Chitosan-cellulose Composite Materials: Preparation, Characterization and Application for Removal of Microcystin

We developed a simple and one-step method to prepare biocompatible composites from cellulose (CEL) and chitosan (CS). [BMIm+Cl−], an ionic liquid (IL), was used as a green solvent to dissolve and prepare the [CEL + CS] composites. Since majority (\u3e88%) of IL used was recovered for reuse by distilling the aqueous washings of [CEL + CS], the method is recyclable. XRD, FTIR, NIR, 13C CP-MAS-NMR and SEM were used to monitor the dissolution and to characterize the composites. The composite was found to have combined advantages of their components: superior mechanical strength (from CEL) and excellent adsorption capability for microcystin-LR, a deadly toxin produced by cyanobacteria (from CS). Specifically, the mechanical strength of the composites increased with CEL loading; e.g., up to 5× increase in tensile strength was achieved by adding 80% of CEL into CS. Kinetic results of adsorption confirm that unique properties of CS remain intact in the composite, i.e., it is not only a very good adsorbent for microcystin but also is better than all other available adsorbents. For example, it can adsorb 4× times more microcystin than the best reported adsorbent. Importantly, the microcystin adsorbed can be quantitatively desorbed to enable the composite to be reused with similar adsorption efficiency

Systems biology of energetic and atomic costs in the yeast transcriptome, proteome, and metabolome

Proteins vary in their cost to the cell and natural selection may favour the use of proteins that are cheaper to produce. We develop a novel approach to estimate the amino acid biosynthetic cost based on genome-scale metabolic models, and directly investigate the effects of biosynthetic cost on transcriptomic, proteomic and metabolomic data in _Saccharomyces cerevisiae_. We find that our systems approach to formulating biosynthetic cost produces a novel measure that explains similar levels of variation in gene expression compared with previously reported cost measures. Regardless of the measure used, the cost of amino acid synthesis is weakly associated with transcript and protein levels, independent of codon usage bias. In contrast, energetic costs explain a large proportion of variation in levels of free amino acids. In the economy of the yeast cell, there appears to be no single currency to compute the cost of amino acid synthesis, and thus a systems approach is necessary to uncover the full effects of amino acid biosynthetic cost in complex biological systems that vary with cellular and environmental conditions

Non-coding RNAs in Saccharomyces cerevisiae: What is the function?

New sequencing technologies and high-resolution microarray analysis have revealed genome-wide pervasive transcription in many eukaryotes, generating a large number of RNAs of no coding capacity. The focus of current debate is whether many of these non-coding RNAs are functional, and if so, what their function is. In this review, we describe recent discoveries in the field of non-coding RNAs in the yeast Saccharomyces cerevisiae. Newly identified non-coding RNAs in this budding yeast, their functions in gene regulation and possible mechanisms of action are discussed

Il documento amministrativo informatico: un cammino per approssimazione

If the road towards a progressive dematerialization of the administrative document is marked, the legislator is not always proceeding in a coherent, clear or complete way. The line of reasoning needs to be focused on the administration of documental heritage, training and preservation rather than on technological issues, involving actively local administration and taking on responsibilities on decisions, also on the relationship between costs and benefits. The way is hard due to the lack of debate and practical directions, where the preservation should not be considered as a commanding confirmation, but as an occasion to face complex and critical issues.Se la strada verso la progressiva dematerializzazione del documento amministrativo è segnata, non sempre il legislatore procede in modo lineare né con chiarezza o completezza. Più che sugli aspetti meramente tecnologici si impone ormai un ragionamento complessivo sulle logiche di governo del patrimonio documentale, dalla formazione alla conservazione, con un attivo coinvolgimento delle amministrazioni e con assunzione di responsabilità in merito alle scelte, anche in termini di rapporto tra costi e benefici. Un cammino molto difficile, data la carenza di possibilità di confronto e di indicazioni operative, in cui il momento della conservazione non deve necessariamente essere vissuto come conferma senza appello, ma può rivelarsi piuttosto un’occasione per tornare ad affrontare temi tanto complessi quanto cruciali

La classificazione ibrida: il caso della documentazione del procedimento di acquisto gestita dentro e fuori dal Sistema Informativo Contratti Pubblici dell'Alto Adige

With reference to the acquisition procedures, the related documentation is created and managed mostly on the platform of the subcontracting institution, partly on the Alto Adige Public Sector Contracts information system. With a partial integration between this system and the platform made available by the Agenzia per i procedimenti e la vigilanza in materia di contratti pubblici di lavori, servizi e forniture, classification and filing information can be assigned to the documents coming from both platform, while the reunification of documents related to the same process is transferred to the preservation system as unique archive of the administration.Nel caso dei procedimenti di acquisto di cui sono titolari le Stazioni Appaltanti dell'Alto Adige che si avvalgono della piattaforma messa a disposizione dall'Agenzia per i procedimenti e la vigilanza in materia di contratti pubblici di lavori, servizi e forniture, la documentazione relativa è formata e gestita in parte sul sistema di gestione documentale della stazione appaltante, in parte (per la gara) sul Sistema Informativo Contratti Pubblici dell'Alto Adige. Con una parziale integrazione dei due sistemi, le informazioni di classificazione e fascicolazione sono attribuite anche ai documenti gestiti in piattaforma, mentre il ricongiungimento dei documenti relativi al medesimo procedimento è demandato al sistema di conservazione come archivio unico dell'amministrazione

