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ISM Virology meeting

Date:
08
Wednesday
December
2021
-
09
Thursday
December
2021
Conference
Time: 08:00
Location: David Lopatie Conference Centre

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    Plant immune system activation is necessary for efficient interaction with auxin secreting beneficial bacteria

    Date:
    12
    Tuesday
    October
    2021
    Lecture / Seminar
    Time: 15:00-16:00
    Title: Guest Seminar via Zoom
    Location: https://weizmann.zoom.us/j/97684910013?pwd=ai9wWUZQNWdVRVU2Y3laaUlWRmdwUT09 Password 973838
    Lecturer: Dr. Elhanan Tzipilevich
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Asaph Aharoni
    Abstract: Plants continuously monitor the presence of microorganisms through their immune ... Read more Plants continuously monitor the presence of microorganisms through their immune system to establish an adaptive response. Unlike immune recognition of pathogenic bacteria, mechanisms by which beneficial bacteria interact with the plant immune system are not well understood. Analysis of colonization of Arabidopsis thaliana by auxin producing beneficial bacteria revealed that activating the plant immune system is necessary for efficient bacterial colonization and auxin secretion. A feedback loop is established in which bacterial colonization triggers an immune reaction and production of reactive oxygen species, which, in turn, stimulate auxin production by the bacteria. Auxin promotes bacterial survival and efficient root colonization, allowing the bacteria to compete with other members of the root microbial community and inhibit fungal infection, promoting plant health.
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    Conservation of TIR immune signaling in bacteria and plants

    Date:
    06
    Tuesday
    July
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Guest Seminar via Zoom
    Location: https://weizmann.zoom.us/j/94920680518?pwd=MDhOVUZsQWRaMGZSYndIME5lZGtRdz09 Password 151190
    Lecturer: Gal Ofir
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Avraham Levy

    Synchronization and spatial coherence of noisy circadian clocks in a multicellular1-d organism

    Date:
    24
    Thursday
    June
    2021
    Colloquium
    Time: 11:15-12:30
    Location: https://weizmann.zoom.us/j/94477142638?pwd=aWNlZGVzNmdJdnJVZVNZUi9sZ0VBZz09
    Lecturer: Joel Stavans
    Organizer: Faculty of Physics
    Details: 11:00: coffee, tea and more. The colloquium will be Hybrid - you can attend i ... Read more 11:00: coffee, tea and more. The colloquium will be Hybrid - you can attend in person in Weissman Auditorium and it will be also broadcast in zoom.
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    Abstract: The collective behavior of oscillators is a venerable subject in Physics since H ... Read more The collective behavior of oscillators is a venerable subject in Physics since Huygens’ seminal contributions. Living systems, from simple unicellular bacteria to multicellular plants and mammals also display oscillatory dynamics, the most conspicuous of which are circadian rhythms, coupling the biology of these organisms to day/night cycles on Earth. While considerable headway has been made in understanding the behavior of individual circadian clocks and their molecular components, the behavior of a large collection of clocks is still poorly understood, constituting a fertile ground of inquiry. We studied at the single-cell level the collective behavior of one-dimensional arrays of clocks in Anabaena, a cyanobacterial organism of ancient origin, as a model system. Anabaena filaments display remarkable synchrony and spatial coherence at the organismal scale, despite considerable and yet inevitable fluctuations in each cell –demographic noise-, stemming from the stochastic nature of biochemical reactions. Furthermore, we provide experimental evidence supporting the notion that spatio-temporal coherence is largely due to the coupling of clocks by cell-cell communication, and that the clock controls other cellular processes such as cell division. A stochastic, one-dimensional toy model of coupled clocks shows that demographic noise can seed stochastic oscillations outside the region where deterministic limit cycles with circadian periods occur. The model reproduces the observed spatio-temporal coherence along filaments and provides a robust description of coupled circadian clocks in a multicellular organism.
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    The human body from a quantitative perspective: cells, bacteria and SARS-CoV-2

    Date:
    01
    Tuesday
    June
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Hybrid Dept. Seminar
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Ron Sender
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Prof. Ron Milo

    Aerobic Bacteria Produce Nitric Oxide Through Denitrification During Microbial Interactions

    Date:
    06
    Tuesday
    April
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Dept. Seminar via Zoom
    Location: https://weizmann.zoom.us/j/93820152550?pwd=c0QzK3VTcjZpditUSGNwQzBKb0gvUT09 Password 419056
    Lecturer: Dr. Adi Abada
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Dr. Einat Segev

    Diatom modulation of associated bacteria

    Date:
    09
    Tuesday
    March
    2021
    Lecture / Seminar
    Time: 11:30-12:30
    Title: Guest Seminar via Zoom
    Location: https://weizmann.zoom.us/j/91943922657?pwd=QnF1eThwV0lWTk45ZWFBWnlHeGx2Zz09Password620591
    Lecturer: Dr. Ahmed Shibl
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Dr. Einat Segev

    Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization”.

