On a new species of Alomasoma (Eichiura: Bonelliidae) from Antarctica

Alomasoma lanai é uma nova espécie de Bonelliidae (Echiura) coletada na Antartica. A nova espécie é de tamanho médio e abriga muitos machos anões presos a pele do tronco. A espécie mostra uma característica única na forma de umsulco transversal que contem a cova genital

On the burrows of Echiuram worms (Echiura): a survey

Estudou-se o biótopo e a arquitetura das galerias dos equiúros Lissomyema exilii e Ochetostoma erythrogrammons comparando-se os resultados com os existentes na literatura para outros equiuros. Lissomyema exilii constrói, com areia fina e lôdo, uma galeria em forma de U, dentro de conchas de moluscos e de carapaças de equinóides irregulares. As conchas estão enterradas entre 100 e 220 mm de profundidade na areia lodosa; o verme comunica-se com a superfície através de um par de canais estreitos, situados entre a galeria e o sedimento da superfície da praia. Os canais e a galeria são revestidos, internamente, com muco endurecido. No sedimento superficial as galerias de equiúros são identificadas, principalmente, por pequenos montes de pelotas fecais. Lissomyema exilii povoa uma pequena área de fundo de mar da região entre-marés no litoral norte de São Paulo, Brasil; a densida de populacional é de 11 animais/m2. A macrofauna da área em estudo é composta principalmente de poliquetos, moluscos e crustáceos, a maioria dos quais vive em galerias ou apresenta tendências cavadoras. As galerias de Lissomyjema exilii acomodam vários comensais entre eles, cinco espécies de poliquetos, duas de nematodes, duas de entoproctos, uma de nudibrânquio e um crustáceo. Ochetostoma erythrogvammon constrói tubos em forma de L, em praias de areia clara e grossa. Até o momento não foram encontrados comensais nestas galerias

Sipunculus marcusi spec. nov. (Sipuncula) from southern Brazil

Descreve-se Sipunculus marcusi spec. nov. da costa do Estado de São Paulo. A espécie em questão difere das outras do gênero Sipunculus principalmente pelas imensas bases dos músculos retrato res da probóscide; estas bases estão unidas umas às outras abrangendo cerca de 18 faixas musculares longitudinais em cada lado do cordão nervoso ventral

Clonal Characterization of Rat Muscle Satellite Cells: Proliferation, Metabolism and Differentiation Define an Intrinsic Heterogeneity

Satellite cells (SCs) represent a distinct lineage of myogenic progenitors responsible for the postnatal growth, repair and maintenance of skeletal muscle. Distinguished on the basis of their unique position in mature skeletal muscle, SCs were considered unipotent stem cells with the ability of generating a unique specialized phenotype. Subsequently, it was demonstrated in mice that opposite differentiation towards osteogenic and adipogenic pathways was also possible. Even though the pool of SCs is accepted as the major, and possibly the only, source of myonuclei in postnatal muscle, it is likely that SCs are not all multipotent stem cells and evidences for diversities within the myogenic compartment have been described both in vitro and in vivo. Here, by isolating single fibers from rat flexor digitorum brevis (FDB) muscle we were able to identify and clonally characterize two main subpopulations of SCs: the low proliferative clones (LPC) present in major proportion (∼75%) and the high proliferative clones (HPC), present instead in minor amount (∼25%). LPC spontaneously generate myotubes whilst HPC differentiate into adipocytes even though they may skip the adipogenic program if co-cultured with LPC. LPC and HPC differ also for mitochondrial membrane potential (ΔΨm), ATP balance and Reactive Oxygen Species (ROS) generation underlying diversities in metabolism that precede differentiation. Notably, SCs heterogeneity is retained in vivo. SCs may therefore be comprised of two distinct, though not irreversibly committed, populations of cells distinguishable for prominent differences in basal biological features such as proliferation, metabolism and differentiation. By these means, novel insights on SCs heterogeneity are provided and evidences for biological readouts potentially relevant for diagnostic purposes described

The LARGE Principle of Cellular Reprogramming: Lost, Acquired and Retained Gene Expression in Foreskin and Amniotic Fluid-Derived Human iPS Cells