Chimeric Protein Complexes in Hybrid Species Generate Novel Phenotypes

Hybridization between species is an important mechanism for the origin of novel lineages and adaptation to new environments. Increased allelic variation and modification of the transcriptional network are the two recognized forces currently deemed to be responsible for the phenotypic properties seen in hybrids. However, since the majority of the biological functions in a cell are carried out by protein complexes, inter-specific protein assemblies therefore represent another important source of natural variation upon which evolutionary forces can act. Here we studied the composition of six protein complexes in two different Saccharomyces “sensu stricto” hybrids, to understand whether chimeric interactions can be freely formed in the cell in spite of species-specific co-evolutionary forces, and whether the different types of complexes cause a change in hybrid fitness. The protein assemblies were isolated from the hybrids via affinity chromatography and identified via mass spectrometry. We found evidence of spontaneous chimericity for four of the six protein assemblies tested and we showed that different types of complexes can cause a variety of phenotypes in selected environments. In the case of TRP2/TRP3 complex, the effect of such chimeric formation resulted in the fitness advantage of the hybrid in an environment lacking tryptophan, while only one type of parental combination of the MBF complex allowed the hybrid to grow under respiratory conditions. These phenotypes were dependent on both genetic and environmental backgrounds. This study provides empirical evidence that chimeric protein complexes can freely assemble in cells and reveals a new mechanism to generate phenotypic novelty and plasticity in hybrids to complement the genomic innovation resulting from gene duplication. The ability to exchange orthologous members has also important implications for the adaptation and subsequent genome evolution of the hybrids in terms of pattern of gene loss

Sequencing and characterisation of rearrangements in three S. pastorianus strains reveals the presence of chimeric genes and gives evidence of breakpoint reuse

Gross chromosomal rearrangements have the potential to be evolutionarily advantageous to an adapting organism. The generation of a hybrid species increases opportunity for recombination by bringing together two homologous genomes. We sought to define the location of genomic rearrangements in three strains of Saccharomyces pastorianus, a natural lager-brewing yeast hybrid of Saccharomyces cerevisiae and Saccharomyces eubayanus, using whole genome shotgun sequencing. Each strain of S. pastorianus has lost species-specific portions of its genome and has undergone extensive recombination, producing chimeric chromosomes. We predicted 30 breakpoints that we confirmed at the single nucleotide level by designing species-specific primers that flank each breakpoint, and then sequencing the PCR product. These rearrangements are the result of recombination between areas of homology between the two subgenomes, rather than repetitive elements such as transposons or tRNAs. Interestingly, 28/30 S. cerevisiae- S. eubayanus recombination breakpoints are located within genic regions, generating chimeric genes. Furthermore we show evidence for the reuse of two breakpoints, located in HSP82 and KEM1, in strains of proposed independent origin

Gene Duplication and Environmental Adaptation within Yeast Populations

PublishedPopulation-level differences in the number of copies of genes resulting from gene duplication and loss have recently been recognized as an important source of variation in eukaryotes. However, except for a small number of cases, the phenotypic effects of this variation are unknown. Data from the Saccharomyces Genome Resequencing Project permit the study of duplication in genome sequences from a set of individuals within the same population. These sequences can be correlated with available information on the environments from which these yeast strains were isolated. We find that yeast show an abundance of duplicate genes that are lineage specific, leading to a large degree of variation in gene content between individual strains. There is a detectable bias for specific functions, indicating that selection is acting to preferentially retain certain duplicates. Most strikingly, we find that sets of over- and underrepresented duplicates correlate with the environment from which they were isolated. Together, these observations indicate that gene duplication can give rise to substantial phenotypic differences within populations that in turn can offer a shortcut to evolutionary adaptation.This work was funded by BBSRC grant BB/F007620/1

Evolutionary Systems Biology of Amino Acid Biosynthetic Cost in Yeast

Every protein has a biosynthetic cost to the cell based on the synthesis of its constituent amino acids. In order to optimise growth and reproduction, natural selection is expected, where possible, to favour the use of proteins whose constituents are cheaper to produce, as reduced biosynthetic cost may confer a fitness advantage to the organism. Quantifying the cost of amino acid biosynthesis presents challenges, since energetic requirements may change across different cellular and environmental conditions. We developed a systems biology approach to estimate the cost of amino acid synthesis based on genome-scale metabolic models and investigated the effects of the cost of amino acid synthesis on Saccharomyces cerevisiae gene expression and protein evolution. First, we used our two new and six previously reported measures of amino acid cost in conjunction with codon usage bias, tRNA gene number and atomic composition to identify which of these factors best predict transcript and protein levels. Second, we compared amino acid cost with rates of amino acid substitution across four species in the genus Saccharomyces. Regardless of which cost measure is used, amino acid biosynthetic cost is weakly associated with transcript and protein levels. In contrast, we find that biosynthetic cost and amino acid substitution rates show a negative correlation, but for only a subset of cost measures. In the economy of the yeast cell, we find that the cost of amino acid synthesis plays a limited role in shaping transcript and protein expression levels compared to that of translational optimisation. Biosynthetic cost does, however, appear to affect rates of amino acid evolution in Saccharomyces, suggesting that expensive amino acids may only be used when they have specific structural or functional roles in protein sequences. However, as there appears to be no single currency to compute the cost of amino acid synthesis across all cellular and environmental conditions, we conclude that a systems approach is necessary to unravel the full effects of amino acid biosynthetic cost in complex biological systems