    Date:
    31
    Sunday
    January
    2021
    Lecture / Seminar
    Time: 11:00-12:00
    Lecturer: Prof. Talila Volk
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWF ... Read more Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWFhZVUVzZz09 The genetic material of live organisms is packed and stored within the nucleus. It contains DNA wrapped around the nucleosomes, which then organized into chromatin fibers that partition into distinct compartments, which eventually fill the entire nucleus. Chromatin three dimensional topology is essential for proper accessibility of transcription factors, which control tissue-specific gene expression programs. Whereas chromatin partition into specific domains has been described in cells in culture conditions, information regarding chromatin 3 dimensional distribution in tissues within live organisms is still missing. We have imaged the chromatin in muscle fibers of live, intact Drosophila larvae, and revealed its 3 dimensional structure. Our results demonstrate novel 3 dimensional architecture of the chromatin which is evolutionary conserved, and has important implications on the regulation of gene expression.
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    MicroEco 2020

    Date:
    06
    Wednesday
    January
    2021
    -
    07
    Thursday
    January
    2021
    Conference
    Time: 08:00
    Location: David Lopatie Conference Centre

    The diverse roles of bacterial chemical messengers: shaping marine communities and protecting phytoplankton against viral mortality

    Date:
    24
    Tuesday
    November
    2020
    Lecture / Seminar
    Time: 16:00
    Title: Guest Seminar by Zoom
    Location: https://weizmann.zoom.us/j/97551963167?pwd=ZWNFWjk3bmU3UThMV3habUdId085dz09 Meeting ID: 975 5196 3167 Password: 971660
    Lecturer: Dr. Kristen Whalen
    Organizer: Department of Plant and Environmental Sciences
    Details: Host: Dr. Einat Segev
    Abstract: Microbes have emerged as key players integrating a variety of external and inter ... Read more Microbes have emerged as key players integrating a variety of external and internal signals that simultaneously influence eukaryotic physiology. The coevolutionary history of microbes and their hosts has selected for a range of interactions from symbiotic to pathogenic, often driven by small molecule chemical messengers that shape community dynamics and govern ecosystem trajectories. However, an ongoing fundamental challenge for the field is identifying bacterial chemical signals and linking their mechanisms of action in the host with resultant ecological consequences in the field. Here, I will describe the mechanisms by which the bacterial quorum sensing signal 2-heptyl-4-quinolone (HHQ) induces immediate, yet reversible, cellular stasis (no cell division nor mortality) in the model coccolithophore, Emiliania huxleyi. Using ultrastructural observations and diagnostic biochemical assays integrated with transcriptomic and proteomic studies, I will describe the molecular targets of this bacterial signal and the mechanism(s) by which bacterial signals assist phytoplankton evasion from viral death. Since interactions between bacteria and eukaryotic phytoplankton play a central role in mediating biogeochemical cycles and global climate, this work provides a new mechanistic framework for how bacterial cues mediate interkingdom behaviors.
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    Zoom Lecture: Designing In Situ Architectures in 3D Cell-Laden Hydrogels

    Date:
    14
    Sunday
    June
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Lecturer: Prof. Dror Seliktar
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: One of the key advantages in using light-sensitive hydrogel biomaterials is the ... Read more One of the key advantages in using light-sensitive hydrogel biomaterials is the ability to spatially structure cell scaffolds with three-dimensional mechanical cues that guide cellular morphogenesis. However, this has proven difficult because of the high toxicity associated with the cross-linking interactions. To overcome this challenge, we developed a new paradigm in micro-patterning using a reversible temperature-induced phase transition from liquid to solid vis-à-vis lower critical solubility temperature (LCST). This facilitates reduced transport kinetics of the polymer chains in solution, thus enabling crosslinking that is truly compatible with cell-laden 3D culture. Cellularized constructs were patterned to reveal a difference in morphogenesis between chemically crosslinked “stiffer” and physically crosslinked “softer” regions. Emphasizing the importance of mechanical heterogeneity in cellular morphogenesis, the results validate cutting-edge technology that can provide scientists with a robust set of tools for engineering cell and tissue growth in three dimensions.
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    Bacterial deposition and attachment to soft surfaces: mitigation, measurements, mechanism and open questions

