Sample records for dinosaur stem lineage

  1. Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage

    PubMed Central

    Benson, Roger B. J.; Campione, Nicolás E.; Carrano, Matthew T.; Mannion, Philip D.; Sullivan, Corwin; Upchurch, Paul; Evans, David C.

    2014-01-01

    Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614–622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages. PMID:24802911

  2. Matrix Elasticity Directs Stem Cell Lineage Specification

    E-print Network

    Discher, Dennis

    and also for therapeu- tic uses of stem cells. INTRODUCTION Adult stem cells, as part of normalMatrix Elasticity Directs Stem Cell Lineage Specification Adam J. Engler,1,2 Shamik Sen,1,2 H. Lee.06.044 SUMMARY Microenvironments appear important in stem cell lineage specification but can be difficult

  3. Matrix Elasticity Directs Stem Cell Lineage Specification

    Microsoft Academic Search

    Adam J. Engler; Shamik Sen; H. Lee Sweeney; Dennis E. Discher

    2006-01-01

    SUMMARY Microenvironments appear important in stem cell lineage specification but can be difficult to adequately characterize or control with soft tis- sues. Naive mesenchymal stem cells (MSCs) areshownheretospecifylineageandcommitto phenotypes with extreme sensitivity to tissue- level elasticity. Soft matrices that mimic brain are neurogenic, stiffer matricesthat mimicmus- cle are myogenic, and comparatively rigid matrices that mimic collagenous bone prove osteogenic. During

  4. Dinosaurs.

    ERIC Educational Resources Information Center

    Miller, Vicki; Happel, Sue

    Facts, activities, and student worksheets about dinosaurs are presented. General information about dinosaurs (when they lived and what they were like) and fossils (how they are created and what information they can provide) is followed by a worksheet and answer sheet. A timeline of the dinosaur age and a classification chart which divides…

  5. Matrix elasticity directs stem cell lineage specification

    NASA Astrophysics Data System (ADS)

    Discher, Dennis

    2010-03-01

    Adhesion of stem cells - like most cells - is not just a membrane phenomenon. Most tissue cells need to adhere to a ``solid'' for viability, and over the last decade it has become increasingly clear that the physical ``elasticity'' of that solid is literally ``felt'' by cells. Here we show that Mesenchymal Stem Cells (MSCs) specify lineage and commit to phenotypes with extreme sensitivity to the elasticity typical of tissues [1]. In serum only media, soft matrices that mimic brain appear neurogenic, stiffer matrices that mimic muscle are myogenic, and comparatively rigid matrices that mimic collagenous bone prove osteogenic. Inhibition of nonmuscle myosin II activity blocks all elasticity directed lineage specification, which indicates that the cytoskeleton pulls on matrix through adhesive attachments. Results have significant implications for `therapeutic' stem cells and have motivated development of a proteomic-scale method to identify mechano-responsive protein structures [2] as well as deeper physical studies of matrix physics [3] and growth factor pathways [4]. [4pt] [1] A. Engler, et al. Matrix elasticity directs stem cell lineage specification. Cell (2006).[0pt] [2] C.P. Johnson, et al. Forced unfolding of proteins within cells. Science (2007).[0pt] [3] A.E.X. Brown, et al. Multiscale mechanics of fibrin polymer: Gel stretching with protein unfolding and loss of water. Science (2009).[0pt] [4] D.E. Discher, et al. Growth factors, matrices, and forces combine and control stem cells. Science (2009).

  6. Dinosaurs

    NSDL National Science Digital Library

    Ms. Stearns

    2008-10-26

    This project was created to use with a first grade class. Most of the content will be used whole group on the Smartboard. WHOLE GROUP Life Has a History - Interactive slide show about diversity of animals, extinction, etc. Palenontology Portal FUN AND GAMES Build a Beast - Put bones together to make a skeleton of a prehistoric animal Build a Dinosaur - choose body parts and make a dinosaur Exploring Fossils and the Fossil Record Hide a beast - camouflage Dino Dig - Virtual dig for dinosaur bones that includes reconstruction of the skeleton ...

  7. Rewiring mesenchymal stem cell lineage specification by switching the

    E-print Network

    Kilian, Kristopher A.

    of mesenchymal stem cell (MSC) lineage specification. We chose to explore two diverse differentiation outcomesRewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment becomes more specialized through several transitory states1­4 . For instance, mesenchymal stem cells (MSCs

  8. Dinosaur

    NSDL National Science Digital Library

    D.M. Candelora

    2007-12-12

    This is a series of experiments about dinosaurs and paleontology that was designed for use in the second grade. Each activity gives the needed materials, what to do, and what to think about. All are designed so the student uses everyday, inexpensive materials and they reinforce information that has already been taught. The Teacher's Notes provide the purpose of the activity, preparation, and notes.

  9. Researcharticle Molecular Signatures of the Three Stem Cell Lineages in

    E-print Network

    Researcharticle Molecular Signatures of the Three Stem Cell Lineages in Hydra and the Emergence of Stem Cell Function at the Base of Multicellularity Georg Hemmrich,y,1 Konstantin Khalturin,y,1 Anna, Zagreb, Croatia 6 Laboratory for Pluripotent Stem Cell Studies, RIKEN Center for Developmental Biology

  10. Cytoskeleton-based forecasting of stem cell lineage fates

    PubMed Central

    Treiser, Matthew D.; Yang, Eric H.; Gordonov, Simon; Cohen, Daniel M.; Androulakis, Ioannis P.; Kohn, Joachim; Chen, Christopher S.; Moghe, Prabhas V.

    2010-01-01

    Stem cells that adopt distinct lineages cannot be distinguished based on traditional cell shape. This study reports that higher-order variations in cell shape and cytoskeletal organization that occur within hours of stimulation forecast the lineage commitment fates of human mesenchymal stem cells (hMSCs). The unique approach captures numerous early (24 h), quantitative features of actin fluororeporter shapes, intensities, textures, and spatial distributions (collectively termed morphometric descriptors). The large number of descriptors are reduced into “combinations” through which distinct subpopulations of cells featuring unique combinations are identified. We demonstrate that hMSCs cultured on fibronectin-treated glass substrates under environments permissive to bone lineage induction could be readily discerned within the first 24 h from those cultured in basal- or fat-inductive conditions by such cytoskeletal feature groupings. We extend the utility of this approach to forecast osteogenic stem cell lineage fates across a series of synthetic polymeric materials of diverse physicochemical properties. Within the first 24 h following stem cell seeding, we could successfully “profile” the substrate responsiveness prospectively in terms of the degree of bone versus nonbone predisposition. The morphometric methodology also provided insights into how substrates may modulate the pace of osteogenic lineage specification. Cells on glass substrates deficient in fibronectin showed a similar divergence of lineage fates, but delayed beyond 48 h. In summary, this high-content imaging and single cell modeling approach offers a framework to elucidate and manipulate determinants of stem cell behaviors, as well as to screen stem cell lineage modulating materials and environments. PMID:20080726

  11. Generation of the epicardial lineage from human pluripotent stem cells.

    PubMed

    Witty, Alec D; Mihic, Anton; Tam, Roger Y; Fisher, Stephanie A; Mikryukov, Alexander; Shoichet, Molly S; Li, Ren-Ke; Kattman, Steven J; Keller, Gordon

    2014-10-01

    The epicardium supports cardiomyocyte proliferation early in development and provides fibroblasts and vascular smooth muscle cells to the developing heart. The epicardium has been shown to play an important role during tissue remodeling after cardiac injury, making access to this cell lineage necessary for the study of regenerative medicine. Here we describe the generation of epicardial lineage cells from human pluripotent stem cells by stage-specific activation of the BMP and WNT signaling pathways. These cells display morphological characteristics and express markers of the epicardial lineage, including the transcription factors WT1 and TBX18 and the retinoic acid-producing enzyme ALDH1A2. When induced to undergo epithelial-to-mesenchymal transition, the cells give rise to populations that display characteristics of the fibroblast and vascular smooth muscle lineages. These findings identify BMP and WNT as key regulators of the epicardial lineage in vitro and provide a model for investigating epicardial function in human development and disease. PMID:25240927

  12. Differentiation of Neural Lineage Cells from Human Pluripotent Stem Cells

    PubMed Central

    Schwartz, Philip H.; Brick, David J.; Stover, Alexander E.; Loring, Jeanne F.; Müller, Franz Josef

    2008-01-01

    Human pluripotent stem cells have the unique properties of being able to proliferate indefinitely in their undifferentiated state and to differentiate into any somatic cell type. These cells are thus posited to be extremely useful for furthering our understanding of both normal and abnormal human development, providing a human cell preparation that can be used to screen for new reagents or therapeutic agents, and generating large numbers of differentiated cells that can be used for transplantation purposes. Critical among the applications for the latter are diseases and injuries of the nervous system, medical approaches to which have been, to date, primarily palliative in nature. Differentiation of human pluripotent stem cells into cells of the neural lineage, therefore, has become a central focus of a number of laboratories. This has resulted in the description in the literature of several dozen methods for neural cell differentiation from human pluripotent stem cells. Among these are methods for the generation of such divergent neural cells as dopaminergic neurons, retinal neurons, ventral motoneurons, and oligodendroglial progenitors. In this review, we attempt to fully describe most of these methods, breaking them down into five basic subdivisions: 1) starting material, 2) induction of loss of pluripotency, 3) neural induction, 4) neural maintenance and expansion, and 5) neuronal/glial differentiation. We also show data supporting the concept that undifferentiated human pluripotent stem cells appear to have an innate neural differentiation potential. In addition, we evaluate data comparing and contrasting neural stem cells differentiated from human pluripotent stem cells with those derived directly from the human brain. PMID:18593611

  13. Slit/Robo signaling regulates cell fate decisions in the intestinal stem cell lineage of Drosophila

    PubMed Central

    Biteau, Benoît; Jasper, Heinrich

    2014-01-01

    To maintain tissue homeostasis, cell fate decisions within stem cell lineages have to respond to the needs of the tissue. This coordination of lineage choices with regenerative demand remains poorly characterized. Here we identify a signal from enteroendocrine cells (EEs) that controls lineage specification in the Drosophila intestine. We find that EEs secrete Slit, a ligand for the Robo2 receptor in stem cells (ISCs) that limits ISC commitment to the endocrine lineage, establishing negative feedback control of EE regeneration. We further show that this lineage decision is made within ISCs and requires induction of the transcription factor Prospero in ISCs. Our work identifies a new function for the conserved Slit/Robo pathway in the regulation of adult stem cells, establishing negative feedback control of ISC lineage specification as a critical strategy to preserve tissue homeostasis. Our results further amend the current understanding of cell fate commitment within the Drosophila ISC lineage. PMID:24931602

  14. HO-1 expression increases mesenchymal stem cell-derived osteoblasts but decreases adipocyte lineage

    E-print Network

    Abraham, Nader G.

    HO-1 expression increases mesenchymal stem cell-derived osteoblasts but decreases adipocyte lineage: Diabetes Osteoporosis Osteoblasts BMP2 Human bone marrow mesenchymal stem cells (MSC) are pleiotropic cellsRNA decreased HO-1 expression but increased adipocyte stem cell differentiation and the adipogenesis marker

  15. Human amniotic fluid stem cell differentiation along smooth muscle lineage.

    PubMed

    Ghionzoli, Marco; Repele, Andrea; Sartiani, Laura; Costanzi, Giulia; Parenti, Astrid; Spinelli, Valentina; David, Anna L; Garriboli, Massimo; Totonelli, Giorgia; Tian, Jun; Andreadis, Stelios T; Cerbai, Elisabetta; Mugelli, Alessandro; Messineo, Antonio; Pierro, Agostino; Eaton, Simon; De Coppi, Paolo

    2013-12-01

    Functional smooth muscle engineering requires isolation and expansion of smooth muscle cells (SMCs), and this process is particularly challenging for visceral smooth muscle tissue where progenitor cells have not been clearly identified. Herein we showed for the first time that efficient SMCs can be obtained from human amniotic fluid stem cells (hAFSCs). Clonal lines were generated from c-kit(+) hAFSCs. Differentiation toward SM lineage (SMhAFSCs) was obtained using a medium conditioned by PDGF-BB and TGF-?1. Molecular assays revealed higher level of ? smooth muscle actin (?-SMA), desmin, calponin, and smoothelin in SMhAFSCs when compared to hAFSCs. Ultrastructural analysis demonstrated that SMhAFSCs also presented in the cytoplasm increased intermediate filaments, dense bodies, and glycogen deposits like SMCs. SMhAFSC metabolism evaluated via mass spectrometry showed higher glucose oxidation and an enhanced response to mitogenic stimuli in comparison to hAFSCs. Patch clamp of transduced hAFSCs with lentiviral vectors encoding ZsGreen under the control of the ?-SMA promoter was performed demonstrating that SMhAFSCs retained a smooth muscle cell-like electrophysiological fingerprint. Eventually SMhAFSCs contractility was evident both at single cell level and on a collagen gel. In conclusion, we showed here that hAFSCs under selective culture conditions are able to give rise to functional SMCs. PMID:23995291

  16. Human mesenchymal stem cells from adipose tissue: Differentiation into hepatic lineage

    Microsoft Academic Search

    R. Taléns-Visconti; A. Bonora; R. Jover; V. Mirabet; F. Carbonell; J. V. Castell; M. J. Gómez-Lechón

    2007-01-01

    Adipose tissue represents an accessible source of mesenchymal stem cells (ADSCs), with similar characteristics to bone marrow-derived stem cells. The aim of this work was to investigate the transdifferentiation of ADSCs into hepatic lineage cells in vitro. ADSCs were obtained from human adipose tissue from lipectomy. Cells were grown in medium containing 15% AB human serum. Cultures were serum deprived

  17. Cytoskeleton-based forecasting of stem cell lineage fates

    E-print Network

    Androulakis, Ioannis (Yannis)

    commitment fates of human mesenchymal stem cells (hMSCs). The unique approach captures numerous early (24 h. biomaterials differentiation imaging and modeling stem cells actin organization Stem cells exhibiting) or isolated from niches within adult tissues including the bone marrow. Human mesenchymal stem cells (h

  18. Origins of adult pigmentation: diversity in pigment stem cell lineages and implications for pattern evolution.

    PubMed

    Parichy, David M; Spiewak, Jessica E

    2015-01-01

    Teleosts comprise about half of all vertebrate species and exhibit an extraordinary diversity of adult pigment patterns that function in shoaling, camouflage, and mate choice and have played important roles in speciation. Here, we review studies that have identified several distinct neural crest lineages, with distinct genetic requirements, that give rise to adult pigment cells in fishes. These lineages include post-embryonic, peripheral nerve-associated stem cells that generate black melanophores and iridescent iridophores, cells derived directly from embryonic neural crest cells that generate yellow-orange xanthophores, and bipotent stem cells that generate both melanophores and xanthophores. This complexity in adult chromatophore lineages has implications for our understanding of adult traits, melanoma, and the evolutionary diversification of pigment cell lineages and patterns. PMID:25421288

  19. TECHNICAL ADVANCE Automated tracking of stem cell lineages of Arabidopsis

    E-print Network

    Chowdhury, Amit K. Roy

    niches. The cells of the stem-cell niche are organized into spatial domains of distinct function and cell (SAMs) also referred to as the stem-cell niche, is the most important part of the plant body plan a contin- uous displacement and diversion of cells into a differentia- tion program, the size of stem-cell

  20. Injury induces direct lineage segregation of functionally distinct airway basal stem/progenitor cell subpopulations.

    PubMed

    Pardo-Saganta, Ana; Law, Brandon M; Tata, Purushothama Rao; Villoria, Jorge; Saez, Borja; Mou, Hongmei; Zhao, Rui; Rajagopal, Jayaraj

    2015-02-01

    Following injury, stem cells restore normal tissue architecture by producing the proper number and proportions of differentiated cells. Current models of airway epithelial regeneration propose that distinct cytokeratin 8-expressing progenitor cells, arising from p63(+) basal stem cells, subsequently differentiate into secretory and ciliated cell lineages. We now show that immediately following injury, discrete subpopulations of p63(+) airway basal stem/progenitor cells themselves express Notch pathway components associated with either secretory or ciliated cell fate commitment. One basal cell population displays intracellular Notch2 activation and directly generates secretory cells; the other expresses c-myb and directly yields ciliated cells. Furthermore, disrupting Notch ligand activity within the basal cell population at large disrupts the normal pattern of lineage segregation. These non-cell-autonomous effects demonstrate that effective airway epithelial regeneration requires intercellular communication within the broader basal stem/progenitor cell population. These findings have broad implications for understanding epithelial regeneration and stem cell heterogeneity. PMID:25658372

  1. Telomerase Protects Werner Syndrome Lineage-Specific Stem Cells from Premature Aging

    PubMed Central

    Cheung, Hoi-Hung; Liu, Xiaozhuo; Canterel-Thouennon, Lucile; Li, Lu; Edmonson, Catherine; Rennert, Owen M.

    2014-01-01

    Summary Werner syndrome (WS) patients exhibit premature aging predominantly in mesenchyme-derived tissues, but not in neural lineages, a consequence of telomere dysfunction and accelerated senescence. The cause of this lineage-specific aging remains unknown. Here, we document that reprogramming of WS fibroblasts to pluripotency elongated telomere length and prevented telomere dysfunction. To obtain mechanistic insight into the origin of tissue-specific aging, we differentiated iPSCs to mesenchymal stem cells (MSCs) and neural stem/progenitor cells (NPCs). We observed recurrence of premature senescence associated with accelerated telomere attrition and defective synthesis of the lagging strand telomeres in MSCs, but not in NPCs. We postulate this “aging” discrepancy is regulated by telomerase. Expression of hTERT or p53 knockdown ameliorated the accelerated aging phenotypein MSC, whereas inhibition of telomerase sensitized NPCs to DNA damage. Our findings unveil a role for telomerase in the protection of accelerated aging in a specific lineage of stem cells. PMID:24749076

  2. Cell-Surface Proteomics Identifies Lineage-Specific Markers of Embryo-Derived Stem Cells

    PubMed Central

    Rugg-Gunn, Peter J.; Cox, Brian J.; Lanner, Fredrik; Sharma, Parveen; Ignatchenko, Vladimir; McDonald, Angela C.H.; Garner, Jodi; Gramolini, Anthony O.; Rossant, Janet; Kislinger, Thomas

    2012-01-01

    Summary The advent of reprogramming and its impact on stem cell biology has renewed interest in lineage restriction in mammalian embryos, the source of embryonic (ES), epiblast (EpiSC), trophoblast (TS), and extraembryonic endoderm (XEN) stem cell lineages. Isolation of specific cell types during stem cell differentiation and reprogramming, and also directly from embryos, is a major technical challenge because few cell-surface proteins are known that can distinguish each cell type. We provide a large-scale proteomic resource of cell-surface proteins for the four embryo-derived stem cell lines. We validated 27 antibodies against lineage-specific cell-surface markers, which enabled investigation of specific cell populations during ES-EpiSC reprogramming and ES-to-XEN differentiation. Identified markers also allowed prospective isolation and characterization of viable lineage progenitors from blastocysts by flow cytometry. These results provide a comprehensive stem cell proteomic resource and enable new approaches to interrogate the mechanisms that regulate cell fate specification. PMID:22424930

  3. Expression Profile of Genes Representing Varied Spectra of Cell Lineages in Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

    Microsoft Academic Search

    Young Joon Moon; Myoung Woo Lee; Mal Sook Yang; Sun Kyung Kim; Joon Seong Park; Hugh C. Kim; Hy-Sook Kim; Kwang-Ho Lee; Young-Jin Kim; Jeongeun Choi

    2005-01-01

    Bone marrow (BM) transplantation is a well-established classical treatment for children with malignant haematologic diseases including leukaemia or fatal metabolic diseases [1]. Mononuclear cells (MNCs) in human BM undergo haemopoiesis into distinct cell lineages such as haemopoietic stem cells and mesenchymal stem cells (MSCs), which are capable of differentiating into varied spectra of cell lineages [2, 3]. Human umbilical cord

  4. Tawa hallae - Dinosaur Ancient History

    NSDL National Science Digital Library

    When paleontologists unearthed the ancient dinosaur Tawa hallae, they knew it was different--and remarkably well preserved. What they did not know is that the animal has an intriguing lineage, one that answers questions about the earliest evolution of dinosaurs.

  5. Vertebrate Neural Stem Cell Segmentation, Tracking and Lineaging with Validation and Editing

    PubMed Central

    Winter, Mark; Wait, Eric; Roysam, Badri; Goderie, Susan; Ali, Rania Ahmed Naguib; Kokovay, Erzsebet; Temple, Sally; Cohen, Andrew R.

    2012-01-01

    This protocol and the accompanying software program called LEVER enable quantitative automated analysis of phase contrast time-lapse images of cultured neural stem cells. Images are captured at 5 min. intervals over a period of 5 to 15 days as the cells proliferate and differentiate. LEVER automatically segments, tracks and generates lineage trees of the stem cells from the image sequence. In addition to generating lineage trees capturing the population dynamics of clonal development, LEVER extracts quantitative phenotypic measurements of cell location, shape, movement, and size. When available, the system can include biomolecular markers imaged using fluorescence. It then displays the results to the user for highly efficient inspection and editing to correct any errors in the segmentation, tracking or lineaging. In order to enable high-throughput inspection, LEVER incorporates features for rapid identification of errors, and learning from user-supplied corrections to automatically identify and correct related errors. PMID:22094730

  6. New Insights Into the Cell Lineage of Pancreatic Ductal Adenocarcinoma: Evidence for Tumor Stem Cells in

    E-print Network

    Sander, Maike

    inhibit PanIN formation3,6,7 support the notion that acinar cells play a major role in tumor initiationNew Insights Into the Cell Lineage of Pancreatic Ductal Adenocarcinoma: Evidence for Tumor Stem that Kras-induced transformation of acinar cells into duct-like cells is the primary event in PDA initiation

  7. Transcriptional analysis of early lineage commitment in human embryonic stem cells

    Microsoft Academic Search

    Andrew L Laslett; Sean Grimmond; Brooke Gardiner; Lincon Stamp; Adelia Lin; Susan M Hawes; Sam Wormald; David Nikolic-Paterson; David Haylock; Martin F Pera

    2007-01-01

    BACKGROUND: The mechanisms responsible for the maintenance of pluripotency in human embryonic stem cells, and those that drive their commitment into particular differentiation lineages, are poorly understood. In fact, even our knowledge of the phenotype of hESC is limited, because the immunological and molecular criteria presently used to define this phenotype describe the properties of a heterogeneous population of cells.

  8. Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment

    NASA Astrophysics Data System (ADS)

    Lee, Junmin; Abdeen, Amr A.; Kilian, Kristopher A.

    2014-06-01

    The propensity of stem cells to specify and commit to a particular lineage program is guided by dynamic biophysical and biochemical signals that are temporally regulated. However, most in vitro studies rely on ``snapshots'' of cell state under static conditions. Here we asked whether changing the biophysical aspects of the substrate could modulate the degree of mesenchymal stem cell (MSC) lineage specification. We chose to explore two diverse differentiation outcomes: MSC osteogenesis and trans-differentiation to neuron-like cells. MSCs were cultured on soft (~0.5 kPa) or stiff (~40 kPa) hydrogels followed by transfer to gels of the opposite stiffness. MSCs on soft gels express elevated neurogenesis markers while MSCs on stiff substrates express elevated osteogenesis markers. Transfer of MSCs from soft to stiff or stiff to soft substrates led to a switch in lineage specification. However, MSCs transferred from stiff to soft substrates maintained elevated osteogenesis markers, suggesting a degree of irreversible activation. Transferring MSCs to micropatterned substrates reveal geometric cues that further modulate lineage reversal. Taken together, this study demonstrates that MSCs remain susceptible to the biophysical properties of the extracellular matrix--even after several weeks of culture--and can redirect lineage specification in response to changes in the microenvironment.

  9. Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment

    PubMed Central

    Lee, Junmin; Abdeen, Amr A.; Kilian, Kristopher A.

    2014-01-01

    The propensity of stem cells to specify and commit to a particular lineage program is guided by dynamic biophysical and biochemical signals that are temporally regulated. However, most in vitro studies rely on “snapshots” of cell state under static conditions. Here we asked whether changing the biophysical aspects of the substrate could modulate the degree of mesenchymal stem cell (MSC) lineage specification. We chose to explore two diverse differentiation outcomes: MSC osteogenesis and trans-differentiation to neuron-like cells. MSCs were cultured on soft (~0.5?kPa) or stiff (~40?kPa) hydrogels followed by transfer to gels of the opposite stiffness. MSCs on soft gels express elevated neurogenesis markers while MSCs on stiff substrates express elevated osteogenesis markers. Transfer of MSCs from soft to stiff or stiff to soft substrates led to a switch in lineage specification. However, MSCs transferred from stiff to soft substrates maintained elevated osteogenesis markers, suggesting a degree of irreversible activation. Transferring MSCs to micropatterned substrates reveal geometric cues that further modulate lineage reversal. Taken together, this study demonstrates that MSCs remain susceptible to the biophysical properties of the extracellular matrix—even after several weeks of culture—and can redirect lineage specification in response to changes in the microenvironment. PMID:24898422

  10. Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment.

    PubMed

    Lee, Junmin; Abdeen, Amr A; Kilian, Kristopher A

    2014-01-01

    The propensity of stem cells to specify and commit to a particular lineage program is guided by dynamic biophysical and biochemical signals that are temporally regulated. However, most in vitro studies rely on "snapshots" of cell state under static conditions. Here we asked whether changing the biophysical aspects of the substrate could modulate the degree of mesenchymal stem cell (MSC) lineage specification. We chose to explore two diverse differentiation outcomes: MSC osteogenesis and trans-differentiation to neuron-like cells. MSCs were cultured on soft (~0.5?kPa) or stiff (~40?kPa) hydrogels followed by transfer to gels of the opposite stiffness. MSCs on soft gels express elevated neurogenesis markers while MSCs on stiff substrates express elevated osteogenesis markers. Transfer of MSCs from soft to stiff or stiff to soft substrates led to a switch in lineage specification. However, MSCs transferred from stiff to soft substrates maintained elevated osteogenesis markers, suggesting a degree of irreversible activation. Transferring MSCs to micropatterned substrates reveal geometric cues that further modulate lineage reversal. Taken together, this study demonstrates that MSCs remain susceptible to the biophysical properties of the extracellular matrix--even after several weeks of culture--and can redirect lineage specification in response to changes in the microenvironment. PMID:24898422

  11. A unified hypothesis on the lineage of neural stem cells

    Microsoft Academic Search

    Arturo Alvarez-Buylla; José Manuel García-Verdugo; Anthony D. Tramontin

    2001-01-01

    For many years, it was assumed that neurons and glia in the central nervous system were produced from two distinct precursor pools that diverged early during embryonic development. This theory was partially based on the idea that neurogenesis and gliogenesis occurred during different periods of development, and that neurogenesis ceased perinatally. However, there is now abundant evidence that neural stem

  12. Polycomb Repressive Complex 2 Regulates Lineage Fidelity during Embryonic Stem Cell Differentiation

    PubMed Central

    Thornton, Seraphim R.; Butty, Vincent L.; Levine, Stuart S.; Boyer, Laurie A.

    2014-01-01

    Polycomb Repressive Complex 2 (PRC2) catalyzes histone H3 lysine 27 tri-methylation (H3K27me3), an epigenetic modification associated with gene repression. H3K27me3 is enriched at the promoters of a large cohort of developmental genes in embryonic stem cells (ESCs). Loss of H3K27me3 leads to a failure of ESCs to properly differentiate, making it difficult to determine the precise roles of PRC2 during lineage commitment. Moreover, while studies suggest that PRC2 prevents DNA methylation, how these two epigenetic regulators coordinate to regulate lineage programs is poorly understood. Using several PRC2 mutant ESC lines that maintain varying levels of H3K27me3, we found that partial maintenance of H3K27me3 allowed for proper temporal activation of lineage genes during directed differentiation of ESCs to spinal motor neurons (SMNs). In contrast, genes that function to specify other lineages failed to be repressed in these cells, suggesting that PRC2 is also necessary for lineage fidelity. We also found that loss of H3K27me3 leads to a modest gain in DNA methylation at PRC2 target regions in both ESCs and in SMNs. Our study demonstrates a critical role for PRC2 in safeguarding lineage decisions and in protecting genes against inappropriate DNA methylation. PMID:25333635

  13. Stretch-activated ion channel Piezo1 directs lineage choice in human neural stem cells

    PubMed Central

    Pathak, Medha M.; Nourse, Jamison L.; Tran, Truc; Hwe, Jennifer; Arulmoli, Janahan; Le, Dai Trang T.; Bernardis, Elena; Flanagan, Lisa A.; Tombola, Francesco

    2014-01-01

    Neural stem cells are multipotent cells with the ability to differentiate into neurons, astrocytes, and oligodendrocytes. Lineage specification is strongly sensitive to the mechanical properties of the cellular environment. However, molecular pathways transducing matrix mechanical cues to intracellular signaling pathways linked to lineage specification remain unclear. We found that the mechanically gated ion channel Piezo1 is expressed by brain-derived human neural stem/progenitor cells and is responsible for a mechanically induced ionic current. Piezo1 activity triggered by traction forces elicited influx of Ca2+, a known modulator of differentiation, in a substrate-stiffness–dependent manner. Inhibition of channel activity by the pharmacological inhibitor GsMTx-4 or by siRNA-mediated Piezo1 knockdown suppressed neurogenesis and enhanced astrogenesis. Piezo1 knockdown also reduced the nuclear localization of the mechanoreactive transcriptional coactivator Yes-associated protein. We propose that the mechanically gated ion channel Piezo1 is an important determinant of mechanosensitive lineage choice in neural stem cells and may play similar roles in other multipotent stem cells. PMID:25349416

  14. Robust Estimation of Stem Cell Lineages Using Local Graph Matching Min Liu, Amit K. Roy-Chowdhury

    E-print Network

    Chowdhury, Amit K. Roy

    (SAMs) also referred to as the stem-cell niche, is the most important part of the plant body plan of the growth of the plant stem cell niche. The SAMs of model plant Arabidopsis thaliana consistRobust Estimation of Stem Cell Lineages Using Local Graph Matching Min Liu, Amit K. Roy

  15. Dinosaur Day!

    ERIC Educational Resources Information Center

    Nakamura, Sandra; Baptiste, H. Prentice

    2006-01-01

    In this article, the authors describe how they capitalized on their first-grade students' love of dinosaurs by hosting a fun-filled Dinosaur Day in their classroom. On Dinosaur Day, students rotated through four dinosaur-related learning stations that integrated science content with art, language arts, math, and history in a fun and time-efficient…

  16. MicroRNA Regulation of Cell Lineages in Mouse and Human Embryonic Stem Cells

    Microsoft Academic Search

    Kathryn N. Ivey; Alecia Muth; Joshua Arnold; Frank W. King; Ru-Fang Yeh; Jason E. Fish; Edward C. Hsiao; Robert J. Schwartz; Bruce R. Conklin; Harold S. Bernstein; Deepak Srivastava

    2008-01-01

    SUMMARY Cell fate decisions of pluripotent embryonic stem (ES) cells are dictated by activation and repression of lineage-specific genes. Numerous signaling and transcriptional networks progressively narrow and specify the potential of ES cells. Whether specific microRNAs help refine and limit gene expression and, thereby,could be used to manipulate ES cell dif- ferentiation has largely been unexplored. Here, we show that

  17. Hematopoietic and mesenchymal stem cells: polymeric nanoparticle uptake and lineage differentiation.

    PubMed

    Brüstle, Ivonne; Simmet, Thomas; Nienhaus, Gerd Ulrich; Landfester, Katharina; Mailänder, Volker

    2015-01-01

    The combination of stem cell therapy and nanoparticles promises to enhance the effect of cellular therapies by using nanocarriers as drug delivery devices to guide the further differentiation or homing of stem cells. The impact of nanoparticles on primary cell types remains much more elusive as most groups study the nanoparticle-cell interaction in malignant cell lines. Here, we report on the influence of polymeric nanoparticles on human hematopoietic stem cells (hHSCs) and mesenchymal stem cells (hMSCs). In this study we systematically investigated the influence of polymeric nanoparticles on the cell functionality and differentiation capacity of hHSCs and hMSCs to obtain a deeper knowledge of the interaction of stem cells and nanoparticles. As model systems of nanoparticles, two sets of either bioinert (polystyrene without carboxylic groups on the surface) or biodegradable (PLLA without magnetite) particles were analyzed. Flow cytometry and microscopy analysis showed high uptake rates and no toxicity for all four tested particles in hMSCs and hHSCs. During the differentiation process, the payload of particles per cell decreased. The PLLA-Fe particle showed a significant increase in the IL-8 release in hMSCs but not in hHSCs. We assume that this is due to an increase of free intracellular iron ions but obviously also depends on the cell type. For hHSCs and hMSCs, lineage differentiation into erythrocytes, granulocytes, and megakaryocytes or adipocytes, osteocytes and chondrocytes, was not influenced by the particles when analyzed with lineage specific cluster of differentiation markers. On the other hand qPCR analysis showed significant changes in the expression of some (but not all) investigated lineage markers for both primary cell types. PMID:25821678

  18. Hematopoietic and mesenchymal stem cells: polymeric nanoparticle uptake and lineage differentiation

    PubMed Central

    Brüstle, Ivonne; Simmet, Thomas; Nienhaus, Gerd Ulrich; Landfester, Katharina

    2015-01-01

    Summary The combination of stem cell therapy and nanoparticles promises to enhance the effect of cellular therapies by using nanocarriers as drug delivery devices to guide the further differentiation or homing of stem cells. The impact of nanoparticles on primary cell types remains much more elusive as most groups study the nanoparticle–cell interaction in malignant cell lines. Here, we report on the influence of polymeric nanoparticles on human hematopoietic stem cells (hHSCs) and mesenchymal stem cells (hMSCs). In this study we systematically investigated the influence of polymeric nanoparticles on the cell functionality and differentiation capacity of hHSCs and hMSCs to obtain a deeper knowledge of the interaction of stem cells and nanoparticles. As model systems of nanoparticles, two sets of either bioinert (polystyrene without carboxylic groups on the surface) or biodegradable (PLLA without magnetite) particles were analyzed. Flow cytometry and microscopy analysis showed high uptake rates and no toxicity for all four tested particles in hMSCs and hHSCs. During the differentiation process, the payload of particles per cell decreased. The PLLA–Fe particle showed a significant increase in the IL-8 release in hMSCs but not in hHSCs. We assume that this is due to an increase of free intracellular iron ions but obviously also depends on the cell type. For hHSCs and hMSCs, lineage differentiation into erythrocytes, granulocytes, and megakaryocytes or adipocytes, osteocytes and chondrocytes, was not influenced by the particles when analyzed with lineage specific cluster of differentiation markers. On the other hand qPCR analysis showed significant changes in the expression of some (but not all) investigated lineage markers for both primary cell types. PMID:25821678

  19. Rho GTPases mediate the mechanosensitive lineage commitment of neural stem cells.

    PubMed

    Keung, Albert J; de Juan-Pardo, Elena M; Schaffer, David V; Kumar, Sanjay

    2011-11-01

    Adult neural stem cells (NSCs) play important roles in learning and memory and are negatively impacted by neurological disease. It is known that biochemical and genetic factors regulate self-renewal and differentiation, and it has recently been suggested that mechanical and solid-state cues, such as extracellular matrix (ECM) stiffness, can also regulate the functions of NSCs and other stem cell types. However, relatively little is known of the molecular mechanisms through which stem cells transduce mechanical inputs into fate decisions, the extent to which mechanical inputs instruct fate decisions versus select for or against lineage-committed blast populations, or the in vivo relevance of mechanotransductive signaling molecules in native stem cell niches. Here we demonstrate that ECM-derived mechanical signals act through Rho GTPases to activate the cellular contractility machinery in a key early window during differentiation to regulate NSC lineage commitment. Furthermore, culturing NSCs on increasingly stiff ECMs enhances RhoA and Cdc42 activation, increases NSC stiffness, and suppresses neurogenesis. Likewise, inhibiting RhoA and Cdc42 or downstream regulators of cellular contractility rescues NSCs from stiff matrix- and Rho GTPase-induced neurosuppression. Importantly, Rho GTPase expression and ECM stiffness do not alter proliferation or apoptosis rates indicating that an instructive rather than selective mechanism modulates lineage distributions. Finally, in the adult brain, RhoA activation in hippocampal progenitors suppresses neurogenesis, analogous to its effect in vitro. These results establish Rho GTPase-based mechanotransduction and cellular stiffness as biophysical regulators of NSC fate in vitro and RhoA as an important regulatory protein in the hippocampal stem cell niche. PMID:21956892

  20. Dinosaur Names

    NSDL National Science Digital Library

    In this classroom activity, young students explore the meaning behind dinosaurs' names. The activity opens with background information for teachers about the Greek and Latin root words that are used in dinosaur names. After discussing what they know about dinosaurs, students learn that dinosaur names can describe what the dinosaur looked like, how it might have acted, or where it was found. Working as a class, students use a chart of root words and their meanings to decipher the names of four well-known dinosaurs.

  1. Activation of the amino acid response modulates lineage specification during differentiation of murine embryonic stem cells.

    PubMed

    Shan, Jixiu; Hamazaki, Takashi; Tang, Tiffany A; Terada, Naohiro; Kilberg, Michael S

    2013-08-01

    In somatic cells, a collection of signaling pathways activated by amino acid limitation have been identified and referred to as the amino acid response (AAR). Despite the importance of possible detrimental effects of nutrient limitation during in vitro culture, the AAR has not been investigated in embryonic stem cells (ESC). AAR activation caused the expected increase in transcription factors that mediate specific AAR pathways, as well as the induction of asparagine synthetase, a terminal AAR target gene. Neither AAR activation nor stable knockdown of activating transcription factor (Atf) 4, a transcriptional mediator of the AAR, adversely affected ESC self-renewal or pluripotency. Low-level induction of the AAR over a 12-day period of embryoid body differentiation did alter lineage specification such that the primitive endodermal, visceral endodermal, and endodermal lineages were favored, whereas mesodermal and certain ectodermal lineages were suppressed. Knockdown of Atf4 further enhanced the AAR-induced increase in endodermal formation, suggesting that this phenomenon is mediated by an Atf4-independent mechanism. Collectively, the results indicate that, during differentiation of mouse embryoid bodies in culture, the availability of nutrients, such as amino acids, can influence the formation of specific cell lineages. PMID:23736538

  2. Histone deacetylase 1 and 3 regulate the mesodermal lineage commitment of mouse embryonic stem cells.

    PubMed

    Lv, Weiying; Guo, Xudong; Wang, Guiying; Xu, Yanxin; Kang, Jiuhong

    2014-01-01

    The important role of histone acetylation alteration has become increasingly recognized in mesodermal lineage differentiation and development. However, the contribution of individual histone deacetylases (HDACs) to mesoderm specification remains poorly understood. In this report, we found that trichostatin A (TSA), an inhibitor of histone deacetylase (HDACi), could induce early differentiation of embryonic stem cells (ESCs) and promote mesodermal lineage differentiation. Further analysis showed that the expression levels of HDAC1 and 3 are decreased gradually during ESCs differentiation. Ectopic expression of HDAC1 or 3 significantly inhibited differentiation into the mesodermal lineage. By contrast, loss of either HDAC1 or 3 enhanced the mesodermal differentiation of ESCs. Additionally, we demonstrated that the activity of HDAC1 and 3 is indeed required for the regulation of mesoderm gene expression. Furthermore, HDAC1 and 3 were found to interact physically with the T-box transcription factor T/Bry, which is critical for mesodermal lineage commitment. These findings indicate a key mechanism for the specific role of HDAC1 and 3 in mammalian mesoderm specification. PMID:25412078

  3. Snail1-dependent control of embryonic stem cell pluripotency and lineage commitment

    PubMed Central

    Lin, Yongshun; Li, Xiao-Yan; Willis, Amanda L.; Liu, Chengyu; Chen, Guokai; Weiss, Stephen J.

    2014-01-01

    Embryonic stem cells (ESCs) exhibit the dual properties of self-renewal and pluripotency as well as the ability to undergo differentiation that gives rise to all three germ layers. Wnt family members can both promote ESC maintenance and trigger differentiation while also controlling the expression of Snail1, a zinc-finger transcriptional repressor. Snail1 has been linked to events ranging from cell cycle regulation and cell survival to epithelial–mesenchymal transition (EMT) and gastrulation, but its role in self-renewal, pluripotency or lineage commitment in ESCs remains undefined. Here we demonstrate using isogenic pairs of conditional knockout mouse ESCs, that Snail1 exerts Wnt- and EMT independent control over the stem cell transcriptome without affecting self-renewal or pluripotency-associated functions. By contrast, during ESC differentiation, an endogenous Wnt-mediated burst in Snail1 expression regulates neuroectodermal fate while playing a required role in epiblast stem cell exit and the consequent lineage fate decisions that define mesoderm commitment. PMID:24401905

  4. Tcf3 and Lef1 regulate lineage differentiation of multipotent stem cells in skin

    PubMed Central

    Merrill, Bradley J.; Gat, Uri; DasGupta, Ramanuj; Fuchs, Elaine

    2001-01-01

    In skin, multipotent stem cells generate the keratinocytes of the epidermis, sebaceous gland, and hair follicles. In this paper, we show that Tcf3 and Lef1 control these differentiation lineages. In contrast to Lef1, which requires Wnt signaling and stabilized ?-catenin to express the hair-specific keratin genes and control hair differentiation, Tcf3 can act independently of its ?-catenin interacting domain to suppress features of epidermal terminal differentiation, in which Tcf3 is normally shut off, and promote features of the follicle outer root sheath (ORS) and multipotent stem cells (bulge), the compartments which naturally express Tcf3. These aspects of Tcf3's action are dependent on its DNA binding and Groucho repressor-binding domains. In the absence of its ?-catenin interacting domain, Lef1's behavior (?NLef1) seems to be markedly distinct from that of ?NTcf3. ?NLef1 does not suppress epidermal differentiation and promote ORS/bulge differentiation, but rather suppresses hair differentiation and gives rise to sebocyte differentiation. Taken together, these findings provide powerful evidence that the status of Tcf3/Lef complexes has a key role in controlling cell fate lineages in multipotent skin stem cells. PMID:11445543

  5. Dinosaur Interaction

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore why animals, specifically dinosaurs, live in families. Learners examine Dinosphere scenes (drawing of dinosaurs in groups) and sort the scenes by reasons the animals are living in groups. Then, learners glue together geometric shapes to create dinosaurs interacting in groups and families. This activity is featured on page 26 of the "Dinosphere" unit of study for K-2 learners.

  6. Hair follicle renewal: authentic morphogenesis that depends on a complex progression of stem cell lineages.

    PubMed

    Legué, Emilie; Sequeira, Inęs; Nicolas, Jean-François

    2010-02-01

    The hair follicle (HF) grows during the anagen phase from precursors in the matrix that give rise to each differentiated HF layer. Little is known about the lineal relationship between these layer-restricted precursors and HF stem cells. To understand how the HF stem cells regenerate the typical anagen organization, we conducted in vivo clonal analysis of key stages of the HF cycle in mice. Unexpectedly, we found that the pool of HF stem cells contains precursors with both multipotent and restricted contributions. This implies that the lineal relationships between HF stem cells (persisting during telogen) and layer-restricted precursors (in the germinative layer), responsible for HF elongation during anagen, are not stereotyped. Formation of the matrix at each cycle is accompanied by the transient expansion of an intermediary pool of precursors at the origin of the germinative layer and by the progressive restriction of cell dispersion. The regionalization of clonal patterns within the outer HF structure (the outer root sheath) suggests that the position of the precursors might be a crucial factor in determining their fate. The presence of HF stem cells with multipotent contribution and the progressive segregation of HF lineages upon anagen activation indicate that each HF renewal cycle constitutes an authentic morphogenetic process. A comprehensive model was constructed based on the different clonal patterns observed. In this model, the positions of the precursors relative to the dermal papilla together with the progressive restriction of cell dispersion are part of the mechanism that restricts their contribution to the different HF lineages. PMID:20110322

  7. Lessons from the Embryonic Neural Stem Cell Niche for Neural Lineage Differentiation of Pluripotent Stem Cells

    Microsoft Academic Search

    Valeriya Solozobova; Nicolas Wyvekens; Jan Pruszak

    2012-01-01

    Pluripotent stem cells offer an abundant and malleable source for the generation of differentiated cells for transplantation as well as for in vitro screens. Patterning and differentiation protocols have been developed to generate neural progeny from human embryonic or induced pluripo- tent stem cells. However, continued refinement is required to enhance efficiency and to prevent the generation of unwanted cell

  8. Stem cells and lineages of the intestine: a developmental and evolutionary perspective

    PubMed Central

    Takashima, Shigeo; Gold, David; Hartenstein, Volker

    2012-01-01

    The intestine consists of epithelial cells that secrete digestive enzymes and mucus (gland cells), absorb food particles (enterocytes), and produce hormones (endocrine cells). Intestinal cells are rapidly turned over and need to be replaced. In cnidarians, mitosis of differentiated intestinal cells accounts for much of the replacement; in addition, migratory, multipotent stem cells (interstitial cells) contribute to the production of intestinal cells. In other phyla, intestinal cell replacement is solely the function of stem cells entering the gut from the outside (such as in case of the neoblasts of platyhelmints) or intestinal stem cells located within the midgut epithelium (as in both vertebrates or arthropods). We will attempt in the following to review important aspects of midgut stem cells in different animal groups: where are they located, what types of lineages do they produce, and how do they develop. We will start out with a comparative survey of midgut cell types found across the animal kingdom; then briefly look at the specification of these cells during embryonic development; and finally focus on the stem cells that regenerate midgut cells during adult life. In a number of model systems, including mouse, zebrafish and Drosophila, the molecular pathways controlling ISC proliferation and the specification of intestinal cell types are under intensive investigation. We will highlight findings of the recent literature, focusing on aspects that are shared between the different models and that point at evolutionary ancient mechanisms of intestinal cell formation. PMID:23179635

  9. Zoom Dinosaurs

    NSDL National Science Digital Library

    Zoom Dinosaurs is a comprehensive on-line hypertext book about dinosaurs. It is designed for students of all ages and levels of comprehension. An easy-to-use structure allows readers to start at a basic level on each topic, then progress to more advanced information as desired simply by clicking on links. The site contains handouts, dinosaur myths, etymologies, evolution, coloring pages, non-dinosaur creatures, activities, and links for more information. Each dinosaur page contains information on size, anatomy, body features, behavior, life span, diet, intelligence, classification, discovery of its fossils, and a diagram.

  10. Immunohistochemical study of melanocyte-melanocyte stem cell lineage in vitiligo; a clue to interfollicular melanocyte stem cell reservoir.

    PubMed

    Seleit, Iman; Bakry, Ola Ahmed; Abdou, Asmaa Gaber; Dawoud, Noha Mohammed

    2014-05-01

    There has been a long lasting controversy over whether melanocytes (MCs) in vitiligo are actually lost or still present but functionally inactive. We aimed to evaluate the MC cell lineage in follicular and interfollicular vitiliginous epidermis through immunohistochemical localization of Human Melanoma Black-45 (HMB-45) and Tyrosinase Related Protein 2 (TRP2) and to correlate it with clinicopathologic parameters. Using immunohistochemical techniques, skin biopsies from 50 vitiligo patients and 20 age- and gender-matched healthy subjects were examined. Differentiated active MCs were detected in 44% of interfollicular epidermis (IFE) and 46.7% of follicular epidermis (FE) in lesional skin. Melanocyte precursors/stem cells were detected in 54% of IFE and 63.3% of FE in lesional skin. Melanocyte precursors/stem cells of IFE were significantly associated with residual melanin pigment (p?=?0.007) and with absence of angiogenesis (p?=?0.05). HMB-45 percentage of expression in IFE was positively correlated with MC precursors/stem cells percentage in FE (r?=?+0.65, p?stem cells positivity (p?stem cells and the clinical type of vitiligo or its duration. In conclusion, functioning MCs may exist in vitiligo. The presence of MC precursors/stem cells in IFE may provide an additional reservoir needed for repigmentation. PMID:24460782

  11. Efficient endoderm induction from human pluripotent stem cells by logically directing signals controlling lineage bifurcations.

