THE ACQUISITION OF RUSSIAN GRAMMAR CASES BY BRAZILIAN STUDENTS

The analysis of Russian discourse in the proficiency levels B1 and B2 points out to Brazilian students' assimilation problems regarding the grammar cases. Such problems are interpreted based on the structural comparison between the verb-object relations in Portuguese and Russian: - the verb and object may be connected directly or through a preposition; - the meaning is also intermediated by the grammar cases. To establish interlinguistic equivalents, they are compared structures with similar meaning in the native language compared to the learnt one. The research aims to understand through an empirical approach to Brazilian students' difficulties when learning grammar cases regarding their native language interference. The authors recorded interviews with Brazilian students in the referred proficiency levels, which were considered under the typological comparison; a questionary answered by the same students was then implemented to confirm such difficulties. The results indicate the structural divergence and consequent difficulty of Brazilian students to acquire the Dative and the Instrumental cases when a preposition does not intermediate the verb-object relation.

Purification of functional Plasmodium falciparum tubulin allows for the identification of parasite-specific microtubule inhibitors

Cytoskeletal proteins are essential for parasite proliferation, growth, and transmission, and therefore represent promising drug targets. While αβ-tubulin, the molecular building block of microtubules, is an established drug target in a variety of cancers, we still lack substantial knowledge of the biochemistry of parasite tubulins, which would allow us to exploit the structural divergence between parasite and human tubulins. Indeed, mechanistic insights have been limited by the lack of purified, functional parasite tubulin. In this study, we isolated Plasmodium falciparum tubulin that is assembly-competent and shows specific microtubule dynamics in vitro. We further present mechanistic evidence that two compounds selectively interact with parasite over host microtubules and inhibit Plasmodium microtubule polymerization at substoichiometric compound concentrations. The ability of compounds to selectively disrupt protozoan microtubule growth without affecting human microtubules provides the exciting possibility for the targeted development of novel antimalarials.

Structural Identification between Phthalazine-1,4-Diones and N-Aminophthalimides via Vilsmeier Reaction: Nitrogen Cyclization and Tautomerization Study

N-aminophthalimides and phthalazine 1,4-diones were synthesized from isobenzofuran-1,3-dione, isoindoline-1,3-dione, furo [3,4-b] pyrazine-5,7-dione, or 1H-pyrrolo [3,4-c] pyridine-1,3-dione with monohydrate hydrazine to carry out the 5-exo or 6-endo nitrogen cyclization under the different reaction conditions. Based on the control experimental results, 6-endo thermodynamic hydrohydrazination and kinetical 5-exo cyclization reactions were individually selective formation. Subsequently, Vilsmeier amidination derivatization was successfully developed to probe the structural divergence between N-aminophthalimide 2 and phthalazine 1,4-dione 3. On the other hand, the best tautomerization of N-aminophthalimide to diazinone was also determined under acetic acid mediated solution.

Comparison of 15 dinoflagellate genomes reveals extensive sequence and structural divergence in family Symbiodiniaceae and genus Symbiodinium

Background Dinoflagellates in the family Symbiodiniaceae are important photosynthetic symbionts in cnidarians (such as corals) and other coral reef organisms. Breakdown of the coral-dinoflagellate symbiosis due to environmental stress (i.e. coral bleaching) can lead to coral death and the potential collapse of reef ecosystems. However, evolution of Symbiodiniaceae genomes, and its implications for the coral, is little understood. Genome sequences of Symbiodiniaceae remain scarce due in part to their large genome sizes (1–5 Gbp) and idiosyncratic genome features. Results Here, we present de novo genome assemblies of seven members of the genus Symbiodinium, of which two are free-living, one is an opportunistic symbiont, and the remainder are mutualistic symbionts. Integrating other available data, we compare 15 dinoflagellate genomes revealing high sequence and structural divergence. Divergence among some Symbiodinium isolates is comparable to that among distinct genera of Symbiodiniaceae. We also recovered hundreds of gene families specific to each lineage, many of which encode unknown functions. An in-depth comparison between the genomes of the symbiotic Symbiodinium tridacnidorum (isolated from a coral) and the free-living Symbiodinium natans reveals a greater prevalence of transposable elements, genetic duplication, structural rearrangements, and pseudogenisation in the symbiotic species. Conclusions Our results underscore the potential impact of lifestyle on lineage-specific gene-function innovation, genome divergence, and the diversification of Symbiodinium and Symbiodiniaceae. The divergent features we report, and their putative causes, may also apply to other microbial eukaryotes that have undergone symbiotic phases in their evolutionary history.

