Article added to library!
x
Pubchase is a service of protocols.io - free, open access, crowdsourced protocols repository. Explore protocols.
Sign in
Reset password
or connect with
Facebook
By signing in you are agreeing to our
Terms Of Service and Privacy Policy
Developmental Biology
Lineage-specific functions of TET1 in the postimplantation mouse embryo
May 15, 2017   Nature Genetics Add nature.com free-link Cancel
Khoueiry R, Sohni A, Thienpont B, Luo X, Velde JV, Bartoccetti M, Boeckx B, Zwijsen A, Rao A, Lambrechts D, Koh KP
Lineage-specific functions of TET1 in the postimplantation mouse embryo
May 15, 2017
Nature Genetics
The mammalian TET enzymes catalyze DNA demethylation. While they have been intensely studied as major epigenetic regulators, little is known about their physiological roles and the extent of functional redundancy following embryo implantation. Here we define non-redundant roles for TET1 at an early postimplantation stage of the mouse embryo, when its paralogs Tet2 and Tet3 are not detectably expressed. TET1 regulates numerous genes defining differentiation programs in the epiblast and extraembryonic ectoderm. In epiblast cells, TET1 demethylates gene promoters via hydroxymethylation and maintains telomere stability. Surprisingly, TET1 represses a majority of epiblast target genes independently of methylation changes, in part through regulation of the gene encoding the transcriptional repressor JMJD8. Dysregulated gene expression in the absence of TET1 causes embryonic defects, which are partially penetrant in an inbred strain but fully lethal in non-inbred mice. Collectively, our study highlights an interplay between the catalytic and non-catalytic activities of TET1 that is essential for normal development.
Actomyosin meshwork mechanosensing enables tissue shape to orient cell force
May 15, 2017   Nature Communications
Chanet S, Miller CJ, Vaishnav ED, Ermentrout B, Davidson LA, Martin AC
Actomyosin meshwork mechanosensing enables tissue shape to orient cell force
May 15, 2017
Nature Communications
Sculpting organism shape requires that cells produce forces with proper directionality. Thus, it is critical to understand how cells orient the cytoskeleton to produce forces that deform tissues. During Drosophila gastrulation, actomyosin contraction in ventral cells generates a long, narrow epithelial furrow, termed the ventral furrow, in which actomyosin fibres and tension are directed along the length of the furrow. Using a combination of genetic and mechanical perturbations that alter tissue shape, we demonstrate that geometrical and mechanical constraints act as cues to orient the cytoskeleton and tension during ventral furrow formation. We developed an in silico model of two-dimensional actomyosin meshwork contraction, demonstrating that actomyosin meshworks exhibit an inherent force orienting mechanism in response to mechanical constraints. Together, our in vivo and in silico data provide a framework for understanding how cells orient force generation, establishing a role for geometrical and mechanical patterning of force production in tissues.
A placental growth factor is silenced in mouse embryos by the zinc finger protein ZFP568
May 19, 2017   Science (New York, N.Y.)
Yang P, Wang Y, Hoang D, Tinkham M, Patel A, Sun MA, Wolf G, Baker M, Chien HC, Lai KN, Cheng X, Shen CJ, Macfarlan TS
A placental growth factor is silenced in mouse embryos by the zinc finger protein ZFP568
May 19, 2017
Science (New York, N.Y.)
Insulin-like growth factor 2 (IGF2) is the major fetal growth hormone in mammals. We identify zinc finger protein 568 (ZFP568), a member of the rapidly evolving Kruppel-associated box-zinc finger protein (KRAB-ZFP) family linked primarily to silencing of endogenous retroelements, as a direct repressor of a placental-specific Igf2 transcript (designated Igf2-P0) in mice. Loss of Zfp568, which causes gastrulation failure, or mutation of the ZFP568-binding site at the Igf2-P0 promoter causes inappropriate Igf2-P0 activation. Deletion of Igf2 can completely rescue Zfp568 gastrulation phenotypes through late gestation. Our data highlight the exquisite selectivity with which members of the KRAB-ZFP family repress their targets and identify an additional layer of transcriptional control of a key growth factor regulating fetal and placental development. Copyright © 2017, American Association for the Advancement of Science.
Brg1 chromatin remodeling ATPase balances germ layer patterning by amplifying the transcriptional burst at midblastula transition
May 12, 2017   PLoS Genetics
Wagner G, Singhal N, Nicetto D, Straub T, Kremmer E, Rupp RAW
Brg1 chromatin remodeling ATPase balances germ layer patterning by amplifying the transcriptional burst at midblastula transition
May 12, 2017
PLoS Genetics
Zygotic gene expression programs control cell differentiation in vertebrate development. In Xenopus, these programs are initiated by local induction of regulatory genes through maternal signaling activities in the wake of zygotic genome activation (ZGA) at the midblastula transition (MBT). These programs lay down the vertebrate body plan through gastrulation and neurulation, and are accompanied by massive changes in chromatin structure, which increasingly constrain cellular plasticity. Here we report on developmental functions for Brahma related gene 1 (Brg1), a key component of embyronic SWI/SNF chromatin remodeling complexes. Carefully controlled, global Brg1 protein depletion in X. tropicalis and X. laevis causes embryonic lethality or developmental arrest from gastrulation on. Transcriptome analysis at late blastula, before development becomes arrested, indicates predominantly a role for Brg1 in transcriptional activation of a limited set of genes involved in pattern specification processes and nervous system development. Mosaic analysis by targeted microinjection defines Brg1 as an essential amplifier of gene expression in dorsal (BCNE/Nieuwkoop Center) and ventral (BMP/Vent) signaling centers. Moreover, Brg1 is required and sufficient for initiating axial patterning in cooperation with maternal Wnt signaling. In search for a common denominator of Brg1 impact on development, we have quantitatively filtered global mRNA fluctuations at MBT. The results indicate that Brg1 is predominantly required for genes with the highest burst of transcriptional activity. Since this group contains many key developmental regulators, we propose Brg1 to be responsible for raising their expression above threshold levels in preparation for embryonic patterning.
Sensing oxygen inside and out
May 19, 2017   ELife
Stupnikov MR, Cardoso WV
Sensing oxygen inside and out
May 19, 2017
ELife
Neuroendocrine cells act as oxygen sensors in animals from fish to humans, but the evolutionary origins of these cells are only just becoming clear.
DNA replication timing during development anticipates transcriptional programs and parallels enhancer activation
May 17, 2017   Genome Research
Siefert JC, Georgescu C, Wren JD, Koren A, Sansam CL
DNA replication timing during development anticipates transcriptional programs and parallels enhancer activation
May 17, 2017
Genome Research
In dividing cells, DNA replication occurs in a precise order, but many questions remain regarding the mechanisms of replication timing establishment and regulation. We now have generated genome-wide, high-resolution replication timing maps throughout zebrafish development. Unexpectedly, in the rapid cell cycles preceding the midblastula transition, a defined timing program was present that predicted the initial wave of zygotic transcription. Replication timing was thereafter progressively and continuously remodeled across the majority of the genome, and epigenetic changes involved in enhancer activation frequently paralleled developmental changes in replication timing. Strikingly, the long arm of chromosome 4 underwent a dramatic developmentally regulated switch to late replication during gastrulation, reminiscent of mammalian X chromosome inactivation. This study reveals that replication timing is dynamic and tightly linked to epigenetic and transcriptional changes throughout early zebrafish development. These data provide insight into the regulation and functions of replication timing and will enable further mechanistic studies. Published by Cold Spring Harbor Laboratory Press.
Structure-function Studies in Mouse Embryonic Stem Cells Using Recombinase-mediated Cassette Exchange
May 18, 2017   Journal Of Visualized Experiments : JoVE
Pieters T, Haenebalcke L, Bruneel K, Vandamme N, Hochepied T, van Hengel J, Wirth D, Berx G, Haigh JJ, van Roy F, Goossens S
Structure-function Studies in Mouse Embryonic Stem Cells Using Recombinase-mediated Cassette Exchange
May 18, 2017
Journal Of Visualized Experiments : JoVE
Gene engineering in mouse embryos or embryonic stem cells (mESCs) allows for the study of the function of a given protein. Proteins are the workhorses of the cell and often consist of multiple functional domains, which can be influenced by posttranslational modifications. The depletion of the entire protein in conditional or constitutive knock-out (KO) mice does not take into account this functional diversity and regulation. An mESC line and a derived mouse model, in which a docking site for FLPe recombination-mediated cassette exchange (RMCE) was inserted within the ROSA26 (R26) locus, was previously reported. Here, we report on a structure-function approach that allows for molecular dissection of the different functionalities of a multidomain protein. To this end, RMCE-compatible mice must be crossed with KO mice and then RMCE-compatible KO mESCs must be isolated. Next, a panel of putative rescue constructs can be introduced into the R26 locus via RMCE targeting. The candidate rescue cDNAs can be easily inserted between RMCE sites of the targeting vector using recombination cloning. Next, KO mESCs are transfected with the targeting vector in combination with an FLPe recombinase expression plasmid. RMCE reactivates the promoter-less neomycin-resistance gene in the ROSA26 docking sites and allows for the selection of the correct targeting event. In this way, high targeting efficiencies close to 100% are obtained, allowing for insertion of multiple putative rescue constructs in a semi-high throughput manner. Finally, a multitude of R26-driven rescue constructs can be tested for their ability to rescue the phenotype that was observed in parental KO mESCs. We present a proof-of-principle structure-function study in p120 catenin (p120ctn) KO mESCs using endoderm differentiation in embryoid bodies (EBs) as the phenotypic readout. This approach enables the identification of important domains, putative downstream pathways, and disease-relevant point mutations that underlie KO phenotypes for a given protein.
