of sophisticated anti-phage defense systems, including CRISPR-Cas and restriction systems. We have recently reported that the microbial pan-genome contains many new defense systems whose function was so far unexplored. The talk will describe the functions of recently discovered new anti-phage systems. These include systems that utilize secondary metabolites for intracellular or as chemical defense against phages. Surprisingly, our studies show that bacterial defense from phage gave rise to key components in the eukaryotic immune system.
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    Mapping internal representations with adaptive sampling, massive online experiments and cross-cultural research

    Date:
    24
    Monday
    October
    2022
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Nori Jacoby
    Organizer: Department of Brain Sciences
    Contact: naomi.moses@weizmann.ac.il
    Details: ROOM 191 C-NEW
    Abstract: Our brain relies on internal representations to support perception, action, and ... Read more Our brain relies on internal representations to support perception, action, and decision-making. Internal representations are usually rich, multidimensional, and cannot be directly observed. How can these internal representations be characterized? How are they affected by experience? My work develops adaptive behavioral paradigms that integrate human decisions into computer algorithms via human-in-the-loop experiments. I combine these paradigms with a data-intensive expansion of the scale and scope of behavioral research by means of massive online experiments and cross-cultural comparative research. This talk presents “adaptive sampling,” a type of experimental paradigm inspired by Monte Carlo Markov Chain techniques. Each successive stimulus depends on a subject's response to the previous stimulus. This process allows us to sample from the complex and high-dimensional joint distribution associated with internal representations and obtain high-resolution maps of perceptual spaces. After introducing these methods and describing their implementation via large-scale online experiments and field experiments around the world, I demonstrate how they can be applied to fundamental questions in the understanding of the human mind. Specifically, I examine how biology and culture influence internal representations and how semantics influence perception.
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    How microbial interactions shape the exo-metabolic landscape of the ocean

    Date:
    12
    Tuesday
    July
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Constanze Kuhlisch
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il
    Details: Host: Prof. Assaf Vardi
    Abstract: Algal blooms are events of high primary productivity and rapid population growth ... Read more Algal blooms are events of high primary productivity and rapid population growth that can cover vast oceanic regions. They thus play an important role for the marine food web and for the global carbon and sulfur cycling. Furthermore, algal blooms are hotspots of microbial interactions with e.g. grazers, heterotrophic bacteria, fungi and viruses. These interactions are mediated by metabolite signals, they can modulate metabolic pathways and can induce biosynthetic gene clusters – the diversity of microbial communities in natural blooms is thus crucial in understanding the chemical ecology of algal blooms. In my talk, I will show how lipid remodeling during the infection of E. huxleyi blooms by its giant virus imprints the marine dissolved organic matter pool. Further, I will present how a tripartite interaction between alga, virus and associated microbes leads to a unique halogenation activity during bloom demise. Lastly, I will discuss the potential ecological role of indole derivatives that accumulate in the blooms of E. huxleyi.
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    Self-assembling structure and function using equilibrium and non-equilibrium statistical mechanics

    Date:
    26
    Tuesday
    April
    2022
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr, Matan Ya Ben Zion
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Self-assembly and self-organization are two big challenges in the natural scienc ... Read more Self-assembly and self-organization are two big challenges in the natural sciences. What are the rules governing the emergence of greater structures from unassuming elements? Does statistical-mechanics restrict their complexity? Biochemical processes can shape highly specific structures and function on the macro-scale using only molecular information. Although stereochemistry has been a central focus of molecular sciences since Pasteur, its synthetic province has been restricted to the nanometric scale. In my talk, I will describe how to propagate molecular information to self-assemble free-form architectures on the micron-scale and beyond. These architectures are a thousand times greater than their constituent molecules yet have a preprogrammed geometry and chirality. I will then show how to animate such synthetic microstructures into bacteria-like micro-swimmers. Previous artificial microswimmers relied on an external chemical fuel to drive their propulsion which restricted their operational concentration as they competed locally over fuel. I will demonstrate how to use material science and physical chemistry to self-assemble fuel-free micro-swimmers that are driven solely by light. The fuel independence allows the swimmers to stay active even at high densities, where they form turbulent flow structures (previously seen in living fluids), and cooperate to perform a greater task.
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    Host innate immunity and bacterial commensals prevent fungal dysbiosis in Arabidopsis roots

