Deciphering neural heterogeneity through cell lineage tracing.

Understanding how an adult brain reaches an appropriate size and cell composition from a pool of progenitors that proliferates and differentiates is a key question in Developmental Neurobiology. Not only the control of final size but also, the proper arrangement of cells of different embryonic origins is fundamental in this process. Each neural progenitor has to produce a precise number of sibling cells that establish clones, and all these clones will come together to form the functional adult nervous system. Lineage cell tracing is a complex and challenging process that aims to reconstruct the offspring that arise from a single progenitor cell. This tracing can be achieved through strategies based on genetically modified organisms, using either genetic tracers, transfected viral vectors or DNA constructs, and even single-cell sequencing. Combining different reporter proteins and the use of transgenic mice revolutionized clonal analysis more than a decade ago and now, the availability of novel genome editing tools and single-cell sequencing techniques has vastly improved the capacity of lineage tracing to decipher progenitor potential. This review brings together the strategies used to study cell lineages in the brain and the role they have played in our understanding of the functional clonal relationships among neural cells. In addition, future perspectives regarding the study of cell heterogeneity and the ontogeny of different cell lineages will also be addressed.

Cell Fate of Retinal Progenitor Cells: In Ovo UbC-StarTrack Analysis.

Clonal cell analysis outlines the ontogenic potential of single progenitor cells, allowing the elucidation of the neural heterogeneity among different cell types and their lineages. In this work, we analyze the potency of retinal stem/progenitor cells through development using the chick embryo as a model. We implemented in ovo the clonal genetic tracing strategy UbC-StarTrack for tracking retinal cell lineages derived from individual progenitors of the ciliary margin at E3.5 (HH21-22). The clonal assignment of the derived-cell progeny was performed in the neural retina at E11.5-12 (HH38) through the identification of sibling cells as cells expressing the same combination of fluorophores. Moreover, cell types were assessed based on their cellular morphology and laminar location. Ciliary margin derived-cell progenies are organized in columnar associations distributed along the peripheral retina with a limited tangential dispersion. The analysis revealed that, at the early stages of development, this region harbors multipotent and committed progenitor cells.

Multiple origins and modularity in the spatiotemporal emergence of cerebellar astrocyte heterogeneity.

The morphological, molecular, and functional heterogeneity of astrocytes is under intense scrutiny, but how this diversity is ontogenetically achieved remains largely unknown. Here, by quantitative in vivo clonal analyses and proliferation studies, we demonstrate that the major cerebellar astrocyte types emerge according to an unprecedented and remarkably orderly developmental program comprising (i) a time-dependent decline in both clone size and progenitor multipotency, associated with clone allocation first to the hemispheres and then to the vermis(ii) distinctive clonal relationships among astrocyte types, revealing diverse lineage potentials of embryonic and postnatal progenitors; and (iii) stereotyped clone architectures and recurrent modularities that correlate to layer-specific dynamics of postnatal proliferation/differentiation. In silico simulations indicate that the sole presence of a unique multipotent progenitor at the source of the whole astrogliogenic program is unlikely and rather suggest the involvement of additional committed components.

Heterogeneity and Bipotency of Astroglial-Like Cerebellar Progenitors along the Interneuron and Glial Lineages.

Cerebellar GABAergic interneurons in mouse comprise multiple subsets of morphologically and neurochemically distinct phenotypes located at strategic nodes of cerebellar local circuits. These cells are produced by common progenitors deriving from the ventricular epithelium during embryogenesis and from the prospective white matter (PWM) during postnatal development. However, it is not clear whether these progenitors are also shared by other cerebellar lineages and whether germinative sites different from the PWM originate inhibitory interneurons. Indeed, the postnatal cerebellum hosts another germinal site along the Purkinje cell layer (PCL), in which Bergmann glia are generated up to first the postnatal weeks, which was proposed to be neurogenic. Both PCL and PWM comprise precursors displaying traits of juvenile astroglia and neural stem cell markers. First, we examine the proliferative and fate potential of these niches, showing that different proliferative dynamics regulate progenitor amplification at these sites. In addition, PCL and PWM differ in the generated progeny. GABAergic interneurons are produced exclusively by PWM astroglial-like progenitors, whereas PCL precursors produce only astrocytes. Finally, through in vitro, ex vivo, and in vivo clonal analyses we provide evidence that the postnatal PWM hosts a bipotent progenitor that gives rise to both interneurons and white matter astrocytes.

