Transcription factor Pax6 regulates cell cycle progression and cell fate determination

The development of the central nervous system relies on the tight regulation of the neural progenitor proliferation and differentiation in order to generate new neurons. The transcription factor Pax6 coordinates these functions during the development of the mammalian forebrain, using the paired DNA binding domain. This is a bipartite DNA-binding domain constituted by two subdomains, the PAI and the RED, binding the DNA in a cooperative or independent manner in order to control specific targets. Focusing on the activity of Pax6 as regulator of cell proliferation and of cell fate determination, I aimed to understanding how these functions are regulated at the molecular level, using the developing ventral forebrain as a model. In this work the role of the RED domain of Pax6 as a regulator of cell cycle progression is investigated. The mutation of the RED subdomain leads to an increase of progenitors in active mitosis (phospho-histone3 positive cells) in the ventral telencephalon at midneurogenesis. Similar result was obtained in the progenitors of the dorsal telencephalon. The increment in the phospho-histone3 positive cells is followed by the increase in cell death in both dorsal and ventral forebrain. These evidences suggest impairments in the cell cycle progression of the progenitor cells in the RED domain mutant. The importance of full activity of the RED domain of Pax6 for the proper progression of the cell cytokinesis is shown via ex-vivo live imaging, performed on ventral developing forebrain of Pax6Leca2 mutant animals (RED domain mutant). To elucidate the molecular mechanisms underlying the observed phenotype, transcriptome of the Pax6Leca2 mutants and their age matching siblings is analyzed, identifying a potential candidate gene: the Holliday junction recognition protein (HJURP). The overexpression of the HJURP protein in the wild type progenitors in vitro resembles the impairment of cytokinesis observed in Pax6Leca2 mutant. In summary, my data suggest new mechanisms for the regulation of cytokinesis in progenitors mediated by the RED domain of Pax6 and indicate that the full functionality of the paired domain is a prerequisite for Pax6 to function as fate determinant

Normal fault earthquakes or graviquakes

Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy accumulated during the interseismic period. However, in crustal extensional settings, gravity is the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times larger than the observed magnitude, far more than enough to explain the earthquake. Therefore, normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the normal fault, the larger is the vertical displacement and the larger is the seismic energy released. Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the other tectonic settings, being the activated fault at most about three times the hypocentre depth, explaining their higher b-value and the lower magnitude of the largest recorded events. Having different phenomenology, graviquakes show peculiar precursor

Evaluating the role of seagrass in Cenozoic CO2 variations

Marine seagrass angiosperms play an important role in carbon sequestration, removing carbon dioxide from the atmosphere and binding it as organic matter. Carbon is stored in the plants themselves, but also in the sediments both in inorganic and organic forms. The inorganic component is represented by carbonates produced by calcareous organisms living as epiphytes on seagrass leaves and rhizomes. In this paper, we find that the rate of seagrass epiphyte production (leaves and rhizomes) averages 400 g m−2 yr−1 , as result of seagrass sampling at seven localities along the Mediterranean coasts, and related laboratory analysis. Seagrasses have appeared in the Late Cretaceous becoming a place of remarkable carbonate production and C sequestration during the whole Cenozoic era. Here, we explore the potential contribution of seagrass as C sink on the atmospheric CO2 decrease by measuring changes in seagrass extent, which is directly associated with variations in the global coastal length associated with plate tectonics. We claim that global seagrass distribution significantly affected the atmospheric composition, particularly at the Eocene-Oligocene boundary, when the CO2 concentration fell to 400 ppm, i.e., the approximate value of current atmospheric CO2

Precise pose estimation of the NASA Mars 2020 Perseverance rover through a stereo-vision-based approach

Visual Odometry (VO) is a fundamental technique to enhance the navigation capabilities of planetary exploration rovers. By processing the images acquired during the motion, VO methods provide estimates of the relative position and attitude between navigation steps with the detection and tracking of two-dimensional (2D) image keypoints. This method allows one to mitigate trajectory inconsistencies associated with slippage conditions resulting from dead-reckoning techniques. We present here an independent analysis of the high-resolution stereo images of the NASA Mars 2020 Perseverance rover to retrieve its accurate localization on sols 65, 66, 72, and 120. The stereo pairs are processed by using a 3D-to-3D stereo-VO approach that is based on consolidated techniques and accounts for the main nonlinear optical effects characterizing real cameras. The algorithm is first validated through the analysis of rectified stereo images acquired by the NASA Mars Exploration Rover Opportunity, and then applied to the determination of Perseverance's path. The results suggest that our reconstructed path is consistent with the telemetered trajectory, which was directly retrieved onboard the rover's system. The estimated pose is in full agreement with the archived rover's position and attitude after short navigation steps. Significant differences (~10–30 cm) between our reconstructed and telemetered trajectories are observed when Perseverance traveled distances larger than 1 m between the acquisition of stereo pairs

Dark Matter Search with Cryogenic Phonon-Light Detectors

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) Dark Matter search is aiming to directly detect Weakly Interacting Massive Particles (WIMPs) via their elastic scattering off nuclei in a target. Due to the low event rate expected for WIMP-nucleus scattering the suppression of background which would hide or mimic the WIMP signal is of crucial importance. Moreover, since the energy transferred to a nucleus in a WIMP-nucleus elastic scattering is extremely low (a few tens of keV), the energy threshold and the sensitivity of detectors are additional fundamental issues in a Dark Matter search. CRESST detectors consist of a 300g CaWO4 scintillating crystal operated as a cryogenic calorimeter in close proximity to a second much smaller cryogenic calorimeter used to detect the scintillation light produced in the target crystal. The lower light yield of nuclear recoils, caused by neutrons and WIMPs, with respect to electron recoils resulting from alpha, beta and gamma interactions is used to identify the event in the scintillating absorber. In the second phase of the CRESST experiment, active background suppression is achieved by the simultaneous measurement of a phonon and a light signal from a scintillating cryogenic calorimeter. Passive background suppression is achieved by operating CRESST detectors in a low background facility located in a deep underground site. About 1% of the energy deposited in CaWO4 by beta or gamma interactions can be detected as scintillation light; therefore the sensitivity of light detectors is a fundamental issue for the discrimination of electron recoils from nuclear recoils at energies relevant for WIMP searches. This work reports on the development of extremely sensitive cryogenic calorimeters for the detection of the scintillation light. These detectors applied a new thermometer geometry characterized by phonon collectors and a thin film thermal coupling to the heat sink. This concept allows a high sensitivity by decoupling the area required for the collection of non-thermal phonons and the heat capacity of the sensor and permits to make the thermal relaxation time of the thermometer long enough to allow for the integration of the scintillation light, despite the slow light emission of CaWO4 at low temperature. Results on new materials to be used as absorbers for a new generation of light detectors are presented. First competitive limits on WIMP Dark Matter established by the CRESST experiment running scintillating CaWO4 cryogenic detectors in association with the light detectors developed in the course of this work are reported together with main results of the detector prototyping phase

Transcription factor Pax6 regulates cell cycle progression and cell fate determination

The development of the central nervous system relies on the tight regulation of the neural progenitor proliferation and differentiation in order to generate new neurons. The transcription factor Pax6 coordinates these functions during the development of the mammalian forebrain, using the paired DNA binding domain. This is a bipartite DNA-binding domain constituted by two subdomains, the PAI and the RED, binding the DNA in a cooperative or independent manner in order to control specific targets. Focusing on the activity of Pax6 as regulator of cell proliferation and of cell fate determination, I aimed to understanding how these functions are regulated at the molecular level, using the developing ventral forebrain as a model. In this work the role of the RED domain of Pax6 as a regulator of cell cycle progression is investigated. The mutation of the RED subdomain leads to an increase of progenitors in active mitosis (phospho-histone3 positive cells) in the ventral telencephalon at midneurogenesis. Similar result was obtained in the progenitors of the dorsal telencephalon. The increment in the phospho-histone3 positive cells is followed by the increase in cell death in both dorsal and ventral forebrain. These evidences suggest impairments in the cell cycle progression of the progenitor cells in the RED domain mutant. The importance of full activity of the RED domain of Pax6 for the proper progression of the cell cytokinesis is shown via ex-vivo live imaging, performed on ventral developing forebrain of Pax6Leca2 mutant animals (RED domain mutant). To elucidate the molecular mechanisms underlying the observed phenotype, transcriptome of the Pax6Leca2 mutants and their age matching siblings is analyzed, identifying a potential candidate gene: the Holliday junction recognition protein (HJURP). The overexpression of the HJURP protein in the wild type progenitors in vitro resembles the impairment of cytokinesis observed in Pax6Leca2 mutant. In summary, my data suggest new mechanisms for the regulation of cytokinesis in progenitors mediated by the RED domain of Pax6 and indicate that the full functionality of the paired domain is a prerequisite for Pax6 to function as fate determinant

'La credenza e il pegno'. Vesti e letteratura tra Parigi e Firenze (secoli XIII-XIV)

Nella seconda metà del Duecento connessioni politiche, economiche e letterarie uniscono Parigi e Firenze: i testi letterari e le vesti si diffondono lungo le vie di comunicazione insieme a oggetti, manoscritti, mercanti, soldati, intellettuali e viaggiatori. Gli abiti vengono comprati, rivenduti, scambiati, sottratti, donati, usati come forma di pagamento. Nei testi gli indumenti funzionano come un linguaggio abbreviato che permette di definire velocemente lo status dei personaggi e allo stesso tempo una valuta che si usa in alternativa al denaro. Tra Francia e Italia i protagonisti dei testi si riferiscono di continuo all’abitudine di usare i propri abiti come pegni per garantire un prestito. Come si vedrà nel saggio, il prestito su pegno offre agli autori e al pubblico un’oc- casione per stabilire il valore delle cose e riflettere sui rapporti tra individui, per interpretare episodi della trama e mettere in discussione la verosimiglianza e la credibilità del racconto