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

Stochastic modeling of nonisothermal antisolvent crystallization processes

In this Thesis a stochastic approach to model antisolvent crystallization processes is addressed. The motivations to choice a stochastic approach instead of a population balance modeling has been developed to find a simple and an alternative way to describe the evolution of the Crystal Size Distribution (CSD), without consider complex thermodynamic and kinetic aspects of the process. An important parameter to consider in crystallization process is the shape of the CSD (in terms of variance) and the mean size of crystals in order to optimize the filtering of the final product and then increase the production. The crystallization processes considered in this Thesis are the antisolvent crystallization processes used in particular when the solute is weakly temperature-sensitive and then a second solvent, properly called antisolvent, is added in the solution favoring the crystallization of the solute. In antisolvent crystallization processes it is important the consumption of the second solvent added, in particular, optimizing the feed-rate and coupling the process in synergy with cooling crystallization in order to improve the production and the quality of the desired product. The stochastic approach used in this Thesis is based on the Fokker Plank Equation (FPE), which has allowed finding an analytical solution of the model, with some assumptions, and obtaining an analytical model able to describe the evolution of the mean size of crystals and the variance of the CSD. This analytical solution has leaded to develop an analytical relationship between the evolution in time of the first two stochastic moments of the FPE, such as mean and variance, and the manipulated variables, such as antisolvent feed-rate and temperature, obtaining as a result a map showing the asymptotic moments obtainable within a certain range of operating conditions. This Thesis also analyzes the physical-chemical aspects of the antisolvent crystallization processes, including the temperature effects, finding a strong influence onto the nucleation and growth rate of crystals due by the hydrogen bond strength between solventantisolvent molecules despite of the molecular interaction in a solvated system.The physical-chemical consideration concerning the antisolvent crystallization processes allowed to better understand the influence of the second solvent added, consequently optimizing the choice for the proper antisolvent to use with a proper feed-rate and temperature profile, minimizing the energy consumptions, in order to obtain the desired product. The stochastic model and the physical-chemical considerations have been validated with experimental data performed in a laboratory scale crystallizer. The experimental samples have been analyzed using an optical microscope and then the images taken have been manually processed in order to obtain the experimental CSDs

From global to local scale: where is the best for conservation purpose?

AbstractDemographic analysis of plant populations represents an essential conservation tool allowing to identify the population trends both at global and at the local level. In this study, the population dynamics of Helianthemum caput-felis (Cistaceae) was investigated at the local level by monitoring six populations distributed in Sardinia, Balearic Islands and Ibero-Levantine coast (Alicante). Demographic data for each population were analysed by performing Integral Projection Models (IPMs). Our results showed that, although the local trend of the main basic demographic functions was similar, vital rates and demographic dynamics varied among populations indicating high variability. In fact, asymptotic growth rate in Spanish populations widely varied both between years and populations (some populations growth, decline or strongly decline), while Sardinian populations showed greater equilibrium or a slight increase. Also, the typical pattern of a long-lived species was not supported by the results at the local scale. These results indicated that different populations of the same species can present extremely different population dynamics and support the belief that, for conservation needs, local studies are more informative than global ones: the conservation status of H. caput-felis could notably vary at a small spatial scale and, accordingly, the conservation efforts must be planned at the population level and supported by local analysis

Epipactis tremolsii seed diversity in two close but extremely different populations: Just a case of intraspecific variability?

Analysis of the seed morphology is a widely used approach in ecological and taxonomic studies. In this context, intraspecific variability with respect to seed morphology (size, weight, and density) was assessed in two close Epipactis tremolsii Pau. populations sharing the same ecological conditions, except for the soil pollution distinguishing one of them. Larger and heavier seeds were found in plants growing on the heavy metal polluted site, while no differences in seed density were detected between seeds produced by plants growing on the contaminated and the control site. Moreover, seed coats and embryos varying together in their dimensions were described in the control population, while coats varying in their size independently from embryos were described in plants growing on the polluted site. Seeds from the two studied populations significantly differed in several parameters suggesting that intraspecific seed variability occurred in the case study

The IUCN Green Status of Species: A Call for Mediterranean Botanists to Contribute to This New Ambitious Effort

In the Mediterranean Basin, a critical focal point for the conservation of plant diversity, there has been a large increase in practical conservation actions for many plant species to prevent extinction and to improve their conservation status; quantifying the effectiveness of these initiatives in reversing species declines is urgently important. In 2021, the International Union for Conservation of Nature (IUCN) launched a new tool that allows the impact of conservation actions on plant species to be assessed. The Green Status of Species is a new set of metrics under the Red List of Threatened Species that assigns species to recovery categories, complementary to the classic extinction risk categories. Crucially, the Green Status of Species provides methods to evaluate the impact of past conservation, and the potential for future conservation impact, on species status and recovery in a standardized way. Considering the efforts made so far for the conservation of Mediterranean threatened plants, using the Green Status of Species would be highly useful to direct future conservation policies. We, therefore, encourage botanists and practitioners working on threatened plants in the Mediterranean area to use this new assessment tool to inform conservation and recovery programs

The post-transcriptional gene silencing machinery functions independently of DNA methylation to repress a LINE1-like retrotransposon in Neurospora crassa

Post-transcriptional gene silencing (PTGS) involving small interfering RNA (siRNA)-directed degradation of RNA transcripts and transcriptional silencing via DNA methylation have each been proposed as mechanisms of genome defence against invading nucleic acids, such as transposons and viruses. Furthermore, recent data from plants indicates that many transposons are silenced via a combination of the two mechanisms, and siRNAs can direct methylation of transposon sequences. We investigated the contribution of DNA methylation and the PTGS pathway to transposon control in the filamentous fungus Neurospora crassa. We found that repression of the LINE1-like transposon, Tad, requires the Argonaute protein QDE2 and Dicer, each of which are required for transgene-induced PTGS (quelling) in N.crassa. Interestingly, unlike quelling, the RNA-dependent RNA polymerase QDE1 and the RecQ DNA helicase QDE3 were not required for Tad control, suggesting the existence of specialized silencing pathways for diverse kinds of repetitive elements. In contrast, Tad elements were not significantly methylated and the DIM2 DNA methyltransferase, responsible for all known DNA methylation in Neurospora, had no effect on Tad control. Thus, an RNAi-related transposon silencing mechanism operates during the vegetative phase of N.crassa that is independent of DNA methylation, highlighting a major difference between this organism and other methylation-proficient species

Global and Regional IUCN Red List Assessments: 6

In this contribution, the conservation status assessment of four vascular plants according to IUCN categories and criteria are presented. It includes the assessment of Epipactis maricae (Croce, Bongiorni, De Vivo & Fori) Presser & S.Hertel at global level, and the regional assessment of Cerinthe retorta Sm. (Italy), Platanthera kuenkelei H.Baumann subsp. kuenkelei (Europe) and Typha elephantina Roxb. (Egypt)

Global and Regional IUCN Red List Assessments: 1

In this contribution, the conservation status assessment of six plant species according to IUCN categories and criteria are presented. It includes the assessment at global level of Linaria tonzigii Lona, Allium garganicum Brullo, Pavone, Salmeri & Terrasi, Ferula arrigonii Bocchieri, Orchis patens Desf. subsp. patens and Armeria saviana Selvi and the assessment at regional level (Italy) of Viola jordanii Hanry

Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 12

In this contribution, new data concerning bryophytes, fungi and lichens of the Italian flora are presented. It includes new records, confirmations or exclusions for the bryophyte genera Acaulon, Campylopus, En-tosthodon, Homomallium, Pseudohygrohypnum, and Thuidium, the fungal genera Entoloma, Cortinarius, Mycenella, Oxyporus, and Psathyrella and the lichen genera Anaptychia, Athallia, Baeomyces, Bagliettoa, Calicium, Nephroma, Pectenia, Phaeophyscia, Polyblastia, Protoparmeliopsis, Pyrenula, Ramalina, and San-guineodiscus