    PubMed

    Loh, Kyle M; Ang, Lay Teng; Zhang, Jingyao; Kumar, Vibhor; Ang, Jasmin; Auyeong, Jun Qiang; Lee, Kian Leong; Choo, Siew Hua; Lim, Christina Y Y; Nichane, Massimo; Tan, Junru; Noghabi, Monireh Soroush; Azzola, Lisa; Ng, Elizabeth S; Durruthy-Durruthy, Jens; Sebastiano, Vittorio; Poellinger, Lorenz; Elefanty, Andrew G; Stanley, Edouard G; Chen, Qingfeng; Prabhakar, Shyam; Weissman, Irving L; Lim, Bing

    2014-02-01

    Human pluripotent stem cell (hPSC) differentiation typically yields heterogeneous populations. Knowledge of signals controlling embryonic lineage bifurcations could efficiently yield desired cell types through exclusion of alternate fates. Therefore, we revisited signals driving induction and anterior-posterior patterning of definitive endoderm to generate a coherent roadmap for endoderm differentiation. With striking temporal dynamics, BMP and Wnt initially specified anterior primitive streak (progenitor to endoderm), yet, 24 hr later, suppressed endoderm and induced mesoderm. At lineage bifurcations, cross-repressive signals separated mutually exclusive fates; TGF-? and BMP/MAPK respectively induced pancreas versus liver from endoderm by suppressing the alternate lineage. We systematically blockaded alternate fates throughout multiple consecutive bifurcations, thereby efficiently differentiating multiple hPSC lines exclusively into endoderm and its derivatives. Comprehensive transcriptional and chromatin mapping of highly pure endodermal populations revealed that endodermal enhancers existed in a surprising diversity of "pre-enhancer" states before activation, reflecting the establishment of a permissive chromatin landscape as a prelude to differentiation. PMID:24412311

  12. Cytokine-regulated GADD45G induces differentiation and lineage selection in hematopoietic stem cells.

    PubMed

    Thalheimer, Frederic B; Wingert, Susanne; De Giacomo, Pangrazio; Haetscher, Nadine; Rehage, Maike; Brill, Boris; Theis, Fabian J; Hennighausen, Lothar; Schroeder, Timm; Rieger, Michael A

    2014-07-01

    The balance of self-renewal and differentiation in long-term repopulating hematopoietic stem cells (LT-HSC) must be strictly controlled to maintain blood homeostasis and to prevent leukemogenesis. Hematopoietic cytokines can induce differentiation in LT-HSCs; however, the molecular mechanism orchestrating this delicate balance requires further elucidation. We identified the tumor suppressor GADD45G as an instructor of LT-HSC differentiation under the control of differentiation-promoting cytokine receptor signaling. GADD45G immediately induces and accelerates differentiation in LT-HSCs and overrides the self-renewal program by specifically activating MAP3K4-mediated MAPK p38. Conversely, the absence of GADD45G enhances the self-renewal potential of LT-HSCs. Videomicroscopy-based tracking of single LT-HSCs revealed that, once GADD45G is expressed, the development of LT-HSCs into lineage-committed progeny occurred within 36 hr and uncovered a selective lineage choice with a severe reduction in megakaryocytic-erythroid cells. Here, we report an unrecognized role of GADD45G as a central molecular linker of extrinsic cytokine differentiation and lineage choice control in hematopoiesis. PMID:25068120

  13. Surface topography enhances differentiation of mesenchymal stem cells towards osteogenic and adipogenic lineages.

    PubMed

    Abagnale, Giulio; Steger, Michael; Nguyen, Vu Hoa; Hersch, Nils; Sechi, Antonio; Joussen, Sylvia; Denecke, Bernd; Merkel, Rudolf; Hoffmann, Bernd; Dreser, Alice; Schnakenberg, Uwe; Gillner, Arnold; Wagner, Wolfgang

    2015-08-01

    Surface topography impacts on cell growth and differentiation, but it is not trivial to generate defined surface structures and to assess the relevance of specific topographic parameters. In this study, we have systematically compared in vitro differentiation of mesenchymal stem cells (MSCs) on a variety of groove/ridge structures. Micro- and nano-patterns were generated in polyimide using reactive ion etching or multi beam laser interference, respectively. These structures affected cell spreading and orientation of human MSCs, which was also reflected in focal adhesions morphology and size. Time-lapse demonstrated directed migration parallel to the nano-patterns. Overall, surface patterns clearly enhanced differentiation of MSCs towards specific lineages: 15 ?m ridges increased adipogenic differentiation whereas 2 ?m ridges enhanced osteogenic differentiation. Notably, nano-patterns with a periodicity of 650 nm increased differentiation towards both osteogenic and adipogenic lineages. However, in absence of differentiation media surface structures did neither induce differentiation, nor lineage-specific gene expression changes. Furthermore, nanostructures did not affect the YAP/TAZ complex, which is activated by substrate stiffness. Our results provide further insight into how structuring of tailored biomaterials and implant interfaces - e.g. by multi beam laser interference in sub-micrometer scale - do not induce differentiation of MSCs per se, but support their directed differentiation. PMID:26026844

  14. The Dinosaur Database

    NSDL National Science Digital Library

    This database contains detailed information on hundreds of dinosaurs and dinosaur related topics. It features a dinosaur dictionary, dinosaur clip art and flex-art, and links to lesson plans and dinosaur experiments for teachers.

  15. Stepwise renal lineage differentiation of mouse embryonic stem cells tracing in vivo development

    SciTech Connect

    Nishikawa, Masaki, E-mail: masakiwestriver@gmail.com [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States) [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States); University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, CA 91343 (United States); Yanagawa, Naomi [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States) [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States); University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, CA 91343 (United States); Kojima, Nobuhiko [Institute of Industrial Science (IIS), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)] [Institute of Industrial Science (IIS), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Yuri, Shunsuke; Hauser, Peter V.; Jo, Oak D.; Yanagawa, Norimoto [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States) [Medical and Research Services, Greater Los Angeles Veterans Affairs Healthcare System at Sepulveda, North Hills, CA (United States); University of California at Los Angeles, David Geffen School of Medicine, Los Angeles, CA 91343 (United States)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer We induced renal lineages from mESCs by following the in vivo developmental cues. Black-Right-Pointing-Pointer We induced nephrogenic intermediate mesoderm by stepwise addition of factors. Black-Right-Pointing-Pointer We induced two types of renal progenitor cells by reciprocal conditioned media. Black-Right-Pointing-Pointer We propose the potential role of CD24 for the enrichment of renal lineage cells. -- Abstract: The in vitro derivation of renal lineage progenitor cells is essential for renal cell therapy and regeneration. Despite extensive studies in the past, a protocol for renal lineage induction from embryonic stem cells remains unestablished. In this study, we aimed to induce renal lineages from mouse embryonic stem cells (mESC) by following in vivo developmental stages, i.e., the induction of mesoderm (Stage I), intermediate mesoderm (Stage II) and renal lineages (Stage III). For stage I induction, in accordance with known signaling pathways involved in mesoderm development in vivo, i.e., Nodal, bone morphogenic proteins (BMPs) and Wnt, we found that the sequential addition of three factors, i.e., Activin-A (A), a surrogate for Nodal signaling, during days 0-2, A plus BMP-4 (4) during days 2-4, and A4 plus lithium (L), a surrogate for Wnt signaling, during days 4-6, was most effective to induce the mesodermal marker, Brachyury. For stage II induction, the addition of retinoic acid (R) in the continuous presence of A4L during days 6-8 was most effective to induce nephrogenic intermediate mesodermal markers, such as Pax2 and Lim1. Under this condition, more than 30% of cells were stained positive for Pax2, and there was a concomitant decrease in the expression of non-mesodermal markers. For stage III induction, in resemblance to the reciprocal induction between ureteric bud (UB) and metanephric mesenchyme (MM) during kidney development, we found that the exposure to conditioned media derived from UB and MM cells was effective in inducing MM and UB markers, respectively. We also observed the emergence and gradual increase of cell populations expressing progenitor cell marker CD24 from Stage I to Stage III. These CD24{sup +} cells correlated with higher levels of expression of Brachyury at stage I, Pax2 and Lim1 at stage II and MM markers, such as WT1 and Cadherin 11, after exposure to UB-conditioned media at stage III. In conclusion, our results show that stepwise induction by tracing in vivo developmental stages was effective to generate renal lineage progenitor cells from mESC, and CD24 may serve as a useful surface marker for renal lineage cells at stage II and MM cells at stage III.

  16. Sequential changes at differentiation gene promoters as they become active in a stem cell lineage

    PubMed Central

    Chen, Xin; Lu, Chenggang; Prado, Jose Rafael Morillo; Eun, Suk Ho; Fuller, Margaret T.

    2011-01-01

    Transcriptional silencing of terminal differentiation genes by the Polycomb group (PcG) machinery is emerging as a key feature of precursor cells in stem cell lineages. How, then, is this epigenetic silencing reversed for proper cellular differentiation? Here, we investigate how the developmental program reverses local PcG action to allow expression of terminal differentiation genes in the Drosophila male germline stem cell (GSC) lineage. We find that the silenced state, set up in precursor cells, is relieved through developmentally regulated sequential events at promoters once cells commit to spermatocyte differentiation. The programmed events include global downregulation of Polycomb repressive complex 2 (PRC2) components, recruitment of hypophosphorylated RNA polymerase II (Pol II) to promoters, as well as the expression and action of testis-specific homologs of TATA-binding protein-associated factors (tTAFs). In addition, action of the testis-specific meiotic arrest complex (tMAC), a tissue-specific version of the MIP/dREAM complex, is required both for recruitment of tTAFs to target differentiation genes and for proper cell type-specific localization of PRC1 components and tTAFs within the spermatocyte nucleolus. Together, the action of the tMAC and tTAF cell type-specific chromatin and transcription machinery leads to loss of Polycomb and release of stalled Pol II from the terminal differentiation gene promoters, allowing robust transcription. PMID:21610025

  17. Synthesized basement membranes direct the differentiation of mouse embryonic stem cells into pancreatic lineages.

    PubMed

    Higuchi, Yuichiro; Shiraki, Nobuaki; Yamane, Keitaro; Qin, Zeng; Mochitate, Katsumi; Araki, Kimi; Senokuchi, Takafumi; Yamagata, Kazuya; Hara, Manami; Kume, Kazuhiko; Kume, Shoen

    2010-08-15

    We previously reported that embryonic stem (ES) cells cultured on M15 cells, a mesoderm-derived supportive cell line, were efficiently differentiated towards an endodermal fate, finally adopting the specific lineages of various digestive organs such as the pancreas and liver. We show here that the endoderm-inducing activity of M15 cells is in part mediated through the extracellular matrices, and that laminin alpha5 is one of the crucial components. In an attempt to establish a feeder-free ES-cell procedure for pancreatic differentiation, we used a synthesized basement membrane (sBM) substratum using an HEK293 cell line stably expressing laminin-511. On the sBM, mouse ES or induced pluripotent stem (iPS) cells sequentially differentiated into the definitive endoderm, pancreatic progenitor cells, and then insulin-expressing pancreatic beta-cells in vitro. Knockdown of ES cells with integrin beta1 (Itgb1) reduces differentiation towards pancreatic cells. Heparan sulfate proteoglycan 2 (HSPG2) knockdown and heparitinase treatment synergistically decreased the number of Pdx1-expressing cells. These findings indicate that components of the basement membrane have an important role in the differentiation of definitive endoderm lineages. This novel procedure will be useful for the study of pancreatic differentiation of ES or iPS cells and the generation of potential sources of surrogate cells for regenerative medicine. PMID:20647375

  18. Dinosaur Illustrations

    NSDL National Science Digital Library

    Are you searching for images of dinosaurs? If so, then set your sights on David Goldman's website of dinosaur illustrations. Mr. Goldman, a dinosaur aficionado, has created a nicely organized site connecting visitors to an impressive online network of dinosaur artwork. The website hosts a diverse and extensive collection of dinosaurs including the Allosaurus, Hadrosaur, Oviraptor, Pteranodon, and over course the iconic Tyrannosaurus Rex. Dinosaur illustrations can be located by alphabetic index, or by using the site's search engine. Illustration listings are accompanied by small, hyperlinked preview images that connect to the illustration's Internet source. The website also links to a collection of Panoramas, prehistoric animal images, and paleontology book reviews appearing in _Prehistoric Times_.

  19. Dinosaur Paleontology

    NSDL National Science Digital Library

    BEGIN:VCARD VERSION:2.1 FN:Mark Stefanski N:Stefanski; Mark ORG:Marin Academy REV:2005-04-14 END:VCARD

    1995-06-30

    Until recently, dinosaurs were looked upon as sluggish, dim-witted beasts dragging their tails in the swamps. With the commercialization of Jurassic Park, students today have a different view of dinosaur life, but what they may not understand is the process used by scientists to revise their interpretation of the fossil record. The purpose of this unit is to have students understand how the scientific method is used to study the life history of dinosaurs. Using readings, video productions, and resources available from museums of paleontology, students are challenged to think of how we can best interpret the fossil record as it pertains to dinosaurs. Students investigate themes in dinosaur evolution, anatomy, physiology, and behavior, as well as ideas regarding the formulation of their own hypotheses pertaining to dinosaur life, and they are further challenged to describe the ways in which they would obtain evidence to support their ideas.

  20. Feathered Dinosaur

    NSDL National Science Digital Library

    This American Museum of Natural History press release, issued in April 2001, announces the discovery of a remarkably well-preserved, 130-million-year-old fossil dinosaur covered from head to tail with downy fluff and primitive feathers. The press release includes details about where the dinosaur was unearthed, and by whom, the significance of the finding, the geologic reasons why the area where this specimen was found has been a treasure trove of fossils and how dinosaurs are related to birds.

  1. Dinosaur Eggs

    NSDL National Science Digital Library

    Carolyn Anderson

    This National Geographic Society (NGS) website takes users behind the scenes of their 1996 article 'The Great Dinosaur Egg Hunt'. The site contains an online egg hunt and a look at fossil researchers as they 'hatch' fossilized dinosaur eggs to reveal the embryos inside. This includes an in-depth look at 3 different dinosaur eggs that have been found, how researchers view the insides of fossilized eggs, the process of embryo modeling, and virtual reality views of hatchlings and embryos.

  2. Nasal ectomesenchymal stem cells: multi-lineage differentiation and transformation effects on fibrin gels.

    PubMed

    Zhang, Zhijian; He, Qinghua; Deng, Wenwen; Chen, Qian; Hu, Xinyuan; Gong, Aihua; Cao, Xia; Yu, Jiangnan; Xu, Ximing

    2015-05-01

    Ectomesenchymal stem cells (EMSCs) are novel adult stem cells derived from the cranial neural crest. However, their stemness and multi-lineage differentiation potential on three-dimensional fibrin gels has not yet been explored. The objective of this study was to investigate induced differentiation of EMSCs on fibrin gels and their remodeling effects on the scaffolds during the induced differentiation process. The results indicated that CD133(+)/nestin(+)/CD44(+) EMSCs were extensively distributed in the lamina propria of the nasal mucosa. The passaged cells could be induced to differentiate to a greater degree into neurons, Schwann cells and osteoblasts on three-dimensional fibrin gels than on two-dimensional glass slides. More importantly, the induced Schwann cells and osteoblasts exerted channelized and calcified remodeling effects, respectively, on the fibrin gels. Thus, these reshaped scaffolds have desirable biological properties, such as good cell adhesion, biocompatibility and guidance over the cell behavior, providing a tissue-committed niche for specific tissue generation. PMID:25725555

  3. Differentiation of Human Induced Pluripotent Stem Cells into a Keratinocyte Lineage

    PubMed Central

    Kogut, Igor; Roop, Dennis R.; Bilousova, Ganna

    2014-01-01

    Direct reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) provides an opportunity to develop novel personalized treatment options for numerous diseases and to advance current approaches for cell-based drug discoveries and disease modeling. The ability to differentiate iPSCs into relevant cell types is an important prerequisite for the successful development of iPSC-based treatment and modeling strategies. Here, we describe a protocol for the efficient differentiation of human iPSCs into functional keratinocytes. The protocol employs treating iPSCs with retinoic acid and bone-morphogenetic protein-4 to induce differentiation toward a keratinocyte lineage, which is then followed by the growth of differentiated iPSCs on collagen type I- and collagen type IV-coated dishes to enrich for iPSC-derived keratinocytes. PMID:24510784

  4. Essential role of PU.1 in maintenance of mixed lineage leukemia-associated leukemic stem cells.

    PubMed

    Aikawa, Yukiko; Yamagata, Kazutsune; Katsumoto, Takuo; Shima, Yutaka; Shino, Mika; Stanley, E Richard; Cleary, Michael L; Akashi, Koichi; Tenen, Daniel G; Kitabayashi, Issay

    2015-03-01

    Acute myeloid leukemia is a clonal malignant disorder derived from a small number of leukemic stem cells (LSCs). Rearrangements of the mixed lineage leukemia (MLL) gene are found in acute myeloid leukemia associated with poor prognosis. The upregulation of Hox genes is critical for LSC induction and maintenance, but is unlikely to support malignancy and the high LSC frequency observed in MLL leukemias. The present study shows that MLL fusion proteins interact with the transcription factor PU.1 to activate the transcription of CSF-1R, which is critical for LSC activity. Acute myeloid leukemia is cured by either deletion of PU.1 or ablation of cells expressing CSF-1R. Kinase inhibitors specific for CSF-1R prolong survival time. These findings indicate that PU.1-mediated upregulation of CSF-1R is a critical effector of MLL leukemogenesis. PMID:25529853

  5. Metakaryotic stem cell lineages in organogenesis of humans and other metazoans

    PubMed Central

    Gostjeva, Elena V; Koledova, Vera; Tomita-Mitchell, Aoy; Mitchell, Michael; Goetsch, Mary A; Varmuza, Susannah; Fomina, Janna N; Darroudi, Firouz

    2009-01-01

    A non-eukaryotic, metakaryotic cell with large, open mouthed, bell shaped nuclei represents an important stem cell lineage in fetal/juvenile organogenesis in humans and rodents. each human bell shaped nucleus contains the diploid human DNA genome as tested by quantitative Feulgen DNA cytometry and fluorescent in situ hybridization with human pan-telomeric, pan-centromeric and chromosome specific probes. From weeks ?5–12 of human gestation the bell shaped nuclei are found in organ anlagen enclosed in sarcomeric tubular syncytia. Within syncytia bell shaped nuclear number increases binomially up to 16 or 32 nuclei; clusters of syncytia are regularly dispersed in organ anlagen. Syncytial bell shaped nuclei demonstrate two forms of symmetrical amitoses, facing or “kissing” bells and “stacking” bells resembling separation of two paper cups. Remarkably, DNA increase and nuclear fission occur coordinately. Importantly, syncytial bell shaped nuclei undergo asymmetrical amitoses creating organ specific ensembles of up to eight distinct closed nuclear forms, a characteristic required of a stem cell lineage. Closed nuclei emerging from bell shaped nuclei are eukaryotic as demonstrated by their subsequent increases by extra-syncytial mitoses populating the parenchyma of growing anlagen. From 9–14 weeks syncytia fragment forming single cells with bell shaped nuclei that continue to display both symmetrical and asymmetrical amitoses. These forms persist in the juvenile period and are specifically observed in bases of colonic crypts. Metakaryotic forms are found in organogenesis of humans, rats, mice and the plant Arabidopsis indicating an evolutionary origin prior to the divergence of plants and animals. PMID:20539738

  6. Stem Cell Derived Extracellular Matrix Enables Survival and Multi Lineage Differentiation within Superporous Hydrogels

    PubMed Central

    Köllmer, Melanie; Keskar, Vandana; Hauk, Thomas G.; Collins, John M.; Russell, Brenda; Gemeinhart, Richard A.

    2012-01-01

    Hydrophilic poly(ethylene glycol) diacrylate (PEGDA) hydrogel surfaces resist protein adsorption and are generally thought to be unsuitable for anchorage dependent cells to adhere. Intriguingly, our previous findings revealed that PEGDA superporous hydrogel scaffolds (SPHs) allow anchorage of bone marrow derived human mesenchymal stem cells (hMSCs) and support their long term survival. Therefore, we hypothesized that the physicochemical characteristics of the scaffold impart properties that could foster cellular responses. We examined if hMSCs alter their microenvironment to allow cell attachment by synthesizing their own extracellular matrix (ECM) proteins. Immunofluorescence staining revealed extensive expression of collagen type I, collagen type IV, laminin and fibronectin within hMSC-seeded SPHs by the end of the third week. Whether cultured in serum-free or serum-supplemented medium, hMSC ECM protein gene expression patterns exhibited no substantial changes. The presence of serum proteins is required for initial anchorage of hMSCs within the SPHs but not for the hMSC survival after 24 hours. In contrast to 2D expansion on tissue culture plastic (TCP), hMSCs cultured within SPHs proliferate similarly in the presence or absence of serum. To test whether hMSCs retain their undifferentiated state within the SPHs, cell-seeded constructs were cultured for 3 weeks in stem cell maintenance medium and the expression of hMSC-specific cell surface markers were evaluated by flow cytometry. CD105, CD90, CD73 and CD44 were present to a similar extent in the SPH and in 2D monolayer culture. We further demonstrated multi lineage potential of hMSCs grown in the PEGDA SPHs whereby differentiation into osteoblasts, chondrocytes and adipocytes could be induced. The present study demonstrates the potential of hMSCs to alter the “blank” PEGDA environment to a milieu conducive to cell growth and multi-lineage differentiation by secreting adhesive ECM proteins within the porous network of the SPH scaffolds. PMID:22404228

  7. Dinosaur Names

    NSDL National Science Digital Library

    Craig Munsart

    In this activity, students will appreciate how descriptive dinosaur names are formed. They will use multiple combining forms added to the suffix "-saurus" (Greek for lizard) to form the name of a "dinosaur" which they will then draw. This activity contains background information, materials, directions, and extension activities.

  8. Digging Dinosaurs

    NSDL National Science Digital Library

    Recent NSF funded expeditions to Antarctica have uncovered new dinosaur finds. This article is a report on the expeditions and on the research tools used to analyze the finds. Theories of the extinction of dinosaurs are reviewed. The site includes links to video Q&A with the paleontologists.

  9. Dinosaur Dig

    NSDL National Science Digital Library

    Teanna Vincent

    2009-11-09

    4th Grade Fossils Unit Your mission is to write a story about a dinosaur that lived and died in Utah. Include in your story what kind of dinosaur your story is about, where it lived, how it lived, what it ate, how it died, and how it became fossilized. Find or draw ...

  10. Dinosaur Homes

    NSDL National Science Digital Library

    OMSI

    2004-01-01

    In this activity about dinosaurs and survival, learners use scrap materials to create a miniature dinosaur habitat that includes a food source, water source, and shelter. This resource includes definitions of key words (habitat, carnivores, herbivores, omnivores, extinct) as well as discussion questions to further learning.

  11. Dinosaur Day!

    NSDL National Science Digital Library

    H. Prentice Baptiste

    2006-01-01

    On Dinosaur Day, first-grade students rotated through four dinosaur-related learning stations that integrated science content with art, language arts, math, and history in a fun and time-efficient manner. The event drew parents, teachers, and students together as they helped each other discuss, write, draw, measure, mix, and record at each learning station.

  12. Dinosaur Tracking.

    ERIC Educational Resources Information Center

    Lockley, Martin

    1984-01-01

    Describes paleontological studies of trace fossils (the impressions that record the animal's activity) such as dinosaur footprints. Discusses the importance of findings to our knowledge of dinosaur social behavior and community structure. Also tracts evolution of behavior from the Upper Triassic through the Upper Cretaceous, building evidence of…

  13. Musashi2 sustains the mixed-lineage leukemia–driven stem cell regulatory program

    PubMed Central

    Park, Sun-Mi; Gönen, Mithat; Vu, Ly; Minuesa, Gerard; Tivnan, Patrick; Barlowe, Trevor S.; Taggart, James; Lu, Yuheng; Deering, Raquel P.; Hacohen, Nir; Figueroa, Maria E.; Paietta, Elisabeth; Fernandez, Hugo F.; Tallman, Martin S.; Melnick, Ari; Levine, Ross; Leslie, Christina; Lengner, Christopher J.; Kharas, Michael G.

    2015-01-01

    Leukemia stem cells (LSCs) are found in most aggressive myeloid diseases and contribute to therapeutic resistance. Leukemia cells exhibit a dysregulated developmental program as the result of genetic and epigenetic alterations. Overexpression of the RNA-binding protein Musashi2 (MSI2) has been previously shown to predict poor survival in leukemia. Here, we demonstrated that conditional deletion of Msi2 in the hematopoietic compartment results in delayed leukemogenesis, reduced disease burden, and a loss of LSC function in a murine leukemia model. Gene expression profiling of these Msi2-deficient animals revealed a loss of the hematopoietic/leukemic stem cell self-renewal program and an increase in the differentiation program. In acute myeloid leukemia patients, the presence of a gene signature that was similar to that observed in Msi2-deficent murine LSCs correlated with improved survival. We determined that MSI2 directly maintains the mixed-lineage leukemia (MLL) self-renewal program by interacting with and retaining efficient translation of Hoxa9, Myc, and Ikzf2 mRNAs. Moreover, depletion of MLL target Ikzf2 in LSCs reduced colony formation, decreased proliferation, and increased apoptosis. Our data provide evidence that MSI2 controls efficient translation of the oncogenic LSC self-renewal program and suggest MSI2 as a potential therapeutic target for myeloid leukemia. PMID:25664853

  14. Proinflammatory Mediators Enhance the Osteogenesis of Human Mesenchymal Stem Cells after Lineage Commitment

    PubMed Central

    Croes, Michiel; Oner, F. Cumhur; Kruyt, Moyo C.; Blokhuis, Taco J.; Bastian, Okan; Dhert, Wouter J. A.; Alblas, Jacqueline

    2015-01-01

    Several inflammatory processes underlie excessive bone formation, including chronic inflammation of the spine, acute infections, or periarticular ossifications after trauma. This suggests that local factors in these conditions have osteogenic properties. Mesenchymal stem cells (MSCs) and their differentiated progeny contribute to bone healing by synthesizing extracellular matrix and inducing mineralization. Due to the variation in experimental designs used in vitro, there is controversy about the osteogenic potential of proinflammatory factors on MSCs. Our goal was to determine the specific conditions allowing the pro-osteogenic effects of distinct inflammatory stimuli. Human bone marrow MSCs were exposed to tumor necrosis factor alpha (TNF-?) and lipopolysaccharide (LPS). Cells were cultured in growth medium or osteogenic differentiation medium. Alternatively, bone morphogenetic protein 2 (BMP-2) was used as osteogenic supplement to simulate the conditions in vivo. Alkaline phosphatase activity and calcium deposition were indicators of osteogenicity. To elucidate lineage commitment-dependent effects, MSCs were pre-differentiated prior treatment. Our results show that TNF-? and LPS do not affect the expression of osteogenic markers by MSCs in the absence of an osteogenic supplement. In osteogenic differentiation medium or together with BMP-2 however, these mediators highly stimulated their alkaline phosphatase activity and subsequent matrix mineralization. In pre-osteoblasts, matrix mineralization was significantly increased by these mediators, but irrespective of the culture conditions. Our study shows that inflammatory factors potently enhance the osteogenic capacity of MSCs. These properties may be harnessed in bone regenerative strategies. Importantly, the commitment of MSCs to the osteogenic lineage greatly enhances their responsiveness to inflammatory signals. PMID:26176237

  15. Mechanical Modulation of Nascent Stem Cell Lineage Commitment in Tissue Engineering Scaffolds

    PubMed Central

    Song, Min Jae; Dean, David; Tate, Melissa L. Knothe

    2013-01-01

    Taking inspiration from tissue morphogenesis in utero, this study tests the concept of using tissue engineering scaffolds as delivery devices to modulate emergent structure-function relationships at early stages of tissue genesis. We report on the use of a combined computational fluid dynamics (CFD) modeling, advanced manufacturing methods, and experimental fluid mechanics (micro-piv and strain mapping) for the prospective design of tissue engineering scaffold geometries that deliver spatially resolved mechanical cues to cells seeded within. When subjected to a constant magnitude global flow regime, the local scaffold geometry dictates the magnitudes of mechanical stresses and strains experienced by a given cell, and in a spatially resolved fashion, similar to patterning during morphogenesis. In addition, early markers of mesenchymal stem cell lineage commitment relate significantly to the local mechanical environment of the cell. Finally, by plotting the range of stress-strain states for all data corresponding to nascent cell lineage commitment (95% CI), we begin to “map the mechanome”, defining stress-strain states most conducive to targeted cell fates. In sum, we provide a library of reference mechanical cues that can be delivered to cells seeded on tissue engineering scaffolds to guide target tissue phenotypes in a temporally and spatially resolved manner. Knowledge of these effects allows for prospective scaffold design optimization using virtual models prior to prototyping and clinical implementation. Finally, this approach enables the development of next generation scaffolds cum delivery devices for genesis of complex tissues with heterogenous properties, e.g., organs, joints or interface tissues such as growth plates. PMID:23660249

  16. Lineage tracing.

    PubMed

    Kretzschmar, Kai; Watt, Fiona M

    2012-01-20

    Lineage tracing is the identification of all progeny of a single cell. Although its origins date back to developmental biology of invertebrates in the 19(th) century, lineage tracing is now an essential tool for studying stem cell properties in adult mammalian tissues. Lineage tracing provides a powerful means of understanding tissue development, homeostasis, and disease, especially when it is combined with experimental manipulation of signals regulating cell-fate decisions. Recently, the combination of inducible recombinases, multicolor reporter constructs, and live-cell imaging has provided unprecedented insights into stem cell biology. Here we discuss the different experimental strategies currently available for lineage tracing, their associated caveats, and new opportunities to integrate lineage tracing with the monitoring of intracellular signaling pathways. PMID:22265400

  17. Organizational metrics of interchromatin speckle factor domains: integrative classifier for stem cell adhesion & lineage signaling.

    PubMed

    Vega, Sebastián L; Dhaliwal, Anandika; Arvind, Varun; Patel, Parth J; Beijer, Nick R M; de Boer, Jan; Murthy, N Sanjeeva; Kohn, Joachim; Moghe, Prabhas V

    2015-04-01

    Stem cell fates on biomaterials are influenced by the complex confluence of microenvironmental cues emanating from soluble growth factors, cell-to-cell contacts, and biomaterial properties. Cell-microenvironment interactions influence the cell fate by initiating a series of outside-in signaling events that traverse from the focal adhesions to the nucleus via the cytoskeleton and modulate the sub-nuclear protein organization and gene expression. Here, we report a novel imaging-based framework that highlights the spatial organization of sub-nuclear proteins, specifically the splicing factor SC-35 in the nucleoplasm, as an integrative marker to distinguish between minute differences of stem cell lineage pathways in response to stimulatory soluble factors, surface topologies, and microscale topographies. This framework involves the high resolution image acquisition of SC-35 domains and imaging-based feature extraction to obtain quantitative nuclear metrics in tandem with machine learning approaches to generate a predictive cell state classification model. The acquired SC-35 metrics led to >90% correct classification of emergent human mesenchymal stem cell (hMSC) phenotypes in populations of hMSCs exposed for merely 3 days to basal, adipogenic, or osteogenic soluble cues, as well as varying levels of dexamethasone-induced alkaline phosphatase (ALP) expression. Early osteogenic cellular responses across a series of surface patterns, fibrous scaffolds, and micropillars were also detected and classified using this imaging-based methodology. Complex cell states resulting from inhibition of RhoGTPase, ?-catenin, and FAK could be classified with >90% sensitivity on the basis of differences in the SC-35 organizational metrics. This indicates that SC-35 organization is sensitively impacted by adhesion-related signaling molecules that regulate osteogenic differentiation. Our results show that diverse microenvironment cues affect different attributes of the SC-35 organizational metrics and lead to distinct emergent organizational patterns. Taken together, these studies demonstrate that the early organization of SC-35 domains could serve as a "fingerprint" of the intracellular mechanotransductive signaling that governs growth factor- and topography-responsive stem cell states. PMID:25765854

  18. Organizational Metrics of Interchromatin Speckle Factor Domains: Integrative Classifier for Stem Cell Adhesion & Lineage Signaling

    PubMed Central

    Vega, Sebastián L.; Dhaliwal, Anandika; Arvind, Varun; Patel, Parth J.; Beijer, Nick R. M.; de Boer, Jan; Murthy, N. Sanjeeva; Kohn, Joachim; Moghe, Prabhas V.

    2015-01-01

    Stem cell fates on biomaterials are influenced by the complex confluence of microenvironmental cues emanating from soluble growth factors, cell-to-cell contacts, and biomaterial properties. Cell-microenvironment interactions influence the cell fate by initiating a series of outside-in signaling events that traverse from the focal adhesions to the nucleus via the cytoskeleton and modulate the sub-nuclear protein organization and gene expression. Here, we report a novel imaging-based framework that highlights the spatial organization of sub-nuclear proteins, specifically the splicing factor SC-35 in the nucleoplasm, as an integrative marker to distinguish between minute differences of stem cell lineage pathways in response to stimulatory soluble factors, surface topologies, and microscale topographies. This framework involves the high resolution image acquisition of SC-35 domains and imaging-based feature extraction to obtain quantitative nuclear metrics in tandem with machine learning approaches to generate a predictive cell state classification model. The acquired SC-35 metrics led to > 90% correct classification of emergent human mesenchymal stem cell (hMSC) phenotypes in populations of hMSCs exposed for merely 3 days to basal, adipogenic, or osteogenic soluble cues, as well as varying levels of dexamethasone-induced alkaline phosphatase (ALP) expression. Early osteogenic cellular responses across a series of surface patterns, fibrous scaffolds, and micropillars were also detected and classified using this imaging-based methodology. Complex cell states resulting from inhibition of RhoGTPase, ?-catenin, and FAK could be classified with > 90% sensitivity on the basis of differences in the SC-35 organizational metrics. This indicates that SC-35 organization is sensitively impacted by adhesion-related signaling molecules that regulate osteogenic differentiation. Our results show that diverse microenvironment cues affect different attributes of the SC-35 organizational metrics and lead to distinct emergent organizational patterns. Taken together, these studies demonstrate that the early organization of SC-35 domains could serve as a “fingerprint” of the intracellular mechanotransductive signaling that governs growth factor- and topography-responsive stem cell states. PMID:25765854

  19. Dinosaur Teeth

    NSDL National Science Digital Library

    In this classroom activity, middle school students learn what kinds of information can be gained by studying teeth. The activity opens with background information for teachers about dinosaur teeth. Working in small groups, students examine their own teeth; hypothesize about how incisors, canine teeth, and molars are used; and test their hypotheses with carrots. The activity concludes with a student worksheet that challenges them to identify the uses of different dinosaur teeth.

  20. Dinosaur Predation

    Microsoft Academic Search

    \\u000a Carnivorous dinosaurs (Theropoda) such as Tyrannosaurus rex, Velociraptor mongoliensis, and Spinosaurus aegyptiacus are among the most popularly known fossil species and (perhaps together with the felid Smilodon and the synapsid Dimetrodon) represent the public’s primary vision of extinct predators. Numerous restorations of theropods engaged in mortal combat\\u000a with each other or with one of the many clades of herbivorous dinosaurs

  1. Facilitating neural stem/progenitor cell niche calibration for neural lineage differentiation by polyelectrolyte multilayer films.

    PubMed

    Lee, I-Chi; Wu, Yu-Chieh

    2014-09-01

    Neural stem/progenitor cells (NSPCs) are a possible candidate for advancing development and lineage control in neural engineering. Differentiated protocols have been developed in this field to generate neural progeny and to establish neural networks. However, continued refinement is required to enhance differentiation specificity and prevent the generation of unwanted cell types. In this study, we fabricated a niche-modulated system to investigate surface effects on NSPC differentiation by the formation of polyelectrolyte multilayer (PEM) films governed by electrostatic interactions of poly-l-glutamine acid as a polyanion and poly-l-lysine as a polycation. The serum- and chemical agent-free system provided a clean and clear platform to observe in isolation the interaction between surface niche and stem cell differentiation. We found that NSPCs were inducible on PEM films of up to eight alternating layers. In addition, neurite outgrowth, neuron percentage, and synaptic function were regulated by layer number and the surface charge of the terminal layer. The average process outgrowth length was over 500?m on PLL/PLGA(n=7.5) only after 3 days of culture. Moreover, the quantity and quality of the differentiated neurons were enhanced as the number of layers increased, especially when the terminal layer was poly-l-lysine. Our results achieve important targets of neural engineering, including long processes, large neural network size, and large amounts of functional neurons. Our methodology for nanoscale control of material deposition can be successfully applied for surface modification, neural niche modulation, and neural engineering applications. PMID:24937134

  2. Single-Cell Gene Expression Profiles Define Self-Renewing, Pluripotent, and Lineage Primed States of Human Pluripotent Stem Cells

    PubMed Central

    Hough, Shelley R.; Thornton, Matthew; Mason, Elizabeth; Mar, Jessica C.; Wells, Christine A.; Pera, Martin F.

    2014-01-01

    Summary Pluripotent stem cells display significant heterogeneity in gene expression, but whether this diversity is an inherent feature of the pluripotent state remains unknown. Single-cell gene expression analysis in cell subsets defined by surface antigen expression revealed that human embryonic stem cell cultures exist as a continuum of cell states, even under defined conditions that drive self-renewal. The majority of the population expressed canonical pluripotency transcription factors and could differentiate into derivatives of all three germ layers. A minority subpopulation of cells displayed high self-renewal capacity, consistently high transcripts for all pluripotency-related genes studied, and no lineage priming. This subpopulation was characterized by its expression of a particular set of intercellular signaling molecules whose genes shared common regulatory features. Our data support a model of an inherently metastable self-renewing population that gives rise to a continuum of intermediate pluripotent states, which ultimately become primed for lineage specification. PMID:24936473

  3. Join the Dinosaur Age

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners rotate through several learning and play stations to explore dinosaurs and paleontologists. At these stations, learners use sand and dinosaur bone replicas to create a dig site and make observations, read several dinosaur books and complete dinosaur puzzles, role play as dinosaur hunters as they explore online dinosaur sites, create a dinosaur romp, listen to dinosaur music, and use clay or play dough to make dinosaurs and dinosaur tracks. This activity is featured on page 9 of the "Dinosphere" unit of study for K-2 learners.

  4. Life cycle and morphology of a cambrian stem-lineage loriciferan.

    PubMed

    Peel, John S; Stein, Martin; Kristensen, Reinhardt Mřbjerg

    2013-01-01

    Cycloneuralians form a rich and diverse element within Cambrian assemblages of exceptionally preserved fossils. Most resemble priapulid worms whereas other Cycloneuralia (Nematoda, Nematomorpha, Kinorhyncha, Loricifera), well known at the present day, have little or no fossil record. First reports of Sirilorica Peel, 2010 from the lower Cambrian Sirius Passet fauna of North Greenland described a tubular lorica covering the abdomen and part of a well developed introvert with a circlet of 6 grasping denticles near the lorica. The introvert is now known to terminate in a narrow mouth tube, while a conical anal field is also developed. Broad muscular bands between the plates in the lorica indicate that it was capable of movement by rhythmic expansion and contraction of the lorica. Sirilorica is regarded as a macrobenthic member of the stem-lineage of the miniaturised, interstitial, present day Loricifera. Like loriciferans, Sirilorica is now known to have grown by moulting. Evidence of the life cycle of Sirilorica is described, including a large post-larval stage and probably an initial larva similar to that of the middle Cambrian fossil Orstenoloricusshergoldii. PMID:23991198

  5. Control of Embryonic Stem Cell Lineage Commitment by Core Promoter Factor, TAF3

    PubMed Central

    Liu, Zhe; Scannell, Devin R.; Eisen, Michael B.; Tjian, Robert

    2011-01-01

    Summary Deciphering the molecular basis of pluripotency is fundamental to our understanding of development and embryonic stem cell function. Here we report that TAF3, a TBP-associated core promoter factor, is highly enriched in ES cells. TAF3 is required for endoderm lineage differentiation and prevents premature specification of neuroectoderm and mesoderm. In addition to its role in the core promoter recognition complex TFIID, genome-wide binding studies reveal that TAF3 localizes to chromosomal regions bound by CTCF and cohesin. Enrichment for TAF3/CTCF/cohesin bound regions distinguishes TAF3-activated from TAF3-repressed genes. Notably, CTCF directly interacts with and recruits TAF3 to promoter distal sites and TAF3-dependent DNA looping is observed between the promoter distal sites and core promoters occupied by TAF3/CTCF/cohesin. Thus, our findings support a new role of TAF3 in mediating long-range chromatin regulatory interactions to safeguard the finely-balanced transcriptional programs that give rise to pluripotency. PMID:21884934

  6. Brain vascular pericytes following ischemia have multipotential stem cell activity to differentiate into neural and vascular lineage cells.

    PubMed

    Nakagomi, Takayuki; Kubo, Shuji; Nakano-Doi, Akiko; Sakuma, Rika; Lu, Shan; Narita, Aya; Kawahara, Maiko; Taguchi, Akihiko; Matsuyama, Tomohiro

    2015-06-01

    Brain vascular pericytes (PCs) are a key component of the blood-brain barrier (BBB)/neurovascular unit, along with neural and endothelial cells. Besides their crucial role in maintaining the BBB, increasing evidence shows that PCs have multipotential stem cell activity. However, their multipotency has not been considered in the pathological brain, such as after an ischemic stroke. Here, we examined whether brain vascular PCs following ischemia (iPCs) have multipotential stem cell activity and differentiate into neural and vascular lineage cells to reconstruct the BBB/neurovascular unit. Using PCs extracted from ischemic regions (iPCs) from mouse brains and human brain PCs cultured under oxygen/glucose deprivation, we show that PCs developed stemness presumably through reprogramming. The iPCs revealed a complex phenotype of angioblasts, in addition to their original mesenchymal properties, and multidifferentiated into cells from both a neural and vascular lineage. These data indicate that under ischemic/hypoxic conditions, PCs can acquire multipotential stem cell activity and can differentiate into major components of the BBB/neurovascular unit. Thus, these findings support the novel concept that iPCs can contribute to both neurogenesis and vasculogenesis at the site of brain injuries. Stem Cells 2015;33:1962-1974. PMID:25694098

  7. Dinosaur Impressions

    NASA Astrophysics Data System (ADS)

    Taquet, Philippe

    1998-09-01

    Perhaps you are a paleontologist or have always wondered what it is like to be one. Or you are fascinated by fossils and like to read about the origins and natural history of dinosaurs. Or maybe you are an avid traveler and reader of travelogues. If you are any of these things, then this book is for you. Originally published in 1994 in French, Dinosaur Impressions is the engaging account of thirty years of travel and paleontological exploration by Philippe Taquet, one of the world's most noted paleontologists. Dr. Taquet takes the reader on a surprisingly far-flung tour ranging from the Provence countryside to the Niger desert, from the Brazilian bush to the Mongolian Steppes, and from the Laos jungle to the Moroccan mountains in search of dinosaur bones and what they have to tell us about a vanished world. With wry humor and lively anecdotes, Dr. Taquet retraces the history of paleontological research, along the way discussing the latest theories of dinosaur existence and extinction. Elegantly translated by Kevin Padian, Dinosaur Impressions provides a unique, thoughtful perspective not often encountered in American- and English-language works. This insightful, first-hand account of an exceptional career is also a travelogue par excellence that will enthrall enthusiasts and general readers alike. Philippe Taquet is the Director of the National Museum of Natural History in Paris and is a member of the French Academy of Sciences. Kevin Padian is a professor in the Department of Integrative Biology and Curator of the Museum of Paleontology at the University of California, Berkeley. He is also the editor of The Beginning of the Age of Dinosaurs (Cambridge, 1986) and The Encyclopedia of Dinosaurs (1997).

  8. Dinosaurs 1: Where Are the Dinosaurs ?

    NSDL National Science Digital Library

    Science Netlinks

    2003-04-15

    This Science NetLinks lesson is the first of a two-part series on dinosaurs. This lesson taps into student curiosity about dinosaurs in order to lead them to consider life forms that no longer exist. A variety of activities are suggested, including viewing online video clips, creating dinosaur puppets, and constructing dinosaur eggs.

  9. Discovering Dinosaurs

    NSDL National Science Digital Library

    Steve Allison-Bunnell

    This Encyclopedia Britannica website highlights the history and changes in thought surrounding dinosaurs since they were discovered. Beginning in the 1820s, this site explores the continued findings which have led to present-day theories regarding what dinosaurs were like, as well as what happened to them. Topics covered include dinosaur anatomy, physiology, characteristics of behavior, and the environments in which they lived. Each topic is discussed in a sequential order. This site contains classroom activities with a teacher's guide to help students explore and understand ideas about these creatures, using this website. The teacher's guide contains details about classroom management and assessment, as well as teaching tips. Links are provided for further information.

  10. Dinosaurs and the Cretaceous Terrestrial Revolution.

    PubMed

    Lloyd, Graeme T; Davis, Katie E; Pisani, Davide; Tarver, James E; Ruta, Marcello; Sakamoto, Manabu; Hone, David W E; Jennings, Rachel; Benton, Michael J

    2008-11-01

    The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125-80 Myr ago, when flowering plants, herbivorous and social insects, squamates, birds and mammals all underwent a rapid expansion. Although an apparent explosion of dinosaur diversity occurred in the mid-Cretaceous, coinciding with the emergence of new groups (e.g. neoceratopsians, ankylosaurid ankylosaurs, hadrosaurids and pachycephalosaurs), results from the first quantitative study of diversification applied to a new supertree of dinosaurs show that this apparent burst in dinosaurian diversity in the last 18 Myr of the Cretaceous is a sampling artefact. Indeed, major diversification shifts occurred largely in the first one-third of the group's history. Despite the appearance of new clades of medium to large herbivores and carnivores later in dinosaur history, these new originations do not correspond to significant diversification shifts. Instead, the overall geometry of the Cretaceous part of the dinosaur tree does not depart from the null hypothesis of an equal rates model of lineage branching. Furthermore, we conclude that dinosaurs did not experience a progressive decline at the end of the Cretaceous, nor was their evolution driven directly by the KTR. PMID:18647715

  11. DNA methylation of the Trip10 promoter accelerates mesenchymal stem cell lineage determination.

    PubMed

    Hsiao, Shu-Huei; Lee, Kuan-Der; Hsu, Chia-Chen; Tseng, Min-Jen; Jin, Victor X; Sun, Wei-Sheng; Hung, Yi-Chen; Yeh, Kun-Tu; Yan, Pearlly S; Lai, Yen-Yu; Sun, H Sunny; Lu, Yen-Jung; Chang, Yu-Sun; Tsai, Shaw-Jenq; Huang, Tim H-M; Leu, Yu-Wei

    2010-09-24

    Epigenetic regulation of gene expression by DNA methylation and histone modification controls cell fate during development and homeostasis in adulthood. Aberrant epigenetic modifications may lead to abnormal development, even diseases. We have found that Trip10 (thyroid hormone receptor interactor 10), an adaptor protein involved in diverse functions, is epigenetically regulated during lineage-specific induction of human bone marrow-derived mesenchymal stem cells (MSCs). To determine whether DNA methylation-induced gene silencing is sufficient to restrict cell fate changes, we applied an invitro method to specifically methylate the promoter of Trip10. Our hypothesis was that the methylation status of the Trip10 promoter in MSCs alters the differentiation preference of MSCs. Transfection of in vitro-methylated Trip10 promoter DNA into MSCs resulted in progressive accumulation of cytosine methylation at the endogenous Trip10 promoter, reduced Trip10 expression, and accelerated MSC-to-neuron and MSC-to-osteocyte differentiation. A two-component EGFP reporter gene system was established to confirm the level of transcriptional silencing and visualize the targeted DNA methylation. EGFP expression induced in the reporter system by targeted Trip10 methylation was reversed by adding 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, confirming that the suppressed Trip10 expression and disrupted MSC differentiation resulted from the in vitro-introduced methylations in the Trip10 promoter. With this targeted DNA methylation and reporter system, we are able to monitor the progression of locus-specific DNA methylation in vivo and correlate such changes with potential functional changes. Using this approach, we have established a new role for Trip10, showing that the level of Trip10 expression is associated with the maintenance and differentiation of MSCs. PMID:20727853

  12. Dinosaur Detectives

    NSDL National Science Digital Library

    This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on the science of paleontology, how scientists have made conclusions about the lives of dinosaurs, and the scientific techniques used for gathering information about dinosaurs. It includes objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

  13. Fighting Dinosaurs

    NSDL National Science Digital Library

    This site will appeal to dinosaur lovers of all ages. It comes from the American Museum of Natural History and serves as a companion to a new exhibit highlighting recent discoveries from Mongolia, including one of the most famous finds ever: a Velociraptor that was apparently buried alive by a sand flow while attacking a Protoceratops. The site features animated recreations of the last moments of these dinosaurs and their fossilized remains, as well as a modest image gallery of some of the other specimens from Mongolia, some of them yet to be named. Beginning Monday May 22, a virtual tour of the exhibit (IPIX plug-in required) will be available.

  14. Dinosaur Paleobiology Geology 331

    E-print Network

    Kammer, Thomas

    Dinosaur Paleobiology Geology 331 Paleontology #12;Dinosaurs are popular with the public #12;Jack Horner, Montana State Univ. #12;Field Work in Montana #12;A dinosaur "drumstick" in its field jacket. #12;Abundant vascular canals in dinosaur bone support the warm- blooded theory #12;Thin section of dinosaur

  15. Convergence of stem cell behaviors and genetic regulation between animals and plants: insights from the Arabidopsis thaliana stomatal lineage.

    PubMed

    Matos, Juliana L; Bergmann, Dominique C

    2014-01-01

    Plants and animals are two successful, but vastly different, forms of complex multicellular life. In the 1600 million years since they shared a common unicellular ancestor, representatives of these kingdoms have had ample time to devise unique strategies for building and maintaining themselves, yet they have both developed self-renewing stem cell populations. Using the cellular behaviors and the genetic control of stomatal lineage of Arabidopsis as a focal point, we find current data suggests convergence of stem cell regulation at developmental and molecular levels. Comparative studies between evolutionary distant groups, therefore, have the power to reveal the logic behind stem cell behaviors and benefit both human regenerative medicine and plant biomass production. PMID:25184043

  16. Reactive astrocytes as neural stem or progenitor cells: In vivo lineage, In vitro potential, and Genome-wide expression analysis.

    PubMed

    Götz, Magdalena; Sirko, Swetlana; Beckers, Johannes; Irmler, Martin

    2015-08-01

    Here, we review the stem cell hallmarks of endogenous neural stem cells (NSCs) during development and in some niches of the adult mammalian brain to then compare these with reactive astrocytes acquiring stem cell hallmarks after traumatic and ischemic brain injury. Notably, even endogenous NSCs including the earliest NSCs, the neuroepithelial cells, generate in most cases only a single type of progeny and self-renew only for a rather short time in vivo. In vitro, however, especially cells cultured under neurosphere conditions reveal a larger potential and long-term self-renewal under the influence of growth factors. This is rather well comparable to reactive astrocytes in the traumatic or ischemic brain some of which acquire neurosphere-forming capacity including multipotency and long-term self-renewal in vitro, while they remain within their astrocyte lineage in vivo. Both reactive astrocytes and endogenous NSCs exhibit stem cell hallmarks largely in vitro, but their lineage differs in vivo. Both populations generate largely a single cell type in vivo, but endogenous NSCs generate neurons and reactive astrocytes remain in the astrocyte lineage. However, at some early postnatal stages or in some brain regions reactive astrocytes can be released from this fate restriction, demonstrating that they can also enact neurogenesis. Thus, reactive astrocytes and NSCs share many characteristic hallmarks, but also exhibit key differences. This conclusion is further substantiated by genome-wide expression analysis comparing NSCs at different stages with astrocytes from the intact and injured brain parenchyma. GLIA 2015;63:1452-1468. PMID:25965557

  17. Dinosaur Dioramas.

    ERIC Educational Resources Information Center

    Scheinkman, Nancy

    2001-01-01

    Describes an art project for second-grade students where in over five class periods, they create fired clay dinosaur sculptures with dioramas as the background. States that this project, the culminating activity for a sculpture unit, teaches students many art terms and uses of different media. (CMK)

  18. Dinosaur Bodies

    NSDL National Science Digital Library

    This lesson plan asks students to think about the ways in which living animals use their bodies and the ways in which dinosaurs might have used their bodies based on fossil evidence and our best educated guesses. These topics serve as a prelude to studying evolution and adaptation.

  19. Make a Dinosaur

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore the size and scale of dinosaurs. Learners listen to "Dinosaurs, Dinosaurs" by Byron Barton to understand some background information about dinosaurs. Then, learners use pipe cleaners or wire to create skeletal dinosaur models to scale based on reference drawings. As a group, learners then make a bar graph of the sizes of the dinosaurs. This activity is featured on page 19 of the "Dinosphere" unit of study for K-2 learners.

