Conformationally Constrained Sialyl Analogues as New Potential Binders of h-CD22.

Here, two conformationally constrained sialyl analogues were synthesized and characterized in their interaction with the inhibitory Siglec, human CD22 (h-CD22). An orthogonal approach, including biophysical assays (SPR and fluorescence), ligand-based NMR techniques, and molecular modelling, was employed to disentangle the interaction mechanisms at a molecular level. The results showed that the Sialyl-TnThr antigen analogue represents a promising scaffold for the design of novel h-CD22 inhibitors. Our findings also suggest that the introduction of a biphenyl moiety at position 9 of the sialic acid hampers canonical accommodation of the ligand in the protein binding pocket, even though the affinity with respect to the natural ligand is increased. Our results address the search for novel modifications of the Neu5Ac-α(2-6)-Gal epitope, outline new insights for the design and synthesis of high-affinity h-CD22 ligands, and offer novel prospects for therapeutic intervention to prevent autoimmune diseases and B-cell malignancies.

Characterisation of the Dynamic Interactions between Complex N-Glycans and Human CD22.

CD22 (Siglec-2) is a B-cell surface inhibitory protein capable of selectively recognising sialylated glycans, thus dampening autoimmune responses against self-antigens. Here we have characterised the dynamic recognition of complex-type N-glycans by human CD22 by means of orthogonal approaches including NMR spectroscopy, computational methods and biophysical assays. We provide new molecular insights into the binding mode of sialoglycans in complex with h-CD22, highlighting the role of the sialic acid galactose moieties in the recognition process, elucidating the conformational behaviour of complex-type N-glycans bound to Siglec-2 and dissecting the formation of CD22 homo-oligomers on the B-cell surface. Our results could enable the development of additional therapeutics capable of modulating the activity of h-CD22 in autoimmune diseases and malignancies derived from B-cells.

Human Macrophage Galactose-Type Lectin (MGL) Recognizes the Outer Core of Escherichia coli Lipooligosaccharide.

Carbohydrate-lectin interactions intervene in and mediate most biological processes, including a crucial modulation of immune responses to pathogens. Despite growing interest in investigating the association between host receptor lectins and exogenous glycan ligands, the molecular mechanisms underlying bacterial recognition by human lectins are still not fully understood. Herein, a novel molecular interaction between the human macrophage galactose-type lectin (MGL) and the lipooligosaccharide (LOS) of Escherichia coli strain R1 is described. Saturation transfer difference NMR spectroscopy analysis, supported by computational studies, demonstrated that MGL bound to the purified deacylated LOSR1 mainly through recognition of its outer core and established crucial interactions with the terminal Galα(1,2)Gal epitope. These results assess the ability of MGL to recognise glycan moieties exposed on Gram-negative bacterial surfaces.

Solving the structural puzzle of bacterial glycome.

The analysis of the bacterial glycome (glycomics) is among the complex 'omics' analysis owing to the inherent difficulties in structural and functional characterization of glycans. The complexity and variability of bacterial glycans, spanning from simple carbohydrates to complex glycolipids, glycopeptides and glycoproteins, make their study a challenging research area. The last two decades have witnessed tremendous advances and development of highly sophisticated methods, in combination with optimized protocols and hyphenate techniques for the understanding of structure, conformations, dynamics and organization of microbial glycans. We here present an overview of the novel approaches that have massively improved our understanding of the carbohydrate-based world of bacteria.

Understanding the Antibacterial Resistance: Computational Explorations in Bacterial Membranes.

Antimicrobial resistance (AMR) represents a major threat to global public health in the 21st century, dramatically increasing the pandemic expectations in the coming years. The ongoing need to develop new antimicrobial treatments that are effective against multi-drug-resistant pathogens has led the research community to investigate innovative strategies to tackle AMR. The bacterial cell envelope has been identified as one of the key molecular players responsible for antibiotic resistance, attracting considerable interest as a potential target for novel antimicrobials effective against AMR, to be used alone or in combination with other drugs. However, the multicomponent complexity of bacterial membranes provides a heterogeneous morphology, which is typically difficult to study at the molecular level by experimental techniques, in spite of the significant development of fast and efficient experimental protocols. In recent years, computational modeling, in particular, molecular dynamics simulations, has proven to be an effective tool to reveal key aspects in the architecture and membrane organization of bacterial cell walls. Here, after a general overview about bacterial membranes, AMR mechanisms, and experimental approaches to study AMR, we review the state-of-the-art computational approaches to investigate bacterial AMR envelopes, including their limitations and challenges ahead. Representative examples illustrate how these techniques improve our understanding of bacterial membrane resistance mechanisms, hopefully leading to the development of novel antimicrobial drugs escaping from bacterial resistance strategies.

