Proteomics Analysis of Extracellular Matrix Remodeling During Zebrafish Heart Regeneration.

Adult zebrafish, in contrast to mammals, are able to regenerate their hearts in response to injury or experimental amputation. Our understanding of the cellular and molecular bases that underlie this process, although fragmentary, has increased significantly over the last years. However, the role of the extracellular matrix (ECM) during zebrafish heart regeneration has been comparatively rarely explored. Here, we set out to characterize the ECM protein composition in adult zebrafish hearts, and whether it changed during the regenerative response. For this purpose, we first established a decellularization protocol of adult zebrafish ventricles that significantly enriched the yield of ECM proteins. We then performed proteomic analyses of decellularized control hearts and at different times of regeneration. Our results show a dynamic change in ECM protein composition, most evident at the earliest (7 days postamputation) time point analyzed. Regeneration associated with sharp increases in specific ECM proteins, and with an overall decrease in collagens and cytoskeletal proteins. We finally tested by atomic force microscopy that the changes in ECM composition translated to decreased ECM stiffness. Our cumulative results identify changes in the protein composition and mechanical properties of the zebrafish heart ECM during regeneration.

Traction forces at the cytokinetic ring regulate cell division and polyploidy in the migrating zebrafish epicardium.

Epithelial repair and regeneration are driven by collective cell migration and division. Both cellular functions involve tightly controlled mechanical events, but how physical forces regulate cell division in migrating epithelia is largely unknown. Here we show that cells dividing in the migrating zebrafish epicardium exert large cell-extracellular matrix (ECM) forces during cytokinesis. These forces point towards the division axis and are exerted through focal adhesions that connect the cytokinetic ring to the underlying ECM. When subjected to high loading rates, these cytokinetic focal adhesions prevent closure of the contractile ring, leading to multi-nucleation through cytokinetic failure. By combining a clutch model with experiments on substrates of different rigidity, ECM composition and ligand density, we show that failed cytokinesis is triggered by adhesion reinforcement downstream of increased myosin density. The mechanical interaction between the cytokinetic ring and the ECM thus provides a mechanism for the regulation of cell division and polyploidy that may have implications in regeneration and cancer.

[Establishment of knowledge, attitudes and opinions of general population about rational use of medicines]. / Establecimiento de los conocimientos, actitudes y opiniones de la población sobre el uso racional de medicamentos.

OBJECTIVE: Identify the level of knowledge, opinions and attitudes of medicines in general population. METHODS: Descriptive transversal study realised in a sample of≥18 years old public health users from primary health centres in the city of Barcelona. Sample has been chosen using a two phases sampling, stratified by district, gender and age. Questionnaire administered face-to-face. SPSSv15 used for the analysis. STUDY PERIOD: December 2011. RESULTS: 484 surveys has been done (IC 95%, α=5%). 53% were women and 21,3% had university studies. Medicine use: 81% had taken medicines in the last 3 months; average of 2,34. TECHNICAL CONCEPTS: 80% of medicated people know what they take and its indication. 55,6% don't know active ingredient concept. Only 35% recognise the active ingredient showed in the box of the medicine (3 cases shown) and 44,5% not one. 22,7% know the meaning of security concepts contraindication, adverse effect and drug interaction. 20% ignore. This fact grows with age and reduces with high study levels. OPINION AND ATTITUDE: Global rational use of medicines indicator obtains 5,03 from 10: 3,42 opinion and 6,51 attitude. 70% of people think there is no rational use of medicines in general and 21,3% would promote raising awareness. CONCLUSIONS: Low level of knowledge and poor attitude and opinion in rational use of medicines have been shown in this study. It is necessary involve citizens and improve their basic knowledge to promote rational use of medicines.

Fate predetermination of cardiac myocytes during zebrafish heart regeneration.

Adult zebrafish have the remarkable ability to regenerate their heart upon injury, a process that involves limited dedifferentiation and proliferation of spared cardiomyocytes (CMs), and migration of their progeny. During regeneration, proliferating CMs are detected throughout the myocardium, including areas distant to the injury site, but whether all of them are able to contribute to the regenerated tissue remains unknown. Here, we developed a CM-specific, photoinducible genetic labelling system, and show that CMs labelled in embryonic hearts survive and contribute to all three (primordial, trabecular and cortical) layers of the adult zebrafish heart. Next, using this system to investigate the fate of CMs from different parts of the myocardium during regeneration, we show that only CMs immediately adjacent to the injury site contributed to the regenerated tissue. Finally, our results show an extensive predetermination of CM fate during adult heart regeneration, with cells from each myocardial layer giving rise to cells that retain their layer identity in the regenerated myocardium. Overall, our results indicate that adult heart regeneration in the zebrafish is a rather static process governed by short-range signals, in contrast to the highly dynamic plasticity of CM fates that takes place during embryonic heart regeneration.