Coronin Promotes the Rapid Assembly and Cross-linking of Actin Filaments and May Link the Actin and Microtubule Cytoskeletons in Yeast

Coronin is a highly conserved actin-associated protein that until now has had unknown biochemical activities. Using microtubule affinity chromatography, we coisolated actin and a homologue of coronin, Crn1p, from Saccharomyces cerevisiae cell extracts. Crn1p is an abundant component of the cortical actin cytoskeleton and binds to F-actin with high affinity (Kd 6 × 10−9 M). Crn1p promotes the rapid barbed-end assembly of actin filaments and cross-links filaments into bundles and more complex networks, but does not stabilize them. Genetic analyses with a crn1Δ deletion mutation also are consistent with Crn1p regulating filament assembly rather than stability. Filament cross-linking depends on the coiled coil domain of Crn1p, suggesting a requirement for Crn1p dimerization. Assembly-promoting activity is independent of cross-linking and could be due to nucleation and/or accelerated polymerization. Crn1p also binds to microtubules in vitro, and microtubule binding is enhanced by the presence of actin filaments. Microtubule binding is mediated by a region of Crn1p that contains sequences (not found in other coronins) homologous to the microtubule binding region of MAP1B. These activities, considered with microtubule defects observed in crn1Δ cells and in cells overexpressing Crn1p, suggest that Crn1p may provide a functional link between the actin and microtubule cytoskeletons in yeast

Neutrino oscillation studies with IceCube-DeepCore

AbstractIceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed

Le fratture dell'estremo prossimale dell'omero: incidenza e classificazioni

Fractures of the proximal humerus are common and their incidence increases with age and, consequently, with the degree of osteoporosis. Over time, many classification systems regarding these fractures have been proposed. The aim of classification is to define a fracture on the basis offixed parameters (morphologic characteristics and fracture pathoanatomy) that can be used for better understanding offracture severity, prognosis and potential surgical options. Most classifications are based on the X-ray appearance of the humeral head fracture on plain films; recently 3D-CT scans have complemented traditional radiograms. Neer developed a classification system based on fracture pathoanatomy and on the presence or absence of displacement of one or more of the four major bony segments (surgical neck, anatomic neck, greater and lesser tuberosity). The AO classification system included the concept ofperfusion of the articular segment. Edelson divided humeral head fractures into five basic types that correspond to some degree to the Neer classification, but dijfer significantly regarding the most complex patterns offracture. Furthermore, an interohserver reliability study indicated the improved usefulness of the 3-D concept in providing a common language among clinicians for classifying these injuries. Finally, Hertel developed a classification system for better understanding the predictors of humeral head ischemia. In conclusion, a fracture must be classified for understanding its severity and guiding the treatment. Radiographics are often not sufficient for establishing the number offragments and the entity of their dislocation. 3D-CT scans allow medial hinge condition and other predictors of humeral head ischemia to be better understood