A new hypothesis for foregut and heart tube formation based on differential growth and actomyosin contraction
May 20, 2017   Development (Cambridge, England)
Hosseini HS, Garcia KE, Taber LA
A new hypothesis for foregut and heart tube formation based on differential growth and actomyosin contraction
May 20, 2017
Development (Cambridge, England)
For decades, it was commonly thought that the bilateral heart fields in the early embryo fold directly toward the midline, where they meet and fuse to create the primitive heart tube. Recent studies have challenged this view, however, suggesting that the heart fields fold diagonally. Since early foregut and heart tube morphogenesis are intimately related, this finding also raises questions concerning the traditional view of foregut formation. Here, we combine experiments on chick embryos with computational modeling to explore a new hypothesis for the physical mechanisms of heart tube and foregut formation. According to our hypothesis, differential anisotropic growth between mesoderm and endoderm drives diagonal folding. Then, active contraction along the anterior intestinal portal generates tension to elongate the foregut and heart tube. We test this hypothesis using biochemical perturbations of cell proliferation and contractility, as well as computational modeling based on nonlinear elasticity theory including growth and contraction. The present results generally support the view that differential growth and actomyosin contraction drive formation of the foregut and heart tube in the early chick embryo. © 2017. Published by The Company of Biologists Ltd.
Interstitial fluid osmolarity modulates the action of differential tissue surface tension in progenitor cell segregation during gastrulation
May 17, 2017   Development (Cambridge, England)
Krens SFG, Veldhuis JH, Barone V, Čapek D, Maître JL, Brodland GW, Heisenberg CP
Interstitial fluid osmolarity modulates the action of differential tissue surface tension in progenitor cell segregation during gastrulation
May 17, 2017
Development (Cambridge, England)
The segregation of different cell types into distinct tissues is a fundamental process in metazoan development. Differences in cell adhesion and cortex tension are commonly thought to drive cell sorting by regulating tissue surface tension (TST). However, the role that differential TST plays in cell segregation within the developing embryo is as yet unclear. Here, we have analyzed the role of differential TST for germ layer progenitor cell segregation during zebrafish gastrulation. Contrary to previous observations that differential TST drives germ layer progenitor cell segregation in vitro, we show that germ layers display indistinguishable TST within the gastrulating embryo, arguing against differential TST driving germ layer progenitor cell segregation in vivo We further show that the osmolarity of the interstitial fluid (IF) is an important factor that influences germ layer TST in vivo, and that lower osmolarity of the IF compared with standard cell culture medium can explain why germ layers display differential TST in culture but not in vivo Finally, we show that directed migration of mesendoderm progenitors is required for germ layer progenitor cell segregation and germ layer formation. © 2017. Published by The Company of Biologists Ltd.
Maternal Torso-Like Coordinates Tissue Folding During Drosophila Gastrulation
May 12, 2017   Genetics
Johnson TK, Moore KA, Whisstock JC, Warr CG
Maternal Torso-Like Coordinates Tissue Folding During Drosophila Gastrulation
May 12, 2017
Genetics
The rapid and orderly folding of epithelial tissue during developmental processes such as gastrulation requires the precise coordination of changes in cell shape. Here, we report that the perforin-like protein Torso-like (Tsl), the key extracellular determinant for Drosophila embryonic terminal patterning, also functions to control epithelial morphogenesis. We find that tsl null mutants display a ventral cuticular hole phenotype that is independent of the loss of terminal structures, and arises as a consequence of mesoderm invagination defects. We show that the holes are caused by uncoordinated constriction of ventral cell apices, resulting in the formation of an incomplete ventral furrow. Consistent with these data, we find that loss of tsl is sensitive to gene dosage of RhoGEF2, a critical mediator of Rho1-dependent ventral cell shape changes during furrow formation, suggesting that Tsl may act in this pathway. In addition, loss of tsl strongly suppressed the effects of ectopic expression of Fog, a secreted protein that promotes apical constriction. Taken together, our data suggests that Tsl controls Rho1-mediated apical constriction via Fog. We therefore propose that Tsl regulates extracellular Fog activity in order to synchronise cell shape changes and coordinate ventral morphogenesis in Drosophila Identifying the Tsl-mediated event that is common to both terminal patterning and morphogenesis will be valuable for our understanding of the extracellular control of developmental signalling by perforin-like proteins. Copyright © 2017, The Genetics Society of America.
RIC8A is essential for the organisation of actin cytoskeleton and cell-matrix interaction
May 20, 2017   Experimental Cell Research
Ruisu K, Meier R, Kask K, Tõnissoo T, Velling T, Pooga M
RIC8A is essential for the organisation of actin cytoskeleton and cell-matrix interaction
May 20, 2017
Experimental Cell Research
RIC8A functions as a chaperone and guanine nucleotide exchange factor for a subset of G protein α subunits. Multiple G protein subunits mediate various signalling events that regulate cell adhesion and migration and the involvement of RIC8A in some of these processes has been demonstrated. We have previously shown that the deficiency of RIC8A causes a failure in mouse gastrulation and neurogenesis - major events in embryogenesis that rely on proper association of cells with the extracellular matrix (ECM) and involve active cell migration. To elaborate on these findings, we used Ric8a-/- mouse embryonic stem cells and Ric8a-deficient mouse embryonic fibroblasts, and found that RIC8A plays an important role in the organisation and remodelling of actin cytoskeleton and cell-ECM association. Ric8a-deficient cells were able to attach to different ECM components, but were unable to spread correctly, and did not form stress fibres or focal adhesion complexes. We also found that the presence of RIC8A is necessary for the activation of β1 integrins and integrin-mediated cell migration. Copyright © 2017 Elsevier Inc. All rights reserved.
Three-dimensional system enabling the maintenance and directed differentiation of pluripotent stem cells under defined conditions
May 16, 2017   Science Advances
Zujur D, Kanke K, Lichtler AC, Hojo H, Chung UI, Ohba S
Three-dimensional system enabling the maintenance and directed differentiation of pluripotent stem cells under defined conditions
May 16, 2017
Science Advances
The development of in vitro models for the maintenance and differentiation of pluripotent stem cells (PSCs) is an active area of stem cell research. The strategies used so far are based mainly on two-dimensional (2D) cultures, in which cellular phenotypes are regulated by soluble factors. We show that a 3D culture system with atelocollagen porous scaffolds can significantly improve the outcome of the current platforms intended for the maintenance and lineage specification of mouse PSCs (mPSCs). Unlike 2D conditions, the 3D conditions maintained the undifferentiated state of mouse embryonic stem cells (mESCs) without exogenous stimulation and also supported endoderm, mesoderm, and ectoderm differentiation of mESCs under serum-free conditions. Moreover, 3D mPSC-derived mesodermal cells showed accelerated osteogenic differentiation, giving rise to functional osteoblast-osteocyte populations within calcified structures. The present strategy offers a 3D platform suitable for the formation of organoids that mimic in vivo organs containing various cell types, and it may be adaptable to the generation of ectoderm-, mesoderm-, and endoderm-derived tissues when combined with appropriate differentiation treatments.
Mouth development
May 17, 2017   Wiley Interdisciplinary Reviews. Developmental Biology
Chen J, Jacox LA, Saldanha F, Sive H
Mouth development
May 17, 2017
Wiley Interdisciplinary Reviews. Developmental Biology
A mouth is present in all animals, and comprises an opening from the outside into the oral cavity and the beginnings of the digestive tract to allow eating. This review focuses on the earliest steps in mouth formation. In the first half, we conclude that the mouth arose once during evolution. In all animals, the mouth forms from ectoderm and endoderm. A direct association of oral ectoderm and digestive endoderm is present even in triploblastic animals, and in chordates, this region is known as the extreme anterior domain (EAD). Further support for a single origin of the mouth is a conserved set of genes that form a 'mouth gene program' including foxA and otx2. In the second half of this review, we discuss steps involved in vertebrate mouth formation, using the frog Xenopus as a model. The vertebrate mouth derives from oral ectoderm from the anterior neural ridge, pharyngeal endoderm and cranial neural crest (NC). Vertebrates form a mouth by breaking through the body covering in a precise sequence including specification of EAD ectoderm and endoderm as well as NC, formation of a 'pre-mouth array,' basement membrane dissolution, stomodeum formation, and buccopharyngeal membrane perforation. In Xenopus, the EAD is also a craniofacial organizer that guides NC, while reciprocally, the NC signals to the EAD to elicit its morphogenesis into a pre-mouth array. Human mouth anomalies are prevalent and are affected by genetic and environmental factors, with understanding guided in part by use of animal models. For further resources related to this article, please visit the WIREs website. © 2017 The Authors. WIREs Developmental Biology published by Wiley Periodicals, Inc.