    Date:
    31
    Sunday
    May
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Lecturer: Prof. Viatcheslav (Slava) Freger
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Zoom Lecture: https://weizmann.zoom.us/j/95418425823 Deposition and attachme ... Read more Zoom Lecture: https://weizmann.zoom.us/j/95418425823 Deposition and attachment are key steps in colonization and fouling of surfaces by bacteria and other microorganisms, undesired in most applications. Soft hydrophilic surfaces are attractive as potential low-fouling coatings, however, deposition on such surfaces open questions regarding microscopic mechanism of attachment and its relation to deposition kinetics, not addressed in the current picture. In the talk, I will highlight our effort to understand deposition and attachment of bacteria and microparticles on low-fouling surfaces and develop appropriate characterization techniques and models.
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    Chemistry Colloquium

    Date:
    11
    Monday
    May
    2020
    Colloquium
    Time: 11:00-12:15
    Title: The Macromolecular Structure of Mucus, Our Bodies’ First Line of Defense Against Pathogens
    Location: https://weizmann.zoom.us/j/92049901272
    Lecturer: Prof. Debbie Fass
    Organizer: Faculty of Chemistry
    Abstract: Respiratory viruses such as coronavirus spread from person to person through dro ... Read more Respiratory viruses such as coronavirus spread from person to person through droplets of saliva or mucus. Face masks decrease the dissemination of such droplets and thereby minimize viral propagation from someone who may be contagious. Mucus did not evolve, though, to help pathogens spread. Quite the opposite. Mucus arose early in the evolution of multicellular animals to exclude undesirable bacteria from body tissues, a primitive type of immunity. The cooperation between cilia* and mucus also helped prevent aquatic organisms from being smothered by sediments and enabled them to clean or collect particulate matter from their exteriors. Producing mucus was likely a prerequisite for evolution of the gut and of the types of respiratory organs necessary for terrestrial life. Today, mucus protects the large, exposed interior surfaces of our respiratory and gastrointestinal tracts from bacteria, viruses, parasites, and chemical/physical hazards. But what material is mucus? Mucus is a hydrogel made of heavily glycosylated protein molecules called “mucins,” each of which is nearly 3 megadaltons in size. Individual giant mucin molecules are disulfide bonded to one another, generating an extended mesh. Using cryo-electron microscopy and X-ray crystallography, we have discovered the three-dimensional structure of mucins and gained insight into the mechanism by which they assemble step-wise into hydrogels. ______________________________________________________ * cell-surface, rope-like structures that beat in coordinated waves
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    Resistance Mechanisms of Salmonella Typhimurium to Antimicrobial Peptides

    Date:
    17
    Tuesday
    March
    2020
    Lecture / Seminar
    Time: 10:00-10:30
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Gal Kapach
    Organizer: Department of Biomolecular Sciences
    Abstract: Bacterial resistance to antibiotics is a major concern worldwide, leading to an ... Read more Bacterial resistance to antibiotics is a major concern worldwide, leading to an extensive search for alternative drugs. Promising candidates are antimicrobial peptides, innate immunity molecules, which were shown to be highly efficient against multidrug resistant bacteria. Therefore, it is essential to study bacterial resistance mechanisms against them. In Salmonella Typhimurium (S.Typhimurium), a pathogenic bacterium that causes inflammation of the gastrointestinal tract, resistance to antimicrobial peptide is mainly mediated by surface modifications. These reduce the molecular interactions between the bacterial surface and the peptides. Searching for new resistance mechanisms to antimicrobial peptides, we revealed two novel strategies that evolved in a S. Typhimurium resistant line. One involves mutations in the AcrAB-TolC efflux pump and the second is acquired by the loss of the periplasmic chaperone Skp. Our data provide a deeper understanding on the role of the AcrAB-TolC system and Skp in S. Typhimurium.
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    Potential role of cloud microorganisms in atmospheric chemistry

