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    Vascular Aging:

    Date:
    18
    Tuesday
    March
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Title: The Hidden Driver of Age-Related Organ Dysfunction
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Dr. Myriam Grunewald
    Organizer: Sagol Institute for Longevity Research
    Contact: urialonw@gmail.com
    Abstract: As life expectancy increases, age-related diseases are becoming more prevalent. ... Read more As life expectancy increases, age-related diseases are becoming more prevalent. While these conditions are traditionally studied in isolation, mounting evidence points to shared, systemic mechanisms underlying these conditions. Our research highlights the vasculature as  a key player in organ homeostasis and repair, and a system shared across all organs—making its dysfunction potential driver of age-related pathologies.We demonstrate that manipulating VEGF signaling to counteract age-related microvascular rarefaction promotes comprehensive geroprotection, preserving organ function and delaying disease onset. Our findings also reveal a link between vascular rarefaction and altered RNA splicing. While hypoxia-driven and age-related changes in alternative RNA splicing have been studied independently, we propose a unifying mechanism that links the two. To explore this further, we also employ patient-derived organoids, which retain their biological age in culture, providing a robust in vitro platform to test anti-aging interventions.Our findings support a vascular theory of aging, identifying vascular health as a promising target to mitigate age-related diseases and promote healthier aging.
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    The Clore Center for Biological Physics

    Date:
    23
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 13:15-14:30
    Title: What can microbes tell us about their environment
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Dr. David Zeevi
    Contact: debbie.hen@weizmann.ac.il
    Abstract: Microbial communities act as living sensors of their environment, continuously a ... Read more Microbial communities act as living sensors of their environment, continuously adapting to and recording changes in their surroundings across temporal and spatial scales. This capacity, combined with their central role in global biogeochemical cycles, makes microbes ideal indicators of ecosystem health. However, our understanding of how these communities respond to anthropogenic perturbations remains limited. In this talk, I will present two complementary approaches to decode environmental information from microbial communities. First, I will show that environmental temperature can be accurately predicted from microbial DNA composition alone, revealing fundamental principles of genome-wide thermal adaptation that transcend ecosystem boundaries. This work uncovers how evolutionary pressures shape microbial genomes across diverse habitats and provides insights into long-term community responses to climate change. Second, I will introduce a novel approach for measuring real-time bacterial growth rates in natural environments from a single sample, without prior knowledge on community composition. This method could enable us to track immediate ecological responses to environmental perturbations. By combining these evolutionary and ecological perspectives, we can begin to establish universal principles governing microbial responses to environmental change across different timescales. This multi-scale understanding is crucial for predicting and potentially mitigating the impacts of human activities on microbial ecosystems, from soil degradation to climate change.FOR THE LATEST UPDATES AND CONTENT ON SOFT MATTER AND BIOLOGICAL PHYSICS AT THE WEIZMANN, VISIT OUR WEBSITE: https://www.biosoftweizmann.com/
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    From Microbes to Human Brains: Unraveling and Targeting Amyloids via Advanced Structural Biology Tools

    Date:
    28
    Tuesday
    January
    2025
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Einav Tayeb-Fligelman
    Organizer: Department of Chemical and Structural Biology

    Physics Colloquium

    Date:
    23
    Thursday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Title: It takes two to tango: The physics of heterogeneous bacterial active matter systems
    Location: Physics Weissman Auditorium
    Lecturer: Prof. Joel Stavans
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Non-equilibrium active matter systems often exhibit self-organized, collective m ... Read more Non-equilibrium active matter systems often exhibit self-organized, collective motion that can give rise to the emergence of coherent spatial structures. Prime examples covering many length scales range from mammal herds, fish schools and bird flocks, to insect and robot swarms. Despite significant advances in understanding the behavior of homogeneous systems in the last decades, little is known about the self-organization and dynamics of heterogeneous active matter. I will present results of bioconvection experiments with multispecies suspensions of wild-type bacteria from the hyper-diverse bacterial communities of Cuatro Ciénegas, Coahuila, whose origin dates back to the pre-Cambrian. Under oxygen gradients, these bacteria swim in auto-organized, directional flows, whose spatial scales exceed the cell size by orders of magnitude, demonstrating a plethora of amazing dynamical behaviors, including segregation. I will present evidence supporting the notion that the mechanisms giving rise to these complex behaviors are predominantly physical, and not a result of biological interactions. This research significantly advances our understanding of both heterogeneity in active matter, as well as in the dynamics of complex microbial ecological communities, bringing profound insights into their spatial organization and collective behavior.
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    Neuromodulation of experience-dependent sexually dimorphic learning

    Date:
    20
    Monday
    January
    2025
    Lecture / Seminar
    Time: 11:00-12:15
    Location: WSOS (FGS)
    Lecturer: Sonu Kurien Dr. Meital Oren Lab
    Organizer: Department of Brain Sciences
    Abstract: How do sex-specific evolutionary drives influence decision-making processes when ... Read more How do sex-specific evolutionary drives influence decision-making processes when facing a shared environmental cue? Given the sex biases in disease states, some of which include a significant cognitive component, it is crucial to evaluate the influence of genetic sex on brain mechanisms from the ground up. In my thesis, I investigate if and how the genetic sex affects context and experience-dependent behavioral plasticity when learning an environmental cue. By utilizing a genes-to-behavior approach, I unravel sexual dimorphism in an ethologically relevant behavioral paradigm. C. elegans males do not learn to avoid the pathogenic bacteria PA14 as efficiently and rapidly as hermaphrodites, even though the pathogenicity is perceived. I explore the neuronal representations following training that encode this dimorphism and observe a possible sensory gating mechanism. The transcriptomic and subsequent behavioral analysis revealed the influence of the neuromodulatory network on male behavior. In particular, npr-5, an ortholog of the mammalian NPY receptor, regulates male learning by modulating typical neuronal activity. Finally, we uncover that male decision-making behavior is shaped by sexual status and is regulated by npr-5. Taken together, the work portrays how shared experiences drive sex-specific plasticity in hermaphrodites and males by modulating learning to fulfill perceived evolutionary needs. 
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    Allochthonous groundwater microorganisms affect coastal seawater microbial abundance, activity and diversity

    Date:
    19
    Sunday
    January
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman building
    Abstract: Submarine groundwater discharge (SGD) is a globally important processsupplying n ... Read more Submarine groundwater discharge (SGD) is a globally important processsupplying nutrients and trace elements to the coastal environment, thusplaying a pivotal role in sustaining marine primary productivity. Along withnutrients, groundwater also contains allochthonous microbes that aredischarged from the terrestrial subsurface into the sea. Currently, little isknown about the interactions between groundwater-borne and coastalseawater microbial populations, and groundwater microbes' role uponintroduction to coastal seawater populations. In the current study weinvestigated seawater microbial abundance, activity and diversity in a sitestrongly influenced by SGD. In addition, through laboratory-controlledbottle incubations, we mimicked different mixing scenarios betweengroundwater and seawater. Our results demonstrate that the addition of0.1 μm filtered groundwater stimulated heterotrophic activity andincreased microbial abundance compared to control coastal seawater,whereas 0.22 μm filtration treatments induced primary productivity andSynechococcus growth. 16S rRNA gene sequencing showed a strongshift from a SAR11-rich community in the control samples toRhodobacteraceae dominance in the <0.1 μm treatment, in agreementwith Rhodobacteraceae enrichment in the SGD field site. These resultssuggest that microbes delivered by SGD may affect the abundance,activity and diversity of intrinsic microbes in coastal seawater, highlightingthe cryptic interplay between groundwater and seawater microbes incoastal environments, which has important implications for carboncycling.
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    Unlocking ALS: Muscle Exosome Control TDP-43 Local Synthesis at the NMJced

    Date:
    12
    Thursday
    December
    2024
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Eran Perlson
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease characterize ... Read more Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease characterized by TDP-43 mislocalization, aggregation, and disruption of neuromuscular junctions (NMJs). We have identified a key pathological mechanism involving the accumulation of TDP-43 in axons, which impairs local protein synthesis and drives NMJ degeneration. This process is linked to dysregulated muscle-derived exosomes carrying miR-126a-5p, essential for maintaining proper nerve-muscle communication. In ALS, reduced levels of miR-126a-5p lead to abnormal TDP-43 synthesis in axons. Restoring miR-126 in vivo and in human co-culture systems provides neuroprotection. Our findings highlight a transcellular signaling axis between muscles and neurons, offering new insights into NMJ maintenance and a potential foundation for ALS therapeutic strategies.
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    On Microbes and Mountains: Unraveling the Links Between Microbial Weathering and Large-Scale Surface Processes