Modelling asymmetric somitogenesis: deciphering the mechanisms behind species differences
May 16, 2017   Developmental Biology
Vroomans RMA, Tusscher KHWJT
Modelling asymmetric somitogenesis: deciphering the mechanisms behind species differences
May 16, 2017
Developmental Biology
Somitogenesis is one of the major hallmarks of bilateral symmetry in vertebrates. This symmetry is lost when retinoic acid (RA) signalling is inhibited, allowing the left-right determination pathway to influence somitogenesis. In all three studied vertebrate model species, zebrafish, chicken and mouse, the frequency of somite formation becomes asymmetric, with slower gene expression oscillations driving somitogenesis on the right side. Still, intriguingly, the resulting left-right asymmetric phenotypes differ significantly between these model species. While somitogenesis is generally considered as functionally equivalent among different vertebrates, substantial differences exist in the subset of oscillating genes between different vertebrate species. Variation also appears to exist in the way oscillations cease and somite boundaries become patterned. In addition, in absence of RA, the FGF8 gradient thought to constitute the determination wavefront becomes asymmetric in zebrafish and mouse, extending more anteriorly to the right, while remaining symmetric in chicken. Here we use a computational modelling approach to decipher the causes underlying species differences in asymmetric somitogenesis. Specifically, we investigate to what extent differences can be explained from observed differences in FGF asymmetry and whether differences in somite determination dynamics may also be involved. We demonstrate that a simple clock-and-wavefront model incorporating the observed left-right differences in somitogenesis frequency readily reproduces asymmetric somitogenesis in chicken. However, incorporating asymmetry in FGF signalling was insufficient to robustly reproduce mouse or zebrafish asymmetry phenotypes. In order to explain these phenoptypes we needed to extend the basic model, incorporating species-specific details of the somitogenesis determination mechanism. Our results thus demonstrate that a combination of differences in FGF dynamics and somite determination cause species differences in asymmetric somitogenesis. In addition,they highlight the power of using computational models as well as studying left-right asymmetry to obtain more insight in somitogenesis. Copyright © 2017. Published by Elsevier Inc.
Mesenchymal Stem/Stromal Cells in Regenerative Medicine: Past, Present, and Future
May 18, 2017   Cellular Reprogramming
Trohatou O, Roubelakis MG
Mesenchymal Stem/Stromal Cells in Regenerative Medicine: Past, Present, and Future
May 18, 2017
Cellular Reprogramming
The concept of Regenerative Medicine combined with Cell based Therapy and Tissue Engineering represents the fourth pillar of healthcare and provides a promising approach for the treatment of serious diseases. Recently, cell based therapies are focused on the use of mesenchymal stem/stromal cells (MSCs). Human MSCs, that represent a mesoderm derived population of progenitors, are easily expanded in culture. They are capable to differentiate into osteoblasts, chondrocytes, and adipocytes and exhibit the potential to repair or regenerate damaged tissues. The best characterized source of human MSCs to date is the bone marrow; recently, fetal sources, such as amniotic fluid, umbilical cord, amniotic membranes, or placenta, have also attracted increased attention. Thus, MSCs may represent a valuable tool for tissue repair and cell therapeutic applications. To this end, the main focus of this review is to summarize and evaluate the key characteristics, the sources, and the potential use of MSCs in therapeutic approaches and modalities.
The effects of copper oxide nanoparticles on dorsoventral patterning, convergent extension, and neural and cardiac development of zebrafish
May 18, 2017   Aquatic Toxicology (Amsterdam, Netherlands)
Xu J, Zhang Q, Li X, Zhan S, Wang L, Chen D
The effects of copper oxide nanoparticles on dorsoventral patterning, convergent extension, and neural and cardiac development of zebrafish
May 18, 2017
Aquatic Toxicology (Amsterdam, Netherlands)
Currently, nanoparticles are widely used in biomedicine and industry. CuO nanoparticles (CuO-NPs) are versatile materials in our daily life and their toxicity has drawn extensive attention. In this study, we concentrate on the effect of CuO-NPs on early zebrafish development. The results reveal that CuO-NPs can induce abnormal phenotypes of a smaller head and eyes and delayed epiboly. The gene expression pattern shows that CuO-NPs spatially narrow the expression of dorsal genes chordin and goosecoid and alter the expression of dlx3, ntl and hgg which are related to the cell migration of gastrulation. The decreased expression of pax2 and pax6 involved in neural differentiation was accordant with the decreased sizes of neural structures. Cmlc2 expression suggests that CuO-NPs prevented looping of the heart tube during cardiogenesis. Furthermore, quantitative RT-PCR results suggest that the CuO-NPs could increase the canonical Wnt signaling pathway to narrow the expression of chordin and goosecoid in dorsoventral patterning as well as decrease the transcription of Wnt5 and Wnt11 to result in slower, less directed movements and an abnormal cell shape. These findings indicated the CuO-NPs exert developmental toxicity. The present study evaluates the ecological and developmental toxicity, providing warnings about the application of CuO-NPs. Copyright © 2017 Elsevier B.V. All rights reserved.