    Date:
    15
    Sunday
    March
    2020
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Anne-Marie Delort
    Organizer: Department of Earth and Planetary Sciences
    Abstract: We have shown that microorganisms (bacteria, yeast and fungi) were present in cl ... Read more We have shown that microorganisms (bacteria, yeast and fungi) were present in clouds and were metabolically active. As a consequence a new scientific question rose: are they able to modify the chemical composition of clouds and be an alternative route to radical chemistry? In the past we have mainly studied the biotransformation of simple carbon compounds (acetate, succinate, formate, methanol, formaldehyde), and oxidants (H2O2). We showed that biodegradation rates were within the same range of order than photo-transformation rates. More recently we investigated their potential biodegradation activity towards atmospheric pollutants. Using GCxGC-HRMS technique we were able to detect and identify over 100 semi-volatile compounds in 3 cloud samples collected at the puy de Dôme station (1465 m, France). Among these compounds, 10 priority pollutants from the US EPA list were identified and quantified. We focused our work on the biodegradation of phenol and catechol in clouds using two strategies. 1) A metatranscriptomic analysis showed in cloud activity of microorganisms. We detected transcripts of genes coding for phenol monooxygenases (and phenol hydroxylases) and catechol 1,2-dioxygenases. These enzymes were likely from Gamma-proteobacteria (Acinetobacter and Pseudomonas genera). 2) 145 bacterial strains isolated from cloud water were screened for their phenol degradation capabilities, 93% of them (mainly Pseudomonas and Rhodococcus strains) were positive. These findings highlighted the possibility of phenol degradation by microorganisms in clouds. To go further we measured the biodegradation rates of Phenol and Catechol by one of the most active strain (Rhodococcus enclensis) and compared them with the transformation rates resulting from the reactivity of °OH and NO3°radicals. In the cloud water phase, both phenol transformation rates were within the same range of order, while biodegradation of catechol was ten times quicker than chemical transformation. The experimentally derived biodegradation rates were included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. In conclusion our results suggest that cloud microorganisms could play a role in atmospheric chemistry.
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    Uncovering a ‘Quorum Sensing-Like’ Mechanism of Malaria Parasites

    Date:
    03
    Tuesday
    March
    2020
    Lecture / Seminar
    Time: 10:30-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Anna Rivkin
    Organizer: Department of Biomolecular Sciences
    Abstract: The ability of pathogens to sense and respond to changes enables them to adapt a ... Read more The ability of pathogens to sense and respond to changes enables them to adapt and survive in hostile environments. In particular, microbes have developed a mechanism called quorum sensing, in which they produce, detect and respond to small, secreted molecules. One of the deadliest pathogens in humans is the parasite Plasmodium falciparum (Pf), the infectious agent of the malaria disease, accounting for the death of about half a million people annually. Here, we reveal that these parasites employ a quorum sensing-like mechanism to respond to their own density and coordinate their asexual growth during the blood stage of their life cycle. Namely, Pf parasites govern their own cell density by secreting active molecule(s). Using a combination of biochemical techniques, we chemically characterized the active fraction (autoinducer-like molecule) and revealed it to be a hydrophilic, positively charged molecule of a size ranging from 100Da to 4,000Da. Further purification using high-pressure liquid chromatography (HPLC) enabled the putative detection of two metabolites. Our finding suggests that malaria parasites signal each other to coordinate their asexual growth pattern is a previously unrecognized survival strategy. Identification and further investigation of the active secreted molecule can potentially lead to the development of anti-malaria drugs.
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    Laser-induced graphene polymer composite membranes as electrically active filters for contaminant removal

    Date:
    23
    Sunday
    February
    2020
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Christopher J. Arnusch
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: The control/elimination of microorganisms, viruses and micropollutants is releva ... Read more The control/elimination of microorganisms, viruses and micropollutants is relevant in many water treatment systems. We developed Laser-induced graphene (LIG), a three-dimensional, porous, electrically conductive graphene material generated by irradiation of polymer substrates composites, which have strong antifouling and antimicrobial properties. This method to “laser-print” electrically conductive antifouling graphene coatings on membranes holds promise for advanced water treatment and purification
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    Packets of Diffusing Particles Exhibit Universal Exponential Tails

    Date:
    09
    Sunday
    February
    2020
    Lecture / Seminar
    Time: 13:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Stas Burov, Bar-Ilan University
    Organizer: Clore Center for Biological Physics
    Abstract: Brownian motion is a Gaussian process described by the central limit theorem. Ho ... Read more Brownian motion is a Gaussian process described by the central limit theorem. However, exponential decays of the positional probability density function $P(X,t)$ of packets of spreading random walkers, were observed in numerous situations that include glasses, live cells and bacteria suspensions. We show that such exponential behavior is generally valid in a large class of problems of transport in random media. By extending the Large Deviations approach for a continuous time random walk we uncover a general universal behavior for the decay of the density. It is found that fluctuations in the number of steps of the random walker, performed at finite time, lead to exponential decay (with logarithmic corrections) of P(X,t). This universal behavior holds also for short times, a fact that makes experimental observations readily achievable.
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    Packets of Diffusing Particles Exhibit Universal Exponential Tails

