First meeting of the Portuguese Society for Developmental Biology (SPBD)

[excerpt] The 1st Meeting of the Portuguese Society for DevelopmentalBiology (SPBD – Sociedade Portuguesa de Biologia doDesenvolvimento; was held during two sunny autumndays at the Instituto Gulbenkian de Ciência (IGC) locatedin the beautiful seaside city of Oeiras. This smallmeeting provided unprecedented conditions for Portuguese Developmental Biology researchers to know what is being done inPortugal, to receive feedback on their own work and to establishstrong and productive national collaborations.(undefined

The right time for senescence

Funding: We are truly grateful to Pedro Sousa-Vitor, Miguel Godinho-Ferreira, and Mariana AscençãoFerreira for critical reading of the manuscript. This work was supported by a FCT PhD Fellowship (PD/BD/105770/2014) to DPC, and co-funded by the FCT (PTDC/MED-NEU/30428/2017), 'la Caixa' Banking Foundation and FCT, IP, under project code HR18-00187 and SCML Melo e Castro Award (MC36-2020).Cellular senescence is a highly complex and programmed cellular state with diverse and, at times, conflicting physiological and pathological roles across the lifespan of an organism. Initially considered a cell culture artifact, senescence evolved from an age-related circumstance to an intricate cellular defense mechanism in response to stress, implicated in a wide spectrum of biolog­ical processes like tissue remodelling, injury and cancer. The development of new tools to study senescence in vivo paved the way to uncover its functional roles in various frameworks, which are sometimes hard to reconcile. Here, we review the functional impact of senescent cells on different organismal contexts. We provide updated insights on the role of senescent cells in tissue repair and regeneration, in which they essentially modulate the levels of fibrosis and inflammation, discussing how “time” seems to be the key maestro of their effects. Finally, we overview the current clinical research landscape to target senescent cells and contemplate its repercussions on this fast-evolving field.publishersversionpublishe

An amputation resets positional information to a proximal identity in the regenerating zebrafish caudal fin

We thank Lara Carvalho and Fabio Valerio for excellent zebrafish husbandry, Andreia Pinto for histology and Antonio Temudo for imaging support. We are grateful to C. Certal and S. Pascoal for comments on the manuscript. A. S. A and S. S were supported by FCT fellowships (SFRH/BD/33179/2007 and SFER/BD/32952/2006). L. S. was supported by two FCT grants (PTDC/SAU-OBD/64628/2006 and PTDC/SAU-OBD/100202/2008) and A.J. was supported by one FCT grant (PTDC/SAU-OBD/100200/2008).Background: Zebrafish has emerged as a powerful model organism to study the process of regeneration. This teleost fish has the ability to regenerate various tissues and organs like the heart, spinal cord, retina and fins. In this study, we took advantage of the existence of an excellent morphological reference in the zebrafish caudal fin, the bony ray bifurcations, as a model to study positional information upon amputation. We investigated the existence of positional information for bifurcation formation by performing repeated amputations at different proximal-distal places along the fin. Results: We show that, while amputations performed at a long distance from the bifurcation do not change its final proximal-distal position in the regenerated fin, consecutive amputations done at 1 segment proximal to the bifurcation (near the bifurcation) induce a positional reset and progressively shift its position distally. Furthermore, we investigated the potential role of Shh and Fgf signalling pathways in the determination of the bifurcation position and observed that they do not seem to be involved in this process. Conclusions: Our results reveal that, an amputation near the bifurcation inhibits the formation of the regenerated bifurcation in the pre-amputation position, inducing a distalization of this structure. This shows that the positional memory for bony ray bifurcations depends on the proximal-distal level of the amputation.publishersversionpublishe

Foxj1a is expressed in ependymal precursors, controls central canal position and is activated in new ependymal cells during regeneration in zebrafish

© 2017 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are creditedZebrafish are able to regenerate the spinal cord and recover motor and sensory functions upon severe injury, through the activation of cells located at the ependymal canal. Here, we show that cells surrounding the ependymal canal in the adult zebrafish spinal cord express Foxj1a. We demonstrate that ependymal cells express Foxj1a from their birth in the embryonic neural tube and that Foxj1a activity is required for the final positioning of the ependymal canal. We also show that in response to spinal cord injury, Foxj1a ependymal cells actively proliferate and contribute to the restoration of the spinal cord structure. Finally, this study reveals that Foxj1a expression in the injured spinal cord is regulated by regulatory elements activated during regeneration. These data establish Foxj1a as a pan-ependymal marker in development, homeostasis and regeneration and may help identify the signals that enable this progenitor population to replace lost cells after spinal cord injury.This research was supported by FCT (Portugal) grants (PTDC/BIM-MED/1375/2012 and PTDC/BIM-MED/3295/2014) given to L.S. L.S. was supported by an IF contract from FCT (Portugal). A.R. was supported by a postdoctoral fellowship of the FCT (Portugal) (SFRH/BPD/100162/2014) and EMBO (605-2012)info:eu-repo/semantics/publishedVersio