  20. Muscle-derived stem cells isolated as non-adherent population give rise to cardiac, skeletal muscle and neural lineages

    SciTech Connect

    Arsic, Nikola; Mamaeva, Daria; Lamb, Ned J. [Cell Biology Unit, Institute for Human Genetics, CNRS, 141 rue de la Cardonille, Montpellier (France); Fernandez, Anne [Cell Biology Unit, Institute for Human Genetics, CNRS, 141 rue de la Cardonille, Montpellier (France)], E-mail: af@acrux.igh.cnrs.fr

    2008-04-01

    Stem cells with the ability to differentiate in specialized cell types can be extracted from a wide array of adult tissues including skeletal muscle. Here we have analyzed a population of cells isolated from skeletal muscle on the basis of their poor adherence on uncoated or collagen-coated dishes that show multi-lineage differentiation in vitro. When analysed under proliferative conditions, these cells express stem cell surface markers Sca-1 (65%) and Bcrp-1 (80%) but also MyoD (15%), Neuronal {beta} III-tubulin (25%), GFAP (30%) or Nkx2.5 (1%). Although capable of growing as non-attached spheres for months, when given an appropriate matrix, these cells adhere giving rise to skeletal muscle, neuronal and cardiac muscle cell lineages. A similar cell population could not be isolated from either bone marrow or cardiac tissue suggesting their specificity to skeletal muscle. When injected into damaged muscle, these non-adherent muscle-derived cells are retrieved expressing Pax7, in a sublaminar position characterizing satellite cells and participate in forming new myofibers. These data show that a non-adherent stem cell population can be specifically isolated and expanded from skeletal muscle and upon attachment to a matrix spontaneously differentiate into muscle, cardiac and neuronal lineages in vitro. Although competing with resident satellite cells, these cells are shown to significantly contribute to repair of injured muscle in vivo supporting that a similar muscle-derived non-adherent cell population from human muscle may be useful in treatment of neuromuscular disorders.

  1. ESSA1 embryonic stem like cells from gilthead seabream: a new tool to study mesenchymal cell lineage differentiation in fish.

    PubMed

    Parameswaran, Vijayakumar; Laizé, Vincent; Gavaia, Paulo J; Leonor Cancela, M

    2012-10-01

    Embryonic stem (ES) cells are a promising tool for generation of transgenic animals and an ideal experimental model for in vitro studies of embryonic cell development, differentiation and gene manipulation. Here we report the development and initial characterization of a pluripotent embryonic stem like cell line, designated as ESSA1, derived from blastula stage embryos of the gilthead seabream (Sparus aurata, L). ESSA1 cells are cultured in Leibovitz's L-15 medium supplemented with 5% fetal bovine serum and, unlike other ES cells, without a feeder layer. They have a round or polygonal morphology, grow exponentially in culture and form dense colonies. ESSA1 cells also exhibit intense alkaline phosphatase activity, normal karyotype and are positive for stage-specific embryonic antigen-1 (SSEA1) and octamer-binding transcription factor 4 (Oct4) markers for up to 30 passages. Upon treatment with all-trans retinoic acid, ESSA1 cells differentiate into neuron-like, oligodendritic, myocyte and melanocyte cells; they can also form embryoid bodies when seeded in bacteriological plates, a characteristic usually associated with pluripotency. The capacity of ESSA1 cells to differentiate into osteoblastic, chondroblastic or osteoclastic cell lineages and to produce a mineralized extracellular matrix in vitro was demonstrated through histochemical techniques and further confirmed by immunocytochemistry using lineage-specific markers. Furthermore, ESSA1 cells can be used to produce chimera, where they contribute to the development of a variety of tissues including the trunk and gut of zebrafish embryos and fry. Thus, ESSA1 cells represent a promising model for investigating bone-lineage cell differentiation in fish and also highlight the potential of piscine stem cell research. PMID:22903186

  2. Dinosaur Flesh and Bones

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore dinosaur skeletons. First, learners listen to "Bones, Bones, Dinosaur Bones" by Byron Barton to learn about the difference between pictures of dinosaurs that have skin and muscle (fleshed-out) and those that show skeletons. Then, learners match pictures of dinosaurs to pictures of the dinosaurs' skeletons. Learners can also explore other animal bones and skeletons online and/or reassemble paper dinosaur skeletons. This activity can also be used to help learners explore scale as they realize that large dinosaurs had large skeletons and small dinosaurs had small skeletons. This activity is featured on page 37 of the "Dinosphere" unit of study for K-2 learners.

  3. Expression Patterns of Cancer-Testis Antigens in Human Embryonic Stem Cells and Their Cell Derivatives Indicate Lineage Tracks

    PubMed Central

    Lifantseva, Nadya; Koltsova, Anna; Krylova, Tatyana; Yakovleva, Tatyana; Poljanskaya, Galina; Gordeeva, Olga

    2011-01-01

    Pluripotent stem cells can differentiate into various lineages but undergo genetic and epigenetic changes during long-term cultivation and, therefore, require regular monitoring. The expression patterns of cancer-testis antigens (CTAs) MAGE-A2, -A3, -A4, -A6, -A8, -B2, and GAGE were examined in undifferentiated human embryonic stem (hES) cells, their differentiated derivatives, teratocarcinoma (hEC) cells, and cancer cell lines of neuroectodermal and mesodermal origin. Undifferentiated hES cells and embryoid body cells expressed MAGE-A3, -A6, -A4, -A8, and GAGEs while later differentiated derivatives expressed only MAGE-A8 or MAGE-A4. Likewise, mouse pluripotent stem cells also express CTAs of Magea but not Mageb family. Despite similarity of the hES and hEC cell expression patterns, MAGE-A2 and MAGE-B2 were detected only in hEC cells but not in hES cells. Moreover, our analysis has shown that CTAs are aberrantly expressed in cancer cell lines and display low tissue specificity. The identification of CTA expression patterns in pluripotent stem cells and their derivatives may be useful for isolation of abnormally CTA-expressing cells to improve the safety of stem-cell based therapy. PMID:21785609

  4. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes

    PubMed Central

    Langer, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W. M.

    2014-01-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U–Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal–vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic–Jurassic boundary.

  5. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes.

    PubMed

    Langer, Max C; Rincón, Ascanio D; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W M

    2014-10-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U-Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal-vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic-Jurassic boundary. PMID:26064540

  6. Effects of dose rates on radiation-induced replenishment of intestinal stem cells determined by Lgr5 lineage tracing.

    PubMed

    Otsuka, Kensuke; Iwasaki, Toshiyasu

    2015-07-01

    An understanding of the dynamics of intestinal Lgr5(+) stem cells is important for elucidating the mechanism of colonic cancer development. We previously established a method for evaluating Lgr5(+) stem cells by tamoxifen-dependent Lgr5-lineage tracing and showed that high-dose-rate radiation stimulated replenishment of colonic stem cells. In this study, we evaluated the effects of low-dose-rate radiation on stem cell maintenance. Tamoxifen (4OHT)-injected Lgr5-EGFP-IRES-Cre(ERT2) × ROSA-LSL-LacZ mice were used, LacZ-labeled colonic crypts were enumerated, and the loss of LacZ(+) crypts under low-dose-rate radiation was estimated. After 4OHT treatment, the number of LacZ-labeled Lgr5(+) stem cells was higher in the colon of infant mice than in adult mice. The percentage of LacZ-labeled crypts in infant mice rapidly decreased after 4OHT treatment. However, the percentage of labeled crypts plateaued at ?2% at 4 weeks post-treatment and remained unchanged for up to 7 months. Thus, it will be advantageous to evaluate the long-term effects of low-dose-rate radiation. Next, we determined the percentages of LacZ-labeled crypts irradiated with 1 Gy administered at different dose rates. As reported in our previous study, mice exposed to high-dose-rate radiation (30 Gy/h) showed a marked replenishment (P = 0.04). However, mice exposed to low-dose-rate radiation (0.003 Gy/h) did not exhibit accelerated stem-cell replenishment (P = 0.47). These findings suggest the percentage of labeled crypts can serve as a useful indicator of the effects of dose rate on the stem cell pool. PMID:25832104

  7. Effects of dose rates on radiation-induced replenishment of intestinal stem cells determined by Lgr5 lineage tracing

    PubMed Central

    Otsuka, Kensuke; Iwasaki, Toshiyasu

    2015-01-01

    An understanding of the dynamics of intestinal Lgr5+ stem cells is important for elucidating the mechanism of colonic cancer development. We previously established a method for evaluating Lgr5+ stem cells by tamoxifen-dependent Lgr5-lineage tracing and showed that high-dose-rate radiation stimulated replenishment of colonic stem cells. In this study, we evaluated the effects of low-dose-rate radiation on stem cell maintenance. Tamoxifen (4OHT)-injected Lgr5-EGFP-IRES-CreERT2 × ROSA-LSL-LacZ mice were used, LacZ-labeled colonic crypts were enumerated, and the loss of LacZ+ crypts under low-dose-rate radiation was estimated. After 4OHT treatment, the number of LacZ-labeled Lgr5+ stem cells was higher in the colon of infant mice than in adult mice. The percentage of LacZ-labeled crypts in infant mice rapidly decreased after 4OHT treatment. However, the percentage of labeled crypts plateaued at ?2% at 4 weeks post-treatment and remained unchanged for up to 7 months. Thus, it will be advantageous to evaluate the long-term effects of low-dose-rate radiation. Next, we determined the percentages of LacZ-labeled crypts irradiated with 1 Gy administered at different dose rates. As reported in our previous study, mice exposed to high-dose-rate radiation (30 Gy/h) showed a marked replenishment (P = 0.04). However, mice exposed to low-dose-rate radiation (0.003 Gy/h) did not exhibit accelerated stem-cell replenishment (P = 0.47). These findings suggest the percentage of labeled crypts can serve as a useful indicator of the effects of dose rate on the stem cell pool. PMID:25832104

  8. Dinosaur biomechanics

    PubMed Central

    Alexander, R. McNeill

    2006-01-01

    Biomechanics has made large contributions to dinosaur biology. It has enabled us to estimate both the speeds at which dinosaurs generally moved and the maximum speeds of which they may have been capable. It has told us about the range of postures they could have adopted, for locomotion and for feeding, and about the problems of blood circulation in sauropods with very long necks. It has made it possible to calculate the bite forces of predators such as Tyrannosaurus, and the stresses they imposed on its skull; and to work out the remarkable chewing mechanism of hadrosaurs. It has shown us how some dinosaurs may have produced sounds. It has enabled us to estimate the effectiveness of weapons such as the tail spines of Stegosaurus. In recent years, techniques such as computational tomography and finite element analysis, and advances in computer modelling, have brought new opportunities. Biomechanists should, however, be especially cautious in their work on animals known only as fossils. The lack of living specimens and even soft tissues oblige us to make many assumptions. It is important to be aware of the often wide ranges of uncertainty that result. PMID:16822743

  9. Reprogramming fibroblasts toward cardiomyocytes, neural stem cells and hepatocytes by cell activation and signaling-directed lineage conversion.

    PubMed

    Zhu, Saiyong; Wang, Haixia; Ding, Sheng

    2015-07-01

    Induction of tissue-specific cell types via a conventional transdifferentiation strategy typically uses overexpression of the corresponding lineage-specific transcription factors. Alternatively, somatic cells can be temporarily activated via a common set of reprogramming factors into a transition state, which can then be directed into various cell types via soluble lineage-specific signals, without establishing a pluripotent state. Here, we provide protocols for the generation of cardiomyocytes, neural stem cells and hepatocytes from fibroblasts with such a cell activation (CA) and signaling-directed (SD; CASD) strategy. In these protocols, beating cardiomyocytes can be induced from mouse fibroblasts in 2-5 weeks; expandable neural stem cells and definitive endoderm progenitors can be obtained from human fibroblasts as early as 2.5 weeks; and human definitive endoderm progenitors can be differentiated into functional hepatocytes in 2 weeks. Through further developments, the CASD strategy can serve as a unique avenue for generating diverse functional cell types for biomedical research and therapeutic applications. PMID:26042385

  10. The WNT-controlled transcriptional regulator LBH is required for mammary stem cell expansion and maintenance of the basal lineage.

    PubMed

    Lindley, Linsey E; Curtis, Kevin M; Sanchez-Mejias, Avencia; Rieger, Megan E; Robbins, David J; Briegel, Karoline J

    2015-03-01

    The identification of multipotent mammary stem cells (MaSCs) has provided an explanation for the unique regenerative capacity of the mammary gland throughout adult life. However, it remains unclear what genes maintain MaSCs and control their specification into the two epithelial lineages: luminal and basal. LBH is a novel transcription co-factor in the WNT pathway with hitherto unknown physiological function. LBH is expressed during mammary gland development and aberrantly overexpressed in aggressive 'basal' subtype breast cancers. Here, we have explored the in vivo role of LBH in mammopoiesis. We show that in postnatal mammary epithelia, LBH is predominantly expressed in the Lin(-)CD29(high)CD24(+) basal MaSC population. Upon conditional inactivation of LBH, mice exhibit pronounced delays in mammary tissue expansion during puberty and pregnancy, accompanied by increased luminal differentiation at the expense of basal lineage specification. These defects could be traced to a severe reduction in the frequency and self-renewal/differentiation potential of basal MaSCs. Mechanistically, LBH induces expression of key epithelial stem cell transcription factor ?Np63 to promote a basal MaSC state and repress luminal differentiation genes, mainly that encoding estrogen receptor ? (Esr1/ER?). Collectively, these studies identify LBH as an essential regulator of basal MaSC expansion/maintenance, raising important implications for its potential role in breast cancer pathogenesis. PMID:25655704

  11. What Makes a Dinosaur a Dinosaur?

    NSDL National Science Digital Library

    This activity opens with background information for teachers about dinosaurs. As a class, students compare the stance of lizards and dinosaurs in drawings and try to replicate both reptiles' walks. Students learn that some paleontologists classify birds as dinosaurs, and then work in groups to compare a Tyrannosaurus rex skeleton with pictures of birds.

  12. Lineage-related cytotoxicity and clonogenic profile of 1,4-benzoquinone-exposed hematopoietic stem and progenitor cells.

    PubMed

    Chow, Paik Wah; Abdul Hamid, Zariyantey; Chan, Kok Meng; Inayat-Hussain, Salmaan Hussain; Rajab, Nor Fadilah

    2015-04-01

    Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) are sensitive targets for benzene-induced hematotoxicity and leukemogenesis. The impact of benzene exposure on the complex microenvironment of HSCs and HPCs remains elusive. This study aims to investigate the mechanism linking benzene exposure to targeting HSCs and HPCs using phenotypic and clonogenic analyses. Mouse bone marrow (BM) cells were exposed ex vivo to the benzene metabolite, 1,4-benzoquinone (1,4-BQ), for 24h. Expression of cellular surface antigens for HSC (Sca-1), myeloid (Gr-1, CD11b), and lymphoid (CD45, CD3e) populations were confirmed by flow cytometry. The clonogenicity of cells was studied using the colony-forming unit (CFU) assay for multilineage (CFU-GM and CFU-GEMM) and single-lineage (CFU-E, BFU-E, CFU-G, and CFU-M) progenitors. 1,4-BQ demonstrated concentration-dependent cytotoxicity in mouse BM cells. The percentage of apoptotic cells increased (p < 0.05) following 1,4-BQ exposure. Exposure to 1,4-BQ showed no significant effect on CD3e(+) cells but reduced the total counts of Sca-1(+), CD11b(+), Gr-1(+), and CD45(+) cells at 7 and 12 ?M (p < 0.05). Furthermore, the CFU assay showed reduced (p < 0.05) clonogenicity in 1,4-BQ-treated cells. 1,4-BQ induced CFU-dependent cytotoxicity by significantly inhibiting colony growth for CFU-E, BFU-E, CFU-G, and CFU-M starting at a low concentration of exposure (5?M); whereas for the CFU-GM and CFU-GEMM, the inhibition of colony growth was remarkable only at 7 and 12?M of 1,4-BQ, respectively. Taken together, 1,4-BQ caused lineage-related cytotoxicity in mouse HPCs, demonstrating greater toxicity in single-lineage progenitors than in those of multi-lineage. PMID:25645895

  13. Dinosaur Books for Kids

    NSDL National Science Digital Library

    This dinosaur reference list has 25 kid-friendly books on a range of related topics. The author, publisher, and publication date are given for each title. The list includes illustrated compilations of the wide variety of dinosaurs that once roamed the Earth, accounts of what it's like to go digging for dinosaurs and theories about what killed off the dinosaurs.

  14. TECHNICAL RESPONSE DINOSAUR EVOLUTION

    E-print Network

    Benton, Michael

    TECHNICAL RESPONSE DINOSAUR EVOLUTION Response to Comment on "A Jurassic ornithischian dinosaur ornithischian dinosaur Kulindadromeus as feather-like appendages and alternatively proposes that the compound of >150-million-year-old fossils (1), he fails to explain the marked regionalization across the dinosaur

  15. Differentiation of human umbilical cord blood CD133+ stem cells towards myelo–monocytic lineage

    Microsoft Academic Search

    Katharina Ruzicka; Branka Grskovic; Vladimir Pavlovic; Durdi Qujeq; Alireza Karimi; Mathias M. Mueller

    2004-01-01

    Background: Characterisation of stem cells by flow cytometry, their expansion and differentiation are presently of major interest for cell engineering as the basis of a therapeutic concept for transplantation. Haematopoietic stem cells (HSC) express CD34, the adhesion structure which binds 2L-selectin, CD117, a receptor for stem cell factor (SCF; c-kit ligand), and CD133, a transmembrane protein belonging to the family

  16. Make a Dinosaur Model

    NSDL National Science Digital Library

    2014-04-14

    In this activity, learners explore dinosaur skeletons, anatomy, and locomotion. Learners compare and contrast dinosaur skeletons and drawings. Learners also work in groups to reassemble "pieces" to form dinosaur skeletons. Finally, learners create and pose paper dinosaur models with moveable parts and list different actions or movements the dinosaurs can do including eating, walking, and sleeping. This activity is featured on page 39 of the "Dinosphere" unit of study for K-2 learners.

  17. Steroidogenic Factor-1 (SF-1)-Driven Differentiation of Murine Embryonic Stem (ES) Cells into a Gonadal Lineage

    PubMed Central

    Jadhav, Unmesh

    2011-01-01

    Steroidogenic factor 1 (SF-1) is essential for the development and function of steroidogenic tissues. Stable incorporation of SF-1 into embryonic stem cells (SF-1-ES cells) has been shown to prime the cells for steroidogenesis. When provided with exogenous cholesterol substrate, and after treatment with retinoic acid and cAMP, SF-1-ES cells produce progesterone but do not produce other steroids such as cortisol, estradiol, or testosterone. In this study, we explored culture conditions that optimize SF-1-mediated differentiation of ES cells into defined steroidogenic lineages. When embryoid body formation was used to facilitate cell lineage differentiation, SF-1-ES cells were found to be restricted in their differentiation, with fewer cells entering neuronal pathways and a larger fraction entering the steroidogenic lineage. Among the differentiation protocols tested, leukemia inhibitory factor (LIF) removal, followed by prolonged cAMP treatment was most efficacious for inducing steroidogenesis in SF-1-ES cells. In this protocol, a subset of SF-1-ES cells survives after LIF withdrawal, undergoes morphologic differentiation, and recovers proliferative capacity. These cells are characterized by induction of steroidogenic enzyme genes, use of de novo cholesterol, and production of multiple steroids including estradiol and testosterone. Microarray studies identified additional pathways associated with SF-1 mediated differentiation. Using biotinylated SF-1 in chromatin immunoprecipitation assays, SF-1 was shown to bind directly to multiple target genes, with induction of binding to some targets after steroidogenic treatment. These studies indicate that SF-1 expression, followed by LIF removal and treatment with cAMP drives ES cells into a steroidogenic pathway characteristic of gonadal steroid-producing cells. PMID:21610156

  18. Direct Lineage Conversion of Adult Mouse Liver Cells and B Lymphocytes to Neural Stem Cells

    E-print Network

    Cassady, John P.

    Overexpression of transcription factors has been used to directly reprogram somatic cells into a range of other differentiated cell types, including multipotent neural stem cells (NSCs), that can be used to generate neurons ...

  19. Radiolabeling and In Vivo Imaging of Transplanted Renal Lineages Differentiated from Human Embryonic Stem Cells in Fetal Rhesus Monkeys

    PubMed Central

    Tarantal, Alice F.; Lee, C. Chang I.; Batchelder, Cynthia A.; Christensen, Jared E.; Prater, Daniel; Cherry, Simon R.

    2014-01-01

    Purpose The goals of this study were to optimize radiolabeling of renal lineages differentiated from human embryonic stem (hES) cells and use noninvasive imaging (positron emission tomography (PET) and bioluminescence imaging (BLI)) to detect the cells in fetal monkeys post-transplant. Procedures hES cells expressing firefly luciferase (5×106) were radiolabeled with the optimized concentration of 10 ?Ci/ml 64Cu-PTSM then transplanted under ultrasound guidance into early second trimester fetal monkey kidneys. Fetuses were imaged in utero with PET and tissues collected for analysis 3 days post-transplant. Fetal kidneys were imaged ex vivo (PET and BLI) post-tissue harvest, and serial kidney sections were assessed by PCR for human-specific DNA sequences, fluorescent in situ hybridization (FISH) for human-specific centromere probes, and immunohistochemistry (IHC) to assess engrafted cells. Results Transplanted cells were readily imaged in vivo and identified at the site of injection; tissue analyses confirmed the imaging findings. Using a semi-quantitative method, one in approximately 650 cells in the kidney was shown to be of human origin by PCR and FISH. Conclusions These studies suggest that hES cells differentiated toward renal lineages can be effectively radiolabeled, transplanted into fetal monkey kidneys under ultrasound guidance, monitored with PET post-transplant, and identified by PET, BLI, PCR, FISH, and IHC post-tissue harvest. PMID:21479709

  20. What Makes a Dinosaur a Dinosaur?

    NSDL National Science Digital Library

    In this classroom activity, middle school students learn what distinguishes dinosaurs from other animals. The activity opens with background information for teachers about these prehistoric reptiles. As a class, students compare the stance of lizards and dinosaurs in pictures and try to replicate both reptiles' walks. Students then learn that Museum paleontologists classify birds as dinosaurs, and work in groups to compare a T. rex skeleton with pictures of birds.

  1. Uniaxial Mechanical Strain Modulates the Differentiation of Neural Crest Stem Cells into Smooth Muscle Lineage on Micropatterned Surfaces

    PubMed Central

    Li, Xian; Chu, Julia; Wang, Aijun; Zhu, Yiqian; Chu, Wai Keung; Yang, Li; Li, Song

    2011-01-01

    Neural crest stem cells (NCSCs) play an important role in the development and represent a valuable cell source for tissue engineering. However, how mechanical factors in vivo regulate NCSC differentiation is not understood. Here NCSCs were derived from induced pluripotent stem cells and used as a model to determine whether vascular mechanical strain modulates the differentiation of NCSCs into smooth muscle (SM) lineage. NCSCs were cultured on micropatterned membranes to mimic the organization of smooth muscle cells (SMCs), and subjected to cyclic uniaxial strain. Mechanical strain enhanced NCSC proliferation and ERK2 phosphorylation. In addition, mechanical strain induced contractile marker calponin-1 within 2 days and slightly induced SM myosin within 5 days. On the other hand, mechanical strain suppressed the differentiation of NCSCs into Schwann cells. The induction of calponin-1 by mechanical strain was inhibited by neural induction medium but further enhanced by TGF-?. For NCSCs pre-treated with TGF-?, mechanical strain induced the gene expression of both calponin-1 and SM myosin. Our results demonstrated that mechanical strain regulates the differentiation of NCSCs in a manner dependent on biochemical factors and the differentiation stage of NCSCs. Understanding the mechanical regulation of NCSC differentiation will shed light on the development and remodeling of vascular tissues, and how transplanted NCSCs respond to mechanical factors. PMID:22016804

  2. Prohibitin 2 Regulates the Proliferation and Lineage-Specific Differentiation of Mouse Embryonic Stem Cells in Mitochondria

    PubMed Central

    Komazaki, Shinji; Enomoto, Kei; Seki, Yasuhiro; Wang, Ying Ying; Ishigaki, Yohei; Ninomiya, Naoto; Noguchi, Taka-aki K.; Kokubu, Yuko; Ohnishi, Keigoh; Nakajima, Yoshiro; Kato, Kaoru; Intoh, Atsushi; Takada, Hitomi; Yamakawa, Norio; Wang, Pi-Chao; Asashima, Makoto; Kurisaki, Akira

    2014-01-01

    Background The pluripotent state of embryonic stem (ES) cells is controlled by a network of specific transcription factors. Recent studies also suggested the significant contribution of mitochondria on the regulation of pluripotent stem cells. However, the molecules involved in these regulations are still unknown. Methodology/Principal Findings In this study, we found that prohibitin 2 (PHB2), a pleiotrophic factor mainly localized in mitochondria, is a crucial regulatory factor for the homeostasis and differentiation of ES cells. PHB2 was highly expressed in undifferentiated mouse ES cells, and the expression was decreased during the differentiation of ES cells. Knockdown of PHB2 induced significant apoptosis in pluripotent ES cells, whereas enhanced expression of PHB2 contributed to the proliferation of ES cells. However, enhanced expression of PHB2 strongly inhibited ES cell differentiation into neuronal and endodermal cells. Interestingly, only PHB2 with intact mitochondrial targeting signal showed these specific effects on ES cells. Moreover, overexpression of PHB2 enhanced the processing of a dynamin-like GTPase (OPA1) that regulates mitochondrial fusion and cristae remodeling, which could induce partial dysfunction of mitochondria. Conclusions/Significance Our results suggest that PHB2 is a crucial mitochondrial regulator for homeostasis and lineage-specific differentiation of ES cells. PMID:24709813

  3. Molecular assessment of erythroid lineage chimerism following nonmyeloablative allogeneic stem cell transplantation

    Microsoft Academic Search

    Catherine J. Wu; Ephraim P. Hochberg; Shelby A. Rogers; Jeffery L. Kutok; Melinda Biernacki; Alessandra F. Nascimento; Peter Marks; Kenneth Bridges; Jerome Ritz

    2003-01-01

    ObjectiveNonmyeloablative conditioning regimens for allogeneic stem cell transplantation are now commonly used in the treatment of patients with hematologic malignancies. Since this treatment often results in the establishment of mixed hematopoietic chimerism, this approach may also prove to be useful in the treatment of nonmalignant disorders, such as sickle cell disease and thalassemia major. To apply this approach to these

  4. Optimization of fibrin scaffolds for differentiation of murine embryonic stem cells into neural lineage cells

    Microsoft Academic Search

    Stephanie M. Willerth; Kelly J. Arendas; David I. Gottlieb; Shelly Elese Sakiyama-Elbert

    2006-01-01

    The objective of this research was to determine the appropriate cell culture conditions for embryonic stem (ES) cell proliferation and differentiation in fibrin scaffolds by examining cell seeding density, location, and the optimal concentrations of fibrinogen, thrombin, and aprotinin (protease inhibitor). Mouse ES cells were induced to become neural progenitors by adding retinoic acid for 4 days to embryoid body

  5. Medulloblastoma Can Be Initiated by Deletion of Patched in Lineage-Restricted Progenitors or Stem Cells

    Microsoft Academic Search

    Zeng-Jie Yang; Tammy Ellis; Shirley L. Markant; Tracy-Ann Read; Jessica D. Kessler; Melissa Bourboulas; Ulrich Schüller; Robert Machold; Gord Fishell; David H. Rowitch; Brandon J. Wainwright; Robert J. Wechsler-Reya

    2008-01-01

    SUMMARY Medulloblastoma is the most common malignant brain tumor in children, but the cells from which it arises remain unclear. Here we examine the origin of medulloblastoma resulting from mutations in the Sonic hedge- hog (Shh) pathway. We show that activation of Shh signaling in neuronal progenitors causes medulloblas- toma by 3 months of age. Shh pathway activation in stem

  6. Dinosaur Sock Puppet

    NSDL National Science Digital Library

    OMSI

    2004-01-01

    In this activity about dinosaurs, learners first participate in a group discussion about where and when dinosaurs lived, how big they were, and who studies them and how. Then, learners use their imaginations to create dinosaur puppets with recycled art supplies and a sock, while considering what features their dinosaurs need. Learners make up stories to go along with their puppets and are encouraged to put on impromptu shows. A list of discussion questions is included in this resource to further the learning.

  7. Palaeontology Dinosaur extinction

    E-print Network

    Sargis, Eric J.

    Palaeontology Dinosaur extinction: closing the `3 m gap' Tyler R. Lyson1,2,*, Antoine Bercovici3- avian dinosaurs was ignited by the publication of the Cretaceous­Tertiary (K­T) asteroid impact theory and has seen 30 years of dispute over the position of the stratigraphically youngest in situ dinosaur

  8. Dinosaur Extinction: Changing Views

    E-print Network

    Archibald, J. David

    99 Dinosaur Extinction: Changing Views J. David Archibald Department of Biology San Diego State Asia. His 1996 book Dinosaur Extinction and the End of an Era: What the Fossils Say (Columbia University Press) documents what we know of the fossil record at the time of dinosaur extinction

  9. Direct lineage conversion of astrocytes to induced neural stem cells or neurons.

    PubMed

    Huang, Yanhua; Tan, Sheng

    2015-06-01

    Since the generation of induced pluripotent stem cells in 2006, cellular reprogramming has attracted increasing attention as a revolutionary strategy for cell replacement therapy. Recent advances have revealed that somatic cells can be directly converted into other mature cell types, which eliminates the risk of neoplasia and the generation of undesired cell types. Astrocytes become reactive and undergo proliferation, which hampers axon regeneration following injury, stroke, and neurodegenerative diseases. An emerging technique to directly reprogram astrocytes into induced neural stem cells (iNSCs) and induced neurons (iNs) by neural fate determinants brings potential hope to cell replacement therapy for the above neurological problems. Here, we discuss the development of direct reprogramming of various cell types into iNs and iNSCs, then detail astrocyte-derived iNSCs and iNs in vivo and in vitro. Finally, we highlight the unsolved challenges and opportunities for improvement. PMID:25854678

  10. Directed differentiation of induced pluripotent stem cells into chondrogenic lineages for articular cartilage treatment

    PubMed Central

    Lach, Micha?; Richter, Magdalena; Pawlicz, Jaros?aw; Suchorska, Wiktoria M

    2014-01-01

    In recent years, increases in the number of articular cartilage injuries caused by environmental factors or pathological conditions have led to a notable rise in the incidence of premature osteoarthritis. Osteoarthritis, considered a disease of civilization, is the leading cause of disability. At present, standard methods for treating damaged articular cartilage, including autologous chondrocyte implantation or microfracture, are short-term solutions with important side effects. Emerging treatments include the use of induced pluripotent stem cells, a technique that could provide a new tool for treatment of joint damage. However, research in this area is still early, and no optimal protocol for transforming induced pluripotent stem cells into chondrocytes has yet been established. Developments in our understanding of cartilage developmental biology, together with the use of modern technologies in the field of tissue engineering, provide an opportunity to create a complete functional model of articular cartilage.

  11. Directed differentiation of induced pluripotent stem cells into chondrogenic lineages for articular cartilage treatment

    PubMed Central

    Lach, Micha?; Richter, Magdalena; Pawlicz, Jaros?aw; Suchorska, Wiktoria M

    2014-01-01

    In recent years, increases in the number of articular cartilage injuries caused by environmental factors or pathological conditions have led to a notable rise in the incidence of premature osteoarthritis. Osteoarthritis, considered a disease of civilization, is the leading cause of disability. At present, standard methods for treating damaged articular cartilage, including autologous chondrocyte implantation or microfracture, are short-term solutions with important side effects. Emerging treatments include the use of induced pluripotent stem cells, a technique that could provide a new tool for treatment of joint damage. However, research in this area is still early, and no optimal protocol for transforming induced pluripotent stem cells into chondrocytes has yet been established. Developments in our understanding of cartilage developmental biology, together with the use of modern technologies in the field of tissue engineering, provide an opportunity to create a complete functional model of articular cartilage. PMID:25383175

  12. [A tumor stem cell-specific marker identified by lineage tracing in the intestine].

    PubMed

    Seno, Hiroshi; Yamaga, Yuichi; Nakanishi, Yuki; Chiba, Tsutomu

    2015-05-01

    Tumor therapies targeting tumor stem cells(TSCs) have been limited. One of the reasons is that TSC markers are often shared by normal stem cells (NSCs), and therapies targeting those marker-positive cells may cause severe injury to normal tissues. To solve the problem, we focused on doublecortin -like kinase 1 (Dclk1). In the normal intestines of Dclk1(creERT2/+); Rosa26(LacZ/+) mice, LacZ-labeled epithelial cells were scattered along villi after tamoxifen injection. In contrast, in Dclk1(creERT2/+); Rosa26(LacZ/+); Apc(Min/+) mice, intestinal tumors were occupied by LacZ-labeled tumor cells, and selective ablation of Dclk1-positive cells using iDTR system resulted in regression of intestinal tumors without apparent damage to the normal intestines. Thus, Dclk1 appeared to be a marker that discriminates TSCs from NSCs in the intestine. PMID:25985642

  13. Generation and applications of human pluripotent stem cells induced into neural lineages and neural tissues.

    PubMed

    Martinez, Y; Dubois-Dauphin, M; Krause, K-H

    2012-01-01

    Human pluripotent stem cells (hPSCs) represent a new and exciting field in modern medicine, now the focus of many researchers and media outlets. The hype is well-earned because of the potential of stem cells to contribute to disease modeling, drug screening, and even therapeutic approaches. In this review, we focus first on neural differentiation of these cells. In a second part we compare the various cell types available and their advantages for in vitro modeling. Then we provide a "state-of-the-art" report about two major biomedical applications: (1) the drug and toxicity screening and (2) the neural tissue replacement. Finally, we made an overview about current biomedical research using differentiated hPSCs. PMID:22457650

  14. Multi-Organ, Multi-Lineage Engraftment by a Single Bone Marrow-Derived Stem Cell

    Microsoft Academic Search

    Diane S. Krause; Neil D. Theise; Octavian Henegariu; Sonya Hwang; Rebekah Gardner; Sara Neutzel; Saul J. Sharkis

    2001-01-01

    Purification of rare hematopoietic stem cell(s) (HSC) to homogeneity is required to study their self-renewal, differentiation, phenotype, and homing. Long-term repopulation (LTR) of irradiated hosts and serial transplantation to secondary hosts represent the gold standard for demonstrating self-renewal and differentiation, the defining properties of HSC. We show that rare cells that home to bone marrow can LTR primary and secondary

  15. Synthetic nanostructures inducing differentiation of human mesenchymal stem cells into neuronal lineage

    SciTech Connect

    Yim, Evelyn K.F. [Department of Biomedical Engineering, Duke University, Durham, NC 27708 (United States); Pang, Stella W. [Solid State Electronics Laboratory, Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, MI 48109 (United States); Leong, Kam W. [Department of Biomedical Engineering, Duke University, Durham, NC 27708 (United States)]. E-mail: kam.leong@duke.edu

    2007-05-15

    Human mesenchymal stem cells (hMSCs) have been shown to trans-differentiate into neuronal-like cells by culture in neuronal induction media, although the mechanism is not well understood. Topography can also influence cellular responses including enhanced differentiation of progenitor cells. As extracellular matrix (ECM) in vivo comprises topography in the nanoscale, we hypothesize that nanotopography could influence stem cell differentiation into specific non-default pathways, such as transdifferentiation of hMSCs. Differentiation and proliferation of hMSCs were studied on nanogratings of 350 nm width. Cytoskeleton and nuclei of hMSCs were aligned and elongated along the nanogratings. Gene profiling and immunostaining showed significant up-regulation of neuronal markers such as microtubule-associated protein 2 (MAP2) compared to unpatterned and micropatterned controls. The combination of nanotopography and biochemical cues such as retinoic acid further enhanced the up-regulation of neuronal marker expressions, but nanotopography showed a stronger effect compared to retinoic acid alone on unpatterned surface. This study demonstrated the significance of nanotopography in directing differentiation of adult stem cells.

  16. Expression and function of receptors for stem cell factor and erythropoietin during lineage commitment of human hematopoietic progenitor cells.

    PubMed

    Olweus, J; Terstappen, L W; Thompson, P A; Lund-Johansen, F

    1996-09-01

    The aim of the present study was to determine whether stem cell factor (SCF) and erythropoietin (EPO) act differently on defined subsets of progenitor cells, and if potential differences correlate with the receptor density on each subset. To investigate this possibility directly, we optimized conditions for the identification and purification of homogeneous progenitor cell subpopulations from human bone marrow. Populations containing 40% and 44% colony forming cells (CFCs) with 99% and 95% purity for the granulomonocytic and erythroid lineage, respectively, were sorted on the basis of differential expression of CD34, CD64, and CD71. In addition, a population containing 67% CFCs, of which 29-43% were CFU-MIX, was sorted from CD34hi CD38loCD50+ cells. Purified progenitor cell subsets were compared directly for responsiveness to SCF and EPO using a short-term proliferation assay. Expression of the receptors for SCF and EPO were then examined on each subset using a flow cytometer modified for high-sensitivity fluorescence measurements. The results show that EPO induces extensive proliferation of erythroid progenitor cells, but has no effect on the proliferation or survival of primitive or granulomonocytic progenitors, even when used in combination with other cytokines. The majority of erythroid progenitor cells furthermore stained positively with anti-EPO receptor (EPO-R) monoclonal antibodies, whereas other progenitor cells were negative. SCF alone induced extensive proliferation of erythroid progenitor cells, and had a stronger synergistic effect on primitive than on granulo-monocytic progenitors. In spite of these differences in SCF activity, there were no significant differences in SCF-R expression between the progenitor subsets. These results suggest that the selective action of EPO on erythropoiesis is determined by lineage-restricted receptor expression, whereas there are additional cell-type specific factors that influence progenitor cell responses to SCF. PMID:8781415

  17. Dinosaurs 2: What Were Dinosaurs Like ?

    NSDL National Science Digital Library

    Science Netlinks

    2004-04-16

    This Science NetLinks lesson is the second of a two-part series on dinosaurs. Activities and discussions in this lesson revolve around comparing and contrasting dinosaurs to animals with which students are familiar. Students consider likenesses and differences through researching various questions and documenting their findings.

  18. Effect of human umbilical cord blood derived lineage negative stem cells transplanted in amyloid-? induced cognitive impaired mice.

    PubMed

    Banik, Avijit; Prabhakar, Sudesh; Kalra, Jasvinder; Anand, Akshay

    2015-09-15

    Alzheimer's disease (AD) is pathologically characterized by extracellular deposition of insoluble amyloid-? (A?) plaques and intracellular tangles made up of phosphorylated tau in brain. Several therapeutic approaches are being carried out in animal AD models for testing their safety and efficacy in altering disease pathology and behavioral deficits. Very few studies have examined the effect of human umbilical cord blood (hUCB) derived stem cells in degenerative disease models despite growing number of cord blood banks worldwide. Here we have examined the therapeutic efficacy of hUCB derived lineage negative (Lin -ve) stem cells in alleviating behavioral and neuropathological deficits in a mouse model of cognitive impairment induced by bilateral intrahippocampal injection of A?-42. Lin -ve cells were transplanted at two doses (50,000 and 100,000) at the site of injury and examined at 10 and 60 days post transplantation for rescue of memory deficits. These cells were found to ameliorate cognitive impairment in 50,000-60 days and 100,000-10 days groups whereas, 50,000-10 days and 100,000-60 days groups could not exert any significant improvement. Further, mice showing spatial memory improvement were mediated by up-regulation of BDNF, CREB and also by concomitant down regulation of Fas-L in their brain. The transplanted cells were found in the host tissue and survived up to 60 days without expressing markers of neuronal differentiation or reducing A? burden in mouse brain. We suggest that these undifferentiated cells could exert neuroprotective effects either through inhibiting apoptosis and/or trophic effects in the brain. PMID:25989508

  19. Direct Lineage Conversion of Adult Mouse Liver Cells and B Lymphocytes to Neural Stem Cells

    PubMed Central

    Cassady, John P.; D’Alessio, Ana C.; Sarkar, Sovan; Dani, Vardhan S.; Fan, Zi Peng; Ganz, Kibibi; Roessler, Reinhard; Sur, Mriganka; Young, Richard A.; Jaenisch, Rudolf

    2014-01-01

    Summary Overexpression of transcription factors has been used to directly reprogram somatic cells into a range of other differentiated cell types, including multipotent neural stem cells (NSCs), that can be used to generate neurons and glia. However, the ability to maintain the NSC state independent of the inducing factors and the identity of the somatic donor cells remain two important unresolved issues in transdifferentiation. Here we used transduction of doxycycline-inducible transcription factors to generate stable tripotent NSCs. The induced NSCs (iNSCs) maintained their characteristics in the absence of exogenous factor expression and were transcriptionally, epigenetically, and functionally similar to primary brain-derived NSCs. Importantly, we also generated tripotent iNSCs from multiple adult cell types, including mature liver and B cells. Our results show that self-maintaining proliferative neural cells can be induced from nonectodermal cells by expressing specific combinations of transcription factors. PMID:25454632

  20. Multipotent caudal neural progenitors derived from human pluripotent stem cells that give rise to lineages of the central and peripheral nervous system.

    PubMed

    Denham, Mark; Hasegawa, Kouichi; Menheniott, Trevelyan; Rollo, Ben; Zhang, Dongcheng; Hough, Shelley; Alshawaf, Abdullah; Febbraro, Fabia; Ighaniyan, Samiramis; Leung, Jessie; Elliott, David A; Newgreen, Donald F; Pera, Martin F; Dottori, Mirella

    2015-06-01

    The caudal neural plate is a distinct region of the embryo that gives rise to major progenitor lineages of the developing central and peripheral nervous system, including neural crest and floor plate cells. We show that dual inhibition of the glycogen synthase kinase 3? and activin/nodal pathways by small molecules differentiate human pluripotent stem cells (hPSCs) directly into a preneuroepithelial progenitor population we named "caudal neural progenitors" (CNPs). CNPs coexpress caudal neural plate and mesoderm markers, and, share high similarities to embryonic caudal neural plate cells in their lineage differentiation potential. Exposure of CNPs to BMP2/4, sonic hedgehog, or FGF2 signaling efficiently directs their fate to neural crest/roof plate cells, floor plate cells, and caudally specified neuroepithelial cells, respectively. Neural crest derived from CNPs differentiated to neural crest derivatives and demonstrated extensive migratory properties in vivo. Importantly, we also determined the key extrinsic factors specifying CNPs from human embryonic stem cell include FGF8, canonical WNT, and IGF1. Our studies are the first to identify a multipotent neural progenitor derived from hPSCs, that is the precursor for major neural lineages of the embryonic caudal neural tube. Stem Cells 2015;33:1759-1770. PMID:25753817

  1. Dinosaur eggs discovered inside mother

    NSDL National Science Digital Library

    American Association for the Advancement of Science (AAAS; )

    2005-04-14

    Scientists have discovered a dinosaur that died right before it laid two eggs. Finding dinosaur eggs inside the female, in almost the same position they were in when she died, might answer some tough questions about dinosaur egg-laying.

  2. Red Ginseng Extract Facilitates the Early Differentiation of Human Embryonic Stem Cells into Mesendoderm Lineage

    PubMed Central

    Kim, Yoon Young; Ku, Seung-Yup; Rosenwaks, Zev; Liu, Hung Ching; Oh, Sun Kyung; Moon, Shin Yong; Choi, Young Min

    2011-01-01

    Human embryonic stem cells (hESCs) have capacities to self-renew and differentiate into all cell types in vitro. Red ginseng (RG) is known to have a wide range of pharmacological effects in vivo; however, the reports on its effects on hESCs are few. In this paper, we tried to demonstrate the effects of RG on the proliferation and differentiation of hESCs. Undifferentiated hESCs, embryoid bodies (EBs), and hESC-derived cardiac progenitors (CPs) were treated with RG extract at 0.125, 0.25, and 0.5?mg/mL. After treatment of undifferentiated hESCs from day 2 to day 6 of culture, BrdU labeling showed that RG treatment increased the proliferation of hESCs, and the expression of Oct4 and Nanog was increased in RG-treated group. To find out the effects of RG on early differentiation stage cells, EBs were treated with RG extract for 10 days and attached for further differentiation. Immunostaining for three germ layer markers showed that RG treatment increased the expressions of Brachyury and HNF3? on EBs. Also, RG treatment increased the expression of Brachyury in early-stage and of Nkx2.5 in late-stage hESC-derived CPs. These results demonstrate facilitating effects of RG extract on the proliferation and early differentiation of hESC. PMID:20924497

  3. GEF-H1 controls focal adhesion signaling that regulates mesenchymal stem cell lineage commitment.

    PubMed

    Huang, I-Husan; Hsiao, Cheng-Te; Wu, Jui-Chung; Shen, Rong-Fong; Liu, Ching-Yi; Wang, Yang-Kao; Chen, Yu-Chen; Huang, Chi-Ming; del Álamo, Juan C; Chang, Zee-Fen; Tang, Ming-Jer; Khoo, Kay-Hooi; Kuo, Jean-Cheng

    2014-10-01

    Focal adhesions (FAs) undergo maturation that culminates in size and composition changes that modulate adhesion, cytoskeleton remodeling and differentiation. Although it is well recognized that stimuli for osteogenesis of mesenchymal stem cells (MSCs) drive FA maturation, actin organization and stress fiber polarization, the extent to which FA-mediated signals regulated by the FA protein composition specifies MSC commitment remains largely unknown. Here, we demonstrate that, upon dexamethasone (osteogenic induction) treatment, guanine nucleotide exchange factor H1 (GEF-H1, also known as Rho guanine nucleotide exchange factor 2, encoded by ARHGEF2) is significantly enriched in FAs. Perturbation of GEF-H1 inhibits FA formation, anisotropic stress fiber orientation and MSC osteogenesis in an actomyosin-contractility-independent manner. To determine the role of GEF-H1 in MSC osteogenesis, we explore the GEF-H1-modulated FA proteome that reveals non-muscle myosin-II heavy chain-B (NMIIB, also known as myosin-10, encoded by MYH10) as a target of GEF-H1 in FAs. Inhibition of targeting NMIIB into FAs suppresses FA formation, stress fiber polarization, cell stiffness and osteogenic commitments in MSCs. Our data demonstrate a role for FA signaling in specifying MSC commitment. PMID:25107365

  4. From weird wonders to stem lineages: the second reclassification of the Burgess Shale fauna.

    PubMed

    Brysse, Keynyn

    2008-09-01

    The Burgess Shale, a set of fossil beds containing the exquisitely preserved remains of marine invertebrate organisms from shortly after the Cambrian explosion, was discovered in 1909, and first brought to widespread popular attention by Stephen Jay Gould in his 1989 bestseller Wonderful life: The Burgess Shale and the nature of history. Gould contrasted the initial interpretation of these fossils, in which they were 'shoehorned' into modern groups, with the first major reexamination begun in the 1960s, when the creatures were perceived as 'weird wonders', possessing unique body plans and unrelated to modern organisms. More recently, a third phase of Burgess Shale studies has arisen, which has not yet been historically examined. This third phase represents a revolutionary new understanding, brought about, I believe, by a change in taxonomic methodology that led to a new perception of the Burgess creatures, and a new way to comprehend their relationships with modern organisms. The adoption of cladistics, and its corollary, the stem group concept, has forged a new understanding of the Burgess Shale ... but has it also changed the questions we are allowed to ask about evolution? PMID:18761282

  5. Nuclear receptor steroidogenic factor 1 directs embryonic stem cells toward the steroidogenic lineage.

    PubMed Central

    Crawford, P A; Sadovsky, Y; Milbrandt, J

    1997-01-01

    The orphan nuclear receptor steroidogenic factor 1 (SF-1) is expressed in the adrenal gland and gonads and is an important regulator of the expression of cytochrome P-450 steroidogenic enzymes in cultured cells. Targeted disruption of the SF-1 gene in mice shows that it is a critical participant in the genetic program that promotes the development of urogenital mesoderm into the adrenal gland and gonads. To assess the ability of SF-1 to regulate this differentiation pathway, we ectopically expressed SF-1 in murine embryonic stem (ES) cells. We found that stable expression of SF-1 is sufficient to alter ES cell morphology, permit cyclic AMP (cAMP) and retinoic acid-induced expression of the endogenous side chain cleavage enzyme gene, and consequently, promote steroidogenesis. While steroid production is dependent upon SF-1, cAMP induction of steroidogenesis does not enhance the responsiveness of an SF-1-specific reporter. Furthermore, the activity of a P450SCC promoter/luciferase reporter construct, which is induced by cAMP in steroidogenic cells and ES cells converted by stable expression of SF-1, is not induced by cAMP in wild-type ES cells transiently transfected with SF-1, suggesting that the induction of downstream gene products is required before steroidogenesis can occur. We demonstrate that mutants which disrupt the DNA binding domain or the AF2 transcriptional activation domain of SF-1 do not confer the steroidogenic phenotype to ES cells. Interestingly, however, AF2 mutants fused to the VP16 activation domain do confer the steroidogenic phenotype to ES cells, but only in the presence of a portion of the ligand binding domain. These studies extend the role of SF-1 in steroidogenic tissues to that of a dominant regulator of the steroidogenic cell phenotype. PMID:9199334

  6. High Throughput Transcriptome Profiling of Lithium Stimulated Human Mesenchymal Stem Cells Reveals Priming towards Osteoblastic Lineage

    PubMed Central

    Satija, Neeraj Kumar; Sharma, Deepa; Afrin, Farhat; Tripathi, Rajendra P.; Gangenahalli, Gurudutta

    2013-01-01

    Human mesenchymal stem cells (hMSCs) present in the bone marrow are the precursors of osteoblasts, chondrocytes and adipocytes, and hold tremendous potential for osteoregenerative therapy. However, achieving directed differentiation into osteoblasts has been a major concern. The use of lithium for enhancing osteogenic differentiation has been documented in animal models but its effect in humans is not clear. We, therefore, performed high throughput transcriptome analysis of lithium-treated hMSCs to identify altered gene expression and its relevance to osteogenic differentiation. Our results show suppression of proliferation and enhancement of alkaline phosphatase (ALP) activity upon lithium treatment of hMSCs under non-osteogenic conditions. Microarray profiling of lithium-stimulated hMSC revealed decreased expression of adipogenic genes (CEBPA, CMKLR1, HSD11B1) and genes involved in lipid biosynthesis. Interestingly, osteoclastogenic factors and immune responsive genes (IL7, IL8, CXCL1, CXCL12, CCL20) were also downregulated. Negative transcriptional regulators of the osteogenic program (TWIST1 and PBX1) were suppressed while genes involved in mineralization like CLEC3B and ATF4 were induced. Gene ontology analysis revealed enrichment of upregulated genes related to mesenchymal cell differentiation and signal transduction. Lithium priming led to enhanced collagen 1 synthesis and osteogenic induction of lithium pretreated MSCs resulted in enhanced expression of Runx2, ALP and bone sialoprotein. However, siRNA-mediated knockdown of RRAD, CLEC3B and ATF4 attenuated lithium-induced osteogenic priming, identifying a role for RRAD, a member of small GTP binding protein family, in osteoblast differentiation. In conclusion, our data highlight the transcriptome reprogramming potential of lithium resulting in higher propensity of lithium “primed” MSCs for osteoblastic differentiation. PMID:23383279

  7. G9a/GLP-dependent histone H3K9me2 patterning during human hematopoietic stem cell lineage commitment

    PubMed Central

    Chen, Xiaoji; Skutt-Kakaria, Kyobi; Davison, Jerry; Ou, Yang-Li; Choi, Edward; Malik, Punam; Loeb, Keith; Wood, Brent; Georges, George; Torok-Storb, Beverly; Paddison, Patrick J.

    2012-01-01

    G9a and GLP are conserved protein methyltransferases that play key roles during mammalian development through mono- and dimethylation of histone H3 Lys 9 (H3K9me1/2), modifications associated with transcriptional repression. During embryogenesis, large H3K9me2 chromatin territories arise that have been proposed to reinforce lineage choice by affecting high-order chromatin structure. Here we report that in adult human hematopoietic stem and progenitor cells (HSPCs), H3K9me2 chromatin territories are absent in primitive cells and are formed de novo during lineage commitment. In committed HSPCs, G9a/GLP activity nucleates H3K9me2 marks at CpG islands and other genomic sites within genic regions, which then spread across most genic regions during differentiation. Immunofluorescence assays revealed the emergence of H3K9me2 nuclear speckles in committed HSPCs, consistent with progressive marking. Moreover, gene expression analysis indicated that G9a/GLP activity suppresses promiscuous transcription of lineage-affiliated genes and certain gene clusters, suggestive of regulation of HSPC chromatin structure. Remarkably, HSPCs continuously treated with UNC0638, a G9a/GLP small molecular inhibitor, better retain stem cell-like phenotypes and function during in vitro expansion. These results suggest that G9a/GLP activity promotes progressive H3K9me2 patterning during HSPC lineage specification and that its inhibition delays HSPC lineage commitment. They also inform clinical manipulation of donor-derived HSPCs. PMID:23105005

  8. Dinosaur Planet video gallery

    NSDL National Science Digital Library

    Discovery Channel

    Despite the long loading times and annoying advertisements, there are a variety of worthwhile Flash and Windows media animations. As might be expected, the animations tend to stress the flashy, violent aspects of dinosaurs, like velociraptor attacks but there are also clips showing dinosaur eggs hatching, dinosaur locomotion, and even an interview with a paleontologist. A fast connection is a must to properly view this site.

  9. Create a Dinosaur Name

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore how dinosaurs are named and what their names mean. Learners listen to "The Littlest Dinosaurs" by Bernard Most. Then, learners decode real and imaginary dinosaur names by sliding paper strips featuring Latin and Greek words through three openings in a T. rex skull drawing. This activity is featured on page 11 of the "Dinosphere" unit of study for K-2 learners.

  10. Classroom Dinosaur Dig

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners participate in a simulated dig to discover fossilized dinosaur bones. Learners take notes, make a map and propose theories about dinosaurs. This can be used as a culminating activity at the end of a unit on dinosaurs, paleontology or archeology. This activity is featured on pp.48-50 (part of a lesson that begins on p.47) of the "Dinosphere" unit of study for grades 3-5.

  11. When Dinosaurs Roamed America

    NSDL National Science Digital Library

    This Discovery Channel interactive feature allows users to go back in time and watch the North American continent change and its creatures evolve. The feature begins with a map from which users can select a location or time period and see what the dinosaurs and their habitats were like. Other features include "Meet The Old Neighbors", in which students can enter their ZIP codes and learn which dinosaurs once lived in their areas, a collection of dinosaur videos, and a section on latest discoveries of dinosaurs.

  12. What Is a Dinosaur?

    NSDL National Science Digital Library

    In this classroom activity, young students learn what distinguishes dinosaurs from other animals. The activity opens with background information for teachers about these prehistoric reptiles. Working in small groups, students look through dinosaur books to gather interesting facts to share. As a class, students use their facts to create a semantic map. Then they explore the differences in dinosaur and lizard legs, and examine how these differences affect their stances. The activity concludes with a student worksheet that challenges them to identify the dinosaurs within a collection of animal illustrations.

  13. The Dinosaur Name Game

    NSDL National Science Digital Library

    In this classroom activity, middle school students explore the Greek and Latin root words used to create dinosaur names. The activity opens with background information for teachers about how dinosaurs are named. As a class, students explore the Greek and Latin roots of the words photograph, terrace and other familiar terms. Working individually, students complete a worksheet that challenges them to translate the meaning of seven dinosaurs' names. Then, working in pairs, students create their own dinosaur; name it; and describe how it moves, what it eats, how it raises it young, and how it behaves.

  14. Fossilized Dinosaur Teeth Adaptations

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners use models of fossilized dinosaur teeth to understand how dinosaur teeth were used. Learners specifically research Tyrannosaurus rex and Triceratops horridus dinosaurs and determine that Triceratops teeth work the way pliers and scissors operate, and T. rex teeth are like sharp knives. Learners match and sort dinosaurs by the type and use of their teeth. This activity is featured on pp.14-18 (part of a lesson that begins on p.7) of the "Dinosphere" unit of study for grades 3-5.

  15. Continuing differentiation of human mesenchymal stem cells and induced chondrogenic and osteogenic lineages in electrospun PLGA nanofiber scaffold

    PubMed Central

    Xin, Xuejun; Hussain, Mohammad; Mao, Jeremy J.

    2010-01-01

    Nanofibers have recently gained substantial interest for potential applications in tissue engineering. The objective of this study was to determine whether electrospun nanofibers accommodate the viability, growth, and differentiation of human mesenchymal stem cells (hMSCs) as well as their osteogenic (hMSC-Ob) and chondrogenic (hMSC-Ch) derivatives. Poly(D,L-lactide-co-glycolide) (PLGA) beads with a PLA:PGA ratio of 85:15 were electrospun into non-woven fibers with an average diameter of 760±210 nm. The average Young’s modulus of electrospun PLGA nanofibers was 42±26 kPa, per nanoindentation with atomic force microscopy (AFM). Human MSCs were seeded 1–4 weeks at a density of 2×106 cells/mL in PLGA nanofiber sheets. After 2 week culture on PLGA nanofiber scaffold, hMSCs remained as precursors upon immunoblotting with hKL12 antibody. SEM taken up to 7 days after cell seeding revealed that hMSCs, hMSC-Ob and hMSC-Ch apparently attached to PLGA nanofibers. The overwhelming majority of hMSCs was viable and proliferating in PLGA nanofiber scaffolds up to the tested 14 days, as assayed live/dead tests, DNA assay and BrdU. In a separate experiment, hMSCs seeded in PLGA nanofiber scaffolds were differentiated into chodrogenic and osteogenic cells. Histological assays revealed that hMSCs continuously differentiated into chondrogenic cells and osteogenic cells after 2 week incubation in PLGA nanofibers. Taken together, these data represent an original investigation of continuous differentiation of hMSCs into chondrogenic and osteogenic cells in PLGA nanofiber scaffold. Consistent with previous work, these findings also suggest that nanofibers may serve as accommodative milieu for not only hMSCs, but also as a 3D carrier vehicle for lineage specific cells. PMID:17010425

  16. No gastric mill in sauropod dinosaurs: new evidence from analysis of gastrolith mass and function in ostriches

    PubMed Central

    Wings, Oliver; Sander, P. Martin

    2006-01-01

    Polished pebbles occasionally found within skeletons of giant herbivorous sauropod dinosaurs are very likely to be gastroliths (stomach stones). Here, we show that based on feeding experiments with ostriches and comparative data for relative gastrolith mass in birds, sauropod gastroliths do not represent the remains of an avian-style gastric mill. Feeding experiments with farm ostriches showed that bird gastroliths experience fast abrasion in the gizzard and do not develop a polish. Relative gastrolith mass in sauropods (gastrolith mass much less than 0.1% of body mass) is at least an order of magnitude less than that in ostriches and other herbivorous birds (gastrolith mass approximates 1% of body mass), also arguing against the presence of a gastric mill in sauropods. Sauropod dinosaurs possibly compensated for their limited oral processing and gastric trituration capabilities by greatly increasing food retention time in the digestive system. Gastrolith clusters of some derived theropod dinosaurs (oviraptorosaurs and ornithomimosaurs) compare well with those of birds, suggesting that the gastric mill evolved in the avian stem lineage. PMID:17254987

  17. GEOL 104 Dinosaurs: A Natural History Homework 5: Dinosaur Physiology

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Homework 5: Dinosaur Physiology DUE: Mon. Nov. 27th (Dinosaur) Radiation 5th (Mammal) Radiation Locality Pred/Prey ratio Locality Pred/Prey ratio Morrison 3.5% Wasatch 4.4% Cloverly 3.7% Chadron 5.4% Dinosaur Park 3.5% Harrison 4.3% Hell Creek 1

  18. GEOL 104 Dinosaurs: A Natural History Homework 3: Dinosaur Relationships

    E-print Network

    Holtz Jr., Thomas R.

    Name: UID: 1 GEOL 104 Dinosaurs: A Natural History Homework 3: Dinosaur Relationships DUE: Wed. Nov. Thyreophora 7. Ankylosauria 8. What is the hypothesized diet of the dinosaurs in the cladogram above ]. Extra Credit) The diet of the dinosaur shown above was most likely [ meat | plants ]. For questions 20

  19. Digging into Dinosaurs.

    ERIC Educational Resources Information Center

    Braus, Judy, Ed.

    1989-01-01

    Ranger Rick's NatureScope is a creative education series dedicated to inspiring in children an understanding and appreciation of the natural world while developing the skills they will need to make responsible decisions about the environment. Contents are organized into the following sections: (1) "What Makes a Dinosaur a Dinosaur?," including…

  20. Dinosaurs of Italy

    Microsoft Academic Search

    Cristiano Dal Sasso

    2003-01-01

    In recent years, the idea that Italy was lacking dinosaurs has been denied by a striking series of finds. Several Triassic and Jurassic dinosaur tracksites were discovered in the mid-eastern Alps, in particular within the Dolomia Principale Fm. (Norian) and the Calcari Grigi Fm. (Hettangian to Pliensbachian), while thousands of Cretaceous (Santonian) prints came to light in Puglia (southern Italy).

  1. Dinosaur Extinction, Early Childhood Style

    ERIC Educational Resources Information Center

    Murray, Mary; Valentine-Anand, Lesley

    2008-01-01

    Do dinosaurs have bellybuttons? This intriguing question launched a journey into inquiry science that captivated a class of four-year-olds for eight months. As students enjoyed dinosaur books, examined dinosaur artifacts, drew pictures, watched videos, and generally immersed themselves in all things dinosaur, the authors built a culture of…

  2. Paleobiology of Herbivorous Dinosaurs

    NASA Astrophysics Data System (ADS)

    Barrett, Paul M.

    2014-05-01

    Herbivorous dinosaurs were abundant, species-rich components of Late Triassic-Cretaceous terrestrial ecosystems. Obligate high-fiber herbivory evolved independently on several occasions within Dinosauria, through the intermediary step of omnivory. Anatomical character complexes associated with this diet exhibit high levels of convergence and morphological disparity, and may have evolved by correlated progression. Dinosaur faunas changed markedly during the Mesozoic, from early faunas dominated by taxa with simple, uniform feeding mechanics to Cretaceous biomes including diverse sophisticated sympatric herbivores; the environmental and biological drivers causing these changes remain unclear. Isotopic, taphonomic, and anatomical evidence implies that niche partitioning reduced competition between sympatric herbivores, via morphological differentiation, dietary preferences, and habitat selection. Large body size in dinosaur herbivores is associated with low plant productivity, and gave these animals prominent roles as ecosystem engineers. Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions.

  3. A self-limiting switch based on translational control regulates the transition from proliferation to differentiation in an adult stem cell lineage

    PubMed Central

    Insco, Megan L.; Bailey, Alexis S.; Kim, Jongmin; Olivares, Gonzalo H.; Wapinski, Orly L.; Tam, Cheuk Ho; Fuller, Margaret T.

    2012-01-01

    Summary In adult stem cell lineages, progenitor cells commonly undergo mitotic transit amplifying (TA) divisions before terminal differentiation, allowing production of many differentiated progeny per stem cell division. Mechanisms that limit TA divisions and trigger the switch to differentiation may protect against cancer by preventing accumulation of oncogenic mutations in the proliferating population. Here we show that the switch from TA proliferation to differentiation in the Drosophila male germline stem cell lineage is mediated by translational control. The TRIM-NHL tumor suppressor homolog Mei-P26 facilitates accumulation of the differentiation regulator Bam in TA cells. In turn, Bam and its partner Bgcn bind the mei-P26 3?UTR and repress translation of mei-P26 in late TA cells. Thus, germ cells progress through distinct, sequential regulatory states, from Mei-P26 on/Bam off to Bam on/Mei-P26 off. TRIM-NHL homologs across species facilitate the switch from proliferation to differentiation, suggesting a novel and conserved developmentally-programmed tumor suppressor mechanism. PMID:23122292

  4. Oncogenic Kras-induced leukemogeneis: hematopoietic stem cells as the initial target and lineage-specific progenitors as the potential targets for final leukemic transformation

    PubMed Central

    Wang, Jing; Liu, Yangang; Sidik, Harwin; Young, Ken H.; Lodish, Harvey F.; Fleming, Mark D.

    2009-01-01

    KRAS is often mutated in human hematopoietic malignancies, including juvenile myelomonocytic leukemia (JMML) and T-cell lymphoblastic leukemia/lymphoma (TLL/L). However, the exact role and function of oncogenic KRAS mutations in the initiation and progression of JMML and TLL/L remain elusive. Here, we report the use of a mouse bone marrow transplantation model to study oncogenic Kras-induced leukemogenesis. We show that as the first genetic hit, oncogenic Kras mutations initiate both JMML and TLL/L, but with different efficiencies. Limiting dilution analyses indicated that an oncogenic Kras mutation alone is insufficient to produce frank malignancy. Instead, it cooperates with additional subsequent genetic event(s). Moreover, transplantation of highly purified hematopoietic stem cells (HSCs) and myeloid progenitors identified HSCs as the primary target for the oncogenic Kras mutation. Karyotypic analysis further indicated that secondary genetic hit(s) target lineage-specific progenitors rather than HSCs for terminal tumor transformation into leukemic stem cells. Thus, we propose the cellular mechanism underlying oncogenic Kras-induced leukemogenesis, with HSCs as the primary target by the oncogenic Kras mutations and lineage-committed progenitors as the final target for cancer stem cell transformation. Our model might be also applicable to other solid tumors harboring oncogenic Kras mutations. PMID:19066392

  5. Rise of dinosaurs reveals major body-size transitions are driven by passive processes of trait evolution.

    PubMed

    Sookias, Roland B; Butler, Richard J; Benson, Roger B J

    2012-06-01

    A major macroevolutionary question concerns how long-term patterns of body-size evolution are underpinned by smaller scale processes along lineages. One outstanding long-term transition is the replacement of basal therapsids (stem-group mammals) by archosauromorphs, including dinosaurs, as the dominant large-bodied terrestrial fauna during the Triassic (approx. 252-201 million years ago). This landmark event preceded more than 150 million years of archosauromorph dominance. We analyse a new body-size dataset of more than 400 therapsid and archosauromorph species spanning the Late Permian-Middle Jurassic. Maximum-likelihood analyses indicate that Cope's rule (an active within-lineage trend of body-size increase) is extremely rare, despite conspicuous patterns of body-size turnover, and contrary to proposals that Cope's rule is central to vertebrate evolution. Instead, passive processes predominate in taxonomically and ecomorphologically more inclusive clades, with stasis common in less inclusive clades. Body-size limits are clade-dependent, suggesting intrinsic, biological factors are more important than the external environment. This clade-dependence is exemplified by maximum size of Middle-early Late Triassic archosauromorph predators exceeding that of contemporary herbivores, breaking a widely-accepted 'rule' that herbivore maximum size greatly exceeds carnivore maximum size. Archosauromorph and dinosaur dominance occurred via opportunistic replacement of therapsids following extinction, but were facilitated by higher archosauromorph growth rates. PMID:22298850

  6. Multi-Lineage Differentiation of Human Umbilical Cord Wharton’s Jelly Mesenchymal Stromal Cells Mediates Changes in the Expression Profile of Stemness Markers

    PubMed Central

    Ali, Hamad; Al-Yatama, Majda K.; Abu-Farha, Mohamed; Behbehani, Kazem; Al Madhoun, Ashraf

    2015-01-01

    Wharton’s Jelly- derived Mesenchymal stem cells (WJ-MSCs) have gained interest as an alternative source of stem cells for regenerative medicine because of their potential for self-renewal, differentiation and unique immunomodulatory properties. Although many studies have characterized various WJ-MSCs biologically, the expression profiles of the commonly used stemness markers have not yet been addressed. In this study, WJ-MSCs were isolated and characterized for stemness and surface markers expression. Flow cytometry, immunofluorescence and qRT-PCR analysis revealed predominant expression of CD29, CD44, CD73, CD90, CD105 and CD166 in WJ-MSCs, while the hematopoietic and endothelial markers were absent. Differential expression of CD 29, CD90, CD105 and CD166 following adipogenic, osteogenic and chondrogenic induction was observed. Furthermore, our results demonstrated a reduction in CD44 and CD73 expressions in response to the tri-lineage differentiation induction, suggesting that they can be used as reliable stemness markers, since their expression was associated with undifferentiated WJ-MSCs only. PMID:25848763

  7. On Dinosaur Growth

    NASA Astrophysics Data System (ADS)

    Erickson, Gregory M.

    2014-05-01

    Despite nearly two centuries of investigation, a comprehensive understanding of dinosaur biology has proven intractable. The recent development of means to study tissue-level growth, age these animals, and make growth curves has revolutionized our knowledge of dinosaur lives. From such data it is now understood that dinosaurs grew both disruptively and determinately; that they rarely if ever exceeded a century in age; that they became giants through accelerated growth and dwarfed through truncated development; that they were likely endothermic, sexually matured like crocodiles, and showed survivorship like populations of large mammals; and that basal birds retained dinosaurian physiology.

  8. Developmental expression of fibroblast growth factor (FGF) receptors in neural stem cell progeny. Modulation of neuronal and glial lineages by basic FGF treatment.

    PubMed

    Reimers, D; López-Toledano, M A; Mason, I; Cuevas, P; Redondo, C; Herranz, A S; Lobo, M V; Bazán, E

    2001-09-01

    Neural stem cells (NSCs) are self-renewable, multipotential cells capable of differentiating into the three major neural cell types, but the mechanisms which regulate their development are not fully understood. Both basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) promote the proliferation of NSCs. However, studies on the role of FGFs in the differentiation of EGF-expanded NSCs are still incomplete. We have studied the expression of distinct FGF receptors (FGFRs) in the progeny of EGF-expanded NSCs isolated from E15 rat striatum. In situ hybridization analysis and immunocytochemistry showed a developmentally related expression pattern and a cell lineage-specific distribution of these receptors. FGFR1 and FGFR2 were identified in many early precursors and in the oligodendrocyte lineage. The latter receptor was also present in a subpopulation of astrocytes. FGFR3 was detected in a restricted population of early precursors, in oligodendroglial progenitors, and in neurons and protoplasmic astrocytes of late-term cultures. Basic FGF treatment of the progeny of NSCs increased the proliferative rate of precursors and the number of oligodendrocytes generated, whereas the number of differentiating neurons was significantly reduced. Together these data provide evidence that FGFs modulate the development of EGF-expanded NSCs, and that this is at least partly determined by a cell lineage-specific expression of multiple FGFRs. PMID:11547930

  9. Combined use of platelet rich plasma and vitamin C positively affects differentiation in vitro to mesodermal lineage of adult adipose equine mesenchymal stem cells.

    PubMed

    Castro, F O; Torres, A; Cabezas, J; Rodríguez-Alvarez, Ll

    2014-02-01

    Repair of injured soft and hard tissues in horses can benefit greatly from the use of regenerative therapies with mesenchymal stem cells (MSC). Vitamin-C and platelet-rich-plasma had been used for in vitro differentiation of MSC. This study was aimed to evaluate the effect of vitamin-C, platelet-rich-plasma and their combination on the in vitro differentiation of adipose horse MSC. We isolated MSC from horse fat and differentiated them in vitro into osteogenic and chondrogenic lineages, as demonstrated by specific staining and RT-qPCR of selected genes. Combining vitamin-C and plasma-rich-platelet positively affected the ability of MSC to differentiate in vitro into mesodermal lineages during 14 days of culture; this effect was not as marked when differentiation was attempted for 21 days. This provides valuable information on the effect of combined use of these molecules in regenerative therapies and their potential application along stem cells for lesions of musculoskeletal tissue in sport horses. PMID:24377415

  10. Differentiation of Retinal Ganglion Cells and Photoreceptor Precursors from Mouse Induced Pluripotent Stem Cells Carrying an Atoh7/Math5 Lineage Reporter

    PubMed Central

    Hashimoto, Takao; Tien, Amy H.; Chen, Andrew; Ge, Jian; Yang, Xian-Jie

    2014-01-01

    The neural retina is a critical component of the visual system, which provides the majority of sensory input in humans. Various retinal degenerative diseases can result in the permanent loss of retinal neurons, especially the light-sensing photoreceptors and the centrally projecting retinal ganglion cells (RGCs). The replenishment of lost RGCs and the repair of optic nerve damage are particularly challenging, as both RGC specification and their subsequent axonal growth and projection involve complex and precise regulation. To explore the developmental potential of pluripotent stem cell-derived neural progenitors, we have established mouse iPS cells that allow cell lineage tracing of progenitors that have expressed Atoh7/Math5, a bHLH transcription factor required for RGC production. These Atoh7 lineage reporter iPS cells encode Cre to replace one copy of the endogenous Atoh7 gene and a Cre-dependent YFP reporter in the ROSA locus. In addition, they express pluripotent markers and are capable of generating teratomas in vivo. Under anterior neural induction and neurogenic conditions in vitro, the Atoh7-Cre/ROSA-YFP iPS cells differentiate into neurons that co-express various RGC markers and YFP, indicating that these neurons are derived from Atoh7-expressing progenitors. Consistent with previous in vivo cell lineage studies, the Atoh7-Cre/ROSA-YFP iPS cells also give rise to a subset of Crx-positive photoreceptor precursors. Furthermore, inhibition of Notch signaling in the iPSC cultures results in a significant increase of YFP-positive RGCs and photoreceptor precursors. Together, these results show that Atoh7-Cre/ROSA-YFP iPS cells can be used to monitor the development and survival of RGCs and photoreceptors from pluripotent stem cells. PMID:25401462

  11. Fossilized Dinosaur Bones

    NSDL National Science Digital Library

    This slide show presents images of dinosaur bones and shows paleotologists at work excavating and preserving these fossils, the best evidence remaining of these long-lost creatures. A background essay and discussion questons are included.

  12. Warm and Cool Dinosaurs.

    ERIC Educational Resources Information Center

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  13. The Bristol Dinosaur Project

    Microsoft Academic Search

    Michael J. Benton; Remmert Schouten; Edward J. A. Drewitt; Pedro Viegas

    Dinosaurs have been fascinating to the widest public since the 1840s, and that interest has grown step-wise ever since. Public interest has been harnessed over the years especially by museums in blockbuster exhibitions, and in the form of best-selling books and films. Here we describe a major educational initiative, the Bristol Dinosaur Project, which has run for ten years and

  14. Polar dinosaurs on parade: a review of dinosaur migration

    Microsoft Academic Search

    Phil R. Bell; Eric Snively

    2008-01-01

    Cretaceous polar dinosaur faunas were taxonomically diverse, which suggests varied strategies for coping with the climatic stress of high latitudes. Some polar dinosaurs, particularly larger taxa such as the duckbill Edmontosaurus Lambe, 1917, were biomechanically and energetically capable of migrating over long distances, up to 2600 km. However, current evidence strongly suggests many polar dinosaurs (including sauropods, large and small theropods,

  15. Regulation of survival in adult hippocampal and glioblastoma stem cell lineages by the homeodomain-only protein HOP

    Microsoft Academic Search

    Arianna De Toni; Marie Zbinden; Jonathan A Epstein; Ariel Ruiz i Altaba; Alain Prochiantz; Isabelle Caillé

    2008-01-01

    BACKGROUND: Homeodomain proteins play critical roles in shaping the development of the embryonic central nervous system in mammals. After birth, neurogenic activities are relegated to stem cell niches, which include the subgranular layer of the dentate gyrus of the hippocampus. Here, we have analyzed the function of HOP (Homeodomain only protein) in this stem cell niche and in human glioblastomas.

  16. Fossilized Fashion: How Dinosaurs Looked

    NSDL National Science Digital Library

    This activity is a printable one-page PDF handout, which focuses on dinosaur features. It includes an album of animal fashions in which students compare three dinosaur's frills with similar features found on animals alive today in order to determine their function and a "design your own dinosaur" challenge in which students create a dinosaur that has the features they'd like to see.

  17. Dinosaurs in Russia and Mongolia

    E-print Network

    Benton, Michael

    The Age of Dinosaurs in Russia and Mongolia EDITED BY MichaelJ. Bemon University of Bristol Mikhail the CloetaCeous of Russia, Middle Asia, and :rvlongolia, arc equally important. Some of the dinosaurs elsewhere, but these are sorely in need of revision (see Chapter 11). The dinosaurs and other tetrapods from

  18. A transposon-mediated system for flexible control of transgene expression in stem and progenitor-derived lineages.

    PubMed

    Akhtar, Aslam Abbasi; Molina, Jessica; Dutra-Clarke, Marina; Kim, Gi Bum; Levy, Rachelle; Schreiber-Stainthorp, William; Danielpour, Moise; Breunig, Joshua J

    2015-03-10

    Precise methods for transgene regulation are important to study signaling pathways and cell lineages in biological systems where gene function is often recycled within and across lineages. We engineered a genetic toolset for flexible transgene regulation in these diverse cellular contexts. Specifically, we created an optimized piggyBac transposon-based system, allowing for the facile generation of stably transduced cell lineages in vivo and in vitro. The system, termed pB-Tet-GOI (piggyBac-transposable tetracycline transactivator-mediated flexible expression of a genetic element of interest), incorporates the latest generation of tetracycline (Tet) transactivator and reverse Tet transactivator variants--along with engineered mutants--in order to provide regulated transgene expression upon addition or removal of doxycycline (dox). Altogether, the flexibility of the system allows for dox-induced, dox-suppressed, dox-resistant (i.e., constitutive), and dox-induced/constitutive regulation of transgenes. This versatile strategy provides reversible temporal regulation of transgenes with robust inducibility and minimal leakiness. PMID:25702640

  19. Universal hydraulics of the flowering plants: vessel diameter scales with stem length across angiosperm lineages, habits and climates.

    PubMed

    Olson, Mark E; Anfodillo, Tommaso; Rosell, Julieta A; Petit, Giai; Crivellaro, Alan; Isnard, Sandrine; León-Gómez, Calixto; Alvarado-Cárdenas, Leonardo O; Castorena, Matiss

    2014-08-01

    Angiosperm hydraulic performance is crucially affected by the diameters of vessels, the water conducting conduits in the wood. Hydraulic optimality models suggest that vessels should widen predictably from stem tip to base, buffering hydrodynamic resistance accruing as stems, and therefore conductive path, increase in length. Data from 257 species (609 samples) show that vessels widen as predicted with distance from the stem apex across angiosperm orders, habits and habitats. Standardising for stem length, vessels are only slightly wider in warm/moist climates and in lianas, showing that, rather than climate or habit, plant size is by far the main driver of global variation in mean vessel diameter. Terminal twig vessels become wider as plant height increases, while vessel density decreases slightly less than expected tip to base. These patterns lead to testable predictions regarding evolutionary strategies allowing plants to minimise carbon costs per unit leaf area even as height increases. PMID:24847972

  20. Mei-P26 regulates microRNAs and cell growth in the Drosophila ovarian stem cell lineage

    Microsoft Academic Search

    Ralph A. Neumüller; Joerg Betschinger; Anja Fischer; Natascha Bushati; Ingrid Poernbacher; Karl Mechtler; Stephen M. Cohen; Juergen A. Knoblich

    2008-01-01

    Drosophila neuroblasts and ovarian stem cells are well characterized models for stem cell biology. In both cell types, one daughter cell self-renews continuously while the other undergoes a limited number of divisions, stops to proliferate mitotically and differentiates. Whereas neuroblasts segregate the Trim-NHL (tripartite motif and Ncl-1, HT2A and Lin-41 domain)-containing protein Brain tumour (Brat) into one of the two

  1. Temporal profiling of the growth and multi-lineage potentiality of adipose tissue-derived mesenchymal stem cells cell-sheets.

    PubMed

    Neo, Puay Yong; See, Eugene Yong-Shun; Toh, Siew Lok; Goh, James Cho-Hong

    2013-06-20

    Cell-sheet tissue engineering retains the benefits of an intact extracellular matrix (ECM) and can be used to produce scaffold-free constructs. Adipose tissue-derived stem cells (ASCs) are multipotent and more easily obtainable than the commonly used bone marrow-derived stem cells (BMSCs). Although BMSC cell sheets have been previously reported to display multipotentiality, a detailed study of the development and multilineage potential of ASC cell sheets (ASC-CSs) is non-existent in the literature. The aims of this study were to temporally profile: (a) the effect of hyperconfluent culture duration on ASC-CSs development; and (b) the multipotentiality of ASC-CSs by differentiation into the osteogenic, adipogenic and chondrogenic lineages. Rabbit ASCs were first isolated and cultured until confluence (day 0). The confluent cells were then cultured in ascorbic acid-supplemented medium for 3?weeks to study cell metabolic activity, cell sheet thickness and early differentiation gene expressions at weekly time points. ASC-CSs and ASCs were then differentiated into the three lineages, using established protocols, and assessed by RT-PCR and histology at multiple time points. ASC-CSs remained healthy up to 3?weeks of hyperconfluent culture. One week-old cell sheets displayed upregulation of early differentiation gene markers (Runx2 and Sox9); however, subsequent differentiation results indicated that they did not necessarily translate to an improved phenotype. ASCs within the preformed cell sheet groups did not differentiate as efficiently as the non-hyperconfluent ASCs, which were directly differentiated. Although ASCs within the cell sheets retained their differentiation capacity and remained viable under prolonged hyperconfluent conditions, future applications of ASC-CSs in tissue engineering should be considered with care. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23784965

  2. Determination of osteogenic or adipogenic lineages in muscle-derived stem cells (MDSCs) by a collagen-binding peptide (CBP) derived from bone sialoprotein (BSP)

    SciTech Connect

    Choi, Yoon Jung [Dental Regenerative Biotechnology Major, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of)] [Dental Regenerative Biotechnology Major, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Lee, Jue Yeon [Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC), Seoul (Korea, Republic of)] [Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC), Seoul (Korea, Republic of); Lee, Seung Jin [Department of Industrial Pharmacy, College of Pharmacy, Ewha Womans University, Seoul (Korea, Republic of)] [Department of Industrial Pharmacy, College of Pharmacy, Ewha Womans University, Seoul (Korea, Republic of); Chung, Chong-Pyoung, E-mail: ccpperio@snu.ac.kr [Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC), Seoul (Korea, Republic of) [Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC), Seoul (Korea, Republic of); Department of Periodontology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul (Korea, Republic of); Park, Yoon Jeong, E-mail: parkyj@snu.ac.kr [Dental Regenerative Biotechnology Major, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 110-749 (Korea, Republic of); Research Institute, Nano Intelligent Biomedical Engineering Corporation (NIBEC), Seoul (Korea, Republic of)

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer CBP sequence is identified from BSP and has collagen binding activity. Black-Right-Pointing-Pointer CBP directly activates the MAPK signaling, especially ERK1/2. Black-Right-Pointing-Pointer CBP increase osteoblastic differentiation by the activation of Runx2. Black-Right-Pointing-Pointer CBP decrease adipogenic differentiation by the inhibition of PPAR{gamma}. -- Abstract: Bone sialoprotein (BSP) is a mineralized, tissue-specific, non-collagenous protein that is normally expressed only in mineralized tissues such as bone, dentin, cementum, and calcified cartilage, and at sites of new mineral formation. The binding of BSP to collagen is thought to be important for initiating bone mineralization and bone cell adhesion to the mineralized matrix. Several recent studies have isolated stem cells from muscle tissue, but their functional properties are still unclear. In this study, we examined the effects of a synthetic collagen-binding peptide (CBP) on the differentiation efficiency of muscle-derived stem cells (MDSCs). The CBP sequence (NGVFKYRPRYYLYKHAYFYPHLKRFPVQ) corresponds to residues 35-62 of bone sialoprotein (BSP), which are located within the collagen-binding domain in BSP. Interestingly, this synthetic CBP inhibited adipogenic differentiation but increased osteogenic differentiation in MDSCs. The CBP also induced expression of osteoblastic marker proteins, including alkaline phosphatase (ALP), type I collagen, Runt-related transcription factor 2 (Runx2), and osteocalcin; prevented adipogenic differentiation in MDSCs; and down-regulated adipose-specific mRNAs, such as adipocyte protein 2 (aP2) and peroxisome proliferator-activated receptor {gamma}. The CBP increased Extracellular signal-regulated kinases (ERK) 1/2 protein phosphorylation, which is important in lineage determination. These observations suggest that this CBP determines the osteogenic or adipogenic lineage in MDSCs by activating ERK1/2. Taken together, a novel CBP could be a useful candidate for regenerating bone and treating osteoporosis, which result from an imbalance in osteogenesis and adipogenesis differentiation.

  3. Dinosaurs in Argentina

    NSDL National Science Digital Library

    This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on recent dinosaur excavations in Argentina and why this is a good place to look for dinosaur fossils. Students read articles, conduct research, and complete worksheets to find out information about what is found in Argentina and why. Included are objectives, materials, procedures, discussion questions, evaluation ideas, performing extensions, suggested readings, and vocabulary. There are videos available to order which compliment this lesson, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

  4. Dinosaur National Monument

    NSDL National Science Digital Library

    David Whitman

    This is the homepage of Dinosaur National Monument. Visitors can access information on the famous Douglas Quarry and visitor center, which preserves the fossils of dozens of dinosaurs from the Jurassic Period, including the Jurassic predator Allosaurus. There is also information on the Monument's plant and animal life, geology, and history and culture, including ancient rock art of the Fremont people. For teachers, there is information on planning field trips, either self-guided or with the assistance of a ranger. There is also a gallery of photos and multimedia resources.

  5. Next generation of ALDH substrates and their potential to study maturational lineage biology in stem and progenitor cells

    PubMed Central

    Boulter, Luke; Leclercq, Isabelle A.; van Grunsven, Leo A.

    2015-01-01

    High aldehyde dehydrogenase (ALDH) activity is a feature of stem cells from normal and cancerous tissues and a reliable universal marker used to isolate them. There are numerous ALDH isoforms with preferred substrate specificity variably expressed depending on tissue, cell type, and organelle and cell status. On the other hand, a given substrate may be metabolized by several enzyme isoforms. Currently ALDH activity is evidenced by using Aldefluor, a fluorescent substrate likely to be metabolized by numerous ALDH isoforms. Therefore, isolation techniques based on ALDH activity detection select a heterogeneous population of stem or progenitor cells. Despite active research in the field, the precise role(s) of different ALDH isoforms in stem cells remains enigmatic. Understanding the metabolic role of different ALDH isoform in the control of stem cell phenotype and cell fate during development, tissue homeostasis, or repair, as well as carcinogenesis, should open perspectives to significant discoveries in tissue biology. In this perspective, novel ALDH substrates are being developed. Here we describe how new substrates could be instrumental for better isolation of cell population with stemness potential and for defining hierarchy of cell populations in tissue. Finally, we speculate on other potential applications. PMID:25656041

  6. Dinosaurs of Switzerland

    Microsoft Academic Search

    Christian A Meyer; Basil Thüring

    2003-01-01

    Until 1960, the record of dinosaurs was rather poor in Switzerland. Between 1960 and 1980, several new localities with plateosaurid remains as well as prosauropod and theropod tracks were found in Late Triassic sabkha and floodplain environments. The discovery of large surfaces with sauropod tracks in the Late Jurassic of the Jura Mountains in 1987 triggered a stream of new

  7. Riding the Dinosaur Wave.

    ERIC Educational Resources Information Center

    Girod, Mark

    1998-01-01

    As his geology students' specialized knowledge of the Mesozoic era increased, a high school teacher realized he needed a way to showcase their work. The Mesozoic Resource Center's biggest hit was a walk-through diorama showing how life might have been during each of three Mesozoic periods. Highlights included two gigantic student-built dinosaur

  8. Kindergartners Love Dinosaurs

    ERIC Educational Resources Information Center

    Stollon, Marcy

    2005-01-01

    In this article, the author relates how she uses an art lesson that integrates art, language arts, and science in an enjoyable, creative project about dinosaurs in her kindergarten class. She relates how the children enjoy being illustrators and becoming familiar with well-known children's illustrators. She also relates that she starts her classes…

  9. Dinosaurs of Portugal

    Microsoft Academic Search

    Miguel Telles Antunes; Octávio Mateus

    2003-01-01

    A synthesis on the state of art on dinosaur knowledge in Portugal is presented. The following genera have been recognized: Ceratosaurus, Torvosaurus, Lourinhanosaurus, Allosaurus, cf. Compsognathus, Stokesosaurus, cf. Richardoestesia, cf. Archaeopteryx, Euronychodon, cf. Paronychodon, Dinheirosaurus, Lourinhasaurus, Lusotitan, cf. Pleurocoelus, Lusitanosaurus, Dacentrurus, Dracopelta, Phyllodon, Hypsilophodon, Alocodon, Trimucrodon, Draconyx, Iguanodon, and Taveirosaurus. Most are from Late Jurassic localities at the Lourinhă area

  10. FEEDBACK REGULATION IN MULTISTAGE CELL LINEAGES

    Microsoft Academic Search

    Wing-Cheong Lo; Ching-Shan Chou; Kimberly K. Gokoffski; Frederic Y.-M. Wan; Arthur D. Lander; Anne L. Calof; Qing Nie

    2009-01-01

    Studies of developing and self-renewing tissues have shown that differentiated cell types are typically specified through the actions of multi- stage cell lineages. Such lineages commonly include a stem cell and multiple progenitor (transit amplifying; TA) cell stages, which ultimately give rise to terminally differentiated (TD) cells. In several cases, self-renewal and differen- tiation of stem and progenitor cells within

  11. A Child Centered Approach to Dinosaurs.

    ERIC Educational Resources Information Center

    Strader, William H.; Rinker, Catherine A.

    1989-01-01

    Describes a curriculum for teaching young children about dinosaurs. Activity topics included Diplodocus eggs, sorting dinosaurs, creating terrariums, and extinction. Describes the incorporation of dinosaur activities into other subject areas and resource materials. (RJC)

  12. Notch Signaling Activation in Human Embryonic Stem Cells Is Required for Embryonic, but Not Trophoblastic, Lineage Commitment

    Microsoft Academic Search

    Xiaobing Yu; Jizhong Zou; Zhaohui Ye; Holly Hammond; Guibin Chen; Akinori Tokunaga; Prashant Mali; Yue-Ming Li; Curt Civin; Nicholas Gaiano; Linzhao Cheng

    SUMMARY The Notch signaling pathway plays important roles in cell-fate determination during embryonic develop- ment and adult life. In this study, we focus on the role of Notch signaling in governing cell-fate choices in human embryonic stem cells (hESCs). Using ge- netic and pharmacological approaches, we achieved both blockade and conditional activation of Notch signaling in several hESC lines. We

  13. Continuing differentiation of human mesenchymal stem cells and induced chondrogenic and osteogenic lineages in electrospun PLGA nanofiber scaffold

    Microsoft Academic Search

    Xuejun Xin; Mohammad Hussain; Jeremy J. Mao

    2007-01-01

    Nanofibers have recently gained substantial interest for potential applications in tissue engineering. The objective of this study was to determine whether electrospun nanofibers accommodate the viability, growth, and differentiation of human mesenchymal stem cells (hMSCs) as well as their osteogenic (hMSC-Ob) and chondrogenic (hMSC-Ch) derivatives. Poly(d,l-lactide-co-glycolide) (PLGA) beads with a PLA:PGA ratio of 85:15 were electrospun into non-woven fibers with

  14. The Wnt Receptor, Lrp5, Is Expressed by Mouse Mammary Stem Cells and Is Required to Maintain the Basal Lineage

    Microsoft Academic Search

    Nisha M. Badders; Shruti Goel; Rod J. Clark; Kristine S. Klos; Soyoung Kim; Anna Bafico; Charlotta Lindvall; Bart O. Williams; Caroline M. Alexander; Joseph Najbauer

    2009-01-01

    BackgroundEctopic Wnt signaling induces increased stem\\/progenitor cell activity in the mouse mammary gland, followed by tumor development. The Wnt signaling receptors, Lrp5\\/6, are uniquely required for canonical Wnt activity. Previous data has shown that the absence of Lrp5 confers resistance to Wnt1-induced tumor development.Methodology\\/Principal FindingsHere, we show that all basal mammary cells express Lrp5, and co-express Lrp6 in a similar

  15. Evolution of dinosaur epidermal structures.

    PubMed

    Barrett, Paul M; Evans, David C; Campione, Nicolás E

    2015-06-01

    Spectacularly preserved non-avian dinosaurs with integumentary filaments/feathers have revolutionized dinosaur studies and fostered the suggestion that the dinosaur common ancestor possessed complex integumentary structures homologous to feathers. This hypothesis has major implications for interpreting dinosaur biology, but has not been tested rigorously. Using a comprehensive database of dinosaur skin traces, we apply maximum-likelihood methods to reconstruct the phylogenetic distribution of epidermal structures and interpret their evolutionary history. Most of these analyses find no compelling evidence for the appearance of protofeathers in the dinosaur common ancestor and scales are usually recovered as the plesiomorphic state, but results are sensitive to the outgroup condition in pterosaurs. Rare occurrences of ornithischian filamentous integument might represent independent acquisitions of novel epidermal structures that are not homologous with theropod feathers. PMID:26041865

  16. Weigh a Dinosaur

    NSDL National Science Digital Library

    Andrew Heckert

    Students select dinosaurian models (toys) from a selection of Carnegie, Natural History Museum (London) and other manufacturers (Schleich, Safari, etc). Each student identifies their dinosaur, places it on a cladogram (provided) and determines when it lived. They then measure the dinosaur in three dimensions (length, width, height), compare one or more of these dimensions to "real" dimensions provided (usually the model says what the length was). Dividing "real" by "measured" yields a scale. Students then determine how much water their model displaces. NOTE: Most textbooks show this happening with a beaker. Beakers are no where near accurate enough to use, and many dinosaurs dont fit in them anyway. You need either extremely large graduated cylinders (unlikely) or else large containers in a sink. What works best is to have students fill a container to overflowing (in the sink, obviously), then gently dunk their dinosaur, causing the vessel to overflow, then retrieve their dinosaur. THEN you can use a graduated cylinder to refill the container and measure the amount of water displaced. Once students have a scale and a volume, the can cube the former and multiply it by the latter to yield an estimate of the volume of the actual dinosaur. Multiplying this by a density estimate provides an estimated mass. I have them bracket it by taking 0.9kg/L and 1.05kg/L for "light" and "heavy." Feathered theropods are even lighterâI have them use 0.8 g/L for the light estimate. They then record their result (I am trying to generate a spreadsheet of these measurements over the years) and compare it to a published estimate. I should probably base their grade on the ratio of their estimate to the "actual" (if light, reversed if heavy) but generally just try to "police" the workâif they are way off, they need to go back and find what arithmetic error led to the problem. In the introductory classes this is a simple 1-sheet worksheet (front and back). For the honors students, they take the assignment home and write it up. PS. I let the anthropology majors play with models of Pleistocene megafauna instead.

  17. Dinosaur Fossils Predict Body Temperatures

    PubMed Central

    Allen, Andrew P; Charnov, Eric L

    2006-01-01

    Perhaps the greatest mystery surrounding dinosaurs concerns whether they were endotherms, ectotherms, or some unique intermediate form. Here we present a model that yields estimates of dinosaur body temperature based on ontogenetic growth trajectories obtained from fossil bones. The model predicts that dinosaur body temperatures increased with body mass from approximately 25 °C at 12 kg to approximately 41 °C at 13,000 kg. The model also successfully predicts observed increases in body temperature with body mass for extant crocodiles. These results provide direct evidence that dinosaurs were reptiles that exhibited inertial homeothermy. PMID:16817695

  18. What's in a Dinosaur Name?

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore the etymology of dinosaur names. Learners first discuss how dinosaurs are often named after a body part or behavior, where they were found, or a person (finder or famous). Learners also discuss Greek and Latin prefixes and suffixes that are commonly found in dinosaur names. Then, learners create a paper puzzle that generates new dinosaur names. This activity is featured on pp.20-27 (part of a lesson that begins on p.19) of the "Dinosphere" unit of study for grades 3-5.

  19. Transcriptome profiling and sequencing of differentiated human hematopoietic stem cells reveal lineage-specific expression and alternative splicing of genes

    PubMed Central

    Liu, Poching; Barb, Jennifer; Woodhouse, Kimberly; Taylor, James G.; Munson, Peter J.

    2011-01-01

    Hematopoietic differentiation is strictly regulated by complex network of transcription factors that are controlled by ligands binding to cell surface receptors. Disruptions of the intricate sequences of transcriptional activation and suppression of multiple genes cause hematological diseases, such as leukemias, myelodysplastic syndromes, or myeloproliferative syndromes. From a clinical standpoint, deciphering the pattern of gene expression during hematopoiesis may help unravel disease-specific mechanisms in hematopoietic malignancies. Herein, we describe a human in vitro hematopoietic model system where lineage-specific differentiation of CD34+ cells was accomplished using specific cytokines. Microarray and RNAseq-based whole transcriptome and exome analysis was performed on the differentiated erythropoietic, granulopoietic, and megakaryopoietic cells to delineate changes in expression of whole transcripts and exons. Analysis on the Human 1.0 ST exon arrays indicated differential expression of 172 genes (P < 0.0000001) and significant alternate splicing of 86 genes during differentiation. Pathway analysis identified these genes to be involved in Rac/RhoA signaling, Wnt/B-catenin signaling and alanine/aspartate metabolism. Comparison of the microarray data to next generation RNAseq analysis during erythroid differentiation demonstrated a high degree of correlation in gene (R = 0.72) and exon (R = 0.62) expression. Our data provide a molecular portrait of events that regulate differentiation of hematopoietic cells. Knowledge of molecular processes by which the cells acquire their cell-specific fate would be beneficial in developing cell-based therapies for human diseases. PMID:21828245

  20. Myogenic lineage differentiated mesenchymal stem cells enhance recovery from dextran sulfate sodium-induced colitis in the rat

    Microsoft Academic Search

    Hiroki TanakaYoshiaki; Yoshiaki Arimura; Takashi Yabana; Akira Goto; Masayo Hosokawa; Kanna Nagaishi; Kentaro Yamashita; Hiroyuki Yamamoto; Yasushi Sasaki; Mineko Fujimiya; Kohzoh Imai; Yasuhisa Shinomura

    2011-01-01

    Background  Although mounting evidence implicates mesenchymal stem cells (MSCs) in intestinal tissue repair, uncertainty remains concerning\\u000a the distribution, function, and fate of repopulating MSCs in recipient colonic tissues. Therefore, we investigated the role\\u000a of transplanted MSCs in the repair phase of DSS colitis.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  LacZ-labeled rat MSCs were transplanted into rats with colitis induced by 4% DSS on day 2. Regular water

  1. Micro-/Nano- sized hydroxyapatite directs differentiation of rat bone marrow derived mesenchymal stem cells towards an osteoblast lineage

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Zhou, Gang; Zheng, Lisha; Liu, Haifeng; Niu, Xufeng; Fan, Yubo

    2012-03-01

    Regenerative medicine consisting of cells and materials provides a new way for the repair and regeneration of tissues and organs. Nano-biomaterials are highlighted due to their advantageous features compared with conventional micro-materials. The aim of this study is to investigate the effects of micro-/nano- sized hydroxyapatite (?/n-HA) on the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells (rBMSCs). ?/n-HA were prepared by a microwave synthesizer and precipitation method, respectively. Different sizes of ?/n-HA were characterized by IR, XRD, SEM, TEM and co-cultured with rBMSCs. It was shown that rBMSCs expressed higher levels of osteoblast-related markers by n-HA than ?-HA stimulation. The size of HA is an important factor for affecting the osteogenic differentiation of rBMSCs. This provides a new avenue for mechanistic studies of stem cell differentiation and a new approach to obtain more committed differentiated cells.

  2. Dinosaur Bone Experiments

    NSDL National Science Digital Library

    Lawrence Hall of Science

    2005-01-01

    This activity features two connected hands-on activities about dinosaur bones. Using chicken or turkey bones and regular household items, learners explore the scientific process of studying fossilized bones. By exposing the bones to vinegar or heat, learners begin to understand how paleontologists use chemical processes to study the bones of animals long dead and gone. Use this bone-themed activity around the Thanksgiving holiday and repurpose some leftovers.

  3. GEOL 104 Dinosaurs: A Natural History Smithsonian Assignment II: Dinosaurs, Mesozoic Marine Life, and the Cenozoic Era (but mostly dinosaurs)

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Smithsonian Assignment II: Dinosaurs, Mesozoic Marine Life, and the Cenozoic Era (but mostly dinosaurs) DUE: November 22 The Smithsonian Institution's National Museum of Natural History (NMNH) has one of the largest collections of dinosaur and other fossils

  4. Life-long in vivo cell-lineage tracing shows that no oogenesis originates from putative germline stem cells in adult mice

    PubMed Central

    Zhang, Hua; Liu, Lian; Li, Xin; Busayavalasa, Kiran; Shen, Yan; Hovatta, Outi; Gustafsson, Jan-Ĺke; Liu, Kui

    2014-01-01

    Whether or not oocyte regeneration occurs in adult life has been the subject of much debate. In this study, we have traced germ-cell lineages over the life spans of three genetically modified mouse models and provide direct evidence that oogenesis does not originate from any germline stem cells (GSCs) in adult mice. By selective ablation of all existing oocytes in a Gdf9-Cre;iDTR mouse model, we have demonstrated that no new germ cells were ever regenerated under pathological conditions. By in vivo tracing of oocytes and follicles in the Sohlh1-CreERT2;R26R and Foxl2-CreERT2;mT/mG mouse models, respectively, we have shown that the initial pool of oocytes is the only source of germ cells throughout the life span of the mice and that no adult oogenesis ever occurs under physiological conditions. Our findings clearly show that there are no GSCs that contribute to adult oogenesis in mice and that the initial pool of oocytes formed in early life is the only source of germ cells throughout the entire reproductive life span. PMID:25453063

  5. Novel basic helix-loop-helix transcription factor hes4 antagonizes the function of twist-1 to regulate lineage commitment of bone marrow stromal/stem cells.

    PubMed

    Cakouros, Dimitrios; Isenmann, Sandra; Hemming, Sarah Elizabeth; Menicanin, Danijela; Camp, Esther; Zannetinno, Andrew Christopher William; Gronthos, Stan

    2015-06-01

    Basic helix-loop-helix (bHLH) transcription factors are pivotal regulators of cellular differentiation and development. The bHLH factor, Twist-1 has previously been found to control bone marrow stromal/stem cells (BMSC) self-renewal, life span, and differentiation, however not much is known about its mechanism of action. In this study, we have discovered a novel Twist-1 regulated bHLH gene, Hes4, expressed in humans, but not in mice. Its closest homologue in both humans and mice is Hes1. Overexpression and knockdown studies demonstrated that Hes4 promotes osteogenesis resulting in an increase in Runx2, osteocalcin, osteopontin, and bone sialoprotein expression. Conversely, Hes4 was found to inhibit adipogenesis accompanied by a decrease in PPAR?2, adiponectin, and adipsin expression. In vitro studies indicate that Hes4 employs a mechanism to counteract the negative function of Twist-1 on osteogenesis by binding to Twist-1 and inhibiting the ability of Twist-1 to bind and inhibit Runx2. In vivo chromatin immunoprecipitation and in vitro reporter assays illustrated that Runx2 recruitment to the osterix promoter, was found to be enhanced in the presence of Hes4 and inhibited in the presence of Twist-1. Therefore, Hes4 antagonizes the function of Twist-1 to regulate lineage commitment of BMSC. These studies highlight the potential differences in molecular mechanisms that regulate BMSC osteogenic differentiation between human and mouse. PMID:25579220

  6. Gastroliths in An Ornithopod Dinosaur

    Microsoft Academic Search

    Ignacio A. Cerda

    2008-01-01

    Gastroliths (stomach stones) are known from many extant and extinct vertebrates, including dinosaurs. Reported here is the first unambiguous record of gastroliths in an ornitho? pod dinosaur. Clusters of small stones found in the abdomi? nal region of three articulated skeletons of Gasparinisaura cincosaltensis were identified as gastroliths on the basis of taphonomic and sedimentologic evidence. The large number of

  7. Early dinosaurs: A phylogenetic study

    Microsoft Academic Search

    Max C. Langer; Michael J. Benton

    2006-01-01

    Early dinosaur evolution has been the subject of several phylogenetic studies and the position of certain basal forms is currently debated. This is the case for the oldest known members of the group, excavated from the Late Triassic Ischigualastian beds of South America, such as Herrerasaurus, Eoraptor, Pisanosaurus, Saturnalia and Staurikosaurus. A new cladistic analysis of the early dinosaur radiation

  8. Making Sense of Dinosaur Tracks

    ERIC Educational Resources Information Center

    MacKenzie, Ann Haley; McDowell, Brian

    2012-01-01

    What do paleontologists, dinosaur tracks, and the nature of science have in common? They're combined here in an inquiry activity where students use methods of observation and inference to devise evidence-based explanations for the data they collect about dinosaur tracks, much like the methods used by paleontologists. Students then debate the…

  9. T-Cell Lineage Determination

    PubMed Central

    Yang, Qi; Bell, J. Jeremiah; Bhandoola, Avinash

    2010-01-01

    Summary T cells originate from hematopoietic stem cells (HSCs) in the bone marrow but complete their development in the thymus. HSCs give rise to a variety of non-renewing hematopoietic progenitors, among which a rare subset migrates to the thymus via the bloodstream. The earliest T-cell progenitors identified in the thymus are not T-lineage restricted but possess the ability to give rise to cells of many different lineages. Alternative lineage potentials are gradually lost as progenitors progress towards later developmental stages. Here, we review the early developmental events that might be involved in T-cell lineage fate determination, including the properties of possible thymus settling progenitors, their homing into the thymus, and their T-cell lineage specification and commitment. PMID:20969581

  10. Dinosaur's Sex No Longer a Mystery

    NSDL National Science Digital Library

    Dinosaur researchers have achieved another first: discovering a way to tell the sex of a dinosaur. The secret is in the bone. This radio broadcast reports on the discovery of medullary bone in dinosaurs, which exists in a cavity of the thigh bone in egg-laying female therapod dinosaurs and provides calcium for the shells of eggs. This discovery also further links dinosaurs to birds. The clip is 3 minutes and 41 seconds in length.

  11. Dinosaur Skull and Body Length Predictions

    NSDL National Science Digital Library

    2012-06-26

    In this activity (located on page 2 of PDF), learners will look for a relationship between skull size and body length among various dinosaurs. Starting from a list of dinosaur measurements, learners will compare dinosaur sizes to common objects and create a chart that plots body length against skull length to see if the data predicts other dinosaurs' length from skull size. Relates to the linked video, DragonflyTV GPS: Baby Dinosaurs.

  12. When Dinosaurs Ruled

    NSDL National Science Digital Library

    John DeMary

    This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on the Mesozoic Era, when dinosaurs roamed the Earth. Through research and activities students learn about the plants and animals that inhabited Earth at that time, and the changes in plant life that occurred due to the development of animal life. It includes objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

  13. What's New with Dinosaurs

    NSDL National Science Digital Library

    This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 6-8. It focuses on a current controversary among scientists over whether dinosaurs were warm-blooded or cold-blooded. Students research both sides of the argument and then present a debate over this topic. It includes objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

  14. Compartmental Hollow Fiber Capillary Membrane–Based Bioreactor Technology for In Vitro Studies on Red Blood Cell Lineage Direction of Hematopoietic Stem Cells

    PubMed Central

    Housler, Greggory J.; Miki, Toshio; Schmelzer, Eva; Pekor, Christopher; Zhang, Xiaokui; Kang, Lin; Voskinarian-Berse, Vanessa; Abbot, Stewart; Zeilinger, Katrin

    2012-01-01

    Continuous production of red blood cells (RBCs) in an automated closed culture system using hematopoietic stem cell (HSC) progenitor cell populations is of interest for clinical application because of the high demand for blood transfusions. Previously, we introduced a four-compartment bioreactor that consisted of two bundles of hollow fiber microfiltration membranes for transport of culture medium (forming two medium compartments), interwoven with one bundle of hollow fiber membranes for transport of oxygen (O2), carbon dioxide (CO2), and other gases (forming one gas compartment). Small-scale prototypes were developed of the three-dimensional (3D) perfusion cell culture systems, which enable convection-based mass transfer and integral oxygenation in the cell compartment. CD34+ HSC were isolated from human cord blood units using a magnetic separation procedure. Cells were inoculated into 2- or 8-mL scaled-down versions of the previously designed 800-mL cell compartment devices and perfused with erythrocyte proliferation and differentiation medium. First, using the small-scale 2-mL analytical scale bioreactor, with an initial seeding density of 800,000 cells/mL, we demonstrated approximately 100-fold cell expansion and differentiation after 7 days of culture. An 8-mL laboratory-scale bioreactor was then used to show pseudocontinuous production by intermediately harvesting cells. Subsequently, we were able to use a model to demonstrate semicontinuous production with up to 14,288-fold expansion using seeding densities of 800,000 cells/mL. The down-scaled culture technology allows for expansion of CD34+ cells and stimulating these progenitors towards RBC lineage, expressing approximately 40% CD235+ and enucleation. The 3D perfusion technology provides an innovative tool for studies on RBC production, which is scalable. PMID:21933020

  15. Centering on Fossils and Dinosaurs.

    ERIC Educational Resources Information Center

    Coble, Charles R.; McCall, Gregory K.

    1986-01-01

    Describes a set of 10 activities which introduce mainstreamed junior high school students to concepts relating to fossils and dinosaurs. Provides students with opportunities for learning the concepts of change and adaptation, as well as fossil facts and terminology. (TW)

  16. How Do Scientists Find Dinosaur Fossils?

    NSDL National Science Digital Library

    This lesson plan is about the process by which paleontologists locate, excavate, and study dinosaurs. Students will write journal entries pretending they are on a dinosaur dig. They will also make fact sheets about this recently discovered Jobaria dinosaur; place Jobaria into a timeline to indicate the periods in which it lived; visit a website to learn about the steps involved in finding and excavating dinosaur fossils, then list these steps and explain their importance; describe what the bones in an interactive Jobaria skeleton indicate about this dinosaur; and view pictures of a trip teenagers took to look for dinosaur fossils.

  17. A distinct dinosaur life history?

    Microsoft Academic Search

    David J. Varricchio

    2011-01-01

    Five factors, mobile terrestrial lifestyle, oviparity, parental care, multi-year maturation and juvenile sociality, contribute to a distinct life history for Mesozoic dinosaurs in comparison to extant archosaurs and mammals. Upright, para-sagittal gait reflects several synapomorphies of Dinosauria, and wide histological sampling suggests that multi-year maturation typified dinosaurs across a range of body sizes. Fossil support for juvenile sociality exceeds that

  18. Dinosaurs: Ancient Fossils, New Discoveries

    NSDL National Science Digital Library

    This Web site, created to complement the Museum's Dinosaurs: Ancient Fossils, New Discoveries exhibit, offers a virtual visit to the Museum, complete with text, photos, video clips, audio interviews, and more and includes much of the information which was in the original exhibit which is now closed. The site includes information on the bio-mechanics of dinosaurs and the reasons behind some of their strange appearances.

  19. How Big Were the Dinosaurs?

    NSDL National Science Digital Library

    In this classroom activity, younger students compare their feet to the footprint of a large Apatosaur. The activity opens with background information about the enormous size range of dinosaurs and a discussion in which the students name some of the dinosaurs they know and describe how big they were. Then, each student will make an outline of their own footprint and fasten it onto the full-size Apatosaur print (which must be enlarged from the smaller drawing that is provided).

  20. The extinction of the dinosaurs.

    PubMed

    Brusatte, Stephen L; Butler, Richard J; Barrett, Paul M; Carrano, Matthew T; Evans, David C; Lloyd, Graeme T; Mannion, Philip D; Norell, Mark A; Peppe, Daniel J; Upchurch, Paul; Williamson, Thomas E

    2015-05-01

    Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult. PMID:25065505

  1. The new evolution of dinosaurs UAlberta research is challenging basic assumptions about dinosaurs and greatly

    E-print Network

    Machel, Hans

    The new evolution of dinosaurs UAlberta research is challenging basic assumptions about dinosaurs on the feathered dinosaur Anchiornis huxleyi (pictured above) are based on comparisons with the cellular structures of modern birds. UAlberta researcher Phil Currie helped identify the first dinosaur specimens

  2. Dinosaurs and the island rule: The dwarfed dinosaurs from Haeg Island Michael J. Benton a,

    E-print Network

    Benton, Michael

    Dinosaurs and the island rule: The dwarfed dinosaurs from Haeg Island Michael J. Benton a, , Zoltan 2009 Accepted 21 January 2010 Available online 28 January 2010 Keywords: Dinosaurs Cretaceous, in 1914, to suggest that the latest Cretaceous dinosaurs from Haeg, Romania were an island fauna, based

  3. Giant European dinosaur found in Spain

    NSDL National Science Digital Library

    American Association for the Advancement of Science (AAAS; )

    2006-12-21

    Fossils of a giant Sauropod, found in Spain, reveal that Europe was home to giant dinosaurs in the Late Jurassic period -- about 150 million years ago. Giant dinosaurs have previously been found mainly in the New World and Africa.

  4. Dinosaur peptides suggest mechanisms of protein survival

    E-print Network

    San Antonio, James D.

    Eleven collagen peptide sequences recovered from chemical extracts of dinosaur bones were mapped onto molecular models of the vertebrate collagen fibril derived from extant taxa. The dinosaur peptides localized to fibril ...

  5. National Museum of Natural History: Dinosaur Exhibits

    NSDL National Science Digital Library

    This site from the National Museum of Natural History's (NMNH) Department of Paleobiology offers an enticing peek into the Smithsonian's large dinosaur collection. Users can browse for their favorite dinosaur alphabetically, by dinosaur groups, or by period, and view photos that are accompanied by brief commentary. A Special Tours section offers an Anatomy Lesson, clickable views of Dinosaur Hall, and a Behind the Scenes look at paleobiologists at work. Additional resources include a Geologic Time Scale and a collection of related links.

  6. Dinosaur Names: Common and Science Names

    NSDL National Science Digital Library

    Rick Crosslin

    2004-01-01

    In this activity, learners explore how dinosaurs are named and what their names mean. Learners listen to "The Littlest Dinosaurs" by Bernard Most. Then, learners brainstorm dinosaur names and discover that names are often based on body parts (i.e. rhino means nose). Learners also create drawings of dinosaurs and their body parts in their Dino Diary. This activity is featured on page 10 of the "Dinosphere" unit of study for K-2 learners.

  7. Simulating Dinosaur Digestion in the Classroom.

    ERIC Educational Resources Information Center

    Peczkis, Jan

    1992-01-01

    Describes an activity for use with a chapter on dinosaurs, prehistoric life, or digestion in which children make simulated dinosaur stomachs to gain hands-on experience about the theory of gastroliths, or stomach stones. Presents teacher information about the digestive processes in birds and dinosaurs. Discusses materials needed, objectives,…

  8. Thump, Thump, Thump ... How Dinosaurs Moved

    NSDL National Science Digital Library

    This activity is a printable one-page PDF handout, which focuses on dinosaur movement. Using illustrations that compare a crocodile's hips to a dinosaur's, students answer a series of questions. Fun challenges, Animal Push-Ups and Reptile Races, help students better understand how a hole in the hip socket differentiates dinosaurs from other reptiles.

  9. Plumage Color Patterns of an Extinct Dinosaur

    Microsoft Academic Search

    Quanguo Li; Ke-Qin Gao; Jakob Vinther; Matthew D. Shawkey; Julia A. Clarke; Liliana D'Alba; Qingjin Meng; Derek E. G. Briggs; Richard O. Prum

    2010-01-01

    For as long as dinosaurs have been known to exist, there has been speculation about their appearance. Fossil feathers can preserve the morphology of color-imparting melanosomes, which allow color patterns in feathered dinosaurs to be reconstructed. Here, we have mapped feather color patterns in a Late Jurassic basal paravian theropod dinosaur. Quantitative comparisons with melanosome shape and density in extant

  10. Dinosaurs and the Cretaceous Terrestrial Revolution

    Microsoft Academic Search

    Graeme T. Lloyd; Katie E. Davis; Davide Pisani; James E. Tarver; Marcello Ruta; Manabu Sakamoto; David W. E. Hone; Rachel Jennings; Michael J. Benton

    2008-01-01

    The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125-80 Myr ago, when flowering plants, herbivorous and

  11. Epidemiologic study of tumors in dinosaurs

    Microsoft Academic Search

    B. M. Rothschild; D. H. Tanke; M. Helbling; L. D. Martin

    2003-01-01

    Occasional reports in isolated fragments of dinosaur bones have suggested that tumors might represent a population phenomenon. Previous study of humans has demonstrated that vertebral radiology is a powerful diagnostic tool for population screening. The epidemiology of tumors in dinosaurs was here investigated by fluoroscopically screening dinosaur vertebrae for evidence of tumors. Computerized tomography (CT) and cross-sections were obtained where

  12. Dinosaur Body Temperatures Determined from Isotopic (13

    E-print Network

    Schöne, Bernd R.

    Dinosaur Body Temperatures Determined from Isotopic (13 C-18 O) Ordering in Fossil Biominerals of the nonavian dinosaurs is the subject of debate. Previously, arguments have been made for both endothermic° to 7°C lower than predicted by a model that showed scaling of dinosaur body temperature with mass

  13. Comment on "Evidence for mesothermy in dinosaurs".

    PubMed

    Myhrvold, Nathan P

    2015-05-29

    Grady et al. (Reports, 13 June 2014, p. 1268) studied dinosaur metabolism by comparison of maximum somatic growth rate allometry with groups of known metabolism. They concluded that dinosaurs exhibited mesothermy, a metabolic rate intermediate between endothermy and ectothermy. Multiple statistical and methodological issues call into question the evidence for dinosaur mesothermy. PMID:26023131

  14. Dinosaurs and the Cretaceous Terrestrial Revolution

    E-print Network

    Benton, Michael

    Dinosaurs and the Cretaceous Terrestrial Revolution Graeme T. Lloyd1,*, Katie E. Davis2 , Davide of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50 Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has

  15. The Development of a Virtual Dinosaur Museum

    ERIC Educational Resources Information Center

    Tarng, Wernhuar; Liou, Hsin-Hun

    2007-01-01

    The objective of this article is to study the network and virtual reality technologies for developing a virtual dinosaur museum, which provides a Web-learning environment for students of all ages and the general public to know more about dinosaurs. We first investigate the method for building the 3D dynamic models of dinosaurs, and then describe…

  16. The Evolutionary History of Sauropod Dinosaurs

    Microsoft Academic Search

    Paul Upchurch

    1995-01-01

    Most recent studies of dinosaur phylogeny have concentrated on theropods and ornithischians. As a result, the evolutionary relationships of sauropod dinosaurs are poorly understood. In this paper previous studies of sauropod phylogeny are reviewed and contrasted with the results of a recent cladistic analysis. This analysis forms the basis for a reconstruction of sauropod phylogeny. Sauropods diverged from other dinosaurs

  17. Teaching Perspective The Bristol Dinosaur Project

    E-print Network

    Benton, Michael

    Teaching Perspective The Bristol Dinosaur Project Michael J. Benton *, Remmert Schouten, Edward J. Introduction Dinosaurs have always been an excellent means of science engagement for people of all ages constituency. Owen famously advised on the construction of life- sized concrete models of dinosaurs

  18. Large Mesozoic mammals fed on young dinosaurs

    E-print Network

    Sullivan, Jack

    dinosaurs Yaoming Hu1,2,3 , Jin Meng2 , Yuanqing Wang1 & Chuankui Li1 1 Institute of Vertebrate Paleontology, probably noctur- nal and lived in the shadow of dinosaurs1­5 . The largest known Mesozoic mammal- saurus, a ceratopsian dinosaur. Our discoveries constitute the first direct evidence that some

  19. Measuring Dinosaur Speed from Trackways

    NSDL National Science Digital Library

    Bret Bennington

    By measuring the spacing of fossil footprints it is possible to estimate the speed of the trackmaker, but only after making several assumptions based on footprint size and the behavior of a wide range of living animals. A widely applied method for estimating speed from trackways was developed through the research of R. McNeill Alexander, an expert in biomechanics. This lab is a group exercise designed to lead students step-by-step through the methods and principles involved in estimating speed of movement from trackway data using Alexander's method. First students test the method on humans to see how accurate it is, and then they apply it to measurements taken from a variety of dinosaur trackways. This activity involves having students collect speed and footprint data on subjects while they are running and walking. The footprint data are analyzed and the speed estimates are compared to the actual measured speeds. Students then collect trackway measurements from published illustrations of dinosaur trackways to estimate dinosaur speeds. Students calculate the percent error for their experimental estimates and use this to interpret the results obtained from dinosaur trackways. Spreadsheets may be used to record and carry out the calculations in the analysis. Students are asked to discuss the significance of their results to ongoing debates over the physical capabilities of dinosaurs.

  20. The earliest known sauropod dinosaur.

    PubMed

    Buffetaut, E; Suteethorn, V; Cuny, G; Tong, H; Le Loeuff, J; Khansubha, S; Jongautchariyakul, S

    2000-09-01

    Sauropods were a very successful group of dinosaurs during the Jurassic and Cretaceous periods, but their earlier history is poorly known. Until now, the earliest reported sauropod bones were from the Early Jurassic, and the only tentative evidence of earlier sauropods was in the form of controversial footprints. Here we report the discovery of an incomplete sauropod skeleton from the Late Triassic period of Thailand, which provides the first osteological evidence of pre-Jurassic sauropods. This dinosaur is markedly different from prosauropods and substantiates theoretical predictions that there was a fairly long period of sauropod evolution during the Triassic. PMID:10993074

  1. Binocular vision in theropod dinosaurs

    Microsoft Academic Search

    Kent A. Stevens

    2006-01-01

    The binocular fields of view of seven theropod dinosaurs are mapped using sculpted life reconstructions of their heads and techniques adopted from ophthalmic field perimetry. The tall, narrow snout and laterally facing eyes of the allosauroids Allosaurus and Carcharodontosaurus restricted binocular vision to a region only approximately 20° wide, comparable to that of modern crocodiles. In contrast, the coelurosaurs Daspletosaurus,

  2. Allometry in dinosaurs and mammals

    NASA Astrophysics Data System (ADS)

    Lee, Scott

    2015-03-01

    The proportions of the leg bones change as the size of an animal becomes larger since the mass of the animal increases at a faster rate than the cross-sectional area of its leg bones. For the case of elastic similarity (in which the longitudinal stress in the legs remains constant in animals of all sizes), the diameter d and length L of the femur should be related as d = A L3/2. For geometric similarity (in which all dimensions are scaled by the same factor), d = A L. For animals with femora longer than 20 cm, we find the power law relationship to be d = A Lb with b = 1.13 +/- 0.06 for extant mammals (the largest mammal being Loxodonta africana with a 1.00-m-long femur) and b = 1.18 +/- 0.02 for dinosaurs (the largest dinosaur being Brachiosaurus brancai with a 2.03-m-long femur). These data show that extinct dinosaurs and extant animals scale in the same basic manner. The large sauropods (with femora twice as long as found in elephants) scale in a manner consistent with extrapolation of the scaling shown by extant mammals. These results argue that extinct dinosaurs moved in a manner very similar to extant mammals.

  3. Evolution: Convergence in Dinosaur Crests.

    PubMed

    Hone, David W E

    2015-06-15

    The horned, ceratopsid dinosaurs can be easily split into two major groups based on their cranial structures, but now a new discovery shows that at least one genus 'switched sides' and convergently evolved the form of the other clade. PMID:26079078

  4. The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962

    E-print Network

    The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial 27 August 2010 The cranial anatomy of the Lower Jurassic ornithischian dinosaur Heterodontosaurus commonly seen in basal archosaurs and saurischian dinosaurs). Evidence for tooth replacement (which has

  5. New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism

    Microsoft Academic Search

    Scott D. Sampson; Mark A. Loewen; Andrew A. Farke; Eric M. Roberts; Catherine A. Forster; Joshua A. Smith; Alan L. Titus; Anna Stepanova

    2010-01-01

    BackgroundDuring much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have

  6. Activation, Proliferation and Commitment of Endogenous Stem\\/Progenitor Cells to the Oligodendrocyte Lineage by TS1 in a Rat Model of Dysmyelination

    Microsoft Academic Search

    Araceli Espinosa-Jeffrey; Paul Zhao; Wole Awosika; Nanping Wu; Fernando Macias; Carlos Cepeda; Michael Levine; Jean de Vellis

    2006-01-01

    Wild-type and myelin-deficient rats received a single intraparenchymal injection of TS1, a specific combination of IGF-1 and transferrin (Tf), into their corpus callosum at postnatal day 4. The fate of endogenous stem cells in the brain was examined by the expression of the stem cell marker nestin, together with Tf, neurofilaments and glial fibrillary acidic protein from 2 to 14

  7. Network representation of a child's dinosaur knowledge

    Microsoft Academic Search

    Michelene T. Chi; Randi D. Koeske

    1983-01-01

    A 4-yr-old male's knowledge of 40 dinosaurs was elicited from 2 tasks. The data gathered from these knowledge-production protocols were used to map 2 interrelated semantic networks of dinosaurs, viewed as concept nodes connected by links. The 2 mappings corresponded to 2 sets of dinosaurs (20 each), partitioned on the basis of external criteria: mother's subjective judgment of the S's

  8. Stems

    NSDL National Science Digital Library

    Olivia Worland (Purdue University; Biological Sciences)

    2008-06-03

    Some mature plants can produce new plants by cutting a piece of stem off of the original plant. Most members of the mint family and ivy family can do this readily. The new plant will grow its own root system.

  9. Tramline Virtual Field Trips: Dinosaurs Field Trip

    NSDL National Science Digital Library

    Hughes-Feletar, Theresa

    Hosted by Tramline Virtual Field Trips, this online field trip was created by educator Theresa Hughes-Feletar to teach young students (grades 1-3) about dinosaurs. Hughes-Feletar's virtual field trip links to a variety of quality websites about dinosaurs to create an integrated learning experience. The field trip links -- or Stops as the website refers to them -- provide information about dinosaur reproduction, fossils, hunting, extinction, and more. A supplemental Teacher's Resources page includes recommended book and music lists, as well as dinosaur curriculum ideas for subjects such as science, math, and art.

  10. Geology Fieldnotes: Dinosaur National Monument, Colorado / Utah

    NSDL National Science Digital Library

    Dinosaur National Monument preserves a fossil bone deposit containing the bones of hundreds of dinosaurs, which was once enclosed in the sands of an ancient river. Features of the site include park geology information, maps, photographs, related links, visitor information, multimedia resources, and resources for teaching geology with National Park examples. The geology section discusses the park's geologic history and fossil beds. A park map of the Monument is included, and the photo album section contains drawings of some of the dinosaur species found at the Monument's Dinosaur Quarry.

  11. The Four-Winged Dinosaur

    NSDL National Science Digital Library

    Tasha Dunn

    For this actiivty the students will watch a Nova documentary called "The Four-Winged Dinosaur." The documentary follows two teams of scientists as they create replicas of microraptor, a dinosaur with four feathered wings, in an attempt to determine how flight evolved in birds (from the ground up or from the trees down). As the students watch the video, they should think about each hypothesis and pay attention to the lines of evidence presented on both sides of the argument. The students are given specific questions to answer while watching the video that will help them pay attention to key ideas. Outside of class they are responsible for writing a short essay (~1 page, typed) describing which origin of flight hypothesis that they believe is the most plausible and why. Students must support their argument with evidence presented in the video.

  12. Could you outrun a dinosaur

    NSDL National Science Digital Library

    Bill Ausich

    After looking at vertebrate skeletons and viewing videos dealing with vertebrates, this is a hands-on exercise with data the students can gather from simulated dinosaur trackways. To scale footprints (cut from poster board) are taped to the hallway floor; one of a bipedal theropod and one a quadrapedal sauropod. Students make the appropriate measurements directly from the simulated trackways. These data, plus additional data provided, are the basis for calculations necessary to calculate speed. With this information, various questions are answered.

  13. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs.

    PubMed

    Wilson, Gregory P; Evans, Alistair R; Corfe, Ian J; Smits, Peter D; Fortelius, Mikael; Jernvall, Jukka

    2012-03-22

    The Cretaceous-Paleogene mass extinction approximately 66 million years ago is conventionally thought to have been a turning point in mammalian evolution. Prior to that event and for the first two-thirds of their evolutionary history, mammals were mostly confined to roles as generalized, small-bodied, nocturnal insectivores, presumably under selection pressures from dinosaurs. Release from these pressures, by extinction of non-avian dinosaurs at the Cretaceous-Paleogene boundary, triggered ecological diversification of mammals. Although recent individual fossil discoveries have shown that some mammalian lineages diversified ecologically during the Mesozoic era, comprehensive ecological analyses of mammalian groups crossing the Cretaceous-Paleogene boundary are lacking. Such analyses are needed because diversification analyses of living taxa allow only indirect inferences of past ecosystems. Here we show that in arguably the most evolutionarily successful clade of Mesozoic mammals, the Multituberculata, an adaptive radiation began at least 20 million years before the extinction of non-avian dinosaurs and continued across the Cretaceous-Paleogene boundary. Disparity in dental complexity, which relates to the range of diets, rose sharply in step with generic richness and disparity in body size. Moreover, maximum dental complexity and body size demonstrate an adaptive shift towards increased herbivory. This dietary expansion tracked the ecological rise of angiosperms and suggests that the resources that were available to multituberculates were relatively unaffected by the Cretaceous-Paleogene mass extinction. Taken together, our results indicate that mammals were able to take advantage of new ecological opportunities in the Mesozoic and that at least some of these opportunities persisted through the Cretaceous-Paleogene mass extinction. Similar broad-scale ecomorphological inventories of other radiations may help to constrain the possible causes of mass extinctions. PMID:22419156

  14. First ceratosaurian dinosaur from Australia.

    PubMed

    Fitzgerald, Erich M G; Carrano, Matthew T; Holland, Timothy; Wagstaff, Barbara E; Pickering, David; Rich, Thomas H; Vickers-Rich, Patricia

    2012-05-01

    The basal theropod dinosaur clade Ceratosauria, and its subclade Abelisauroidea, is characteristic of late Mesozoic terrestrial vertebrate faunas in western Gondwana (South America, Africa, Madagascar, and India) and Europe. Yet unambiguous records of ceratosaurs have hitherto been absent from Australia, where the theropod assemblage appears to include several typically Laurasian clades. Here, we report the first evidence of ceratosaurs (and potentially abelisauroids) from eastern Gondwana--a diagnostic astragalocalcaneum from the Aptian (121-125 Ma) of Victoria, Australia. Ceratosauria thus occurred in both western and eastern Gondwana during the Early Cretaceous. This fossil adds to the poorly known dinosaur fauna of Australia, a major clade of basal theropods, emphasising that its mid-Cretaceous theropod diversity was surprisingly cosmopolitan despite relative geographic isolation, including clades that have been thought to be typical of both Gondwana and Laurasia--Ceratosauria, Spinosauridae, Carcharodontosauria, Tyrannosauroidea, and Deinonychosauria. Such a contemporaneous association of theropod clades is unknown from other Gondwanan continents and questions the views that the late Mesozoic dinosaur fauna of Australia was dominated by Gondwanan or Laurasian elements, extreme isolation, relictualism, and/or novelty as a 'centre of origin'. The cosmopolitan theropod fauna of Australia probably reflects the global distribution of these clades early in their history, prior to significant continental breakup. PMID:22552426

  15. First ceratosaurian dinosaur from Australia

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Erich M. G.; Carrano, Matthew T.; Holland, Timothy; Wagstaff, Barbara E.; Pickering, David; Rich, Thomas H.; Vickers-Rich, Patricia

    2012-05-01

    The basal theropod dinosaur clade Ceratosauria, and its subclade Abelisauroidea, is characteristic of late Mesozoic terrestrial vertebrate faunas in western Gondwana (South America, Africa, Madagascar, and India) and Europe. Yet unambiguous records of ceratosaurs have hitherto been absent from Australia, where the theropod assemblage appears to include several typically Laurasian clades. Here, we report the first evidence of ceratosaurs (and potentially abelisauroids) from eastern Gondwana--a diagnostic astragalocalcaneum from the Aptian (121-125 Ma) of Victoria, Australia. Ceratosauria thus occurred in both western and eastern Gondwana during the Early Cretaceous. This fossil adds to the poorly known dinosaur fauna of Australia, a major clade of basal theropods, emphasising that its mid-Cretaceous theropod diversity was surprisingly cosmopolitan despite relative geographic isolation, including clades that have been thought to be typical of both Gondwana and Laurasia--Ceratosauria, Spinosauridae, Carcharodontosauria, Tyrannosauroidea, and Deinonychosauria. Such a contemporaneous association of theropod clades is unknown from other Gondwanan continents and questions the views that the late Mesozoic dinosaur fauna of Australia was dominated by Gondwanan or Laurasian elements, extreme isolation, relictualism, and/or novelty as a `centre of origin'. The cosmopolitan theropod fauna of Australia probably reflects the global distribution of these clades early in their history, prior to significant continental breakup.

  16. Cell Lineages of the Embryo of the Nematode Caenorhabditis elegans

    Microsoft Academic Search

    Uwe Deppe; Einhard Schierenberg; Thomas Cole; Christian Krieg; David Schmitt; Bonita Yoder; Gunter von Ehrenstein

    1978-01-01

    Embryogenesis of the free-living soil nematode Caenorhabditis elegans produces a juvenile having about 550 cells at hatching. We have determined the lineages of 182 cells by tracing the divisions of individual cells in living embryos. An invariant pattern of cleavage divisions of the egg generates a set of stem cells. These stem cells are the founders of six stem cell

  17. Dynamic Locomotor Capabilities Revealed by Early Dinosaur Trackmakers from Southern Africa

    PubMed Central

    Wilson, Jeffrey A.; Marsicano, Claudia A.; Smith, Roger M. H.

    2009-01-01

    Background A new investigation of the sedimentology and ichnology of the Early Jurassic Moyeni tracksite in Lesotho, southern Africa has yielded new insights into the behavior and locomotor dynamics of early dinosaurs. Methodology/Principal Findings The tracksite is an ancient point bar preserving a heterogeneous substrate of varied consistency and inclination that includes a ripple-marked riverbed, a bar slope, and a stable algal-matted bar top surface. Several basal ornithischian dinosaurs and a single theropod dinosaur crossed its surface within days or perhaps weeks of one another, but responded to substrate heterogeneity differently. Whereas the theropod trackmaker accommodated sloping and slippery surfaces by gripping the substrate with its pedal claws, the basal ornithischian trackmakers adjusted to the terrain by changing between quadrupedal and bipedal stance, wide and narrow gauge limb support (abduction range?=?31°), and plantigrade and digitigrade foot posture. Conclusions/Significance The locomotor adjustments coincide with changes in substrate consistency along the trackway and appear to reflect ‘real time’ responses to a complex terrain. It is proposed that these responses foreshadow important locomotor transformations characterizing the later evolution of the two main dinosaur lineages. Ornithischians, which shifted from bipedal to quadrupedal posture at least three times in their evolutionary history, are shown to have been capable of adopting both postures early in their evolutionary history. The substrate-gripping behavior demonstrated by the early theropod, in turn, is consistent with the hypothesized function of pedal claws in bird ancestors. PMID:19806213

  18. Sauropod dinosaur osteoderms from the Late Cretaceous of Madagascar.

    PubMed

    Curry Rogers, Kristina; D'Emic, Michael; Rogers, Raymond; Vickaryous, Matthew; Cagan, Amanda

    2011-01-01

    Osteoderms are bones embedded within the dermis, and are common to select members of most major tetrapod lineages. The largest known animals that bear osteoderms are members of Titanosauria, a diverse clade of sauropod dinosaurs. Here we report on two titanosaur osteoderms recovered from the Upper Cretaceous Maevarano Formation of Madagascar. Each osteoderm was discovered in association with a partial skeleton representing a distinct ontogenetic stage of the titanosaur Rapetosaurus krausei. Combined, these specimens provide novel insights into the arrangement and function of titanosaur osteoderms. Taphonomic data confirm that Rapetosaurus developed only limited numbers of osteoderms in its integument. The adult-sized osteoderm is the most massive integumentary skeletal element yet discovered, with an estimated volume of 9.63?litres. Uniquely, this specimen possesses an internal cavity equivalent to more than half its total volume. Large, hollow osteoderms may have functioned as mineral stores in fecund, rapidly growing titanosaurs inhabiting stressed environments. PMID:22127060

  19. Early ornithischian dinosaurs: the Triassic record

    Microsoft Academic Search

    Randall B. Irmis; William G. Parker; Sterling J. Nesbitt; Jun Liu

    2007-01-01

    Ornithischian dinosaurs are one of the most taxonomically diverse dinosaur clades during the Mesozoic, yet their origin and early diversification remain virtually unknown. In recent years, several new Triassic ornithischian taxa have been proposed, mostly based upon isolated teeth. New discoveries of skeletal material of some of these tooth taxa indicate that these teeth can no longer be assigned to

  20. 3D-MODELLING OF DINOSAURS

    Microsoft Academic Search

    Anke Bellmann; Tim Suthau; Stefan Stoinski; Andreas Friedrich; Olaf Hellwich; Hanns-Christian Gunga

    The paper gives a detailed report on investigations of dinosaur skeletons being conducted to collect data on dinosaurs' life history. A large quantity of physiological data can be derived if the properties of living animals are inferred, e.g. body volume (body mass) and body surface area, using the methods of comparative physiology. These values can be determined through the use

  1. Origins and Evolution of Ornithischian Dinosaurs

    Microsoft Academic Search

    Richard A. Thulborn

    1971-01-01

    Recent discoveries in the red beds of the Upper Trias have shed light on the history of the ornithischian dinosaurs. It is suggested that these dinosaurs had a monophyletic origin among advanced pseudosuchian thecodonts. Development of their rather bird-like pelvis involved backwards rotation of the pubis and subsequent growth of a prepubis. A conservative stock of primitive-looking hypsilophodonts, which persisted

  2. Comment on "Evidence for mesothermy in dinosaurs".

    PubMed

    D'Emic, M D

    2015-05-29

    Grady et al. (Reports, 13 June 2014, p. 1268) suggested that nonavian dinosaur metabolism was neither endothermic nor ectothermic but an intermediate physiology termed "mesothermic." However, rates were improperly scaled and phylogenetic, physiological, and temporal categories of animals were conflated during analyses. Accounting for these issues suggests that nonavian dinosaurs were on average as endothermic as extant placental mammals. PMID:26023130

  3. Evidence of intestinal parasites of dinosaurs.

    PubMed

    Poinar, G; Boucot, A J

    2006-08-01

    Protozoan cysts and helminth eggs preserved in a coprolite from the Early Cretaceous Bernissart Iguanodon shaft in Belgium demonstrate that representatives of 3 phyla parasitized dinosaurs by that period. These fossil parasite stages are described and their possible effect on dinosaurs discussed. These findings represent the earliest fossil records of protozoan and helminth parasites of terrestrial vertebrates. PMID:16623965

  4. Body Size Distribution of the Dinosaurs

    PubMed Central

    O’Gorman, Eoin J.; Hone, David W. E.

    2012-01-01

    The distribution of species body size is critically important for determining resource use within a group or clade. It is widely known that non-avian dinosaurs were the largest creatures to roam the Earth. There is, however, little understanding of how maximum species body size was distributed among the dinosaurs. Do they share a similar distribution to modern day vertebrate groups in spite of their large size, or did they exhibit fundamentally different distributions due to unique evolutionary pressures and adaptations? Here, we address this question by comparing the distribution of maximum species body size for dinosaurs to an extensive set of extant and extinct vertebrate groups. We also examine the body size distribution of dinosaurs by various sub-groups, time periods and formations. We find that dinosaurs exhibit a strong skew towards larger species, in direct contrast to modern day vertebrates. This pattern is not solely an artefact of bias in the fossil record, as demonstrated by contrasting distributions in two major extinct groups and supports the hypothesis that dinosaurs exhibited a fundamentally different life history strategy to other terrestrial vertebrates. A disparity in the size distribution of the herbivorous Ornithischia and Sauropodomorpha and the largely carnivorous Theropoda suggests that this pattern may have been a product of a divergence in evolutionary strategies: herbivorous dinosaurs rapidly evolved large size to escape predation by carnivores and maximise digestive efficiency; carnivores had sufficient resources among juvenile dinosaurs and non-dinosaurian prey to achieve optimal success at smaller body size. PMID:23284818

  5. theropod dinosaurs. The absence of respiratory turbinates in

    E-print Network

    theropod dinosaurs. The absence of respiratory turbinates in theropod dinosaurs indicates of dinosaurs to have achieved ac- tive rates of O2-CO2 exchange that might have approached, or even overlapped in theropods indicates that, although these dinosaurs maintained ectotherm-like routine metabolic rates

  6. Q:China and dinosaurs: what's the connection?

    E-print Network

    Q:China and dinosaurs: what's the connection? China and dinosaurs: what's the connection? MSU N 10 by visiting Montana.edu/outreach Scientists discovered a four-winged dinosaur from China that was the size of a turkey. Did you know?Did you know? What does China have to do with dinosaurs? Some of the most well

  7. Dinosaur Locomotion John R Hutchinson, Stanford University, California, USA

    E-print Network

    Hutchinson, John

    Dinosaur Locomotion John R Hutchinson, Stanford University, California, USA Many lines of evidence must be used to understand dinosaur locomotion: how extinct dinosaurs moved. Introduction: What Evidence and Methods are Useful for Studying Dinosaur Locomotion? Several lines of inquiry offer clues

  8. The Evolution of Dinosaurs Over Geologic Time

    NSDL National Science Digital Library

    This lesson plan asks high school students to combine their knowledge of evolution, geologic time, and dinosaurs into a discussion of how these three topics overlap with regard to dinosaur evolution in the Cretaceous period. Students will read about the work of paleontologist Paul Sereno and list the dinosaurs he has discovered as well as the locations in which they were found and the time periods in which they lived; review the periods of geologic time; review the theory of evolution and write a paragraph explaining how geographic isolation would contribute to the evolutionary process; write paragraphs describing the changes to the continental layout of the Earth during the Cretaceous period; write paragraphs relating geological changes to dinosaur evolution during the Cretaceous period; and create posters or computer presentations illustrating the Earth during the Cretaceous period and the evolution processes of dinosaur species during this time.

  9. Inferring the Possible Speeds of Dinosaurs?

    NSDL National Science Digital Library

    John Hutchinson

    Several lines of evidence are presented in this text that can help us estimate how dinosaurs could move. A good sequence of preserved footprints (called a trackway) can be extrapolated to give a rough estimate of how fast a particular animal was traveling at that moment. The morphology (shape and structure, or anatomy) of dinosaurs may be a more useful tool, but it is much more difficult to use properly. We can compare dinosaurs with extant (living) animals whose motion we understand better, and make assumptions based on the similarities and differences between the two. This is called the morphological paradigm. We can use the laws of physics and apply them to our dinosaurs. This is called biomechanics. Specific dinosaurs are used as examples and active links lead to more information on each.

  10. Dinosaur Tracksites of the Paluxy River Valley (Glen Rose Formation, Lower Cretaceous), Dinosaur Valley State Park, Somervell County, Texas

    E-print Network

    Falkingham, Peter

    41 Dinosaur Tracksites of the Paluxy River Valley (Glen Rose Formation, Lower Cretaceous), Dinosaur Glen Rose, Cretácico Inferior), Dinosaur Valley State Park, Condado de Somervell, Tejas J. O. Farlow1 Formation; Lower Cretaceous) of the Paluxy River, in what is now Dinosaur Valley State Park (Glen Rose

  11. Genes from the APETALA3 and PISTILLATA Lineages are Expressed in Developing Vascular Bundles of the Tuberous Rhizome, Flowering Stem and Flower Primordia of Eranthis hyemalis

    PubMed Central

    SKIPPER, MARTIN

    2002-01-01

    In Arabidopsis thaliana expression of the B?class MADS?box genes APETALA3 (AP3) and PISTILLATA (PI) is confined to petals and stamens but in other plant species these genes are also transcribed in non?flower tissues; in Solanum tuberosum they are transcribed specifically in vascular bundles leading to petals and stamens. Transcription analysis of B?class genes in Eranthis hyemalis using reverse transcribed in situ PCR revealed that both AP3 and PI are expressed in developing vascular bundles in the tuberous rhizome, flowering stem and floral primordia. In addition, AP3 and PI transcripts are also found in stems and leaves. These results suggest a more complex role of B?class genes in Eranthis and possible involvement in the development of vascular tissue. PMID:12096822

  12. The Genetic Engineering of Hematopoietic Stem Cells: the Rise of Lentiviral Vectors, the Conundrum of the LTR, and the Promise of Lineage-restricted Vectors

    Microsoft Academic Search

    Alex H Chang; Michel Sadelain

    2007-01-01

    Recent studies on the integration patterns of different categories of retroviral vectors, the genotoxicity of long-terminal repeats (LTRs) and other genetic elements, the rise of lentiviral technology and the emergence of regulated vector systems providing tissue-restricted transgene expression and RNA interference, are profoundly changing the landscape of stem cell-based therapies. New developments in vector design and an increasing understanding of

  13. Macrophage-Lineage Cells Negatively Regulate the Hematopoietic Stem Cell Pool in Response to Interferon Gamma at Steady State and During Infection.

    PubMed

    McCabe, Amanda; Zhang, Yubin; Thai, Vinh; Jones, Maura; Jordan, Michael B; MacNamara, Katherine C

    2015-07-01

    Bone marrow (BM) resident macrophages (M?s) regulate hematopoietic stem cell (HSC) mobilization; however, their impact on HSC function has not been investigated. We demonstrate that depletion of BM resident M?s increases HSC proliferation as well as the pool of quiescent HSCs. At the same time, during bacterial infection where BM resident M?s are selectively increased we observe a decrease in HSC numbers. Moreover, strategies that deplete or reduce M?s during infection prevent HSC loss and rescue HSC function. We previously found that the transient loss of HSCs during infection is interferon-gamma (IFN?)-dependent. We now demonstrate that IFN? signaling specifically in M?s is critical for both the diminished HSC pool and maintenance of BM resident M?s during infection. In addition to the IFN?-dependent loss of BM HSC and progenitor cells (HSPCs) during infection, IFN? reduced circulating HSPC numbers. Importantly, under infection conditions AMD3100 or G-CSF-induced stem cell mobilization was impaired. Taken together, our data show that IFN? acts on M?s, which are a negative regulator of the HSC pool, to drive the loss in BM and peripheral HSCs during infection. Our findings demonstrate that modulating BM resident M? numbers can impact HSC function in vivo, which may be therapeutically useful for hematologic conditions and refinement of HSC transplantation protocols. Stem Cells 2015;33:2294-2305. PMID:25880153

  14. Ectoderm to Mesoderm Lineage Switching During Axolotl Tail Regeneration

    Microsoft Academic Search

    Karen Echeverri; Elly M. Tanaka

    2002-01-01

    Foreign environments may induce adult stem cells to switch lineages and populate multiple tissue types, but whether this mechanism is used for tissue repair remains uncertain. Urodele amphibians can regenerate fully functional, multitissue structures including the limb and tail. To determine whether lineage switching is an integral feature of this regeneration, we followed individual spinal cord cells live during tail

  15. Biology of the sauropod dinosaurs: the evolution of gigantism

    PubMed Central

    Sander, P Martin; Christian, Andreas; Clauss, Marcus; Fechner, Regina; Gee, Carole T; Griebeler, Eva-Maria; Gunga, Hanns-Christian; Hummel, Jürgen; Mallison, Heinrich; Perry, Steven F; Preuschoft, Holger; Rauhut, Oliver W M; Remes, Kristian; Tütken, Thomas; Wings, Oliver; Witzel, Ulrich

    2011-01-01

    The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism. We review the biology of sauropod dinosaurs in detail and posit that sauropod gigantism was made possible by a specific combination of plesiomorphic characters (phylogenetic heritage) and evolutionary innovations at different levels which triggered a remarkable evolutionary cascade. Of these key innovations, the most important probably was the very long neck, the most conspicuous feature of the sauropod bauplan. Compared to other herbivores, the long neck allowed more efficient food uptake than in other large herbivores by covering a much larger feeding envelope and making food accessible that was out of the reach of other herbivores. Sauropods thus must have been able to take up more energy from their environment than other herbivores. The long neck, in turn, could only evolve because of the small head and the extensive pneumatization of the sauropod axial skeleton, lightening the neck. The small head was possible because food was ingested without mastication. Both mastication and a gastric mill would have limited food uptake rate. Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates. The extensive pneumatization of the axial skeleton resulted from the evolution of an avian-style respiratory system, presumably at the base of Saurischia. An avian-style respiratory system would also have lowered the cost of breathing, reduced specific gravity, and may have been important in removing excess body heat. Another crucial innovation inherited from basal dinosaurs was a high BMR. This is required for fueling the high growth rate necessary for a multi-tonne animal to survive to reproductive maturity. The retention of the plesiomorphic oviparous mode of reproduction appears to have been critical as well, allowing much faster population recovery than in megaherbivore mammals. Sauropods produced numerous but small offspring each season while land mammals show a negative correlation of reproductive output to body size. This permitted lower population densities in sauropods than in megaherbivore mammals but larger individuals. Our work on sauropod dinosaurs thus informs us about evolutionary limits to body size in other groups of herbivorous terrestrial tetrapods. Ectothermic reptiles are strongly limited by their low BMR, remaining small. Mammals are limited by their extensive mastication and their vivipary, while ornithsichian dinosaurs were only limited by their extensive mastication, having greater average body sizes than mammals. PMID:21251189

  16. N-Q Dinosaur Bones

    NSDL National Science Digital Library

    2012-05-01

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Quincy is a tour guide at a museum of science and history. During a tour of the museum, he tells some visitors about a fossilized dinosaur bone that is...

  17. Cell Lineage and Segmentation in the Leech

    Microsoft Academic Search

    D. A. Weisblat; M. Shankland

    1985-01-01

    Segments in the leech arise by the proliferation of longitudinally arrayed bandlets of blast cells derived from ten identifiable embryonic stem cells, two M, two N, four O\\/P and two Q teloblasts. In each bandlet, older blast cells lie ahead of those born later. By using microinjected cell lineage tracers it was shown previously that the teloblasts give rise to

  18. Derivation of Mesenchymal Stromal Cells from Pluripotent Stem Cells through a Neural Crest Lineage using Small Molecule Compounds with Defined Media

    PubMed Central

    Nakagawa, Masato; Sekiguchi, Kazuya; Nagata, Sanae; Matsumoto, Yoshihisa; Yamamoto, Takuya; Umeda, Katsutsugu; Heike, Toshio; Okumura, Naoki; Koizumi, Noriko; Sato, Takahiko; Nakahata, Tatsutoshi; Saito, Megumu; Otsuka, Takanobu; Kinoshita, Shigeru; Ueno, Morio; Ikeya, Makoto; Toguchida, Junya

    2014-01-01

    Neural crest cells (NCCs) are an embryonic migratory cell population with the ability to differentiate into a wide variety of cell types that contribute to the craniofacial skeleton, cornea, peripheral nervous system, and skin pigmentation. This ability suggests the promising role of NCCs as a source for cell-based therapy. Although several methods have been used to induce human NCCs (hNCCs) from human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), further modifications are required to improve the robustness, efficacy, and simplicity of these methods. Chemically defined medium (CDM) was used as the basal medium in the induction and maintenance steps. By optimizing the culture conditions, the combination of the GSK3? inhibitor and TGF? inhibitor with a minimum growth factor (insulin) very efficiently induced hNCCs (70–80%) from hPSCs. The induced hNCCs expressed cranial NCC-related genes and stably proliferated in CDM supplemented with EGF and FGF2 up to at least 10 passages without changes being observed in the major gene expression profiles. Differentiation properties were confirmed for peripheral neurons, glia, melanocytes, and corneal endothelial cells. In addition, cells with differentiation characteristics similar to multipotent mesenchymal stromal cells (MSCs) were induced from hNCCs using CDM specific for human MSCs. Our simple and robust induction protocol using small molecule compounds with defined media enabled the generation of hNCCs as an intermediate material producing terminally differentiated cells for cell-based innovative medicine. PMID:25464501

  19. The Rod Photoreceptor Lineage of Teleost Fish

    PubMed Central

    Stenkamp, Deborah L.

    2011-01-01

    The retinas of postembryonic teleost fish continue to grow for the lifetime of the fish. New retinal cells are added continuously at the retinal margin, by stem cells residing at the circumferential germinal zone. Some of these retinal cells differentiate as Müller glia with cell bodies that reside within the inner nuclear layer. These glia retain some stem cell properties in that they carry out asymmetric cell divisions and continuously generate a population of transit-amplifying cells – the rod photoreceptor lineage – that are committed to rod photoreceptor neurogenesis. These rod progenitors progress through a stereotyped sequence of changes in gene expression as they continue to divide and migrate to the outer nuclear layer. Now referred to as rod precursors, they undergo terminal mitoses and then differentiate as rods, which are inserted into the existing array of rod and cone photoreceptors. The rod lineage displays developmental plasticity, as rod precursors can respond to the loss of rods through increased proliferation, resulting in rod replacement. The stem cells of the rod lineage, Müller glia, respond to acute damage of other retinal cell types by increasing their rate of proliferation. In addition, the Müller glia in an acutely damaged retina dedifferentiate and become multipotent, generating new, functional neurons. This review focuses on the cells of the rod lineage and includes discussions of experiments over the last 30 years that led to their identification and characterization, and the discovery of the stem cells residing at the apex of the lineage. The plasticity of cells of the rod lineage, their relationships to cone progenitors, and the applications of this information for developing future treatments for human retinal disorders will also be discussed. PMID:21742053

  20. An Evolutionary Cascade Model for Sauropod Dinosaur Gigantism - Overview, Update and Tests

    PubMed Central

    Sander, P. Martin

    2013-01-01

    Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades (“Reproduction”, “Feeding”, “Head and neck”, “Avian-style lung”, and “Metabolism”). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait “Very high body mass”. Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size. PMID:24205267

  1. Targeted Disruption in Mice of a Neural Stem Cell-Maintaining, KRAB-Zn Finger-Encoding Gene That Has Rapidly Evolved in the Human Lineage

    PubMed Central

    Lai, Kuan-Yu; Lu, Li-Chen; Chen, Pau-Chung; Tsai, Shih-Feng; Wu, Chung-I; Hsieh, Wu-Shiun; Shen, Che-Kun James

    2012-01-01

    Understanding the genetic basis of the physical and behavioral traits that separate humans from other primates is a challenging but intriguing topic. The adaptive functions of the expansion and/or reduction in human brain size have long been explored. From a brain transcriptome project we have identified a KRAB-Zn finger protein-encoding gene (M003-A06) that has rapidly evolved since the human-chimpanzee separation. Quantitative RT-PCR analysis of different human tissues indicates that M003-A06 expression is enriched in the human fetal brain in addition to the fetal heart. Furthermore, analysis with use of immunofluorescence staining, neurosphere culturing and Western blotting indicates that the mouse ortholog of M003-A06, Zfp568, is expressed mainly in the embryonic stem (ES) cells and fetal as well as adult neural stem cells (NSCs). Conditional gene knockout experiments in mice demonstrates that Zfp568 is both an NSC maintaining- and a brain size-regulating gene. Significantly, molecular genetic analyses show that human M003-A06 consists of 2 equilibrated allelic types, H and C, one of which (H) is human-specific. Combined contemporary genotyping and database mining have revealed interesting genetic associations between the different genotypes of M003-A06 and the human head sizes. We propose that M003-A06 is likely one of the genes contributing to the uniqueness of the human brain in comparison to other higher primates. PMID:23071813

  2. Two Feathered Dinosaurs From Northeastern China

    NSDL National Science Digital Library

    Currie, Philip J.

    1998-01-01

    The Nature Web Special (discussed in the April 29, 1998 Scout Report for Science & Engineering), concerns the discovery by Canadian, Chinese, and American researchers of two species of "theropod dinosaur from China -­ dinosaurs with feathers." The Nature site includes a press release, commentary by Kevin Padian of the Department of Integrative Biology and the Museum of Paleontology, University of California, Berkeley, and full text of the article: "Two feathered dinosaurs from northeastern China," (Nature 393, 753-761; 1998), by Quang Ji, et al.

  3. C/EBP? Is Required for Long-Term Self-Renewal and Lineage Priming of Hematopoietic Stem Cells and for the Maintenance of Epigenetic Configurations in Multipotent Progenitors

    PubMed Central

    Hasemann, Marie S.; Lauridsen, Felicia K. B.; Waage, Johannes; Jakobsen, Janus S.; Frank, Anne-Katrine; Schuster, Mikkel B.; Rapin, Nicolas; Bagger, Frederik O.; Hoppe, Philipp S.; Schroeder, Timm; Porse, Bo T.

    2014-01-01

    Transcription factors are key regulators of hematopoietic stem cells (HSCs) and act through their ability to bind DNA and impact on gene transcription. Their functions are interpreted in the complex landscape of chromatin, but current knowledge on how this is achieved is very limited. C/EBP? is an important transcriptional regulator of hematopoiesis, but its potential functions in HSCs have remained elusive. Here we report that C/EBP? serves to protect adult HSCs from apoptosis and to maintain their quiescent state. Consequently, deletion of Cebpa is associated with loss of self-renewal and HSC exhaustion. By combining gene expression analysis with genome-wide assessment of C/EBP? binding and epigenetic configurations, we show that C/EBP? acts to modulate the epigenetic states of genes belonging to molecular pathways important for HSC function. Moreover, our data suggest that C/EBP? acts as a priming factor at the HSC level where it actively promotes myeloid differentiation and counteracts lymphoid lineage choice. Taken together, our results show that C/EBP? is a key regulator of HSC biology, which influences the epigenetic landscape of HSCs in order to balance different cell fate options. PMID:24415956

  4. C/EBP? is required for long-term self-renewal and lineage priming of hematopoietic stem cells and for the maintenance of epigenetic configurations in multipotent progenitors.

    PubMed

    Hasemann, Marie S; Lauridsen, Felicia K B; Waage, Johannes; Jakobsen, Janus S; Frank, Anne-Katrine; Schuster, Mikkel B; Rapin, Nicolas; Bagger, Frederik O; Hoppe, Philipp S; Schroeder, Timm; Porse, Bo T

    2014-01-01

    Transcription factors are key regulators of hematopoietic stem cells (HSCs) and act through their ability to bind DNA and impact on gene transcription. Their functions are interpreted in the complex landscape of chromatin, but current knowledge on how this is achieved is very limited. C/EBP? is an important transcriptional regulator of hematopoiesis, but its potential functions in HSCs have remained elusive. Here we report that C/EBP? serves to protect adult HSCs from apoptosis and to maintain their quiescent state. Consequently, deletion of Cebpa is associated with loss of self-renewal and HSC exhaustion. By combining gene expression analysis with genome-wide assessment of C/EBP? binding and epigenetic configurations, we show that C/EBP? acts to modulate the epigenetic states of genes belonging to molecular pathways important for HSC function. Moreover, our data suggest that C/EBP? acts as a priming factor at the HSC level where it actively promotes myeloid differentiation and counteracts lymphoid lineage choice. Taken together, our results show that C/EBP? is a key regulator of HSC biology, which influences the epigenetic landscape of HSCs in order to balance different cell fate options. PMID:24415956

  5. 101 Crazy Theories About Dinosaur Extinction

    NSDL National Science Digital Library

    This document presents a number of theories, both plausible and implausible or even humorous, for the extinction of the dinosaurs. Links to a glossary are embedded in the text. A reading list and links to related sites are also provided.

  6. How a Dinosaur Became a Fossil

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2005-12-17

    This interactive resource adapted from the Museum of Paleontology at the University of California, Berkeley shows how a dinosaur can be buried under sediment after it dies, become a fossil, and then become exposed and discovered by paleontologists.

  7. Are You Smarter Than a Dinosaur?

    NSDL National Science Digital Library

    Martin Farley

    Students investigate the intelligence of dinosaurs by comparing the relative size of brain and body mass to living animals. Students plot the living animals to determine a general relationship of brain and body mass and then use that relation to interpret a range of dinosaurs. The activity gives students practice in graphical data comparison and other methods of data analysis. Students also investigate how well this method works and what weaknesses it might have.

  8. Fossils From China Link Birds with Dinosaurs

    NSDL National Science Digital Library

    1998-01-01

    The discovery by Canadian, Chinese, and American researchers of two species of "theropod dinosaur from China -­ dinosaurs with feathers" is reported in the July 1998 issue of National Geographic. The National Geographic site contains information about the discovery, including a brief interview with Quang Ji, images (including a QuickTime VR image), and a 55 minute RealPlayer audio press conference held June 23, 1998.

  9. Lineage-specific chimaerism after stem cell transplantation in children following reduced intensity conditioning: potential predictive value of NK cell chimaerism for late graft rejection.

    PubMed

    Matthes-Martin, S; Lion, T; Haas, O A; Frommlet, F; Daxberger, H; König, M; Printz, D; Scharner, D; Eichstill, C; Peters, C; Lawitschka, A; Gadner, H; Fritsch, G

    2003-10-01

    Chimaerism of FACS-sorted leucocyte subsets (CD14+, CD15+, CD3-/56+, CD3+/4+, CD3+/8+, CD19+) was monitored prospectively between days +14 and +100 in 39 children undergoing allogeneic stem cell transplantation with reduced intensity-conditioning regimens. Cell subsets exceeding 1% of nucleated cells were subject to cell sorting. Chimaerism was analysed by dual-colour FISH and/or by short tandem repeat-polymerase chain reaction. The chimaerism pattern on day +28 was evaluated with regard to its correlation with graft rejection. Of 39 patients, nine patients had donor chimaerism (DC) in all subsets. Mixed/recipient chimaerism (MC/RC) was detectable within T cells in 62%, within NK cells in 39% and within monocytes and granulocytes in 38% of the patients. The correlation of secondary graft rejection with the chimaerism pattern on day +28 revealed the strongest association between RC in NK-cells (P<0.0001), followed by T cells (P=0.001), and granulocytes and monocytes (P=0.034). Notably, patients with RC in T cells rejected their graft only if MC or RC was also present in the NK-cell subset. By contrast, none of the children with DC in NK cells experienced a graft rejection. These observations suggest that, in the presence of recipient T-cell chimaerism, the chimaerism status in NK-cells on day +28 might be able to identify patients at high risk for late graft rejection. PMID:14513041

  10. Last updated 1/13/12 Genus List for Holtz (2007) Dinosaurs 1 * New genus; ** New grouping; ^ New genus name for previously unnamed dinosaur

    E-print Network

    Holtz Jr., Thomas R.

    2007-01-01

    Last updated 1/13/12 Genus List for Holtz (2007) Dinosaurs 1 * New genus; ** New grouping; ^ New genus name for previously unnamed dinosaur Primitive Dinosauromorphs--Dinosaurs' Closest Relatives (Chapter 11) These animals are not true dinosaurs, but they are the closest relatives to the dinosaurs

  11. Multiple bottlenecks, allopatric lineages and Badlands bison Bos bison: Consequences of lineage mixing

    Microsoft Academic Search

    Joel Berger; Carol Cunningham

    1995-01-01

    While ecological and conservation consequences of combining animals of varied genetic backgrounds have been widely discussed, the demonstration of effects that stem from lineage mixing remains elusive. Since management agencies relocate populations or supplement them with individuals regularly, the opportunity for either inbreeding or outbreeding depression may be high; still, any putative effects will go unnoticed without detailed knowledge of

  12. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago

    Microsoft Academic Search

    Ursula B. Göhlich; Luis M. Chiappe

    2006-01-01

    Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the

  13. ESTIMATING SPEEDS OF DINOSAURS FROM TRACKWAYS: A REEVALUATION OF ASSUMPTIONS

    Microsoft Academic Search

    Emma C. Rainforth; Melissa Manzella

    For 30 years, using equations determined by Alexander (1976), paleontologists have estimated speeds of dinosaurs from their trackways; the fundamental assumption, based on limited observations, was that dinosaur hip height is approximately four times foot length. Thulborn (1990) subsequently determined that the leg length to foot length ratio ranges from 4.5-6.0, according to type and size of dinosaur. Given that

  14. A Diverse Assemblage of Late Cretaceous Dinosaur and Bird

    E-print Network

    Machel, Hans

    A Diverse Assemblage of Late Cretaceous Dinosaur and Bird Feathers from Canadian Amber Ryan C. Mc primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights filamentous structures similar to the protofeathers of nonavian dinosaurs that are unknown in mod- ern birds

  15. INTEGRATED LIDAR & PHOTOGRAMMETRIC DOCUMENTATION OF THE RED GULCH DINOSAUR

    E-print Network

    Falkingham, Peter

    101 INTEGRATED LIDAR & PHOTOGRAMMETRIC DOCUMENTATION OF THE RED GULCH DINOSAUR TRACKSITE (WYOMING. At the First International Symposium on Dinosaur Tracks and Traces in 1989, concerns were expressed about discovery and formal description in 2001, the Red Gulch Dinosaur Tracksite (RGDT) in northern Wyoming (USA

  16. Estimating the diversity of dinosaurs Steve C. Wang*

    E-print Network

    Wang, Steve C.

    Estimating the diversity of dinosaurs Steve C. Wang* and Peter Dodson *Department of Mathematics, little effort has been devoted to estimating the diversity of dinosaurs. Here we estimate the diversity of nonavian dinosaurs at 1,850 genera, including those that remain to be discovered. With 527 genera currently

  17. GEOL 104 Dinosaurs: A Natural History Geology Assignment

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Geology Assignment DUE: Mon. Sept. 18 Part I available that dinosaurs (or today, even houses!) can be buried). However, if a smaller animal falls. Tracks of terrestrial animals (like dinosaurs) would indicate that the ground was soft but was either

  18. All about Dinosaurs. Animal Life for Children. [Videotape].

    ERIC Educational Resources Information Center

    2000

    Dinosaurs were the rulers of the land 65 million years ago. In this videotape, children learn more about the different kinds of dinosaurs by viewing vivid illustrations and fossil discoveries. Students compare the dinosaurs to their modern kin--snakes, lizards, and crocodiles. Students also listen to different theories to try to answer the big…

  19. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds

    E-print Network

    Benton, Michael

    LETTERS Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds Fucheng Zhang1 greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and con) feathers and integumentary fila- ments are preserved in birds3­5 and non-avian theropod dinosaurs6

  20. Response to Comment on "Ascent of Dinosaurs Linked to

    E-print Network

    Olsen, Paul E.

    Response to Comment on "Ascent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundary" Our recent study on the nature of the ascent of the dinosaurs (1) argued three main points: (i dinosaurs appear im- mediately after the boundary (based on foot- prints); and (iii) that both the boundary

  1. Dinosaurs: Warm Blooded or Cold Blooded? Gumundur Freyr Matthasson

    E-print Network

    Ingólfsson, Ólafur

    Dinosaurs: Warm Blooded or Cold Blooded? Guđmundur Freyr Matthíasson Laufásvegur 42, 101 Reykjavík 09.60.31 Jarđsaga 1. Haust 2003 During the Mesozoic era, dinosaurs reigned supreme on the planet that this was not so, that dinosaurs were, indeed, warm-blooded. Several arguments have been put forth by both camps

  2. GEOL 104 Dinosaurs: A Natural History Anatomy and Taxonomy Assignment

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Anatomy and Taxonomy Assignment DUE: Fri. Sept. 29 Part I. Comparative Anatomy Below is the skull of the early primitive meat-eating dinosaur 25) Ulna 26) A Metacarpal 27) A Metatarsal 28) Chevron 29) Acetabulum Extra Credit) This dinosaur

  3. Dinosaur Fossils Predict Body Temperatures James F. Gillooly1*

    E-print Network

    Allen, Andrew P.

    Dinosaur Fossils Predict Body Temperatures James F. Gillooly1* , Andrew P. Allen2 , Eric L. Charnov of America Perhaps the greatest mystery surrounding dinosaurs concerns whether they were endotherms, ectotherms, or some unique intermediate form. Here we present a model that yields estimates of dinosaur body

  4. GEOL 104 Dinosaurs: A Natural History Video Assignment

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Video Assignment DUE: Fri. Nov. 3 For this assignment, you are asked to watch the documentary series Walking With Dinosaurs (WWD). The version you will see minutes long. The conceit of Walking With Dinosaurs is that this is a "real" nature documentary: that is

  5. DWARFING IN ORNITHOPOD DINOSAURS FROM THE EARLY CRETACEOUS OF ROMANIA

    E-print Network

    Benton, Michael

    DWARFING IN ORNITHOPOD DINOSAURS FROM THE EARLY CRETACEOUS OF ROMANIA Michael J. BENTON1 , Nicholas maturation in the descendant. Key words. Dinosaur, dwarfing, island faunas, Cretaceous, Romania. Rezumat), but the pterosaur and supposed bird remains still await revision. The dinosaurs aroused interest from the beginning

  6. Emergence of Patterned Stem Cell Differentiation Within Multicellular Structures

    E-print Network

    Chen, Christopher S.

    , Pennsylvania, USA Key Words. Mesenchymal stem cells · Differentiation · Three-dimensional · Patterning ABSTRACTEmergence of Patterned Stem Cell Differentiation Within Multicellular Structures SAMI ALOM RUIZ The ability of stem cells to differentiate into specified lineages in the appropriate locations is vital

  7. Forearm Posture and Mobility in Quadrupedal Dinosaurs

    PubMed Central

    VanBuren, Collin S.; Bonnan, Matthew

    2013-01-01

    Quadrupedality evolved four independent times in dinosaurs; however, the constraints associated with these transitions in limb anatomy and function remain poorly understood, in particular the evolution of forearm posture and rotational ability (i.e., active pronation and supination). Results of previous qualitative studies are inconsistent, likely due to an inability to quantitatively assess the likelihood of their conclusions. We attempt to quantify antebrachial posture and mobility using the radius bone because its morphology is distinct between extant sprawled taxa with a limited active pronation ability and parasagittal taxa that have an enhanced ability to actively pronate the manus. We used a sliding semi-landmark, outline-based geometric morphometric approach of the proximal radial head and a measurement of the angle of curvature of the radius in a sample of 189 mammals, 49 dinosaurs, 35 squamates, 16 birds, and 5 crocodilians. Our results of radial head morphology showed that quadrupedal ceratopsians, bipedal non-hadrosaurid ornithopods, and theropods had limited pronation/supination ability, and sauropodomorphs have unique radial head morphology that likely allowed limited rotational ability. However, the curvature of the radius showed that no dinosaurian clade had the ability to cross the radius about the ulna, suggesting parallel antebrachial elements for all quadrupedal dinosaurs. We conclude that the bipedal origins of all quadrupedal dinosaur clades could have allowed for greater disparity in forelimb posture than previously appreciated, and future studies on dinosaur posture should not limit their classifications to the overly simplistic extant dichotomy. PMID:24058633

  8. GEOL 104 Dinosaurs: A Natural History Smithsonian Assignment I: Osteology and Life on Land before the Dinosaurs

    E-print Network

    Holtz Jr., Thomas R.

    Name: 1 GEOL 104 Dinosaurs: A Natural History Smithsonian Assignment I: Osteology and Life on Land before the Dinosaurs DUE: October 9 "Every man is a valuable member of society who by his observations of dinosaur and other fossils in the world. The Smithsonian museums are free; hours for the NMNH are 10 am

  9. Stem cell differentiation: Sticky mechanical memory

    NASA Astrophysics Data System (ADS)

    Eyckmans, Jeroen; Chen, Christopher S.

    2014-06-01

    Physical cues from the extracellular environment influence the lineage commitment of stem cells. Now, experiments on human mesenchymal stem cells cultured on photodegradable hydrogels show that the cells' fate can also be determined by past physical environments.

  10. Scaling effects in theropod dinosaurs

    NASA Astrophysics Data System (ADS)

    Lee, Scott A.

    2014-03-01

    For geometrically similar animals, the length of the leg bones l would scale as the diameter of the leg bone d: d ~ l. In order to maintain the same stresses in the leg bones when standing (i.e., elastic similarity), l3 must scale as d2, yielding d ~ l 3 / 2. Sixty-six femora from more than 30 different species of theropod dinosaurs were studied. Our results yield d ~ l 1 . 16, well below the prediction of elastic similarity. The maximum stresses on the leg bones would have occurred during locomotion when forces on the order of several times the body weight would have been present. Bending and torsional stresses of the femur would have been more likely to break the bone than compression. The ability of the bone to resist bending stresses is given by its section modulus Z. From our data, we find that Z ~ l 3 . 49. The bending torque applied to the femur is expected to scale as roughly l4. Both results indicate that larger theropods had smaller cursorial abilities than smaller theropods, as is observed in extant animals. Assuming that all theropod bones have the same shear modulus, the ability for the femora to resist torsion is given by Q = J/ l where J is the second polar moment of the area. From our data, we find that Q ~ l 3 . 66.

  11. Control of a robot dinosaur

    PubMed Central

    Papantoniou, V.

    1999-01-01

    The Palaiomation Consortium, supported by the European Commission, is building a robot Iguanodon atherfieldensis for museum display that is much more sophisticated than existing animatronic exhibits. The current half-size (2.5 m) prototype is fully autonomous, carrying its own computer and batteries. It walks around the room, choosing its own path and avoiding obstacles. A bigger version with a larger repertoire of behaviours is planned. Many design problems have had to be overcome. A real dinosaur would have had hundreds of muscles, and we have had to devise means of achieving life-like movement with a much smaller number of motors; we have limited ourselves to 20, to keep the control problems manageable. Realistic stance requires a narrower trackway and a higher centre of mass than in previous (often spider-like) legged robots, making it more difficult to maintain stability. Other important differences from previous walking robots are that the forelegs have to be shorter than the hind, and the machinery has had to be designed to fit inside a realistically shaped body shell. Battery life is about one hour, but to achieve this we have had to design the robot to have very low power consumption. Currently, this limits it to unrealistically slow movement. The control system includes a high-level instructions processor, a gait generator, a motion-coordination generator, and a kinematic model.

  12. Plumage color patterns of an extinct dinosaur.

    PubMed

    Li, Quanguo; Gao, Ke-Qin; Vinther, Jakob; Shawkey, Matthew D; Clarke, Julia A; D'Alba, Liliana; Meng, Qingjin; Briggs, Derek E G; Prum, Richard O

    2010-03-12

    For as long as dinosaurs have been known to exist, there has been speculation about their appearance. Fossil feathers can preserve the morphology of color-imparting melanosomes, which allow color patterns in feathered dinosaurs to be reconstructed. Here, we have mapped feather color patterns in a Late Jurassic basal paravian theropod dinosaur. Quantitative comparisons with melanosome shape and density in extant feathers indicate that the body was gray and dark and the face had rufous speckles. The crown was rufous, and the long limb feathers were white with distal black spangles. The evolution of melanin-based within-feather pigmentation patterns may coincide with that of elongate pennaceous feathers in the common ancestor of Maniraptora, before active powered flight. Feathers may thus have played a role in sexual selection or other communication. PMID:20133521

  13. What Lies Beneath: Sub-Articular Long Bone Shape Scaling in Eutherian Mammals and Saurischian Dinosaurs Suggests Different Locomotor Adaptations for Gigantism

    PubMed Central

    Bonnan, Matthew F.; Wilhite, D. Ray; Masters, Simon L.; Yates, Adam M.; Gardner, Christine K.; Aguiar, Adam

    2013-01-01

    Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more saurischian dinosaurs were giants than eutherians, the long bones of both taxa scale similarly and suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian mammals but thick in saurischian dinosaurs, differences that could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested the hypothesis that sub-articular bone, which supports the articular cartilage, changes shape in different ways between terrestrial mammals and dinosaurs with increasing size. Our sample consisted of giant mammal and reptile taxa (i.e., elephants, rhinos, sauropods) plus erect and non-erect outgroups with thin and thick articular cartilage. Our results show that eutherian mammal sub-articular shape becomes narrow with well-defined surface features as size increases. In contrast, this region in saurischian dinosaurs expands and remains gently convex with increasing size. Similar trends were observed in non-erect outgroup taxa (monotremes, alligators), showing that the trends we report are posture-independent. These differences support our hypothesis that sub-articular shape scales differently between eutherian mammals and saurischian dinosaurs. Our results show that articular cartilage thickness and sub-articular shape are correlated. In mammals, joints become ever more congruent and thinner with increasing size, whereas archosaur joints remained both congruent and thick, especially in sauropods. We suggest that gigantism occurs less frequently in mammals, in part, because joints composed of thin articular cartilage can only become so congruent before stress cannot be effectively alleviated. In contrast, frequent gigantism in saurischian dinosaurs may be explained, in part, by joints with thick articular cartilage that can deform across large areas with increasing load. PMID:24130690

  14. Scaling in Theropod Dinosaurs: Femoral Bone Dimensions

    NASA Astrophysics Data System (ADS)

    Lee, Scott A.

    2014-05-01

    Finding topics that inspire students is an important aspect of any physics course. Virtually everyone is fascinated by Tyrannosaurus rex, and the excitement of the class is palpable when we explore scaling effects in T. rex and other bipedal theropod dinosaurs as part of our discussion of mechanics and elasticity. In this paper, we explore the role of longitudinal stress in the femur bones due to the weight of the dinosaur in determining how the geometry of the femur changes with size of the theropod. This is one area of allometry the study of how different biological characteristics scale with size.

  15. Important new dinosaur located in Utah

    NSDL National Science Digital Library

    Recently, a team of researchers in a remote area of eastern Utah led by Utah state paleontologist James I. Kirkland made an important discovery that has been described as a type of dinosaur â??missing linkâ?ť. Essentially, this â??linkâ?ť represents a rather primitive plant-eater that evolved from the meat-eating raptors that also gave rise to modern birds. The dinosaur has been named Falcarius utahensis, which means â??sickle-maker from Utahâ?ť, largely due to its claws. The results of this important find were documented in this Thursdayâ??s edition of the journal Nature, and this material supports earlier contentions that link the plant-eating dinosaurs known as therizinosaurs to raptors. Matthew Lamanna from the Carnegie Museum of Natural History remarked that â??Itâ??s an extremely significant find. Before this discovery, the oldest known animal recognized as a therizinosaur came from China, and this one is just as old and seems to be more primitive anatomically. It appears to be the final piece of the puzzle.â?ťThe first link leads to an article from this Wednesdayâ??s Washington Post that offers some perspective on the find from the paleontologist James I. Kirkland. The second link will take visitors to a fine news story from the National Geographicâ??s website that provides a good perspective on this important discovery. The third link offers some informed insights from Natureâ??s own Michael Hopkins on this discovery. The fourth link leads to a very informative site from BBC on dinosaurs, which includes fact files on a number of dinosaurs, a timeline, and some interactive games and screensavers. The fifth link will take visitors to a very useful FAQ site, offered by the United States Geological Survey, which answers a number of common queries about dinosaurs, such as â??Where did dinosaurs live?â?ť and â??Did dinosaurs communicate?â?ť. The final link leads to the homepage of that noted University of Chicago paleontologist, Paul Sereno. Here visitors can learn about his work and expeditions, among other things.

  16. Geochemical and mineralogical studies of dinosaur bone from the Morrison Formation at Dinosaur Ridge

    USGS Publications Warehouse

    Modreski, P.J.

    2001-01-01

    The dinosaur bones first discovered in 1877 in the Upper Jurassic Morrison Formation at Morrison, Colorado were the first major find of dinosaur skeletons in the western U.S. and led to the recognition of four new dinosaur genera (Apatosaurus, Allosaurus, Diplodocus, and Stegosaurus). Eight articles dealing with these bones which appeared as research reports in the annual reports of the Friends of Dinosaur Ridge from 1990-1999 are condensed and summarized with some additional comments. Two of the articles are about the mineralogy and preservation of the bones; two are about the physical description of the bone occurrence; two are about the history of the site, and two are about use of novel instrumental methods (ground-penetrating radar and a directional scintillometer) to search for new bones.

  17. Instruction of hematopoietic lineage choice by cytokine signaling.

    PubMed

    Endele, Max; Etzrodt, Martin; Schroeder, Timm

    2014-12-10

    Hematopoiesis is the cumulative consequence of finely tuned signaling pathways activated through extrinsic factors, such as local niche signals and systemic hematopoietic cytokines. Whether extrinsic factors actively instruct the lineage choice of hematopoietic stem and progenitor cells or are only selectively allowing survival and proliferation of already intrinsically lineage-committed cells has been debated over decades. Recent results demonstrated that cytokines can instruct lineage choice. However, the precise function of individual cytokine-triggered signaling molecules in inducing cellular events like proliferation, lineage choice, and differentiation remains largely elusive. Signal transduction pathways activated by different cytokine receptors are highly overlapping, but support the production of distinct hematopoietic lineages. Cellular context, signaling dynamics, and the crosstalk of different signaling pathways determine the cellular response of a given extrinsic signal. New tools to manipulate and continuously quantify signaling events at the single cell level are therefore required to thoroughly interrogate how dynamic signaling networks yield a specific cellular response. PMID:25046868

  18. New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism

    PubMed Central

    Sampson, Scott D.; Loewen, Mark A.; Farke, Andrew A.; Roberts, Eric M.; Forster, Catherine A.; Smith, Joshua A.; Titus, Alan L.

    2010-01-01

    Background During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur “provinces,” or “biomes,” on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested. Methodology/Principal Findings Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.—characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment—is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.—characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks—has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta. Conclusions/Significance Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs. PMID:20877459

  19. 76 FR 7232 - Notice of Inventory Completion: U.S. Department of the Interior, National Park Service, Dinosaur...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ...Department of the Interior, National Park Service, Dinosaur National Monument, Dinosaur, CO AGENCY: National Park Service, Interior...Department of the Interior, National Park Service, Dinosaur National Monument, Dinosaur, CO, has...

  20. Phylogenetic lineages in Entomophthoromycota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Entomophthoromycota Humber is one of five major phylogenetic lineages among the former phylum Zygomycota. These early terrestrial fungi share evolutionarily ancestral characters such as coenocytic mycelium and gametangiogamy as a sexual process resulting in zygospore formation. Previous molecular st...

  1. Mesenchymal stem cells in health and disease

    Microsoft Academic Search

    Lorenzo Moretta; Vito Pistoia; Antonio Uccelli

    2008-01-01

    Mesenchymal stem cells (MSCs) are a heterogeneous subset of stromal stem cells that can be isolated from many adult tissues. They can differentiate into cells of the mesodermal lineage, such as adipocytes, osteocytes and chondrocytes, as well as cells of other embryonic lineages. MSCs can interact with cells of both the innate and adaptive immune systems, leading to the modulation

  2. Dinosaur diversity and the rock record.

    PubMed

    Barrett, Paul M; McGowan, Alistair J; Page, Victoria

    2009-07-22

    Palaeobiodiversity analysis underpins macroevolutionary investigations, allowing identification of mass extinctions and adaptive radiations. However, recent large-scale studies on marine invertebrates indicate that geological factors play a central role in moulding the shape of diversity curves and imply that many features of such curves represent sampling artefacts, rather than genuine evolutionary events. In order to test whether similar biases affect diversity estimates for terrestrial taxa, we compiled genus-richness estimates for three Mesozoic dinosaur clades (Ornithischia, Sauropodomorpha and Theropoda). Linear models of expected genus richness were constructed for each clade, using the number of dinosaur-bearing formations available through time as a proxy for the amount of fossiliferous rock outcrop. Modelled diversity estimates were then compared with observed patterns. Strong statistically robust correlations demonstrate that almost all aspects of ornithischian and theropod diversity curves can be explained by geological megabiases, whereas the sauropodomorph record diverges from modelled predictions and may be a stronger contender for identifying evolutionary signals. In contrast to other recent studies, we identify a marked decline in dinosaur genus richness during the closing stages of the Cretaceous Period, indicating that the clade decreased in diversity for several million years prior to the final extinction of non-avian dinosaurs at the Cretaceous-Palaeocene boundary. PMID:19403535

  3. Did dinosaurs come up to scratch?

    Microsoft Academic Search

    David M. Martill; Paul G. Davis

    1998-01-01

    The high specificity of bird ectoparasites has frequently been interpreted to mean that they have a long evolutionary history. Either they were present as parasites before the main diversification of birds in the Cretaceous period, or they evolved independently into avian parasites on several occasions. The recent discovery of dinosaurs with feathers suggests that birds may have inherited some of

  4. Tail and pelvis pathologies of ankylosaurian dinosaurs

    Microsoft Academic Search

    Victoria M. Arbour; Philip J. Currie

    2011-01-01

    Ankylosaurid dinosaurs had modified distal caudal vertebrae (the handle) and large terminal caudal osteoderms (the knob), which together form the tail club. The tail club may have been used as a weapon. Ankylosaur pelvic and caudal elements were surveyed for evidence of healing wounds that may indicate traumatic injury, and which could support clubbing behaviour. No pathologies were found in

  5. A review of the dinosaurs from Kansas

    Microsoft Academic Search

    Gregory A. Liggett

    2005-01-01

    Although Kansas is best known for an abundance of marine fossils from the Late Cretaceous, there may be up to 16 dinosaur records from the state. These are (in order of discovery): 1) the Mudge tracks from the Dakota Formation of Clay County; 2) the hadrosaur, Claosaurus agilis, from the Niobrara Chalk of Logan County; 3) the Snow track from

  6. Eden Garden and Dinosaur Sugata Sanyal

    E-print Network

    Sanyal, Sugata

    , but it was so cold, I begged him to take us back to his drawing room. And the device is so simple; it looks likeEden Garden and Dinosaur Sugata Sanyal Professor Prashanta Bose is a renowned scholar. Though he, do you feel like seeing live creatures from past?" I was trying to get a drift of his thoughts. But I

  7. An unusual oviraptorosaurian dinosaur from China

    Microsoft Academic Search

    Xing Xu; Yen-Nien Cheng; Xiao-Lin Wang; Chun-Hsiang Chang

    2002-01-01

    Oviraptorosaurians are an unusual group of theropod dinosaurs, with highly specialized skulls. Here we report a new oviraptorosaurian, Incisivosaurus gauthieri, gen. et sp. nov., from the lowest part of the Lower Cretaceous Yixian Formation of China. This oviraptorosaurian displays a number of characters closer to more typical theropods, such as a low skull and toothed jaws, thus greatly reducing the

  8. Four-winged dinosaurs from China

    Microsoft Academic Search

    Xing Xu; Zhonghe Zhou; Xiaolin Wang; Xuewen Kuang; Fucheng Zhang; Xiangke Du

    2003-01-01

    Although the dinosaurian hypothesis of bird origins is widely accepted, debate remains about how the ancestor of birds first learned to fly. Here we provide new evidence suggesting that basal dromaeosaurid dinosaurs were four-winged animals and probably could glide, representing an intermediate stage towards the active, flapping-flight stage. The new discovery conforms to the predictions of early hypotheses that proavians

  9. Scaling in Theropod Dinosaurs: Femoral Bone Dimensions

    ERIC Educational Resources Information Center

    Lee, Scott A.

    2014-01-01

    Finding topics that inspire students is an important aspect of any physics course. Virtually everyone is fascinated by "Tyrannosaurus rex," and the excitement of the class is palpable when we explore scaling effects in "T. rex" and other bipedal theropod dinosaurs as part of our discussion of mechanics and elasticity. In this…

  10. Theory Choices: What Happened to the Dinosaurs?

    NSDL National Science Digital Library

    In this lesson, students read and discuss articles presenting two alternative theories about the extinction of dinosaurs. They are encouraged to use the criteria that scientists use to get the best solution. Students will learn that: some evolutionary change is rapid and discontinuous; extinction plays in role in macroevolution; and scientists use specific criteria in deciding which theory is better.

  11. Fighting Dinosaurs: New Discoveries from Mongolia

    NSDL National Science Digital Library

    This Web site, created to complement an American Museum of Natural History exhibition, reports on one of the most famous fossil finds in the world (the fighting dinosaurs of Mongolia) and other ancient animal fossils discovered in the Gobi Desert. Although the exhibit is closed, there is useful information on the fossil finds and three short video clips.

  12. Sequence stratigraphic controls on synsedimentary cementation and preservation of dinosaur tracks: Example from the lower Cretaceous,

    E-print Network

    González, Luis A.

    Sequence stratigraphic controls on synsedimentary cementation and preservation of dinosaur tracks in the Upper Albian Dakota Formation of southeastern Nebraska contains the first dinosaur tracks; Diagenesis; Isotopes; Dinosaur tracks; Carbonate cements 1. Introduction The preservation of fossils

  13. Paleobiology and skeletochronology of Jurassic dinosaurs: implications from the histology and oxygen

    E-print Network

    Schöne, Bernd R.

    Paleobiology and skeletochronology of Jurassic dinosaurs: implications from the histology Abstract Fossil biogenic phosphate of fast-growing primary bone tissue of dinosaurs can preserve dinosaurs with different histologic patterns of bone growth, high-resolution oxygen isotope profiles were

  14. LE BULLETIN DE L'EPI N 54 LES DINOSAURES ET LES MOHICANS TRIBUNE LIBRE

    E-print Network

    Paris-Sud XI, Université de

    31 LE BULLETIN DE L'EPI N° 54 LES DINOSAURES ET LES MOHICANS TRIBUNE LIBRE LES DINOSAURES ET LES certains esprits embrumés : pourquoi ne pas regrouper et parquer les derniers dinosaures et les derniers

  15. Mesenchymal stem cells from the outer ear: a novel adult stem cell model system for the study of adipogenesis

    Microsoft Academic Search

    Jong-Seop Rim; Randall L. Mynatt; Barbara Gawronska-Kozak

    2005-01-01

    Adipocytes arise from multipotent stem cells of mesodermal origin, which also give rise to the muscle, bone, and cartilage lineages. However, signals and early molecular events that commit multipotent stem cells into the adipocyte lineage are not well established mainly due to lack of an adequate model system. We have identified a novel source of adult stem cells from the

  16. Last updated 1/28/11 Genus List for Holtz (2007) Dinosaurs 1 Primitive Dinosauromorphs--Dinosaurs' Closest Relatives (Chapter 11)

    E-print Network

    Holtz Jr., Thomas R.

    2007-01-01

    Last updated 1/28/11 Genus List for Holtz (2007) Dinosaurs 1 Primitive Dinosauromorphs--Dinosaurs' Closest Relatives (Chapter 11) These animals are not true dinosaurs, but they are the closest relatives to the dinosaurs that we know of. Name Meaning Age Time Length Weight Where found Comments Lagosuchus rabbit

  17. Estimating Speeds of Dinosaurs: a Re-Evaluation of AssumptionsEstimating Speeds of Dinosaurs: a Re-Evaluation of Assumptions 1. INTRODUCTION1. INTRODUCTION

    E-print Network

    Rainforth, Emma C.

    Estimating Speeds of Dinosaurs: a Re-Evaluation of AssumptionsEstimating Speeds of Dinosaurs: a Re-Evaluation of Assumptions 1. INTRODUCTION1. INTRODUCTION · Paleontologists estimate speeds of dinosaurs from their trackways: ­ McNeill Alexander (1976): hip height is approximately 4x foot length in a variety of dinosaurs, both

  18. 06/07/2006 01:19 PMUnderstanding the Swimming Dinosaurs -Softpedia Page 1 of 2http://news.softpedia.com/news/Understanding-the-Swimming-Dinosaurs-25209.shtml

    E-print Network

    Long Jr., John H.

    06/07/2006 01:19 PMUnderstanding the Swimming Dinosaurs - Softpedia Page 1 of 2http://news.softpedia.com/news/Understanding-the-Swimming-Dinosaurs on this site Understanding the Swimming Dinosaurs Category: SOFTPEDIA NEWS :: Science Scientists use a robot for propulsion, the swimming dinosaurs, such as the plesiosaurs, probably used all their limbs. Scientists

  19. Last updated 8/1/2008 Genus List for Holtz (2008) Dinosaurs 1 Primitive Dinosauromorphs--the Dinosaurs' Closest Relatives (Chapter 11)

    E-print Network

    Holtz Jr., Thomas R.

    2008-01-01

    Last updated 8/1/2008 Genus List for Holtz (2008) Dinosaurs 1 Primitive Dinosauromorphs--the Dinosaurs' Closest Relatives (Chapter 11) These animals are not true dinosaurs, but they are the closest relatives to the dinosaurs that we know of. Name Meaning Age Time Length Weight Where found Comments

  20. A Triassic Fauna from Madagascar, Including Early Dinosaurs.

    PubMed

    Flynn; Parrish; Rakotosamimanana; Simpson; Whatley; Wyss

    1999-10-22

    The discovery of a Middle to Late Triassic ( approximately 225 to 230 million years old) terrestrial vertebrate fauna from Madagascar is reported. This fauna documents a temporal interval not well represented by continental vertebrate assemblages elsewhere in the world. It contains two new prosauropod dinosaurs, representing some of the earliest dinosaur occurrences known globally. This assemblage provides information about the poorly understood transition to the dinosaur-dominated faunas of the latest Triassic. PMID:10531059

  1. The smallest known non-avian theropod dinosaur

    Microsoft Academic Search

    Xing Xu; Zhonghe Zhou; Xiaolin Wang

    2000-01-01

    Non-avian dinosaurs are mostly medium to large-sized animals, and to date all known mature specimens are larger than the most primitive bird, Archaeopteryx. Here we report on a new dromaeosaurid dinosaur, Microraptor zhaoianus gen. et sp. nov., from the Early Cretaceous Jiufotang Formation of Liaoning, China. This is the first mature non-avian dinosaur to be found that is smaller than

  2. Discover Dinosaurs Paleontology at the American Museum of Natural History

    NSDL National Science Digital Library

    This activity sheet for young children is designed to be completed during a visit to the Museum's fourth floor Fossil Halls. The printable two-page handout includes notes about how paleontologists use tools to find and dig out fossils, a scavenger hunt in the Hall of Saurischian Dinosaurs for two vegetarian dinosaurs, a scavenger hunt for protective body parts in the Hall of Ornithischian Dinosaurs and a collection of fun facts.

  3. Team of Paleontologists Discovers New Dinosaur Species

    NSDL National Science Digital Library

    Grinnell, Max

    Working as part of a joint expedition, scientists from India and the United States (including the well-known paleontologist Paul Sereno from the University of Chicago) announced this Wednesday that they discovered a new carnivorous dinosaur species in the Narmada River region in western India. Based on the bones located by the team, this newly discovered species of dinosaur was between 25-30 feet long, had a horn above its skull, and was relatively heavy. As part of a collaborative effort with Jeff Wilson of the University of Michigan, Sereno reconstructed the dinosaur skull and presented a model to their Indian colleagues at Punjab University. It is believed that the new species (named Rajasaurus narmadensis) roamed the Southern Hemisphere land masses that constitute modern-day Madagascar, Africa, and South America. Utilizing these new findings, scientists hope to shed additional light on the potential cause of the dinosaurs' extinction, a subject that is often debated within the community of paleontologists.The first link leads to a news article about this recent find from Newind.com. The second link will take visitors to another news article from the Chicago Sun-Times that talks about Sereno's latest find. The third link leads to Paul Sereno's personal Web site from the University of Chicago, and contains interesting information about his numerous expeditions and his various experiences as an educator and scientist. The fourth link leads to the Project Exploration Web site, an organization founded by Sereno and his wife, Gabrielle Lyon, that is dedicated to making science "accessible to the public-with a special focus on city kids and girls." Here visitors can learn about the groups' many outreach programs, along with reading about events sponsored by the organization. The fifth link leads to a fabulous Web site provided by the BBC geared towards young people that features fact files on dinosaurs, a detailed chronology of their time on Earth, and several interactive games. The sixth and final link leads to a brief piece from Scientific American.com that talks a bit about the controversy surrounding the cause of the mass extinction of dinosaurs approximately 65 million years ago.

  4. Locomotion speeds from trackways: Predatory dinosaurs moved faster than herbivorous dinosaurs

    NASA Astrophysics Data System (ADS)

    Lee, Scott A.

    2014-03-01

    Fossilized trackways from dinosaurs leaves evidence of their locomotion from the stride length S and foot length F which yields the leg length L. From studies of living animals, it is known that a walking animal has a relative stride length RSL (= S/L) less than 2 and a running animal has a RSL greater than 2. A statistical analysis was performed of trackways associated with three groups of herbivorous dinosaurs: sauropods (N = 23), the armored ankylosaurs and stegosaurs (N = 10), and the unarmored ornithopods (N = 23) as well as the predatory theropods (N = 35). The average RSL of the sauropods and the armored dinosaurs were both 0.9 +/- 0.3. The ornithopods had an average RSL of 1.2 +/- 0.2. None of the trackways associated with herbivorous dinosaurs have an RSL greater than 1.5, indicating that they were all walking. The theropods showed the fastest and most varied locomomtion: their highest average RSL was 1.8 +/- 0.7. Nine of the theropod trackways had an RSL greater than 2.0, indicating that the dinosaurs were running when they made those trackways. One of the theropod trackways had an RSL of 4.5, indicating that it was running very fast compared to its body length.

  5. The second Jurassic dinosaur rush and the dawn of dinomania.

    PubMed

    Brinkman, Paul D

    2010-09-01

    During the second Jurassic dinosaur rush museum paleontologists raced to display the world's first mounted sauropod dinosaur. The American Museum of Natural History triumphed in 1905 when its Brontosaurus debuted before an admiring crowd of wealthy New Yorkers. The Carnegie Museum of Natural History in Pittsburgh, the Field Columbian Museum in Chicago and other institutions were quick to follow with their own sauropod displays. Thereafter, dinomania spread far and wide, and big, showpiece dinosaurs became a museum staple. This brief but intensely competitive period of acquisitiveness fostered important Jurassic dinosaur revisions and crucial innovations in paleontological field and lab techniques. PMID:20667597

  6. The Great Dinosaur Feud: Science Against All Odds

    NSDL National Science Digital Library

    Amy Carpinelli

    2008-10-01

    In the 19th century, the race to uncover dinosaur fossils and name new dinosaur species inspired two rival scientists, Edward Drinker Cope and Othniel Charles Marsh, to behave in ways that were the antithesis of scientific methods. Subterfuge, theft, and espionage were the ingredients of the Great Dinosaur Feud. Because students often enjoy controversy, as evidenced by popular television programs today, the authors use the controversy of the dinosaur feud to illustrate the human side of science, and the triumph of science in spite of inappropriate competition.

  7. Should Dinosaurs be "Cloned" from Ancient DNA?

    NSDL National Science Digital Library

    Constance Soja

    These are the teaching notes for a case study in which students use cooperative learning and role-playing to explore the scientific, technical, environmental, and ethical issues related to the possibility of cloning dinosaurs from ancient DNA. The case was designed to enhance the learning environment in an introductory class through cooperative problem-solving and to promote active participation in learning by using library and web resources to do research on a controversial topic in science and ethics. As the students pursue this case, they will apply knowledge explored in readings, lectures, and in-class discussions about dinosaurs, gain a general understanding of the revolutionary techniques used to discover and retrieve ancient DNA and to produce a clone, and improve communication and collaboration skills by working cooperatively in small groups and arguing a position in an authoritative fashion.

  8. Models for the rise of the dinosaurs.

    PubMed

    Benton, Michael J; Forth, Jonathan; Langer, Max C

    2014-01-20

    Dinosaurs arose in the early Triassic in the aftermath of the greatest mass extinction ever and became hugely successful in the Mesozoic. Their initial diversification is a classic example of a large-scale macroevolutionary change. Diversifications at such deep-time scales can now be dissected, modelled and tested. New fossils suggest that dinosaurs originated early in the Middle Triassic, during the recovery of life from the devastating Permo-Triassic mass extinction. Improvements in stratigraphic dating and a new suite of morphometric and comparative evolutionary numerical methods now allow a forensic dissection of one of the greatest turnovers in the history of life. Such studies mark a move from the narrative to the analytical in macroevolutionary research, and they allow us to begin to answer the proposal of George Gaylord Simpson, to explore adaptive radiations using numerical methods. PMID:24456985

  9. Hanford: The evolution of a dinosaur

    SciTech Connect

    Fulton, J.

    1995-11-01

    This article describes how the Westinghouse Hanford Company is reinventing the US DOE`s Hanford Site, turning a 1940s-era dinosaur into a 1990s-style business. The major topics covered include the following: breaking the logjam by ending the inefficient cost-plus days; Concentrating resources on resolving urgent safety issues; contract reform with more incentive, greater risk; finally reengineering: the next step.

  10. Revisiting the Estimation of Dinosaur Growth Rates

    PubMed Central

    Myhrvold, Nathan P.