    Date:
    09
    Sunday
    February
    2020
    Lecture / Seminar
    Time: 13:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Stas Burov
    Organizer: Department of Physics of Complex Systems
    Abstract: Brownian motion is a Gaussian process described by the central limit theorem. Ho ... Read more Brownian motion is a Gaussian process described by the central limit theorem. However, exponential decays of the positional probability density function $P(X,t)$ of packets of spreading random walkers, were observed in numerous situations that include glasses, live cells and bacteria suspensions. We show that such exponential behavior is generally valid in a large class of problems of transport in random media. By extending the Large Deviations approach for a continuous time random walk we uncover a general universal behavior for the decay of the density. It is found that fluctuations in the number of steps of the random walker, performed at finite time, lead to exponential decay (with logarithmic corrections) of $P(X,t)$. This universal behavior holds also for short times, a fact that makes experimental observations readily achievable.
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    Adaptation of bacteria with CRISPR and adaptation on a rugged fitness landscape

    Date:
    06
    Monday
    January
    2020
    Lecture / Seminar
    Time: 14:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Marija Vucelja
    Organizer: Department of Physics of Complex Systems
    Abstract: I will tell you two stories of adaptation of populations aided and enriched by s ... Read more I will tell you two stories of adaptation of populations aided and enriched by statistical physics approaches. The first story is about the adaptation of bacteria with CRISPR. CRISPR-Cas is a famous biology buzz word, due to its applications to gene editing. However, CRISPR-Cas is also a prokaryote immune system. It works as a “library” of previous infections. This library contains snippets of exogenous genetic material. With a new infection, the library is consulted, and if a match is found, the attempt will be made to neutralize the intruding genome. Bacteria use CRISPR-Cas as an immune system against phages and plasmids. Such immunity is hereditary and dynamic — it can be gained and lost during the lifetime of the single bacteria. Also, the process of acquiring snippets when exposed to the same phage is stochastic, and the same strain bacteria in a population contain different CRISPR loci content and thus variable immunity to the phage. We use dynamical systems approaches to predict the shape of this diverse distribution of CRISPR loci content within a bacterial population as a function of two crucial parameters — the rate of acquisition and the immunity to the phage. The second story is about adaptation on a rugged fitness landscape. A crude measure of adaption to a new environment called fitness. Often one defines fitness as the expected growth rate. The higher the fitness, the more thriving is a population. What happens over long times for a population with a finite genome — when all beneficial, fitness mutations, are exhausted? Contrary to expectations, the experiments show that fitness does not reach a plateau. Here we introduce a spin-glass microscopic model, where a genome can be represented as a spin configuration, and individual spins are genes. The fitness plays the role of minus the Hamiltonian of the system. We use numerical approaches and estimates to study hopping between metastable states on a rugged fitness landscape. We show that with gene interactions (interacting spins), double beneficial mutations (flipping of pairs of spins) can lead to a slow, logarithmic increase of fitness in a wide class of cases.
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    Adaptation of bacteria with CRISPR and adaptation on a rugged fitness landscape

    Date:
    06
    Monday
    January
    2020
    Lecture / Seminar
    Time: 14:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Marija Vucelja
    Organizer: Department of Physics of Complex Systems
    Abstract: I will tell you two stories of adaptation of populations aided and enriched by s ... Read more I will tell you two stories of adaptation of populations aided and enriched by statistical physics approaches. The first story is about the adaptation of bacteria with CRISPR. CRISPR-Cas is a famous biology buzz word, due to its applications to gene editing. However, CRISPR-Cas is also a prokaryote immune system. It works as a “library” of previous infections. This library contains snippets of exogenous genetic material. With a new infection, the library is consulted, and if a match is found, the attempt will be made to neutralize the intruding genome. Bacteria use CRISPR-Cas as an immune system against phages and plasmids. Such immunity is hereditary and dynamic — it can be gained and lost during the lifetime of the single bacteria. Also, the process of acquiring snippets when exposed to the same phage is stochastic, and the same strain bacteria in a population contain different CRISPR loci content and thus variable immunity to the phage. We use dynamical systems approaches to predict the shape of this diverse distribution of CRISPR loci content within a bacterial population as a function of two crucial parameters — the rate of acquisition and the immunity to the phage. The second story is about adaptation on a rugged fitness landscape. A crude measure of adaption to a new environment called fitness. Often one defines fitness as the expected growth rate. The higher the fitness, the more thriving is a population. What happens over long times for a population with a finite genome — when all beneficial, fitness mutations, are exhausted? Contrary to expectations, the experiments show that fitness does not reach a plateau. Here we introduce a spin-glass microscopic model, where a genome can be represented as a spin configuration, and individual spins are genes. The fitness plays the role of minus the Hamiltonian of the system. We use numerical approaches and estimates to study hopping between metastable states on a rugged fitness landscape. We show that with gene interactions (interacting spins), double beneficial mutations (flipping of pairs of spins) can lead to a slow, logarithmic increase of fitness in a wide class of cases.
    Close abstract

    Seminar for thesis defense, Maya Voichek

    Date:
    19
    Thursday
    December
    2019
    Lecture / Seminar
    Time: 15:00-16:00
    Title: “Chatty microbes - Regulation of communication systems in bacteria”
    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    Lecturer: Maya Voichek
    Organizer: Department of Molecular Genetics

    At the Interface between Organic and Inorganic Matter: Interactions and Design of Simple Functional Coatings

    Date:
    18
    Wednesday
    December
    2019
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Meital Reches
    Organizer: Department of Molecular Chemistry and Materials Science
    Abstract: Several natural processes are mediated by the interactions between organic and ... Read more Several natural processes are mediated by the interactions between organic and inorganic materials. The immune response towards an implant inserted into the body is mediated by proteins. Composite materials are formed by the interactions of organic materials (usually proteins) and minerals. Biofouling, the process in which organisms attached to surfaces, is also mediated by organic molecules. Understanding the nature of interactions between organic and inorganic materials will bring to the development of improved implants, new composites and antifouling materials. This lecture will present single-molecule force spectroscopy measurements of the interactions between individual biomolecules (either amino acid residues or short peptides) and inorganic surfaces in aqueous solution. Using this method, we were able to measure low adhesion forces and could clearly determine the strength of interactions between individual amino acid residues and inorganic substrates. Our results with peptides also shed light on the factors that control the interactions at the organic-inorganic interface. Based on our knowledge from single molecule experiments, we designed a short peptide (tripeptide) that can spontaneously form a coating that resists biofilm formation. Our results clearly demonstrate the formation of a coating on various surfaces (glass, titanium, silicon oxide, metals and polymers). This coating prevents the first step of antifouling, which involves the adsorption of bioorganic molecules to the substrate. In addition, it significantly reduces the attachment of various organisms such as bacteria and fungi to surfaces. Another variation of this peptide can encourage the adhesion of mammalian cells while preventing biofilm formation.
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    The Braginsky Center for the Interface between the Sciences and the Humanities

    Date:
    03
    Tuesday
    December
    2019
    Lecture / Seminar
    Time: 15:00-16:00
    Title: The Science of Memory and the Mechanisms of Mnemohistory - or, the fate of Jewish memory over >3300 yrs
    Location: Dolfi and Lola Ebner Auditorium
    Lecturer: Prof. Yadin Dudai
    Organizer: Department of Chemical and Biological Physics
    Abstract: From the vantage point of the Science of Memory, human cultures can be considere ... Read more From the vantage point of the Science of Memory, human cultures can be considered as 'biocultural supraorganisms' that can store distributed experience-dependent, behaviorally-relevant representations over hundreds and thousands of years. I will describe cognitive and artefactual instruments that mediate encoding, consolidation, storage and retrieval of such cross-generational collective engrams in large human populations. Investigation of this type of long-duration memory is made possible by combining archeology, history and cognitive science. I will focus on a model system for the analysis of long-duration cultural memory. This is the memory of the Jewish culture, that can be traced back ca. 3300 yr (i.e. ca. 130 generations) ago. I will zoom in on the core memory of this culture, i.e., the minimal set of cross-generational mnemonic items considered by members of that culture to define their collective origin, history and distinctiveness. Identifying a core memory item and tracing its fate over time can facilitate mechanistic understanding of remote as well as more recent collective memory. I will present data and hypotheses concerning the encoding, transformation, persistence and reactivation of an early component of the core memory, that had amalgamated fact with fiction in its first ca. 1000 yrs before being put in writing ca. 2300 yrs ago in an information-dense text of only 63 Hebrew words. Its high-fidelity persistence relied on evolving procedural reactivations. Potential implications of this persistence mechanism for understanding remote memory in individuals will be discussed. In recent generations reactivation of this memory and its updating play a role in splitting Jewish cultural memory into sub-narratives that differ, inter alia, in geographical distribution and cultural signature. This enables data-based analysis of ongoing transformation of collective memory in a large distributed human population
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    Active Matter: `active thermodynamics’ and the dynamics of biopolymer gels

    Date:
    01
    Sunday
    December
    2019
    Lecture / Seminar
    Time: 13:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Tomer Markovich
    Organizer: Department of Physics of Complex Systems
    Abstract: Active materials are composed of many components that can convert energy from it ... Read more Active materials are composed of many components that can convert energy from its environment (usually in the form of chemical energy) into directed mechanical motion. Time reversal symmetry is thus locally broken, leading to a variety of novel phenomena such as motility induced phase separation, reversal of the Ostwald process and flocking. Examples of active matter are abundant and range from living matter such as bacteria, actomyosin networks and bird flocks to Janus particles, colloidal rollers and macroscale driven chiral rods. Nevertheless, in many cases experiments on active materials exhibit equilibrium like properties (e.g., sedimentation of bacteria). In the first part of the talk I will try to answer the important question: how do we know a system is `active’? And if it is, can we have generic observables as in equilibrium thermodynamics? Can we measure how far it is from equilibrium? In the second part of the talk I will focus on examples of activity in biopolymer gels, such as the cytoskeleton of living cells. I will show some of the effects of active motors with emphasis on chiral motors. The latter does not have a unique hydrodynamic description, which one can utilize to gain access to the microscopic details of the complex motors using macroscopic measurements. I will also discuss non-motor activity and demonstrate how it can result in contractility, e.g., in the process of cell division.
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    "Sporadic Alzheimer's disease – does it start with altered ubiquitin signaling?”

    Date:
    29
    Tuesday
    October
    2019
    Lecture / Seminar
    Time: 14:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Michael H. Glickman
    Organizer: Department of Brain Sciences
    Details: Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance w ... Read more Host: Dr. Meital Oren meital.oren@weizmann.ac.il tel: 6479 For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
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    Abstract: With our rapidly aging population, Alzheimer’s disease (AD) is often considere ... Read more With our rapidly aging population, Alzheimer’s disease (AD) is often considered the plague of the 21st century. While much is known regarding the direct genetic mutations that trigger the rare familial form of the disease (FAD), molecular mechanisms driving the emergence of late-onset sporadic AD (SAD) remain elusive. A distinctively human predicament, AD is a protein-based disease characterized by toxic protein build up in the brain. The principal mechanisms for protein turnover or removal are dependent on ubiquitin. We will describe evidence that interference with ubiquitin signalling in a 3-dimentional human neuronal culture is sufficient to cause the two pathological hallmarks of AD (A plaques and neurofibrillary tangles), even in the absence of any familial mutations. By utilizing this platform, we specifically demonstrate that attenuated ubiquitin-dependent turnover leads to elevated levels of the Amyloid Precursor Protein (APP), enhanced secretion of the toxic amyloid-β42 peptide, and extra-cellular amyloid plaque build-up. Furthermore, we demonstrate that impaired ubiquitin signalling is a common feature of different human and murine models of AD, whereas overcoming this impairment is sufficient to decrease formation of A plaques and neurofibrillary tangles in an experimental model of FAD. To summarise, our work uncovers a role for ubiquitin during the early “cellular phase” of neurodegeneration that underlies emergence and progression of AD, providing hope that tweaking components of the ubiquitin-proteasome system has the potential to decrease risk for developing AD pathology, opening up new therapeutic approaches.
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    Growth dynamics and complexity of national economies in the

    Date:
    15
    Monday
    April
    2019
    Lecture / Seminar
    Time: 14:15
    Title: Growth dynamics and complexity of national economies in the global trade network
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: A.L. Stella
    Organizer: Department of Physics of Complex Systems
    Abstract: Methods of statistical physics allow to explore the quantitative nexus among eco ... Read more Methods of statistical physics allow to explore the quantitative nexus among economic growth of a country, diversity of its productions, and evolution in time of its export basket(*). A stochastic model of evolution, calibrated on data for 1238 exports from 223 countries in 21 years, enables counterfactual analyses based on estimates of the part of growth due to resource transfers between different productions. Original use of the Boltzmann-Shannon entropy function leads to the construction of consistent measures of the efficiency of national economies and of the specialization of productions. Comparisons with dynamical and GDP pc data lead to clear distinctions among developed, developing, underdeveloped and risky countries. Perspective applications of the entropic measures in other fields (ecology, microbiology,..) where diversity has to be estimated from bipartite networks will be shortly outlined. (Work in collaboration with G. Teza, University of Padova, and M. Caraglio, Katholieke Universiteit Leuven.)
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    Annual Meeting 2019, Israel Society for Microbiology

    Date:
    06
    Wednesday
    March
    2019
    -
    07
    Thursday
    March
    2019
    Conference
    Time: 08:00
    Location: Dolfi and Lola Ebner Auditorium
    Organizer: Conferences Section