Influence of Disease-Causing Mutations on Protein Structural Networks

The interactions between residues in a protein tertiary structure can be studied effectively using the approach of protein structure network (PSN). A PSN is a node-edge representation of the structure with nodes representing residues and interactions between residues represented by edges. In this study, we have employed weighted PSNs to understand the influence of disease-causing mutations on proteins of known 3D structures. We have used manually curated information on disease mutations from UniProtKB/Swiss-Prot and their corresponding protein structures of wildtype and disease variant from the protein data bank. The PSNs of the wildtype and disease-causing mutant are compared to analyse variation of global and local dissimilarity in the overall network and at specific sites. We study how a mutation at a given site can affect the structural network at a distant site which may be involved in the function of the protein. We have discussed specific examples of the disease cases where the protein structure undergoes limited structural divergence in their backbone but have large dissimilarity in their all atom networks and vice versa, wherein large conformational alterations are observed while retaining overall network. We analyse the effect of variation of network parameters that characterize alteration of function or stability.

Investment, Saving and Stagnation from a Keynesian Perspective

It can also be shown from a Keynesian perspective that planned investment and saving are diverging in the twenty-first century and that there is a risk of sustained (secular) underemployment unless appropriate countermeasures are taken by the state. In this chapter, we look at the arguments that Keynesian authors have used, in both older and more recent writings, to demonstrate the possibility of secular stagnation and at the possibilities they considered for overcoming tendencies toward stagnation. We make clear that, despite general differences in the theoretical framework and some differences in detail, there are a number of parallels between the Keynesian view and the new capital-theoretical conception presented in this book. This applies both for the causes of the structural divergence between planned private saving and private investment and for its consequences.

Forced Structural Convergence in the Eurozone

The euro crisis has been a consequence of the structural divergence between the export-oriented growth models of Northern political economies and the domestic-demand oriented growth models of Southern political economies. In response to the crisis, the Monetary Union has established a regime of compulsory structural convergence on the Northern model that has asymmetrically imposed huge economic and social costs on its Southern member states. In economic terms, enforced structural transformation may perhaps work, but its distributional asymmetry that cannot be democratically legitimated undermines the regime’s political sustainability.

Asymmetric dynamic coupling promotes alternative evolutionary pathways in an enzyme dimer

The importance of dynamic factors in enzyme evolution is gaining recognition. Here we study how the evolution of a new enzymatic activity exploits conformational tinkering and demonstrate that conversion of a dimeric phosphotriesterase to an arylesterase in Pseudomonas diminuta is accompanied by structural divergence between the two subunits. Deviations in loop conformations increase with promiscuity, leading to functionally distinct states, while they decrease during specialisation for the new function. We show that opposite loop movements in the two subunits are due to a dynamic coupling with the dimer interface, the importance of which is also corroborated by the co-evolution of the loop and interface residues. These results illuminate how protein dynamics promotes conformational heterogeneity in a dimeric enzyme, leading to alternative evolutionary pathways for the emergence of a new function.

Independent accretion of TIM22 complex subunits in the animal and fungal lineages

Background: The mitochondrial protein import complexes arose early in eukaryogenesis. Most of the components of the protein import pathways predate the last eukaryotic common ancestor. For example, the carrier-insertase TIM22 complex comprises the widely conserved Tim22 channel core. However, the auxiliary components of fungal and animal TIM22 complexes are exceptions to this ancient conservation. Methods: Using comparative genomics and phylogenetic approaches, we identified precisely when each TIM22 accretion occurred. Results: In animals, we demonstrate that Tim29 and Tim10b arose early in the holozoan lineage. Tim29 predates the metazoan lineage being present in the animal sister lineages, choanoflagellate and filastereans, whereas the erroneously named Tim10b arose from a duplication of Tim9 at the base of metazoans. In fungi, we show that Tim54 has representatives present in every holomycotan lineage including microsporidians and fonticulids, whereas Tim18 and Tim12 appeared much later in fungal evolution. Specifically, Tim18 and Tim12 arose from duplications of Sdh3 and Tim10, respectively, early in the Saccharomycotina. Surprisingly, we show that Tim54 is distantly related to AGK suggesting that AGK and Tim54 are extremely divergent orthologues and the origin of AGK/Tim54 interaction with Tim22 predates the divergence of animals and fungi. Conclusions: We argue that the evolutionary history of the TIM22 complex is best understood as the neutral structural divergence of an otherwise strongly functionally conserved protein complex. This view suggests that many of the differences in structure/subunit composition of multi-protein complexes are non-adaptive. Instead, most of the phylogenetic variation of functionally conserved molecular machines, which have been under stable selective pressures for vast phylogenetic spans, such as the TIM22 complex, is most likely the outcome of the interplay of random genetic drift and mutation pressure.