Relaxation time asymmetry in stator dynamics of the bacterial flagellar motor.

The bacterial flagellar motor is the membrane-embedded rotary motor, which turns the flagellum that provides thrust to many bacteria. This large multimeric complex, composed of a few dozen constituent proteins, is a hallmark of dynamic subunit exchange. The stator units are inner-membrane ion channels that dynamically bind to the peptidoglycan at the rotor periphery and apply torque. Their dynamic exchange is a function of the viscous load on the flagellum, allowing the bacterium to adapt to its local environment, although the molecular mechanisms of mechanosensitivity remain unknown. Here, by actively perturbing the steady-state stator stoichiometry of individual motors, we reveal a stoichiometry-dependent asymmetry in stator remodeling kinetics. We interrogate the potential effect of next-neighbor interactions and local stator unit depletion and find that neither can explain the observed asymmetry. We then simulate and fit two mechanistically diverse models that recapitulate the asymmetry, finding assembly dynamics to be particularly well described by a two-state catch-bond mechanism.

Correction: Study of the efficacy of the Hero program: Cross-national evidence.

[This corrects the article DOI: 10.1371/journal.pone.0238442.].

Astrocytes and neurons share region-specific transcriptional signatures that confer regional identity to neuronal reprogramming.

Neural cell diversity is essential to endow distinct brain regions with specific functions. During development, progenitors within these regions are characterized by specific gene expression programs, contributing to the generation of diversity in postmitotic neurons and astrocytes. While the region-specific molecular diversity of neurons and astrocytes is increasingly understood, whether these cells share region-specific programs remains unknown. Here, we show that in the neocortex and thalamus, neurons and astrocytes express shared region-specific transcriptional and epigenetic signatures. These signatures not only distinguish cells across these two brain regions but are also detected across substructures within regions, such as distinct thalamic nuclei, where clonal analysis reveals the existence of common nucleus-specific progenitors for neurons and astrocytes. Consistent with their shared molecular signature, regional specificity is maintained following astrocyte-to-neuron reprogramming. A detailed understanding of these regional-specific signatures may thus inform strategies for future cell-based brain repair.

Therapeutic drug monitoring of mycophenolic acid in patients with psoriasis.

Mycophenolate mofetil (MMF) has been shown to be effective in the treatment of psoriasis. MMF is the morpholinoethyl ester of mycophenolic acid (MPA), the active compound. Our objective was to characterize the pharmacokinetic profile of MPA in patients with psoriasis treated with MMF and to examine its correlation with effectiveness and toxicity. Eleven patients with moderate-to-severe chronic plaque psoriasis were treated with oral MMF 30 mg kg-1 daily over a period of 16 weeks. Patients were reviewed at 3, 8 and 16 weeks, checking the Psoriasis Area and Severity Index (PASI) and possible adverse events, and performing MPA C0 (trough) and C1 (1-hour post-dose) plasma levels. The reduction in PASI was statistically significant in all our patients. The drug was well tolerated. There was no significant correlation between C0 and C1 MPA levels and the reduction of PASI, improvement rates of PASI from baseline, weight of the patients and total dosage of MMF. Nevertheless, the highest detected mean levels of MPA C1 were observed in two of the patients with the highest improvement rate of PASI at the end of the study. Although C1 levels do not seem to strongly correlate with the effectiveness of the drug, the finding that the highest detected mean levels of MPA C1 were observed in two of the patients with the highest improvement rate of PASI suggests that the monitoring of C1 could be useful in some individual cases.

Study of the efficacy of the Hero program: Cross-national evidence.

The present study focuses on an analysis of the efficacy of the online intervention program called "Hero" for promoting prosociality and other socioemotional variables related to prosocial behavior, such as empathy, positive emotions, and forgiveness, in two Latin American countries: Argentina and Uruguay. The final Argentinean sample consisted of 579 adolescents (experimental group = 319 and control group = 260), and the Uruguayan sample consisted of 330 adolescents (experimental group = 140 and control group = 169), aged 12 to 15 years old. The 'Hero' program provided evidence of efficacy for the promotion of prosociality, empathy, positive emotions, and attitudes of forgiveness. It impacted each of the dimensions comprising these variables differently depending on the country where it was applied. We discuss the differences found in each country.

Cell Progeny in the Olfactory Bulb After Targeting Specific Progenitors with Different UbC-StarTrack Approaches.

The large phenotypic variation in the olfactory bulb may be related to heterogeneity in the progenitor cells. Accordingly, the progeny of subventricular zone (SVZ) progenitor cells that are destined for the olfactory bulb is of particular interest, specifically as there are many facets of these progenitors and their molecular profiles remain unknown. Using modified StarTrack genetic tracing strategies, specific SVZ progenitor cells were targeted in E12 mice embryos, and the cell fate of these neural progenitors was determined in the adult olfactory bulb. This study defined the distribution and the phenotypic diversity of olfactory bulb interneurons from specific SVZ-progenitor cells, focusing on their spatial pallial origin, heterogeneity, and genetic profile.

Lineage Tracing and Cell Potential of Postnatal Single Progenitor Cells In Vivo.

Understanding the contribution of adult neural progenitor cells (NPCs) and their lineage potential is a great challenge in neuroscience. To reveal progenitor diversity and cell-lineage relationships of postnatal NPCs in the subventricular zone (SVZ), we performed in vivo lineage-tracing genetic analysis using the UbC-StarTrack. We determined the progeny of single SVZ-NPCs, the number of cells per clone, the dispersion of sibling cells, and the cell types within clones. Long-term analysis revealed that both the cell-dispersion pattern and number of cells comprising clones varied depending on the glial/neuronal nature of sibling cells. Sibling-olfactory interneurons were primarily located within the same layer, while sibling-glial cells populated SVZ-adjacent areas. Sibling astrocytes and interneurons did not form big clones, whereas oligodendroglial-lineage clones comprised the largest clones originated in adult brains. These results demonstrate the existence of SVZ postnatal bipotential progenitors that give rise to clones widely dispersed across the olfactory bulb and SVZ-adjacent areas.

Development of Ependymal and Postnatal Neural Stem Cells and Their Origin from a Common Embryonic Progenitor.

The adult mouse brain contains an extensive neurogenic niche in the lateral walls of the lateral ventricles. This epithelium, which has a unique pinwheel organization, contains multiciliated ependymal (E1) cells and neural stem cells (B1). This postnatal germinal epithelium develops from the embryonic ventricular zone, but the lineage relationship between E1 and B1 cells remains unknown. Distinct subpopulations of radial glia (RG) cells in late embryonic and early postnatal development either expand their apical domain >11-fold to form E1 cells or retain small apical domains that coalesce into the centers of pinwheels to form B1 cells. Using independent methods of lineage tracing, we show that individual RG cells can give rise to clones containing E1 and B1 cells. This study reveals key developmental steps in the formation of the postnatal germinal niche and the shared cellular origin of E1 and B1 cells.

Calciphylaxis.

Calciphylaxis is defined by the presence of calcium deposits within the wall of small and medium-sized vessels. It is classically considered a life-threatening disease in patients with end-stage renal disease under dialysis. Clinically, it is characterized by the presence of painful plaques surrounded by a reticulate purpura that progresses to nonhealing ulcers, predominately in the lower limbs. It is associated with elevated parathyroid hormone levels and a dysregulation of the calcium/phosphate metabolism. In the absence of renal disease, normal parathyroid hormone levels, and calcium/phosphorus product, a good prognosis and the observation of similar calcium deposits associated with different conditions or even an epiphenomenon in diseases with well-known diagnosis leads one to consider the term calciphylaxis controversial.

Stage-Specific Transcription Factors Drive Astrogliogenesis by Remodeling Gene Regulatory Landscapes.

A broad molecular framework of how neural stem cells are specified toward astrocyte fate during brain development has proven elusive. Here we perform comprehensive and integrated transcriptomic and epigenomic analyses to delineate gene regulatory programs that drive the developmental trajectory from mouse embryonic stem cells to astrocytes. We report molecularly distinct phases of astrogliogenesis that exhibit stage- and lineage-specific transcriptomic and epigenetic signatures with unique primed and active chromatin regions, thereby revealing regulatory elements and transcriptional programs underlying astrocyte generation and maturation. By searching for transcription factors that function at these elements, we identified NFIA and ATF3 as drivers of astrocyte differentiation from neural precursor cells while RUNX2 promotes astrocyte maturation. These transcription factors facilitate stage-specific gene expression programs by switching the chromatin state of their target regulatory elements from primed to active. Altogether, these findings provide integrated insights into the genetic and epigenetic mechanisms steering the trajectory of astrogliogenesis.

