Electron-phonon interaction in the solid form of the smallest fullerene C20_{20}

The electron-phonon coupling of a theoretically devised carbon phase made by assembling the smallest fullerenes C$_{20}$ is calculated from first principles. The structure consists of C$_{20}$ cages in an {\it fcc} lattice interlinked by two bridging carbon atoms in the interstitial tetrahedral sites ({\it fcc}-C$_{22}$). The crystal is insulating but can be made metallic by doping with interstitial alkali atoms. In the compound NaC$_{22}$ the calculated coupling constant $\lambda/N(0)$ is 0.28 eV, a value much larger than in C$_{60}$, as expected from the larger curvature of C$_{20}$. On the basis of the McMillan's formula, the calculated $\lambda$=1.12 and a $\mu^*$ assumed in the range 0.3-0.1 a superconducting T$_c$ in the range 15-55 K is predicted.Comment: 7 page

Deciphering the light signal transduction mechanism in Staphylococcus aureus

Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii have been recognized by the WHO and the CDC as critical human pathogens. These microorganisms belong to the ESKAPE group, so named since they are capable of "escaping" antibiotic treatments. The infections caused by these pathogens result in a dramatic increase in the costs of medical care. Previous results from our laboratory have shown that these microorganisms can sense and respond to light. In S. aureus, light has been shown to modulate important pathogenicity determinants such as alpha toxin-dependent hemolysis, as well as virulence in an epithelial infection model, which could have implications in human infections. Light also regulates persistence, metabolism, and the ability to kill competitors such as C. albicans, in this microorganism. To our knowledge, the ability of S. aureus to sense and respond to light constitutes a newly described physiological trait. These pathogens could sense light to synchronize their behavior with the circadian rhythm of their hosts, likely as a strategy to optimize infection development. Identification of the photoreceptors involved in light sensing in S. aureus would provide important insights into the light signal transduction cascade. Despite no traditional photoreceptors were found encoded in its genome, we identified the presence of three putative proteins containing GAF domains. GAF domains have been shown to be part of phytochromes and cyanobacteriochromes along with other domains such as PHY and PAS. While in two of them the GAF domain encompasses the full-length protein sequence, suggesting a new photoreceptor architecture, the last one harbors a GAF N-terminal domain associated with a C-terminal histidine kinase. The genomic environment of each putative photoreceptor was determined, and genes such as LuxR, involved in a quorum-sensing regulation; and DegU, identified as a response regulator of bacterial motility, virulence and biofilm formation, were found in their close proximity. Recent results from our group show that motility in S. aureus is not only modulated by blue light, but also by red and green lights. This is compatible with multiple GAF photoreceptors as they exist in two thermally stable states interconvertible by light, absorbing in different regions of the spectrum. Moreover, the presence of three cysteine residues were observed, residue shown to be essential for binding of the bilin chromophore. In this sense, it is interesting to note that S. aureus produces Staphylobilin as a product of heme metabolism. In addition, we amplified the DNA fragments encoding these putative photoreceptors from S. aureus USA300 strain, and subcloned them into the expression vector pET-TEV, to corroborate that they are active photoreceptors upon light absorption. Finally, proteomic results are discussed which suggest new pathways modulated by light in S. aureus such as cell wall synthesis and recycling.Fil: Arana, N. A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Müller, G. L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Mussi, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaLVII SAIB Meeting; XVI SAMIGE MeetingArgentinaSociedad Argentina De Investigación Bioquímica Y Biología MolecularSociedad Argentina de Microbiología Genera

Fishing activities overlap with bottlenose dolphin core habitats of Ischia and Procida islands

Tursiops truncatus – the common bottlenose dolphin – is a species of conservation interest, listed in Annex II and IV of Habitat Directive (92/43/CEE) that requires strict protection and the creation of specially protected areas for conservation, managed according to the ecological requirements of the species, within the “Nature 2000” network. A local population of bottlenose dolphins has been monitored over fifteen years in the sea waters around Ischia and Procida Islands in the frame of the Ischia Dolphin Project, an ongoing long-term research program on Tyrrhenian cetaceans. The study area lies partially within the boundaries of "Regno di Nettuno" Marine Protected Area (MPA), which is classified by IUCN as an Important Marine Mammal Area (IMMA), where pods of cetacean key species such as common dolphin (Delphinus Delphis), bottlenose dolphin, and fin whale (Balaenoptera physalus) live. Investigating habitat exploitation by bottlenose dolphins is crucial for conserving this protected species. Between 2004 and 2018, 1186 surveys were performed, resulting in 91 encounters with the species. To investigate bottlenose dolphins' habitat exploitation, we combined both behavioral observations and spatial analysis. Kernel Density Estimation and Hotspot analysis allowed to delineate fine-scale areas of higher concentration of critical activities (feeding, socializing/mating, resting) and interactions with fisheries (gillnets and trawlers). Results show a vital region for feeding, resting, social cohesion, and mating, i.e. essential habitat for bottlenose dolphins. Unfortunately, these critical habitats are only partially protected by the zonation of the MPA, because it overlaps with human activities, especially fishing. Although the influence of fisheries on dolphins' behavior and movements needs further investigation, the results thus far collected suggest that effective management measures should take into account the human-animal conflict that can arise in these critical areas