    Are you stressed? The molecular framework of the nutritional alarmones (p)ppGpp

    Date:
    26
    Tuesday
    February
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Prof. Gert Bange
    Organizer: Department of Biomolecular Sciences
    Abstract: The ability of bacteria to adapt their metabolism to nutrient limitation or envi ... Read more The ability of bacteria to adapt their metabolism to nutrient limitation or environmental changes is essential for survival. The stringent response is a highly conserved mechanism that enables bacteria to respond to nutrient limitations. Central to stringent response is the synthesis of the nutritional alarmones pppGpp and ppGpp (collectively named: (p)ppGpp) that globally reprograms transcription and translation associated to variety of different cellular processes. In Bacillus subtilis and Staphylococcus aureus, three types of alarmone synthases (i.e., RelA, SAS1 and SAS2) have been identified that differ in length and domain composition. These differences might be attributed to their specific roles during stringent response. However, only little information on the molecular details is known. I will present our recent progress towards the structural/mechanistic understanding of the molecular framework of alarmone response.
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    Computational Design Principles of Cognition

    Date:
    24
    Sunday
    February
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Wolfson Building for Biological Research
    Lecturer: Dr. Yuval Hart
    Organizer: Department of Brain Sciences
    Abstract: Driven by recent technological advancements, behavior and brain activity can now ... Read more Driven by recent technological advancements, behavior and brain activity can now be measured at an unprecedented resolution and scale. This “big-data” revolution is akin to a similar revolution in biology. In biology, the wealth of data allowed systems-biologists to uncover the underlying design principles that are shared among biological systems. In my studies, I apply design principles from systems-biology to cognitive phenomena. In my talk I will demonstrate this approach in regard to creative search. Using a novel paradigm, I discovered that people’s search exhibits exploration and exploitation durations that were highly correlated along a line between quick-to-discover/quick-to-drop and slow-to-discover/slow-to-drop strategies. To explain this behavior, I focused on the property of scale invariance, which allows sensory systems to adapt to environmental signals spanning orders of magnitude. For example, bacteria search for nutrients, by responding to relative changes in nutrient concentration rather than absolute levels, via a sensory mechanism termed fold change detection (FCD). Scale invariance is prevalent in cognition, yet the specific mechanisms are mostly unknown. I found that an FCD model best describes creative search dynamics and further predicts robustness to variations in meaning perception, in agreement with behavioral data. These findings suggest FCD as a specific mechanism for scale invariant search, connecting sensory processes of cells and cognitive processes in human. I will end with a broader perspective and outline the benefits of the search for computational design principles of cognition.
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    Connecting the dots: functional and structural insights into the Legionella pneumophila Dot/Icm secretion system

    Date:
    22
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. David Chetrit
    Organizer: Department of Biomolecular Sciences
    Abstract: Type IV secretion systems (T4SS) are widespread in bacteria and despite their fu ... Read more Type IV secretion systems (T4SS) are widespread in bacteria and despite their fundamental importance in processes such as DNA conjugation and pathogenesis of plants, animals and humans, they are among the most complex and yet arguably the least understood secretion systems in the prokaryotic kingdom. Using live fluorescence microscopy in conjunction with cryo-electron tomography, we determined the in-situ structure of the T4SS of the respiratory pathogen Legionella pneumophila, called Dot/Icm. Unexpectedly, we have discovered that the major ATPases energizing center in the cytosol of the bacterial cell creates a dynamic assembly and forms a unique central channel in that it is constructed by a hexameric array of dimeric proteins. We have showed that the ATPase DotB cycles between the cytosol and the Type IV machine, indicating that it is involved in energizing the Type IV apparatus once a signal is received to initiate protein translocation. Our data changed the existing paradigm for how T4SS function and provides new insights for future studies that are important for a complete understanding of host pathogen interaction processes.
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    Rapid characterization of secreted recombinant proteins by native mass spectrometry

    Date:
    15
    Tuesday
    January
    2019
    Lecture / Seminar
    Time: 10:00-10:15
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Shay Vimer
    Organizer: Department of Biomolecular Sciences
    Abstract: Characterization of overexpressed proteins is essential for assessing their qual ... Read more Characterization of overexpressed proteins is essential for assessing their quality, and providing input for iterative redesign and optimization. This process is typically carried out following purification procedures, which are costly and time-consuming. We developed a native mass spectrometry method that enables characterization of recombinant proteins directly from culture media. Properties such as solubility, molecular weight, folding, assembly state, overall structure, post-translational modifications (PTMs) and ability to bind relevant biomolecules can be immediately revealed. We show the applicability of the method for in-depth characterization of secreted recombinant proteins from eukaryotic host systems such as yeast and insect cells. This method, which can be readily extended to high-throughput analysis, considerably shortens the time gap between protein production and characterization, and is particularly suitable for characterizing engineered and mutated proteins, and optimizing the yield and quality of overexpressed proteins.
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