לוח שנה משולב

B2 small noncoding RNAs are transcribed from short interspersed nuclear elements (SINEs), which are high copy number transposable elements in the mouse genome. B2 RNAs are upregulated upon cellular stress and may repress mRNA synthesis or affect protein translation. Surprisingly, we observed global upregulation of polyadenylated B2 RNAs in sensory neuron ganglia following periperal nerve injury. Interestingly, similar induction was not seen in optic nerve injury, a model of central nervous system injury. In this talk, I will discuss our efforts to understand the possible involvement of B2 RNAs (and their corresponding human Alu RNA analogs) in neuronal regeneration.

While our world is three-dimensional (3D), spatial perception is most often studied in animals and humans navigating across 2D surfaces. I will present two cases in which the consideration of the 3D nature of the world has led us to surprising results. The first case regards the neural recording of mammalian grid cells. Grid cells that are recorded over 2D surfaces create a hexagonal-shaped repetitive lattice, which inspired many theoretical studies to investigate the pattern’s mechanism and function. Upon recording in bats flying through 3D space, we found that grid cells did not exhibit a hexagonal global lattice, but rather showed a local order – with grid-fields exhibiting fixed local distances. Our results in 3D strongly argue against most of the prevailing models of grid-cell function, and we suggest a unified model that explains the results in both 2D and 3D. The second case regards the perception of 3D space in humans. Different behavioral studies have shown contradicting evidence of human perception of 3D space being either isotropic or vertically compressed. We addressed this question using human experts in 3D motion and navigation – fighter pilots – studied in a flight simulator. We considered two aspects of the perception of 3D space: surrounding space and travelled space. We show that different aspects of the perception of space are shaped differently with experience: whereas the perception of the 3D surrounding space was vertically compressed in both expert and non-expert subjects, fighter pilots exhibited isotropic perception of travelled space, whereas non-expert subjects retained a distorted perception. Together, our research sheds light on the differences and similarities between the coding of 3D versus 2D space, in both animals and humans.


Zoom link to join-
https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09

Meeting ID: 966 0803 3618
Password: 564068

Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

ULTRASAT is a scientific satellite, that is planned to be launched to a geo-stationary orbit in Q4 2024. It will carry a telescope with an unprecedentedly large field of view (200 squared degrees) and UV (220-280nm) sensitivity. These unique properties will enable us to detect and systematically study transient astronomical events within an extra-Galactic volume, that is hundreds of time larger than that accessible to current observatories. ULTRASAT’s measurements will have a broad science impact across the fields of gravitational wave sources, supernovae, variable and flare stars, active galactic nuclei, tidal disruption events, compact objects, and galaxies. In this talk I will review ULTRASAT’s key science goals, its unique technical properties, and the project’s structure and status.

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.