Honey bees increase social distancing when facing the ectoparasite Varroa destructor

Social distancing in response to infectious diseases is a strategy exhibited by human and nonhuman animals to counteract the spread of pathogens and/or parasites. Honey bee (Apis mellifera) colonies are ideal models to study this behavior because of the compartmentalized structure of these societies, evolved under exposure to parasite pressure and the need to ensure efficient functioning. Here, by using a combination of spatial and behavioral approaches, we investigated whether the presence of the ectoparasite mite Varroa destructor induces changes in the social organization of A. mellifera colonies that could reduce the spread of the parasite. Our results demonstrated that honey bees react to the intrusion of V. destructor by modifying space use and social interactions to increase the social distancing between young (nurses) and old (foragers) cohorts of bees. These findings strongly suggest a behavioral strategy not previously reported in honey bees to limit the intracolony parasite transmission

Small Fermi energy and phonon anharmonicity in MgB_2 and related compounds

The remarkable anharmonicity of the E_{2g} phonon in MgB_2 has been suggested in literature to play a primary role in its superconducting pairing. We investigate, by means of LDA calculations, the microscopic origin of such an anharmonicity in MgB_2, AlB_2, and in hole-doped graphite. We find that the anharmonic character of the E_{2g} phonon is essentially driven by the small Fermi energy of the sigma holes. We present a simple analytic model which allows us to understand in microscopic terms the role of the small Fermi energy and of the electronic structure. The relation between anharmonicity and nonadiabaticity is pointed out and discussed in relation to various materials.Comment: 5 pages, 2 figures replaced with final version, accepted on Physical Review

Isolating stem cells from skin: designing a novel highly efficient non-enzymatic approach

Stem cells are undifferentiated elements capable to acquire a specific cellular phenotype under the influence of specific stimuli, thus being involved in tissue integrity and maintenance. In the skin tissue self-renewal and wound healing after injury is a complex process, especially in adulthood, due to the aging process and the continuous exposure to damaging agents. The importance of stem cells in regenerative medicine is well known and defining or improving their isolation methods is therefore a primary and crucial step. In the present paper we present a novel method to isolate stem cells from human skin, including the involvement of a novel medium for the maintenance and expansion of in vitro cultures. The biopsies were mechanically digested and put in culture. The migrating cells were positive selected with magnetic cell sorting, characterized by flow-cytometry analysis, and viability detected by MTT assay. Cells exhibited a mesenchymal phenotype, as demonstrated by the positive acquirement of an osteogenic or adipogenic phenotype when cultured in specific conditioned media. Taken together our results disclose a novel method for culturing and expanding stem cells from skin and pave the way for future clinical applications in tissue regeneration

INTEGRATING CLIMATE CHANGE ADAPTATION INTO SEA AN ASSESSMENT FOR SARDINIA, ITALY

Climate Change (CC) is recognized as an urgent concern, which implies negative effects on the environment, such as sea level rise, coastal erosion, fl ooding, droughts, and desertifi cation. It involves not only the environmental, but also the economic, and social sphere. The impacts of CC are addressed through two complementary strategies: mitigation and adaptation. The fi rst one operates on the reasons of CC aiming at preventing or reducing greenhouse gases emissions, while the second one focuses on the damage they can cause, aiming at minimizing it or to take advantage of opportunities that may occur. Strategic Environmental Assessment (SEA) represents a systematic and participatory decisionmaking support process, aiming at integrating environmental considerations in the elaboration of plans and programs. While SEA regards explicitly mitigation strategies, so far it still refers marginally to CC adaptation measures to be carried on when implementing spatial planning tools at the regional and local scale. The integration of SEA processes with concepts inspired to adaptation to CCs represents a powerful tool for mainstreaming the corresponding policies and strategies. In this study, we scrutinize SEA and spatial planning tools issued in Sardinia (Italy), with reference to their attitude to incorporate possible climate adaptation concerns. We are interested in proposing and applying a framework based on internationally acknowledged criteria that need to be met to properly implement climate change adaptation measures and actions in current spatial planning and SEA practices

Circulating haematopoietic and endothelial progenitor cells are decreased in COPD

Circulating CD34+ cells are haemopoietic progenitors that may play a role in tissue repair. No data are available on circulating progenitors in chronic obstructive pulmonary disease (COPD). Circulating CD34+ cells were studied in 18 patients with moderate-to-severe COPD (age: mean+/-sd 68+/-8 yrs; forced expiratory volume in one second: 48+/-12% predicted) and 12 controls, at rest and after endurance exercise. Plasma concentrations of haematopoietic growth factors (FMS-like tyrosine kinase 3 (Flt3) ligand, kit ligand), markers of hypoxia (vascular endothelial growth factor (VEGF)) and stimulators of angiogenesis (VEGF, hepatocyte growth factor (HGF)) and markers of systemic inflammation (tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8) were measured. Compared with the controls, the COPD patients showed a three-fold reduction in CD34+ cell counts (3.3+/-2.5 versus 10.3+/-4.2 cells.microL-1), and a 50% decrease in AC133+ cells. In the COPD patients, progenitor-derived haemopoietic and endothelial cell colonies were reduced by 30-50%. However, four COPD patients showed progenitor counts in the normal range associated with lower TNF-alpha levels. In the entire sample, CD34+ cell counts correlated with exercise capacity and severity of airflow obstruction. After endurance exercise, progenitor counts were unchanged, while plasma Flt3 ligand and VEGF only increased in the COPD patients. Plasma HGF levels were higher in the COPD patients compared with the controls and correlated inversely with the number of progenitor-derived colonies. In conclusion, circulating CD34+ cells and endothelial progenitors were decreased in chronic obstructive pulmonary disease patients and could be correlated with disease severity

Identification of ‘Candidatus Phytoplasma’ species in “huanglongbing” infected citrus orchards in the Caribbean

“Huanglongbing” (HLB) is one of the most devastating diseases of citrus orchards worldwide. Samples from 183 citrus plants of different cultivars and rootstock/cultivar combinations, showing HLB symptoms in three Caribbean countries (Cuba, Jamaica, and Guadeloupe-France), were collected to verify the possible co-infection of ‘Candidatus Phytoplasma’ and ‘Candidatus Liberibacter’ species. The 64% of the samples resulted positive to the ‘Ca. L. asiaticus’ and the 27% to diverse ‘Ca. Phytoplasma’-related species, moreover about the 14% of the samples infected with ‘Ca. Liberibacter’ were also found positive to phytoplasmas, indicating the presence of mixed infection especially in the orchards located in Cuba. Moreover, in one of the samples from Jamaica mixed phytoplasma infection was detected. Moreover the detection of only phytoplasmas in 11 symptomatic citrus samples collected from Cuba and Guadeloupe without ‘Ca. Liberibacter’ detection, confirmed that the symptomatology cannot be the sole criterium to discriminate between the presence of the two pathogens, and molecular detection is necessary to identify single or mixed infections. Diaphorina citri insects collected from Cuba and Guadeloupe resulted infected with ‘Ca. L. asiaticus’ confirming its active role in the dissemination of the pathogen. Only one insect of the Cicadidae family, collected in Guadeloupe, was found positive for phytoplasma presence. Considering that the phytoplasmas belonging to some ‘Candidatus species’ were detected in the three countries in different citrus varieties, a relevant role as phytoplasma reservoir can be attribute to citrus orchards

Surface and Image-Potential States on the MgB_2(0001) Surfaces

We present a self-consistent pseudopotential calculation of surface and image-potential states on $MgB_2(0001)$ for both $B$-terminated ($B-t$) and $Mg$-terminated ($Mg-t$) surfaces. We find a variety of very clear surface and subsurface states as well as resonance image-potential states n=1,2 on both surfaces. The surface layer DOS at $E_F$ is increased by 55% at $B-t$ and by 90% at the $Mg-t$ surface compared to DOS in the corresponding bulk layers.Comment: 3 pages, 6 figure