Why are hematopoietic stem cells so 'sexy'?-on a search for developmental explanation
May 15, 2017   Leukemia
Ratajczak MZ
Why are hematopoietic stem cells so 'sexy'?-on a search for developmental explanation
May 15, 2017
Leukemia
Evidence has accumulated that normal human and murine hematopoietic stem cells express several functional pituitary and gonadal sex hormones and that, in fact, some sex hormones, such as androgens, have been employed for many years to stimulate hematopoiesis in patients with bone marrow aplasia. Interestingly, sex hormone receptors are also expressed by leukemic cell lines and blasts. In this review I will discuss the emerging question of why hematopoietic cells express these receptors. A tempting hypothetical explanation for this phenomenon is that hematopoietic stem cells are related to subpopulation of migrating primordial germ cells. To support of this notion, the anatomical sites of origin of primitive and definitive hematopoiesis during embryonic development are tightly connected with the migratory route of primordial germ cells: from the proximal epiblast to the extraembryonic endoderm at the bottom of the yolk sac and then back to the embryo proper via the primitive streak to the aorta-gonado-mesonephros (AGM) region on the way to the genital ridges. The migration of these cells overlaps with the emergence of primitive hematopoiesis in the blood islands at the bottom of the yolk sac, and definitive hematopoiesis that occurs in hemogenic endothelium in the embryonic dorsal aorta in AGM region.Leukemia accepted article preview online, 15 May 2017. doi:10.1038/leu.2017.148.
Partially compromised specification causes stochastic effects on gut development in C. elegans
May 15, 2017   Developmental Biology
Choi H, Broitman-Maduro G, Maduro MF
Partially compromised specification causes stochastic effects on gut development in C. elegans
May 15, 2017
Developmental Biology
The C. elegans gut descends from the E progenitor cell through a series of stereotyped cell divisions and morphogenetic events. Effects of perturbations of upstream cell specification on downstream organogenesis have not been extensively investigated. Here we have assembled an allelic series of strains that variably compromise specification of E by perturbing the activation of the gut-specifying end-1 and end-3 genes. Using a marker that allows identification of all E descendants regardless of fate, superimposed with markers that identify cells that have adopted a gut fate, we have examined the fate of E lineage descendants among hundreds of embryos. We find that when specification is partially compromised, the E lineage undergoes hyperplasia accompanied by stochastic and variable specification of gut fate among the E descendants. As anticipated by prior work, the activation of the gut differentiation factor elt-2 becomes delayed in these strains, although ultimate protein levels of a translational ELT-2::GFP reporter resemble those of the wild type. By comparing these effects among the various specification mutants, we find that the stronger the defect in specification (i.e. the fewer number of embryos specifying gut), the stronger the defects in the E lineage and delay in activation of elt-2. Despite the changes in the E lineage in these strains, we find that supernumerary E descendants that adopt a gut fate are accommodated into a relatively normal-looking intestine. Hence, upstream perturbation of specification dramatically affects the E lineage, but as long as sufficient descendants adopt a gut fate, organogenesis overcomes these effects to form a relatively normal intestine. Copyright © 2017. Published by Elsevier Inc.
Defective neuronal migration and inhibition of bipolar to multipolar transition of migrating neural cells by Mesoderm-Specific Transcript, Mest, in the developing mouse neocortex
May 14, 2017   Neuroscience
Ji L, Bishayee K, Sadra A, Choi S, Choi W, Moon S, Jho EH, Huh SO
Defective neuronal migration and inhibition of bipolar to multipolar transition of migrating neural cells by Mesoderm-Specific Transcript, Mest, in the developing mouse neocortex
May 14, 2017
Neuroscience
Brain developmental disorders such as lissencephaly can result from faulty neuronal migration and differentiation during the formation of the mammalian neocortex. The cerebral cortex is a modular structure, where developmentally, newborn neurons are generated as a neuro-epithelial sheet and subsequently differentiate, migrate and organize into their final positions in the cerebral cortical plate via a process involving both tangential and radial migration. The specific role of Mest, an imprinted gene, in neuronal migration has not been previously studied. In this work, we reduced expression of Mest with in utero electroporation of neuronal progenitors in the developing embryonic mouse neocortex. Reduction of Mest levels by shRNA significantly reduced the number of neurons migrating to the cortical plate. Also, Mest-knockdown disrupted the transition of bipolar neurons into multipolar neurons migrating out of the sub-ventricular zone region. The migrating neurons also adopted a more tangential migration pattern upon knockdown of the Mest message, losing their potential to attach to radial glia cells, required for radial migration. The differentiation and migration properties of neurons via Wnt-Akt signaling were affected by Mest changes. In addition, miR-335, encoded in a Mest gene intron, was identified as being responsible for blocking the default tangential migration of the neurons. Our results suggest that Mest and its intron product, miR-335, play important roles in neuronal migration with Mest regulating the morphological transition of primary neurons required in the formation of the mammalian neocortex. Copyright © 2017. Published by Elsevier Ltd.