Análisis psicométrico de la Escala de Experiencias Espirituales Diarias en adolescentes y jóvenes argentinos / Daily Spiritual Experiences Scale Psychometric Analysis among Argentinian Adolescents and Young Adults

Objetivo. El objetivo de este estudio fue evaluar las propiedades psicométricas de la Escala de Experiencias Espirituales Diarias (DSES). Se analiza específicamente la consistencia interna, la discriminación de los ítems, la estructura factorial exploratoria y confirmatoria, y la validez constructiva. Método. Se conformó una muestra de 692 adolescentes y jóvenes entre los 12 y los 28 años. Se aplicó además la Escala de Experiencias Espirituales Diarias y la dimensión bienestar emocional de la Escala Multidimensional de Flourishing. Resultados. Se evidenciaron ítems discriminativos y buena consistencia interna. Se comprobó la estructura unifactorial, y se halló correlación entre la espiritualidad y el bienestar emocional, lo cual respalda la validez constructiva. Se concluye que la DSES presenta adecuadas propiedades psicométricas que apoyan su uso para la evaluación de la espiritualidad en adolescentes y jóvenes argentinos.

Objective. The present work aimed to evaluate the psychometric properties of the Daily Spiritual Experience Scale (DSES), specifically analyzing the internal consistency, the discrimination of the items, the exploratory and confirmatory factorial structure, and the constructive validity. Method. A sample of 692 adolescents and young adults aged between 12 and 28 years old was collected. In addition, the Daily Spiritual Experiences Scale and the emotional well-being dimension of the Multidimensional Flourishing Scale were applied. Results. Discriminatory items and good internal consistency were evidenced. The unifactorial structure was verified, and a correlation between spirituality and emotional well-being was found, which supports the construct's validity. It is concluded that the DSES has adequate psychometric properties that support its use for the evaluation of spirituality in Argentine adolescents and young adults.

Evaluación de la terapia de reproducción médicamente asistida en 9 años: estudio de cohorte retrospectivo / Medically assisted reproductive therapy assessment in 9 years: retrospective cohort study

OBJETIVO: Describir las tasas de recién nacidos vivos (RNV) y embarazo de la terapia de reproducción médicamente asistida de baja complejidad del Centro de Reproducción Humana de la Universidad de Valparaíso, Chile. MÉTODO: Estudio retrospectivo de todos los ciclos de estimulación ovárica controlada con inseminación intrauterina (IIU) completados, entre los años 2011 y 2019. Se evaluaron las características clínicas basales y los resultados en IIU homólogas y heterólogas según el ciclo inseminado, la causa de infertilidad, el rango etario y el índice de masa corporal (IMC). El desenlace principal fue la tasa de RNV por ciclo inseminado. RESULTADOS: Se estudiaron 1415 ciclos en 700 parejas. La tasa acumulativa de RNV fue del 19,6%, un 18,3% en IIU homóloga y un 39,0% en IIU heteróloga. La tasa de RNV fue del 10,0% al primer ciclo, del 5,8% al segundo ciclo y del 3,7% al tercer o más ciclos. Al separar por IIU heteróloga, esta aumenta al 24,4% al primer ciclo y al 14,6% al segundo ciclo. La tasa de RNV es significativamente mejor en pacientes menores de 35 años (23,7%) y con IMC < 29 (20,8%). CONCLUSIONES: El tratamiento de baja complejidad en pacientes infértiles es una opción terapéutica vigente con una aceptable tasa de RNV por ciclo inseminado. Los resultados están influenciados por la edad y por el IMC.

