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1

Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic.  

PubMed

The ascent of dinosaurs in the Triassic is an exemplary evolutionary radiation, but the earliest phase of dinosaur history remains poorly understood. Body fossils of close dinosaur relatives are rare, but indicate that the dinosaur stem lineage (Dinosauromorpha) originated by the latest Anisian (ca 242-244 Ma). Here, we report footprints from the Early-Middle Triassic of Poland, stratigraphically well constrained and identified using a conservative synapomorphy-based approach, which shifts the origin of the dinosaur stem lineage back to the Early Olenekian (ca 249-251 Ma), approximately 5-9 Myr earlier than indicated by body fossils, earlier than demonstrated by previous footprint records, and just a few million years after the Permian/Triassic mass extinction (252.3 Ma). Dinosauromorph tracks are rare in all Polish assemblages, suggesting that these animals were minor faunal components. The oldest tracks are quadrupedal, a morphology uncommon among the earliest dinosauromorph body fossils, but bipedality and moderately large body size had arisen by the Early Anisian (ca 246 Ma). Integrating trace fossils and body fossils demonstrates that the rise of dinosaurs was a drawn-out affair, perhaps initiated during recovery from the Permo-Triassic extinction. PMID:20926435

Brusatte, Stephen L; Nied?wiedzki, Grzegorz; Butler, Richard J

2011-04-01

2

Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic  

PubMed Central

The ascent of dinosaurs in the Triassic is an exemplary evolutionary radiation, but the earliest phase of dinosaur history remains poorly understood. Body fossils of close dinosaur relatives are rare, but indicate that the dinosaur stem lineage (Dinosauromorpha) originated by the latest Anisian (ca 242–244 Ma). Here, we report footprints from the Early–Middle Triassic of Poland, stratigraphically well constrained and identified using a conservative synapomorphy-based approach, which shifts the origin of the dinosaur stem lineage back to the Early Olenekian (ca 249–251 Ma), approximately 5–9 Myr earlier than indicated by body fossils, earlier than demonstrated by previous footprint records, and just a few million years after the Permian/Triassic mass extinction (252.3 Ma). Dinosauromorph tracks are rare in all Polish assemblages, suggesting that these animals were minor faunal components. The oldest tracks are quadrupedal, a morphology uncommon among the earliest dinosauromorph body fossils, but bipedality and moderately large body size had arisen by the Early Anisian (ca 246 Ma). Integrating trace fossils and body fossils demonstrates that the rise of dinosaurs was a drawn-out affair, perhaps initiated during recovery from the Permo-Triassic extinction. PMID:20926435

Brusatte, Stephen L.; Nied?wiedzki, Grzegorz; Butler, Richard J.

2011-01-01

3

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

PubMed Central

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

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

2014-01-01

4

Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage.  

PubMed

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

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

2014-05-01

5

Matrix Elasticity Directs Stem Cell Lineage Specification  

Microsoft Academic Search

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

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

2006-01-01

6

Dinosaurs  

NSDL National Science Digital Library

This video segment from IdahoPTV's D4K shows us what paleontologists think dinosaurs looked like, what they ate, and why they might have disappeared. We see paleontologists at work studying dinosaurs fossils.

Idaho PTV

2011-09-21

7

Dinosaurs.  

ERIC Educational Resources Information Center

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…

Miller, Vicki; Happel, Sue

8

Dinosaurs  

NSDL National Science Digital Library

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 ...

Ms. Stearns

2008-10-26

9

Dinosaurs  

NSDL National Science Digital Library

On this site students will find three separate website, all with lots of information. Students will then be asked to answer the questions after reviewing the website. First is Dino Data, this website contains the names, classifications, and time line of all dinosaurs. Dino Data 1) What was the time line of dinosaurs, and why did they become extinct. 2) What was the most interesting Dino Data you found? The next website was chosen for it's wonderful description of dinosaur names. Dino Names: Why they are named and why 1) What ...

Mr. Morton

2010-09-27

10

Dinosaur  

NSDL National Science Digital Library

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.

D.M. Candelora

2007-12-12

11

Dinosaurs  

NSDL National Science Digital Library

This is a four day lesson plan that high school students grade 10-12 in the Child Care course can use to evaluate and then create their own lesson plan. This lesson plan also includes an example field trip. It can also be used for the high school students to experience teaching the preschool school children a unit on dinosaurs. At the end of reviewing this lesson plan students will be able to identify the components of this lesson plan and identify which DAP learning experience was used in each activity. After analyzing this lesson plan and identifying all the parts students will then be able to create their own lesson plan , picking a theme of their own. If used for students to teach the unit to preschoolers they will be able to present the lesson plan with all requirements met, and then better understand them to then create their own. Dinosaurs NOTE: For students who may have a disability preventing them from typing their lesson plan you could use the following assistive technology which allows them to speak into the computer and the computer types it up for them. A great source for this is: Dragon naturally speaking. Also you could ...

Mrs. Weaver

2009-11-02

12

Notch Promotes Neural Lineage Entry by Pluripotent Embryonic Stem Cells  

E-print Network

Notch Promotes Neural Lineage Entry by Pluripotent Embryonic Stem Cells Sally Lowell1* , Alexandra Benchoua1,2 , Barry Heavey1 , Austin G. Smith1,3* 1 Centre Development in Stem Cell Biology, Institute for Stem Cell Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom

Paris-Sud XI, Université de

13

Human Hepatic Stem Cell and Maturational Liver Lineage Biology  

PubMed Central

Livers are comprised of maturational lineages of cells beginning extrahepatically in the hepato-pancreatic common duct near the duodenum and intrahepatically in zone 1 by the portal triads. The extrahepatic stem cell niches are the peribiliary glands deep within the walls of the bile ducts; those intrahepatically are the canals of Hering in postnatal livers and that derive from ductal plates in fetal livers. Intrahepatically, there are at least 8 maturational lineage stages from the stem cells in zone 1 (periportal), through the midacinar region (zone 2), to the most mature cells and apoptotic cells found pericentrally in zone 3. Those found in the biliary tree are still being defined. Parenchymal cells are closely associated with lineages of mesenchymal cells, and their maturation is coordinated. Each lineage stage consists of parenchymal and mesenchymal cell partners distinguishable by their morphology, ploidy, antigens, biochemical traits, gene expression, and ability to divide. They are governed by changes in chromatin (e.g. methylation), gradients of paracrine signals (soluble factors and insoluble extracellular matrix components), mechanical forces, and feedback loop signals derived from late lineage cells. Feedback loop signals, secreted by late lineage stage cells into bile, flow back to the periportal area and regulate the stem cells and other early lineage stage cells, in mechanisms dictating the size of the liver mass. Recognition of maturational lineage biology and its regulation by these multiple mechanisms offers new understandings of liver biology, pathologies, and strategies for regenerative medicine. PMID:21374667

Turner, Rachael; Lozoya, Oswaldo; Wang, Yunfang; Cardinale, Vincenzo; Gaudio, Eugenio; Alpini, Gianfranco; Mendel, Gemma; Wauthier, Eliane; Barbier, Claire; Alvaro, Domenico; Reid, Lola M.

2011-01-01

14

SCLD: a stem cell lineage database for the annotation of cell types and developmental lineages  

PubMed Central

Stem cell biology has experienced explosive growth over the past decade as researchers attempt to generate therapeutically relevant cell types in the laboratory. Recapitulation of endogenous developmental trajectories is a dominant paradigm in the design of directed differentiation protocols, and attempts to guide stem cell differentiation are often based explicitly on knowledge of in vivo development. Therefore, when designing protocols, stem cell biologists rely heavily upon information including (i) cell type-specific gene expression profiles, (ii) anatomical and developmental relationships between cells and tissues and (iii) signals important for progression from progenitors to target cell types. Here, we present the Stem Cell Lineage Database (SCLD) (http://scld.mcb.uconn.edu) that aims to unify this information into a single resource where users can easily store and access information about cell type gene expression, cell lineage maps and stem cell differentiation protocols for both human and mouse stem cells and endogenous developmental lineages. By establishing the SCLD, we provide scientists with a centralized location to organize access and share data, dispute and resolve contentious relationships between cell types and within lineages, uncover discriminating cell type marker panels and design directed differentiation protocols. PMID:20972216

Hemphill, Edward E.; Dharia, Asav P.; Lee, Chih; Jakuba, Caroline M.; Gibson, Jason D.; Kolling, Frederick W.; Nelson, Craig E.

2011-01-01

15

Generation of enteroendocrine cell diversity in midgut stem cell lineages.  

PubMed

The endocrine system mediates long-range peptide hormone signaling to broadcast changes in metabolic status to distant target tissues via the circulatory system. In many animals, the diffuse endocrine system of the gut is the largest endocrine tissue, with the full spectrum of endocrine cell subtypes not yet fully characterized. Here, we combine molecular mapping, lineage tracing and genetic analysis in the adult fruit fly to gain new insight into the cellular and molecular mechanisms governing enteroendocrine cell diversity. Neuropeptide hormone distribution was used as a basis to generate a high-resolution cellular map of the diffuse endocrine system. Our studies show that cell diversity is seen at two distinct levels: regional and local. We find that class I and class II enteroendocrine cells can be distinguished locally by combinatorial expression of secreted neuropeptide hormones. Cell lineage tracing studies demonstrate that class I and class II cells arise from a common stem cell lineage and that peptide profiles are a stable feature of enteroendocrine cell identity during homeostasis and following challenge with the enteric pathogen Pseudomonas entomophila. Genetic analysis shows that Notch signaling controls the establishment of class II cells in the lineage, but is insufficient to reprogram extant class I cells into class II enteroendocrine cells. Thus, one mechanism by which secretory cell diversity is achieved in the diffuse endocrine system is through cell-cell signaling interactions within individual adult stem cell lineages. PMID:25670792

Beehler-Evans, Ryan; Micchelli, Craig A

2015-02-15

16

Troika of the mouse blastocyst: lineage segregation and stem cells.  

PubMed

The initial period of mammalian embryonic development is primarily devoted to cell commitment to the pluripotent lineage, as well as to the formation of extraembryonic tissues essential for embryo survival in utero. This phase of development is also characterized by extensive morphological transitions. Cells within the preimplantation embryo exhibit extraordinary cell plasticity and adaptation in response to experimental manipulation, highlighting the use of a regulative developmental strategy rather than a predetermined one resulting from the non-uniform distribution of maternal information in the cytoplasm. Consequently, early mammalian development represents a useful model to study how the three primary cell lineages; the epiblast, primitive endoderm (also referred to as the hypoblast) and trophoblast, emerge from a totipotent single cell, the zygote. In this review, we will discuss how the isolation and genetic manipulation of murine stem cells representing each of these three lineages has contributed to our understanding of the molecular basis of early developmental events. PMID:22023624

Artus, Jerome; Hadjantonakis, Anna-Katerina

2012-01-01

17

Troika of the Mouse Blastocyst: Lineage Segregation and Stem Cells  

PubMed Central

The initial period of mammalian embryonic development is primarily devoted to cell commitment to the pluri-potent lineage, as well as to the formation of extraembryonic tissues essential for embryo survival in utero. This phase of development is also characterized by extensive morphological transitions. Cells within the preimplantation embryo exhibit extraordinary cell plasticity and adaptation in response to experimental manipulation, highlighting the use of a regulative developmental strategy rather than a predetermined one resulting from the non-uniform distribution of maternal information in the cytoplasm. Consequently, early mammalian development represents a useful model to study how the three primary cell lineages; the epiblast, primitive endoderm (also referred to as the hypoblast) and trophoblast, emerge from a totipotent single cell, the zygote. In this review, we will discuss how the isolation and genetic manipulation of murine stem cells representing each of these three lineages has contributed to our understanding of the molecular basis of early developmental events. PMID:22023624

Artus, Jérôme; Hadjantonakis, Anna-Katerina

2012-01-01

18

Trophoblast lineage cells derived from human induced pluripotent stem cells  

SciTech Connect

Highlights: •Epithelial-like phenotype of trophoblast lineage cells derived from human iPS cells. •Trophoblast lineage cells derived from human iPS cells exhibit trophoblast function. •Trophoblasts from iPS cells provides a proof-of-concept in regenerative medicine. -- Abstract: Background: During implantation, the blastocyst trophectoderm attaches to the endometrial epithelium and continues to differentiate into all trophoblast subtypes, which are the major components of a placenta. Aberrant trophoblast proliferation and differentiation are associated with placental diseases. However, due to ethical and practical issues, there is almost no available cell or tissue source to study the molecular mechanism of human trophoblast differentiation, which further becomes a barrier to the study of the pathogenesis of trophoblast-associated diseases of pregnancy. In this study, our goal was to generate a proof-of-concept model for deriving trophoblast lineage cells from induced pluripotency stem (iPS) cells from human fibroblasts. In future studies the generation of trophoblast lineage cells from iPS cells established from patient’s placenta will be extremely useful for studying the pathogenesis of individual trophoblast-associated diseases and for drug testing. Methods and results: Combining iPS cell technology with BMP4 induction, we derived trophoblast lineage cells from human iPS cells. The gene expression profile of these trophoblast lineage cells was distinct from fibroblasts and iPS cells. These cells expressed markers of human trophoblasts. Furthermore, when these cells were differentiated they exhibited invasive capacity and placental hormone secretive capacity, suggesting extravillous trophoblasts and syncytiotrophoblasts. Conclusion: Trophoblast lineage cells can be successfully derived from human iPS cells, which provide a proof-of-concept tool to recapitulate pathogenesis of patient placental trophoblasts in vitro.

Chen, Ying, E-mail: ying.chen@hc.msu.edu [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States)] [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States); Wang, Kai; Chandramouli, Gadisetti V.R. [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States)] [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States); Knott, Jason G. [Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University (United States)] [Developmental Epigenetics Laboratory, Department of Animal Science, Michigan State University (United States); Leach, Richard, E-mail: Richard.leach@hc.msu.edu [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States) [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, 333 Bostwick NE, Grand Rapids, MI 49503 (United States); Department of Obstetrics, Gynecology and Women’s Health, Spectrum Health Medical Group (United States)

2013-07-12

19

Mechanically induced osteogenic lineage commitment of stem cells  

PubMed Central

Bones adapt to accommodate the physical forces they experience through changes in architecture and mass. Stem cells differentiate into bone-forming osteoblasts, and mechanical stimulation is involved in this process. Various studies have applied controlled mechanical stimulation to stem cells and investigated the effects on osteogenic lineage commitment. These studies demonstrate that physical stimuli can induce osteogenic lineage commitment. Tension, fluid shear stress, substrate material properties, and cell shape are all factors that influence osteogenic differentiation. In particular, the level of tension is important. Also, rigid substrates with stiffness similar to collagenous bone induce osteogenic differentiation, while softer substrates induce other lineages. Finally, cells allowed to adhere over a larger area are able to differentiate towards the osteogenic lineage while cells adhering to a smaller area are restricted to the adipogenic lineage. Stem cells are able to sense their mechanical environments through various mechanosensors, including the cytoskeleton, focal adhesions, and primary cilia. The cytoskeleton provides a structural frame for the cell, and myosin interacts with actin to generate cytoskeletal tension, which is important for mechanically induced osteogenesis of stem cells. Adapter proteins link the cytoskeleton to integrins, which attach the cell to the substrate, forming a focal adhesion. A variety of signaling proteins are also associated with focal adhesions. Forces are transmitted to the substrate at these sites, and an intact focal adhesion is important for mechanically induced osteogenesis. The primary cilium is a single, immotile, antenna-like structure that extends from the cell into the extracellular space. It has emerged as an important signaling center, acting as a microdomain to facilitate biochemical signaling. Mechanotransduction is the process by which physical stimuli are converted into biochemical responses. When potential mechanosensors are disrupted, the activities of components of mechanotransduction pathways are also inhibited, preventing mechanically induced osteogenesis. Calcium, mitogen-activated protein kinase/extracellular signal-regulated kinase, Wnt, Yes-associated protein/transcriptional coactivator with PDZ-binding motif and RhoA/Rho kinase signaling are some of the mechanotransduction pathways proposed to be important. In this review, types of mechanical stimuli, mechanosensors, and key pathways involved in mechanically induced osteogenesis of stem cells are discussed. PMID:24004875

2013-01-01

20

Differentiation of Neural Lineage Cells from Human Pluripotent Stem Cells  

PubMed Central

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

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

2008-01-01

21

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

PubMed

In order 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 intestinal stem cells (ISCs) that limits ISC commitment to the endocrine lineage, establishing negative feedback control of EE regeneration. Furthermore, we show that this lineage decision is made within ISCs and requires induction of the transcription factor Prospero in ISCs. Our work identifies a 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

Biteau, Benoît; Jasper, Heinrich

2014-06-26

22

Cell Shape, Cytoskeletal Tension, and RhoA Regulate Stem Cell Lineage Commitment  

Microsoft Academic Search

Commitment of stem cells to different lineages is regulated by many cues in the local tissue microenvironment. Here we demonstrate that cell shape regulates commitment of human mesenchymal stem cells (hMSCs) to adipocyte or osteoblast fate. hMSCs allowed to adhere, flatten, and spread underwent osteogenesis, while unspread, round cells became adipocytes. Cell shape regulated the switch in lineage commitment by

Rowena McBeath; Dana M. Pirone; Celeste M. Nelson; Kiran Bhadriraju; Christopher S. Chen

2004-01-01

23

Foetal stem cell derivation & characterization for osteogenic lineage  

PubMed Central

Background & objectives: Mesencymal stem cells (MSCs) derived from foetal tissues present a multipotent progenitor cell source for application in tissue engineering and regenerative medicine. The present study was carried out to derive foetal mesenchymal stem cells from ovine source and analyze their differentiation to osteogenic linage to serve as an animal model to predict human applications. Methods: Isolation and culture of sheep foetal bone marrow cells were done and uniform clonally derived MSC population was collected. The cells were characterized using cytochemical, immunophenotyping, biochemical and molecular analyses. The cells with defined characteristics were differentiated into osteogenic lineages and analysis for differentiated cell types was done. The cells were analyzed for cell surface marker expression and the gene expression in undifferentiated and differentiated osteoblast was checked by reverse transcriptase PCR (RT PCR) analysis and confirmed by sequencing using genetic analyzer. Results: Ovine foetal samples were processed to obtain mononuclear (MNC) cells which on culture showed spindle morphology, a characteristic oval body with the flattened ends. MSC population CD45-/CD14- was cultured by limiting dilution to arrive at uniform spindle morphology cells and colony forming units. The cells were shown to be positive for surface markers such as CD44, CD54, integrin?1, and intracellular collagen type I/III and fibronectin. The osteogenically induced MSCs were analyzed for alkaline phosphatase (ALP) activity and mineral deposition. The undifferentiated MSCs expressed RAB3B, candidate marker for stemness in MSCs. The osteogenically induced and uninduced MSCs expressed collagen type I and MMP13 gene in osteogenic induced cells. Interpretation & conclusions: The protocol for isolation of ovine foetal bone marrow derived MSCs was simple to perform, and the cultural method of obtaining pure spindle morphology cells was established. Criteria proposed for defining MSCs by this study includes the cell adherence to culture plates, specific surface protein profiles and differentiation to osteogenic lineage. The MSCs and osteogenic differentiated cells in this ovine animal model may serve as a large source for stem cell applications in regenerative medical therapies. PMID:23563374

Gowri, A. Mangala; Kavitha, G.; Rajasundari, M.; Fathima, S. Mubeen; Kumar, T.M.A. Senthil; Raj, G. Dhinakar

2013-01-01

24

Differentiation of murine embryonic stem and induced pluripotent stem cells to renal lineage in vitro  

SciTech Connect

Embryonic stem (ES) cells which have the unlimited proliferative capacity and extensive differentiation potency can be an attractive source for kidney regeneration therapies. Recent breakthroughs in the generation of induced pluripotent stem (iPS) cells have provided with another potential source for the artificially-generated kidney. The purpose of this study is to know how to differentiate mouse ES and iPS cells into renal lineage. We used iPS cells from mouse fibroblasts by transfection of four transcription factors, namely Oct4, Sox2, c-Myc and Klf4. Real-time PCR showed that renal lineage markers were expressed in both ES and iPS cells after the induction of differentiation. It also showed that a tubular specific marker, KSP progressively increased to day 18, although the differentiation of iPS cells was slower than ES cells. The results indicated that renal lineage cells can be differentiated from both murine ES and iPS cells. Several inducing factors were tested whether they influenced on cell differentiation. In ES cells, both of GDNF and BMP7 enhanced the differentiation to metanephric mesenchyme, and Activin enhanced the differentiation of ES cells to tubular cells. Activin also enhanced the differentiation of iPS cells to tubular cells, although the enhancement was lower than in ES cells. ES and iPS cells have a potential to differentiate to renal lineage cells, and they will be an attractive resource of kidney regeneration therapy. This differentiation is enhanced by Activin in both ES and iPS cells.

Morizane, Ryuji [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan)] [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan); Monkawa, Toshiaki, E-mail: monkawa@sc.itc.keio.ac.jp [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan)] [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan); Itoh, Hiroshi [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan)] [Department of Internal Medicine, Keio University School of Medicine, Tokyo (Japan)

2009-12-25

25

Epigenetic dynamics of stem cells and cell lineage commitment: digging Waddington's canal.  

PubMed

Cells of the early mammalian embryo, including pluripotent embryonic stem (ES) cells and primordial germ cells (PGCs), are epigenetically dynamic and heterogeneous. During early development, this heterogeneity of epigenetic states is associated with stochastic expression of lineage-determining transcription factors that establish an intimate crosstalk with epigenetic modifiers. Lineage-specific epigenetic modification of crucial transcription factor loci (for example, methylation of the Elf5 promoter) leads to the restriction of transcriptional circuits and the fixation of lineage fate. The intersection of major epigenetic reprogramming and programming events in the early embryo creates plasticity followed by commitment to the principal cell lineages of the early conceptus. PMID:19603040

Hemberger, Myriam; Dean, Wendy; Reik, Wolf

2009-08-01

26

The differentiation of embryonic stem cells seeded on electrospun nanofibers into neural lineages  

Microsoft Academic Search

Due to advances in stem cell biology, embryonic stem (ES) cells can be induced to differentiate into a particular mature cell lineage when cultured as embryoid bodies. Although transplantation of ES cells-derived neural progenitor cells has been demonstrated with some success for either spinal cord injury repair in small animal model, control of ES cell differentiation into complex, viable, higher

Jingwei Xie; Stephanie M. Willerth; Xiaoran Li; Matthew R. Macewan; Allison Rader; Shelly E. Sakiyama-Elbert; Younan Xia

2009-01-01

27

Colon Stem Cell and Crypt Dynamics Exposed by Cell Lineage Reconstruction  

PubMed Central

Stem cell dynamics in vivo are often being studied by lineage tracing methods. Our laboratory has previously developed a retrospective method for reconstructing cell lineage trees from somatic mutations accumulated in microsatellites. This method was applied here to explore different aspects of stem cell dynamics in the mouse colon without the use of stem cell markers. We first demonstrated the reliability of our method for the study of stem cells by confirming previously established facts, and then we addressed open questions. Our findings confirmed that colon crypts are monoclonal and that, throughout adulthood, the process of monoclonal conversion plays a major role in the maintenance of crypts. The absence of immortal strand mechanism in crypts stem cells was validated by the age-dependent accumulation of microsatellite mutations. In addition, we confirmed the positive correlation between physical and lineage proximity of crypts, by showing that the colon is separated into small domains that share a common ancestor. We gained new data demonstrating that colon epithelium is clustered separately from hematopoietic and other cell types, indicating that the colon is constituted of few progenitors and ruling out significant renewal of colonic epithelium from hematopoietic cells during adulthood. Overall, our study demonstrates the reliability of cell lineage reconstruction for the study of stem cell dynamics, and it further addresses open questions in colon stem cells. In addition, this method can be applied to study stem cell dynamics in other systems. PMID:21829376

Itzkovitz, Shalev; Elbaz, Judith; Maruvka, Yosef E.; Segev, Elad; Shlush, Liran I.; Dekel, Nava; Shapiro, Ehud

2011-01-01

28

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

E-print Network

distinct subpopulation of cells with stem cell properties in pre-invasive pancreatic cancer," by Bailey JMNew Insights Into the Cell Lineage of Pancreatic Ductal Adenocarcinoma: Evidence for Tumor Stem Cells in Premalignant Lesions? See "Identification and manipulation of biliary metaplasia in pancreatic

Sander, Maike

29

Differential gene expression in human hematopoietic stem cells specified toward erythroid, megakaryocytic, and granulocytic lineage  

Microsoft Academic Search

To better understand the transcrip- tional program that accompanies orderly lineage- specific hematopoietic differentiation, we analyzed expression changes during the lineage-specific dif- ferentiation of human hematopoietic stem cells (HSC; CD34\\/CD38-\\/CD33-); HSC and multipo- tent myeloid progenitors (MMP; CD34\\/CD38-\\/ CD33) were isolated from the bone marrow of healthy individuals by MACS. CD34 cells in semi- solid culture were stimulated with the

Xiao-Ling Liu; Jin-Yun Yuan; Jun-Wu Zhang; Xin-Hua Zhang; Rong-Xin Wang

2007-01-01

30

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

PubMed Central

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

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

2014-01-01

31

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.

32

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

PubMed Central

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

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

33

Epigenomic Analysis of Multi-lineage Differentiation of Human Embryonic Stem Cells  

PubMed Central

SUMMARY Epigenetic mechanisms have been proposed to play crucial roles in mammalian development, but their precise functions are only partially understood. To investigate epigenetic regulation of embryonic development, we differentiated human embryonic stem cells into mesendoderm, neural progenitor cells, trophoblast-like cells, and mesenchymal stem cells, and systematically characterized DNA methylation, chromatin modifications, and the transcriptome in each lineage. We found that promoters that are active in early developmental stages tend to be CG rich and mainly engage H3K27me3 upon silencing in non-expressing lineages. By contrast, promoters for genes expressed preferentially at later stages are often CG poor and primarily employ DNA methylation upon repression. Interestingly, the early developmental regulatory genes are often located in large genomic domains that are generally devoid of DNA methylation in most lineages, which we termed DNA methylation valleys (DMVs). Our results suggest that distinct epigenetic mechanisms regulate early and late stages of ES cell differentiation. PMID:23664764

Xie, Wei; Schultz, Matthew D.; Lister, Ryan; Hou, Zhonggang; Rajagopal, Nisha; Ray, Pradipta; Whitaker, John W.; Tian, Shulan; Hawkins, R. David; Leung, Danny; Yang, Hongbo; Wang, Tao; Lee, Ah Young; Swanson, Scott A.; Zhang, Jiuchun; Zhu, Yun; Kim, Audrey; Nery, Joseph R.; Urich, Mark A.; Kuan, Samantha; Yen, Chia-an; Klugman, Sarit; Yu, Pengzhi; Suknuntha, Kran; Propson, Nicholas E.; Chen, Huaming; Edsall, Lee E.; Wagner, Ulrich; Li, Yan; Ye, Zhen; Kulkarni, Ashwinikumar; Xuan, Zhenyu; Chung, Wen-Yu; Chi, Neil C.; Antosiewicz-Bourget, Jessica E.; Slukvin, Igor; Stewart, Ron; Zhang, Michael Q.; Wang, Wei; Thomson, James A.; Ecker, Joseph R.; Ren, Bing

2013-01-01

34

Epigenomic Analysis of Multi-lineage Differentiation of Human Embryonic Stem Cells  

PubMed Central

Epigenetic mechanisms have been proposed as crucial for regulating mammalian development, but their precise function is only partially understood. To investigate the epigenetic control of embryonic development, we differentiated human embryonic stem cells into mesendoderm, neural progenitor cells, trophoblast-like cells, and mesenchymal stem cells and systematically characterized DNA methylation, chromatin modifications, and the transcriptome in each lineage. Strikingly, we found that promoters that are active in early developmental stages tend to be CG rich and mainly engage H3K27me3 upon silencing in non-expressing lineages. By contrast, promoters for genes expressed preferentially at later stages are often CG poor and employ DNA methylation upon repression. Interestingly, the early developmental regulatory genes are often located in large genomic domains that are generally devoid of DNA methylation in most lineages, as we termed DNA methylation valleys (DMVs). Our results suggest that distinct epigenetic mechanisms regulate early and late stages of ES cell differentiation.

Garcia, Benjamin; Xie, Wei; Schultz, Matt; Lister, Ryan; Hou, Zhonggang; Rajagopal, Nisha; Ray, Pradipta; Whitaker, John W.; Tian, Shulan; Hawkins, R. David; Leung, Danny; Yang, Hongbo; Wang, Tao; Lee, Ah Young; Swanson, Scott A.; Zhang, Jiuchun; Zhu, Yun; Kim, Audrey; Nery, Joseph; Urich, Mark A.; Kuan, Samantha; Yen, Chia-an; Klugman, Sarit; Yu, Pengzhi; Suknuntha, Kran; Propson, Nicholas E.; Chen, Huaming; Edsall, Lee E.; Wagner, Ulrich; Li, Yan; Ye, Zhen; Kulkarni, Ashwinikumar; Xuan, Zhenyu; Chung, Wen-yu; Chi, Neil C.; Antosiewicz-Bourget, Jessica; Slukvin, Igor; Stewart, Ron; Zhang, Michael Q.; Wang, Wei; Thomson, James A.; Ecker, Joseph R.; Ren, Bing

2013-01-01

35

Differentiation of Embryonic Stem Cells to Vascular Cell Lineages  

Microsoft Academic Search

\\u000a In the face of extraordinary advances in the ­prevention, diagnosis, and treatment of human diseases, devastating cardiopulmonary\\u000a diseases continue to deprive people of health. Research in developmental biology has led to the discovery of stem cells, which\\u000a provide a platform to understand the basic mechanism of those diseases and give a hope for potential clinical applications.\\u000a Three main types of

Andriana Margariti; Lingfang Zeng; Qingbo Xu

36

Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

37

Rewiring mesenchymal stem cell lineage specification by switching the biophysical microenvironment  

PubMed Central

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

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

2014-01-01

38

Dinosaur Day!  

ERIC Educational Resources Information Center

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…

Nakamura, Sandra; Baptiste, H. Prentice

2006-01-01

39

Polycomb group protein expression during differentiation of human embryonic stem cells into pancreatic lineage in vitro  

PubMed Central

Background Polycomb Group (PcG) proteins are chromatin modifiers involved in early embryonic development as well as in proliferation of adult stem cells and cancer cells. PcG proteins form large repressive complexes termed Polycomb Repressive Complexes (PRCs) of which PRC1 and PRC2 are well studied. Differentiation of human Embryonic Stem (hES) cells into insulin producing cells has been achieved to limited extent, but several aspects of differentiation remain unexplored. The PcG protein dynamics in human embryonic stem (hES) cells during differentiation into pancreatic lineage has not yet been reported. In the present study, the expression of RING1A, RING1B, BMI1, CBX2, SUZ12, EZH2, EED and JARID2 during differentiation of hES cells towards pancreatic lineage was examined. Results In-house derived hES cell line KIND1 was used to study expression of PcG protein upon spontaneous and directed differentiation towards pancreatic lineage. qRT-PCR analysis showed expression of gene transcripts for various lineages in spontaneously differentiated KIND1 cells, but no differentiation into pancreatic lineage was observed. Directed differentiation induced KIND1 cells grown under feeder-free conditions to transition from definitive endoderm (Day 4), primitive gut tube stage (Day 8) and pancreatic progenitors (Day 12-Day 16) as evident from expression of SOX17, PDX1 and SOX9 by qRT-PCR and Western blotting. In spontaneously differentiating KIND1 cells, RING1A and SUZ12 were upregulated at day 15, while other PcG transcripts were downregulated. qRT-PCR analysis showed transcripts of RING1B, BMI1, SUZ12, EZH2 and EED were upregulated, while RING1A and CBX2 expression remained low and JARID2 was downregulated during directed differentiation of KIND1 cells. Upregulation of BMI1, EZH2 and SUZ12 during differentiation into pancreatic lineage was also confirmed by Western blotting. Histone modifications such as H3K27 trimethylation and monoubiquitinylation of H2AK119 increased during differentiation into pancreatic lineage as seen by Western blotting. Conclusion Our study shows expression of PcG proteins was distinct during spontaneous and directed differentiation. Differentiation into pancreatic lineage was achieved by directed differentiation approach and was associated with increased expression of PcG proteins RING1B, BMI1, EZH2 and SUZ12 accompanied by increase in monoubiquitinylation of H2AK119 and trimethylation of H3K27. PMID:24885493

2014-01-01

40

Lineage specific expression of Polycomb Group Proteins in human embryonic stem cells in vitro.  

PubMed

Human embryonic (hES) stem cells are an excellent model to study lineage specification and differentiation into various cell types. Differentiation necessitates repression of specific genes not required for a particular lineage. Polycomb Group (PcG) proteins are key histone modifiers, whose primary function is gene repression. PcG proteins form complexes called Polycomb Repressive Complexes (PRCs), which catalyze histone modifications such as H2AK119ub1, H3K27me3, and H3K9me3. PcG proteins play a crucial role during differentiation of stem cells. The expression of PcG transcripts during differentiation of hES cells into endoderm, mesoderm, and ectoderm lineage is yet to be shown. In-house derived hES cell line KIND1 was differentiated into endoderm, mesoderm, and ectoderm lineages; followed by characterization using RT-PCR for HNF4A, CDX2, MEF2C, TBX5, SOX1, and MAP2. qRT-PCR and western blotting was performed to compare expression of PcG transcripts and proteins across all the three lineages. We observed that cells differentiated into endoderm showed upregulation of RING1B, BMI1, EZH2, and EED transcripts. Mesoderm differentiation was characterized by significant downregulation of all PcG transcripts during later stages. BMI1 and RING1B were upregulated while EZH2, SUZ12, and EED remained low during ectoderm differentiation. Western blotting also showed distinct expression of BMI1 and EZH2 during differentiation into three germ layers. Our study shows that hES cells differentiating into endoderm, mesoderm, and ectoderm lineages show distinct PcG expression profile at transcript and protein level. PMID:25572667

Pethe, Prasad; Pursani, Varsha; Bhartiya, Deepa

2015-05-01

41

The differentiation of embryonic stem cells seeded on electrospun nanofibers into neural lineages  

PubMed Central

Due to advances in stem cell biology, embryonic stem (ES) cells can be induced to differentiate into a particular mature cell lineage when cultured as embryoid bodies. Although transplantation of ES cells-derived neural progenitor cells has been demonstrated with some success for either spinal cord injury repair in small animal model, control of ES cell differentiation into complex, viable, higher ordered tissues is still challenging. Mouse ES cells have been induced to become neural progenitors by adding retinoic acid to embryoid body cultures for 4 days. In this study, we examine the use of electrospun biodegradable polymers as scaffolds not only for enhancing the differentiation of mouse ES cells into neural lineages but also for promoting and guiding the neurite outgrowth. A combination of electrospun fiber scaffolds and ES cells-derived neural progenitor cells could lead to the development of a better strategy for nerve injury repair. PMID:18930315

Xie, Jingwei; Willerth, Stephanie M.; Li, Xiaoran; Macewan, Matthew R.; Rader, Allison; Sakiyama-Elbert, Shelly E.; Xia, Younan

2008-01-01

42

The Satb1 protein directs hematopoietic stem cell differentiation toward lymphoid lineages.  

PubMed

How hematopoietic stem cells (HSCs) produce particular lineages is insufficiently understood. We searched for key factors that direct HSC to lymphopoiesis. Comparing gene expression profiles for HSCs and early lymphoid progenitors revealed that Satb1, a global chromatin regulator, was markedly induced with lymphoid lineage specification. HSCs from Satb1-deficient mice were defective in lymphopoietic activity in culture and failed to reconstitute T lymphopoiesis in wild-type recipients. Furthermore, Satb1 transduction of HSCs and embryonic stem cells robustly promoted their differentiation toward lymphocytes. Whereas genes that encode Ikaros, E2A, and Notch1 were unaffected, many genes involved in lineage decisions were regulated by Satb1. Satb1 expression was reduced in aged HSCs with compromised lymphopoietic potential, but forced Satb1 expression partly restored that potential. Thus, Satb1 governs the initiating process central to the replenishing of lymphoid lineages. Such activity in lymphoid cell generation may be of clinical importance and useful to overcome immunosenescence. PMID:23791645

Satoh, Yusuke; Yokota, Takafumi; Sudo, Takao; Kondo, Motonari; Lai, Anne; Kincade, Paul W; Kouro, Taku; Iida, Ryuji; Kokame, Koichi; Miyata, Toshiyuki; Habuchi, Yoko; Matsui, Keiko; Tanaka, Hirokazu; Matsumura, Itaru; Oritani, Kenji; Kohwi-Shigematsu, Terumi; Kanakura, Yuzuru

2013-06-27

43

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.

44

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

PubMed Central

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

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

2015-01-01

45

Scholastic: Dinosaurs  

NSDL National Science Digital Library

This website contains details and activities about dinosaurs. It covers the geologic time periods during which dinosaurs existed, a web-quest for dinosaur information, quizzes and games about various dinosaur topics, and research starters for projects and activities. For teachers, there are lesson plan suggestions, assessment ideas, and details for using this site in the classroom as a project. Links are provided for additional information.

46

Dinosaur Interaction  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

47

Sall4 regulates distinct transcription circuitries in different blastocyst-derived stem cell lineages.  

PubMed

Stem cells self-renew or differentiate under the governance of a stem-cell-specific transcriptional program, with each transcription factor orchestrating the activities of a particular set of genes. Here we demonstrate that a single transcription factor is able to regulate distinct core circuitries in two different blastocyst-derived stem cell lines, embryonic stem cells (ESCs) and extraembryonic endoderm (XEN) cells. The transcription factor Sall4 is required for early embryonic development and for ESC pluripotency. Sall4 is also expressed in XEN cells, and depletion of Sall4 disrupts self-renewal and induces differentiation. Genome-wide analysis reveals that Sall4 is regulating different gene sets in ESCs and XEN cells, and depletion of Sall4 targets in the respective cell types induces differentiation. With Oct4, Sox2, and Nanog, Sall4 forms a crucial interconnected autoregulatory network in ESCs. In XEN cells, Sall4 regulates the key XEN lineage-associated genes Gata4, Gata6, Sox7, and Sox17. Our findings demonstrate how Sall4 functions as an essential stemness factor for two different stem cell lines. PMID:18804426

Lim, Chin Yan; Tam, Wai-Leong; Zhang, Jinqiu; Ang, Haw Siang; Jia, Hui; Lipovich, Leonard; Ng, Huck-Hui; Wei, Chia-Lin; Sung, Wing Kin; Robson, Paul; Yang, Henry; Lim, Bing

2008-11-01

48

Histone Deacetylase 1 and 3 Regulate the Mesodermal Lineage Commitment of Mouse Embryonic Stem Cells  

PubMed Central

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

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

2014-01-01

49

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

PubMed Central

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

Shan, Jixiu; Hamazaki, Takashi; Tang, Tiffany A.; Terada, Naohiro

2013-01-01

50

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.

51

Directing Human Induced Pluripotent Stem Cells into a Neurosensory Lineage for Auditory Neuron Replacement  

PubMed Central

Abstract Emerging therapies for sensorineural hearing loss include replacing damaged auditory neurons (ANs) using stem cells. Ultimately, it is important that these replacement cells can be patient-matched to avoid immunorejection. As human induced pluripotent stem cells (hiPSCs) can be obtained directly from the patient, they offer an opportunity to generate patient-matched neurons for transplantation. Here, we used an established neural induction protocol to differentiate two hiPSC lines (iPS1 and iPS2) and one human embryonic stem cell line (hESC; H9) toward a neurosensory lineage in vitro. Immunocytochemistry and qRT-PCR were used to analyze the expression of key markers involved in AN development at defined time points of differentiation. The hiPSC- and hESC-derived neurosensory progenitors expressed the dorsal hindbrain marker (PAX7), otic placodal marker (PAX2), proneurosensory marker (SOX2), ganglion neuronal markers (NEUROD1, BRN3A, ISLET1, ßIII-tubulin, Neurofilament kDa 160), and sensory AN markers (GATA3 and VGLUT1) over the time course examined. The hiPSC- and hESC-derived neurosensory progenitors had the highest expression levels of the sensory neural markers at 35 days in vitro. Furthermore, the neurons generated from this assay were found to be electrically active. While all cell lines analyzed produced functional neurosensory-like progenitors, variabilities in the levels of marker expression were observed between hiPSC lines and within samples of the same cell line, when compared with the hESC controls. Overall, these findings indicate that this neural assay was capable of differentiating hiPSCs toward a neurosensory lineage but emphasize the need for improving the consistency in the differentiation of hiPSCs into the required lineages. PMID:25126480

Gunewardene, Niliksha; Bergen, Nicole Van; Crombie, Duncan; Needham, Karina; Dottori, Mirella

2014-01-01

52

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

PubMed Central

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

Takashima, Shigeo; Gold, David; Hartenstein, Volker

2012-01-01

53

Dinosaur evolution. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds.  

PubMed

Recent discoveries have highlighted the dramatic evolutionary transformation of massive, ground-dwelling theropod dinosaurs into light, volant birds. Here, we apply Bayesian approaches (originally developed for inferring geographic spread and rates of molecular evolution in viruses) in a different context: to infer size changes and rates of anatomical innovation (across up to 1549 skeletal characters) in fossils. These approaches identify two drivers underlying the dinosaur-bird transition. The theropod lineage directly ancestral to birds undergoes sustained miniaturization across 50 million years and at least 12 consecutive branches (internodes) and evolves skeletal adaptations four times faster than other dinosaurs. The distinct, prolonged phase of miniaturization along the bird stem would have facilitated the evolution of many novelties associated with small body size, such as reorientation of body mass, increased aerial ability, and paedomorphic skulls with reduced snouts but enlarged eyes and brains. PMID:25082702

Lee, Michael S Y; Cau, Andrea; Naish, Darren; Dyke, Gareth J

2014-08-01

54

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

PubMed

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

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

55

Cytokine-Regulated GADD45G Induces Differentiation and Lineage Selection in Hematopoietic Stem Cells  

PubMed Central

Summary 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

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

2014-01-01

56

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

PubMed

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

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

57

FGF4-DEPENDENT STEM CELLS DERIVED FROM RAT BLASTOCYSTS DIFFERENTIATE ALONG THE TROPHOBLAST LINEAGE  

PubMed Central

Differentiated trophoblast cell lineages arise from trophoblast stem (TS) cells. To date such a stem cell population has only been established in the mouse. The objective of this investigation was to establish TS cell populations from rat blastocysts. Blastocysts were cultured individually on a feeder layer of rat embryonic fibroblasts (REFs) in fibroblast growth factor-4 (FGF4) and heparin supplemented culture medium. Once cell colonies were established REF feeder layers could be replaced with REF conditioned medium. The blastocyst-derived cell lines, in either proliferative or differentiated states, did not express genes indicative of ICM-derived tissues. In the proliferative state the cells expressed established stem cell-associated markers of TS cells. Cells ceased proliferation and differentiated when FGF4, heparin, and REF conditioned medium were removed. Differentiation was characterized by a decline of stem cell-associated marker gene expression, the appearance of large polyploid cells (trophoblast giant cells), and the expression of trophoblast differentiation-associated genes. Collectively, the data indicate that the rat blastocyst-derived cell lines possess many features characteristic of mouse TS cells but also possess some distinct properties. These rat TS cell lines represent valuable new in vitro models for analyses of mechanisms controlling TS cell renewal and differentiation. PMID:21215265

Asanoma, Kazuo; Rumi, M.A. Karim; Kent, Lindsey N.; Chakraborty, Damayanti; Renaud, Stephen J.; Wake, Norio; Lee, Dong-Soo; Kubota, Kaiyu; Soares, Michael J.

2011-01-01

58

The Drosophila female germline stem cell lineage acts to spatially restrict DPP function within the niche.  

PubMed

Maintenance of stem cells requires spatially restricted, niche-associated signals. In the Drosophila female germline stem cell (GSC) niche, Decapentaplegic (DPP) is the primary niche-associated factor and functions over a short range to promote GSC self-renewal rather than differentiation. Here, we show that the GSC lineage and, more specifically, the stem cells themselves participate in the spatial restriction of DPP function by activating epidermal growth factor receptor (EGFR)-mitogen-activated protein kinase (MAPK) signaling in the surrounding somatic cells. EGFR-MAPK signaling in somatic cells repressed the expression of dally, which encodes a glypican required for DPP movement and stability. Consequently, only GSCs close to the DPP source (the somatic cells in the niche) showed high signal activation and were maintained as stem cells, whereas cystoblasts outside the niche showed low signal activation and initiated differentiation. Thus, our data reveal that the reciprocal crosstalk between the GSCs and the somatic cells defines the spatial limits of DPP action and therefore the extent of the GSC niche. PMID:20664066

Liu, Ming; Lim, Tit Meng; Cai, Yu

2010-01-01

59

Dinosaur Paleontology  

NSDL National Science Digital Library

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.

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

1995-06-30

60

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_.

61

Dinosaur News  

NSDL National Science Digital Library

Publishing the latest findings and theories in the wide world of dinosaur science since 1998, Dinosaur News will raise the eyebrows of even the least paleontologically inclined. Did you know that tyrannosauruses may have hunted in packs? Are you curious where the apocalyptic asteroid that wiped out the dinosaurs came from? Want to hear about the latest dinosaur exhibits from around the country â?? and the world? The Dinosaur News has all this and more. Visitors can explore a variety of features, including Links We Like and What Readers Say, but may wish to start with The Dinosaurnews Daily. This newsfeed-style site is updated daily and offers exciting headlines, photos, videos, and more. Make sure to sign up for the Dinosaur News Newsletter, then tour the well-appointed bookstore and the gift shop if so desired.

62

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

SciTech Connect

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.

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

63

Small SSEA-4-positive cells from human ovarian cell cultures: related to embryonic stem cells and germinal lineage?  

PubMed Central

Background It has already been found that very small embyronic-like stem cells (VSELs) are present in adult human tissues and organs. The aim of this study was to find if there exists any similar population of cells in cell cultures of reproductive tissues and embryonic stem cells, and if these cells have any relation to pluripotency and germinal lineage. Methods and results Here we report that a population of small SSEA-4-positive cells with diameters of up to 4 ?m was isolated by fluorescence-activated cell sorting (FACS) from the human ovarian cell cultures after enzymatic degradation of adult cortex tissues. These small cells – putative ovarian stem cells – were also observed during cell culturing of up to 6 months and more. In general, small putative ovarian stem cells, isolated by FACS, showed a relatively low gene expression profile when compared to human embryonic stem cells (hESCs) and human adult fibroblasts; this may reflect the quiescent state of these cells. In spite of that, small putative ovarian stem cells expressed several genes related to primordial germ cells (PGCs), pluripotency and germinal lineage, including VASA. The PGC-related gene PRDM1 was strongly expressed in small putative ovarian stem cells; in both hESCs and fibroblasts it was significantly down-regulated. In addition, putative ovarian stem cells expressed other PGC-related genes, such as PRDM14 and DPPA3. Most of the pluripotency and germinal lineage-related genes were up-regulated in hESCs (except VASA). When compared to fibroblasts, there were several pluripotency-related genes, which were up-regulated in small putative ovarian stem cells. Similar populations of small cells were also isolated by FACS from human testicular and hESC cultures. Conclusions Our results confirm the potential embryonic-like character of small putative stem cells isolated from human adult ovaries and their possible relation to germinal lineage. PMID:23570331

2013-01-01

64

Regulation of adult human mesenchymal stem cells into osteogenic and chondrogenic lineages by different bioreactor systems.  

PubMed

The aim of this study was to examine the feasibility of expanding and regulating mesenchymal stem cells (MSCs) from isolated adult human bone marrow mononuclear cells, seeded on gelatin-hyaluronic acid biomatrices, and then to quantitatively compare the gene expression in three different culture systems. Individual and interactive effects of model system parameters on construct structure, function, and molecular properties were evaluated. The results showed that these adult human MSCs even at old age not only expressed primitive mesenchymal cell markers but also maintained a high level of colony-forming efficiency and were capable of differentiating into osteoblasts, chondrocytes, and adipocytes upon appropriate inductions. After 21 days of culture, we found that the osteoblastic and chondrocytic lineage gene expression were earlier and higher expressed in spinner flask bioreactor culture group when compared with the static culture and rotating wall vessel reactor culture. The osteogenic lineage proteins type I collagen, alkaline phosphatase, and osteocalcin were strongly stained in histological sections of spinner flask bioreactor culture, whereas these were less detected in the other two groups, especially in rotating wall vessel reactor culture. As for the markers associated with the chondrogenic lineage differentiation proteins, type II collagen was apparently expressed in spinner flask culture group, while the expression of proteoglycans (aggreacan, decorin) in three culture conditions took the lead of each other. We conclude that the spinner flask bioreactor with appropriate induction medium reported in this study may be used to rapidly expand adult MSCs and is likely to possess better induction results toward osteoblastic and chondrocytic lineages. PMID:18384159

Wang, Tzu-Wei; Wu, Hsi-Chin; Wang, Hsin-Yen; Lin, Feng-Huei; Sun, Jui-Sheng

2009-03-15

65

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.

66

Dinosaur Detectives  

NSDL National Science Digital Library

This lesson plan will help students learn that discoveries about dinosaurs have a long history and that each paleontologist adds his or her work to a body of fossil evidence used to support theories about dinosaurs. In it, students will use the internet to explore the discovery of fossils and dinosaurs. The website includes the lesson plan, extensions, guidelines for evaluation, and MCREL standards alignment.

Audrey Carangelo

2008-01-01

67

Twist-1, a novel regulator of hematopoietic stem cell self-renewal and myeloid lineage development.  

PubMed

Transcription factor Twist-1 plays essential roles in specification and differentiation of mesoderm-derived tissues. Growing evidences now link Twist-1 to the acquisition of stem-cell-like properties. However, the role of Twist-1 in hematopoietic stem cell (HSC) remains largely uncharacterized. We report that Twist-1 is more highly expressed in murine HSC and its expression declines with differentiation. To investigate Twist-1 gene function, retroviral-mediated overexpression or removal experiments are performed. Competitive repopulation studies demonstrate that enforced expression of Twist-1 in HSC-enriched Lin(-) c-Kit(+) Sca-1(+) (LKS) cells results in an increase in the size of the G(0) population, and in their reconstitution ability after the first and a second transplantation. Conversely, removal of Twist-1 in LKS cells impairs their ability to repopulate. In addition, increased Twist-1 expression causes a shift toward production of myeloid cells. Twist-1 transduction in LKS cells activates myeloid lineage-determining factors PU.1 and GATA-1 and downregulates lymphoid factor GATA-3 in vitro, suggesting that Twist-1-mediated myeloid skewing occurs in hematopoietic stem and progenitor cells (HSPCs). These findings indicate that Twist-1 is not only involved in the maintenance of HSC dormancy and self-renewal capacity but also implicated in the myeloid lineage fate choice of HSPCs. Exploration of the underlying mechanisms reveals that Runx1/c-Mpl/Tie2 regulatory pathway could possibly account for the observed effects caused by Twist-1 overexpression. Our study provides the first evidence supporting a role for Twist-1 in hematopoiesis. PMID:25100001

Dong, Cheng-Ya; Liu, Xiao-Yan; Wang, Nan; Wang, Li-Na; Yang, Bin-Xia; Ren, Qian; Liang, Hao-Yue; Ma, Xiao-Tong

2014-12-01

68

In vitro differentiation of rat mesenchymal stem cells to hepatocyte lineage  

PubMed Central

Objective(s): Mesenchyme is a type of undifferentiated loose connective tissue that is derived mostly from mesoderm. Recently, mesenchymal stem cells (MSCs), as adult stem cells (ASCs) able to divide into a variety of different cells, are of utmost importance for stem cell research. In this research, ability of the liver extract to induce differentiation of rat derived omentum tissue mesenchymal stem cells (rOT-MSCs) into hepatocyte cells (HCs) was investigated. Materials and Methods: After isolation and confirmation of rOT-MSCs they were co-cultured with liver extract and hepatogenic differentiation was monitored. Expressions of mesenchymal stem cell markers were also analyzed via flow cytometry. Moreover, expressions of octamer-binding transcription factor-4 (Oct-4), Wilm’s tumor suppressor gene-1 (WT-1), albumin (ALB), alpha fetoprotein (AFP), cytokeratin-18 (CK-18), and mRNAs were analyzed using RT-PCR on days 16, 18 and 21. ALB production was analyzed by immunocytochemistry and western blot. Furthermore, glycogen and urea production were determined via periodic acid-Schiff (PAS) staining and colorimetric assays respectively. Results: The phenotypic characterization revealed the positive expressions of CD90, CD44 and negative expression of CD45 in rOT-MSCs. These cells also expressed mRNA of Oct-4 and WT-1 as markers of omentum tissue. Differentiated rOT-MSCs in presence of 6 µg/ml liver extract expressed ALB, AFP, CK-18, glycogen and urea as specific markers of HCs. Conclusion: These observations suggest that liver extract is potentially able to induce differentiation of MSCs into hepatocyte lineage and can be considered an available source for imposing tissue healing on the damaged liver. PMID:25810881

Sarvandi, Samaneh Solati; Joghataei, Mohammad Taghi; Parivar, Kazem; Khosravi, Maryam; Sarveazad, Arash; Sanadgol, Nima

2015-01-01

69

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

PubMed

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

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

2015-05-01

70

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.

71

Dinosaur Names  

NSDL National Science Digital Library

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.

Craig Munsart

72

Dinosaur Homes  

NSDL National Science Digital Library

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.

OMSI

2004-01-01

73

Dinosaur Day!  

NSDL National Science Digital Library

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.

H. Prentice Baptiste

2006-01-01

74

Dinosaur Dig  

NSDL National Science Digital Library

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 ...

Teanna Vincent

2009-11-09

75

Chinese Dinosaurs  

NSDL National Science Digital Library

What's "Jurassic Park" in Mandarin? That isn't easy to say, but if you're interested in Chinese dinosaurs, then you will love the new online (and real) exhibit hosted by the Australian Museum in Sydney. A vast land containing many of the world's best-preserved dinosaur specimens, China offers remnants of many species not commonly available in Western exhibits. With lots to explore, the site features a readily accessible list of dinosaurs, each arranged under its Chinese-derived species name. Not like anything most of us have ever heard, many of the specimens look and seem familiar, at least as members of the dinosaur family. While generally well-executed, particularly worthy of note is the site's presentation of China's celebrated feathered dinosaurs, Caudipteryx zoui and Protarchaeopteryx, two curious figures believed to represent part of the great reptilian leap from land to air.

2002-01-01

76

Dynamic loading of electrospun yarns guides mesenchymal stem cells towards a tendon lineage.  

PubMed

Alternative strategies are required when autograft tissue is not sufficient or available to reconstruct damaged tendons. Electrospun fibre yarns could provide such an alternative. This study investigates the seeding of human mesenchymal stem cells (hMSC) on electrospun yarns and their response when subjected to dynamic tensile loading. Cell seeded yarns sustained 3600 cycles per day for 21 days. Loaded yarns demonstrated a thickened cell layer around the scaffold?s exterior compared to statically cultured yarns, which would suggest an increased rate of cell proliferation and/or matrix deposition, whilst maintaining a predominant uniaxial cell orientation. Tensile properties of cell-seeded yarns increased with time compared to acellular yarns. Loaded scaffolds demonstrated an up-regulation in several key tendon genes, including collagen Type I. This study demonstrates the support of hMSCs on electrospun yarns and their differentiation towards a tendon lineage when mechanically stimulated. PMID:25129861

Bosworth, L A; Rathbone, S R; Bradley, R S; Cartmell, S H

2014-11-01

77

Dynamic loading of electrospun yarns guides mesenchymal stem cells towards a tendon lineage  

PubMed Central

Alternative strategies are required when autograft tissue is not sufficient or available to reconstruct damaged tendons. Electrospun fibre yarns could provide such an alternative. This study investigates the seeding of human mesenchymal stem cells (hMSC) on electrospun yarns and their response when subjected to dynamic tensile loading. Cell seeded yarns sustained 3600 cycles per day for 21 days. Loaded yarns demonstrated a thickened cell layer around the scaffold?s exterior compared to statically cultured yarns, which would suggest an increased rate of cell proliferation and/or matrix deposition, whilst maintaining a predominant uniaxial cell orientation. Tensile properties of cell-seeded yarns increased with time compared to acellular yarns. Loaded scaffolds demonstrated an up-regulation in several key tendon genes, including collagen Type I. This study demonstrates the support of hMSCs on electrospun yarns and their differentiation towards a tendon lineage when mechanically stimulated. PMID:25129861

Bosworth, L.A.; Rathbone, S.R.; Bradley, R.S.; Cartmell, S.H.

2014-01-01

78

Differentiation of Human Induced Pluripotent Stem Cells into a Keratinocyte Lineage  

PubMed Central

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

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

2014-01-01

79

Accelerated neuronal differentiation toward motor neuron lineage from human embryonic stem cell line (h9).  

PubMed

Motor neurons loss plays a pivotal role in the pathoetiology of various debilitating diseases such as, but not limited to, amyotrophic lateral sclerosis, primary lateral sclerosis, progressive muscular atrophy, progressive bulbar palsy, pseudobulbar palsy, and spinal muscular atrophy. However, advancement in motor neuron replacement therapy has been significantly constrained by the difficulties in large-scale production at a cost-effective manner. Current methods to derive motor neuron heavily rely on biochemical stimulation, chemical biological screening, and complex physical cues. These existing methods are seriously challenged by extensive time requirements and poor yields. An innovative approach that overcomes prior hurdles and enhances the rate of successful motor neuron transplantation in patients is of critical demand. Iron, a trace element, is indispensable for the normal development and function of the central nervous system. Whether ferric ions promote neuronal differentiation and subsequently promote motor neuron lineage has never been considered. Here, we demonstrate that elevated iron concentration can drastically accelerate the differentiation of human embryonic stem cells (hESCs) toward motor neuron lineage potentially via a transferrin mediated pathway. HB9 expression in 500?nM iron-treated hESCs is approximately twofold higher than the control. Moreover, iron treatment generated more matured and functional motor neuron-like cells that are ?1.5 times more sensitive to depolarization when compared to the control. Our methodology renders an expedited approach to harvest motor neuron-like cells for disease, traumatic injury regeneration, and drug screening. PMID:25036750

Lu, David; Chen, Eric Y T; Lee, Philip; Wang, Yung-Chen; Ching, Wendy; Markey, Christopher; Gulstrom, Chase; Chen, Li-Ching; Nguyen, Thien; Chin, Wei-Chun

2015-03-01

80

Microenvironment Modulates Osteogenic Cell Lineage Commitment in Differentiated Embryonic Stem Cells  

PubMed Central

Background Due to their self-renewal, embryonic stem cells (ESCs) are attractive cells for applications in regenerative medicine and tissue engineering. Although ESC differentiation has been used as a platform for generating bone in vitro and in vivo, the results have been unsatisfactory at best. It is possible that the traditional culture methods, which have been used, are not optimal and that other approaches must be explored. Methodology/Principal Findings ESCs were differentiated into osteoblast lineage using a micro-mass approach. In response to osteogenic differentiation medium, many cells underwent apoptosis, while others left the micro-mass, forming small aggregates in suspension. These aggregates were cultured in three different culture conditions (adhesion, static suspension, and stirred suspension), then examined for osteogenic potential in vitro and in vivo. In adhesion culture, ESCs primed to become osteoblasts recommitted to the adipocyte lineage in vitro. In a static suspension culture, resulting porous aggregates expressed osteoblasts markers and formed bone in vivo via intermembranous ossification. In a stirred suspension culture, resulting non-porous aggregates suppressed osteoblast differentiation in favor of expanding progenitor cells. Conclusions/Significance We demonstrate that microenvironment modulates cell fate and subsequent tissue formation during ESC differentiation. For effective tissue engineering using ESCs, it is important to develop optimized cell culture/differentiation conditions based upon the influence of microenvironment. PMID:20300192

Yamashita, Akihiro; Nishikawa, Sandi; Rancourt, Derrick E.

2010-01-01

81

Lineage-specific regulation of imprinted X inactivation in extraembryonic endoderm stem cells  

PubMed Central

Background Silencing of the paternal X chromosome (Xp), a phenomenon known as imprinted X-chromosome inactivation (I-XCI), characterises, amongst mouse extraembryonic lineages, the primitive endoderm and the extraembryonic endoderm (XEN) stem cells derived from it. Results Using a combination of chromatin immunoprecipitation characterisation of histone modifications and single-cell expression studies, we show that whilst the Xp in XEN cells, like the inactive X chromosome in other cell types, globally accumulates the repressive histone mark H3K27me3, a large number of Xp genes locally lack H3K27me3 and escape from I-XCI. In most cases this escape is specific to the XEN cell lineage. Importantly, the degree of escape and the genes concerned remain unchanged upon XEN conversion into visceral endoderm, suggesting stringent control of I-XCI in XEN derivatives. Surprisingly, chemical inhibition of EZH2, a member of the Polycomb repressive complex 2 (PRC2), and subsequent loss of H3K27me3 on the Xp, do not drastically perturb the pattern of silencing of Xp genes in XEN cells. Conclusions The observations that we report here suggest that the maintenance of gene expression profiles of the inactive Xp in XEN cells involves a tissue-specific mechanism that acts partly independently of PRC2 catalytic activity. PMID:25053977

2014-01-01

82

Mechanical modulation of nascent stem cell lineage commitment in tissue engineering scaffolds.  

PubMed

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 stem 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

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

2013-07-01

83

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

Microsoft Academic Search

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

Nikola Arsic; Daria Mamaeva; Ned J. Lamb; Anne Fernandez

2008-01-01

84

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

PubMed

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

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

2015-03-01

85

Fam40b is required for lineage commitment of murine embryonic stem cells  

PubMed Central

FAM40B (STRIP2) is a member of the striatin-interacting phosphatase and kinase (STRIPAK) complex that is involved in the regulation of various processes such as cell proliferation and differentiation. Its role for differentiation processes in embryonic stem cells (ESCs) is till now completely unknown. Short hairpin RNA (shRNA)-mediated silencing of Fam40b expression in ESCs and differentiating embryoid bodies (EBs) led to perturbed differentiation to embryonic germ layers and their derivatives including a complete abrogation of cardiomyogenesis. Pluripotency factors such as Nanog, Oct4 and Sox2 as well as epigenetic factors such as histone acetyltransferase type B (HAT1) and DNA (cytosine-5)-methyltransferase 3-? (Dnmt3b) were highly upregulated in Fam40b knockdown EBs as compared with control and scrambled EBs. To examine the relevance of Fam40b for development in vivo, Fam40b was knocked down in developing zebrafish. Morpholino-mediated knockdown of Fam40b led to severe abnormalities of the cardiovascular system, including an impaired expression of ventricular myosin heavy chain (vmhc) and of cardiac myosin light chain 2 (cmlc2) in the heart. We identified the gene product of Fam40b in ESCs as a perinuclear and nucleolar protein with a molecular weight of 96?kDa. We conclude that the expression of Fam40b is essential for the lineage commitment of murine embryonic stem cells (mESCs) into differentiated somatic cells via mechanisms involving pluripotency and epigenetic networks. PMID:25010986

Wagh, V; Doss, M X; Sabour, D; Niemann, R; Meganathan, K; Jagtap, S; Gaspar, J A; Ardestani, M A; Papadopoulos, S; Gajewski, M; Winkler, J; Hescheler, J; Sachinidis, A

2014-01-01

86

Dinosaur Journey  

NSDL National Science Digital Library

The Museum of Western Colorado's Dinosaur Journey Museum in Fruita, Colorado is located in the heart of dinosaur country. The Museum features exhibits and information about dinosaurs of western Colorado, eastern Utah and surrounding areas. There are robotic displays of Dilophosaurus, Stegosaurus, Apatosaurus, Triceratops, Utahraptor, T-Rex, and exhibits include real bones plus cast skeletons of Camarasaurus, Camptosaurus, Stegosaurus, Allosaurus, Velociraptor, Othnielia and the rare Mymoorapelta. There is a monthly newsletter available online with information on interpretive hikes and tours, an Extinct Animal of the Month, and the latest information on paleontological finds in the area.

87

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.

88

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

PubMed Central

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

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

2013-01-01

89

Join the Dinosaur Age  

NSDL National Science Digital Library

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.

2014-04-14

90

Matrix elasticity perturbation and Lamin-A/C expression in stem cells modulate their mechanics and lineage specification  

NASA Astrophysics Data System (ADS)

Commitment of stem cells to different lineages is regulated by many cues in their local microenvironment. They are particularly sensitive to the mechanical properties of their extracellular matrix. Nuclear lamins are fibrous proteins providing structural function and transcriptional regulation in the cell nucleus. In particular Lamin A/C levels could influence cellular mechanical sensitivity. Here we show that perturbation of the extracellular matrix and nucleus mechanics can direct stem cells lineage specification. We studied the behavior of human mensechymal stem cells (hMSC) cultured on thin highly ordered collagen nanofilms. To tune the mechanical properties of the nanofilms we used the enzyme transglutaminase as a crosslinking agent. AFM imaging and manipulation is used to examine the nano topography and mechanical properties of the films and cells. Film stiffening affects cells morphology, cytoskeleton organization and their elastic response. hMSCs cultured for two weeks on collagen nanofilms initially tune their stiffness with matrix elasticity but later continuously change it with time. We observed upregulation of osteogenic markers on cross-linked films and increased lamin A/C expression. We show that manipulating Lamin-A/C expression in stem cells also directs cell lineage with knockdown favoring adipogenesis and over expression favoring osteogenesis. We found positive correlation between matrix and nucleus mechanics and that they have a synergistic effect on hMSCs differentiation potential.

Ivanovska, Irena; Discher, Dennis

2012-02-01

91

The origin and early radiation of dinosaurs  

NASA Astrophysics Data System (ADS)

Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and showed no signs of outcompeting their rivals. Instead, the rise of dinosaurs was a two-stage process, as dinosaurs expanded in taxonomic diversity, morphological disparity, and absolute faunal abundance only after the extinction of most crocodile-line reptiles and other groups.

Brusatte, Stephen L.; Nesbitt, Sterling J.; Irmis, Randall B.; Butler, Richard J.; Benton, Michael J.; Norell, Mark A.

2010-07-01

92

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

PubMed

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

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

93

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

PubMed Central

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

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

94

The potential of dental stem cells differentiating into neurogenic cell lineage after cultivation in different modes in vitro.  

PubMed

Trauma or degenerative diseases of the central nervous system (CNS) cause the loss of neurons or glial cells. Stem cell transplantation has become a vital strategy for CNS regeneration. It is necessary to effectively induce nonneurogenic stem cells to differentiate into neurogenic cell lineages because of the limited source of neurogenic stem cells, relatively difficult cultivation, and ethical issues. Previous studies have found that dental stem cells can be used for transplantation therapy. The aim of this study was to explore a better inductive mode and time point for dental stem cells to differentiate into neural-like cells and evaluate a better candidate cell. In this study, dental follicle stem cells (DFSCs), dental papilla stem cells (DPSCs), and stem cells from apical papilla (SCAPs) were cultivated in five different modes. The proliferation ability, morphology, and expression of neural marker genes were analyzed. Results showed that DFSCs showed a higher proliferation potential. The proliferation was decreased after cultivation in chemical inductive medium as cultivation modes 3 and 5. The cells could present neural-like cell morphology after cultivation with human epidermal growth factor (EGF) and fibroblast growth factor-basic (bFGF) as cultivation modes 4 and 5. The vast majority of DFSCs gene expression levels in mode 4 on the third day was upregulated significantly. In conclusion, our data suggested that different dental stem cells exhibited different neural differentiation potentials. DFSCs might be the better candidate cell type. Furthermore, cultivation mode 4 and timing of the third day may promote differentiation into neurogenic cell lineages more effectively before transplantation to treat neurological diseases. PMID:25072651

Yang, Chao; Sun, Liang; Li, Xinghan; Xie, Li; Yu, Mei; Feng, Lian; Jiang, Zongting; Guo, Weihua; Tian, Weidong

2014-10-01

95

Blood-borne stem cells differentiate into vascular and cardiac lineages during normal development.  

PubMed

Recent investigations have indicated that hematopoietic stem cells (HSCs) have the potential to differentiate into multiple non-blood cell lineages and contribute to the cellular regeneration of various tissues and multiple organs. Most studies to date on HSC potential have examined the adult, focusing on their potential to repair tissue under pathological conditions (e.g., ischemic injury, organ failure). Comparatively little is known about the physiological role of HSCs in normal tissue homeostasis in the adult, and even less of their contribution to organogenesis during prenatal development. This study reports the contribution of blood-borne cells to various organ systems of the developing embryo using a quail-chick parabiosis model. Under these conditions, the developing circulatory systems fuse between ED6-ED8, resulting in free exchange of circulating cells. Cells of quail origin, identified by quail-specific antibodies at ED15, were found in numerous organs of the parabiotic chick embryo. Circulating cells contributed to developing vasculature, where they differentiated into endothelial, smooth muscle, and adventitial tissues. In the heart, differentiation of circulating cells into cardiomyocytes was demonstrated using double immunolabeling for QCPN and sarcomeric actin or myosin. These results were confirmed by intramyocardial injection of quail bone marrow cells that were found to express markers of myocytes, coronary smooth muscle, and epicardium. Experiments using lacZ-transgenic chick embryos for a second positive cellular marker showed that fusion between chick and quail cells was a rare event. These results suggest that during development, multipotent cells are present in the embryonic circulation and home into different organs where they undergo tissue-specific differentiation. Moreover, the demonstration that blood-borne cells contribute to the development of various organs lends credence to claims that hematopoietic stem cells have utility for treating diseased or damaged tissues in the adult. PMID:16522159

Zhang, Ning; Mustin, Deanna; Reardon, Wade; Almeida, Angela De; Mozdziak, Paul; Mrug, Michal; Eisenberg, Leonard M; Sedmera, David

2006-02-01

96

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

PubMed

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

Lee, I-Chi; Wu, Yu-Chieh

2014-09-01

97

Aging-like Phenotype and Defective Lineage Specification in SIRT1-Deleted Hematopoietic Stem and Progenitor Cells  

PubMed Central

Summary Aging hematopoietic stem cells (HSCs) exhibit defective lineage specification that is thought to be central to increased incidence of myeloid malignancies and compromised immune competence in the elderly. Mechanisms underlying these age-related defects remain largely unknown. We show that the deacetylase Sirtuin (SIRT)1 is required for homeostatic HSC maintenance. Differentiation of young SIRT1-deleted HSCs is skewed toward myeloid lineage associated with a significant decline in the lymphoid compartment, anemia, and altered expression of associated genes. Combined with HSC accumulation of damaged DNA and expression patterns of age-linked molecules, these have striking overlaps with aged HSCs. We further show that SIRT1 controls HSC homeostasis via the longevity transcription factor FOXO3. These findings suggest that SIRT1 is essential for HSC homeostasis and lineage specification. They also indicate that SIRT1 might contribute to delaying HSC aging. PMID:25068121

Rimmelé, Pauline; Bigarella, Carolina L.; Liang, Raymond; Izac, Brigitte; Dieguez-Gonzalez, Rebeca; Barbet, Gaetan; Donovan, Michael; Brugnara, Carlo; Blander, Julie M.; Sinclair, David A.; Ghaffari, Saghi

2014-01-01

98

Dinosaur Impressions  

NASA Astrophysics Data System (ADS)

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).

Taquet, Philippe

1998-09-01

99

Life Cycle and Morphology of a Cambrian Stem-Lineage Loriciferan  

PubMed Central

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

Peel, John S.; Stein, Martin; Kristensen, Reinhardt Møbjerg

2013-01-01

100

Dinosaurs 1: Where Are the Dinosaurs ?  

NSDL National Science Digital Library

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.

Science Netlinks

2003-04-15

101

Discovering Dinosaurs  

NSDL National Science Digital Library

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.

Steve Allison-Bunnell

102

Elimination of tumorigenic stem cells from differentiated progeny and selection of definitive endoderm reveals a Pdx1 + foregut endoderm stem cell lineage  

Microsoft Academic Search

Embryonic stem cell (ESC) derivatives offer promise for generating clinically useful tissues for transplantation, yet the specter of producing tumors in patients remains a significant concern. We have developed a simple method that eliminates the tumorigenic potential from differentiated ESC cultures of murine and human origin while purifying lineage-restricted, definitive endoderm-committed cells. A three-stage scheme utilizing magnetic bead sorting and

Brenda Kahan; Joseph Magliocca; Fabiola Merriam; Nathan Treff; Melisa Budde; Jeffrey Nelson; Victoria Browning; Benjamin Ziehr; Jon Odorico

2011-01-01

103

Dinosauric demise  

NASA Astrophysics Data System (ADS)

For more than a decade, many scientists have theorized that the disappearance of the dinosaurs may be due to the collision of a huge asteroid with Earth 65 mya. However, many gaps have persisted in the theory. Now NASA scientists offer a detailed explanation of how the impact may have led to the extinction of the dinosaur. In a recent issue of Earth and Planetary Science Letters, a team of scientists from the Jet Propulsion Laboratory's Earth and Space Sciences Division in Pasadena, Calif., write that the location of the impact was key.

104

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.

105

Adult Thymus Contains FoxN1? Epithelial Stem Cells that Are Bipotent for Medullary and Cortical Thymic Epithelial Lineages  

PubMed Central

Summary Within the thymus, two major thymic epithelial cell (TEC) subsets—cortical and medullary TECs—provide unique structural and functional niches for T cell development and establishment of central tolerance. Both lineages are believed to originate from a common progenitor cell, yet the cellular and molecular identity of these bipotent TEC progenitors/stem cells remains ill defined. Here we identify rare stromal cells in the murine adult thymus, which under low-attachment conditions formed spheres (termed “thymospheres”). These thymosphere-forming cells (TSFCs) displayed the stemness features of being slow cycling, self-renewing, and bipotent. TSFCs could be significantly enriched based on their distinct surface antigen phenotype. The FoxN1 transcription factor was dispensable for TSFCs maintenance in situ and for commitment to the medullary and cortical TEC lineages. In summary, this study presents the characterization of the adult thymic epithelial stem cells and demonstrates the dispensability of FoxN1 function for their stemness. PMID:25148026

Ucar, Ahmet; Ucar, Olga; Klug, Paula; Matt, Sonja; Brunk, Fabian; Hofmann, Thomas G.; Kyewski, Bruno

2014-01-01

106

Adult thymus contains FoxN1(-) epithelial stem cells that are bipotent for medullary and cortical thymic epithelial lineages.  

PubMed

Within the thymus, two major thymic epithelial cell (TEC) subsets-cortical and medullary TECs-provide unique structural and functional niches for T cell development and establishment of central tolerance. Both lineages are believed to originate from a common progenitor cell, yet the cellular and molecular identity of these bipotent TEC progenitors/stem cells remains ill defined. Here we identify rare stromal cells in the murine adult thymus, which under low-attachment conditions formed spheres (termed "thymospheres"). These thymosphere-forming cells (TSFCs) displayed the stemness features of being slow cycling, self-renewing, and bipotent. TSFCs could be significantly enriched based on their distinct surface antigen phenotype. The FoxN1 transcription factor was dispensable for TSFCs maintenance in situ and for commitment to the medullary and cortical TEC lineages. In summary, this study presents the characterization of the adult thymic epithelial stem cells and demonstrates the dispensability of FoxN1 function for their stemness. PMID:25148026

Ucar, Ahmet; Ucar, Olga; Klug, Paula; Matt, Sonja; Brunk, Fabian; Hofmann, Thomas G; Kyewski, Bruno

2014-08-21

107

Dinosaur evolution. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales.  

PubMed

Middle Jurassic to Early Cretaceous deposits from northeastern China have yielded varied theropod dinosaurs bearing feathers. Filamentous integumentary structures have also been described in ornithischian dinosaurs, but whether these filaments can be regarded as part of the evolutionary lineage toward feathers remains controversial. Here we describe a new basal neornithischian dinosaur from the Jurassic of Siberia with small scales around the distal hindlimb, larger imbricated scales around the tail, monofilaments around the head and the thorax, and more complex featherlike structures around the humerus, the femur, and the tibia. The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs. PMID:25061209

Godefroit, Pascal; Sinitsa, Sofia M; Dhouailly, Danielle; Bolotsky, Yuri L; Sizov, Alexander V; McNamara, Maria E; Benton, Michael J; Spagna, Paul

2014-07-25

108

Dinosaur Illustrations  

NSDL National Science Digital Library

These twelve dark-line dinosaur drawings can be used as either a research or coloring activity. Overhead transparencies of the drawings can be projected to make large traced images of the animals. The site includes drawings of Ankylosaurus, Barosaurus, Coelophysis, Diplodocus, Iguanodon, Ornithomimus, Pachycephalosaurus, Parasaurolophus, Plateosaurus, Stegosaurus, Triceratops, and Tyrannosaurus rex.

109

Dinosaur Dig  

NSDL National Science Digital Library

This is an activity about dinosaurs, fossils, and the work of paleontologists. Learners use hand tools (paint brushes, scoops, and sifters) to unearth fossil specimens in tubs of birdseed. This resource includes definitions of fossils and paleontologists as well as discussion questions to further learning.

OMSI

2004-01-01

110

Dinosaur Dioramas.  

ERIC Educational Resources Information Center

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)

Scheinkman, Nancy

2001-01-01

111

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

PubMed

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

Matos, Juliana L; Bergmann, Dominique C

2014-01-01

112

Make a Dinosaur  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

113

Synaptically-competent neurons derived from canine embryonic stem cells by lineage selection with EGF and Noggin.  

PubMed

Pluripotent stem cell lines have been generated in several domestic animal species; however, these lines traditionally show poor self-renewal and differentiation. Using canine embryonic stem cell (cESC) lines previously shown to have sufficient self-renewal capacity and potency, we generated and compared canine neural stem cell (cNSC) lines derived by lineage selection with epidermal growth factor (EGF) or Noggin along the neural default differentiation pathway, or by directed differentiation with retinoic acid (RA)-induced floating sphere assay. Lineage selection produced large populations of SOX2+ neural stem/progenitor cell populations and neuronal derivatives while directed differentiation produced few and improper neuronal derivatives. Primary canine neural lines were generated from fetal tissue and used as a positive control for differentiation and electrophysiology. Differentiation of EGF- and Noggin-directed cNSC lines in N2B27 with low-dose growth factors (BDNF/NT-3 or PDGF??) produced phenotypes equivalent to primary canine neural cells including 3CB2+ radial progenitors, MOSP+ glia restricted precursors, VIM+/GFAP+ astrocytes, and TUBB3+/MAP2+/NFH+/SYN+ neurons. Conversely, induction with RA and neuronal differentiation produced inadequate putative neurons for further study, even though appropriate neuronal gene expression profiles were observed by RT-PCR (including Nestin, TUBB3, PSD95, STX1A, SYNPR, MAP2). Co-culture of cESC-derived neurons with primary canine fetal cells on canine astrocytes was used to test functional maturity of putative neurons. Canine ESC-derived neurons received functional GABA(A)- and AMPA-receptor mediated synaptic input, but only when co-cultured with primary neurons. This study presents established neural stem/progenitor cell populations and functional neural derivatives in the dog, providing the proof-of-concept required to translate stem cell transplantation strategies into a clinically relevant animal model. PMID:21611190

Wilcox, Jared T; Lai, Jonathan K Y; Semple, Esther; Brisson, Brigitte A; Gartley, Cathy; Armstrong, John N; Betts, Dean H

2011-01-01

114

Dinosaur Flesh and Bones  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

115

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

SciTech Connect

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.

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

116

All-trans retinoic acid and basic fibroblast growth factor synergistically direct pluripotent human embryonic stem cells to extraembryonic lineages.  

PubMed

Human embryonic stem cells (hESCs) can be used to model the cellular and molecular mechanisms that underlie embryonic development. Understanding the cellular mechanisms and pathways involved in extraembryonic (ExE) differentiation is of great interest because of the important role of this process in maternal health and fertility. Fibroblast growth factor 2 (FGF-2) is widely used to maintain the self-renewal of hESCs and induced pluripotent stem cells, while all trans retinoic acid (RA) is used to facilitate the directed differentiation of hESCs. Here, we monitored the RA induced differentiation of hESCs to the ExE lineage with and without FGF-2 over a 7-day period via global transcriptional profiling. The stemness markers POU5F1, NANOG and TDGF1 were markedly downregulated, whereas an upregulation of the ExE markers KRT7, CGA, DDAH2 and IGFBP3 was observed. Many of the differentially expressed genes were involved in WNT and TGF-? signaling. RA inactivated WNT signaling even in the presence of exogenous FGF-2, which that promotes the maintenance of the pluripotent state. We also show that BMP4 was upregulated and that RA was able to modulate the TGF-? signaling pathway and direct hESCs toward the ExE lineage. In addition, an epigenetic study revealed hypermethylation of the DDAH2, TDGF1 and GATA3 gene promoters, suggesting a role for epigenetic regulation during ExE differentiation. These data reveals that the effect of RA prevails in the presence of exogenous FGF-2 thus resulting in the direction of hESCs toward the ExE lineage. PMID:23314291

Jagtap, Smita; Meganathan, Kesavan; Wagh, Vilas; Natarajan, Karthick; Hescheler, Jürgen; Sachinidis, Agapios

2013-03-01

117

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

PubMed

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

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

2012-10-01

118

Feathered Dinosaurs  

NASA Astrophysics Data System (ADS)

Recent fossil discoveries from Early Cretaceous rocks of Liaoning Province, China, have provided a wealth of spectacular specimens. Included in these are the remains of several different kinds of small theropod dinosaurs, many of which are extremely closely related to modern birds. Unique preservation conditions allowed soft tissues of some of these specimens to be preserved. Many dinosaur specimens that preserve feathers and other types of integumentary coverings have been recovered. These fossils show a progression of integumentary types from simple fibers to feathers of modern aspect. The distribution of these features on the bodies of these animals is surprising in that some show large tail plumes, whereas others show the presence of wing-like structures on both fore and hind limbs. The phylogenetic distribution of feather types is highly congruent with models of feather evolution developed from developmental biology.

Norell, Mark A.; Xu, Xing

2005-01-01

119

Transcriptomic and phenotypic analysis of murine embryonic stem cell derived BMP2 + lineage cells: an insight into mesodermal patterning  

Microsoft Academic Search

Background  Bone morphogenetic protein (BMP)2 is a late mesodermal marker expressed during vertebrate development and plays a crucial\\u000a role in early embryonic development. The nature of the BMP2-expressing cells during the early stages of embryonic development,\\u000a their transcriptome and cell phenotypes developed from these cells have not yet been characterized.\\u000a \\u000a \\u000a \\u000a \\u000a Results  We generated a transgenic BMP2 embryonic stem (ES) cell lineage expressing

Michael Xavier Doss; Shuhua Chen; Johannes Winkler; Rita Hippler-Altenburg; Margareta Odenthal; Claudia Wickenhauser; Sridevi Balaraman; Herbert Schulz; Oliver Hummel; Norbert Hübner; Nandini Ghosh-Choudhury; Isaia Sotiriadou; Jürgen Hescheler; Agapios Sachinidis

2007-01-01

120

Lineage Switching in Acute Leukemias: A Consequence of Stem Cell Plasticity?  

PubMed Central

Acute leukemias are the most common cancer in childhood and characterized by the uncontrolled production of hematopoietic precursor cells of the lymphoid or myeloid series within the bone marrow. Even when a relatively high efficiency of therapeutic agents has increased the overall survival rates in the last years, factors such as cell lineage switching and the rise of mixed lineages at relapses often change the prognosis of the illness. During lineage switching, conversions from lymphoblastic leukemia to myeloid leukemia, or vice versa, are recorded. The central mechanisms involved in these phenomena remain undefined, but recent studies suggest that lineage commitment of plastic hematopoietic progenitors may be multidirectional and reversible upon specific signals provided by both intrinsic and environmental cues. In this paper, we focus on the current knowledge about cell heterogeneity and the lineage switch resulting from leukemic cells plasticity. A number of hypothetical mechanisms that may inspire changes in cell fate decisions are highlighted. Understanding the plasticity of leukemia initiating cells might be fundamental to unravel the pathogenesis of lineage switch in acute leukemias and will illuminate the importance of a flexible hematopoietic development. PMID:22852088

Dorantes-Acosta, Elisa; Pelayo, Rosana

2012-01-01

121

Dinosaur biomechanics.  

PubMed

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

Alexander, R McNeill

2006-08-01

122

Dinosaur taphonomy  

NSDL National Science Digital Library

In preparation for this assignment, students have read a brief section in their textbook on the fossilization process as it relates to dinosaurs. In addition they will have had one lecture on taphonomy that briefly covers the processes that transpire from the death of a dinosaur until its discovery by a paleontologist. Students work in groups. Each group is given a quarry map of a dinosaur locality and no other information. The exercise is framed as detecive work, where the "scene of the crime" is represented by the quarry map. The objective is to gather clues to make an informed intepretation. Students can obtain additional clues, but to do so, they must formulate a hypothesis that can be tested by the information they seek. However, they only get to formulate 10 hypotheses. An untestable hypothesis wastes a potential clue. Once students have gathered all their clues, they are encouraged to discuss the significance. Students write up their own interpretation and its limitations individually. The exercise gives students practice with taphonomic data and both its potential and limitations; hypothesis formulation; and examining differing viewpoints as group discussions often lead to debates about what information would be most important.

David Varricchio

123

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.

124

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.

125

Dinosaur Books for Educators  

NSDL National Science Digital Library

This dinosaur reference list has 18 books that are recommended for learning more about Dinosaurs. The author, publisher, and publishing date are given for each title. The list includes encyclopedias of dinosaurs, real-life tales of fossil hunts, hands-on activities for students, and an examination of the link between birds and dinosaurs.

126

TECHNICAL RESPONSE DINOSAUR EVOLUTION  

E-print Network

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

Benton, Michael

127

Environmental signals regulate lineage choice and temporal maturation of neural stem cells from human embryonic stem cells  

Microsoft Academic Search

Human embryonic stem cells (hESCs) are a potential source of defined tissue for cell-based therapies in regenerative neurology. In order for this potential to be realized, there is a need for the evaluation of the behaviour of human embryonic stem cell-derived neural stem cells (hES-NSCs) both in the normal and the injured CNS. Using normal tissue and two experimental models,

Alexis J. Joannides; Daniel J. Webber; Olivier Raineteau; Claire Kelly; Karen-Amanda Irvine; Colin Watts; Anne E. Rosser; Paul J. Kemp; William F. Blakemore; Alastair Compston; Maeve A. Caldwell; Nicholas D. Allen; Siddharthan Chandran

2007-01-01

128

Pluripotent lineage of CD133 stem cells isolated from human skin samples.  

PubMed

Skin stem cells are very important in cosmetics, pharmacological and regenerative medicine and burn cases. Foreskin samples surgically removed after circumcision from boys below 7 years were collected and primary epidermal cells were prepared by enzymatic and mechanical tituration method. Selecting CD133 (prominin-1) multipotent stem cell marker, enriched stem cells were analyzed by MACS using CD133 antibodies conjugated with magnetic beads. CD133 positive and negative cells with specific skin stem cells markers like - CD34 (Universal stem cells marker), CD29 (integrin beta-1) and CD49f (integrin alpha-6) immunophenotypes were screened and sorted in flowcytometer. Further the expression of four embryonic genes or transcription factors of pluripotent stem cells were analyzed for pluripotent character of sorted cells. It was found that skin stem cell markers associated with CD133 cells, differentially expressed CD34, CD29 and CD49f immunophenotyes on both positive and negative CD133 cells in FACS analysis. The embryonic stem cell markers (induced pluripotent stem cell markers) like Oct4, SOX2, Notch-2 and K19 genes were expressed in CD133 positive epidermal cells. It is therefore evident that foreskin derived epidermal stem cells showed pluripotent or multipotent nature. This finding opens up avenues for new uses of these stem cells for direct cell seeding in wound healing, surgical suturing and drug screening. PMID:23923603

Balaji, Avvari Bhaskara; Jamil, Kaiser; Ram, Gangaraju Maruthi; Raju, G Suryanarayana

2013-02-01

129

The Ornithischian Dinosaurs  

NSDL National Science Digital Library

This site introduces a group of dinosaurs called ornithischians. There were many kinds of ornithischian dinosaurs dating back to the early Jurassic. The Ornithopoda included the hadrosaurs (duck-billed dinosaurs), the iguanodontids, the heterodontosaurs, the hypsilophodontids, and various others. The Ceratopsia included the horned dinosaurs, while the Ankylosauria and Stegosauria (now usually grouped together in the Thyreophora) included various types of armored dinosaurs. The Pachycephalosauria included the extremely thick-skulled pachycephalosaurs.

130

Make a Dinosaur Model  

NSDL National Science Digital Library

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.

2014-04-14

131

X-ray Dinosaurs  

NSDL National Science Digital Library

In this activity, learners explore dinosaur fossils and skeletons. First, learners listen to "Tyrannosaurus Rex" by Daniel Cohen to learn about T. rex dinosaurs specifically. Then, learners make dinosaur tracings and drawings similar to x-rays. Learners can repeat the activity using pictures of other dinosaurs to compare and contrast various dinosaurs. This activity is featured on page 38 of the "Dinosphere" unit of study for K-2 learners.

2014-04-14

132

Boundary cap cells are peripheral nervous system stem cells that can be redirected into central nervous system lineages  

PubMed Central

Boundary cap cells (BC), which express the transcription factor Krox20, participate in the formation of the boundary between the central nervous system and the peripheral nervous system. To study BC stemness, we developed a method to purify and amplify BC in vitro from Krox20Cre/+, R26RYFP/+ mouse embryos. We show that BC progeny are EGF/FGF2-responsive, form spheres, and express neural crest markers. Upon growth factor withdrawal, BC progeny gave rise to multiple neural crest and CNS lineages. Transplanted into the developing murine forebrain, they successfully survived, migrated, and integrated within the host environment. Surprisingly, BC progeny generated exclusively CNS cells, including neurons, astrocytes, and myelin-forming oligodendrocytes. In vitro experiments indicated that a sequential combination of ventralizing morphogens and glial growth factors was necessary to reprogram BC into oligodendrocytes. Thus, BC progeny are endowed with differentiation plasticity beyond the peripheral nervous system. The demonstration that CNS developmental cues can reprogram neural crest-derived stem cells into CNS derivatives suggests that BC could serve as a source of cell type-specific lineages, including oligodendrocytes, for cell-based therapies to treat CNS disorders. PMID:21670295

Zujovic, Violetta; Thibaud, Julie; Bachelin, Corinne; Vidal, Marie; Deboux, Cyrille; Coulpier, Fanny; Stadler, Nicolas; Charnay, Patrick; Topilko, Piotr; Baron-Van Evercooren, Anne

2011-01-01

133

Induction of multipotential hematopoietic progenitors from human pluripotent stem cells via re-specification of lineage-restricted precursors  

PubMed Central

Summary Human pluripotent stem cells (hPSCs) represent a promising source of patient-specific cells for disease modeling, drug screens, and cellular therapies. However, the inability to derive engraftable human hematopoietic stem and progenitor (HSPCs) has limited their characterization to in vitro assays. We report a strategy to re-specify lineage-restricted CD34+CD45+ myeloid precursors derived from hPSCs into multilineage progenitors that can be expanded in vitro and engraft in vivo. HOXA9, ERG, and RORA conferred self-renewal and multilineage potential in vitro and maintained primitive CD34+CD38? cells. Screening cells via transplantation revealed that two additional factors, SOX4 and MYB, were required for engraftment. Progenitors specified with all five factors gave rise to reproducible short-term engraftment with myeloid and erythroid lineages. Erythroid precursors underwent hemoglobin switching in vivo, silencing embryonic and activating adult globin expression. Our combinatorial screening approach establishes a strategy for obtaining transcription factor-mediated engraftment of blood progenitors from human pluripotent cells. PMID:24094326

Doulatov, Sergei; Vo, Linda T.; Chou, Stephanie S.; Kim, Peter G.; Arora, Natasha; Li, Hu; Hadland, Brandon K.; Bernstein, Irwin D.; Collins, James J.; Zon, Leonard I.; Daley, George Q.

2013-01-01

134

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

PubMed

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

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

2015-03-01

135

Reversible lineage-specific priming of human embryonic stem cells can be exploited to optimize the yield of differentiated cells.  

PubMed

The clinical use of human embryonic stem cells (hESCs) requires efficient cellular expansion that must be paired with an ability to generate specialized progeny through differentiation. Self-renewal and differentiation are deemed inherent hallmarks of hESCs and a growing body of evidence suggests that initial culture conditions dictate these two aspects of hESC behavior. Here, we reveal that defined culture conditions using commercial mTeSR1 media augment the expansion of hESCs and enhance their capacity for neural differentiation at the expense of hematopoietic lineage competency without affecting pluripotency. This culture-induced modification was shown to be reversible, as culture in mouse embryonic fibroblast-conditioned media (MEF-CM) in subsequent passages allowed mTeSR1-expanded hESCs to re-establish hematopoietic differentiation potential. Optimal yield of hematopoietic cells can be achieved by expansion in mTeSR1 followed by a recovery period in MEF-CM. Furthermore, the lineage propensity to hematopoietic and neural cell types could be predicted via analysis of surrogate markers expressed by hESCs cultured in mTeSR1 versus MEF-CM, thereby circumventing laborious in vitro differentiation assays. Our study reveals that hESCs exist in a range of functional states and balance expansion with differentiation potential, which can be modulated by culture conditions in a predictive and quantitative manner. Stem Cells 2015;33:1142-1152. PMID:25639500

Lee, Jung Bok; Graham, Monica; Collins, Tony J; Lee, Jong-Hee; Hong, Seok-Ho; Mcnicol, Amie Jamie; Shapovalova, Zoya; Bhatia, Mickie

2015-04-01

136

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

PubMed

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

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

2015-04-01

137

Dinosaur Breath  

NSDL National Science Digital Library

This simple demonstration is about the role of dinosaurs in the carbon cycle and the eventual storage of excess carbon in the form of chalk. Students will come to understand the importance of the carbon cycle, appreciate that it has always been essential for life on earth, and appreciate the role of the oceans as a carbon sink. The instructor guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.

138

Dinosaur Breath  

NSDL National Science Digital Library

Through discussion and hands-on experimentation, students learn about the geological (ancient) carbon cycle. They investigate the role of dinosaurs in the carbon cycle and the eventual storage of carbon in the form of chalk. Students discover how the carbon cycle has been occurring for millions of years and is necessary for life on Earth. Finally, they may extend their knowledge to the concept of global warming and how engineers are working to understand the carbon cycle and reduce harmful CO2 emissions.

Integrated Teaching and Learning Program,

139

Discovering Dinosaurs  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades K-5. It focuses on how scientists have developed theories about what dinosaurs were like by using evidence that they have found. Students work in groups and as a class to discover what a theory is and how it is supported or disproven. Included are 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.

William McDonald

140

The cardiomyocyte lineage is critical for optimization of stem cell therapy in a mouse model of myocardial infarction.  

PubMed

We recently described a murine embryonic stem cell (ESC) line engineered to express the activated Notch 4 receptor in a tetracycline (doxcycline; Dox) regulated fashion (tet-notch4 ESCs). Notch 4 induction in Flk1(+) hematopoietic and vascular progenitors from this line respecified them to a cardiovascular fate. We reasoned that these cells would be ideal for evaluating the contribution of the cardiomyocyte and vascular lineages to the functional improvement noted following stem cell transplantation in infarcted hearts. Flk-1(+) Tet-notch4 cells from d 3 embryoid bodies exposed to doxycycline (Dox(+)) were compared to uninduced (Dox(-)) Flk-1(+) cells. Mice underwent transplantation of 5 x 10(5) Dox(+) cells, Dox(-)cells, or an equal volume of serum-free medium after surgically induced myocardial infarction. The mean ejection fraction was 59 + or - 15, 46 + or - 17, and 39 + or - 13% in the Dox(+), Dox(-), and serum-free medium groups, respectively (P<0.05 for the differences among all 3 groups). Immunohistochemistry of hearts injected with Dox(+) grafts expressed myocardial and vascular markers, whereas grafts of Dox(-) cells expressed primarily vascular markers. We conclude that cardiovascular progenitors are more effective than vascular progenitors in improving function after myocardial infarction. The transplantation of appropriate cell types is critical for maximizing the benefit of cardiovascular cell therapy.-Adler, E. D., Chen, V. C., Bystrup, A., Kaplan, A. D., Giovannone, S., Briley-Saebo, K., Young, W., Kattman, S., Mani, V., Laflamme, M., Zhu, W.-Z., Fayad, Z., Keller, G. The cardiomyocyte lineage is critical for optimization of stem cell therapy in a mouse model of myocardial infarction. PMID:19940262

Adler, Eric D; Chen, Vincent C; Bystrup, Anne; Kaplan, Aaron D; Giovannone, Steven; Briley-Saebo, Karen; Young, Wilson; Kattman, Steve; Mani, Venkatesh; Laflamme, Michael; Zhu, Wei-Zhong; Fayad, Zahi; Keller, Gordon

2010-04-01

141

The cardiomyocyte lineage is critical for optimization of stem cell therapy in a mouse model of myocardial infarction  

PubMed Central

We recently described a murine embryonic stem cell (ESC) line engineered to express the activated Notch 4 receptor in a tetracycline (doxcycline; Dox) regulated fashion (tet-notch4 ESCs). Notch 4 induction in Flk1+ hematopoietic and vascular progenitors from this line respecified them to a cardiovascular fate. We reasoned that these cells would be ideal for evaluating the contribution of the cardiomyocyte and vascular lineages to the functional improvement noted following stem cell transplantation in infarcted hearts. Flk-1+ Tet-notch4 cells from d 3 embryoid bodies exposed to doxycycline (Dox+) were compared to uninduced (Dox?) Flk-1+ cells. Mice underwent transplantation of 5 × 105 Dox+ cells, Dox?cells, or an equal volume of serum-free medium after surgically induced myocardial infarction. The mean ejection fraction was 59 ± 15, 46 ± 17, and 39 ± 13% in the Dox+, Dox?, and serum-free medium groups, respectively (P<0.05 for the differences among all 3 groups). Immunohistochemistry of hearts injected with Dox+ grafts expressed myocardial and vascular markers, whereas grafts of Dox? cells expressed primarily vascular markers. We conclude that cardiovascular progenitors are more effective than vascular progenitors in improving function after myocardial infarction. The transplantation of appropriate cell types is critical for maximizing the benefit of cardiovascular cell therapy.—Adler, E. D., Chen, V. C., Bystrup, A., Kaplan, A. D., Giovannone, S., Briley-Saebo, K., Young, W., Kattman, S., Mani, V., Laflamme, M., Zhu, W.-Z., Fayad, Z., Keller, G. The cardiomyocyte lineage is critical for optimization of stem cell therapy in a mouse model of myocardial infarction. PMID:19940262

Adler, Eric D.; Chen, Vincent C.; Bystrup, Anne; Kaplan, Aaron D.; Giovannone, Steven; Briley-Saebo, Karen; Young, Wilson; Kattman, Steve; Mani, Venkatesh; Laflamme, Michael; Zhu, Wei-Zhong; Fayad, Zahi; Keller, Gordon

2010-01-01

142

mTORC2 regulates mechanically induced cytoskeletal reorganization and lineage selection in marrow derived mesenchymal stem cells  

PubMed Central

The cell cytoskeleton interprets and responds to physical cues from the microenvironment. Applying mechanical force to mesenchymal stem cells induces formation of a stiffer cytoskeleton, which biases against adipogenic differentiation and toward osteoblastogenesis. mTORC2, the mTOR complex defined by its binding partner rictor, is implicated in resting cytoskeletal architecture and is activated by mechanical force. We asked if mTORC2 played a role in mechanical adaptation of the cytoskeleton. We found that during bi-axial strain induced cytoskeletal restructuring, mTORC2 and Akt co-localize with newly assembled focal adhesions (FA). Disrupting the function of mTORC2, or that of its downstream substrate Akt, prevented mechanically-induced F-actin stress fiber development. mTORC2 becomes associated with vinculin during strain, and knock-down of vinculin prevents mTORC2 activation. In contrast, mTORC2 is not recruited to the FA complex during its activation by insulin, nor does insulin alter cytoskeletal structure. Further, when rictor was knocked down, the ability of MSC to enter the osteoblastic lineage was reduced, and when cultured in adipogenic medium, rictor-deficient MSC showed accelerated adipogenesis. This indicated that cytoskeletal remodeling promotes osteogenesis over adipogenesis. In sum, our data show that mTORC2 is involved in stem cell responses to biophysical stimuli, regulating both signaling and cytoskeletal reorganization. As such, mechanical activation of mTORC2 signaling participates in mesenchymal stem cell lineage selection, preventing adipogenesis by preserving ?-catenin and stimulating osteogenesis by generating a stiffer cytoskeleton. PMID:23821483

Sen, Buer; Xie, Zhihui; Case, Natasha; Thompson, William R.; Uzer, Gunes; Styner, Maya; Rubin, Janet

2013-01-01

143

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

E-print Network

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 ...

Cassady, John P.

144

A Computational Model for Understanding Stem Cell, Trophectoderm and Endoderm Lineage Determination  

E-print Network

of Theoretical Physics, Lund University, Lund, Sweden, 3 Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, Lund University, Lund, Sweden Abstract Background: Recent studies have associated

Peterson, Carsten

145

Micropatterning of human embryonic stem cells dissects the mesoderm and endoderm lineages  

Microsoft Academic Search

Human pluripotent cells such as human embryonic stem cells (hESC) are a great potential source of cells for cell-based therapies; however, directing their differentiation into the desired cell types with high purity remains a challenge. The stem cell microenvironment plays a vital role in directing hESC fate and we have previously shown that manipulation of colony size in a serum-

Lawrence Haoran Lee; Raheem Peerani; Mark Ungrin; Chirag Joshi; Eugenia Kumacheva; Peter W. Zandstra

2009-01-01

146

Identification of a putative intestinal stem cell and early lineage marker; musashi-1  

Microsoft Academic Search

There are few reliable markers for adult stem cells and none for those of the intestinal epithelium. Previously, indirect experimental approaches have predicted stem cell position and numbers. The Musashi-1 (Msi-1) gene encodes an RNA binding protein associated with asymmetric divisions in neural progenitor cells. Two-day-old, adult, and 4.5 h, 1-, 2-, 4- and 12-day post-irradiation samples of BDF1 mouse

Christopher S. Potten; Catherine Booth; Gregory L. Tudor; Dawn Booth; Gerard Brady; Patricia Hurley; Gary Ashton; Robert Clarke; Shin-ichi Sakakibara; Hideyuki Okano

2003-01-01

147

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.

148

The histone H2A deubiquitinase Usp16 regulates embryonic stem cell gene expression and lineage commitment  

PubMed Central

Polycomb Repressive Complex 1 and histone H2A ubiquitination (ubH2A) contribute to embryonic stem cell (ESC) pluripotency by repressing lineage-specific gene expression. However, whether active deubiquitination co-regulates ubH2A levels in ESCs and during differentiation is not known. Here we report that Usp16, a histone H2A deubiquitinase, regulates H2A deubiquitination and gene expression in ESCs, and importantly, is required for ESC differentiation. Usp16 knockout is embryonic lethal in mice, but does not affect ESC viability or identity. Usp16 binds to the promoter regions of a large number of genes in ESCs, and Usp16 binding is inversely correlated with ubH2A levels, and positively correlates with gene expression levels. Intriguingly, Usp16?/? ESCs fail to differentiate due to ubH2A-mediated repression of lineage-specific genes. Finally, Usp16, but not a catalytically inactive mutant, rescues the differentiation defects of Usp16?/? ESCs. Therefore, this study identifies Usp16 and H2A deubiquitination as critical regulators of ESC gene expression and differentiation. PMID:24784029

Yang, Wei; Lee, Yun-Hwa; Jones, Amanda E.; Woolnough, Jessica L.; Zhou, Dewang; Dai, Qian; Wu, Qiang; Giles, Keith E.; Townes, Tim M.; Wang, Hengbin

2014-01-01

149

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

PubMed Central

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

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

2014-01-01

150

The adipose-derived lineage-negative cells are enriched mesenchymal stem cells and promote limb ischemia recovery in mice.  

PubMed

White adipose tissue (WAT) is a very attractive source of mesenchymal stem cells (MSCs) because of its availability and ease of harvest. However, the current method of isolating adipose tissue-derived MSCs often relies on the adhesiveness of the cultured stromal-vascular fraction (SVF). Unfortunately, the SVF is a heterogeneous cell population containing many cell types, including adipocyte precursor cells, endothelial cells, pericytes, multipotent MSCs, erythrocytes, and hematopoietic cells. Here we systematically characterized the adipose tissue-derived lineage-negative (Lin(-)) cell population using various surface markers and a set of cell proliferation and differentiation assays. We demonstrate clearly that the Lin(-) cell population represents enriched MSCs, which were identified by their high expression of MSC surface markers, and that these cells are a robust population with a vigorous growth capability and delayed aging. This cell population also demonstrated a much higher capacity for differentiation into osteogenic, chondrogenic and adipogenic cell lineages related to MSCs than did the SVF. These cells promoted recovery from limb ischemia, likely via production of vascular endothelial growth factor, an angiogenic factor. Our study demonstrates that Lin(-) cells are enriched in MSCs and provides a reliable method for isolating purer MSCs than SVF cells from the WAT, especially for obtaining fresh MSCs for clinical applications. In summary, this study identified a new, reliable method for enrichment of WAT MSCs with regenerative repairing features. PMID:24083854

Qin, Yiren; Zhou, Peijie; Zhou, Chikai; Li, Jinsong; Gao, Wei-Qiang

2014-02-15

151

Effects of Ionizing Radiation on Human Adipose Derived Mesenchymal Stem Cells and their Differentiation towards the Osteoblastic Lineage  

NASA Astrophysics Data System (ADS)

Radiation exposure and musculoskeletal disuse are among the major challenges during space missions. Astronauts face the problem to lose bone calcium due to uncoupling of bone formation and resorption. Bone forming osteoblasts can be derived from the undifferentiated mesenchymal stem cell compartment (MSC). In this study, the ability of human adipose tissue derived stem cells (ATSC) to differentiate into the osteoblastic lineage was examined after radiation exposure in presence of medium supplementation with osteogenic additives (ß-glycerophosphate, ascorbic acid and dexamethasone). The SAOS-2 cell line (human osteosarcoma cell line) was used as control for osteoblastic differentiation. Changes in cellular morphology, cell cycle progression, as well as cellular radiation sensitivity were characterized after ionizing radiation exposure with X-rays and heavy ions (Ti). Rapidly proliferating SAOS-2 cells are less radiation-sensitive than slowly proliferating ATSC cells after X-ray (CFA: dose effect curves show D0 values of 1 Gy and 0.75 Gy for SAOS-2 and ATSC, respectively) exposure. Heavy ion (Ti) exposure resulted in a greater extent of cells accumulating in the G2/M phase of the cell cycle in a dose-dependent manner when compared to X-ray exposure. Differentiation of cells towards the osteoblastic lineage was quantified by hydroxyapatite (HA) deposition using Lonza OsteoImageTM mineralization assay. The deposition of HA after X- and Ti-irradiation for highly proliferating SAOS-2 cells showed a dose-dependent time delay while slowly proliferating ATSC showed no effect from radiation exposure. More detailed investigation is required to reveal the radiation dependent mechanism of bone loss in astronauts.

Konda, Bikash; Baumstark-Khan, Christa; Hellweg, Christine; Reitz, Guenther; Lau, Patrick

152

Brushing up on Dinosaurs.  

ERIC Educational Resources Information Center

Describes new methods of reconstruction of dinosaurs using skeletons, mummified skin, and muscle scars, along with clay and paint. Examines some inaccuracies in dinosaur's physical characteristics and behaviors suggested by recent findings. (TW)

Weisburd, Stefi

1986-01-01

153

What's New, Dinosaur?  

ERIC Educational Resources Information Center

Activities and information relating to dinosaurs are presented, including: study of warm- and cold-blooded animals; research about recent dinosaur discoveries; track-making; studying and making fossils; and extinction theories. (CB)

Prime, Carol Spirkoff; Cox, Judy

1987-01-01

154

Dinosaur Sock Puppet  

NSDL National Science Digital Library

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.

2012-11-09

155

The cellular form of the prion protein guides the differentiation of human embryonic stem cells into neuron-, oligodendrocyte-, and astrocyte-committed lineages.  

PubMed

Prion protein, PrP(C), is a glycoprotein that is expressed on the cell surface beginning with the early stages of embryonic stem cell differentiation. Previously, we showed that ectopic expression of PrP(C) in human embryonic stem cells (hESCs) triggered differentiation toward endodermal, mesodermal, and ectodermal lineages, whereas silencing of PrP(C) suppressed differentiation toward ectodermal but not endodermal or mesodermal lineages. Considering that PrP(C) might be involved in controlling the balance between cells of different lineages, the current study was designed to test whether PrP(C) controls differentiation of hESCs into cells of neuron-, oligodendrocyte-, and astrocyte-committed lineages. PrP(C) was silenced in hESCs cultured under three sets of conditions that were previously shown to induce hESCs differentiation into predominantly neuron-, oligodendrocyte-, and astrocyte-committed lineages. We found that silencing of PrP(C) suppressed differentiation toward all three lineages. Similar results were observed in all three protocols, arguing that the effect of PrP(C) was independent of differentiation conditions employed. Moreover, switching PrP(C) expression during a differentiation time course revealed that silencing PrP(C) expression during the very initial stage that corresponds to embryonic bodies has a more significant impact than silencing at later stages of differentiation. The current work illustrates that PrP(C) controls differentiation of hESCs toward neuron-, oligodendrocyte-, and astrocyte-committed lineages and is likely involved at the stage of uncommitted neural progenitor cells rather than lineage-committed neural progenitors. PMID:25486050

Lee, Young Jin; Baskakov, Ilia V

2014-01-01

156

Paper Mache Dinosaurs  

NSDL National Science Digital Library

In this activity (located on page 6 of PDF), learners observe and reproduce the distinctive physical features (i.e. plates, sharp spikes, long necks, deep jaws, claws) of their favorite dinosaurs. Learners construct their own dinosaurs out of recycled objects and using paper mache techniques. Learners also document and display their dinosaurs.

Chicago Children's Museum

2011-01-01

157

Thermoregulation in Dinosaurs  

Microsoft Academic Search

ANATOMICAL, physiological and ecological evidence has been assembled by Bakker1 in an attempt to demonstrate that dinosaurs were endotherms. But critical parts of this evidence are less than convincing and may be interpreted differently. Bakker suggests that dinosaurs were built for sustained locomotion at moderate speeds and infers from this that dinosaur energy metabolism was endotherm-like. But I consider it

R. A. Thulborn

1973-01-01

158

Digging into Dinosaurs.  

ERIC Educational Resources Information Center

This four-week unit of study for grades 1-3 provides information and activities on 17 different dinosaurs. A 21-item pre- and post-test and a brief history of dinosaurs precede descriptions and full-page drawings of the following dinosaurs: (1) giant plant-eaters (brachiosaurus, brontosaurus, and diplodocus); (2) giant meat-eaters (allosaurus,…

Oleson, Barb

159

Dinosaur Extinction: Changing Views  

E-print Network

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

Archibald, J. David

160

Palaeontology Dinosaur extinction  

E-print Network

with the hypothesis that non-avian dinosaurs were extinct prior to the K­T boundary impact event. Keywords: dinosaurs The temporal mode of the Cretaceous­Tertiary (K­T) extinction, during which many groups of organisms, includingPalaeontology Dinosaur extinction: closing the `3 m gap' Tyler R. Lyson1,2,*, Antoine Bercovici3

Sargis, Eric J.

161

Differentiation of mouse and human embryonic stem cells into hepatic lineages  

Microsoft Academic Search

We recently reported a novel method to induce embryonic stem (ES) cells differentiate into an endodermal fate, especially pancreatic, using a supporting cell line. Here we describe the modified culture condition with the addition and withdrawal of secreted growth factors could induce ES cells to selectively differentiate into a hepatic fate efficiently. The signaling of BMP and FGF that have

Nobuaki Shiraki; Kahoko Umeda; Naomi Sakashita; Motohiro Takeya; Kazuhiko Kume; Shoen Kume

2008-01-01

162

Growth Dynamics of Australia's Polar Dinosaurs  

PubMed Central

Analysis of bone microstructure in ornithopod and theropod dinosaurs from Victoria, Australia, documents ontogenetic changes, providing insight into the dinosaurs' successful habitation of Cretaceous Antarctic environments. Woven-fibered bone tissue in the smallest specimens indicates rapid growth rates during early ontogeny. Later ontogeny is marked by parallel-fibered tissue, suggesting reduced growth rates approaching skeletal maturity. Bone microstructure similarities between the ornithopods and theropods, including the presence of LAGs in each group, suggest there is no osteohistologic evidence supporting the hypothesis that polar theropods hibernated seasonally. Results instead suggest high-latitude dinosaurs had growth trajectories similar to their lower-latitude relatives and thus, rapid early ontogenetic growth and the cyclical suspensions of growth inherent in the theropod and ornithopod lineages enabled them to successfully exploit polar regions. PMID:21826250

Woodward, Holly N.; Rich, Thomas H.; Chinsamy, Anusuya; Vickers-Rich, Patricia

2011-01-01

163

Intracellular Inactivation of Thyroid Hormone Is a Survival Mechanism for Muscle Stem Cell Proliferation and Lineage Progression  

PubMed Central

Summary Precise control of the thyroid hormone (T3)-dependent transcriptional program is required by multiple cell systems, including muscle stem cells. Deciphering how this is achieved and how the T3 signal is controlled in stem cell niches is essentially unknown. We report that in response to proliferative stimuli such as acute skeletal muscle injury, type 3 deiodinase (D3), the thyroid hormone-inactivating enzyme, is induced in satellite cells where it reduces intracellular thyroid signaling. Satellite cell-specific genetic ablation of dio3 severely impairs skeletal muscle regeneration. This impairment is due to massive satellite cell apoptosis caused by exposure of activated satellite cells to the circulating TH. The execution of this proapoptotic program requires an intact FoxO3/MyoD axis, both genes positively regulated by intracellular TH. Thus, D3 is dynamically exploited in vivo to chronically attenuate TH signaling under basal conditions while also being available to acutely increase gene programs required for satellite cell lineage progression. PMID:25456740

Dentice, Monica; Ambrosio, Raffaele; Damiano, Valentina; Sibilio, Annarita; Luongo, Cristina; Guardiola, Ombretta; Yennek, Siham; Zordan, Paola; Minchiotti, Gabriella; Colao, Annamaria; Marsili, Alessandro; Brunelli, Silvia; Del Vecchio, Luigi; Larsen, P. Reed; Tajbakhsh, Shahragim; Salvatore, Domenico

2014-01-01

164

Dinosaurs 2: What Were Dinosaurs Like ?  

NSDL National Science Digital Library

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.

Science Netlinks

2004-04-16

165

Capability of Cartilage Extract to In Vitro Differentiation of Rat Mesenchymal Stem Cells (MSCs) to Chondrocyte Lineage  

PubMed Central

The importance of mesenchymal stem cells (MSCs), as adult stem cells (ASCs) able to divide into a variety of different cells is of utmost importance for stem cell researches. In this study, the ability of cartilage extract to induce differentiation of rat derived omentum tissue MSCs (rOT-MSCs) into chondrocyte cells (CCs) was investigated. After isolation of rOT-MSCs, they were co-cultured with different concentrations of hyaline cartilage extract and chondrocyte differentiation was monitored. Expression of MSCs markers was analyzed via flow cytometry. Moreover, expression of octamer- binding transcription factor-4 (Oct-4), Wilm's tumor suppressor gene-1 (WT-1), aggrecan (AG), collagen type-II (CT-II) and collagen type-X (CT-X) was analyzed using RT-PCR on 16, 18 and 21 days. Furthermore, immunocytochemistry and western blot were performed for CT-II production. Finally, proteoglycans (PGs) were examined using toluidine blue and alcian blue staining. The phenotypic characterization revealed the positive expression of CD90, CD44 and negative expression of CD45 in rOT-MSCs. These cells also expressed mRNA of Oct-4 and WT-1 as markers of omentum tissue. Differentiated rOT-MSCs in the presence of 20 µg/ ml cartilage extract expressed AG, CT-II, CT-X, and PGs as specific markers of CCs. These observations suggest that cartilage extract is potentially able to induce differentiation of MSCs into chondrocyte lineage and may be considered as an available source for imposing tissue healing on the damaged cartilage. More investigations are needed to prove in vivo cartilage repair via cartilage extract or its effective factors. PMID:25815278

Talakoob, Setareh; Joghataei, Mohammad Taghi; Parivar, Kazem; Bananej, Maryam; Sanadgol, Nima

2015-01-01

166

Generation and Applications of Human Pluripotent Stem Cells Induced into Neural Lineages and Neural Tissues  

PubMed Central

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

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

2012-01-01

167

Of lineage and legacy – the development of mammalian hematopoietic stem cells  

PubMed Central

The hematopoietic system is one of the first complex tissues to develop in the mammalian conceptus. Of particular interest within the field of developmental hematopoiesis is the origin of adult bone marrow hematopoietic stem cells. Tracing their origin is complicated because blood is a mobile tissue, and because hematopoietic cells emerge from multiple embryonic sites. The origin of the adult mammalian blood system remains a topic of lively discussion and intense research. Interest is also focused on developmental signals that induce the adult hematopoietic stem cell program, as these may prove useful for generating and expanding these clinically important cells ex vivo. This review presents a historical overview of, and the most recent data on the developmental origins of hematopoiesis. PMID:18204427

Dzierzak, Elaine; Speck, Nancy A.

2009-01-01

168

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

PubMed Central

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

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

2014-01-01

169

Supersize That Dinosaur  

NSDL National Science Digital Library

In this activity, learners explore the size and scale of dinosaurs. Learners listen to "The Littlest Dinosaurs" by Bernard Most. Then, learners estimate the size of a Triceratops and T. rex by measuring and comparing the dinosaurs to known objects. Learners also use a hallway or go outdoors to create a full-size depiction of scale of the dinosaurs by predicting and measuring how many learners would have to lie across the ground head to foot to match the size of the two dinosaurs. This activity is featured on page 18 of the "Dinosphere" unit of study for K-2 learners.

Rick Crosslin

2004-01-01

170

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

Microsoft Academic Search

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

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

2001-01-01

171

Generation of purified neural precursors from embryonic stem cells by lineage selection  

Microsoft Academic Search

Mouse embryonic stem (ES) cells are non-transformed cell lines derived directly from the pluripotent founder tissue in the mouse embryo, the epiblast [1–3]. Aggregation of ES cells triggers the generation of a diverse array of cell types, including neuronal cells [4–7]. This capacity for multilineage differentiation is retained during genetic manipulation and clonal expansion [8]. In principle, therefore, ES cells

Meng Li; Larysa Pevny; Robin Lovell-Badge; Austin Smith

1998-01-01

172

Well-aligned chitosan-based ultrafine fibers committed teno-lineage differentiation of human induced pluripotent stem cells for Achilles tendon regeneration.  

PubMed

Physical property of substrates such as stiffness and topography have been reported to induce mesenchymal stem cells differentiation into bone, muscle and neuron lineages. Human-induced pluripotent stem cells (hiPSCs) are a highly promising cell source for regenerative medicine. However, physical properties have not yet been reported to successfully induce pluripotent stem cells into specific lineages. This study aimed to develop a robust, stepwise topographic strategy to induce hiPSCs differentiate into teno-lineage. A novel spinning approach termed stable jet electrospinning (SJES), is utilized to fabricate continuous well-aligned ultra?ne ?bers (891 ± 71 nm), which mimic the native tendon's microstructure and mechanical properties. hiPSCs are ?rst differentiated into MSCs on smooth plastic surface as confirmed by the differentiations into three mesenchymal lineages and expression of characteristic MSC surface markers through an EMT (Epithelial-Mesenchymal Transition) process. Subsequently, the hiPSC derived MSCs are seeded onto well-aligned fibers to differentiate into tenocyte-like cells through activating mechanic-signal pathway. The in situ tendon repair study further confirms that aligned fiber scaffold with hiPSC-MSCs had significant effect on improving the structural and mechanical properties of tendon injury repair. These findings indicate that the stepwise physical substrate change strategy can be adopted to induce hiPSCs differentiation for tendon tissue regeneration. PMID:25890767

Zhang, Can; Yuan, Huihua; Liu, Huanhuan; Chen, Xiao; Lu, Ping; Zhu, Ting; Yang, Long; Yin, Zi; Heng, Boon Chin; Zhang, Yanzhong; Ouyang, Hongwei

2015-06-01

173

Electrospun fibre diameter, not alignment, affects mesenchymal stem cell differentiation into the tendon/ligament lineage.  

PubMed

Efforts to develop engineered tendons and ligaments have focused on the use of a biomaterial scaffold and a stem cell source. However, the ideal scaffold microenvironment to promote stem cell differentiation and development of organized extracellular matrix is unknown. Through electrospinning, fibre scaffolds can be designed with tailorable architectures to mimic the intended tissue. In this study, the effects of fibre diameter and orientation were examined by electrospinning thin mats, consisting of small (< 1?µm), medium (1-2?µm) or large (> 2?µm) diameter fibres with either random or aligned fibre orientation. C3H10T1/2 model stem cells were cultured on the six different electrospun mats, as well as smooth spin-coated films, and the morphology, growth and expression of tendon/ligament genes were evaluated. The results demonstrated that fibre diameter affects cellular behaviour more significantly than fibre alignment. Initially, cell density was greater on the small fibre diameter mats, but similar cell densities were found on all mats after an additional week in culture. After 2?weeks, gene expression of collagen 1?1 and decorin was increased on all mats compared to films. Expression of the tendon/ligament transcription factor scleraxis was suppressed on all electrospun mats relative to spin-coated films, but expression on the large-diameter fibre mats was consistently greater than on the medium-diameter fibre mats. These results suggest that larger-diameter fibres (e.g. > 2?µm) may be more suitable for in vitro development of a tendon/ligament tissue. PMID:23038413

Cardwell, Robyn D; Dahlgren, Linda A; Goldstein, Aaron S

2014-12-01

174

Isolation, characterization and the multi-lineage differentiation potential of rabbit bone marrow-derived mesenchymal stem cells  

PubMed Central

Mesenchymal stem cells (MSCs) are recognized by their plastic adherent ability, fibroblastic-like appearance, expression of specific surface protein markers, and are defined by their ability to undergo multi-lineage differentiation. Although rabbit bone marrow-derived MSCs (rbMSCs) have been used extensively in previous studies especially in translational research, these cells have neither been defined morphologically and ultrastructurally, nor been compared with their counterparts in humans in their multi-lineage differentiation ability. A study was therefore conducted to define the morphology, surface marker proteins, ultrastructure and multi-lineage differentiation ability of rbMSCs. Herein, the primary rbMSC cultures of three adult New Zealand white rabbits (at least 4 months old) were used for three independent experiments. rbMSCs were isolated using the gradient-centrifugation method, an established technique for human MSCs (hMSCs) isolation. Cells were characterized by phase contrast microscopy observation, transmission electron microscopy analysis, reverse transcriptase-polymerase chain reaction (PCR) analysis, immunocytochemistry staining, flow cytometry, alamarBlue® assay, histological staining and quantitative (q)PCR analysis. The isolated plastic adherent cells were in fibroblastic spindle-shape and possessed eccentric, irregular-shaped nuclei as well as rich inner cytoplasmic zones similar to that of hMSCs. The rbMSCs expressed CD29, CD44, CD73, CD81, CD90 and CD166, but were negative (or dim positive) for CD34, CD45, CD117 and HLD-DR. Despite having similar morphology and phenotypic expression, rbMSCs possessed significantly larger cell size but had a lower proliferation rate as compared with hMSCs. Using established protocols to differentiate hMSCs, rbMSCs underwent osteogenic, adipogenic and chondrogenic differentiation. Interestingly, differentiated rbMSCs demonstrated higher levels of osteogenic (Runx2) and chondrogenic (Sox9) gene expressions than that of hMSCs (P < 0.05). There was, however, no difference in the adipogenic (Ppar?) expressions between these cell types (P > 0.05). rbMSCs possess similar morphological characteristics to hMSCs, but have a higher potential for osteogenic and chondrogenic differentiation, despite having a lower cell proliferation rate than hMSCs. The characteristics reported here may be used as a comprehensive set of criteria to define or characterize rbMSCs. PMID:23510053

Tan, Sik-Loo; Ahmad, Tunku Sara; Selvaratnam, Lakshmi; Kamarul, Tunku

2013-01-01

175

Concise Review: Skeletal Muscle Stem Cells and Cardiac Lineage: Potential for Heart Repair  

PubMed Central

Valuable and ample resources have been spent over the last two decades in pursuit of interventional strategies to treat the unmet demand of heart failure patients to restore myocardial structure and function. At present, it is clear that full restoration of myocardial structure and function is outside our reach from both clinical and basic research studies, but it may be achievable with a combination of ongoing research, creativity, and perseverance. Since the 1990s, skeletal myoblasts have been extensively investigated for cardiac cell therapy of congestive heart failure. Whereas the Myoblast Autologous Grafting in Ischemic Cardiomyopathy (MAGIC) trial revealed that transplanted skeletal myoblasts did not integrate into the host myocardium and also did not transdifferentiate into cardiomyocytes despite some beneficial effects on recipient myocardial function, recent studies suggest that skeletal muscle-derived stem cells have the ability to adopt a cardiomyocyte phenotype in vitro and in vivo. This brief review endeavors to summarize the importance of skeletal muscle stem cells and how they can play a key role to surpass current results in the future and enhance the efficacious implementation of regenerative cell therapy for heart failure. PMID:24371329

Hassan, Narmeen; Tchao, Jason

2014-01-01

176

Dinosaur eggs discovered inside mother  

NSDL National Science Digital Library

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.

American Association for the Advancement of Science (AAAS; )

2005-04-14

177

Insulin receptor isoform switching in intestinal stem cells, progenitors, differentiated lineages and tumors: evidence that IR-B limits proliferation  

PubMed Central

Summary Despite evidence for the impact of insulin on intestinal epithelial physiology and pathophysiology, the expression patterns, roles, and regulation of insulin receptor (IR) and IR isoforms in the intestinal epithelium are not well characterized. IR-A is thought to mediate the proliferative effects of insulin or insulin growth factors (IGFs) in fetal or cancer cells. IR-B is considered to be the metabolic receptor for insulin in specialized tissues. This study used a novel Sox9-EGFP reporter mouse that permits isolation of intestinal epithelial stem cells (IESCs), progenitors, enteroendocrine cells and differentiated lineages, the ApcMin/+ mouse model of precancerous adenoma and normal human intestinal and colorectal cancer (CRC) cell lines. We tested the hypothesis that there is differential expression of IR-A or IR-B in stem and tumor cells versus differentiated intestinal epithelial cells (IECs) and that IR-B impacts cell proliferation. Our findings provide evidence that IR-B expression is significantly lower in highly proliferative IESCs and progenitor cells versus post-mitotic, differentiated IECs and in subconfluent and undifferentiated versus differentiated Caco-2 cells. IR-B is also reduced in ApcMin/+ tumors and highly tumorigenic CRC cells. These differences in IR-B were accompanied by altered levels of mRNAs encoding muscleblind-like 2 (MBNL2), a known regulator of IR alternative splicing. Forced IR-B expression in subconfluent and undifferentiated Caco-2 cells reduced proliferation and increased biomarkers of differentiation. Our findings indicate that the impact of insulin on different cell types in the intestinal epithelium might differ depending on relative IR-B? IR-A expression levels and provide new evidence for the roles of IR-B to limit proliferation of CRC cells. PMID:24127567

Andres, Sarah F.; Simmons, James G.; Mah, Amanda T.; Santoro, M. Agostina; Van Landeghem, Laurianne; Lund, P. Kay

2013-01-01

178

Housekeeping gene stability influences the quantification of osteogenic markers during stem cell differentiation to the osteogenic lineage  

PubMed Central

Real-time reverse transcription PCR (RT-qPCR) relies on a housekeeping or normalizer gene whose expression remains constant throughout the experiment. RT-qPCR is commonly used for characterization of human bone marrow mesenchymal stem cells (hBMSCs). However, to the best of our knowledge, there are no studies validating the expression stability of the genes used as normalizers during hBMSCs differentiation. This work aimed to study the stability of the housekeeping genes ?-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and ribosomal protein L13A (RPL13A) during the osteogenic differentiation of hBMSCs. Their stability was evaluated via RT-qPCR in 14 and 20 day differentiation assays to the osteogenic lineage. Different normalization strategies were evaluated to quantify the osteogenic markers collagen type I, bone sialoprotein and osteonectin. Cell differentiation was confirmed via alizarin red staining. The results demonstrated up-regulation of ?-actin with maximum fold changes (MFC) of 4.38. GAPDH and RPL13A were not regulated by osteogenic media after 14 days and presented average fold changes lower than 2 in 20 day cultures. RPL13A (MFC < 2) had a greater stability when normalizing as a function of culture time compared with GAPDH (MFC ? 2.2), which resulted in expression patterns of the osteogenic markers more consistent with the observed differentiation process. The results suggest that ?-actin regulation could be associated with the morphological changes characteristic of hBMSCs osteogenic differentiation, and provide evidence for the superior performance of RPL13A as a normalizer gene in osteogenic differentiation studies of hBMSCs. This work highlights the importance of validating the normalizer genes used for stem cells characterization via RT-qPCR. PMID:20396946

Posada, Olga M.; Gallego-Perez, Daniel; Higuita-Castro, Natalia; Sarassa, Carlos; Hansford, Derek J.; Agudelo-Florez, Piedad; López, Luis E.

2010-01-01

179

Housekeeping gene stability influences the quantification of osteogenic markers during stem cell differentiation to the osteogenic lineage.  

PubMed

Real-time reverse transcription PCR (RT-qPCR) relies on a housekeeping or normalizer gene whose expression remains constant throughout the experiment. RT-qPCR is commonly used for characterization of human bone marrow mesenchymal stem cells (hBMSCs). However, to the best of our knowledge, there are no studies validating the expression stability of the genes used as normalizers during hBMSCs differentiation. This work aimed to study the stability of the housekeeping genes beta-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and ribosomal protein L13A (RPL13A) during the osteogenic differentiation of hBMSCs. Their stability was evaluated via RT-qPCR in 14 and 20 day differentiation assays to the osteogenic lineage. Different normalization strategies were evaluated to quantify the osteogenic markers collagen type I, bone sialoprotein and osteonectin. Cell differentiation was confirmed via alizarin red staining. The results demonstrated up-regulation of beta-actin with maximum fold changes (MFC) of 4.38. GAPDH and RPL13A were not regulated by osteogenic media after 14 days and presented average fold changes lower than 2 in 20 day cultures. RPL13A (MFC < 2) had a greater stability when normalizing as a function of culture time compared with GAPDH (MFC stem cells characterization via RT-qPCR. PMID:20396946

Quiroz, Felipe Garcia; Posada, Olga M; Gallego-Perez, Daniel; Higuita-Castro, Natalia; Sarassa, Carlos; Hansford, Derek J; Agudelo-Florez, Piedad; López, Luis E

2010-04-01

180

Differentiation of murine embryonic stem cells toward renal lineages by conditioned medium from ureteric bud cells in vitro.  

PubMed

The kidney is formed from two tissue populations derived from the intermediate mesoderm, the ureteric bud, and the metanephric mesenchyme. Metanephric mesenchyme is a pluripotent renal stem population, and conversion of renal mesenchyme into epithelia depends on the ureteric bud in vivo and in vitro. Embryonic stem (ES) cells have been induced to differentiate into a broad spectrum of specialized cell types in vitro, including hematopoietic, pancreatic, and neuronal cells. Such ES-derived cells can provide a valuable source of progenitor cells. However, whether ES cells can be stimulated by factors secreted from the fetal renal cells to differentiate into renal precursor cells in vitro has not been reported. In this study, we showed that murine ES cells can give rise to embryoid bodies in the absence of leukemia inhibitory factor. Culture conditions were optimized [6 days, 10 ng/ml activin and 10(-7) M retinoic acid (RA)] to generate maximal mesoderm populations specifically expressing Pax2 and brachyury. Results showed that 72% of the cells were brachyury positive by fluorescent activated cell sorter on Day 6 of EB cell differentiation. Conditioned medium collected from cultures of ureteric bud cells from renal cells of a 13-day-old fetus was added to the culture medium. Mesoderm cells were cultured for up to 10 days before showing expression of renal markers, initiation of nephrogenesis (WT-1 and Pax2), and terminally differentiated renal cell types (POD-1 and E-cadherin). This study suggests that ES cells pre-treated by RA and activin can interact with secreted molecules of the fetal renal cells to specifically differentiate into renal precursor cells. Our results provide an experimental basis for the development of in vitro assays to steer differentiation of ES cells toward renal lineages. PMID:20705585

Ren, Xiaohui; Zhang, Jingya; Gong, Xiaowen; Niu, Xin; Zhang, Xuejin; Chen, Peng; Zhang, Xuejun

2010-07-01

181

Dual Small-Molecule Targeting of SMAD Signaling Stimulates Human Induced Pluripotent Stem Cells toward Neural Lineages  

PubMed Central

Incurable neurological disorders such as Parkinson’s disease (PD), Huntington’s disease (HD), and Alzheimer’s disease (AD) are very common and can be life-threatening because of their progressive disease symptoms with limited treatment options. To provide an alternative renewable cell source for cell-based transplantation and as study models for neurological diseases, we generated induced pluripotent stem cells (iPSCs) from human dermal fibroblasts (HDFs) and then differentiated them into neural progenitor cells (NPCs) and mature neurons by dual SMAD signaling inhibitors. Reprogramming efficiency was improved by supplementing the histone deacethylase inhibitor, valproic acid (VPA), and inhibitor of p160-Rho associated coiled-coil kinase (ROCK), Y-27632, after retroviral transduction. We obtained a number of iPS colonies that shared similar characteristics with human embryonic stem cells in terms of their morphology, cell surface antigens, pluripotency-associated gene and protein expressions as well as their in vitro and in vivo differentiation potentials. After treatment with Noggin and SB431542, inhibitors of the SMAD signaling pathway, HDF-iPSCs demonstrated rapid and efficient differentiation into neural lineages. Six days after neural induction, neuroepithelial cells (NEPCs) were observed in the adherent monolayer culture, which had the ability to differentiate further into NPCs and neurons, as characterized by their morphology and the expression of neuron-specific transcripts and proteins. We propose that our study may be applied to generate neurological disease patient-specific iPSCs allowing better understanding of disease pathogenesis and drug sensitivity assays. PMID:25207966

Wattanapanitch, Methichit; Klincumhom, Nuttha; Potirat, Porntip; Amornpisutt, Rattaya; Lorthongpanich, Chanchao; U-pratya, Yaowalak; Laowtammathron, Chuti; Kheolamai, Pakpoom; Poungvarin, Niphon; Issaragrisil, Surapol

2014-01-01

182

Adult Murine Bone Marrow-Derived Very Small Embryonic-Like Stem Cells (VSELs) Differentiate Into the Hematopoietic Lineage After Co-Culture Over OP9 Stromal Cells  

PubMed Central

Objective We recently identified a population of small Sca-1+/Lin?/CD45? cells in adult murine bone marrow that express several epiblast/germ line and pluripotent stem cell markers (e.g., Oct-4 and SSEA-4) that we named “very small embryonic-like stem cells” (VSELs). In this report, we test the hypothesis that VSELs can differentiate along the hemato/lymphopoietic lineage. Material and Methods Purified from BM VSELs were primed/co-cultured over OP9 stroma cell line and subsequently tested in vitro and in vivo assays for their hematopoietic potential. In parallel cells derived from VSELs were evaluated for expression of hematopoietic genes and surface markers. Results While we observed that freshly isolated VSELs do not exhibit in vitro and in vivo hematopoietic potential, they may, after co-culture over OP9 stromal cells, differentiate along the hematopoietic lineage in a similar way as embryonic stem cells or inducible pluripotent stem cells. “OP9-primed,” VSEL-derived cells acquired expression of several hemato/lymphopoiesis-specific genes and markers, gave rise to hematopoietic colonies in vitro, and protected lethally irradiated mice in both primary and secondary transplant models upon transplantation. We also observed that, compared to hematopoietic stem/progenitor cells (HSCs), VSELs are highly resistant to total body irradiation. Conclusions Based on these observations, we postulate that VSELs are the most primitive murine BM-residing population of stem cells that have the potential to become specified into the hematopoietic lineage and thus may share some of the characteristics of long-term repopulating HSCs. PMID:21034791

Ratajczak, Janina; Wysoczynski, Marcin; Zuba-Surma, Ewa; Wan, Wu; Kucia, Magda; Yoder, Mervin C.; Ratajczak, Mariusz Z.

2011-01-01

183

Activated Notch1 alters differentiation of embryonic stem cells into mesodermal cell lineages at multiple stages of development.  

PubMed

Signals of Notch transmembrane receptors function to regulate a wide variety of developmental cell fates. Here we investigate the role of Notch signaling in the development of mesodermal cell types by expressing a tamoxifen-inducible, activated form of Notch1 in embryonic stem cells (ESC). For differentiation of ESC into first mesodermal progenitor cells and then endothelial, mural, cardiac muscle and hematopoietic cells, the OP9 stroma co-culture system was used. Timed activation of Notch signaling by the addition of tamoxifen at various stages during differentiation of ESC into mesodermal cell lineages results in profound alterations in the generation of all of these cells. Differentiation of ESC into Flk1(+) mesodermal cells is inhibited by activated Notch. When Notch signaling is activated in mesodermal cells, generation of cardiac muscle, endothelial and hematopoietic cells is inhibited, favoring the generation of mural cells. Activation of Notch signaling in hematopoietic cells reduces colony formation and maintenance of hematopoiesis. These data suggest that Notch signaling plays a regulatory role in mesodermal development, cardiomyogenesis, the balanced generation of endothelial versus mural cells of blood vessels and hematopoietic development. PMID:16822655

Schroeder, Timm; Meier-Stiegen, Franziska; Schwanbeck, Ralf; Eilken, Hanna; Nishikawa, Satomi; Häsler, Robert; Schreiber, Stefan; Bornkamm, Georg W; Nishikawa, Shin-Ichi; Just, Ursula

2006-07-01

184

A sauropodomorph dinosaur from the Upper Triassic (Carman) of southern Brazil  

NASA Astrophysics Data System (ADS)

Three newly discovered skeletons from the Carnian red beds of the Santa Maria Formation, south Brazil, represent one of the oldest dinosaurs ever found. The new taxon Saturnalia tupiniquim, is equivalent in age to the earliest dinosaurs from northwestern Argentina, being the oldest sauropodomorph dinosaur known from plentiful skeletal material. The record of Saturnalia, a 1.5-m-long gracile plant-eating animal, indicates that, like other major dinosaur lineages, the first representatives of the mainly heavy-built sauropodomorphs were gracile animals.

Langer, Max C.; Abdala, Fernando; Richter, Martha; Benton, Michael J.

1999-10-01

185

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

PubMed Central

ABSTRACT 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

Huang, I-Husan; Hsiao, Cheng-Te; Wu, Jui-Chung; 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

2014-01-01

186

Optimization of Fibrin Scaffolds for Differentiation of Murine Embryonic Stem Cells into Neural Lineage Cells  

PubMed Central

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 (EB) cultures. For dissociated EBs, the optimal cell seeding density and location was determined to be 250,000 cells/cm2 seeded on top of fibrin scaffolds. For intact EBs, three dimensional (3D) cultures with one EB per 400 ?L fibrin scaffold resulted in greater cell proliferation and differentiation than two dimensional (2D) cultures. Optimal concentrations for scaffold polymerization were 10 mg/mL of fibrinogen and 2 NIH units/mL of thrombin. The optimal aprotinin concentration was determined to be 50 ?g/mL for dissociated EBs (2D) and 5 ?g/mL for intact EBs in 3D fibrin scaffolds. Additionally, after 14 days in 3D culture EBs differentiated into neurons and astrocytes as indicated by immunohistochemisty. These conditions provide an optimal fibrin scaffold for evaluating ES cell differentiation and proliferation in culture, and for use as a platform for neural tissue engineering applications, such as the treatment for spinal cord injury. PMID:16919326

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

2007-01-01

187

Arthropod phylogeny: onychophoran brain organization suggests an archaic relationship with a chelicerate stem lineage  

PubMed Central

Neuroanatomical studies have demonstrated that the architecture and organization among neuropils are highly conserved within any order of arthropods. The shapes of nerve cells and their neuropilar arrangements provide robust characters for phylogenetic analyses. Such analyses so far have agreed with molecular phylogenies in demonstrating that entomostracans+malacostracans belong to a clade (Tetraconata) that includes the hexapods. However, relationships among what are considered to be paraphyletic groups or among the stem arthropods have not yet been satisfactorily resolved. The present parsimony analyses of independent neuroarchitectural characters from 27 arthropods and lobopods demonstrate relationships that are congruent with phylogenies derived from molecular studies, except for the status of the Onychophora. The present account describes the brain of the onychophoran Euperipatoides rowelli, demonstrating that the structure and arrangements of its neurons, cerebral neuropils and sensory centres are distinct from arrangements in the brains of mandibulates. Neuroanatomical evidence suggests that the organization of the onychophoran brain is similar to that of the brains of chelicerates. PMID:16822744

Strausfeld, Nicholas J; Mok Strausfeld, Camilla; Loesel, Rudi; Rowell, David; Stowe, Sally

2006-01-01

188

Compare Dinosaur Body Parts  

NSDL National Science Digital Library

In this activity, learners explore the size and scale of dinosaurs. Learners listen to "The Littlest Dinosaurs" by Bernard Most to learn about the different sizes of dinosaurs. Then, learners create a chart of measurements that compare the sizes of the body parts of a T. rex, Triceratops, the learner, and their partner. Learners also convert the measurements into centimeters and meters. This activity is featured on pp. 20-21 of the "Dinosphere" unit of study for K-2 learners.

2014-04-14

189

Those Fussy Dinosaurs!  

NSDL National Science Digital Library

This lesson introduces students to the idea that animals prefer certain types of habitats over others and, in fact, cannot live in places that are too different from what they prefer. In this case they will focus on dinosaurs. They will learn about the types of habitats and climates scientists believe dinosaurs tended to prefer and will conclude by drawing background scenes to use in a toy dinosaur home.

190

Classroom Dinosaur Dig  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

191

Dinosaur Planet video gallery  

NSDL National Science Digital Library

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.

Discovery Channel

192

Create a Dinosaur Name  

NSDL National Science Digital Library

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.

2014-04-14

193

Evidence for a critical role of catecholamines for cardiomyocyte lineage commitment in murine embryonic stem cells.  

PubMed

Catecholamine release is known to modulate cardiac output by increasing heart rate. Although much is known about catecholamine function and regulation in adults, little is known about the presence and role of catecholamines during heart development. The present study aimed therefore to evaluate the effects of different catecholamines on early heart development in an in vitro setting using embryonic stem (ES) cell-derived cardiomyocytes. Effects of catecholamine depletion induced by reserpine were examined in murine ES cells (line D3, ?PIG44) during differentiation. Cardiac differentiation was assessed by immunocytochemistry, qRT-PCR, quantification of beating clusters, flow cytometry and pharmacological approaches. Proliferation was analyzed by EB cross-section measurements, while functionality of cardiomyocytes was studied by extracellular field potential (FP) measurements using microelectrode arrays (MEAs). To further differentiate between substance-specific effects of reserpine and catecholamine action via ?- and ?-receptors we proved the involvement of adrenergic receptors by application of unspecific ?- and ?-receptor antagonists. Reserpine treatment led to remarkable down-regulation of cardiac-specific genes, proteins and mesodermal marker genes. In more detail, the average ratio of ?40% spontaneously beating control clusters was significantly reduced by 100%, 91.1% and 20.0% on days 10, 12, and 14, respectively. Flow cytometry revealed a significant reduction (by 71.6%, n?=?11) of eGFP positive CMs after reserpine treatment. By contrast, reserpine did not reduce EB growth while number of neuronal cells in reserpine-treated EBs was significantly increased. MEA measurements of reserpine-treated EBs showed lower FP frequencies and weak responsiveness to adrenergic and muscarinic stimulation. Interestingly we found that developmental inhibition after ?- and ?-adrenergic blocker application mimicked developmental changes with reserpine. Using several methodological approaches our data suggest that reserpine inhibits cardiac differentiation. Thus catecholamines play a critical role during development. PMID:23936474

Lehmann, Martin; Nguemo, Filomain; Wagh, Vilas; Pfannkuche, Kurt; Hescheler, Jürgen; Reppel, Michael

2013-01-01

194

High throughput transcriptome profiling of lithium stimulated human mesenchymal stem cells reveals priming towards osteoblastic lineage.  

PubMed

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

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

2013-01-01

195

Angiogenic CXC chemokine expression during differentiation of human mesenchymal stem cells towards the osteoblastic lineage.  

PubMed

The potential role of ELR(+) CXC chemokines in early events in bone repair was studied using human mesenchymal stem cells (hMSCs). Inflammation, which occurs in the initial phase of tissue healing in general, is critical to bone repair. Release of cytokines from infiltrating immune cells and injured bone can lead to recruitment of MSCs to the region of repair. CXC chemokines bearing the Glu-Leu-Arg (ELR) motif are also released by inflammatory cells and serve as angiogenic factors stimulating chemotaxis and proliferation of endothelial cells. hMSCs, induced to differentiate with osteogenic medium (OGM) containing ascorbate, beta-glycerophosphate (beta-GP), and dexamethasone (DEX), showed an increase in mRNA and protein secretion of the ELR(+) CXC chemokines CXCL8 and CXCL1. CXCL8 mRNA half-life studies reveal an increase in mRNA stability upon OGM stimulation. Increased expression and secretion is a result of DEX in OGM and is dose-dependent. Inhibition of the glucocorticoid receptor with mifepristone only partially inhibits DEX-stimulated CXCL8 expression indicating both glucocorticoid receptor dependent and independent pathways. Treatment with signal transduction inhibitors demonstrate that this expression is due to activation of the ERK and p38 mitogen-activated protein kinase (MAPK) pathways and is mediated through the G(alphai)-coupled receptors. Angiogenesis assays demonstrate that OGM-stimulated conditioned media containing secreted CXCL8 and CXCL1 can induce angiogenesis of human microvascular endothelial cells in an in vitro Matrigel assay. PMID:17583554

Bischoff, D S; Zhu, J H; Makhijani, N S; Kumar, A; Yamaguchi, D T

2008-02-15

196

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.

197

Fossilized Dinosaur Teeth Adaptations  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

198

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.

199

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

E-print Network

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

Holtz Jr., Thomas R.

200

Redundant miR-3077-5p and miR-705 mediate the shift of mesenchymal stem cell lineage commitment to adipocyte in osteoporosis bone marrow  

PubMed Central

During the process of aging, especially for postmenopausal females, the cell lineage commitment of mesenchymal stem cells (MSCs) shift to adipocyte in bone marrow, resulting in osteoporosis. However, the cell-intrinsic mechanism of this cell lineage commitment switch is poorly understood. As the post-transcription regulation by microRNAs (miRNAs) has a critical role in MSCs differentiation and bone homeostasis, we performed comprehensive miRNAs profiling and found miR-705 and miR-3077-5p were significantly enhanced in MSCs from osteoporosis bone marrow. Both miR-705 and miR-3077-5p acted as inhibitors of MSCs osteoblast differentiation and promoters of adipocyte differentiation, by targeting on the 3?untranslated region (3?UTR) of HOXA10 and RUNX2 mRNA separately. Combined inhibition of miR-705 and miR-3077-5p rescued the cell lineage commitment disorder of MSCs through restoring HOXA10 and RUNX2 protein level. Furthermore, we found excessive TNF? and reactive oxygen species caused by estrogen deficiency led to the upregulation of both miRNAs through NF-?B pathway. In conclusion, our findings showed that redundant miR-705 and miR-3077-5p synergistically mediated the shift of MSCs cell lineage commitment to adipocyte in osteoporosis bone marrow, providing new insight into the etiology of osteoporosis at the post-transcriptional level. Moreover, the rescue of MSCs lineage commitment disorder by regulating miRNAs expression suggested a novel potential therapeutic target for osteoporosis as well as stem cell-mediated regenerative medicine. PMID:23598412

Liao, L; Yang, X; Su, X; Hu, C; Zhu, X; Yang, N; Chen, X; Shi, S; Shi, S; Jin, Y

2013-01-01

201

There is more to a lipid than just being a fat: sphingolipid-guided differentiation of oligodendroglial lineage from embryonic stem cells.  

PubMed

Dr. Robert K. Yu's research showed for the first time that the composition of glycosphingolipids is tightly regulated during embryo development. Studies in our group showed that the glycosphingolipid precursor ceramide is also critical for stem cell differentiation and apoptosis. Our new studies suggest that ceramide and its derivative, sphingosine-1-phosphate (S1P), act synergistically on embryonic stem (ES) cell differentiation. When using neural precursor cells (NPCs) derived from ES cells for transplantation, residual pluripotent stem (rPS) cells pose a significant risk of tumor formation after stem cell transplantation. We show here that rPS cells did not express the S1P receptor S1P1, which left them vulnerable to ceramide or ceramide analog (N-oleoyl serinol or S18)-induced apoptosis. In contrast, ES cell-derived NPCs expressed S1P1 and were protected in the presence of S1P or its pro-drug analog FTY720. Consistent with previous studies, FTY720-treated NPCs differentiated predominantly toward oligodendroglial lineage as tested by the expression of the oligodendrocyte precursor cell (OPC) markers Olig2 and O4. As the consequence, a combined administration of S18 and FTY720 to differentiating ES cells eliminated rPS cells and promoted oligodendroglial differentiation. In addition, we show that this combination promoted differentiation of ES cell-derived NPCs toward oligodendroglial lineage in vivo after transplantation into mouse brain. PMID:21136155

Bieberich, Erhard

2011-09-01

202

There is more to a lipid than just being a fat: sphingolipid-guided differentiation of oligodendroglial lineage from embryonic stem cells  

PubMed Central

Dr. Robert K. Yu's research showed for the first time that the composition of glycosphingolipids is tightly regulated during embryo development. Studies in our group showed that the glycosphingolipid precursor ceramide is also critical for stem cell differentiation and apoptosis. Our new studies suggest that ceramide and its derivative, sphingosine-1-phosphate (S1P), act synergistically on embryonic stem (ES) cell differentiation. When using neural precursor cells (NPCs) derived from ES cells for transplantation, residual pluripotent stem (rPS) cells pose a significant risk of tumor formation after stem cell transplantation. We show here that rPS cells did not express the S1P receptor S1P1, which left them vulnerable to ceramide or ceramide analog (N-oleoyl serinol or S18)-induced apoptosis. In contrast, ES cell-derived NPCs expressed S1P1 and were protected in the presence of S1P or its pro-drug analog FTY720. Consistent with previous studies, FTY720-treated NPCs differentiated predominantly toward oligodendroglial lineage as tested by the expression of the oligodendrocyte precursor cell (OPC) markers Olig2 and O4. As the consequence, a combined administration of S18 and FTY720 to differentiating ES cells eliminated rPS cells and promoted oligodendroglial differentiation. In addition, we show that this combination promoted differentiation of ES cell-derived NPCs toward oligodendroglial lineage in vivo after transplantation into mouse brain. PMID:21136155

Bieberich, Erhard

2013-01-01

203

Dinosaur Extinction, Early Childhood Style  

ERIC Educational Resources Information Center

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…

Murray, Mary; Valentine-Anand, Lesley

2008-01-01

204

Dinosaur Paleobiology Geology 331  

E-print Network

;Abundant vascular canals in dinosaur bone support the warm- blooded theory #12;Thin section of dinosaur ­ abundant vascular canals · Head above the heart required high blood pressure and, thus, a four;Coelophysis, a late Triassic bipedal ancestor #12;Tyrannosaurus rex, the Cretaceous theropod everyone loves

Kammer, Thomas

205

Dinosaur Tracks and Trackways  

NSDL National Science Digital Library

This University of Bristol page discusses the process and importance of studying dinosaur tracks and trackways. Beginning with footprint morphology and preservation, it covers track taphonomy, ichnotaxonomy, dinosaur posture and stance, behavior, gait and speed, paleoecology and how to identify the trackmaker. Links are provided for additional resources.

Myles McLeod

206

Dinosaur Footprints & Fossils  

NSDL National Science Digital Library

In this activity, early learners simulate fossil prints in play dough or clay. Using plastic dinosaur feet to make footprints on their “mud” (much as dinosaurs walked around their habitat) and harvest items (leaves, corn, twigs, acorns) to make impressions, learners simulate fossil prints. This resource includes open-ended discussion questions to encourage reflection.

2012-12-27

207

Sauropod dinosaur osteoderms from the Late Cretaceous of Madagascar  

Microsoft Academic Search

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

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

2011-01-01

208

Paleobiology of Herbivorous Dinosaurs  

NASA Astrophysics Data System (ADS)

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.

Barrett, Paul M.

2014-05-01

209

Instruction of haematopoietic lineage choices, evolution of transcriptional landscapes and cancer stem cell hierarchies derived from an AML1-ETO mouse model  

PubMed Central

The t(8;21) chromosomal translocation activates aberrant expression of the AML1-ETO (AE) fusion protein and is commonly associated with core binding factor acute myeloid leukaemia (CBF AML). Combining a conditional mouse model that closely resembles the slow evolution and the mosaic AE expression pattern of human t(8;21) CBF AML with global transcriptome sequencing, we find that disease progression was characterized by two principal pathogenic mechanisms. Initially, AE expression modified the lineage potential of haematopoietic stem cells (HSCs), resulting in the selective expansion of the myeloid compartment at the expense of normal erythro- and lymphopoiesis. This lineage skewing was followed by a second substantial rewiring of transcriptional networks occurring in the trajectory to manifest leukaemia. We also find that both HSC and lineage-restricted granulocyte macrophage progenitors (GMPs) acquired leukaemic stem cell (LSC) potential being capable of initiating and maintaining the disease. Finally, our data demonstrate that long-term expression of AE induces an indolent myeloproliferative disease (MPD)-like myeloid leukaemia phenotype with complete penetrance and that acute inactivation of AE function is a potential novel therapeutic option. PMID:24124051

Cabezas-Wallscheid, Nina; Eichwald, Victoria; de Graaf, Jos; Löwer, Martin; Lehr, Hans-Anton; Kreft, Andreas; Eshkind, Leonid; Hildebrandt, Andreas; Abassi, Yasmin; Heck, Rosario; Dehof, Anna Katharina; Ohngemach, Svetlana; Sprengel, Rolf; Wörtge, Simone; Schmitt, Steffen; Lotz, Johannes; Meyer, Claudius; Kindler, Thomas; Zhang, Dong-Er; Kaina, Bernd; Castle, John C; Trumpp, Andreas; Sahin, Ugur; Bockamp, Ernesto

2013-01-01

210

Instruction of haematopoietic lineage choices, evolution of transcriptional landscapes and cancer stem cell hierarchies derived from an AML1-ETO mouse model.  

PubMed

The t(8;21) chromosomal translocation activates aberrant expression of the AML1-ETO (AE) fusion protein and is commonly associated with core binding factor acute myeloid leukaemia (CBF AML). Combining a conditional mouse model that closely resembles the slow evolution and the mosaic AE expression pattern of human t(8;21) CBF AML with global transcriptome sequencing, we find that disease progression was characterized by two principal pathogenic mechanisms. Initially, AE expression modified the lineage potential of haematopoietic stem cells (HSCs), resulting in the selective expansion of the myeloid compartment at the expense of normal erythro- and lymphopoiesis. This lineage skewing was followed by a second substantial rewiring of transcriptional networks occurring in the trajectory to manifest leukaemia. We also find that both HSC and lineage-restricted granulocyte macrophage progenitors (GMPs) acquired leukaemic stem cell (LSC) potential being capable of initiating and maintaining the disease. Finally, our data demonstrate that long-term expression of AE induces an indolent myeloproliferative disease (MPD)-like myeloid leukaemia phenotype with complete penetrance and that acute inactivation of AE function is a potential novel therapeutic option. PMID:24124051

Cabezas-Wallscheid, Nina; Eichwald, Victoria; de Graaf, Jos; Löwer, Martin; Lehr, Hans-Anton; Kreft, Andreas; Eshkind, Leonid; Hildebrandt, Andreas; Abassi, Yasmin; Heck, Rosario; Dehof, Anna Katharina; Ohngemach, Svetlana; Sprengel, Rolf; Wörtge, Simone; Schmitt, Steffen; Lotz, Johannes; Meyer, Claudius; Kindler, Thomas; Zhang, Dong-Er; Kaina, Bernd; Castle, John C; Trumpp, Andreas; Sahin, Ugur; Bockamp, Ernesto

2013-12-01

211

A reappraisal of the Cretaceous non-avian dinosaur faunas from Australia and New Zealand: evidence for their Gondwanan affinities  

Microsoft Academic Search

It has often been assumed that Australasian Cretaceous dinosaur faunas were for the most part endemic, but with some Laurasian affinities. In this regard, some Australasian dinosaurs have been considered Jurassic relicts, while others were thought to represent typical Laurasian forms or endemic taxa. Furthermore, it has been proposed that some dinosaurian lineages, namely oviraptorosaurians, dromaeosaurids, ornithomimosaurians and protoceratopsians, may

Federico L. Agnolin; Martín D. Ezcurra; Diego F. Pais; Steven W. Salisbury

2010-01-01

212

Dinosaur physiology. Evidence for mesothermy in dinosaurs.  

PubMed

Were dinosaurs ectotherms or fast-metabolizing endotherms whose activities were unconstrained by temperature? To date, some of the strongest evidence for endothermy comes from the rapid growth rates derived from the analysis of fossil bones. However, these studies are constrained by a lack of comparative data and an appropriate energetic framework. Here we compile data on ontogenetic growth for extant and fossil vertebrates, including all major dinosaur clades. Using a metabolic scaling approach, we find that growth and metabolic rates follow theoretical predictions across clades, although some groups deviate. Moreover, when the effects of size and temperature are considered, dinosaur metabolic rates were intermediate to those of endotherms and ectotherms and closest to those of extant mesotherms. Our results suggest that the modern dichotomy of endothermic versus ectothermic is overly simplistic. PMID:24926017

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

2014-06-13

213

The origin and early evolution of dinosaurs.  

PubMed

The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical "competitive" models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian-Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as "prosauropods" and coelophysoids. PMID:19895605

Langer, Max C; Ezcurra, Martin D; Bittencourt, Jonathas S; Novas, Fernando E

2010-02-01

214

Are Birds Really Dinosaurs?  

NSDL National Science Digital Library

Evidence presented on this site is overwhelmingly in favor of birds being the descendants of a maniraptoran dinosaur, probably something similar (but not identical) to a small dromaeosaur. Dr. Jacques Gauthier created the first well-accepted, detailed phylogeny of the diapsids. His work provided strong, compelling support for the theory that birds are theropod dinosaurs. The development of the theory is traced and a list of twenty major skeletal characteristics the first birds shared with many coelurosaurian dinosaurs is included. The site contains many active links for further study.

John Hutchinson

215

On Dinosaur Growth  

NASA Astrophysics Data System (ADS)

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.

Erickson, Gregory M.

2014-05-01

216

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

PubMed Central

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

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

2015-01-01

217

T-Cell Factor 3 Regulates Embryonic Stem Cell Pluripotency and Self-Renewal by the Transcriptional Control of Multiple Lineage Pathways  

PubMed Central

The Wnt signaling pathway is necessary both for maintaining undifferentiated stem cells and for directing their differentiation. In mouse embryonic stem cells (ESCs), Wnt signaling preferentially maintains “stemness” under certain permissive conditions. T-cell factor 3 (Tcf3) is a component of the Wnt signaling and a dominant downstream effector in ESCs. Despite the wealth of knowledge regarding the importance of Wnt signaling underlying stem cells functions, the precise mechanistic explanation by which the effects are mediated is unknown. In this study, we identified new regulatory targets of Tcf3 using a whole-genome approach and found that Tcf3 transcriptionally represses many genes important for maintaining pluripotency and self-renewal, as well as those involved in lineage commitment and stem cell differentiation. This effect is in part mediated by the corepressors transducin-like enhancer of split 2 and C-terminal Binding Protein (CtBP). Notably, Tcf3 binds to and represses the Oct4 promoter, and this repressive effect requires both the Groucho and CtBP interacting domains of Tcf3. Interestingly, we find that in mouse preimplantation development embryos, Tcf3 expression is coregulated with Oct4 and Nanog and becomes localized to the inner cell mass of the blastocyst. These data demonstrate an important role for Tcf3 in modulating the appropriate level of gene transcription in ESCs and during embryonic development. PMID:18467660

TAM, WAI-LEONG; LIM, CHIN YAN; HAN, JIANYONG; ZHANG, JINQIU; ANG, YEN-SIN; NG, HUCK-HUI; YANG, HENRY; LIM, BING

2009-01-01

218

Melanosome evolution indicates a key physiological shift within feathered dinosaurs.  

PubMed

Inference of colour patterning in extinct dinosaurs has been based on the relationship between the morphology of melanin-containing organelles (melanosomes) and colour in extant bird feathers. When this relationship evolved relative to the origin of feathers and other novel integumentary structures, such as hair and filamentous body covering in extinct archosaurs, has not been evaluated. Here we sample melanosomes from the integument of 181 extant amniote taxa and 13 lizard, turtle, dinosaur and pterosaur fossils from the Upper-Jurassic and Lower-Cretaceous of China. We find that in the lineage leading to birds, the observed increase in the diversity of melanosome morphologies appears abruptly, near the origin of pinnate feathers in maniraptoran dinosaurs. Similarly, mammals show an increased diversity of melanosome form compared to all ectothermic amniotes. In these two clades, mammals and maniraptoran dinosaurs including birds, melanosome form and colour are linked and colour reconstruction may be possible. By contrast, melanosomes in lizard, turtle and crocodilian skin, as well as the archosaurian filamentous body coverings (dinosaur 'protofeathers' and pterosaur 'pycnofibres'), show a limited diversity of form that is uncorrelated with colour in extant taxa. These patterns may be explained by convergent changes in the key melanocortin system of mammals and birds, which is known to affect pleiotropically both melanin-based colouration and energetic processes such as metabolic rate in vertebrates, and may therefore support a significant physiological shift in maniraptoran dinosaurs. PMID:24522537

Li, Quanguo; Clarke, Julia A; Gao, Ke-Qin; Zhou, Chang-Fu; Meng, Qingjin; Li, Daliang; D'Alba, Liliana; Shawkey, Matthew D

2014-03-20

219

Molecular signatures of the three stem cell lineages in hydra and the emergence of stem cell function at the base of multicellularity.  

PubMed

How distinct stem cell populations originate and whether there is a clear stem cell "genetic signature" remain poorly understood. Understanding the evolution of stem cells requires molecular profiling of stem cells in an animal at a basal phylogenetic position. In this study, using transgenic Hydra polyps, we reveal for each of the three stem cell populations a specific signature set of transcriptions factors and of genes playing key roles in cell type-specific function and interlineage communication. Our data show that principal functions of stem cell genes, such as maintenance of stemness and control of stem cell self-renewal and differentiation, arose very early in metazoan evolution. They are corroborating the view that stem cell types shared common, multifunctional ancestors, which achieved complexity through a stepwise segregation of function in daughter cells. PMID:22595987

Hemmrich, Georg; Khalturin, Konstantin; Boehm, Anna-Marei; Puchert, Malte; Anton-Erxleben, Friederike; Wittlieb, Jörg; Klostermeier, Ulrich C; Rosenstiel, Philip; Oberg, Hans-Heinrich; Domazet-Loso, Tomislav; Sugimoto, Toshimi; Niwa, Hitoshi; Bosch, Thomas C G

2012-11-01

220

F-box Protein FBXL16 Binds PP2A-B55? and Regulates Differentiation of Embryonic Stem Cells along the FLK1+ Lineage*  

PubMed Central

The programmed formation of specific tissues from embryonic stem cells is a major goal of regenerative medicine. To identify points of intervention in cardiac tissue formation, we performed an siRNA screen in murine embryonic stem cells to identify ubiquitin system genes that repress cardiovascular tissue formation. Our screen uncovered an F-box protein, Fbxl16, as a repressor of one of the earliest steps in the cardiogenic lineage: FLK1+ progenitor formation. Whereas F-box proteins typically form SCF ubiquitin ligases, shotgun mass spectrometry revealed that FBXL16 instead binds protein phosphatase 2A (PP2A) containing a B55 specificity subunit (PP2AB55). Phosphoproteomic analyses indicate that FBXL16 negatively regulates phosphorylation of the established PP2AB55 substrate, vimentin. We suggest that FBXL16 negatively regulates the activity of B55?-PP2A to modulate the genesis of FLK1+ progenitor cells. PMID:24390425

Honarpour, Narimon; Rose, Christopher M.; Brumbaugh, Justin; Anderson, Jody; Graham, Robert L. J.; Sweredoski, Michael J.; Hess, Sonja; Coon, Joshua J.; Deshaies, Raymond J.

2014-01-01

221

Dinosaur Reproduction and Parenting  

NASA Astrophysics Data System (ADS)

Non-avian dinosaur reproductive and parenting behaviors were mostly similar to those of extant archosaurs. Non-avian dinosaurs were probably sexually dimorphic and some may have engaged in hierarchical rituals. Non-avian coelurosaurs (e.g. Troodontidae, Oviraptorosauria) had two active oviducts, each of which produced single eggs on a daily or greater time scale. The eggs of non-coelurosaurian dinosaurs (e.g. Ornithischia, Sauropoda) were incubated in soils, whereas the eggs of non-avian coelurosaurs (e.g. Troodon, Oviraptor) were incubated with a combination of soil and direct parental contact. Parental attention to the young was variable, ranging from protection from predators to possible parental feeding of nest-bound hatchlings. Semi-altricial hadrosaur hatchlings exited their respective nests near the time of their first linear doubling. Some reproductive behaviors, once thought exclusive to Aves, arose first in non-avian dinosaurs. The success of the Dinosauria may be related to reproductive strategies.

Horner, John R.

222

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.

223

Warm and Cool Dinosaurs.  

ERIC Educational Resources Information Center

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)

Mannlein, Sally

2001-01-01

224

Dinosaur Count and Sort  

NSDL National Science Digital Library

In this activity, learners sort and count different colored plastic dinosaurs by various attributes including tail length, whether or not the dinosaurs have horns, etc. Learners discuss the basis of their sorting, describe individual dinosaurs as well as groups and count the whole as well as subsets of the whole. This identification, sorting and grouping based on different traits (physical attributes, diet, habitat) provides a strong foundation for the development of the concept of species. The lesson plan also explains that dinosaurs lived a long time ago, but because they are no longer alive today, they are said to be extinct. Reasons for their extinction and the concept of endangered species can be explored.

OMSI

2004-01-01

225

Dinosaur Trace Fossils  

NSDL National Science Digital Library

Anthony J. Martin, Senior Lecturer at Emory University, provides this interesting Website on dinosaur trace fossils -- namely tracks, trails, burrows, borings, gnawings, eggs, nests, gizzard stones, and dung of dinosaurs. The site offers a brief overview followed by illustrated descriptions of particular trace fossil types: Tracks and Trackways, Eggs and Nests, Tooth Marks, Gastroliths, and Coprolites. A series of links points users to further information, and a bibliography on Vertebrate Ichnology provides additional readings (through 1997).

Martin, Anthony J.

226

How Big Were Dinosaurs?  

NSDL National Science Digital Library

In this classroom activity, young students compare their feet to the foot of a large Apatosaur. The activity opens with background information for teachers about the enormous size range of dinosaurs. After using personal references to describe the size of dinosaurs, students examine the outline of an Apatosaur footprint. Students then estimate how many of their footprints would fit inside the Apatosaur footprint and conduct an experiment to test their estimate.

227

A misexpression screen reveals effects of bag-of-marbles and TGF beta class signaling on the Drosophila male germ-line stem cell lineage.  

PubMed Central

Male gametes are produced throughout reproductive life by a classic stem cell mechanism. However, little is known about the molecular mechanisms for lineage production that maintain male germ-line stem cell (GSC) populations, regulate mitotic amplification divisions, and ensure germ cell differentiation. Here we utilize the Drosophila system to identify genes that cause defects in the male GSC lineage when forcibly expressed. We conducted a gain-of-function screen using a collection of 2050 EP lines and found 55 EP lines that caused defects at early stages of spermatogenesis upon forced expression either in germ cells or in surrounding somatic support cells. Most strikingly, our analysis of forced expression indicated that repression of bag-of-marbles (bam) expression in male GSC is important for male GSC survival, while activity of the TGF beta signal transduction pathway may play a permissive role in maintenance of GSCs in Drosophila testes. In addition, forced activation of the TGF beta signal transduction pathway in germ cells inhibits the transition from the spermatogonial mitotic amplification program to spermatocyte differentiation. PMID:15238523

Schulz, Cordula; Kiger, Amy A; Tazuke, Salli I; Yamashita, Yukiko M; Pantalena-Filho, Luiz C; Jones, D Leanne; Wood, Cricket G; Fuller, Margaret T

2004-01-01

228

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

PubMed Central

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

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

2014-01-01

229

Contribution of hepatic lineage stage-specific donor memory to the differential potential of induced mouse pluripotent stem cells (iPSC)  

PubMed Central

Recent studies suggested that induced pluripotent stem cells (iPSCs) retain a residual donor cell gene expression which may impact their capacity to differentiate into cell of origin. Here we addressed a contribution of a lineage stage-specific donor cell memory in modulating the functional properties of iPSCs. iPSCs were generated from hepatic lineage cells at an early (hepatoblast-derived, HB-iPSCs) and end stage (adult hepatocyte, AH-iPSCs) of hepatocyte differentiation as well as from mouse fetal fibroblasts (MEF-iPSCs) using a lentiviral vector encoding four pluripotency-inducing factors Oct4, Sox2, Klf4, and c-Myc. All resulting iPS cell lines acquired iPSCs phenotype as judged by the accepted criteria including morphology, expression of pluripotency markers, silencing of transducing factors, capacity of multilineage differentiation in teratoma assay and normal diploid karyotype. However, HB-iPSCs were more efficient in directed differentiation towards hepatocytic lineage as compared to AH-iPSCs, MEF-iPSCs or mESCs. Extensive comparative transcriptome analyses of the early passage iPSCs, donor cells and mESCs revealed that despite global similarities in gene expression patterns between generated iPSCs and mESCs, HB-iPSCs retained a transcriptional memory (7 up- and 17 down-regulated genes) typical of the original cells. Continuous passaging of HB-iPSCs erased most of these differences including a superior capacity for hepatic re-differentiation. These results suggest that retention of lineage stage-specific donor memory in iPSCs may facilitate differentiation into donor cell type. The identified gene set help to improve hepatic differentiation for therapeutic applications and contribute to the better understanding of liver development. PMID:22378611

Lee, Seung Bum; Seo, Daekwan; Choi, Dongho; Park, Kye-Yoon; Holczbauer, Agnes; Marquardt, Jens U.; Conner, Elizabeth A.; Factor, Valentina M.; Thorgeirsson, Snorri S.

2014-01-01

230

Dinosaur Extinction, Early Childhood Style  

NSDL National Science Digital Library

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 learning in their classroom that helped these young students develop science-process skills such as observation, measurement, and communication. They share their inspiring learning adventure here.

Lesley Valentine-Anand

2008-12-01

231

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.

232

Birds have paedomorphic dinosaur skulls.  

PubMed

The interplay of evolution and development has been at the heart of evolutionary theory for more than a century. Heterochrony—change in the timing or rate of developmental events—has been implicated in the evolution of major vertebrate lineages such as mammals, including humans. Birds are the most speciose land vertebrates, with more than 10,000 living species representing a bewildering array of ecologies. Their anatomy is radically different from that of other vertebrates. The unique bird skull houses two highly specialized systems: the sophisticated visual and neuromuscular coordination system allows flight coordination and exploitation of diverse visual landscapes, and the astonishing variations of the beak enable a wide range of avian lifestyles. Here we use a geometric morphometric approach integrating developmental, neontological and palaeontological data to show that the heterochronic process of paedomorphosis, by which descendants resemble the juveniles of their ancestors, is responsible for several major evolutionary transitions in the origin of birds. We analysed the variability of a series of landmarks on all known theropod dinosaur skull ontogenies as well as outgroups and birds. The first dimension of variability captured ontogeny, indicating a conserved ontogenetic trajectory. The second dimension accounted for phylogenetic change towards more bird-like dinosaurs. Basally branching eumaniraptorans and avialans clustered with embryos of other archosaurs, indicating paedomorphosis. Our results reveal at least four paedomorphic episodes in the history of birds combined with localized peramorphosis (development beyond the adult state of ancestors) in the beak. Paedomorphic enlargement of the eyes and associated brain regions parallels the enlargement of the nasal cavity and olfactory brain in mammals. This study can be a model for investigations of heterochrony in evolutionary transitions, illuminating the origin of adaptive features and inspiring studies of developmental mechanisms. PMID:22722850

Bhullar, Bhart-Anjan S; Marugán-Lobón, Jesús; Racimo, Fernando; Bever, Gabe S; Rowe, Timothy B; Norell, Mark A; Abzhanov, Arhat

2012-07-12

233

How Big Were the Dinosaurs?  

NSDL National Science Digital Library

In this activity (located on page 4 of PDF), learners gain insight into the actual size of dinosaurs and practice making estimations and measurements. Learners measure the lengths of various dinosaurs by measuring lengths of string in field or gym. Learners also estimate and measure these lengths by lying head to foot. Learners also compare and contrast the sizes of different dinosaur species.

Chicago Children's Museum

2011-01-01

234

Dinosaurs in Russia and Mongolia  

E-print Network

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

Benton, Michael

235

Co-Culture of Hematopoietic Stem/Progenitor Cells with Human Osteblasts Favours Mono/Macrophage Differentiation at the Expense of the Erythroid Lineage  

PubMed Central

Hematopoietic stem cells (HSCs) are located in the bone marrow in a specific microenvironment referred as the hematopoietic stem cell niche, where HSCs interact with a variety of stromal cells. Though several components of the stem cell niche have been identified, the regulatory mechanisms through which such components regulate the stem cell fate are still unknown. In order to address this issue, we investigated how osteoblasts (OBs) can affect the molecular and functional phenotype of Hematopoietic Stem/Progenitor Cells (HSPCs) and vice versa. For this purpose, human CD34+ cells were cultured in direct contact with primary human OBs. Our data showed that CD34+ cells cultured with OBs give rise to higher total cell numbers, produce more CFUs and maintain a higher percentage of CD34+CD38- cells compared to control culture. Moreover, clonogenic assay and long-term culture results showed that co-culture with OBs induces a strong increase in mono/macrophage precursors coupled to a decrease in the erythroid ones. Finally, gene expression profiling (GEP) allowed us to study which signalling pathways were activated in the hematopoietic cell fraction and in the stromal cell compartment after coculture. Such analysis allowed us to identify several cytokine-receptor networks, such as WNT pathway, and transcription factors, as TWIST1 and FOXC1, that could be activated by co-culture with OBs and could be responsible for the biological effects reported above. Altogether our results indicate that OBs are able to affect HPSCs on 2 different levels: on one side, they increase the immature progenitor pool in vitro, on the other side, they favor the expansion of the mono/macrophage precursors at the expense of the erythroid lineage. PMID:23349713

Salati, Simona; Lisignoli, Gina; Manferdini, Cristina; Pennucci, Valentina; Zini, Roberta; Bianchi, Elisa; Norfo, Ruggiero; Facchini, Andrea; Ferrari, Sergio; Manfredini, Rossella

2013-01-01

236

Early cretaceous dinosaurs from the sahara.  

PubMed

A major question in Mesozoic biogeography is how the land-based dinosaurian radiation responded to fragmentation of Pangaea. A rich fossil record has been uncovered on northern continents that spans the Cretaceous, when continental isolation reached its peak. In contrast, dinosaur remains on southern continents are scarce. The discovery of dinosaurian skeletons from Lower Cretaceous beds in the southern Sahara shows that several lineages of tetanuran theropods and broad-toothed sauropods had a cosmopolitan distribution across Pangaea before the onset of continental fragmentation. The distinct dinosaurian faunas of Africa, South America, and Asiamerica arose during the Cretaceous by differential survival of once widespread lineages on land masses that were becoming increasingly isolated from one another. PMID:17771449

Sereno, P C; Wilson, J A; Larsson, H C; Dutheil, D B; Sues, H D

1994-10-14

237

Shape of Mesozoic dinosaur richness  

NASA Astrophysics Data System (ADS)

The richness of Mesozoic Dinosauria is examined through the use of a new global database. Mesozoic dinosaurs show a steadily increasing rate of diversification, in part attributable to the development of new innovations driving an increasing variety of behavioral strategies. The data do not suggest that dinosaurs were decreasing in richness leading to extinction during the last ˜10 m.y. of the Cretaceous. Refinement of the dating of dinosaur fossils, rather than the collection of more dinosaurs, is the best way to resolve globally the rate of the Cretaceous-Tertiary dinosaur extinction.

Fastovsky, David E.; Huang, Yifan; Hsu, Jason; Martin-McNaughton, Jamie; Sheehan, Peter M.; Weishampel, David B.

2004-10-01

238

Differentiation of Human Umbilical Cord Matrix Mesenchymal Stem Cells into Neural-Like Progenitor Cells and Maturation into an Oligodendroglial-Like Lineage  

PubMed Central

Mesenchymal stem cells (MSCs) are viewed as safe, readily available and promising adult stem cells, which are currently used in several clinical trials. Additionally, their soluble-factor secretion and multi-lineage differentiation capacities place MSCs in the forefront of stem cell types with expected near-future clinical applications. In the present work MSCs were isolated from the umbilical cord matrix (Wharton's jelly) of human umbilical cord samples. The cells were thoroughly characterized and confirmed as bona-fide MSCs, presenting in vitro low generation time, high proliferative and colony-forming unit-fibroblast (CFU-F) capacity, typical MSC immunophenotype and osteogenic, chondrogenic and adipogenic differentiation capacity. The cells were additionally subjected to an oligodendroglial-oriented step-wise differentiation protocol in order to test their neural- and oligodendroglial-like differentiation capacity. The results confirmed the neural-like plasticity of MSCs, and suggested that the cells presented an oligodendroglial-like phenotype throughout the differentiation protocol, in several aspects sharing characteristics common to those of bona-fide oligodendrocyte precursor cells and differentiated oligodendrocytes. PMID:25357129

Leite, Cristiana; Silva, N. Tatiana; Mendes, Sandrine; Ribeiro, Andreia; de Faria, Joana Paes; Lourenço, Tânia; dos Santos, Francisco; Andrade, Pedro Z.; Cardoso, Carla M. P.; Vieira, Margarida; Paiva, Artur; da Silva, Cláudia L.; Cabral, Joaquim M. S.; Relvas, João B.; Grãos, Mário

2014-01-01

239

Cell Lineage and Regional Identity of Cultured Spinal Cord Neural Stem Cells and Comparison to Brain-Derived Neural Stem Cells  

Microsoft Academic Search

Neural stem cells (NSCs) can be isolated from different regions of the central nervous system. There has been controversy whether regional differences amongst stem and progenitor cells are cell intrinsic and whether these differences are maintained during expansion in culture. The identification of inherent regional differences has important implications for the use of these cells in neural repair. Here, we

Theresa K. Kelly; Stanislav L. Karsten; Daniel H. Geschwind; Harley I. Kornblum; Daphne Soares

2009-01-01

240

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

PubMed

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

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

241

A Transposon-Mediated System for Flexible Control of Transgene Expression in Stem and Progenitor-Derived Lineages  

PubMed Central

Summary 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

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

2015-01-01

242

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

PubMed

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

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

2015-03-10

243

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.

244

Dinosaur National Monument  

NSDL National Science Digital Library

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.

David Whitman

245

7q11.23 dosage-dependent dysregulation in human pluripotent stem cells affects transcriptional programs in disease-relevant lineages.  

PubMed

Cell reprogramming promises to make characterization of the impact of human genetic variation on health and disease experimentally tractable by enabling the bridging of genotypes to phenotypes in developmentally relevant human cell lineages. Here we apply this paradigm to two disorders caused by symmetrical copy number variations of 7q11.23, which display a striking combination of shared and symmetrically opposite phenotypes-Williams-Beuren syndrome and 7q-microduplication syndrome. Through analysis of transgene-free patient-derived induced pluripotent stem cells and their differentiated derivatives, we find that 7q11.23 dosage imbalance disrupts transcriptional circuits in disease-relevant pathways beginning in the pluripotent state. These alterations are then selectively amplified upon differentiation of the pluripotent cells into disease-relevant lineages. A considerable proportion of this transcriptional dysregulation is specifically caused by dosage imbalances in GTF2I, which encodes a key transcription factor at 7q11.23 that is associated with the LSD1 repressive chromatin complex and silences its dosage-sensitive targets. PMID:25501393

Adamo, Antonio; Atashpaz, Sina; Germain, Pierre-Luc; Zanella, Matteo; D'Agostino, Giuseppe; Albertin, Veronica; Chenoweth, Josh; Micale, Lucia; Fusco, Carmela; Unger, Christian; Augello, Bartolomeo; Palumbo, Orazio; Hamilton, Brad; Carella, Massimo; Donti, Emilio; Pruneri, Giancarlo; Selicorni, Angelo; Biamino, Elisa; Prontera, Paolo; McKay, Ronald; Merla, Giuseppe; Testa, Giuseppe

2015-02-01

246

Stress hematopoiesis reveals abnormal control of self-renewal, lineage bias, and myeloid differentiation in Mll partial tandem duplication (Mll-PTD) hematopoietic stem/progenitor cells  

PubMed Central

One mechanism for disrupting the MLL gene in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) is through partial tandem duplication (MLL-PTD); however, the mechanism by which MLL-PTD contributes to MDS and AML development and maintenance is currently unknown. Herein, we investigated hematopoietic stem/progenitor cell (HSPC) phenotypes of Mll-PTD knock-in mice. Although HSPCs (Lin?Sca1+Kit+ (LSK)/SLAM+ and LSK) in MllPTD/WT mice are reduced in absolute number in steady state because of increased apoptosis, they have a proliferative advantage in colony replating assays, CFU-spleen assays, and competitive transplantation assays over wild-type HSPCs. The MllPTD/WT-derived phenotypic short-term (ST)–HSCs/multipotent progenitors and granulocyte/macrophage progenitors have self-renewal capability, rescuing hematopoiesis by giving rise to long-term repopulating cells in recipient mice with an unexpected myeloid differentiation blockade and lymphoid-lineage bias. However, MllPTD/WT HSPCs never develop leukemia in primary or recipient mice, suggesting that additional genetic and/or epigenetic defects are necessary for full leukemogenic transformation. Thus, the Mll-PTD aberrantly alters HSPCs, enhances self-renewal, causes lineage bias, and blocks myeloid differentiation. These findings provide a framework by which we can ascertain the underlying pathogenic role of MLL-PTD in the clonal evolution of human leukemia, which should facilitate improved therapies and patient outcomes. PMID:22740449

Zhang, Yue; Yan, Xiaomei; Sashida, Goro; Zhao, Xinghui; Rao, Yalan; Goyama, Susumu; Whitman, Susan P.; Zorko, Nicholas; Bernot, Kelsie; Conway, Rajeana M.; Witte, David; Wang, Qian-fei; Tenen, Daniel G.; Xiao, Zhijian; Marcucci, Guido; Mulloy, James C.; Grimes, H. Leighton; Caligiuri, Michael A.

2012-01-01

247

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

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.

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

248

Biliary tree stem/progenitor cells in glands of extrahepatic and intraheptic bile ducts: an anatomical in situ study yielding evidence of maturational lineages  

PubMed Central

Stem/progenitors have been identified intrahepatically in the canals of Hering and extrahepatically in glands of the biliary tree. Glands of the biliary tree (peribiliary glands) are tubulo-alveolar glands with mucinous and serous acini, located deep within intrahepatic and extrahepatic bile ducts. We have shown that biliary tree stem/progenitors (BTSCs) are multipotent, giving rise in vitro and in vivo to hepatocytes, cholangiocytes or pancreatic islets. Cells with the phenotype of BTSCs are located at the bottom of the peribiliary glands near the fibromuscular layer. They are phenotypically heterogeneous, expressing transcription factors as well as surface and cytoplasmic markers for stem/progenitors of liver (e.g. SOX9/17), pancreas (e.g. PDX1) and endoderm (e.g. SOX17, EpCAM, NCAM, CXCR4, Lgr5, OCT4) but not for mature markers (e.g. albumin, secretin receptor or insulin). Subpopulations co-expressing liver and pancreatic markers (e.g. PDX1+/SOX17+) are EpCAM+/?, and are assumed to be the most primitive of the BTSC subpopulations. Their descendants undergo a maturational lineage process from the interior to the surface of ducts and vary in the mature cells generated: pancreatic cells in hepatopancreatic ducts, liver cells in large intrahepatic bile ducts, and bile duct cells along most of the biliary tree. We hypothesize that there is ongoing organogenesis throughout life, with BTSCs giving rise to hepatic stem cells in the canals of Hering and to committed progenitors within the pancreas. The BTSCs are likely to be central to normal tissue turnover and injury repair and to be key elements in the pathophysiology of liver, pancreas and biliary tree diseases, including oncogenesis. PMID:22136171

Carpino, Guido; Cardinale, Vincenzo; Onori, Paolo; Franchitto, Antonio; Berloco, Pasquale Bartolomeo; Rossi, Massimo; Wang, Yunfang; Semeraro, Rossella; Anceschi, Maurizio; Brunelli, Roberto; Alvaro, Domenico; Reid, Lola M; Gaudio, Eugenio

2012-01-01

249

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

PubMed Central

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

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

2015-01-01

250

A Child Centered Approach to Dinosaurs.  

ERIC Educational Resources Information Center

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)

Strader, William H.; Rinker, Catherine A.

1989-01-01

251

Relative Speed of Dinosaurs  

NSDL National Science Digital Library

In this activity, learners interpret three trackways and use measurements and a formula to infer the relative speed of dinosaurs. A portion of the activity details how students can create their own trackways and evaluate the accuracy of the formula. This step-by-step lesson plan includes an illustrated look at stride length and a reproducible worksheet for learners to complete.

2012-08-01

252

Kindergartners Love Dinosaurs  

ERIC Educational Resources Information Center

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…

Stollon, Marcy

2005-01-01

253

Activated Notch1 alters differentiation of embryonic stem cells into mesodermal cell lineages at multiple stages of development  

Microsoft Academic Search

Signals of Notch transmembrane receptors function to regulate a wide variety of developmental cell fates. Here we investigate the role of Notch signaling in the development of mesodermal cell types by expressing a tamoxifen-inducible, activated form of Notch1 in embryonic stem cells (ESC). For differentiation of ESC into first mesodermal progenitor cells and then endothelial, mural, cardiac muscle and hematopoietic

Timm Schroeder; Franziska Meier-Stiegen; Ralf Schwanbeck; Hanna Eilken; Satomi Nishikawa; Robert Häsler; Stefan Schreiber; Georg W. Bornkamm; Shin-Ichi Nishikawa; Ursula Just

2006-01-01

254

BMP4Expressing Muscle-Derived Stem Cells Differentiate into Osteogenic Lineage and Improve Bone Healing in Immunocompetent Mice  

Microsoft Academic Search

Recent advances in molecular biology have led the way for novel approaches to improve bone healing. The ideal growth factor, vector, and delivery systems for producing bone in an immune competent animal model, however, have yet to be identified. Using a retrovirus encoding BMP4 and recently isolated muscle-derived stem cells (MDSCs), we demonstrated the following: MDSCs undergo osteogenic differentiation in

Vonda J. Wright; Hairong Peng; Arvydas Usas; Brett Young; Brian Gearhart; James Cummins; Johnny Huard

2002-01-01

255

Motor Neuron Differentiation from Pluripotent Stem Cells and Other Intermediate Proliferative Precursors that can be Discriminated by Lineage Specific Reporters.  

PubMed

We have used a four stage protocol to generate spinal motor neurons (MNs) from human embryonic stem cells (ESCs) and human induced pluripotent stem cells (iPSCs). These stages include the pluripotent stem cell (PSC) stage, neural stem cell (NSC) stage, OLIG2 expressing motor neuron precursor (MNP) stage, and HB9 expressing mature-MN stage. To optimize the differentiation protocol reporter lines marking the NSC and MNP stages were used. The NSC stage is a pro-proliferative precursor stage at which cells can be directed to differentiate to other neural types like cortical neurons also, in addition to MNs; thus, NSCs can be expanded and stored for future differentiation to different neural types thereby, shortening the differentiation interval as compared to the complete process of differentiation from ESCs or iPSCs. Additionally, we find that OLIG2 positive cells at the MNP stage can be cryopreserved and then recovered to continue the process of MN differentiation, thereby providing a highly stable and reproducible technique for bulk differentiation. MNPs were differentiated to MNs expressing the marker HB9 demonstrating that mature-MNs can be generated with this protocol. PMID:25091426

Jha, Balendu Shekhar; Rao, Mahendra; Malik, Nasir

2015-02-01

256

Differentiation of pluripotent embryonic stem cells into the neuronal lineage in vitro gives rise to mature inhibitory and excitatory neurons  

Microsoft Academic Search

Embryonic stem (ES) cells represent a suitable model to analyze cell differentiation processes in vitro. Here, we report that pluripotent ES cells of the line BLC 6 differentiate in vitro into neuronal cells possessing the complex electrophysiological and immunocytochemical properties of postmitotic nerve cells. In the course of differentiation BLC 6-derived neurons differentially express voltagedependent (K+, Na+, Ca2+) and receptor-operated

Carsten Strübing; Gudrun Ahnert-Hilger; Jin Shan; Bertram Wiedenmann; Jürgen Hescheler; Anna M. Wobus

1995-01-01

257

Hematopoiesis in steady-state versus stress: self-renewal, lineage fate choice, and the conversion of danger signals into cytokine signals in hematopoietic stem cells.  

PubMed

Long-term hematopoietic stem cells (LT-HSCs) replenish the innate and adaptive immune compartments throughout life. Although significant progress has defined the major transcription factors that regulate lineage specification, the architectural proteins that globally coordinate DNA methylation, histone modification, and changes in gene expression are poorly defined. Provocative new studies establish the chromatin organizer special AT-rich binding protein 1 (Satb1) as one such global regulator in LT-HSCs. Satb1 is a nuclear organizer that partitions chromatin through the formation of cage-like structures. By integrating epigenetic and transcriptional pathways, Satb1 coordinates LT-HSC division, self-renewal, and lymphoid potential. Unexpected among the assortment of genes under Satb1 control in hematopoietic stem cells (HSCs) are cytokines, a finding that takes on additional importance with the provocative finding that short-term HSCs and downstream multipotent progenitors are potent and biologically relevant cytokine secretors during stress-mediated hematopoiesis. Together, these studies reveal a new mechanism of fate regulation and an unforeseen functional capability of HSCs. PMID:25128551

Borghesi, Lisa

2014-09-01

258

Human Induced Hepatic Lineage-Oriented Stem Cells: Autonomous Specification of Human iPS Cells toward Hepatocyte-Like Cells without Any Exogenous Differentiation Factors  

PubMed Central

Preparing targeted cells for medical applications from human induced pluripotent stem cells (hiPSCs) using growth factors, compounds, or gene transfer has been challenging. Here, we report that human induced hepatic lineage-oriented stem cells (hiHSCs) were generated and expanded as a new type of hiPSC under non-typical coculture with feeder cells in a chemically defined hiPSC medium at a very high density. Self-renewing hiHSCs expressed markers of both human embryonic stem cells (hESCs) and hepatocytes. Those cells were highly expandable, markedly enhancing gene expression of serum hepatic proteins and cytochrome P450 enzymes with the omission of FGF-2 from an undefined hiPSC medium. The hepatic specification of hiHSCs was not attributable to the genetic and epigenetic backgrounds of the starting cells, as they were established from distinct donors and different types of cells. Approximately 90% of hiHSCs autonomously differentiated to hepatocyte-like cells, even in a defined minimum medium without any of the exogenous growth factors necessary for hepatic specification. After 12 days of this culture, the differentiated cells significantly enhanced gene expression of serum hepatic proteins (ALB, SERPINA1, TTR, TF, FABP1, FGG, AGT, RBP4, and AHSG), conjugating enzymes (UGT2B4, UGT2B7, UGT2B10, GSTA2, and GSTA5), transporters (SULT2A1, SLC13A5, and SLCO2B1), and urea cycle-related enzymes (ARG1 and CPS1). In addition, the hepatocyte-like cells performed key functions of urea synthesis, albumin secretion, glycogen storage, indocyanine green uptake, and low-density lipoprotein uptake. The autonomous hepatic specification of hiHSCs was due to their culture conditions (coculture with feeder cells in a defined hiPSC medium at a very high density) in self-renewal rather than in differentiation. These results suggest the feasibility of preparing large quantities of hepatocytes as a convenient and inexpensive hiPSC differentiation. Our study also suggests the necessity of optimizing culture conditions to generate other specific lineage-oriented hiPSCs, allowing for a very simple differentiation. PMID:25875613

Yanagi, Satoshi; Kato, Chika; Takashima, Ryokichi; Kobayashi, Eiji; Hagiwara, Keitaro; Ochiya, Takahiro

2015-01-01

259

Dinosaurs: Bigger Than You Think  

NSDL National Science Digital Library

In this classroom activity, middle school students examine the wide-ranging sizes of dinosaurs. The activity opens with background information about the enormous range of dinosaur sizes and a classroom discussion in which students describe the size of some of the dinosaurs they know. Then, working from gridded drawings which are provided, students create either a life-size drawing of a Tyrannosaurus rex head or a life-size drawing of a complete Protoceratops.

260

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

Microsoft Academic Search

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

Xuejun Xin; Mohammad Hussain; Jeremy J. Mao

2007-01-01

261

What's in a Dinosaur Name?  

NSDL National Science Digital Library

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.

Rick Crosslin

2004-01-01

262

Weigh a Dinosaur  

NSDL National Science Digital Library

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.

Andrew Heckert

263

Biomechanics of Running Indicates Endothermy in Bipedal Dinosaurs  

PubMed Central

Background One of the great unresolved controversies in paleobiology is whether extinct dinosaurs were endothermic, ectothermic, or some combination thereof, and when endothermy first evolved in the lineage leading to birds. Although it is well established that high, sustained growth rates and, presumably, high activity levels are ancestral for dinosaurs and pterosaurs (clade Ornithodira), other independent lines of evidence for high metabolic rates, locomotor costs, or endothermy are needed. For example, some studies have suggested that, because large dinosaurs may have been homeothermic due to their size alone and could have had heat loss problems, ectothermy would be a more plausible metabolic strategy for such animals. Methodology/Principal Findings Here we describe two new biomechanical approaches for reconstructing the metabolic rate of 14 extinct bipedal dinosauriforms during walking and running. These methods, well validated for extant animals, indicate that during walking and slow running the metabolic rate of at least the larger extinct dinosaurs exceeded the maximum aerobic capabilities of modern ectotherms, falling instead within the range of modern birds and mammals. Estimated metabolic rates for smaller dinosaurs are more ambiguous, but generally approach or exceed the ectotherm boundary. Conclusions/Significance Our results support the hypothesis that endothermy was widespread in at least larger non-avian dinosaurs. It was plausibly ancestral for all dinosauriforms (perhaps Ornithodira), but this is perhaps more strongly indicated by high growth rates than by locomotor costs. The polarity of the evolution of endothermy indicates that rapid growth, insulation, erect postures, and perhaps aerobic power predated advanced “avian” lung structure and high locomotor costs. PMID:19911059

Pontzer, Herman; Allen, Vivian; Hutchinson, John R.

2009-01-01

264

A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids  

PubMed Central

Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features. Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives. The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives. The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods. PMID:19129109

Novas, Fernando E.; Pol, Diego; Canale, Juan I.; Porfiri, Juan D.; Calvo, Jorge O.

2008-01-01

265

A bizarre Cretaceous theropod dinosaur from Patagonia and the evolution of Gondwanan dromaeosaurids.  

PubMed

Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features. Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives. The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives. The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods. PMID:19129109

Novas, Fernando E; Pol, Diego; Canale, Juan I; Porfiri, Juan D; Calvo, Jorge O

2009-03-22

266

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

E-print Network

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

Holtz Jr., Thomas R.

267

Deciphering hematopoietic stem cells in their niches: a critical appraisal of genetic models, lineage tracing, and imaging strategies.  

PubMed

In recent years, technical developments in mouse genetics and imaging equipment have substantially advanced our understanding of hematopoietic stem cells (HSCs) and their niche. The availability of numerous Cre strains for targeting HSCs and microenvironmental cells provides extensive flexibility in experimental design, but it can also pose significant challenges due to strain-specific differences in cell specificity. Here we outline various genetic approaches for isolating, detecting, and ablating HSCs and niche components and provide a guide for advantages and caveats to consider. We also discuss opportunities and limitations presented by imaging technologies that allow investigation of HSC behavior in situ. PMID:24209759

Joseph, Chacko; Quach, Julie M; Walkley, Carl R; Lane, Steven W; Lo Celso, Cristina; Purton, Louise E

2013-11-01

268

Theropod Dinosaurs:The "Beast-Footed" Carnivorous Dinosaurs  

NSDL National Science Digital Library

The Theropod (meaning "beast-footed") dinosaurs are a diverse group of bipedal saurischians. They include the largest terrestrial carnivores ever to have made the earth tremble. This page provides an explanation of the general characteristics that place dinosaurs in this group, followed by detailed information on the three major groups: Herrerasauridae, Ceratosauria, and Tetanurae. Active links within the site allow for further study.

269

A Dinosaur's Neighborhood  

NSDL National Science Digital Library

This website is part of National Geographic's Xpeditions Hall, and offers videos, links to related sites, and other interactive features to help students understand the importance of environment as it relates to organisms and where they choose to live. This activity uses the dinosaur Tyrannosaurus rex as an example and prompts students to find out what kind of environment would best suit this creature's needs. These lesson plans were written by educators and have been tested in the classroom.

270

Dinosaur Bone Experiments  

NSDL National Science Digital Library

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.

2013-11-07

271

Dinosaurs in Patagonia  

NSDL National Science Digital Library

This Web site is a firsthand report from an expedition to Patagonia in which the first dinosaur embryos with fossilized skin were found. It tells the story of the find, which was made by scientists who were actually looking for early birds and their ancestors. There are two short English and Spanish audio recordings. A select list of books and articles by the expedition's two lead scientists, including abstracts of and excerpts from their work is included.

272

Shoebox Dinosaur Dig Site  

NSDL National Science Digital Library

In this activity, (on page 6 of the PDF) learners participate in a hands-on fossil excavation. Groups of learners will receive a shoebox full off sand in which several chicken bones have been buried at various levels. After preparing string grid lines over the “dig site,” they will carefully brush away sand and record observations as each bone is discovered. Relates to linked video, DragonflyTV GPS: Dinosaurs.

Twin Cities Public Television, Inc.

2006-01-01

273

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

PubMed Central

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

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

2011-01-01

274

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

275

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

This lesson will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. This lesson focuses on what we have learned and can learn from fossils. The follow-up lesson, Dinosaurs Fossils - Uncovering the Facts, explores what information can be discerned by comparing fossils to living organisms.

Science Netlinks

2001-10-20

276

Making Sense of Dinosaur Tracks  

ERIC Educational Resources Information Center

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…

MacKenzie, Ann Haley; McDowell, Brian

2012-01-01

277

If You Were a Dinosaur...  

ERIC Educational Resources Information Center

Dinosaurs are one of those science topics that draw children in and teach them about concepts like measuring and using descriptive language. Learning about dinosaurs, although not hands-on like observing and recording caterpillar growth, develops critical thinking and introduces animal diversity and the relations between body form and function.…

Ashbrook, Peggy

2010-01-01

278

Adipose-derived stem cell adhesion on laminin-coated microcarriers improves commitment toward the cardiomyogenic lineage.  

PubMed

For tissue-engineering studies of the infarcted heart it is essential to identify a source of cells that may provide cardiomyocyte progenitors, which is easy to amplify, accessible in adults, and allowing autologous grafts. Preclinical studies have shown that human adipose-derived stem cells (ADSCs) can differentiate into cardiomyocyte-like cells and improve heart function in myocardial infarction. We have developed pharmacologically active microcarriers (PAMs) which are biodegradable and biocompatible polymeric microspheres conveying cells on their biomimetic surface, therefore providing an adequate three-dimensional (3D) microenvironment. Moreover, they can release a growth factor in a prolonged manner. In order to implement ADSCs and PAMs for cardiac tissue engineering we first defined the biomimetic surface by studying the influence of matrix molecules laminin (LM) and fibronectin (FN), in combination with growth factors present in the cardiogenic niche, to further enhance the in vitro cardiac differentiation of ADSCs. We demonstrated that LM increased the expression of cardiac markers (Nkx2.5, GATA4, MEF2C) by ADSCs after 2 weeks in vitro. Interestingly, our results suggest that the 3D support provided by PAMs with a LM biomimetic surface (LM-PAMs) further enhanced the expression of cardiac markers and induced the expression of a more mature contractile protein, cardiac troponin I, compared with the 2D differentiating conditions after only 1 week in culture. The enrichment of the growth-factor cocktail with TGF-?1 potentiated the cardiomyogenic differentiation. These results suggest that PAMs offering a LM biomimetic surface may be efficiently used for applications combining adult stem cells in tissue-engineering strategies of the ischemic heart. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1828-1839, 2015. PMID:25098676

Karam, Jean-Pierre; Bonafè, Francesca; Sindji, Laurence; Muscari, Claudio; Montero-Menei, Claudia N

2015-05-01

279

Cell Lineage and Regional Identity of Cultured Spinal Cord Neural Stem Cells and Comparison to Brain-Derived Neural Stem Cells  

E-print Network

Neural stem cells (NSCs) can be isolated from different regions of the central nervous system. There has been controversy whether regional differences amongst stem and progenitor cells are cell intrinsic and whether these differences are maintained during expansion in culture. The identification of inherent regional differences has important implications for the use of these cells in neural repair. Here, we compared NSCs derived from the spinal cord and embryonic cortex. We found that while cultured cortical and spinal cord derived NSCs respond similarly to mitogens and are equally neuronogenic, they retain and maintain through multiple passages gene expression patterns indicative of the region from which they were isolated (e.g Emx2 and HoxD10). Further microarray analysis identified 229 genes that were differentially expressed between cortical and spinal cord derived neurospheres, including many Hox genes, Nuclear receptors, Irx3, Pace4, Lhx2, Emx2 and Ntrk2. NSCs in the cortex express LeX. However, in the embryonic spinal cord there are two lineally

280

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.

281

Dinosaur Skull and Body Length Predictions  

NSDL National Science Digital Library

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.

Twin Cities Public Television, Inc.

2007-01-01

282

Differentiation and lineage selection of mouse embryonic stem cells in a stirred bench scale bioreactor with automated process control.  

PubMed

It is well established that embryonic stem (ES) cells can differentiate into functional cardiomyocytes in vitro. ES-derived cardiomyocytes could be used for pharmaceutical and therapeutic applications, provided that they can be generated in sufficient quantity and with sufficient purity. To enable large-scale culture of ES-derived cells, we have developed a robust and scalable bioprocess that allows direct embryoid body (EB) formation in a fully controlled, stirred 2 L bioreactor following inoculation with a single cell suspension of mouse ES cells. Utilizing a pitched-blade-turbine, parameters for optimal cell expansion as well as efficient ES cell differentiation were established. Optimization of stirring conditions resulted in the generation of high-density suspension cultures containing 12.5 x 10(6) cells/mL after 9 days of differentiation. Approximately 30%-40% of the EBs formed in this process vigorously contracted, indicating robust cardiomyogenic induction. An ES cell clone carrying a recombinant DNA molecule comprised of the cardiomyocyte-restricted alpha myosin heavy chain (alphaMHC) promoter and a neomycin resistance gene was used to establish the utility of this bioprocess to efficiently generate ES-derived cardiomyocytes. The genetically engineered ES cells were cultured directly in the stirred bioreactor for 9 days, followed by antibiotic treatment for another 9 days. The protocol resulted in the generation of essentially pure cardiomyocyte cultures, with a total yield of 1.28 x 10(9) cells in a single 2 L bioreactor run. This study thus provides an important step towards the large-scale generation of ES-derived cells for therapeutic and industrial applications. PMID:16189818

Schroeder, Magnus; Niebruegge, Sylvia; Werner, Andreas; Willbold, Elmar; Burg, Monika; Ruediger, Manfred; Field, Loren J; Lehmann, Juergen; Zweigerdt, Robert

2005-12-30

283

The Story of Dinosaur Evolution  

NSDL National Science Digital Library

In this case study, students write their own “evolution stories” based on information taken from a review article by Paul Sereno on the evolution of dinosaurs published in Science magazine. In the process, they learn to distinguish between the three major groups of dinosaurs based on physical characteristics; trace the ancestry of individual dinosaur species; and interpret a complex evolutionary tree that includes extinctions, speciation events, and changes in the number of taxa over time. The case was designed for use in non-majors introductory science courses, but could also be used in majors’ courses.

Jeffrey Scott Coker

2005-01-01

284

T-Cell Lineage Determination  

PubMed Central

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

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

2010-01-01

285

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

PubMed Central

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

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

2012-01-01

286

Pluripotent stem cell model reveals essential roles for miR-450b-5p and miR-184 in embryonic corneal lineage specification.  

PubMed

Approximately 6 million people worldwide are suffering from severe visual impairments or blindness due to corneal diseases. Corneal allogeneic transplantation is often required to restore vision; however, shortage in corneal grafts and immunorejections remain major challenges. The molecular basis of corneal diseases is poorly understood largely due to lack of appropriate cellular models. Here, we described a robust differentiation of human-induced pluripotent stem cells (hiPSCs) derived from hair follicles or skin fibroblasts into corneal epithelial-like cells. We found that BMP4, coupled with corneal fibroblast-derived conditioned medium and collagen IV allowed efficient corneal epithelial commitment of hiPSCs in a manner that recapitulated corneal epithelial lineage development with high purity. Organotypic reconstitution assays suggested the ability of these cells to stratify into a corneal-like epithelium. This model allowed us identifying miR-450b-5p as a molecular switch of Pax6, a major regulator of eye development. miR-450b-5p and Pax6 were reciprocally distributed at the presumptive epidermis and ocular surface, respectively. miR-450b-5p inhibited Pax6 expression and corneal epithelial fate in vitro, altogether, suggesting that by repressing Pax6, miR-450b-5p triggers epidermal specification of the ectoderm, while its absence allows ocular epithelial development. Additionally, miR-184 was detectable in early eye development and corneal epithelial differentiation of hiPSCs. The knockdown of miR-184 resulted in a decrease in Pax6 and K3, in line with recent findings showing that a point mutation in miR-184 leads to corneal dystrophy. Altogether, these data indicate that hiPSCs are valuable for modeling corneal development and may pave the way for future cell-based therapy. PMID:22367714

Shalom-Feuerstein, Ruby; Serror, Laura; De La Forest Divonne, Stephanie; Petit, Isabelle; Aberdam, Edith; Camargo, Livia; Damour, Odile; Vigouroux, Clotilde; Solomon, Abraham; Gaggioli, Cédric; Itskovitz-Eldor, Joseph; Ahmad, Sajjad; Aberdam, Daniel

2012-05-01

287

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.

288

A distinct dinosaur life history?  

Microsoft Academic Search

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

David J. Varricchio

2011-01-01

289

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.

290

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).

291

Counting dinosaurs: how many kinds were there?  

PubMed Central

Dinosaurs figure prominently in discussions of mass extinctions and evolutionary metrics, but their usefulness is hampered by archaic taxonomy, imprecise biostratigraphy, and imperfect preservation that bias our understanding of dinosaur diversity. A critical evaluation shows that of 540 genera and 800 species of dinosaurs proposed since 1824, 285 genera and 336 species are probably valid. Nearly half of all genera are based on a single specimen, and complete skulls and skeletons are known for only 20% of all dinosaurs. Dinosaurs are known from every continent. Countries with the greatest known diversity of dinosaurs are (in descending order) the United States, Mongolia, China, Canada, England, and Argentina; the greatest future increases may be expected from Argentina and China. Nearly half of all dinosaur genera are of latest Cretaceous age (Campanian or Maastrichtian). Estimates of the average duration of a dinosaur genus range from 5 million to 10.5 million years, with the most likely value about 7.7 million years. Dinosaurs evolved as rapidly as Cenozoic mammals. Global dinosaur diversity during the Campanian and Maastrichtian is estimated at 100 genera per stage, using a logistic model to estimate future discoveries. A model of increasing diversity and a bottleneck model compensate for the biasis in the preserved fossil record. The number of dinosaurs that have ever lived is estimated at 900-1200 genera. The fossil record of dinosaurs is presently about 25% complete. Dinosaurs disappeared in the Maastrichtian near the peak of their historic diversity. PMID:2217192

Dodson, P

1990-01-01

292

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

E-print Network

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

Benton, Michael

293

The extinction of the dinosaurs.  

PubMed

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

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

294

What Killed the Dinosaurs?  

NSDL National Science Digital Library

At this site the question of the extinction of the dinosaurs takes the form of an interactive matrix. With the hypotheses in the left margin and the types of evidence along the bottom, the resulting squares are indicated in cases where the evidence supports the hypothesis. Students can click on hypotheses to view an animated description, click on an evidence element to get a definition, or click on a marked square in the grid to see how a particular piece of evidence supports a particular hypothesis. Hypotheses include asteroid impact, volcanism, mammal competition and continental drift while the listed evidence elements are rare metal, melted rock, fractured crystals, fossil record, lava flows, sea level, and impact crater.

2007-12-12

295

Dinosaur peptides suggest mechanisms of protein survival  

E-print Network

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 ...

San Antonio, James D.

296

Giant European dinosaur found in Spain  

NSDL National Science Digital Library

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.

American Association for the Advancement of Science (AAAS; )

2006-12-21

297

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.

298

Dinosaur Names: Common and Science Names  

NSDL National Science Digital Library

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.

2014-04-14

299

Newsflash! Dinosaur Pages at the UCMP  

NSDL National Science Digital Library

This site, sponsored by the University of California Museum of Paleontology, provides information on most classes of dinosaurs, arranged in outline form on the basis of evolutionary relationships. Links also lead to birds and their relationship with dinosaurs. Also, there is a link to flying reptiles, which are neither dinosaurs nor birds.

300

Epidemiologic study of tumors in dinosaurs  

Microsoft Academic Search

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

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

2003-01-01

301

The origin and early radiation of dinosaurs  

Microsoft Academic Search

Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of

Stephen L. Brusatte; Sterling J. Nesbitt; Randall B. Irmis; Richard J. Butler; Michael J. Benton; Mark A. Norell

2010-01-01

302

Plumage Color Patterns of an Extinct Dinosaur  

Microsoft Academic Search

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

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

303

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.

304

Simulating Dinosaur Digestion in the Classroom.  

ERIC Educational Resources Information Center

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,…

Peczkis, Jan

1992-01-01

305

Dinosaur Body Temperatures Determined from Isotopic (13  

E-print Network

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

Schöne, Bernd R.

306

Teaching Perspective The Bristol Dinosaur Project  

E-print Network

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

Benton, Michael

307

Large Mesozoic mammals fed on young dinosaurs  

E-print Network

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

Sullivan, Jack

308

The Development of a Virtual Dinosaur Museum  

ERIC Educational Resources Information Center

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…

Tarng, Wernhuar; Liou, Hsin-Hun

2007-01-01

309

Dinosaurs and the Cretaceous Terrestrial Revolution  

E-print Network

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

Benton, Michael

310

The Evolutionary History of Sauropod Dinosaurs  

Microsoft Academic Search

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

Paul Upchurch

1995-01-01

311

Measuring Dinosaur Speed from Trackways  

NSDL National Science Digital Library

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.

Bret Bennington

312

Feeding height stratification among the herbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta, Canada  

PubMed Central

Background Herbivore coexistence on the Late Cretaceous island continent of Laramidia has been a topic of great interest, stemming from the paradoxically high diversity and biomass of these animals in relation to the relatively small landmass available to them. Various hypotheses have been advanced to account for these facts, of which niche partitioning is among the most frequently invoked. However, despite its wide acceptance, this hypothesis has not been rigorously tested. This study uses the fossil assemblage from the Dinosaur Park Formation of Alberta as a model to investigate whether niche partitioning facilitated herbivorous dinosaur coexistence on Laramidia. Specifically, the question of feeding height stratification is examined in light of the role it plays in facilitating modern ungulate coexistence. Results Most herbivorous dinosaur species from the Dinosaur Park Formation were restricted to feeding no higher than approximately 1 m above the ground. There is minimal evidence for feeding height partitioning at this level, with ceratopsids capable of feeding slightly higher than ankylosaurs, but the ecological significance of this is ambiguous. Hadrosaurids were uniquely capable of feeding up to 2 m quadrupedally, or up to 5 m bipedally. There is no evidence for either feeding height stratification within any of these clades, or for change in these ecological relationships through the approximately 1.5 Ma record of the Dinosaur Park Formation. Conclusions Although we cannot reject the possibility, we find no good evidence that feeding height stratification, as revealed by reconstructed maximum feeding heights, played an important role in facilitating niche partitioning among the herbivorous dinosaurs of Laramidia. Most browsing pressure was concentrated in the herb layer, although hadrosaurids were capable of reaching shrubs and low-growing trees that were out of reach from ceratopsids, ankylosaurs, and other small herbivores, effectively dividing the herbivores in terms of relative abundance. Sympatric hadrosaurids may have avoided competing with one another by feeding differentially using bipedal and quadrupedal postures. These ecological relationships evidently proved to be evolutionarily stable because they characterize the herbivore assemblage of the Dinosaur Park Formation through time. If niche partitioning served to facilitate the rich diversity of these animals, it may have been achieved by other means in addition to feeding height stratification. Consideration of other feeding height proxies, including dental microwear and skull morphology, may help to alleviate problems of underdetermination identified here. PMID:23557203

2013-01-01

313

First Dinosaurs from Saudi Arabia  

PubMed Central

Dinosaur remains from the Arabian subcontinent are exceedingly rare, and those that have been documented manifest indeterminate affinities. Consequently the discovery of a small, but diagnostic, accumulation of elements from Campanian-Maastrichtian (?75 Ma) deposits in northwestern Saudi Arabia is significant because it constitutes the first taxonomically identifiable dinosaur material described from the Arabian Peninsula. The fossils include a series of possible lithostrotian titanosaur caudal vertebrae, and some isolated theropod marginal teeth that share unique character states and metric parameters (analyzed using multivariate statistical methods) with derived abelisaurids – this is the first justifiable example of a non-avian carnivorous dinosaur clade from Arabia. The recognition of titanosaurians and abelisaurids from Saudi Arabia extends the palaeogeographical range of these groups along the entire northern Gondwanan margin during the latest Cretaceous. Moreover, given the extreme paucity of coeval occurrences elsewhere, the Saudi Arabian fossils provide a tantalizing glimpse into dinosaurian assemblage diversity within the region. PMID:24386326

Kear, Benjamin P.; Rich, Thomas H.; Vickers-Rich, Patricia; Ali, Mohammed A.; Al-Mufarreh, Yahya A.; Matari, Adel H.; Al-Massari, Abdu M.; Nasser, Abdulaziz H.; Halawani, Mohammed A.

2013-01-01

314

The earliest known sauropod dinosaur.  

PubMed

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

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

2000-09-01

315

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

316

Fossil quality and naming dinosaurs.  

PubMed

The intense interest in dinosaurs through the past 30 years might have led to an increase in poor practice in naming new species. A review of the data shows that the reverse is the case. For 130 years, from the 1820s to the 1950s, most new species of dinosaurs were based on scrappy and incomplete material. After 1960, the majority of new species have been based on complete skulls or skeletons, and sometimes on materials from several individuals. This switch in the quality of type specimens corresponds to the recent explosive renaissance of interest in dinosaurs, during which the number of new species named per year has risen, from three or four in the 1950s, to thirty or more today. The pattern of specimen quality varies by continent, with the highest proportion of new species based on good material in North America, then Asia, then South America, then Africa and finally Europe. This ranking reflects a complex pattern of perhaps overstudy in Europe, immensely rich reserves of new dinosaur materials in North America and Asia, and a relative paucity in South America and Africa. PMID:18796391

Benton, Michael J

2008-12-23

317

Dinosaurs: The Past Is Present.  

ERIC Educational Resources Information Center

Justifies including dinosaurs as a topic in the curriculum for young children if approached from the inquiry processes of science exploration. Suggests that this topic encourages observational, classification, and communication skills and the ability to compare, hypothesize, and derive conclusions. (AS)

Seefeldt, Carol; Tinney, Sallie

1985-01-01

318

Binocular vision in theropod dinosaurs  

Microsoft Academic Search

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,

Kent A. Stevens

2006-01-01

319

The End of the Dinosaurs  

NASA Astrophysics Data System (ADS)

The discovery of the giant Chicxulub impact crater, buried off the coast of Mexico, unveiled the solution to one of Earth's greatest mysteries--what killed the dinosaurs. Scientists uncovered physical evidence to explain the mass extinction that rocked the Earth 65 million years ago. Step-by-step, The End of the Dinosaurs: Chicxulub Crater and Mass Extinctions tells this great scientific detective story. Charles Frankel recounts the birth of the cosmic hypothesis, which holds that the crash of a meteor on the Earth's surface killed two-thirds of life and all the dinosaurs. He first provides a dramatic account of the impact and its aftermath. Frankel then goes on to detail the controversy that preceded the acceptance of the cosmic hypothesis, the search for the crater, its discovery and ongoing exploration, and the effect of the giant impact on the biosphere. In addition, he reviews other mass extinctions in the fossil record and the threat of asteroids and comets to our planet today. More than 70 photographs and diagrams enhance and help illustrate the material. Filled with drama and interesting science, The End of the Dinosaurs will readily appeal to both the general reader fascinated with the subject and the specialist always searching for more clues to this great mystery. Charles Frankel has written a number of articles on the earth sciences in books and magazines. His many books include Volcanoes of the Solar System (Cambridge University Press 1996).

Frankel, Charles

1999-10-01

320

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

E-print Network

's bestkept secrets: a graveyard containing the remains of at least a dozen dinosaurs. Excavating the bones, occasionally, even pruning and grafting the dinosaur family tree. A hotbed for fossil hunters Although

Machel, Hans

321

The Evolution and Extinction of the Dinosaurs  

NASA Astrophysics Data System (ADS)

Written for non-specialists, this detailed survey of dinosaur origins, diversity, and extinction is designed as a series of successive essays covering important and timely topics in dinosaur paleobiology, such as "warm-bloodedness," birds as living dinosaurs, the new, non-flying feathered dinosaurs, dinosaur functional morphology, and cladistic methods in systematics. Its explicitly phylogenetic approach to the group is that taken by dinosaur specialists. The book is not an edited compilation of the works of many individuals, but a unique, cohesive perspective on Dinosauria. Lavishly illustrated with hundreds of new, specially commissioned illustrations by John Sibbick, world-famous illustrator of dinosaurs, the volume includes multi-page drawings as well as sketches and diagrams. First edition Hb (1996): 0-521-44496-9 David E. Fastovsky is Professor of Geosciences at the University of Rhode Island. Fastovsky, the author of numerous scientific publications dealing with Mesozoic vertebrate faunas and their ancient environments, is also scientific co-Editor of Geology. He has undertaken extensive fieldwork studying dinosaurs and their environments in Montana, North Dakota, Arizona, Mexico, and Mongolia. David B. Weishampel is a professor at the Center for Functional Anatomy and Evolution at Johns Hopkins University, School of Medicine. Weishampel is best known for discovering, researching, and naming several rare European dinosaur species. During the 1980s Weishampel gained fame for his work with American paleontologist Jack Horner and later named the famous plant-eating, egg-laying Orodromeus, Horner. Now, a decade after his pioneering studies with Horner, Weishampel is most widely known for his current work on the Romanian dinosaur fauna. He is the author and co-author of many titles, including The Dinosaur Papers, 1676-1906 (Norton, 2003); The Dinosauria, (University of California, 1990); and Dinosaurs of the East Coast, (Johns Hopkins University Press, 1996).

Fastovsky, David E.; Weishampel, David B.

2005-02-01

322

Network representation of a child's dinosaur knowledge  

Microsoft Academic Search

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

Michelene T. Chi; Randi D. Koeske

1983-01-01

323

Extreme convergence in the body plans of an early suchian (Archosauria) and ornithomimid dinosaurs (Theropoda)  

PubMed Central

Living archosaurs comprise birds (dinosaurs) and crocodylians (suchians). The morphological diversity of birds and stem group dinosaurs is tremendous and well-documented. Suchia, the archosaurian group including crocodylians, is generally considered more conservative. Here, we report a new Late Triassic suchian archosaur with unusual, highly specialized features that are convergent with ornithomimid dinosaurs. Several derived features of the skull and postcranial skeleton are identical to conditions in ornithomimids. Such cases of extreme convergence in multiple regions of the skeleton in two distantly related vertebrate taxa are rare. This suggests that these archosaurs show iterative patterns of morphological evolution. It also suggests that this group of suchians occupied the adaptive zone that was occupied by ornithomimosaurs later in the Mesozoic. PMID:16600879

Nesbitt, Sterling J; Norell, Mark A

2006-01-01

324

Tramline Virtual Field Trips: Dinosaurs Field Trip  

NSDL National Science Digital Library

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.

Hughes-Feletar, Theresa

325

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.

326

New Developmental Evidence Clarifies the Evolution of Wrist Bones in the Dinosaur–Bird Transition  

PubMed Central

From early dinosaurs with as many as nine wrist bones, modern birds evolved to develop only four ossifications. Their identity is uncertain, with different labels used in palaeontology and developmental biology. We examined embryos of several species and studied chicken embryos in detail through a new technique allowing whole-mount immunofluorescence of the embryonic cartilaginous skeleton. Beyond previous controversy, we establish that the proximal–anterior ossification develops from a composite radiale+intermedium cartilage, consistent with fusion of radiale and intermedium observed in some theropod dinosaurs. Despite previous claims that the development of the distal–anterior ossification does not support the dinosaur–bird link, we found its embryonic precursor shows two distinct regions of both collagen type II and collagen type IX expression, resembling the composite semilunate bone of bird-like dinosaurs (distal carpal 1+distal carpal 2). The distal–posterior ossification develops from a cartilage referred to as “element x,” but its position corresponds to distal carpal 3. The proximal–posterior ossification is perhaps most controversial: It is labelled as the ulnare in palaeontology, but we confirm the embryonic ulnare is lost during development. Re-examination of the fossil evidence reveals the ulnare was actually absent in bird-like dinosaurs. We confirm the proximal–posterior bone is a pisiform in terms of embryonic position and its development as a sesamoid associated to a tendon. However, the pisiform is absent in bird-like dinosaurs, which are known from several articulated specimens. The combined data provide compelling evidence of a remarkable evolutionary reversal: A large, ossified pisiform re-evolved in the lineage leading to birds, after a period in which it was either absent, nonossified, or very small, consistently escaping fossil preservation. The bird wrist provides a modern example of how developmental and paleontological data illuminate each other. Based on all available data, we introduce a new nomenclature for bird wrist ossifications. PMID:25268520

Botelho, João Francisco; Ossa-Fuentes, Luis; Soto-Acuña, Sergio; Smith-Paredes, Daniel; Nuñez-León, Daniel; Salinas-Saavedra, Miguel; Ruiz-Flores, Macarena; Vargas, Alexander O.

2014-01-01

327

New developmental evidence clarifies the evolution of wrist bones in the dinosaur-bird transition.  

PubMed

From early dinosaurs with as many as nine wrist bones, modern birds evolved to develop only four ossifications. Their identity is uncertain, with different labels used in palaeontology and developmental biology. We examined embryos of several species and studied chicken embryos in detail through a new technique allowing whole-mount immunofluorescence of the embryonic cartilaginous skeleton. Beyond previous controversy, we establish that the proximal-anterior ossification develops from a composite radiale+intermedium cartilage, consistent with fusion of radiale and intermedium observed in some theropod dinosaurs. Despite previous claims that the development of the distal-anterior ossification does not support the dinosaur-bird link, we found its embryonic precursor shows two distinct regions of both collagen type II and collagen type IX expression, resembling the composite semilunate bone of bird-like dinosaurs (distal carpal 1+distal carpal 2). The distal-posterior ossification develops from a cartilage referred to as "element x," but its position corresponds to distal carpal 3. The proximal-posterior ossification is perhaps most controversial: It is labelled as the ulnare in palaeontology, but we confirm the embryonic ulnare is lost during development. Re-examination of the fossil evidence reveals the ulnare was actually absent in bird-like dinosaurs. We confirm the proximal-posterior bone is a pisiform in terms of embryonic position and its development as a sesamoid associated to a tendon. However, the pisiform is absent in bird-like dinosaurs, which are known from several articulated specimens. The combined data provide compelling evidence of a remarkable evolutionary reversal: A large, ossified pisiform re-evolved in the lineage leading to birds, after a period in which it was either absent, nonossified, or very small, consistently escaping fossil preservation. The bird wrist provides a modern example of how developmental and paleontological data illuminate each other. Based on all available data, we introduce a new nomenclature for bird wrist ossifications. PMID:25268520

Botelho, João Francisco; Ossa-Fuentes, Luis; Soto-Acuña, Sergio; Smith-Paredes, Daniel; Nuñez-León, Daniel; Salinas-Saavedra, Miguel; Ruiz-Flores, Macarena; Vargas, Alexander O

2014-09-01

328

The Four-Winged Dinosaur  

NSDL National Science Digital Library

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.

Tasha Dunn

329

Engraftment and lineage potential of adult hematopoietic stem and progenitor cells is compromised following short-term culture in the presence of an aryl hydrocarbon receptor antagonist.  

PubMed

Hematopoietic stem cell gene therapy for HIV/AIDS is a promising alternative to lifelong antiretroviral therapy. One of the limitations of this approach is the number and quality of stem cells available for transplant following in vitro manipulations associated with stem cell isolation and genetic modification. The development of methods to increase the number of autologous, gene-modified stem cells available for transplantation would overcome this barrier. Hematopoietic stem and progenitor cells (HSPC) from adult growth factor-mobilized peripheral blood were cultured in the presence of an aryl hydrocarbon receptor antagonist (AhRA) previously shown to expand HSPC from umbilical cord blood. Qualitative and quantitative assessment of the hematopoietic potential of minimally cultured (MC-HSPC) or expanded HSPC (Exp-HSPC) was performed using an immunodeficient mouse model of transplantation. Our results demonstrate robust, multilineage engraftment of both MC-HSPC and Exp-HSPC although estimates of expansion based on stem cell phenotype were not supported by a corresponding increase in in vivo engrafting units. Bone marrow of animals transplanted with either MC-HSPC or Exp-HSPC contained secondary engrafting cells verifying the presence of primitive stem cells in both populations. However, the frequency of in vivo engrafting units among the more primitive CD34+/CD90+ HSPC population was significantly lower in Exp-HSPC compared with MC-HSPC. Exp-HSPC also produced fewer lymphoid progeny and more myeloid progeny than MC-HSPC. These results reveal that in vitro culture of adult HSPC in AhRA maintains but does not increase the number of in vivo engrafting cells and that HSPC expanded in vitro contain defects in lymphopoiesis as assessed in this model system. Further investigation is required before implementation of this approach in the clinical setting. PMID:25003230

Gu, Angel; Torres-Coronado, Monica; Tran, Chy-Anh; Vu, Hieu; Epps, Elizabeth W; Chung, Janet; Gonzalez, Nancy; Blanchard, Suzette; DiGiusto, David L

2014-08-01

330

Engraftment and Lineage Potential of Adult Hematopoietic Stem and Progenitor Cells Is Compromised Following Short-Term Culture in the Presence of an Aryl Hydrocarbon Receptor Antagonist  

PubMed Central

Abstract Hematopoietic stem cell gene therapy for HIV/AIDS is a promising alternative to lifelong antiretroviral therapy. One of the limitations of this approach is the number and quality of stem cells available for transplant following in vitro manipulations associated with stem cell isolation and genetic modification. The development of methods to increase the number of autologous, gene-modified stem cells available for transplantation would overcome this barrier. Hematopoietic stem and progenitor cells (HSPC) from adult growth factor-mobilized peripheral blood were cultured in the presence of an aryl hydrocarbon receptor antagonist (AhRA) previously shown to expand HSPC from umbilical cord blood. Qualitative and quantitative assessment of the hematopoietic potential of minimally cultured (MC-HSPC) or expanded HSPC (Exp-HSPC) was performed using an immunodeficient mouse model of transplantation. Our results demonstrate robust, multilineage engraftment of both MC-HSPC and Exp-HSPC although estimates of expansion based on stem cell phenotype were not supported by a corresponding increase in in vivo engrafting units. Bone marrow of animals transplanted with either MC-HSPC or Exp-HSPC contained secondary engrafting cells verifying the presence of primitive stem cells in both populations. However, the frequency of in vivo engrafting units among the more primitive CD34+/CD90+ HSPC population was significantly lower in Exp-HSPC compared with MC-HSPC. Exp-HSPC also produced fewer lymphoid progeny and more myeloid progeny than MC-HSPC. These results reveal that in vitro culture of adult HSPC in AhRA maintains but does not increase the number of in vivo engrafting cells and that HSPC expanded in vitro contain defects in lymphopoiesis as assessed in this model system. Further investigation is required before implementation of this approach in the clinical setting. PMID:25003230

Gu, Angel; Torres-Coronado, Monica; Tran, Chy-Anh; Vu, Hieu; Epps, Elizabeth W.; Chung, Janet; Gonzalez, Nancy; Blanchard, Suzette

2014-01-01

331

First ceratosaurian dinosaur from Australia  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

332

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

E-print Network

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

Hutchinson, John

333

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

334

Osteology of Dinosaurs at The Field Museum  

NSDL National Science Digital Library

This activity explores vertebrate paleontology/paleobiology of the Mesozoic. It focuses on dinosaur osteology using skeletons and models at The Field Museum in Chicago. Students will compare the morphology of several types of bones between a variety of ornithischian and saurischian dinosaurs.

Roy Plotnick

335

Early ornithischian dinosaurs: the Triassic record  

Microsoft Academic Search

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

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

2007-01-01

336

Dinosaur dynamics in the Jurassic Era  

NASA Astrophysics Data System (ADS)

Dinosaurs were fascinating animals and elicit much excitement in the classroom. Analysis of fossilized dinosaur trackways permits one to estimate the locomotion speeds and accelerations of these extinct beasts. Such analysis allows one to apply Newton's laws of motion to examples from the Jurassic Era.

Lee, Scott

2010-04-01

337

Palaeontology Parental care in an ornithischian dinosaur  

Microsoft Academic Search

Crocodilians and birds show extensive parental care of their young, but whether this behaviour evolved independently in these two groups of living archosaurs is unknown - in part because features of parenting among related fossil groups such as dinosaurs are unclear. A dramatic specimen of the small ornithischian dinosaur Psittacosaurus sp. (Dalian Natural History Museum D2156) from Liaoning in China

Qingjin Meng; Jinyuan Liu; David J. Varricchio; Timothy Huang; Chunling Gao

2004-01-01

338

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.

339

STEM?!?!  

ERIC Educational Resources Information Center

The author's son has been an engineer since birth. He never asked "why" as a toddler, it was always "how's it work?" So that he wanted a STEM-based home education was no big surprise. In this article, the author considers what kind of curricula would work best for her complex kid.

Merrill, Jen

2012-01-01

340

Cyclopamine treatment of human embryonic stem cells followed by culture in human astrocyte medium promotes differentiation into nestin- and GFAP-expressing astrocytic lineage  

Microsoft Academic Search

Human embryonic stem cells (hESCs) are able to differentiate into various cell types, including neuronal cells and glial cells. However, little information is available regarding astrocyte differentiation. This report describes the differentiation of hESCs into nestin- and GFAP-expressing astrocytes following treatment with cyclopamine, which is an inhibitor of Hedgehog (Hh) signaling, and culturing in human astrocyte medium (HAM). In hESCs,

Dong-Seok Lee; Kweon Yu; Jeung-Yon Rho; Eunyoung Lee; Jee-Soo Han; Deog-Bon Koo; Yee Sook Cho; Janghwan Kim; Kyung-Kwang Lee; Yong-Mahn Han

2006-01-01

341

Induction of chondro-, osteo- and adipogenesis in embryonic stem cells by bone morphogenetic protein-2: Effect of cofactors on differentiating lineages  

Microsoft Academic Search

BACKGROUND: Recently, tissue engineering has merged with stem cell technology with interest to develop new sources of transplantable material for injury or disease treatment. Eminently interesting, are bone and joint injuries\\/disorders because of the low self-regenerating capacity of the matrix secreting cells, particularly chondrocytes. ES cells have the unlimited capacity to self-renew and maintain their pluripotency in culture. Upon induction

Nicole I zur Nieden; Grazyna Kempka; Derrick E Rancourt; Hans-Jürgen Ahr

2005-01-01

342

The last polar dinosaurs: high diversity of latest Cretaceous arctic dinosaurs in Russia  

NASA Astrophysics Data System (ADS)

A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous-Tertiary mass extinction event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.

Godefroit, Pascal; Golovneva, Lina; Shchepetov, Sergei; Garcia, Géraldine; Alekseev, Pavel

2009-04-01

343

N-Q Dinosaur Bones  

NSDL National Science Digital Library

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...

2012-05-01

344

Biology of the sauropod dinosaurs: the evolution of gigantism  

PubMed Central

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

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

345

REST regulates the pool size of the different neural lineages by restricting the generation of neurons and oligodendrocytes from neural stem/progenitor cells  

PubMed Central

REST is a master repressor of neuronal genes; however, whether it has any role during nervous system development remains largely unknown. Here, we analyzed systematically the role of REST in embryonic stem cells and multipotent neural stem/progenitor (NS/P) cells, including neurogenic and gliogenic NS/P cells derived from embryonic stem (ES) cells or developing mouse embryos. We showed that REST-null ES cells remained pluripotent and generated teratomas consisting of the three germ layers. By contrast, multipotent NS/P cells lacking REST displayed significantly reduced self-renewal capacity owing to reduced cell cycle kinetics and precocious neuronal differentiation. Importantly, although early-born neurogenic NS/P cells that lack REST were capable of differentiating to neurons and glia, the neuronal and oligodendrocytic pools were significantly enlarged and the astrocytic pool was shrunken. However, gliogenic NS/P cells lacking REST were able to generate a normal astrocytic pool size, suggesting that the shrinkage of the astrocytic pool generated from neurogenic NS/P cells lacking REST probably occurs by default. Microarray profiling of early-born NS/P cells lacking REST showed upregulation of neuronal as well as oligodendrocytic genes, specifically those involved in myelination. Furthermore, chromatin immunoprecipitation analyses showed that some of the upregulated oligodendrocytic genes contain an RE1 motif and are direct REST targets. Together, our data support a central role for REST during neural development in promoting NS/P cell self-renewal while restricting the generation and maturation of neurons and oligodendrocytes. PMID:22791895

Covey, Matthew V.; Streb, Jeffrey W.; Spektor, Roman; Ballas, Nurit

2012-01-01

346

REST regulates the pool size of the different neural lineages by restricting the generation of neurons and oligodendrocytes from neural stem/progenitor cells.  

PubMed

REST is a master repressor of neuronal genes; however, whether it has any role during nervous system development remains largely unknown. Here, we analyzed systematically the role of REST in embryonic stem cells and multipotent neural stem/progenitor (NS/P) cells, including neurogenic and gliogenic NS/P cells derived from embryonic stem (ES) cells or developing mouse embryos. We showed that REST-null ES cells remained pluripotent and generated teratomas consisting of the three germ layers. By contrast, multipotent NS/P cells lacking REST displayed significantly reduced self-renewal capacity owing to reduced cell cycle kinetics and precocious neuronal differentiation. Importantly, although early-born neurogenic NS/P cells that lack REST were capable of differentiating to neurons and glia, the neuronal and oligodendrocytic pools were significantly enlarged and the astrocytic pool was shrunken. However, gliogenic NS/P cells lacking REST were able to generate a normal astrocytic pool size, suggesting that the shrinkage of the astrocytic pool generated from neurogenic NS/P cells lacking REST probably occurs by default. Microarray profiling of early-born NS/P cells lacking REST showed upregulation of neuronal as well as oligodendrocytic genes, specifically those involved in myelination. Furthermore, chromatin immunoprecipitation analyses showed that some of the upregulated oligodendrocytic genes contain an RE1 motif and are direct REST targets. Together, our data support a central role for REST during neural development in promoting NS/P cell self-renewal while restricting the generation and maturation of neurons and oligodendrocytes. PMID:22791895

Covey, Matthew V; Streb, Jeffrey W; Spektor, Roman; Ballas, Nurit

2012-08-01

347

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

PubMed Central

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

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

348

Derivation of mesenchymal stromal cells from pluripotent stem cells through a neural crest lineage using small molecule compounds with defined media.  

PubMed

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

Fukuta, Makoto; Nakai, Yoshinori; Kirino, Kosuke; 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

349

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

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

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

350

Paleoenvironment, paleoecology, and evolution of Maniraptoran "dinosaurs"  

E-print Network

are herein considered important links in the origin of flight and a subsequent transition to terrestriality in some forms. In cladistic classifications, dromaeosaurid "dinosaurs" were only considered terrestrial cursors. The discovery of a gliding stage...

Burnham, David A.

2007-05-01

351

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.

352

The Science of Digging Up Dinosaurs  

NSDL National Science Digital Library

This activity has students trace the steps of a paleontologist from determining where to look for dinosaur fossils to studying the completed dinosaur skeleton for clues about the dinosaurs' behavior, diet, and anatomy. To start, students list and discuss the things they know about paleontology and then brainstorm what they think would be the most and least interesting aspects of being a paleontologist. Then they read about Paul Serenos' activities and discoveries, list his dinosaur findings and locations, read about the processes involved in paleontology, and explain why these steps are important. Lastly students prepare a report in which they write and share with the class detailed plans explaining specific parts of the fossil location, excavation, transportation, and research processes. This site provides twelve links to aid students in their research and five more for further investigation. It also has suggestions for assessment and ideas for extending the lesson.

353

Dinosaurs in the year of Darwin.  

PubMed

This special issue of The Anatomical Record explores the recent advances in the functional morphology and paleobiology of dinosaurs. Although Darwin did not study dinosaurs because paleontology was in its infancy a century and half ago, he considered both paleontology and anatomy as essential subjects for establishing the validity of evolution. The study of dinosaurs constitutes a vigorous subdiscipline within vertebrate paleontology, and anatomists and evolutionary functional morphologists constitute an especially creative subgroup within dinosaur paleontology. The collection of 17 papers presented in this issue encompass cranial anatomy, postcranial anatomy, and paleobiology of dinosaurs and other archosaurs. Soft tissue subjects include studies of brain structure, jaw adductor muscles, and keratinous appendages of the skull. Taxonomically, it includes four papers with a focus on theropods, including Tyrannosaurus, five papers dealing with ceratopsians, three papers on hadrosaurs, and one on ankylosaurs. Modern anatomical techniques such as CT scanning, finite element analysis, and high resolution histology are emphasized. The visual presentation of results of these studies is spectacular. Results include the first-ever life history table of a plant-eating dinosaur; a determination of the head orientation of Tyrannosaurus and its relatives based on interpretation of the semicircular canals. The claws of Velociraptor appear to best adapted for tree climbing, but not for horrific predatory activities. Pachyrhinosaurus evidently used its massive head for head butting. The tail club of the armored dinosaur Euoplocephalus had the structural integrity to be used as a weapon. The pages abound with insights such as these. Dinosaurs once dead for millions of years live again! PMID:19711448

Dodson, Peter

2009-09-01

354

Dinosaur eggshell study using scanning electron microscopy.  

PubMed

Visualization and analysis of structural features in fossil dinosaur eggs by scanning electron microscopy augment information from traditional petrographic light microscopy. Comparison of characteristics in fossil and modern eggshells allows inferences to be made regarding dinosaur reproductive biology, physiology, and evolutionary relationships. Assessment of diagenetic alteration of primary eggshell calcite structure that occurs during fossilization provides important information necessary for taxonomic identification and paleoenvironmental interpretations. PMID:12392352

Jackson, Frankie D; Schweitzer, Mary H; Schmitt, James G

2002-01-01

355

Are You Smarter Than a Dinosaur?  

NSDL National Science Digital Library

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.

Martin Farley

356

First Dinosaur Tracks from the Arabian Peninsula  

PubMed Central

Background The evolutionary history of Mesozoic terrestrial vertebrates from the Arabian Peninsula is virtually unknown. Despite vast exposures of rocky outcrops, only a handful of fossils have yet been described from the region. Here we report a multi-taxon dinosaur track assemblage near Madar village, 47 km north of Sana'a, Republic of Yemen. This represents the first dinosaur tracksite from the Arabian Peninsula, and the only multi-taxon dinosaur ichnosite in the Middle East. Methodology/Findings Measurements were taken directly from trackway impressions, following standard ichnological conventions. The presence of bipedal trackmakers is evidenced by a long series of pes imprints preserving smoothly rounded posterior margins, no evidence of a hallux, bluntly rounded digit tips and digital divarication angles characteristic of ornithopod dinosaurs. Nearby, eleven parallel quadrupedal trackways document a sauropod herd that included large and small individuals traveling together. Based on the morphology of manus impressions along with a narrow-gauged stance, the quadrupedal trackways were made by non-titanosauriform neosauropods. Additional isolated tracks and trackways of sauropod and ornithopod dinosaurs are preserved nearby. Conclusions/Significance Taken together, these discoveries present the most evocative window to date into the evolutionary history of dinosaurs of the Arabian Peninsula. Given the limited Mesozoic terrestrial record from the region, this discovery is of both temporal and geographic significance, and massive exposures of similarly-aged outcrops nearby offer great promise for future discoveries. PMID:18493306

Schulp, Anne S.; Al-Wosabi, Mohammed; Stevens, Nancy J.

2008-01-01

357

Dinosaur extinction: closing the ‘3 m gap’  

PubMed Central

Modern debate regarding the extinction of non-avian dinosaurs was ignited by the publication of the Cretaceous–Tertiary (K–T) asteroid impact theory and has seen 30 years of dispute over the position of the stratigraphically youngest in situ dinosaur. A zone devoid of dinosaur fossils reported from the last 3 m of the Upper Cretaceous, coined the ‘3 m gap’, has helped drive controversy. Here, we report the discovery of the stratigraphically youngest in situ dinosaur specimen: a ceratopsian brow horn found in a poorly rooted, silty, mudstone floodplain deposit located no more than 13 cm below the palynologically defined boundary. The K–T boundary is identified using three criteria: (i) decrease in Cretaceous palynomorphs without subsequent recovery, (ii) the existence of a ‘fern spike’, and (iii) correlation to a nearby stratigraphic section where primary extraterrestrial impact markers are present (e.g. iridium anomaly, spherules, shocked quartz). The in situ specimen demonstrates that a gap devoid of non-avian dinosaur fossils does not exist and is inconsistent with the hypothesis that non-avian dinosaurs were extinct prior to the K–T boundary impact event. PMID:21752814

Lyson, Tyler R.; Bercovici, Antoine; Chester, Stephen G. B.; Sargis, Eric J.; Pearson, Dean; Joyce, Walter G.

2011-01-01

358

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

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

Holtz Jr., Thomas R.

359

The Early Years: If You Were a Dinosaur?  

NSDL National Science Digital Library

Dinosaurs are one of those science topics that draw children in and teach them about concepts like measuring and using descriptive language. Learning about dinosaurs, although not hands-on like observing and recording caterpillar growth, develops critical

Peggy Ashbrook

2010-01-01

360

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago  

Microsoft Academic Search

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

Ursula B. Göhlich; Luis M. Chiappe

2006-01-01

361

BroadScale Patterns of Late Jurassic Dinosaur Paleoecology  

Microsoft Academic Search

BackgroundThere have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur

Christopher R. Noto; Ari Grossman

2010-01-01

362

The Great Dinosaur Feud: Science against All Odds  

ERIC Educational Resources Information Center

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…

Clary, Renee; Wandersee, James; Carpinelli, Amy

2008-01-01

363

Estimating the diversity of dinosaurs Steve C. Wang*  

E-print Network

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

Wang, Steve C.

364

GEOL 104 Dinosaurs: A Natural History Anatomy and Taxonomy Assignment  

E-print Network

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

Holtz Jr., Thomas R.

365

DWARFING IN ORNITHOPOD DINOSAURS FROM THE EARLY CRETACEOUS OF ROMANIA  

E-print Network

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

Benton, Michael

366

Response to Comment on "Ascent of Dinosaurs Linked to  

E-print Network

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

Olsen, Paul E.

367

GEOL 104 Dinosaurs: A Natural History Video Assignment  

E-print Network

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

Holtz Jr., Thomas R.

368

Dinosaur Fossils Predict Body Temperatures James F. Gillooly1*  

E-print Network

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

Allen, Andrew P.

369

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

ERIC Educational Resources Information Center

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…

2000

370

Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds  

E-print Network

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

Benton, Michael

371

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

E-print Network

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

Holtz Jr., Thomas R.

372

Forearm posture and mobility in quadrupedal dinosaurs.  

PubMed

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

VanBuren, Collin S; Bonnan, Matthew

2013-01-01

373

The evolution of dinosaur tooth enamel microstructure.  

PubMed

The evolution of tooth enamel microstructure in both extinct and extant mammalian groups has been extensively documented, but is poorly known in reptiles, including dinosaurs. Previous intensive sampling of dinosaur tooth enamel microstructure revealed that: (1) the three-dimensional arrangement of enamel types and features within a tooth-the schmelzmuster-is most useful in diagnosing dinosaur clades at or around the family level; (2) enamel microstructure complexity is correlated with tooth morphology complexity and not necessarily with phylogenetic position; and (3) there is a large amount of homoplasy within Theropoda but much less within Ornithischia. In this study, the examination of the enamel microstructure of 28 additional dinosaur taxa fills in taxonomic gaps of previous studies and reinforces the aforementioned conclusions. Additionally, these new specimens reveal that within clades such as Sauropodomorpha, Neotheropoda, and Euornithopoda, the more basal taxa have simpler enamel that is a precursor to the more complex enamel of more derived taxa and that schmelzmusters evolve in a stepwise fashion. In the particularly well-sampled clade of Euornithopoda, correlations between the evolution of dental and enamel characters could be drawn. The ancestral schmelzmuster for Genasauria remains ambiguous due to the dearth of basal ornithischian teeth available for study. These new specimens provide new insights into the evolution of tooth enamel microstructure in dinosaurs, emphasizing the importance of thorough sampling within broadly inclusive clades, especially among their more basal members. PMID:20518758

Hwang, Sunny H

2011-02-01

374

Forearm Posture and Mobility in Quadrupedal Dinosaurs  

PubMed Central

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

VanBuren, Collin S.; Bonnan, Matthew

2013-01-01

375

Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence.  

PubMed

The origin of birds and avian flight from within the archosaurian radiation has been among the most contentious issues in paleobiology. Although there is general agreement that birds are related to theropod dinosaurs at some level, debate centers on whether birds are derived directly from highly derived theropods, the current dogma, or from an earlier common ancestor lacking suites of derived anatomical characters. Recent discoveries from the Early Cretaceous of China have highlighted the debate, with claims of the discovery of all stages of feather evolution and ancestral birds (theropod dinosaurs), although the deposits are at least 25 million years younger than those containing the earliest known bird Archaeopteryx. In the first part of the study we examine the fossil evidence relating to alleged feather progenitors, commonly referred to as protofeathers, in these putative ancestors of birds. Our findings show no evidence for the existence of protofeathers and consequently no evidence in support of the follicular theory of the morphogenesis of the feather. Rather, based on histological studies of the integument of modern reptiles, which show complex patterns of the collagen fibers of the dermis, we conclude that "protofeathers" are probably the remains of collagenous fiber "meshworks" that reinforced the dinosaur integument. These "meshworks" of the skin frequently formed aberrant patterns resembling feathers as a consequence of decomposition. Our findings also draw support from new paleontological evidence. We describe integumental structures, very similar to "protofeathers," preserved within the rib area of a Psittacosaurus specimen from Nanjing, China, an ornithopod dinosaur unconnected with the ancestry of birds. These integumental structures show a strong resemblance to the collagenous fiber systems in the dermis of many animals. We also report the presence of scales in the forearm of the theropod ornithomimid (bird mimic) dinosaur, Pelecanimimus, from Spain. In the second part of the study we examine evidence relating to the most critical character thought to link birds to derived theropods, a tridactyl hand composed of digits 1-2-3. We maintain the evidence supports interpretation of bird wing digit identity as 2,3,4, which appears different from that in theropod dinosaurs. The phylogenetic significance of Chinese microraptors is also discussed, with respect to bird origins and flight origins. We suggest that a possible solution to the disparate data is that Aves plus bird-like maniraptoran theropods (e.g., microraptors and others) may be a separate clade, distinctive from the main lineage of Theropoda, a remnant of the early avian radiation, exhibiting all stages of flight and flightlessness. PMID:16217748

Feduccia, Alan; Lingham-Soliar, Theagarten; Hinchliffe, J Richard

2005-11-01

376

The complete skull and skeleton of an early dinosaur.  

PubMed

The unearthing of a complete skull and skeleton of the early dinosaur Herrerasaurus ischigualastensis sheds light on the early evolution of dinosaurs. Discovered in the Upper Triassic Ischigualasto Formation of Argentina, the fossils show that Herrerasaurus, a primitive theropod, was an agile, bipedal predator with a short forelimb specialized for grasping and raking. The fossils clarify anatomical features of the common ancestor of all dinosaurs. Herrerasaurus and younger dinosaurs from Upper Triassic beds in Argentina suggest that the dinosaurian radiation was well under way before dinosaurs dominated terrestrial vertebrate communities in taxonomic diversity and abundance. PMID:17789086

Sereno, P C; Novas, F E

1992-11-13

377

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

Microsoft Academic Search

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

Joel Berger; Carol Cunningham

1995-01-01

378

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

PubMed Central

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

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

2013-01-01

379

Plumage color patterns of an extinct dinosaur.  

PubMed

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

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

380

Willo: The Dinosaur with a Heart  

NSDL National Science Digital Library

This site refers to the discovery of a fossilized dinosaur heart that was reported in the April 21, 2000 issue of the Journal Science. This heart of a small herbivore called a Thescelosaurus reveals a structure "more like that of a bird or a mammal than those of reptiles, adding substantially to evidence suggesting that at least some dinosaurs had high metabolic rates." The site, from the Center for the Exploration of the Dinosaurian World, a collaboration between North Carolina State University and the North Carolina Museum of Natural Sciences, offers up-to-date information about and images of the important discovery.

381

Scaling in Theropod Dinosaurs: Femoral Bone Dimensions  

NASA Astrophysics Data System (ADS)

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.

Lee, Scott A.

2014-05-01

382

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?. Essentially, this â??linkâ? 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?, 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?The 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? and â??Did dinosaurs communicate?â?. 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.

383

Palaeontology: parental care in an ornithischian dinosaur.  

PubMed

Crocodilians and birds show extensive parental care of their young, but whether this behaviour evolved independently in these two groups of living archosaurs is unknown - in part because features of parenting among related fossil groups such as dinosaurs are unclear. A dramatic specimen of the small ornithischian dinosaur Psittacosaurus sp. (Dalian Natural History Museum D2156) from Liaoning in China reveals a single adult clustered with 34 juveniles within an area of 0.5 square metres, providing strong evidence for post-hatching parental care in Dinosauria. PMID:15356619

Meng, Qingjin; Liu, Jinyuan; Varricchio, David J; Huang, Timothy; Gao, Chunling

2004-09-01

384

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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...

2011-02-09

385

ELSEVIER Palaeogeography, Palaeoclimatology, Palaeoecology 130(1997) 275-292 Dinosaurs and other tetrapods in an Early Cretaceous bauxite-  

E-print Network

ELSEVIER Palaeogeography, Palaeoclimatology, Palaeoecology 130(1997) 275-292 PAI O Dinosaurs from ornithopod dinosaurs and rarer pterosaurs. Bird specimens reported previously from this fauna for insular adaptations in the dinosaur faunas. The ornithopod dinosaurs may include several taxa

Benton, Michael

386

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

USGS Publications Warehouse

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.

Modreski, P.J.

2001-01-01

387

Mammary lineage tracing: the coming of age.  

PubMed

Identification and characterization of the normal epithelial lineages in the mammary gland is a fundamental step in understanding both development and cellular origin of cancer. In contrast to other tissues where lineage tracing has been widely accepted as a method of choice for dissecting the stem cell hierarchy, mammary gland has long remained a challenge due to its unique developmental and topological features. Recent advances in high-resolution single-cell imaging, combined with the use of inducible Cre-recombinase and in situ cell ablation, have provided unprecedented insight into mammary epithelial cell composition and function. Here, we briefly summarize and compare different mammary gland lineage tracing strategies, examine associated caveats and discuss future challenges and opportunities. PMID:25563489

Sale, Sanja; Pavelic, Kresimir

2015-04-01

388

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

E-print Network

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

González, Luis A.

389

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

E-print Network

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

Schöne, Bernd R.

390

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

E-print Network

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

Paris-Sud XI, Université de

391

Did dinosaurs come up to scratch?  

Microsoft Academic Search

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

David M. Martill; Paul G. Davis

1998-01-01

392

Crocodilian behaviour: a window to dinosaur behaviour?  

Microsoft Academic Search

Modern crocodilians and birds are the only living representatives of the Archosauria, a group that also includes non-avian dinosaurs and pterosaurs. Modern crocodilians originated during the early Cretaceous period and dispersed globally. Examples of physiological similarities between living crocodilians and birds include similar amino acids in ?-keratins among crocodiles, turtles and birds; oviduct homologies between crocodilians and birds; similar forelimb

Peter Brazaitis; Myrna E. Watanabe

2011-01-01

393

Resources and energetics determined dinosaur maximal size  

PubMed Central

Some dinosaurs reached masses that were ?8 times those of the largest, ecologically equivalent terrestrial mammals. The factors most responsible for setting the maximal body size of vertebrates are resource quality and quantity, as modified by the mobility of the consumer, and the vertebrate's rate of energy expenditure. If the food intake of the largest herbivorous mammals defines the maximal rate at which plant resources can be consumed in terrestrial environments and if that limit applied to dinosaurs, then the large size of sauropods occurred because they expended energy in the field at rates extrapolated from those of varanid lizards, which are ?22% of the rates in mammals and 3.6 times the rates of other lizards of equal size. Of 2 species having the same energy income, the species that uses the most energy for mass-independent maintenance of necessity has a smaller size. The larger mass found in some marine mammals reflects a greater resource abundance in marine environments. The presumptively low energy expenditures of dinosaurs potentially permitted Mesozoic communities to support dinosaur biomasses that were up to 5 times those found in mammalian herbivores in Africa today. The maximal size of predatory theropods was ?8 tons, which if it reflected the maximal capacity to consume vertebrates in terrestrial environments, corresponds in predatory mammals to a maximal mass less than a ton, which is what is observed. Some coelurosaurs may have evolved endothermy in association with the evolution of feathered insulation and a small mass. PMID:19581600

McNab, Brian K.

2009-01-01

394

A beaver buddy for the dinosaurs?  

NSDL National Science Digital Library

Wouldn't it be cool to go back in time and see what things looked like 164 million years ago? Those were the days of the dinosaurs, which is why scientists digging in China were so surprised when they found a new animal fossil from that time that looks a lot like a beaver!

American Association for the Advancement of Science (AAAS; )

2006-02-23

395

THE FOSSIL RECORD OF PREDATION IN DINOSAURS  

Microsoft Academic Search

Predatory theropod dinosaurs can usually be identified as such by features of their jaws, teeth, and postcrania, but different clades of these reptiles differed in their adaptations for prey handling. Inferences about theropod diets and hunting behavior based on functional morphology are sometimes supported by evidence from taphonomic associations with likely prey species, bite marks, gut contents, coprolites, and trackways.

JAMES O. FARLOW; THOMAS R. HOLTZ

396

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.

397

Introduction to Thyreophora: The Armored Dinosaurs  

NSDL National Science Digital Library

The Thyreophora are a group of small to quite large armored plant-eating dinosaurs. The most familiar are Stegosaurus and Ankylosaurus, though there were many others. The two earliest known, Scutellosaurus and Scelidosaurus along with the remaining two major groups Stegosauria and Ankylosauria are described on this site.

398

Four-winged dinosaurs from China  

Microsoft Academic Search

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

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

2003-01-01

399

An unusual oviraptorosaurian dinosaur from China  

Microsoft Academic Search

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

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

2002-01-01

400

Scaling in Theropod Dinosaurs: Femoral Bone Dimensions  

ERIC Educational Resources Information Center

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…

Lee, Scott A.

2014-01-01

401

Matrix Elasticity Directs Stem Cell Lineage Specification  

E-print Network

regenerative pro- cesses, are believed to egress and circulate away from their niche (Katayama et al., 2006-dependent cell types, including neurons, myoblasts, and osteoblasts (respec- tively, [Deng et al., 2005 have yet to be examined. Differentiated cells ranging from neurons to osteoblasts adhere, contract

Discher, Dennis

402

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

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

Long Jr., John H.

403

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

E-print Network

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

Rainforth, Emma C.

404

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

E-print Network

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

Holtz Jr., Thomas R.

405

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

E-print Network

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

Holtz Jr., Thomas R.

406

A JUVENILE SKULL OF THE PRIMITIVE ORNITHISCHIAN DINOSAUR HETERODONTOSAURUS TUCKI FROM THE `STORMBERG' OF SOUTHERN AFRICA  

E-print Network

ARTICLE A JUVENILE SKULL OF THE PRIMITIVE ORNITHISCHIAN DINOSAUR HETERODONTOSAURUS TUCKI FROM of primitive ornithischian dinosaurs best known from the Early Jurassic of southern Africa. Because fossil

407

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...

408

Gastrointestinal Stem Cells  

Microsoft Academic Search

\\u000a Stem cell research is advancing at an incredible pace, with new ­discoveries and clinical applications being reported from\\u000a all over the world. Stem cells are functionally defined by their ability to self-renew and to differentiate into the cell\\u000a lineages of their tissue of origin. Stem cells are self-sustaining and can ­replicate themselves for long periods of time.\\u000a These characteristics make

N. Parveen; Aleem A. Khan; M. Aejaz Habeeb; C. M. Habibullah

409

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.

410

The smallest known non-avian theropod dinosaur  

Microsoft Academic Search

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

Xing Xu; Zhonghe Zhou; Xiaolin Wang

2000-01-01

411

Dinosaurs: Warm Blooded or Cold Blooded? Gumundur Freyr Matthasson  

E-print Network

Dinosaurs: Warm Blooded or Cold Blooded? Guðmundur Freyr Matthíasson Laufásvegur 42, 101 Reykjavík 09.60.31 Jarðsaga 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

Ingólfsson, �lafur

412

Sauropod dinosaur embryos from the Late Cretaceous of Patagonia  

Microsoft Academic Search

Definitive non-avian dinosaur embryos, those contained inside fossil eggs, are rare,. Here we describe the first known unequivocal embryonic remains of sauropod dinosaurs-the only known non-avian dinosaur embryos from Gondwana-from a nesting ground in the Upper Cretaceous stage of Patagonia, Argentina. At this new site, Auca Mahuevo (Fig. 1), thousands of eggs are distributed over an area greater than 1km2.

Luis M. Chiappe; Rodolfo A. Coria; Lowell Dingus; Frankie Jackson; Anusuya Chinsamy; Marilyn Fox

1998-01-01

413

Stem cells: research tools and clinical treatments.  

PubMed

The term 'stem cell' most commonly refers to embryonic stem cells, particularly in the lay media; however, it also describes other cell types. A stem cell represents a cell of multi-lineage potential with the ability for self-renewal. It is now clear that the plasticity and immortality of a given stem cell will depend on what type of stem cell it is, whether an embryonic stem cell, a fetal-placental stem cell or an adult stem cell. Stem cells offer great promise as cell-based therapies for the future. With evolving technology, much of the socio-political debate regarding stem cells can now be avoided. PMID:21951457

Fahey, Michael C; Wallace, Euan M

2011-09-01

414

The second Jurassic dinosaur rush and the dawn of dinomania.  

PubMed

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

Brinkman, Paul D

2010-09-01

415

The Great Dinosaur Feud: Science Against All Odds  

NSDL National Science Digital Library

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.

Amy Carpinelli

2008-10-01

416

Team of Paleontologists Discovers New Dinosaur Species  

NSDL National Science Digital Library

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.

Grinnell, Max

417

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

Microsoft Academic Search

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

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

2005-01-01

418

Skull Ecomorphology of Megaherbivorous Dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada  

PubMed Central

Megaherbivorous dinosaur coexistence on the Late Cretaceous island continent of Laramidia has long puzzled researchers, owing to the mystery of how so many large herbivores (6–8 sympatric species, in many instances) could coexist on such a small (4–7 million km2) landmass. Various explanations have been put forth, one of which–dietary niche partitioning–forms the focus of this study. Here, we apply traditional morphometric methods to the skulls of megaherbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta to infer the ecomorphology of these animals and to test the niche partitioning hypothesis. We find evidence for niche partitioning not only among contemporaneous ankylosaurs, ceratopsids, and hadrosaurids, but also within these clades at the family and subfamily levels. Consubfamilial ceratopsids and hadrosaurids differ insignificantly in their inferred ecomorphologies, which may explain why they rarely overlap stratigraphically: interspecific competition prevented their coexistence. PMID:23874409

Mallon, Jordan C.; Anderson, Jason S.

2013-01-01

419

Models for the rise of the dinosaurs.  

PubMed

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

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

2014-01-20

420

Should Dinosaurs be "Cloned" from Ancient DNA?  

NSDL National Science Digital Library

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.

Constance Soja

421

Hanford: The evolution of a dinosaur  

SciTech Connect

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.

Fulton, J.

1995-11-01

422

Revisiting the Estimation of Dinosaur Growth Rates  

PubMed Central

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

Myhrvold, Nathan P.

2013-01-01

423

Dinosaur Peptides Suggest Mechanisms of Protein Survival  

SciTech Connect

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 regions protected by the close packing of collagen molecules, and contained few acidic amino acids. Four peptides mapped to collagen regions crucial for cell-collagen interactions and tissue development. Dinosaur peptides were not represented in more exposed parts of the collagen fibril or regions mediating intermolecular cross-linking. Thus functionally significant regions of collagen fibrils that are physically shielded within the fibril may be preferentially preserved in fossils. These results show empirically that structure-function relationships at the molecular level could contribute to selective preservation in fossilized vertebrate remains across geological time, suggest a 'preservation motif', and bolster current concepts linking collagen structure to biological function. This non-random distribution supports the hypothesis that the peptides are produced by the extinct organisms and suggests a chemical mechanism for survival.

San Antonio, James D.; Schweitzer, Mary H.; Jensen, Shane T.; Kalluri, Raghu; Buckley, Michael; Orgel, Joseph P.R.O. (Harvard-Med); (IIT); (NCSU); (UPENN); (Manchester); (Orthovita)

2011-09-16

424

Cockroaches Probably Cleaned Up after Dinosaurs  

PubMed Central

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

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

2013-01-01

425

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

E-print Network

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

Benton, Michael

426

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

ERIC Educational Resources Information Center

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…

Duggan, Denis

2011-01-01

427

A Diverse Assemblage of Late Cretaceous Dinosaur and Bird  

E-print Network

A Diverse Assemblage of Late Cretaceous Dinosaur and Bird Feathers from Canadian Amber Ryan C. Mc and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure filamentous structures similar to the protofeathers of nonavian dinosaurs that are unknown in mod- ern birds

Machel, Hans

428

The Complete Skull and Skeleton of an Early Dinosaur  

Microsoft Academic Search

The unearthing of a complete skull and skeleton of the early dinosaur Herrerasaurus ischigualastensis sheds light on the early evolution of dinosaurs. Discovered in the Upper Triassic Ischigualasto Formation of Argentina, the fossils show that Herrerasaurus, a primitive theropod, was an agile, bipedal predator with a short forelimb specialized for grasping and raking. The fossils clarify anatomical features of the

Paul C. Sereno; Fernando E. Novas

1992-01-01

429

Ecological and evolutionary impli- cations of dinosaur feeding behaviour  

Microsoft Academic Search

Dinosaurs had a wide variety of feeding mechanisms that strongly impacted on their ecology and evolution. Here, we show how novel application of technologies borrowed from medicine and engineering, such as CT scanning and Finite Element Analysis, have recently been combined with traditional approaches to result in significant advances in our understanding of dinosaur palaeobiology. Taxon-specific studies are providing quantitative

Paul M. Barrett; Emily J. Rayfield

2006-01-01

430

Dino-Facts: A Unit on Dinosaur Behavior  

NSDL National Science Digital Library

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.

Judith Scotchmoor

431

Dinosaurs in the Dark: Grades K-1: Text Only Version  

NSDL National Science Digital Library

This informational text introduces students to the dinosaurs found near the polar regions and discusses the adaptations that allowed these dinosaurs to survive in a dark and cold environment. The text is written at a kindergarten through grade one reading level. This is a PDF containing the informational text and a glossary.

Jessica Fries-Gaither

432

36 CFR 7.63 - Dinosaur National Monument.  

Code of Federal Regulations, 2014 CFR

...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....

2014-07-01

433

Young Scientists Explore Dinosaurs. Book 8 Primary Level.  

ERIC Educational Resources Information Center

Designed to present interesting facts about science and to heighten the curiosity of primary age students, this book contains activities about the natural world and numerous black and white illustrations. Activities that focus on the dinosaur are organized into five sections. These include: (1) "Dinosaur Facts/Then and Now" (exploring bird and…

Penn, Linda

434

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

ERIC Educational Resources Information Center

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…

Herminghaus, Trisha, Ed.

435

36 CFR 7.63 - Dinosaur National Monument.  

Code of Federal Regulations, 2010 CFR

...Public Property 1 2010-07-01 2010-07-01 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....

2010-07-01

436

36 CFR 7.63 - Dinosaur National Monument.  

Code of Federal Regulations, 2012 CFR

...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....

2012-07-01

437

36 CFR 7.63 - Dinosaur National Monument.  

Code of Federal Regulations, 2011 CFR

...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....

2011-07-01

438

36 CFR 7.63 - Dinosaur National Monument.  

Code of Federal Regulations, 2013 CFR

...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....

2013-07-01

439

The distribution of integumentary structures in a feathered dinosaur  

Microsoft Academic Search

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

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

2001-01-01

440

Early crocodylomorph increases top tier predator diversity during rise of dinosaurs  

PubMed Central

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

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

2015-01-01

441

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

PubMed

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

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

2015-01-01

442

From dinosaurs to modern bird diversity: extending the time scale of adaptive radiation.  

PubMed

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

Moen, Daniel; Morlon, Hélène

2014-05-01

443

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

PubMed

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

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

2012-03-01

444

Understanding the Molecular Circuitry of Cell Lineage Specification in the Early Mouse Embryo  

PubMed Central

Pluripotent stem cells hold great promise for cell-based therapies in regenerative medicine. However, critical to understanding and exploiting mechanisms of cell lineage specification, epigenetic reprogramming, and the optimal environment for maintaining and differentiating pluripotent stem cells is a fundamental knowledge of how these events occur in normal embryogenesis. The early mouse embryo has provided an excellent model to interrogate events crucial in cell lineage commitment and plasticity, as well as for embryo-derived lineage-specific stem cells and induced pluripotent stem (iPS) cells. Here we provide an overview of cell lineage specification in the early (preimplantation) mouse embryo focusing on the transcriptional circuitry and epigenetic marks necessary for successive differentiation events leading to the formation of the blastocyst. PMID:24710206

Bergsmedh, Anna; Donohoe, Mary E.; Hughes, Rebecca-Ayme; Hadjantonakis, Anna-Katerina

2011-01-01

445

H3K36me3 key to Polycomb-mediated gene silencing in lineage specification  

PubMed Central

A newly uncovered activity of a family of Polycomb-group proteins provides insight into the mechanisms by which active genes become repressed during the transition from pluripotency to restricted cell fates as stem cells undergo lineage specification. PMID:23211767

Abed, Jumana AlHaj; Jones, Richard S

2014-01-01

446

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

Microsoft Academic Search

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

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

447

Dinosaur Breath - Learning about the Carbon Cycle  

NSDL National Science Digital Library

This activity illustrates the carbon cycle using an age-appropriate hook, and it includes thorough discussion and hands-on experimentation. Students learn about the geological (ancient) carbon cycle; they investigate the role of dinosaurs in the carbon cycle, and the eventual storage of carbon in the form of chalk. Students discover how the carbon cycle has been occurring for millions of years and is necessary for life on Earth. Finally, they may extend their knowledge to the concept of global warming and how engineers are working to understand the carbon cycle and reduce harmful carbon dioxide emissions.

Lauren Cooper

448

Dinosaur Breath - Learning about the Carbon Cycle  

NSDL National Science Digital Library

This activity illustrates the carbon cycle using an age-appropriate hook, and i