Evolution of MIR168 paralogs in Brassicaceae

<p>Abstract</p> <p>Background</p> <p>In plants, expression of ARGONAUTE1 (AGO1), the catalytic subunit of the RNA-Induced Silencing Complex responsible for post-transcriptional gene silencing, is controlled through a feedback loop involving the miR168 microRNA. This complex auto-regulatory loop, composed of miR168-guided AGO1-catalyzed cleavage of <it>AGO1 </it>mRNA and AGO1-mediated stabilization of miR168, was shown to ensure the maintenance of AGO1 homeostasis that is pivotal for the correct functioning of the miRNA pathway.</p> <p>Results</p> <p>We applied different approaches to studying the genomic organization and the structural and functional evolution of <it>MIR168 </it>homologs in Brassicaeae. A whole genome comparison of Arabidopsis and poplar, phylogenetic footprinting and phylogenetic reconstruction were used to date the duplication events originating <it>MIR168 </it>homologs in these genomes. While orthology was lacking between Arabidopsis and poplar <it>MIR168 </it>genes, we successfully isolated orthologs of both loci present in Arabidopsis (<it>MIR168a </it>and <it>MIR168b</it>) from all the Brassicaceae species analyzed, including the basal species <it>Aethionema grandiflora</it>, thus indicating that (1) independent duplication events took place in Arabidopsis and poplar lineages and (2) the origin of <it>MIR168 </it>paralogs predates both the Brassicaceae radiation and the Arabidopsis alpha polyploidization. Different phylogenetic footprints, corresponding to known functionally relevant regions (transcription starting site and double-stranded structures responsible for microRNA biogenesis and function) or for which functions could be proposed, were found to be highly conserved among <it>MIR168 </it>homologs. Comparative predictions of the identified microRNAs also indicate extreme conservation of secondary structure and thermodynamic stability.</p> <p>Conclusion</p> <p>We used a comparative phylogenetic footprinting approach to identify the structural and functional constraints that shaped <it>MIR168 </it>evolution in Brassicaceae. Although their duplication happened at least 40 million years ago, we found evidence that both <it>MIR168 </it>paralogs have been maintained throughout the evolution of Brassicaceae, most likely functionally as indicated by the extremely high conservation of functionally relevant regions, predicted secondary structure and thermodynamic profile. Interestingly, the expression patterns observed in Arabidopsis indicate that <it>MIR168b </it>underwent partial subfunctionalization as determined by the experimental characterization of its expression pattern provided in this study. We found further evolutionary evidence that pre-miR168 lower stem (the RNA-duplex structure adjacent to the miR-miR* stem) is significantly longer than animal lower stems and probably plays a relevant role in multi-step miR168 biogenesis.</p

Brain doping: stimulants use and misuse among a sample of Italian college students

Introduction. The non-medical use of prescription stimulants (NMUPS) has become of great interest for its diffusion among university students, engaged in NUMPS to cope with the increasing load of academic stress. This consumption has been more throughoutly investigated in the U.S. due to its increasing trend. However, NMUPS has been reported also in Europe. The aim of this cross-sectional study was to examine stimulants misuse in an Italian area, identifying possible developments of the phenomenon in Italy.Methods.To evaluate academic and extra-academic NMUPS (Methylphenidate and Amphetamines), an anonymous multiple-choice questionnaire was administrated to a representative sample of Bachelor’s and Master’s degrees students attending a University of North of Italy.Data elaboration and Confidence Interval 95% were performed with Excel software 2013, while Fisher's exact tests with GraphPad INSTAT software.Results. Data from 899 correctly compiled questionnaires were analyzed in this study.11.3% of students reported NMUPS with an apparent greater use by students aged 18-22 years (73.5%) and without any gender predominance (p: n.s.). 57,8% of students used stimulants at most five times in six months, while the most frequent academic and extra-academic motives for use were respectively to improve concentration while studying (51.0%) and sports performance (25.5%). NMUPS was higher among working students than non-working ones (p &lt;0.05), suggesting a stimulants use to cope with stress by the first ones.Conclusion. These data suggest that NMUPS is quite relevant in the North of Italy, requiring preventive and monitoring measures, besides future analysis with a longitudinal multicenter study

A non-canonical RNA silencing pathway promotes mRNA degradation in basal fungi

The increasing knowledge on the functional relevance of endogenous small RNAs (esRNAs) as riboregulators has stimulated the identification and characterization of these molecules in numerous eukaryotes. In the basal fungus Mucor circinelloides, an emerging opportunistic human pathogen, esRNAs that regulate the expression of many protein coding genes have been described. These esRNAs share common machinery for their biogenesis consisting of an RNase III endonuclease Dicer, a single Argonaute protein and two RNA-dependent RNA polymerases. We show in this study that, besides participating in this canonical dicer-dependent RNA interference (RNAi) pathway, the rdrp genes are involved in a novel dicer-independent degradation process of endogenous mRNAs. The analysis of esRNAs accumulated in wild type and silencing mutants demonstrates that this new rdrp-dependent dicer-independent regulatory pathway, which does not produce sRNA molecules of discrete sizes, controls the expression of target genes promoting the specific degradation of mRNAs by a previously unknown RNase. This pathway mainly regulates conserved genes involved in metabolism and cellular processes and signaling, such as those required for heme biosynthesis, and controls responses to specific environmental signals. Searching the Mucor genome for candidate RNases to participate in this pathway, and functional analysis of the corresponding knockout mutants, identified a new protein, R3B2. This RNase III-like protein presents unique domain architecture, it is specifically found in basal fungi and, besides its relevant role in the rdrp-dependent dicer-independent pathway, it is also involved in the canonical dicer-dependent RNAi pathway, highlighting its crucial role in the biogenesis and function of regulatory esRNAs. The involvement of RdRPs in RNA degradation could represent the first evolutionary step towards the development of an RNAi mechanism and constitutes a genetic link between mRNA degradation and post-transcriptional gene silencing

Role of FRIGIDA in repressing the floral transition

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Is old age a risk factor for psychiatric referral in the general hospital

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Elderly inpatients from the perspective of modena consultation-liaison psychiatry service

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Evaluation of the Upper Arch Morphological Changes after Two Different Protocols of Expansion in Early Mixed Dentition: Rapid Maxillary Expansion and Invisalign&reg; First System

Background: The objective of this retrospective study was to analyze the morphological changes of the upper arch after two protocols of expansion, the Invisalign&reg; First system and rapid maxillary expansion (RME), in mixed dentition by means of geometric morphometric analysis (GMM). Methods: Digital dental casts of 32 children treated either with RME (RME group: 17 subjects; mean age 8.1 years) or the First system (First group: subjects; mean age 8.4 years) were collected. For both the RG and FG, pre-(T1) and post-treatment(T2) digital models were created. A total of 14 landmarks were digitized and GMM was applied. Procrustes analysis and principal component analysis (PCA) were performed. Results: The PC1 resulting from the T2&ndash;T1 comparison in the RG g showed statistically significant morphological changes in the posterior region of the upper arch shape, without significant variations in the anterior region. The comparison of the T2&ndash;T1 changes in the FG showed an increase in the transverse dimension at the level of the canine and the first deciduous molar widths, with morphological variation in the anterior region due to frontal teeth alignment. Conclusions: The First system induced shape modifications of the upper arch during expansion in contrast to RME. The FG presented an improvement in the maxillary arch shape, while the RG maintained the initial triangular shape