Sea Urchin Embryogenesis as Bioindicators of Marine Pollution in Impact Areas of the Sea of Japan/East Sea and the Sea of Okhotsk
May 21, 2017   Archives Of Environmental Contamination And Toxicology
Lukyanova ON, Zhuravel EV, Chulchekov DN, Mazur AA
Sea Urchin Embryogenesis as Bioindicators of Marine Pollution in Impact Areas of the Sea of Japan/East Sea and the Sea of Okhotsk
May 21, 2017
Archives Of Environmental Contamination And Toxicology
The embryogenesis of the sea urchin sand dollar Scaphechinus mirabilis was used as bioindicators of seawater quality from the impact areas of the Sea of Japan/East Sea (Peter the Great Bay) and the Sea of Okhotsk (northwestern shelf of Sakhalin Island and western shelf of Kamchatka Peninsula). Fertilization membrane formation, first cleavage, blastula formation, gastrulation, and 2-armed and 4-armed pluteus formation have been analyzed and a number of abnormalities were calculated. Number of embryogenesis anomalies in sand dollar larvae exposed to sea water from different stations in Peter the Great Bay corresponds to pollution level at each area. The Sea of Okhotsk is the main fishing area for Russia. Anthropogenic impact on the marine ecosystem is caused by fishing and transport vessels mainly. But two shelf areas are considered as "hot spots" due to oil and gas drilling. Offshore oil exploitation on the northeastern Sakhalin Island has been started and at present time oil is being drill on oil-extracting platforms continuously. Significant reserves of hydrocarbons are prospected on western Kamchatka shelf, and exploitation drilling in this area was intensified in 2014. A higher number of abnormalities at gastrula and pluteus stages (19-36%) were detected for the stations around oil platforms near Sakhalin Island. On the western Kamchatka shelf number of abnormalities was 7-21%. Such anomalies as exogastrula, incomplete development of pairs of arms were not observed at all; only the delay of development was registered. Eggs, embryos, and larvae of sea urchins are the suitable bioindicators of early disturbances caused by marine pollution in impact ecosystems.
ADP-ribosyl cyclases regulate early development of the sea urchin
May 22, 2017   Messenger (Los Angeles, Calif. : Print)
Ramakrishnan L, Uhlinger K, Dale L, Hamdoun A, Patel S
ADP-ribosyl cyclases regulate early development of the sea urchin
May 22, 2017
Messenger (Los Angeles, Calif. : Print)
ADP-ribosyl cyclases are multifunctional enzymes involved in the metabolism of nucleotide derivatives necessary for Ca2+ signalling such as cADPR and NAADP. Although Ca2+ signalling is a critical regulator of early development, little is known of the role of ADP-ribosyl cyclases during embryogenesis. Here we analyze the expression, activity and function of ADP-ribosyl cyclases in the embryo of the sea urchin - a key organism for study of both Ca2+ signalling and embryonic development. ADP-ribosyl cyclase isoforms (SpARC1-4) showed unique changes in expression during early development. These changes were associated with an increase in the ratio of cADPR:NAADP production. Over-expression of SpARC4 (a preferential cyclase) disrupted gastrulation. Our data highlight the importance of ADP-ribosyl cyclases during embryogenesis.
Pancreatic differentiation of induced pluripotent stem cells in activin A-grafted gelatin-poly(lactide-co-glycolide) nanoparticle scaffolds with induction of LY294002 and retinoic acid
May 23, 2017   Materials Science & Engineering. C, Materials For Biological Applications
Kuo YC, Liu YC, Rajesh R
Pancreatic differentiation of induced pluripotent stem cells in activin A-grafted gelatin-poly(lactide-co-glycolide) nanoparticle scaffolds with induction of LY294002 and retinoic acid
May 23, 2017
Materials Science & Engineering. C, Materials For Biological Applications
The differentiation of induced pluripotent stem cells (iPSCs) in biomaterial scaffolds is an emerging area for biomedical applications. This study proposes, for the first time, the production of pancreatic cells from iPSCs in gelatin-poly(lactide-co-glycolide) nanoparticle (PLGA NP) scaffolds. The porosity and swelling ratio of the scaffolds decreased with increases in gelatin and PLGA NP concentrations. The adhesion efficiency of iPSCs in gelatin-PLGA NP scaffolds was found to be higher at 6.7% (w/w) PLGA NP. A 3-step induction of iPSCs was used to differentiate into pancreatic islet cells using activin A, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), and retinoic acid (RA). The ability of iPSCs to differentiate into pancreatic islet cells in a scaffold was demonstrated by immunofluorescence staining and flow-cytometry analysis. The results indicate that the concentration of activin A, LY294002, and RA plays a decisive role in the differentiation of iPSCs into pancreatic cells. Activin A and LY294002 induce the iPSCs into endoderm and RA induces endoderm into islet cells. A maximum insulin secretion by glucose stimulation was obtained with a higher concentration (2μM) of RA. The use of activin A-grafted gelatin-PLGA NP scaffolds induced by LY294002 and RA can be a promising approach to developing pancreatic islet cells from iPSCs. Copyright © 2017 Elsevier B.V. All rights reserved.
