Malkostrake Krebse zeigen im postnauplialen Keimstreif ein invariantes Zellteilungsmuster und eine Zelllinie. Embryonen eines Isopoden (Porcellio scaber) und eines Amphipoden (Orchestia cavimana) wurden bezüglich ihrer Zelllinie vergleichend Untersucht. Mittels immunhistochemischer Färbungen wurde das Expressionsmuster der Gene engrailed und Distal-less in Hinblick auf die Zelllinie und die Morphogenese der Segmente und der Beinentwicklung analysiert. Die Zelllinie wurde bei Porcellio scaber mit der Methode der 4D-Mikroskopie untersucht. Mit Zellablationsexperimenten wurden Abhängigkeiten der Zellen untereinander aufgezeigt. Die Ergebnisse dieser Untersuchungen zeigen: I. Die Genexpression von Distal-less und engrailed wird unabhängig von der Zelllinie reguliert. II. Die Bildung der konvergenten einästigen Beine im Thoraxbereich beider Krebse erfolgt durch unterschiedliche Regulation des Gens Distal-less - bei Orchestia cavimana wird die Expression des Gens in den lateralen Zellen abgeschaltet, während diese Zellen bei Porcellio scaber erst gar nicht Distal-less exprimieren. III. Die Anwendung des Systems der 4D-Mikroskopie zeigte unter anderem, dass in den vorderen Reihen nichtektoteloblastischen Ursprungs bei Porcellio scaber die Zelllinie variabel ist und eine Zellsortierung und Zellimmigration stattfindet. IV. Die Ähnlichkeit der Bildung dieser Reihen bei Porcellio scaber mit der der Tanaidaceen lässt auf ein Schwestergruppenverhältnis der Taxa Isopoda und Tanaidacea schliessen. Die Dissertation enthält fünf Videoaufnahmen als separate AVI-Dateien. / Malacostracan crustaceans show in their postnaupliar germ-band an invariant cleavage pattern and a cell-lineage. A comparative analysis of this cell-lineage in an Isopod (Porcellio scaber) and an amphipod (Orchestia cavimana) was done in this thesis. Immunohistochemical stainings of the gene products Distal-less and Engrailed were used, to show the relation of these genes to the morphogenesis of segments and legs. Further, the cell-lineage of Porcellio scaber was analyzed with a 4D-microscope system. Cell-ablation experiments were used to show regulational networks in the development of the germ-band. The results of this work show: I. The regulation of the genes Distal-less and engrailed is independent of the cell-lineage. II. The morphogenesis of the convergent monoramous limbs in the thorax is reflected by different expression patterns of the gene Distal-less - in Orchestia cavimana the expression of Distal-less is switched off in the lateral cells, in Porcellio scaber these cells do not start the Distal-less expression. III. The 4D-microscopy analysis show, that the cell-lineage in the cellrows wich have a non-ectoteloblastic origin is not invariant. In these rows of cells show cell sorting. IV. The formation of these rows in the isopod Porcellio scaber shows similarity to the formation in tanaidaceans. A sister group relationship of Tanaidacea and Isopoda is strongly supported. This dissertation contains five video recordings as separate AVI files.

Die vorliegende Arbeit behandelt die Embryonalentwicklung des Rankenfußkrebses Elminius modestus (Thecostraca: Cirripedia). Der Entwicklungsprozess wurde mithilfe unterschiedlicher Methoden wie 4D Mikroskopie, in vivo Einzelzellmarkierungen, Fluoreszenzhistochemie und konfokaler Laserscanningmikroskopie in Verbindung mit 3D Rekonstruktionen untersucht. Die Furchung von E. modestus ist total, inequal in Bezug auf die Dotterzelle und asynchron mit einem anterior-posterioren Gradienten. Der gesamte Prozess folgt einem strengen Teilungsmuster mit nur sehr geringer Variabilität. Eine davon stellt das Auftreten spiegelbildlicher Embryonen ab dem 4-Zell. Die Keimblattdifferenzierung wurde vor allem mittels in vivo Zellmarkierungen untersucht. Die Trennung der endodermalen und endomesodemalen Keimblätter erfolgt nach der vierten Furchungsteilung, die Trennung des Ectomesoderm nach der sechsten Teilung. Die Urkeimzellen sind aller Wahrscheinlichkeit nach ein Produkt der siebten Furchungsteilung der Dotterzellen (3Da und 3Dp). Im Zuge der Untersuchung konnte die Zelllinie jedes Keimblattes rekonstruiert werden, die Zellschicksale der Abkömmlinge der Quadranten wurde bis zum 16-Zell Stadium beschrieben. Das Ectoderm entspringt allen vier Quadranten, ebenso das Ectomesoderm (die letzten identifizierten Mesectoblasten sind 3A, 3B, 3C, 1drp und 1dlp). Endoderm und Endomesoderm entwickeln sich aus einzelnen Vorläuferzellen im 16-Zell Stadium (2D bzw. 2d). Das Auftreten nur eines einzelnen Endoblasten stellt eine mögliche Apomorphie aller Ecdysozoa dar. Das Vorhandensein eines einzelnen Mesendoblasten wird als mögliches Merkmal des Grundmusters aller Protostomia in Betracht gezogen. / The present work is devoted to the embryonic development of the thoracican barnacle Elminius modestus (Thecostraca: Cirripedia). The developmental process was investigated by means of different techniques like 4D microscopy, in vivo labelling, fluorescent histochemistry, and confocal laser scanning microscopy combined with 3D reconstructions. The cleavage of E. modestus is total, unequal with regards to the yolky cell, and asynchronous with an anterior-posterior gradient. The entire process appears to follow a strict pattern of divisions with very little variability, one of which includes the occurrence of mirror image embryos from the 4-cell stage on. The germ layer differentiation was mainly studied by means of in vivo labelling. The segregation of the endodermal and the endomesodemal germ layers are shown to happen after the fourth division, whereas the ectomesoderm segregates after the sixth division. The primordial germ cells are suggested to be a product of the seventh cleavage division of the yolky cells (3Da and 3Dp). During the research the cell lineage of each germ layer was established, the fates of the quadrant descendants are described up to the 16-cell stage. The ectoderm originates from four quadrants, as does the ectomesoderm (the last identified mesectoblasts are 3A, 3B, 3C, 1drp, and 1dlp). The endoderm and the endomesoderm develop from single precursors at the 16-cell stage (2D and 2d, respectively). The presence of only a single endoblastic cell, might represent an apomorphy for the entire group of Ecdysozoa. A singular mesendoblast is suggested to be a possible feature in the developmental ground pattern of all Protostomia.

Nous nous intéressons à des modèles statistiques pour les données indexées par des arborescences. Dans le contexte de l'équipe Virtual Plants, équipe hôte de cette thèse, les applications d'intérêt portent sur le développement de la plante et sa modulation par des facteurs environnementaux et génétiques. Nous nous restreignons donc à des applications issues du développement de la plante, à la fois au niveau microscopique avec l'étude de la lignée cellulaire du tissu biologique servant à la croissance des plantes, et au niveau macroscopique avec le mécanisme de production de branches. Le catalogue de modèles disponibles pour les données indexées par des arborescences est beaucoup moins important que celui disponible pour les données indexées par des chemins. Cette thèse vise donc à proposer un cadre de modélisation statistique pour l'étude de patterns pour données indexées par des arborescences. À cette fin, deux classes différentes de modèles statistiques, les modèles de Markov et de détection de ruptures, sont étudiées. / We address statistical models for tree-indexed data.Tree-indexed data can be seen as a generalization of path-indexed data since directed path graphs are directed tree graphs where there is at most one child per vertex.In the context of the Virtual Plants team, host team of this thesis, applications of interest focus on plant development and its modulation by environmental and genetic factors.We thus focus on plant developmental applications, both at the microscopic level with the study of the cell lineage in the biological tissue responsible for the plant growth, and at the macroscopic level with the mechanism of production of branches. The catalog of models available for tree-indexed data is far less important than the one available for path-indexed data.This thesis therefore aims at proposing a statistical modeling framework for studying patterns in tree-indexed data.To this end, two different classes of statistical models, Markov and change-point models, are investigated.

No / Androgens stimulate many hair follicles to alter hair colour and size via the hair growth cycle; in androgenetic alopecia tiny, pale hairs gradually replace large, pigmented ones. Since stem cell factor (SCF) is important in embryonic melanocyte migration and maintaining adult rodent pigmentation, we investigated SCF/c-Kit signalling in human hair follicles to determine whether this was altered in androgenetic alopecia. Quantitative immunohistochemistry detected three melanocyte-lineage markers and c-Kit in four focus areas: the epidermis, infundibulum, hair bulb (where pigment is formed) and mid-follicle outer root sheath (ORS). Colocalisation confirmed melanocyte c-Kit expression; cultured follicular melanocytes also exhibited c-Kit. Few ORS cells expressed differentiated melanocyte markers or c-Kit, but NKI/beteb antibody, which also recognises early melanocyte-lineage antigens, identified fourfold more cells, confirmed by colocalisation. Occasional similar bulbar cells were seen. Melanocyte distribution, concentration and c-Kit expression were unaltered in balding follicles. Androgenetic alopecia cultured dermal papilla cells secreted less SCF, measured by ELISA, than normal cells. This identifies three types of melanocyte-lineage cells in human follicles. The c-Kit expression by dendritic, pigmenting, bulbar melanocytes and rounded, differentiated, non-pigmenting ORS melanocytes implicate SCF in maintaining pigmentation and migration into regenerating hair bulbs. Less differentiated, c-Kit-independent cells in the mid-follicle ORS stem cell niche and occasionally in the bulb, presumably a local reserve for long scalp hair growth, implicate other factors in activating stem cells. Androgens appear to reduce alopecia hair colour by inhibiting dermal papilla SCF production, impeding bulbar melanocyte pigmentation. These results may facilitate new treatments for hair colour changes in hirsutism, alopecia or greying.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 182-199.

Stem cells differentiate through an organized hierarchy of intermediate cell types to terminally differentiated cell types. This process is largely guided by master transcriptional regulators, but it also depends on the expression of many other types of genes. The discrete cell types in the differentiation hierarchy are often identified based on the expression or non-expression of certain marker genes. Historically, these have often been various cell-surface proteins, which are fairly easy to assay biochemically but are not necessarily causative of the cell type, in the sense of being master transcriptional regulators. This raises important questions about how gene expression across the whole genome controls or reflects cell state, and in particular, differentiation hierarchies. Traditional approaches to understanding gene expression patterns across multiple conditions, such as principal components analysis or K-means clustering, can group cell types based on gene expression, but they do so without knowledge of the differentiation hierarchy. Hierarchical clustering and maximization of parsimony can organize the cell types into a tree, but in general this tree is different from the differentiation hierarchy. Using hematopoietic differentiation as an example, we demonstrate how many genes other than marker genes are able to discriminate between different branches of the differentiation tree by proposing two models for detecting genes that are up-regulated or down-regulated in distinct lineages. We then propose a novel approach to solving the following problem: Given the differentiation hierarchy and gene expression data at each node, construct a weighted Euclidean distance metric such that the minimum spanning tree with respect to that metric is precisely the given differentiation hierarchy. We provide a set of linear constraints that are provably sufficient for the desired construction and a linear programming framework to identify sparse sets of weights, effectively identifying genes that are most relevant for discriminating different parts of the tree. We apply our method to microarray gene expression data describing 38 cell types in the hematopoiesis hierarchy, constructing a sparse weighted Euclidean metric that uses just 175 genes. These 175 genes are different than the marker genes that were used to identify the 38 cell types, hence offering a novel alternative way of discriminating different branches of the tree. A DAVID functional annotation analysis shows that the 175 genes reflect major processes and pathways active in different parts of the tree. However, we find that there are many alternative sets of weights that satisfy the linear constraints. Thus, in the style of random-forest training, we also construct metrics based on random subsets of the genes and compare them to the metric of 175 genes. Our results show that the 175 genes frequently appear in the random metrics, implicating their significance from an empirical point of view as well. Finally, we show how our linear programming method is able to identify columns that were selected to build minimum spanning trees on the nodes of random variable-size matrices.