Linear scale bounds on dark matter--dark radiation interactions and connection with the small scale crisis of cold dark matter

One of the open questions in modern cosmology is the small scale crisis of the cold dark matter paradigm. Increasing attention has recently been devoted to self-interacting dark matter models as a possible answer. However, solving the so-called "missing satellites" problem requires in addition the presence of an extra relativistic particle (dubbed dark radiation) scattering with dark matter in the early universe. Here we investigate the impact of different theoretical models devising dark matter dark radiation interactions on large scale cosmological observables. We use cosmic microwave background data to put constraints on the dark radiation component and its coupling to dark matter. We find that the values of the coupling allowed by the data imply a cut-off scale of the halo mass function consistent with the one required to match the observations of satellites in the Milky Way.Comment: 7 pages, 4 figures. Comments welcom

Single-vesicle imaging reveals lipid-selective and stepwise membrane disruption by monomeric α-synuclein

The interaction of the neuronal protein α-synuclein with lipid membranes appears crucial in the context of Parkinson\u27s disease, but the underlying mechanistic details, including the roles of different lipids in pathogenic protein aggregation and membrane disruption, remain elusive. Here, we used single-vesicle resolution fluorescence and label-free scattering microscopy to investigate the interaction kinetics of monomeric α-synuclein with surface-tethered vesicles composed of different negatively charged lipids. Supported by a theoretical model to account for structural changes in scattering properties of surface-tethered lipid vesicles, the data demonstrate stepwise vesicle disruption and asymmetric membrane deformation upon α-synuclein binding to phosphatidylglycerol vesicles at protein concentrations down to 10 nM (∼100 proteins per vesicle). In contrast, phosphatidylserine vesicles were only marginally affected. These insights into structural consequences of α-synuclein interaction with lipid vesicles highlight the contrasting roles of different anionic lipids, which may be of mechanistic relevance for both normal protein function (e.g., synaptic vesicle binding) and dysfunction (e.g., mitochondrial membrane interaction)

First As Probe, Then As Function - Fluorescence in Bio-inspired Nanotechnology

In this thesis, I demonstrate how fluorescence can be used in the context of bio-inspired nanotechnology, both as an indirect probe and as a function in itself. By combining principles and molecules from three different bio-molecular systems, DNA, bacterial light-harvesting complexes and cell membranes, I have constructed nano- and microscale systems for long-range excitation energy transfer, light-harvesting and reaction control.In the first part of the work, DNA is utilized as a scaffold for fluorophores, arranged in a manner that facilitates excitation energy transfer from either one end of a wire to the other, or from a single input to two separate outputs in a nanoscale DNA network. These photonic assemblies use Pacific Blue and Cy3 as input and output fluorophores, respectively. The network also comprises fluorescein as an alternative output. Both systems rely on the intercalator YO-PRO-1 to mediate energy transfer between input and output. With this design, it is possible to construct a 20-mer wire with over 90% end-to-end efficiency and a longer 50-mer wire that enables energy transfer over more than 20 nm. In the network, it is possible to regulate the flow of excitation energy between the two spatially and spectrally separate outputs.In the second part, a DNA-based light-harvesting complex is presented. By loading the DNA scaffold with intercalators it is possible to enhance the excitation of a membrane-anchored porphyrin acceptor through energy transfer from the YO-PRO-1 donors. Using a linear and a hexagonal light-harvesting complex the excitation of the acceptor porphyrin can be enhanced by a factor of 13 and 18, respectively. Finally in the third part, lipid monolayer films with incorporated DNA molecules are created on hydrophobic substrates. DNA moves inside the film and can therefore interact and form duplexes with complementary strands also incorporated in the film. This process is studied in patterned surfaces where the mixing of lipid films is restricted by the shape of the hydrophobic support. The hybridization mechanism is investigated using single molecule fluorescence spectroscopy, showing that the duplex formation rate depends on the length of the DNA strand

First As Probe, Then As Function - Fluorescence in Bio-inspired Nanotechnology

In this thesis, I demonstrate how fluorescence can be used in the context of bio-inspired nanotechnology, both as an indirect probe and as a function in itself. By combining principles and molecules from three different bio-molecular systems, DNA, bacterial light-harvesting complexes and cell membranes, I have constructed nano- and microscale systems for long-range excitation energy transfer, light-harvesting and reaction control.In the first part of the work, DNA is utilized as a scaffold for fluorophores, arranged in a manner that facilitates excitation energy transfer from either one end of a wire to the other, or from a single input to two separate outputs in a nanoscale DNA network. These photonic assemblies use Pacific Blue and Cy3 as input and output fluorophores, respectively. The network also comprises fluorescein as an alternative output. Both systems rely on the intercalator YO-PRO-1 to mediate energy transfer between input and output. With this design, it is possible to construct a 20-mer wire with over 90% end-to-end efficiency and a longer 50-mer wire that enables energy transfer over more than 20 nm. In the network, it is possible to regulate the flow of excitation energy between the two spatially and spectrally separate outputs.In the second part, a DNA-based light-harvesting complex is presented. By loading the DNA scaffold with intercalators it is possible to enhance the excitation of a membrane-anchored porphyrin acceptor through energy transfer from the YO-PRO-1 donors. Using a linear and a hexagonal light-harvesting complex the excitation of the acceptor porphyrin can be enhanced by a factor of 13 and 18, respectively. Finally in the third part, lipid monolayer films with incorporated DNA molecules are created on hydrophobic substrates. DNA moves inside the film and can therefore interact and form duplexes with complementary strands also incorporated in the film. This process is studied in patterned surfaces where the mixing of lipid films is restricted by the shape of the hydrophobic support. The hybridization mechanism is investigated using single molecule fluorescence spectroscopy, showing that the duplex formation rate depends on the length of the DNA strand

Distribuzione dei recettori TRK per le neurotrofine nei tessuti nervosi e non-nervosi nel teleosteo Dicentrarchus labrax

Dottorato di ricerca in morfologia delle specie ittiche e degli uccelli. 12. ciclo. A.a. 1996-99. Coordinatore e docente guida Emilia CiriacoConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal