Profound genetic divergence and asymmetric parental genome contributions as hallmarks of hybrid speciation in polyploid toads.

The evolutionary causes and consequences of allopolyploidization, an exceptional pathway to instant hybrid speciation, are poorly investigated in animals. In particular, when and why hybrid polyploids versus diploids are produced, and constraints on sources of paternal and maternal ancestors, remain underexplored. Using the Palearctic green toad radiation (including bisexually reproducing species of three ploidy levels) as model, we generate a range-wide multi-locus phylogeny of 15 taxa and present four new insights: (i) at least five (up to seven) distinct allotriploid and allotetraploid taxa have evolved in the Pleistocene; (ii) all maternal and paternal ancestors of hybrid polyploids stem from two deeply diverged nuclear clades (6 Mya, 3.1-9.6 Mya), with distinctly greater divergence than the parental species of diploid hybrids found at secondary contact zones; (iii) allotriploid taxa possess two conspecific genomes and a deeply diverged allospecific one, suggesting that genomic imbalance and divergence are causal for their partly clonal reproductive mode; (iv) maternal versus paternal genome contributions exhibit asymmetry, with the maternal nuclear (and mitochondrial) genome of polyploids always coming from the same clade, and the paternal genome from the other. We compare our findings with similar patterns in diploid/polyploid vertebrates, and suggest deep ancestral divergence as a precondition for successful allopolyploidization

Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor

Charge density waves are a common occurrence in all families of high critical temperature superconducting cuprates. Although consistently observed in the underdoped region of the phase diagram and at relatively low temperatures, it is still unclear to what extent they influence the unusual properties of these systems. Using resonant x-ray scattering we carefully determined the temperature dependence of charge density modulations in (Y,Nd)Ba$_2$Cu$_3$O$_{7-{\delta}}$ for three doping levels. We discovered short-range dynamical charge density fluctuations besides the previously known quasi-critical charge density waves. They persist up to well above the pseudogap temperature T*, are characterized by energies of few meV and pervade a large area of the phase diagram, so that they can play a key role in shaping the peculiar normal-state properties of cuprates.Comment: 34 pages, 4 figures, 11 supplementary figure

Polarization resolved Cu L3L_3-edge resonant inelastic x-ray scattering of orbital and spin excitations in NdBa2_{2}Cu3_{3}O7−δ_{7-\delta}

High resolution resonant inelastic x-ray scattering (RIXS) has proven particularly effective in the determination of crystal field and spin excitations in cuprates. Its strength lies in the large Cu $L_{3}$ resonance and in the fact that the scattering cross section follows quite closely the single-ion model predictions, both in the insulating parent compounds and in the superconducting doped materials. However, the spectra become increasingly broader with (hole) doping, hence resolving and assigning spectral features has proven challenging even with the highest energy resolution experimentally achievable. Here we have overcome this limitation by measuring the complete polarization dependence of the RIXS spectra as function of momentum transfer and doping in thin films of NdBa$_{2}$Cu$_{3}$O$_{7-\delta}$. Besides confirming the previous assignment of $dd$ and spin excitations (magnon, bimagnon) in the antiferromagnetic insulating parent compound, we unequivocally single out the actual spin-flip contribution at all dopings. We also demonstrate that the softening of $dd$ excitations is mainly attributed to the shift of the $xy$ peak to lower energy loss. These results provide a definitive assessment of the RIXS spectra of cuprates and demonstrate that RIXS measurements with full polarization control are practically feasible and highly informative.Comment: 14 pages, 10 figure

Fractional Spin Excitations in the Infinite-Layer Cuprate CaCuO2

We use resonant inelastic x-ray scattering (RIXS) to investigate the magnetic dynamics of the infinite-layer cuprate CaCuO2. We find that close to the (1/2,0) point, the single magnon decays into a broad continuum of excitations accounting for about 80% of the total magnetic spectral weight. Polarization-resolved RIXS spectra reveal the overwhelming dominance of the spin-flip (Delta S = 1) character of this continuum with respect to the Delta S = 0 multimagnon contributions. Moreover, its incident-energy dependence is identical to that of the magnon, supporting a common physical origin. We propose that the continuum originates from the decay of the magnon into spinon pairs, and we relate it to the exceptionally high ring exchange J(c) similar to J(1) of CaCuO2. In the infinite-layer cuprates, long-range and multisite hopping integrals are very important, and they amplify the 2D quantum magnetism effects in spite of the 3D antiferromagnetic Neel order