    Date:
    16
    Sunday
    June
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Michal Ben-Israel
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Microorganisms play a crucial role in the weathering processes that transform ro ... Read more Microorganisms play a crucial role in the weathering processes that transform rock into soil through chemical and physical mechanisms essential for nutrient cycling, nitrogen fixation, carbon storage, and organic matter decomposition. This intricate relationship between microbial life and landscapes forms the backbone of ecosystem dynamics and biogeochemical processes. Microbes influence rock weathering and soil production, adapting to their surroundings and creating distinct communities across various landscapes. These complex interactions and feedback mechanisms are pivotal to understanding the co-evolution of microbial communities and landscapes over time. However, existing research on microbial contributions to weathering and soil production has predominantly focused on relatively short timescales and small spatial scales. Understanding the interplay between the evolution of microbial communities and their role in weathering processes over geomorphic timescales within transient landscapes is important for a more complete understanding of how landscapes evolve as well as the impact of geomorphic changes on microbial community establishment and evolution. The main objective of this study is to elucidate the long-term dynamics of microbial communities and their role in weathering processes over millennial timescales. To achieve this, we focused on recently deglaciated basins in the Eastern Sierra Nevada, CA, examining bacterial community composition in three phases of the weathering process: exposed rock at the surface, saprolite—the weathered rock found beneath soil, and soil. Sampling along an elevational transect, we collected 25 samples of rock, soil, and saprolite, and evaluated their bacterial composition using 16S rRNA and metagenomic sequencing. Results show that both soil and saprolite samples exhibited diverse and similar microbial communities, indicating a developmental relationship between these habitats despite distinct geochemical compositions. In contrast, rock habitats are less diverse, and their composition resembles those of young deglaciated landscapes. Our findings point to a link between microbial community composition and rock-to-soil weathering processes, suggesting that the majority of weathering processes occur within the soil column (saprolite and soil), with exposed rock maintaining a steady state. The stability of these microbial communities over extended timescales suggests a potentially significant role for microbial weathering in landscape evolution. This finding underscores the importance of considering microbial contributions in future geomorphic studies, as they may play a key role in shaping the Earth's surface. Moving forward, we plan on coupling a long-term, landscape-scale geomorphic perspective with 'omics approaches from microbial ecology to comprehensively understand the complex relationships between microbial life and landscapes, ultimately advancing our knowledge of ecosystem dynamics and health.
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    The Clore Center for Biological Physics

    Date:
    26
    Sunday
    May
    2024
    Lecture / Seminar
    Time: 13:15-14:30
    Title: Phages vs bacteria warfare: co-evolution and intelligence gathering
    Location: Koffler Accelerator of the Canada Center of Nuclear Physics
    Lecturer: Prof. Yigal Meir
    Organizer: Clore Center for Biological Physics
    Contact: Debbie.hen@weizmann.ac.il
    Details: Lunch will be served at 12:45
    Abstract: The warfare between bacteria and phages - viruses that infect bacteria - has bee ... Read more The warfare between bacteria and phages - viruses that infect bacteria - has been raging for billions of years. During this time both sides have evolved various attack and defense systems. In this talk I will describe 3 related projects: 1. Is there an optimal number of such defense or anti-defense systems? 2. How can different phages which prey on the same bacteria co-exist, in contradiction with the expected competitive exclusion? 3. Some phages have developed the ability to garner environmental information, enabling them to make more "intelligent" decisions. How much is such intelligence worth, in terms of other resources? FOR THE LATEST UPDATES AND CONTENT ON SOFT MATTER AND BIOLOGICAL PHYSICS AT THE WEIZMANN, VISIT OUR WEBSITE: https://www.biosoftweizmann.com/
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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
    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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