לוח שנה משולב

Voltage gated ion channels gate in response to changes in the electrical membrane potential by the coupling of a voltage sensitive paddle module with an ion-selective pore. Toxins that target these channels are traditionally classified as either pore-blockers or gating-modifiers, the former bind and physically occlude the channel pore, while the later bind the paddle module and restrict its movement in response to alterations in the membrane potential. During my talk, I would present a toxin derived from a cone-snail venom, exhibiting a novel allosteric action mechanism which seem to defy this traditional classification.

Animal ability to effectively locate and navigate towards food sources is central for survival. Here, using C. elegans nematodes, we revealed a previously unknown mechanism underlying efficient navigation in chemical gradients. This mechanism relies on the orchestrated dynamics of two types of chemosensory neurons: one coding gradients via stochastic pulsatile dynamics, and the second coding the gradients deterministically in a graded manner. The pulsatile dynamics obeys a novel principle where the activity adapts to the magnitude of the gradient derivative, allowing animals to take trajectories better oriented towards the target. The robust response of the second neuron to negative derivatives promotes immediate turns, thus alleviating costs of erroneous turns possibly incurred by the first neuron. This mechanism empowers an efficient navigation strategy which outperforms the classical biased-random walk strategy. Importantly, this mechanism is generalizable and other sensory modalities may use similar principles for efficient gradient-based navigation.

Proximal metallic and semiconductor nanocrystals can interact in various ways. Time-resolved photoluminescence allows to address interaction dependeces, which happen on picosecond timescales. We were able to reveal an unanticipated dependence on the gold nanoparticle size.
Looking deeper into the gold afterwards leads to the plasmon dynamics, for example hot-electron generation, which is happening faster than picoseconds. We found dependences of the hot electron generation on the excitation conditions which will allow more systematic studies of the plasmon-assisted catalysis

The Gulf of Lion (GoL) is an ideal location for investigation of past ecological changes and processes affecting sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.
We analyzed the isotopic composition of organic carbon and nitrogen preserved in sediment core PRGL1-4, and the results highlight the importance of river runoff during warm periods of the last 200 kyr. Regional intercomparison with terrestrial and marine records indicates that these river exports result from an increase in precipitation over the North Mediterranean borderland. The location of PRGL1-4 is outside the Mediterranean cyclogenetic area, and we suggest that these pluvial events occurred in response to enhanced passage of North Atlantic atmospheric perturbations into the Western Mediterranean basin.
We also measured pyrite sulfur isotopes over the last 500 kyr, and find stratigraphic variations (>76‰) that are among the largest ever observed in pyrite. Interestingly, the stratigraphic variations in pyrite sulfur isotope ratios are in phase with glacial-interglacial sea level variations. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: (i) a climatic modulation of the microbial activity and isotope fractionation, and/or (ii) a local early diagenetic sedimentary modulation of microbial fractionation that responds to sea level variations and to associated properties of the depositional environment.