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Sample records for development evolution des

  1. Diffusion des Metaux et Evolution Stellaire

    NASA Astrophysics Data System (ADS)

    Turcotte, Sylvain

    Nous presentons dans cette these des modeles d'evolution stellaire incorporant la diffusion microscopique de maniere consistante. Pour la premiere fois, on a calcule l'evolution d'etoiles en tenant compte en detail de l'impact des variations d'abondances sur leur structure. Nous utilisons des spectres monochromatiques pour chacun des elements les plus abondants dans un melange solaire pour recalculer l'opacite pour les abondances et les conditions locales dans l'interieur d'une etoile au cours de son evolution. Nos modeles montrent que la diffusion atomique des metaux a un effet important sur les opacites dan les etoiles de plus de 1.3Msolar ou l'abondance du fer et des autres elements du pic du fer varient substantiellement. Ces etoiles, sans rotation ou champ magnetique, sont proches des etoiles de type Fm-Am dans lesquelles on observe une legere surabondance d'elements du pic du fer en plus d'une sous-abondance de calcium, sous-abondance que l'on obtient egalement. Nous obtenons cependant des surabondances depassant un facteur 10 pour les etoiles de plus de 1.4Msolar ce qui suggere qu'il existe un ou plusieurs mecanismes limitant la diffusion microscopique. La surabondance du fer en surface cause une augmentation, qui peut atteindre un facteur sept, de l'opacite a la limite de la zone convective. Ceci cause un accroissement de la temperature effective et de la masse de la zone convective comparativement aux modeles n'incluant que la diffusion de l'helium. Il s'agit la du principal effet de la diffusion sur la structure interne de ces etoiles. La diffusions n'a pas d'influence sur l'evolution de coeur stellaire dans les etoiles significativement plus massives quie le Soleil. Nous avons verife que l'utilisation de modeles consistants avec diffusion n'apporte pas d'amelioration sensible aux modeles solaires. Les forces radiatives calculees a partir des spectres d'OPAL pour les elements du pic du fer representent une fraction importante de la gravite. On obtient des

  2. Formation et Evolution des Quasars et Contraintes cosmologiques

    NASA Astrophysics Data System (ADS)

    Hatziminaoglou, Evanthia

    2000-06-01

    Cette thèse porte sur l'étude de l'évolution des quasars. Elle en aborde certains aspects théoriques et observationnels, ainsi que la construction des grands échantillons de quasars dans le but à long terme de combiner le tout dans un test cosmologique géométrique pour déterminer les valeurs des paramètres cosmologiques Omega et Lambda. Les paramètres cosmologiques Omegaspan>et Lambdaspan>décrivent la géométrie globale de l'Univers. En faisant des hypothèses raisonnables sur la distribution spatiale et l'évolution des objets astrophysiques (galaxies, amas des galaxies, quasars), on peut déterminer les valeurs de ces paramètres qui sont cohérentes avec ces hypothèses. Les tests cosmologiques traditionnels ont besoin de ''chandelles standards'', objets dont les propriétés intrinsèques sont indépendantes des distances. De tels objets sont probablement fictifs. Néanmoins, certains de ces tests cosmologiques peuvent être adaptés si l'évolution individuelle, ou au moins l'évolution statistique d'une population d'objets est connue. La question de la nature de l'évolution des quasars a très vite été posée et des réponses ''phénoménologiques'' ont d'abord été données. Ces réponses ne faisaient que donner une forme mathématique à l'évolution mais n'expliquaient rien de la physique duphénomène. Les premières tentatives de construction d'un modèle physique, liées au processus d'accrétion sur un trou noir et à la théorie de la formation de l'Univers ont commencé à la fin des années 80. Depuis, des dizaines de modèles tentent d'expliquer les observations, qui sont les résultats de l'étude d'objets de plus en plus nombreux. Au cours de cette thèse, le test V/Vmax a été appliqué sur l'échantillon du Large Bright Quasar Survey en montrant 1) que l'échantillon était biaisé à cause des critères de sélection et 2) que la (simple) loi de Pure Evolution en Luminosité n'était pas une bonne approximation à tout

  3. Molecular evolution of peste des petits ruminants virus.

    PubMed

    Muniraju, Murali; Munir, Muhammad; Parthiban, AravindhBabu R; Banyard, Ashley C; Bao, Jingyue; Wang, Zhiliang; Ayebazibwe, Chrisostom; Ayelet, Gelagay; El Harrak, Mehdi; Mahapatra, Mana; Libeau, Geneviève; Batten, Carrie; Parida, Satya

    2014-12-01

    Despite safe and efficacious vaccines against peste des petits ruminants virus (PPRV), this virus has emerged as the cause of a highly contagious disease with serious economic consequences for small ruminant agriculture across Asia, the Middle East, and Africa. We used complete and partial genome sequences of all 4 lineages of the virus to investigate evolutionary and epidemiologic dynamics of PPRV. A Bayesian phylogenetic analysis of all PPRV lineages mapped the time to most recent common ancestor and initial divergence of PPRV to a lineage III isolate at the beginning of 20th century. A phylogeographic approach estimated the probability for root location of an ancestral PPRV and individual lineages as being Nigeria for PPRV, Senegal for lineage I, Nigeria/Ghana for lineage II, Sudan for lineage III, and India for lineage IV. Substitution rates are critical parameters for understanding virus evolution because restrictions in genetic variation can lead to lower adaptability and pathogenicity.

  4. Molecular Evolution of Peste des Petits Ruminants Virus

    PubMed Central

    Muniraju, Murali; Munir, Muhammad; Parthiban, AravindhBabu R.; Banyard, Ashley C.; Bao, Jingyue; Wang, Zhiliang; Ayebazibwe, Chrisostom; Ayelet, Gelagay; El Harrak, Mehdi; Mahapatra, Mana; Libeau, Geneviève; Batten, Carrie

    2014-01-01

    Despite safe and efficacious vaccines against peste des petits ruminants virus (PPRV), this virus has emerged as the cause of a highly contagious disease with serious economic consequences for small ruminant agriculture across Asia, the Middle East, and Africa. We used complete and partial genome sequences of all 4 lineages of the virus to investigate evolutionary and epidemiologic dynamics of PPRV. A Bayesian phylogenetic analysis of all PPRV lineages mapped the time to most recent common ancestor and initial divergence of PPRV to a lineage III isolate at the beginning of 20th century. A phylogeographic approach estimated the probability for root location of an ancestral PPRV and individual lineages as being Nigeria for PPRV, Senegal for lineage I, Nigeria/Ghana for lineage II, Sudan for lineage III, and India for lineage IV. Substitution rates are critical parameters for understanding virus evolution because restrictions in genetic variation can lead to lower adaptability and pathogenicity. PMID:25418782

  5. Darwin, Engels und die Rolle der Arbeit in der biologischen und kulturellen Evolution des Menschen

    NASA Astrophysics Data System (ADS)

    Reichholf, Josef H.

    Im Jahre 1876, 5 Jahre nach Erscheinen von Darwins Buch über die Evolution des Menschen und die sexuelle Selektion (Darwin 1871), veröffentlichte Friedrich Engels den berühmt gewordenen Essay "Anteil der Arbeit an der Menschwerdung des Affen“ (Engels 1876). Die Kernfrage darin lautet in Kurzform: Warum hat der Mensch eigentlich ein Bedürfnis nach Arbeit? Engels Antwort wird nachfolgend näher betrachtet und vom gegenwärtigen Kenntnisstand aus beurteilt. Wie sich zeigen wird, beantworten seine Überlegungen die Frage nicht wirklich. Sie ist weiterhin offen. Es können lediglich einige zusätzliche Anhaltspunkte zur Diskussion gestellt werden. Angesichts des drängenden Problems millionenfacher Arbeitslosigkeit und der Forderungen nach einem "Grundrecht auf Arbeit“ kommt den Überlegungen zum möglichen Ursprung des Bedürfnisses nach Arbeit mehr als nur akademisches Interesse zu.

  6. Human Development, Human Evolution.

    ERIC Educational Resources Information Center

    Smillie, David

    One of the truly remarkable events in human evolution is the unprecedented increase in the size of the brain of "Homo" over a brief span of 2 million years. It would appear that some significant selective pressure or opportunity presented itself to this branch of the hominid line and caused a rapid increase in the brain, introducing a…

  7. Human Development, Human Evolution.

    ERIC Educational Resources Information Center

    Smillie, David

    One of the truly remarkable events in human evolution is the unprecedented increase in the size of the brain of "Homo" over a brief span of 2 million years. It would appear that some significant selective pressure or opportunity presented itself to this branch of the hominid line and caused a rapid increase in the brain, introducing a…

  8. On the evolution of development

    PubMed Central

    Torday, John S.

    2015-01-01

    Perhaps development is more than just morphogenesis. We now recognize that the conceptus expresses epigenetic marks that heritably affect it phenotypically, indicating that the offspring are to some degree genetically autonomous, and that ontogeny and phylogeny may coordinately determine the fate of such marks. This scenario mechanistically links ecology, ontogeny and phylogeny together as an integrated mechanism for evolution for the first time. As a functional example, the Parathyroid Hormone-related Protein (PTHrP) signaling duplicated during the Phanerozoic water-land transition. The PTHrP signaling pathway was critical for the evolution of the skeleton, skin barrier, and lung function, based on experimental evidence, inferring that physiologic stress can profoundly affect adaptation through internal selection, giving seminal insights to how and why vertebrates were able to evolve from water to land. By viewing evolution from its inception in unicellular organisms, driven by competition between pro- and eukaryotes, the emergence of complex biologic traits from the unicellular cell membrane offers a novel way of thinking about the process of evolution from its beginnings, rather than from its consequences as is traditionally done. And by focusing on the epistatic balancing mechanisms for calcium and lipid homeostasis, the evolution of unicellular organisms, driven by competition between pro- and eukaryotes, gave rise to the emergence of complex biologic traits derived from the unicellular plasma lemma, offering a unique way of thinking about the process of evolution. By exploiting the cellular-molecular mechanisms of lung evolution as ontogeny and phylogeny, the sequence of events for the evolution of the skin, kidney and skeleton become more transparent. This novel approach to the evolution question offers equally novel insights to the primacy of the unicellular state, hologenomics and even a priori bioethical decisions. PMID:25729239

  9. Biocatalyst Development by Directed Evolution

    PubMed Central

    Wang, Meng; Si, Tong; Zhao, Huimin

    2012-01-01

    Biocatalysis has emerged as a great addition to traditional chemical processes for production of bulk chemicals and pharmaceuticals. To overcome the limitations of naturally occurring enzymes, directed evolution has become the most important tool for improving critical traits of biocatalysts such as thermostability, activity, selectivity, and tolerance towards organic solvents for industrial applications. Recent advances in mutant library creation and high-throughput screening have greatly facilitated the engineering of novel and improved biocatalysts. This review provides an update of the recent developments in the use of directed evolution to engineer biocatalysts for practical applications. PMID:22310212

  10. Provenance of Des Moines lobe till records ice-stream catchment evolution during Laurentide deglaciation

    USGS Publications Warehouse

    Lusardi, B.A.; Jennings, C.E.; Harris, K.L.

    2011-01-01

    Mapping and analysis of deposits of the Des Moines lobe of the Laurentide Ice Sheet, active after the Last Glacial Maximum (LGM), reveal several texturally and lithologically distinct tills within what had been considered to be a homogeneous deposit. Although the differences between tills are subtle, minor distinctions are predictable and mappable, and till sheets within the area covered by the lobe can be correlated for hundreds of kilometres parallel to ice flow. Lateral till-sheet contacts are abrupt or overlap in a narrow zone, coincident with a geomorphic discontinuity interpreted to be a shear margin. Till sheets 10 to 20m thick show mixing in their lower 2 to 3m. We suggest that: (i) lithologically distinct till sheets correspond to unique ice-stream source areas; (ii) the sequence of tills deposited by the Des Moines lobe was the result of the evolution and varying dominance of nearby and competing ice streams and their tributaries; and (iii) in at least one instance, more than one ice stream simultaneously contributed to the lobe. Therefore the complex sequence of tills of subtly different provenances, and the unconformities between them record the evolution of an ice-catchment area during Laurentide Ice Sheet drawdown. Till provenance data suggest that, after till is created in the ice-stream source area, the subglacial conditions required for transporting till decline and incorporation of new material is limited. ?? 2011 The Authors. Boreas ?? 2011 The Boreas Collegium.

  11. Human development, heredity and evolution.

    PubMed

    Nishinakamura, Ryuichi; Takasato, Minoru

    2017-06-15

    From March 27-29 2017, the RIKEN Center for Developmental Biology held a symposium entitled 'Towards Understanding Human Development, Heredity, and Evolution' in Kobe, Japan. Recent advances in technologies including stem cell culture, live imaging, single-cell approaches, next-generation sequencing and genome editing have led to an expansion in our knowledge of human development. Organized by Yoshiya Kawaguchi, Mitinori Saitou, Mototsugu Eiraku, Tomoya Kitajima, Fumio Matsuzaki, Takashi Tsuji and Edith Heard, the symposium covered a broad range of topics including human germline development, epigenetics, organogenesis and evolution. This Meeting Review provides a summary of this timely and exciting symposium, which has convinced us that we are moving into the era of science targeted on humans. © 2017. Published by The Company of Biologists Ltd.

  12. Angiosperm ovules: diversity, development, evolution

    PubMed Central

    Endress, Peter K.

    2011-01-01

    Background Ovules as developmental precursors of seeds are organs of central importance in angiosperm flowers and can be traced back in evolution to the earliest seed plants. Angiosperm ovules are diverse in their position in the ovary, nucellus thickness, number and thickness of integuments, degree and direction of curvature, and histological differentiations. There is a large body of literature on this diversity, and various views on its evolution have been proposed over the course of time. Most recently evo–devo studies have been concentrated on molecular developmental genetics in ovules of model plants. Scope The present review provides a synthetic treatment of several aspects of the sporophytic part of ovule diversity, development and evolution, based on extensive research on the vast original literature and on experience from my own comparative studies in a broad range of angiosperm clades. Conclusions In angiosperms the presence of an outer integument appears to be instrumental for ovule curvature, as indicated from studies on ovule diversity through the major clades of angiosperms, molecular developmental genetics in model species, abnormal ovules in a broad range of angiosperms, and comparison with gymnosperms with curved ovules. Lobation of integuments is not an atavism indicating evolution from telomes, but simply a morphogenetic constraint from the necessity of closure of the micropyle. Ovule shape is partly dependent on locule architecture, which is especially indicated by the occurrence of orthotropous ovules. Some ovule features are even more conservative than earlier assumed and thus of special interest in angiosperm macrosystematics. PMID:21606056

  13. Zu einer inhaltsorientierten Theorie des Lernens und Lehrens der biologischen Evolution

    NASA Astrophysics Data System (ADS)

    Wallin, Anita

    Der Zweck dieser Studie (zwecks Überblick siehe dazu Abb. 9.1) war zu untersuchen, wie die Schüler der Sekundarstufe II ein Verständnis von der Theorie der biologischen Evolution entwickeln. Vom Ausgangspunkt "Vorurteile der Schüler“ ausgehend wurden Unterrichtssequenzen entwickelt und drei verschiedene Lernexperimente in einem zyklischen Prozess durchgeführt. Das Wissen der Schüler wurde vor, während und nach den Unterrichtssequenzen mit Hilfe von schriftlichen Tests, Interviews und Diskussionsrunden in kleinen Gruppen abgefragt. Etwa 80 % der Schüler hatten vor dem Unterricht alternative Vorstellungen von Evolution, und in dem Nachfolgetest erreichten circa 75 % ein wissenschaftliches Niveau. Die Argumentation der Schüler in den verschiedenen Tests wurde sorgfältig unter Rücksichtnahme auf Vorurteile, der konzeptionellen Struktur der Theorie der Evolution und den Zielen des Unterrichts analysiert. Daraus konnten Einsichten in solche Anforderungen an Lehren und Lernen gewonnen werden, die Herausforderungen an Schüler und Lehrer darstellen, wenn sie anfangen, evolutionäre Biologie zu lernen oder zu lehren. Ein wichtiges Ergebnis war, dass das Verständnis existierender Variation in einer Population der Schlüssel zum Verständnis von natürlicher Selektion ist. Die Ergebnisse sind in einer inhaltsorientierten Theorie zusammengefasst, welche aus drei verschiedenen Aspekten besteht: 1) den inhaltsspezifischen Aspekten, die einzigartig für jedes wissenschaftliche Feld sind; 2) den Aspekten, die die Natur der Wissenschaft betreffen; und 3) den allgemeinen Aspekten. Diese Theorie kann in neuen Experimenten getestet und weiter entwickelt werden.

  14. Eyes: variety, development and evolution.

    PubMed

    Fernald, Russell D

    2004-01-01

    The selective advantages of using light as a source of information are reflected in the diverse types of extant eyes. The physical properties of light restrict how it can be collected and processed, resulting in only eight known optical systems found in animals. Eyes develop through tissue rearrangement and differentiation. Our understanding of the source of genetic information used in developmental programs is growing rapidly and reveals distributions of gene expression with substantial overlap in both time and space. Specific genes and their products are used repeatedly, making causal relationships more difficult to discern. The phenomenon of groups of genes acting together seems to be the rule. Throughout evolution, particular genes have become associated with distinct aspects of eye development, and these suites of genes have been recruited repeatedly as new eyes evolved.

  15. Vertebral development and amphibian evolution.

    PubMed

    Carroll, R L; Kuntz, A; Albright, K

    1999-01-01

    Amphibians provide an unparalleled opportunity to integrate studies of development and evolution through the investigation of the fossil record of larval stages. The pattern of vertebral development in modern frogs strongly resembles that of Paleozoic labyrinthodonts in the great delay in the ossification of the vertebrae, with the centra forming much later than the neural arches. Slow ossification of the trunk vertebrae in frogs and the absence of ossification in the tail facilitate the rapid loss of the tail during metamorphosis, and may reflect retention of the pattern in their specific Paleozoic ancestors. Salamanders and caecilians ossify their centra at a much earlier stage than frogs, which resembles the condition in Paleozoic lepospondyls. The clearly distinct patterns and rates of vertebral development may indicate phylogenetic separation between the ultimate ancestors of frogs and those of salamanders and caecilians within the early radiation of ancestral tetrapods. This divergence may date from the Lower Carboniferous. Comparison with the molecular regulation of vertebral development described in modern mammals and birds suggests that the rapid chondrification of the centra in salamanders relative to that of frogs may result from the earlier migration of sclerotomal cells expressing Pax1 to the area surrounding the notochord.

  16. Crocodilian Forebrain: Evolution and Development

    PubMed Central

    Pritz, Michael B.

    2015-01-01

    Organization and development of the forebrain in crocodilians are reviewed. In juvenile Caiman crocodilus, the following features were examined: identification and classification of dorsal thalamic nuclei and their respective connections with the telencephalon, presence of local circuit neurons in the dorsal thalamic nuclei, telencephalic projections to the dorsal thalamus, and organization of the thalamic reticular nucleus. These results document many similarities between crocodilians and other reptiles and birds. While crocodilians, as well as other sauropsids, demonstrate several features of neural circuitry in common with mammals, certain striking differences in organization of the forebrain are present. These differences are the result of evolution. To explore a basis for these differences, embryos of Alligator misissippiensis were examined to address the following. First, very early development of the brain in Alligator is similar to that of other amniotes. Second, the developmental program for individual vesicles of the brain differs between the secondary prosencephalon, diencephalon, midbrain, and hindbrain in Alligator. This is likely to be the case for other amniotes. Third, initial development of the diencephalon in Alligator is similar to that in other amniotes. In Alligator, alar and basal parts likely follow a different developmental scheme. PMID:25829019

  17. Molecular Evolution and Characterization of Hemagglutinin (H) in Peste des Petits Ruminants Virus

    PubMed Central

    Chen, Lei; Zhu, Xueliang; Dou, Yongxi

    2016-01-01

    Peste des Petits Ruminants (PPR) is an acute, highly contagious, and febrile viral disease that affects both domestic and wild small ruminants. The disease has become a major obstacle to the development of sustainable Agriculture. Hemagglutinin (H), the envelope glycoprotein of Peste des Petits Ruminants Virus (PPRV), plays a crucial role in regulating viral adsorption and entry, thus determining pathogenicity, and release of newly produced viral particles. In order to accurately understand the epidemic of the disease and the interactions between the virus and host, we launch the work. Here, we examined H gene from all four lineages of the PPRV to investigate evolutionary and epidemiologic dynamics of PPRV by the Bayesian method. In addition, we predicted positive selection sites due to selective pressures. Finally, we studied the interaction between H protein and SLAM receptor based on homology model of the complex. Phylogenetic analysis suggested that H gene can also be used to investigate evolutionary and epidemiologic dynamics of PPRV. Positive selection analysis identified four positive selection sites in H gene, in which only one common site (aa246) was detected by two methods, suggesting strong operation structural and/or functional constraint of changes on the H protein. This target site may be of interest for future mutagenesis studies. The results of homology modeling showed PPRVHv-shSLAM binding interface and MVH-maSLAM binding interface were consistent, wherein the groove in the B4 blade and B5 of the head domain of PPRVHv bound to the AGFCC′ β-sheets of the membrane-distal ectodomain of shSLAM. The binding regions could provide insight on the nature of the protein for epitope vaccine design, novel drug discovery, and rational drug design against PPRV. PMID:27035347

  18. Polyphase evolution of the Chaîne des Matheux frontal thrust (Haiti)

    NASA Astrophysics Data System (ADS)

    Wessels, Richard; Ellouz-Zimmermann, Nadine; Rosenberg, Claudio; Bellahsen, Nicolas; Hamon, Youri; Deschamps, Remy; Battani, Anne; Leroy, Sylvie; Momplaisir, Roberte

    2016-04-01

    The NW - SE trending Haitian fold-and-thrust belt (HFTB) is located in the western part of the Caribbean island of Hispaniola. It covers the suture between the Cretaceous Caribbean island arc in the north and the Late Cretaceous thickened oceanic crust in the south. The HFTB is bounded to the north and south by the left-lateral Septentrional (SFZ) and Enriquillo-Plantain Garden (EPGFZ) fault zones, respectively. Compressional deformation on the HFTB commenced as early as Eocene times. It was followed by transpressional deformation from the early Miocene onwards, with in sequence progressive stacking of thrust sheets towards the SW. Seismicity at the junction between the HFTB and the EPGFZ is recorded by the 12 January 2010 Mw 7.0 earthquake. Surface mapping did not reveal a rupture, as the main activity occurred on the steep NNW dipping oblique transpressional Léogâne fault, while aftershocks documented motion on a shallow SW dipping thrust segment. The structural style of deformation of the HFTB, either the stacking of thrust sheets on basement heterogeneities or basement-involved thrusting, has not been studied in detail. Also lacking are conceptual models addressing the amount of convergence between the northern and southern domains, and describing how convergence was accommodated. To address these problems we conducted a detailed fieldwork on the southernmost thrust sheet, known as the Chaîne des Matheux front. Using stratigraphy, geological mapping, cross sections, kinematic fault slip data, analysis of mineralizations and fluid inclusions, and geochemical analysis of fluid seeps, we decipher the evolution of this anticlinal structure. Stratigraphic data reveal stable Eocene platform sedimentation over the whole region, which preceded deepening of the basin throughout Oligocene and early Miocene times. A diachronous evolution is evident from the middle Miocene onwards. The NE flank displays a shallowing upwards trend and clastic sedimentation, while the

  19. Evolution of a highly vulnerable ice-cored moraine: Col des Gentianes, Swiss Alps

    NASA Astrophysics Data System (ADS)

    Ravanel, L.; Lambiel, C.; Oppikofer, T.; Mazotti, B.; Jaboyedoff, M.

    2012-04-01

    Rock mass movements are dominant in the morphodynamics of high mountain rock slopes and are at the origin of significant risks for people who attend these areas and for infrastructures that are built on (mountain huts, cable cars, etc.). These risks are becoming greater because of permafrost degradation and glacier retreat, two consequences of the global warming. These two commonly associated factors may affect slope stability by changing mechanical properties of the interstitial ice and modifying the mechanical constraints in these rock slopes. Between 1977 and 1979, significant works were carried out on the Little Ice Age moraine of the Tortin glacier at the Col des Gentianes (2894 m), in the Mont Fort area (Verbier, Switzerland), for the construction of a cable car station and a restaurant. Since the early 1980s, the glacier drastically retreated and the moraine became unstable: its inner slope has retreated for several meters. Various observations and geoelectric measurements indicate that significant volume of massive ice mass is still present within the moraine (ice-cored moraine). Its melting could therefore increase the instability of the moraine. Since 2007, the moraine is surveyed by terrestrial laser scanning (TLS) in order to characterize its evolution: 8 campaigns were conducted between July 2007 and October 2011. The comparison of the high resolution 3D models so obtained allowed the detection and quantification of mass movements that have affected the moraine over this period, essentially by calculating difference maps (shortest oblique distances between two models). Between July 2007 and October 2011, 7 landslides were measured, involving volumes between 87 and 1138 m3. The most important of these occurred during the summers 2009 and 2011. TLS data also allowed identifying: (i) two main areas affected by slower but sometimes substantial movements (displacements of blocks on more than 2 m during a summer period); (ii) significant deposits of

  20. Hétérochronies dans l'évolution des hominidés. Le développement dentaire des australopithécines «robustes»Heterochronic process in hominid evolution. The dental development in 'robust' australopithecines.

    NASA Astrophysics Data System (ADS)

    Ramirez Rozzi, Fernando V.

    2000-10-01

    Heterochrony is defined as an evolutionary modification in time and in the relative rate of development [6]. Growth (size), development (shape), and age (adult) are the three fundamental factors of ontogeny and have to be known to carry out a study on heterochronies. These three factors have been analysed in 24 Plio-Pleistocene hominid molars from Omo, Ethiopia, attributed to A. afarensis and robust australopithecines ( A. aethiopicus and A. aff. aethiopicus) . Molars were grouped into three chronological periods. The analysis suggests that morphological modifications through time are due to heterochronic process, a neoteny ( A. afarensis - robust australopithecine clade) and a time hypermorphosis ( A. aethiopicus - A. aff. aethiopicus).

  1. Origin, development, and evolution of butterfly eyespots.

    PubMed

    Monteiro, Antónia

    2015-01-07

    This article reviews the latest developments in our understanding of the origin, development, and evolution of nymphalid butterfly eyespots. Recent contributions to this field include insights into the evolutionary and developmental origin of eyespots and their ancestral deployment on the wing, the evolution of eyespot number and eyespot sexual dimorphism, and the identification of genes affecting eyespot development and black pigmentation. I also compare features of old and more recently proposed models of eyespot development and propose a schematic for the genetic regulatory architecture of eyespots. Using this schematic I propose two hypotheses for why we observe limits to morphological diversity across these serially homologous traits.

  2. Play in Evolution and Development

    ERIC Educational Resources Information Center

    Pellegrini, Anthony D.; Dupuis, Danielle; Smith, Peter K.

    2007-01-01

    In this paper we examine the role of play in human ontogeny and phylogeny, following Surplus Resource Theory. We consider how juveniles use play to sample their environment in order to develop adaptive behaviors. We speculate about how innovative behaviors developed in play in response to environmental novelty may influence subsequent evolutionary…

  3. Play in Evolution and Development

    ERIC Educational Resources Information Center

    Pellegrini, Anthony D.; Dupuis, Danielle; Smith, Peter K.

    2007-01-01

    In this paper we examine the role of play in human ontogeny and phylogeny, following Surplus Resource Theory. We consider how juveniles use play to sample their environment in order to develop adaptive behaviors. We speculate about how innovative behaviors developed in play in response to environmental novelty may influence subsequent evolutionary…

  4. Tracking Concept Development through Semiotic Evolution

    ERIC Educational Resources Information Center

    Ronen, Ilana

    2015-01-01

    A qualitative research focused on a case study aiming to monitor emergent knowledge in a discourse group by tracking the development of the concept "goal." The analysis, based on "Semiotic Evolution" methodology facilitates the description of interactions between personal perceptions in the group discourse, illustrating the…

  5. Evolution and development of inflorescence architectures.

    PubMed

    Prusinkiewicz, Przemyslaw; Erasmus, Yvette; Lane, Brendan; Harder, Lawrence D; Coen, Enrico

    2007-06-08

    To understand the constraints on biological diversity, we analyzed how selection and development interact to control the evolution of inflorescences, the branching structures that bear flowers. We show that a single developmental model accounts for the restricted range of inflorescence types observed in nature and that this model is supported by molecular genetic studies. The model predicts associations between inflorescence architecture, climate, and life history, which we validated empirically. Paths, or evolutionary wormholes, link different architectures in a multidimensional fitness space, but the rate of evolution along these paths is constrained by genetic and environmental factors, which explains why some evolutionary transitions are rare between closely related plant taxa.

  6. New Frontiers in Language Evolution and Development.

    PubMed

    Oller, D Kimbrough; Dale, Rick; Griebel, Ulrike

    2016-04-01

    This article introduces the Special Issue and its focus on research in language evolution with emphasis on theory as well as computational and robotic modeling. A key theme is based on the growth of evolutionary developmental biology or evo-devo. The Special Issue consists of 13 articles organized in two sections: A) Theoretical foundations and B) Modeling and simulation studies. All the papers are interdisciplinary in nature, encompassing work in biological and linguistic foundations for the study of language evolution as well as a variety of computational and robotic modeling efforts shedding light on how language may be developed and may have evolved. Copyright © 2016 Cognitive Science Society, Inc.

  7. Evolution of Bacillus subtilis to enhanced growth at low pressure: up-regulated transcription of des-desKR, encoding the fatty acid desaturase system.

    PubMed

    Fajardo-Cavazos, Patricia; Waters, Samantha M; Schuerger, Andrew C; George, Sheeja; Marois, James J; Nicholson, Wayne L

    2012-03-01

    The atmospheric pressure on Mars ranges from 1-10 mbar, about 1% of Earth pressure (∼1013 mbar). Low pressure is a growth-inhibitory factor for terrestrial microorganisms on Mars, and a putative low-pressure barrier for growth of Earth bacteria of ∼25 mbar has been postulated. In a previous communication, we described the isolation of a strain of Bacillus subtilis that had evolved enhanced growth ability at the near-inhibitory low pressure of 50 mbar. To explore mechanisms that enabled growth of the low-pressure-adapted strain, numerous genes differentially transcribed between the ancestor strain WN624 and low-pressure-evolved strain WN1106 at 50 mbar were identified by microarray analysis. Among these was a cluster of three candidate genes (des, desK, and desR), whose mRNA levels in WN1106 were higher than the ancestor on the microarrays. Up-regulation of these genes was confirmed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. The des, desK, and desR genes encode the Des membrane fatty acid (FA) desaturase, the DesK sensor kinase, and the DesR response regulator, respectively, which function to maintain membrane fluidity in acute response to temperature downshift. Pressure downshift caused an up-regulation of des mRNA levels only in WN1106, but expression of a des-lacZ transcriptional fusion was unaffected, which suggests that des regulation was different in response to temperature versus pressure downshift. Competition experiments showed that inactivation of the des gene caused a slight, but statistically significant, loss of fitness of strain WN1106 at 50 mbar. Further, analysis of membrane FA composition of cells grown at 1013 versus 50 mbar revealed a decrease in the ratio of unsaturated to saturated FAs but an increase in the ratio of anteiso- to iso-FAs. The present study represents a first step toward identification of molecular mechanisms by which B. subtilis could sense and respond to the novel environmental stress

  8. Diabetes: energetics, development and human evolution.

    PubMed

    Campbell, B C; Cajigal, A

    2001-07-01

    The recent emergence of the thrifty phenotype as an explanation for metabolic efficiency has brought evolutionary perspectives on diabetes, as represented by the thrifty genotype, under scrutiny. However, the logic of natural selection along with evidence from non-human primates supports the role for energetic constraints in the evolution of metabolic efficiency, particularly in skeletal muscle physiology. Environmental fluctuation during human evolution would have provided selective pressures for the development of efficient skeletal muscle starting prenatally and continuing throughout the lifespan. Such mechanisms including, glucose transporters, mitochondrial gene expression, leptin receptors and uncoupling proteins, should be present in all humans, though some living populations may exhibit particular 'thriftier' alleles. A focus on physical activity and the factors underlying efficient muscle physiology has implications for prevention of diabetes in both developing and developed societies. Copyright 2001 Harcourt Publishers Ltd.

  9. Inflorescences: concepts, function, development and evolution

    PubMed Central

    Kirchoff, Bruce K.; Claßen-Bockhoff, Regine

    2013-01-01

    Background Inflorescences are complex structures with many functions. At anthesis they present the flowers in ways that allow for the transfer of pollen and optimization of the plant's reproductive success. During flower and fruit development they provide nutrients to the developing flowers and fruits. At fruit maturity they support the fruits prior to dispersal, and facilitate effective fruit and seed dispersal. From a structural point of view, inflorescences have played important roles in systematic and phylogenetic studies. As functional units they facilitate reproduction, and are largely shaped by natural selection. Scope The papers in this Special Issue bridge the gap between structural and functional approaches to inflorescence evolution. They include a literature review of inflorescence function, an experimental study of inflorescences as essential contributors to the display of flowers, and two papers that present new methods and concepts for understanding inflorescence diversity and for dealing with terminological problems. The transient model of inflorescence development is evaluated in an ontogenetic study, and partially supported. Four papers present morphological and ontogenetic studies of inflorescence development in monophyletic groups, and two of these evaluate the usefulness of Hofmeister's Rule and inhibitory fields to predict inflorescence structure. In the final two papers, Bayesian and Monte-Carlo methods are used to elucidate inflorescence evolution in the Panicoid grasses, and a candidate gene approach is used in an attempt to understand the evolutionary genetics of inflorescence evolution in the genus Cornus (Cornaceae). Taken as a whole, the papers in this issue provide a glimpse of contemporary approaches to the study of the structure, development, and evolution of inflorescences, and suggest fruitful new directions for research. PMID:24383103

  10. Evolution des quasiparticules nodales du cuprate supraconducteur YBa2Cu3Oy en conductivite thermique

    NASA Astrophysics Data System (ADS)

    Rene de Cotret, Samuel

    Ce memoire presente des mesures de conductivite thermique sur les supraconducteurs YBCO et Tl-2201 afin de statuer sur la presence possible d'un point critique quantique (QCP) dans le diagramme de phase de cuprates. Ce point critique quantique serait a l'origine de la reconstruction de la surface de Fermi, d'un large cylindre de trous en de petites poches de trous et d'electrons. La conductivite thermique dans le regime T → 0 permet d'extraire une quantite purement electronique liee aux vitesses de Fermi et du gap, au noeud. Une discontinuite dans cette quantite pourrait signaler la traversee du dopage critique qui reconstruit la surface de Fermi. Plusieurs sondes experimentales distinguent une transition de phase ou un crossover a T* a temperature finie. D'autres sondes mettent en evidence une transition de phase sous l'effet d'un champ magnetique. La presence ou non de cet ordre, a temperature et champ magnetique nul questionne la communaute depuis plusieurs annees. Dans cette etude, nous detectons une variation brusque de kappa0/T a p = 0.18 dans YBCO et a p = 0.20 dans Tl-2201. Ces sauts sont interpretes comme un signe de la transition a temperature nulle et sont en faveur d'un QCP. Le manque de donnees d'un meme materiau a ces dopages ne permet pas de valider hors de tout doute l'existence d'un point critique quantique. Le modele theorique YRZ decrit aussi bien les donnees de conductivite thermique. Des pistes de travaux experimentaux a poursuivre sont proposees pour determiner la presence ou non du QCP de facon franche. Mots-cles : Supraconducteurs, cuprates, conductivite thermique, point critique quantique.

  11. Evolution and development of monocot stomata.

    PubMed

    Rudall, Paula J; Chen, Elisabeth D; Cullen, Erin

    2017-08-09

    Leaves of monocots are typically linear with parallel venation, though a few taxa have broad leaves. Studies of stomatal patterning and development in monocots required updating in the context of rapidly improving knowledge of both the phylogenetic and development-genetic context of monocots that facilitate studies of character evolution. We used an existing microscope-slide collection to obtain data on stomatal structure across all the major monocot clades, including some species with relatively broad leaves. In addition, we used both light and electron microscopy to study stomatal development in 16 selected species. We evaluated these data in a phylogenetic context to assess stomatal character evolution. Mature stomatal patterning in monocots can be broadly categorized as anomocytic, paracytic-nonoblique, and paracytic/tetracytic oblique, depending on the presence, development, and arrangement of lateral subsidiary cells. Stomatal meristemoids invariably result from an asymmetric mitosis in monocots. In species where lateral subsidiary cells are present, they are perigene cells. Among monocots with relatively broad leaves, stomatal orientation is linear-axial in most taxa, but transverse in Lapageria and Stemona, and random in Dioscorea and some Araceae. Amplifying divisions are apparently absent in monocots. Anomocytic stomata represent the likely ancestral (plesiomorphic) condition in monocots, though multiple evolutionary transitions and reversals have occurred. Paracytic-nonoblique stomata with highly modified perigene lateral neighbor cells characterize grasses and other Poales. The presence of anomocytic stomata in Japonolirion and Tofieldia reinforces the concept that these two genera have retained many ancestral monocot features and are critical in understanding character evolution in monocots. © 2017 Botanical Society of America.

  12. Haeckel's ABC of evolution and development.

    PubMed

    Richardson, Michael K; Keuck, Gerhard

    2002-11-01

    One of the central, unresolved controversies in biology concerns the distribution of primitive versus advanced characters at different stages of vertebrate development. This controversy has major implications for evolutionary developmental biology and phylogenetics. Ernst Haeckel addressed the issue with his Biogenetic Law, and his embryo drawings functioned as supporting data. We re-examine Haeckel's work and its significance for modern efforts to develop a rigorous comparative framework for developmental studies. Haeckel's comparative embryology was evolutionary but non-quantitative. It was based on developmental sequences, and treated heterochrony as a sequence change. It is not always clear whether he believed in recapitulation of single characters or entire stages. The Biogenetic Law is supported by several recent studies -- if applied to single characters only. Haeckel's important but overlooked alphabetical analogy of evolution and development is an advance on von Baer. Haeckel recognized the evolutionary diversity in early embryonic stages, in line with modern thinking. He did not necessarily advocate the strict form of recapitulation and terminal addition commonly attributed to him. Haeckel's much-criticized embryo drawings are important as phylogenetic hypotheses, teaching aids, and evidence for evolution. While some criticisms of the drawings are legitimate, others are more tendentious. In opposition to Haeckel and his embryo drawings, Wilhelm His made major advances towards developing a quantitative comparative embryology based on morphometrics. Unfortunately His's work in this area is largely forgotten. Despite his obvious flaws, Haeckel can be seen as the father of a sequence-based phylogenetic embryology.

  13. Development and Evolution of the Pharyngeal Apparatus

    PubMed Central

    Frisdal, Aude; Trainor, Paul A

    2014-01-01

    The oral or pharyngeal apparatus facilitates the dual functions of respiration and feeding. It develops during embryogenesis from transient structures called pharyngeal arches, which comprise a reiterated series of outgrowths on the lateral side of the head. The pharyngeal arches and their segmental arrangement are highly conserved throughout evolution from invertebrate chordates such as amphioxus, through to vertebrate agnathans including avians, squamates and mammals. The structural organization of the pharyngeal arches is also highly conserved and involves contributions from each of the three primary endoderm, mesoderm and ectoderm germ layers. The endoderm is particularly important for pharyngeal arch formation and segmentation and also plays a critical role in tissue specific differentiation. The ectoderm gives rise to neural crest cells (NCC) which provides an additional layer of complexity to pharyngeal arch development and differentiation in vertebrates compared to invertebrate chordates that do not possess NCC. Collectively the pharyngeal arches give rise to much of the neurovasculature and musculoskeletal systems in the head and neck. The complexity of development renders the pharyngeal apparatus prone to perturbation and subsequently the pathogenesis of birth defects. Hence it is important to understand the signals and mechanisms that govern the development and evolution of the pharyngeal complex. PMID:25176500

  14. Development and Testing of a Field Diagnostic Assay for Peste des Petits Ruminants Virus

    PubMed Central

    Baron, J; Fishbourne, E; Couacy-Hyman, E; Abubakar, M; Jones, B A; Frost, L; Herbert, R; Chibssa, T R; van't Klooster, G; Afzal, M; Ayebazibwe, C; Toye, P; Bashiruddin, J; Baron, M D

    2014-01-01

    We have developed an immunochromatographic test for the diagnosis of peste des petits ruminants (PPR) under field conditions. The diagnostic assay has been tested in the laboratory and also under field conditions in Ivory Coast, Pakistan, Ethiopia and Uganda. The test is carried out on a superficial swab sample (ocular or nasal) and showed a sensitivity of 84% relative to PCR. The specificity was 95% over all nasal and ocular samples. The test detected as little as 103 TCID50 (50% tissue culture infectious doses) of cell culture-grown virus, and detected virus isolates representing all four known genetic lineages of peste des petits ruminants virus. Virus could be detected in swabs from animals as early as 4 days post-infection, at a time when clinical signs were minimal. Feedback from field trials was uniformly positive, suggesting that this diagnostic tool may be useful for current efforts to control the spread of PPR. PMID:25073647

  15. Geomorphic evolution of the Piton des Neiges volcano (Réunion Island, Indian Ocean): Competition between volcanic construction and erosion since 1.4 Ma

    NASA Astrophysics Data System (ADS)

    Salvany, Tiffany; Lahitte, Pierre; Nativel, Pierre; Gillot, Pierre-Yves

    2012-01-01

    Réunion Island (Indian Ocean) is a volcanic complex whose eruptive history was dominated by the activity of two main edifices: Piton des Neiges (PN) and Piton de la Fournaise (PF) volcanoes. The tropical climate induces erosion processes that permanently compete with volcanic constructional processes. Exposed to the trade winds and associated heavy rainfalls, the northeastern part of the island exhibits the most complex morphological evolution. Geomorphological analysis, performed on a 50 m DEM and associated to new K-Ar ages has clarified the overall history of PN volcano. Each massif is assigned to one of the main building stages of the edifice. In addition, the arrangement of these different massifs reveals that the eruptive phases have led to successive relief inversions and successive excavations of large central depressions in the proximal area. As a result, the younger massifs are always located in more proximal parts of the volcano, the youngest being close to the edifice center. In distal areas, early lava flows were channeled into valleys incised along the massif boundaries, leading to a more complex geochronological organization. Quantitative study of the dissection of PN volcano allows us to propose a minimum eroded volume of 101 ± 44 and 105 ± 41 km 3 for the Mafate and Cilaos "Cirques" (depressions), respectively, during the last 180 kyr and a minimum average long-term erosion rate of 1.2 ± 0.4 km 3/ka. This leads us to estimate the removed volume during the whole history of PN volcano (> 1000 km 3) as equivalent to the volume of the deposits identified on the submarine flanks of Piton des Neiges volcano. Therefore, as regressive erosion appears to be the prevailing geomorphic process during the whole PN history, it questions the presence of major flank collapses younger than 1.4 Ma on this volcano. Erosion processes have largely been neglected in recent models, but our study emphasizes them as a key component of landscape development and a major

  16. Development and evolution of the pallium.

    PubMed

    Medina, Loreta; Abellán, Antonio

    2009-08-01

    The neocortex is the most representative and elaborated structure of the mammalian brain and is related to the achievement of complex cognitive capabilities, which are disturbed following malformation or lesion. Searching for the evolutionary origin of this structure continues to be one of the most important and challenging questions in comparative neurobiology. However, this is extremely difficult because of the highly divergent evolution of the pallium in different vertebrates, which has obscured the comparison. Herein, we review developmental neurobiology data for trying to understand the genetic factors that define and underlie the parcellation of homologous pallial subdivisions in different vertebrates. According to these data, the pallium in all tetrapods parcellates during development into four major histogenetic subdivisions, which are homologous as fields across species. The neocortex derives from the dorsal pallium and, as such, is only comparable to the sauropsidian dorsal pallium (avian hyperpallium and lizard/turtle dorsal cortex). We also tried to identify developmental changes in phylogeny that may be responsible of pallial divergent evolution. In particular, we point out to evolutionary differences regarding the cortical hem (an important signaling center for pallial patterning, that also is a source of Cajal-Retzius cells, which are involved in cortical lamination), which may be behind the distinct organization of the pallium in mammals and non-mammals. In addition, we mention recent data suggesting a correlation between the appearance and elaboration of the subventricular zone (a new germinative cell layer of the developing neocortex), and the evolution of novel cell layers (the supragranular layers) and interneuron subtypes. Finally, we comment on epigenetic factors that modulate the developmental programs, leading to changes in the formation of functional areas in the pallium (within some constraints).

  17. Development, regeneration, and evolution of feathers.

    PubMed

    Chen, Chih-Feng; Foley, John; Tang, Pin-Chi; Li, Ang; Jiang, Ting Xin; Wu, Ping; Widelitz, Randall B; Chuong, Cheng Ming

    2015-01-01

    The feather is a complex ectodermal organ with hierarchical branching patterns. It provides functions in endothermy, communication, and flight. Studies of feather growth, cycling, and health are of fundamental importance to avian biology and poultry science. In addition, feathers are an excellent model for morphogenesis studies because of their accessibility, and their distinct patterns can be used to assay the roles of specific molecular pathways. Here we review the progress in aspects of development, regeneration, and evolution during the past three decades. We cover the development of feather buds in chicken embryos, regenerative cycling of feather follicle stem cells, formation of barb branching patterns, emergence of intrafeather pigmentation patterns, interplay of hormones and feather growth, and the genetic identification of several feather variants. The discovery of feathered dinosaurs redefines the relationship between feathers and birds. Inspiration from biomaterials and flight research further fuels biomimetic potential of feathers as a multidisciplinary research focal point.

  18. Evolution des contraintes résiduelles dans des films minces de tungstène en fonction de l'irradiation

    NASA Astrophysics Data System (ADS)

    Durand, N.; Badawi, K. F.; Goudeau, P.; Naudon, A.

    1994-01-01

    The influence of the irradiation dose upon the residual stresses in 1 000 Å tungsten thin films has been studied by two different techniques. Results show a relaxation of the strong initial compressive stresses σ=- 4,5 GPa) in virgin samples when the irradiation dose increases. The existence of a relaxation threshold is also clearly evidenced, it indicates a strong correlation between the thin film microstructure (point defects, grain size) and the relaxation phenomenon, and consequently, the residual stresses. Nous avons étudié, par deux méthodes différentes, l'évolution des contraintes résiduelles dans des couches minces de 1 000 Å de W en fonction de la dose d'irradiation. Ces expériences mettent en évidence une relaxation des fortes contraintes de compression (σ=- 4,5 GPa) observées dans les échantillons vierges quand la dose de l'irradiation augmente. Notre étude montre par ailleurs, l'existence d'un seuil de relaxation et relie de façon indiscutable, la microstructure de la couche mince (défauts ponctuels, taille de grains) au phénomène de relaxation, donc aux contraintes elles-mêmes.

  19. Evolution and development of the vertebrate ear

    NASA Technical Reports Server (NTRS)

    Fritzsch, B.; Beisel, K. W.

    2001-01-01

    This review outlines major aspects of development and evolution of the ear, specifically addressing issues of cell fate commitment and the emerging molecular governance of these decisions. Available data support the notion of homology of subsets of mechanosensors across phyla (proprioreceptive mechanosensory neurons in insects, hair cells in vertebrates). It is argued that this conservation is primarily related to the specific transducing environment needed to achieve mechanosensation. Achieving this requires highly conserved transcription factors that regulate the expression of the relevant structural genes for mechanosensory transduction. While conserved at the level of some cell fate assignment genes (atonal and its mammalian homologue), the ear has also radically reorganized its development by implementing genes used for cell fate assignment in other parts of the developing nervous systems (e.g., neurogenin 1) and by evolving novel sets of genes specifically associated with the novel formation of sensory neurons that contact hair cells (neurotrophins and their receptors). Numerous genes have been identified that regulate morphogenesis, but there is only one common feature that emerges at the moment: the ear appears to have co-opted genes from a large variety of other parts of the developing body (forebrain, limbs, kidneys) and establishes, in combination with existing transcription factors, an environment in which those genes govern novel, ear-related morphogenetic aspects. The ear thus represents a unique mix of highly conserved developmental elements combined with co-opted and newly evolved developmental elements.

  20. Evolution and development of the vertebrate ear

    NASA Technical Reports Server (NTRS)

    Fritzsch, B.; Beisel, K. W.

    2001-01-01

    This review outlines major aspects of development and evolution of the ear, specifically addressing issues of cell fate commitment and the emerging molecular governance of these decisions. Available data support the notion of homology of subsets of mechanosensors across phyla (proprioreceptive mechanosensory neurons in insects, hair cells in vertebrates). It is argued that this conservation is primarily related to the specific transducing environment needed to achieve mechanosensation. Achieving this requires highly conserved transcription factors that regulate the expression of the relevant structural genes for mechanosensory transduction. While conserved at the level of some cell fate assignment genes (atonal and its mammalian homologue), the ear has also radically reorganized its development by implementing genes used for cell fate assignment in other parts of the developing nervous systems (e.g., neurogenin 1) and by evolving novel sets of genes specifically associated with the novel formation of sensory neurons that contact hair cells (neurotrophins and their receptors). Numerous genes have been identified that regulate morphogenesis, but there is only one common feature that emerges at the moment: the ear appears to have co-opted genes from a large variety of other parts of the developing body (forebrain, limbs, kidneys) and establishes, in combination with existing transcription factors, an environment in which those genes govern novel, ear-related morphogenetic aspects. The ear thus represents a unique mix of highly conserved developmental elements combined with co-opted and newly evolved developmental elements.

  1. The evolution and development of mammalian flight.

    PubMed

    Cooper, Lisa Noelle; Cretekos, Chris J; Sears, Karen E

    2012-01-01

    Mammals have evolved a stunning diversity of limb morphologies (e.g., wings, flippers, hands, and paws) that allowed access to a wide range of habitats. Over 50 million years ago, bats (Order Chiroptera) evolved a wing (composed of a thin membrane encasing long digits) and thereby achieved powered flight. Unfortunately, the fossil record currently lacks any transitional fossils between a rodent-like ancestor and a winged bat. To reconstruct how this important evolutionary transition occurred, researchers have begun to employ an evolutionary developmental approach. This approach has revealed some of the embryological and molecular changes that have contributed to the evolution of the bat wing. For example, bat and mouse forelimb morphologies are similar during earliest limb development. Despite this, some key signaling centers for limb development are already divergent in bat and mouse at these early stages. Bat and mouse limb development continues to diverge, such that at later stages many differences are apparent. For example, at these later stages bats redeploy expression of toolkit genes (i.e., Fgf, Shh, Bmp, Grem) in a novel expression domain to inhibit apoptosis of the interdigital tissues. When results are taken together, a broad picture of the developmental changes that drove the transition from a hand to a wing over 50 million years ago is beginning to take shape. Moreover, studies seem to suggest that small changes in gene regulation during organogenesis can generate large evolutionary changes in phenotype.

  2. Origins and Evolution of Stomatal Development.

    PubMed

    Chater, Caspar C C; Caine, Robert S; Fleming, Andrew J; Gray, Julie E

    2017-06-01

    The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and ICE/SCREAMs (SCRMs), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR (EPF) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis (Arabidopsis thaliana) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants. © 2017 American Society of Plant Biologists. All Rights Reserved.

  3. Human prefrontal cortex: evolution, development, and pathology.

    PubMed

    Teffer, Kate; Semendeferi, Katerina

    2012-01-01

    The prefrontal cortex is critical to many cognitive abilities that are considered particularly human, and forms a large part of a neural system crucial for normal socio-emotional and executive functioning in humans and other primates. In this chapter, we survey the literature regarding prefrontal development and pathology in humans as well as comparative studies of the region in humans and closely related primate species. The prefrontal cortex matures later in development than more caudal regions, and some of its neuronal subpopulations exhibit more complex dendritic arborizations. Comparative work suggests that the human prefrontal cortex differs from that of closely related primate species less in relative size than it does in organization. Specific reorganizational events in neural circuitry may have taken place either as a consequence of adjusting to increases in size or as adaptive responses to specific selection pressures. Living in complex environments has been recognized as a considerable factor in the evolution of primate cognition. Normal frontal lobe development and function are also compromised in several neurological and psychiatric disorders. A phylogenetically recent reorganization of frontal cortical circuitry may have been critical to the emergence of human-specific executive and social-emotional functions, and developmental pathology in these same systems underlies many psychiatric and neurological disorders, including autism and schizophrenia.

  4. The Evolution and Development of Neural Superposition

    PubMed Central

    Agi, Egemen; Langen, Marion; Altschuler, Steven J.; Wu, Lani F.; Zimmermann, Timo

    2014-01-01

    Visual systems have a rich history as model systems for the discovery and understanding of basic principles underlying neuronal connectivity. The compound eyes of insects consist of up to thousands of small unit eyes that are connected by photoreceptor axons to set up a visual map in the brain. The photoreceptor axon terminals thereby represent neighboring points seen in the environment in neighboring synaptic units in the brain. Neural superposition is a special case of such a wiring principle, where photoreceptors from different unit eyes that receive the same input converge upon the same synaptic units in the brain. This wiring principle is remarkable, because each photoreceptor in a single unit eye receives different input and each individual axon, among thousands others in the brain, must be sorted together with those few axons that have the same input. Key aspects of neural superposition have been described as early as 1907. Since then neuroscientists, evolutionary and developmental biologists have been fascinated by how such a complicated wiring principle could evolve, how it is genetically encoded, and how it is developmentally realized. In this review article, we will discuss current ideas about the evolutionary origin and developmental program of neural superposition. Our goal is to identify in what way the special case of neural superposition can help us answer more general questions about the evolution and development of genetically “hard-wired” synaptic connectivity in the brain. PMID:24912630

  5. The evolution and development of neural superposition.

    PubMed

    Agi, Egemen; Langen, Marion; Altschuler, Steven J; Wu, Lani F; Zimmermann, Timo; Hiesinger, Peter Robin

    2014-01-01

    Visual systems have a rich history as model systems for the discovery and understanding of basic principles underlying neuronal connectivity. The compound eyes of insects consist of up to thousands of small unit eyes that are connected by photoreceptor axons to set up a visual map in the brain. The photoreceptor axon terminals thereby represent neighboring points seen in the environment in neighboring synaptic units in the brain. Neural superposition is a special case of such a wiring principle, where photoreceptors from different unit eyes that receive the same input converge upon the same synaptic units in the brain. This wiring principle is remarkable, because each photoreceptor in a single unit eye receives different input and each individual axon, among thousands others in the brain, must be sorted together with those few axons that have the same input. Key aspects of neural superposition have been described as early as 1907. Since then neuroscientists, evolutionary and developmental biologists have been fascinated by how such a complicated wiring principle could evolve, how it is genetically encoded, and how it is developmentally realized. In this review article, we will discuss current ideas about the evolutionary origin and developmental program of neural superposition. Our goal is to identify in what way the special case of neural superposition can help us answer more general questions about the evolution and development of genetically "hard-wired" synaptic connectivity in the brain.

  6. Development and testing of a field diagnostic assay for peste des petits ruminants virus.

    PubMed

    Baron, J; Fishbourne, E; Couacy-Hyman, E; Abubakar, M; Jones, B A; Frost, L; Herbert, R; Chibssa, T R; Van't Klooster, G; Afzal, M; Ayebazibwe, C; Toye, P; Bashiruddin, J; Baron, M D

    2014-10-01

    We have developed an immunochromatographic test for the diagnosis of peste des petits ruminants (PPR) under field conditions. The diagnostic assay has been tested in the laboratory and also under field conditions in Ivory Coast, Pakistan, Ethiopia and Uganda. The test is carried out on a superficial swab sample (ocular or nasal) and showed a sensitivity of 84% relative to PCR. The specificity was 95% over all nasal and ocular samples. The test detected as little as 10(3) TCID50 (50% tissue culture infectious doses) of cell culture-grown virus, and detected virus isolates representing all four known genetic lineages of peste des petits ruminants virus. Virus could be detected in swabs from animals as early as 4 days post-infection, at a time when clinical signs were minimal. Feedback from field trials was uniformly positive, suggesting that this diagnostic tool may be useful for current efforts to control the spread of PPR. © 2014 Blackwell Verlag GmbH.

  7. Development and evolution of cortical fields.

    PubMed

    Arai, Yoko; Pierani, Alessandra

    2014-09-01

    The neocortex is the brain structure that has been subjected to a major size expansion, in its relative size, during mammalian evolution. It arises from the cortical primordium through coordinated growth of neural progenitor cells along both the tangential and radial axes and their patterning providing spatial coordinates. Functional neocortical areas are ultimately consolidated by environmental influences such as peripheral sensory inputs. Throughout neocortical evolution, cortical areas have become more sophisticated and numerous. This increase in number is possibly involved in the complexification of neocortical function in primates. Whereas extensive divergence of functional cortical fields is observed during evolution, the fundamental mechanisms supporting the allocation of cortical areas and their wiring are conserved, suggesting the presence of core genetic mechanisms operating in different species. We will discuss some of the basic molecular mechanisms including morphogen-dependent ones involved in the precise orchestration of neurogenesis in different cortical areas, elucidated from studies in rodents. Attention will be paid to the role of Cajal-Retzius neurons, which were recently proposed to be migrating signaling units also involved in arealization, will be addressed. We will further review recent works on molecular mechanisms of cortical patterning resulting from comparative analyses between different species during evolution. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  8. Phenotypic plasticity in development and evolution: facts and concepts

    PubMed Central

    Fusco, Giuseppe; Minelli, Alessandro

    2010-01-01

    This theme issue pursues an exploration of the potential of taking into account the environmental sensitivity of development to explaining the evolution of metazoan life cycles, with special focus on complex life cycles and the role of developmental plasticity. The evolution of switches between alternative phenotypes as a response to different environmental cues and the evolution of the control of the temporal expression of alternative phenotypes within an organism's life cycle are here treated together as different dimensions of the complex relationships between genotype and phenotype, fostering the emergence of a more general and comprehensive picture of phenotypic evolution through a quite diverse sample of case studies. This introductory article reviews fundamental facts and concepts about phenotypic plasticity, adopting the most authoritative terminology in use in the current literature. The main topics are types and components of phenotypic variation, the evolution of organismal traits through plasticity, the origin and evolution of phenotypic plasticity and its adaptive value. PMID:20083631

  9. Biology Teachers' Professional Development Needs for Teaching Evolution

    ERIC Educational Resources Information Center

    Friedrichsen, Patricia J.; Linke, Nicholas; Barnett, Ellen

    2016-01-01

    The social controversy surrounding the teaching of evolution puts pressure on secondary biology teachers to deemphasize or omit evolution from their curriculum. In this growing pressure, professional development can offer support to biology teachers. In this study, we surveyed secondary biology teachers in Missouri and report the data from…

  10. Biology Teachers' Professional Development Needs for Teaching Evolution

    ERIC Educational Resources Information Center

    Friedrichsen, Patricia J.; Linke, Nicholas; Barnett, Ellen

    2016-01-01

    The social controversy surrounding the teaching of evolution puts pressure on secondary biology teachers to deemphasize or omit evolution from their curriculum. In this growing pressure, professional development can offer support to biology teachers. In this study, we surveyed secondary biology teachers in Missouri and report the data from…

  11. Quantifying the impact of development on phenotypic variation and evolution.

    PubMed

    Sears, Karen E

    2014-12-01

    A primary goal of evolutionary biology is to identify the factors that shape phenotypic evolution. According to the theory of natural selection, phenotypic evolution occurs through the differential survival and reproduction of individuals whose traits are selectively advantageous relative to other individuals in the population. This implies that evolution by natural selection is contingent upon the distribution and magnitude of phenotypic variation among individuals, which are in turn the products of developmental processes. Development therefore has the potential to affect the trajectory and rate of phenotypic evolution. Recent research in diverse systems (e.g., mammalian teeth, cichlid skulls, butterfly wings, and marsupial limbs) supports the hypothesis that development biases phenotypic variation and evolution, but suggests that these biases might be system-specific. © 2014 Wiley Periodicals, Inc.

  12. Dynamical evolution of globular clusters: Recent developments

    NASA Astrophysics Data System (ADS)

    Merafina, Marco

    We analyze structural parameters of the globular clusters belonging to the Milky Way system which were listed in the latest edition of the Harris Catalogue. We search for observational evidences of the effect of tidal forces induced by the Galaxy on the dynamical and thermodynamical evolution of a globular cluster. The behavior for the W0 distribution exhibited by the globular cluster population seems to be in contrast with theoretical results in literature about gravothermal instability, and suggest a new limit value smaller than the previous one.

  13. Arthropod evolution and development: recent insights from chelicerates and myriapods.

    PubMed

    Leite, Daniel J; McGregor, Alistair P

    2016-08-01

    Research on arthropod genetics and development has added much to our understanding of animal evolution. While this work has mainly focused on insects, a growing body of research on the less studied myriapods and chelicerates is providing important new insights into arthropod genomics and development. Multiple chelicerate lineages have a high incidence of gene duplication, which is suggestive of large-scale and even whole genome duplications. Furthermore, the duplication and divergence of genes is associated with the evolution of appendage morphology and other phenotypes in chelicerates and myriapods. Recent studies of these arthropods have also helped to understand the evolution and development of segmented bodies. Further research on chelicerate and myriapod models as well as species from other orders of these subphyla has great potential to expand our understanding of the evolution of animal genomes and development.

  14. Evolution

    NASA Astrophysics Data System (ADS)

    Peter, Ulmschneider

    When we are looking for intelligent life outside the Earth, there is a fundamental question: Assuming that life has formed on an extraterrestrial planet, will it also develop toward intelligence? As this is hotly debated, we will now describe the development of life on Earth in more detail in order to show that there are good reasons why evolution should culminate in intelligent beings.

  15. Did food allergy develop in the process of animal evolution?

    PubMed Central

    Nabavizadeh, Seyed Hesamedin; Nabavizadeh, Sara Sadat; Anushiravani, Amir

    2016-01-01

    Food allergy is pathophysiologic ally based on stimulation of the immune system at the first exposure, and allergic reactions develop during following exposures. Therefore, memory is the cornerstone of an allergy, as seen in the adaptive immune system. The adaptive immune system was first introduced during evolution in vertebrates, so we can say that invertebrates do not have allergic reactions. We can conclude that food allergy is a complication of animal evolution. Evolution also can cause diseases and complications; therefore, understanding it may help in allergy treatment. PMID:28163859

  16. The evolution, morphology, and development of fern leaves

    PubMed Central

    Vasco, Alejandra; Moran, Robbin C.; Ambrose, Barbara A.

    2013-01-01

    Leaves are lateral determinate structures formed in a predictable sequence (phyllotaxy) on the flanks of an indeterminate shoot apical meristem. The origin and evolution of leaves in vascular plants has been widely debated. Being the main conspicuous organ of nearly all vascular plants and often easy to recognize as such, it seems surprising that leaves have had multiple origins. For decades, morphologists, anatomists, paleobotanists, and systematists have contributed data to this debate. More recently, molecular genetic studies have provided insight into leaf evolution and development mainly within angiosperms and, to a lesser extent, lycophytes. There has been recent interest in extending leaf evolutionary developmental studies to other species and lineages, particularly in lycophytes and ferns. Therefore, a review of fern leaf morphology, evolution and development is timely. Here we discuss the theories of leaf evolution in ferns, morphology, and diversity of fern leaves, and experimental results of fern leaf development. We summarize what is known about the molecular genetics of fern leaf development and what future studies might tell us about the evolution of fern leaf development. PMID:24027574

  17. Frogs without polliwogs: evolution of anuran direct development.

    PubMed

    Callery, E M; Fang, H; Elinson, R P

    2001-03-01

    Direct development is the assumption of the adult morphology without progression through an intervening, morphologically distinct, free-living larval phase. We discuss the ecological factors contributing to the evolution of this derived life-history strategy in frogs, and the developmental modifications that facilitate such an unusual mode of embryogenesis. Studies on the Puerto Rican tree frog, Eleutherodactylus coqui, have identified several such modifications, including developmental adaptations for dealing with increased egg size, and loss of tadpole structures. Surprisingly, this direct developer still undergoes a thyroid hormone-dependent metamorphosis, which occurs before hatching. We suggest how the ancestral biphasic developmental pattern may have been rearranged during the evolution of direct development.

  18. The Evolution from Traditional to Online Professional Development: A Review

    ERIC Educational Resources Information Center

    Elliott, Joshua C.

    2017-01-01

    Online professional development offers opportunities for growth to teachers who may not be able to participate otherwise due to constraints. These constraints include, but are not limited to, time and travel distance. This document is a narrative review of relevant literature as it relates to the evolution of teacher professional development. This…

  19. The Evolution of Army Leader Development

    DTIC Science & Technology

    2013-03-01

    and International Studies, 2006), 16; M . Wade 24 Markel, Henry A . Leonard, Charlotte Lynch, Christina Panis, Peter Schirmer, Carra S . Sims...847. 8 M . Wade Markel, Henry A . Leonard, Charlotte Lynch, Christina Panis, Peter Schirmer, Carra S . Sims, Developing U.S. Army Officers...Department of the Army, 01 February, 2010), 15. 10 ibid 11 M . Wade Markel, Henry A . Leonard, Charlotte Lynch, Christina Panis, Peter Schirmer, Carra S

  20. Evolution, development, and the emergence of disgust.

    PubMed

    Rottman, Joshua

    2014-04-29

    Evolutionary developmental psychology typically utilizes an evolutionary lens to explain various phenomena that occur throughout development. In this paper, I argue that the converse is also important: Developmental evidence can inform evolutionary theory. In particular, knowledge about the developmental origins of a psychological trait can be used to evaluate theoretical claims about its evolved function. I use the emotion of disgust as a case study to illustrate this approach. Disgust is commonly thought to be a behavioral adaptation for avoiding the ingestion of pathogens. Given this claim, disgust should be expected to develop at a time when humans are especially vulnerable to the dangers of ingesting pathogens, during the immediate post-weaning period from about 3 to 5 years of age. Despite a strong selective pressure at this point in development, research has suggested that the emotion of disgust and the recognition of the "disgust face" do not reliably emerge until later in ontogeny, at 5 years of age or after. Given the late developmental appearance of disgust, I re-evaluate claims about its adaptive role.

  1. Injectabilite des coulis de ciment dans des milieux fissures

    NASA Astrophysics Data System (ADS)

    Mnif, Thameur

    Le travail presente ici est un bilan du travaux de recherche effectues sur l'injectabilite des coulis de ciment dans lu milieux fissures. Un certain nombre de coulis a base de ciment Portland et microfin ont ete selectionnes afin de caracteriser leur capacite a penetrer des milieux fissures. Une partie des essais a ete menee en laboratoire. L'etude rheologique des differents melanges a permis de tester l'influence de l'ajout de superplastifiant et/ou de fumee de silice sur la distribution granulometrique des coulis et par consequent sur leur capacite a injecter des colonnes de sable simulant un milieu fissure donne. La classe granulometrique d'un coulis, sa stabilite et sa fluidite sont apparus comme les trois facteurs principaux pour la reussite d'une injection. Un facteur de finesse a ete defini au cours de cette etude: base sur la classe granulometrique du ciment et sa stabilite, il peut entrer dans la formulation theorique du debit d'injection avant application sur chantier. La deuxieme et derniere partie de l'etude presente les resultats de deux projets de recherche sur l'injection realises sur chantier. L'injection de dalles de beton fissurees a permis le suivi de l'evolution des pressions avec la distance au point d'injection. L'injection de murs de maconnerie a caractere historique a montre l'importance de la definition de criteres de performance des coulis a utiliser pour traiter un milieu donne et pour un objectif donne. Plusieurs melanges peuvent ainsi etre predefinis et mis a disposition sur le chantier. La complementarite des ciments traditionnels et des ciments microfins devient alors un atout important. Le choix d'utilisation de ces melanges est fonction du terrain rencontre. En conclusion, cette recherche etablit une methodologie pour la selection des coulis a base de ciment et des pressions d'injection en fonction de l'ouverture des fissures ou joints de construction.

  2. Telerobotic work system: Concept development and evolution

    NASA Technical Reports Server (NTRS)

    Jenkins, Lyle M.

    1987-01-01

    The basic concept of a telerobotic work system (TWS) consists of two dexterous manipulator arms controlled from a remote station. The term telerobotic describes a system that is a combination of teleoperator control and robotic operation. Work represents the function of producing physical changes. System describes the integration of components and subsystems to effectively accomplish the needed mission. Telerobotics reduces exposure to hazards for flight crewmembers and increases their productivity. The requirements for the TWS are derived from both the mission needs and the functional capabilities of existing hardware and software to meet those needs. The development of the TWS is discussed.

  3. Evolution of meiosis timing during floral development

    PubMed Central

    Johnston, M. O.

    1999-01-01

    Meiosis divides the haploid and diploid portions of the life cycle in all sexual organisms. In angiosperms meiosis occurs during flower development, the duration of which varies widely among species and is affected by environmental conditions within species. For 36 species representing 13 angiosperm families, we determined the time at which meiosis ceased in the anthers as a fraction of the total time from floral primordium initiation (beginning of development) to flower opening (end). It was found that this fraction, rather than being continuously distributed among species, occurred in three discrete classes despite wide variations within and among species in absolute developmental durations. Each species was characterized by a single timing class. For all species within a given timing class, therefore, the durations before and after the end of microsporocyte meiosis existed in constant ratio. Each timing class was found in phylogenetically distant species; conversely, a plant family often contained more than one class. Timing class was not related to ploidy level, inflorescence architecture, pollination syndrome or mating system. These findings show that either the durations before and after microsporocyte meiosis are regulated by the same exogenous process, or one duration determines the other. They further imply that the underlying developmental processes have evolved in a limited number of ways among flowering plants.

  4. Evolution, development and intentional control of imitation

    PubMed Central

    Heyes, Cecilia

    2009-01-01

    Imitation is at the heart of social cognitive neuroscience. It is a neurocognitive process that bridges the gap between minds; powers cognitive and social development; promotes cooperation and well-being; and provides a channel of cultural inheritance. The papers in this theme issue review cutting-edge research on imitation and report original data using all of the principal methodologies, including comparative, developmental, cognitive-behavioural and neurological techniques. This paper introduces these interdisciplinary contributions and, proposing that the field currently has four inter-related foci—correspondence, control, cooperation and cultural inheritance—offers an overview of the state-of-the-art in research on the mechanisms and functions of imitation. PMID:19620101

  5. MCPH1: a window into brain development and evolution

    PubMed Central

    Pulvers, Jeremy N.; Journiac, Nathalie; Arai, Yoko; Nardelli, Jeannette

    2015-01-01

    The development of the mammalian cerebral cortex involves a series of mechanisms: from patterning, progenitor cell proliferation and differentiation, to neuronal migration. Many factors influence the development of the cerebral cortex to its normal size and neuronal composition. Of these, the mechanisms that influence the proliferation and differentiation of neural progenitor cells are of particular interest, as they may have the greatest consequence on brain size, not only during development but also in evolution. In this context, causative genes of human autosomal recessive primary microcephaly, such as ASPM and MCPH1, are attractive candidates, as many of them show positive selection during primate evolution. MCPH1 causes microcephaly in mice and humans and is involved in a diverse array of molecular functions beyond brain development, including DNA repair and chromosome condensation. Positive selection of MCPH1 in the primate lineage has led to much insight and discussion of its role in brain size evolution. In this review, we will present an overview of MCPH1 from these multiple angles, and whilst its specific role in brain size regulation during development and evolution remain elusive, the pieces of the puzzle will be discussed with the aim of putting together the full picture of this fascinating gene. PMID:25870538

  6. MCPH1: a window into brain development and evolution.

    PubMed

    Pulvers, Jeremy N; Journiac, Nathalie; Arai, Yoko; Nardelli, Jeannette

    2015-01-01

    The development of the mammalian cerebral cortex involves a series of mechanisms: from patterning, progenitor cell proliferation and differentiation, to neuronal migration. Many factors influence the development of the cerebral cortex to its normal size and neuronal composition. Of these, the mechanisms that influence the proliferation and differentiation of neural progenitor cells are of particular interest, as they may have the greatest consequence on brain size, not only during development but also in evolution. In this context, causative genes of human autosomal recessive primary microcephaly, such as ASPM and MCPH1, are attractive candidates, as many of them show positive selection during primate evolution. MCPH1 causes microcephaly in mice and humans and is involved in a diverse array of molecular functions beyond brain development, including DNA repair and chromosome condensation. Positive selection of MCPH1 in the primate lineage has led to much insight and discussion of its role in brain size evolution. In this review, we will present an overview of MCPH1 from these multiple angles, and whilst its specific role in brain size regulation during development and evolution remain elusive, the pieces of the puzzle will be discussed with the aim of putting together the full picture of this fascinating gene.

  7. Evolution and development in cave animals: from fish to crustaceans

    PubMed Central

    Protas, Meredith; Jeffery, William R.

    2013-01-01

    Cave animals are excellent models to study the general principles of evolution as well as the mechanisms of adaptation to a novel environment: the perpetual darkness of caves. In this article, two of the major model systems used to study the evolution and development (evo–devo) of cave animals are described: the teleost fish Astyanax mexicanus and the isopod crustacean Asellus aquaticus. The ways in which these animals match the major attributes expected of an evo–devo cave animal model system are described. For both species, we enumerate the regressive and constructive troglomorphic traits that have evolved during their adaptation to cave life, the developmental and genetic basis of these traits, the possible evolutionary forces responsible for them, and potential new areas in which these model systems could be used for further exploration of the evolution of cave animals. Furthermore, we compare the two model cave animals to investigate the mechanisms of troglomorphic evolution. Finally, we propose a few other cave animal systems that would be suitable for development as additional models to obtain a more comprehensive understanding of the developmental and genetic mechanisms involved in troglomorphic evolution. PMID:23580903

  8. Evolution and development in cave animals: from fish to crustaceans.

    PubMed

    Protas, Meredith; Jeffery, William R

    2012-01-01

    Cave animals are excellent models to study the general principles of evolution as well as the mechanisms of adaptation to a novel environment: the perpetual darkness of caves. In this article, two of the major model systems used to study the evolution and development (evo-devo) of cave animals are described: the teleost fish Astyanax mexicanus and the isopod crustacean Asellus aquaticus. The ways in which these animals match the major attributes expected of an evo-devo cave animal model system are described. For both species, we enumerate the regressive and constructive troglomorphic traits that have evolved during their adaptation to cave life, the developmental and genetic basis of these traits, the possible evolutionary forces responsible for them, and potential new areas in which these model systems could be used for further exploration of the evolution of cave animals. Furthermore, we compare the two model cave animals to investigate the mechanisms of troglomorphic evolution. Finally, we propose a few other cave animal systems that would be suitable for development as additional models to obtain a more comprehensive understanding of the developmental and genetic mechanisms involved in troglomorphic evolution.

  9. The Evolution, Development, and Future of Affirmative Action in Government.

    ERIC Educational Resources Information Center

    Davis, James Edward

    This thesis discusses the evolution, development, and future of affirmative action in government. Executive Order 11246 formally created affirmative action in 1965 as a remedy for underuse of minorities and women in the workplace and classroom. Many private businesses believe government organizations promote diversity and social equity. Many local…

  10. Faculty Development in Medicine: A Field in Evolution

    ERIC Educational Resources Information Center

    Skeff, Kelley M.; Stratos, Georgette A.; Mount, Jane F. S.

    2007-01-01

    This article focuses on the evolution of faculty development in medicine. Of note, improving teaching in medical education is not a new concept. At a minimum, it was seriously discussed by pioneers like George Miller and Steve Abrahamson as early as the 1950s [Simpson & Bland (2002). Stephen Abrahamson, PhD, ScD, educationist: A stranger in a kind…

  11. The plant vascular system: Evolution, development and functions

    Treesearch

    William J. Lucas; Andrew Groover; Raffael Lichtenberger; Kaori Furuta; Shri-Ram Yadav; Yka Helariutta; Xin-Qiang He; Hiroo Fukuda; Julie Kang; Siobhan M. Brady; John W. Patrick; John Sperry; Akiko Yoshida; Ana-Flor Lopez-Millan; Michael A. Grusak; Pradeep Kachroo

    2013-01-01

    The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made...

  12. The evolution of development of vascular cambia and secondary growth

    Treesearch

    Andrew Groover; Rachel Spicer

    2010-01-01

    Secondary growth from vascular cambia results in radial, woody growth of stems. The innovation of secondary vascular development during plant evolution allowed the production of novel plant forms ranging from massive forest trees to flexible, woody lianas. We present examples of the extensive phylogenetic variation in secondary vascular growth and discuss current...

  13. Faculty Development in Medicine: A Field in Evolution

    ERIC Educational Resources Information Center

    Skeff, Kelley M.; Stratos, Georgette A.; Mount, Jane F. S.

    2007-01-01

    This article focuses on the evolution of faculty development in medicine. Of note, improving teaching in medical education is not a new concept. At a minimum, it was seriously discussed by pioneers like George Miller and Steve Abrahamson as early as the 1950s [Simpson & Bland (2002). Stephen Abrahamson, PhD, ScD, educationist: A stranger in a kind…

  14. The plant vascular system: Evolution, development and functions

    USDA-ARS?s Scientific Manuscript database

    The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of ...

  15. [Historical evolution and development countermeasures of uncommon-territorial herbs].

    PubMed

    Peng, Hua-sheng; Wang, De-qun; Hao, Jin-da; Xie, Jin; Liu, He-ling; Peng, Dai-yin; Huang, Lu-qi

    2015-05-01

    As an important part of Chinese medicinal materials, uncommon-territorial herbs are also the most complex parts in the herbal medicine markets. Through years of investigation on the key markets of Chinese herbal medicine, the meaning of uncommon-territorial herbs, their historical evolution, origin and characteristics were clarified in this paper, and some countermeasures were put forward for its development.

  16. [Graphic Evolution Witness the Development of Lung Cancer Translational Research].

    PubMed

    Zhang, Chao; Zhong, Wenzhao

    2016-06-20

    Lung cancer treatment has altered from conventional chemotherapy to targeted treatment, which now has been turned to the immunotherapy. Translational research has played an irreplaceable role during this progression which graphic evolution has witnessed. The evolution has gone through forest plot, KM-curve, waterfall plot, spider plot and timeline-area, showing us the refining concept and gradual process of lung cancer treatment undergoing from community towards individual. Even though the latest immunotherapy is getting increasingly hot, the result isn't quite expected. Meanwhile, the limitations of conventional treatment still exist which require further research. This article will primarily illustrate the development of translational research of lung cancer via the aspect of curve evolution and analysis some abortive clinical trials in lung cancer surgery for inspiring the next graphic style and lung cancer treatment.

  17. Modeling the connection between development and evolution: Preliminary report

    SciTech Connect

    Mjolsness, E.; Reinitz, J.; Garrett, C.D.; Sharp, D.H.

    1993-07-29

    In this paper we outline a model which incorporates development processes into an evolutionary frame work. The model consists of three sectors describing development, genetics, and the selective environment. The formulation of models governing each sector uses dynamical grammars to describe processes in which state variables evolve in a quantitative fashion, and the number and type of participating biological entities can change. This program has previously been elaborated for development. Its extension to the other sectors of the model is discussed here and forms the basis for further approximations. A specific implementation of these ideas is described for an idealized model of the evolution of a multicellular organism. While this model doe not describe an actual biological system, it illustrates the interplay of development and evolution. Preliminary results of numerical simulations of this idealized model are presented.

  18. PIN proteins and the evolution of plant development.

    PubMed

    Bennett, Tom

    2015-08-01

    Many aspects of development in the model plant Arabidopsis thaliana involve regulated distribution of the hormone auxin by the PIN-FORMED (PIN) family of auxin efflux carriers. The role of PIN-mediated auxin transport in other plants is not well understood, but studies in a wider range of species have begun to illuminate developmental mechanisms across land plants. In this review, I discuss recent progress in understanding the evolution of PIN-mediated auxin transport, and its role in development across the green plant lineage. I also discuss the idea that changes in auxin biology led to morphological novelty in plant development: currently available evidence suggests major innovations in auxin transport are rare and not associated with the evolution of new developmental mechanisms.

  19. Evolution.

    ERIC Educational Resources Information Center

    Mayr, Ernst

    1978-01-01

    Traces the history of evolution theory from Lamarck and Darwin to the present. Discusses natural selection in detail. Suggests that, besides biological evolution, there is also a cultural evolution which is more rapid than the former. (MA)

  20. Evolution.

    ERIC Educational Resources Information Center

    Mayr, Ernst

    1978-01-01

    Traces the history of evolution theory from Lamarck and Darwin to the present. Discusses natural selection in detail. Suggests that, besides biological evolution, there is also a cultural evolution which is more rapid than the former. (MA)

  1. From molecules to mastication: the development and evolution of teeth

    PubMed Central

    Jheon, Andrew H.; Seidel, Kerstin; Biehs, Brian; Klein, Ophir D.

    2012-01-01

    Teeth are unique to vertebrates and have played a central role in their evolution. The molecular pathways and morphogenetic processes involved in tooth development have been the focus of intense investigation over the past few decades, and the tooth is an important model system for many areas of research. Developmental biologists have exploited the clear distinction between the epithelium and the underlying mesenchyme during tooth development to elucidate reciprocal epithelial/mesenchymal interactions during organogenesis. The preservation of teeth in the fossil record makes these small organs essential for the work of paleontologists, anthropologists, and evolutionary biologists. In addition, with the recent identification and characterization of dental stem cells, teeth have become of interest to the field of regenerative medicine. Here, we review the major research areas and studies in the development and evolution of teeth, including morphogenesis, genetics and signaling, evolution of tooth development, and dental stem cells. Brief discussions of microRNAs and human disease as they apply to teeth are also included. PMID:24009032

  2. Peste des petits ruminants.

    PubMed

    Parida, S; Muniraju, M; Mahapatra, M; Muthuchelvan, D; Buczkowski, H; Banyard, A C

    2015-12-14

    Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants.

  3. Peste des petits ruminants

    PubMed Central

    Parida, S.; Muniraju, M.; Mahapatra, M.; Muthuchelvan, D.; Buczkowski, H.; Banyard, A.C.

    2015-01-01

    Peste des petits ruminants virus causes a highly infectious disease of small ruminants that is endemic across Africa, the Middle East and large regions of Asia. The virus is considered to be a major obstacle to the development of sustainable agriculture across the developing world and has recently been targeted by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) for eradication with the aim of global elimination of the disease by 2030. Fundamentally, the vaccines required to successfully achieve this goal are currently available, but the availability of novel vaccine preparations to also fulfill the requisite for differentiation between infected and vaccinated animals (DIVA) may reduce the time taken and the financial costs of serological surveillance in the later stages of any eradication campaign. Here, we overview what is currently known about the virus, with reference to its origin, updated global circulation, molecular evolution, diagnostic tools and vaccines currently available to combat the disease. Further, we comment on recent developments in our knowledge of various recombinant vaccines and on the potential for the development of novel multivalent vaccines for small ruminants. PMID:26443889

  4. Genetic, epigenetic and exogenetic information in development and evolution.

    PubMed

    Griffiths, Paul E

    2017-10-06

    The idea that development is the expression of information accumulated during evolution and that heredity is the transmission of this information is surprisingly hard to cash out in strict, scientific terms. This paper seeks to do so using the sense of information introduced by Francis Crick in his sequence hypothesis and central dogma of molecular biology. It focuses on Crick's idea of precise determination. This is analysed using an information-theoretic measure of causal specificity. This allows us to reconstruct some of Crick's claims about information in transcription and translation. Crick's approach to information has natural extensions to non-coding regions of DNA, to epigenetic marks, and to the genetic or environmental upstream causes of those epigenetic marks. Epigenetic information cannot be reduced to genetic information. The existence of biological information in epigenetic and exogenetic factors is relevant to evolution as well as to development.

  5. Movers and shakers: evolution and development of the mesoderm.

    PubMed

    Davidson, Brad

    2008-01-15

    Groundbreaking research in a wide variety of organisms has begun to address fundamental questions regarding the evolutionary origin of mesoderm and how patterning of this emergent tissue layer has played a central role in the diversification of metazoan body plans. However, attempts to synthesize this growing body of research have been limited. To address this perceived gap, a symposium entitled "Movers and Shakers: The Evolution and Development of Mesoderm" was held at the 2006 Society for Integrative and Comparative Biology Conference in Orlando, Florida. The papers derived from this symposium cover a broad range of organisms and approaches. It was our intention that integration of the data and methodologies from these diverse research programs would generate new hypotheses and collaborative efforts to decipher fundamental questions of mesoderm development and evolution.

  6. The diversity, development and evolution of polyclad flatworm larvae

    PubMed Central

    2014-01-01

    Polyclad flatworms offer an excellent system with which to explore the evolution of larval structures and the ecological and developmental mechanisms driving flatworm and marine invertebrate life history evolution. Although the most common mode of development in polyclads might be direct development (where the embryo develops directly into a form resembling the young adult), there are many species that develop indirectly, through a planktonic phase with transient larval features, before settling to the sea floor. In this review, I introduce polyclad life history strategies, larval diversity and larval anatomical features (presenting previously unpublished micrographs of a diversity of polyclad larvae). I summarize what is known about polyclad larval development during the planktonic phase and the transition to the benthic juvenile. Finally, I discuss evolutionary and developmental scenarios on the origin of polyclad larval characters. The most prominent characters that are found exclusively in the larval stages are lobes that protrude from the body and a ciliary band, or ciliary tufts, at the peripheral margins of the lobes. Larvae with 4–8 and 10 lobes have been described, with most indirect developing species hatching with 8 lobes. A ventral sucker develops in late stage larvae, and I put forward the hypothesis that this is an organ for larval settlement for species belonging to the Cotylea. Historically, the biphasic life cycle of polyclads was thought to be a shared primitive feature of marine invertebrates, with similarities in larval features among phyla resulting from evolutionary conservation. However, our current understanding of animal phylogeny suggests that indirect development in polyclads has evolved independently of similar life cycles found in parasitic flatworms and some other spiralian taxa, and that morphological similarities between the larvae of polyclads and other spiralians are likely a result of convergent evolution. PMID:24602223

  7. Morphology and behaviour: functional links in development and evolution

    PubMed Central

    Bertossa, Rinaldo C.

    2011-01-01

    Development and evolution of animal behaviour and morphology are frequently addressed independently, as reflected in the dichotomy of disciplines dedicated to their study distinguishing object of study (morphology versus behaviour) and perspective (ultimate versus proximate). Although traits are known to develop and evolve semi-independently, they are matched together in development and evolution to produce a unique functional phenotype. Here I highlight similarities shared by both traits, such as the decisive role played by the environment for their ontogeny. Considering the widespread developmental and functional entanglement between both traits, many cases of adaptive evolution are better understood when proximate and ultimate explanations are integrated. A field integrating these perspectives is evolutionary developmental biology (evo-devo), which studies the developmental basis of phenotypic diversity. Ultimate aspects in evo-devo studies—which have mostly focused on morphological traits—could become more apparent when behaviour, ‘the integrator of form and function’, is integrated into the same framework of analysis. Integrating a trait such as behaviour at a different level in the biological hierarchy will help to better understand not only how behavioural diversity is produced, but also how levels are connected to produce functional phenotypes and how these evolve. A possible framework to accommodate and compare form and function at different levels of the biological hierarchy is outlined. At the end, some methodological issues are discussed. PMID:21690124

  8. Etude des Abondances de MG et de fe dans la Composante Stellaire des Disques des Galaxies Spirales

    NASA Astrophysics Data System (ADS)

    Beauchamp, Dominique

    Je presente ici une technique d'observation par imagerie des disques stellaires des galaxies spirales. Je tente, a l'aide d'un modele evolutif multiphase, de determiner les abondances de fer et de magnesium dans les disques. Dans ce but, je mesure les indices Mg2 et Fe5270 du systeme de Lick. Ces elements representent un choix judicieux d'indicateurs car ils sont formes par des supernovae de deux types differents ayant des durees de vie differentes. Le rapport d'abondances de ces deux elements est un indicateur du taux de formation des populations stellaires. Je decris, en premier lieu, les observations, la technique de mesure, ainsi que son application. J'analyse ensuite les indices mesures. A partir du modele multiphase, j'explore differents parametres physiques des spirales comme le taux de formation stellaire, l'evolution des abondances, les effets possibles de la presence de la barre, etc.

  9. The evolution of robust development and homeostasis in artificial organisms.

    PubMed

    Basanta, David; Miodownik, Mark; Baum, Buzz

    2008-03-28

    During embryogenesis, multicellular animals are shaped via cell proliferation, cell rearrangement, and apoptosis. At the end of development, tissue architecture is then maintained through balanced rates of cell proliferation and loss. Here, we take an in silico approach to look for generic systems features of morphogenesis in multicellular animals that arise as a consequence of the evolution of development. Using artificial evolution, we evolved cellular automata-based digital organisms that have distinct embryonic and homeostatic phases of development. Although these evolved organisms use a variety of strategies to maintain their form over time, organisms of different types were all found to rapidly recover from environmental damage in the form of wounds. This regenerative response was most robust in an organism with a stratified tissue-like architecture. An evolutionary analysis revealed that evolution itself contributed to the ability of this organism to maintain its form in the face of genetic and environmental perturbation, confirming the results of previous studies. In addition, the exceptional robustness of this organism to surface injury was found to result from an upward flux of cells, driven in part by cell divisions with a stable niche at the tissue base. Given the general nature of the model, our results lead us to suggest that many of the robust systems properties observed in real organisms, including scar-free wound-healing in well-protected embryos and the layered tissue architecture of regenerating epithelial tissues, may be by-products of the evolution of morphogenesis, rather than the direct result of selection.

  10. Development and psychometric evaluation of the Decisional Engagement Scale (DES-10): A patient-reported psychosocial survey for quality cancer care.

    PubMed

    Hoerger, Michael; Chapman, Benjamin P; Mohile, Supriya G; Duberstein, Paul R

    2016-09-01

    In light of recent health care reforms, we have provided an illustrative example of new opportunities available for psychologists to develop patient-reported measures related to health care quality. Patient engagement in health care decision making has been increasingly acknowledged as a vital component of quality cancer care. We developed the 10-item Decisional Engagement Scale (DES-10), a patient-reported measure of engagement in decision making in cancer care that assesses patients' awareness of their diagnosis, sense of empowerment and involvement, and level of information seeking and planning. The National Institutes of Health's ResearchMatch recruitment tool was used to facilitate Internet-mediated data collection from 376 patients with cancer. DES-10 scores demonstrated good internal consistency reliability (α = .80), and the hypothesized unidimensional factor structure fit the data well. The reliability and factor structure were supported across subgroups based on demographic, socioeconomic, and health characteristics. Higher DES-10 scores were associated with better health-related quality of life (r = .31). In concurrent validity analyses controlling for age, socioeconomic status, and health-related quality of life, higher DES-10 scores were associated with higher scores on quality-of-care indices, including greater awareness of one's treatments, greater preferences for shared decision making, and clearer preferences about end-of-life care. A mini-measure, the DES-3, also performed well psychometrically. In conclusion, DES-10 and DES-3 scores showed evidence of reliability and validity, and these brief patient-reported measures can be used by researchers, clinicians, nonprofits, hospitals, insurers, and policymakers interested in evaluating and improving the quality of cancer care. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  11. Evaluation of potential risk factors for development of primary angle-closure glaucoma in Bouviers des Flandres.

    PubMed

    Dubin, Alexis J; Bentley, Ellison; Buhr, Kevin A; Miller, Paul E

    2017-01-01

    OBJECTIVE To evaluate potential risk factors for development of primary angle-closure glaucoma (PACG) in Bouviers des Flandres. DESIGN Prospective, observational study. ANIMALS 98 Bouviers des Flandres. PROCEDURES All dogs underwent slit-lamp biomicroscopy, indirect ophthalmoscopy, gonioscopy, applanation tonometry, streak retinoscopy, and A-scan, B-scan, and high-resolution ultrasonography. Iridocorneal angles and degree of pectinate ligament dysplasia sheeting were graded, and an angle index was mathematically derived for each eye on the basis of these values. Ciliary clefts evaluated by high-resolution ultrasonography were classified as open, narrow, or closed. Owners were contacted by telephone 7 to 9 years after the initial examination to determine whether dogs had a subsequent diagnosis of PACG. Relationships between previously recorded variables and the development of PACG were evaluated by logistic regression methods. Available pedigrees were reviewed to assess genetic relationships among affected dogs. RESULTS 9 of 92 (9.8%) dogs with follow-up information available developed PACG. An angle index < 1 and presence of a narrow or closed ciliary cleft in 1 or both eyes were each significantly associated with development of PACG. Odds of developing PACG for dogs with an angle index < 1 (indicating marked reduction in outflow capacity through the iridocorneal angle), a narrow or closed ciliary cleft in > 1 eye, or both findings were 13, 20, and 28 times those for dogs that did not have these findings, respectively. All dogs that developed PACG shared 1 common male sire or grandsire. CONCLUSIONS AND CLINICAL RELEVANCE Several anatomic factors were significant risk factors for development of PACG in this population of dogs. Results also suggested a genetic component for the disease.

  12. Development and evolution of the unique cetacean dentition

    PubMed Central

    Zheng, Zhengui; Bajpai, Sunil; Vinyard, Christopher J.; Thewissen, JGM

    2013-01-01

    The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Cetaceans are one of the few groups of mammals in which precise occlusion has been secondarily lost. Most toothed whales have an increased number of simple crowned teeth that are similar along the tooth row. Evolution toward these specializations began immediately after the time cetaceans transitioned from terrestrial-to-marine environments. The fossil record documents the critical aspects of occlusal evolution of cetaceans, and allows us to pinpoint the evolutionary timing of the macroevolutionary events leading to their unusual dental morphology among mammals. The developmental controls of tooth differentiation and tooth number have been studied in a few mammalian clades, but nothing is known about how these controls differ between cetaceans and mammals that retain functional occlusion. Here we show that pigs, a cetacean relative with regionalized tooth morphology and complex tooth crowns, retain the typical mammalian gene expression patterns that control early tooth differentiation, expressing Bmp4 in the rostral (mesial, anterior) domain of the jaw, and Fgf8 caudally (distal, posterior). By contrast, dolphins have lost these regional differences in dental morphology and the Bmp4 domain is extended into the caudal region of the developing jaw. We hypothesize that the functional constraints underlying mammalian occlusion have been released in cetaceans, facilitating changes in the genetic control of early dental development. Such major developmental changes drive morphological evolution and are correlated with major shifts in diet and food processing during cetacean evolution. PMID:23638359

  13. Development and evolution of the unique cetacean dentition.

    PubMed

    Armfield, Brooke A; Zheng, Zhengui; Bajpai, Sunil; Vinyard, Christopher J; Thewissen, Jgm

    2013-01-01

    The evolutionary success of mammals is rooted in their high metabolic rate. A high metabolic rate is sustainable thanks to efficient food processing and that in turn is facilitated by precise occlusion of the teeth and the acquisition of rhythmic mastication. These major evolutionary innovations characterize most members of the Class Mammalia. Cetaceans are one of the few groups of mammals in which precise occlusion has been secondarily lost. Most toothed whales have an increased number of simple crowned teeth that are similar along the tooth row. Evolution toward these specializations began immediately after the time cetaceans transitioned from terrestrial-to-marine environments. The fossil record documents the critical aspects of occlusal evolution of cetaceans, and allows us to pinpoint the evolutionary timing of the macroevolutionary events leading to their unusual dental morphology among mammals. The developmental controls of tooth differentiation and tooth number have been studied in a few mammalian clades, but nothing is known about how these controls differ between cetaceans and mammals that retain functional occlusion. Here we show that pigs, a cetacean relative with regionalized tooth morphology and complex tooth crowns, retain the typical mammalian gene expression patterns that control early tooth differentiation, expressing Bmp4 in the rostral (mesial, anterior) domain of the jaw, and Fgf8 caudally (distal, posterior). By contrast, dolphins have lost these regional differences in dental morphology and the Bmp4 domain is extended into the caudal region of the developing jaw. We hypothesize that the functional constraints underlying mammalian occlusion have been released in cetaceans, facilitating changes in the genetic control of early dental development. Such major developmental changes drive morphological evolution and are correlated with major shifts in diet and food processing during cetacean evolution.

  14. Development of the Verona coding definitions of emotional sequences to code health providers' responses (VR-CoDES-P) to patient cues and concerns.

    PubMed

    Del Piccolo, Lidia; de Haes, Hanneke; Heaven, Cathy; Jansen, Jesse; Verheul, William; Bensing, Jozien; Bergvik, Svein; Deveugele, Myriam; Eide, Hilde; Fletcher, Ian; Goss, Claudia; Humphris, Gerry; Kim, Young-Mi; Langewitz, Wolf; Mazzi, Maria Angela; Mjaaland, Trond; Moretti, Francesca; Nübling, Matthias; Rimondini, Michela; Salmon, Peter; Sibbern, Tonje; Skre, Ingunn; van Dulmen, Sandra; Wissow, Larry; Young, Bridget; Zandbelt, Linda; Zimmermann, Christa; Finset, Arnstein

    2011-02-01

    To present a method to classify health provider responses to patient cues and concerns according to the VR-CoDES-CC (Del Piccolo et al. (2009) [2] and Zimmermann et al. (submitted for publication) [3]). The system permits sequence analysis and a detailed description of how providers handle patient's expressions of emotion. The Verona-CoDES-P system has been developed based on consensus views within the "Verona Network of Sequence Analysis". The different phases of the creation process are described in detail. A reliability study has been conducted on 20 interviews from a convenience sample of 104 psychiatric consultations. The VR-CoDES-P has two main classes of provider responses, corresponding to the degree of explicitness (yes/no) and space (yes/no) that is given by the health provider to each cue/concern expressed by the patient. The system can be further subdivided into 17 individual categories. Statistical analyses showed that the VR-CoDES-P is reliable (agreement 92.86%, Cohen's kappa 0.90 (±0.04) p<0.0001). Once validity and reliability are tested in different settings, the system should be applied to investigate the relationship between provider responses to patients' expression of emotions and outcome variables. Research employing the VR-CoDES-P should be applied to develop research-based approaches to maximize appropriate responses to patients' indirect and overt expressions of emotional needs. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  15. Evolution and development of the homocercal caudal fin in teleosts.

    PubMed

    Moriyama, Yuuta; Takeda, Hiroyuki

    2013-10-01

    The vertebrate caudal skeleton is one of the most innovative structures in vertebrate evolution and has been regarded as an excellent model for functional morphology, a discipline that relates a structure to its function. Teleosts have an internally-asymmetrical caudal fin, called the homocercal caudal fin, formed by the upward bending of the caudal-most portion of the body axis, the ural region. This homocercal type of the caudal fin ensures powerful and complex locomotion and is thought to be one of the most important evolutionary innovations for teleosts during adaptive radiation in an aquatic environment. In this review, we summarize the past and present research of fish caudal skeletons, especially focusing on the homocercal caudal fin seen in teleosts. A series of studies with a medaka spontaneous mutant have provided important insight into the evolution and development of the homocercal caudal skeleton. By comparing developmental processes in various vertebrates, we propose a scenario for acquisition and morphogenesis of the homocercal caudal skeleton during vertebrate evolution.

  16. Genetic Evolution during the development of an attenuated EIAV vaccine.

    PubMed

    Wang, Xue-Feng; Lin, Yue-Zhi; Li, Qiang; Liu, Qiang; Zhao, Wei-Wei; Du, Cheng; Chen, Jie; Wang, Xiaojun; Zhou, Jian-Hua

    2016-02-03

    The equine infectious anemia virus (EIAV) vaccine is the only attenuated lentiviral vaccine applied on a large scale that has been shown to be effective in controlling the prevalence of EIA in China. This vaccine was developed by successive passaging of a field-isolated virulent strain in different hosts and cultivated cells. To explore the molecular basis for the phenotype alteration of this vaccine strain, we systematically analyzed its genomic evolution during vaccine development. Sequence analysis revealed that the genetic distance between the wild-type strain and six representative strains isolated from key development stages gradually increased with the number of passages. Env gene, but not gag and pol, showed a clear evolutionary flow similar to that of the whole genomes of different generations during the attenuation. Stable mutations were identified in multiple regions of multiple genes along with virus passaging. The adaption of the virus to the growth environment of cultured cells with accumulated genomic and genetic variations was positively correlated with the reduction in pathogenicity and rise of immunogenicity. Statistical analyses revealed significant differences in the frequency of the most stable mutations between in vivo and ex vivo-adapted strains and between virulent and attenuated strains. These data indicate that EIAV evolution during vaccine development generated an accumulation of mutations under the selective drive force, which helps to better understand the molecular basis of lentivirus pathogenicity and immunogenicity.

  17. Ferns: the missing link in shoot evolution and development

    PubMed Central

    Plackett, Andrew R. G.; Di Stilio, Verónica S.; Langdale, Jane A.

    2015-01-01

    Shoot development in land plants is a remarkably complex process that gives rise to an extreme diversity of forms. Our current understanding of shoot developmental mechanisms comes almost entirely from studies of angiosperms (flowering plants), the most recently diverged plant lineage. Shoot development in angiosperms is based around a layered multicellular apical meristem that produces lateral organs and/or secondary meristems from populations of founder cells at its periphery. In contrast, non-seed plant shoots develop from either single apical initials or from a small population of morphologically distinct apical cells. Although developmental and molecular information is becoming available for non-flowering plants, such as the model moss Physcomitrella patens, making valid comparisons between highly divergent lineages is extremely challenging. As sister group to the seed plants, the monilophytes (ferns and relatives) represent an excellent phylogenetic midpoint of comparison for unlocking the evolution of shoot developmental mechanisms, and recent technical advances have finally made transgenic analysis possible in the emerging model fern Ceratopteris richardii. This review compares and contrasts our current understanding of shoot development in different land plant lineages with the aim of highlighting the potential role that the fern C. richardii could play in shedding light on the evolution of underlying genetic regulatory mechanisms. PMID:26594222

  18. Caste development and evolution in ants: it's all about size.

    PubMed

    Trible, Waring; Kronauer, Daniel J C

    2017-01-01

    Female ants display a wide variety of morphological castes, including workers, soldiers, ergatoid (worker-like) queens and queens. Alternative caste development within a species arises from a variable array of genetic and environmental factors. Castes themselves are also variable across species and have been repeatedly gained and lost throughout the evolutionary history of ants. Here, we propose a simple theory of caste development and evolution. We propose that female morphology varies as a function of size, such that larger individuals possess more queen-like traits. Thus, the diverse mechanisms that influence caste development are simply mechanisms that affect size in ants. Each caste-associated trait has a unique relationship with size, producing a phenotypic space that permits some combinations of worker- and queen-like traits, but not others. We propose that castes are gained and lost by modifying the regions of this phenotypic space that are realized within a species. These modifications can result from changing the size-frequency distribution of individuals within a species, or by changing the association of tissue growth and size. We hope this synthesis will help unify the literature on caste in ants, and facilitate the discovery of molecular mechanisms underlying caste development and evolution. © 2017. Published by The Company of Biologists Ltd.

  19. On the evolution of early development in the Nematoda.

    PubMed Central

    Goldstein, B

    2001-01-01

    The phylum Nematoda serves as an excellent model system for exploring how development evolves, using a comparative approach to developmental genetics. More than 100 laboratories are studying developmental mechanisms in the nematode Caenorhabditis elegans, and many of the methods that have been developed for C. elegans can be applied to other nematodes. This review summarizes what is known so far about steps in early development that have evolved in the nematodes, and proposes potential experiments that could make use of these data to further our understanding of how development evolves. The promise of such a comparative approach to developmental genetics is to fill a wide gap in our understanding of evolution--a gap spanning from mutations in developmental genes through to their phenotypic results, on which natural selection may act. PMID:11604120

  20. Aquilegia: a new model for plant development, ecology, and evolution.

    PubMed

    Kramer, Elena M

    2009-01-01

    The lower eudicot genus Aquilegia holds enormous potential for investigating aspects of development, ecology, and evolution that are otherwise unrepresented among existing model systems. Its evolutionary history is of particular interest because it represents a phylogenetic midpoint between models such as Arabidopsis and Oryza but, at the same time, has experienced a recent adaptive radiation within the genus. To take advantage of these features, a collaborative group has developed a number of genetic and genomic resources for Aquilegia that have facilitated the study of its distinct morphology. This work has demonstrated that although the petaloid sepals of Aquilegia do not depend on B-class genes for their identity, these loci do control development of the petals, stamens, and novel staminodium. Overall, Aquilegia stands as a key example of the potential utility and speed of developing new genetic model systems.

  1. On the evolution of early development in the Nematoda.

    PubMed

    Goldstein, B

    2001-10-29

    The phylum Nematoda serves as an excellent model system for exploring how development evolves, using a comparative approach to developmental genetics. More than 100 laboratories are studying developmental mechanisms in the nematode Caenorhabditis elegans, and many of the methods that have been developed for C. elegans can be applied to other nematodes. This review summarizes what is known so far about steps in early development that have evolved in the nematodes, and proposes potential experiments that could make use of these data to further our understanding of how development evolves. The promise of such a comparative approach to developmental genetics is to fill a wide gap in our understanding of evolution--a gap spanning from mutations in developmental genes through to their phenotypic results, on which natural selection may act.

  2. New frontiers in the evolution of fin development.

    PubMed

    Freitas, Renata; Gómez-Skarmeta, José Luis; Rodrigues, Pedro Nuno

    2014-11-01

    The locomotory appendages of vertebrates have undergone significant changes during evolution, which likely promoted a wide range of adaptive strategies. These appendages first evolved as unpaired finfolds in the dorsal midline of early chordates, more than 500 million years ago. Later on, during vertebrates' radiation, two sets of locomotory appendages emerged, developing from both sides of the latero-ventral body wall. The morphology of these paired fins in fishes at different phylogenetic positions suggests an evolutionary tendency for increasing elaboration of the endoskeleton and concomitant reduction of the distal dermoskeleton. This evolutionary process culminated with the origin of limbs in the lineages leading to tetrapods. The developmental programs responsible for the evolution of vertebrate appendages have been a major topic for evolutionary developmental biology recently. Gene expression comparisons performed in chordates explored how these mechanisms were transferred from a midline to latero-ventral position. On another front, gene function assays have begun to test classical hypotheses concerning the transition from fish fins to tetrapod limbs. In this review, we highlight these recent findings on the evolution of vertebrate fin development. First, we discuss new perspectives on the transition from midline to paired appendages focus on (i) origin and molecular regionalization of the lateral plate mesoderm and (ii) novel ectodermic competency zones for fin induction. Next, we review recent work exploring how tetrapod limbs evolved from fish fins, considering (i) molecular and structural changes in the distal ectoderm of fins and (ii) modulation of 5'HoxD transcription during fin endoskeleton development. © 2014 Wiley Periodicals, Inc.

  3. Magnetic field effects on plant growth, development, and evolution

    PubMed Central

    Maffei, Massimo E.

    2014-01-01

    The geomagnetic field (GMF) is a natural component of our environment. Plants, which are known to sense different wavelengths of light, respond to gravity, react to touch and electrical signaling, cannot escape the effect of GMF. While phototropism, gravitropism, and tigmotropism have been thoroughly studied, the impact of GMF on plant growth and development is not well-understood. This review describes the effects of altering magnetic field (MF) conditions on plants by considering plant responses to MF values either lower or higher than those of the GMF. The possible role of GMF on plant evolution and the nature of the magnetoreceptor is also discussed. PMID:25237317

  4. Measuring through the microscope: development and evolution of stereological methods.

    PubMed

    Weibel, E R

    1989-09-01

    Obtaining, by means of microscopy, meaningful measurements pertaining to spatial structures requires methods which allow three-dimensional quantitative information to be derived from the reduced information available on the two-dimensional flat sections of the structure. The most powerful methods to that effect are those of stereology which are based on mathematical principles. This paper reviews the early invention of these methods, which sought to solve practical problems, and their further evolution as more rigorous mathematical foundations were developed. It is demonstrated that stereological methods are essentially sampling methods and that newer trends provide new and sound solutions to old and elusive problems, such as anisotropy or particle number and size.

  5. Of mice and genes: evolution of vertebrate brain development

    NASA Technical Reports Server (NTRS)

    Fritzsch, B.

    1998-01-01

    In this review the current understanding of genetic and molecular evolution of development, in particular the formation of the major axis of bilateral animals, is critically evaluated, and the early pattern formation in the hindbrain is related as much as possible to these processes. On the genetic level it is proposed that the exuberant multiplication of regulatory genes compared to that of structural genes relates to the increased flexibility of early vertebrate development. In comparisons to fruit flies, many conserved genes are found to be expressed very differently, while many others seem to reflect a comparable pattern and thus suggest a conservation of function. Even genes with a largely conserved pattern of expression may change the level at which they are expressed and the mechanisms by which they are regulated in their expression. Evolution and development of hindbrain motoneurons is reviewed, and it is concluded that both comparative data as well as more recent experimental data suggest a limited importance for the rhombomeres. Clearly, many cell fate-specifying processes work below the level of rhombomeres or in the absence of rhombomeres. It is suggested that more comparative developmental data are needed to establish firmly the relationship between homeobox genes and rhombomere specification in vertebrates other than a few model species.

  6. Of mice and genes: evolution of vertebrate brain development

    NASA Technical Reports Server (NTRS)

    Fritzsch, B.

    1998-01-01

    In this review the current understanding of genetic and molecular evolution of development, in particular the formation of the major axis of bilateral animals, is critically evaluated, and the early pattern formation in the hindbrain is related as much as possible to these processes. On the genetic level it is proposed that the exuberant multiplication of regulatory genes compared to that of structural genes relates to the increased flexibility of early vertebrate development. In comparisons to fruit flies, many conserved genes are found to be expressed very differently, while many others seem to reflect a comparable pattern and thus suggest a conservation of function. Even genes with a largely conserved pattern of expression may change the level at which they are expressed and the mechanisms by which they are regulated in their expression. Evolution and development of hindbrain motoneurons is reviewed, and it is concluded that both comparative data as well as more recent experimental data suggest a limited importance for the rhombomeres. Clearly, many cell fate-specifying processes work below the level of rhombomeres or in the absence of rhombomeres. It is suggested that more comparative developmental data are needed to establish firmly the relationship between homeobox genes and rhombomere specification in vertebrates other than a few model species.

  7. Chapter 8. Evolution and development in the cavefish Astyanax.

    PubMed

    Jeffery, William R

    2009-01-01

    The teleost Astyanax mexicanus is a single species consisting of two radically different forms: a sighted pigmented surface-dwelling form (surface fish) and a blind depigmented cave-dwelling form (cavefish). The two forms of Astyanax have favorable attributes, including descent from a common ancestor, ease of laboratory culture, and the ability to perform genetic analysis, permitting their use as a model system to explore questions in evolution and development. Here, we review current research on the molecular, cellular, and developmental mechanisms underlying the loss of eyes and pigmentation in Astyanax cavefish. Although functional eyes are lacking in adults, cavefish embryos begin to develop eye primordia, which subsequently degenerate. The major cause of eye degeneration appears to be apoptotic cell death of the lens, which prevents the growth of other optic tissues, including the retina. Ultimately, the loss of the eye is the cause of craniofacial differences between cavefish and surface fish. Lens apoptosis is induced by enhanced activity of the Hedgehog signaling system along the cavefish embryonic midline. The absence of melanin pigmentation in cavefish is due to a block in the ability of undifferentiated melanoblasts to accumulate L-tyrosine, the precursor of L-DOPA and melanin, in melanosomes. Genetic analysis has shown that this defect is caused by a hypomorphic mutation in the p/oca2 gene encoding an integral melanosomal membrane protein. We discuss how current studies of eye and pigment regression have revealed some of the mechanisms in which cavefish development has been changed during evolution.

  8. Coincident development of sesamoid bones and clues to their evolution.

    PubMed

    Sarin, V K; Erickson, G M; Giori, N J; Bergman, A G; Carter, D R

    1999-10-15

    Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity. In this article we review the literature on sesamoids and explore the question of genetic control of sesamoid development. Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella (in the lateral gastrocnemius tendon of the knee) and os peroneum (in the peroneus longus tendon of the foot) are related within individuals (P < 0.01). This finding suggests that the tendency to form sesamoids may be linked to intrinsic genetic factors. Evolutionary character analyses suggest that the formation of these sesamoids in humans may be a consequence of phylogeny. These observations indicate that variations of intrinsic factors may interact with extrinsic mechanobiological factors to influence sesamoid development and evolution.

  9. On the origins of novelty in development and evolution.

    PubMed

    Moczek, Armin P

    2008-05-01

    The origin of novel traits is what draws many to evolutionary biology, yet our understanding of the mechanisms that underlie the genesis of novelty remains limited. Here I review definitions of novelty including its relationship to homology. I then discuss how ontogenetic perspectives may allow us to move beyond current roadblocks in our understanding of the mechanics of innovation. Specifically, I explore the roles of canalization, plasticity and threshold responses during development in generating a reservoir of cryptic genetic variation free to drift and accumulate in natural populations. Environmental or genetic perturbations that exceed the buffering capacity of development can then release this variation, and, through evolution by genetic accommodation, result in rapid diversification, recurrence of lost phenotypes as well as the origins of novel features. I conclude that, in our quest to understand the nature of innovation, the nature of development deserves to take center stage.

  10. A Summary of Transonic Natural Laminar Flow Airfoil Development at NAE (Resume Des Recherches de l’Ena sur des Profils Aerodynamiques A Ecoulements Laminaires Naturels Transsoniques)

    DTIC Science & Technology

    1990-05-01

    connaissances. RAPPORTS TECHNIQUES DE LABORATOIRE (LTR): Informations peu dissdmindes pour des raisons d’usage secret, de droit de propn6t ou autres ou parce ...COULEMENTS LAMINAIRES NATURELS TRANSSONIQUES Acce-,iwn For NTIS CRA&I DTIC TAB Urianoonnced 0 Jusficatcn by/par copy B IVSPEc7rE Dislribiution I M. Khalid...r6sultats exp6rimentaux obtenus pour quatre profils a6rodynamiques I 6coulements laminaires naturels surcritiques qui ont fait l’objet de recherches A

  11. Evolution and development of ventricular septation in the amniote heart.

    PubMed

    Poelmann, Robert E; Gittenberger-de Groot, Adriana C; Vicente-Steijn, Rebecca; Wisse, Lambertus J; Bartelings, Margot M; Everts, Sonja; Hoppenbrouwers, Tamara; Kruithof, Boudewijn P T; Jensen, Bjarke; de Bruin, Paul W; Hirasawa, Tatsuya; Kuratani, Shigeru; Vonk, Freek; van de Put, Jeanne M M S; de Bakker, Merijn A; Richardson, Michael K

    2014-01-01

    During cardiogenesis the epicardium, covering the surface of the myocardial tube, has been ascribed several functions essential for normal heart development of vertebrates from lampreys to mammals. We investigated a novel function of the epicardium in ventricular development in species with partial and complete septation. These species include reptiles, birds and mammals. Adult turtles, lizards and snakes have a complex ventricle with three cava, partially separated by the horizontal and vertical septa. The crocodilians, birds and mammals with origins some 100 million years apart, however, have a left and right ventricle that are completely separated, being a clear example of convergent evolution. In specific embryonic stages these species show similarities in development, prompting us to investigate the mechanisms underlying epicardial involvement. The primitive ventricle of early embryos becomes septated by folding and fusion of the anterior ventricular wall, trapping epicardium in its core. This folding septum develops as the horizontal septum in reptiles and the anterior part of the interventricular septum in the other taxa. The mechanism of folding is confirmed using DiI tattoos of the ventricular surface. Trapping of epicardium-derived cells is studied by transplanting embryonic quail pro-epicardial organ into chicken hosts. The effect of decreased epicardium involvement is studied in knock-out mice, and pro-epicardium ablated chicken, resulting in diminished and even absent septum formation. Proper folding followed by diminished ventricular fusion may explain the deep interventricular cleft observed in elephants. The vertical septum, although indistinct in most reptiles except in crocodilians and pythonidsis apparently homologous to the inlet septum. Eventually the various septal components merge to form the completely septated heart. In our attempt to discover homologies between the various septum components we aim to elucidate the evolution and development

  12. Evolution and Development of Ventricular Septation in the Amniote Heart

    PubMed Central

    Poelmann, Robert E.; Groot, Adriana C. Gittenberger-de; Vicente-Steijn, Rebecca; Wisse, Lambertus J.; Bartelings, Margot M.; Everts, Sonja; Hoppenbrouwers, Tamara; Kruithof, Boudewijn P. T.; Jensen, Bjarke; de Bruin, Paul W.; Hirasawa, Tatsuya; Kuratani, Shigeru; Vonk, Freek; van de Put, Jeanne M. M. S.; de Bakker, Merijn A.; Richardson, Michael K.

    2014-01-01

    During cardiogenesis the epicardium, covering the surface of the myocardial tube, has been ascribed several functions essential for normal heart development of vertebrates from lampreys to mammals. We investigated a novel function of the epicardium in ventricular development in species with partial and complete septation. These species include reptiles, birds and mammals. Adult turtles, lizards and snakes have a complex ventricle with three cava, partially separated by the horizontal and vertical septa. The crocodilians, birds and mammals with origins some 100 million years apart, however, have a left and right ventricle that are completely separated, being a clear example of convergent evolution. In specific embryonic stages these species show similarities in development, prompting us to investigate the mechanisms underlying epicardial involvement. The primitive ventricle of early embryos becomes septated by folding and fusion of the anterior ventricular wall, trapping epicardium in its core. This folding septum develops as the horizontal septum in reptiles and the anterior part of the interventricular septum in the other taxa. The mechanism of folding is confirmed using DiI tattoos of the ventricular surface. Trapping of epicardium-derived cells is studied by transplanting embryonic quail pro-epicardial organ into chicken hosts. The effect of decreased epicardium involvement is studied in knock-out mice, and pro-epicardium ablated chicken, resulting in diminished and even absent septum formation. Proper folding followed by diminished ventricular fusion may explain the deep interventricular cleft observed in elephants. The vertical septum, although indistinct in most reptiles except in crocodilians and pythonidsis apparently homologous to the inlet septum. Eventually the various septal components merge to form the completely septated heart. In our attempt to discover homologies between the various septum components we aim to elucidate the evolution and development

  13. Development of a helper cell-dependent form of peste des petits ruminants virus: a system for making biosafe antigen.

    PubMed

    Baron, Jana; Baron, Michael D

    2015-09-23

    Peste des petits ruminants (PPR) is a viral disease of sheep and goats that is spreading through many countries in the developing world. Work on the virus is often restricted to studies of attenuated vaccine strains or to work in laboratories that have high containment facilities. We have created a helper cell dependent form of PPR virus by removing the entire RNA polymerase gene and complementing it with polymerase made constitutively in a cell line. The resultant L-deleted virus grows efficiently in the L-expressing cell line but not in other cells. Virus made with this system is indistinguishable from normal virus when used in diagnostic assays, and can be grown in normal facilities without the need for high level biocontainment. The L-deleted virus will thus make a positive contribution to the control and study of this important disease.

  14. Space Shuttle GN and C Development History and Evolution

    NASA Technical Reports Server (NTRS)

    Zimpfer, Douglas; Hattis, Phil; Ruppert, John; Gavert, Don

    2011-01-01

    Completion of the final Space Shuttle flight marks the end of a significant era in Human Spaceflight. Developed in the 1970 s, first launched in 1981, the Space Shuttle embodies many significant engineering achievements. One of these is the development and operation of the first extensive fly-by-wire human space transportation Guidance, Navigation and Control (GN&C) System. Development of the Space Shuttle GN&C represented first time inclusions of modern techniques for electronics, software, algorithms, systems and management in a complex system. Numerous technical design trades and lessons learned continue to drive current vehicle development. For example, the Space Shuttle GN&C system incorporated redundant systems, complex algorithms and flight software rigorously verified through integrated vehicle simulations and avionics integration testing techniques. Over the past thirty years, the Shuttle GN&C continued to go through a series of upgrades to improve safety, performance and to enable the complex flight operations required for assembly of the international space station. Upgrades to the GN&C ranged from the addition of nose wheel steering to modifications that extend capabilities to control of the large flexible configurations while being docked to the Space Station. This paper provides a history of the development and evolution of the Space Shuttle GN&C system. Emphasis is placed on key architecture decisions, design trades and the lessons learned for future complex space transportation system developments. Finally, some of the interesting flight operations experience is provided to inform future developers of flight experiences.

  15. Cis-regulatory control of corticospinal system development and evolution

    PubMed Central

    Shim, Sungbo; Kwan, Kenneth Y.; Li, Mingfeng; Lefebvre, Veronique; Šestan, Nenad

    2012-01-01

    Summary The co-emergence of a six-layered cerebral neocortex and its corticospinal output system is one of the evolutionary hallmarks of mammals. However, the genetic programs that underlie their development and evolution remain poorly understood. Here we identify a conserved non-exonic element (E4) that acts as a cortex-specific enhancer for the nearby Fezf2, which is required for the specification of corticospinal neuron identity and connectivity. We find that SOX4 and SOX11 functionally compete with the repressor SOX5 in the trans-activation of E4. Cortex-specific double deletion of Sox4 and Sox11 leads to the loss of Fezf2 expression and failed specification of corticospinal neurons and, independent of Fezf2, a reeler-like inversion of layers. We show evidence supporting the emergence of functional SOX binding sites in E4 during tetrapod evolution and their subsequent stabilization in mammals and possibly amniotes. These findings reveal that SOX transcription factors converge onto a cis-acting element of Fezf2 and form critical components of a regulatory network controlling the identity and connectivity of corticospinal neurons. PMID:22678282

  16. Brain evolution and development: adaptation, allometry and constraint

    PubMed Central

    Barton, Robert A.

    2016-01-01

    Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns. PMID:27629025

  17. Evolution and development of interhemispheric connections in the vertebrate forebrain

    PubMed Central

    Suárez, Rodrigo; Gobius, Ilan; Richards, Linda J.

    2014-01-01

    Axonal connections between the left and right sides of the brain are crucial for bilateral integration of lateralized sensory, motor, and associative functions. Throughout vertebrate species, forebrain commissures share a conserved developmental plan, a similar position relative to each other within the brain and similar patterns of connectivity. However, major events in the evolution of the vertebrate brain, such as the expansion of the telencephalon in tetrapods and the origin of the six-layered isocortex in mammals, resulted in the emergence and diversification of new commissural routes. These new interhemispheric connections include the pallial commissure, which appeared in the ancestors of tetrapods and connects the left and right sides of the medial pallium (hippocampus in mammals), and the corpus callosum, which is exclusive to eutherian (placental) mammals and connects both isocortical hemispheres. A comparative analysis of commissural systems in vertebrates reveals that the emergence of new commissural routes may have involved co-option of developmental mechanisms and anatomical substrates of preexistent commissural pathways. One of the embryonic regions of interest for studying these processes is the commissural plate, a portion of the early telencephalic midline that provides molecular specification and a cellular scaffold for the development of commissural axons. Further investigations into these embryonic processes in carefully selected species will provide insights not only into the mechanisms driving commissural evolution, but also regarding more general biological problems such as the role of developmental plasticity in evolutionary change. PMID:25071525

  18. Indirect development, transdifferentiation and the macroregulatory evolution of metazoans

    PubMed Central

    Arenas-Mena, Cesar

    2010-01-01

    It is proposed here that a biphasic life cycle with partial dedifferentiation of intermediate juvenile or larval stages represents the mainstream developmental mode of metazoans. Developmental plasticity of differentiated cells is considered the essential characteristic of indirect development, rather than the exclusive development of the adult from ‘set-aside’ cells. Many differentiated larval cells of indirect developers resume proliferation, partially dedifferentiate and contribute to adult tissues. Transcriptional pluripotency of differentiated states has premetazoan origins and seems to be facilitated by histone variant H2A.Z. Developmental plasticity of differentiated states also facilitates the evolution of polyphenism. Uncertainty remains about whether the most recent common ancestor of protostomes and deuterostomes was a direct or an indirect developer, and how the feeding larvae of bilaterians are related to non-feeding larvae of sponges and cnidarians. Feeding ciliated larvae of bilaterians form their primary gut opening by invagination, which seems related to invagination in cnidarians. Formation of the secondary gut opening proceeds by protostomy or deuterostomy, and gene usage suggests serial homology of the mouth and anus. Indirect developers do not use the Hox vector to build their ciliated larvae, but the Hox vector is associated with the construction of the reproductive portion of the animal during feeding-dependent posterior growth. It is further proposed that the original function of the Hox cluster was in gonad formation rather than in anteroposterior diversification. PMID:20083640

  19. Development of a Prognostic Marker for Lung Cancer Using Analysis of Tumor Evolution

    DTIC Science & Technology

    2016-08-01

    AWARD NUMBER: W81XWH-15-1-0243 TITLE: Development of a Prognostic Marker for Lung Cancer Using Analysis of Tumor Evolution PRINCIPAL...SUBTITLE 5a. CONTRACT NUMBER Development of a Prognostic Marker for Lung Cancer Using Analysis of Tumor Evolution 5b. GRANT NUMBER W81XWH-15-1...reconstruct tumor cell evolution in tumors. 15. SUBJECT TERMS NSCLC; tumor evolution ; whole exome sequencing 16. SECURITY CLASSIFICATION OF: 17

  20. Origine et developpement des industries de la langue (Origin and Development of Language Utilities). Publication K-8.

    ERIC Educational Resources Information Center

    L'Homme, Marie-Claude

    The evolution of "language utilities," a concept confined largely to the francophone world and relating to the uses of language in computer science and the use of computer science for languages, is chronicled. The language utilities are of three types: (1) tools for language development, primarily dictionary databases and related tools;…

  1. Evolution of the Human Nervous System Function, Structure, and Development.

    PubMed

    Sousa, André M M; Meyer, Kyle A; Santpere, Gabriel; Gulden, Forrest O; Sestan, Nenad

    2017-07-13

    The nervous system-in particular, the brain and its cognitive abilities-is among humans' most distinctive and impressive attributes. How the nervous system has changed in the human lineage and how it differs from that of closely related primates is not well understood. Here, we consider recent comparative analyses of extant species that are uncovering new evidence for evolutionary changes in the size and the number of neurons in the human nervous system, as well as the cellular and molecular reorganization of its neural circuits. We also discuss the developmental mechanisms and underlying genetic and molecular changes that generate these structural and functional differences. As relevant new information and tools materialize at an unprecedented pace, the field is now ripe for systematic and functionally relevant studies of the development and evolution of human nervous system specializations. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Building the backbone: the development and evolution of vertebral patterning.

    PubMed

    Fleming, Angeleen; Kishida, Marcia G; Kimmel, Charles B; Keynes, Roger J

    2015-05-15

    The segmented vertebral column comprises a repeat series of vertebrae, each consisting of two key components: the vertebral body (or centrum) and the vertebral arches. Despite being a defining feature of the vertebrates, much remains to be understood about vertebral development and evolution. Particular controversy surrounds whether vertebral component structures are homologous across vertebrates, how somite and vertebral patterning are connected, and the developmental origin of vertebral bone-mineralizing cells. Here, we assemble evidence from ichthyologists, palaeontologists and developmental biologists to consider these issues. Vertebral arch elements were present in early stem vertebrates, whereas centra arose later. We argue that centra are homologous among jawed vertebrates, and review evidence in teleosts that the notochord plays an instructive role in segmental patterning, alongside the somites, and contributes to mineralization. By clarifying the evolutionary relationship between centra and arches, and their varying modes of skeletal mineralization, we can better appreciate the detailed mechanisms that regulate and diversify vertebral patterning.

  3. The evolution and development of vertebrate lateral line electroreceptors.

    PubMed

    Baker, Clare V H; Modrell, Melinda S; Gillis, J Andrew

    2013-07-01

    Electroreception is an ancient vertebrate sense with a fascinating evolutionary history involving multiple losses as well as independent evolution at least twice within teleosts. We review the phylogenetic distribution of electroreception and the morphology and innervation of electroreceptors in different vertebrate groups. We summarise recent work from our laboratory that has confirmed the homology of ampullary electroreceptors in non-teleost jawed vertebrates by showing, in conjunction with previously published work, that these are derived embryonically from lateral line placodes. Finally, we review hypotheses to explain the distribution of electroreception within teleosts, including the hypothesis that teleost ampullary and tuberous electroreceptors evolved via the modification of mechanosensory hair cells in lateral line neuromasts. We conclude that further experimental work on teleost electroreceptor development is needed to test such hypotheses.

  4. The evolution and development of vertebrate lateral line electroreceptors

    PubMed Central

    Baker, Clare V. H.; Modrell, Melinda S.; Gillis, J. Andrew

    2016-01-01

    Summary Electroreception is an ancient vertebrate sense with a fascinating evolutionary history involving multiple losses as well as independent evolution at least twice within teleosts. We review the phylogenetic distribution of electroreception and the morphology and innervation of electroreceptors in different vertebrate groups. We summarise recent work from our laboratory that has confirmed the homology of ampullary electroreceptors in non-teleost jawed vertebrates by showing, in conjunction with previously published work, that these are derived embryonically from lateral line placodes. Finally, we review hypotheses to explain the distribution of electroreception within teleosts, including the hypothesis that teleost ampullary and tuberous electroreceptors evolved via the modification of mechanosensory hair cells in lateral line neuromasts. We conclude that further experimental work on teleost electroreceptor development is needed to test such hypotheses. PMID:23761476

  5. Cis-regulatory landscapes in development and evolution.

    PubMed

    Maeso, Ignacio; Acemel, Rafael D; Gómez-Skarmeta, José Luis

    2017-04-01

    The recent advances in our understanding of the 3D organization of the chromatin together with an almost unlimited ability to detect cis-regulatory elements genome-wide using different biochemical signatures has provided us with an unprecedented power to study gene regulation. It is now possible to profile the complete regulatory apparatus controlling the spatio-temporal expression of any given gene, the so-called gene Regulatory Landscapes (RLs). Here we review several studies over the last two years demonstrating the functional consequences of altering RL structure in development, disease and evolution. These works clearly show that a deep understanding of transcriptional regulation is no longer conceivable without considering the 3D modular organization of animal genomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Roles of dental development and adaptation in rodent evolution.

    PubMed

    Rodrigues, Helder Gomes; Renaud, Sabrina; Charles, Cyril; Le Poul, Yann; Solé, Floréal; Aguilar, Jean-Pierre; Michaux, Jacques; Tafforeau, Paul; Headon, Denis; Jernvall, Jukka; Viriot, Laurent

    2013-01-01

    In paleontology, many changes affecting morphology, such as tooth shape in mammals, are interpreted as ecological adaptations that reflect important selective events. Despite continuing studies, the identification of the genetic bases and key ecological drivers of specific mammalian dental morphologies remains elusive. Here we focus on the genetic and functional bases of stephanodonty, a pattern characterized by longitudinal crests on molars that arose in parallel during the diversification of murine rodents. We find that overexpression of Eda or Edar is sufficient to produce the longitudinal crests defining stephanodonty in transgenic laboratory mice. Whereas our dental microwear analyses show that stephanodonty likely represents an adaptation to highly fibrous diet, the initial and parallel appearance of stephanodonty may have been facilitated by developmental processes, without being necessarily under positive selection. This study demonstrates how combining development and function can help to evaluate adaptive scenarios in the evolution of new morphologies.

  7. Dynamical patterning modules in plant development and evolution.

    PubMed

    Hernández-Hernández, Valeria; Niklas, Karl J; Newman, Stuart A; Benítez, Mariana

    2012-01-01

    Broad comparative studies at the level of developmental processes are necessary to fully understand the evolution of development and phenotypes. The concept of dynamical patterning modules (DPMs) provides a framework for studying developmental processes in the context of wide comparative analyses. DPMs are defined as sets of ancient, conserved gene products and molecular networks, in conjunction with the physical morphogenetic and patterning processes they mobilize in the context of multicellularity. The theoretical framework based on DPMs originally postulated that each module generates a key morphological motif of the basic animal body plans and organ forms. Here, we use a previous definition of the plant multicellular body plan and describe the basic DPMs underlying the main features of plant development. For each DPM, we identify characteristic molecules and molecular networks, and when possible, the physical processes they mobilize. We then briefly review the phyletic distribution of these molecules across the various plant lineages. Although many of the basic plant DPMs are significantly different from those of animals, the framework established by a DPM perspective on plant development is essential for comparative analyses aiming to provide a truly mechanistic explanation for organic development across all plant and animal lineages.

  8. Medical policy development for human spaceflight at NASA: an evolution.

    PubMed

    Doarn, Charles R

    2011-11-01

    Codification of medical policy for the National Aeronautics and Space Administration (NASA) did not occur until 1977. Policy development was based on NASA's human spaceflight efforts from 1958, and the need to support the operational aspects of the upcoming Space Shuttle Program as well as other future activities. In 1958, the Space Task Group (STG), a part of the National Advisory Committee on Aeronautics (NACA), became the focal point for astronaut selection, medical support, and instrumentation development in support of Project Mercury. NACA transitioned into NASA in 1958. The STG moved to Houston, TX, in 1961 and became the Manned Spacecraft Center. During these early years, medical support for astronaut selection and healthcare was provided through arrangements with the U.S. military, specifically the United States Air Force, which had the largest group of subject matter experts in aerospace medicine. Through most of the 1960s, the military worked very closely with NASA in developing the foundations of bioastronautics and space medicine. This work was complemented by select individuals from outside the government. From 1958 to 1977, there was no standard approach to medical policy formulation within NASA. During this time, it was individualized and subjected to political pressures. This manuscript documents the evolution of medical policy in the NASA, and provides a historical account of the individuals, processes, and needs to develop policy.

  9. The temporal dynamics of vertebrate limb development, teratogenesis and evolution.

    PubMed

    Zeller, Rolf

    2010-08-01

    Recent genetic and functional analysis of vertebrate limb development begins to reveal how the functions of particular genes and regulatory hierarchies can drastically change over time. The temporal and spatial interplay of the two instructive signalling centres are part of a larger signalling system that orchestrates limb bud morphogenesis in a rather self-regulatory manner. It appears that mesenchymal cells are specified early and subsequently, the progenitors for the different skeletal elements are expanded and determined progressively during outgrowth. Mutations and teratogens that disrupt distal progression of limb development most often cause death of the early-specified progenitors rather than altering their fates. The proliferative expansion and distal progression of paired appendage development was one of the main driving forces behind the transition from fin to limb buds during paired appendage evolution. Finally, the adaptive diversification or loss of modern tetrapod limbs in particular phyla or species appear to be a consequence of evolutionary tampering with the regulatory systems that control distal progression of limb development.

  10. Slip of the tongue: Implications for evolution and language development.

    PubMed

    Forrester, Gillian S; Rodriguez, Alina

    2015-08-01

    A prevailing theory regarding the evolution of language implicates a gestural stage prior to the emergence of speech. In support of a transition of human language from a gestural to a vocal system, articulation of the hands and the tongue are underpinned by overlapping left hemisphere dominant neural regions. Behavioral studies demonstrate that human adults perform sympathetic mouth actions in imitative synchrony with manual actions. Additionally, right-handedness for precision manual actions in children has been correlated with the typical development of language, while a lack of hand bias has been associated with psychopathology. It therefore stands to reason that sympathetic mouth actions during fine precision motor action of the hands may be lateralized. We employed a fine-grained behavioral coding paradigm to provide the first investigation of tongue protrusions in typically developing 4-year old children. Tongue protrusions were investigated across a range of cognitive tasks that required varying degrees of manual action: precision motor action, gross motor action and no motor actions. The rate of tongue protrusions was influenced by the motor requirements of the task and tongue protrusions were significantly right-biased for only precision manual motor action (p<.001). From an evolutionary perspective, tongue protrusions can drive new investigations regarding how an early human communication system transitioned from hand to mouth. From a developmental perspective, the present study may serve to reveal patterns of tongue protrusions during the motor development of typically developing children. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Sipuncula: an emerging model of spiralian development and evolution.

    PubMed

    Boyle, Michael J; Rice, Mary E

    2014-01-01

    Sipuncula is an ancient clade of unsegmented marine worms that develop through a conserved pattern of unequal quartet spiral cleavage. They exhibit putative character modifications, including conspicuously large first-quartet micromeres and prototroch cells, postoral metatroch with exclusive locomotory function, paired retractor muscles and terminal organ system, and a U-shaped digestive architecture with left-right asymmetric development. Four developmental life history patterns are recognized, and they have evolved a unique metazoan larval type, the pelagosphera. When compared with other quartet spiral-cleaving models, sipunculan development is understudied, challenging and typically absent from evolutionary interpretations of spiralian larval and adult body plan diversity. If spiral cleavage is appropriately viewed as a flexible character complex, then understudied clades and characters should be investigated. We are pursuing sipunculan models for modern molecular, genetic and cellular research on evolution of spiralian development. Protocols for whole mount gene expression studies are established in four species. Molecular labeling and confocal imaging techniques are operative from embryogenesis through larval development. Next-generation sequencing of developmental transcriptomes has been completed for two species with highly contrasting life history patterns, Phascolion cryptum (direct development) and Nephasoma pellucidum (indirect planktotrophy). Looking forward, we will attempt intracellular lineage tracing and fate-mapping studies in a proposed model sipunculan, Themiste lageniformis. Importantly, with the unsegmented Sipuncula now repositioned within the segmented Annelida, sipunculan worms have become timely and appropriate models for investigating the potential for flexibility in spiralian development, including segmentation. We briefly review previous studies, and discuss new observations on the spiralian character complex within Sipuncula.

  12. Origins and Evolution of Stomatal Development1[OPEN

    PubMed Central

    2017-01-01

    The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and ICE/SCREAMs (SCRMs), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR (EPF) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis (Arabidopsis thaliana) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants. PMID:28356502

  13. Evolution and development of mammalian limb integumentary structures.

    PubMed

    Hamrick, Mark W

    2003-08-15

    The adaptive radiation of mammalian clades has involved marked changes in limb morphology that have affected not only the skeleton but also the integumentary structures. For example, didelphid marsupials show distinct differences in nail and claw morphology that are functionally related to the evolution of arboreal, terrestrial, and aquatic foraging behaviors. Vespertilionoid bats have evolved different volar pad structures such as adhesive discs, scales, and skin folds, whereas didelphid marsupials have apical pads covered either with scales, ridges, or small cones. Comparative analysis of pad and claw development reveals subtle differences in mesenchymal and ectodermal patterning underlying interspecific variation in morphology. Analysis of gene expression during pad and claw development reveals that signaling molecules such as Msx1 and Hoxc13 play important roles in the morphogenesis of these integumentary structures. These findings suggest that evolutionary change in the expression of these molecules, and in the response of mesenchymal and ectodermal cells to these signaling factors, may underlie interspecific differences in nail, claw, and volar pad morphology. Evidence from comparative morphology, development, and functional genomics therefore sheds new light on both the patterns and mechanisms of evolutionary change in mammalian limb integumentary structures. Copyright 2003 Wiley-Liss, Inc.

  14. Evolution of external genitalia: insights from reptilian development.

    PubMed

    Gredler, Marissa L; Larkins, Christine E; Leal, Francisca; Lewis, A Kelsey; Herrera, Ana M; Perriton, Claire L; Sanger, Thomas J; Cohn, Martin J

    2014-01-01

    External genitalia are found in each of the major clades of amniotes. The phallus is an intromittent organ that functions to deliver sperm into the female reproductive tract for internal fertilization. The cellular and molecular genetic mechanisms of external genital development have begun to be elucidated from studies of the mouse genital tubercle, an embryonic appendage adjacent to the cloaca that is the precursor of the penis and clitoris. Progress in this area has improved our understanding of genitourinary malformations, which are among the most common birth defects in humans, and created new opportunities for comparative studies of other taxa. External genitalia evolve rapidly, which has led to a striking diversity of anatomical forms. Within the past year, studies of external genital development in non-mammalian amniotes, including birds, lizards, snakes, alligators, and turtles, have begun to shed light on the molecular and morphogenetic mechanisms underlying the diversification of phallus morphology. Here, we review recent progress in the comparative developmental biology of external genitalia and discuss the implications of this work for understanding external genital evolution. We address the question of the deep homology (shared common ancestry) of genital structures and of developmental mechanisms, and identify new areas of investigation that can be pursued by taking a comparative approach to studying development of the external genitalia. We propose an evolutionary interpretation of hypospadias, a congenital malformation of the urethra, and discuss how investigations of non-mammalian species can provide novel perspectives on human pathologies.

  15. The early development and evolution of the human brain.

    PubMed

    Crawford, M A

    1990-01-01

    THE CHEMISTRY OF THE BRAIN: The brain and nervous system is characterised by a heavy investment in lipid chemistry which accounts for up to 60% of its structural material. In the different mammalian species so far studied, only the 20 and 22 carbon chain length polyenoic fatty acids were present and the balance of the n-3 to n-6 fatty acids was consistently 1:1. The difference observed between species, was not in the chemistry but in the extent to which the brain is developed. This paper discusses the possibility that essential fatty acids may have played a part in it evolution. THE ORIGIN OF AIR BREATHING ANIMALS: The first phase of the planet's existence indulged in high temperature reactions in which oxygen combined with everything feasible: from silicon to make rocks to hydrogen to make water. Once the planet's temperature dropped to a point at which water could condense on the surface allowing chemical reactions to take place in it. The atmosphere was at that time devoid of oxygen so life evolved in a reducing atmosphere. Oxygen was liberated by photolysis of water and as a by-product of the blue-green algae through photosynthesis. When the point was reached at which oxidative metabolism became thermodynamically possible, animal life evolved with all the principle phyla establishing themselves within a relatively short space of geological time. (Bernal 1973). DHA and nerve cell membranes DHA AND NERVE CELL MEMBRANES: From the chemistry of contemporary algae it is likely that animal life evolved in an n-3 rich environment although not exclusively so as smaller amounts of n-6 fatty acids would have been present. A key feature of the first animals was the evolution of the photoreceptor: in examples of marine, amphibian and modern mammalian species, it has been found to use docosahexaenoic acid (DHA) as the principle membrane fatty acid in the phosphoglycerides. It is likely that the first animals did so as well. Coincidentally, the synaptic membranes involved in

  16. Detection of homeobox genes in development and evolution.

    PubMed Central

    Murtha, M T; Leckman, J F; Ruddle, F H

    1991-01-01

    The homeobox genes encode a family of DNA-binding regulatory proteins whose function and genomic organization make them an important model system for the study of development and differentiation. Oligonucleotide primers corresponding to highly conserved regions of Antennapediaclass homeodomains were designed to detect and identify homeobox sequences in populations of DNA or RNA by means of the polymerase chain reaction (PCR). Here we present a survey of sequences detected by PCR using an initial set of primers (HoxA and HoxB) based on an early nucleotide consensus for vertebrate Antennapedia-class homeodomains. Several novel sequences are reported from both mouse genomic DNA and RNA from the developing mouse telencephalon. Forebrain-derived clones are similar to the chicken CHox7, Drosophila H2.0, and mouse Hlx genes. PCR also proved to be a rapid method for identifying homeobox sequences from diverse metazoan species. Cloning of three Antennapedia-related sequences from cnidarians provides evidence of ancient roles for homeobox genes early in metazoan evolution. Images PMID:1720547

  17. Evolution of paradigms of child health in developing countries.

    PubMed

    Mohs, E

    1985-01-01

    In 1982 Costa Rica had an infant mortality of 18 per 1000 live births and a life expectancy at birth of 76 years for women and 72 years for men. In the evolution of infant health in Costa Rica two paradigms were identified. One developed in the decades before 1970 and the other during the 1970s. The necessity of conceptualizing a third new paradigm compatible with health needs of the present and the immediate future is recognized. The first or "malnutrition paradigm" was orthodox in its derivation; it identified the lack of food as the underlying base for the major health problems and placed its emphasis on institutional medicine. The paradigm was influenced by foreign schools of nutrition and pediatrics and led to the development of an infrastructure for the delivery of medical services and the programs for food distribution. The "infectious disease paradigm" recognized infectious diseases as the main determinants of morbidity, mortality and malnutrition in childhood. The strategies derived from such a revolutionary paradigm aimed at the control and eradication of infectious diseases, and they resulted in a rapid improvement of child nutrition and health. However, the infectious disease paradigm does not seem to reduce infant mortality below the present level.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Des Moines.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1988-01-01

    This document, intended for elementary students, contains articles and activities designed to acquaint young people with the history of Des Moines, Iowa. The articles are short, and new or difficult words are highlighted and defined for young readers. "The Raccoon River Indian Agency" discusses the archeological exploration of the indian…

  19. Des Moines.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1988-01-01

    This document, intended for elementary students, contains articles and activities designed to acquaint young people with the history of Des Moines, Iowa. The articles are short, and new or difficult words are highlighted and defined for young readers. "The Raccoon River Indian Agency" discusses the archeological exploration of the indian…

  20. The integumentary skeleton of tetrapods: origin, evolution, and development

    PubMed Central

    Vickaryous, Matthew K; Sire, Jean-Yves

    2009-01-01

    Although often overlooked, the integument of many tetrapods is reinforced by a morphologically and structurally diverse assemblage of skeletal elements. These elements are widely understood to be derivatives of the once all-encompassing dermal skeleton of stem-gnathostomes but most details of their evolution and development remain confused and uncertain. Herein we re-evaluate the tetrapod integumentary skeleton by integrating comparative developmental and tissue structure data. Three types of tetrapod integumentary elements are recognized: (1) osteoderms, common to representatives of most major taxonomic lineages; (2) dermal scales, unique to gymnophionans; and (3) the lamina calcarea, an enigmatic tissue found only in some anurans. As presently understood, all are derivatives of the ancestral cosmoid scale and all originate from scleroblastic neural crest cells. Osteoderms are plesiomorphic for tetrapods but demonstrate considerable lineage-specific variability in size, shape, and tissue structure and composition. While metaplastic ossification often plays a role in osteoderm development, it is not the exclusive mode of skeletogenesis. All osteoderms share a common origin within the dermis (at or adjacent to the stratum superficiale) and are composed primarily (but not exclusively) of osseous tissue. These data support the notion that all osteoderms are derivatives of a neural crest-derived osteogenic cell population (with possible matrix contributions from the overlying epidermis) and share a deep homology associated with the skeletogenic competence of the dermis. Gymnophionan dermal scales are structurally similar to the elasmoid scales of most teleosts and are not comparable with osteoderms. Whereas details of development are lacking, it is hypothesized that dermal scales are derivatives of an odontogenic neural crest cell population and that skeletogenesis is comparable with the formation of elasmoid scales. Little is known about the lamina calcarea. It is

  1. Subglacial extensional fracture development and implications for Alpine Valley evolution

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Moore, Jeffrey R.; Amann, Florian; Loew, Simon

    2014-01-01

    stresses induced through exhumation and tectonic processes play a key role in the topographic evolution of alpine valleys. Using a finite difference model combining the effects of tectonics, erosion, and long-term bedrock strength, we assess the development of near-surface in situ stresses and predict bedrock behavior in response to glacial erosion in an Alpine Valley (the Matter Valley, southern Switzerland). Initial stresses are derived from the regional tectonic history, which is characterized by ongoing transtensional or extensional strain throughout exhumation of the brittle crust. We find that bedrock stresses beneath glacial ice in an initial V-shaped topography are sufficient to induce localized extensional fracturing in a zone extending laterally 600 m from the valley axis. The limit of this zone is reflected in the landscape today by a valley "shoulder," separating linear upper mountain slopes from the deep U-shaped inner valley. We propose that this extensional fracture development enhanced glacial quarrying between the valley shoulder and axis and identify a positive feedback where enhanced quarrying promoted valley incision, which in turn increased in situ stress concentrations near the valley floor, assisting erosion and further driving rapid U-shaped valley development. During interglacial periods, these stresses were relieved through brittle strain or topographic modification, and without significant erosion to reach more highly stressed bedrock, subsequent glaciation caused a reduction in differential stress and suppressed extensional fracturing. A combination of stress relief during interglacial periods, and increased ice accumulation rates in highly incised valleys, will reduce the likelihood of repeat enhanced erosion events.

  2. The integumentary skeleton of tetrapods: origin, evolution, and development.

    PubMed

    Vickaryous, Matthew K; Sire, Jean-Yves

    2009-04-01

    Although often overlooked, the integument of many tetrapods is reinforced by a morphologically and structurally diverse assemblage of skeletal elements. These elements are widely understood to be derivatives of the once all-encompassing dermal skeleton of stem-gnathostomes but most details of their evolution and development remain confused and uncertain. Herein we re-evaluate the tetrapod integumentary skeleton by integrating comparative developmental and tissue structure data. Three types of tetrapod integumentary elements are recognized: (1) osteoderms, common to representatives of most major taxonomic lineages; (2) dermal scales, unique to gymnophionans; and (3) the lamina calcarea, an enigmatic tissue found only in some anurans. As presently understood, all are derivatives of the ancestral cosmoid scale and all originate from scleroblastic neural crest cells. Osteoderms are plesiomorphic for tetrapods but demonstrate considerable lineage-specific variability in size, shape, and tissue structure and composition. While metaplastic ossification often plays a role in osteoderm development, it is not the exclusive mode of skeletogenesis. All osteoderms share a common origin within the dermis (at or adjacent to the stratum superficiale) and are composed primarily (but not exclusively) of osseous tissue. These data support the notion that all osteoderms are derivatives of a neural crest-derived osteogenic cell population (with possible matrix contributions from the overlying epidermis) and share a deep homology associated with the skeletogenic competence of the dermis. Gymnophionan dermal scales are structurally similar to the elasmoid scales of most teleosts and are not comparable with osteoderms. Whereas details of development are lacking, it is hypothesized that dermal scales are derivatives of an odontogenic neural crest cell population and that skeletogenesis is comparable with the formation of elasmoid scales. Little is known about the lamina calcarea. It is

  3. Diagnosis of peste des petits ruminants infection in small ruminants through in-house developed Indirect ELISA: Practical considerations

    PubMed Central

    Sharma, K. K.; Kshirsagar, D. P.; Kalyani, I. H.; Patel, D. R.; Vihol, P. D.; Patel, J. M.

    2015-01-01

    Aim: The work was conducted to diagnose peste des petits ruminants (PPR) outbreak through an in house developed indirect ELISA (thereafter referred as iELISA) its comparison with other available diagnostic tests and description of practical considerations in its development, utility and limitations. Materials and Methods: An outbreak resembled to PPR occurred in two different places of southern Gujarat viz. Vapi and Navsari, affecting 622 animals, including both goat (n = 476) and sheep (n = 146). Animals displayed the typical signs of PPR at Vapi; however diarrhea was the inconsistent feature in animals of Navsari. The affection caused morbidity of 100% and mortality were 73.68% (n = 392/532) and 56.67% (n = 51/90) in Vapi and Navsari outbreaks, respectively. Relevant ante mortem and post mortem samples were collected from representative animals. At the outset of the epidemic no kit was available with us, so agar gel immunodiffusion (AGID) was carried out and a commercial ELISA (cELISA) kit was ordered for making diagnosis through antibody demonstration. Meanwhile, an iELISA was developed in house using PPR vaccine as antigen and protein G conjugated HRPO antibody as detector. Histopathology and results of sandwich ELISA were also used to diagnose PPR virus (PPRV) in the outbreak. Results: The iELISA developed had detected PPRV antibodies in 22/24 samples (91.66%). Significant difference was observed in disease sensitivity pattern of two species by Chi-square test. While AGID failed to detect antibodies in any sample. Results were reconfirmed by comparing with commercially available cELISA kit. Conclusion: PPR is an economically important disease and for the rapid diagnosis of PPR the in house developed antibody capture iELISA can be a suitable cost effective alternative. PMID:27047112

  4. Variation in salamanders: an essay on genomes, development, and evolution.

    PubMed

    Brockes, Jeremy P

    2015-01-01

    Regeneration is studied in a few model species of salamanders, but the ten families of salamanders show considerable variation, and this has implications for our understanding of salamander biology. The most recent classification of the families identifies the cryptobranchoidea as the basal group which diverged in the early Jurassic. Variation in the sizes of genomes is particularly obvious, and reflects a major contribution from transposable elements which is already present in the basal group.Limb development has been a focus for evodevo studies, in part because of the variable property of pre-axial dominance which distinguishes salamanders from other tetrapods. This is thought to reflect the selective pressures that operate on a free-living aquatic larva, and might also be relevant for the evolution of limb regeneration. Recent fossil evidence suggests that both pre-axial dominance and limb regeneration were present 300 million years ago in larval temnospondyl amphibians that lived in mountain lakes. A satisfying account of regeneration in salamanders may need to address all these different aspects in the future.

  5. On the Development and Evolution of Astronomy in ancient Egypt

    NASA Astrophysics Data System (ADS)

    Maravelias, S. E.

    In the present paper the development and evolution of astronomy in = Ancient Egypt are briefly examined. Emphasis is given to the = applications of astronomy on: (i) the orientation of temples and = pyramids, and the subsequent determination of the year; (ii) the = reorientation of temples --after the lapse of several centuries-- (due = to the fact that the priesthood was empirically aware of the precession = of equinoxes, and the subsequent use of this very fact in order to = estimate the archaeological age of temples, tombs and pyramids; (iii) = the heliacal rising of Sirius, which was used by ancient = priests-astronomers in order to fix the New Year's Day and determine the = seasons of the civil year, although the discre pancy of the Sothic cycle = in their calendrical system was not seriously taken into account. = Finally the conclusion put forward is that astronomy in Ancient Egypt = never reached the grounds of pure science (as in Ancient Greece), at = least before the Ptolemaic era, but always remained under the influence = of traditionalism and mythology pertaining more to the sphere of = religion and dogma.

  6. Hip arthroscopy: evolution, current practice and future developments.

    PubMed

    Griffiths, Emmet J; Khanduja, Vikas

    2012-06-01

    Arthroscopic examination and treatment is an ever-increasing part of modern orthopaedic practice in this age of minimally invasive surgery. Arthroscopic procedures have been widespread in surgery of the knee and the shoulder for many years; however, the hip until relatively recently, has been largely neglected. Even now hip arthroscopy is not widely available; this may be due to the complexity of the procedure, the requirement of specialist equipment and a reportedly long learning curve. On the other hand, it has gone through a period of rapid growth over the last decade and is being performed in large numbers routinely in some centres around the world. Hip arthroscopy now provides excellent visualisation of not only the articular surfaces of the hip joint but also of the peritrochanteric or extra-articular space around the hip. Pathology of both the femoral head and the acetabulum along with the soft tissues of the hip, namely the ligamentum teres, the acetabular labrum, the synovial folds and synovium, is readily diagnosed. Modern techniques provide therapeutic options for a myriad of conditions and allow modulation of pathological processes early. Additionally hip arthroscopy is a relatively safe procedure with few complications and contraindications. However, the key to good outcomes is in the careful selection of patients and meticulous surgical technique. The aim of this review is to bring the reader up to date with an overview of the evolution of arthroscopy of the hip, review the current practice and explore possible future developments.

  7. Constraints imposed by cosmic evolution towards the development of life

    NASA Technical Reports Server (NTRS)

    Oro, J.

    1988-01-01

    The probability of terrestrial-type life emerging in any other place of the universe will depend on the constraints imposed by cosmic evolution on that particular place. A systematic examination of cosmic constraints, which must have provided the necessary and sufficient conditions for the origin and evolution of life on earth, shows that they are concerned with the nature of the central star, the planetary system, and the specific life-bearing planet, as well as with the chemical and biological evolution processes involved. These constraints or universal requirements for life are briefly described.

  8. Evolution and development of brain sensory organs in molgulid ascidians.

    PubMed

    Jeffery, William R

    2004-01-01

    The ascidian tadpole larva has two brain sensory organs containing melanocytes: the otolith, a gravity receptor, and the ocellus, part of a photoreceptor. One or both of these sensory organs are absent in molgulid ascidians. We show here that developmental changes leading to the loss of sensory pigment cells occur by different mechanisms in closely related molgulid species. Sensory pigment cells are formed through a bilateral determination pathway in which two or more precursor cells are specified as an equivalence group on each side of the embryo. The precursor cells subsequently converge at the midline after neurulation and undergo cell interactions that decide the fates of the otolith and ocellus. Molgula occidentalis and M. oculata, which exhibit a tadpole larva with an otolith but lacking an ocellus, have conserved the bilateral pigment cell determination pathway. Programmed cell death (PCD) is superimposed on this pathway late in development to eliminate the ocellus precursor and supernumerary pigment cells, which do not differentiate into either an otolith or ocellus. In contrast to molgulids with tadpole larvae, no pigment cell precursors are specified on either side of the M. occulta embryo, which forms a tailless (anural) larva lacking both sensory organs, suggesting that the bilateral pigment cell determination pathway has been lost. The bilateral pigment cell determination pathway and superimposed PCD can be restored in hybrids obtained by fertilizing M. occulta eggs with M. oculata sperm, indicating control by a zygotic process. We conclude that PCD plays an important role in the evolution and development of brain sensory organs in molgulid ascidians.

  9. The plant vascular system: evolution, development and functions.

    PubMed

    Lucas, William J; Groover, Andrew; Lichtenberger, Raffael; Furuta, Kaori; Yadav, Shri-Ram; Helariutta, Ykä; He, Xin-Qiang; Fukuda, Hiroo; Kang, Julie; Brady, Siobhan M; Patrick, John W; Sperry, John; Yoshida, Akiko; López-Millán, Ana-Flor; Grusak, Michael A; Kachroo, Pradeep

    2013-04-01

    The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essential functions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.

  10. S cones: Evolution, retinal distribution, development, and spectral sensitivity.

    PubMed

    Hunt, David M; Peichl, Leo

    2014-03-01

    S cones expressing the short wavelength-sensitive type 1 (SWS1) class of visual pigment generally form only a minority type of cone photoreceptor within the vertebrate duplex retina. Hence, their primary role is in color vision, not in high acuity vision. In mammals, S cones may be present as a constant fraction of the cones across the retina, may be restricted to certain regions of the retina or may form a gradient across the retina, and in some species, there is coexpression of SWS1 and the long wavelength-sensitive (LWS) class of pigment in many cones. During retinal development, SWS1 opsin expression generally precedes that of LWS opsin, and evidence from genetic studies indicates that the S cone pathway may be the default pathway for cone development. With the notable exception of the cartilaginous fishes, where S cones appear to be absent, they are present in representative species from all other vertebrate classes. S cone loss is not, however, uncommon; they are absent from most aquatic mammals and from some but not all nocturnal terrestrial species. The peak spectral sensitivity of S cones depends on the spectral characteristics of the pigment present. Evidence from the study of agnathans and teleost fishes indicates that the ancestral vertebrate SWS1 pigment was ultraviolet (UV) sensitive with a peak around 360 nm, but this has shifted into the violet region of the spectrum (>380 nm) on many separate occasions during vertebrate evolution. In all cases, the shift was generated by just one or a few replacements in tuning-relevant residues. Only in the avian lineage has tuning moved in the opposite direction, with the reinvention of UV-sensitive pigments.

  11. La modelisation mathematique dans l'enseignement de la chimie des gaz a des eleves de la cinquieme annee du secondaire

    NASA Astrophysics Data System (ADS)

    Gauthier, Diane

    Les problemes d'enseignement de la chimie des gaz parfaits sont donc importants. Si plusieurs etudes ont ete realisees dans le but d'identifier et d'interpreter ces problemes, aucune recherche, a notre connaissance, n'a ete realisee sur l'enseignement des lois sur les gaz parfaits. Notre recherche sur l'enseignement est donc pionniere. Elle a pour objectif general de construire et d'analyser une sequence d'enseignement de la chimie des gaz comportant diverses situations de modelisation mathematique des conduites des gaz. Les principaux objectifs specifiques sont les suivants: (1) identifier et caracteriser les situations qui provoquent une evolution des conceptions naives des eleves, evolution vers des connaissances plus adequate sur les gaz; (2) identifier et caractEriser les situations qui provoquent une evolution des connaissances mathematiques des eleves leur permettant d'interpreter convenablement les resultats des experiences, d'eprouver leurs conceptions, de donner un sens aux notions et aux relations impliquees dans les lois des gaz parfaits, lois de Boyle-Mariotte et Gay-Lussac. Une sequence d'enseignement comportant huit situations est d'eleves de secondaire V. La construction de ces situations est orientee par les recherches sur les conceptions naives des eleves, par les etudes sur l'evolution historique des conceptions sur les gaz et des pratiques scientifiques, ainsi que par les etudes theoriques et empiriques realisees en didactique des sciences et des mathematiques. La methodologie de l'ingenierie didactique (Artigue, 1998) qui constitue une application de la theorie des situations didactiques (Brousseau, 1986) est utilisee dans la construction et l'analyse des situations d'enseignement. Une analyse a priori de chacune des situations d'enseignement est effectuee; elle a pour but dexpliquer les choix des taches qui font partie des situations et de preciser la gestion didactique des situations. Diverses situations d'enseignement de la chimie ont ainsi

  12. Development of a Microfluidic Platform to Analyze Evolution of Programmed Bacterial Death

    DTIC Science & Technology

    2015-12-20

    SECURITY CLASSIFICATION OF: Evolution of programmed cell death in bacteria is a poorly understood phenomenon in biology. A critical limitation...Final Report: Development of a Microfluidic Platform to Analyze Evolution of Programmed Bacterial Death The views, opinions and/or findings contained...Papers published in non peer-reviewed journals: Final Report: Development of a Microfluidic Platform to Analyze Evolution of Programmed Bacterial Death

  13. The GAENE--Generalized Acceptance of EvolutioN Evaluation: Development of a New Measure of Evolution Acceptance

    ERIC Educational Resources Information Center

    Smith, Mike U.; Snyder, Scott W.; Devereaux, Randolph S.

    2016-01-01

    The present study reports the development of a brief, quantitative, web-based, psychometrically sound measure--the Generalized Acceptance of EvolutioN Evaluation (GAENE, pronounced "gene") in a format that is useful in large and small groups, in research, and in classroom settings. The measure was designed to measure only evolution…

  14. The GAENE--Generalized Acceptance of EvolutioN Evaluation: Development of a New Measure of Evolution Acceptance

    ERIC Educational Resources Information Center

    Smith, Mike U.; Snyder, Scott W.; Devereaux, Randolph S.

    2016-01-01

    The present study reports the development of a brief, quantitative, web-based, psychometrically sound measure--the Generalized Acceptance of EvolutioN Evaluation (GAENE, pronounced "gene") in a format that is useful in large and small groups, in research, and in classroom settings. The measure was designed to measure only evolution…

  15. Evolution of reproductive development in the volvocine algae.

    PubMed

    Hallmann, Armin

    2011-06-01

    The evolution of multicellularity, the separation of germline cells from sterile somatic cells, and the generation of a male-female dichotomy are certainly among the greatest innovations of eukaryotes. Remarkably, phylogenetic analysis suggests that the shift from simple to complex, differentiated multicellularity was not a unique progression in the evolution of life, but in fact a quite frequent event. The spheroidal green alga Volvox and its close relatives, the volvocine algae, span the full range of organizational complexity, from unicellular and colonial genera to multicellular genera with a full germ-soma division of labor and male-female dichotomy; thus, these algae are ideal model organisms for addressing fundamental issues related to the transition to multicellularity and for discovering universal rules that characterize this transition. Of all living species, Volvox carteri represents the simplest version of an immortal germline producing specialized somatic cells. This cellular specialization involved the emergence of mortality and the production of the first dead ancestors in the evolution of this lineage. Volvocine algae therefore exemplify the evolution of cellular cooperation from cellular autonomy. They also serve as a prime example of the evolution of complex traits by a few successive, small steps. Thus, we learn from volvocine algae that the evolutionary transition to complex, multicellular life is probably much easier to achieve than is commonly believed. © The Author(s) 2010. This article is published with open access at Springerlink.com

  16. Vers une approche globale de l'évolution des HominidésTowards an all-round approach to Hominid evolution

    NASA Astrophysics Data System (ADS)

    Chaline, Jean

    1998-03-01

    Two models of diversification of the common ancestor of gorillas, chimpanzees and men can be proposed on the basis of the distribution of chromosomal rearrangements in extant species and reconsideration of the role played by climate. The small genetic divergence between chimpanzees and humans is greatly amplified at the morphological level, thus constituting the 'human paradox'. This paradox is resolved by the economical and flexible evolutionary mechanism of mutations in regulator genes and the heterochronies they control, which are the true internal clocks of evolution. Changes in cranial morphology are quantified and used to analyse and explain the steps in the transition from great ape to human morphology. By comparison at the various stages of development, it is suggested that from great apes to modern man numerous heterochronies have occured during ontogeny (hypermorphosis, hypomorphosis and post-displacements).

  17. Development of an analytical method for analysis of flubendiamide, des-iodo flubendiamide and study of their residue persistence in tomato and soil.

    PubMed

    Mohapatra, S; Ahuja, A K; Deepa, M; Jagadish, G K; Rashmi, N; Sharma, D

    2011-01-01

    Flubendiamide is a new insecticide that has been found to give excellent control of lepidopterous pests of tomato. This study has been undertaken to develop an improved method for analysis of flubendiamide and its metabolite des-iodo flubendiamide and determine residue retention in tomato and soil. The analytical method developed involved extraction of flubendiamide and its metabolite des-iodo flubendiamide with acetonitrile, liquid-liquid partitioning into hexane-ethyl acetate mixture (6:4, v v⁻¹) and cleanup with activated neutral alumina. Finally the residues were dissolved in gradient high pressure liquid chromatography (HPLC) grade acetonitrile for analysis by HPLC. The mobile phase, acetonitrile-water at 60:40 (v v⁻¹) proportion and the wavelength of 235 nm gave maximum peak resolution. Using the above method and HPLC parameters described, nearly 100 % recovery of both insecticides were obtained. There was no matrix interference and the limit of quantification (LOQ) of the method was 0.01 mg kg⁻¹. Initial residue deposits of flubendiamide on field-treated tomato from treatments @ 48 and 96 g active ingredient hectare⁻¹ were 0.83 and 1.68 mg kg⁻¹, respectively. The residues of flubendiamide dissipated at the half-life of 3.9 and 4.4 days from treatments @ 48 and 96 g a.i. ha⁻¹, respectively and persisted for 15 days from both the treatments. Des-iodo flubendiamide was not detected in tomato fruits at any time during the study period. Residues of flubendiamide and des-iodo flubendiamide in soil from treatment @ 48 and 96 g a.i. ha⁻¹ were below detectable level (BDL, < 0.01 mg kg⁻¹) after 20 days. Flubendiamide completely dissipated from tomato within 20 days when the 480 SC formulation was applied at doses recommended for protection against lepidopterous pests.

  18. Research and Development for Technology Evolution Potential Forecasting System

    NASA Astrophysics Data System (ADS)

    Gao, Changqing; Cao, Shukun; Wang, Yuzeng; Ai, Changsheng; Ze, Xiangbo

    Technology forecasting is a powerful weapon for many enterprises to gain an animate future. Evolutionary potential radar plot is a necessary step of some valuable methods to help the technology managers with right technical strategy. A software system for Technology Evolution Potential Forecasting (TEPF) with automatic radar plot drawing is introduced in this paper. The framework of the system and the date structure describing the concrete evolution pattern are illustrated in details. And the algorithm for radar plot drawing is researched. It is proved that the TEPF system is an effective tool during the technology strategy analyzing process with a referenced case study.

  19. The dynamical evolution of H II regions - Recent theoretical developments

    NASA Astrophysics Data System (ADS)

    Yorke, Harold W.

    Recent H II line observations of stellar systems are discussed with regard to the capabilities of current models of stellar formation, structure and dynamics. Observations of emission nebulae arising from the interaction between the interstellar medium and evolving stars are summarized and time scales of stellar evolution are examined. A system of basic equations that consider MHD flows, radiation transfer, ionization, recombination, thermal energy balance, boundary conditions and initial values is defined for the density and temperature range of H II regions. Current numerical models for the evolution of H II regions are summarized. Planned observations of ultracompact H II regions, blisters and champagne flow are described.

  20. The evolution of plant development in a paleontological context.

    PubMed

    Boyce, C Kevin

    2010-02-01

    Contrary to what might be expected from the observation of extant plants alone, the fossil record indicates that most aspects of vascular plant form evolved multiple times during their Paleozoic radiation. Opportunity is increasing to unite information from fossil and living plants to understand the evolution of developmental mechanisms and each field can provide tests for hypotheses derived from the other. The paleontological context to recent advances in developmental genetics is reviewed for the evolution of a functionally independent sporophyte generation, of leaves, and of roots-all of which are integral to understanding the explosive radiation of vascular plants during the Devonian, 400 million years ago.

  1. Zur Entwicklung des qualitativen Adverbs im Deutschen (On the Development of the Qualitative Adverb in German)

    ERIC Educational Resources Information Center

    Paraschkewoff, Boris

    1974-01-01

    The contemporary German, predicate adjective and adjectival adverb are expressed by the same form. Although modern grammatical research gathers the various functions of the adjective under "indicator of kind," school practice still separates adjective and adverb. The historical development of qualitative adverbs is outlined. (Text is in German.)…

  2. Nutritional armor in evolution: docosahexaenoic acid as a determinant of neural, evolution and hominid brain development.

    PubMed

    Crawford, Michael A; Broadhurst, C Leigh; Cunnane, Stephen; Marsh, David E; Schmidt, Walter F; Brand, Annette; Ghebremeskel, Kebreab

    2014-11-01

    The aim of this article is to draw attention to the special significance of docosahexaenoic acid (DHA) in the brain, the potential relevance of its abundance to the evolution of the brain in past history, and now the relevance of paucity in the food supply to the rise in mental ill-health. Membrane lipids of photoreceptors, synapses, and neurons over the last 600 million years contained consistent and similarly high levels of DHA despite wide genomic change. The consistency is despite the DHA precursor differing only by 2 protons. This striking conservation is an example of Darwin's "Conditions of Existence," which he described as the higher force in evolution. A purpose of this article is to suggest that the present paradigm of food production currently based on protein requirements, should change to serve the specific lipid needs of the brain to address the rise in mental ill-health.(1.)

  3. Orogenic development of the Adrar des Iforas (Tuareg Shield, NE Mali): new geochemical and geochronological data and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Bosch, Delphine; Bruguier, Olivier; Caby, Renaud; Buscail, Francois; Hammor, Dalila

    2016-04-01

    Laser-ablation U-Th-Pb analyses of zircon and allanite from magmatic and metamorphic rocks of the Adrar des Iforas (Northern Mali) allow re-examining the relationships between the different crustal units constituting the western part of the Tuareg Shield, as well as the timing of magmatic and metamorphic events in the West Gondwana Orogen. Granulite-facies metamorphism in the Iforas Granulitic Unit (IGU) and at In Bezzeg occurred at 1986 ± 7 Ma and 1988 ± 5 Ma respectively. This age is slightly younger, but consistent with that of the HT granulite facies event characterizing the In Ouzzal granulitic unit (IOGU), thereby substantiating the view that these units once formed a single granulitic belt of c. 800 km long. High-grade metamorphic basement units of the Kidal terrane surrounding the IGU contain Paleoproterozoic magmatic rocks crystallized between 1982 ± 8 Ma and 1966 ± 9 Ma. Inherited components in these rocks (2.1 Ga and 2.3-2.5 Ga) have ages similar to that of detrital zircons at In Bezzeg and to that of basement rocks from the IGU. This is taken as evidence that the Kidal terrane and the IGU formed a single crustal block at least until 1.9 Ga. East of the Adrar fault, the Tin Essako orthogneiss is dated at 2020 ± 5 Ma, but escaped granulite facies metamorphism. During the Neoproterozoic, the Kidal terrane underwent a long-lived continental margin magmatism. To the west, this terrane is bounded by the Tilemsi intra-oceanic island arc, for which a gneissic sub-alkali granite was dated at 716 ± 6 Ma. A synkinematic diorite extends the magmatic activity of the arc down to 643 ± 4 Ma, and, along with litterature data, indicates that the Tilemsi arc had a life span of about 90 Ma. Backward docking to the western margin of the Kidal terrane is documented by migmatites dated at 628 ± 6 Ma. Subduction related processes and the development of the Kidal active margin was responsible for the development of a back-arc basin in the Tafeliant area, with

  4. Orogenic development of the Adrar des Iforas (Tuareg Shield, NE Mali): New geochemical and geochronological data and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Bosch, Delphine; Bruguier, Olivier; Caby, Renaud; Buscail, François; Hammor, Dalila

    2016-05-01

    Laser-ablation U-Th-Pb analyses of zircon and allanite from magmatic and metamorphic rocks of the Adrar des Iforas in Northern Mali allow re-examining the relationships between the different crustal units constituting the western part of the Tuareg Shield, as well as the timing of magmatic and metamorphic events in the West Gondwana Orogen. Granulite-facies metamorphism in the Iforas Granulitic Unit (IGU) and at In Bezzeg occurred at 1986 ± 7 Ma and 1988 ± 5 Ma respectively. This age is slightly younger, but consistent with that of the HT granulite facies event characterizing the In Ouzzal granulitic unit (IOGU), thereby substantiating the view that these units once formed a single granulitic belt of c. 800 km long. High-grade metamorphic basement units of the Kidal terrane surrounding the IGU contain Paleoproterozoic magmatic rocks crystallized between 1982 ± 8 Ma and 1966 ± 9 Ma. Inherited components in these rocks (2.1 Ga and 2.3-2.5 Ga) have ages similar to that of detrital zircons at In Bezzeg and to that of basement rocks from the IGU. This is taken as evidence that the Kidal terrane and the IGU formed a single crustal block at least until 1.9 Ga. East of the Adrar fault, the Tin Essako orthogneiss is dated at 2020 ± 5 Ma, but escaped granulite facies metamorphism. During the Neoproterozoic, the Kidal terrane underwent a long-lived continental margin magmatism. To the west, this terrane is bounded by the Tilemsi intra-oceanic island arc, for which a gneissic sub-alkali granite was dated at 716 ± 6 Ma. A synkinematic diorite extends the magmatic activity of the arc down to 643 ± 4 Ma, and, along with literature data, indicates that the Tilemsi arc has a life span of about 90 Ma. Backward docking to the western margin of the Kidal terrane is documented by migmatites dated at 628 ± 6 Ma. Subduction related processes and the development of the Kidal active margin was responsible for the development of a back-arc basin in the Tafeliant area, with

  5. The impact of stellar evolution on planetary system development

    NASA Technical Reports Server (NTRS)

    Bodenheimer, Peter

    1989-01-01

    The connection between stellar evolution and planet formation is investigated. Particular attention is given to the problem posed by the fact that the formation of Jupiter occurred before the formation of Mars and that the formation of the solid core of Saturn was completed before the dissipation of the gas in the nebula. Several possible solutions to this problem are suggested.

  6. Developing of the future: scaffolded Darwinism in societal evolution.

    PubMed

    Andersson, Claes; Törnberg, Anton; Törnberg, Petter

    2014-08-01

    We sympathize with the project of a synthetic approach for devising a "theory of intentional change" and agree that Darwinism should be central in such a theory. But Darwinism is not the only process of evolution that needs to be included. Evolutionary biology itself has taken such a turn recently, with the emergence of developmental evolutionary approaches.

  7. Evolution post-opératoire des séquelles de tuberculose pulmonaire chez les séropositifs VIH

    PubMed Central

    Grégoire, Ayegnon Kouakou; Flavien, Kendja Hypolite; Raphaël, Ouédé; Démine, Blaise; Christophe, Ménéas Gueu; Marie, Ano Kounangui; Hervé, Yangni-Angaté Koffi; Yves, Tanauh

    2014-01-01

    Cette étude rapporte les aspects cliniques et évolutifs des séquelles pulmonaires tuberculeuses (SPT) opérées chez les séropositifs (VIH+). Il s'agit d'une étude prospective transversale réalisée entre Novembre 2005 et Octobre 2012. Elle a porté sur 20 patients VIH+, ayant dans leurs antécédents, une tuberculose pulmonaire (TP) traitée et déclarée guérie, et admise dans ladite période pour une chirurgie de la SPT secondaire. Une enquête sérologique VIH a été réalisée systématiquement au cours du bilan pré-opératoire. Le diagnostic pré-opératoire de la SPT, la mortalité, les complications post- opératoires (CPOP), le séjour hospitalier, le suivi à moyen terme des STP opérées ont été évalués. Les séropositifs étaient VIH1+ (n = 12; 60%), VIH1&2+ (n = 4; 20%) et VIH2+ (n = 4; 20%). La durée moyenne d’évolution des STP était de 26,22 ± 21,3 mois. Les STP étaient les pyothorax ou pleurésies enkystées (n = 16; 80%), le poumon détruit (n = 2;10%) et les dilatations de bronches (n = 2;10%). Les VIH+ ne présentaient pas d'aspergillome pulmonaire. Le séjour hospitalier moyen était 13,1 ± 10,2 jours. Le suivi total était de 82 patients-année avec une moyenne de suivi de 4,2 ± 2,3 ans (extrêmes: 1 et 7 ans). Le taux de mortalité à court et moyen terme était nul. Aucun décès post-opératoire immédiat n'a été noté. Les CPOP immédiates étaient les bullages prolongés chez 75% des immunodéprimés. Les CPOP tardives (n = 3) étaient un syndrome restrictif pulmonaire, un pyothorax persistant et une pachypleurite résiduelle restrictive. A court terme, le taux de guérison radiologique était de 80% (n = 16). PMID:24932331

  8. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    NASA Astrophysics Data System (ADS)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques

  9. The Role of Scale in the Development and Evolution of Stratified Shear Turbulence, Entrainment and Mixing

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Role of Scale in the Development and Evolution of...collaborator on a Large Eddy Simulation (LES) study of the dynamical evolution of ocean turbulence, where the properties of Richardson instabilities are

  10. Thinking outside the Cortex: Social Motivation in the Evolution and Development of Language

    ERIC Educational Resources Information Center

    Syal, Supriya; Finlay, Barbara L.

    2011-01-01

    Alteration of the organization of social and motivational neuroanatomical circuitry must have been an essential step in the evolution of human language. Development of vocal communication across species, particularly birdsong, and new research on the neural organization and evolution of social and motivational circuitry, together suggest that…

  11. Thinking outside the Cortex: Social Motivation in the Evolution and Development of Language

    ERIC Educational Resources Information Center

    Syal, Supriya; Finlay, Barbara L.

    2011-01-01

    Alteration of the organization of social and motivational neuroanatomical circuitry must have been an essential step in the evolution of human language. Development of vocal communication across species, particularly birdsong, and new research on the neural organization and evolution of social and motivational circuitry, together suggest that…

  12. Cultural evolution and individual development of openness and conservatism.

    PubMed

    Acerbi, Alberto; Enquist, Magnus; Ghirlanda, Stefano

    2009-11-10

    We present a model of cultural evolution in which an individual's propensity to engage in social learning is affected by social learning itself. We assume that individuals observe cultural traits displayed by others and decide whether to copy them based on their overall preference for the displayed traits. Preferences, too, can be transmitted between individuals. Our results show that such cultural dynamics tends to produce conservative individuals, i.e., individuals who are reluctant to copy new traits. Openness to new information, however, can be maintained when individuals need significant time to acquire the cultural traits that make them effective cultural models. We show that a gradual enculturation of young individuals by many models and a larger cultural repertoire to be acquired are favorable circumstances for the long-term maintenance of openness in individuals and groups. Our results agree with data about lifetime personality change, showing that openness to new information decreases with age. Our results show that cultural remodeling of cultural transmission is a powerful force in cultural evolution, i.e., that cultural evolution can change its own dynamics.

  13. The Evolution and Development of Cephalopod Chambers and Their Shape.

    PubMed

    Lemanis, Robert; Korn, Dieter; Zachow, Stefan; Rybacki, Erik; Hoffmann, René

    2016-01-01

    The Ammonoidea is a group of extinct cephalopods ideal to study evolution through deep time. The evolution of the planispiral shell and complexly folded septa in ammonoids has been thought to have increased the functional surface area of the chambers permitting enhanced metabolic functions such as: chamber emptying, rate of mineralization and increased growth rates throughout ontogeny. Using nano-computed tomography and synchrotron radiation based micro-computed tomography, we present the first study of ontogenetic changes in surface area to volume ratios in the phragmocone chambers of several phylogenetically distant ammonoids and extant cephalopods. Contrary to the initial hypothesis, ammonoids do not possess a persistently high relative chamber surface area. Instead, the functional surface area of the chambers is higher in earliest ontogeny when compared to Spirula spirula. The higher the functional surface area the quicker the potential emptying rate of the chamber; quicker chamber emptying rates would theoretically permit faster growth. This is supported by the persistently higher siphuncular surface area to chamber volume ratio we collected for the ammonite Amauroceras sp. compared to either S. spirula or nautilids. We demonstrate that the curvature of the surface of the chamber increases with greater septal complexity increasing the potential refilling rates. We further show a unique relationship between ammonoid chamber shape and size that does not exist in S. spirula or nautilids. This view of chamber function also has implications for the evolution of the internal shell of coleoids, relating this event to the decoupling of soft-body growth and shell growth.

  14. Cultural evolution and individual development of openness and conservatism

    PubMed Central

    Acerbi, Alberto; Enquist, Magnus; Ghirlanda, Stefano

    2009-01-01

    We present a model of cultural evolution in which an individual's propensity to engage in social learning is affected by social learning itself. We assume that individuals observe cultural traits displayed by others and decide whether to copy them based on their overall preference for the displayed traits. Preferences, too, can be transmitted between individuals. Our results show that such cultural dynamics tends to produce conservative individuals, i.e., individuals who are reluctant to copy new traits. Openness to new information, however, can be maintained when individuals need significant time to acquire the cultural traits that make them effective cultural models. We show that a gradual enculturation of young individuals by many models and a larger cultural repertoire to be acquired are favorable circumstances for the long-term maintenance of openness in individuals and groups. Our results agree with data about lifetime personality change, showing that openness to new information decreases with age. Our results show that cultural remodeling of cultural transmission is a powerful force in cultural evolution, i.e., that cultural evolution can change its own dynamics. PMID:19858478

  15. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    NASA Astrophysics Data System (ADS)

    Amrani, Salah

    fabriquees industriellement. Cette technique a consiste a determiner le profil des differentes proprietes physiques. En effet, la methode basee sur la mesure de la distribution de la resistivite electrique sur la totalite de l'echantillon est la technique qui a ete utilisee pour localiser la fissuration et les macro-pores. La microscopie optique et l'analyse d'image ont, quant a elles, permis de caracteriser les zones fissurees tout en determinant la structure des echantillons analyses a l'echelle microscopique. D'autres tests ont ete menes, et ils ont consiste a etudier des echantillons cylindriques d'anodes de 50 mm de diametre et de 130 mm de longueur. Ces derniers ont ete cuits dans un four a UQAC a differents taux de chauffage dans le but de pouvoir determiner l'influence des parametres de cuisson sur la formation de la fissuration dans ce genre de carottes. La caracterisation des echantillons d'anodes cuites a ete faite a l'aide de la microscopie electronique a balayage et de l'ultrason. La derniere partie des travaux realises a l'UQAC contient une etude sur la caracterisation des anodes fabriquees au laboratoire sous differentes conditions d'operation. L'evolution de la qualite de ces anodes a ete faite par l'utilisation de plusieurs techniques. L'evolution de la temperature de refroidissement des anodes crues de laboratoire a ete mesuree; et un modele mathematique a ete developpe et valide avec les donnees experimentales. Cela a pour objectif d'estimer la vitesse de refroidissement ainsi que le stress thermique. Toutes les anodes fabriquees ont ete caracterisees avant la cuisson par la determination de certaines proprietes physiques (resistivite electrique, densite apparente, densite optique et pourcentage de defauts). La tomographie et la distribution de la resistivite electrique, qui sont des techniques non destructives, ont ete employees pour evaluer les defauts internes des anodes. Pendant la cuisson des anodes de laboratoire, l'evolution de la resistivite

  16. Mosaic evolution of neural development in anurans: acceleration of spinal cord development in the direct developing frog Eleutherodactylus coqui.

    PubMed

    Schlosser, Gerhard

    2003-02-01

    Previous studies have shown that spinal cord development in direct developing frogs of the genus Eleutherodactylus, which have evolutionarily lost the tadpole stage, differs from that in biphasically developing anurans (with the larval and the adult stage separated by metamorphosis). The present study of spinal cord development in Eleutherodactylus coqui provides additional information about neurogenesis, neuronal differentiation and growth analyzed by immunostaining for proliferating cell nuclear antigen (PCNA), in situ hybridization for NeuroD, and morphometric measurements in various developmental stages. Furthermore, spinal cord development in the frogs Discoglossus pictus, Xenopus laevis, and Physalaemus pustulosus, which belong to different anuran families but all exhibit biphasic development, was similarly analyzed. This comparative analysis allows inference of the ancestral anuran pattern of spinal cord development and how it has been modified during the evolution of Eleutherodactylus. All biphasically developing frogs analyzed share a similar pattern of spinal cord development, suggesting that this is ancestral for anurans: after neural tube closure, levels of proliferation and neurogenesis in the spinal cord were low throughout embryogenesis until they were upregulated drastically at early larval stages followed by development of the lateral motor columns. In contrast, no such quiescent embryonic period exists in E. coqui, where rapid growth, high levels of proliferation and neurogenesis, and early formation of lateral motor columns occur shortly after neural tube closure, while other parts of the central nervous system develop more slowly. Thus, spinal cord development has been accelerated during the evolution of Eleutherodactylus relative to the development of other parts of the central nervous system, probably related to the precocious development of limbs in this lineage.

  17. Development of the carapacial ridge: implications for the evolution of genetic networks in turtle shell development.

    PubMed

    Moustakas, Jacqueline E

    2008-01-01

    Paleontologists and neontologists have long looked to development to understand the homologies of the dermal bones that form the "armor" of turtles, crocodiles, armadillos, and other vertebrates. This study shows molecular evidence supporting a dermomyotomal identity for the mesenchyme of the turtle carapacial ridge. The mesenchyme of the carapace primordium expresses Pax3, Twist1, Dermo1, En1, Sim1, and Gremlin at early stages and before overt ossification expresses Pax1. A hypothesis is proposed that this mesenchyme forms dermal bone in the turtle carapace. A comparison of regulatory gene expression in the primordia of the turtle carapace, the vertebrate limb, and the vertebral column implies the exaptation of key genetic networks in the development of the turtle shell. This work establishes a new role for this mesodermal compartment and highlights the importance of changes in genetic regulation in the evolution of morphology.

  18. The Evolution and Development of Cephalopod Chambers and Their Shape

    PubMed Central

    Lemanis, Robert; Korn, Dieter; Zachow, Stefan; Rybacki, Erik; Hoffmann, René

    2016-01-01

    The Ammonoidea is a group of extinct cephalopods ideal to study evolution through deep time. The evolution of the planispiral shell and complexly folded septa in ammonoids has been thought to have increased the functional surface area of the chambers permitting enhanced metabolic functions such as: chamber emptying, rate of mineralization and increased growth rates throughout ontogeny. Using nano-computed tomography and synchrotron radiation based micro-computed tomography, we present the first study of ontogenetic changes in surface area to volume ratios in the phragmocone chambers of several phylogenetically distant ammonoids and extant cephalopods. Contrary to the initial hypothesis, ammonoids do not possess a persistently high relative chamber surface area. Instead, the functional surface area of the chambers is higher in earliest ontogeny when compared to Spirula spirula. The higher the functional surface area the quicker the potential emptying rate of the chamber; quicker chamber emptying rates would theoretically permit faster growth. This is supported by the persistently higher siphuncular surface area to chamber volume ratio we collected for the ammonite Amauroceras sp. compared to either S. spirula or nautilids. We demonstrate that the curvature of the surface of the chamber increases with greater septal complexity increasing the potential refilling rates. We further show a unique relationship between ammonoid chamber shape and size that does not exist in S. spirula or nautilids. This view of chamber function also has implications for the evolution of the internal shell of coleoids, relating this event to the decoupling of soft-body growth and shell growth. PMID:26963712

  19. Development of the aftershock process of the 2010 Val-des-Bois (Quebec) Mw 5.0 Earthquake

    NASA Astrophysics Data System (ADS)

    Dineva, S.; Steffen, R.; Drysdale, J.; Peci, V.; Fay, E.; McManus, M.

    2011-12-01

    The Mw 5.0 June 23, 2010 earthquake near Val-des-Bois, Quebec (Latitude 45.88N, Longitude 75.48W, depth 22 km) is one of the largest earthquakes in eastern North America since the 2002 Mw 5.0 Au Sable Forks earthquake in upper NY State. The earthquake was felt over an area of approximately 3 million km2 from Quebec, Ontario, and New York State to Maine, Illinois and Kentucky, producing probably the strongest shaking felt in Ottawa, Canada (60 km from the epicentre) in the past 200 years. The maximum intensity of the earthquake was VII MMI. The earthquake produced more than 350 aftershocks in a comparatively small area (~10 x 10 km2) the majority of which occurred within a week. The magnitudes of the recorded aftershocks ranged from 0.7 to 3.3 MN. Within 24 hours after the main shock the Geological Survey of Canada installed 6 temporary stations within 15 km of the epicentre, one of which is still in operation. The records from these stations, as well as the records from the stations of the Canadian National Seismic Network (CNSN), and the POLARIS stations in Ontario and Quebec are used to study the parameters (hypocenter locations and focal mechanisms) of the aftershocks. The hypocenter locations of over 100 events are defined using single event calculations (HYPOCENTER program) and HypoDD. The focal mechanisms are defined for 20 stronger events using P-wave polarities and seismic moment inversion of the waveforms. The depths of 24 aftershocks are defined also using regional depth-phases method. The local stress field is obtained from an inversion of the focal mechanisms using two different methods and compared with the regional stress field. The results from this study show the development of the aftershock process in space and time and the spatial variation of the focal mechanisms. It helped to define the actual fault plane of the main event, as well as to throw some light on the seismotectonics of the epicentral area which is part of the Western Quebec seismic

  20. Shear band evolution and accumulated microstructural development in Cosserat media

    NASA Astrophysics Data System (ADS)

    Tordesillas, A.; Peters, J. F.; Gardiner, B. S.

    2004-08-01

    This paper prepares the ground for the continuum analysis of shear band evolution using a Cosserat/micropolar constitutive equation derived from micromechanical considerations. The nature of the constitutive response offers two key advantages over other existing models. Firstly, its non-local character obviates the mathematical difficulties of traditional analyses, and facilitates an investigation of the shear band evolution (i.e. the regime beyond the onset of localization). Secondly, the constitutive model parameters are physical properties of particles and their interactions (e.g. particle stiffness coefficients, coefficients of inter-particle rolling friction and sliding friction), as opposed to poorly understood fitting parameters. In this regard, the model is based on the same material properties used as model inputs to a discrete element (DEM) analysis, therefore, the micromechanics approach provides the vehicle for incorporating results not only from physical experiments but also from DEM simulations. Although the capabilities of such constitutive models are still limited, much can be discerned from their general rate form. In this paper, an attempt is made to distinguish between those aspects of the continuum theory of localization that are independent of the constitutive model, and those that require significant advances in the understanding of micromechanics. Copyright

  1. The defective seed5 (des5) mutant: effects on barley seed development and HvDek1, HvCr4, and HvSal1 gene regulation.

    PubMed

    Olsen, Lene T; Divon, Hege H; Al, Ronald; Fosnes, Kjetil; Lid, Stein Erik; Opsahl-Sorteberg, Hilde-Gunn

    2008-01-01

    Barley, one of the major small grain crops, is especially important in climatically demanding agricultural areas of the world, with multiple uses within food, feed, and beverage. The barley endosperm is further of special scientific interest due to its three aleurone cell layers, with the potential of bringing forward the molecular understanding of seed development and cell specification from Arabidopsis and maize. Work done in Arabidopsis and maize indicate the presence of conserved seed developmental pathways where Crinkly4 (Cr4), Defective kernel1 (Dek1), and Supernumerary aleurone layer1 (Sal1) are key players. With the use of microscopy, a comprehensive phenotypic characterization of the barley defective seed5 (des5) mutant is presented here. The analysis further extends to molecular quantification of gene expression changes in the des5 mutant by qRT-PCR. Moreover, full-length genomic sequences of the barley orthologues were generated and these were annotated as HvDek1, HvCr4, and HvSal1. The most striking results in this study are the patchy reduction in number of aleurone cells, rudimentary anticlinal aleurone cell walls, and the specific change of HvCr4 expression compared to HvDek1 and HvSal1. The data presented support the involvement of Hvdes5 in establishing aleurone cells. Finally, how these results might affect the current model of aleurone and epidermal cell identity and development is discussed with a speculation regarding a possible role of Des5 in regulating cell division/ secondary cell wall building.

  2. High-expanding cortical regions in human development and evolution are related to higher intellectual abilities.

    PubMed

    Fjell, Anders M; Westlye, Lars T; Amlien, Inge; Tamnes, Christian K; Grydeland, Håkon; Engvig, Andreas; Espeseth, Thomas; Reinvang, Ivar; Lundervold, Astri J; Lundervold, Arvid; Walhovd, Kristine B

    2015-01-01

    Cortical surface area has tremendously expanded during human evolution, and similar patterns of cortical expansion have been observed during childhood development. An intriguing hypothesis is that the high-expanding cortical regions also show the strongest correlations with intellectual function in humans. However, we do not know how the regional distribution of correlations between intellectual function and cortical area maps onto expansion in development and evolution. Here, in a sample of 1048 participants, we show that regions in which cortical area correlates with visuospatial reasoning abilities are generally high expanding in both development and evolution. Several regions in the frontal cortex, especially the anterior cingulate, showed high expansion in both development and evolution. The area of these regions was related to intellectual functions in humans. Low-expanding areas were not related to cognitive scores. These findings suggest that cortical regions involved in higher intellectual functions have expanded the most during development and evolution. The radial unit hypothesis provides a common framework for interpretation of the findings in the context of evolution and prenatal development, while additional cellular mechanisms, such as synaptogenesis, gliogenesis, dendritic arborization, and intracortical myelination, likely impact area expansion in later childhood.

  3. Wnt signaling and the evolution of embryonic posterior development.

    PubMed

    Martin, Benjamin L; Kimelman, David

    2009-03-10

    During vertebrate embryogenesis, most of the mesodermal tissue posterior to the head forms from a progenitor population that continuously adds blocks of muscles (the somites) from the back end of the embryo. Recent work in less commonly studied arthropods--the flour beetle Tribolium and the common house spider--provides evidence suggesting that this posterior growth process might be evolutionarily conserved, with canonical Wnt signaling playing a key role in vertebrates and invertebrates. We discuss these findings as well as other evidence that suggests that the genetic network controlling posterior growth was already present in the last common ancestor of the Bilateria. We also highlight other interesting commonalities as well as differences between posterior growth in vertebrates and invertebrates, suggest future areas of research, and hypothesize that posterior growth may facilitate evolution of animal body plans.

  4. Proteomic profile evolution during steatosis development in ducks.

    PubMed

    Bax, M L; Chambon, C; Marty-Gasset, N; Remignon, H; Fernandez, X; Molette, C

    2012-01-01

    We investigated a protein profile evolution during steatosis in ducks using 2-dimensional electrophoresis gels to better understand the mechanisms underlying liver steatosis at the level of hepatic proteins in waterfowl. Two-dimensional electrophoresis gels were performed in the liver at different stages of steatosis in the duck. Mule ducks were slaughtered after 0, 14, or 23 meals of overfeeding, according to commercial conditions. Thirty-one proteic spots were differentially expressed between 3 or 2 durations of overfeeding: 3 spots were differentially expressed between the 3 times and 28 spots were differentially expressed between 2 times. The identified proteins (14) could be regrouped into 5 categories: enzymes, translation factors, proteins involved in cell structure, proteins with antioxidant properties, and proteins that can link calcium. This study opens new research areas in the understanding of steatosis in waterfowl, such as cell structure and oxidative stress.

  5. Development and Evolution of the Muscles of the Pelvic Fin

    PubMed Central

    Cole, Nicholas J.; Hall, Thomas E.; Don, Emily K.; Berger, Silke; Boisvert, Catherine A.; Neyt, Christine; Ericsson, Rolf; Joss, Jean; Gurevich, David B.; Currie, Peter D.

    2011-01-01

    Locomotor strategies in terrestrial tetrapods have evolved from the utilisation of sinusoidal contractions of axial musculature, evident in ancestral fish species, to the reliance on powerful and complex limb muscles to provide propulsive force. Within tetrapods, a hindlimb-dominant locomotor strategy predominates, and its evolution is considered critical for the evident success of the tetrapod transition onto land. Here, we determine the developmental mechanisms of pelvic fin muscle formation in living fish species at critical points within the vertebrate phylogeny and reveal a stepwise modification from a primitive to a more derived mode of pelvic fin muscle formation. A distinct process generates pelvic fin muscle in bony fishes that incorporates both primitive and derived characteristics of vertebrate appendicular muscle formation. We propose that the adoption of the fully derived mode of hindlimb muscle formation from this bimodal character state is an evolutionary innovation that was critical to the success of the tetrapod transition. PMID:21990962

  6. Development of real-time and lateral flow strip reverse transcription recombinase polymerase Amplification assays for rapid detection of peste des petits ruminants virus.

    PubMed

    Yang, Yang; Qin, Xiaodong; Song, Yiming; Zhang, Wei; Hu, Gaowei; Dou, Yongxi; Li, Yanmin; Zhang, Zhidong

    2017-02-07

    Peste des petits ruminants (PPR) is an economically important, Office International des Epizooties (OIE) notifiable, transboundary viral disease of small ruminants such as sheep and goat. PPR virus (PPRV), a negative-sense single-stranded RNA virus, is the causal agent of PPR. Therefore, sensitive, specific and rapid diagnostic assay for the detection of PPRV are necessary to accurately and promptly diagnose suspected case of PPR. In this study, reverse transcription recombinase polymerase amplification assays using real-time fluorescent detection (real-time RT-RPA assay) and lateral flow strip detection (LFS RT-RPA assay) were developed targeting the N gene of PPRV. The sensitivity of the developed real-time RT-RPA assay was as low as 100 copies per reaction within 7 min at 40 °C with 95% reliability; while the sensitivity of the developed LFS RT-RPA assay was as low as 150 copies per reaction at 39 °C in less than 25 min. In both assays, there were no cross-reactions with sheep and goat pox viruses, foot-and-mouth disease virus and Orf virus. These features make RPA assay promising candidates either in field use or as a point of care diagnostic technique.

  7. Overdeepening development in a glacial landscape evolution model with quarrying

    NASA Astrophysics Data System (ADS)

    Ugelvig, S. V.; Egholm, D. L.; Brædstrup, C. F.; Iverson, N. R.

    2013-12-01

    In glacial landscape evolution models, subglacial erosion rates are often related to basal sliding or ice discharge by a power-law. This relation can be justified when considering bed abrasion, where rock debris transported in the basal ice drives erosion. However, the relation is not well supported when considering models for quarrying of rock blocks from the bed. Field observations indicate that the principal mechanism of glacial erosion is quarrying, which emphasize the importance of a better way of implementing erosion by quarrying in glacial landscape evolution models. Iverson (2012) introduced a new model for subglacial erosion by quarrying that operates from the theory of adhesive wear. The model is based on the fact that cavities, with a high level of bedrock differential stress, form in the lee of bed obstacles when the sliding velocity is too high to allow for the ice to creep around the obstacles. The erosion rate is quantified by considering the likelihood of rock fracturing on topographic bumps. The model includes a statistical treatment of the bedrock weakness, which is neglected in previous quarrying models. Sliding rate, effective pressure, and average bedslope are the primary factors influencing the erosion rate of this new quarrying model [Iverson, 2012]. We have implemented the quarrying model in a depth-integrated higher-order ice-sheet model [Egholm et al. 2011], coupled to a model for glacial hydrology. In order to also include the effects of cavitation on the subglacial sliding rate, we use a sliding law proposed by Schoof (2005), which includes an upper limit for the stress that can be supported at the bed. Computational experiments show that the combined influence of pressure, sliding rate and bed slope leads to realistically looking landforms such as U-shaped valleys, cirques, hanging valleys and overdeepenings. The influence of the effective pressure leads naturally to overdeepenings. However, in contrast to previously used erosion models

  8. Individual Development and Evolution: Experiential Canalization of Self-Regulation

    ERIC Educational Resources Information Center

    Blair, Clancy; Raver, C. Cybele

    2012-01-01

    In this article, we contrast evolutionary and psychobiological models of individual development to address the idea that individual development occurring in prototypically risky and unsupportive environments can be understood as adaptation. We question traditional evolutionary explanations of individual development, calling on the principle of…

  9. Individual Development and Evolution: Experiential Canalization of Self-Regulation

    ERIC Educational Resources Information Center

    Blair, Clancy; Raver, C. Cybele

    2012-01-01

    In this article, we contrast evolutionary and psychobiological models of individual development to address the idea that individual development occurring in prototypically risky and unsupportive environments can be understood as adaptation. We question traditional evolutionary explanations of individual development, calling on the principle of…

  10. Metrics Evolution in an Energy Research & Development Program

    SciTech Connect

    Brent Dixon

    2011-08-01

    All technology programs progress through three phases: Discovery, Definition, and Deployment. The form and application of program metrics needs to evolve with each phase. During the discovery phase, the program determines what is achievable. A set of tools is needed to define program goals, to analyze credible technical options, and to ensure that the options are compatible and meet the program objectives. A metrics system that scores the potential performance of technical options is part of this system of tools, supporting screening of concepts and aiding in the overall definition of objectives. During the definition phase, the program defines what specifically is wanted. What is achievable is translated into specific systems and specific technical options are selected and optimized. A metrics system can help with the identification of options for optimization and the selection of the option for deployment. During the deployment phase, the program shows that the selected system works. Demonstration projects are established and classical systems engineering is employed. During this phase, the metrics communicate system performance. This paper discusses an approach to metrics evolution within the Department of Energy's Nuclear Fuel Cycle R&D Program, which is working to improve the sustainability of nuclear energy.

  11. The Evolution of Cooperative Collection Development in Alabama Academic Libraries.

    ERIC Educational Resources Information Center

    Medina, Sue O.

    1992-01-01

    Describes a cooperative collection development program implemented by the Network of Alabama Academic Libraries (NAAL) to strengthen resources available for graduate education and research. Topics discussed include funding collection development, the formula for the equitable distribution of funds, research support, and other related activities.…

  12. Individual development and evolution: experiential canalization of self-regulation.

    PubMed

    Blair, Clancy; Raver, C Cybele

    2012-05-01

    In this article, we contrast evolutionary and psychobiological models of individual development to address the idea that individual development occurring in prototypically risky and unsupportive environments can be understood as adaptation. We question traditional evolutionary explanations of individual development, calling on the principle of probabilistic epigenesis to suggest that individual development resulting from the combined activity of genes and environments is best understood to precede rather than follow from evolutionary change. Specifically, we focus on the ways in which experience shapes the development of stress response physiology, with implications for individual development and intergenerational transmission of reactive, as opposed to reflective, phenotypes. In doing so, we describe results from several analyses conducted with a longitudinal data set of 1,292 children and their primary caregivers followed from birth. Our results indicate that the effects of poverty on stress response physiology and on the development of the self-regulation of behavior represent instances of the experiential canalization of development with implications for understanding the genesis and "adaptiveness" of risk behavior.

  13. Thinking outside the cortex: social motivation in the evolution and development of language.

    PubMed

    Syal, Supriya; Finlay, Barbara L

    2011-03-01

    Alteration of the organization of social and motivational neuroanatomical circuitry must have been an essential step in the evolution of human language. Development of vocal communication across species, particularly birdsong, and new research on the neural organization and evolution of social and motivational circuitry, together suggest that human language is the result of an obligatory link of a powerful cortico-striatal learning system, and subcortical socio-motivational circuitry.

  14. Phonation takes precedence over articulation in development as well as evolution of language.

    PubMed

    Oller, D Kimbrough

    2014-12-01

    Early human vocal development is characterized first by emerging control of phonation and later by prosodic and supraglottal articulation. The target article has missed the opportunity to use these facts in the characterization of evolution in language-specific brain mechanisms. Phonation appears to be the initial human-specific brain change for language, and it was presumably a key target of selection in early hominin evolution.

  15. Using XML to encode TMA DES metadata

    PubMed Central

    Lyttleton, Oliver; Wright, Alexander; Treanor, Darren; Lewis, Paul

    2011-01-01

    Background: The Tissue Microarray Data Exchange Specification (TMA DES) is an XML specification for encoding TMA experiment data. While TMA DES data is encoded in XML, the files that describe its syntax, structure, and semantics are not. The DTD format is used to describe the syntax and structure of TMA DES, and the ISO 11179 format is used to define the semantics of TMA DES. However, XML Schema can be used in place of DTDs, and another XML encoded format, RDF, can be used in place of ISO 11179. Encoding all TMA DES data and metadata in XML would simplify the development and usage of programs which validate and parse TMA DES data. XML Schema has advantages over DTDs such as support for data types, and a more powerful means of specifying constraints on data values. An advantage of RDF encoded in XML over ISO 11179 is that XML defines rules for encoding data, whereas ISO 11179 does not. Materials and Methods: We created an XML Schema version of the TMA DES DTD. We wrote a program that converted ISO 11179 definitions to RDF encoded in XML, and used it to convert the TMA DES ISO 11179 definitions to RDF. Results: We validated a sample TMA DES XML file that was supplied with the publication that originally specified TMA DES using our XML Schema. We successfully validated the RDF produced by our ISO 11179 converter with the W3C RDF validation service. Conclusions: All TMA DES data could be encoded using XML, which simplifies its processing. XML Schema allows datatypes and valid value ranges to be specified for CDEs, which enables a wider range of error checking to be performed using XML Schemas than could be performed using DTDs. PMID:21969921

  16. Using XML to encode TMA DES metadata.

    PubMed

    Lyttleton, Oliver; Wright, Alexander; Treanor, Darren; Lewis, Paul

    2011-01-01

    The Tissue Microarray Data Exchange Specification (TMA DES) is an XML specification for encoding TMA experiment data. While TMA DES data is encoded in XML, the files that describe its syntax, structure, and semantics are not. The DTD format is used to describe the syntax and structure of TMA DES, and the ISO 11179 format is used to define the semantics of TMA DES. However, XML Schema can be used in place of DTDs, and another XML encoded format, RDF, can be used in place of ISO 11179. Encoding all TMA DES data and metadata in XML would simplify the development and usage of programs which validate and parse TMA DES data. XML Schema has advantages over DTDs such as support for data types, and a more powerful means of specifying constraints on data values. An advantage of RDF encoded in XML over ISO 11179 is that XML defines rules for encoding data, whereas ISO 11179 does not. We created an XML Schema version of the TMA DES DTD. We wrote a program that converted ISO 11179 definitions to RDF encoded in XML, and used it to convert the TMA DES ISO 11179 definitions to RDF. We validated a sample TMA DES XML file that was supplied with the publication that originally specified TMA DES using our XML Schema. We successfully validated the RDF produced by our ISO 11179 converter with the W3C RDF validation service. All TMA DES data could be encoded using XML, which simplifies its processing. XML Schema allows datatypes and valid value ranges to be specified for CDEs, which enables a wider range of error checking to be performed using XML Schemas than could be performed using DTDs.

  17. Developments in Our Understanding of Lunar Crustal Formation and Evolution

    NASA Astrophysics Data System (ADS)

    Pernet-Fisher, J. F.; Joy, K. H.

    2016-05-01

    Our recent understanding of lunar crustal formation has developed through the combination of analytical advances, and the increased availability of anorthositic material sampled as clasts within meteorite regolith breccias.

  18. Developing students' understanding of evolution in an inquiry-based versus a traditional science classroom

    NASA Astrophysics Data System (ADS)

    Humphrey, Robert James, Jr.

    Research studies over the past 30 years have found that individuals have a limited understanding of the theory of evolution and the mechanisms involved in species change. One possible avenue of improvement has been the use of alternative instructional methods, such as inquiry-based activities and teaching about nature of science. Using recommendations from research, this study integrated nature of science, evolution, and inquiry-based instruction to discern its impact on student understanding of evolution. An instructional unit was developed with a community college instructor and carried out in two introductory biology classes with a total of 38 participants. One class was taught using inquiry-based methods, with an integrated approach to nature of science and evolution, while the other was not. Data collection included student and instructor interviews, surveys, pre and post assessments, classroom observations, and student work products. The number of students holding accurate conceptions of the nature of science in the inquiry class was higher for all the reported categories on the posttest. Despite less direct exposure to evolution concepts in lecture, the inquiry class had higher means on two separate posttests for evolution. The traditional class performed better on the pretests yet the inquiry class had higher posttest scores on both measures. Students in the inquiry class held a positive view of the inquiry-based methods and they cited them as a reason for their understanding of evolution. Individuals indicated that the integration of nature of science and evolution allowed them to grasp the concepts of evolution better than if evolution was taught alone. A creationist student became more accepting of evolution and also improved her understanding of evolution. Another student interviewed four years after the intervention remembered only the inquiry-based unit and was able to still use examples from class to explain natural selection. The instructor had a

  19. Perestroika in pharma: evolution or revolution in drug development?

    PubMed

    FitzGerald, Garret A

    2010-01-01

    New-drug approvals have remained roughly constant since 1950, while the cost of drug development has soared. It seems likely that a more modular approach to drug discovery and development will evolve, deriving some features from the not-for-profit sector. For this to occur, we must address the deficit in human capital with expertise in both translational medicine and therapeutics and also in regulatory science; utilize regulatory reform to incentivize innovation and the expansion of the precompetitive space; and develop an informatics infrastructure that permits the global, secure, and compliant sharing of heterogeneous data across academic and industry sectors. These developments, likely prompted by the perception of crisis rather than opportunity, will require linked initiatives among academia, the pharmaceutical industry, the US National Institutes of Health, and the US Food and Drug Administration, along with a more adventurous role for venture capital. A failure to respond threatens the United States' lead in biomedical science and in the development and regulation of novel therapeutics.

  20. Insights into neural crest development and evolution from genomic analysis

    PubMed Central

    Simões-Costa, Marcos; Bronner, Marianne E.

    2013-01-01

    The neural crest is an excellent model system for the study of cell type diversification during embryonic development due to its multipotency, motility, and ability to form a broad array of derivatives ranging from neurons and glia, to cartilage, bone, and melanocytes. As a uniquely vertebrate cell population, it also offers important clues regarding vertebrate origins. In the past 30 yr, introduction of recombinant DNA technology has facilitated the dissection of the genetic program controlling neural crest development and has provided important insights into gene regulatory mechanisms underlying cell migration and differentiation. More recently, new genomic approaches have provided a platform and tools that are changing the depth and breadth of our understanding of neural crest development at a “systems” level. Such advances provide an insightful view of the regulatory landscape of neural crest cells and offer a new perspective on developmental as well as stem cell and cancer biology. PMID:23817048

  1. Insights into neural crest development and evolution from genomic analysis.

    PubMed

    Simões-Costa, Marcos; Bronner, Marianne E

    2013-07-01

    The neural crest is an excellent model system for the study of cell type diversification during embryonic development due to its multipotency, motility, and ability to form a broad array of derivatives ranging from neurons and glia, to cartilage, bone, and melanocytes. As a uniquely vertebrate cell population, it also offers important clues regarding vertebrate origins. In the past 30 yr, introduction of recombinant DNA technology has facilitated the dissection of the genetic program controlling neural crest development and has provided important insights into gene regulatory mechanisms underlying cell migration and differentiation. More recently, new genomic approaches have provided a platform and tools that are changing the depth and breadth of our understanding of neural crest development at a "systems" level. Such advances provide an insightful view of the regulatory landscape of neural crest cells and offer a new perspective on developmental as well as stem cell and cancer biology.

  2. Coverage with evidence development for pharmaceuticals: a policy in evolution?

    PubMed

    Lexchin, Joel

    2011-01-01

    Coverage with evidence development (CED) has been developed as a response to the uncertainty in evidence when new technologies, including pharmaceuticals, are introduced into the market. Rather than deny coverage for these technologies or grant them unlimited coverage, CED attempts to ensure that patients' access to new medications is not prevented but is managed in a coordinated way, while also generating additional evidence to reduce any uncertainty about the value of the medications. CED projects are currently operating in Australia, Canada, the United Kingdom, and the United States. However, decision-making about these projects is haphazard, and basic information about the projects is not publicly available. As a new policy development there are many unanswered policy questions, and no organized comprehensive strategy seems to be in place in any country for resolving these questions. Until these policy issues have been addressed, CED will have difficulty achieving its potential.

  3. Photovoltaic power conditioners: Development, evolution, and the next generation

    SciTech Connect

    Bulawka, A.; Krauthamer, S.; Das, R.; Bower, W.

    1994-07-01

    Market-place acceptance of utility-connected photovoltaic (PV) power generation systems and their accelerated installation into residential and commercial applications are heavily dependent upon the ability of their power conditioning subsystems (PCS) to meet high reliability, low cost, and high performance goals. Many PCS development efforts have taken place over the last 15 years, and those efforts have resulted in substantial PCS hardware improvements. These improvements, however, have generally fallen short of meeting many reliability, cost and performance goals. Continuously evolving semiconductor technology developments, coupled with expanded market opportunities for power processing, offer a significant promise of improving PCS reliability, cost and performance, as they are integrated into future PCS designs. This paper revisits past and present development efforts in PCS design, identifies the evolutionary improvements and describes the new opportunities for PCS designs. The new opportunities are arising from the increased availability and capability of semiconductor switching components, smart power devices, and power integrated circuits (PICS).

  4. Compound Leaf Development and Evolution in the Legumes[W

    PubMed Central

    Champagne, Connie E.M.; Goliber, Thomas E.; Wojciechowski, Martin F.; Mei, Raymond W.; Townsley, Brad T.; Wang, Kan; Paz, Margie M.; Geeta, R.; Sinha, Neelima R.

    2007-01-01

    Across vascular plants, Class 1 KNOTTED1-like (KNOX1) genes appear to play a critical role in the development of compound leaves. An exception to this trend is found in the Fabaceae, where pea (Pisum sativum) uses UNIFOLIATA, an ortholog of the floral regulators FLORICAULA (FLO) and LEAFY (LFY), in place of KNOX1 genes to regulate compound leaf development. To assess the phylogenetic distribution of KNOX1-independent compound leaf development, a survey of KNOX1 protein expression across the Fabaceae was undertaken. The majority of compound-leafed Fabaceae have expression of KNOX1 proteins associated with developing compound leaves. However, in a large subclade of the Fabaceae, the inverted repeat–lacking clade (IRLC), of which pea is a member, KNOX1 expression is not associated with compound leaves. These data suggest that the FLO/LFY gene may function in place of KNOX1 genes in generating compound leaves throughout the IRLC. The contribution of FLO/LFY to leaf complexity in a member of the Fabaceae outside of the IRLC was examined by reducing expression of FLO/LFY orthologs in transgenic soybean (Glycine max). Transgenic plants with reduced FLO/LFY expression showed only slight reductions in leaflet number. Overexpression of a KNOX1 gene in alfalfa (Medicago sativa), a member of the IRLC, resulted in an increase in leaflet number. This implies that KNOX1 targets, which promote compound leaf development, are present in alfalfa and are still sensitive to KNOX1 regulation. These data suggest that KNOX1 genes and the FLO/LFY gene may have played partially overlapping roles in compound leaf development in ancestral Fabaceae but that the FLO/LFY gene took over this role in the IRLC. PMID:17993625

  5. Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flava.

    PubMed

    Henry, J Q; Tagawa, K; Martindale, M Q

    2001-01-01

    Molecular and morphological comparisons indicate that the Echinodermata and Hemichordata represent closely related sister-phyla within the Deuterostomia. Much less is known about the development of the hemichordates compared to other deuterostomes. For the first time, cell lineage analyses have been carried out for an indirect-developing representative of the enteropneust hemichordates, Ptychodera flava. Single blastomeres were iontophoretically labeled with Dil at the 2- through 16-cell stages, and their fates followed through development to the tornaria larval stage. The early cleavage pattern of P. flava is similar to that of the direct-developing hemichordate, Saccoglossus kowalevskii, as well as that displayed by indirect-developing echinoids. The 16-celled embryo contains eight animal "mesomeres," four slightly larger "macromeres," and four somewhat smaller vegetal "micromeres." The first cleavage plane was not found to bear one specific relationship relative to the larval dorsoventral axis. Although individual blastomeres generate discrete clones of cells, the appearance and exact locations of these clones are variable with respect to the embryonic dorsoventral and bilateral axes. The eight animal mesomeres generate anterior (animal) ectoderm of the larva, which includes the apical organ; however, contributions to the apical organ were found to be variable as only a subset of the animal blastomeres end up contributing to its formation and this varies from embryo to embryo. The macromeres generate posterior larval ectoderm, and the vegetal micromeres form all the internal, endomesodermal tissues. These blastomere contributions are similar to those found during development of the only other hemichordate studied, the direct-developing enteropneust, S. kowalevskii. Finally, isolated blastomeres prepared at either the two- or the four-cell stage are capable of forming normal-appearing, miniature tornaria larvae. These findings indicate that the fates of these

  6. Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flava

    NASA Technical Reports Server (NTRS)

    Henry, J. Q.; Tagawa, K.; Martindale, M. Q.

    2001-01-01

    Molecular and morphological comparisons indicate that the Echinodermata and Hemichordata represent closely related sister-phyla within the Deuterostomia. Much less is known about the development of the hemichordates compared to other deuterostomes. For the first time, cell lineage analyses have been carried out for an indirect-developing representative of the enteropneust hemichordates, Ptychodera flava. Single blastomeres were iontophoretically labeled with Dil at the 2- through 16-cell stages, and their fates followed through development to the tornaria larval stage. The early cleavage pattern of P. flava is similar to that of the direct-developing hemichordate, Saccoglossus kowalevskii, as well as that displayed by indirect-developing echinoids. The 16-celled embryo contains eight animal "mesomeres," four slightly larger "macromeres," and four somewhat smaller vegetal "micromeres." The first cleavage plane was not found to bear one specific relationship relative to the larval dorsoventral axis. Although individual blastomeres generate discrete clones of cells, the appearance and exact locations of these clones are variable with respect to the embryonic dorsoventral and bilateral axes. The eight animal mesomeres generate anterior (animal) ectoderm of the larva, which includes the apical organ; however, contributions to the apical organ were found to be variable as only a subset of the animal blastomeres end up contributing to its formation and this varies from embryo to embryo. The macromeres generate posterior larval ectoderm, and the vegetal micromeres form all the internal, endomesodermal tissues. These blastomere contributions are similar to those found during development of the only other hemichordate studied, the direct-developing enteropneust, S. kowalevskii. Finally, isolated blastomeres prepared at either the two- or the four-cell stage are capable of forming normal-appearing, miniature tornaria larvae. These findings indicate that the fates of these

  7. Deuterostome evolution: early development in the enteropneust hemichordate, Ptychodera flava

    NASA Technical Reports Server (NTRS)

    Henry, J. Q.; Tagawa, K.; Martindale, M. Q.

    2001-01-01

    Molecular and morphological comparisons indicate that the Echinodermata and Hemichordata represent closely related sister-phyla within the Deuterostomia. Much less is known about the development of the hemichordates compared to other deuterostomes. For the first time, cell lineage analyses have been carried out for an indirect-developing representative of the enteropneust hemichordates, Ptychodera flava. Single blastomeres were iontophoretically labeled with Dil at the 2- through 16-cell stages, and their fates followed through development to the tornaria larval stage. The early cleavage pattern of P. flava is similar to that of the direct-developing hemichordate, Saccoglossus kowalevskii, as well as that displayed by indirect-developing echinoids. The 16-celled embryo contains eight animal "mesomeres," four slightly larger "macromeres," and four somewhat smaller vegetal "micromeres." The first cleavage plane was not found to bear one specific relationship relative to the larval dorsoventral axis. Although individual blastomeres generate discrete clones of cells, the appearance and exact locations of these clones are variable with respect to the embryonic dorsoventral and bilateral axes. The eight animal mesomeres generate anterior (animal) ectoderm of the larva, which includes the apical organ; however, contributions to the apical organ were found to be variable as only a subset of the animal blastomeres end up contributing to its formation and this varies from embryo to embryo. The macromeres generate posterior larval ectoderm, and the vegetal micromeres form all the internal, endomesodermal tissues. These blastomere contributions are similar to those found during development of the only other hemichordate studied, the direct-developing enteropneust, S. kowalevskii. Finally, isolated blastomeres prepared at either the two- or the four-cell stage are capable of forming normal-appearing, miniature tornaria larvae. These findings indicate that the fates of these

  8. Evolution Makes More Sense in the Light of Development

    ERIC Educational Resources Information Center

    Kampourakis, Kostas; Minelli, Alessandro

    2014-01-01

    We highlight some important conceptual issues that biologists should take into account when teaching evolutionary biology or communicating it to the public. We first present conclusions from conceptual development research on how particular human intuitions, namely design teleology and psychological essentialism, influence the understanding of…

  9. Conceptual Evolution and Policy Developments in Lifelong Learning

    ERIC Educational Resources Information Center

    Yang, Jin, Ed.; Valdes-Cotera, Raul, Ed.

    2011-01-01

    In recognition of the status of the World Expo 2010 in Shanghai as a platform for exchange of ideas and experience in lifelong learning, UNESCO, the Shanghai Municipal People's Government, the Chinese Society of Educational Development Strategy and the Chinese National Commission for UNESCO joined forces to co-organise the Shanghai International…

  10. Evolution Makes More Sense in the Light of Development

    ERIC Educational Resources Information Center

    Kampourakis, Kostas; Minelli, Alessandro

    2014-01-01

    We highlight some important conceptual issues that biologists should take into account when teaching evolutionary biology or communicating it to the public. We first present conclusions from conceptual development research on how particular human intuitions, namely design teleology and psychological essentialism, influence the understanding of…

  11. Evolution of Growth in the Development of Competence.

    ERIC Educational Resources Information Center

    Bierschenk, Bernhard; Bierschenk, Inger

    This article presents the third study of a series that has been designed to manifest consciousness and to measure developed competence. The emphasis of the main hypothesis of this experiment has been put on the students ability to adapt to the main idea of a given story and to express his comprehension verbally. The way the two students of the…

  12. Ontology Development and Evolution in the Accident Investigation Domain

    NASA Technical Reports Server (NTRS)

    Carvalho, Robert; Berrios, Dan; Williams, James

    2004-01-01

    InvestiigationOrganizer (IO) is a collaborative semantic web system designed to support the conduct of mishap investigations. IO provides a common repository for a wide range of mishap related information, allowing investigators to integrate evidence, causal models, and investigation results. IO has been used to support investigations ranging from a small property damage case to the loss of the Space Shuttle Columbia. Through IO'S use in these investigations, we have learned significant lessons? about the application of ontologies and semantic systems to solving real-world problems. This paper will describe the development of the ontology within IO, from the initial development, its growth in response to user requests during use in investigations, and the recent work that was done to control the results of that growth. This paper will also describe the lessons learned from this experience and how they may apply to the implementaton of future ontologies and semantic systems.

  13. Ontology Development and Evolution in the Accident Investigation Domain

    NASA Technical Reports Server (NTRS)

    Carvalho, Robert; Berrios, Dan; Williams, James

    2004-01-01

    InvestiigationOrganizer (IO) is a collaborative semantic web system designed to support the conduct of mishap investigations. IO provides a common repository for a wide range of mishap related information, allowing investigators to integrate evidence, causal models, and investigation results. IO has been used to support investigations ranging from a small property damage case to the loss of the Space Shuttle Columbia. Through IO'S use in these investigations, we have learned significant lessons? about the application of ontologies and semantic systems to solving real-world problems. This paper will describe the development of the ontology within IO, from the initial development, its growth in response to user requests during use in investigations, and the recent work that was done to control the results of that growth. This paper will also describe the lessons learned from this experience and how they may apply to the implementaton of future ontologies and semantic systems.

  14. Development of the annelid axochord: insights into notochord evolution.

    PubMed

    Lauri, Antonella; Brunet, Thibaut; Handberg-Thorsager, Mette; Fischer, Antje H L; Simakov, Oleg; Steinmetz, Patrick R H; Tomer, Raju; Keller, Philipp J; Arendt, Detlev

    2014-09-12

    The origin of chordates has been debated for more than a century, with one key issue being the emergence of the notochord. In vertebrates, the notochord develops by convergence and extension of the chordamesoderm, a population of midline cells of unique molecular identity. We identify a population of mesodermal cells in a developing invertebrate, the marine annelid Platynereis dumerilii, that converges and extends toward the midline and expresses a notochord-specific combination of genes. These cells differentiate into a longitudinal muscle, the axochord, that is positioned between central nervous system and axial blood vessel and secretes a strong collagenous extracellular matrix. Ancestral state reconstruction suggests that contractile mesodermal midline cells existed in bilaterian ancestors. We propose that these cells, via vacuolization and stiffening, gave rise to the chordate notochord. Copyright © 2014, American Association for the Advancement of Science.

  15. Sibling competition and the evolution of prenatal development rates.

    PubMed Central

    Lloyd, John D; Martin, Thomas E

    2003-01-01

    Sibling competition has been proposed as an important evolutionary pressure driving interspecific variation in developmental rates. We tested this hypothesis using rates of extra-pair paternity and brood parasitism, as well as the degree of hatching asynchrony, as indices of sibling competition in a comparative analysis of 70 species of bird. We found mixed support for the influence of sibling competition on prenatal development. Brood parasitism was negatively correlated with the length of incubation, and hatching asynchrony was positively correlated with the length of incubation, but both correlations disappeared when phylogeny was controlled for. Extra-pair paternity, however, was negatively correlated with incubation length even when phylogeny was controlled for. The latter could represent support for the influence of sibling competition on prenatal development or indirect effects of correlated selection on both traits by adult mortality. The existence of these correlations demonstrates that life-history strategies include linkages among a larger suite of traits than previously recognized. PMID:12713748

  16. Evolution and Development of Hypersonic Configurations 1958-1990

    DTIC Science & Technology

    1991-09-01

    of lifting body configurations was developed and designated the MDF series. The approach used in these designs was to consider both the constraints...L/Ds and characteristics. The MDF -1 configuration, which molded a Clark Y airfoil into the lifting body, can show a lineage with the SV-5...configuration used in both the PRIME and PILOT programs. The MDF -1 configuration is shown in Figure 5. An additional series investigated was postulated as

  17. Evolution of amylopectin structure in developing wheat endosperm starch.

    PubMed

    Kalinga, Danusha N; Bertoft, Eric; Tetlow, Ian; Liu, Qiang; Yada, Rickey Y; Seetharaman, Koushik

    2014-11-04

    In this study, starches extracted from wheat grains harvested at 7, 14, 28, and 35 days after anthesis (DAA) were used as a means of examining the molecular structure of amylopectin (AP) from developing wheat grain. Scanning electron microscopy of wheat grain cross-sections revealed the presence of endosperm at 7 DAA and contained lenticular-shaped developing large (A-type) granules. From 14 DAA onward, spherical-shaped small (B-type) granules coexisted with large granules in the endosperm. During granule development, the fine structure of AP varied with maturity in both large and small granules. Towards the end of the pre-physiological maturity stage (28 DAA), AP in small and large granules had shortest external chain length (ECL), longest internal chain length (ICL) and lowest amount of A-chains. At physiological maturity (35 DAA), these changes in ECL, ICL and amount of A-chains were reversed when compared to 28 DAA. In both large and small granules, the external AP structure was apparently more organized at physiological maturity than at pre-physiological maturity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Patterning the nervous system through development and evolution.

    PubMed

    Ghysen, Alain; Dambly-Chaudière, Christine; Raible, David W

    2010-01-01

    We report presentations and discussions at a meeting held in May 2010 in the small village of Minerve, in the south of France. The meeting was devoted mostly but not exclusively to patterning in the nervous system, with an emphasis on two model organisms, Drosophila Melanogaster and Danio rerio. Among the major issues presented were fear and its neuroanatomy, life in darkness, patterning of sensory systems, as well as fundamental issues of neural connectivity, including the role of lineage in neural development. Talks on large-scale patterning and re-patterning, and on the mouse as a third model system, concluded the meeting.

  19. SSME Electrical Harness and Cable Development and Evolution

    NASA Technical Reports Server (NTRS)

    Abrams, Russ; Heflin, Johnny; Burns, Bob; Camper, Scott J.; Hill, Arthur J.

    2010-01-01

    The Space Shuttle Main Engine (SSME) electrical harness and cable system consists of the various interconnecting devices necessary for operation of complex rocket engine functions. Thirty seven harnesses incorporate unique connectors, backshell adapters, conductors, insulation, shielding, and physical barriers for a long maintenance-free life while providing the means to satisfy performance requirements and to mitigate adverse environmental influences. The objective of this paper is to provide a description of the SSME electrical harness and cable designs as well as the development history and lessons learned.

  20. SSME Electrical Harness and Cable Development and Evolution

    NASA Technical Reports Server (NTRS)

    Abrams, Russ; Heflin, Johnny; Burns, Bob; Camper, Scott J.; Hill, Arthur J.

    2010-01-01

    The Space Shuttle Main Engine (SSME) electrical harness and cable system consists of the various interconnecting devices necessary for operation of complex rocket engine functions. Thirty seven harnesses incorporate unique connectors, backshell adapters, conductors, insulation, shielding, and physical barriers for a long maintenance-free life while providing the means to satisfy performance requirements and to mitigate adverse environmental influences. The objective of this paper is to provide a description of the SSME electrical harness and cable designs as well as the development history and lessons learned.

  1. Evolution of animal models in cancer vaccine development

    PubMed Central

    Wei, Wei-Zen; Jones, Richard F.; Juhasz, Csaba; Gibson, Heather; Veenstra, Jesse

    2015-01-01

    Advances in cancer vaccine development are facilitated by animal models reflecting key features of human cancer and its interface with host immunity. Several series of transplantable preneoplastic and neoplastic mouse mammary lesions have been used to delineate mechanisms of anti-tumor immunity. Mimicking immune tolerance to tumor-associated antigens (TAA) such as HER2/neu, transgenic mice developing spontaneous mammary tumors are strong model systems for pre-clinical vaccine testing. In these models, HER2 DNA vaccines are easily administered, well-tolerated, and induce both humoral and cellular immunity. Although engineered mouse strains have advanced cancer immunotherapy, basic shortcomings remain. For example, multiple mouse strains have to be tested to recapitulate genetic regulation of immune tolerance in humans. Outbred domestic felines more closely parallel humans in the natural development of HER2 positive breast cancer and their varying genetic background. Electrovaccination with heterologous HER2 DNA induces robust adaptive immune responses in cats. Importantly, homologous feline HER2 DNA with a single amino acid substitution elicits unique antibodies to feline mammary tumor cells, unlocking a new vaccine principle. As an alternative approach to targeted vaccination, non-surgical tumor ablation such as cryoablation induces anti-tumor immunity via in situ immunization, particularly when combined with toll-like receptor (TLR) agonist. As strategies for vaccination advance, non-invasive monitoring of host response becomes imperative. As an example, magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning following administration of tryptophan metabolism tracer [11C]-alpha-methyl-tryptophan (AMT) provides non-invasive imaging of both tumor growth and metabolic activities. Because AMT is a substrate of indoleamine-pyrrole 2,3-dioxygenase (IDO), an enzyme that produces the immune regulatory molecule kynurenine, AMT imaging can provide

  2. Evolution of animal models in cancer vaccine development.

    PubMed

    Wei, Wei-Zen; Jones, Richard F; Juhasz, Csaba; Gibson, Heather; Veenstra, Jesse

    2015-12-16

    Advances in cancer vaccine development are facilitated by animal models reflecting key features of human cancer and its interface with host immunity. Several series of transplantable preneoplastic and neoplastic mouse mammary lesions have been used to delineate mechanisms of anti-tumor immunity. Mimicking immune tolerance to tumor-associated antigens (TAA) such as HER2/neu, transgenic mice developing spontaneous mammary tumors are strong model systems for pre-clinical vaccine testing. In these models, HER2 DNA vaccines are easily administered, well-tolerated, and induce both humoral and cellular immunity. Although engineered mouse strains have advanced cancer immunotherapy, basic shortcomings remain. For example, multiple mouse strains have to be tested to recapitulate genetic regulation of immune tolerance in humans. Outbred domestic felines more closely parallel humans in the natural development of HER2 positive breast cancer and their varying genetic background. Electrovaccination with heterologous HER2 DNA induces robust adaptive immune responses in cats. Importantly, homologous feline HER2 DNA with a single amino acid substitution elicits unique antibodies to feline mammary tumor cells, unlocking a new vaccine principle. As an alternative approach to targeted vaccination, non-surgical tumor ablation such as cryoablation induces anti-tumor immunity via in situ immunization, particularly when combined with toll-like receptor (TLR) agonist. As strategies for vaccination advance, non-invasive monitoring of host response becomes imperative. As an example, magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning following administration of tryptophan metabolism tracer [11C]-alpha-methyl-tryptophan (AMT) provides non-invasive imaging of both tumor growth and metabolic activities. Because AMT is a substrate of indoleamine-pyrrole 2,3-dioxygenase (IDO), an enzyme that produces the immune regulatory molecule kynurenine, AMT imaging can provide

  3. Evolution of fruit development genes in flowering plants

    PubMed Central

    Pabón-Mora, Natalia; Wong, Gane Ka-Shu; Ambrose, Barbara A.

    2014-01-01

    The genetic mechanisms regulating dry fruit development and opercular dehiscence have been identified in Arabidopsis thaliana. In the bicarpellate silique, valve elongation and differentiation is controlled by FRUITFULL (FUL) that antagonizes SHATTERPROOF1-2 (SHP1/SHP2) and INDEHISCENT (IND) at the dehiscence zone where they control normal lignification. SHP1/2 are also repressed by REPLUMLESS (RPL), responsible for replum formation. Similarly, FUL indirectly controls two other factors ALCATRAZ (ALC) and SPATULA (SPT) that function in the proper formation of the separation layer. FUL and SHP1/2 belong to the MADS-box family, IND and ALC belong to the bHLH family and RPL belongs to the homeodomain family, all of which are large transcription factor families. These families have undergone numerous duplications and losses in plants, likely accompanied by functional changes. Functional analyses of homologous genes suggest that this network is fairly conserved in Brassicaceae and less conserved in other core eudicots. Only the MADS box genes have been functionally characterized in basal eudicots and suggest partial conservation of the functions recorded for Brassicaceae. Here we do a comprehensive search of SHP, IND, ALC, SPT, and RPL homologs across core-eudicots, basal eudicots, monocots and basal angiosperms. Based on gene-tree analyses we hypothesize what parts of the network for fruit development in Brassicaceae, in particular regarding direct and indirect targets of FUL, might be conserved across angiosperms. PMID:25018763

  4. Evolution of fruit development genes in flowering plants.

    PubMed

    Pabón-Mora, Natalia; Wong, Gane Ka-Shu; Ambrose, Barbara A

    2014-01-01

    The genetic mechanisms regulating dry fruit development and opercular dehiscence have been identified in Arabidopsis thaliana. In the bicarpellate silique, valve elongation and differentiation is controlled by FRUITFULL (FUL) that antagonizes SHATTERPROOF1-2 (SHP1/SHP2) and INDEHISCENT (IND) at the dehiscence zone where they control normal lignification. SHP1/2 are also repressed by REPLUMLESS (RPL), responsible for replum formation. Similarly, FUL indirectly controls two other factors ALCATRAZ (ALC) and SPATULA (SPT) that function in the proper formation of the separation layer. FUL and SHP1/2 belong to the MADS-box family, IND and ALC belong to the bHLH family and RPL belongs to the homeodomain family, all of which are large transcription factor families. These families have undergone numerous duplications and losses in plants, likely accompanied by functional changes. Functional analyses of homologous genes suggest that this network is fairly conserved in Brassicaceae and less conserved in other core eudicots. Only the MADS box genes have been functionally characterized in basal eudicots and suggest partial conservation of the functions recorded for Brassicaceae. Here we do a comprehensive search of SHP, IND, ALC, SPT, and RPL homologs across core-eudicots, basal eudicots, monocots and basal angiosperms. Based on gene-tree analyses we hypothesize what parts of the network for fruit development in Brassicaceae, in particular regarding direct and indirect targets of FUL, might be conserved across angiosperms.

  5. Pharmacotherapy in the cardiac catheterization laboratory: evolution and recent developments

    PubMed Central

    Thind, Guramrinder S; Parida, Raunak; Gupta, Nishant

    2014-01-01

    Many recent innovations have been made in developing new antiplatelet and anticoagulant drugs in the last few years, with a total of nine new antithrombotic drugs approved by the Food and Drug Administration after the year 2000. This has revolutionized the medical therapy given to manage acute coronary syndrome and support cardiac catheterization. The concept of dual antiplatelet therapy has been emphasized, and clopidogrel has emerged as the most-popular second antiplatelet drug after aspirin. Newer P2Y12 inhibitors like prasugrel and ticagrelor have been extensively studied and compared to clopidogrel. The role of glycoprotein (Gp) IIb/IIIa inhibitors is being redefined. Other alternatives to unfractionated heparin have become available, of which enoxaparin and bivalirudin have been studied the most. Apart from these, many more drugs with novel therapeutic targets are being studied and are currently under development. In this review, current evidence on these drugs is presented and analyzed in a way that would facilitate decision making for the clinician. For this analysis, various high-impact clinical trials, pharmacological studies, meta-analyses, and reviews were accessed through the MEDLINE database. Adopting a unique interdisciplinary approach, an attempt has been made to integrate pharmacological and clinical evidence to better understand and appreciate the pros and cons of each of these classes of drugs. PMID:25364258

  6. The comet assay: Reflections on its development, evolution and applications.

    PubMed

    Singh, Narendra P

    2016-01-01

    The study of DNA damage and its repair is critical to our understanding of human aging and cancer. This review reflects on the development of a simple technique, now known as the comet assay, to study the accumulation of DNA damage and its repair. It describes my journey into aging research and the need for a method that sensitively quantifies DNA damage on a cell-by-cell basis and on a day-by-day basis. My inspirations, obstacles and successes on the path to developing this assay and improving its reliability and sensitivity are discussed. Recent modifications, applications, and the process of standardizing the technique are also described. What was once untried and unknown has become a technique used around the world for understanding and monitoring DNA damage. The comet assay's use has grown exponentially in the new millennium, as emphasis on studying biological phenomena at the single-cell level has increased. I and others have applied the technique across cell types (including germ cells) and species (including bacteria). As it enters new realms and gains clinical relevance, the comet assay may very well illuminate human aging and its prevention.

  7. Craniofacial development of hagfishes and the evolution of vertebrates.

    PubMed

    Oisi, Yasuhiro; Ota, Kinya G; Kuraku, Shigehiro; Fujimoto, Satoko; Kuratani, Shigeru

    2013-01-10

    Cyclostomes, the living jawless vertebrates including hagfishes and lampreys, represent the most basal lineage of vertebrates. Although the monophyly of cyclostomes has been supported by recent molecular analyses, the phenotypic traits of hagfishes, especially the lack of some vertebrate-defining features and the reported endodermal origin of the adenohypophysis, have been interpreted as hagfishes exhibiting a more ancestral state than those of all other vertebrates. Furthermore, the adult anatomy of hagfishes cannot be compared easily with that of lampreys. Here we describe the craniofacial development of a series of staged hagfish embryos, which shows that their adenohypophysis arises ectodermally, consistent with the molecular phylogenetic data. This finding also allowed us to identify a pan-cyclostome pattern, one not shared by jawed vertebrates. Comparative analyses indicated that many of the hagfish-specific traits can be explained by changes secondarily introduced into the hagfish lineage. We also propose a possibility that the pan-cyclostome pattern may reflect the ancestral programme for the craniofacial development of all living vertebrates.

  8. Sensor Open System Architecture (SOSA) evolution for collaborative standards development

    NASA Astrophysics Data System (ADS)

    Collier, Charles Patrick; Lipkin, Ilya; Davidson, Steven A.; Baldwin, Rusty; Orlovsky, Michael C.; Ibrahim, Tim

    2017-04-01

    The Sensor Open System Architecture (SOSA) is a C4ISR-focused technical and economic collaborative effort between the Air Force, Navy, Army, the Department of Defense (DoD), Industry, and other Governmental agencies to develop (and incorporate) a technical Open Systems Architecture standard in order to maximize C4ISR sub-system, system, and platform affordability, re-configurability, and hardware/software/firmware re-use. The SOSA effort will effectively create an operational and technical framework for the integration of disparate payloads into C4ISR systems; with a focus on the development of a modular decomposition (defining functions and behaviors) and associated key interfaces (physical and logical) for common multi-purpose architecture for radar, EO/IR, SIGINT, EW, and Communications. SOSA addresses hardware, software, and mechanical/electrical interfaces. The modular decomposition will produce a set of re-useable components, interfaces, and sub-systems that engender reusable capabilities. This, in effect, creates a realistic and affordable ecosystem enabling mission effectiveness through systematic re-use of all available re-composed hardware, software, and electrical/mechanical base components and interfaces. To this end, SOSA will leverage existing standards as much as possible and evolve the SOSA architecture through modification, reuse, and enhancements to achieve C4ISR goals. This paper will present accomplishments over the first year of SOSA initiative.

  9. Development and evolution of the vertebrate primary mouth

    PubMed Central

    Soukup, Vladimír; Horácek, Ivan; Cerny, Robert

    2013-01-01

    The vertebrate oral region represents a key interface between outer and inner environments, and its structural and functional design is among the limiting factors for survival of its owners. Both formation of the respective oral opening (primary mouth) and establishment of the food-processing apparatus (secondary mouth) require interplay between several embryonic tissues and complex embryonic rearrangements. Although many aspects of the secondary mouth formation, including development of the jaws, teeth or taste buds, are known in considerable detail, general knowledge about primary mouth formation is regrettably low. In this paper, primary mouth formation is reviewed from a comparative point of view in order to reveal its underestimated morphogenetic diversity among, and also within, particular vertebrate clades. In general, three main developmental modes were identified. The most common is characterized by primary mouth formation via a deeply invaginated ectodermal stomodeum and subsequent rupture of the bilaminar oral membrane. However, in salamander, lungfish and also in some frog species, the mouth develops alternatively via stomodeal collar formation contributed both by the ecto- and endoderm. In ray-finned fishes, on the other hand, the mouth forms via an ectoderm wedge and later horizontal detachment of the initially compressed oral epithelia with probably a mixed germ-layer derivation. A very intriguing situation can be seen in agnathan fishes: whereas lampreys develop their primary mouth in a manner similar to the most common gnathostome pattern, hagfishes seem to undergo a unique oropharyngeal morphogenesis when compared with other vertebrates. In discussing the early formative embryonic correlates of primary mouth formation likely to be responsible for evolutionary–developmental modifications of this area, we stress an essential role of four factors: first, positioning and amount of yolk tissue; closely related to, second, endoderm formation during

  10. Evolution of vertebrate forebrain development: how many different mechanisms?

    PubMed Central

    FOLEY, ANN C.; STERN, CLAUDIO D.

    2001-01-01

    Over the past 50 years and more, many models have been proposed to explain how the nervous system is initially induced and how it becomes subdivided into gross regions such as forebrain, midbrain, hindbrain and spinal cord. Among these models is the 2-signal model of Nieuwkoop & Nigtevecht (1954), who suggested that an initial signal (‘activation’) from the organiser both neuralises and specifies the forebrain, while later signals (‘transformation’) from the same region progressively caudalise portions of this initial territory. An opposing idea emerged from the work of Otto Mangold (1933) and other members of the Spemann laboratory: 2 or more distinct organisers, emitting different signals, were proposed to be responsible for inducing the head, trunk and tail regions. Since then, evidence has accumulated that supports one or the other model, but it has been very difficult to distinguish between them. Recently, a considerable body of work from mouse embryos has been interpreted as favouring the latter model, and as suggesting that a ‘head organiser’, required for the induction of the forebrain, is spatially separate from the classic organiser (Hensen's node). An extraembryonic tissue, the ‘anterior visceral endoderm’ (AVE), was proposed to be the source of forebrain-inducing signals. It is difficult to find tissues that are directly equivalent embryologically or functionally to the AVE in other vertebrates, which led some (e.g. Kessel, 1998) to propose that mammals have evolved a new way of patterning the head. We will present evidence from the chick embryo showing that the hypoblast is embryologically and functionally equivalent to the mouse AVE. Like the latter, the hypoblast also plays a role in head development. However, it does not act like a true organiser. It induces pre-neural and pre-forebrain markers, but only transiently. Further development of neural and forebrain phenotypes requires additional signals not provided by the hypoblast. In

  11. Development and evolution of the vertebrate primary mouth.

    PubMed

    Soukup, Vladimír; Horácek, Ivan; Cerny, Robert

    2013-01-01

    The vertebrate oral region represents a key interface between outer and inner environments, and its structural and functional design is among the limiting factors for survival of its owners. Both formation of the respective oral opening (primary mouth) and establishment of the food-processing apparatus (secondary mouth) require interplay between several embryonic tissues and complex embryonic rearrangements. Although many aspects of the secondary mouth formation, including development of the jaws, teeth or taste buds, are known in considerable detail, general knowledge about primary mouth formation is regrettably low. In this paper, primary mouth formation is reviewed from a comparative point of view in order to reveal its underestimated morphogenetic diversity among, and also within, particular vertebrate clades. In general, three main developmental modes were identified. The most common is characterized by primary mouth formation via a deeply invaginated ectodermal stomodeum and subsequent rupture of the bilaminar oral membrane. However, in salamander, lungfish and also in some frog species, the mouth develops alternatively via stomodeal collar formation contributed both by the ecto- and endoderm. In ray-finned fishes, on the other hand, the mouth forms via an ectoderm wedge and later horizontal detachment of the initially compressed oral epithelia with probably a mixed germ-layer derivation. A very intriguing situation can be seen in agnathan fishes: whereas lampreys develop their primary mouth in a manner similar to the most common gnathostome pattern, hagfishes seem to undergo a unique oropharyngeal morphogenesis when compared with other vertebrates. In discussing the early formative embryonic correlates of primary mouth formation likely to be responsible for evolutionary-developmental modifications of this area, we stress an essential role of four factors: first, positioning and amount of yolk tissue; closely related to, second, endoderm formation during

  12. Evolution of Fractal Parameters through Development Stage of Soil Crust

    NASA Astrophysics Data System (ADS)

    Ospina, Abelardo; Florentino, Adriana; Tarquis, Ana Maria

    2016-04-01

    Soil surface characteristics are subjected to changes driven by several interactions between water, air, biotic and abiotic components. One of the examples of such interactions is provided through biological soil crusts (BSC) in arid and semi-arid environments. BSC are communities composed of cyanobacteria, fungi, mosses, lichens, algae and liverworts covering the soil surface and play an important role in ecosystem functioning. The characteristics and formation of these BSC influence the soil hydrological balance, control the mass of eroded sediment, increase stability of soil surface, and influence plant productivity through the modification of nitrogen and carbon cycle. The site of this work is located at Quibor and Ojo de Agua (Lara state, Venezuela). The Quibor Depression in Venezuela is a major agricultural area being at semi-arid conditions and limited drainage favor the natural process of salinization. Additionally, the extension and intensification of agriculture has led to over-exploitation of groundwater in the past 30 years (Méndoza et al., 2013). The soil microbial crust develops initially on physical crusts which are mainly generated since wetting and drying, being a recurrent feature in the Quíbor arid zone. The microbiotic crust is organic, composed of macro organisms (bryophytes and lichens) and microorganisms (cyanobacteria, fungi algae, etc.); growing on the ground, forming a thickness no greater than 3 mm. For further details see Toledo and Florentino (2009). This study focus on characterize the development stage of the BSC based on image analysis. To this end, grayscale images of different types of biological soil crust at different stages where taken, each image corresponding to an area of 12.96 cm2 with a resolution of 1024x1024 pixels (Ospina et al., 2015). For each image lacunarity and fractal dimension through the differential box counting method were calculated. These were made with the software ImageJ/Fraclac (Karperien, 2013

  13. Evolution and development of the chordates: collagen and pharyngeal cartilage.

    PubMed

    Rychel, Amanda L; Smith, Shannon E; Shimamoto, Heather T; Swalla, Billie J

    2006-03-01

    Chordates evolved a unique body plan within deuterostomes and are considered to share five morphological characters, a muscular postanal tail, a notochord, a dorsal neural tube, an endostyle, and pharyngeal gill slits. The phylum Chordata typically includes three subphyla, Cephalochordata, Vertebrata, and Tunicata, the last showing a chordate body plan only as a larva. Hemichordates, in contrast, have pharyngeal gill slits, an endostyle, and a postanal tail but appear to lack a notochord and dorsal neural tube. Because hemichordates are the sister group of echinoderms, the morphological features shared with the chordates must have been present in the deuterostome ancestor. No extant echinoderms share any of the chordate features, so presumably they have lost these structures evolutionarily. We review the development of chordate characters in hemichordates and present new data characterizing the pharyngeal gill slits and their cartilaginous gill bars. We show that hemichordate gill bars contain collagen and proteoglycans but are acellular. Hemichordates and cephalochordates, or lancelets, show strong similarities in their gill bars, suggesting that an acellular cartilage may have preceded cellular cartilage in deuterostomes. Our evidence suggests that the deuterostome ancestor was a benthic worm with gill slits and acellular gill cartilages.

  14. The evolution of Zipf's law indicative of city development

    NASA Astrophysics Data System (ADS)

    Chen, Yanguang

    2016-02-01

    Zipf's law of city-size distributions can be expressed by three types of mathematical models: one-parameter form, two-parameter form, and three-parameter form. The one-parameter and one of the two-parameter models are familiar to urban scientists. However, the three-parameter model and another type of two-parameter model have not attracted attention. This paper is devoted to exploring the conditions and scopes of application of these Zipf models. By mathematical reasoning and empirical analysis, new discoveries are made as follows. First, if the size distribution of cities in a geographical region cannot be described with the one- or two-parameter model, maybe it can be characterized by the three-parameter model with a scaling factor and a scale-translational factor. Second, all these Zipf models can be unified by hierarchical scaling laws based on cascade structure. Third, the patterns of city-size distributions seem to evolve from three-parameter mode to two-parameter mode, and then to one-parameter mode. Four-year census data of Chinese cities are employed to verify the three-parameter Zipf's law and the corresponding hierarchical structure of rank-size distributions. This study is revealing for people to understand the scientific laws of social systems and the property of urban development.

  15. The evolution and development of cranial form in Homo sapiens

    PubMed Central

    Lieberman, Daniel E.; McBratney, Brandeis M.; Krovitz, Gail

    2002-01-01

    Despite much data, there is no unanimity over how to define Homo sapiens in the fossil record. Here, we examine cranial variation among Pleistocene and recent human fossils by using a model of cranial growth to identify unique derived features (autapomorphies) that reliably distinguish fossils attributed to “anatomically modern” H. sapiens (AMHS) from those attributed to various taxa of “archaic” Homo spp. (AH) and to test hypotheses about the changes in cranial development that underlie the origin of modern human cranial form. In terms of pattern, AMHS crania are uniquely characterized by two general structural autapomorphies: facial retraction and neurocranial globularity. Morphometric analysis of the ontogeny of these autapomorphies indicates that the developmental changes that led to modern human cranial form derive from a combination of shifts in cranial base angle, cranial fossae length and width, and facial length. These morphological changes, some of which may have occurred because of relative size increases in the temporal and possibly the frontal lobes, occur early in ontogeny, and their effects on facial retraction and neurocranial globularity discriminate AMHS from AH crania. The existence of these autapomorphies supports the hypothesis that AMHS is a distinct species from taxa of “archaic” Homo (e.g., Homo neanderthalensis). PMID:11805284

  16. Evolution and development of budding by stem cells: ascidian coloniality as a case study.

    PubMed

    Brown, Federico D; Swalla, Billie J

    2012-09-15

    The evolution of budding in metazoans is not well understood on a mechanistic level, but is an important developmental process. We examine the evolution of coloniality in ascidians, contrasting the life histories of solitary and colonial forms with a focus on the cellular and developmental basis of the evolution of budding. Tunicates are an excellent group to study colonial transitions, as all solitary larvae develop with determinant and invariant cleavage patterns, but colonial species show robust developmental flexibility during larval development. We propose that acquiring new stem cell lineages in the larvae may be a preadaptation necessary for the evolution of budding. Brooding in colonial ascidians allows increased egg size, which in turn allows greater flexibility in the specification of cells and cell numbers in late embryonic and pre-metamorphic larval stages. We review hypotheses for changes in stem cell lineages in colonial species, describe what the current data suggest about the evolution of budding, and discuss where we believe further studies will be most fruitful.

  17. Education and Poverty in the Global Development Agenda: Emergence, Evolution and Consolidation

    ERIC Educational Resources Information Center

    Tarabini, Aina

    2010-01-01

    The objective of this paper is to analyse the role of education and poverty in the current global development agenda. It intends to analyse the emergence, evolution and consolidation of a global agenda, which attributes a key role to education in the fight against poverty. With this objective, the paper addresses four main issues: first, it…

  18. Evolution and Development of the Tetrapod Auditory System: an Organ of Corti-Centric Perspective

    PubMed Central

    Fritzsch, Bernd; Pan, Ning; Jahan, Israt; Duncan, Jeremy S.; Kopecky, Benjamin J.; Elliott, Karen L.; Kersigo, Jennifer; Yang, Tian

    2013-01-01

    The tetrapod auditory system transmits sound through the outer and middle ear to the organ of Corti or other sound pressure receivers of the inner ear where specialized hair cells translate vibrations of the basilar membrane into electrical potential changes that are conducted by the spiral ganglion neurons to the auditory nuclei. In other systems, notably the vertebrate limb, a detailed connection between the evolutionary variations in adaptive morphology and the underlying alterations in the genetic basis of development has been partially elucidated. In this review, we attempt to correlate evolutionary and partially characterized molecular data into a cohesive perspective of the evolution of the mammalian organ of Corti out of the tetrapod basilar papilla. We propose a stepwise, molecularly partially characterized transformation of the ancestral, vestibular developmental program of the vertebrate ear. This review provides a framework to decipher both discrete steps in development and the evolution of unique functional adaptations of the auditory system. The combined analysis of evolution and development establishes a powerful cross-correlation where conclusions derived from either approach become more meaningful in a larger context not possible through exclusively evolution or development centered perspectives. PMID:23331918

  19. Evolution and development of the tetrapod auditory system: an organ of Corti-centric perspective.

    PubMed

    Fritzsch, Bernd; Pan, Ning; Jahan, Israt; Duncan, Jeremy S; Kopecky, Benjamin J; Elliott, Karen L; Kersigo, Jennifer; Yang, Tian

    2013-01-01

    The tetrapod auditory system transmits sound through the outer and middle ear to the organ of Corti or other sound pressure receivers of the inner ear where specialized hair cells translate vibrations of the basilar membrane into electrical potential changes that are conducted by the spiral ganglion neurons to the auditory nuclei. In other systems, notably the vertebrate limb, a detailed connection between the evolutionary variations in adaptive morphology and the underlying alterations in the genetic basis of development has been partially elucidated. In this review, we attempt to correlate evolutionary and partially characterized molecular data into a cohesive perspective of the evolution of the mammalian organ of Corti out of the tetrapod basilar papilla. We propose a stepwise, molecularly partially characterized transformation of the ancestral, vestibular developmental program of the vertebrate ear. This review provides a framework to decipher both discrete steps in development and the evolution of unique functional adaptations of the auditory system. The combined analysis of evolution and development establishes a powerful cross-correlation where conclusions derived from either approach become more meaningful in a larger context which is not possible through exclusively evolution or development centered perspectives. Selection may explain the survival of the fittest auditory system, but only developmental genetics can explain the arrival of the fittest auditory system. [Modified after (Wagner 2011)]. © 2013 Wiley Periodicals, Inc.

  20. Education and Poverty in the Global Development Agenda: Emergence, Evolution and Consolidation

    ERIC Educational Resources Information Center

    Tarabini, Aina

    2010-01-01

    The objective of this paper is to analyse the role of education and poverty in the current global development agenda. It intends to analyse the emergence, evolution and consolidation of a global agenda, which attributes a key role to education in the fight against poverty. With this objective, the paper addresses four main issues: first, it…

  1. [Capsulotomy/capsulectomy in phacosurgery: evolution of development and up-to-date technology (communication 1)].

    PubMed

    Toropygin, S G; Moshetova, L K

    2010-01-01

    The review gives information on the anatomy and functions of the lenticular capsule, the evolution of development, and current techniques of capsulotomy (capsulectomy) in the surgery of cataract. It discusses the advantages and disadvantages of anterior continuous curvilinear capsulorhexis, Kloeti radiofrequency bipolar capsulotomy, vitrectorhexis, Fugo plasma blade, and other anterior lenticular capsule opening techniques.

  2. Professional Development and the Master Technology Teacher: The Evolution of One Partnership

    ERIC Educational Resources Information Center

    Wright, Vivian H.

    2010-01-01

    This article describes the formation and evolution of a successful collaboration titled the "Master Technology Teacher", a professional development program that focuses on training teachers how to use technology in classroom instruction. Partners in the collaboration include inservice and preservice teachers and university content area…

  3. Reptilian heart development and the molecular basis of cardiac chamber evolution.

    PubMed

    Koshiba-Takeuchi, Kazuko; Mori, Alessandro D; Kaynak, Bogac L; Cebra-Thomas, Judith; Sukonnik, Tatyana; Georges, Romain O; Latham, Stephany; Beck, Laurel; Beck, Laural; Henkelman, R Mark; Black, Brian L; Olson, Eric N; Wade, Juli; Takeuchi, Jun K; Nemer, Mona; Gilbert, Scott F; Bruneau, Benoit G

    2009-09-03

    The emergence of terrestrial life witnessed the need for more sophisticated circulatory systems. This has evolved in birds, mammals and crocodilians into complete septation of the heart into left and right sides, allowing separate pulmonary and systemic circulatory systems, a key requirement for the evolution of endothermy. However, the evolution of the amniote heart is poorly understood. Reptilian hearts have been the subject of debate in the context of the evolution of cardiac septation: do they possess a single ventricular chamber or two incompletely septated ventricles? Here we examine heart development in the red-eared slider turtle, Trachemys scripta elegans (a chelonian), and the green anole, Anolis carolinensis (a squamate), focusing on gene expression in the developing ventricles. Both reptiles initially form a ventricular chamber that homogenously expresses the T-box transcription factor gene Tbx5. In contrast, in birds and mammals, Tbx5 is restricted to left ventricle precursors. In later stages, Tbx5 expression in the turtle (but not anole) heart is gradually restricted to a distinct left ventricle, forming a left-right gradient. This suggests that Tbx5 expression was refined during evolution to pattern the ventricles. In support of this hypothesis, we show that loss of Tbx5 in the mouse ventricle results in a single chamber lacking distinct identity, indicating a requirement for Tbx5 in septation. Importantly, misexpression of Tbx5 throughout the developing myocardium to mimic the reptilian expression pattern also results in a single mispatterned ventricular chamber lacking septation. Thus ventricular septation is established by a steep and correctly positioned Tbx5 gradient. Our findings provide a molecular mechanism for the evolution of the amniote ventricle, and support the concept that altered expression of developmental regulators is a key mechanism of vertebrate evolution.

  4. Reptilian heart development and the molecular basis of cardiac chamber evolution

    PubMed Central

    Koshiba-Takeuchi, Kazuko; Mori, Alessandro D.; Kaynak, Bogac L.; Cebra-Thomas, Judith; Sukonnik, Tatyana; Georges, Romain O.; Latham, Stephany; Beck, Laural; Henkelman, R. Mark; Black, Brian L.; Olson, Eric N.; Wade, Juli; Takeuchi, Jun K.; Nemer, Mona; Gilbert, Scott F.; Bruneau, Benoit G.

    2009-01-01

    The emergence of terrestrial life witnessed the need for more sophisticated circulatory systems. This has evolved in birds, mammals, and crocodilians into complete septation of the heart into left and right sides, allowing separate pulmonary and systemic circulatory systems, a key requirement for the evolution of endothermy1–3. However, the evolution of the amniote heart is poorly understood. Reptilian hearts have been the subject of debate in the context of the evolution of cardiac septation: do they possess a single ventricular chamber or two incompletely septated ventricles4–7? We examined heart development in the red-eared slider turtle, Trachemys scripta elegans (a chelonian), and the green anole, Anolis carolinensis (a squamate), focusing on gene expression in the developing ventricles. Both reptiles initially form a ventricular chamber that homogenously expresses the T-box transcription factor gene Tbx5. In contrast, in birds and mammals, Tbx5 is restricted to left ventricle precursors8,9. In later stages, Tbx5 expression in the turtle (but not anole) heart is gradually restricted to a distinct left ventricle, forming a left-right gradient. This suggests that Tbx5 expression was refined during evolution to pattern the ventricles. In support of this hypothesis, we show that loss of Tbx5 in the mouse ventricle results in a single chamber lacking distinct identity, indicating a requirement for Tbx5 in septation. Importantly, misexpression of Tbx5 throughout the developing myocardium to mimic the reptilian expression pattern also results in a single mispatterned ventricular chamber lacking septation. Thus, ventricular septation is established by a steep and correctly positioned Tbx5 gradient. Our findings provide a molecular mechanism for the evolution of the amniote ventricle, and support the concept that altered expression of developmental regulators is a key mechanism of vertebrate evolution. PMID:19727199

  5. Phylogeny and adaptive evolution of the brain-development gene microcephalin (MCPH1) in cetaceans.

    PubMed

    McGowen, Michael R; Montgomery, Stephen H; Clark, Clay; Gatesy, John

    2011-04-14

    Representatives of Cetacea have the greatest absolute brain size among animals, and the largest relative brain size aside from humans. Despite this, genes implicated in the evolution of large brain size in primates have yet to be surveyed in cetaceans. We sequenced ~1240 basepairs of the brain development gene microcephalin (MCPH1) in 38 cetacean species. Alignments of these data and a published complete sequence from Tursiops truncatus with primate MCPH1 were utilized in phylogenetic analyses and to estimate ω (rate of nonsynonymous substitution/rate of synonymous substitution) using site and branch models of molecular evolution. We also tested the hypothesis that selection on MCPH1 was correlated with brain size in cetaceans using a continuous regression analysis that accounted for phylogenetic history. Our analyses revealed widespread signals of adaptive evolution in the MCPH1 of Cetacea and in other subclades of Mammalia, however, there was not a significant positive association between ω and brain size within Cetacea. In conjunction with a recent study of Primates, we find no evidence to support an association between MCPH1 evolution and the evolution of brain size in highly encephalized mammalian species. Our finding of significant positive selection in MCPH1 may be linked to other functions of the gene.

  6. Phylogeny and adaptive evolution of the brain-development gene microcephalin (MCPH1) in cetaceans

    PubMed Central

    2011-01-01

    Background Representatives of Cetacea have the greatest absolute brain size among animals, and the largest relative brain size aside from humans. Despite this, genes implicated in the evolution of large brain size in primates have yet to be surveyed in cetaceans. Results We sequenced ~1240 basepairs of the brain development gene microcephalin (MCPH1) in 38 cetacean species. Alignments of these data and a published complete sequence from Tursiops truncatus with primate MCPH1 were utilized in phylogenetic analyses and to estimate ω (rate of nonsynonymous substitution/rate of synonymous substitution) using site and branch models of molecular evolution. We also tested the hypothesis that selection on MCPH1 was correlated with brain size in cetaceans using a continuous regression analysis that accounted for phylogenetic history. Our analyses revealed widespread signals of adaptive evolution in the MCPH1 of Cetacea and in other subclades of Mammalia, however, there was not a significant positive association between ω and brain size within Cetacea. Conclusion In conjunction with a recent study of Primates, we find no evidence to support an association between MCPH1 evolution and the evolution of brain size in highly encephalized mammalian species. Our finding of significant positive selection in MCPH1 may be linked to other functions of the gene. PMID:21492470

  7. A theoretical examination of the relative importance of evolution management and drug development for managing resistance.

    PubMed

    McClure, Nathan S; Day, Troy

    2014-12-22

    Drug resistance is a serious public health problem that threatens to thwart our ability to treat many infectious diseases. Repeatedly, the introduction of new drugs has been followed by the evolution of resistance. In principle, there are two complementary ways to address this problem: (i) enhancing drug development and (ii) slowing the evolution of drug resistance through evolutionary management. Although these two strategies are not mutually exclusive, it is nevertheless worthwhile considering whether one might be inherently more effective than the other. We present a simple mathematical model that explores how interventions aimed at these two approaches affect the availability of effective drugs. Our results identify an interesting feature of evolution management that, all else equal, tends to make it more effective than enhancing drug development. Thus, although enhancing drug development will necessarily be a central part of addressing the problem of resistance, our results lend support to the idea that evolution management is probably a very significant component of the solution as well.

  8. A theoretical examination of the relative importance of evolution management and drug development for managing resistance

    PubMed Central

    McClure, Nathan S.; Day, Troy

    2014-01-01

    Drug resistance is a serious public health problem that threatens to thwart our ability to treat many infectious diseases. Repeatedly, the introduction of new drugs has been followed by the evolution of resistance. In principle, there are two complementary ways to address this problem: (i) enhancing drug development and (ii) slowing the evolution of drug resistance through evolutionary management. Although these two strategies are not mutually exclusive, it is nevertheless worthwhile considering whether one might be inherently more effective than the other. We present a simple mathematical model that explores how interventions aimed at these two approaches affect the availability of effective drugs. Our results identify an interesting feature of evolution management that, all else equal, tends to make it more effective than enhancing drug development. Thus, although enhancing drug development will necessarily be a central part of addressing the problem of resistance, our results lend support to the idea that evolution management is probably a very significant component of the solution as well. PMID:25377456

  9. A More Fine-Grained Measure of Students' Acceptance of Evolution: Development of the Inventory of Student Evolution Acceptance—I-SEA

    NASA Astrophysics Data System (ADS)

    Nadelson, Louis S.; Southerland, Sherry

    2012-07-01

    The potential influences of affective perceptions on cognitive engagement in learning, particularly with emotionally charged topics such as evolution, provide justification for acknowledging and assessing learners' attitudes toward content. One approach to determining students' attitudes toward a construct is to explicitly ask them to what degree they accept the related content. This was the approach we took as we developed the Inventory of Student Evolution Acceptance. Our goal was to make a finer-grained instrument that would assess acceptance on three evolution subscales: microevolution, macroevolution, and human evolution. Further, we sought to not conflate understanding with acceptance of the constructs. We began our instrument development with a series of interviews and open-ended questionnaires to determine students' perceptions of evolution acceptance. Based on the responses we developed and field tested a 49-item Likert scale instrument with stems distributed across our three targeted subscales. Using the data from our field test, we reduced the instrument to 24 items evenly distributed across the three subscales, and the revised instrument was again field tested with high school and undergraduate college students. The final instrument has an internal reliability of Cronbach's alpha of 0.96 and the items loaded onto three components that reflect documented evolution acceptance conditions. The instrument development, implications, and applications are discussed.

  10. Evolution de la résistance aux antibiotiques des entérobactéries isolées à l'Hôpital Général de Douala de 2005 à 2012

    PubMed Central

    Ebongue, Cécile Okalla; Tsiazok, Martial Dongmo; Mefo'o, Jean Pierre Nda; Ngaba, Guy Pascal; Beyiha, Gérard; Adiogo, Dieudonné

    2015-01-01

    Introduction Cette étude vise à déterminer le profil de résistance aux antibiotiques des entérobactéries isolées à l'Hôpital Général de Douala (Cameroun) et analyser leur évolution dans le temps. Méthodes Etude rétrospective, sur une période de huit ans (2005 - 2012), portant sur l'ensemble des souches d'entérobactéries isolées chez les malades ambulatoires et hospitalisés. Les prélèvements ont été analysés au laboratoire de bactériologie de l'Hôpital Général de Douala. Résultats Les entérobactéries étaient les germes les plus fréquents sur l'ensemble des souches isolées. Nous avons noté une prédominance d’Escherichia coli (48,5%) et de Klebsiella pneumoniae (32,8%). Pendant la période d’étude, nous avons observé des taux de résistance élevés aux principales classes d'antibiotiques, et une augmentation entre 2005 et 2012 de 29,1% à 51,6% pour les céphalosporines de troisième génération, de 29,2% à 44% pour la ciprofloxacine. L'imipénème, l'amikacine et la fosfomycine étaient les molécules les plus actives avec respectivement 1,3%, 12,9% et 13,4% des souches d'entérobactéries résistantes. Conclusion L’évolution des résistances des entérobactéries aux antibiotiques est un phénomène réel dans la ville de Douala. Il expose à des difficultés de prise en charge thérapeutique des infections. Lamaitrise actuelle de ce phénomène est une véritable urgence et nécessite une implication des pouvoirs publics. Des tests spécifiques de recherche des bétalactamases à spectre élargi (BLSE) et AmpC doivent être mis en place dans nos laboratoires afin de mettre en évidence les différents phénotypes de résistances. PMID:26140070

  11. Vocal Development as a Guide to Modeling the Evolution of Language.

    PubMed

    Oller, D Kimbrough; Griebel, Ulrike; Warlaumont, Anne S

    2016-04-01

    Modeling of evolution and development of language has principally utilized mature units of spoken language, phonemes and words, as both targets and inputs. This approach cannot address the earliest phases of development because young infants are unable to produce such language features. We argue that units of early vocal development-protophones and their primitive illocutionary/perlocutionary forces-should be targeted in evolutionary modeling because they suggest likely units of hominin vocalization/communication shortly after the split from the chimpanzee/bonobo lineage, and because early development of spontaneous vocal capability is a logically necessary step toward vocal language, a root capability without which other crucial steps toward vocal language capability are impossible. Modeling of language evolution/development must account for dynamic change in early communicative units of form/function across time. We argue for interactive contributions of sender/infants and receiver/caregivers in a feedback loop involving both development and evolution and propose to begin computational modeling at the hominin break from the primate communicative background.

  12. Development of the cypriniform protrusible jaw complex in Danio rerio: constructional insights for evolution.

    PubMed

    Staab, Katie Lynn; Hernandez, L Patricia

    2010-07-01

    Studies on the evolution of complex biological systems are difficult because the construction of these traits cannot be observed during the course of evolution. Complex traits are defined as consisting of multiple elements, often of differing embryological origins, with multiple linkages integrated to form a single functional unit. An example of a complex system is the cypriniform oral jaw apparatus. Cypriniform fishes possess an upper jaw characterized by premaxillary protrusion during feeding. Cypriniforms effect protrusion via the kinethmoid, a synapomorphy for the order. The kinethmoid is a sesamoid ossification suspended by ligaments attaching to the premaxillae, maxillae, palatines, and neurocranium. Upon mouth opening, the kinethmoid rotates as the premaxillae move anteriorly. Along with bony and ligamentous elements, there are three divisions of the adductor mandibulae that render this system functional. It is unclear how cypriniform jaws evolved because although the evolution of sesamoid elements is common, the incorporation of the kinethmoid into the protrusible jaw results in a function that is atypical for sesamoids. Developmental studies can show how biological systems are assembled within individuals and offer clues about how traits might have been constructed during evolution. We investigated the development of the protrusible upper jaw in zebrafish to generate hypotheses regarding the evolution of this character. Early in development, the adductor mandibulae arises as a single unit. The muscle divides after ossification of the maxillae, on which the A1 division will ultimately insert. A cartilaginous kinethmoid first develops within the intermaxillary ligament; it later ossifies at points of ligamentous attachment. We combine our structural developmental data with published kinematic data at key developmental stages and discuss potential functional advantages in possessing even the earliest stages of a system for protrusion.

  13. Vocal development as a guide to modeling the evolution of language

    PubMed Central

    Oller, D. Kimbrough; Griebel, Ulrike; Warlaumont, Anne S.

    2016-01-01

    Modeling of evolution and development of language has principally utilized mature units of spoken language, phonemes and words, as both targets and inputs. This approach cannot address the earliest phases of development because young infants are unable to produce such language features. We argue that units of early vocal development—protophones and their primitive illocutionary/perlocutionary forces—should be targeted in evolutionary modeling because they suggest likely units of hominin vocalization/communication shortly after the split from the chimpanzee/bonobo lineage, and because early development of spontaneous vocal capability is a logically necessary step toward vocal language, a root capability without which other crucial steps toward vocal language capability are impossible. Modeling of language evolution/development must account for dynamic change in early communicative units of form/function across time. We argue for interactive contributions of sender/infants and receiver/caregivers in a feedback loop involving both development and evolution and propose to begin computational modeling at the hominin break from the primate communicative background. PMID:26932662

  14. Correlated Evolution between Mode of Larval Development and Habitat in Muricid Gastropods

    PubMed Central

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Abstract Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids

  15. Correlated evolution between mode of larval development and habitat in muricid gastropods.

    PubMed

    Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

    2014-01-01

    Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.

  16. Phylogeny and evo-devo: characters, homology, and the historical analysis of the evolution of development.

    PubMed

    Cracraft, Joel

    2005-01-01

    The concept of homology continues to attract more and more commentary. In systematic and evolutionary biology the meaning of homology as synapomorphic similarity inherited from a common ancestor has gained wide acceptance over the last three or four decades. In recent years, however, developmental biologists, in particular, have argued for a new approach to, and new definition for, homology that revolves around the desire to make it more process-oriented and more mechanistic. These efforts raise questions about the relationship between developmental and evolutionary biology as well as how the evolution of development is to be studied. It is argued in this paper that this new approach to homology seemingly decouples developmental biology from the study of the evolution of development rather than to facilitate that study. In contrast, applying the notion of historical, phylogenetic homology to developmental data is inherently comparative and therefore evolutionary.

  17. Historical perspective on the development and evolution of eyes and photoreceptors.

    PubMed

    Gehring, Walter J

    2004-01-01

    The development and evolution of eyes is an "old problem" in biology, which required a special treatment in Charles Darwin's "Origin of the species" (1882) under the heading of "Difficulties of the theory". Darwin postulated a simple and imperfect eye, as a prototype, which can vary and evolve under natural selection into more complex and perfect eyes. Based upon morphological criteria and the different modes of development of the different kinds of eyes, neodarwinists have postulated that the various eye-types are polyphyletic in origin and that the eyes have evolved independently in the various animal phyla. Recent developmental genetic experiments and molecular phylogenetic analyses cast serious doubts on this interpretation and argue strongly for a monophyletic origin of the eyes from a Darwinian prototype and subsequent divergent, parallel and convergent evolution leading to the various eye-types.

  18. Morphology, development, and evolution of fetal membranes and placentation in squamate reptiles.

    PubMed

    Blackburn, Daniel G; Flemming, Alexander F

    2009-09-15

    Current studies on fetal membranes of reptiles are providing insight into three major historical transformations: evolution of the amniote egg, evolution of viviparity, and evolution of placentotrophy. Squamates (lizards and snakes) are ideal for such studies because their fetal membranes sustain embryos in oviparous species and contribute to placentas in viviparous species. Ultrastructure of the fetal membranes in oviparous corn snakes (Pituophis guttatus) shows that the chorioallantois is specialized for gas exchange and the omphalopleure, for water absorption. Transmission and scanning electron microscopic studies of viviparous thamnophine snakes (Thamnophis, Storeria) have revealed morphological specializations for gas exchange and absorption in the intra-uterine environment that represent modifications of features found in oviparous species. Thus, fetal membranes in oviparous species show morphological differentiation for distinct functions that have been recruited and enhanced under viviparous conditions. The ultimate in specialization of fetal membranes is found in viviparous skinks of South America (Mabuya) and Africa (Trachylepis, Eumecia), in which placentotrophy accounts for nearly all of the nutrients for development. Ongoing research on these lizards has revealed morphological specializations of the chorioallantoic placenta through which nutrient transfer is accomplished. In addition, African Trachylepis show an invasive form of implantation, in which uterine epithelium is replaced by invading chorionic cells. Ongoing analysis of these lizards shows how integration of multiple lines of evidence can provide insight into the evolution of developmental and reproductive specializations once thought to be confined to eutherian mammals.

  19. [Centennial retrospective on the evolution and development of the nursing profession in Taiwan].

    PubMed

    Wang, Kwua-Yun; Chang, Shu-Rong

    2014-08-01

    This article explores the evolution and development of the Taiwanese nursing profession. After introducing the origins of nursing, this article proceeds to introduce nursing during various periods in Taiwan, including the early-Qing Dynasty, foreign missionary nursing, the Japanese Colonial Era, and the Nationalist Chinese Era following World War Two up to the present. The authors then present the current situation in the Taiwanese nursing profession in terms of gender issues, high-technology developments, educational issues, the nursing licensing examination, hiring and training, multiple role functions, and the skill-mix care model. Finally, the authors make recommendations for the further development and improvement of the nursing profession in Taiwan.

  20. Neocentromeres: New Insights into Centromere Structure, Disease Development, and Karyotype Evolution

    PubMed Central

    Marshall, Owen J.; Chueh, Anderly C.; Wong, Lee H.; Choo, K.H. Andy

    2008-01-01

    Since the discovery of the first human neocentromere in 1993, these spontaneous, ectopic centromeres have been shown to be an astonishing example of epigenetic change within the genome. Recent research has focused on the role of neocentromeres in evolution and speciation, as well as in disease development and the understanding of the organization and epigenetic maintenance of the centromere. Here, we review recent progress in these areas of research and the significant insights gained. PMID:18252209

  1. Geochemical evolution of the northern plains of Mars - Early hydrosphere, carbonate development, and present morphology

    NASA Technical Reports Server (NTRS)

    Schaefer, Martha W.

    1990-01-01

    An equilibrium geochemical model of the primitive Martian atmosphere-regolith-ocean system that could have existed early in the history of Mars is developed. The results of this model are used to examine the evolution of the volatile budget of Mars and the processes occurring in the Martian ocean that may have contributed to the deposition of large carbonate beds on the northern plains. Results of this model are compared to those of the Pollack et al. (1987) model.

  2. Evolution of facility layout requirements and CAD (computer-aided design) system development

    SciTech Connect

    Jones, M. )

    1990-06-01

    The overall configuration of the Superconducting Super Collider (SSC) including the infrastructure and land boundary requirements were developed using a computer-aided design (CAD) system. The evolution of the facility layout requirements and the use of the CAD system are discussed. The emphasis has been on minimizing the amount of input required and maximizing the speed by which the output may be obtained. The computer system used to store the data is also described.

  3. Tuberculosis Drug Development: History and Evolution of the Mechanism-Based Paradigm.

    PubMed

    Chakraborty, Sumit; Rhee, Kyu Y

    2015-04-15

    Modern tuberculosis (TB) chemotherapy is widely viewed as a crowning triumph of anti-infectives research. However, only one new TB drug has entered clinical practice in the past 40 years while drug resistance threatens to further destabilize the pandemic. Here, we review a brief history of TB drug development, focusing on the evolution of mechanism(s)-of-action studies and key conceptual barriers to rational, mechanism-based drugs. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  4. Development of a Software Evolution Process for Military Systems Composed of Integrated Commercial off the Shelf Components

    DTIC Science & Technology

    2000-03-01

    system architectures. Traditional DoD source code development and evolution methodologies do not effectively support COTS-intensive systems. To fully...realize the benefits of COTS technologies and products, the DoD must adopt new ways to sustain system evolution in the face of a dynamic market...environment subject to constant change. This thesis proposes a new software evolution methodology to effectively maintain COTS-intensive military systems

  5. Genomics, evolution and development of amphioxus and tunicates: The Goldilocks principle.

    PubMed

    Holland, Linda Z

    2015-06-01

    Morphological comparisons among extant animals have long been used to infer their long-extinct ancestors for which the fossil record is poor or non-existent. For evolution of the vertebrates, the comparison has typically involved amphioxus and vertebrates. Both groups are evolving relatively slowly, and their genomes share a high level of synteny. Both vertebrates and amphioxus have regulative development in which cell fates become fixed only gradually during embryogenesis. Thus, their development fits a modified hourglass model in which constraints are greatest at the phylotypic stage (i.e., the late neurula/early larva), but are somewhat greater on earlier development than on later development. In contrast, the third group of chordates, the tunicates, which are sister group to vertebrates, are evolving rapidly. Constraints on evolution of tunicate genomes are relaxed, and they have discarded key developmental genes and organized much of their coding sequences into operons, which are transcribed as a single mRNA that undergoes trans-splicing. This contrasts with vertebrates and amphioxus, whose genomes are not organized into operons. Concomitantly, tunicates have switched to determinant development with very early fixation of cell fates. Thus, tunicate development more closely fits a progressive divergence model (shaped more like a wine glass than an hourglass) in which the constraints on the zygote and very early development are greatest. This model can help explain why tunicate body plans are so very diverse. The relaxed constraints on development after early cleavage stages are correlated with relaxed constraints on genome evolution. The question remains: which came first?

  6. Insects as test systems for assessing the potential role of microgravity in biological development and evolution

    NASA Astrophysics Data System (ADS)

    Vernós, I.; Carratalá, M.; González-Jurado, J.; Valverde, J. R.; Calleja, M.; Domingo, A.; Vinós, J.; Cervera, M.; Marco, R.

    Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into

  7. Insects as test systems for assessing the potential role of microgravity in biological development and evolution.

    PubMed

    Vernós, I; Carratalá, M; González-Jurado, J; Valverde, J R; Calleja, M; Domingo, A; Vinós, J; Cervera, M; Marco, R

    1989-01-01

    Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into

  8. Molecular development of fibular reduction in birds and its evolution from dinosaurs.

    PubMed

    Botelho, João Francisco; Smith-Paredes, Daniel; Soto-Acuña, Sergio; O'Connor, Jingmai; Palma, Verónica; Vargas, Alexander O

    2016-03-01

    Birds have a distally reduced, splinter-like fibula that is shorter than the tibia. In embryonic development, both skeletal elements start out with similar lengths. We examined molecular markers of cartilage differentiation in chicken embryos. We found that the distal end of the fibula expresses Indian hedgehog (IHH), undergoing terminal cartilage differentiation, and almost no Parathyroid-related protein (PTHrP), which is required to develop a proliferative growth plate (epiphysis). Reduction of the distal fibula may be influenced earlier by its close contact with the nearby fibulare, which strongly expresses PTHrP. The epiphysis-like fibulare however then separates from the fibula, which fails to maintain a distal growth plate, and fibular reduction ensues. Experimental downregulation of IHH signaling at a postmorphogenetic stage led to a tibia and fibula of equal length: The fibula is longer than in controls and fused to the fibulare, whereas the tibia is shorter and bent. We propose that the presence of a distal fibular epiphysis may constrain greater growth in the tibia. Accordingly, many Mesozoic birds show a fibula that has lost its distal epiphysis, but remains almost as long as the tibia, suggesting that loss of the fibulare preceded and allowed subsequent evolution of great fibulo-tibial disparity. © 2016 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  9. Friends with social benefits: host-microbe interactions as a driver of brain evolution and development?

    PubMed

    Stilling, Roman M; Bordenstein, Seth R; Dinan, Timothy G; Cryan, John F

    2014-01-01

    The tight association of the human body with trillions of colonizing microbes that we observe today is the result of a long evolutionary history. Only very recently have we started to understand how this symbiosis also affects brain function and behavior. In this hypothesis and theory article, we propose how host-microbe associations potentially influenced mammalian brain evolution and development. In particular, we explore the integration of human brain development with evolution, symbiosis, and RNA biology, which together represent a "social triangle" that drives human social behavior and cognition. We argue that, in order to understand how inter-kingdom communication can affect brain adaptation and plasticity, it is inevitable to consider epigenetic mechanisms as important mediators of genome-microbiome interactions on an individual as well as a transgenerational time scale. Finally, we unite these interpretations with the hologenome theory of evolution. Taken together, we propose a tighter integration of neuroscience fields with host-associated microbiology by taking an evolutionary perspective.

  10. Friends with social benefits: host-microbe interactions as a driver of brain evolution and development?

    PubMed Central

    Stilling, Roman M.; Bordenstein, Seth R.; Dinan, Timothy G.; Cryan, John F.

    2014-01-01

    The tight association of the human body with trillions of colonizing microbes that we observe today is the result of a long evolutionary history. Only very recently have we started to understand how this symbiosis also affects brain function and behavior. In this hypothesis and theory article, we propose how host-microbe associations potentially influenced mammalian brain evolution and development. In particular, we explore the integration of human brain development with evolution, symbiosis, and RNA biology, which together represent a “social triangle” that drives human social behavior and cognition. We argue that, in order to understand how inter-kingdom communication can affect brain adaptation and plasticity, it is inevitable to consider epigenetic mechanisms as important mediators of genome-microbiome interactions on an individual as well as a transgenerational time scale. Finally, we unite these interpretations with the hologenome theory of evolution. Taken together, we propose a tighter integration of neuroscience fields with host-associated microbiology by taking an evolutionary perspective. PMID:25401092

  11. Not just black and white: pigment pattern development and evolution in vertebrates

    PubMed Central

    Mills, Margaret G.; Patterson, Larissa B.

    2009-01-01

    Animals display diverse colors and patterns that vary within and between species. Similar phenotypes appear in both closely related and widely divergent taxa. Pigment patterns thus provide an opportunity to explore how development is altered to produce differences in form and whether similar phenotypes share a common genetic basis. Understanding the development and evolution of pigment patterns requires knowledge of the cellular interactions and signaling pathways that produce those patterns. These complex traits provide unparalleled opportunities for integrating studies from ecology and behavior to molecular biology and biophysics. PMID:19073271

  12. Effects of ionizing radiation and pretreatment with (D-Leu6,des-Gly10) luteinizing hormone-releasing hormone ethylamide on developing rat ovarian follicles

    SciTech Connect

    Jarrell, J.; YoungLai, E.V.; McMahon, A.; Barr, R.; O'Connell, G.; Belbeck, L.

    1987-10-01

    To assess the effects of a gonadotropin-releasing hormone agonist, (D-Leu6,des-Gly10) luteinizing hormone-releasing hormone ethylamide, in ameliorating the damage caused by ionizing radiation, gonadotropin-releasing hormone agonist was administered to rats from day 22 to 37 of age in doses of 0.1, 0.4, and 1.0 microgram/day or vehicle and the rats were sacrificed on day 44 of age. There were no effects on estradiol, progesterone, luteinizing, or follicle-stimulating hormone, nor an effect on ovarian follicle numbers or development. In separate experiments, rats treated with gonadotropin-releasing hormone agonist in doses of 0.04, 0.1, 0.4, or 1.0 microgram/day were either irradiated or sham irradiated on day 30 and all groups sacrificed on day 44 of age. Irradiation produced a reduction in ovarian weight and an increase in ovarian follicular atresia. Pretreatment with the agonist prevented the reduction in ovarian weight and numbers of primordial and preantral follicles but not healthy or atretic antral follicles. Such putative radioprotection should be tested on actual reproductive performance.

  13. Development and Preliminary Evaluation of a New Real-Time RT-PCR Assay For Detection of Peste des petits Ruminants Virus Genome.

    PubMed

    Polci, A; Cosseddu, G M; Ancora, M; Pinoni, C; El Harrak, M; Sebhatu, T T; Ghebremeskel, E; Sghaier, S; Lelli, R; Monaco, F

    2015-06-01

    A duplex real-time reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for a simple and rapid diagnosis of Peste des petits ruminants (PPR). qRT-PCR primers and TaqMan probe were designed on a conserved region of nucleocapsid protein (Np) of PPR virus (PPRV) genome. An in vitro transcript of the target region was constructed and tested to determine analytical sensitivity. Commercial heterologous Armored RNA(®) was used as an internal positive control (IPC) for either RNA isolation or RT-PCR steps. The detection limit of the newly designed duplex real-time RT-PCR (qRT-PCR PPR_Np) was approximately 20 copies/μl with a 95% probability. No amplification signals were recorded when the qRT-PCR PPR_Np was applied to viruses closely related or clinically similar to PPRV- or to PPR-negative blood samples. A preliminary evaluation of the diagnostic performance was carried out by testing a group of 43 clinical specimens collected from distinct geographic areas of Africa and Middle East. qRT-PCR PPR_Np showed higher sensitivity than the conventional gel-based RT-PCR assays, which have been used as reference standards. Internal positive control made it possible to identify the occurrence of 5 false-negative results caused by the amplification failure, thus improving the accuracy of PPRV detection. © 2013 Blackwell Verlag GmbH.

  14. [Physiological problems of biological evolution. "Errors" in the development of physiological functions].

    PubMed

    Ivanov, K P; Mel'nikova, N N

    2005-01-01

    During the evolution the physiological functions grow more perfect and complex. However, sometimes a developing function can show some evidence of regress and in certain cases can become the cause of dangerous diseases. The autoimmune diseases are among them. We conventionally call such cases the "error" of the evolution. In this work a negative role of leukocytes in the brain microcirculation is considered. With the help of experimental studies it was shown that leukocytes owing to their large volume (by a factor of 2-2.5 greater than the volume of an erythrocyte) slow down the capillary blood flow. As the result of the increasing tendency to adhesion, under the influence of hypoxia they make leukocyte conglomerates which cause the occlusion of venules and smallest veins of the brain. This is the reason for the known effect "no reflow" and results in an organism death.

  15. Fibroblast growth factors: from molecular evolution to roles in development, metabolism and disease.

    PubMed

    Itoh, Nobuyuki; Ornitz, David M

    2011-02-01

    Fibroblast growth factors (FGFs) are a family of structurally related polypeptides that are essential for embryonic development and that function postnatally as homoeostatic factors, in the response to injury, in the regulation of electrical excitability of cells and as hormones that regulate metabolism. In humans, FGF signalling is involved in developmental, neoplastic, metabolic and neurological diseases. Fgfs have been identified in metazoans but not in unicellular organisms. In vertebrates, FGFs can be classified as having intracrine, paracrine and endocrine functions. Paracrine and endocrine FGFs act via cell-surface FGF receptors (FGFRs); while, intracrine FGFs act independent of FGFRs. The evolutionary history of the Fgf family indicates that an intracrine Fgf is the likely ancestor of the Fgf family. During metazoan evolution, the Fgf family expanded in two phases, after the separation of protostomes and deuterostomes and in the evolution of early vertebrates. These expansions enabled FGFs to acquire diverse actions and functions.

  16. Development of a Dinitrosyl Iron Complex Molecular Catalyst into a Hydrogen Evolution Cathode.

    PubMed

    Chiou, Tzung-Wen; Lu, Tsai-Te; Wu, Ying-Hao; Yu, Yi-Ju; Chu, Li-Kang; Liaw, Wen-Feng

    2015-12-01

    Despite extensive efforts, the electrocatalytic reduction of water using homogeneous/heterogeneous Fe, Co, Ni, Cu, W, and Mo complexes remains challenging because of issues involving the development of efficient, recyclable, stable, and aqueous-compatible catalysts. In this study, evolution of the de novo designed dinitrosyl iron complex DNIC-PMDTA from a molecular catalyst into a solid-state hydrogen evolution cathode, considering all the parameters to fulfill the electronic and structural requirements of each step of the catalytic cycle, is demonstrated. DNIC-PMDTA reveals electrocatalytic reduction of water at neutral and basic media, whereas its deposit on electrode preserves exceptional longevity, 139 h. This discovery will initiate a systematic study on the assembly of [Fe(NO)2] motif into current collector for mass production of H2, whereas the efficiency remains tailored by its molecular precursor [(L)Fe(NO)2].

  17. Morphological Evolution of Physical Robots through Model-Free Phenotype Development

    PubMed Central

    Brodbeck, Luzius; Hauser, Simon; Iida, Fumiya

    2015-01-01

    Artificial evolution of physical systems is a stochastic optimization method in which physical machines are iteratively adapted to a target function. The key for a meaningful design optimization is the capability to build variations of physical machines through the course of the evolutionary process. The optimization in turn no longer relies on complex physics models that are prone to the reality gap, a mismatch between simulated and real-world behavior. We report model-free development and evaluation of phenotypes in the artificial evolution of physical systems, in which a mother robot autonomously designs and assembles locomotion agents. The locomotion agents are automatically placed in the testing environment and their locomotion behavior is analyzed in the real world. This feedback is used for the design of the next iteration. Through experiments with a total of 500 autonomously built locomotion agents, this article shows diversification of morphology and behavior of physical robots for the improvement of functionality with limited resources. PMID:26091255

  18. Embedding Evolution: Exploring Changes in Students' Conceptual Development, Beliefs, and Motivations in a Population Ecology Unit

    NASA Astrophysics Data System (ADS)

    Rose, Nancy L.

    The purpose of this study was to explore student changes in conceptual development, epistemology, and motivations when evolution concepts are embedded and explicit reflective discourse is used in a unit for population ecology. The two research problems were: (1) What changes are observed in student's conceptual development, epistemology, and motivations when there is explicit reflective discourse within a population ecology unit with embedded evolution?, and (2) In what ways does explicit reflection influence students' mental models within a population ecology unit with embedded evolution? This mixed-method, quasi-experimental study assessed two regular high school biology classes in a small, urban, Midwestern high school. Students in this study had not studied evolution within any formal chapters, but had been immersed in a curriculum with embedded evolution. The study was conducted over a four-week period in a population ecology unit near the beginning of second semester. Instruction emphasized basic conceptions in population ecology. Five key intervention activities included evolutionary concepts as part of an embedded curriculum. The independent variable was explicit reflective discourse with one or two intervention questions after completion of these activities. Data included pre- and posttest surveys measuring (a) evolutionary understanding of natural selection, (b) science beliefs, and (c) science motivations. Written artifacts included (a) explanations to scenarios, (b) pre- and post-argument reflections revealing student's science beliefs and science motivations resultant from two argumentations, and (c) three, pre-, post-, and 6-week final concept maps constructed from 12 concepts. All data sources provided descriptive data. Conceptual change was interpreted from an ontological, epistemological, and motivational perspective. The experimental class receiving explicit reflective discourse showed greater overall increases in conceptual development. Students

  19. Energetic and nutritional constraints on infant brain development: implications for brain expansion during human evolution.

    PubMed

    Cunnane, Stephen C; Crawford, Michael A

    2014-12-01

    The human brain confronts two major challenges during its development: (i) meeting a very high energy requirement, and (ii) reliably accessing an adequate dietary source of specific brain selective nutrients needed for its structure and function. Implicitly, these energetic and nutritional constraints to normal brain development today would also have been constraints on human brain evolution. The energetic constraint was solved in large measure by the evolution in hominins of a unique and significant layer of body fat on the fetus starting during the third trimester of gestation. By providing fatty acids for ketone production that are needed as brain fuel, this fat layer supports the brain's high energy needs well into childhood. This fat layer also contains an important reserve of the brain selective omega-3 fatty acid, docosahexaenoic acid (DHA), not available in other primates. Foremost amongst the brain selective minerals are iodine and iron, with zinc, copper and selenium also being important. A shore-based diet, i.e., fish, molluscs, crustaceans, frogs, bird's eggs and aquatic plants, provides the richest known dietary sources of brain selective nutrients. Regular access to these foods by the early hominin lineage that evolved into humans would therefore have helped free the nutritional constraint on primate brain development and function. Inadequate dietary supply of brain selective nutrients still has a deleterious impact on human brain development on a global scale today, demonstrating the brain's ongoing vulnerability. The core of the shore-based paradigm of human brain evolution proposes that sustained access by certain groups of early Homo to freshwater and marine food resources would have helped surmount both the nutritional as well as the energetic constraints on mammalian brain development.

  20. Language at three timescales: The role of real-time processes in language development and evolution

    PubMed Central

    McMurray, Bob

    2016-01-01

    Evolutionary developmental systems (Evo-Devo) theory stresses that selection pressures operate on entire developmental systems rather than just genes. This paper extends this approach to language evolution arguing that selection pressure may operate on two quasi-independent timescales. First, children clearly must acquire language successfully (as acknowledged in traditional Evo-Devo accounts) and evolution must equip them with the tools to do so. Second, while this is developing they must also communicate with others in the moment using partially developed knowledge. These pressures may require different solutions and their combination may underlie the evolution of complex mechanisms for language development and processing. I present two case studies to illustrate how the demands of both real-time communication and language acquisition may be subtly different (and interact). The first case study examines infant directed speech (IDS). A recent view is that IDS underwent cultural to statistical learning mechanisms that infants use to acquire the speech categories of their language. However, recent data suggest is it may not have evolved to enhance development, but rather to serve a more real-time communicative function. The second case study examines the argument for seemingly specialized mechanisms for learning word meanings (e.g., fast-mapping). Both behavioral and computational work suggest that learning may be much slower, and served by general purpose mechanisms like associative learning. Fast-mapping, then, may be a real-time process meant to serve immediate communication, not learning, by augmenting incomplete vocabulary knowledge with constraints from the current context. Together, these studies suggest that evolutionary accounts consider selection pressure arising from both real-time communicative demands and from the need for accurate language development. PMID:26991438

  1. Language at Three Timescales: The Role of Real-Time Processes in Language Development and Evolution.

    PubMed

    McMurray, Bob

    2016-04-01

    Evolutionary developmental systems (evo-devo) theory stresses that selection pressures operate on entire developmental systems rather than just genes. This study extends this approach to language evolution, arguing that selection pressure may operate on two quasi-independent timescales. First, children clearly must acquire language successfully (as acknowledged in traditional evo-devo accounts) and evolution must equip them with the tools to do so. Second, while this is developing, they must also communicate with others in the moment using partially developed knowledge. These pressures may require different solutions, and their combination may underlie the evolution of complex mechanisms for language development and processing. I present two case studies to illustrate how the demands of both real-time communication and language acquisition may be subtly different (and interact). The first case study examines infant-directed speech (IDS). A recent view is that IDS underwent cultural to statistical learning mechanisms that infants use to acquire the speech categories of their language. However, recent data suggest is it may not have evolved to enhance development, but rather to serve a more real-time communicative function. The second case study examines the argument for seemingly specialized mechanisms for learning word meanings (e.g., fast-mapping). Both behavioral and computational work suggest that learning may be much slower and served by general-purpose mechanisms like associative learning. Fast-mapping, then, may be a real-time process meant to serve immediate communication, not learning, by augmenting incomplete vocabulary knowledge with constraints from the current context. Together, these studies suggest that evolutionary accounts consider selection pressure arising from both real-time communicative demands and from the need for accurate language development. Copyright © 2016 Cognitive Science Society, Inc.

  2. The Genome and Development-Dependent Transcriptomes of Pyronema confluens: A Window into Fungal Evolution

    PubMed Central

    Traeger, Stefanie; Altegoer, Florian; Freitag, Michael; Gabaldon, Toni; Kempken, Frank; Kumar, Abhishek; Marcet-Houben, Marina; Pöggeler, Stefanie; Stajich, Jason E.; Nowrousian, Minou

    2013-01-01

    Fungi are a large group of eukaryotes found in nearly all ecosystems. More than 250 fungal genomes have already been sequenced, greatly improving our understanding of fungal evolution, physiology, and development. However, for the Pezizomycetes, an early-diverging lineage of filamentous ascomycetes, there is so far only one genome available, namely that of the black truffle, Tuber melanosporum, a mycorrhizal species with unusual subterranean fruiting bodies. To help close the sequence gap among basal filamentous ascomycetes, and to allow conclusions about the evolution of fungal development, we sequenced the genome and assayed transcriptomes during development of Pyronema confluens, a saprobic Pezizomycete with a typical apothecium as fruiting body. With a size of 50 Mb and ∼13,400 protein-coding genes, the genome is more characteristic of higher filamentous ascomycetes than the large, repeat-rich truffle genome; however, some typical features are different in the P. confluens lineage, e.g. the genomic environment of the mating type genes that is conserved in higher filamentous ascomycetes, but only partly conserved in P. confluens. On the other hand, P. confluens has a full complement of fungal photoreceptors, and expression studies indicate that light perception might be similar to distantly related ascomycetes and, thus, represent a basic feature of filamentous ascomycetes. Analysis of spliced RNA-seq sequence reads allowed the detection of natural antisense transcripts for 281 genes. The P. confluens genome contains an unusually high number of predicted orphan genes, many of which are upregulated during sexual development, consistent with the idea of rapid evolution of sex-associated genes. Comparative transcriptomics identified the transcription factor gene pro44 that is upregulated during development in P. confluens and the Sordariomycete Sordaria macrospora. The P. confluens pro44 gene (PCON_06721) was used to complement the S. macrospora pro44 deletion

  3. Decanalization of wing development accompanied the evolution of large wings in high-altitude Drosophila

    PubMed Central

    Lack, Justin B.; Monette, Matthew J.; Johanning, Evan J.; Sprengelmeyer, Quentin D.; Pool, John E.

    2016-01-01

    In higher organisms, the phenotypic impacts of potentially harmful or beneficial mutations are often modulated by complex developmental networks. Stabilizing selection may favor the evolution of developmental canalization—that is, robustness despite perturbation—to insulate development against environmental and genetic variability. In contrast, directional selection acts to alter the developmental process, possibly undermining the molecular mechanisms that buffer a trait’s development, but this scenario has not been shown in nature. Here, we examined the developmental consequences of size increase in highland Ethiopian Drosophila melanogaster. Ethiopian inbred strains exhibited much higher frequencies of wing abnormalities than lowland populations, consistent with an elevated susceptibility to the genetic perturbation of inbreeding. We then used mutagenesis to test whether Ethiopian wing development is, indeed, decanalized. Ethiopian strains were far more susceptible to this genetic disruption of development, yielding 26 times more novel wing abnormalities than lowland strains in F2 males. Wing size and developmental perturbability cosegregated in the offspring of between-population crosses, suggesting that genes conferring size differences had undermined developmental buffering mechanisms. Our findings represent the first observation, to our knowledge, of morphological evolution associated with decanalization in the same tissue, underscoring the sensitivity of development to adaptive change. PMID:26755605

  4. Des ballons pour demain

    NASA Astrophysics Data System (ADS)

    Régipa, R.

    A partir d'une théorie sur la détermination des formes et des contraintes globales d'un ballon de révolution, ou s'en rapprochant, une nouvelle famille de ballons a été définie. Les ballons actuels, dits de ``forme naturelle'', sont calculés en général pour une tension circonférencielle nulle. Ainsi, pour une mission donnée, la tension longitudinale et la forme de l'enveloppe sont strictement imposées. Les ballons de la nouvelle génération sont globalement cylindriques et leurs pôles sont réunis par un câble axial, chargé de transmettre une partie des efforts depuis le crochet (pôle inférieur), directement au pôle supérieur. De plus, la zone latérale cylindrique est soumise à un faible champ de tensions circonférencielles. Ainsi, deux paramètres permettent de faire évoluer la distribution des tensions et la forme de l'enveloppe: - la tension du câble de liaison entre pôles (ou la longueur de ce câble) - la tension circonférencielle moyenne désirée (ou le rayon du ballon). On peut donc calculer et réaliser: - soit des ballons de forme adaptée, comme les ballons à fond plat pour le bon fonctionnement des montgolfières infrarouge (projet MIR); - soit des ballons optimisés pour une bonne répartition des contraintes et une meilleure utilisation des matériaux d'enveloppe, pour l'ensemble des programmes stratosphériques. Il s'ensuit une économie sensible des coûts de fabrication, une fiabilité accrue du fonctionnement de ces ballons et une rendement opérationnel bien supérieur, permettant entre autres, d'envisager des vols à très haute altitude en matériaux très légers.

  5. Evolution and development of gas exchange structures in Mammalia: the placenta and the lung.

    PubMed

    Mess, Andrea M; Ferner, Kirsten J

    2010-08-31

    Appropriate oxygen supply is crucial for organisms. Here we examine the evolution of structures associated with the delivery of oxygen in the pre- and postnatal phases in mammals. There is an enormous structural and functional variability in the placenta that has facilitated the evolution of specialized reproductive strategies, such as precociality. In particular the cell layers separating fetal and maternal blood differ markedly: a non-invasive epitheliochorial placenta, which increases the diffusion distance, represents a derived state in ungulates. Rodents and their relatives have an invasive haemochorial placental type as optimum for the diffusion distance. In contrast, lung development is highly conserved and differences in the lungs of neonates can be explained by different developmental rates. Monotremes and marsupials have altricial stages with lungs at the early saccular phase, whereas newborn eutherians have lungs at the late saccular or alveolar phase. In conclusion, the evolution of exchange structures in the pre- and postnatal periods does not follow similar principles. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  6. Evolution and development of fetal membranes and placentation in amniote vertebrates.

    PubMed

    Ferner, Kirsten; Mess, Andrea

    2011-08-31

    We review aspects of fetal membrane evolution and patterns of placentation within amniotes, the most successful land vertebrates. Special reference is given to embryonic gas supply. The evolution of fetal membranes is a prerequisite for reproduction independent from aquatic environments. Starting from a basically similar repertoire of fetal membranes - the amnion, chorion, allantois and yolk sac, which form the cleidoic egg - different structural solutions for embryonic development have evolved. In oviparous amniotes the chorioallantoic membrane is the major site for the exchange of respiratory gases between fetus and outer environment. The richly vascularised yolk sac and allantois in concert with the chorion play an important role in the evolution of placentation in various viviparous amniotes. Highly complex placentas have evolved independently among squamate sauropsids and in marsupial and placental mammals. In conclusion, there seems to be a natural force to improve gas exchange processes in intrauterine environments by reducing the barrier between the blood systems and optimising the exchange areas. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Mapping arealisation of the visual cortex of non-primate species: lessons for development and evolution

    PubMed Central

    Homman-Ludiye, Jihane; Bourne, James A.

    2014-01-01

    The integration of the visual stimulus takes place at the level of the neocortex, organized in anatomically distinct and functionally unique areas. Primates, including humans, are heavily dependent on vision, with approximately 50% of their neocortical surface dedicated to visual processing and possess many more visual areas than any other mammal, making them the model of choice to study visual cortical arealisation. However, in order to identify the mechanisms responsible for patterning the developing neocortex, specifying area identity as well as elucidate events that have enabled the evolution of the complex primate visual cortex, it is essential to gain access to the cortical maps of alternative species. To this end, species including the mouse have driven the identification of cellular markers, which possess an area-specific expression profile, the development of new tools to label connections and technological advance in imaging techniques enabling monitoring of cortical activity in a behaving animal. In this review we present non-primate species that have contributed to elucidating the evolution and development of the visual cortex. We describe the current understanding of the mechanisms supporting the establishment of areal borders during development, mainly gained in the mouse thanks to the availability of genetically modified lines but also the limitations of the mouse model and the need for alternate species. PMID:25071460

  8. Language and life history: a new perspective on the development and evolution of human language.

    PubMed

    Locke, John L; Bogin, Barry

    2006-06-01

    It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language.

  9. Evolution of volatile compounds during the development of cabernet sauvignon grapes (Vitis vinifera L.).

    PubMed

    Kalua, Curtis M; Boss, Paul K

    2009-05-13

    The evolution of volatile compounds was explored in grape berries at fortnightly intervals from fruit-set to late ripening to identify when biosynthetic pathways may be targeted for enhancement of grape and wine aroma. Stepwise linear discriminant analysis (SLDA) fully recognized patterns in berry physiological developmental stages with most of the variance (>99.0%) explained. The preveraison berry developmental stage was identified as a transition stage for volatile compound biosynthesis when most compounds were potentially sequestered to nonvolatile conjugates and berries lost their potential to synthesize esters and terpenes. Terpenes (predominantly eucalyptol, beta-caryophyllene, and alpha-humulene) characterized early berry development, whereas benzene derivatives (2-phenylethanol and 2-phenylethanal) appeared toward late ripening. Furthermore, C(6) volatile compounds changed from acetate esters to aldehydes and finally to alcohols during early, middle, and late berry developmental stages, respectively. The dominance of alcohols in the late stages of berry development, preceded by aldehydes, offers an opportunity for alcohols to aldehydes ratios to be used in the prediction of harvest timing for enhanced grape and wine aroma. The evolution of volatile compounds during berry development suggests a greater dependency on enzyme activity and specificity than extent of fatty acid unsaturation. The dependence of the stage of berry development on the accumulation of the products of alcohol dehydrogenase (ADH), alcohol acetyl transferase (AAT), and enal isomerase enzyme activity from the lipoxygenase pathway raises possibilities for the manipulation of aroma profiles in grapes and wines.

  10. Space Launch System Spacecraft/Payloads Integration and Evolution Office Advanced Development FY 2014 Annual Report

    NASA Technical Reports Server (NTRS)

    Crumbly, C. M.; Bickley, F. P.; Hueter, U.

    2015-01-01

    The Advanced Development Office (ADO), part of the Space Launch System (SLS) program, provides SLS with the advanced development needed to evolve the vehicle from an initial Block 1 payload capability of 70 metric tons (t) to an eventual capability Block 2 of 130 t, with intermediary evolution options possible. ADO takes existing technologies and matures them to the point that insertion into the mainline program minimizes risk. The ADO portfolio of tasks covers a broad range of technical developmental activities. The ADO portfolio supports the development of advanced boosters, upper stages, and other advanced development activities benefiting the SLS program. A total of 36 separate tasks were funded by ADO in FY 2014.

  11. Evolution-development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures.

    PubMed

    Kohsokabe, Takahiro; Kaneko, Kunihiko

    2016-01-01

    Search for possible relationships between phylogeny and ontogeny is important in evolutionary-developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell-to-cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi-stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical-systems theory, which lead to the evolution-development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution Published by Wiley Periodicals, Inc.

  12. Development of a two-step SYBR Green I based real time RT-PCR assay for detecting and quantifying peste des petits ruminants virus in clinical samples.

    PubMed

    Abera, Tsegalem; Thangavelu, Ardhanary

    2014-12-01

    A two-step SYBR Green I based real time RT-PCR targeting the matrix (M) gene of Peste des petits ruminants virus (PPRV) was developed. The specificity of the assay was assessed against viral nucleic acid extracted from a range of animal viruses of clinical and structural similarities to PPRV including canine distemper virus, measles virus, bluetongue virus and Newcastle disease virus. But none of the viruses and no template control showed an amplification signal. Sensitivity of the same assay was assessed based on plasmid DNA copy number and with respect to infectivity titre. The lower detection limit achieved was 2.88 plasmid DNA copies/μl with corresponding Ct value of 35.93. Based on tissue culture infectivity titre the lower detection limits were 0.0001TCID50/ml and 1TCID50/ml for the SYBR green I based real time RT-PCR and conventional RT-PCR, respectively. The calculated coefficient of variations values for intra- and inter-assay variability were low, ranging from 0.21% to 1.83% and 0.44% to 1.97%, respectively. The performance of newly developed assay was evaluated on a total of 36 clinical samples suspected of PPR and compared with conventional RT-PCR. The SYBR Green I based real time RT-PCR assay detected PPRV in 32 (88.8%) of clinical samples compared to 19 (52.7%) by conventional RT-PCR. Thus, the two-step SYBR Green I based real time RT-PCR assay targeting the M gene of PPRV reported in this study was highly sensitive, specific and reproducible for detection and quantitation of PPRV nucleic acids.

  13. Simulation de l'accretion de glace sur un obstacle bidimensionnel par la methode des bissectrices et par la modelisation des ruisselets et des gouttes de surface

    NASA Astrophysics Data System (ADS)

    Fortin, Guy

    Le LIMA (Laboratoire International des Materiaux Antigivre) en collaboration avec le CIRA (Italian Aerospace Research Centre) a developpe un logiciel simulant l'accretion de la glace en regimes sec et humide sur un objet bidimensionnel fixe. L'approche utilisee s'appuie sur les travaux de Lozowski pour les bilans energetiques, sur une etude du comportement du film d'eau, des ruisselets et des gouttes de surface pour le calcul des rugosites et des masses d'eau residuelle, ainsi que sur une methode de bissectrice pour l'evolution de la surface de glace. La contribution du CIRA a ete de fournir le logiciel pour le calcul des ecoulements et de la captation. Le bilan energetique base sur la conservation de l'energie est la sommation de la chaleur latente de fusion, d'evaporation et de sublimation, du rechauffement adiabatique et cinetique, et des pertes de chaleur par convection et conduction, ainsi que de l'evolution thermodynamique de l'eau de son etat initial a son etat final. La densite de la glace, qui a un impact important sur la simulation, est calculee a partir d'une correlation empirique developpee avec les cylindres tournants. En se basant sur les travaux de Al-Khalil et Hansman, le comportement des gouttes en regimes sec et humide a ete decrit analytiquement, ce qui a mene a determiner la hauteur maximale que peuvent atteindre les gouttes avant mouvement. Cette hauteur, appelee hauteur de mouvement, permet de determiner l'etat de l'eau sur la surface (film, ruisselets ou gouttes), ainsi que la hauteur des rugosites lorsque l'eau existe sous forme de gouttes ou de ruisselets. La hauteur de mouvement est determinee par l'equilibre entre les forces de cisaillement, induites par les effets aerodynamiques et gravitationnels evalues pour une goutte non deformee, et la force de cisaillement, induite par la tension de surface et la deformation de la goutte. Elle a ete validee en laboratoire et la precision obtenue pour la partie aerodynamique et gravitationnelle est

  14. Development and evolution of the amniote integument: current landscape and future horizon.

    PubMed

    Chuong, Cheng-Ming; Homberger, Dominique G

    2003-08-15

    This special issue on the development and evolution of the amniote integument begins with a discussion of the adaptations to terrestrial conditions, the acquisition of water-impermeability of the reptilian integument, and the initial formation of filamentous integumentary appendages that prepare the way towards avian flight. Recent feather fossils are reviewed, and a definition of feathers is developed. Hierarchical models are proposed for the formation of complex structures, such as feathers. Molecular signals that alter the phenotype of integumentary appendages at different levels of the hierarchy are presented. Tissue interactions and the roles of keratins in evolution are discussed and linked to their bio-mechanical properties. The role of mechanical forces on patterning is explored. Elaborate extant feather variants are introduced. The regeneration/gene mis-expression protocol for the chicken feather is established as a testable model for the study of biological structures. The adaptations of the mammalian distal limb end organs to terrestrial, arboreal and aquatic conditions are discussed. The development and cycling of hair are reviewed from a molecular perspective. These contributions reveal that the structure and function of diverse integumentary appendages are variations that are superimposed on a common theme, and that their formation is modular, hierarchical and cyclical. They further reveal that these mechanisms can be understood at the molecular level, and that an integrative and organismal approach to studying integumentary appendages is called for. We propose that future research should foster interdisciplinary approaches, pursue understanding at the cellular and molecular level, analyze interactions between the environment and genome, and recognize the contributions of variation in morphogenesis and evolution. Copyright 2003 Wiley-Liss, Inc.

  15. Discrete element modeling of rock deformation, fracture network development and permeability evolution under hydraulic stimulation

    SciTech Connect

    Shouchun Deng; Robert Podgorney; Hai Huang

    2011-02-01

    Key challenges associated with the EGS reservoir development include the ability to reliably predict hydraulic fracturing and the deformation of natural fractures as well as estimating permeability evolution of the fracture network with time. We have developed a physics-based rock deformation and fracture propagation simulator by coupling a discrete element model (DEM) for fracturing with a network flow model. In DEM model, solid rock is represented by a network of discrete elements (often referred as particles) connected by various types of mechanical bonds such as springs, elastic beams or bonds that have more complex properties (such as stress-dependent elastic constants). Fracturing is represented explicitly as broken bonds (microcracks), which form and coalesce into macroscopic fractures when external and internal load is applied. The natural fractures are represented by a series of connected line segments. Mechanical bonds that intersect with such line segments are removed from the DEM model. A network flow model using conjugate lattice to the DEM network is developed and coupled with the DEM. The fluid pressure gradient exerts forces on individual elements of the DEM network, which therefore deforms the mechanical bonds and breaks them if the deformation reaches a prescribed threshold value. Such deformation/fracturing in turn changes the permeability of the flow network, which again changes the evolution of fluid pressure, intimately coupling the two processes. The intimate coupling between fracturing/deformation of fracture networks and fluid flow makes the meso-scale DEM- network flow simulations necessary in order to accurately evaluate the permeability evolution, as these methods have substantial advantages over conventional continuum mechanical models of elastic rock deformation. The challenges that must be overcome to simulate EGS reservoir stimulation, preliminary results, progress to date and near future research directions and opportunities will be

  16. Development and Evolution of the Amniote Integument: Current Landscape and Future Horizon

    PubMed Central

    CHUONG, CHENG-MING; HOMBERGER, DOMINIQUE G.

    2015-01-01

    This special issue on the development and evolution of the amniote integument begins with a discussion of the adaptations to terrestrial conditions, the acquisition of water-impermeability by the reptilian integument, and the initial formation of filamentous integumentary appendages that pave the way towards avian flight. Recent feather fossils are reviewed and a definition of feathers is developed. Hierarchical models are proposed for the formation of complex structures, such as feathers. Molecular signals that alter the phenotype of integumentary appendages at different levels of the hierarchy are presented. Tissue interactions and the roles of keratins in evolution are discussed and linked to their bio-mechanical properties. The role of mechanical forces on patterning is explored. Elaborate extant feather variants are introduced. The regeneration/gene mis-expression protocol for the chicken feather is established as a testable model for the study of biological structures. The adaptations of the mammalian distal limb end organs to terrestrial, arboreal and aquatic conditions are discussed. The development and cycling of hair are reviewed from a molecular perspective. These contributions reveal that the structure and function of diverse integumentary appendages are variations superimposed on a common theme, and that their formation is modular, hierarchical, and cyclical. They further reveal that these mechanisms can be understood at the molecular level, and that an integrative and organismal approach to studying integumentary appendages is needed. We propose that future research should foster interdisciplinary approaches, pursue understanding at the cellular and molecular level, analyze interactions between the environment and genome, and recognize the contributions of variation in morphogenesis and evolution. PMID:12949766

  17. LORICA - A new model for linking landscape and soil profile evolution: Development and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Temme, Arnaud J. A. M.; Vanwalleghem, Tom

    2016-05-01

    Soils and landscapes evolve in tandem. Landscape position is a strong determinant of vertical soil development, which has often been formalized in the catena concept. At the same time, soil properties are strong determinants of geomorphic processes such as overland erosion, landsliding and creep. We present a new soilscape evolution model; LORICA, to study these numerous interactions between soil and landscape development. The model is based on the existing landscape evolution model LAPSUS and the soil formation model MILESD. The model includes similar soil formation processes as MILESD, but the main novelties include the consideration of more layers and the dynamic adaption of the number of layers as a function of the soil profile's heterogeneity. New processes in the landscape evolution component include a negative feedback of vegetation and armouring and particle size selectivity of the erosion-deposition process. In order to quantify these different interactions, we present a full sensitivity analysis of the input parameters. First results show that the model successfully simulates various soil-landscape interactions, leading to outputs where the surface changes in the landscape clearly depend on soil development, and soil changes depend on landscape location. Sensitivity analysis of the model confirms that soil and landscape interact: variables controlling amount and position of fine clay have the largest effect on erosion, and erosion variables control among others the amount of chemical weathering. These results show the importance of particle size distribution, and especially processes controlling the presence of finer clay particles that are easily eroded, both for the resulting landscape form as for the resulting soil profiles. Further research will have to show whether this is specific to the boundary conditions of this study or a general phenomenon.

  18. Evolutionary psychology and evolutionary developmental psychology: understanding the evolution of human behavior and development.

    PubMed

    Hernández Blasi, Carlos; Causey, Kayla

    2010-02-01

    This is an introduction to this special issue on evolutionary psychology (EP) and evolutionary developmental psychology (EDP). We suggest here that, contrary to some common assumptions, mainstream psychology continues to be essentially non Darwinian and that EP and EDP are new approaches that can potentially help us to change this situation. We then present the organization of the special issue (composed of six papers). We conclude that evolution is certainly not the final consideration in psychology, but emphasize its importance as the basis upon which all modern behaviors and development are built.

  19. A software development and evolution model based on decision-making

    NASA Technical Reports Server (NTRS)

    Wild, J. Christian; Dong, Jinghuan; Maly, Kurt

    1991-01-01

    Design is a complex activity whose purpose is to construct an artifact which satisfies a set of constraints and requirements. However the design process is not well understood. The software design and evolution process is the focus of interest, and a three dimensional software development space organized around a decision-making paradigm is presented. An initial instantiation of this model called 3DPM(sub p) which was partly implemented, is presented. Discussion of the use of this model in software reuse and process management is given.

  20. The Soft Touch: Low-Affinity Transcription Factor Binding Sites in Development and Evolution.

    PubMed

    Crocker, Justin; Noon, Ella Preger-Ben; Stern, David L

    2016-01-01

    Transcription factor proteins regulate gene expression by binding to specific DNA regions. Most studies of transcription factor binding sites have focused on the highest affinity sites for each factor. There is abundant evidence, however, that binding sites with a range of affinities, including very low affinities, are critical to gene regulation. Here, we present the theoretical and experimental evidence for the importance of low-affinity sites in gene regulation and development. We also discuss the implications of the widespread use of low-affinity sites in eukaryotic genomes for robustness, precision, specificity, and evolution of gene regulation. © 2016 Elsevier Inc. All rights reserved.

  1. The evolution of nervous system patterning: insights from sea urchin development

    PubMed Central

    Angerer, Lynne M.; Yaguchi, Shunsuke; Angerer, Robert C.; Burke, Robert D.

    2011-01-01

    Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields – the anterior neuroectoderm and the more posterior ciliary band neuroectoderm – during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution. PMID:21828090

  2. The evolution of nervous system patterning: insights from sea urchin development.

    PubMed

    Angerer, Lynne M; Yaguchi, Shunsuke; Angerer, Robert C; Burke, Robert D

    2011-09-01

    Recent studies of the sea urchin embryo have elucidated the mechanisms that localize and pattern its nervous system. These studies have revealed the presence of two overlapping regions of neurogenic potential at the beginning of embryogenesis, each of which becomes progressively restricted by separate, yet linked, signals, including Wnt and subsequently Nodal and BMP. These signals act to specify and localize the embryonic neural fields - the anterior neuroectoderm and the more posterior ciliary band neuroectoderm - during development. Here, we review these conserved nervous system patterning signals and consider how the relationships between them might have changed during deuterostome evolution.

  3. Theories of genetics and evolution and the development of medical entomology in France (1900-1939).

    PubMed

    Gachelin, G; Opinel, A

    2008-12-01

    The development of entomology and medical entomology in France is discussed in the context of the prevalence of Lamarckian ideas concerning heredity and evolution. Lamarckian ideas have greatly influenced research carried out at the Institut Pasteur by Emile Roubaud and more generally in Felix Mesnil's laboratory, as well as research in general entomology at the Museum national d'histoire naturelle. By contrast, it did not influence research and teaching at the Faculté de médecine of Paris or that of physicians more generally including those in overseas Instituts Pasteur, which clearly kept away from theoretical discussion concerning the origin of variations and adaptation in insects of medical interest.

  4. Role of maternal thyroid hormones in the developing neocortex and during human evolution

    PubMed Central

    Stenzel, Denise; Huttner, Wieland B.

    2013-01-01

    The importance of thyroid hormones during brain development has been appreciated for many decades. In humans, low levels of circulating maternal thyroid hormones, e.g., caused by maternal hypothyroidism or lack of iodine in diet, results in a wide spectrum of severe neurological defects, including neurological cretinism characterized by profound neurologic impairment and mental retardation, underlining the importance of the maternal thyroid hormone contribution. In fact, iodine intake, which is essential for thyroid hormone production in the thyroid gland, has been related to the expansion of the brain, associated with the increased cognitive capacities during human evolution. Because thyroid hormones regulate transcriptional activity of target genes via their nuclear thyroid hormone receptors (THRs), even mild and transient changes in maternal thyroid hormone levels can directly affect and alter the gene expression profile, and thus disturb fetal brain development. Here we summarize how thyroid hormones may have influenced human brain evolution through the adaptation to new habitats, concomitant with changes in diet and, therefore, iodine intake. Further, we review the current picture we gained from experimental studies in rodents on the function of maternal thyroid hormones during developmental neurogenesis. We aim to evaluate the effects of maternal thyroid hormone deficiency as well as lack of THRs and transporters on brain development and function, shedding light on the cellular behavior conducted by thyroid hormones. PMID:23882187

  5. Sensitive Periods, Vasotocin-Family Peptides, and the Evolution and Development of Social Behavior

    PubMed Central

    Baran, Nicole M.

    2017-01-01

    Nonapeptides, by modulating the activity of neural circuits in specific social contexts, provide an important mechanism underlying the evolution of diverse behavioral phenotypes across vertebrate taxa. Vasotocin-family nonapeptides, in particular, have been found to be involved in behavioral plasticity and diversity in social behavior, including seasonal variation, sexual dimorphism, and species differences. Although nonapeptides have been the focus of a great deal of research over the last several decades, the vast majority of this work has focused on adults. However, behavioral diversity may also be explained by the ways in which these peptides shape neural circuits and influence social processes during development. In this review, I synthesize comparative work on vasotocin-family peptides during development and classic work on early forms of social learning in developmental psychobiology. I also summarize recent work demonstrating that early life manipulations of the nonapeptide system alter attachment, affiliation, and vocal learning in zebra finches. I thus hypothesize that vasotocin-family peptides are involved in the evolution of social behaviors through their influence on learning during sensitive periods in social development. PMID:28824549

  6. How social evolution theory impacts our understanding of development in the social amoeba Dictyostelium.

    PubMed

    Strassmann, Joan E; Queller, David C

    2011-05-01

    Dictyostelium discoideum has been very useful for elucidating principles of development over the last 50 years, but a key attribute means there is a lot to be learned from a very different intellectual tradition: social evolution. Because Dictyostelium arrives at multicellularity by aggregation instead of through a single-cell bottleneck, the multicellular body could be made up of genetically distinct cells. If they are genetically distinct, natural selection will result in conflict over which cells become fertile spores and which become dead stalk cells. Evidence for this conflict includes unequal representation of two genetically different clones in spores of a chimera, the poison-like differentiation inducing factor (DIF) system that appears to involve some cells forcing others to become stalk, and reduced functionality in migrating chimeras. Understanding how selection operates on chimeras of genetically distinct clones is crucial for a comprehensive view of Dictyostelium multicellularity. In nature, Dictyostelium fruiting bodies are often clonal, or nearly so, meaning development will often be very cooperative. Relatedness levels tell us what benefits must be present for sociality to evolve. Therefore it is important to measure relatedness in nature, show that it has an impact on cooperation in the laboratory, and investigate genes that Dictyostelium uses to discriminate between relatives and non-relatives. Clearly, there is a promising future for research at the interface of development and social evolution in this fascinating group.

  7. Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments.

    PubMed

    Orgeig, Sandra; Morrison, Janna L; Daniels, Christopher B

    2015-12-15

    Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.

  8. Apercu de certains developpements recents des recherches sur l'acquisition du langage (Recent Developments in Language Acquisition Research)

    ERIC Educational Resources Information Center

    Berthoz-Proux, Michelle

    1975-01-01

    The goal of this article is to give a survey of the literature and theoretical trends relevant to language acquisition. Developments in the fields of psychology, psycholinguistics, sociology, sociolinguistics and in various interdisciplinary studies are discussed. (Text is in French.) (CLK)

  9. Molecular development of chondrichthyan claspers and the evolution of copulatory organs

    PubMed Central

    O'Shaughnessy, Katherine L.; Dahn, Randall D.; Cohn, Martin J.

    2015-01-01

    The earliest known vertebrate copulatory organs are claspers, paired penis-like structures that are associated with evolution of internal fertilization and viviparity in Devonian placoderms. Today, only male chondrichthyans possess claspers, which extend from posterior pelvic fins and function as intromittent organs. Here we report that clasper development from pelvic fins of male skates is controlled by hormonal regulation of the Sonic hedgehog (Shh) pathway. We show that Shh signalling is necessary for male clasper development and is sufficient to induce clasper cartilages in females. Androgen receptor (AR) controls the male-specific pattern of Shh in pelvic fins by regulation of Hand2. We identify an androgen response element (ARE) in the Hand2 locus and present biochemical evidence that AR can directly bind the Hand2 ARE. Together, our results suggest that the genetic circuit for appendage development evolved an androgen regulatory input, which prolonged signalling activity and drove clasper skeletogenesis in male fins. PMID:25868783

  10. The tardigrade Hypsibius dujardini, a new model for studying the evolution of development.

    PubMed

    Gabriel, Willow N; McNuff, Robert; Patel, Sapna K; Gregory, T Ryan; Jeck, William R; Jones, Corbin D; Goldstein, Bob

    2007-12-15

    Studying development in diverse taxa can address a central issue in evolutionary biology: how morphological diversity arises through the evolution of developmental mechanisms. Two of the best-studied developmental model organisms, the arthropod Drosophila and the nematode Caenorhabditis elegans, have been found to belong to a single protostome superclade, the Ecdysozoa. This finding suggests that a closely related ecdysozoan phylum could serve as a valuable model for studying how developmental mechanisms evolve in ways that can produce diverse body plans. Tardigrades, also called water bears, make up a phylum of microscopic ecdysozoan animals. Tardigrades share many characteristics with C. elegans and Drosophila that could make them useful laboratory models, but long-term culturing of tardigrades historically has been a challenge, and there have been few studies of tardigrade development. Here, we show that the tardigrade Hypsibius dujardini can be cultured continuously for decades and can be cryopreserved. We report that H. dujardini has a compact genome, a little smaller than that of C. elegans or Drosophila, and that sequence evolution has occurred at a typical rate. H. dujardini has a short generation time, 13-14 days at room temperature. We have found that the embryos of H. dujardini have a stereotyped cleavage pattern with asymmetric cell divisions, nuclear migrations, and cell migrations occurring in reproducible patterns. We present a cell lineage of the early embryo and an embryonic staging series. We expect that these data can serve as a platform for using H. dujardini as a model for studying the evolution of developmental mechanisms.

  11. Transcriptome Analysis of Nautilus and Pygmy Squid Developing Eye Provides Insights in Lens and Eye Evolution

    PubMed Central

    Sousounis, Konstantinos; Ogura, Atsushi; Tsonis, Panagiotis A.

    2013-01-01

    Coleoid cephalopods like squids have a camera-type eye similar to vertebrates. On the other hand, Nautilus (Nautiloids) has a pinhole eye that lacks lens and cornea. Since pygmy squid and Nautilus are closely related species they are excellent model organisms to study eye evolution. Having being able to collect Nautilus embryos, we employed next-generation RNA sequencing using Nautilus and pygmy squid developing eyes. Their transcriptomes were compared and analyzed. Enrichment analysis of Gene Ontology revealed that contigs related to nucleic acid binding were largely up-regulated in squid, while the ones related to metabolic processes and extracellular matrix-related genes were up-regulated in Nautilus. These differences are most likely correlated with the complexity of tissue organization in these species. Moreover, when the analysis focused on the eye-related contigs several interesting patterns emerged. First, contigs from both species related to eye tissue differentiation and morphogenesis as well as to cilia showed best hits with their Human counterparts, while contigs related to rabdomeric photoreceptors showed the best hit with their Drosophila counterparts. This bolsters the idea that eye morphogenesis genes have been generally conserved in evolution, and compliments other studies showing that genes involved in photoreceptor differentiation clearly follow the diversification of invertebrate (rabdomeric) and vertebrate (ciliated) photoreceptors. Interestingly some contigs showed as good a hit with Drosophila and Human homologues in Nautilus and squid samples. One of them, capt/CAP1, is known to be preferentially expressed in Drosophila developing eye and in vertebrate lens. Importantly our analysis also provided evidence of gene duplication and diversification of their function in both species. One of these genes is the Neurofibromatosis 1 (NF1/Nf1), which in mice has been implicated in lens formation, suggesting a hitherto unsuspected role in the evolution

  12. Transcriptome analysis of Nautilus and pygmy squid developing eye provides insights in lens and eye evolution.

    PubMed

    Sousounis, Konstantinos; Ogura, Atsushi; Tsonis, Panagiotis A

    2013-01-01

    Coleoid cephalopods like squids have a camera-type eye similar to vertebrates. On the other hand, Nautilus (Nautiloids) has a pinhole eye that lacks lens and cornea. Since pygmy squid and Nautilus are closely related species they are excellent model organisms to study eye evolution. Having being able to collect Nautilus embryos, we employed next-generation RNA sequencing using Nautilus and pygmy squid developing eyes. Their transcriptomes were compared and analyzed. Enrichment analysis of Gene Ontology revealed that contigs related to nucleic acid binding were largely up-regulated in squid, while the ones related to metabolic processes and extracellular matrix-related genes were up-regulated in Nautilus. These differences are most likely correlated with the complexity of tissue organization in these species. Moreover, when the analysis focused on the eye-related contigs several interesting patterns emerged. First, contigs from both species related to eye tissue differentiation and morphogenesis as well as to cilia showed best hits with their Human counterparts, while contigs related to rabdomeric photoreceptors showed the best hit with their Drosophila counterparts. This bolsters the idea that eye morphogenesis genes have been generally conserved in evolution, and compliments other studies showing that genes involved in photoreceptor differentiation clearly follow the diversification of invertebrate (rabdomeric) and vertebrate (ciliated) photoreceptors. Interestingly some contigs showed as good a hit with Drosophila and Human homologues in Nautilus and squid samples. One of them, capt/CAP1, is known to be preferentially expressed in Drosophila developing eye and in vertebrate lens. Importantly our analysis also provided evidence of gene duplication and diversification of their function in both species. One of these genes is the Neurofibromatosis 1 (NF1/Nf1), which in mice has been implicated in lens formation, suggesting a hitherto unsuspected role in the evolution

  13. Maladie des vibrations

    PubMed Central

    Shen, Shixin (Cindy); House, Ronald A.

    2017-01-01

    Résumé Objectif Permettre aux médecins de famille de comprendre l’épidémiologie, la pathogenèse, les symptômes, le diagnostic et la prise en charge de la maladie des vibrations, une maladie professionnelle importante et courante au Canada. Sources d’information Une recherche a été effectuée sur MEDLINE afin de relever les recherches et comptes rendus portant sur la maladie des vibrations. Une recherche a été effectuée sur Google dans le but d’obtenir la littérature grise qui convient au contexte canadien. D’autres références ont été tirées des articles relevés. Message principal La maladie des vibrations est une maladie professionnelle répandue touchant les travailleurs de diverses industries qui utilisent des outils vibrants. La maladie est cependant sous-diagnostiquée au Canada. Elle compte 3 éléments : vasculaire, sous la forme d’un phénomène de Raynaud secondaire; neurosensoriel; et musculosquelettique. Aux stades les plus avancés, la maladie des vibrations entraîne une invalidité importante et une piètre qualité de vie. Son diagnostic exige une anamnèse minutieuse, en particulier des antécédents professionnels, un examen physique, des analyses de laboratoire afin d’éliminer les autres diagnostics, et la recommandation en médecine du travail aux fins d’investigations plus poussées. La prise en charge consiste à réduire l’exposition aux vibrations, éviter les températures froides, abandonner le tabac et administrer des médicaments. Conclusion Pour assurer un diagnostic rapide de la maladie des vibrations et améliorer le pronostic et la qualité de vie, les médecins de famille devraient connaître cette maladie professionnelle courante, et pouvoir obtenir les détails pertinents durant l’anamnèse, recommander les patients aux cliniques de médecine du travail et débuter les demandes d’indemnisation de manière appropriée. PMID:28292812

  14. Effets perturbateurs endocriniens des pesticides organochlores.

    PubMed

    Charlier, C; Plomteux, G

    2002-01-01

    Xenoestrogens such organochlorine pesticides are known to induce changes in reproductive development, function or behaviour in wildlife. Because these compounds are able to modify the estrogens metabolism, or to compete with estradiol for binding to the estrogen receptor, it may be possible that these products affect the risk of developing impaired fertility, precocious puberty or some kinds of cancer in man. Le plus ancien récit de lutte contre la pollution remonte à une légende indienne racontant que la divinité Sing-bonga était incommodée par les émanations des fours dans lesquels les Asuras fondaient leurs métaux (1). Evidemment depuis, la problématique n-a cessé de s-accroître et la contamination de la Terre par de nombreux polluants est devenue aujourd-hui un problème majeur de notre Société. La protection de notre environnement est une question capitale qui doit être respectée malgré la pression économique actuelle et qui ne cessera de croître au cours des prochaines années même si l-identification objective et indiscutable de ce qui est essentiel - donc devant être prioritairement garanti sur la planète - est difficile à cerner (2). « Un oiseau en mauvais état ne pond pas de bons oeufs » disait un proverbe grec. Mais ce n-est qu-à partir de la seconde moitié du XXème siècle que les toxicologues ont commencé à identifier les effets qu-avaient entraînés à l-échelle mondiale les pollutions émises aux XIXème siècle sur la faune sauvage et sur le cheptel (3). L-histoire contemporaine des pesticides industriels commence vers 1874 (synthèse des organochlorés) et se poursuit tout au long de ces 2 siècles en passant par la synthèse des organophosphorés (1950), des carbamates (1970) et des pyréthroïdes (1975) (4). Le dichlorodiphényltrichloroéthane (DDT) a été synthétisé pour la première fois par un étudiant en cours de préparation de sa thèse de doctorat : Othmer Zeidler. La production, reprise par les

  15. Tracing the Evolution of Educational Development through the POD Network's Institute for New Faculty Developers

    ERIC Educational Resources Information Center

    DiPietro, Michele

    2014-01-01

    Educational development is a unique professional field in that it is not defined by content taught in a single degree that qualifies individuals to be in it. The resulting heterogeneity in newcomers' knowledge and skills is addressed in different ways by different national networks. Since 1997, the POD Network has held a biennial Institute for New…

  16. Tracing the Evolution of Educational Development through the POD Network's Institute for New Faculty Developers

    ERIC Educational Resources Information Center

    DiPietro, Michele

    2014-01-01

    Educational development is a unique professional field in that it is not defined by content taught in a single degree that qualifies individuals to be in it. The resulting heterogeneity in newcomers' knowledge and skills is addressed in different ways by different national networks. Since 1997, the POD Network has held a biennial Institute for New…

  17. Development of a cyber physical apparatus for investigating fluid structure interaction on leading edge vortex evolution

    NASA Astrophysics Data System (ADS)

    Raghu Gowda, Belagumba Venkatachalaiah

    This dissertation examines how simple structural compliance impacts a specific transient vortex phenomenon that occurs on high angle of attack lifting surfaces termed dynamic stall. In many Fluid structure interaction (FSI) research efforts, a purely physical or purely computational approach is taken. In this work a low cost cyber-physical (CPFD) system is designed and developed for representing the FSI in the leading edge vortex (LEV) development problem. The leading edge compliance appears to be favorable in a specific spring constant range for a given wing. When the leading edge compliance prescribed via CPFD system is too low compared with the moment due to dynamic pressure or fluid unsteady effect, the LEV behavior is similar to that of a rigid wing system. When the leading edge compliance is too high, excessive compliance is introduced into the wing system and the leading edge vortex evolution is affected by the large change in wing angle. At moderate leading edge compliance, a balance appears to be achieved in which the leading edge vorticity shedding rate supports the long term evolution of the leading edge vortex. Further investigation is required to determine specific parameters governing these leading edge compliance ranges.

  18. Convective scale interaction: Arc cloud lines and the development and evolution of deep convection

    NASA Technical Reports Server (NTRS)

    Purdom, James Francis Whitehurst

    1986-01-01

    Information is used from satellite data and research aircraft data to provide new insights concerning the mesoscale development and evolution of deep convection in an atmosphere typified by weak synoptic-scale forcing. The importance of convective scale interaction in the development and evolution of deep convection is examined. This interaction is shown to manifest itself as the merger and intersection of thunderstorm outflow boundaries (arc cloud lines) with other convective lines, areas or boundaries. Using geostationary satellite visible and infrared data convective scale interaction is shown to be responsible for over 85 percent of the intense convection over the southeast U.S. by late afternoon, and a majority of that area's afternoon rainfall. The aircraft observations provided valuable information concerning critically important regions of the arc cloud line: (1) the cool outflow region, (2) the density surge line interface region; and (3) the sub-cloud region above the surge line. The observations when analyzed with rapid scan satellite data, helped in defining the arc cloud line's life cycle as 3 evolving stages.

  19. Comparative transcriptomic analysis of the evolution and development of flower size in Saltugilia (Polemoniaceae).

    PubMed

    Landis, Jacob B; Soltis, Douglas E; Soltis, Pamela S

    2017-06-23

    Flower size varies dramatically across angiosperms, representing innovations over the course of >130 million years of evolution and contributing substantially to relationships with pollinators. However, the genetic underpinning of flower size is not well understood. Saltugilia (Polemoniaceae) provides an excellent non-model system for extending the genetic study of flower size to interspecific differences that coincide with variation in pollinators. Using targeted gene capture methods, we infer phylogenetic relationships among all members of Saltugilia to provide a framework for investigating the genetic control of flower size differences via RNA-Seq de novo assembly. Nuclear concatenation and species tree inference methods provide congruent topologies. The inferred evolutionary trajectory of flower size is from small flowers to larger flowers. We identified 4 to 10,368 transcripts that are differentially expressed during flower development, with many unigenes associated with cell wall modification and components of the auxin and gibberellin pathways. Saltugilia is an excellent model for investigating covarying floral and pollinator evolution. Four candidate genes from model systems (BIG BROTHER, BIG PETAL, GASA, and LONGIFOLIA) show differential expression during development of flowers in Saltugilia, and four other genes (FLOWERING-PROMOTING FACTOR 1, PECTINESTERASE, POLYGALACTURONASE, and SUCROSE SYNTHASE) fit into hypothesized organ size pathways. Together, these gene sets provide a strong foundation for future functional studies to determine their roles in specifying interspecific differences in flower size.

  20. Development and evaluation of an online CO(2) evolution test and a multicomponent biodegradation test system.

    PubMed

    Strotmann, Uwe; Reuschenbach, Peter; Schwarz, Helmut; Pagga, Udo

    2004-08-01

    Well-established biodegradation tests use biogenously evolved carbon dioxide (CO(2)) as an analytical parameter to determine the ultimate biodegradability of substances. A newly developed analytical technique based on the continuous online measurement of conductivity showed its suitability over other techniques. It could be demonstrated that the method met all criteria of established biodegradation tests, gave continuous biodegradation curves, and was more reliable than other tests. In parallel experiments, only small variations in the biodegradation pattern occurred. When comparing the new online CO(2) method with existing CO(2) evolution tests, growth rates and lag periods were similar and only the final degree of biodegradation of aniline was slightly lower. A further test development was the unification and parallel measurement of all three important summary parameters for biodegradation--i.e., CO(2) evolution, determination of the biochemical oxygen demand (BOD), and removal of dissolved organic carbon (DOC)--in a multicomponent biodegradation test system (MCBTS). The practicability of this test method was demonstrated with aniline. This test system had advantages for poorly water-soluble and highly volatile compounds and allowed the determination of the carbon fraction integrated into biomass (heterotrophic yield). The integrated online measurements of CO(2) and BOD systems produced continuous degradation curves, which better met the stringent criteria of ready biodegradability (60% biodegradation in a 10-day window). Furthermore the data could be used to calculate maximal growth rates for the modeling of biodegradation processes.

  1. Development and Evaluation of an Online CO2 Evolution Test and a Multicomponent Biodegradation Test System

    PubMed Central

    Strotmann, Uwe; Reuschenbach, Peter; Schwarz, Helmut; Pagga, Udo

    2004-01-01

    Well-established biodegradation tests use biogenously evolved carbon dioxide (CO2) as an analytical parameter to determine the ultimate biodegradability of substances. A newly developed analytical technique based on the continuous online measurement of conductivity showed its suitability over other techniques. It could be demonstrated that the method met all criteria of established biodegradation tests, gave continuous biodegradation curves, and was more reliable than other tests. In parallel experiments, only small variations in the biodegradation pattern occurred. When comparing the new online CO2 method with existing CO2 evolution tests, growth rates and lag periods were similar and only the final degree of biodegradation of aniline was slightly lower. A further test development was the unification and parallel measurement of all three important summary parameters for biodegradation—i.e., CO2 evolution, determination of the biochemical oxygen demand (BOD), and removal of dissolved organic carbon (DOC)—in a multicomponent biodegradation test system (MCBTS). The practicability of this test method was demonstrated with aniline. This test system had advantages for poorly water-soluble and highly volatile compounds and allowed the determination of the carbon fraction integrated into biomass (heterotrophic yield). The integrated online measurements of CO2 and BOD systems produced continuous degradation curves, which better met the stringent criteria of ready biodegradability (60% biodegradation in a 10-day window). Furthermore the data could be used to calculate maximal growth rates for the modeling of biodegradation processes. PMID:15294794

  2. Microbes in the coral holobiont: partners through evolution, development, and ecological interactions

    PubMed Central

    Thompson, Janelle R.; Rivera, Hanny E.; Closek, Collin J.; Medina, Mónica

    2015-01-01

    In the last two decades, genetic and genomic studies have revealed the astonishing diversity and ubiquity of microorganisms. Emergence and expansion of the human microbiome project has reshaped our thinking about how microbes control host health—not only as pathogens, but also as symbionts. In coral reef environments, scientists have begun to examine the role that microorganisms play in coral life history. Herein, we review the current literature on coral-microbe interactions within the context of their role in evolution, development, and ecology. We ask the following questions, first posed by McFall-Ngai et al. (2013) in their review of animal evolution, with specific attention to how coral-microbial interactions may be affected under future environmental conditions: (1) How do corals and their microbiome affect each other's genomes? (2) How does coral development depend on microbial partners? (3) How is homeostasis maintained between corals and their microbial symbionts? (4) How can ecological approaches deepen our understanding of the multiple levels of coral-microbial interactions? Elucidating the role that microorganisms play in the structure and function of the holobiont is essential for understanding how corals maintain homeostasis and acclimate to changing environmental conditions. PMID:25621279

  3. Spin evolution of neutron stars: Nonlinear development of the r-mode instability

    NASA Astrophysics Data System (ADS)

    Bondarescu, Ruxandra

    2008-08-01

    Rotating neutron stars have modes that are driven unstable by gravitational radiation reaction, principally the r-mode, a Rossby wave with n = 3, m = 2, and hence large gravitational radiation reaction. Here n and m label the Legendre functions associated with the mode. The r-mode instability is active when gravitational driving dominates viscous dissipation. It has been suggested that this instability can (1) set the largest angular frequency of rotation of accreting neutron stars and (2) significantly spin down newborn neutron stars preventing them from reaching millisecond periods. Both the maximum frequency that neutron stars can reach and the frequency to which newborn stars can be spun down to in the first few years after formation depend on the neutron star composition via viscous dissipation and neutrino cooling. The nonlinear development of the instability plays a very important role in determining how the saturation process works, and also illustrates how instabilities can saturate at low amplitudes as a consequence of nearly resonant excitation of other modes. We model the nonlinear interactions between modes together with basic neutron star physics including viscous heating, cooling and spin evolution of the star. The nonlinear effects are included via three-mode couplings. We show that in most scenarios one triplet of modes is sufficient to stop the growth of the instability. To explore possible nonlinear behaviors we parameterize uncertain properties of neutron stars such as the superfluid transition temperature and the rate at which the star cools via neutrino emission. The average evolution of the mode amplitudes can usually be approximated by quasi-stationary states that change slowly with spin frequency and temperature and can be determined algebraically. The spin and temperature evolution follow or oscillate around trajectories along sequences of quasi-stationary states. In the Low Mass X-ray Binary (LMXB) case (Chapter 2), after some brief

  4. Systematic Approach to the Development, Evolution, and Effectiveness of Integrated Product Development Teams (IPDTs)

    SciTech Connect

    Margie Jeffs; R. Douglas Hamelin

    2011-06-01

    Integrated Product Development Teams (IPDT) are a key component of any systems engineering (SE) application, but since they are formed primarily from technical considerations, many IPDTs are far less productive than they otherwise could be. By recognizing specific personality types and skill sets, a random group of 'technical' individuals can be structured to become a highly effective team capable of delivering much more than the sum of its members.

  5. [The influence of Janicki cercomer theory on the development of platyhelminthes systematics and evolution investigations].

    PubMed

    Pojmańska, Teresa

    2005-01-01

    The aim of this article was to present the development of ideas about the provenience of parasitic helminths and the phylogenetical relationships within this taxon, since the publication of the "cercomer theory" just to nowadays. The following essentials of the Janicki theory are outlined: main differences between free-living Turbellaria and parasitic platyhelminths (ciliated epithelium in Turbellaria versus unciliated surface in the others); universality of the cercomer presence in Monogenea, Digenea and Cestoda; evolutionary changes in the morphology and function of the cercomer; homology of the caudal appendices of all parasitic helminths; the subsequent evolution of parasitic platyhelminthes from the ancestor to Monogena, Digenea and Cestoda; proposition to establish a new common taxon--Cercomerophora--for these three groups. In this background the evolution of evolutionary ideas is reviewed, divided into two periods: up to the eighties of the XX century, and up to date. The first period can be characterised by the criticism of some points of the "cercomer theory" and formulation of some new hypotheses; these are those of Fuhrmann, Bychovsky, Llewellyn, Price and Malmberg, which: questioned the homology of the cercarial tail with the caudal appendices of Monogenea and Cestoda; rejected Digenea from the common group; established the common taxon--Cercomeromorpha--comprising only Monogenea and Cestoda; opposed the idea of radial evolution of three main groups of Platyhelmithes (Turbellaria, Digenea and Cercomeromorpha) to the idea of subsequent evolution presented by Janicki. The differences between these last hypotheses are also underlined, arising mainly from the different ideas on the importance of particular features as the evolutionary indicators of affinities between and within the taxons. As to the hypotheses dealing with the evolution of particular groups of parasitic platyhelminths formulated at the same period, the publications of Freeman and Jarecka

  6. Transcription Factor Networks Directing the Development, Function, and Evolution of Innate Lymphoid Effectors

    PubMed Central

    Kang, Joonsoo; Malhotra, Nidhi

    2015-01-01

    Mammalian lymphoid immunity is mediated by fast and slow responders to pathogens. Fast innate lymphocytes are active within hours after infections in mucosal tissues. Slow adaptive lymphocytes are conventional T and B cells with clonal antigen receptors that function days after pathogen exposure. A transcription factor (TF) regulatory network guiding early T cell development is at the core of effector function diversification in all innate lymphocytes, and the kinetics of immune responses is set by developmental programming. Operational units within the innate lymphoid system are not classified by the types of pathogen-sensing machineries but rather by discrete effector functions programmed by regulatory TF networks. Based on the evolutionary history of TFs of the regulatory networks, fast effectors likely arose earlier in the evolution of animals to fortify body barriers, and in mammals they often develop in fetal ontogeny prior to the establishment of fully competent adaptive immunity. PMID:25650177

  7. Transcription factor networks directing the development, function, and evolution of innate lymphoid effectors.

    PubMed

    Kang, Joonsoo; Malhotra, Nidhi

    2015-01-01

    Mammalian lymphoid immunity is mediated by fast and slow responders to pathogens. Fast innate lymphocytes are active within hours after infections in mucosal tissues. Slow adaptive lymphocytes are conventional T and B cells with clonal antigen receptors that function days after pathogen exposure. A transcription factor (TF) regulatory network guiding early T cell development is at the core of effector function diversification in all innate lymphocytes, and the kinetics of immune responses is set by developmental programming. Operational units within the innate lymphoid system are not classified by the types of pathogen-sensing machineries but rather by discrete effector functions programmed by regulatory TF networks. Based on the evolutionary history of TFs of the regulatory networks, fast effectors likely arose earlier in the evolution of animals to fortify body barriers, and in mammals they often develop in fetal ontogeny prior to the establishment of fully competent adaptive immunity.

  8. Evolution of Psychosomatic Diagnosis in DSM. Historical Perspectives and New Development for Internists.

    PubMed

    Moldovan, Ramona; Radu, Mădălia; Băban, Adriana; Dumitraşcu, D L

    2015-01-01

    The so-called "Psychosomatic symptoms" represent a real challenge for internists. These have often been described as non-specific, non-organic, functional, dysfunctional or idiopathic. These "diagnostic puzzles" are obviously difficult to treat. Psychosomatic symptoms have been categorized as hysteria, psychogenic, psychosomatic, conversion, somatization and somatoform disorder. It is only when modern classificatory systems such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Classification of Diseases (ICD) were developed that research was stimulated and new clinical developments became much stronger than any other time. The current paper is aimed at briefly presenting the evolution of psychosomatic symptoms in DSM while pointing out the major milestones as well as the benefits and challenges along the way. We discuss the perspectives open with the advent of the 5th edition the DSM-V.

  9. Evolution of the IBDM Structural Latch Development into a Generic Simplified Design

    NASA Technical Reports Server (NTRS)

    DeVriendt, K.; Dittmer, H.; Vrancken, D.; Urmston, P.; Gracia, O.

    2010-01-01

    This paper presents the evolution in the development of the structural latch for the International Berthing Docking Mechanism (IBDM, see Figure 1). It reports on the lessons learned since completion of the test program on the engineering development unit of the first generation latching system in 2007. The initial latch design has been through a second generation concept in 2008, and now evolved into a third generation of this mechanism. Functional and structural testing on the latest latch hardware has recently been completed with good results. The IBDM latching system will provide the structural connection between two mated space vehicles after berthing or docking. The mechanism guarantees that the interface seals become compressed to form a leak-tight pressure system that creates a passageway for the astronauts.

  10. Des Vents et des Jets Astrophysiques

    NASA Astrophysics Data System (ADS)

    Sauty, C.

    well expected result from the theory. Although, collimation may be conical, paraboloidal or cylindrical (Part 4), cylindrical collimation is the more likely to occur. The shape of outflows may then be used as a tool to predict physical conditions on the flows or on their source. L'éjection continue de plasma autour d'objets massifs est un phénomène largement répandu en astrophysique, que ce soit sous la forme du vent solaire, de vents stellaires, de jets d'étoiles en formation, de jets stellaires autour d'objets compacts ou de jets extra-galactiques. Cette zoologie diversifiée fait pourtant l'objet d'un commun effort de modélisation. Le but de cette revue est d'abord de présenter qualitativement le développement, depuis leur origine, des diverses théories de vents (Partie 1) et l'inter disciplinarité dans ce domaine. Il s'agit d'une énumération, plus ou moins exhaustive, des idées proposées pour expliquer l'accélération et la morphologie des vents et des jets, accompagnée d'une présentation sommaire des aspects observationnels. Cette partie s'abstient de tout aspect faisant appel au formalisme mathématique. Ces écoulements peuvent être décrits, au moins partiellement, en résolvant les équations magnétohydrodynamiques, axisymétriques et stationnaires. Ce formalisme, à la base de la plupart des théories, est exposé dans la Partie 2. Il permet d'introduire quantitativement les intégrales premières qu'un tel système possède. Ces dernières sont amenées à jouer un rôle important dans la compréhension des phénomènes d'accélération ou de collimation, en particulier le taux de perte de masse, le taux de perte de moment angulaire ou l'énergie du rotateur magnétique. La difficulté de modélisation réside dans l'existence de points critiques, propres aux équations non linéaires, qu'il faut franchir. La nature physique et la localisation de ces points critiques fait l'objet d'un débat important car ils sont la clef de voute de la r

  11. Contribution of genoarchitecture to understanding forebrain evolution and development, with particular emphasis on the amygdala.

    PubMed

    Medina, Loreta; Bupesh, Munisamy; Abellán, Antonio

    2011-01-01

    The amygdala is a forebrain center involved in functions and behaviors that are critical for survival (such as control of the neuroendocrine system and homeostasis, and reproduction and fear/escape responses) and in cognitive functions such as attention and emotional learning. In mammals, the amygdala is highly complex, with multiple subdivisions, neuronal subtypes, and connections, making it very difficult to understand its functional organization and evolutionary origin. Since evolution is the consequence of changes that occurred in development, herein we review developmental data based on genoarchitecture and fate mapping in mammals (in the mouse model) and other vertebrates in order to identify its basic components and embryonic origin in different species and understand how they changed in evolution. In all tetrapods studied, the amygdala includes at least 4 components: (1) a ventral pallial part, characterized by expression of Lhx2 and Lhx9, that includes part of the basal amygdalar complex in mammals and a caudal part of the dorsal ventricular ridge in sauropsids and also produces a cell subpopulation of the medial amygdala; (2) a striatal part, characterized by expression of Pax6 and/or Islet1, which includes the central amygdala in different species; (3) a pallidal part, characterized by expression of Nkx2.1 and, in amniotes, Lhx6, which includes part of the medial amygdala, and (4) a hypothalamic part (derived from the supraoptoparaventricular domain or SPV), characterized by Otp and/or Lhx5 expression, which produces an important subpopulation of cells of the medial extended amygdala (medial amygdala and/or medial bed nucleus of the stria terminalis). Importantly, the size of the SPV domain increases upon reduction or lack of Nkx2.1 function in the hypothalamus. It appears that Nkx2.1 expression was downregulated in the alar hypothalamus during evolution to mammals, which may have produced an enlargement of SPV and the amygdalar cell subpopulation

  12. Evolution of the Arden Syntax: Key Technical Issues from the Standards Development Organization Perspective.

    PubMed

    Jenders, Robert A; Adlassnig, Klaus-Peter; Fehre, Karsten; Haug, Peter

    2016-08-11

    The initial version of the Arden Syntax for Medical Logic Systems was created to facilitate explicit representation of medical logic in a form that could be easily composed and interpreted by clinical experts in order to facilitate clinical decision support (CDS). Because of demand from knowledge engineers and programmers to improve functionality related to complex use cases, the Arden Syntax evolved to include features typical of general programming languages but that were specialized to meet the needs of the clinical decision support environment, including integration into a clinical information system architecture. Review of the design history and evolution of the Arden Syntax by workers who participated in this evolution from the perspective of the standards development organization (SDO). In order to meet user needs, a variety of features were successively incorporated in Arden Syntax. These can be grouped in several classes of change, including control flow, data structures, operators and external links. These changes included expansion of operators to manipulate lists and strings; a formalism for structured output; iteration constructs; user-defined objects and operators to manipulate them; features to support international use and output in different natural languages; additional control features; fuzzy logic formalisms; and mapping of the entire syntax to XML. The history and rationale of this evolution are summarized. In response to user demand and to reflect its growing role in clinical decision support, the Arden Syntax has evolved to include a number of powerful features. These depart somewhat from the original vision of the syntax as simple and easily understandable but from the SDO perspective increase the utility of this standard for implementation of CDS. Backwards compatibility has been maintained, allowing continued support of the earlier, simpler decision support models. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. MicroRNA evolution, expression, and function during short germband development in Tribolium castaneum.

    PubMed

    Ninova, Maria; Ronshaugen, Matthew; Griffiths-Jones, Sam

    2016-01-01

    MicroRNAs are well-established players in the development of multicellular animals. Most of our understanding of microRNA function in arthropod development comes from studies in Drosophila. Despite their advantages as model systems, the long germband embryogenesis of fruit flies is an evolutionary derived state restricted to several holometabolous insect lineages. MicroRNA evolution and expression across development in animals exhibiting the ancestral and more widespread short germband mode of embryogenesis has not been characterized. We sequenced small RNA libraries of oocytes and successive intervals covering the embryonic development of the short germband model organism, Tribolium castaneum. We analyzed the evolution and temporal expression of the microRNA complement and sequenced libraries of total RNA to investigate the relationships with microRNA target expression. We show microRNA maternal loading and sequence-specific 3' end nontemplate oligoadenylation of maternally deposited microRNAs that is conserved between Tribolium and Drosophila. We further uncover large clusters encoding multiple paralogs from several Tribolium-specific microRNA families expressed during a narrow interval of time immediately after the activation of zygotic transcription. These novel microRNAs, together with several early expressed conserved microRNAs, target a significant number of maternally deposited transcripts. Comparison with Drosophila shows that microRNA-mediated maternal transcript targeting is a conserved process in insects, but the number and sequences of microRNAs involved have diverged. The expression of fast-evolving and species-specific microRNAs in the early blastoderm of T. castaneum is consistent with previous findings in Drosophila and shows that the unique permissiveness for microRNA innovation at this stage is a conserved phenomenon.

  14. Development of a coupled Thermo-Hydro model and study of the evolution of a river-valley-talik system in the context of climate change

    NASA Astrophysics Data System (ADS)

    Regnier, Damien; Grenier, Christophe; Davy, Philippe; Benabderrahmane, Hakim

    2010-05-01

    Boreal regions have been subject to recent and intensive studies within the field of the impact of climate change. A vast number of the modeling approaches correspond to large scale modeling firstly oriented to thermal field and permafrost evolution. We consider the evolution of smaller scale units of the landscape, in particular here the river-valley unit. In cold environments, we know that some rivers have at their bottoms a talik or a non frozen zone. Such systems have been poorly studied until now should it be as such or in relation with their surroundings, as major thermal conductors potentially impacting a larger portion of a region. The present work is part of a more global study implying the Lena river (Siberia) evolution under climate change in collaboration with the IDES laboratory (Interaction et Dynamique des Environnements de Surface at Orsay University, see e.g. Costard and Gautier, 2007) where the study of the system involves a threefold approach including in situ field work (near Yakutsk), experimental modeling (in a cold room at Orsay University) and numerical modeling. The river-valley system is a case where thermal evolution is coupled with water flow (hydrology and hydrogeology in the talik). The thermal field is impacted by and modifies the water flow conditions when freezing. We first present the development of our numerical simulation procedure. A novel 2D-3D simulation approach was developed in the Cast3M code (www-cast3m.cea.fr/cast3m) with a mixed hybrid finite element approach. It couples Darcy equations for flow (permeability depending on temperature) with heat transfer equations (conductive, advective and phase change process) with a Picard iterations algorithm for coupling. Then we present the validation of the code against 1D analytical solutions (Stefan problem) and 2D cases issued from the literature (McKenzie et al. 2007, Bense et al. 2009). We finally study by means of numeric simulations the installation of permafrost in an

  15. Evolution of cranial development and the role of neural crest: insights from amphibians

    PubMed Central

    Hanken, James; Gross, Joshua B

    2005-01-01

    Contemporary studies of vertebrate cranial development document the essential role played by the embryonic neural crest as both a source of adult tissues and a locus of cranial form and patterning. Yet corresponding and basic features of cranial evolution, such as the extent of conservation vs. variation among species in the contribution of the neural crest to specific structures, remain to be adequately resolved. Investigation of these features requires comparable data from species that are both phylogenetically appropriate and taxonomically diverse. One key group are amphibians, which are uniquely able to inform our understanding of the ancestral patterns of ontogeny in fishes and tetrapods as well as the evolution of presumably derived patterns reported for amniotes. Recent data support the hypothesis that a prominent contribution of the neural crest to cranial skeletal and muscular connective tissues is a fundamental property that evolved early in vertebrate history and is retained in living forms. The contribution of the neural crest to skull bones appears to be more evolutionarily labile than that of cartilages, although significance of the limited comparative data is difficult to establish at present. Results underline the importance of accurate and reliable homology assessments for evaluating the contrasting patterns of derivation reported for the three principal tetrapod models: mouse, chicken and frog. PMID:16313386

  16. Nitric oxide signaling in the development and evolution of language and cognitive circuits.

    PubMed

    Funk, Owen H; Kwan, Kenneth Y

    2014-09-01

    The neocortex underlies not only remarkable motor and sensory capabilities, but also some of our most distinctly human cognitive functions. The emergence of these higher functions during evolution was accompanied by structural changes in the neocortex, including the acquisition of areal specializations such as Broca's speech and language area. The study of these evolutionary mechanisms, which likely involve species-dependent gene expression and function, represents a substantial challenge. These species differences, however, may represent valuable opportunities to understand the molecular underpinnings of neocortical evolution. Here, we discuss nitric oxide signaling as a candidate mechanism in the assembly of neocortical circuits underlying language and higher cognitive functions. This hypothesis was based on the highly specific mid-fetal pattern of nitric oxide synthase 1 (NOS1, previously nNOS) expression in the pyramidal (projection) neurons of two human neocortical areas respectively involved in speech and language, and higher cognition; the frontal operculum (FOp) and the anterior cingulate cortex (ACC). This expression is transiently present during mid-gestation, suggesting that NOS1 may be involved in the development of these areas and the assembly of their neural circuits. As no other gene product is known to exhibit such exquisite spatiotemporal expression, NOS1 represents a remarkable candidate for these functions. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  17. Cerebral cortex development: From progenitors patterning to neocortical size during evolution.

    PubMed

    Pierani, Alessandra; Wassef, Marion

    2009-04-01

    The central nervous system is composed of thousands of distinct neurons that are assembled in a highly organized structure. In order to form functional neuronal networks, distinct classes of cells have to be generated in a precise number, in a spatial and temporal hierarchy and to be positioned at specific coordinates. An exquisite coordination of appropriate growth of competent territories and their patterning is required for regionalization and neurogenesis along both the anterior-posterior and dorso-ventral axis of the developing nervous system. The neocortex represents the brain territory that has undergone a major increase in its relative size during the course of mammalian evolution. In this review we will discuss how the fine tuning of growth and cell fate patterning plays a crucial role in the achievement of the final size of central nervous system structures and how divergence might have contributed to the surface increase of the cerebral cortex in mammals. In particular, we will describe how lack of precision might have been instrumental to neocortical evolution.

  18. Evolution of cranial development and the role of neural crest: insights from amphibians.

    PubMed

    Hanken, James; Gross, Joshua B

    2005-11-01

    Contemporary studies of vertebrate cranial development document the essential role played by the embryonic neural crest as both a source of adult tissues and a locus of cranial form and patterning. Yet corresponding and basic features of cranial evolution, such as the extent of conservation vs. variation among species in the contribution of the neural crest to specific structures, remain to be adequately resolved. Investigation of these features requires comparable data from species that are both phylogenetically appropriate and taxonomically diverse. One key group are amphibians, which are uniquely able to inform our understanding of the ancestral patterns of ontogeny in fishes and tetrapods as well as the evolution of presumably derived patterns reported for amniotes. Recent data support the hypothesis that a prominent contribution of the neural crest to cranial skeletal and muscular connective tissues is a fundamental property that evolved early in vertebrate history and is retained in living forms. The contribution of the neural crest to skull bones appears to be more evolutionarily labile than that of cartilages, although significance of the limited comparative data is difficult to establish at present. Results underline the importance of accurate and reliable homology assessments for evaluating the contrasting patterns of derivation reported for the three principal tetrapod models: mouse, chicken and frog.

  19. Maternal-fetal unit interactions and eutherian neocortical development and evolution

    PubMed Central

    Montiel, Juan F.; Kaune, Heidy; Maliqueo, Manuel

    2013-01-01

    The conserved brain design that primates inherited from early mammals differs from the variable adult brain size and species-specific brain dominances observed across mammals. This variability relies on the emergence of specialized cerebral cortical regions and sub-compartments, triggering an increase in brain size, areal interconnectivity and histological complexity that ultimately lies on the activation of developmental programs. Structural placental features are not well correlated with brain enlargement; however, several endocrine pathways could be tuned with the activation of neuronal progenitors in the proliferative neocortical compartments. In this article, we reviewed some mechanisms of eutherians maternal–fetal unit interactions associated with brain development and evolution. We propose a hypothesis of brain evolution where proliferative compartments in primates become activated by “non-classical” endocrine placental signals participating in different steps of corticogenesis. Changes in the inner placental structure, along with placenta endocrine stimuli over the cortical proliferative activity would allow mammalian brain enlargement with a concomitant shorter gestation span, as an evolutionary strategy to escape from parent-offspring conflict. PMID:23882189

  20. Non-invasive oxidative stress markers for liver fibrosis development in the evolution of toxic hepatitis.

    PubMed

    Clichici, Simona; Catoi, C; Mocan, T; Filip, A; Login, C; Nagy, A; Daicoviciu, D; Decea, N; Gherman, C; Moldovan, R; Muresan, Adriana

    2011-06-01

    Oxidative stress is related to the liver fibrosis, anticipating the hepatic stellate cells' (HSC) activation. Our aim was to correlate oxidative stress markers with the histological liver alterations in order to identify predictive, noninvasive parameters of fibrosis progression in the evolution of toxic hepatitis.CCl4 in sunflower oil was administered to rats intragastrically, twice a week. After 2, 3, 4 and 8 weeks of treatment, plasma levels of malondialdehyde (MDA), protein carbonyls (PC), hydrogen donor capacity (HD), sulfhydryl groups (SH), and glutathione (GSH) were measured and histological examination of the liver slides was performed. Dynamics of histological disorders was assessed by The Knodell score. Significant elevation of inflammation grade was obtained after the second week of the experiment only (p=0.001), while fibrosis started to become significant (p=0.001) after 1 month of CCl4 administration. Between plasma MDA and liver fibrosis development a good correlation was obtained (r=0.877, p=0.05). Correlation between PC dynamics and liver alterations was marginally significant for inflammation grade (r=0.756, p=0.138). HD evolution revealed a marginally inverse correlation with inflammation grade (r=-0.794, p=0.108). No correlations could be established for other parameters with either inflammation grade or fibrosis stage.Our study shows that MDA elevation offers the best prediction potential for fibrosis, while marginal prediction fiability could be attributed to high levels of plasma PC and low levels of HD.

  1. Evolution of the meiotic prophase and of the chromosome pairing process during human fetal ovarian development.

    PubMed

    Roig, I; Robles, P; Garcia, R; Martin, M; Egozcue, J; Cabero, Ll; Barambio, S; Garcia, M

    2005-09-01

    Studies on human oocytes in prophase I are limited due to the difficulty in obtaining the sample. However, a complete study of meiotic prophase evolution and the homologue pairing process is necessary to try to understand the implication of oogenesis in the origin of human aneuploidy. A complete analysis of meiotic prophase progression comprising the long developmental time period during which meiotic prophase takes place, based on the analysis of a total of 8603 oocytes in prophase I from 15 different cases is presented. The pairing process of chromosomes 13 and 18 is also described. The findings significantly relate for the first time the evolution of meiotic prophase to fetal development. Although for both chromosomes 13 and 18 a high pairing efficiency is found, pairing failure at the pachytene stage has been observed in 0.1% of oocytes. However, errors at the diplotene stage are substantially increased, suggesting that complete, premature disjunction of the homologues commonly occurs. Moreover, pre-meiotic errors are also described. Our findings show that homologous chromosomes pair very efficiently, but the high frequency of complete, premature homologue separation found at diplotene suggests that mechanisms other than the pairing process could be more likely to lead to the high aneuploidy rate observed in human oocytes.

  2. Basinwide fold evolution and geometric development of cratonic - foreland basin interaction

    SciTech Connect

    Redly, P.; Hajnal, Z. )

    1996-01-01

    Latest results of the Williston Basin Project incorporate a north-south regional seismic line, which is crossing the deepest part of the Williston Basin from Saskatchewan to South Dakota. The integration of this new profile to the two, existing east-west regional seismic sections, gives a quasi-3D image of the basin. The combined seismic data illustrate alternating extensive and compressive phases during basin development, marked by basinwide circular and radial folds. This alternating pattern of basin subsidence is the very nature of crotonic basin evolution. The structural necessity for compressive phases during crotonic basin subsidence, is shown in a regional scale interpretation that has undergone an Earth-curvature correction. The geometrical evolution of the neighboring foreland basin is also interpreted from data that has been corrected with the Earth-curvature function. It shows that basinwide folds sub-parallel and perpendicular to the longitudinal axis of the basin are analogous to the circular and radial folds of the crotonic basins. These folds, in the foreland belt, are less pronounced because larger scale structural elements can overprint them. Where the crotonic and foreland basins overlap, a complex, deformed zone is present, and contains late stage volcanism, in this area. The geometry of the Williston Basin can be modeled by the Sloss-type [open quote]inverted Gaussian function[close quote] that is modified by the periodic westward tilting of the basin and the Earth-curvature function.

  3. Data encryption standard ASIC design and development report.

    SciTech Connect

    Robertson, Perry J.; Pierson, Lyndon George; Witzke, Edward L.

    2003-10-01

    This document describes the design, fabrication, and testing of the SNL Data Encryption Standard (DES) ASIC. This device was fabricated in Sandia's Microelectronics Development Laboratory using 0.6 {micro}m CMOS technology. The SNL DES ASIC was modeled using VHDL, then simulated, and synthesized using Synopsys, Inc. software and finally IC layout was performed using Compass Design Automation's CAE tools. IC testing was performed by Sandia's Microelectronic Validation Department using a HP 82000 computer aided test system. The device is a single integrated circuit, pipelined realization of DES encryption and decryption capable of throughputs greater than 6.5 Gb/s. Several enhancements accommodate ATM or IP network operation and performance scaling. This design is the latest step in the evolution of DES modules.

  4. Insights into electrosensory organ development, physiology and evolution from a lateral line-enriched transcriptome.

    PubMed

    Modrell, Melinda S; Lyne, Mike; Carr, Adrian R; Zakon, Harold H; Buckley, David; Campbell, Alexander S; Davis, Marcus C; Micklem, Gos; Baker, Clare Vh

    2017-03-27

    The anamniote lateral line system, comprising mechanosensory neuromasts and electrosensory ampullary organs, is a useful model for investigating the developmental and evolutionary diversification of different organs and cell types. Zebrafish neuromast development is increasingly well understood, but neither zebrafish nor Xenopus is electroreceptive and our molecular understanding of ampullary organ development is rudimentary. We have used RNA-seq to generate a lateral line-enriched gene-set from late-larval paddlefish (Polyodon spathula). Validation of a subset reveals expression in developing ampullary organs of transcription factor genes critical for hair cell development, and genes essential for glutamate release at hair cell ribbon synapses, suggesting close developmental, physiological and evolutionary links between non-teleost electroreceptors and hair cells. We identify an ampullary organ-specific proneural transcription factor, and candidates for the voltage-sensing L-type Cav channel and rectifying Kv channel predicted from skate (cartilaginous fish) ampullary organ electrophysiology. Overall, our results illuminate ampullary organ development, physiology and evolution.

  5. The role of the endoderm in the development and evolution of the pharyngeal arches

    PubMed Central

    Graham, Anthony; Okabe, Masataka; Quinlan, Robyn

    2005-01-01

    The oro-pharyngeal apparatus has its origin in a series of bulges found on the lateral surface of the embryonic head, the pharyngeal arches. Significantly, the development of these structures is extremely complex, involving interactions between a number of disparate embryonic cell types: ectoderm, endoderm, mesoderm and neural crest, each of which generates particular components of the arches, and whose development must be co-ordinated to generate the functional adult oro-pharyngeal apparatus. In the past most studies have emphasized the role played by the neural crest, which generates the skeletal elements of the arches, in directing pharyngeal arch development. However, it is now apparent that the pharyngeal endoderm plays an important role in directing arch development. Here we discuss the role of the pharyngeal endoderm in organizing the development of the pharyngeal arches, and the mechanisms that act to pattern the endoderm itself and those which direct its morphogenesis. Finally, we discuss the importance of modification to the pharyngeal endoderm during vertebrate evolution. In particular, we focus on the emergence of the parathyroid gland, which we have recently shown to be the result of the internalization of the gills. PMID:16313389

  6. Insights into electrosensory organ development, physiology and evolution from a lateral line-enriched transcriptome

    PubMed Central

    Modrell, Melinda S; Lyne, Mike; Carr, Adrian R; Zakon, Harold H; Buckley, David; Campbell, Alexander S; Davis, Marcus C; Micklem, Gos; Baker, Clare VH

    2017-01-01

    The anamniote lateral line system, comprising mechanosensory neuromasts and electrosensory ampullary organs, is a useful model for investigating the developmental and evolutionary diversification of different organs and cell types. Zebrafish neuromast development is increasingly well understood, but neither zebrafish nor Xenopus is electroreceptive and our molecular understanding of ampullary organ development is rudimentary. We have used RNA-seq to generate a lateral line-enriched gene-set from late-larval paddlefish (Polyodon spathula). Validation of a subset reveals expression in developing ampullary organs of transcription factor genes critical for hair cell development, and genes essential for glutamate release at hair cell ribbon synapses, suggesting close developmental, physiological and evolutionary links between non-teleost electroreceptors and hair cells. We identify an ampullary organ-specific proneural transcription factor, and candidates for the voltage-sensing L-type Cav channel and rectifying Kv channel predicted from skate (cartilaginous fish) ampullary organ electrophysiology. Overall, our results illuminate ampullary organ development, physiology and evolution. DOI: http://dx.doi.org/10.7554/eLife.24197.001 PMID:28346141

  7. Dynamic DDES On DES Type Grid

    NASA Astrophysics Data System (ADS)

    Yin, Zifei; Durbin, Paul

    2014-11-01

    A dynamic procedure allows a DES formulation that we developed to adjustCDES for different flow configurations. Similarly to the dynamic Smagorinsky model, the grid is required to be fine enough to resolve a significant portion of the inertial range. In some cases, that requirement conflicts with the goal of DES to cut down computing cost. The current effort is therefore to determine a properCDES value by approximately recovering some unresolved small scales from primary, filtered solution. Repeated test filtering is adopted here to compute the approximation of the unfiltered solution. The formulation is based on the dynamicl2 w DDES model and different geometries with varies grid resolution are tested to determine the applicability of proposed formultion on DES type grids.

  8. Significance of epigenetics for understanding brain development, brain evolution and behaviour.

    PubMed

    Keverne, E B

    2014-04-04

    Two major environmental developments have occurred in mammalian evolution which have impacted on the genetic and epigenetic regulation of brain development. The first of these was viviparity and development of the placenta which placed a considerable burden of time and energy investment on the matriline, and which resulted in essential hypothalamic modifications. Maternal feeding, maternal care, parturition, milk letdown and the suspension of fertility and sexual behaviour are all determined by the maternal hypothalamus and have evolved to meet foetal needs under the influence of placental hormones. Viviparity itself provided a new environmental variable for selection pressures to operate via the co-existence over three generations of matrilineal genomes (mother, developing offspring and developing oocytes) in one individual. Also of importance for the matriline has been the evolution of epigenetic marks (imprint control regions) which are heritable and undergo reprogramming primarily in the oocyte to regulate imprinted gene expression according to parent of origin. Imprinting of autosomal genes has played a significant role in mammalian evolutionary development, particularly that of the hypothalamus and placenta. Indeed, many imprinted genes that are co-expressed in the placenta and hypothalamus play an important role in the co-adapted functioning of these organs. Thus the action and interaction of two genomes (maternal and foetal) have provided a template for transgenerational selection pressures to operate in shaping the mothering capabilities of each subsequent generation. The advanced aspects of neocortical brain evolution in primates have emancipated much of behaviour from the determining effects of hormonal action. Thus in large brain primates, most of the sexual behaviour is not reproductive hormone dependent and maternal care can and does occur outside the context of pregnancy and parturition. The neocortex has evolved to be adaptable and while the adapted

  9. New perspectives on eye development and the evolution of eyes and photoreceptors.

    PubMed

    Gehring, W J

    2005-01-01

    Recent experiments on the genetic control of eye development have opened up a completely new perspective on eye evolution. The demonstration that targeted expression of one and the same master control gene, that is, Pax6 can induce the formation of ectopic eyes in both insects and vertebrates, necessitates a reconsideration of the dogma of a polyphyletic origin of the various eye types in all the animal phyla. The involvement of Pax6 and six1 and six3 genes, which encode highly conserved transcription factors, in the genetic control of eye development in organisms ranging from planarians to humans argues strongly for a monophyletic origin of the eye. Because transcription factors can control the expression of any target gene provided it contains the appropriate gene regulatory elements, the conservation of the genetic control of eye development by Pax6 among all bilaterian animals is not due to functional constraints but a consequence of its evolutionary history. The prototypic eyes postulated by Darwin to consist of two cells only, a photoreceptor and a pigment cell, were accidentally controlled by Pax6 and the subsequent evolution of the various eye types occurred by building onto this original genetic program. A hypothesis of intercalary evolution is proposed that assumes that the eye morphogenetic pathway is progressively modified by intercalation of genes between the master control genes on the top of the hierarchy and the structural genes like rhodopsin at the bottom. The recruitment of novel genes into the eye morphogenetic pathway can be due to at least two different genetic mechanisms, gene duplication and enhancer fusion.In tracing back the evolution of eyes beyond bilaterians, we find highly developed eyes in some box-jellyfish as well as in some Hydrozoans. In Hydrozoans the same orthologous six genes (six1 and six3) are required for eye regeneration as in planarians, and in the box jellyfish Tripedalia a pax B gene, which may be a precursor of Pax6

  10. Genomic divergence and brain evolution: How regulatory DNA influences development of the cerebral cortex

    PubMed Central

    Silver, Debra L.

    2015-01-01

    The cerebral cortex controls our most distinguishing higher cognitive functions. Human-specific gene expression differences are abundant in the cerebral cortex, yet we have only begun to understand how these variations impact brain function. This review discusses the current evidence linking non-coding regulatory DNA changes, including enhancers, with neocortical evolution. Functional interrogation using animal models reveals converging roles for our genome in key aspects of cortical development including progenitor cell cycle and neuronal signaling. New technologies, including iPS cells and organoids, offer potential alternatives to modeling evolutionary modifications in a relevant species context. Several diseases rooted in the cerebral cortex uniquely manifest in humans compared to other primates, thus highlighting the importance of understanding human brain differences. Future studies of regulatory loci, including those implicated in disease, will collectively help elucidate key cellular and genetic mechanisms underlying our distinguishing cognitive traits. PMID:26642006

  11. Distribution and evolution of cotton fiber development genes in the fibreless Gossypium raimondii genome.

    PubMed

    Xu, Zhanyou; Yu, Jing; Kohel, Russell J; Percy, Richard G; Beavis, William D; Main, Dorrie; Yu, John Z

    2015-07-01

    Cotton fiber represents the largest single cell in plants and they serve as models to study cell development. This study investigated the distribution and evolution of fiber Unigenes anchored to recombination hotspots between tetraploid cotton (Gossypium hirsutum) At and Dt subgenomes, and within a parental diploid cotton (Gossypium raimondii) D genome. Comparative analysis of At vs D and Dt vs D showed that 1) the D genome provides many fiber genes after its merger with another parental diploid cotton (Gossypium arboreum) A genome although the D genome itself does not produce any spinnable fiber; 2) similarity of fiber genes is higher between At vs D than between Dt vs D genomic hotspots. This is the first report that fiber genes have higher similarity between At and D than between Dt and D. The finding provides new insights into cotton genomic regions that would facilitate genetic improvement of natural fiber properties.

  12. Genomic divergence and brain evolution: How regulatory DNA influences development of the cerebral cortex.

    PubMed

    Silver, Debra L

    2016-02-01

    The cerebral cortex controls our most distinguishing higher cognitive functions. Human-specific gene expression differences are abundant in the cerebral cortex, yet we have only begun to understand how these variations impact brain function. This review discusses the current evidence linking non-coding regulatory DNA changes, including enhancers, with neocortical evolution. Functional interrogation using animal models reveals converging roles for our genome in key aspects of cortical development including progenitor cell cycle and neuronal signaling. New technologies, including iPS cells and organoids, offer potential alternatives to modeling evolutionary modifications in a relevant species context. Several diseases rooted in the cerebral cortex uniquely manifest in humans compared to other primates, thus highlighting the importance of understanding human brain differences. Future studies of regulatory loci, including those implicated in disease, will collectively help elucidate key cellular and genetic mechanisms underlying our distinguishing cognitive traits. © 2015 WILEY Periodicals, Inc.

  13. General hallmarks of microRNAs in brain evolution and development.

    PubMed

    Chen, Wei; Qin, Chuan

    2015-01-01

    MicroRNAs (miRNAs) are endogenous, small non-coding RNA molecules that mediate post-transcriptional gene suppression by incomplete matches with their host mRNAs. In the central nervous system, miRNAs that functionally interact with their target genes constitute a flexible, robust and buffered regulatory network, exerting diverse roles in brain evolution and development. However, distinct variation either in hub miRNA expression levels or patterns may initiate and/or progress various adult-onset nerve-related diseases. In this review, we will summarize the current knowledge about the general hallmarks of brain miRNAs that act as vital determinants in increasingly complicated neural activities. We endeavor to provide a constructive insight into the neuroscience research in the quest to comprehend molecular underpinnings of physiological functions and pathological disorders in central nervous system.

  14. Geochemical evolution of the northern plains of Mars: Early hydrosphere, carbonate development, and present morphology

    SciTech Connect

    Schaefer, M.W. )

    1990-08-30

    It is likely that early in Mars' history, abundant liquid water was available. Under a thick (several bars) carbon dioxide atmosphere, this water could have formed an ocean, located primarily in the lowlands of the northern hemisphere. An equilibrium geochemical model of this ocean and its interactions with the atmosphere and regolith of Mars was developed, and the results of this model were used to discuss the evolution of the volatile budget of Mars, including the deposition of large carbonate beds on the northern plains. Differential solutional weathering of these carbonate beds may have caused the formation of some of the enigmatic features seen on the northern plains of Mars, such as the thumbprint terrain and enclosed depressions.

  15. Genetic manipulation of reptilian embryos: toward an understanding of cortical development and evolution

    PubMed Central

    Nomura, Tadashi; Yamashita, Wataru; Gotoh, Hitoshi; Ono, Katsuhiko

    2015-01-01

    The mammalian neocortex is a remarkable structure that is characterized by tangential surface expansion and six-layered lamination. However, how the mammalian neocortex emerged during evolution remains elusive. Because all modern reptiles have a homolog of the neocortex at the dorsal pallium, developmental analyses of the reptilian cortex are valuable to explore the origin of the neocortex. However, reptilian cortical development and the underlying molecular mechanisms remain unclear, mainly due to technical difficulties with sample collection and embryonic manipulation. Here, we introduce a method of embryonic manipulations for the Madagascar ground gecko and Chinese softshell turtle. We established in ovo electroporation and an ex ovo culture system to address neural stem cell dynamics, neuronal differentiation and migration. Applications of these techniques illuminate the developmental mechanisms underlying reptilian corticogenesis, which provides significant insight into the evolutionary steps of different types of cortex and the origin of the mammalian neocortex. PMID:25759636

  16. The cell biology of neurogenesis: toward an understanding of the development and evolution of the neocortex.

    PubMed

    Taverna, Elena; Götz, Magdalena; Huttner, Wieland B

    2014-01-01

    Neural stem and progenitor cells have a central role in the development and evolution of the mammalian neocortex. In this review, we first provide a set of criteria to classify the various types of cortical stem and progenitor cells. We then discuss the issue of cell polarity, as well as specific subcellular features of these cells that are relevant for their modes of division and daughter cell fate. In addition, cortical stem and progenitor cell behavior is placed into a tissue context, with consideration of extracellular signals and cell-cell interactions. Finally, the differences across species regarding cortical stem and progenitor cells are dissected to gain insight into key developmental and evolutionary mechanisms underlying neocortex expansion.

  17. Genetic manipulation of reptilian embryos: toward an understanding of cortical development and evolution.

    PubMed

    Nomura, Tadashi; Yamashita, Wataru; Gotoh, Hitoshi; Ono, Katsuhiko

    2015-01-01

    The mammalian neocortex is a remarkable structure that is characterized by tangential surface expansion and six-layered lamination. However, how the mammalian neocortex emerged during evolution remains elusive. Because all modern reptiles have a homolog of the neocortex at the dorsal pallium, developmental analyses of the reptilian cortex are valuable to explore the origin of the neocortex. However, reptilian cortical development and the underlying molecular mechanisms remain unclear, mainly due to technical difficulties with sample collection and embryonic manipulation. Here, we introduce a method of embryonic manipulations for the Madagascar ground gecko and Chinese softshell turtle. We established in ovo electroporation and an ex ovo culture system to address neural stem cell dynamics, neuronal differentiation and migration. Applications of these techniques illuminate the developmental mechanisms underlying reptilian corticogenesis, which provides significant insight into the evolutionary steps of different types of cortex and the origin of the mammalian neocortex.

  18. Robust non-linear differential equation models of gene expression evolution across Drosophila development.

    PubMed

    Haye, Alexandre; Albert, Jaroslav; Rooman, Marianne

    2012-01-19

    This paper lies in the context of modeling the evolution of gene expression away from stationary states, for example in systems subject to external perturbations or during the development of an organism. We base our analysis on experimental data and proceed in a top-down approach, where we start from data on a system's transcriptome, and deduce rules and models from it without a priori knowledge. We focus here on a publicly available DNA microarray time series, representing the transcriptome of Drosophila across evolution from the embryonic to the adult stage. In the first step, genes were clustered on the basis of similarity of their expression profiles, measured by a translation-invariant and scale-invariant distance that proved appropriate for detecting transitions between development stages. Average profiles representing each cluster were computed and their time evolution was analyzed using coupled differential equations. A linear and several non-linear model structures involving a transcription and a degradation term were tested. The parameters were identified in three steps: determination of the strongest connections between genes, optimization of the parameters defining these connections, and elimination of the unnecessary parameters using various reduction schemes. Different solutions were compared on the basis of their abilities to reproduce the data, to keep realistic gene expression levels when extrapolated in time, to show the biologically expected robustness with respect to parameter variations, and to contain as few parameters as possible. We showed that the linear model did very well in reproducing the data with few parameters, but was not sufficiently robust and yielded unrealistic values upon extrapolation in time. In contrast, the non-linear models all reached the latter two objectives, but some were unable to reproduce the data. A family of non-linear models, constructed from the exponential of linear combinations of expression levels, reached

  19. Robust non-linear differential equation models of gene expression evolution across Drosophila development

    PubMed Central

    2012-01-01

    Background This paper lies in the context of modeling the evolution of gene expression away from stationary states, for example in systems subject to external perturbations or during the development of an organism. We base our analysis on experimental data and proceed in a top-down approach, where we start from data on a system's transcriptome, and deduce rules and models from it without a priori knowledge. We focus here on a publicly available DNA microarray time series, representing the transcriptome of Drosophila across evolution from the embryonic to the adult stage. Results In the first step, genes were clustered on the basis of similarity of their expression profiles, measured by a translation-invariant and scale-invariant distance that proved appropriate for detecting transitions between development stages. Average profiles representing each cluster were computed and their time evolution was analyzed using coupled differential equations. A linear and several non-linear model structures involving a transcription and a degradation term were tested. The parameters were identified in three steps: determination of the strongest connections between genes, optimization of the parameters defining these connections, and elimination of the unnecessary parameters using various reduction schemes. Different solutions were compared on the basis of their abilities to reproduce the data, to keep realistic gene expression levels when extrapolated in time, to show the biologically expected robustness with respect to parameter variations, and to contain as few parameters as possible. Conclusions We showed that the linear model did very well in reproducing the data with few parameters, but was not sufficiently robust and yielded unrealistic values upon extrapolation in time. In contrast, the non-linear models all reached the latter two objectives, but some were unable to reproduce the data. A family of non-linear models, constructed from the exponential of linear combinations

  20. Genome Evolution and the Emergence of Fruiting Body Development in Myxococcus xanthus

    PubMed Central

    Goldman, Barry; Bhat, Swapna; Shimkets, Lawrence J.

    2007-01-01

    Background Lateral gene transfer (LGT) is thought to promote speciation in bacteria, though well-defined examples have not been put forward. Methodology/Principle Findings We examined the evolutionary history of the genes essential for a trait that defines a phylogenetic order, namely fruiting body development of the Myxococcales. Seventy-eight genes that are essential for Myxococcus xanthus development were examined for LGT. About 73% of the genes exhibit a phylogeny similar to that of the 16S rDNA gene and a codon bias consistent with other M. xanthus genes suggesting vertical transmission. About 22% have an altered codon bias and/or phylogeny suggestive of LGT. The remaining 5% are unique. Genes encoding signal production and sensory transduction were more likely to be transmitted vertically with clear examples of duplication and divergence into multigene families. Genes encoding metabolic enzymes were frequently acquired by LGT. Myxobacteria exhibit aerobic respiration unlike most of the δ Proteobacteria. M. xanthus contains a unique electron transport pathway shaped by LGT of genes for succinate dehydrogenase and three cytochrome oxidase complexes. Conclusions/Significance Fruiting body development depends on genes acquired by LGT, particularly those involved in polysaccharide production. We suggest that aerobic growth fostered innovation necessary for development by allowing myxobacteria access to a different gene pool from anaerobic members of the δ Proteobacteria. Habitat destruction and loss of species diversity could restrict the evolution of new bacterial groups by limiting the size of the prospective gene pool. PMID:18159227

  1. A perspective on the evolution of germ-cell development and germinal mosaics of deleterious mutations.

    PubMed

    Woodruff, Ronny C; Balinski, Michael A; Bouzat, Juan L

    2015-10-01

    In many animals a small number of primordial germ cells (PGCs) are set aside early in development, mitosis and mitochondrial DNA syntheses are arrested, transcription is stopped or reduced, and the PGCs migrate later to the emerging gonads and become germ cells. What could be the evolutionary advantage of sequestering non-dividing PGCs early in development? A commonly cited advantage is a reduction in the number of new deleterious mutations that would occur if there were additional divisions in PGCs early in development. We would like to add to this advantage the fact that these additional mutations in PGCs give rise to germinal mosaics (i.e., premeiotic clusters of mutation) in multiple progeny of the same individual, thus having a larger detrimental effect on the evolutionary fitness of their carriers. Here, we reviewed published studies providing evidence that germinal mosaics of deleterious mutant alleles are not rare, occur for all types of genetic damage, and have been observed in all tested organisms and in nature. We propose the hypothesis that PGC sequestration during early animal development may have evolved in part in response to selection for preventing the occurrence of premeiotic clusters of deleterious mutant alleles, and describe a series of predictions that would allow the assessment of the potential role of germinal mosaics on the evolution of PGC sequestration.

  2. Evolution of pyruvate carboxylase and other biotin containing enzymes in developing rat liver and kidney.

    PubMed

    Salto, R; Girón, M D; del Mar Sola, M; Vargas, A M

    1999-10-01

    The evolution of pyruvate carboxylase has been studied in rat liver and kidney during perinatal development. The pyruvate carboxylase activity, amount of enzyme and mRNA levels have been assayed from 2 days before delivery to weaning. In liver, there is a peak of activity and amount of enzyme 24 h before delivery and 2 peaks, at 12 h and 6 days, after parturition. The transcription of the enzyme gene followed a similar pattern, with mRNA peaks preceding those of activity and amount of enzyme. However, in kidney, pyruvate carboxylase activity, amount and mRNA remain low until weaning. These results confirm the limited role of renal gluconeogenesis during the perinatal development. Since all carboxylases contain biotin as prosthetic group, the biotinylation of pyruvate carboxylase during the perinatal period was investigated by western-blot using streptavidin-biotin peroxidase. In the mitochondrial samples from liver and kidney, all the pyruvate carboxylase detected was fully biotinylated, indicating an early development of the holocarboxylase synthetase activity in the perinatal period. This Western-blot technique also allowed us the detection of other biotin-enzymes based on their molecular weight. In liver, during the perinatal development propionyl-coA and 3-methyl-crotonyl-coA carboxylases followed a pattern of induction similar to pyruvate carboxylase. In kidney, the expression of mitochondrial carboxylases was lower compared to liver and propionyl-coA carboxylase was not detected during the studied period.

  3. Early floral development of Heliconia latispatha (Heliconiaceae), a key taxon for understanding the evolution of flower development in the Zingiberales.

    PubMed

    Kirchoff, Bruce K; Lagomarsino, Laura P; Newman, Winnell H; Bartlett, Madelaine E; Specht, Chelsea D

    2009-03-01

    We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.

  4. The Start-Up, Evolution and Impact of a Research Group in a University Developing Its Knowledge Base

    ERIC Educational Resources Information Center

    Horta, Hugo; Martins, Rui

    2014-01-01

    This article focuses on the understudied role of research groups contributing to develop the knowledge base of developing universities in regions lagging behind in human, financial and scientific resources. We analyse the evolution of a research group that, in less than 10 years, achieved worldwide recognition in the field of microelectronics,…

  5. A developmental staging series for the lizard genus Anolis: a new system for the integration of evolution, development, and ecology.

    PubMed

    Sanger, Thomas J; Losos, Jonathan B; Gibson-Brown, Jeremy J

    2008-02-01

    Vertebrate developmental biologists typically rely on a limited number of model organisms to understand the evolutionary bases of morphological change. Unfortunately, a typical model system for squamates (lizards and snakes) has not yet been developed leaving many fundamental questions about morphological evolution unaddressed. New model systems would ideally include clades, rather than single species, that are amenable to both laboratory studies of development and field-based analyses of ecology and evolution. Combining an understanding of development with an understanding of ecology and evolution within and between closely related species has the potential to create a seamless understanding of how genetic variation underlies ecologically and evolutionarily relevant variation within populations and between species. Here we briefly introduce a new model system for the integration of development, evolution, and ecology, the lizard genus Anolis, a diverse group of lizards whose ecology and evolution is well understood, and whose genome has recently been sequenced. We present a developmental staging series for Anolis lizards that can act as a baseline for later comparative and experimental studies within this genus.

  6. Frogs as integrative models for understanding digestive organ development and evolution

    PubMed Central

    Womble, Mandy; Pickett, Melissa; Nascone-Yoder, Nanette

    2016-01-01

    The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laev is and Eleutherodactylouscoqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines. PMID:26851628

  7. Cis-regulatory programs in the development and evolution of vertebrate paired appendages

    PubMed Central

    Gehrke, Andrew R.; Shubin, Neil H.

    2017-01-01

    Differential gene expression is the core of development, mediating the genetic changes necessary for determining cell identity. The regulation of gene activity by cis-acting elements (e.g., enhancers) is a crucial mechanism for determining differential gene activity by precise control of gene expression in embryonic space and time. Modifications to regulatory regions can have profound impacts on phenotype, and therefore developmental and evolutionary biologists have increasingly focused on elucidating the transcriptional control of genes that build and pattern body plans. Here, we trace the evolutionary history of transcriptional control of three loci key to vertebrate appendage development (Fgf8, Shh, and HoxD/A). Within and across these regulatory modules, we find both complex and flexible regulation in contrast with more fixed enhancers that appear unchanged over vast timescales of vertebrate evolution. The transcriptional control of vertebrate appendage development was likely already incredibly complex in the common ancestor of fish, implying that subtle changes to regulatory networks were more likely responsible for alterations in phenotype rather than the de novo addition of whole regulatory domains. Finally, we discuss the dangers of relying on inter-species transgenesis when testing enhancer function, and call for more controlled regulatory swap experiments when inferring the evolutionary history of enhancer elements. PMID:26783722

  8. Embryonic development of fin spines in Callorhinchus milii (Holocephali); implications for chondrichthyan fin spine evolution.

    PubMed

    Jerve, Anna; Johanson, Zerina; Ahlberg, Per; Boisvert, Catherine

    2014-01-01

    Fin spines are commonly known from fossil gnathostomes (jawed vertebrates) and are usually associated with paired and unpaired fins. They are less common among extant gnathostomes, being restricted to the median fins of certain chondrichthyans (cartilaginous fish), including chimaerids (elephant sharks) and neoselachians (sharks, skates, and rays). Fin spine growth is of great interest and relevance but few studies have considered their evolution and development. We investigated the development of the fin spine of the chimaerid Callorhinchus milii using stained histological sections from a series of larval, hatchling, and adult individuals. The lamellar trunk dentine of the Callorhinchus spine first condenses within the mesenchyme, rather than at the contact surface between mesenchyme and epithelium, in a manner more comparable to dermal bone formation than to normal odontode development. Trabecular dentine forms a small component of the spine under the keel; it is covered externally with a thin layer of lamellar trunk dentine, which is difficult to distinguish in sectioned adult spines. We suggest that the distinctive characteristics of the trunk dentine may reflect an origin through co-option of developmental processes involved in dermal bone formation. Comparison with extant Squalus and a range of fossil chondrichthyans shows that Callorhinchus is more representative than Squalus of generalized chondrichthyan fin-spine architecture, highlighting its value as a developmental model organism.

  9. Gestural and symbolic development among apes and humans: support for a multimodal theory of language evolution

    PubMed Central

    Gillespie-Lynch, Kristen; Greenfield, Patricia M.; Lyn, Heidi; Savage-Rumbaugh, Sue

    2014-01-01

    What are the implications of similarities and differences in the gestural and symbolic development of apes and humans?This focused review uses as a starting point our recent study that provided evidence that gesture supported the symbolic development of a chimpanzee, a bonobo, and a human child reared in language-enriched environments at comparable stages of communicative development. These three species constitute a complete clade, species possessing a common immediate ancestor. Communicative behaviors observed among all species in a clade are likely to have been present in the common ancestor. Similarities in the form and function of many gestures produced by the chimpanzee, bonobo, and human child suggest that shared non-verbal skills may underlie shared symbolic capacities. Indeed, an ontogenetic sequence from gesture to symbol was present across the clade but more pronounced in child than ape. Multimodal expressions of communicative intent (e.g., vocalization plus persistence or eye-contact) were normative for the child, but less common for the apes. These findings suggest that increasing multimodal expression of communicative intent may have supported the emergence of language among the ancestors of humans. Therefore, this focused review includes new studies, since our 2013 article, that support a multimodal theory of language evolution. PMID:25400607

  10. The evolution of basal progenitors in the developing non-mammalian brain

    PubMed Central

    Nomura, Tadashi; Ohtaka-Maruyama, Chiaki; Yamashita, Wataru; Wakamatsu, Yoshio; Murakami, Yasunori; Calegari, Federico; Suzuki, Kunihiro; Gotoh, Hitoshi; Ono, Katsuhiko

    2016-01-01

    The amplification of distinct neural stem/progenitor cell subtypes during embryogenesis is essential for the intricate brain structures present in various vertebrate species. For example, in both mammals and birds, proliferative neuronal progenitors transiently appear on the basal side of the ventricular zone of the telencephalon (basal progenitors), where they contribute to the enlargement of the neocortex and its homologous structures. In placental mammals, this proliferative cell population can be subdivided into several groups that include Tbr2+ intermediate progenitors and basal radial glial cells (bRGs). Here, we report that basal progenitors in the developing avian pallium show unique morphological and molecular characteristics that resemble the characteristics of bRGs, a progenitor population that is abundant in gyrencephalic mammalian neocortex. Manipulation of LGN (Leu-Gly-Asn repeat-enriched protein) and Cdk4/cyclin D1, both essential regulators of neural progenitor dynamics, revealed that basal progenitors and Tbr2+ cells are distinct cell lineages in the developing avian telencephalon. Furthermore, we identified a small population of subapical mitotic cells in the developing brains of a wide variety of amniotes and amphibians. Our results suggest that unique progenitor subtypes are amplified in mammalian and avian lineages by modifying common mechanisms of neural stem/progenitor regulation during amniote brain evolution. PMID:26732839

  11. Frogs as integrative models for understanding digestive organ development and evolution.

    PubMed

    Womble, Mandy; Pickett, Melissa; Nascone-Yoder, Nanette

    2016-03-01

    The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laevis and Eleutherodactylous coqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Evolution and protein interactions of AP2 proteins in Brassicaceae: Evidence linking development and environmental responses.

    PubMed

    Zeng, Liping; Yin, Yue; You, Chenjiang; Pan, Qianli; Xu, Duo; Jin, Taijie; Zhang, Bailong; Ma, Hong

    2016-06-01

    Plants have evolved a large number of transcription factors (TF), which are enriched among duplicate genes, highlighting their roles in complex regulatory networks. The APETALA2/EREBP-like genes constitute a large plant TF family and participate in development and stress responses. To probe the conservation and divergence of AP2/EREBP genes, we analyzed the duplication patterns of this family in Brassicaceae and identified interacting proteins of representative Arabidopsis AP2/EREBP proteins. We found that many AP2/EREBP duplicates generated early in Brassicaceae history were quickly lost, but many others were retained in all tested Brassicaceae species, suggesting early functional divergence followed by persistent conservation. In addition, the sequences of the AP2 domain and exon numbers were highly conserved in rosids. Furthermore, we used 16 A. thaliana AP2/EREBP proteins as baits in yeast screens and identified 1,970 potential AP2/EREBP-interacting proteins, with a small subset of interactions verified in planta. Many AP2 genes also exhibit reduced expression in an anther-defective mutant, providing a possible link to developmental regulation. The putative AP2-interacting proteins participate in many functions in development and stress responses, including photomorphogenesis, flower development, pathogenesis, drought and cold responses, abscisic acid and auxin signaling. Our results present the AP2/EREBP evolution patterns in Brassicaceae, and support a proposed interaction network of AP2/EREBP proteins and their putative interacting proteins for further study. © 2015 Institute of Botany, Chinese Academy of Sciences.

  13. A gene network model accounting for development and evolution of mammalian teeth.

    PubMed

    Salazar-Ciudad, Isaac; Jernvall, Jukka

    2002-06-11

    Generation of morphological diversity remains a challenge for evolutionary biologists because it is unclear how an ultimately finite number of genes involved in initial pattern formation integrates with morphogenesis. Ideally, models used to search for the simplest developmental principles on how genes produce form should account for both developmental process and evolutionary change. Here we present a model reproducing the morphology of mammalian teeth by integrating experimental data on gene interactions and growth into a morphodynamic mechanism in which developing morphology has a causal role in patterning. The model predicts the course of tooth-shape development in different mammalian species and also reproduces key transitions in evolution. Furthermore, we reproduce the known expression patterns of several genes involved in tooth development and their dynamics over developmental time. Large morphological effects frequently can be achieved by small changes, according to this model, and similar morphologies can be produced by different changes. This finding may be consistent with why predicting the morphological outcomes of molecular experiments is challenging. Nevertheless, models incorporating morphology and gene activity show promise for linking genotypes to phenotypes.

  14. Carbonate Platform Development and Stromatolite Morphogenesis: Constraints on Environmental and Biological Evolution

    NASA Technical Reports Server (NTRS)

    Grotzinger, John P.

    2003-01-01

    Work has been completed on the digital mapping of a terminal Proterozoic reef complex in Namibia. This complex formed an isolated carbonate platform developed downdip on a carbonate ramp of the Nama Group. The stratigraphic evolution of the platform was digitally reconstructed from an extensive dataset that was compiled by using digital surveying technologies. The platform comprises three accommodation cycles in which each subsequent cycle experienced progressively greater influence of a long-term accommodation increase. Aggradation and progradation during the first cycle resulted in a flat, uniform, sheet-like platform. The coarsening and shallowing-upward sequence representing the first cycle is dominated by columnar stromatolitic thrombolites and massive dolostones with interbedded mudstone-grainstone at the base of the sequence grading into cross-bedded dolostones. The second cycle features aggradation, formation of a distinct margin containing thrombolite mounds and domes, and the development of a bucket geometry. Columnar stromatolitic thrombolites dominate the platform interior. The final stage of platform development shows a deepening trend with initial aggradation and formation of well-bedded, thin deposits in the interior and mound development at the margins. While the interior drowned, the platform margin kept up with rising sea level and a complex pinnacle reef formed containing fused and coalesced thrombolite mounds flanked by bioclastic grainstones (containing Cloudina and Namacalathus fossils) and collapse breccias. A set of isolated large thrombolite mounds flanked by shales indicate the final stage of the carbonate platform. During a progressive increase in accommodation, a flat-topped isolated carbonate platform becomes aerially less extensive by either backstepping or formation of smaller pinnacles or a combination of both. The overall geometric evolution of the studied platform from flat-topped to bucket with elevated margins is recorded in many

  15. Carbonate Platform Development and Stromatolite Morphogenesis: Constraints on Environmental and Biological Evolution

    NASA Technical Reports Server (NTRS)

    Grotzinger, John P.

    2003-01-01

    Work has been completed on the digital mapping of a terminal Proterozoic reef complex in Namibia. This complex formed an isolated carbonate platform developed downdip on a carbonate ramp of the Nama Group. The stratigraphic evolution of the platform was digitally reconstructed from an extensive dataset that was compiled by using digital surveying technologies. The platform comprises three accommodation cycles in which each subsequent cycle experienced progressively greater influence of a long-term accommodation increase. Aggradation and progradation during the first cycle resulted in a flat, uniform, sheet-like platform. The coarsening and shallowing-upward sequence representing the first cycle is dominated by columnar stromatolitic thrombolites and massive dolostones with interbedded mudstone-grainstone at the base of the sequence grading into cross-bedded dolostones. The second cycle features aggradation, formation of a distinct margin containing thrombolite mounds and domes, and the development of a bucket geometry. Columnar stromatolitic thrombolites dominate the platform interior. The final stage of platform development shows a deepening trend with initial aggradation and formation of well-bedded, thin deposits in the interior and mound development at the margins. While the interior drowned, the platform margin kept up with rising sea level and a complex pinnacle reef formed containing fused and coalesced thrombolite mounds flanked by bioclastic grainstones (containing Cloudina and Namacalathus fossils) and collapse breccias. A set of isolated large thrombolite mounds flanked by shales indicate the final stage of the carbonate platform. During a progressive increase in accommodation, a flat-topped isolated carbonate platform becomes aerially less extensive by either backstepping or formation of smaller pinnacles or a combination of both. The overall geometric evolution of the studied platform from flat-topped to bucket with elevated margins is recorded in many

  16. The Earth's core formation and development: evidence from evolution of tectonomagmatic processes and paleomagnetic data

    NASA Astrophysics Data System (ADS)

    Sharkov, E. V.

    2011-12-01

    Many geologists confident that the core provides modern tectonic and magmatic activity on the Earth, which explains our interest in this topic, and vice versa we can use evolution of tectonomagmatic processes throughout the Earth's (and other terrestrial planetary bodies) history for reconstruction of the core formation and evolution. Most researchers, follow to V. Safronov (1972) and A. Ringwood (1979), confident that the Earth has occurred due to accumulation of hypothetical chemically homogeneous planetesimals, composed by chondrite material, ie, as a result of homogeneous accretion. However, this single-stage chondrite model of accretion is inconsistent with fact of cardinal change of tectonomagmatic processes on the terrestrial planets in the middle stages of their development. For example, the critical irreversible change of the Earth's tectonomagmatic evolution occurred in range 2.35-2.0 Ga, when geochemical-enriched Fe-Ti picrites and basalts firstly appeared in large quantities and first geological evidence of plate tectonics showed up (Sharkov, Bogatikov, 2010). We suggest that these changes were linked with ascending of mantle superplumes of the second generation (thermochemical), originated at the the boundary of liquid iron core and silicate mantle, in similar way as the modern plumes. All terrestrial planetary bodies (Earth, Venus, Mars, Mercury, and the Moon) have a similar structure, consist of iron core and silicate envelope, and developed at the same scenario, which provide for drastic irreversible change in character of tectonomagmatic processes at the middle stages of their evolution (Sharkov, Bogatikov, 2009). Such a situation can be realized only in case: (1) the terrestrial planetary bodies originally had heterogeneous structure, and (2) their heating occurred from the top down accompanied by cooling of outer shells. As a result, material of the primordial cores, where enriched material survived, were remained a long time untouched. It

  17. Cartographie des disques

    NASA Astrophysics Data System (ADS)

    Hameury, Jean-Marie

    2001-01-01

    Two techniques are frequently used to produce images of the accretion disc in an eclipsing binary: eclipse mapping and Doppler tomography. From the light curve, one can deduce the radial distribution of the effective temperature, assuming axial symmetry. On the other hand, from the variation of the line profile one can reconstruct an image in the velocity space, which can be converted into a real image if one knows the kinematics of the system. Deux techniques sont couramment utilisées pour obtenir des images des disques dans les systèmes binaires à éclipses. En utilisant la courbe de lumière, on peut remonter à la distribution radiale de la brillance de surface, en supposant que celle-ci a une symètrie axiale. D'autre part, les profils de raies renseignent sur la distribution de vitesse des régions émissives leur variation temporelle permet de réaliser une image dans l'espace des vitesses, que l'on peut ensuite transformer en carte dans l'espace (x,y) si on connaît la cinématique du système.

  18. A simple rule governs the evolution and development of hominin tooth size.

    PubMed

    Evans, Alistair R; Daly, E Susanne; Catlett, Kierstin K; Paul, Kathleen S; King, Stephen J; Skinner, Matthew M; Nesse, Hans P; Hublin, Jean-Jacques; Townsend, Grant C; Schwartz, Gary T; Jernvall, Jukka

    2016-02-25

    The variation in molar tooth size in humans and our closest relatives (hominins) has strongly influenced our view of human evolution. The reduction in overall size and disproportionate decrease in third molar size have been noted for over a century, and have been attributed to reduced selection for large dentitions owing to changes in diet or the acquisition of cooking. The systematic pattern of size variation along the tooth row has been described as a 'morphogenetic gradient' in mammal, and more specifically hominin, teeth since Butler and Dahlberg. However, the underlying controls of tooth size have not been well understood, with hypotheses ranging from morphogenetic fields to the clone theory. In this study we address the following question: are there rules that govern how hominin tooth size evolves? Here we propose that the inhibitory cascade, an activator-inhibitor mechanism that affects relative tooth size in mammals, produces the default pattern of tooth sizes for all lower primary postcanine teeth (deciduous premolars and permanent molars) in hominins. This configuration is also equivalent to a morphogenetic gradient, finally pointing to a mechanism that can generate this gradient. The pattern of tooth size remains constant with absolute size in australopiths (including Ardipithecus, Australopithecus and Paranthropus). However, in species of Homo, including modern humans, there is a tight link between tooth proportions and absolute size such that a single developmental parameter can explain both the relative and absolute sizes of primary postcanine teeth. On the basis of the relationship of inhibitory cascade patterning with size, we can use the size at one tooth position to predict the sizes of the remaining four primary postcanine teeth in the row for hominins. Our study provides a development-based expectation to examine the evolution of the unique proportions of human teeth.

  19. Strength evolution and the development of crystallographic preferred orientation during deformation of two-phase marbles

    NASA Astrophysics Data System (ADS)

    Austin, Nicholas; Evans, Brian; Rybacki, Erik; Dresen, Georg

    2014-09-01

    We conducted conventional triaxial compression and confined torsion tests on calcite rocks at 1023 K and equivalent strain rates between 10- 6 and 10- 3 s- 1, to investigate the influence of variations in volume fraction and geometry of a second phase on the evolution of strength and CPO. Nominally dense, two-phase marbles were made by hot-isostatic pressing of mixtures of calcite and amorphous carbon. The carbon grains were either spheres or splinters with known size distributions, were chemically inert, and are nearly rigid. Adding 1 vol.% spheres caused only small changes in strength or CPO. Strengths were consistent with the activation of slip on f101bar1, the hardest system in calcite. Adding 10 vol.% splinters increased the strength at low strains and strain rates but had smaller effects at high strains or rates. The CPO of rocks containing splinters were similar to those in pure samples, but with reduced intensity. When 10 vol.% spheres were added, the aggregate strength under confined torsion was less than that of the pure material. Distinct and intense CPOs developed. The reduced stresses were consistent with those necessary for slip on systems weaker than f. Viscoplastic self-consistent calculations used to model the texture evolution required slip on f101bar1 and c1bar21bar0 to match the CPO of pure samples; results were consistent with the inclusion of slip on r1bar21bar0. In samples containing 10 vol.% spheres deformed in torsion, slip activity on the harder systems was decreased. The exact cause of the strength reduction in these experiments is not understood, but it is possible that adding smooth spheres enhanced grain-boundary sliding, thereby decreasing activity on f101bar1. Thus, shape and volume fraction of second phases may be important in determining CPO and strength; and it is important to consider the loading geometry.

  20. Success in Developing Regions: World Records Evolution through a Geopolitical Prism

    PubMed Central

    Guillaume, Marion; Helou, Nour El; Nassif, Hala; Berthelot, Geoffroy; Len, Stéphane; Thibault, Valérie; Tafflet, Muriel; Quinquis, Laurent; Desgorces, François; Hermine, Olivier; Toussaint, Jean-François

    2009-01-01

    A previous analysis of World Records (WR) has revealed the potential limits of human physiology through athletes' personal commitment. The impact of political factors on sports has only been studied through Olympic medals and results. Here we studied 2876 WR from 63 nations in four summer disciplines. We propose three new indicators and show the impact of historical, geographical and economical factors on the regional WR evolution. The south-eastward path of weighted annual barycenter (i.e. the average of country coordinates weighting by the WR number) shows the emergence of East Africa and China in WR archives. Home WR ratio decreased from 79.9% before the second World War to 23.3% in 2008, underlining sports globalization. Annual Cumulative Proportions (ACP, i.e. the cumulative sum of the WR annual rate) highlight the regional rates of progression. For all regions, the mean slope of ACP during the Olympic era is 0.0101, with a maximum between 1950 and 1989 (0.0156). For European countries, this indicator reflects major historical events (slowdown for western countries after 1945, slowdown for eastern countries after 1990). Mean North-American ACP slope is 0.0029 over the century with an acceleration between 1950 and 1989 at 0.0046. Russia takes off in 1935 and slows down in 1988 (0.0038). For Eastern Europe, maximal progression is seen between 1970 and 1989 (0.0045). China starts in 1979 with a maximum between 1990 and 2008 (0.0021), while other regions have largely declined (mean ACP slope for all other countries  = 0.0011). A similar trend is observed for the evolution of the 10 best performers. The national analysis of WR reveals a precise and quantifiable link between the sport performances of a country, its historical or geopolitical context, and its steps of development. PMID:19862324

  1. Pollen structure and development in Nymphaeales: insights into character evolution in an ancient angiosperm lineage.

    PubMed

    Taylor, Mackenzie L; Cooper, Ranessa L; Schneider, Edward L; Osborn, Jeffrey M

    2015-10-01

    A knowledge of pollen characters in early-diverging angiosperm lineages is essential for understanding pollen evolution and the role of pollen in angiosperm diversification. In this paper, we report and synthesize data on mature pollen and pollen ontogeny from all genera of Nymphaeales within a comparative, phylogenetic context and consider pollen evolution in this early-diverging angiosperm lineage. We describe mature pollen characters for Euryale, Barclaya, and Nymphaea ondinea, taxa for which little to no structural data exist. We studied mature pollen for all nymphaealean genera using light, scanning electron, and transmission electron microscopy. We reviewed published reports of nymphaealean pollen to provide a comprehensive discussion of pollen characters in water lilies. Nymphaeales exhibit diversity in key pollen characters, including dispersal unit size, ornamentation, aperture morphology, and tapetum type. All Nymphaeales pollen are tectate-columellate, exhibiting one of two distinct patterns of infratectal ultrastructure-a thick infratectal space with robust columellae or a thin infratectal space with thin columellae. All genera have pollen with a lamellate endexine that becomes compressed in the proximal, but not distal wall. This endexine ultrastructure supports the operculate hypothesis for aperture origin. Nymphaeaceae pollen exhibit a membranous granular layer, which is a synapomorphy of the family. Variation in pollen characters indicates that significant potential for lability in pollen development was present in Nymphaeales at the time of its divergence from the rest of angiosperms. Structural and ontogenetic data are essential for interpreting pollen characters, such as infratectum and endexine ultrastructure in Nymphaeales. © 2015 Botanical Society of America.

  2. Sox2+ progenitors in sharks link taste development with the evolution of regenerative teeth from denticles

    PubMed Central

    Martin, Kyle J.; Rasch, Liam J.; Cooper, Rory L.; Johanson, Zerina; Fraser, Gareth J.

    2016-01-01

    Teeth and denticles belong to a specialized class of mineralizing epithelial appendages called odontodes. Although homology of oral teeth in jawed vertebrates is well supported, the evolutionary origin of teeth and their relationship with other odontode types is less clear. We compared the cellular and molecular mechanisms directing development of teeth and skin denticles in sharks, where both odontode types are retained. We show that teeth and denticles are deeply homologous developmental modules with equivalent underlying odontode gene regulatory networks (GRNs). Notably, the expression of the epithelial progenitor and stem cell marker sex-determining region Y-related box 2 (sox2) was tooth-specific and this correlates with notable differences in odontode regenerative ability. Whereas shark teeth retain the ancestral gnathostome character of continuous successional regeneration, new denticles arise only asynchronously with growth or after wounding. Sox2+ putative stem cells associated with the shark dental lamina (DL) emerge from a field of epithelial progenitors shared with anteriormost taste buds, before establishing within slow-cycling cell niches at the (i) superficial taste/tooth junction (T/TJ), and (ii) deep successional lamina (SL) where tooth regeneration initiates. Furthermore, during regeneration, cells from the superficial T/TJ migrate into the SL and contribute to new teeth, demonstrating persistent contribution of taste-associated progenitors to tooth regeneration in vivo. This data suggests a trajectory for tooth evolution involving cooption of the odontode GRN from nonregenerating denticles by sox2+ progenitors native to the oral taste epithelium, facilitating the evolution of a novel regenerative module of odontodes in the mouth of early jawed vertebrates: the teeth. PMID:27930309

  3. Human immunodeficiency virus type 1 genetic evolution in children with different rates of development of disease.

    PubMed Central

    Ganeshan, S; Dickover, R E; Korber, B T; Bryson, Y J; Wolinsky, S M

    1997-01-01

    The rate of development of disease varies considerably among human immunodeficiency virus type 1 (HIV-1)-infected children. The reasons for these observed differences are not clearly understood but most probably depend on the dynamic interplay between the HIV-1 quasispecies virus population and the immune constraints imposed by the host. To study the relationship between disease progression and genetic diversity, we analyzed the evolution of viral sequences within six perinatally infected children by examining proviral sequences spanning the C2 through V5 regions of the viral envelope gene by PCR of blood samples obtained at sequential visits. PCR product DNAs from four sample time points per child were cloned, and 10 to 13 clones from each sample were sequenced. Greater genetic distances relative to the time of infection were found for children with low virion-associated RNA burdens and slow progression to disease relative to those found for children with high virion-associated RNA burdens and rapid progression to disease. The greater branch lengths observed in the phylogenetic reconstructions correlated with a higher accumulation rate of nonsynonymous base substitutions per potential nonsynonymous site, consistent with positive selection for change rather than a difference in replication kinetics. Viral sequences from children with slow progression to disease also showed a tendency to form clusters that associated with different sampling times. These progressive shifts in the viral population were not found in viral sequences from children with rapid progression to disease. Therefore, despite the HIV-1 quasispecies being a diverse, rapidly evolving, and competing population of genetic variants, different rates of genetic evolution could be found under different selective constraints. These data suggest that the evolutionary dynamics exhibited by the HIV-1 quasispecies virus populations are compatible with a Darwinian system evolving under the constraints of

  4. Evolution, development, and plasticity of the human brain: from molecules to bones.

    PubMed

    Hrvoj-Mihic, Branka; Bienvenu, Thibault; Stefanacci, Lisa; Muotri, Alysson R; Semendeferi, Katerina

    2013-10-30

    Neuroanatomical, molecular, and paleontological evidence is examined in light of human brain evolution. The brain of extant humans differs from the brains of other primates in its overall size and organization, and differences in size and organization of specific cortical areas and subcortical structures implicated into complex cognition and social and emotional processing. The human brain is also characterized by functional lateralizations, reflecting specializations of the cerebral hemispheres in humans for different types of processing, facilitating fast and reliable communication between neural cells in an enlarged brain. The features observed in the adult brain reflect human-specific patterns of brain development. Compared to the brains of other primates, the human brain takes longer to mature, promoting an extended period for establishing cortical microcircuitry and its modifications. Together, these features may underlie the prolonged period of learning and acquisition of technical and social skills necessary for survival, creating a unique cognitive and behavioral niche typical of our species. The neuroanatomical findings are in concordance with molecular analyses, which suggest a trend toward heterochrony in the expression of genes implicated in different functions. These include synaptogenesis, neuronal maturation, and plasticity in humans, mutations in genes implicated in neurite outgrowth and plasticity, and an increased role of regulatory mechanisms, potentially promoting fast modification of neuronal morphologies in response to new computational demands. At the same time, endocranial casts of fossil hominins provide an insight into the timing of the emergence of uniquely human features in the course of evolution. We conclude by proposing several ways of combining comparative neuroanatomy, molecular biology and insights gained from fossil endocasts in future research.

  5. Evolution, development, and plasticity of the human brain: from molecules to bones

    PubMed Central

    Hrvoj-Mihic, Branka; Bienvenu, Thibault; Stefanacci, Lisa; Muotri, Alysson R.; Semendeferi, Katerina

    2013-01-01

    Neuroanatomical, molecular, and paleontological evidence is examined in light of human brain evolution. The brain of extant humans differs from the brains of other primates in its overall size and organization, and differences in size and organization of specific cortical areas and subcortical structures implicated into complex cognition and social and emotional processing. The human brain is also characterized by functional lateralizations, reflecting specializations of the cerebral hemispheres in humans for different types of processing, facilitating fast and reliable communication between neural cells in an enlarged brain. The features observed in the adult brain reflect human-specific patterns of brain development. Compared to the brains of other primates, the human brain takes longer to mature, promoting an extended period for establishing cortical microcircuitry and its modifications. Together, these features may underlie the prolonged period of learning and acquisition of technical and social skills necessary for survival, creating a unique cognitive and behavioral niche typical of our species. The neuroanatomical findings are in concordance with molecular analyses, which suggest a trend toward heterochrony in the expression of genes implicated in different functions. These include synaptogenesis, neuronal maturation, and plasticity in humans, mutations in genes implicated in neurite outgrowth and plasticity, and an increased role of regulatory mechanisms, potentially promoting fast modification of neuronal morphologies in response to new computational demands. At the same time, endocranial casts of fossil hominins provide an insight into the timing of the emergence of uniquely human features in the course of evolution. We conclude by proposing several ways of combining comparative neuroanatomy, molecular biology and insights gained from fossil endocasts in future research. PMID:24194709

  6. A model of growth restraints to explain the development and evolution of tooth shapes in mammals.

    PubMed

    Osborn, Jeffrey W

    2008-12-07

    The problem investigated here is control of the development of tooth shape. Cells at the growing soft tissue interface between the ectoderm and mesoderm in a tooth anlage are observed to buckle and fold into a template for the shape of the tooth crown. The final shape is created by enamel secreted onto the folds. The pattern in which the folds develop is generally explained as a response to the pattern in which genes are locally expressed at the interface. This congruence leaves the problem of control unanswered because it does not explain how either pattern is controlled. Obviously, cells are subject to Newton's laws of motion so that mechanical forces and constraints must ultimately cause the movements of cells during tooth morphogenesis. A computer model is used to test the hypothesis that directional resistances to growth of the epithelial part of the interface could account for the shape into which the interface folds. The model starts with a single epithelial cell whose growth is constrained by 4 constant directional resistances (anterior, posterior, medial and lateral). The constraints force the growing epithelium to buckle and fold. By entering into the model different values for these constraints the modeled epithelium is induced to buckle and fold into the different shapes associated with the evolution of a human upper molar from that of a reptilian ancestor. The patterns and sizes of cusps and the sequences in which they develop are all correctly reproduced. The model predicts the changes in the 4 directional constraints necessary to develop and evolve from one tooth shape into another. I conclude more generally expressed genes that control directional resistances to growth, not locally expressed genes, may provide the information for the shape into which a tooth develops.

  7. Evolution and development of the adelphophagic, intracapsular Schmidt's larva of the nemertean Lineus ruber.

    PubMed

    Martín-Durán, José M; Vellutini, Bruno C; Hejnol, Andreas

    2015-01-01

    The life cycle of many animals includes a larval stage, which has diversified into an astonishing variety of ecological strategies. The Nemertea is a group of spiralians that exhibits a broad diversity of larval forms, including the iconic pilidium. A pelagic planktotrophic pilidium is the ancestral form in the Pilidiophora, but several lineages exhibit deviations of this condition, mostly as a transition to pelagic lecithotrophy. The most extreme case occurs, however, in the Pilidiophoran Lineus ruber, which exhibits an adelphophagic intracapsular pilidium, the so-called Schmidt's larva. We combined confocal laser scanning microscopy and gene expression studies to characterize the development and metamorphosis of the Schmidt's larva of L. ruber. The larva forms after gastrulation, and comprises a thin epidermis, a proboscis rudiment and two pairs of imaginal discs from which the juvenile will develop. The cells internalized during gastrulation form a blind gut and the blastopore gives rise to the mouth of the larva and juvenile. The Schmidt's larva eats other siblings that occupy the same egg capsule, accumulating nutrients for the juvenile. A gradual metamorphosis involves the differentiation of the juvenile cell types from the imaginal discs and the shedding of the larval epidermis. The expression of evolutionarily conserved anterior (foxQ2, six3/6, gsc, otx), endomesodermal (foxA, GATA456-a, twi-a) and posterior (evx, cdx) markers demonstrate that the juvenile retains the molecular patterning of the Schmidt's larva. After metamorphosis, the juveniles stay over 20 days within the egg masses, until they are fully mature and hatch. The evolution of the intracapsular Schmidt's larva involved the loss of the typical feeding structures of the planktotrophic pilidium and a precocious formation of the imaginal discs, as also observed in other pelagic lecithotrophic forms. However, no special adaptations are observed related to adelphophagy. As in planktotrophic

  8. Floral development and vascularization help to explain merism evolution in Paepalanthus (Eriocaulaceae, Poales)

    PubMed Central

    Trovó, Marcelo; Coan, Alessandra Ike

    2016-01-01

    Background Flowers in Eriocaulaceae, a monocot family that is highly diversified in Brazil, are generally trimerous, but dimerous flowers occur in Paepalanthus and a few other genera. The floral merism in an evolutionary context, however, is unclear. Paepalanthus encompasses significant morphological variation leading to a still unresolved infrageneric classification. Ontogenetic comparative studies of infrageneric groups in Paepalanthus and in Eriocaulaceae are lacking, albeit necessary to establish evolution of characters such as floral merism and their role as putative synapomorphies. Methods We studied the floral development and vascularization of eight species of Paepalanthus that belong to distinct clades in which dimery occurs, using light and scanning electron microscopies. Results Floral ontogeny in dimerous Paepalanthus shows lateral sepals emerging simultaneously and late-developing petals. The outer whorl of stamens is absent in all flowers examined here. The inner whorl of stamens becomes functional in staminate flowers and is reduced to staminodes in the pistillate ones. In pistillate flowers, vascular bundles reach the staminodes. Ovary vascularization shows ventral bundles in a commissural position reaching the synascidiate portion of the carpels. Three gynoecial patterns are described for the studied species: (1) gynoecium with a short style, two nectariferous branches and two long stigmatic branches, in most species; (2) gynoecium with a long style, two nectariferous branches and two short stigmatic branches, in P. echinoides; and (3) gynoecium with long style, absent nectariferous branches and two short stigmatic branches, in P. scleranthus. Discussion Floral development of the studied species corroborates the hypothesis that the sepals of dimerous flowers of Paepalanthus correspond to the lateral sepals of trimerous flowers. The position and vascularization of floral parts also show that, during dimery evolution in Paepalanthus, a flower sector

  9. The machine conception of the organism in development and evolution: a critical analysis.

    PubMed

    Nicholson, Daniel J

    2014-12-01

    This article critically examines one of the most prevalent metaphors in contemporary biology, namely the machine conception of the organism (MCO). Although the fundamental differences between organisms and machines make the MCO an inadequate metaphor for conceptualizing living systems, many biologists and philosophers continue to draw upon the MCO or tacitly accept it as the standard model of the organism. The analysis presented here focuses on the specific difficulties that arise when the MCO is invoked in the contexts of development and evolution. In developmental biology the MCO underlies a logically incoherent model of ontogeny, the genetic program, which serves to legitimate three problematic theses about development: genetic animism, neo-preformationism, and developmental computability. In evolutionary biology the MCO is responsible for grounding unwarranted theoretical appeals to the concept of design as well as to the interpretation of natural selection as an engineer, which promote a distorted understanding of the process and products of evolutionary change. Overall, it is argued that, despite its heuristic value, the MCO today is impeding rather than enabling further progress in our comprehension of living systems.

  10. Evolution of the knowledge system for agricultural development in the Yaqui Valley, Sonora, Mexico.

    PubMed

    McCullough, Ellen B; Matson, Pamela A

    2016-04-26

    Knowledge systems-networks of linked actors, organizations, and objects that perform a number of knowledge-related functions that link knowledge and know how with action-have played a key role in fostering agricultural development over the last 50 years. We examine the evolution of the knowledge system of the Yaqui Valley, Mexico, a region often described as the home of the green revolution for wheat, tracing changes in the functions of critical knowledge system participants, information flows, and research priorities. Most of the knowledge system's key players have been in place for many decades, although their roles have changed in response to exogenous and endogenous shocks and trends (e.g., drought, policy shifts, and price trends). The system has been agile and able to respond to challenges, in part because of the diversity of players (evolving roles of actors spanning research-decision maker boundaries) and also because of the strong and consistent role of innovative farmers. Although the agricultural research agenda in the Valley is primarily controlled from within the agricultural sector, outside voices have become an important influence in broadening development- and production-oriented perspectives to sustainability perspectives.

  11. Molecular development of fibular reduction in birds and its evolution from dinosaurs

    PubMed Central

    Botelho, João Francisco; Smith‐Paredes, Daniel; Soto‐Acuña, Sergio; O'Connor, Jingmai; Palma, Verónica; Vargas, Alexander O.

    2016-01-01

    Birds have a distally reduced, splinter‐like fibula that is shorter than the tibia. In embryonic development, both skeletal elements start out with similar lengths. We examined molecular markers of cartilage differentiation in chicken embryos. We found that the distal end of the fibula expresses Indian hedgehog (IHH), undergoing terminal cartilage differentiation, and almost no Parathyroid‐related protein (PTHrP), which is required to develop a proliferative growth plate (epiphysis). Reduction of the distal fibula may be influenced earlier by its close contact with the nearby fibulare, which strongly expresses PTHrP. The epiphysis‐like fibulare however then separates from the fibula, which fails to maintain a distal growth plate, and fibular reduction ensues. Experimental downregulation of IHH signaling at a postmorphogenetic stage led to a tibia and fibula of equal length: The fibula is longer than in controls and fused to the fibulare, whereas the tibia is shorter and bent. We propose that the presence of a distal fibular epiphysis may constrain greater growth in the tibia. Accordingly, many Mesozoic birds show a fibula that has lost its distal epiphysis, but remains almost as long as the tibia, suggesting that loss of the fibulare preceded and allowed subsequent evolution of great fibulo–tibial disparity. PMID:26888088

  12. Evolution and diverse roles of the CUP-SHAPED COTYLEDON genes in Arabidopsis leaf development.

    PubMed

    Hasson, Alice; Plessis, Anne; Blein, Thomas; Adroher, Bernard; Grigg, Stephen; Tsiantis, Miltos; Boudaoud, Arezki; Damerval, Catherine; Laufs, Patrick

    2011-01-01

    CUP-SHAPED COTYLEDON2 (CUC2) and the interacting microRNA miR164 regulate leaf margin dissection. Here, we further investigate the evolution and the specific roles of the CUC1 to CUC3 genes during Arabidopsis thaliana leaf serration. We show that CUC2 is essential for dissecting the leaves of a wide range of lobed/serrated Arabidopsis lines. Inactivation of CUC3 leads to a partial suppression of the serrations, indicating a role for this gene in leaf shaping. Morphometric analysis of leaf development and genetic analysis provide evidence for different temporal contributions of CUC2 and CUC3. Chimeric constructs mixing CUC regulatory sequences with different coding sequences reveal both redundant and specific roles for the three CUC genes that could be traced back to changes in their expression pattern or protein activity. In particular, we show that CUC1 triggers the formation of leaflets when ectopically expressed instead of CUC2 in the developing leaves. These divergent fates of the CUC1 and CUC2 genes after their formation by the duplication of a common ancestor is consistent with the signature of positive selection detected on the ancestral branch to CUC1. Combining experimental observations with the retraced origin of the CUC genes in the Brassicales, we propose an evolutionary scenario for the CUC genes.

  13. Evolution and formation of shear layers in a developing turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Lee, Junghoon; Monty, Jason; Hutchins, Nicholas

    2016-11-01

    The evolution and formation mechanism of shear layers in the outer region of a turbulent boundary layer are investigated using time-resolved PIV datasets of a developing turbulent boundary layer from inception at the trip up to Reτ = 3000 . An analysis of a sequence of instantaneous streamwise velocity fluctuation fields reveals that strong streamwise velocity gradients are prevalent along interfaces where low- and high-speed regions interact. To provide an insight on how such regions are associated with the formation of shear layers in the outer regions, we compute conditional averages of streamwise velocity fluctuations based on a strong shear layer. Our results reveal that one possible mechanism for the generation of shear layers in the outer region is due to the mismatch in the convection velocities between low- and high-speed regions. The results also indicate that the angle of the inclined shear layer is developing in time. In addition, the conditionally averaged velocity fluctuations exhibit a local instability along these shear layers, leading to a shear layer roll-up event as the layers evolve in time. Based on these findings, we propose a conceptual model which describes dynamic interactions of shear layers and their associated large-scale coherent motions. The authors wish to acknowledge the financial support of the Australian Research Council.

  14. Heredity, development and evolution: the unmodern synthesis of E.S. Russell.

    PubMed

    Esposito, Maurizio

    2013-09-01

    In 1930, while R.A. Fisher, J.B.S. Haldane, E.B. Ford and S.G. Wright were laying the foundations of what a decade later J.S. Huxley dubbed "Modern Synthesis", E.S. Russell published a groundbreaking work, The Interpretation of Development and Heredity. In this book Russell not only condemned Mendelian genetics and neo-Darwinism, but also proposed an alternative synthesis unifying heredity, development, and evolution. The book did not represent the work of a mind operating in isolation. Rather, it was a synthetic work connecting ideas and doctrines of many influential scientists working in Europe and the USA. Through the analysis of archival documents and rarely or never mentioned sources, this article provides an unconventional picture of Russell's theoretical biology. It will be shown that Russell was an international celebrity; he was at the centre of a large network of scholars who shared his ideas and insights. He was one of several biologists arguing for a different synthesis; a synthesis perhaps less visible, less institutionalised, and less 'modern', nevertheless with its influential advocates and international support. Finally, this study shows that Russell's synthesis was not rooted in the classic pantheon of towering figures in the history of biology, i.e. Darwin, Wallace, and Mendel, but was based on the teachings of Kant, Goethe, Cuvier, von Baer, and Müller.

  15. Evolution of the knowledge system for agricultural development in the Yaqui Valley, Sonora, Mexico

    PubMed Central

    McCullough, Ellen B.; Matson, Pamela A.

    2016-01-01

    Knowledge systems—networks of linked actors, organizations, and objects that perform a number of knowledge-related functions that link knowledge and know how with action—have played a key role in fostering agricultural development over the last 50 years. We examine the evolution of the knowledge system of the Yaqui Valley, Mexico, a region often described as the home of the green revolution for wheat, tracing changes in the functions of critical knowledge system participants, information flows, and research priorities. Most of the knowledge system's key players have been in place for many decades, although their roles have changed in response to exogenous and endogenous shocks and trends (e.g., drought, policy shifts, and price trends). The system has been agile and able to respond to challenges, in part because of the diversity of players (evolving roles of actors spanning research–decision maker boundaries) and also because of the strong and consistent role of innovative farmers. Although the agricultural research agenda in the Valley is primarily controlled from within the agricultural sector, outside voices have become an important influence in broadening development- and production-oriented perspectives to sustainability perspectives. PMID:21606365

  16. Wings versus legs in the avian bauplan: development and evolution of alternative locomotor strategies.

    PubMed

    Heers, Ashley M; Dial, Kenneth P

    2015-02-01

    Wings have long been regarded as a hallmark of evolutionary innovation, allowing insects, birds, and bats to radiate into aerial environments. For many groups, our intuitive and colloquial perspective is that wings function for aerial activities, and legs for terrestrial, in a relatively independent manner. However, insects and birds often engage their wings and legs cooperatively. In addition, the degree of autonomy between wings and legs may be constrained by tradeoffs, between allocating resources to wings versus legs during development, or between wing versus leg investment and performance (because legs must be carried as baggage by wings during flight and vice versa). Such tradeoffs would profoundly affect the development and evolution of locomotor strategies, and many related aspects of animal ecology. Here, we provide the first evaluation of wing versus leg investment, performance and relative use, in birds-both across species, and during ontogeny in three precocial species with different ecologies. Our results suggest that tradeoffs between wing and leg modules help shape ontogenetic and evolutionary trajectories, but can be offset by recruiting modules cooperatively. These findings offer a new paradigm for exploring locomotor strategies of flying organisms and their extinct precursors, and thereby elucidating some of the most spectacular diversity in animal history.

  17. Pollen development in Annona cherimola Mill. (Annonaceae). Implications for the evolution of aggregated pollen

    PubMed Central

    Lora, Jorge; Testillano, Pilar S; Risueño, Maria C; Hormaza, Jose I; Herrero, Maria

    2009-01-01

    Background In most flowering plants, pollen is dispersed as monads. However, aggregated pollen shedding in groups of four or more pollen grains has arisen independently several times during angiosperm evolution. The reasons behind this phenomenon are largely unknown. In this study, we followed pollen development in Annona cherimola, a basal angiosperm species that releases pollen in groups of four, to investigate how pollen ontogeny may explain the rise and establishment of this character. We followed pollen development using immunolocalization and cytochemical characterization of changes occurring from anther differentiation to pollen dehiscence. Results Our results show that, following tetrad formation, a delay in the dissolution of the pollen mother cell wall and tapetal chamber is a key event that holds the four microspores together in a confined tapetal chamber, allowing them to rotate and then bind through the aperture sites through small pectin bridges, followed by joint sporopollenin deposition. Conclusion Pollen grouping could be the result of relatively minor ontogenetic changes beneficial for pollen transfer or/and protection from desiccation. Comparison of these events with those recorded in the recent pollen developmental mutants in Arabidopsis indicates that several failures during tetrad dissolution may convert to a common recurring phenotype that has evolved independently several times, whenever this grouping conferred advantages for pollen transfer. PMID:19874617

  18. Differentiation of ovarian development and the evolution of fecundity in rapidly diverging exotic beetle populations.

    PubMed

    Macagno, Anna L M; Beckers, Oliver M; Moczek, Armin P

    2015-11-01

    Fecundity is a fundamental determinant of fitness, yet the proximate developmental and physiological mechanisms that enable its often rapid evolution in natural populations are poorly understood. Here, we investigated two populations of the dung beetle Onthophagus taurus that were established in exotic ranges in the early 1970s. These populations are subject to drastically different levels of resource competition in the field, and have diverged dramatically in female fecundity. Specifically, Western Australian O. taurus experience high levels of resource competition, and exhibit greatly elevated reproductive output compared to beetles from the Eastern US, where resource competition is minimal and female fecundity is low. We compared patterns of ovarian maturation, relative investment into and timing of egg production, and potential trade-offs between ovarian investment and the duration of larval development and adult body size between populations representative of both exotic ranges. We found that the rapid divergence in fecundity between exotic populations is associated with striking differences in several aspects of ovarian development: (1) Western Australian females exhibit accelerated ovarian development, (2) produce more eggs, (3) bigger eggs, and (4) start laying eggs earlier compared to their Eastern US counterparts. At the same time, divergence in ovarian maturation patterns occurred alongside changes in (5) larval developmental time, and (6) adult body size, and (7) mass. Western Australian females take longer to complete larval development and, surprisingly, emerge into smaller yet heavier adults than size-matched Eastern US females. We discuss our results in the context of the evolutionary developmental biology of fecundity in exotic populations. © 2015 Wiley Periodicals, Inc.

  19. Evolution of insect wings and development - new details from Palaeozoic nymphs.

    PubMed

    Haug, Joachim T; Haug, Carolin; Garwood, Russell J

    2016-02-01

    The nymphal stages of Palaeozoic insects differ significantly in morphology from those of their modern counterparts. Morphological details for some previously reported species have recently been called into question. Palaeozoic insect nymphs are important, however - their study could provide key insights into the evolution of wings, and complete metamorphosis. Here we review past work on these topics and juvenile insects in the fossil record, and then present both novel and previously described nymphs, documented using new imaging methods. Our results demonstrate that some Carboniferous nymphs - those of Palaeodictyopteroidea - possessed movable wing pads and appear to have been able to perform simple flapping flight. It remains unclear whether this feature is ancestral for Pterygota or an autapomorphy of Palaeodictyopteroidea. Further characters of nymphal development which were probably in the ground pattern of Pterygota can be reconstructed. Wing development was very gradual (archimetaboly). Wing pads did not protrude from the tergum postero-laterally as in most modern nymphs, but laterally, and had well-developed venation. The modern orientation of wing pads and the delay of wing development into later developmental stages (condensation) appears to have evolved several times independently within Pterygota: in Ephemeroptera, Odonatoptera, Eumetabola, and probably several times within Polyneoptera. Selective pressure appears to have favoured a more pronounced metamorphosis between the last nymphal and adult stage, ultimately reducing exploitation competition between the two. We caution, however, that the results presented herein remain preliminary, and the reconstructed evolutionary scenario contains gaps and uncertainties. Additional comparative data need to be collected. The present study is thus seen as a starting point for this enterprise. © 2014 Cambridge Philosophical Society.

  20. Beyond the Baseline: Proceedings of the Space Station Evolution Symposium. Volume 2, Part 2; Space Station Freedom Advanced Development Program

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This report contains the individual presentations delivered at the Space Station Evolution Symposium in League City, Texas on February 6, 7, 8, 1990. Personnel responsible for Advanced Systems Studies and Advanced Development within the Space Station Freedom program reported on the results of their work to date. Systems Studies presentations focused on identifying the baseline design provisions (hooks and scars) necessary to enable evolution of the facility to support changing space policy and anticipated user needs. Also emphasized were evolution configuration and operations concepts including on-orbit processing of space transfer vehicles. Advanced Development task managers discussed transitioning advanced technologies to the baseline program, including those near-term technologies which will enhance the safety and productivity of the crew and the reliability of station systems. Special emphasis was placed on applying advanced automation technology to ground and flight systems. This publication consists of two volumes. Volume 1 contains the results of the advanced system studies with the emphasis on reference evolution configurations, system design requirements and accommodations, and long-range technology projections. Volume 2 reports on advanced development tasks within the Transition Definition Program. Products of these tasks include: engineering fidelity demonstrations and evaluations on Station development testbeds and Shuttle-based flight experiments; detailed requirements and performance specifications which address advanced technology implementation issues; and mature applications and the tools required for the development, implementation, and support of advanced technology within the Space Station Freedom Program.

  1. Modelisations des effets de surface sur les jets horizontaux subsoniques d'hydrogene et de methane

    NASA Astrophysics Data System (ADS)

    Gomez, Luis Fernando

    Le developpement des codes et de normes bases sur une methodologie scientifique requiert la capacite de predire l'etendue inflammable de deversements gazeux d'hydrogene sous differentes conditions. Des etudes anterieures ont deja etabli des modeles bases sur les lois de conservation de la mecanique des fluides basees sur des correlations experimentales qui permettent de predire la decroissance de la concentration et de la vitesse d'un gaz le long de l'axe d'un jet libre vertical. Cette etude s'interesse aux effets de proximite a une surface horizontale parallele sur un jet turbulent. Nous nous interessons a son impact sur l'etendue du champ de la concentration et sur l'enveloppe inflammable en particulier. Cette etude est comparative : l'hydrogene est compare au methane. Ceci permet de degager l'influence des effets de difference de la densite sur le comportement du jet, et de comparer le comportement de l'hydrogene aux correlations experimentales, qui ont ete essentiellement etablies pour le methane. Un modele decrivant l'evolution spatio-temporelle du champ de concentration du gaz dilue est propose, base sur la mecanique des fluides computationnelle. Cette approche permet de varier systematiquement les conditions aux frontieres (proximite du jet a la surface, par exemple) et de connaitre en detail les proprietes de l'ecoulement. Le modele est implemente dans le code de simulations par volumes finis de FLUENT. Les resultats des simulations sont compares avec les lois de similitudes decoulant de la theorie des jets d'ecoulements turbulents libres ainsi qu'avec les resultats experimentaux disponibles. L'effet de la difference des masses molaires des constituantes du jet et des constituantes du milieu de dispersion est egalement etudie dans le contexte du comportement d'echelle de la region developpee du jet.

  2. Development of a lecithotrophic pilidium larva illustrates convergent evolution of trochophore-like morphology.

    PubMed

    Hunt, Marie K; Maslakova, Svetlana A

    2017-01-01

    's morphological and developmental features are best explained by transition from planktotrophy to lecithotrophy in the context of pilidial development, rather than by retention of or reversal to what is often assumed to be the spiralian ancestral larval type - the trochophore. Development of pilidium nielseni is a compelling example of convergent evolution of a trochophore-like body plan within Spiralia.

  3. The Development, Evolution, and Status of Holland's Theory of Vocational Personalities: Reflections and Future Directions for Counseling Psychology

    ERIC Educational Resources Information Center

    Nauta, Margaret M.

    2010-01-01

    This article celebrates the 50th anniversary of the introduction of John L. Holland's (1959) theory of vocational personalities and work environments by describing the theory's development and evolution, its instrumentation, and its current status. Hallmarks of Holland's theory are its empirical testability and its user-friendliness. By…

  4. The Development, Evolution, and Status of Holland's Theory of Vocational Personalities: Reflections and Future Directions for Counseling Psychology

    ERIC Educational Resources Information Center

    Nauta, Margaret M.

    2010-01-01

    This article celebrates the 50th anniversary of the introduction of John L. Holland's (1959) theory of vocational personalities and work environments by describing the theory's development and evolution, its instrumentation, and its current status. Hallmarks of Holland's theory are its empirical testability and its user-friendliness. By…

  5. National medicines policies - a review of the evolution and development processes.

    PubMed

    Hoebert, Joëlle M; van Dijk, Liset; Mantel-Teeuwisse, Aukje K; Leufkens, Hubert Gm; Laing, Richard O

    2013-01-01

    Continuous provision of appropriate medicines of assured quality, in adequate quantities, and at reasonable prices is a concern for all national governments. A national medicines policy (NMP) developed in a collaborative fashion identifies strategies needed to meet these objectives and provides a comprehensive framework to develop all components of a national pharmaceutical sector. To meet the health needs of the population, there is a general need for medicine policies based on universal principles, but nevertheless adapted to the national situation. This review aims to provide a quantitative and qualitative (describing the historical development) study of the development process and evolution of NMPs. The number of NMPs and their current status has been obtained from the results of the assessment of WHO Level I indicators. The policy formulation process is examined in more detail with case studies from four countries: Sri Lanka, Australia, former Yugoslav Republic of Macedonia and South Africa. The number of NMPs worldwide has increased in the last 25 years with the highest proportional increase in the last 5-10 years in high-income countries. Higher income countries seem to have more NMP implementation plans available and have updated their NMP more recently. The four case studies show that the development of a NMP is a complex process that is country specific. In addition, it demonstrates that an appropriate political window is needed for the policy to be passed (for South Africa and the FYR Macedonia, a major political event acted as a trigger for initiating the policy development). Policy-making does not stop with the official adoption of a policy but should create mechanisms for implementation and monitoring. The NMPs of the FYR Macedonia and Australia provide indicators for monitoring. To date, not all countries have a NMP since political pressure by national experts or non-governmental organizations is generally needed to establish a NMP. Case studies in

  6. National medicines policies – a review of the evolution and development processes

    PubMed Central

    2013-01-01

    Objectives Continuous provision of appropriate medicines of assured quality, in adequate quantities, and at reasonable prices is a concern for all national governments. A national medicines policy (NMP) developed in a collaborative fashion identifies strategies needed to meet these objectives and provides a comprehensive framework to develop all components of a national pharmaceutical sector. To meet the health needs of the population, there is a general need for medicine policies based on universal principles, but nevertheless adapted to the national situation. This review aims to provide a quantitative and qualitative (describing the historical development) study of the development process and evolution of NMPs. Methods The number of NMPs and their current status has been obtained from the results of the assessment of WHO Level I indicators. The policy formulation process is examined in more detail with case studies from four countries: Sri Lanka, Australia, former Yugoslav Republic of Macedonia and South Africa. Results The number of NMPs worldwide has increased in the last 25 years with the highest proportional increase in the last 5–10 years in high-income countries. Higher income countries seem to have more NMP implementation plans available and have updated their NMP more recently. The four case studies show that the development of a NMP is a complex process that is country specific. In addition, it demonstrates that an appropriate political window is needed for the policy to be passed (for South Africa and the FYR Macedonia, a major political event acted as a trigger for initiating the policy development). Policy-making does not stop with the official adoption of a policy but should create mechanisms for implementation and monitoring. The NMPs of the FYR Macedonia and Australia provide indicators for monitoring. Conclusions To date, not all countries have a NMP since political pressure by national experts or non-governmental organizations is generally

  7. Evolution of water chemistry during Marcellus Shale gas development: A case study in West Virginia.

    PubMed

    Ziemkiewicz, Paul F; Thomas He, Y

    2015-09-01

    Hydraulic fracturing (HF) has been used with horizontal drilling to extract gas and natural gas liquids from source rock such as the Marcellus Shale in the Appalachian Basin. Horizontal drilling and HF generates large volumes of waste water known as flowback. While inorganic ion chemistry has been well characterized, and the general increase in concentration through the flowback is widely recognized, the literature contains little information relative to organic compounds and radionuclides. This study examined the chemical evolution of liquid process and waste streams (including makeup water, HF fluids, and flowback) in four Marcellus Shale gas well sites in north central West Virginia. Concentrations of organic and inorganic constituents and radioactive isotopes were measured to determine changes in waste water chemistry during shale gas development. We found that additives used in fracturing fluid may contribute to some of the constituents (e.g., Fe) found in flowback, but they appear to play a minor role. Time sequence samples collected during flowback indicated increasing concentrations of organic, inorganic and radioactive constituents. Nearly all constituents were found in much higher concentrations in flowback water than in injected HF fluids suggesting that the bulk of constituents originate in the Marcellus Shale formation rather than in the formulation of the injected HF fluids. Liquid wastes such as flowback and produced water, are largely recycled for subsequent fracturing operations. These practices limit environmental exposure to flowback. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Chiton myogenesis: perspectives for the development and evolution of larval and adult muscle systems in molluscs.

    PubMed

    Wanninger, Andreas; Haszprunar, Gerhard

    2002-02-01

    We investigated muscle development in two chiton species, Mopalia muscosa and Chiton olivaceus, from embryo hatching until 10 days after metamorphosis. The anlagen of the dorsal longitudinal rectus muscle and a larval prototroch muscle ring are the first detectable muscle structures in the early trochophore-like larva. Slightly later, a ventrolaterally situated pair of longitudinal muscles appears, which persists through metamorphosis. In addition, the anlagen of the putative dorsoventral shell musculature and the first fibers of a muscular grid, which is restricted to the pretrochal region and consists of outer ring and inner diagonal muscle fibers, are generated. Subsequently, transversal muscle fibers form underneath each future shell plate and the ventrolateral enrolling muscle is established. At metamorphic competence, the dorsoventral shell musculature consists of numerous serially repeated, intercrossing muscle fibers. Their concentration into seven (and later eight) functional shell plate muscle bundles starts after the completion of metamorphosis. The larval prototroch ring and the pretrochal muscle grid are lost at metamorphosis. The structure of the apical grid and its atrophy during metamorphosis suggests ontogenetic repetition of (parts of) the original body-wall musculature of a proposed worm-shaped molluscan ancestor. Moreover, our data show that the "segmented" character of the polyplacophoran shell musculature is a secondary condition, thus contradicting earlier theories that regarded the Polyplacophora (and thus the entire phylum Mollusca) as primarily eumetameric (annelid-like). Instead, we propose an unsegmented trochozoan ancestor at the base of molluscan evolution. Copyright 2002 Wiley-Liss, Inc.

  9. Mutual influences between the main olfactory and vomeronasal systems in development and evolution

    PubMed Central

    Suárez, Rodrigo; García-González, Diego; de Castro, Fernando

    2012-01-01

    The sense of smell plays a crucial role in the sensory world of animals. Two chemosensory systems have been traditionally thought to play-independent roles in mammalian olfaction. According to this, the main olfactory system (MOS) specializes in the detection of environmental odorants, while the vomeronasal system (VNS) senses pheromones and semiochemicals produced by individuals of the same or different species. Although both systems differ in their anatomy and function, recent evidence suggests they act synergistically in the perception of scents. These interactions include similar responses to some ligands, overlap of telencephalic connections and mutual influences in the regulation of olfactory-guided behavior. In the present work, we propose the idea that the relationships between systems observed at the organismic level result from a constant interaction during development and reflects a common history of ecological adaptations in evolution. We review the literature to illustrate examples of developmental and evolutionary processes that evidence these interactions and propose that future research integrating both systems may shed new light on the mechanisms of olfaction. PMID:23269914

  10. Comb jellies (ctenophora): a model for Basal metazoan evolution and development.

    PubMed

    Pang, Kevin; Martindale, Mark Q

    2008-11-01

    INTRODUCTIONCtenophores, or comb jellies, are a group of marine organisms whose unique biological features and phylogenetic placement make them a key taxon for understanding animal evolution. These gelatinous creatures are clearly distinct from cnidarian medusae (i.e., jellyfish). Key features present in the ctenophore body plan include biradial symmetry, an oral-aboral axis delimited by a mouth and an apical sensory organ, two tentacles, eight comb rows composed of interconnected cilia, and thick mesoglea. Other morphological features include definitive muscle cells, a nerve net, basal lamina, a sperm acrosome, and light-producing photocytes. Aspects of their development made them attractive to experimental embryologists as early as the 19th century. Recently, because of their role as an invasive species, studies on their role in ecology and fisheries-related fields have increased. Although the phylogenetic placement of ctenophores with respect to other animals has proven difficult, it is clear that, along with poriferans, placozoans, and cnidarians, ctenophores are one of the earliest diverging extant animal groups. It is important to determine if some of the complex features of ctenophores are examples of convergence or if they were lost in other animal branches. Because ctenophores are amenable to modern technical approaches, they could prove to be a highly useful emerging model.

  11. Skeletal development in sloths and the evolution of mammalian vertebral patterning.

    PubMed

    Hautier, Lionel; Weisbecker, Vera; Sánchez-Villagra, Marcelo R; Goswami, Anjali; Asher, Robert J

    2010-11-02

    Mammals show a very low level of variation in vertebral count, particularly in the neck. Phenotypes exhibited at various stages during the development of the axial skeleton may play a key role in testing mechanisms recently proposed to explain this conservatism. Here, we provide osteogenetic data that identify developmental criteria with which to recognize cervical vs. noncervical vertebrae in mammals. Except for sloths, all mammals show the late ossification of the caudal-most centra in the neck after other centra and neural arches. In sloths with 8-10 ribless neck vertebrae, the caudal-most neck centra ossify early, matching the pattern observed in cranial thoracic vertebrae of other mammals. Accordingly, we interpret the ribless neck vertebrae of three-toed sloths caudal to V7 as thoracic based on our developmental criterion. Applied to the unusual vertebral phenotype of long-necked sloths, these data support the interpretation that elements of the axial skeleton with origins from distinct mesodermal tissues have repatterned over the course of evolution.

  12. Human APOBEC3G drives HIV-1 evolution and the development of drug resistance

    SciTech Connect

    Bhattacharya, Tamoy; Kim, Eun - Young; Koning, Fransje; Malim, Michael; Wolinsky, Steven M

    2008-01-01

    Human APOBEC3G (hA3G) is an innate virus restriction factor that induces deamination of specific cytidine residues in single-stranded human immunodeficiency virus type 1 (HIV-1) DNA. Whereas destructive hA3G editing leads to a profound loss of HIV-1 infectivity, more limited editing could be a source of adaptation and diversification. Here we show that the presence of hA3G in T-cells can drive the development of diversity in HIV-1 populations and that under selection pressure imposed by the nucleotide analog reverse transcriptase inhibitor 3TC ((-)2',3'-dideoxy-3'-thiacytidine), a single point mutation that confers 3TC resistance, methionine 184 to isoleucine (M1841), emerges rapidly and reaches fixation. These results provide strong evidence that mutation by hA3G is an important source of genetic variation on which natural selection acts to shape the structure of the viral population and drive the tempo of HIV-1 evolution.

  13. The role of human-specific gene duplications during brain development and evolution.

    PubMed

    Sassa, Takayuki

    2013-09-01

    One of the most fascinating questions in evolutionary biology is how traits unique to humans, such as their high cognitive abilities, erect bipedalism, and hairless skin, are encoded in the genome. Recent advances in genomics have begun to reveal differences between the genomes of the great apes. It has become evident that one of the many mutation types, segmental duplication, has drastically increased in the primate genomes, and most remarkably in the human genome. Genes contained in these segmental duplications have a tremendous potential to cause genetic innovation, probably accounting for the acquisition of human-specific traits. In this review, I begin with an overview of the genes, which have increased their copy number specifically in the human lineage, following its separation from the common ancestor with our closest living relative, the chimpanzee. Then, I introduce the recent experimental approaches, focusing on SRGAP2, which has been partially duplicated, to elucidate the role of SRGAP2 protein and its human-specific paralogs in human brain development and evolution.

  14. Pandora's growing box: Inferring the evolution and development of hominin brains from endocasts.

    PubMed

    Zollikofer, Christoph Peter Eduard; De León, Marcia Silvia Ponce

    2013-01-01

    The brain of modern humans is an evolutionary and developmental outlier: At birth, it has the size of an adult chimpanzee brain and expands by a factor of 2 during the first postnatal year. Large neonatal brain size and rapid initial growth contrast with slow maturation, which extends well into adolescence. When, how, and why this peculiar pattern of brain ontogeny evolved and how it is correlated with structural changes in the brain are key questions of paleoanthropology. Because brains and their ontogenies do not fossilize, indirect evidence from fossil hominin endocasts needs to be combined with evidence from modern humans and our closest living relatives, the great apes. New fossil finds permit a denser sampling of hominin endocranial morphologies along ontogenetic and evolutionary time lines. New brain imaging methods provide the basis for quantifying endocast-brain relationships and tracking endocranial and brain growth and development noninvasively. Combining this evidence with ever-more detailed knowledge about actual and fossil "brain genes," we are now beginning to understand how brain ontogeny and structure were modified during human evolution and what the adaptive significance of these modifications may have been. Copyright © 2013 Wiley Periodicals, Inc.

  15. Skeletal development in sloths and the evolution of mammalian vertebral patterning

    PubMed Central

    Hautier, Lionel; Weisbecker, Vera; Sánchez-Villagra, Marcelo R.; Goswami, Anjali; Asher, Robert J.

    2010-01-01

    Mammals show a very low level of variation in vertebral count, particularly in the neck. Phenotypes exhibited at various stages during the development of the axial skeleton may play a key role in testing mechanisms recently proposed to explain this conservatism. Here, we provide osteogenetic data that identify developmental criteria with which to recognize cervical vs. noncervical vertebrae in mammals. Except for sloths, all mammals show the late ossification of the caudal-most centra in the neck after other centra and neural arches. In sloths with 8–10 ribless neck vertebrae, the caudal-most neck centra ossify early, matching the pattern observed in cranial thoracic vertebrae of other mammals. Accordingly, we interpret the ribless neck vertebrae of three-toed sloths caudal to V7 as thoracic based on our developmental criterion. Applied to the unusual vertebral phenotype of long-necked sloths, these data support the interpretation that elements of the axial skeleton with origins from distinct mesodermal tissues have repatterned over the course of evolution. PMID:20956304

  16. Development and evolution of the female gametophyte and fertilization process in Welwitschia mirabilis (Welwitschiaceae).

    PubMed

    Friedman, William E

    2015-02-01

    The female gametophyte of Welwitschia has long been viewed as highly divergent from other members of the Gnetales and, indeed, all other seed plants. However, the formation of female gametes and the process of fertilization have never been observed. Standard histological techniques were applied to study gametophyte development and the fertilization process in Welwitschia. In Welwitschia, fertilization events occur when pollen tubes with binucleate sperm cells grow down through the nucellus and encounter prothallial tubes, free nuclear tubular extensions of the micropylar end of the female gametophyte that grow up through the nucellus. Entry of a binucleate sperm cell into a vacuolate prothallial tube appears to stimulate the rapid coagulation of cytoplasm around a single female nucleus, which differentiates into an egg cell. One sperm nucleus enters the female gamete, while the second sperm nucleus remains outside and ultimately degenerates. Only a single fertilization event occurs per mating pair of pollen tube and prothallial tube. Welwitschia lacks the gnetalean pattern of regular double fertilization, as found in Ephedra and Gnetum, involving sperm from a single pollen tube to yield two zygotes. Moreover, an analysis of character evolution indicates that the female gametophyte of Welwitschia is highly apomorphic both among seed plants, and specifically within Gnetales, but also shares several key synapomorphies with its sister taxon Gnetum. Finally, the biological role of prothallial tubes in Welwitschia is examined from the perspectives of gamete competition and kin conflict. © 2015 Botanical Society of America, Inc.

  17. Leaf venation: structure, function, development, evolution, ecology and applications in the past, present and future.

    PubMed

    Sack, Lawren; Scoffoni, Christine

    2013-06-01

    The design and function of leaf venation are important to plant performance, with key implications for the distribution and productivity of ecosystems, and applications in paleobiology, agriculture and technology. We synthesize classical concepts and the recent literature on a wide range of aspects of leaf venation. We describe 10 major structural features that contribute to multiple key functions, and scale up to leaf and plant performance. We describe the development and plasticity of leaf venation and its adaptation across environments globally, and a new global data compilation indicating trends relating vein length per unit area to climate, growth form and habitat worldwide. We synthesize the evolution of vein traits in the major plant lineages throughout paleohistory, highlighting the multiple origins of individual traits. We summarize the strikingly diverse current applications of leaf vein research in multiple fields of science and industry. A unified core understanding will enable an increasing range of plant biologists to incorporate leaf venation into their research. © 2013 The Authors New Phytologist © 2013 New Phytologist Trust.

  18. Development of the RFBB “Bargouzine” concept for Ariane-5 evolution

    NASA Astrophysics Data System (ADS)

    Sumin, Yuriy; Kostromin, Sergey F.; Panichkin, Nikolai; Prel, Yves; Osin, Mikhail; Iranzo-Greus, David; Prampolini, Marco

    2009-10-01

    This paper presents the study of a concept of Ariane-5 evolution by means of replacement of two solid-propellant boosters EAP with two liquid-propellant reusable fly-back boosters (RFBBs) called "Bargouzine". The main design feature of the reference RFBB is LOX/LH2 propellant, the canard aerodynamic configuration with delta wings and rocket engines derived from Vulcain-2 identical to that of the central core except for the nozzle length. After separation RFBBs return back by use of air breathing engines mounted in the aft part and then landing on a runway. The aim of the study is a more detailed investigation of critical technology issues concerning reliability, re-usability and maintenance requirements. The study was performed in three main phases: system trade-off, technical consolidation, and programmatic synthesis. The system trade-off includes comparative analysis of two systems with three and four engines on each RFBB and determination of the necessary thrust level taking into account thrust reservation for emergency situations. Besides, this phase contains trade-off on booster aerodynamic configurations and abort scenario analysis. The second phase includes studying of controllability during the ascent phase and separation, thermo-mechanical design, development of ground interfaces and attachment means, and turbojets engine analysis taking into account reusability.

  19. Clonal evolution in patients with chronic lymphocytic leukaemia developing resistance to BTK inhibition

    PubMed Central

    Burger, Jan A.; Landau, Dan A.; Taylor-Weiner, Amaro; Bozic, Ivana; Zhang, Huidan; Sarosiek, Kristopher; Wang, Lili; Stewart, Chip; Fan, Jean; Hoellenriegel, Julia; Sivina, Mariela; Dubuc, Adrian M.; Fraser, Cameron; Han, Yulong; Li, Shuqiang; Livak, Kenneth J.; Zou, Lihua; Wan, Youzhong; Konoplev, Sergej; Sougnez, Carrie; Brown, Jennifer R.; Abruzzo, Lynne V.; Carter, Scott L.; Keating, Michael J.; Davids, Matthew S.; Wierda, William G.; Cibulskis, Kristian; Zenz, Thorsten; Werner, Lillian; Cin, Paola Dal; Kharchencko, Peter; Neuberg, Donna; Kantarjian, Hagop; Lander, Eric; Gabriel, Stacey; O'Brien, Susan; Letai, Anthony; Weitz, David A.; Nowak, Martin A.; Getz, Gad; Wu, Catherine J.

    2016-01-01

    Resistance to the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has been attributed solely to mutations in BTK and related pathway molecules. Using whole-exome and deep-targeted sequencing, we dissect evolution of ibrutinib resistance in serial samples from five chronic lymphocytic leukaemia patients. In two patients, we detect BTK-C481S mutation or multiple PLCG2 mutations. The other three patients exhibit an expansion of clones harbouring del(8p) with additional driver mutations (EP300, MLL2 and EIF2A), with one patient developing trans-differentiation into CD19-negative histiocytic sarcoma. Using droplet-microfluidic technology and growth kinetic analyses, we demonstrate the presence of ibrutinib-resistant subclones and estimate subclone size before treatment initiation. Haploinsufficiency of TRAIL-R, a consequence of del(8p), results in TRAIL insensitivity, which may contribute to ibrutinib resistance. These findings demonstrate that the ibrutinib therapy favours selection and expansion of rare subclones already present before ibrutinib treatment, and provide insight into the heterogeneity of genetic changes associated with ibrutinib resistance. PMID:27199251

  20. Mechanisms of Long Non-coding RNAs in Mammalian Nervous System Development, Plasticity, Disease, and Evolution.

    PubMed

    Briggs, James A; Wolvetang, Ernst J; Mattick, John S; Rinn, John L; Barry, Guy

    2015-12-02

    Only relatively recently has it become clear that mammalian genomes encode tens of thousands of long non-coding RNAs (lncRNAs). A striking 40% of these are expressed specifically in the brain, where they show precisely regulated temporal and spatial expression patterns. This begs the question, what is the functional role of these many lncRNA transcripts in the brain? Here we canvass a growing number of mechanistic studies that have elucidated central roles for lncRNAs in the regulation of nervous system development and function. We also survey studies indicating that neurological and psychiatric disorders may ensue when these mechanisms break down. Finally, we synthesize these insights with evidence from comparative genomics to argue that lncRNAs may have played important roles in brain evolution, by virtue of their abundant sequence innovation in mammals and plausible mechanistic connections to the adaptive processes that occurred recently in the primate and human lineages. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Evolution of cartesian genetic programs for development of learning neural architecture.

    PubMed

    Khan, Gul Muhammad; Miller, Julian F; Halliday, David M

    2011-01-01

    Although artificial neural networks have taken their inspiration from natural neurological systems, they have largely ignored the genetic basis of neural functions. Indeed, evolutionary approaches have mainly assumed that neural learning is associated with the adjustment of synaptic weights. The goal of this paper is to use evolutionary approaches to find suitable computational functions that are analogous to natural sub-components of biological neurons and demonstrate that intelligent behavior can be produced as a result of this additional biological plausibility. Our model allows neurons, dendrites, and axon branches to grow or die so that synaptic morphology can change and affect information processing while solving a computational problem. The compartmental model of a neuron consists of a collection of seven chromosomes encoding distinct computational functions inside the neuron. Since the equivalent computational functions of neural components are very complex and in some cases unknown, we have used a form of genetic programming known as Cartesian genetic programming (CGP) to obtain these functions. We start with a small random network of soma, dendrites, and neurites that develops during problem solving by repeatedly executing the seven chromosomal programs that have been found by evolution. We have evaluated the learning potential of this system in the context of a well-known single agent learning problem, known as Wumpus World. We also examined the harder problem of learning in a competitive environment for two antagonistic agents, in which both agents are controlled by independent CGP computational networks (CGPCN). Our results show that the agents exhibit interesting learning capabilities.

  2. Heredity, evolution and development in their (epistemic) environment at the turn of the nineteenth century.

    PubMed

    Colonna, Federica Turriziani

    2016-03-01

    During the early 1870s a young zoologist who worked as a Privatdozent delivering lectures at different Prussian universities invested much of his family wealth and solicited his fellows' contributions to establish a research facility by the sea. The young zoologist happened to be called Anton Dohrn. From the time it opened its doors, the Anton Dohrn Zoological Station - or Naples Zoological Station, as it was originally called - played a crucial role in shaping life sciences as it facilitated research aimed at explaining the mechanics of inheritance. During the last quarter of the nineteenth century and the first decades of the twentieth, zoologists attempted to explain how evolutionary changes occur within a population and become stabilized. In so doing, they looked at developmental processes as well as environmental pressure, coming up with different hypotheses to explain inheritance. In some cases, their research was highly speculative, whereas in other cases they conducted cytological observations to identify the material basis of heredity. Research on evolution and development has been carried out in different places, and zoological stations like the one in Naples have played a major role in this story. However, numerous biological institutions active at the turn of the twentieth century have not received much attention from historians.

  3. The International Development Research Centre: A Guide for the Canadian University Research Community = Le Centre de recherches pour le developpement international: guide a l'intention des scientifiques des universites Canadiennes.

    ERIC Educational Resources Information Center

    Tillman, George; Wasilewski, Ania, Ed.

    Written in both English and French this is a manual for the Canadian research community. It describes the International Development Research Centre (IDRC) and its operations. The main objective of the IDRC is to assist scientists in developing countries to identify and conduct research into long term practical solutions to development problems.…

  4. Is globalization undermining the welfare state? The evolution of the welfare state in developed capitalist countries during the 1990s.

    PubMed

    Navarro, Vicente; Schmitt, John; Astudillo, Javier

    2004-01-01

    The authors analyze the evolution of macro-indicators of social and economic well-being during the 1990s in the majority of developed capitalist countries, grouped according to their dominant political traditions since the end of World War II. Their analysis shows that, despite the economic globalization of commerce and finance, "politics still matters" in explaining the evolution of the welfare states and labor markets in these countries; the impact of the globalization of financial capital in forcing reductions in the financial resources available for welfare state purposes has been exaggerated.

  5. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    NASA Astrophysics Data System (ADS)

    Savard, Stephane

    choisi, nous avons mesure les proprietes intrinseques du meme echantillon de YBa2Cu3O7- delta avec la technique pompe-visible et sonde-terahertz donnant, elle aussi, acces aux temps caracteristiques regissant l'evolution hors-equilibre de ce materiau. Dans le meilleur scenario, ces temps caracteristiques devraient correspondre a ceux evalues grace a la modelisation des antennes. Un bon controle des parametres de croissance des couches minces supraconductrices et de fabrication du dispositif nous a permis de realiser des antennes d'emission terahertz possedant d'excellentes caracteristiques en terme de largeur de bande d'emission (typiquement 3 THz) exploitables pour des applications de spectroscopie resolue dans le domaine temporel. Le modele developpe et retenu pour le lissage du spectre terahertz decrit bien les caracteristiques de l'antenne supraconductrice pour tous les parametres d'operation. Toutefois, le lien avec la technique pompe-sonde lors de la comparaison des proprietes intrinseques n'est pas direct malgre que les deux techniques montrent que le temps de relaxation des porteurs augmente pres de la temperature critique. Les donnees en pompe-sonde indiquent que la mesure du temps de relaxation depend de la frequence de la sonde, ce qui complique la correspondance des proprietes intrinseques entre les deux techniques. De meme, le temps de relaxation extrait a partir du spectre de l'antenne terahertz augmente en s'approchant de la temperature critique (T c) de YBa2Cu 3O7-delta. Le comportement en temperature du temps de relaxation correspond a une loi de puissance qui est fonction de l'inverse du gap supraconducteur avec un exposant 5 soit 1/Delta 5(T). Le travail presente dans cette these permet de mieux decrire les caracteristiques des antennes supraconductrices a haute temperature critique et de les relier aux proprietes intrinseques du materiau qui les compose. De plus, cette these presente les parametres a ajuster comme le courant applique, la puissance de

  6. Les reseaux de politique publique comme facteur d'influence du choix des instruments de politique energetique canadienne a des fins environnementales de 1993 a nos jours

    NASA Astrophysics Data System (ADS)

    Fathy El Dessouky, Naglaa

    l'agenda politique du pays. Notre projet de recherche, par le truchement de l'approche des reseaux de politique publique, s'attarde a decrire et a expliquer le processus de la formulation d'une politique particuliere, soit la politique energetique a des fins de protection de l'environnement, elaboree en 1993. Il s'agit de mettre en evidence les facteurs affectant le choix des instruments de ces politiques publiques dans leur contexte national. Ainsi, la question generale de cette recherche est: Comment les phases evolutives de la formation d'un reseau de politique, en l'occurrence le Conseil canadien de l'energie (CCE), menent a des caracteristiques particulieres a ce reseau; et comment celles-ci determinent-elles les types des instruments de politique publique choisis, particulierement ceux de la recente orientation des politiques energetiques canadiennes a des fins environnementales elaborees en 1993? Afin d'atteindre l'objectif de notre recherche, deux facteurs primordiaux sont utilises, soit la circulation de l'information et l'exercice du controle sur les ressources des acteurs. L'analyse des caracteristiques du reseau en fonction des liens forts et des liens faibles autant que la presence ou l'absence des trous structuraux nous permettent de bien identifier les positions des differents acteurs, etatiques et non etatiques, sur le plan de l'information et du controle, qui a leur tour, nous semble-t-il, constituent des facteurs affectant les types des instruments des politiques publiques choisis: instruments substantifs, qui indiquent le degre de l'intervention du gouvernement, et instruments proceduraux, qui mettent plutot l'accent sur le degre de l'influence du gouvernement sur les acteurs non etatiques. L'etude soutient que l'approche des reseaux se distingue notamment par son potentiel a expliquer l'interrelation relative entre idees, interets et institutions, ce qui a son tour est susceptible de permettre une meilleure comprehension des processus de l

  7. Groundwater evolution beneath Hat Yai, a rapidly developing city in Thailand

    NASA Astrophysics Data System (ADS)

    Lawrence, A. R.; Gooddy, D. C.; Kanatharana, P.; Meesilp, W.; Ramnarong, V.

    2000-09-01

    Many cities and towns in South and Southeast Asia are unsewered, and urban wastewaters are often discharged either directly to the ground or to surface-water canals and channels. This practice can result in widespread contamination of the shallow groundwater. In Hat Yai, southern Thailand, seepage of urban wastewaters has produced substantial deterioration in the quality of the shallow groundwater directly beneath the city. For this reason, the majority of the potable water supply is obtained from groundwater in deeper semi-confined aquifers 30-50 m below the surface. However, downward leakage of shallow groundwater from beneath the city is a significant component of recharge to the deeper aquifer, which has long-term implications for water quality. Results from cored boreholes and shallow nested piezometers are presented. The combination of high organic content of the urban recharge and the shallow depth to the water table has produced strongly reducing conditions in the upper layer and the mobilisation of arsenic. A simple analytical model shows that time scales for downward leakage, from the surface through the upper aquitard to the semi-confined aquifer, are of the order of several decades. Résumé. De nombreuses villes du sud et du sud-est de l'Asie ne possèdent pas de réseaux d'égouts et les eaux usées domestiques s'écoulent souvent directement sur le sol ou dans des canaux et des cours d'eau de surface. Ces pratiques peuvent provoquer une contamination dispersée de la nappe phréatique. A Hat Yai (sud de la Thaïlande), les infiltrations d'eaux usées domestiques sont responsables d'une détérioration notable de la qualité de la nappe phréatique directement sous la ville. Pour cette raison, la majorité de l'eau potable est prélevée dans des aquifères semi-captifs plus profonds, situés entre 30 et 50 m sous la surface. Cependant, une drainance à partir de la nappe phréatique sous la ville constitue une composante significative de la recharge

  8. DES Science Portal: Computing Photometric Redshifts

    SciTech Connect

    Gschwend, Julia

    2016-01-01

    An important challenge facing photometric surveys for cosmological purposes, such as the Dark Energy Survey (DES), is the need to produce reliable photometric redshifts (photo-z). The choice of adequate algorithms and configurations and the maintenance of an up-to-date spectroscopic database to build training sets, for example, are challenging tasks when dealing with large amounts of data that are regularly updated and constantly growing. In this paper, we present the first of a series of tools developed by DES, provided as part of the DES Science Portal, an integrated web-based data portal developed to facilitate the scientific analysis of the data, while ensuring the reproducibility of the analysis. We present the DES Science Portal photometric redshift tools, starting from the creation of a spectroscopic sample to training the neural network photo-z codes, to the final estimation of photo-zs for a large photometric catalog. We illustrate this operation by calculating well calibrated photo-zs for a galaxy sample extracted from the DES first year (Y1A1) data. The series of processes mentioned above is run entirely within the Portal environment, which automatically produces validation metrics, and maintains the provenance between the different steps. This system allows us to fine tune the many steps involved in the process of calculating photo-zs, making sure that we do not lose the information on the configurations and inputs of the previous processes. By matching the DES Y1A1 photometry to a spectroscopic sample, we define different training sets that we use to feed the photo-z algorithms already installed at the Portal. Finally, we validate the results under several conditions, including the case of a sample limited to i<22.5 with the color properties close to the full DES Y1A1 photometric data. This way we compare the performance of multiple methods and training configurations. The infrastructure presented here is an effcient way to test several methods of

  9. Grundlagen des Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Mayer, Jörg; Blum, Janaki; Wintermantel, Erich

    Die Organtransplantation stellt eine verbreitete Therapie dar, um bei krankheitsoder unfallbedingter Schädigung eines Organs die Gesamtheit seiner Funktionen wieder herzustellen, indem es durch ein Spenderorgan ersetzt wird. Organtransplantationen werden für die Leber, die Niere, die Lunge, das Herz oder bei schweren grossflächigen Verbrennungen der Haut vorgenommen. Der grosse apparative, personelle und logistische Aufwand und die Risiken der Transplantationschirurgie (Abstossungsreaktionen) sowie die mangelnde Verfügbarkeit von immunologisch kompatiblen Spenderorganen führen jedoch dazu, dass der Bedarf an Organtransplantaten nur zu einem sehr geringen Teil gedeckt werden kann. Sind Spenderorgane nicht verfügbar, können in einzelnen Fällen lebenswichtige Teilfunktionen, wie beispielsweise die Filtrationsfunktion der Niere durch die Blutreinigung mittels Dialyse ersetzt oder, bei mangelnder Funktion der Bauchspeicheldrüse (Diabetes), durch die Verabreichung von Insulin ein normaler Zustand des Gesamtorganismus auch über Jahre hinweg erhalten werden. Bei der notwendigen lebenslangen Anwendung apparativer oder medikamentöser Therapie können für den Patienten jedoch häufig schwerwiegende, möglicherweise lebensverkürzende Nebenwirkungen entstehen. Daher werden in der Forschung Alternativen gesucht, um die Funktionen des ausgefallenen Organs durch die Implantation von Zellen oder in vitro gezüchteten Geweben möglichst umfassend wieder herzustellen. Dies erfordert biologisch aktive Implantate, welche die für den Stoffwechsel des Organs wichtigen Zellen enthalten und einen organtypischen Stoffwechsel entfalten.

  10. Development and evolution of dentition pattern and tooth order in the skates and rays (batoidea; chondrichthyes).

    PubMed

    Underwood, Charlie J; Johanson, Zerina; Welten, Monique; Metscher, Brian; Rasch, Liam J; Fraser, Gareth J; Smith, Moya Meredith

    2015-01-01

    Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the

  11. Adaptive evolution of the Hox gene family for development in bats and dolphins.

    PubMed

    Liang, Lu; Shen, Yong-Yi; Pan, Xiao-Wei; Zhou, Tai-Cheng; Yang, Chao; Irwin, David M; Zhang, Ya-Ping

    2013-01-01

    Bats and cetaceans (i.e., whales, dolphins, porpoises) are two kinds of mammals with unique locomotive styles and occupy novel niches. Bats are the only mammals capable of sustained flight in the sky, while cetaceans have returned to the aquatic environment and are specialized for swimming. Associated with these novel adaptations to their environment, various development changes have occurred to their body plans and associated structures. Given the importance of Hox genes in many aspects of embryonic development, we conducted an analysis of the coding regions of all Hox gene family members from bats (represented by Pteropus vampyrus, Pteropus alecto, Myotis lucifugus and Myotis davidii) and cetaceans (represented by Tursiops truncatus) for adaptive evolution using the available draft genome sequences. Differences in the selective pressures acting on many Hox genes in bats and cetaceans were found compared to other mammals. Positive selection, however, was not found to act on any of the Hox genes in the common ancestor of bats and only upon Hoxb9 in cetaceans. PCR amplification data from additional bat and cetacean species, and application of the branch-site test 2, showed that the Hoxb2 gene within bats had significant evidence of positive selection. Thus, our study, with genomic and newly sequenced Hox genes, identifies two candidate Hox genes that may be closely linked with developmental changes in bats and cetaceans, such as those associated with the pancreatic, neuronal, thymus shape and forelimb. In addition, the difference in our results from the genome-wide scan and newly sequenced data reveals that great care must be taken in interpreting results from draft genome data from a limited number of species, and deep genetic sampling of a particular clade is a powerful tool for generating complementary data to address this limitation.

  12. Adaptive Evolution of the Hox Gene Family for Development in Bats and Dolphins

    PubMed Central

    Pan, Xiao-Wei; Zhou, Tai-Cheng; Yang, Chao; Irwin, David M.; Zhang, Ya-Ping

    2013-01-01

    Bats and cetaceans (i.e., whales, dolphins, porpoises) are two kinds of mammals with unique locomotive styles and occupy novel niches. Bats are the only mammals capable of sustained flight in the sky, while cetaceans have returned to the aquatic environment and are specialized for swimming. Associated with these novel adaptations to their environment, various development changes have occurred to their body plans and associated structures. Given the importance of Hox genes in many aspects of embryonic development, we conducted an analysis of the coding regions of all Hox gene family members from bats (represented by Pteropus vampyrus, Pteropus alecto, Myotis lucifugus and Myotis davidii) and cetaceans (represented by Tursiops truncatus) for adaptive evolution using the available draft genome sequences. Differences in the selective pressures acting on many Hox genes in bats and cetaceans were found compared to other mammals. Positive selection, however, was not found to act on any of the Hox genes in the common ancestor of bats and only upon Hoxb9 in cetaceans. PCR amplification data from additional bat and cetacean species, and application of the branch-site test 2, showed that the Hoxb2 gene within bats had significant evidence of positive selection. Thus, our study, with genomic and newly sequenced Hox genes, identifies two candidate Hox genes that may be closely linked with developmental changes in bats and cetaceans, such as those associated with the pancreatic, neuronal, thymus shape and forelimb. In addition, the difference in our results from the genome-wide scan and newly sequenced data reveals that great care must be taken in interpreting results from draft genome data from a limited number of species, and deep genetic sampling of a particular clade is a powerful tool for generating complementary data to address this limitation. PMID:23825528

  13. The evolution of spinnable cotton fiber entailed prolonged development and a novel metabolism.

    PubMed

    Hovav, Ran; Udall, Joshua A; Chaudhary, Bhupendra; Hovav, Einat; Flagel, Lex; Hu, Guanjing; Wendel, Jonathan F

    2008-02-01

    A central question in evolutionary biology concerns the developmental processes by which new phenotypes arise. An exceptional example of evolutionary innovation is the single-celled seed trichome in Gossypium ("cotton fiber"). We have used fiber development in Gossypium as a system to understand how morphology can rapidly evolve. Fiber has undergone considerable morphological changes between the short, tightly adherent fibers of G. longicalyx and the derived long, spinnable fibers of its closest relative, G. herbaceum, which facilitated cotton domestication. We conducted comparative gene expression profiling across a developmental time-course of fibers from G. longicalyx and G. herbaceum using microarrays with approximately 22,000 genes. Expression changes between stages were temporally protracted in G. herbaceum relative to G. longicalyx, reflecting a prolongation of the ancestral developmental program. Gene expression and GO analyses showed that many genes involved with stress responses were upregulated early in G. longicalyx fiber development. Several candidate genes upregulated in G. herbaceum have been implicated in regulating redox levels and cell elongation processes. Three genes previously shown to modulate hydrogen peroxide levels were consistently expressed in domesticated and wild cotton species with long fibers, but expression was not detected by quantitative real time-PCR in wild species with short fibers. Hydrogen peroxide is important for cell elongation, but at high concentrations it becomes toxic, activating stress processes that may lead to early onset of secondary cell wall synthesis and the end of cell elongation. These observations suggest that the evolution of long spinnable fibers in cotton was accompanied by novel expression of genes assisting in the regulation of reactive oxygen species levels. Our data suggest a model for the evolutionary origin of a novel morphology through differential gene regulation causing prolongation of an ancestral

  14. Multi-class computational evolution: development, benchmark evaluation and application to RNA-Seq biomarker discovery.

    PubMed

    Crabtree, Nathaniel M; Moore, Jason H; Bowyer, John F; George, Nysia I

    2017-01-01

    A computational evolution system (CES) is a knowledge discovery engine that can identify subtle, synergistic relationships in large datasets. Pareto optimization allows CESs to balance accuracy with model complexity when evolving classifiers. Using Pareto optimization, a CES is able to identify a very small number of features while maintaining high classification accuracy. A CES can be designed for various types of data, and the user can exploit expert knowledge about the classification problem in order to improve discrimination between classes. These characteristics give CES an advantage over other classification and feature selection algorithms, particularly when the goal is to identify a small number of highly relevant, non-redundant biomarkers. Previously, CESs have been developed only for binary class datasets. In this study, we developed a multi-class CES. The multi-class CES was compared to three common feature selection and classification algorithms: support vector machine (SVM), random k-nearest neighbor (RKNN), and random forest (RF). The algorithms were evaluated on three distinct multi-class RNA sequencing datasets. The comparison criteria were run-time, classification accuracy, number of selected features, and stability of selected feature set (as measured by the Tanimoto distance). The performance of each algorithm was data-dependent. CES performed best on the dataset with the smallest sample size, indicating that CES has a unique advantage since the accuracy of most classification methods suffer when sample size is small. The multi-class extension of CES increases the appeal of its application to complex, multi-class datasets in order to identify important biomarkers and features.

  15. Dynamical patterning modules: a "pattern language" for development and evolution of multicellular form.

    PubMed

    Newman, Stuart A; Bhat, Ramray

    2009-01-01

    This article considers the role played by a core set of "dynamical patterning modules" (DPMs) in the origination, development and evolution of complex organisms. These consist of the products of a subset of the genes of what has come to be known as the "developmental-genetic toolkit" in association with physical processes they mobilize. The physical processes are those characteristic of chemically and mechanically excitable mesoscopic systems like cell aggregates: cohesion, viscoelasticity, diffusion, spatiotemporal heterogeneity based on activator-inhibitor interaction, and multistable and oscillatory dynamics. We focus on the emergence of the Metazoa, and show how toolkit gene products and pathways that pre-existed the metazoans acquired novel morphogenetic functions simply by virtue of the change in scale and context inherent to multicellularity. We propose that DPMs, acting singly and in combination with each other, constitute a "pattern language" capable of generating all metazoan body plans and organ forms. This concept implies that the multicellular organisms of the late Precambrian-early Cambrian were phenotypically plastic, fluently exploring morphospace in a fashion decoupled from both function-based selection and genotypic change. The relatively stable developmental trajectories and morphological phenotypes of modern organisms, then, are considered to be products of stabilizing selection. This perspective solves the apparent "molecular homology-analogy paradox," whereby widely divergent modern animal types utilize the same molecular toolkit during development, but it does so by inverting the neo-Darwinian principle that phenotypic disparity was generated over long periods of time in concert with, and in proportion to genotypic change.

  16. Development and Evolution of Dentition Pattern and Tooth Order in the Skates And Rays (Batoidea; Chondrichthyes)

    PubMed Central

    Underwood, Charlie J.; Johanson, Zerina; Welten, Monique; Metscher, Brian; Rasch, Liam J.; Fraser, Gareth J.; Smith, Moya Meredith

    2015-01-01

    Shark and ray (elasmobranch) dentitions are well known for their multiple generations of teeth, with isolated teeth being common in the fossil record. However, how the diverse dentitions characteristic of elasmobranchs form is still poorly understood. Data on the development and maintenance of the dental patterning in this major vertebrate group will allow comparisons to other morphologically diverse taxa, including the bony fishes, in order to identify shared pattern characters for the vertebrate dentition as a whole. Data is especially lacking from the Batoidea (skates and rays), hence our objective is to compile data on embryonic and adult batoid tooth development contributing to ordering of the dentition, from cleared and stained specimens and micro-CT scans, with 3D rendered models. We selected species (adult and embryonic) spanning phylogenetically significant batoid clades, such that our observations may raise questions about relationships within the batoids, particularly with respect to current molecular-based analyses. We include developmental data from embryos of recent model organisms Leucoraja erinacea and Raja clavata to evaluate the earliest establishment of the dentition. Characters of the batoid dentition investigated include alternate addition of teeth as offset successional tooth rows (versus single separate files), presence of a symphyseal initiator region (symphyseal tooth present, or absent, but with two parasymphyseal teeth) and a restriction to tooth addition along each jaw reducing the number of tooth families, relative to addition of successor teeth within each family. Our ultimate aim is to understand the shared characters of the batoids, and whether or not these dental characters are shared more broadly within elasmobranchs, by comparing these to dentitions in shark outgroups. These developmental morphological analyses will provide a solid basis to better understand dental evolution in these important vertebrate groups as well as the

  17. Catalog Production for the DES Blind Cosmology Challenge

    NASA Astrophysics Data System (ADS)

    Busha, Michael T.; Wechsler, R. H.; Becker, M. R.; Erickson, B.; Evrard, A. E.

    2013-01-01

    The Blind Cosmology Challenge (BCC) is an effort by the Dark Energy Survey (DES) to test analysis tools for extracting cosmological information using a set of detailed synthetic galaxy catalogs. Here, we describe the creation of these synthetic sky catalogs based on requirements of the optical (DES) and the near-IR VISTA Hemisphere Survey, producing catalogs covering a quarter of the sky to z ˜ 2, with sources complete to r ˜ 25. Starting with a nested set of lightcone outputs of large, N-body simulation, galaxies are assigned to the dark matter distribution using an empirical algorithm that is tunable to match observed evolution of low-order galaxy population properties (counts and spatial clustering) in luminosity-color-density space. Galaxies are lensed by matter along the line of sight (including magnification, shape distortion, and multiple images), using a new algorithm that calculates shear with 3.22 arcsec resolution at galaxy positions in the full catalog. The catalog is well suited to support DES+VISTA joint studies of galaxy clustering, groups and clusters of galaxies, and gravitational lensing, and we highlight their application to the ongoing DES BBCC. Catalogs include ˜320 million galaxies and ˜150 million stars, with realistic colors, shapes and photometric errors. Using the expected DES photometric errors, three independent photometric redshift codes are run on the catalog, two of which produce full probability distributions. The synthetic observable catalog includes object position, magnitudes in the DES and VISTA bands, photometric errors, photometric redshifts, size, ellipticity, for each of ˜ 500 million objects. The galaxy distribution is additionally masked appropriately for the 5000 square degree DES footprint, including the impact of bright stars. In addition, we offer separate catalogs with magnitudes for additional existing and planned surveys, including SDSS, CFHTLS, HSC, LSST, and Euclid.

  18. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

    Pour faire face à la crise économique la conception de papier à valeur ajoutée est développée par les industries papetières. Le but de se projet est l'amélioration des techniques actuelles de réticulation des fibres lignocellulosiques de la pâte à papier visant à produire un papier plus résistant. En effet, lors des réactions de réticulation traditionnelles, de nombreuses liaisons intra-fibres se forment ce qui affecte négativement l'amélioration anticipée des propriétés physiques du papier ou du matériau produit. Pour éviter la formation de ces liaisons intra-fibres, un greffage sur les fibres de groupements ne pouvant pas réagir entre eux est nécessaire. La réticulation des fibres par une réaction de « click chemistry » appelée cycloaddition de Huisgen entre un azide et un alcyne vrai, catalysée par du cuivre (CuAAC) a été l'une des solutions trouvée pour remédier à ce problème. De plus, une adaptation de cette réaction en milieux aqueux pourrait favoriser son utilisation en milieu industriel. L'étude que nous désirons entreprendre lors de ce projet vise à optimiser la réaction de CuAAC et les réactions intermédiaires (propargylation, tosylation et azidation) sur la pâte kraft, en milieu aqueux. Pour cela, les réactions ont été adaptées en milieu aqueux sur la cellulose microcristalline afin de vérifier sa faisabilité, puis transférée à la pâte kraft et l'influence de différents paramètres comme le temps de réaction ou la quantité de réactifs utilisée a été étudiée. Dans un second temps, une étude des différentes propriétés conférées au papier par les réactions a été réalisée à partir d'une série de tests papetiers optiques et physiques. Mots Clés Click chemistry, Huisgen, CuAAC, propargylation, tosylation, azidation, cellulose, pâte kraft, milieu aqueux, papier.

  19. La diffraction des neutrons et des rayons X pour l'étude structurale des liquides et des verres

    NASA Astrophysics Data System (ADS)

    Fischer, H. E.; Salmon, P. S.; Barnes, A. C.

    2003-02-01

    La compréhension de mainte propriété physique d'un verre ou d'un liquide nécessite la connaissance des facteurs de structure partiels (PSFs) qui décrivent chacun la distribution d'une espèce atomique autour d'une autre. La technique de diffraction des neutrons avec substitution isotopique (NDIS) [1,2,3], ayant bien réussi a déterminer les PSFs de certains composés [4,5], est pourtant restreinte aux isotopes présentant un contraste suffisant en longueur de diffusion. D'un autre cote, la technique de diffusion anomale des rayons X (AXS ou AXD) [6] permet de faire varier la longueur de diffusion d'une espèce atomique pourvu que son énergie d'absorption soit à la fois accessible et suffisamment élevée pour donner un assez grand transfert du moment. La combinaison des techniques de diffraction des neutrons (avec ou sans substitution isotopique) et de diffraction des rayons X (avec ou sans diffusion anomale) peut donc permettre d'obtenir un meilleur contraste en longueurs de diffusion pour un système donné, mais exige une analyse de données plus soignée pour pouvoir bien tenir compte des erreurs systématiques qui sont différentes pour les 2 techniques [7]. Pour les atomes ayant des distributions électroniques quasi-sphériques, e.g. dans le cas d'un alliage liquide, la combinaison des techniques de NDIS et de diffraction des rayons X s'est déjà montrée très avantageuse pour la détermination des PSFs [8,9]. Dans le cas des verres ayant d'importantes liaisons covalentes, l'effective combinaison des 2 techniques peut être moins directe mais facilitée lorsqu'il s'agit des atomes de grand Z [10,11]. Nous présentons ici un sommaire du méthode et quelques exemples des résultats.

  20. Peste des Petits Ruminants Virus.

    PubMed

    Baron, M D; Diallo, A; Lancelot, R; Libeau, G

    2016-01-01

    Peste des petits ruminants virus (PPRV) causes a severe contagious disease of sheep and goats and has spread extensively through the developing world. Because of its disproportionately large impact on the livelihoods of low-income livestock keepers, and the availability of effective vaccines and good diagnostics, the virus is being targeted for global control and eventual eradication. In this review we examine the origin of the virus and its current distribution, and the factors that have led international organizations to conclude that it is eradicable. We also review recent progress in the molecular and cellular biology of the virus and consider areas where further research is required to support the efforts being made by national, regional, and international bodies to tackle this growing threat.

  1. Analogue and numerical modelling in Volcanology: Development, evolution and future challenges

    NASA Astrophysics Data System (ADS)

    Kavanagh, Janine; Annen, Catherine

    2015-04-01

    Since the inception of volcanology as a science, analogue modelling has been an important methodology to study the formation and evolution of the volcanic system. With the development of computing capacities numerical modelling has become a widely used tool to explore magmatic process quantitatively and try to predict eruptive behaviour. Processes of interest include the development and establishment of the volcanic plumbing system, the propagation of magma to the surface to feed eruptions, the construction of a volcanic edifice and the dynamics of eruptive processes. An important ultimate aim is to characterise and measure the experimental volcanic and magmatic phenomena, to inform and improve eruption forecasting for hazard assessments. In nature, volcanic activity is often unpredictable and in an environment that is highly changeable and forbidding. Volcanic or magmatic activity cannot be repeated at will and has many (often unconstrained) variables. The processes of interest are frequently hidden from view, for example occurring beneath the Earth's surface or within a pyroclastic flow or plume. The challenges of working in volcanic terrains and gathering 'real' volcano data mean that analogue and numerical models have gained significant importance as a method to study the geometrics, kinematics, and dynamics of volcano growth and eruption. A huge variety of analogue materials have been used in volcanic modelling, often bringing out the more creative side of the scientific mind. As with all models, the choice of appropriate materials and boundary conditions are critical for assessing the relevance and usefulness of the experimental results. Numerical simulation has proved a useful tool to test the physical plausibility of conceptual models and presents the advantage of being applicable at different scales. It is limited however in its predictive power by the number of free parameters needed to describe geological systems. In this special symposium we will

  2. Forest Ecosystem Processes at the Watershed Scale: Ecosystem services, feedback and evolution in developing mountainous catchments

    NASA Astrophysics Data System (ADS)

    Band, Larry

    2010-05-01

    Mountain watersheds provide significant ecosystem services both locally and for surrounding regions, including the provision of freshwater, hydropower, carbon sequestration, habitat, forest products and recreational/aesthetic opportunities. The hydrologic connectivity along hillslopes in sloping terrain provides an upslope subsidy of water and nutrients to downslope ecosystem patches, producing characteristic ecosystem patterns of vegetation density and type, and soil biogeochemical cycling. Recent work suggests that optimal patterns of forest cover evolve along these flowpaths which maximize net primary productivity and carbon sequestration at the hillslope to catchment scale. These watersheds are under significant pressure from potential climate change, changes in forest management, increasing population and development, and increasing demand for water export. As water balance and flowpaths are altered by shifting weather patterns and new development, the spatial distribution and coupling of water, carbon and nutrient cycling will spur the evolution of different ecosystem patterns. These issues have both theoretical and practical implications for the coupling of water, carbon and nutrient cycling at the landscape level, and the potential to manage watersheds for bundled ecosystem services. If the spatial structure of the ecosystem spontaneously adjusts to maximize landscape level use of limiting resources, there may be trade-offs in the level of services provided. The well known carbon-for-water tradeoff reflects the growth of forests to maximize carbon uptake, but also transpiration which limits freshwater availability in many biomes. We provide examples of the response of bundled ecosystem services to climate and land use change in the Southern Appalachian Mountains of the United States. These mountains have very high net primary productivity, biodiversity and water yields, and provide significant freshwater resources to surrounding regions. There has been a

  3. Genomics: disclose the influence of human specific genetic variation on the evolution and development of cerebral cortex.

    PubMed

    Maomao, Pu; Jun, Yao; Xin, Cao

    2016-11-20

    Cerebral cortex, whose complexity of structure and function has derived from human specific genetic variation, is the most advanced nerve center of human, controlling the cognitive ability which distinguishes human from any other creatures. Using genomics technology, molecular mechanisms of cerebral cortex development and evolution have been disclosed. In this review, we summarize how genomics technologies are used in exploring the influence of human specific genetic variation on cerebral cortex development and evolution, including the genomics methods to study the gene expression differences among the cerebral cortex of human beings, chimpanzee and other mammals; as well as the role of the significant non-coding regulatory sequences-human accelerated regions (HARs) in the process of brain development. We also discuss the future research trends on the human specific genetic variation in the field of neurobiology.

  4. Ancient homeobox gene loss and the evolution of chordate brain and pharynx development: deductions from amphioxus gene expression.

    PubMed

    Butts, Thomas; Holland, Peter W H; Ferrier, David E K

    2010-11-22

    Homeobox genes encode a large superclass of transcription factors with widespread roles in animal development. Within chordates there are over 100 homeobox genes in the invertebrate cephalochordate amphioxus and over 200 in humans. Set against this general trend of increasing gene number in vertebrate evolution, some ancient homeobox genes that were present in the last common ancestor of chordates have been lost from vertebrates. Here, we describe the embryonic expression of four amphioxus descendants of these genes--AmphiNedxa, AmphiNedxb, AmphiMsxlx and AmphiNKx7. All four genes are expressed with a striking asymmetry about the left-right axis in the pharyngeal region of neurula embryos, mirroring the pronounced asymmetry of amphioxus embryogenesis. AmphiMsxlx and AmphiNKx7 are also transiently expressed in an anterior neural tube region destined to become the cerebral vesicle. These findings suggest significant rewiring of developmental gene regulatory networks occurred during chordate evolution, coincident with homeobox gene loss. We propose that loss of otherwise widely conserved genes is possible when these genes function in a confined role in development that is subsequently lost or significantly modified during evolution. In the case of these homeobox genes, we propose that this has occurred in relation to the evolution of the chordate pharynx and brain.

  5. Development of bat flight: morphologic and molecular evolution of bat wing digits.

    PubMed

    Sears, Karen E; Behringer, Richard R; Rasweiler, John J; Niswander, Lee A

    2006-04-25

    The earliest fossil bats resemble their modern counterparts in possessing greatly elongated digits to support the wing membrane, which is an anatomical hallmark of powered flight. To quantitatively confirm these similarities, we performed a morphometric analysis of wing bones from fossil and modern bats. We found that the lengths of the third, fourth, and fifth digits (the primary supportive elements of the wing) have remained constant relative to body size over the last 50 million years. This absence of transitional forms in the fossil record led us to look elsewhere to understand bat wing evolution. Investigating embryonic development, we found that the digits in bats (Carollia perspicillata) are initially similar in size to those of mice (Mus musculus) but that, subsequently, bat digits greatly lengthen. The developmental timing of the change in wing digit length points to a change in longitudinal cartilage growth, a process that depends on the relative proliferation and differentiation of chondrocytes. We found that bat forelimb digits exhibit relatively high rates of chondrocyte proliferation and differentiation. We show that bone morphogenetic protein 2 (Bmp2) can stimulate cartilage proliferation and differentiation and increase digit length in the bat embryonic forelimb. Also, we show that Bmp2 expression and Bmp signaling are increased in bat forelimb embryonic digits relative to mouse or bat hind limb digits. Together, our results suggest that an up-regulation of the Bmp pathway is one of the major factors in the developmental elongation of bat forelimb digits, and it is potentially a key mechanism in their evolutionary elongation as well.

  6. Development of bat flight: Morphologic and molecular evolution of bat wing digits

    PubMed Central

    Sears, Karen E.; Behringer, Richard R.; Rasweiler, John J.; Niswander, Lee A.

    2006-01-01

    The earliest fossil bats resemble their modern counterparts in possessing greatly elongated digits to support the wing membrane, which is an anatomical hallmark of powered flight. To quantitatively confirm these similarities, we performed a morphometric analysis of wing bones from fossil and modern bats. We found that the lengths of the third, fourth, and fifth digits (the primary supportive elements of the wing) have remained constant relative to body size over the last 50 million years. This absence of transitional forms in the fossil record led us to look elsewhere to understand bat wing evolution. Investigating embryonic development, we found that the digits in bats (Carollia perspicillata) are initially similar in size to those of mice (Mus musculus) but that, subsequently, bat digits greatly lengthen. The developmental timing of the change in wing digit length points to a change in longitudinal cartilage growth, a process that depends on the relative proliferation and differentiation of chondrocytes. We found that bat forelimb digits exhibit relatively high rates of chondrocyte proliferation and differentiation. We show that bone morphogenetic protein 2 (Bmp2) can stimulate cartilage proliferation and differentiation and increase digit length in the bat embryonic forelimb. Also, we show that Bmp2 expression and Bmp signaling are increased in bat forelimb embryonic digits relative to mouse or bat hind limb digits. Together, our results suggest that an up-regulation of the Bmp pathway is one of the major factors in the developmental elongation of bat forelimb digits, and it is potentially a key mechanism in their evolutionary elongation as well. PMID:16618938

  7. Structural Evolution and Fracture Development of Chinshui Anticline in a Fold-and-Thrust Belt, Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, T. W.; Hu, J. C.; Huang, S. T.

    2016-12-01

    Hsinchu-Miaoli area is the major hydrocarbon producing fields in the fold-and-thrust belt of Taiwan. To understand the nature and the geometry of the reservoirs in this area, 82 wells were drilled in the Chinshui Field, which is one of the important gas fields in the Hsinchu-Miaoli area. However, the subsurface structures and fracture distribution of these fields are still unclear, and the reason for long time producing is also unknown. Fractures in the oil-bearing reservoir might be one of the important factors of long time gas producing, but the fracture reservoirs attaining hydrocarbons associated with fault-related folding need to be further clarified. In this study, we first represent a new structural interpretation of Chinshui anticlines and adjacent structures by a geological cross section across from Miaoli offshore to inner western foothills. After conducting 2D restoration with 2DMove, we could test whether our structural interpretation is reasonable and clarify the evolution history of Chinshui anticline and adjacent structures. We further construct a 3D structural model of Chinshui anticline by GOCAD. By using surface restoration, the location with higher fracture density could be inferred and be taken into account for reproduction. According to the restoration, we conclude that Chinshui anticline is mainly formed by the movement of the deep detachment. The old strata between two detachments develop a thrust wedge and deform upper strata to form Chinshui anticline. Furthermore, we obtain strain fields and the extension areas of Talu shale, Tungkeng, Chuhaungkeng, Mushan and Wuchihshan Formation of Chinshui anticline during the deformation. The results reveal that the highest fracture density lies in the hinge of A and C blocks in Mushan Formation as well as the hinge of B block in Wuchihshan Formation. After comparing the curvature and strain fields of these surfaces, we also find out that the strain field is highly relevant to the curvature of Chinshui

  8. Dynamical patterning modules: physico-genetic determinants of morphological development and evolution

    NASA Astrophysics Data System (ADS)

    Newman, Stuart A.; Bhat, Ramray

    2008-03-01

    The shapes and forms of multicellular organisms arise by the generation of new cell states and types and changes in the numbers and rearrangements of the various kinds of cells. While morphogenesis and pattern formation in all animal species are widely recognized to be mediated by the gene products of an evolutionarily conserved 'developmental-genetic toolkit', the link between these molecular players and the physics underlying these processes has been generally ignored. This paper introduces the concept of 'dynamical patterning modules' (DPMs), units consisting of one or more products of the 'toolkit' genes that mobilize physical processes characteristic of chemically and mechanically excitable meso- to macroscopic systems such as cell aggregates: cohesion, viscoelasticity, diffusion, spatiotemporal heterogeneity based on lateral inhibition and multistable and oscillatory dynamics. We suggest that ancient toolkit gene products, most predating the emergence of multicellularity, assumed novel morphogenetic functions due to change in the scale and context inherent to multicellularity. We show that DPMs, acting individually and in concert with each other, constitute a 'pattern language' capable of generating all metazoan body plans and organ forms. The physical dimension of developmental causation implies that multicellular forms during the explosive radiation of animal body plans in the middle Cambrian, approximately 530 million years ago, could have explored an extensive morphospace without concomitant genotypic change or selection for adaptation. The morphologically plastic body plans and organ forms generated by DPMs, and their ontogenetic trajectories, would subsequently have been stabilized and consolidated by natural selection and genetic drift. This perspective also solves the apparent 'molecular homology-analogy paradox', whereby widely divergent modern animal types utilize the same molecular toolkit during development by proposing, in contrast to the Neo

  9. Des Regles et du Jeu. Complementarite des facteurs genetiques et epigenetiques dans le developpement cerebral (Of Rules and of Play. The Complementary Nature of Genetic and Epigenetic Factors in Brain Development).

    ERIC Educational Resources Information Center

    Lambert, Jean-Francois

    1997-01-01

    Discusses the importance of genetic and epigenetic factors in the development of the nervous system and the performances it conditions. From the perspective of rules, play, and relaxation of rules, learning and education are not considered as a kind of conditioning but as providing a content in which the cumulative expression of potential can take…

  10. Des Regles et du Jeu. Complementarite des facteurs genetiques et epigenetiques dans le developpement cerebral (Of Rules and of Play. The Complementary Nature of Genetic and Epigenetic Factors in Brain Development).

    ERIC Educational Resources Information Center

    Lambert, Jean-Francois

    1997-01-01

    Discusses the importance of genetic and epigenetic factors in the development of the nervous system and the performances it conditions. From the perspective of rules, play, and relaxation of rules, learning and education are not considered as a kind of conditioning but as providing a content in which the cumulative expression of potential can take…

  11. Recursive causality in evolution: a model for epigenetic mechanisms in cancer development.

    PubMed

    Haslberger, A; Varga, F; Karlic, H

    2006-01-01

    Interactions between adaptative and selective processes are illustrated in the model of recursive causality as defined in Rupert Riedl's systems theory of evolution. One of the main features of this theory also termed as theory of evolving complexity is the centrality of the notion of 'recursive' or 'feedback' causality - 'the idea that every biological effect in living systems, in some way, feeds back to its own cause'. Our hypothesis is that "recursive" or "feedback" causality provides a model for explaining the consequences of interacting genetic and epigenetic mechanisms which are known to play a key role in development of cancer. Epigenetics includes any process that alters gene activity without changes of the DNA sequence. The most important epigenetic mechanisms are DNA-methylation and chromatin remodeling. Hypomethylation of so-called oncogenes and hypermethylation of tumor suppressor genes appear to be critical determinants of cancer. Folic acid, vitamin B12 and other nutrients influence the function of enzymes that participate in various methylation processes by affecting the supply of methyl groups into a variety of molecules which may be directly or indirectly associated with cancerogenesis. We present an example from our own studies by showing that vitamin D3 has the potential to de-methylate the osteocalcin-promoter in MG63 osteosarcoma cells. Consequently, a stimulation of osteocalcin synthesis can be observed. The above mentioned enzymes also play a role in development and differentiation of cells and organisms and thus illustrate the close association between evolutionary and developmental mechanisms. This enabled new ways to understand the interaction between the genome and environment and may improve biomedical concepts including environmental health aspects where epigenetic and genetic modifications are closely associated. Recent observations showed that methylated nucleotides in the gene promoter may serve as a target for solar UV

  12. Adaptive evolution of Desulfovibrio alaskensis G20 for developing resistance to perchlorate

    NASA Astrophysics Data System (ADS)

    Mehta-Kolte, M. G.; Youngblut, M.; Redford, S.; Gregoire, P.; Carlson, H. K.; Coates, J. D.

    2015-12-01

    Due to its toxic, explosive, and corrosive nature, inadvertent biological H2S production by sulfate reducing microorganisms (SRM) poses significant health and industrial operational risks. Anthropogenic sources are dominated by the oil industry where H2S in reservoir gases and fluids has an associated annual cost estimated at $90 billion globally. Our previous studies have identified perchlorate (ClO4-) as a selective and potent inhibitor of SRM in pure culture and complex microbial ecosystems. However, constant addition of inhibitors like perchlorate to natural ecosystems may result in a new adaptive selective pressure on SRM populations. With this in mind we investigated the ability of Desulfovibrio alaskensis G20, a model oil reservoir SRM, to adapt to perchlorate and develop a resistance. Serial transfers of three parallel cultures with increasing concentrations of perchlorate up to 100 mM were generated and compared to wild-type strains that were transferred for same number of generations in absence of perchlorate. Genome sequencing revealed that all three adapted strains had single non-synonymous single-nucleotide polymorphisms in the same gene, Dde_2265, the sulfate adenylytransferase (ATP sulfurylase (ATPS)) (EC 2.7.7.4). ATPS catalyzes the first committed step in sulfate reduction and is essential in all SRM. IC50s against growth for these evolved strains demonstrated a three-fold increased resistance to perchlorate compared to wild-type controls. These evolved strains also had 5x higher transcriptional abundance of Dde_2265 compared to the wild-type strain. Biochemical characterization of the purified ATPS enzyme from both wild-type and the evolved strain showed that the mutant ATPS from the evolved strain was resistant to perchlorate inhibition of ATP turnover with a KI for perchlorate that was 3x greater relative to the wild-type ATPS. These results demonstrate that a single-base pair mutation in ATPS can have a significant impact on developing

  13. The Parental Non-Equivalence of Imprinting Control Regions during Mammalian Development and Evolution

    PubMed Central

    Bestor, Timothy H.; Woodfine, Kathryn; Lin, Chyuan-Sheng; Lin, Shau-Ping; Prissette, Marine; Oakey, Rebecca J.; Bourc'his, Déborah

    2010-01-01

    In mammals, imprinted gene expression results from the sex-specific methylation of imprinted control regions (ICRs) in the parental germlines. Imprinting is linked to therian reproduction, that is, the placenta and imprinting emerged at roughly the same time and potentially co-evolved. We assessed the transcriptome-wide and ontology effect of maternally versus paternally methylated ICRs at the developmental stage of setting of the chorioallantoic placenta in the mouse (8.5dpc), using two models of imprinting deficiency including completely imprint-free embryos. Paternal and maternal imprints have a similar quantitative impact on the embryonic transcriptome. However, transcriptional effects of maternal ICRs are qualitatively focused on the fetal-maternal interface, while paternal ICRs weakly affect non-convergent biological processes, with little consequence for viability at 8.5dpc. Moreover, genes regulated by maternal ICRs indirectly influence genes regulated by paternal ICRs, while the reverse is not observed. The functional dominance of maternal imprints over early embryonic development is potentially linked to selection pressures favoring methylation-dependent control of maternal over paternal ICRs. We previously hypothesized that the different methylation histories of ICRs in the maternal versus the paternal germlines may have put paternal ICRs under higher mutational pressure to lose CpGs by deamination. Using comparative genomics of 17 extant mammalian species, we show here that, while ICRs in general have been constrained to maintain more CpGs than non-imprinted sequences, the rate of CpG loss at paternal ICRs has indeed been higher than at maternal ICRs during evolution. In fact, maternal ICRs, which have the characteristics of CpG-rich promoters, have gained CpGs compared to non-imprinted CpG-rich promoters. Thus, the numerical and, during early embryonic development, functional dominance of maternal ICRs can be explained as the consequence of two

  14. [Evolution and new perspectives of health care financing in developing countries].

    PubMed

    Audibert, Martine; Mathonnat, Jacky; de Roodenbeke, Eric

    2003-01-01

    a better management of resources through financing mechanisms. Some major reports from WHO and the World Bank are the landmarks of the evolution on how to approach health care financing: The 1993 World Bank report on investing in health, the 2000 WHO report on health in the world and the WHO report on macroeconomics and health. In this early millenium, there is a general agreement on some major aspects of health care financing such as: Lack of resources for financing health care; cost recovery as a part of any sustainable health care system; health as a public good needing some extended subsidies; protecting people from the burden of disease as a part of financing schemes; equity in relation with the public private mix at the center of many debates; financing as a key mechanism for the regulation of the whole health care system and not only as a resource mobilization; HIV in bringing up new problems clearly shows how all these matters are related. Health care financing is at the heart of ongoing questions on health care reforms. Although developing countries have low insurance coverage and weak modern medical care, they share the same questions as developed countries: How to promote technical and allocative efficiency? What place for incentives? What role for the public sector? How can market and contracting bring results? What progress through stewardship and better governance?

  15. Development and evolution of convective bursts in WRF simulations of hurricanes Dean (2007) and Bill (2009)

    NASA Astrophysics Data System (ADS)

    Hazelton, Andrew Todd

    Understanding and predicting the inner-core structure and intensity change of tropical cyclones (TCs) remains one of the biggest challenges in tropical meteorology. This study addresses this challenge by investigating the formation, structure, and intensity changes resulting from localized strong updrafts in TCs known as convective bursts (CBs). The evolution of CBs are analyzed in high-resolution simulations of two hurricanes (Dean 2007 and Bill 2009) using the Weather Research and Forecasting (WRF) model. The simulations are able to capture the observed track and peak intensity of the TCs. With Dean, there is a slight lag between the simulated intensification and actual intensification, and the extreme rate of RI is not fully captured. However, the cycle of intensification, weakening, and re-intensification observed in both TCs is captured in the simulations, and appears to be due to a combination of internal dynamics and the surrounding environmental conditions. CBs are identified based on the 99th percentile of eyewall vertical velocity (over the layer from z = 6-12 km) in each simulation (8.4 m s-1 for Dean, 5.4 m s-1 for Bill). The highest density of CBs is found in the downshear-left quadrant, consistent with prior studies. The structure of the CBs is analyzed by comparing r-z composites of azimuths with CBs and azimuths without CBs, using composite figures and statistical comparisons. The CB composites show stronger radial inflow in the lowest 0-2 km, and stronger radial outflow from the eye to the eyewall in the 2-4 km layer. The CB composites also have stronger low-level vorticity than the non-CBs, potentially due to eyewall mesovortices. The analysis of individual CBs also confirms the importance of the eye-eyewall exchange in CB development, potentially by providing buoyancy, as parcel trajectories show that many parcels are flung outward from the eye and rapidly ascend in the CBs, with as much as 500 J/kg of CAPE along the parcel path. In addition, the

  16. Generic oscillation patterns of the developing systems and their role in the origin and evolution of ontogeny.

    PubMed

    Cherdantsev, Vladimir G

    2014-09-01

    The role of generic oscillation patterns in embryonic development on a macroscopic scale is discussed in terms of active shell model. These self-oscillations include periodic changes in both the mean shape of the shell surface and its spatial variance. They lead to origination of a universal oscillatory contour in the form of a non-linear dependence of the average rudiment's curvature upon the curvature variance. The alternation of high and low levels of the variance makes it possible to pursue the developmental dynamics irrespective to the spatiotemporal order of development and characters subject to selection and genetic control. Spatially homogeneous and heterogeneous states can alternate in both time and space being the parametric modifications of the same self-organization dynamics, which is a precondition of transforming of the oscillations into spatial differences between the parts of the embryo and then into successive stages of their formation. This process can be explained as a "retrograde developmental evolution", which means the late evolutionary appearance of the earlier developmental stages. The developing system progressively retreats from the initial self-organization threshold replacing the self-oscillatory dynamics by a linear succession of stages in which the earlier developmental stages appear in the evolution after the later ones. It follows that ontogeny is neither the cause, nor the effect of phylogeny: the phenotype development can be subject to directional change under the constancy of the phenotype itself and, vice versa, the developmental evolution can generate new phenotypes in the absence of the external environmental trends of their evolution. Copyright © 2014. Published by Elsevier Ireland Ltd.

  17. The evolution of the home healthcare industry--developing new levels of business sophistication.

    PubMed

    Louden, T L

    1987-07-01

    Home healthcare is undergoing significant evolution as it matures as an industry segment. As different types of providers are attracted to home care, home care product companies are finding their customer bases dividing in two--traditional referral customers and a new type of customer, those looking for joint ventures and contracts.

  18. Evolution Online: Using a Virtual Learning Environment to Develop Active Learning in Undergraduates

    ERIC Educational Resources Information Center

    Bromham, Lindell; Oprandi, Paolo

    2006-01-01

    We show how an interactive website can help first-year undergraduates acquire independent study skills, and provide a user-friendly way of approaching challenging material in introductory level evolution and ecology. Students embraced the opportunity to undertake self-assessment tasks online, which allowed them to gauge their understanding and…

  19. Developing a Learning Progression for Three-Dimensional Learning of the Patterns of Evolution

    ERIC Educational Resources Information Center

    Wyner, Yael; Doherty, Jennifer H.

    2017-01-01

    This paper examines how students make progress toward three-dimensional (3D) understanding of the patterns of evolution. Specifically, it proposes a learning progression that explains how scientific practices, crosscutting concepts, and disciplinary core ideas come together in naming and grouping, length of change over time, and the role of common…

  20. Human development x: Explanation of macroevolution--top-down evolution materializes consciousness. The origin of metamorphosis.

    PubMed

    Hermansen, Tyge Dahl; Ventegodt, Søren; Merrick, Joav

    2006-12-15

    In this paper, we first give a short discussion of the macroevolution viewing life as information-directed, complex, dynamic systems. On this basis, we give our explanation of the origin of life and discuss the top-down evolution of molecules, proteins, and macroevolution. We discuss these subjects according to our new holistic biological paradigm. In view of this, we discuss the macroevolution of the organism, the species, the biosphere, and human society. After this, we discuss the shift in evolution from natural selection to a new proposed process of nature called the "metamorphous top-down" evolution. We discuss the capability of the evolutionary shift to govern some of the processes that lead to the formation of new species. We discuss the mechanisms we think are behind this proposed shift in evolution and conclude that this event is able to explain the huge biological diversity of nature in combination with evolutionary natural selection. We also discuss this event of nature as an isolated, but integrated, part of the universe. We propose the most important genetic and biochemical process that we think is behind the evolutionary shift as a complicated symbiosis of mechanisms leading to metamorphosis in all biological individuals, from bacteria to humans. The energetic superorbital that manifests the consciousness governs all these processes through quantum chemical activity. This is the key to evolutionary shift through the consciousness, and we propose to call this process "adult human metamorphosis".

  1. La participation des enfants et des adolescents à la boxe

    PubMed Central

    Purcell, Laura K; LeBlanc, Claire MA

    2012-01-01

    RÉSUMÉ Des milliers de garçons et de filles de moins de 19 ans font de la boxe en Amérique du Nord. Même si la boxe comporte des avantages pour ceux qui y participent, y compris l’exercice, l’autodiscipline et la confiance en soi, le sport lui-même favorise et récompense des coups délibérés à la tête et au visage. Les personnes qui font de la boxe risquent de subir des blessures à la tête, au visage et au cou, y compris des traumatismes neurologiques chroniques et même fatals. Les commotions cérébrales sont l’une des principales blessures causées par la boxe. En raison du risque de blessures crâniennes et faciales, la Société canadienne de pédiatrie et l’American Academy of Pediatrics s’opposent vigoureusement à la boxe comme activité sportive pour les enfants et les adolescents. Ces organismes recommandent que les médecins s’élèvent contre la boxe auprès des jeunes et les encouragent à participer à d’autres activités dans lesquelles les coups intentionnels à la tête ne constituent pas un élément essentiel du sport.

  2. Prédiction du comportement à long terme des matériaux polymères

    NASA Astrophysics Data System (ADS)

    Lemaire, J.

    1998-06-01

    Most of the world activity on research, development and control of polymer durability is still based on empirical techniques developed in the early ages of polymer uses. Those techniques should be critically analysed considering the state of the art in the fundamental understanding of these complex phenomena. A more rational approach is described, especially to predict the lifetime of polymeric materials in environmental conditions. That approach is based on the recognition of the chemical evolution mechanisms. Les activités de recherche, développement et contrôle de durabilité des matériaux polymères sont encore, pour une part très importante, basées sur l'emploi de techniques empiriques dont les principes ont été énoncés dès le début de l'exploitation de ces matériaux. Une analyse critique de ces méthodes s'impose aujourd'hui en tenant compte de l'avancement des connaissances. Une approche plus rationnelle est décrite, approche basée sur la reconnaissance des mécanismes d'évolution chimique. A titre d'exemple, le mécanisme d'évolution du PVC sous contraintes conjuguées de l'UV, de la chaleur et de l'oxygène, est décrit. Des études récentes de photooxydation de polymères conducteurs au sein de polyéthylène sont également succinctement rapportées.

  3. Evolutionary developmental pathology and anthropology: A new field linking development, comparative anatomy, human evolution, morphological variations and defects, and medicine.

    PubMed

    Diogo, Rui; Smith, Christopher M; Ziermann, Janine M

    2015-11-01

    We introduce a new subfield of the recently created field of Evolutionary-Developmental-Anthropology (Evo-Devo-Anth): Evolutionary-Developmental-Pathology-and-Anthropology (Evo-Devo-P'Anth). This subfield combines experimental and developmental studies of nonhuman model organisms, biological anthropology, chordate comparative anatomy and evolution, and the study of normal and pathological human development. Instead of focusing on other organisms to try to better understand human development, evolution, anatomy, and pathology, it places humans as the central case study, i.e., as truly model organism themselves. We summarize the results of our recent Evo-Devo-P'Anth studies and discuss long-standing questions in each of the broader biological fields combined in this subfield, paying special attention to the links between: (1) Human anomalies and variations, nonpentadactyly, homeotic transformations, and "nearest neighbor" vs. "find and seek" muscle-skeleton associations in limb+facial muscles vs. other head muscles; (2) Developmental constraints, the notion of "phylotypic stage," internalism vs. externalism, and the "logic of monsters" vs. "lack of homeostasis" views about human birth defects; (3) Human evolution, reversions, atavisms, paedomorphosis, and peromorphosis; (4) Scala naturae, Haeckelian recapitulation, von Baer's laws, and parallelism between phylogeny and development, here formally defined as "Phylo-Devo parallelism"; and (5) Patau, Edwards, and Down syndrome (trisomies 13, 18, 21), atavisms, apoptosis, heart malformations, and medical implications.

  4. Turning Points: Canadians from Coast to Coast Set a New Course for Healthy Child and Youth Development. The National Goals for Healthy Child and Youth Development = Points Tournants: Les Canadiens et les Canadiennes d'un ocean a l'autre tracent une nouvelle voie pour le developpement sain des enfants et des adolescents. Les objectifs nationaux pour le developpement sain des enfants et des adolescents.

    ERIC Educational Resources Information Center

    Ministry of Health, Ottawa (Ontario).

    This document details Canada's mission to safeguard and improve the health and well-being of all Canadian children and youth and presents eight national goals through which Canada plans to fulfill that mission. The document is presented in three parts. Part 1 describes the development of national goals, including their origin in the underlying…

  5. Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development

    PubMed Central

    2011-01-01

    Background We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. Results The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements. Conclusions Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution. PMID:21854559

  6. Early 20th-century research at the interfaces of genetics, development, and evolution: reflections on progress and dead ends.

    PubMed

    Deichmann, Ute

    2011-09-01

    Three early 20th-century attempts at unifying separate areas of biology, in particular development, genetics, physiology, and evolution, are compared in regard to their success and fruitfulness for further research: Jacques Loeb's reductionist project of unifying approaches by physico-chemical explanations; Richard Goldschmidt's anti-reductionist attempts to unify by integration; and Sewall Wright's combination of reductionist research and vision of hierarchical genetic systems. Loeb's program, demanding that all aspects of biology, including evolution, be studied by the methods of the experimental sciences, proved highly successful and indispensible for higher level investigations, even though evolutionary change and properties of biological systems up to now cannot be fully explained on the molecular level alone. Goldschmidt has been appraised as pioneer of physiological and developmental genetics and of a new evolutionary synthesis which transcended neo-Darwinism. However, this study concludes that his anti-reductionist attempts to integrate genetics, development and evolution have to be regarded as failures or dead ends. His grand speculations were based on the one hand on concepts and experimental systems that were too vague in order to stimulate further research, and on the other on experiments which in their core parts turned out not to be reproducible. In contrast, Sewall Wright, apart from being one of the architects of the neo-Darwinian synthesis of the 1930s, opened up new paths of testable quantitative developmental genetic investigations. He placed his research within a framework of logical reasoning, which resulted in the farsighted speculation that examinations of biological systems should be related to the regulation of hierarchical genetic subsystems, possibly providing a mechanism for development and evolution. I argue that his suggestion of basing the study of systems on clearly defined properties of the components has proved superior to

  7. Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development.

    PubMed

    Renfree, Marilyn B; Papenfuss, Anthony T; Deakin, Janine E; Lindsay, James; Heider, Thomas; Belov, Katherine; Rens, Willem; Waters, Paul D; Pharo, Elizabeth A; Shaw, Geoff; Wong, Emily S W; Lefèvre, Christophe M; Nicholas, Kevin R; Kuroki, Yoko; Wakefield, Matthew J; Zenger, Kyall R; Wang, Chenwei; Ferguson-Smith, Malcolm; Nicholas, Frank W; Hickford, Danielle; Yu, Hongshi; Short, Kirsty R; Siddle, Hannah V; Frankenberg, Stephen R; Chew, Keng Yih; Menzies, Brandon R; Stringer, Jessica M; Suzuki, Shunsuke; Hore, Timothy A; Delbridge, Margaret L; Patel, Hardip R; Mohammadi, Amir; Schneider, Nanette Y; Hu, Yanqiu; O'Hara, William; Al Nadaf, Shafagh; Wu, Chen; Feng, Zhi-Ping; Cocks, Benjamin G; Wang, Jianghui; Flicek, Paul; Searle, Stephen M J; Fairley, Susan; Beal, Kathryn; Herrero, Javier; Carone, Dawn M; Suzuki, Yutaka; Sugano, Sumio; Toyoda, Atsushi; Sakaki, Yoshiyuki; Kondo, Shinji; Nishida, Yuichiro; Tatsumoto, Shoji; Mandiou, Ion; Hsu, Arthur; McColl, Kaighin A; Lansdell, Benjamin; Weinstock, George; Kuczek, Elizabeth; McGrath, Annette; Wilson, Peter; Men, Artem; Hazar-Rethinam, Mehlika; Hall, Allison; Davis, John; Wood, David; Williams, Sarah; Sundaravadanam, Yogi; Muzny, Donna M; Jhangiani, Shalini N; Lewis, Lora R; Morgan, Margaret B; Okwuonu, Geoffrey O; Ruiz, San Juana; Santibanez, Jireh; Nazareth, Lynne; Cree, Andrew; Fowler, Gerald; Kovar, Christie L; Dinh, Huyen H; Joshi, Vandita; Jing, Chyn; Lara, Fremiet; Thornton, Rebecca; Chen, Lei; Deng, Jixin; Liu, Yue; Shen, Joshua Y; Song, Xing-Zhi; Edson, Janette; Troon, Carmen; Thomas, Daniel; Stephens, Amber; Yapa, Lankesha; Levchenko, Tanya; Gibbs, Richard A; Cooper, Desmond W; Speed, Terence P; Fujiyama, Asao; Graves, Jennifer A M; O'Neill, Rachel J; Pask, Andrew J; Forrest, Susan M; Worley, Kim C

    2011-08-29

    We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements. Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution.

  8. The development and application of landscape evolution models to coupled coast-estuarine environments

    NASA Astrophysics Data System (ADS)

    Morris, Chloe; Coulthard, Tom; Parsons, Daniel R.; Manson, Susan; Barkwith, Andrew

    2017-04-01

    Landscape Evolution Models (LEMs) are proven to be useful tools in understanding the morphodynamics of coast and estuarine systems. However, perhaps owing to the lack of research in this area, current models are not capable of simulating the dynamic interactions between these systems and their co-evolution at the meso-scale. Through a novel coupling of numerical models, this research is designed to explore coupled coastal-estuarine interactions, controls on system behaviour and the influence that environmental change could have. This will contribute to the understanding of the morphodynamics of these systems and how they may behave and evolve over the next century in response to climate changes, with the aim of informing management practices. This goal is being achieved through the modification and coupling of the one-line Coastline Evolution Model (CEM) with the hydrodynamic LEM CAESAR-Lisflood (C-L). The major issues faced with coupling these programs are their differing complexities and the limited graphical visualisations produced by the CEM that hinder the dissemination of results. The work towards overcoming these issues and reported here, include a new version of the CEM that incorporates a range of more complex geomorphological processes and boasts a graphical user interface that guides users through model set-up and projects a live output during model runs. The improved version is a stand-alone tool that can be used for further research projects and for teaching purposes. A sensitivity analysis using the Morris method has been completed to identify which key variables, including wave climate, erosion and weathering values, dominate the control of model behaviour. The model is being applied and tested using the evolution of the Holderness Coast, Humber Estuary and Spurn Point on the east coast of England (UK), which possess diverse geomorphologies and complex, co-evolving sediment pathways. Simulations using the modified CEM are currently being completed to

  9. Les Applications Therapeutiques Des Lasers

    NASA Astrophysics Data System (ADS)

    Brunetaud, J. M.; Mordon, S.; Bourez, J.; Mosquet, L.; Moschetto, Y.

    1984-03-01

    C'est de tres loin le mecanisme predominant dans les applications therapeutiques du laser. En concentrant le flux lumineux sur une surface redui-te, le laser chauffe localement les tissus qui se retractent (coagulation) pour etre elimines ensuite (detersion) ; si on chauffe plus intensement, les tissus peuvent etre volatilises. La coagulation est utilisee soit pour detruire de petits phenomenes tumoraux qui seront elimines lors du processus de detersion, soit pour arreter une hemorragie (hemo-stase) ; dans ce cas la retraction thermique des tissus va provoquer la fermeture de la lumiere des vaisseaux qui seront secondairement obliteres par des caillots formes sur place (thrombose). Par volatilisation it est possible de detruire des phenomenes tumoraux plus importants que ceux at-teints lors d'une simple coagulation. Si la zone volatilisee est tres etroite (de 0,1 a 1 mm) on obtient un effet de coupe avec une excellente hemostase au niveau des berges. Certes ces deux processus - coagulation et volatilisation - peuvent etre obtenus par d'autres procedes : echauffement par contact (sonde thermique) ou effet Joule (courant electrique haute frequence). Le laser a l'avantage de ne necessiter aucun contact mecanique entre le vecteur d'energie et les tissus ; on peut alors predire correctement la repartition d'energie au niveau des tissus et les effets sont tres repro-ductibles. Par ailleurs, l'absorption tissulaire variant considerablement avec la longueur d'onde on peut choisir la source laser en fonction des effets desires.

  10. Microstructural Evolution and Mechanical Property Development of Selective Laser Melted Copper Alloys

    NASA Astrophysics Data System (ADS)

    Ventura, Anthony Patrick

    Selective Laser Melting (SLM) is an additive manufacturing technology that utilizes a high-power laser to melt metal powder and form a part layer-by-layer. Over the last 25 years, the technology has progressed from prototyping polymer parts to full scale production of metal component. SLM offers several advantages over traditional manufacturing techniques; however, the current alloy systems that are researched and utilized for SLM do not address applications requiring high electrical and thermal conductivity. This work presents a characterization of the microstructural evolution and mechanical property development of two copper alloys fabricated via SLM and post-process heat treated to address this gap in knowledge. Tensile testing, conductivity measurement, and detailed microstructural characterization was carried out on samples in the as-printed and heat treated conditions. A single phase solid solution strengthened binary alloy, Cu-4.3Sn, was the first alloy studied. Components were selectively laser melted from pre-alloyed Cu-4.3Sn powder and heat treated at 873 K (600 °C) and 1173 K (900 °C) for 1 hour. As-printed samples were around 97 percent dense with a yield strength of 274 MPa, an electrical conductivity of 24.1 %IACS, and an elongation of 5.6%. Heat treatment resulted in lower yield strength with significant increases in ductility due to recrystallization and a decrease in dislocation density. Tensile sample geometry and surface finish also showed a significant effect on measured yield strength but a negligible change in measured ductility. Microstructural characterization indicated that grains primarily grow epitaxially with a sub-micron cellular solidification sub-structure. Nanometer scale tin dioxide particles identified via XRD were found throughout the structure in the tin-rich intercellular regions. The second alloy studied was a high-performance precipitation hardening Cu-Ni-Si alloy, C70250. Pre-alloyed powder was selectively laser melted to

  11. Genetics of flower development in Ranunculales - a new, basal eudicot model order for studying flower evolution.

    PubMed

    Damerval, Catherine; Becker, Annette

    2017-10-01

    Contents 361 I. 361 II. 362 III. 363 IV. 364 V. 364 Acknowledgements 365 References 365 SUMMARY: Ranunculales, the sister group to all other eudicots, encompasses species with a remarkable floral diversity, which are currently emerging as new model organisms to address questions relating to the genetic architecture of flower morphology and its evolution. These questions concern either traits only found in members of the Ranunculales or traits that have convergently evolved in other large clades of flowering plants. We present recent results obtained on floral organ identity and number, symmetry evolution and spur formation in Ranunculales species. We discuss benefits and future prospects of evo-devo studies in Ranunculales, which can provide the opportunity to decipher the genetic architecture of novel floral traits and also to appraise the degree of conservation of genetic mechanisms involved in homoplasious traits. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  12. Cultural evolution: interpersonal influence, issue importance, and the development of shared attitudes in college residence halls.

    PubMed

    Cullum, Jerry; Harton, Helen C

    2007-10-01

    This article investigates cultural evolution in four college residence halls. Up to four attitude surveys were completed by 1,252 participants in a semester. Participants' attitudes became more similar to those living closest to them over time as a result of localized interpersonal influence processes. Correlations between attitudes also increased with time as these cultural attributes grew increasingly interdependent. These basic findings support the predictions of dynamic social impact theory. However, these effects were stronger for more important issues even when controlling for discussion. These findings are likely the result of (a) individual-level selective attention to personally important information, (b) greater attitude-behavior consistency for important issues, and/or (c) nonlinear attitude change processes for important issues as suggested by the catastrophe theory of attitudes. These results suggest that intrapsychic processes as well as interpersonal processes contribute to cultural evolution.