Symmetry breaking at the (111) interfaces of SrTiO3{_3} hosting a 2D-electron system

We used x-ray absorption spectroscopy to study the orbital symmetry and the energy band splitting of (111) LaAlO${_3}$/SrTiO${_3}$ and LaAlO${_3}$/EuTiO${_3}$/SrTiO${_3}$ heterostructures, hosting a quasi two-dimensional electron system (q2DES), and of a Ti-terminated (111) SrTiO${_3}$ single crystal, also known to form a q2DES at its surface. We demonstrate that the bulk tetragonal Ti-3d D${_4}$${_h}$ crystal field is turned into trigonal D${_3}$${_d}$ crystal field in all cases. The symmetry adapted a${_1}$${_g}$ and e${^\pi_g}$ orbitals are non-degenerate in energy and their splitting, \Delta, is positive at the bare STO surface but negative in the heterostructures, where the a${_1}$${_g}$ orbital is lowest in energy. These results demonstrate that the interfacial symmetry breaking induced by epitaxial engineering of oxide interfaces has a dramatic effect on their electronic properties, and it can be used to manipulate the ground state of the q2DES.Comment: 6 pages article, plus 5 pages supplementary informatio

A 48-week update of a multicentre real-life experience of dupilumab in adult patients with moderate-to-severe atopic dermatitis

The long-term efficacy and safety of dupilumab has been demonstrated in clinical trials and only in few real-world studies. We conducted an extension analysis from a previous 16-week study on 109 adult patients affected by moderate-to-severe atopic dermatitis treated with dupilumab. Eczema-Area-and-Severity-Index (EASI), itch numerical-rating-score (itch-NRS), Dermatology-Life-Quality-Index (DLQI) scores, drug survival rate and occurrence of adverse events after 24 and 48 weeks of dupilumab treatment were retrospectively collected. Dupilumab demonstrated sustained improvement of disease severity, pruritus, and quality of life in our series with an increasing percentage of patients gaining EASI75 and EASI90 response during the study period. Few patients interrupted treatment resulting in a very high drug survival rate. We also confirmed the favorable safety profile of the drug with absence of serious adverse events and serious infections throughout the 48-week period. The prevalence of conjunctivitis was low and mainly occurred in the mid-term with resolution of the majority of cases at 48 weeks

Threatened and extinct amphibians and reptiles in Italian natural history collections are useful conservation tools

Natural history museums are irreplaceable tools to study and preserve the biological diversity around the globe and among the primary actors in the recognition of species and the logical repositories for their type specimens. In this paper we surveyed the consistency of the preserved specimens of amphibians and reptiles housed in the major Italian scientific collections, and verified the presence of threatened species according to the IUCN Red List, includ-ing the Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), and Vulnerable (VU) categories. Altogether, we analyzed 39 Italian zoological collections. We confirmed the presence of one extinct reptile (Chioninia coctei) and five extinct or extinct in the wild amphibian species (Atelopus longirostris, Nectophrynoides asperginis, Pseudophilautus leucorhinus, P. nasutus, and P. variabilis). Seven CR amphibians, fourteen CR reptile species and the extinct skink C. coctei are shared by more than one institution. Museums which host the highest number of threatened and extinct amphibian species are respectively Turin (17 CR and 1 EX), Florence (13 CR and 1 EX), and Trento (15 CR and 1 EW), while for reptiles the richest museums are those from Genoa (15 CR and 1 EX), Florence (11 CR and 1 EX), and Pisa (7 CR). Finally, we discussed the utility of natural history museums and the strategies to follow for the implementation of their functionality. © Firenze University Press