Targeting senescent cells improves functional recovery after spinal cord injury

© The Author(s). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Persistent senescent cells (SCs) are known to underlie aging-related chronic disorders, but it is now recognized that SCs may be at the center of tissue remodeling events, namely during development or organ repair. In this study, we show that two distinct senescence profiles are induced in the context of a spinal cord injury between the regenerative zebrafish and the scarring mouse. Whereas induced SCs in zebrafish are progressively cleared out, they accumulate over time in mice. Depletion of SCs in spinal-cord-injured mice, with different senolytic drugs, improves locomotor, sensory, and bladder functions. This functional recovery is associated with improved myelin sparing, reduced fibrotic scar, and attenuated inflammation, which correlate with a decreased secretion of pro-fibrotic and pro-inflammatory factors. Targeting SCs is a promising therapeutic strategy not only for spinal cord injuries but potentially for other organs that lack regenerative competence.D.P.d.C. was supported by a FCT PhD fellowship (PD/BD/105770/2014). I.M. was supported by a FCT post-doctoral fellowship (SFRH/BPD/118051/2016). A.M.C. was supported by a FCT fellowship (PTDC/BOM-MED/3295/2014). A.F.D. was supported by CONGENTO LISBOA-01-0145-FEDER-022170, co-financed by FCT (Portugal) and Lisboa2020, under the PORTUGAL2020 agreement (European Regional Development Fund). D.N.-S. was supported by a FCT PhD fellowship (SFRH/BD/138636/2018). D.C. was supported by a FCT PhD fellowship (PD/BD/114179/2016). L.S. was supported by a FCT IF contract. The project leading to these results has received funding from a FCT grant (PTDC/MED-NEU/30428/2017) and “la Caixa” Banking Foundation and FCT, I.P., under project code HR18-00187.info:eu-repo/semantics/publishedVersio

Monkeypox: o que estamos esperando para agir?

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Left-Right Function of dmrt2 Genes Is Not Conserved between Zebrafish and Mouse

Background: Members of the Dmrt family, generally associated with sex determination, were shown to be involved in several other functions during embryonic development. Dmrt2 has been studied in the context of zebrafish development where, due to a duplication event, two paralog genes dmrt2a and dmrt2b are present. Both zebrafish dmrt2a/terra and dmrt2b are important to regulate left-right patterning in the lateral plate mesoderm. In addition, dmrt2a/terra is necessary for symmetric somite formation while dmrt2b regulates somite differentiation impacting on slow muscle development. One dmrt2 gene is also expressed in the mouse embryo, where it is necessary for somite differentiation but with an impact on axial skeleton development. However, nothing was known about its role during left-right patterning in the lateral plate mesoderm or in the symmetric synchronization of somite formation. Methodology/Principal Findings: Using a dmrt2 mutant mouse line, we show that this gene is not involved in symmetric somite formation and does not regulate the laterality pathway that controls left-right asymmetric organ positioning. We reveal that dmrt2a/terra is present in the zebrafish laterality organ, the Kupffer’s vesicle, while its homologue is excluded from the mouse equivalent structure, the node. On the basis of evolutionary sub-functionalization and neo-functionalization theories we discuss this absence of functional conservation. Conclusions/Significance: Our results show that the role of dmrt2 gene is not conserved during zebrafish and mous

Risk factors for differential outcome following directly observed treatment (DOT) of slum and non-slum tuberculosis patients: a retrospective cohort study