    Date:
    12
    Tuesday
    April
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Location: VIA ZOOM: https://weizmann.zoom.us/j/98989152393?pwd=a050Mm4rSlEwb2hLN1FiKy9oT24xdz09 Meeting ID: 989 8915 2393 Password: 002663
    Lecturer: Prof. Stéphane Hacquard
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il
    Details: Host: Dr. Daniel Dar
    Abstract: Understanding how host–microbe homeostasis is controlled and maintained in pla ... Read more Understanding how host–microbe homeostasis is controlled and maintained in plant roots is key to enhance plant productivity. However, the factors that contribute to the maintenance of this equilibrium between plant roots and their multikingdom microbial communities remain largely unknown. Using a microbiota deconstruction-reconstruction approach in gnotobiotic plant systems with synthetic, yet representative communities of bacteria, fungi, and oomycetes, we observe a link between fungal assemblages/load in roots and plant health. We show that modulation of fungal abundance in roots is tightly controlled by a two-layer regulatory circuit involving the host innate immune system on one hand and bacterial root commensals on another hand. We also report that fungi with the most detrimental activities in mono-association experiments with the host are part of the core root mycobiome in nature. Our results shed a light into how host–microbe and microbe–microbe interactions act in concert to prevent fungal dysbiosis in roots, thereby promoting plant health and maintaining growth-promoting activities of multikingdom microbial consortia.
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    Role of forces in membrane dynamics and tissue morphogenesis

    Date:
    05
    Tuesday
    April
    2022
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Marino Zerial
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: Our work has highlighted the function of Rab GTPases as key components for the b ... Read more Our work has highlighted the function of Rab GTPases as key components for the biogenesis, transport and function of cellular membrane organelles. The specificity and directionality of membrane fusion is mediated by Rab GTPases and tethering effectors, such as EEA1, which is recruited on the early endosome membrane and binds to Rab5. EEA1 is a long dimeric coiled-coil tether molecule. Upon binding to its N-terminus, Rab5 induces conformational changes on EEA1, from extended to a more flexible “collapsed” state, giving rise to an effective force. Our recent studies suggest that Rab5 and EEA1 effectively constitute a two-component molecular motor, cyclically converting the free energy of GTP binding and hydrolysis into mechanical work. We are now combining biochemical, quantitative image analysis and 3D primary cell culture approaches to explore the role of Rab GTPases and endocytic mechanisms in liver tissue organization and regeneration. Hepatocytes are polarized cells at the interface of both sinusoidal endothelial and bile canaliculi (BC) networks that transport blood and bile between portal and central vein, respectively. In contrast to simple epithelia, where the cells have a single apical surface facing the lumen of organs, hepatocytes exhibit a multipolar (biaxial) organization, i.e. have multiple apical and basal domains. We studied the mechanism of hepatocyte polarization by using a hepatoblasts culture system. We discovered that, during lumen formation, hepatoblasts create apical protrusions along the tight junction belt that connects them, suggesting that these are responsible for the anisotropic growth of apical lumina. These protrusions form a pattern reminiscent of the bulkheads of boats ships and planes. Similarly, the apical bulkheads of hepatocytes are structural elements which can provide such anisotropy and mechanical stability to the elongating cylindrical lumen under inner pressure.
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    Microbial and Antimicrobial Amyloids in the Fight Against Infections

    Date:
    29
    Tuesday
    March
    2022
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Meytal Landau
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: Amyloids are protein fibers with unique and strong structures, known mainly in t ... Read more Amyloids are protein fibers with unique and strong structures, known mainly in the context of neurodegenerative diseases. Surprisingly, amyloid fibers are secreted by species across kingdoms of life, including by microorganisms, and helps their survival and activity. Our laboratory published the first molecular structures of functional bacterial amyloid fibrils, which serve as key “weapons” making infections more aggressive. This exposed new routes for the development of novel antivirulence drugs. In addition, we identified peptides produced across species that provide antimicrobial protection that form amyloid fibrils, and determined their first high resolution structures. This amyloid-antimicrobial link signifies a physiological role in neuroimmunity for human amyloids.
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    New metabolic functions can rapidly evolve in microbes by multiple convergent mechanisms

    Date:
    01
    Tuesday
    February
    2022
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Special Guest Seminar with Dr. Avihu Yona via zoom
    Location: https://weizmann.zoom.us/j/95436548996?pwd=Uk9yOVFrK0ZuTnRsdm5TY1JiM1NzQT09 Meeting ID: 954 3654 8996 Password: 356165
    Lecturer: Dr. Avihu Yona
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il
    Details: Host: Dr. David Zeevi
    Abstract: Many plant foods contain oxalate C2O4(-2) that reaches the colon when we eat pla ... Read more Many plant foods contain oxalate C2O4(-2) that reaches the colon when we eat plant foods. When oxalate reaches high concentrations it can crystalize together with Ca+2 to form kidney stones. Humans don’t have enzymes to degrade oxalate, but microbes do. Therefore oxalate-degrading probiotics are a potential treatment for hyperoxaluria. Since clinical trials with oxalate-degrading microbes, like Oxalobacter Formigenes, could not show oxalate reduction, additional microbes that can degrade oxalate are of high interest, especially those that can perform in the human gut. In my talk I will describe how we harnessed lab evolution to develop novel gut microbes that can degrade oxalate. We obtained E. coli isolates from the stool of human volunteers and evolved them to metabolize oxalate in an anaerobic chamber. While no E. coli is known to utilize oxalate, our isolates evolved robust growth on oxalate as a sole source of carbon and energy. In my talk I will present findings on the genetic and molecular mechanism underlying this evolution.
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