MicroRNA in control of gene expression: An overview of nuclear functions

The finding that small non-coding RNAs (ncRNAs) are able to control gene expression in a sequence specific manner has had a massive impact on biology. Recent improvements in high throughput sequencing and computational prediction methods have allowed the discovery and classification of several types of ncRNAs. Based on their precursor structures, biogenesis pathways and modes of action, ncRNAs are classified as small interfering RNAs (siRNAs), microRNAs (miRNAs), PIWI-interacting RNAs (piRNAs), endogenous small interfering RNAs (endo-siRNAs or esiRNAs), promoter associate RNAs (pRNAs), small nucleolar RNAs (snoRNAs) and sno-derived RNAs. Among these, miRNAs appear as important cytoplasmic regulators of gene expression. miRNAs act as post-transcriptional regulators of their messenger RNA (mRNA) targets via mRNA degradation and/or translational repression. However, it is becoming evident that miRNAs also have specific nuclear functions. Among these, the most studied and debated activity is the miRNA-guided transcriptional control of gene expression. Although available data detail quite precisely the effectors of this activity, the mechanisms by which miRNAs identify their gene targets to control transcription are still a matter of debate. Here, we focus on nuclear functions of miRNAs and on alternative mechanisms of target recognition, at the promoter lavel, by miRNAs in carrying out transcriptional gene silencing

Contributo alla conoscenza della brioflora del Sulcis (Sardegna sud-occidentale)

A first contribution to the knowledge of the bryological flora of Sulcis is presented. The total number of species amounts to 216 entities belonging to classes of Musci(186), Hepaticae (29) and Anthocerotae (1); finding of 30 new species to Sulcis is reported. A chorological analysis is also done

A powerful computational crystallography method to study ice polymorphism

Classical Molecular Dynamics (MD) simulations are employed as a tool to investigate structural properties of ice crystals under several temperature and pressure conditions. All ice crystal phases are analyzed by means of a computational protocol based on a clustering approach following standard MD simulations. The MD simulations are performed by using a recently published classical interaction potential for oxygen and hydrogen in bulk water, derived from neutron scattering data, able to successfully describe complex phenomena such as proton hopping and bond formation/breaking. The present study demonstrates the ability of the interaction potential model to well describe most ice structures found in the phase diagram of water and to estimate the relative stability of sixteen known phases through a cluster analysis of simulated powder diagrams of polymorphs obtained from MD simulations. The proposed computational protocol is suited for automated crystal structure identification.Comment: RevTex 4.1, 7 figures - to be published in the Journal of Chemical Physic

Optimization of Heliostat Fields for Solar Tower Systems

In this work, a geometrical model is used to evaluate the sun radiation reflected from the heliostats toward the aim point on the tower top, by taking into account the shading and blocking between neighboring heliostats. This results in an analytical expression for the heliostats efficiency, which can provide very useful informations for the optimization of the heliostat field. In particular, we obtain a very simple and exact expression of the maximal energy collectable by the solar field and present effective strategies to reach such maximum.2012-09-11Perpignan, Morocco, Marrakech; 2012Proceedings of the 18th International SolarPaces Symposiu

An eco-physiological and biotechnological approach to conservation of the world-wide rare and endangered aquatic liverwort Riella helicophylla (Bory et Mont.) Mont.

The rare aquatic liverwort Riella helicophylla (Bory et Mont.) Mont., inhabitant of temporary shallow ponds around the Mediterranean basin, is considered threatened throughout its distribution range. In addition, little is known of its biology and ecology or of its role in such an important ecosystem where envi- ronmental conditions vary yearly in unpredictable ways. In these variable habitats, due to the seasonal fluc- tuation of water levels, there is no guarantee of yearly spore input into the spore bank. Spore germination rate and the effects of different culture media in an axenic culture establishment, as well as propagation proce- dures of R. helicophylla, were tested. New insights into the ecology and biology of R. helicophylla are given. Spore dormancy is documented, and the protocols for the in vitro culture establishment, propagation and ac- climatization of this liverwort are developed. Dry storage at 20 ± 2 °C for about three months broke the dor- mancy of spores, which subsequently germinated in a high percentage (over 90%). A two phase (solid and liquid) culture media system was developed for the purpose of achieving fully developed gametophytes. The liquid phase contained electrolytes simulating brackish water

Conserving plant diversity in Europe: outcomes, criticisms and perspectives of the Habitats Directive application in Italy

Habitat Directive is the core strategy of nature conservation in Europe aiming at halting biodiversity loss. In this study the results of the third Italian assessment regarding the conservation status (CS) of plants listed in the Habitat Directive (Flora of community interest—FCI) was presented. Data was collected from several sources related to plant distribution, population data, habitats and pressures. Following the official European procedure, all parameters were evaluated and combined to give the CS of each taxon in each biogeographical region of presence. A comparison between the recent Italian IUCN and Reporting assessments was performed in order to evaluate the consistency between these two assessments. The official EU checklist comprises 113 Italian plant taxa, 107 of which were examined in this study. Our results showed a critical situation with only 34% of favourable CS, while 50% were unfavourable (40% inadequate plus 10% bad) and 16% unknown, in particular in the Mediterranean bioregion, where the unfavourable assessments reach the 65%. The results of the Report were consistent with those of the IUCN assessment, in which 41.9% of plants were threatened with extinction. This report highlighted some benefits and criticisms at national level, but it may have a wider significance. Although a general advance of knowledge, a great effort is needed to reach the Habitats Directive goals. Despite the limited resources, monitoring activities needs to be improved in order to close information gaps for several plants. A positive outcome was the development of a specific national project funded by the Italian Ministry of Environment, with the ambitious target to set future monitoring activities for FCI and optimize monitoring efforts

Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 3

In this contribution, new data concerning bryophytes, fungi and lichens and of the Italian flora are presented. It includes new records and confirmations for the bryophyte genera Dicranodontium, Fontinalis, Lophocoleaand Riccia, the fungal genus Diplolaeviopsis, the lichen genera Agonimia, Cladonia, Protoparmelia, Rhizocarpon, and Scytinium