    2013-01-01

    Previous growth-rate studies covering 14 dinosaur taxa, as represented by 31 data sets, are critically examined and reanalyzed by using improved statistical techniques. The examination reveals that some previously reported results cannot be replicated by using the methods originally reported; results from new methods are in many cases different, in both the quantitative rates and the qualitative nature of the growth, from results in the prior literature. Asymptotic growth curves, which have been hypothesized to be ubiquitous, are shown to provide best fits for only four of the 14 taxa. Possible reasons for non-asymptotic growth patterns are discussed; they include systematic errors in the age-estimation process and, more likely, a bias toward younger ages among the specimens analyzed. Analysis of the data sets finds that only three taxa include specimens that could be considered skeletally mature (i.e., having attained 90% of maximum body size predicted by asymptotic curve fits), and eleven taxa are quite immature, with the largest specimen having attained less than 62% of predicted asymptotic size. The three taxa that include skeletally mature specimens are included in the four taxa that are best fit by asymptotic curves. The totality of results presented here suggests that previous estimates of both maximum dinosaur growth rates and maximum dinosaur sizes have little statistical support. Suggestions for future research are presented. PMID:24358133

  11. Cannibalism in the Madagascan dinosaur Majungatholus atopus.

    PubMed

    Rogers, Raymond R; Krause, David W; Curry Rogers, Kristina

    2003-04-01

    Many lines of evidence have been brought to bear on the question of theropod feeding ecology, including functional and physiological considerations, morphological constraints, taphonomic associations, and telling--although rare--indications of direct ingestion. Tooth marks of theropods, although rarely described and generally left unassigned to a particular taxon, can provide unique clues into predator-prey interaction, and can also yield insights into the extent of carcass utilization. Here we describe a sample of tooth-marked dinosaur bone recovered from three well-documented localities in the Upper Cretaceous Maevarano Formation of Madagascar that provides insights into the feeding ecology of the abelisaurid theropod Majungatholus atopus. Intensely tooth-marked elements from multiple individuals show that Majungatholus defleshed dinosaur carcasses. Furthermore, Majungatholus clearly fed upon the remains of not only sauropods, but also conspecifics, and thus was a cannibal. Cannibalism is a common ecological strategy among extant carnivores, but until now the evidence in relation to carnivorous dinosaurs has been sparse and anecdotal. PMID:12673249

  12. Cockroaches probably cleaned up after dinosaurs.

    PubMed

    Vršanský, Peter; van de Kamp, Thomas; Azar, Dany; Prokin, Alexander; Vidli?ka, L'ubomír; Vagovi?, Patrik

    2013-01-01

    Dinosaurs undoubtedly produced huge quantities of excrements. But who cleaned up after them? Dung beetles and flies with rapid development were rare during most of the Mesozoic. Candidates for these duties are extinct cockroaches (Blattulidae), whose temporal range is associated with herbivorous dinosaurs. An opportunity to test this hypothesis arises from coprolites to some extent extruded from an immature cockroach preserved in the amber of Lebanon, studied using synchrotron X-ray microtomography. 1.06% of their volume is filled by particles of wood with smooth edges, in which size distribution directly supports their external pre-digestion. Because fungal pre-processing can be excluded based on the presence of large particles (combined with small total amount of wood) and absence of damages on wood, the likely source of wood are herbivore feces. Smaller particles were broken down biochemically in the cockroach hind gut, which indicates that the recent lignin-decomposing termite and cockroach endosymbionts might have been transferred to the cockroach gut upon feeding on dinosaur feces. PMID:24324610

  13. A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution.

    PubMed

    Zanno, Lindsay E; Gillette, David D; Albright, L Barry; Titus, Alan L

    2009-10-01

    Historically, ecomorphological inferences regarding theropod (i.e. 'predatory') dinosaurs were guided by an assumption that they were singularly hypercarnivorous. A recent plethora of maniraptoran discoveries has produced evidence challenging this notion. Here, we report on a new species of maniraptoran theropod, Nothronychus graffami sp. nov. Relative completeness of this specimen permits a phylogenetic reassessment of Therizinosauria-the theropod clade exhibiting the most substantial anatomical evidence of herbivory. In the most comprehensive phylogenetic study of the clade conducted to date, we recover Therizinosauria as the basalmost maniraptoran lineage. Using concentrated changes tests, we present evidence for correlated character evolution among herbivorous and hypercarnivorous taxa and propose ecomorphological indicators for future interpretations of diet among maniraptoran clades. Maximum parsimony optimizations of character evolution within our study indicate an ancestral origin for dietary plasticity and facultative herbivory (omnivory) within the clade. These findings suggest that hypercarnivory in paravian dinosaurs is a secondarily derived dietary specialization and provide a potential mechanism for the invasion of novel morpho- and ecospace early in coelurosaurian evolution-the loss of obligate carnivory and origin of dietary opportunism. PMID:19605396

  14. From Dinosaurs to Modern Bird Diversity: Extending the Time Scale of Adaptive Radiation

    PubMed Central

    Moen, Daniel; Morlon, Hélčne

    2014-01-01

    What explains why some groups of organisms, like birds, are so species rich? And what explains their extraordinary ecological diversity, ranging from large, flightless birds to small migratory species that fly thousand of kilometers every year? These and similar questions have spurred great interest in adaptive radiation, the diversification of ecological traits in a rapidly speciating group of organisms. Although the initial formulation of modern concepts of adaptive radiation arose from consideration of the fossil record, rigorous attempts to identify adaptive radiation in the fossil record are still uncommon. Moreover, most studies of adaptive radiation concern groups that are less than 50 million years old. Thus, it is unclear how important adaptive radiation is over temporal scales that span much larger portions of the history of life. In this issue, Benson et al. test the idea of a “deep-time” adaptive radiation in dinosaurs, compiling and using one of the most comprehensive phylogenetic and body-size datasets for fossils. Using recent phylogenetic statistical methods, they find that in most clades of dinosaurs there is a strong signal of an “early burst” in body-size evolution, a predicted pattern of adaptive radiation in which rapid trait evolution happens early in a group's history and then slows down. They also find that body-size evolution did not slow down in the lineage leading to birds, hinting at why birds survived to the present day and diversified. This paper represents one of the most convincing attempts at understanding deep-time adaptive radiations. PMID:24802950

  15. Early crocodylomorph increases top tier predator diversity during rise of dinosaurs.

    PubMed

    Zanno, Lindsay E; Drymala, Susan; Nesbitt, Sterling J; Schneider, Vincent P

    2015-01-01

    Triassic predatory guild evolution reflects a period of ecological flux spurred by the catastrophic end-Permian mass extinction and terminating with the global ecological dominance of dinosaurs in the early Jurassic. In responding to this dynamic ecospace, terrestrial predator diversity attained new levels, prompting unique trophic webs with a seeming overabundance of carnivorous taxa and the evolution of entirely new predatory clades. Key among these was Crocodylomorpha, the largest living reptiles and only one of two archosaurian lineages that survive to the present day. In contrast to their existing role as top, semi-aquatic predators, the earliest crocodylomorphs were generally small-bodied, terrestrial faunivores, occupying subsidiary (meso) predator roles. Here we describe Carnufex carolinensis a new, unexpectedly large-bodied taxon with a slender and ornamented skull from the Carnian Pekin Formation (~231 Ma), representing one of the oldest and earliest diverging crocodylomorphs described to date. Carnufex bridges a problematic gap in the early evolution of pseudosuchians by spanning key transitions in bauplan evolution and body mass near the origin of Crocodylomorpha. With a skull length of >50 cm, the new taxon documents a rare instance of crocodylomorphs ascending to top-tier predator guilds in the equatorial regions of Pangea prior to the dominance of dinosaurs. PMID:25787306

  16. Does morphological convergence imply functional similarity? A test using the evolution of quadrupedalism in ornithischian dinosaurs

    PubMed Central

    Maidment, Susannah C. R.; Barrett, Paul M.

    2012-01-01

    Convergent morphologies are thought to indicate functional similarity, arising because of a limited number of evolutionary or developmental pathways. Extant taxa displaying convergent morphologies are used as analogues to assess function in extinct taxa with similar characteristics. However, functional studies of extant taxa have shown that functional similarity can arise from differing morphologies, calling into question the paradigm that form and function are closely related. We test the hypothesis that convergent skeletal morphology indicates functional similarity in the fossil record using ornithischian dinosaurs. The rare transition from bipedality to quadrupedality occurred at least three times independently in this clade, resulting in a suite of convergent osteological characteristics. We use homology rather than analogy to provide an independent line of evidence about function, reconstructing soft tissues using the extant phylogenetic bracket and applying biomechanical concepts to produce qualitative assessments of muscle leverage. We also optimize character changes to investigate the sequence of character acquisition. Different lineages of quadrupedal ornithischian dinosaur stood and walked differently from each other, falsifying the hypothesis that osteological convergence indicates functional similarity. The acquisition of features correlated with quadrupedalism generally occurs in the same order in each clade, suggesting underlying developmental mechanisms that act as evolutionary constraints. PMID:22719033

  17. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds

    Microsoft Academic Search

    Fucheng Zhang; Stuart L. Kearns; Patrick J. Orr; Michael J. Benton; Zhonghe Zhou; Diane Johnson; Xing Xu; Xiaolin Wang

    2010-01-01

    Spectacular fossils from the Early Cretaceous Jehol Group of northeastern China have greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and contributed to our understanding of the origin of birds, of flight, and of feathers. Pennaceous (vaned) feathers and integumentary filaments are preserved in birds and non-avian theropod dinosaurs, but little is known of

  18. Dino-Facts: A Unit on Dinosaur Behavior

    NSDL National Science Digital Library

    Judith Scotchmoor

    This activity takes students to the Bozeman, Montana area, where many dinosaurs once lived. They will gain an understanding of paleontological field work by analyzing evidence, developing hypotheses about dinosaur behavior, and supporting their hypotheses with evidence. This lesson contains materials needed, procedure, and extension ideas.

  19. Preservation of the bone protein osteocalcin in dinosaurs

    Microsoft Academic Search

    Gerard Muyzer; Philip Sandberg; Marjo H. J. Knapen; Cees Vermeer; Matthew Collins; Peter Westbroek

    1992-01-01

    Two different immunological assays were used to identify the remains of a bone matrix protein, osteocalcin (OC), in the bones of dinosaurs and other fossil vertebrates. Antibodies raised against OC from modern vertebrates showed strong immunological cross-reactivity with modern and relatively young fossil samples and significant reactions with some of the dinosaur bone extracts. The presence of OC was confirmed

  20. 36 CFR 7.63 - Dinosaur National Monument.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Public Property 1 2014-07-01 2014-07-01 false Dinosaur National Monument. 7.63 Section 7.63 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.63 Dinosaur National Monument. (a) Commercial hauling....

  1. 36 CFR 7.63 - Dinosaur National Monument.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Public Property 1 2011-07-01 2011-07-01 false Dinosaur National Monument. 7.63 Section 7.63 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.63 Dinosaur National Monument. (a) Commercial hauling....

  2. "Dinosaurs." Kindergarten. Anchorage School District Elementary Science Program.

    ERIC Educational Resources Information Center

    Herminghaus, Trisha, Ed.

    This unit contains 15 lessons on dinosaurs for kindergarten children. It provides a materials list, supplementary materials list, use of process skill terminology, unit objectives, vocabulary, six major dinosaurs, and background information. Lessons are: (1) "Webbing"; (2) "Introduction to the Big Six"; (3) "Paleontology and Fossils"; (4) "How Big…

  3. The distribution of integumentary structures in a feathered dinosaur

    Microsoft Academic Search

    Qiang Ji; Mark A. Norell; Ke-Qin Gao; Shu-An Ji; Dong Ren

    2001-01-01

    Non-avian theropod dinosaurs with preserved integumentary coverings are becoming more common; but apart from the multiple specimens of Caudipteryx, which have true feathers, animals that are reasonably complete and entirely articulated that show these structures in relation to the body have not been reported. Here we report on an enigmatic small theropod dinosaur that is covered with filamentous feather-like structures

  4. 36 CFR 7.63 - Dinosaur National Monument.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Public Property 1 2013-07-01 2013-07-01 false Dinosaur National Monument. 7.63 Section 7.63 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.63 Dinosaur National Monument. (a) Commercial hauling....

  5. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

    ERIC Educational Resources Information Center

    Lee, Scott

    2015-01-01

    In our first article on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find…

  6. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion II

    ERIC Educational Resources Information Center

    Lee, Scott

    2015-01-01

    In the second paper of this series, the effect of transverse femoral stresses due to locomotion in theropod dinosaurs of different sizes was examined for the case of an unchanging leg geometry. Students are invariably thrilled to learn about theropod dinosaurs, and this activity applies the concepts of torque and stress to the issue of theropod…

  7. 36 CFR 7.63 - Dinosaur National Monument.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Public Property 1 2012-07-01 2012-07-01 false Dinosaur National Monument. 7.63 Section 7.63 Parks, Forests...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.63 Dinosaur National Monument. (a) Commercial hauling....

  8. The Metabolic Status of Some Late Cretaceous Dinosaurs

    Microsoft Academic Search

    John A. Ruben; Willem J. Hillenius; Nicholas R. Geist; Andrew Leitch; Terry D. Jones; Philip J. Currie; John R. Horner; George Espe III

    1996-01-01

    Analysis of the nasal region in fossils of three theropod dinosaurs (Nanotyrannus, Ornithomimus, and Dromaeosaurus) and one omithischian dinosaur (Hypacrosaurus) showed that their metabolic rates were significantly lower than metabolic rates in modern birds and mammals. In extant endotherms and ectotherms, the cross-sectional area of the nasal passage scales approximately with increasing body mass M at M0 72. However, the

  9. The origin and early radiation of dinosaurs Stephen L. Brusatte a,b,

    E-print Network

    Benton, Michael

    The origin and early radiation of dinosaurs Stephen L. Brusatte a,b, , Sterling J. Nesbitt a online 4 May 2010 Keywords: dinosaurs diversification evolution Jurassic paleontology Triassic Dinosaurs of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been

  10. "Teachosaurus" and "Learnoceratops": Dinosaurs as a Motivating Cross-Curricular Theme

    ERIC Educational Resources Information Center

    Duggan, Denis

    2011-01-01

    The author takes a look into the benefits that dinosaurs may bring to the classroom. He discusses how he used dinosaurs as a cross-curricular theme to improve children's understanding and knowledge of science concepts. To investigate what a child might learn from dinosaurs, he started by comparing the many non-fiction dinosaur books using the…

  11. Computational modelling of locomotor muscle moment arms in the basal dinosaur Lesothosaurus diagnosticus: assessing convergence between birds and basal ornithischians

    PubMed Central

    Bates, Karl T; Maidment, Susannah C R; Allen, Vivian; Barrett, Paul M

    2012-01-01

    Ornithischia (the ‘bird-hipped’ dinosaurs) encompasses bipedal, facultative quadrupedal and quadrupedal taxa. Primitive ornithischians were small bipeds, but large body size and obligate quadrupedality evolved independently in all major ornithischian lineages. Numerous pelvic and hind limb features distinguish ornithischians from the majority of other non-avian dinosaurs. However, some of these features, notably a retroverted pubis and elongate iliac preacetabular process, appeared convergently in maniraptoran theropods, and were inherited by their avian descendants. During maniraptoran/avian evolution these pelvic modifications led to significant changes in the functions of associated muscles, involving alterations to the moment arms and the activation patterns of pelvic musculature. However, the functions of these features in ornithischians and their influence on locomotion have not been tested and remain poorly understood. Here, we provide quantitative tests of bipedal ornithischian muscle function using computational modelling to estimate 3D hind limb moment arms for the most complete basal ornithischian, Lesothosaurus diagnosticus. This approach enables sensitivity analyses to be carried out to explore the effects of uncertainties in muscle reconstructions of extinct taxa, and allows direct comparisons to be made with similarly constructed models of other bipedal dinosaurs. This analysis supports some previously proposed qualitative inferences of muscle function in basal ornithischians. However, more importantly, this work highlights ambiguities in the roles of certain muscles, notably those inserting close to the hip joint. Comparative analysis reveals that moment arm polarities and magnitudes in Lesothosaurus, basal tetanuran theropods and the extant ostrich are generally similar. However, several key differences are identified, most significantly in comparisons between the moment arms of muscles associated with convergent osteological features in ornithischians and birds. Craniad migration of the iliofemoralis group muscles in birds correlates with increased leverage and use of medial femoral rotation to counter stance phase adduction moments at the hip. In Lesothosaurus the iliofemoralis group maintains significantly higher moment arms for abduction, consistent with the hip abduction mode of lateral limb support hypothesized for basal dinosaurs. Sensitivity analysis highlights ambiguity in the role of musculature associated with the retroverted pubis (puboischiofemoralis externus group) in ornithischians. However, it seems likely that this musculature may have predominantly functioned similarly to homologous muscles in extant birds, activating during the swing phase to adduct the lower limb through lateral rotation of the femur. Overall the results suggest that locomotor muscle leverage in Lesothosaurus (and by inference basal ornithischians in general) was more similar to that of other non-avian dinosaurs than the ostrich, representing what was probably the basal dinosaur condition. This work thereby contradicts previous hypotheses of ornithischian–bird functional convergence. PMID:22211275

  12. Plasticity of Adult Stem Cells

    Microsoft Academic Search

    Amy J Wagers; Irving L Weissman

    2004-01-01

    Recent years have seen much excitement over the possibility that adult mammalian stem cells may be capable of differentiating across tissue lineage boundaries, and as such may represent novel, accessible, and very versatile effectors of therapeutic tissue regeneration. Yet studies proposing such “plasticity” of adult somatic stem cells remain controversial, and in general, existing evidence suggests that in vivo such

  13. Systematic Palaeontology \\/ Paléontologie systématique (Vertebrate Palaeontology \\/ Paléontologie des Vertébrés) Dinosaurs of Portugal Dinosaures du Portugal

    Microsoft Academic Search

    Miguel Telles Antunes; Octávio Mateus

    A synthesis on the state of art on dinosaur knowledge in Portugal is presented. The following genera have been recognized: Ceratosaurus, Torvosaurus , Lourinhanosaurus, Allosaurus, cf. Compsognathus, Stokesosaurus , cf. Richardoestesia, cf. Archaeopteryx, Euronychodon,cf. Paronychodon, Dinheirosaurus, Lourinhasaurus, Lusotitan, cf. Pleurocoelus, Lusitanosau- rus, Dacentrurus, Dracopelta, Phyllodon, Hypsilophodon , Alocodon, Trimucrodon, Draconyx, Iguanodon , and Taveirosaurus. Most are from Late Jurassic localities

  14. A Theropod Dinosaur Embryo and the Affnities of the Flaming Cliffs Dinosaur Eggs

    Microsoft Academic Search

    Mark A. Norell; James M. Clark; Dashzeveg Demberelyin; Barsbold Rhinchen; Luis M. Chiappe; Amy R. Davidson; Malcolm C. McKenna; Perle Altangerel; Michael J. Novacek

    1994-01-01

    An embryonic skeleton of a nonavian theropod dinosaur was found preserved in an egg from Upper Cretaceous rocks in the Gobi Desert of Mongolia. Cranial features identify the embryo as a member of Oviraptoridae. Two embryo-sized skulls of dromaeosaurids, similar to that of Velociraptor, were also recovered in the nest. The eggshell microstructure is similar to that of ratite birds

  15. A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny

    Microsoft Academic Search

    Martin D. Ezcurra

    2010-01-01

    It was traditionally thought that the oldest known dinosaur assemblages were not diverse, and that their early diversification and numerical dominance over other tetrapods occurred during the latest Triassic. However, new evidence gathered from the lower levels of the Ischigualasto Fm. of Argentina challenges this view. New dinosaur remains are described from this stratigraphical unit, including the new species Chromogisaurus

  16. Generalized Potential of Adult Neural Stem Cells

    Microsoft Academic Search

    Diana L. Clarke; Clas B. Johansson; Johannes Wilbertz; Biborka Veress; Erik Nilsson; Helena Karlström; Urban Lendahl; Jonas Frisén

    2000-01-01

    The differentiation potential of stem cells in tissues of the adult has been thought to be limited to cell lineages present in the organ from which they were derived, but there is evidence that some stem cells may have a broader differentiation repertoire. We show here that neural stem cells from the adult mouse brain can contribute to the formation

  17. Epithelial stem cells, wound healing and cancer

    Microsoft Academic Search

    Esther N. Arwert; Esther Hoste; Fiona M. Watt

    2012-01-01

    It is well established that tissue repair depends on stem cells and that chronic wounds predispose to tumour formation. However, the association between stem cells, wound healing and cancer is poorly understood. Lineage tracing has now shown how stem cells are mobilized to repair skin wounds and how they contribute to skin tumour development. The signalling pathways, including WNT and

  18. Contribution of Stem Cells to Kidney Repair

    Microsoft Academic Search

    Benedetta Bussolati; Peter Viktor Hauser; Raquel Carvalhosa; Giovanni Camussi

    2009-01-01

    A current explanation for development of chronic renal injury is the imbalance between injurious mechanism and regenerative repair. The possibility that stem cells contribute to the repair of glomerular and tubular damage is of great interest for basic and translational research. Endogenous bone marrow-derived stem cells have been implicated in the repair of renal tissue, although the lineage of stem

  19. Upper jurassic dinosaur egg from utah.

    PubMed

    Hirsch, K F; Stadtman, K L; Miller, W E; Madsen, J H

    1989-03-31

    The Upper Jurassic egg described here is the first known egg from the 100-million-year gap in the fossil record between Lower Jurassic (South Africa) and upper Lower Cretaceous (Utah). The discovery of the egg, which was found mixed in with thousands of dinosaur bones rather than in a nest, the pathological multilayering of the eggshell as found in modern and fossil reptilians, and the pliable condition of the eggshell at the time of burial indicate an oviducal retention of the egg at the time of burial. PMID:17751281

  20. A palaeoequatorial ornithischian and new constraints on early dinosaur diversification.

    PubMed

    Barrett, Paul M; Butler, Richard J; Mundil, Roland; Scheyer, Torsten M; Irmis, Randall B; Sánchez-Villagra, Marcelo R

    2014-09-22

    Current characterizations of early dinosaur evolution are incomplete: existing palaeobiological and phylogenetic scenarios are based on a fossil record dominated by saurischians and the implications of the early ornithischian record are often overlooked. Moreover, the timings of deep phylogenetic divergences within Dinosauria are poorly constrained owing to the absence of a rigorous chronostratigraphical framework for key Late Triassic-Early Jurassic localities. A new dinosaur from the earliest Jurassic of the Venezuelan Andes is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date and the first-named dinosaur from northern South America. It expands the early palaeogeographical range of Ornithischia to palaeoequatorial regions, an area sometimes thought to be devoid of early dinosaur taxa, and offers insights into early dinosaur growth rates, the evolution of sociality and the rapid tempo of the global dinosaur radiation following the end-Triassic mass extinction, helping to underscore the importance of the ornithischian record in broad-scale discussions of early dinosaur history. PMID:25100698

  1. Hadrosaurus foulkii: Finding the World's First Dinosaur Skeleton

    NSDL National Science Digital Library

    Hoag Levins

    This site describes the discovery of a nearly-complete dinosaur skeleton, which occurred in 1858 in Haddonfield, New Jersey. There is information about what the Hadrosaurus dinosaur and its life was like and how the Haddonfield discovery led to the Bone Wars. The history of public displays of the skeleton as well as changes that were made in its stance and the shape of its skull based on new knowledge is explained. The site describes what the ravine where the first dinosaur bones were found is like today and how the fossil site was re-established and dedicated.

  2. Fossilized excreta associated to dinosaurs in Brazil

    NASA Astrophysics Data System (ADS)

    Souto, P. R. F.; Fernandes, M. A.

    2015-01-01

    This work provides an updated register of the main occurrences of fossilized excreta (coprolites and urolites) associated with dinosaurs found in the Brazil. The goal is to provide a relevant guide to the interpretation of the environment in the context of Gondwana. In four geographic areas, the excreta are recovered from Cretaceous sedimentary deposits in outcrops of the Bauru and Săo Luis basins and the Upper Jurassic aeolian deposits of the Parana Basin in the state of Săo Paulo. The coprolites were analyzed by X-ray diffraction and X-ray fluorescence methods. The results of these analyses reveal compositions that differ from the surrounding matrix, indicating a partial substitution of the organic material due to the feeding habits of the producers. Additionally, we describe the urolite excavations in epirelief and hyporelief, the result of gravitational flow the impact from urine jets on sand. These are associated with ornithopod and theropod dinosaur footprints preserved in the aeolian flagstones of the Botucatu Formation, Parana Basin.

  3. Lineage specificity of primary cilia in the mouse embryo.

    PubMed

    Bangs, Fiona K; Schrode, Nadine; Hadjantonakis, Anna-Katerina; Anderson, Kathryn V

    2015-02-01

    Primary cilia are required for vertebrate cells to respond to specific intercellular signals. Here we define when and where primary cilia appear in the mouse embryo using a transgenic line that expresses ARL13B-mCherry in cilia and Centrin 2-GFP in centrosomes. Primary cilia first appear on cells of the epiblast at E6.0 and are subsequently present on all derivatives of the epiblast. In contrast, extraembryonic cells of the visceral endoderm and trophectoderm lineages have centrosomes but no cilia. Stem cell lines derived from embryonic lineages recapitulate the in vivo pattern: epiblast stem cells are ciliated, whereas trophoblast stem cells and extraembryonic endoderm (XEN) stem cells lack cilia. Basal bodies in XEN cells are mature and can form cilia when the AURKA-HDAC6 cilium disassembly pathway is inhibited. The lineage-dependent distribution of cilia is stable throughout much of gestation, defining which cells in the placenta and yolk sac are able to respond to Hedgehog ligands. PMID:25599390

  4. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.

    PubMed

    Göhlich, Ursula B; Chiappe, Luis M

    2006-03-16

    Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought. PMID:16541071

  5. Fossil Footprints: How Fast Was That Dinosaur Moving?

    ERIC Educational Resources Information Center

    Caton, Randall; Otts, Charlotte

    1999-01-01

    Describes an activity in which students construct relationships between their leg lengths, stride lengths, and movements in order to estimate the speeds of the dinosaurs that made various fossilized tracks. (WRM)

  6. Response to Comments on "Evidence for mesothermy in dinosaurs".

    PubMed

    Grady, John M; Enquist, Brian J; Dettweiler-Robinson, Eva; Wright, Natalie A; Smith, Felisa A

    2015-05-29

    D'Emic and Myhrvold raise a number of statistical and methodological issues with our recent analysis of dinosaur growth and energetics. However, their critiques and suggested improvements lack biological and statistical justification. PMID:26023132

  7. Dinosaur Paleoecology: Determining the Diet of Ancient Animals

    NSDL National Science Digital Library

    David Davies

    In this activity student groups, after being given the proper background information, will work together to determine the likely food source and overall body shape for each animal from a single dinosaur tooth. Class discussion will then be initiated by naming the animal whose tooth was described, then showing color pictures of reconstructions of the dinosaur and its environment. Additional discussion will be centered on how each dinosaur was able to develop teeth so well suited to its particular lifestyle. This will lead to the students discovering the concept of adaptation and survival of the fittest. This activity also allows the topic of dinosaurs to be used to introduce basic topics of paleobiology such as predator/prey interactions, scientific methods of determining lifestyles of extinct animals, and processes of evolution.

  8. An Interdisciplinary Approach to Dinosaur Fossils, Morphology, Ethology, and Energetics.

    ERIC Educational Resources Information Center

    Zipko, Stephen J.

    1981-01-01

    Describes an interdisciplinary minicourse on dinosaur fossils, morphology, ethology, and energetics. Suggests and provides examples of hands-on activities for junior high school- through college-level students. (DS)

  9. Eggs tell story of baby dinosaurs' first steps

    NSDL National Science Digital Library

    American Association for the Advancement of Science (AAAS; )

    2005-07-28

    Scientists have discovered fossilized eggs containing developing dinosaurs that probably started out moving around on all four limbs before learning to walk only on only two legs -- kind of like people.

  10. New Discoveries about Dinosaurs: Separating the Facts from the News.

    ERIC Educational Resources Information Center

    Padian, Kevin

    1988-01-01

    Reviews discoveries and reports of dinosaurs to help put them into paleontological perspective. Proposes that discoveries not be announced from the field, but submitted to professional evaluation and peer review before release to the public. (Author/RT)

  11. Beyond T. rex: A Dinosaur Cladogram (title provided or enhanced by cataloger)

    NSDL National Science Digital Library

    Students will have the chance to see some strange and unusual dinosaurs they have never heard of when they can play with the cladogram. A cladogram is like a family tree. It's a way of organizing dinosaurs based on the unique characteristics they share, like a three-toed foot or a hole in the hip socket. In order to see the information the student will roll over a dinosaur's name to see its picture, click the dinosaur name and roll over a blue dot to discover how dinosaurs on a branch of this tree are related and what physical characteristics they share. Nineteen dinosaurs are featured.

  12. Furculae in the Late Triassic theropod dinosaur Coelophysis bauri

    Microsoft Academic Search

    Larry F. Rinehart; Spencer G. Lucas; Adrian P. Hunt

    2007-01-01

    Furculae have been identified in many dinosaurs and are synapomorphic in some clades (e.g., dromaeosaurids). All coelophysid\\u000a dinosaurs exceptCoelophysis bauri have been shown to possess furculae. To date, the oldest well-documented furculae have been those of the Early Jurassic coelophysids,Coelophysis kayentakatae andCoelophysis rhodesiensis. The confirmation of furculae in Apachean-agedC. bauri further documents appearance of these elements in the Late Triassic

  13. Computer-aided paleontology: a new look for dinosaurs

    Microsoft Academic Search

    D. I. Lewin

    2002-01-01

    Over the past 150 years, our perception of how dinosaurs looked has changed on the basis of museum displays and artists' renditions. Reproductions of lumbering dinosaurs at London's Crystal Palace during the mid 1800s look little like the creatures in the 40-year-old murals at Yale University's Peabody Museum of Natural History, or the computer-animated images of agile animals depicted in

  14. A new giant carnivorous dinosaur from the Cretaceous of Patagonia

    Microsoft Academic Search

    Rodolfo A. Coria; Leonardo Salgado

    1995-01-01

    LARGE carnivorous animals, the top members of the trophic chain, are rare, and flesh-eating dinosaurs were rarer still. For years the only known giant theropods were Tyrannosaums rex1 and the poorly known Deinocheirus mirificus2, both from the Northern Hemisphere, but many important new dinosaurs have been dis-covered in the Southern Hemisphere during the past decade, con-siderably increasing our knowledge of

  15. A new armored dinosaur from the Cretaceous of Kansas

    E-print Network

    Eaton, T. H., Jr.

    1960-11-21

    THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VE RTE BRATA ARTICLE 8 Pages 1-24, Figures 1-21 A NEW ARMORED DINOSAUR FROM THE CRETACEOUS OF KANSAS By THEODORE H. EATON, JR. (Contribution from the Museum of Natural History) THE UNIVERSITY... OF KANSAS PUBLICATIONS November 21, 1960 PRINTED BY THE UNIVERSITY OF KANSAS PRESS LAWRENCE THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VERTEBRATA, ARTICLE 8, PAGES 1-24, FIGURES 1-21 A NEW ARMORED DINOSAUR FROM THE CRETACEOUS OF KANSAS...

  16. Pulmonary function and metabolic physiology of theropod dinosaurs

    PubMed

    Ruben; Dal Sasso C; Geist; Hillenius; Jones; Signore

    1999-01-22

    Ultraviolet light analysis of a fossil of the theropod dinosaur Scipionyx samniticus revealed that the liver subdivided the visceral cavity into distinct anterior pleuropericardial and posterior abdominal regions. In addition, Scipionyx apparently had diaphragmatic musculature and a dorsally attached posterior colon. These features provide evidence that diaphragm-assisted lung ventilation was present in theropods and that these dinosaurs may have used a pattern of exercise physiology unlike that in any group of living tetrapods. PMID:9915693

  17. Introduction to the Hadrosaurs: "Duck-billed" Dinosaurs

    NSDL National Science Digital Library

    Hadrosaurs, the "duckbilled dinosaurs", were common in the Upper Cretaceous of Europe, Asia, and North America. They were members of the Ornithopoda, and close relatives and possibly descendants of the earlier iguanodontid dinosaurs. The morphology of the two subfamilies, Lambeosaurinae and Hadrosaurinae, is discussed, including the purpose of the crest on the head of the former. Two other fossils are also described, Edmontosaurus and a baby Maiasaura.

  18. Semiaquatic adaptations in a giant predatory dinosaur.

    PubMed

    Ibrahim, Nizar; Sereno, Paul C; Dal Sasso, Cristiano; Maganuco, Simone; Fabbri, Matteo; Martill, David M; Zouhri, Samir; Myhrvold, Nathan; Iurino, Dawid A

    2014-09-26

    We describe adaptations for a semiaquatic lifestyle in the dinosaur Spinosaurus aegyptiacus. These adaptations include retraction of the fleshy nostrils to a position near the mid-region of the skull and an elongate neck and trunk that shift the center of body mass anterior to the knee joint. Unlike terrestrial theropods, the pelvic girdle is downsized, the hindlimbs are short, and all of the limb bones are solid without an open medullary cavity, for buoyancy control in water. The short, robust femur with hypertrophied flexor attachment and the low, flat-bottomed pedal claws are consistent with aquatic foot-propelled locomotion. Surface striations and bone microstructure suggest that the dorsal "sail" may have been enveloped in skin that functioned primarily for display on land and in water. PMID:25213375

  19. Largest Dinosaur Ever Discovered Found in Oklahoma

    NSDL National Science Digital Library

    de Nie, Michael Willem.

    Originally discovered in a remote corner of Oklahoma in 1994, the fossil of what may have been the largest creature to ever walk the earth has been excavated by a research team from the University of Oklahoma. Dubbed Sauroposeidon proteles, or "thunder lizard," the dinosaur was almost 100 feet long, with a 39 foot neck and weighing over 50 tons, so big that it would have created minor seismic activity just by walking, according to scientists. The new find is about 110 million years old and consists of neck vertebrae, some almost five feet in length, together with neck ribs nearly twelve feet long. The find is also significant because it may shed light on the last of the North American sauropods, who died out about 100 million years ago. A paper on this new find is scheduled to appear in the Journal of Vertebrate Paleontology. The sites listed provide information and background material about this momentous discovery.

  20. Skeletal stem cells.

    PubMed

    Bianco, Paolo; Robey, Pamela G

    2015-03-15

    Skeletal stem cells (SSCs) reside in the postnatal bone marrow and give rise to cartilage, bone, hematopoiesis-supportive stroma and marrow adipocytes in defined in vivo assays. These lineages emerge in a specific sequence during embryonic development and post natal growth, and together comprise a continuous anatomical system, the bone-bone marrow organ. SSCs conjoin skeletal and hematopoietic physiology, and are a tool for understanding and ameliorating skeletal and hematopoietic disorders. Here and in the accompanying poster, we concisely discuss the biology of SSCs in the context of the development and postnatal physiology of skeletal lineages, to which their use in medicine must remain anchored. PMID:25758217

  1. Common Avian Infection Plagued the Tyrant Dinosaurs

    PubMed Central

    Wolff, Ewan D. S.; Salisbury, Steven W.; Horner, John R.; Varricchio, David J.

    2009-01-01

    Background Tyrannosaurus rex and other tyrannosaurid fossils often display multiple, smooth-edged full-thickness erosive lesions on the mandible, either unilaterally or bilaterally. The cause of these lesions in the Tyrannosaurus rex specimen FMNH PR2081 (known informally by the name ‘Sue’) has previously been attributed to actinomycosis, a bacterial bone infection, or bite wounds from other tyrannosaurids. Methodology/Principal Findings We conducted an extensive survey of tyrannosaurid specimens and identified ten individuals with full-thickness erosive lesions. These lesions were described, measured and photographed for comparison with one another. We also conducted an extensive survey of related archosaurs for similar lesions. We show here that these lesions are consistent with those caused by an avian parasitic infection called trichomonosis, which causes similar abnormalities on the mandible of modern birds, in particular raptors. Conclusions/Significance This finding represents the first evidence for the ancient evolutionary origin of an avian transmissible disease in non-avian theropod dinosaurs. It also provides a valuable insight into the palaeobiology of these now extinct animals. Based on the frequency with which these lesions occur, we hypothesize that tyrannosaurids were commonly infected by a Trichomonas gallinae-like protozoan. For tyrannosaurid populations, the only non-avian dinosaur group that show trichomonosis-type lesions, it is likely that the disease became endemic and spread as a result of antagonistic intraspecific behavior, consumption of prey infected by a Trichomonas gallinae-like protozoan and possibly even cannibalism. The severity of trichomonosis-related lesions in specimens such as Tyrannosaurus rex FMNH PR2081 and Tyrannosaurus rex MOR 980, strongly suggests that these animals died as a direct result of this disease, mostly likely through starvation. PMID:19789646

  2. Mice in the world of stem cell biology

    Microsoft Academic Search

    Geraldine Guasch; Elaine Fuchs

    2005-01-01

    The ability of embryos to diversify and of some adult tissues to regenerate throughout life is directly attributable to stem cells. These cells have the capacity to self-renew—that is, to divide and to create additional stem cells—and to differentiate along a specific lineage. The differentiation of pluripotent embryonic stem cells along specific cell lineages has been used to understand the

  3. HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007

    E-print Network

    Holtz Jr., Thomas R.

    1 HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007 Critical...) But how can we determine how extinct dinosaurs moved and operated in the living world? One approach

  4. First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition

    NASA Astrophysics Data System (ADS)

    Chure, Daniel; Britt, Brooks B.; Whitlock, John A.; Wilson, Jeffrey A.

    2010-04-01

    Sauropod dinosaur bones are common in Mesozoic terrestrial sediments, but sauropod skulls are exceedingly rare—cranial materials are known for less than one third of sauropod genera and even fewer are known from complete skulls. Here we describe the first complete sauropod skull from the Cretaceous of the Americas, Abydosaurus mcintoshi, n. gen., n. sp., known from 104.46 ± 0.95 Ma (megannum) sediments from Dinosaur National Monument, USA. Abydosaurus shares close ancestry with Brachiosaurus, which appeared in the fossil record ca. 45 million years earlier and had substantially broader teeth. A survey of tooth shape in sauropodomorphs demonstrates that sauropods evolved broad crowns during the Early Jurassic but did not evolve narrow crowns until the Late Jurassic, when they occupied their greatest range of crown breadths. During the Cretaceous, brachiosaurids and other lineages independently underwent a marked diminution in tooth breadth, and before the latest Cretaceous broad-crowned sauropods were extinct on all continental landmasses. Differential survival and diversification of narrow-crowned sauropods in the Late Cretaceous appears to be a directed trend that was not correlated with changes in plant diversity or abundance, but may signal a shift towards elevated tooth replacement rates and high-wear dentition. Sauropods lacked many of the complex herbivorous adaptations present within contemporaneous ornithischian herbivores, such as beaks, cheeks, kinesis, and heterodonty. The spartan design of sauropod skulls may be related to their remarkably small size—sauropod skulls account for only 1/200th of total body volume compared to 1/30th body volume in ornithopod dinosaurs.

  5. First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition.

    PubMed

    Chure, Daniel; Britt, Brooks B; Whitlock, John A; Wilson, Jeffrey A

    2010-04-01

    Sauropod dinosaur bones are common in Mesozoic terrestrial sediments, but sauropod skulls are exceedingly rare--cranial materials are known for less than one third of sauropod genera and even fewer are known from complete skulls. Here we describe the first complete sauropod skull from the Cretaceous of the Americas, Abydosaurus mcintoshi, n. gen., n. sp., known from 104.46 +/- 0.95 Ma (megannum) sediments from Dinosaur National Monument, USA. Abydosaurus shares close ancestry with Brachiosaurus, which appeared in the fossil record ca. 45 million years earlier and had substantially broader teeth. A survey of tooth shape in sauropodomorphs demonstrates that sauropods evolved broad crowns during the Early Jurassic but did not evolve narrow crowns until the Late Jurassic, when they occupied their greatest range of crown breadths. During the Cretaceous, brachiosaurids and other lineages independently underwent a marked diminution in tooth breadth, and before the latest Cretaceous broad-crowned sauropods were extinct on all continental landmasses. Differential survival and diversification of narrow-crowned sauropods in the Late Cretaceous appears to be a directed trend that was not correlated with changes in plant diversity or abundance, but may signal a shift towards elevated tooth replacement rates and high-wear dentition. Sauropods lacked many of the complex herbivorous adaptations present within contemporaneous ornithischian herbivores, such as beaks, cheeks, kinesis, and heterodonty. The spartan design of sauropod skulls may be related to their remarkably small size--sauropod skulls account for only 1/200th of total body volume compared to 1/30th body volume in ornithopod dinosaurs. PMID:20179896

  6. Comparison of Multi-Lineage Cells from Human Adipose Tissue and Bone Marrow

    Microsoft Academic Search

    Daniel A. De Ugarte; Kouki Morizono; Amir Elbarbary; Zeni Alfonso; Patricia A. Zuk; Min Zhu; Jason L. Dragoo; Peter Ashjian; Bert Thomas; Prosper Benhaim; Irvin Chen; John Fraser; Marc H. Hedrick

    2003-01-01

    Our laboratory has recently characterized a population of cells from adipose tissue, termed processed lipoaspirate (PLA) cells, which have multi-lineage potential similar to bone-marrow-derived mesenchymal stem cells (MSCs). This study is the first comparison of PLA cells and MSCs isolated from the same patient. No significant differences were observed for yield of adherent stromal cells, growth kinetics, cell senescence, multi-lineage

  7. K-Pg events facilitated lineage transitions between terrestrial and aquatic ecosystems.

    PubMed

    Proche?, Serban; Polgar, Gianluca; Marshall, David J

    2014-06-01

    We use dated phylogenetic trees for tetrapod vertebrates to identify lineages that shifted between terrestrial and aquatic ecosystems in terms of feeding or development, and to assess the timing of such events. Both stem and crown lineage ages indicate a peak in transition events in correspondence with the K-Pg mass extinction. This meets the prediction that changes in competitive pressure and resource availability following mass extinction events should facilitate such transitions. PMID:24919699

  8. Temporal and Embryonic Lineage-Dependent Regulation of Human Vascular SMC Development by NOTCH3

    E-print Network

    Granata, Alessandra; Bernard, William G.; Zhao, Ning; Mccafferty, John; Lilly, Brenda; Sinhav, Sanjay

    2014-12-24

    M, ME Verberne, MC DeRuiter, RE Poelmann and AC Gittenberger-de Groot (1998). Neural crest cell contribution to the developing circulatory system: implications for vascular morphology? Circ Res 82: 221–231. 4. Boucher J, T Gridley and L Liaw (2012... generated an in vitro model for lineage-specific vascular SMC originating from human pluripotent stem cells (hpsc) [8]. Origin-specific smcs derived using this system replicate many of the known differences between SMC of different lineages...

  9. K-Pg events facilitated lineage transitions between terrestrial and aquatic ecosystems

    PubMed Central

    Proche?, ?erban; Polgar, Gianluca; Marshall, David J.

    2014-01-01

    We use dated phylogenetic trees for tetrapod vertebrates to identify lineages that shifted between terrestrial and aquatic ecosystems in terms of feeding or development, and to assess the timing of such events. Both stem and crown lineage ages indicate a peak in transition events in correspondence with the K-Pg mass extinction. This meets the prediction that changes in competitive pressure and resource availability following mass extinction events should facilitate such transitions. PMID:24919699

  10. DinoViz: Exploring the History and Nature of Science through the Progression of Dinosaur Visualization

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2011-01-01

    Dinosaurs in the middle school classroom can be exciting. These extinct reptiles are both an exotic subject and familiar to our students. Because students are inherently interested, dinosaurs can serve as an effective portal for the integration of biology, geology, ecology, and the history and nature of science. The field of dinosaur study is…

  11. A critical re?evaluation of the Late Triassic dinosaur taxa of North America

    Microsoft Academic Search

    Sterling J. Nesbitt; Randall B. Irmis; William G. Parker

    2007-01-01

    The North American Triassic dinosaur record has been repeatedly cited as one of the most complete early dinosaur assemblages. The discovery of Silesaurus from Poland and the recognition that Herrerasaurus and Eoraptor may not be theropods have forced a re?evaluation of saurischian and theropod synapomorphies. Here, we re?evaluate each purported Triassic dinosaur from North America on a specimen by specimen

  12. Paleobiological implications of dinosaur egg-bearing deposits in the Cretaceous Gyeongsang Supergroup of Korea

    Microsoft Academic Search

    In Sung Paik; Hyun Joo Kim; Min Huh

    2010-01-01

    Dinosaur egg-bearing deposits in the Cretaceous Gyeongsang Basin in Korea is described in taphonomic aspect, their paleoenvironments are interpreted, and geobiological implications of dinosaur egg-bearing deposits in the world and Korea are analyzed in geographic occurrences, geological ages, paleoenvironments, and lithology. Dinosaur eggs with spheroolithids, faveoloolithid, and elongatoolithid structural types occur in several stratigraphic formations of the Cretaceous Gyeongsang Basin

  13. Dinosaur and turtle tracks from the Laramie\\/Arapahoe formations (Upper Cretaceous), near Denver, Colorado, USA

    Microsoft Academic Search

    Joanna Wright; Martin Lockley

    2001-01-01

    A large slab showing more than two dozen dinosaur footprints discovered in the Upper Cretaceous (Maastrichtian) Laramie or Arapahoe Formation near Denver, Colorado, represents the first significant find of dinosaur tracks in the greater Denver metropolitan area in more than a decade. The tracks are all of tridactyl bipeds and appear to be mainly attributable to theropod dinosaurs, although some

  14. Dinosaurs in the Early and Mid Triassic?—The footprint evidence from Britain

    Microsoft Academic Search

    Michael J. King; Michael J. Benton

    1996-01-01

    The oldest skeletons of dinosaurs date from the Late Triassic (Carnian), but supposed dinosaur footprints have been reported from Lower and Mid Triassic rocks, dated up to 20 m.y. earlier. Supposed Lower Triassic dinosaur footprints from Britain are reinterpreted as ripple marks, mud rip-up clasts, and possible limulid prints. The Middle Triassic material is reinterpreted as partial specimens of Chirotherium,

  15. HONR 259C "Fearfully Great Lizards": Topics in Dinosaur Research Test I Review

    E-print Network

    Holtz Jr., Thomas R.

    HONR 259C "Fearfully Great Lizards": Topics in Dinosaur Research Test I Review The nature of Science and the nature of research Major events and figures in the history of dinosaur paleontology: Baron the other; Type III: neither EPB has same state that you infer for the fossil) Dinosaur Origins Where do

  16. A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous of China

    E-print Network

    Cambridge, University of

    A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous. 2012. A reassessment of Kelmayisaurus petrolicus, a large theropod dinosaur from the Early Cretaceous-bodied theropods from Asia is poor, hindering comparison of Asian predatory dinosaur faunas with those from other

  17. Predation upon Hatchling Dinosaurs by a New Snake from the Late Cretaceous of India

    E-print Network

    Peters, Shanan E.

    Predation upon Hatchling Dinosaurs by a New Snake from the Late Cretaceous of India Jeffrey A India. S. indicus was fossilized in association with a sauropod dinosaur egg clutch, coiled around and demonstrate predation risks for hatchling sauropod dinosaurs. Our results suggest that large body size and jaw

  18. Communiqu de presse -Mars 2013 Prolongation de l'exposition Dinosaure, la vie en grand

    E-print Network

    Communiqué de presse - Mars 2013 Prolongation de l'exposition « Dinosaure, la vie en grand » jusqu'au 24 juin 2013 En raison de son vif succčs auprčs du public, l'exposition « Dinosaure, la vie en grand dinosaures : les sauropodes, des herbivores géants, pouvant peser 90 tonnes, et qui ont vécu pendant environ

  19. HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007

    E-print Network

    Holtz Jr., Thomas R.

    HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007 Preliminary:xxx-xxx. Prasad, V., C.A.E. Strömberg, H. Alimohammadian & A. Sahni. 2005. Dinosaur coprolites and the early. Cannibalism in the Madagascan dinosaur Majungatholus atopus. Nature 422:515-518. TOPIC 2: Trace Fossil

  20. Occurrence of sauropod dinosaur tracks in the Upper Jurassic of Chile (redescription of Iguanodonichnus frenki)

    E-print Network

    Benton, Michael

    Occurrence of sauropod dinosaur tracks in the Upper Jurassic of Chile (redescription studied Upper Jurassic dinosaur unit in South America, the Ban~os del Flaco Formation, Chile. Keywords: Chile; Dinosaur footprints; Parabrontopodus; Sauropod; Upper Jurassic Resu´men En el presente

  1. Therizinosauroid dinosaurs grew up fast. When they chipped their way out of an

    E-print Network

    Jackson, Kate

    Therizinosauroid dinosaurs grew up fast. When they chipped their way out of an egg, the animals- lion-year-old fossil dinosaur eggs con- ducted by a team of paleontologists and developmental the dinosaur embryos with em- bryos of birds and alligators, Kundrát has determined how far along

  2. Extra genomes helped plants to survive extinction event that killed dinosaurs

    E-print Network

    Gent, Universiteit

    Extra genomes helped plants to survive extinction event that killed dinosaurs Category: Evolution, the dinosaurs. The fate of the planet's plants is less familiar, but 60% of those also perished. What separated with the dramatic environmental changes that wiped out the dinosaurs and other less wellendowed species. Time

  3. Protecting Utah's Fossil Treasures Hunter Almost Gets Away With New Dinosaur

    E-print Network

    Johnson, Cari

    Protecting Utah's Fossil Treasures Hunter Almost Gets Away With New Dinosaur Because everything. Such was the case that eventually led to the identification and naming of Falcarius utahensis, a new dinosaur dinosaur remains. To thwart discovery, he had dug tunnels, removing blocks of stone and discarding pieces

  4. HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007

    E-print Network

    Holtz Jr., Thomas R.

    1 HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007 Critical Review IV: Dinosaur Growth and Behavior DUE: Thursday April 19 Overview Sometimes people tend to think of dinosaurs--or other animals, for that matter--as if they were only adults. Yet all animals start off

  5. NEW INFORMATION ON SEGISAURUS HALLI, A SMALL THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ARIZONA

    E-print Network

    Hutchinson, John

    NEW INFORMATION ON SEGISAURUS HALLI, A SMALL THEROPOD DINOSAUR FROM THE EARLY JURASSIC OF ARIZONA, a small Early Jurassic dinosaur and the only theropod known from the Navajo Sandstone. Our study unknown in dinosaurs), seemingly solid centra and limb bones (atypical for theropods), and accessory

  6. Author's personal copy Naming the Bristol dinosaur, Thecodontosaurus: politics and science in the 1830s

    E-print Network

    Benton, Michael

    Author's personal copy Naming the Bristol dinosaur, Thecodontosaurus: politics and science. Introduction The circumstances of the discovery and naming of the first dinosaurs ever reported, Megalosaurus, 1984; Buffetaut, 1987; Torrens, 1992, 1995; Torrens, 2012). The fourth dinosaur to be named from

  7. 18.1. Cladogram showing suggested relationships of the basal dinosaurs.

    E-print Network

    Benton, Michael

    18.1. Cladogram showing suggested relationships of the basal dinosaurs. Courtesy of Max Langer. FPO CompleteD2E.indd 336 12/21/11 4:49 PM #12;337 Origin and Early Evolution of Dinosaurs Michael J. Benton 18 The dinosaurs arose in the Triassic, and probably during the Early to Mid- dle Triassic. They entered a world

  8. A new large-bodied theropod dinosaur from the Middle Jurassic of Warwickshire, United Kingdom

    E-print Network

    Cambridge, University of

    A new large-bodied theropod dinosaur from the Middle Jurassic of Warwickshire, United Kingdom ROGER dinosaur from the Middle Jurassic of Warwickshire, United Kingdom. Acta Palaeontologica Polonica 55 (1): 35-bodied theropod dinosaur, distinct from the contemporaneous Megalosaurus bucklandii. Cruxicheiros newmanorum gen

  9. The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye

    E-print Network

    Benton, Michael

    The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye M. J right tibia of a carnivorous dinosaur is reported from the Lower Jurassic Broadford Beds Formation characteristic features of the ceratosaur theropods, a group of medium-sized predatory dinosaurs that were

  10. Detecting Dinosaur DNA The fact that DNA sequence can be ob-

    E-print Network

    Hedges, Blair

    N COMMEN Detecting Dinosaur DNA The fact that DNA sequence can be ob- tained from fossil organisms fragments ap- parently from a dinosaur that lived 80 mil- lion years ago (2). However, the likely source (1). In the case of a possible dinosaur sequence, there is strong evidence from morphology that birds

  11. On the Meaning of Words and Dinosaur Bones: Lexical Knowledge Without a Lexicon

    E-print Network

    Elman, Jeff

    On the Meaning of Words and Dinosaur Bones: Lexical Knowledge Without a Lexicon Jeffrey L. Elman to Hebb's (1949) paleontologist, who uses his beliefs and knowledge about dinosaurs in conjunction- tologist, and the dinosaur, to the meaning conveyed through these clues. (p. 140) David Rumelhart (1979) 1

  12. L E T T E R Bizarre structures in dinosaurs: species recognition or

    E-print Network

    Knell, Rob

    L E T T E R Bizarre structures in dinosaurs: species recognition or sexual selection? A response' struc- tures) of dinosaurs ­ for example, the horns and frills of ceratopsids, the crests examples of exaggerated structures among dinosaurs pass both of these tests, indicating that species

  13. 2006 Nature Publishing Group A new carnivorous dinosaur from the Late Jurassic

    E-print Network

    Cai, Long

    © 2006 Nature Publishing Group A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago Ursula B. Go¨hlich1 & Luis M. Chiappe2 Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus1

  14. HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007

    E-print Network

    Holtz Jr., Thomas R.

    1 HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007 Critical and scary, the most important thing about dinosaurs that the general public knows is that they died off was the extinction of the non-avian dinosaurs catastrophic? The extinction event between the Maastrichtian Age

  15. HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007

    E-print Network

    Holtz Jr., Thomas R.

    1 HONR 259C: "Fearfully Great Lizards": Topics in Dinosaur Research Spring Semester 2007 Critical of dinosaur fossils merely in terms of body fossils: skeletons and isolated teeth and bones. But trace fossils of dinosaurs. After all, while body fossils are parts of dead individuals, trace fossils were made

  16. Deccan volcanism, the KT mass extinction and dinosaurs 709 J. Biosci. 34(5), November 2009

    E-print Network

    Keller, Gerta

    Deccan volcanism, the KT mass extinction and dinosaurs 709 J. Biosci. 34(5), November 2009 1 to or even significantly contributed to the extinction of the dinosaurs and many other groups has lagged volcanism, the KT mass extinction and dinosaurs G KELLER1,* , A SAHNI2 and S BAJPAI3 1 Geosciences

  17. Homology of the palpebral and origin of supraorbital ossifications in ornithischian dinosaurs

    E-print Network

    Homology of the palpebral and origin of supraorbital ossifications in ornithischian dinosaurs and origin of supraor- bital ossifications in ornithischian dinosaurs. Lethaia, 10.1111/j.1502 dinosaurs and its presence is considered a synapomorphy of the clade. By contrast, other ornithischians lack

  18. The end of the sauropod dinosaur hiatus in North America Michael D. D'Emic a,

    E-print Network

    Thompson, Richard Maxwell

    The end of the sauropod dinosaur hiatus in North America Michael D. D'Emic a, , Jeffrey A. Wilson 19 September 2010 Keywords: Dinosaur Sauropod Titanosaur Alamosaurus Hadrosaur Biogeography Cretaceous Sauropod dinosaurs reached their acme in abundance and diversity in North America during the Late

  19. Pattullo Fellowship Application Environmental Issue Literary Piece A Dinosaur Fish Back from the Brink of Extinction

    E-print Network

    Pattullo Fellowship Application Environmental Issue Literary Piece 1 A Dinosaur Fish Back from on the Yellow River along the Florida panhandle, you might not expect to see a dinosaur. But, that's exactly sturgeon (Acipenser oxyrinchus desotoi). These fish are, in fact, a "living dinosaur." Gulf sturgeon first

  20. Anatomy and Cranial Functional Morphology of the Small-Bodied Dinosaur Fruitadens haagarorum from the

    E-print Network

    Anatomy and Cranial Functional Morphology of the Small-Bodied Dinosaur Fruitadens haagarorum from The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, California, United States radiation of ornithischian dinosaurs. The late-surviving heterodontosaurid Fruitadens haagarorum from

  1. Clonal Tracking of Rhesus Macaque Hematopoiesis Highlights A Distinct Lineage Origin for Natural Killer Cells

    PubMed Central

    Koelle, Samson J.; Yang, Yanqin; Jares, Alexander; Krouse, Alan E.; Metzger, Mark; Liang, Frank; Loré, Karin; Wu, Colin O.; Donahue, Robert E.; Chen, Irvin S.Y; Weissman, Irving; Dunbar, Cynthia E.

    2014-01-01

    Summary Analysis of hematopoietic stem cell function in non-human primates provides insights that are relevant for human biology and therapeutic strategies. In this study, we applied quantitative genetic barcoding to track the clonal output of transplanted autologous rhesus macaque hematopoietic stem and progenitor cells over a time period of up to 9.5 months. We found that uni-lineage short-term progenitors reconstituted myeloid and lymphoid lineages at one month, but were supplanted over time by multi-lineage clones, initially myeloid-restricted, then myeloid-B clones, and then stable myeloid-B-T multi-lineage long-term repopulating clones. Surprisingly, reconstitution of the natural killer cell lineage, and particularly the major CD16+/CD56? peripheral blood NK compartment, showed limited clonal overlap with T, B or myeloid lineages, and therefore appears to be ontologically distinct. Thus, in addition to providing insights into clonal behavior over time, our analysis suggests an unexpected paradigm for the relationship between NK cells and other hematopoietic lineages in primates. PMID:24702997

  2. Cell Stem Cell Secretion of Shh by a Neurovascular Bundle Niche

    E-print Network

    Klein, Ophir

    Cell Stem Cell Article Secretion of Shh by a Neurovascular Bundle Niche Supports Mesenchymal Stem. To address this issue, we used lineage tracing in a mouse incisor model and identified the neurovascular

  3. Diachronism between extinction time of terrestrial and marine dinosaurs

    NASA Technical Reports Server (NTRS)

    Hansen, H. J.

    1988-01-01

    The dinosaur eggs of southern France occur in continental, fine-grained red-beds, rich in carbonate. The last eggs in the region occur in the magnetic polarity interval 30 normal. Estimates of the accumulation rate of these sediments on the basis of the magneto-stratigraphy leads to placement of the time of disappearance of the dinosaurs in this region of 200,000 to 400,000 years earlier than the Cretaceous-Tertiary boundary. In the Red Deer Valley, Canada, estimates of average accumulation rate lead to a time of disappearance of the dinosaurs of 135,000 to 157,000 years earlier than the Cretaceous-Tertiary boundary. In the central part of Poland, in the Nasilow Quarry, the paleomagnetic pattern shows 7 m of chalk of reversed polarity containing in its upper part the marine Cretaceous-Tertiary biostratigraphic boundary. A greensand deposit contains numerous re-deposited Maastrichtian fossils. The fossils show no signs of wear and are of very different sizes including 1 mm thick juvenile belemnites. The deposit was described as a lag-sediment. Among the various fossils are teeth of mosasaurs. Thus there is coincidence in time between the extinction of mosasaurs and other Cretaceous organisms. This leads to the conclusion, that extinction of terrestrial dinosaurs took place earlier than extinction of marine dinosaurs at the Cretaceous-Tertiary boundary.

  4. First New Zealand record of probable dinosaur footprints from the Late Cretaceous North Cape Formation, northwest Nelson

    Microsoft Academic Search

    Greg H. Browne

    2009-01-01

    Structures that are interpreted as dinosaur footprints are recorded from six localities within the Late Cretaceous (Maastrictian) aged North Cape Formation of northwest Nelson. These are the first dinosaur footprints to be recognised from New Zealand and the first occurrence of dinosaurs from the South Island, and add considerably to our knowledge of New Zealand dinosaurs, which currently is based

  5. Controlled differentiation of stem cells?

    PubMed Central

    Hwang, Nathaniel S.; Varghese, Shyni; Elisseeff, Jennifer

    2009-01-01

    The extracellular microenvironment plays a significant role in controlling cellular behavior. Identification of appropriate biomaterials that support cellular attachment, proliferation and, most importantly in the case of human embryonic stem cells, lineage-specific differentiation is critical for tissue engineering and cellular therapy. In addition to growth factors and morphogenetic factors known to induce lineage commitment of stem cells, a number of scaffolding materials, including synthetic and naturally-derived biomaterials, have been utilized in tissue engineering approaches to direct differentiation. This review focuses on recent emerging findings and well-characterized differentiation models of human embryonic stem cells. Additionally, we also discuss about various strategies that have been used in stem cell expansion. PMID:18006108

  6. TAZ, a Transcriptional Modulator of Mesenchymal Stem

    E-print Network

    TAZ, a Transcriptional Modulator of Mesenchymal Stem Cell Differentiation Jeong-Ho Hong,1 Eun Sook Benjamin,4 Bruce M. Spiegelman,5 Phillip A. Sharp,1 Nancy Hopkins,1 Michael B. Yaffe1,2 * Mesenchymal stem cells (MSCs) are a pluripotent cell type that can differentiate into several distinct lineages. Two key

  7. New insights into liver stem cells

    Microsoft Academic Search

    E. Gaudio; G. Carpino; V. Cardinale; A. Franchitto; P. Onori; D. Alvaro

    2009-01-01

    Hepatic progenitor cells are bi-potential stem cells residing in human and animal livers that are able to differentiate towards the hepatocytic and the cholangiocytic lineages. In adult livers, hepatic progenitor cells are quiescent stem cells with a low proliferating rate, representing a reserve compartment that is activated only when the mature epithelial cells of the liver are continuously damaged or

  8. Lipid metabolism greases the stem cell engine.

    PubMed

    Folmes, Clifford D L; Park, Sungjo; Terzic, Andre

    2013-02-01

    Metabolic plasticity is increasingly postulated to be vital in the transition between stemness maintenance and lineage specification. Knobloch et al. (2012) now demonstrate that regulation of lipogenesis by fatty acid synthase and Spot14-dependent malonyl-CoA supply determines the proliferative activity of resident neural stem cells, contributing to adult neurogenesis. PMID:23395162

  9. Stem cells from adipose tissue

    Microsoft Academic Search

    Malgorzata Witkowska-Zimny; Katarzyna Walenko

    2011-01-01

    This is a review of the growing scientific interest in the developmental plasticity and therapeutic potential of stromal cells\\u000a isolated from adipose tissue. Adipose-derived stem\\/stromal cells (ASCs) are multipotent somatic stem cells that are abundant\\u000a in fat tissue. It has been shown that ASCs can differentiate into several lineages, including adipose cells, chondrocytes,\\u000a osteoblasts, neuronal cells, endothelial cells, and cardiomyocytes.

  10. Existence of Reserve Quiescent Stem Cells in Adults, From Amphibians to Humans

    Microsoft Academic Search

    H. E. Young

    \\u000a Several theories have been proposed to explain the phenomenon of tissue restoration in amphibians and higher order animals.\\u000a These theories include dedifferentiation of damaged tissues, transdifferentiation of lineage-committed stem cells, and activation\\u000a of quiescent stem cells. Young and colleagues demonstrated that connective tissues throughout the body contain multiple populations\\u000a of quiescent lineagecommitted progenitor stem cells and lineage-uncommitted pluripotent stem cells.

  11. The First Dinosaur from Washington State and a Review of Pacific Coast Dinosaurs from North America

    PubMed Central

    2015-01-01

    We describe the first diagnostic dinosaur fossil from Washington State. The specimen, which consists of a proximal left femur, was recovered from the shallow marine rocks of the Upper Cretaceous (Campanian) Cedar District Formation (Nanaimo Group) and is interpreted as pertaining to a large theropod on the basis of its hollow medullary cavity and proximally placed fourth trochanter. The Washington theropod represents one of the northernmost occurrences of a Mesozoic dinosaur on the west coast of the United States and one of only a handful from the Pacific coast of Laramidia during the Cretaceous. Its isolated nature and preservation in marine rocks suggest that the element was washed in from a nearby fluvial system. If the femur pertains to a tyrannosauroid, which seems likely given its size and the widespread occurrence of the group across Laramidia during Late Cretaceous times, then it would represent an earlier occurrence of large body size than previously recognized (complete femur length estimated at 1.2 meters). Uncertainty surrounding the latitude of deposition of the Nanaimo Group (i.e., the Baja-British Columbia hypothesis) precludes assigning the Washington theropod to either of the putative northern or southern biogeographic provinces of Laramidia. PMID:25993090

  12. The first dinosaur from washington state and a review of pacific coast dinosaurs from north america.

    PubMed

    Peecook, Brandon R; Sidor, Christian A

    2015-01-01

    We describe the first diagnostic dinosaur fossil from Washington State. The specimen, which consists of a proximal left femur, was recovered from the shallow marine rocks of the Upper Cretaceous (Campanian) Cedar District Formation (Nanaimo Group) and is interpreted as pertaining to a large theropod on the basis of its hollow medullary cavity and proximally placed fourth trochanter. The Washington theropod represents one of the northernmost occurrences of a Mesozoic dinosaur on the west coast of the United States and one of only a handful from the Pacific coast of Laramidia during the Cretaceous. Its isolated nature and preservation in marine rocks suggest that the element was washed in from a nearby fluvial system. If the femur pertains to a tyrannosauroid, which seems likely given its size and the widespread occurrence of the group across Laramidia during Late Cretaceous times, then it would represent an earlier occurrence of large body size than previously recognized (complete femur length estimated at 1.2 meters). Uncertainty surrounding the latitude of deposition of the Nanaimo Group (i.e., the Baja-British Columbia hypothesis) precludes assigning the Washington theropod to either of the putative northern or southern biogeographic provinces of Laramidia. PMID:25993090

  13. Global aspects of dinosaur distribution and evolution

    SciTech Connect

    Sues, H.

    1988-02-01

    Late Jurassic dinosaurian assemblages show close taxonomic correspondence over wide geographical ranges. Presently available if meager evidence suggests that this is also the case for Early Cretaceous communities. Cretaceous dinosaurian assemblages of Campanian and Maastrichtian age show considerable geographical differentiation but also some wide-ranging genera. Northern Hemisphere terrestrial ecosystems were dominated by hadrosaurs and ceratopsians, both herbivores with advanced capabilities for oral food-processing, whereas Southern Hemisphere biota were characterized by the abundance of titanosaurid sauropods, which relied on gut processing. Very close taxonomic similarities exist between the Campanian and early Maastrichtian dinosaurian assemblages of Mongolia and western North America, which, in part, is matched by similarities among other tetrapods such as mammals. Endemic dinosaurs in the Southern Hemisphere appear to reflect major changes in continental configuration. Some evidence exists for interchange of fuanal elements between North and South America. In absence of late Maastrichtian dinosaurian assemblages from most regions, scenarios concerning the terminal Cretaceous extinction of the Dinosauria should be regarded with caution because they are exclusively based on the conditions in western North America.

  14. Career of the Month: An interview with Dinosaur Paleontologist Matthew Carrano

    NSDL National Science Digital Library

    Megan Sullivan

    2006-11-01

    In the hunt for dinosaurs, only a small number of species have been unearthed. Many answers remain buried, awaiting discovery, which is why dinosaur paleontology today is such a thriving field. Dinosaur paleontologist Matthew Carrano not only works with real dinosaur bones every day, but he contributes to the centuries-old process of furthering scientific understanding. To Carrano, it's always exciting to uncover a new dinosaur fossil and be the first person in the history of the universe to see and touch it.

  15. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion II

    NASA Astrophysics Data System (ADS)

    Lee, Scott

    2015-03-01

    In the second paper1 of this series, the effect of transverse femoral stresses due to locomotion in theropod dinosaurs of different sizes was examined for the case of an unchanging leg geometry. Students are invariably thrilled to learn about theropod dinosaurs, and this activity applies the concepts of torque and stress to the issue of theropod locomotion. In this paper, our model calculation of Ref. 1 is extended to incorporate the fact that larger animals run with straighter legs. As in Ref. 1, students use geometric data for the femora of theropod dinosaurs to analyze their locomotion abilities. This can either be an in-class activity or given as a homework problem. Larger theropods are found to be less athletic in their movements than smaller theropods since the stresses in the femora of large theropods are closer to breaking their legs than smaller theropods.

  16. Elementary School Educator's Guide to the Dinosaur Halls

    NSDL National Science Digital Library

    The Museum's two Dinosaur Halls follow the evolutionary development of two distinct groups of dinosaurs, the Sauriscans and Ornithischians. This comprehensive guide to the halls' resources is designed to help you maximize your trip to the Museum. It includes detailed background information about the Museum's collection, a map of the Dinosaur Halls that shows the location of the exhibits and specimens that are highlighted on the elementary school tour and several pre-, during-, and post-visit activities to do with your students. There is a listing of related Museum exhibits and suggestions for how to tie them into your field trip and notes about how the topics featured in the halls address performance standards and curriculum requirements.

  17. Epidermal and dermal integumentary structures of ankylosaurian dinosaurs.

    PubMed

    Arbour, Victoria M; Burns, Michael E; Bell, Phil R; Currie, Philip J

    2014-01-01

    Ankylosaurian dinosaurs are most notable for their abundant and morphologically diverse osteoderms, which would have given them a spiky appearance in life. Isolated osteoderms are relatively common and provide important information about the structure of the ankylosaur dermis, but fossilized impressions of the soft-tissue epidermis of ankylosaurs are rare. Nevertheless, well-preserved integument exists on several ankylosaur fossils that shows osteoderms were covered by a single epidermal scale, but one or many millimeter-sized ossicles may be present under polygonal, basement epidermal scales. Evidence for the taxonomic utility of ankylosaurid epidermal scale architecture is presented for the first time. This study builds on previous osteological work that argues for a greater diversity of ankylosaurids in the Dinosaur Park Formation of Alberta than has been traditionally recognized and adds to the hypothesis that epidermal skin impressions are taxonomically relevant across diverse dinosaur clades. PMID:24105904

  18. Histone deacetylases and cardiovascular cell lineage commitment.

    PubMed

    Yang, Jun-Yao; Wang, Qian; Wang, Wen; Zeng, Ling-Fang

    2015-06-26

    Cardiovascular diseases (CVDs), which include all diseases of the heart and circulation system, are the leading cause of deaths on the globally. During the development of CVDs, choric inflammatory, lipid metabolism disorder and endothelial dysfunction are widely recognized risk factors. Recently, the new treatment for CVDs that designed to regenerate the damaged myocardium and injured vascular endothelium and improve recovery by the use of stem cells, attracts more and more public attention. Histone deacetylases (HDACs) are a family of enzymes that remove acetyl groups from lysine residues of histone proteins allowing the histones to wrap the DNA more tightly and commonly known as epigenetic regulators of gene transcription. HDACs play indispensable roles in nearly all biological processes, such as transcriptional regulation, cell cycle progression and developmental events, and have originally shown to be involved in cancer and neurological diseases. HDACs are also found to play crucial roles in cardiovascular diseases by modulating vascular cell homeostasis (e.g., proliferation, migration, and apoptosis of both ECs and SMCs). This review focuses on the roles of different members of HDACs and HDAC inhibitor on stem cell/ progenitor cell differentiation toward vascular cell lineages (endothelial cells, smooth muscle cells and Cardiomyocytes) and its potential therapeutics. PMID:26131315

  19. Histone deacetylases and cardiovascular cell lineage commitment

    PubMed Central

    Yang, Jun-Yao; Wang, Qian; Wang, Wen; Zeng, Ling-Fang

    2015-01-01

    Cardiovascular diseases (CVDs), which include all diseases of the heart and circulation system, are the leading cause of deaths on the globally. During the development of CVDs, choric inflammatory, lipid metabolism disorder and endothelial dysfunction are widely recognized risk factors. Recently, the new treatment for CVDs that designed to regenerate the damaged myocardium and injured vascular endothelium and improve recovery by the use of stem cells, attracts more and more public attention. Histone deacetylases (HDACs) are a family of enzymes that remove acetyl groups from lysine residues of histone proteins allowing the histones to wrap the DNA more tightly and commonly known as epigenetic regulators of gene transcription. HDACs play indispensable roles in nearly all biological processes, such as transcriptional regulation, cell cycle progression and developmental events, and have originally shown to be involved in cancer and neurological diseases. HDACs are also found to play crucial roles in cardiovascular diseases by modulating vascular cell homeostasis (e.g., proliferation, migration, and apoptosis of both ECs and SMCs). This review focuses on the roles of different members of HDACs and HDAC inhibitor on stem cell/ progenitor cell differentiation toward vascular cell lineages (endothelial cells, smooth muscle cells and Cardiomyocytes) and its potential therapeutics. PMID:26131315

  20. Pluripotency of spermatogonial stem cells from adult mouse testis

    Microsoft Academic Search

    Kaomei Guan; Karim Nayernia; Lars S. Maier; Stefan Wagner; Ralf Dressel; Jae Ho Lee; Jessica Nolte; Frieder Wolf; Manyu Li; Wolfgang Engel; Gerd Hasenfuss

    2006-01-01

    Embryonic germ cells as well as germline stem cells from neonatal mouse testis are pluripotent and have differentiation potential similar to embryonic stem cells, suggesting that the germline lineage may retain the ability to generate pluripotent cells. However, until now there has been no evidence for the pluripotency and plasticity of adult spermatogonial stem cells (SSCs), which are responsible for

  1. Stem cells in reproductive strategy of asexually reproducing invertebrates

    Microsoft Academic Search

    V. V. Isaeva; A. I. Shukalyuk; A. V. Akhmadieva

    2008-01-01

    Original and literature data supporting the evolutionary conservation of the morphofunctional organization of totipotent cells\\u000a of germ and stem lineages in metazoan animals are reviewed. We studied stem cells of the colonial rhizocephalans, Peltogasterella gracilis, Polyascus polygenea and Thylacoplethus isaevae, the turbellarian Dugesia tigrina, the colonial hydroid Obelia longissima, and cultured embryonic stem cells of mouse. The typical germinal granules

  2. Hematopoiesis from embryonic stem cells: Lessons from and for ontogeny

    Microsoft Academic Search

    Michael Kyba; George Q. Daley

    Cellular therapies derived from embryonic stem (ES) cells have acquired new interest and urgency with the demonstration that embryonic stem cells can be established from human blastocyst-stage embryos. Our ability to derive therapeutic cells from differentiating ES cell cultureswillultimatelydependonourunderstandingoftheembryonicdevelopmentalprocesses that direct the differentiation of pluripotent cells into transplantable lineage-specific stem cells, and on our ability to recapitulate these processes in

  3. Adult neural stem cells: plasticity and developmental potential

    Microsoft Academic Search

    Angela Gritti; Angelo L Vescovi; Rossella Galli

    2002-01-01

    Stem cells play an essential role during the processes of embryonic tissue formation and development and in the maintenance of tissue integrity and renewal throughout adulthood. The differentiation potential of stem cells in adult tissues has been thought to be limited to cell lineages present in the organ from which they derive, but there is evidence that somatic stem cells

  4. Biomimetic interfacial interpenetrating polymer networks control neural stem cell behavior

    E-print Network

    Saha, Krishanu

    Biomimetic interfacial interpenetrating polymer networks control neural stem cell behavior Krishanu.interscience.wiley.com). DOI: 10.1002/jbm.a.30986 Abstract: Highly-regulated signals surrounding stem cells, such as growth stem cell proliferation and maturation. However, tight con- trol of proliferation and lineage

  5. Microfluidic Perfusion for Regulating Diffusible Signaling in Stem Cells

    E-print Network

    Voldman, Joel

    Microfluidic Perfusion for Regulating Diffusible Signaling in Stem Cells Katarina Blagovic1 , Lily and in vitro, and are particularly important in embryonic stem cell (ESC) pluripotency and lineage commitment, Voldman J (2011) Microfluidic Perfusion for Regulating Diffusible Signaling in Stem Cells. PLoS ONE 6

  6. Sauropod dinosaurs evolved moderately sized genomes unrelated to body size

    PubMed Central

    Organ, Chris L.; Brusatte, Stephen L.; Stein, Koen

    2009-01-01

    Sauropodomorph dinosaurs include the largest land animals to have ever lived, some reaching up to 10 times the mass of an African elephant. Despite their status defining the upper range for body size in land animals, it remains unknown whether sauropodomorphs evolved larger-sized genomes than non-avian theropods, their sister taxon, or whether a relationship exists between genome size and body size in dinosaurs, two questions critical for understanding broad patterns of genome evolution in dinosaurs. Here we report inferences of genome size for 10 sauropodomorph taxa. The estimates are derived from a Bayesian phylogenetic generalized least squares approach that generates posterior distributions of regression models relating genome size to osteocyte lacunae volume in extant tetrapods. We estimate that the average genome size of sauropodomorphs was 2.02 pg (range of species means: 1.77–2.21 pg), a value in the upper range of extant birds (mean = 1.42 pg, range: 0.97–2.16 pg) and near the average for extant non-avian reptiles (mean = 2.24 pg, range: 1.05–5.44 pg). The results suggest that the variation in size and architecture of genomes in extinct dinosaurs was lower than the variation found in mammals. A substantial difference in genome size separates the two major clades within dinosaurs, Ornithischia (large genomes) and Saurischia (moderate to small genomes). We find no relationship between body size and estimated genome size in extinct dinosaurs, which suggests that neutral forces did not dominate the evolution of genome size in this group. PMID:19793755

  7. Scaling in Theropod Dinosaurs: Femoral Bone Strength and Locomotion

    NASA Astrophysics Data System (ADS)

    Lee, Scott

    2015-02-01

    In our first article1 on scaling in theropod dinosaurs, the longitudinal stress in the leg bones due to supporting the weight of the animal was studied and found not to control the dimensions of the femur. As a continuation of our study of elasticity in dinosaur bones, we now examine the transverse stress in the femur due to locomotion and find that this effect is important for the geometry of the bone. We find that larger theropods (including Tyrannosaurus rex) were less athletic than smaller theropods.

  8. Ancient wolf lineages in India.

    PubMed Central

    Sharma, Dinesh K; Maldonado, Jesus E; Jhala, Yadrendradev V; Fleischer, Robert C

    2004-01-01

    All previously obtained wolf (Canis lupus) and dog (Canis familiaris) mitochondrial (mt) DNA sequences fall within an intertwined and shallow clade (the 'wolf-dog' clade). We sequenced mtDNA of recent and historical samples from 45 wolves from throughout lowland peninsular India and 23 wolves from the Himalayas and Tibetan Plateau and compared these sequences with all available wolf and dog sequences. All 45 lowland Indian wolves have one of four closely related haplotypes that form a well-supported, divergent sister lineage to the wolf-dog clade. This unique lineage may have been independent for more than 400,000 years. Although seven Himalayan wolves from western and central Kashmir fall within the widespread wolf-dog clade, one from Ladakh in eastern Kashmir, nine from Himachal Pradesh, four from Nepal and two from Tibet form a very different basal clade. This lineage contains five related haplotypes that probably diverged from other canids more than 800,000 years ago, but we find no evidence of current barriers to admixture. Thus, the Indian subcontinent has three divergent, ancient and apparently parapatric mtDNA lineages within the morphologically delineated wolf. No haplotypes of either novel lineage are found within a sample of 37 Indian (or other) dogs. Thus, we find no evidence that these two taxa played a part in the domestication of canids. PMID:15101402

  9. Therapeutic Potential of Stem Cells in Diabetes

    Microsoft Academic Search

    E. Roche; R. Enseńat-Waser; J. A. Reig; J. Jones; T. León-Quinto; B. Soria

    Stem cells possess the ability to self-renew by symmetric divisions and, under certain circumstances, differentiate to a committed\\u000a lineage by asymmetric cell divisions. Depending on the origin, stem cells are classified as either embryonic or adult. Embryonic\\u000a stem cells are obtained from the inner cell mass of the blastocyst, a structure that appears during embryonic development\\u000a at day 6 in

  10. Transdifferentiation of Stem Cells: A Critical View

    Microsoft Academic Search

    Ina Gruh; Ulrich Martin

    2009-01-01

    \\u000a Recently a large amount of new data on the plasticity of stem cells of various lineages have emerged, providing new perspectives\\u000a especially for the therapeutic application of adult stem cells. Previously unknown possibilities of cell differentiation beyond\\u000a the known commitment of a given stem cell have been described using keywords such as “blood to liver,” or “bone to brain.”\\u000a Controversies

  11. Structural Extremes in a Cretaceous Dinosaur

    PubMed Central

    Sereno, Paul C.; Wilson, Jeffrey A.; Witmer, Lawrence M.; Whitlock, John A.; Maga, Abdoulaye; Ide, Oumarou; Rowe, Timothy A.

    2007-01-01

    Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic. PMID:18030355

  12. No evidence for directional evolution of body mass in herbivorous theropod dinosaurs

    PubMed Central

    Zanno, Lindsay E.; Makovicky, Peter J.

    2013-01-01

    The correlation between large body size and digestive efficiency has been hypothesized to have driven trends of increasing mass in herbivorous clades by means of directional selection. Yet, to date, few studies have investigated this relationship from a phylogenetic perspective, and none, to our knowledge, with regard to trophic shifts. Here, we reconstruct body mass in the three major subclades of non-avian theropod dinosaurs whose ecomorphology is correlated with extrinsic evidence of at least facultative herbivory in the fossil record—all of which also achieve relative gigantism (more than 3000 kg). Ordinary least-squares regressions on natural log-transformed mean mass recover significant correlations between increasing mass and geological time. However, tests for directional evolution in body mass find no support for a phylogenetic trend, instead favouring passive models of trait evolution. Cross-correlation of sympatric taxa from five localities in Asia reveals that environmental influences such as differential habitat sampling and/or taphonomic filtering affect the preserved record of dinosaurian body mass in the Cretaceous. Our results are congruent with studies documenting that behavioural and/or ecological factors may mitigate the benefit of increasing mass in extant taxa, and suggest that the hypothesis can be extrapolated to herbivorous lineages across geological time scales. PMID:23193135

  13. What drove reversions to quadrupedality in ornithischian dinosaurs? Testing hypotheses using centre of mass modelling.

    PubMed

    Maidment, Susannah C R; Henderson, Donald M; Barrett, Paul M

    2014-11-01

    The exceptionally rare transition to quadrupedalism from bipedal ancestors occurred on three independent occasions in ornithischian dinosaurs. The possible driving forces behind these transitions remain elusive, but several hypotheses-including the development of dermal armour and the expansion of head size and cranial ornamentation-have been proposed to account for this major shift in stance. We modelled the position of the centre of mass (CoM) in several exemplar ornithischian taxa and demonstrate that the anterior shifts in CoM position associated with the development of an enlarged skull ornamented with horns and frills for display/defence may have been one of the drivers promoting ceratopsian quadrupedality. A posterior shift in CoM position coincident with the development of extensive dermal armour in thyreophorans demonstrates this cannot have been a primary causative mechanism for quadrupedality in this clade. Quadrupedalism developed in response to different selective pressures in each ornithischian lineage, indicating different evolutionary pathways to convergent quadrupedal morphology. PMID:25228349

  14. Bird-like anatomy, posture, and behavior revealed by an early jurassic theropod dinosaur resting trace

    USGS Publications Warehouse

    Milner, A.R.C.; Harris, J.D.; Lockley, M.G.; Kirkland, J.I.; Matthews, N.A.

    2009-01-01

    Background: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings: Here we describe a well-preserved theropod trackway in a Lower Jurassic (???198 millionyear- old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods.

  15. Stem cell factor is a chemoattractant and a survival factor for CNS stem cells

    Microsoft Academic Search

    Anna Erlandsson; Jimmy Larsson; Karin Forsberg-Nilsson

    2004-01-01

    Migration of neural cells to their final positions is crucial for the correct formation of the central nervous system. Several extrinsic factors are known to be involved in the regulation of neural migration. We asked if stem cell factor (SCF), well known as a chemoattractant and survival factor in the hematopoietic lineage, could elicit similar responses in neural stem cells.

  16. HEAD-BITING BEHAVIOR IN THEROPOD DINOSAURS: PALEOPATHOLOGICAL EVIDENCE

    Microsoft Academic Search

    Darren H. TANKE; Philip J. CURRIE

    Cranial material of Sinraptor dongi (Upper Jurassic, Xinjiang, China), Gorgosau- rus libratus, Daspletosaurus torosus (Upper Cretaceous, Alberta, Canada), and other large theropod dinosaurs exhibit similar paleopathological anomalies indicative of aggressive in- tra- or interspecific biting. Tooth strike trauma includes osseous lesions caused by solitary or multiple tooth punctures, or by dragging or gouging the tooth tips across the surfaces of

  17. Science Sampler: Metric-asaurus--Conceptualizing scale using dinosaur models

    NSDL National Science Digital Library

    Lisa Gloyna

    2010-11-01

    For middle school students who have seen only pictures of dinosaurs in books, in the movies, or on the internet, trying to comprehend the size of these gargantuan animals can be difficult. This lesson provides a way for students to visualize changing scal

  18. Dinosaur eggs and nesting behaviors: A paleobiological investigation

    Microsoft Academic Search

    Gerald Grellet-Tinner; Luis Chiappe; Mark Norell; David Bottjer

    2006-01-01

    Although dinosaur eggs were first discovered and identified in the late 1800s, limited attention was given to the scientific value of oological fossils in contrast to observations based on skeletal features. Here, we offer a review of Mesozoic saurischian egg materials, in comparison with extant crocodilians and avians, and their paleobiological interpretation based either on the presence of embryos in

  19. Functional morphology of spinosaur ‘crocodile-mimic’ dinosaurs

    Microsoft Academic Search

    Emily J. Rayfield; Angela C. Milner; Viet Bui Xuan; Philippe G. Young

    2007-01-01

    Spinosaurid theropod dinosaurs appear to represent convergent morphological evolution toward a croc-odylian-like cranial morphology, previously linked to the possibility that spinosaurs adopted a similar, partially piscivorous, trophic niche. Further conclusions are hindered by a lack of quantitative evidence, and an incomplete understanding of the functional significance of key crocodylian cranial characters. A comparative biomechanical analysis of function in the snout

  20. Ornithopod dinosaur tracks from the Lower Jurassic of Queensland

    Microsoft Academic Search

    Richard A. Thulborn

    1994-01-01

    Natural casts of seven small footprints have been identified on a single weathered block derived from the Precipice Sandstone (Lower Jurassic) of the Carnarvon Gorge, southeastern Queensland. The footprints are attributed to ornithopod dinosaurs and are referred to the ichnogenus Anomoepus. They appear to be most similar to the ichnospecies Anomoepus gracillimus, originally defined on footprints from the Lower Jurassic

  1. A revised taxonomy of the iguanodont dinosaur genera and species

    Microsoft Academic Search

    Gregory S. Paul

    2008-01-01

    Criteria for designating dinosaur genera are inconsistent; some very similar species are highly split at the generic level, other anatomically disparate species are united at the same rank. Since the mid-1800s the classic genus Iguanodon has become a taxonomic grab-bag containing species spanning most of the Early Cretaceous of the northern hemisphere. Recently the genus was radically redesignated when the

  2. Dinosaur remains from the type Maastrichtian: an update

    Microsoft Academic Search

    David B. Weishampel; Eric W. A. Mulder; Rudi W. Dortangs; John W. M. Jagt; Coralia-Maria Jianu; Marcel M. M. Kuypers; Hans H. G. Peeters; Anne S. Schulp

    1999-01-01

    Isolated cranial and post-cranial remains of hadrosaurid dinosaurs have been collected from various outcrops in the type area of the Maastrichtian stage during the last few years. In the present contribution, dentary and maxillary teeth are recorded from the area for the first time. Post-cranial elements comprise a newly collected, fragmentary, large right metatarsal III and a broken ?right humerus,

  3. Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation

    Microsoft Academic Search

    Paul C. Sereno; Didier B. Dutheil; M. Larochene; Hans C. E. Larsson; Gabrielle H. Lyon; Paul M. Magwene; Christian A. Sidor; David J. Varricchio; Jeffrey A. Wilson

    1996-01-01

    Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely

  4. Testing the Dinosaur Hypothesis under different GP algorithms

    Microsoft Academic Search

    Michael Kampouridis; Shu-Heng Chen; Edward Tsang

    2010-01-01

    The Dinosaur Hypothesis states that the behaviour of a market never settles down and that the population of predictors continually co-evolves with this market. This observation had been made and tested under artificial datasets. Recently, we formalized this hypothesis and also tested it under 10 empirical datasets. The tests were based on a GP system. However, it could be argued

  5. Metric-Asaurus: Conceptualizing Scale Using Dinosaur Models

    ERIC Educational Resources Information Center

    Gloyna, Lisa; West, Sandra; Martin, Patti; Browning, Sandra

    2010-01-01

    For middle school students who have seen only pictures of dinosaurs in books, in the movies, or on the internet, trying to comprehend the size of these gargantuan animals can be difficult. This lesson provides a way for students to visualize changing scale through studying extinct organisms and to gain a deeper understanding of the history of the…

  6. New dinosaurs link southern landmasses in the Mid-Cretaceous

    Microsoft Academic Search

    Paul C. Sereno; Jeffrey A. Wilson; Jack L. Conrad

    2004-01-01

    Abelisauroid predators have been recorded almost exclusively from South America, India and Madagascar, a distribution thought to document persistent land connections exclusive of Africa. Here, we report fossils from three stratigraphic levels in the Cretaceous of Niger that provide definitive evidence that abelisauroid dinosaurs and their immediate antecedents were also present on Africa. The fossils include an immediate abelisauroid antecedent

  7. Growing up with dinosaurs: molecular dates and the mammalian radiation

    Microsoft Academic Search

    Lindell Bromham; Matthew J. Phillips; David Penny

    1999-01-01

    Dates of divergence derived from molecular data have been used to place the beginning of the radiation of modern mammalian orders in the Cretaceous, long before the final extinction of the dinosaurs. These molecular dates have been used to challenge the idea that the ordinal diversification of mammals was triggered by the availability of ‘empty niches’ left vacant by the

  8. Confetti clarifies controversy: neural crest stem cells are multipotent.

    PubMed

    Bronner, Marianne

    2015-03-01

    Neural crest precursors generate diverse cell lineages during development, which have been proposed to arise either from multipotent precursor cells or pools of heterogeneous, restricted progenitors. Now in Cell Stem Cell, Baggiolini et al. (2015) perform rigorous in vivo lineage tracing to show that individual neural crest precursors are multipotent. PMID:25748927

  9. Use of Embryonic Stem Cells for Endocrine Disorders

    Microsoft Academic Search

    Alan Trounson

    2007-01-01

    Embryonic stem cells (ESCs) can be derived from unused cultured human embryos, provided by patients undergoing treatment for infertility, that would otherwise be disposed of. The inner cell mass cells form immortal pluripotent cell colonies that may be directed into a wide range of cell lineages and end-differentiated cell types. Endocrine lineages are now being actively explored, particularly for their

  10. Evolution of Developmental Control Mechanisms Grandparental stem cells in leech segmentation: Differences in CDC42 expression are

    E-print Network

    Weisblat, David A.

    Evolution of Developmental Control Mechanisms Grandparental stem cells in leech segmentation Keywords: Segmentation cdc42 Cell polarity Leech Asymmetric cell division Grandparental stem cell Embryonic segmentation in clitellate annelids (oligochaetes and leeches) is a cell lineage-driven process. Embryos

  11. CRETACEOUS CLIMATE SENSITIVITY STUDY USING DINOSAUR & PLANT PALEOBIOGEOGRAPHY

    NASA Astrophysics Data System (ADS)

    Goswami, A.; Main, D. J.; Noto, C. R.; Moore, T. L.; Scotese, C.

    2009-12-01

    The Early Cretaceous was characterized by cool poles and moderate global temperatures (~16° C). During the mid and late Cretaceous, long-term global warming (~20° - 22° C) was driven by increasing levels of CO2, rising sea level (lowering albedo) and the continuing breakup of Pangea. Paleoclimatic reconstructions for four time intervals during the Cretaceous: Middle Campanian (80 Ma), Cenomanian/Turonian (90 Ma), Early Albian (110 Ma) and Barremian-Hauterivian (130Ma) are presented here. These paleoclimate simulations were prepared using the Fast Ocean and Atmosphere Model (FOAM). The simulated results show the pattern of the pole-to-Equator temperature gradients, rainfall, surface run-off, the location of major rivers and deltas. In order to investigate the effect of potential dispersal routes on paleobiogeographic patterns, a time-slice series of maps from Early - Late Cretaceous were produced showing plots of dinosaur and plant fossil distributions. These Maps were created utilizing: 1) plant fossil localities from the GEON and Paleobiology (PBDB) databases; and 2) dinosaur fossil localities from an updated version of the Dinosauria (Weishampel, 2004) database. These results are compared to two different types of datasets, 1) Paleotemperature database for the Cretaceous and 2) locality data obtained from GEON, PBDB and Dinosauria database. Global latitudinal mean temperatures from both the model and the paelotemperature database were plotted on a series of latitudinal graphs along with the distributions of fossil plants and dinosaurs. It was found that most dinosaur localities through the Cretaceous tend to cluster within specific climate belts, or envelopes. Also, these Cretaceous maps show variance in biogeographic zonation of both plants and dinosaurs that is commensurate with reconstructed climate patterns and geography. These data are particularly useful for understanding the response of late Mesozoic ecosystems to geographic and climatic conditions that differed markedly from the present. Studies of past biotas and their changes may elucidate the role of climatic and geographic factors in driving changes in species distributions, ecosystem organization, and evolutionary dynamics over time.

  12. Mesenchymal Progenitors and the Osteoblast Lineage in Bone Marrow Hematopoietic Niches

    PubMed Central

    Panaroni, Cristina; Tzeng, Yi-shiuan; Saeed, Hamid; Wu, Joy Y.

    2014-01-01

    The bone marrow cavity is essential for the proper development of the hematopoietic system. In the last few decades it has become clear that mesenchymal stem/progenitor cells as well as cells of the osteoblast lineage, besides maintaining bone homeostasis, are also fundamental regulators of bone marrow hematopoiesis. Several studies have demonstrated the direct involvement of mesenchymal and osteoblast lineage cells in the maintenance and regulation of supportive microenvironments necessary for quiescence, self-renewal and differentiation of hematopoietic stem cells. In addition, specific niches have also been identified within the bone marrow for maturing hematopoietic cells. Here we will review recent findings that have highlighted the roles of mesenchymal progenitors and cells of the osteoblast lineage in regulating distinct stages of hematopoiesis. PMID:24477415

  13. Squamosal ontogeny and variation in the pachycephalosaurian dinosaur Stegoceras validum Lambe, 1902, from the Dinosaur Park Formation, Alberta

    Microsoft Academic Search

    Ryan K. Schott; David C. Evans

    2012-01-01

    The pachycephalosaurian squamosal is one of the most diagnostic bones in this enigmatic group of dinosaurs, but little is known about variation in its morphology. Despite this, features of squamosal morphology are often used in diagnoses and phylogenetic studies. The recently proposed hypothesis of an ontogenetic transition from Dracorex to Pachycephalosaurus implies a large amount of ontogenetic variation in squamosal

  14. Identifying neuronal lineages of Drosophila by sequence analysis of axon tracts.

    PubMed

    Cardona, Albert; Saalfeld, Stephan; Arganda, Ignacio; Pereanu, Wayne; Schindelin, Johannes; Hartenstein, Volker

    2010-06-01

    The Drosophila brain is formed by an invariant set of lineages, each of which is derived from a unique neural stem cell (neuroblast) and forms a genetic and structural unit of the brain. The task of reconstructing brain circuitry at the level of individual neurons can be made significantly easier by assigning neurons to their respective lineages. In this article we address the automation of neuron and lineage identification. We focused on the Drosophila brain lineages at the larval stage when they form easily recognizable secondary axon tracts (SATs) that were previously partially characterized. We now generated an annotated digital database containing all lineage tracts reconstructed from five registered wild-type brains, at higher resolution and including some that were previously not characterized. We developed a method for SAT structural comparisons based on a dynamic programming approach akin to nucleotide sequence alignment and a machine learning classifier trained on the annotated database of reference SATs. We quantified the stereotypy of SATs by measuring the residual variability of aligned wild-type SATs. Next, we used our method for the identification of SATs within wild-type larval brains, and found it highly accurate (93-99%). The method proved highly robust for the identification of lineages in mutant brains and in brains that differed in developmental time or labeling. We describe for the first time an algorithm that quantifies neuronal projection stereotypy in the Drosophila brain and use the algorithm for automatic neuron and lineage recognition. PMID:20519528

  15. Pathologic bone tissues in a Turkey vulture and a nonavian dinosaur: implications for interpreting endosteal bone and radial fibrolamellar bone in fossil dinosaurs.

    PubMed

    Chinsamy, Anusuya; Tumarkin-Deratzian, Allison

    2009-09-01

    We report on similar pathological bone microstructure in an extant turkey vulture (Cathartes aura) and a nonavian dinosaur from Transylvania. Both these individuals exhibit distinctive periosteal reactive bone deposition accompanied by endosteal bone deposits in the medullary cavity. Our findings have direct implications on the two novel bone tissues recently described among nonavian dinosaurs, radial fibrolamellar bone tissue and medullary bone tissue. On the basis of the observed morphology of the periosteal reactive bone in the turkey vulture and the Transylvanian dinosaur, we propose that the radial fibrolamellar bone tissues observed in mature dinosaurs may have had a pathological origin. Our analysis also shows that on the basis of origin, location, and morphology, pathologically derived endosteal bone tissue can be similar to medullary bone tissues described in nonavian dinosaurs. As such, we caution the interpretation of all endosteally derived bone tissue as homologous to avian medullary bone. PMID:19711479

  16. The molecular repertoire of the 'almighty' stem cell

    Microsoft Academic Search

    Craig E. Eckfeldt; Eric M. Mendenhall; Catherine M. Verfaillie

    2005-01-01

    Stem cells share the defining characteristics of self-renewal, which maintains or expands the stem-cell pool, and multi-lineage differentiation, which generates and regenerates tissues. Stem-cell self-renewal and differentiation are influenced by the convergence of intrinsic cellular signals and extrinsic microenvironmental cues from the surrounding stem-cell niche, but the specific signals involved are poorly understood. Recently, several studies have sought to identify

  17. Energy metabolism plasticity enables stemness programs.

    PubMed

    Folmes, Clifford D L; Nelson, Timothy J; Dzeja, Petras P; Terzic, Andre

    2012-04-01

    Engineering pluripotency through nuclear reprogramming and directing stem cells into defined lineages underscores cell fate plasticity. Acquisition of and departure from stemness are governed by genetic and epigenetic controllers, with modulation of energy metabolism and associated signaling increasingly implicated in cell identity determination. Transition from oxidative metabolism, typical of somatic tissues, into glycolysis is a prerequisite to fuel-proficient reprogramming, directing a differentiated cytotype back to the pluripotent state. The glycolytic metabotype supports the anabolic and catabolic requirements of pluripotent cell homeostasis. Conversely, redirection of pluripotency into defined lineages requires mitochondrial biogenesis and maturation of efficient oxidative energy generation and distribution networks to match demands. The vital function of bioenergetics in regulating stemness and lineage specification implicates a broader role for metabolic reprogramming in cell fate decisions and determinations of tissue regenerative potential. PMID:22548573

  18. Bioprinting for stem cell research

    PubMed Central

    Tasoglu, Savas; Demirci, Utkan

    2012-01-01

    Recently, there has been a growing interest to apply bioprinting techniques to stem cell research. Several bioprinting methods have been developed utilizing acoustics, piezoelectricity, and lasers to deposit living cells onto receiving substrates. Using these technologies, spatially defined gradients of immobilized proteins can be engineered to direct stem cell differentiation into multiple subpopulations of different lineages. Stem cells can also be patterned in a high-throughput manner onto flexible implementation patches for tissue regeneration or onto substrates with the goal of accessing encapsulated stem cell of interest for genomic analysis. Here, we review recent achievements with bioprinting technologies in stem cell research, and identify future challenges and potential applications including tissue engineering and regenerative medicine, wound healing, and genomics. PMID:23260439

  19. A bizarre predatory dinosaur from the Late Cretaceous of Madagascar.

    PubMed

    Sampson, S D; Carrano, M T; Forster, C A

    2001-01-25

    Here we report the discovery of a small-bodied (approximately 1.8 m) predatory dinosaur from the Late Cretaceous (Maastrichtian) of Madagascar. Masiakasaurus knopfleri, gen. et sp. nov., represented by several skull elements and much of the postcranial skeleton, is unique in being the only known theropod with a highly procumbent and distinctly heterodont lower dentition. Such a derived dental morphology is otherwise unknown among dinosaurs. Numerous skeletal characteristics indicate that Masiakasaurus is a member of Abelisauroidea, an enigmatic clade of Gondwanan theropods. Previously, small-bodied abelisauroids were known only from Argentina. The occurrence of Masiakasaurus on Madagascar suggests that small-bodied abelisauroids, like their larger-bodied counterparts, were more cosmopolitan, radiating throughout much of Gondwana and paralleling the diversification of small coelurosaur theropods in Laurasia. PMID:11206544

  20. An Abelisauroid Theropod Dinosaur from the Turonian of Madagascar

    PubMed Central

    Farke, Andrew A.; Sertich, Joseph J. W.

    2013-01-01

    Geophysical evidence strongly supports the complete isolation of India and Madagascar (Indo-Madagascar) by ?100 million years ago, though sparse terrestrial fossil records from these regions prior to ?70 million years ago have limited insights into their biogeographic history during the Cretaceous. A new theropod dinosaur, Dahalokely tokana, from Turonian-aged (?90 million years old) strata of northernmost Madagascar is represented by a partial axial column. Autapomorphies include a prominently convex prezygoepipophyseal lamina on cervical vertebrae and a divided infraprezygapophyseal fossa through the mid-dorsal region, among others. Phylogenetic analysis definitively recovers the species as an abelisauroid theropod and weakly as a noasaurid. Dahalokely is the only known dinosaur from the interval during which Indo-Madagascar likely existed as a distinct landmass, but more complete material is needed to evaluate whether or not it is more closely related to later abelisauroids of Indo-Madagascar or those known elsewhere in Gondwana. PMID:23637961