Characterization of Natural and Synthetic Sialoglycans Targeting the Hemagglutinin-Neuraminidase of Mumps Virus.

The inhibition of surface viral glycoproteins offers great potential to hamper the attachment of viruses to the host cells surface and the spreading of viral infection. Mumps virus (MuV) is the etiological agent of the mumps infectious disease and causes a wide spectrum of mild to severe symptoms due to the inflammation of the salivary glands. Here we focus our attention on the hemagglutinin-neuraminidase (HN) isolated from MuV SBL-1 strain. We describe the molecular features of host sialoglycans recognition by HN protein by means of NMR, fluorescence assays and computational studies. Furthermore, we also describe the synthesis of a N-acetylneuraminic acid-derived thiotrisaccharide targeting the viral protein, and the corresponding 3D-complex. Our results provide the basis to improve the design and synthesis of potent viral hemagglutinin-neuraminidase inhibitors.

Molecular recognition of sialoglycans by streptococcal Siglec-like adhesins: toward the shape of specific inhibitors.

Streptococcus gordonii and Streptococcus sanguinis, commensal bacteria present in the oral cavity of healthy individuals, upon entry into the bloodstream can become pathogenic, causing infective endocarditis (IE). Sialic acid-binding serine-rich repeat adhesins on the microbial surface represent an important factor of successful infection to cause IE. They contain Siglec-like binding regions (SLBRs) that variously recognize different repertoires of O-glycans, with some strains displaying high selectivity and others broader specificity. We here dissect at an atomic level the mechanism of interaction of SLBR-B and SLBR-H from S. gordonii with a multivarious approach that combines NMR spectroscopy and computational and biophysical studies. The binding pockets of both SLBRs are broad enough to accommodate extensive interactions with sialoglycans although with key differences related to strain specificity. Furthermore, and significantly, the pattern of interactions established by the SLBRs are mechanistically very different from those reported for mammalian Siglecs despite them having a similar fold. Thus, our detailed description of the binding modes of streptococcal Siglec-like adhesins sparks the development of tailored synthetic inhibitors and therapeutics specific for Streptococcal adhesins to counteract IE, without impairing the interplay between Siglecs and glycans.

Behavior of glycolylated sialoglycans in the binding pockets of murine and human CD22.

Siglecs (sialic acid binding immunoglobulin (Ig)-like lectins) constitute a group of 15 human and 9 murine cell-surface transmembrane receptors belonging to the I-type lectin family, mostly expressed on innate immune cells and characterized by broadly similar structural features. Here, the prominent inhibitory CD22 (Siglec-2), well known in maintaining tolerance and preventing autoimmune responses on B cells, is studied in its human and murine forms in complex with sialoglycans. In detail, the role of the N-glycolyl neuraminic acid (Neu5Gc) moiety in the interaction with both orthologues was explored. The analysis of the binding mode was carried out by the combination of NMR spectroscopy, computational approaches, and CORCEMA-ST calculations. Our findings provide a first model of Neu5Gc recognition by h-CD22 and show a comparable molecular recognition profile by h- and m-CD22. These data open the way to innovative diagnostic and/or therapeutic methodologies to be used in the modulation of the immune responses.

Thermotolerant and Thermophilic Mycobiota in Different Steps of Compost Maturation.

Composting is a complex process in which various micro-organisms, mainly fungi and bacteria, are involved. The process depends on a large number of factors (biological, chemical, and physical) among which microbial populations play a fundamental role. The high temperatures that occur during the composting process indicate the presence of thermotolerant and thermophilic micro-organisms that are key for the optimization of the process. However, the same micro-organisms can be harmful (allergenic, pathogenic) for workers that handle large quantities of material in the plant, and for end users, for example, in the indoor environment (e.g., pots in houses and offices). Accurate knowledge of thermotolerant and thermophilic organisms present during the composting stages is required to find key organisms to improve the process and estimate potential health risks. The objective of the present work was to study thermotolerant and thermophilic mycobiota at different time points of compost maturation. Fungi were isolated at four temperatures (25, 37, 45, and 50 °C) from compost samples collected at five different steps during a 21-day compost-maturation period in an active composting plant in Liguria (northwestern Italy). The samples were subsequently plated on three different media. Our results showed a high presence of fungi with an order of magnitude ranging from 1 × 104 to 3 × 105 colony-forming units (CFU) g-1. The isolated strains, identified by means of specific molecular tools (ITS, beta-tubulin, calmodulin, elongation factor 1-alpha, and LSU sequencing), belonged to 45 different species. Several thermophilic species belonging to genera Thermoascus and Thermomyces were detected, which could be key during composting. Moreover, the presence of several potentially harmful fungal species, such as Aspergillus fumigatus, A. terreus, and Scedosporium apiospermum, were found during the whole process, including the final product. Results highlighted the importance of surveying the mycobiota involved in the composting process in order to: (i) find solutions to improve efficiency and (ii) reduce health risks.

Structural basis for Glycan-receptor binding by mumps virus hemagglutinin-neuraminidase.

Mumps virus is one of the main cause of respiratory illnesses in humans, especially children. Among the viral surface glycoproteins, the hemagglutinin - neuraminidase, MuV-HN, plays key roles in virus entry into host cells and infectivity, thus representing an ideal target for the design of novel inhibitors. Here we report the detailed analysis of the molecular recognition of host cell surface sialylated glycans by the viral glycoprotein MuV-HN. By a combined use of NMR, docking, molecular modelling and CORCEMA-ST, the structural features of sialoglycans/MuV-HN complexes were revealed. Evidence for a different enzyme activity toward longer and complex substrates compared to unbranched ligands was also examined by an accurate NMR kinetic analysis. Our results provide the basis for the structure-based design of effective drugs against mumps-induced diseases.

Unveiling Molecular Recognition of Sialoglycans by Human Siglec-10.

Siglec-10 is an inhibitory I-type lectin selectively recognizing sialoglycans exposed on cell surfaces, involved in several patho-physiological processes. The key role Siglec-10 plays in the regulation of immune cell functions has made it a potential target for the development of immunotherapeutics against a broad range of diseases. However, the crystal structure of the protein has not been resolved for the time being and the atomic description of Siglec-10 interactions with complex glycans has not been previously unraveled. We present here the first insights of the molecular mechanisms regulating the interaction between Siglec-10 and naturally occurring sialoglycans. We used combined spectroscopic, computational and biophysical approaches to dissect glycans' epitope mapping and conformation upon binding in order to afford a description of the 3D complexes. Our outcomes provide a structural perspective for the rational design and development of high-affinity ligands to control the receptor functionality.

O papel das crianças e dos jovens na constituição das identidades profissionais de educadores/professores/formadores de professores / The role of children and young people in the constitution of professional identities of educators/teachers/teacher educators

As transformações da sociedade têm afetado, direta e indiretamente, a escola, atribuindo-lhe um caráter complexo e, por consequência, promotor de reconfigurações identitárias. Este artigo propõe-se a analisar o papel das crianças e jovens na re(constituição) das identidades profissionais de educadores, professores e formadores de professores. Foram utilizados dados e análises de cinco investigações realizadas pelas autoras. A noção de identidade profissional (Dubar, 1997; Lopes, 2007), o conceito de socialização (Berger & Luckmann, 1996) e o conceito de saberes profissionais (Tardif, 2002) fundamentaram o estudo. Os resultados indicam que: as crianças e jovens são o outro significativo central na (re)constituição identitária; as relações de proximidade, afeto e reconhecimento do saber são a base da (re)construção das identidades; os saberes profissionais são (re)configurados a partir das relações estabelecidas entre educadores/professores/formadores de professores e crianças/alunos/estudantes, devolvendo sentido maior ou menor, consoante o nível de ensino.(AU)

The changes in society have affected, directly and indirectly, the school, giving it a complex character, promoting identity reconfigurations. This article aims to analyze the role of children and youth in re (constitution) of educators, teachers and teacher educator' professional identities. We used data from five studies that were conducted by the authors. The theoretical background is the notion of professional identity (Dubar, 1997; Lopes, 2007), the concept of socialization (Berger and Luckmann,1996) and the concept of professional knowledge (Tardif, 2002). The results indicate that children and youngsters are the significant other of centrality in the re (constitution) of identity; the proximity relations, affection and acknowledgement of knowledge are a central aspect of the (re)construction of identity; professional knowledge is (re)configured from the relationships established among educators/teachers/ teachers' educators and children/students, being more or less significant according to the level of teaching.(AU)

Professores sabem o que é bullying?: um tema para a formação docente / Do teachers know what is bullying?: a teacher training issue / ¿Profesores saben qué es bullying?: un tema para la formación docente

A pesquisa, de cunho qualitativo, abordou o bullying na formação de professores, tendo como objetivo refletir a respeito das concepções sobre o fenômeno e do que eles consideram serem formas eficazes de intervenção diante dos casos ocorridos em escolas públicas do ensino fundamental, e ainda sobre as demandas para a formação docente. Foram entrevistados seis professores em uma escola municipal do Recife e seis licenciandos da Universidade Federal de Pernambuco. Como resultado, identificamos que os participantes tiveram dificuldade em definir o bullying e de caracterizar sua abrangência na escola. Consideram o tema relevante, embora apontem que está pouco presente nos cursos de formação. Quanto à intervenção, propõem o diálogo e o envolvimento de pais e de autoridades públicas. Conclui-se que o bullying é reconhecido como problema concernente às escolas e aos professores, porém não se constitui num tópico de estudo sistemático na formação de licenciados.

This qualitative research focused on how teacher education approaches bullying and aimed to identify what teachers think about this phenomena, how they interfere when it happens in elementary public schools and what do they expect to study about this theme during teacher training. Six trainees and six public school teachers were interviewed in Recife, Brazil. As results, we identified that the research participants found it difficult to characterize how bullying is present in schools. They consider that this is a relevant issue, even thou they recognize that their teacher education did not address this problem. When questioned about how to interfere, they proposed that dialogue is the best resource and that parents and other authorities must be involved. The study leads to conclude that bullying is recognized as a problem that concerns schools and teachers, but it has not been studied regularly in formal education or in teacher training.

La investigación cualitativa enfocó el tema bullying en la formación de profesores y tuvo como objetivo reflexionar sobre las concepciones sobre el fenómeno, sobre lo que consideran medios eficaces de intervención ante casos ocurridos en escuelas públicas de enseñanza fundamental, así como sobre las demandas para la formación docente. Se entrevistó seis profesores en una escuela municipal de Recife y seis estudiantes de licenciatura en la Universidad Federal de Pernambuco. Los resultados identifican que los participantes tuvieron dificultades de definir bullying y de caracterizar su presencia y alcance en la escuela. Además, consideran el tema relevante, a pesar de indicar que está poco presente en los cursos de formación. En cuanto a formas de intervención proponen el diálogo y el envolvimiento de los padres de familia y otras autoridades públicas. Se concluye que el bullying es reconocido como problema que concierne a escuelas y profesores, sin embargo no se constituye un tópico de estudio sistemático en la formación de licenciados.

A memória congelada do imigrante: a solidariedade intergeracional dos japoneses e dos nikkeis no Brasil e no Japão atual / The frozen memory of the immigrant: the intergenerational solidarity of the Japanese and of the Nikkeis in Brazil and the actual Japan

O artigo discute a solidariedade intergeracional dos migrantes japoneses e seus descendentes no Brasil, incluindo-se os nikkeis que retornaram para o Japão. Discute também a atual solidariedade existente entre os japoneses residentes no Japão, que não migraram para o Brasil.

Práticas de leitura de professoras e narrativas autobiográficas / Teacher´s reading practices and life histories

Neste texto, é discutida a concepção de prática de leitura, aproximando-a da perspectiva sociocultural em Psicologia para em seguida situar a autobiografia de professores como leitores enquanto tema emergente na pesquisa educacional. Em seguida, foram apresentados alguns dos resultados de uma pesquisa qualitativa realizada no Recife, Pernambuco, envolvendo 16 professoras que atuam na Educação Infantil e nas séries iniciais do Ensino Fundamental em escolas públicas. O objetivo desta investigação foi identificar como aparecem, nos relatos dessas professoras, suas características como leitoras, considerando que a história de vida informa suas concepções sobre leitura e o modo como atuam no ensino deste componente curricular