BACKGROUND: Brazil’s National Tuberculosis Control Program seeks to improve tuberculosis (TB) treatment in vulnerable populations. Slum residents are more vulnerable to TB due to a variety of factors, including their overcrowded living conditions, substandard infrastructure, and limited access to healthcare compared to their non-slum dwelling counterparts. Directly observed treatment (DOT) has been suggested to improve TB treatment outcomes among vulnerable populations, but the program’s differential effectiveness among urban slum and non-slum residents is not known. METHODS: We retrospectively compared the impact of DOT on TB treatment outcome in residents of slum and non-slum census tracts in Rio de Janeiro reported to the Brazilian Notifiable Disease Database in 2010. Patient residential addresses were geocoded to census tracts from the 2010 Brazilian Census, which were identified as slum (aglomerados subnormais -AGSN) and non-slum (non-AGSN) by the Census Bureau. Homeless and incarcerated cases as well as those geocoded outside the city’s limits were excluded from analysis. RESULTS: In 2010, 6,601 TB cases were geocoded within Rio de Janeiro; 1,874 (27.4 %) were residents of AGSN, and 4,794 (72.6 %) did not reside in an AGSN area. DOT coverage among AGSN cases was 35.2 % (n = 638), while the coverage in non-AGSN cases was 26.2 % (n = 1,234). Clinical characteristics, treatment, follow-up, cure, death and abandonment were similar in both AGSN and non-AGSN TB patients. After adjusting for covariates, AGSN TB cases on DOT had 1.67 (95 % CI: 1.17, 2.4) times the risk of cure, 0.61 (95 % CI: 0.41, 0.90) times the risk of abandonment, and 0.1 (95 % CI: 0.01, 0.77) times the risk of death from TB compared to non-AGSN TB cases not on DOT. CONCLUSION: While DOT coverage was low among TB cases in both AGSN and non-AGSN communities, it had a greater impact on TB cure rate in AGSN than in non-AGSN populations in the city of Rio de Janeiro

The Regenerative Capacity of the Zebrafish Caudal Fin Is Not Affected by Repeated Amputations

Background: The zebrafish has the capacity to regenerate many tissues and organs. The caudal fin is one of the most convenient tissues to approach experimentally due to its accessibility, simple structure and fast regeneration. In this work we investigate how the regenerative capacity is affected by recurrent fin amputations and by experimental manipulations that block regeneration. Methodology/Principal Findings: We show that consecutive repeated amputations of zebrafish caudal fin do not reduce its regeneration capacity and do not compromise any of the successive regeneration steps: wound healing, blastema formation and regenerative outgrowth. Interfering with Wnt/ß-catenin signalling using heat-shock-mediated overexpression of Dickkopf1 completely blocks fin regeneration. Notably, if these fins were re-amputated at the non-inhibitory temperature, the regenerated caudal fin reached the original length, even after several rounds of consecutive Wnt/ß-catenin signalling inhibition and re-amputation. Conclusions/Significance: We show that the caudal fin has an almost unlimited capacity to regenerate. Even after inhibition of regeneration caused by the loss of Wnt/ß-catenin signalling, a new amputation resets the regeneration capacity within the caudal fin, suggesting that blastema formation does not depend on a pool of stem/progenitor cells that require Wnt/ßcateni

Identification of Dmrt2a downstream genes during zebrafish early development using a timely controlled approach

This research was supported by FCT (Portugal) grant (PTDC/SAU-BID/119627/2010) given to L.S. L.S. was supported by an IF contract from FCT (Portugal). R.A.P. was supported by a PhD fellowship (SFRH/BD/87607/2012) from FCT (Portugal). Publication was sponsored by LISBOA-01-0145-FEDER-007391, project co-funded by FEDER through POR Lisboa 2020 - Programa Operacional Regional de Lisboa, PORTUGAL 2020 and by Fundacao para a Ciencia e a Tecnologia.BACKGROUND: Dmrt2a is a zinc finger like transcription factor with several roles during zebrafish early development: left-right asymmetry, synchronisation of the somite clock genes and fast muscle differentiation. Despite the described functions, Dmrt2a mechanism of action is unknown. Therefore, with this work, we propose to identify Dmrt2a downstream genes during zebrafish early development. RESULTS: We generated and validated a heat-shock inducible transgenic line, to timely control dmrt2a overexpression, and dmrt2a mutant lines. We characterised dmrt2a overexpression phenotype and verified that it was very similar to the one described after knockdown of this gene, with left-right asymmetry defects and desynchronisation of somite clock genes. Additionally, we identified a new phenotype of somite border malformation. We generated several dmrt2a mutant lines, but we only detected a weak to negligible phenotype. As dmrt2a has a paralog gene, dmrt2b, with similar functions and expression pattern, we evaluated the possibility of redundancy. We found that dmrt2b does not seem to compensate the lack of dmrt2a. Furthermore, we took advantage of one of our mutant lines to confirm dmrt2a morpholino specificity, which was previously shown to be a robust knockdown tool in two independent studies. Using the described genetic tools to perform and validate a microarray, we were able to identify six genes downstream of Dmrt2a: foxj1b, pxdc1b, cxcl12b, etv2, foxc1b and cyp1a. CONCLUSIONS: In this work, we generated and validated several genetic tools for dmrt2a and identified six genes downstream of this transcription factor. The identified genes will be crucial to the future understanding of Dmrt2a mechanism of action in zebrafish.publishersversionpublishe