Human amniotic fluid cells (AFCs) are routinely obtained for prenatal diagnostics procedures. Recently, it has been illustrated that these cells may also serve as a valuable model system to study developmental processes and for application in regenerative therapies. Cellular reprogramming is a means of assigning greater value to primary AFCs by inducing self-renewal and pluripotency and, thus, bypassing senescence. Here, we report the generation and characterization of human amniotic fluid-derived induced pluripotent stem cells (AFiPSCs) and demonstrate their ability to differentiate into the trophoblast lineage after stimulation with BMP2/BMP4. We further carried out comparative transcriptome analyses of primary human AFCs, AFiPSCs, fibroblast-derived iPSCs (FiPSCs) and embryonic stem cells (ESCs). This revealed that the expression of key senescence-associated genes are down-regulated upon the induction of pluripotency in primary AFCs (AFiPSCs). By defining distinct and overlapping gene expression patterns and deriving the LARGE (Lost, Acquired and Retained Gene Expression) Principle of Cellular Reprogramming, we could further highlight that AFiPSCs, FiPSCs and ESCs share a core self-renewal gene regulatory network driven by OCT4, SOX2 and NANOG. Nevertheless, these cell types are marked by distinct gene expression signatures. For example, expression of the transcription factors, SIX6, EGR2, PKNOX2, HOXD4, HOXD10, DLX5 and RAXL1, known to regulate developmental processes, are retained in AFiPSCs and FiPSCs. Surprisingly, expression of the self-renewal-associated gene PRDM14 or the developmental processes-regulating genes WNT3A and GSC are restricted to ESCs. Implications of this, with respect to the stability of the undifferentiated state and long-term differentiation potential of iPSCs, warrant further studies

Data for "Identification of a retinoic acid-dependent hemogenic endothelial progenitor from human pluripotent stem cells"

The generation of hematopoietic stem cells (HSCs) from human pluripotent stem cells (hPSCs) is a major goal for regenerative medicine. During embryonic development, HSCs derive from hemogenic endothelium (HE) in a NOTCH and retinoic acid (RA)-dependent manner. While a WNT-dependent (WNTd) patterning of nascent hPSC mesoderm specifies clonally multipotent intra-embryonic-like HOXA+ definitive HE, this HE is functionally unresponsive to RA. Here we show that WNTd mesoderm, prior to HE specification, is actually comprised of two distinct KDR+CD34neg populations. CXCR4negCYP26A1+ mesoderm gives rise to HOXA+ multilineage definitive HE in an RA-independent manner, while CXCR4+ALDH1A2+ mesoderm gives rise to HOXA+ multilineage definitive HE in a stage-specific, RA-dependent manner. Further, both RA-independent (RAi) and -dependent (RAd) HE harbor transcriptional similarity to distinct populations found in the early human embryo, including HSC-competent HE. This revised model of human hematopoietic development provides essential resolution to the regulation and origins of the multiple waves of hematopoiesis. These insights provide the basis for the generation of specific hematopoietic populations, including the de novo specification of HSCs.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Data for "B1 lymphocytes develop independently of Notch signaling during mouse embryonic development"

B1 lymphocytes are a small but unique component of the innate immune-like cells. However, their ontogenic origin is still a matter of debate. Although it is widely accepted that B1 cells originate early in fetal life, whether or not they arise from hematopoietic stem cells (HSCs) is still unclear. In order to shed light on the B1 cell origin, we set out to determine whether their lineage specification is dependent on Notch signaling, which is essential for the HSC generation and, therefore, all derivatives lineages. Using mouse embryonic stem cells (mESCs) to recapitulate murine embryonic development, we have studied the requirement for Notch signaling during the earliest B-cell lymphopoiesis and found that Rbpj-deficient mESCs are able to generate B1 cells. Their Notch independence was confirmed in ex vivo experiments using Rbpj-deficient embryos. In addition, we found that upregulation of Notch signaling induced the emergence of B2 lymphoid cells. Taken together, these findings indicate that control of Notch signaling dose is crucial for different B-cell lineage specification from endothelial cells and provides pivotal information for their in vitro generation from PSCs for therapeutic applications.DOI: 10.1242/dev.199373THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV