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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.

The introduction of two-photon microscopy for in vivo imaging has opened the door to chronic monitoring of individual neurons in the adult brain and the study of structural plasticity mechanisms at a very fine scale. Perhaps the biggest contribution of this modern anatomical method has been the discovery that even across the stable excitatory dendritic scaffold there is significant capacity for synaptic remodeling, and that synaptic structural rearrangements are a key mechanism mediating neural circuit adaptation and behavioral plasticity in the adult. To monitor the extent and nature of excitatory and inhibitory synapse dynamics on individual L2/3 pyramidal neurons in mouse visual cortex in vivo, we labeled these neurons with a fluorescent cell fill as well as the fluorescently tagged synaptic scaffolding molecules, Teal-Gephyrin to label inhibitory synapses, and mCherry-PSD-95 to label excitatory synapses. We simultaneously tracked the daily dynamics of both synapse types using spectrally resolved two-photon microscopy. We found that aside from the lower magnitude of excitatory synaptic changes in the adult, as compared to inhibitory ones, excitatory synapse dynamics appear to follow a different logic than inhibitory dynamics. While excitatory dynamics seem to follow a sampling strategy to search for and create connections with new presynaptic partners, inhibitory synapse dynamics likely serve to locally modulate gain at specific cellular locales.

Sensory photoreceptor proteins underpin sensation of incident light and mediate numerous organismal adaptations of behavior, lifestyle and physiology. Photoreceptors excel in the reversibility, noninvasiveness and spatiotemporal precision of the biological responses they elicit. For exactly these benefits, photoreceptors have found frequent use as light-gated actuators for the control by light of intracellular processes and parameters, an application area known as optogenetics. The engineering of novel photoreceptors, that is, protein actuators with custom-tailored light-gated function, has greatly expanded the repertoire provided by natural photoreceptors and has thereby unlocked additional areas for optogenetic intervention. By recombining blue-light-sensitive light-oxygen-voltage (LOV) photosensor modules with effector modules of desired output activity, we have generated several implements for the optogenetic control of nucleic-acid-based biological processes, e.g., endonuclease cleavage and gene expression. Biochemical analyses of structure, function and signaling mechanism of sensory photoreceptors unravel the molecular bases for light-dependent allostery and inform the engineering of additional representatives.

TBA