Gene expression analysis of bovine embryonic disc, trophoblast and parietal hypoblast at the start of gastrulation
May 23, 2017   Zygote (Cambridge, England)
Pfeffer PL, Smith CS, Maclean P, Berg DK
Gene expression analysis of bovine embryonic disc, trophoblast and parietal hypoblast at the start of gastrulation
May 23, 2017
Zygote (Cambridge, England)
In cattle early gastrulation-stage embryos (Stage 5), four tissues can be discerned: (i) the top layer of the embryonic disc consisting of embryonic ectoderm (EmE); (ii) the bottom layer of the disc consisting of mesoderm, endoderm and visceral hypoblast (MEH); (iii) the trophoblast (TB); and (iv) the parietal hypoblast. We performed microsurgery followed by RNA-seq to analyse the transcriptome of these four tissues as well as a developmentally earlier pre-gastrulation embryonic disc. The cattle EmE transcriptome was similar at Stages 4 and 5, characterised by the OCT4/SOX2/NANOG pluripotency network. Expression of genes associated with primordial germ cells suggest their presence in the EmE tissue at these stages. Anterior visceral hypoblast genes were transcribed in the Stage 4 disc, but no longer by Stage 5. The Stage 5 MEH layer was equally similar to mouse embryonic and extraembryonic visceral endoderm. Our data suggest that the first mesoderm to invaginate in cattle embryos is fated to become extraembryonic. TGFβ, FGF, VEGF, PDGFA, IGF2, IHH and WNT signals and receptors were expressed, however the representative members of the FGF families differed from that seen in equivalent tissues of mouse embryos. The TB transcriptome was unique and differed significantly from that of mice. FGF signalling in the TB may be autocrine with both FGFR2 and FGF2 expressed. Our data revealed a range of potential inter-tissue interactions, highlighted significant differences in early development between mice and cattle and yielded insight into the developmental events occurring at the start of gastrulation.
Moderate ocean warming mitigates, but more extreme warming exacerbates the impacts of zinc from engineered nanoparticles on a marine larva
May 23, 2017   Environmental Pollution (Barking, Essex : 1987)
Mos B, Kaposi KL, Rose AL, Kelaher B, Dworjanyn SA
Moderate ocean warming mitigates, but more extreme warming exacerbates the impacts of zinc from engineered nanoparticles on a marine larva
May 23, 2017
Environmental Pollution (Barking, Essex : 1987)
There is growing concern about the combined effects of multiple human-induced stressors on biodiversity. In particular, there are substantial knowledge gaps about the combined effects of existing stressors (e.g. pollution) and predicted environmental stress from climate change (e.g. ocean warming). We investigated the impacts of ocean warming and engineered nanoparticles (nano-zinc oxide, nZnO) on larvae of a cosmopolitan tropical sea urchin, Tripneustes gratilla. Larval T. gratilla were exposed to all combinations of three temperatures, 25, 27 and 29 °C (current SST and near-future predicted warming of +2 and + 4 °C) and six concentrations of nZnO (0, 0.001, 0.01, 0.1, 1 and 10 mg nZnO·L-1). These stressors had strong interactive effects on fertilization, gastrulation and normal development of 5 day old larvae. High concentrations of nZnO had a negative effect, but this impact was less pronounced for sea urchins reared at their preferred temperature of 27 °C compared to 25 or 29 °C. Larval growth was also impacted by combined stress of elevated temperature and nZnO. Subsequent measurement of the dissolution and aggregation of nZnO particles and the direct effect of Zn2+ ions on larvae, suggest the negative effects of nZnO on larval development and growth were most likely due to Zn2+ ions. Our results demonstrate that marine larvae may be more resilient to stressors at optimal temperatures and highlight the potential for ocean warming to exacerbate the effects of pollution on marine larvae. Copyright © 2017 Elsevier Ltd. All rights reserved.

The link you entered does not seem to be valid

Please make sure the link points to nature.com contains a valid shared_access_token

Downloading PDF to your library...

Uploading PDF...

PDF uploading

Delete tag: