bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of retinoic acid in mouse neural crest cell development in vitro
Authors: Ito Kazuo , Morita Toshiteru 
Published: February 2005

AbstractThis study examines the role of retinoic acid (RA) in mouse neural crest cell development in culture. We have compared the effects of RA on the developmental behavior of mouse neural crest cells from different axial leveles, that is the mesencephalic (cranial) and sympathoadrenal (trunk) levels by colony assay using antibodies against cell‐type‐specific markers. In control cultures in the absence of RA, the efficiency of colony formation by cranial neural crest cells was considerably lower than in colony cultures of trunk neural crest cells. Pulse‐labelling experiments using 5‐bromo‐2′‐deoxyuridine (BrdU) showed that the proportion of neural crest cells that incorporated BrdU was significantly smaller in day 5 cultures of cranial neural crest cells in the absence of RA compared to cultures from the trunk level. However, BrdU‐incorporation matched the labelling observed in trunk crest cell cultures when RA was added to the culture medium. The efficiency of colony formation and the proportion of BrdU‐incorporated cells in trunk crest cell cultures was similar in the presence and absence of RA. The results suggest that in the early stages of in vitro development, RA has a larger impact on proliferation and/or survival of cranial neural crest cells than of trunk neural crest cells. Moreover, the data indicate that RA significantly affects melanogenesis and the differentiation of serotonergic neurons in mouse neural crest cell cultures from both axial levels. Whereas melanogenesis was suppressed by RA treatment, serotonergic neurogenesis was promoted. Doublelabelling experiments with antibodies against BrdU and serotonin (5‐HT) indicated that RA selectively promoted proliferation of these neurons at a later stage of in vitro development. Furthermore, RA acted upon both committed cells and multipotent cells. Based on the results, we conclude that RA plays multiple critical roles in mouse neural crest cell development. © 1995 wiley‐Liss, Inc.
Expression of Cdx‐2 in the mouse embryo and placenta: Possible role in patterning of the extra‐embryonic membranes
Authors: Beck F. , Erler T. , Russell A. , James R. 
Published: February 2005

AbstractThree mouse homologues of the Drosophila homeotic gene Caudal (Cad) have been described. They are currently designated Cdx‐1, Cdx‐2, and Cdx‐4. Cdx‐1 and 2 are both strongly expressed in the adult mid‐ and hindgut, while Cdx‐1 and 4 have been shown to be activated in the embryonic primitive streak. Using a polyclonal antibody against a fusion protein containing the amino terminal 109 amino acids of murine Cdx‐2, we here describe the topographical location of the gene product from early cleavage to 12.5 days of embryonic development. Cdx‐2 expression begins at 3.5 days and is confined to the trophectoderm, being absent from the inner cell mass. Subsequently, staining is located in the extra‐embryonic ectoderm adjacent to the epiblast, but sparing the more superficially placed polar, as well as the mural trophoblastic cells. Continuing expression in the fetal membranes involves the chorion, the allantoic bud, and, at even later stages, the spongiotrophoblast. From 8.5 days, Cdx‐2 begins to be expressed in embryonic tissues, principally (unlike Cdx‐1) in the posterior part of the gut from its earliest formation, as well as in the tail bud and in the caudal part of the neural tube. Cdx‐2 is, therefore, transcribed well before any other membrane of the Cad homologue group and of the related Hox‐C group; its expression in the extra‐embryonic membranes and in the hindgut reflects the phylogenetic relationship between the cloaca and the chorio‐allantois and suggests the possibility that homeobox genes may be involved in placental development and/or patterning. © 1995 wiley‐Liss, Inc.
Expression patterns of laminin receptor splice variants α6Aβ1 and α6Bβ1 suggest different roles in mouse development
Authors: Thorsteinsdóttir Sólveig , Roelen Bernard A. J. , Freund Eric , Gaspar Ana C. , Sonnenberg Arnoud , Mummery Christine L. 
Published: February 2005

AbstractThe α6β1 integrin is a receptor for laminins and is present from early stages of mouse embryogenesis. In the present study determined the temporal and spatial expression of the two cytoplasmic splice variants of the α6 integrin subunit, α6A and α6B, in the early‐ and midgestation mouse postimplantation embryo using RT‐PCR, in situ hybridization, and immunofluorescence. Our results show that α6B is present in the embryo at all stages studied and is expressed before α6A. α6A expression begins in 8.5 day p.c. embryos and is initially exclusively localized to the developing heart. In 8.5 (and 9.5) day p.c. embryos α6A mRNA and protein are present in a gradient in the myocardium of the heart tube from strongest expression in the sinus venosus and in the common atrial chamber to a weakening expression along the ventricle and bulbus cordis. In 10.5 day p.c. embryos this gradient is less evident and in 12.5 day p.c. embryos α6A mRNA and protein are present in comparable amounts between atria and ventricles. Neither α6A nor α6B is present in endocardial cushion tissue. By day 12.5 p.c. α6A expression is also present in the developing epidermis, dental primordia, lens, gonads, and in a few epithelia such as those of the digestive tract. α6B expression is always much more widespread than α6A expression. For example, only α6B is present in the myotome of the somites of 9.5 day p.c. embryos, in the developing central and peripheral nervous systems, and in the nephrogenic system at all stages studied, except after the differentiation of the gonads when α6A is also present. Furthermore, α6B is the only splice variant present on endothelial cells. We also examined the distribution of the β4 integrin subunit to determine whether the α6β4 integrin was present during these stages of development. β4 protein was absent in early postimplantation stages but was present in the epidermis and digestive tract of 12.5 day p.c. embryos. These results show a differential distribution of α6A and α6B during mouse development and thus strongly suggest a different function of these splice variants during embryogenesis. Our results point to a possible role for the α6Aβ1 integrin in the development of the myocardium of the developing heart, but not in the migration of endocardial cushion cells, while α6Bβ1 could be important in the developing nephrogenic and nervous systems. © 1995 wiley‐Liss, Inc.
Relationship between fibronectin expression during gastrulation and heart formation in the rat embryo
Authors: Suzuki Hiroaki R. , Solursh Michael , Baldwin H. Scott 
Published: February 2005

AbstractBy utilizing myosin immunostaining, we were able to identify early rat myocardium as a thin epithelial sheet and realized that its cohesive movement toward the midline leads to the straight heart tube formation. Localization study of fibronectin mRNA and protein was, therefore, carried out to investigate its tissue origin and possible roles in facilitating mesoderm migration and heart formation. Fibronectin mRNAs were first detected throughout the mesoderm during the early primitive streak stage, suggesting that the mesoderm is the source of fibronectin. By pre‐head fold (pre‐somite) and head fold (early somite) stages, the mesoderm became largely down‐regulated for fibronectin mRNAs, while it was also at these stages when myosin‐positive myocardium formed itself into the epithelium and was subsequently folding toward the midline. Thus, there appears to be little fibronectin synthesis during and directly relevant to early heart tube formation. Later, during the early straight heart tube stage (5 somite and older), endocardium became highly positive for fibronectin mRNAs, suggesting that the endocardium is the major source of fibronectin for the cardiac jelly. Based on the results, we present a map for the early mammalian heart in which the heart is a single crescentic band lying in front of the prechordal plate. We also suggest a process for heart tube formation based on the cohesive movement of the myocardial epithelium. During heart tube formation, fibronectin protein had been deposited previously by the mesoderm and was found uniformly in the ECM and not newly produced by any adjacent tissue. The data contradict the endodermal guidance of heart migration by fibronectin gradient and suggest, instead, a permissive role for the fibronectin substrate. © 1995 wiley‐Liss, Inc.
Molecular analysis of smooth muscle development in the mouse
Authors: McHugh Kirk M. 
Published: February 2005

AbstractLittle is currently known regarding the ontogeny of smooth muscle tissues during normal mammalian development. The α‐smooth muscle and γ‐smooth muscle isoactins have been shown to be excellent molecular markers of smooth muscle cell phenotype. This study characterizes both the temporal and spatial patterns of α‐smooth muscle and γ‐smooth muscle isoactin expression in the developing mouse. In situ analysis was performed on serial sections of whole mouse embryos on embryonic day 9, 11, 13, 15, and 17 using α‐smooth muscle and γ‐smooth muscle isoactin‐specific riboprobes. Distinct temporal and spatial patterns of α‐smooth muscle and γ‐smooth muscle isoactin gene expression were observed in the developing gastrointestinal tract, urogenital tract, respiratory tract, and vascular system. Independent expression of the α‐smooth muscle isoactin was observed during the early stages of skeletal, cardiac, and smooth muscle myogenesis as well as in a novel subset of distinct organs including the postanal component of the hindgut, allantois, and primitive placenta. The results of this study indicate that distinct cellular phenotypes are involved in smooth muscle myogenesis and suggest that organ‐specific mechanisms might exist for the initiation of smooth muscle development in vivo. In addition, the pattern of independent α‐smooth muscle isoactin expression observed in this study provides novel information regarding the early stages of hindgut and placental development, and suggests that a common functional phenotype may be associated with the early stages of skeletal, cardiac, and smooth muscle myogenesis. © 1995 wiley‐Liss, Inc.
Cell and matrix specialisations of rhombomere boundaries
Authors: Heyman Isobel , Faissner Andreas , Lumsden Andrew 
Published: February 2005

AbstractHindbrain segments, rhom‐bomeres, define distinct cellular and molecular domains which furnish the ground plan for important aspects of neural and cranial development. In this study, further evidence is presented that the interfaces between rhombomeres, rhombomere boundaries, contain both cells and extracellular matrix with specialised characteristics. Cells at rhombomere boundaries show temporally and spatially distinct expression patterns of developmentally important genes. Towards the end of the developmental period when rhombomeres are present, a fan‐shaped array of cells at rhom‐bomere boundaries, that constitute the ventricular ridge, shows decreased expression of two genes (Hoxb‐1 and Krox‐20), which earlier in development were expressed in all cells of specific rhombomeres. In contrast, these boundary cells show increased expression of another gene, Pax‐6, which earlier in development has a rhombomere‐specific expression pattern. A specialised identity for boundary cells is further suggested by increased labelling with an anti‐vimentin antibody at rhombomere boundaries, indicating that at least some boundary cells are radial glia or glial precursors. In addition to distinct cellular properties, the extracellular domain at rhombomere boundaries is also specialised. Chondroitin sulphate proteoglycan (CSPG) immunoreactivity is increased and, as revealed by immuno‐electron microscopy, localised to extracellular spaces. CSPG is also enriched in boundaries regenerated after ablation, or boundaries generated ectopically by rhombomere transplantation. We propose that rhombomere boundaries form their characteristic morphology at the interface between groups of cells with differing molecular characteristics, representing different cell states. A specialised band of cells then develops at the interface. Both the boundary cells and extracellular matrix have characteristics which could be important in later events of neural development such as axon guidance and cell migration. © 1995 wiley‐Liss, Inc.
Cooperative model of epithelial shaping and bending during avian neurulation: Autonomous movements of the neural plate, autonomous movements of the epidermis, and interactions in the neural plate/epidermis transition zone
Authors: Moury J. David , Schoenwolf Gary C. 
Published: February 2005

AbstractMorphogenetic movements during neurulation cause a tissue to change shape within the plane of the epithelium (e.g., conversion of the oval neural plate into the narrow spinal plate and the wide brain plate), cause bending out of the plane of the epithelium (e.g., raise the neural folds and curl the neural plate into a tube), or contribute to both phenomena. In this study, pieces that contain neural plate alone, epidermis alone, or both tissues (with or without underlying tissues) are cut from chick embryos and allowed to develop for up to 24 hr. Examination of histological sections through such isolates allows analysis of the formation of neural folds. When the neural plate/epidermis transition zone is disrupted, neural folds do not form. Conversely, when the transition zone remains intact, neural folds form. Neural folds form even when most of the medial neural plate and lateral epidermis has been removed, leaving only the isolated transition zone. These data indicate that the transition zone is both necessary and sufficient for the formation of neural folds. The transition zone may play a number of roles in epithelial bending including organizing, focussing, and redirecting movements that are autonomous to the neural plate or epidermis. Time‐lapse video recording, and sequential photographs allowed the documentation of such movements. Neural plate isolates exhibit autonomous rostrocaudal lengthening and mediolateral narrowing. Isolated strips of epidermis exhibit autonomous movements which, unlike wound‐healing movements, are unidirectional (mediad), and region‐specific (beginning and reaching their greatest extent in the cranial region). Isolated pieces of neural plate or epidermis remain flat instead of bending, providing further evidence that the transition zone is necessary for the formation of neural folds. © 1995 wiley‐Liss, Inc.
Protein characterization and targeted disruption of Grg, a mouse gene related to the groucho transcript of the Drosophila enhancer of split complex
Authors: Mallo Moisés , Gendron‐Maguire Maureen , Harbison Margaret L. , Gridley Thomas 
Published: February 2005

AbstractThe Grg gene encodes a 197 amino acid protein homologous to the amino‐terminal domain of the product of the groucho gene of the Drosophila Enhancer of split complex. Analysis with a polyclonal antisera specific for the Grg protein revealed that Grg is a 25 kd nuclear protein that can participate in specific protein‐protein interactions. A null mutation of the Grg gene was constructed by gene targeting. Mice homozygous for this mutation completed embryogenesis and were born, but exhibited varying degrees of postnatal growth deficiency. No dosage‐sensitive genetic interaction was detected between the Notch1 and Grg genes in mice heterozygous for a Notch1 mutant allele and homozygous for the Grg null mutation. © 1995 wiley‐Liss, Inc.
Patterns of oriented cell division during the steady‐state morphogenesis of the body column in hydra
Authors: Shimizu Hiroshi , Bode Patricia M. , Bode Hans R. 
Published: February 2005

AbstractIn an adult hydra, the tissue of the body column is in a dynamic state. The epithelial cells of both layers are constantly in the mitotic cycle. As the tissue expands, it is continuously displaced along the body axis in either an apical or basal direction, but not in a circumfer‐ential direction. Using a modified whole mount method we examined the orientation of mitotic spindles to determine what role the direction of cell division plays in axial displacement. Surprisingly, the direction of cell division was found to differ in the two epithelial layers. In the ectoderm it was somewhat biased in an axial direction. In the endoderm it was strongly biased in a circumferential direction. For both layers, the directional biases occurred throughout the length of the body column, with some regional variation in its extent. As buds developed into adults, the bias in each layer increased from an almost random distribution to the distinctly different orientations of the adult. Thus, to maintain the observed axial direction of tissue displacement, rearrangement of the epithelial cells of both layers must occur continuously in the adult as well as in developing animals. How the locomotory and contractile behavior of the muscle processes of the epithelial cells may effect changes in cell shape, and thereby influence the direction of cell division in each layer, is discussed. © 1995 wiley‐Liss, Inc.
Sequence and expression pattern of the Stra7 (Gbx‐2) homeobox‐containing gene induced by retinoic acid in P19 embryonal carcinoma cells
Authors: Bouillet Philippe , Chazaud Claire , Oulad‐Abdelghani Mustapha , Dollé Pascal , Chambon Pierre 
Published: February 2005

AbstractThe cDNA sequence of Stra7, a retinoic acid (RA)‐inducible gene in P19 embryonal carcinoma (EC) cells, was determined. The deduced Stra7 protein contains a homeodomain highly similar to that of the previously described chicken CHox7 gene product, and is highly conserved during evolution, from hemichordates to vertebrates. The mouse Stra7 cDNA corresponds to the full‐length form of the 77 bp homeodomainencoding cDNA fragment which was previously cloned and termed MMoxA or Gbx‐2. Reversetranscriptase‐PCR analysis revealed the presence of Stra7/Gbx‐2 transcripts in the adult brain, spleen, and female genital tract, whereas no expression could be observed in heart, liver, lung, kidney, or testes. In situ hybridization analysis showed a restricted expression pattern of Stra7/Gbx‐2 in the three primitive germ layers during gastrulation. Restricted expression was also detected in the pharyngeal arches. Subsequently, there were specific expression domains in the developing central nervous system, at the midbrain/hindbrain boundary and later in the cerebellum anlage, in certain rhombomeres, in dorsal regions of the spinal cord, and in the developing dorsal thalamus and corpus striatum. © 1995 wiley‐Liss, Inc.
Restricted expression of the ron gene encoding the macrophage stimulating protein receptor during mouse development
Authors: Quantin Béatrice , Schuhbaur Brigitte , Gesnel Marie‐Claude , Dollé Pascal , Breathnach Richard 
Published: February 2005

AbstractThe human ron gene codes for a transmembrane protein tyrosine kinase which is a receptor for the macrophage stimulating protein. The ron receptor, together with the hepatocyte growth factor/scatter factor receptor encoded by the proto‐oncogene met, and the product of the c‐sea proto‐oncogene, make up a family of structurally related receptors. We have cloned murine ron cDNA sequences and used them as probes for in situ hybridization and Northern blot experiments. We show that ron gene expression occurs relatively late in development, and is much more restricted than that of the met gene. ron gene expression is detected in specific areas of the central and the peripheric nervous system, as well as in discrete cells in developing bones, and in the glandular epithelia along the digestive tract. © 1995 wiley‐Liss, Inc.
Expression of the integrin subunit α9 in the murine embryo
Authors: Wang Angela , Patrone Laura , McDonald John A. , Sheppard Dean 
Published: February 2005

AbstractThe α9 integrin subunit is expressed in adult skeletal muscle, visceral smooth muscle, hepatocytes, squamous epithelium, and airway epithelium. The in vivo function of this protein is unknown. Thus far, only a single α9‐containing integrin has been identified (α9β1) and only a single ligand (tenascin) has been found for this integrin. In order to gain insight into the potential function of α9 integrin(s), we examined the spatiotemporal distribution of the α9 subunit and tenascin during murine embryogenesis. In all tissues where α9 was expressed, its appearance was associated with other evidence of cell differentiation. In developing airway, visceral, and vascular smooth muscles, the onset of α9 expression either coincided with or immediately followed the expression of α‐SM actin. Expression of α9 in epithelia was restricted to the choroid plexus and the basal cell layer of squamous epithelia where its appearance coincided with the development of stratification. α9 immunostaining was first detected in developing skeletal musculature when skeletal myotubes formed. Tenascin expression was detected in many, but not all tissues found to express α9. For example, the hair germs of maturing hair follicles exhibited high levels of α9 staining, but no tenascin immunoreactivity was detected either within the hair germ themselves or in the adjacent dermis. In some tissues where tenascin expression colocalized with α9, expression patterns were not synchronous. Although α9 expression was associated with the onset of tissue differentiation, its expression was not limited to terminally differentiated cells. In fact, in the skin, α9 expression appeared restricted to cells known to retain the capacity to proliferate, i.e., basal cells and hair germs. Thus, α9 integrin(s) are not likely to contribute to the early steps in organ formation, but probably play a role in the maturation and/or maintenance of a variety of differentiated tissues. The expression of α9 without its only known ligand, tenascin, suggests the existence of additional ligands. © 1995 wiley‐Liss, Inc.
Changes in the expression of fibroblast growth factor receptors mark distinct stages of chondrogenesis in vitro and during chick limb skeletal patterning
Authors: Szebenyi Györgyi , Savage Mary Pfann , Olwin Bradley B. , Fallon John F. 
Published: February 2005

AbstractMembers of the fibroblast growth factor (FGF) family of growth factors are key regulators of limb skeletal patterning and growth. Abnormal expression of FGFs or mutations in their receptors (fgfrs) result in skeletal disorders. Here we show that changes in the expression of fgfrs are intrinsic properties of differentiating cartilage. In mesenchymal micromass cultures differentiating into cartilage, as in ovo, fgfr 1 mRNA was found predominantly in undifferentiated, proliferating mesenchyme, fgfr 2 in precartilage cell aggregates, and fgfr 3 in differentiating cartilage nodules. Thus, our data suggest that switches in the expression of fgfr 1, 2, and 3 mRNAs are associated with phases of cartilage patterning both in vitro and in ovo, and mark distinct stages in the development of the limb skeleton. © 1995 wiley‐Liss, Inc.