OBJECTIVE: To describe the rates of live newborns (LNB) and pregnancy of the low complexity therapy of the Centre for Human Reproduction of Universidad de Valparaíso, Chile. METHOD: Retrospective study of all cycles of controlled ovarian stimulation with intrauterine insemination (IUI) completed between 2011-2019. The baseline clinical characteristics and results in homologous and heterologous IUI were evaluated according to inseminated cycle, cause of infertility, age range and body mass index (BMI). The main outcome was rate of LNB per inseminated cycle. RESULTS: 1415 cycles were studied in 700 couples. The cumulative rate of LNB was 19.6%, 18.3% in homologous IUI and 39.0% in heterologous IUI. The LNB rate was 10.0% at the first cycle, 5.8% at the second cycle, 3.7% at the third or more cycles. When separating by heterologous IUI, it increases to 24.4% in the first cycle and 14.6% in the second cycle. The LNB rate is significantly better in patients under 35 years of age (23.7%) and with a BMI less than 29 (20.8%). CONCLUSIONS: Treatment of low complexity in selected infertile patients is a current therapeutic option with an acceptable rate of LNB per inseminated cycle. The results are influenced by age and BMI.

Adult Olfactory Bulb Interneuron Phenotypes Identified by Targeting Embryonic and Postnatal Neural Progenitors.

Neurons are generated during embryonic development and in adulthood, although adult neurogenesis is restricted to two main brain regions, the hippocampus and olfactory bulb. The subventricular zone (SVZ) of the lateral ventricles generates neural stem/progenitor cells that continually provide the olfactory bulb (OB) with new granule or periglomerular neurons, cells that arrive from the SVZ via the rostral migratory stream. The continued neurogenesis and the adequate integration of these newly generated interneurons is essential to maintain homeostasis in the olfactory bulb, where the differentiation of these cells into specific neural cell types is strongly influenced by temporal cues. Therefore, identifying the critical features that control the generation of adult OB interneurons at either pre- or post-natal stages is important to understand the dynamic contribution of neural stem cells. Here, we used in utero and neonatal SVZ electroporation along with a transposase-mediated stable integration plasmid, in order to track interneurons and glial lineages in the OB. These plasmids are valuable tools to study the development of OB interneurons from embryonic and post-natal SVZ progenitors. Accordingly, we examined the location and identity of the adult progeny of embryonic and post-natally transfected progenitors by examining neurochemical markers in the adult OB. These data reveal the different cell types in the olfactory bulb that are generated in function of age and different electroporation conditions.

UbC-StarTrack, a clonal method to target the entire progeny of individual progenitors.

Clonal cell analysis defines the potential of single cells and the diversity they can produce. To achieve this, we have developed a novel adaptation of the genetic tracing strategy, UbC-StarTrack, which attributes a specific and unique color-code to single neural precursors, allowing all their progeny to be tracked. We used integrable fluorescent reporters driven by a ubiquitous promoter in PiggyBac-based vectors to achieve inheritable and stable clonal cell labeling. In addition, coupling this to an inducible Cre-LoxP system avoids the expression of non-integrated reporters. To assess the utility of this system, we first analyzed images of combinatorial expression of fluorescent reporters in transfected cells and their progeny. We also validated the efficiency of the UbC-StarTrack to trace cell lineages through in vivo, in vitro and ex vivo strategies. Finally, progenitors located in the lateral ventricles were targeted at embryonic or postnatal stages to determine the diversity of neurons and glia they produce, and their clonal relationships. In this way we demonstrate that UbC-StarTrack can be used to identify all the progeny of a single cell and that it can be employed in a wide range of contexts.

Spatiotemporal analyses of neural lineages after embryonic and postnatal progenitor targeting combining different reporters.

Genetic lineage tracing with electroporation is one of the most powerful techniques to target neural progenitor cells and their progeny. However, the spatiotemporal relationship between neural progenitors and their final phenotype remain poorly understood. One critical factor to analyze the cell fate of progeny is reporter integration into the genome of transfected cells. To address this issue, we performed postnatal and in utero co-electroporations of different fluorescent reporters to label, in both cerebral cortex and olfactory bulb, the progeny of subventricular zone neural progenitors. By comparing fluorescent reporter expression in the adult cell progeny, we show a differential expression pattern within the same cell lineage, depending on electroporation stage and cell identity. Further, while neuronal lineages arise from many progenitors in proliferative zones after few divisions, glial lineages come from fewer progenitors that accomplish many cell divisions. Together, these data provide a useful guide to select a strategy to track the cell fate of a specific cell population and to address whether a different proliferative origin might be correlated with functional heterogeneity.