bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryonic expression of tenascin‐X suggests a role in limb, muscle, and heart development
Authors: Burch Grant H. , Bedolli Melanie A. , McDonough Stephen , Rosenthal Stephen M. , Bristow James 
Published: February 2005

AbstractTenascin‐X (TN‐X) is the newest member of the tenascin family of extracellular matrix proteins and it is highly expressed in muscular tissues during development. To gain insight into the possible functions of TN‐X during development, we evaluated its expression in the rat embryo. Using an 800 bp cDNA encoding the fibrinogen‐like domain of TN‐X, we show that TN‐X expression begins in migrating cells of the epicardium in the E12 heart. The epicardium provides progenitors of fibrous and vascular tissue to the developing heart. After the epicardium is complete, TN‐X is expressed in the sub‐epicardial space in association with developing blood vessels, and later by non‐myocytes dispersed through the myocardial wall. A similar pattern of TN‐X expression, first in connective tissue surrounding muscle, and then by a subset of cells within muscle, was seen in para‐axial, body wall, craniofacial, and appendicular muscle. This pattern suggests a role in connective tissue cell migration and late muscle morphogenesis. TN‐X is also highly expressed in the interdigital space at E15 and surrounding developing tendons, suggesting an additional role in cell fate determination. Although the pattern of TN‐X expression is distinct from that of tenascin C, they are frequently expressed in close proximity. Indirect genetic evidence in humans suggests an essential function for TN‐X, and the pattern of TN‐X expression in heart, skeletal muscle, and limb is consistent with this hypothesis. ©1995 Wiley‐Liss, Inc.
Specification of multiple vertebral identities by ectopically expressed Hoxb‐8
Authors: Charité Jeroen , de Graaff Wim , Deschamps Jacqueline 
Published: February 2005

AbstractWe have recently generated Hoxb‐8 gain‐of‐function mutant embryos, using a Hoxb‐8 transgene driven by a retinoic acid receptor β2 promoter to extend the expression domain to more anterior regions of the embryo (Charité et al. [1994] Cell 78:589–601). Here we describe the phenotype in the axial skeleton of transgenic embryos. The severity of the phenotype was variable, and cervical vertebrae and the base of the skull were affected in different ways. We observed fusion of the anterior arch of the atlas to the dens of the axis, partial splitting of the vertebral body and the neural arch of the axis, and abnormal morphology of the basioccipital and exoccipital bones. The basioccipital bone projected into the atlas, sometimes fusing to the dens of the axis; the exoccipital bones appeared to be transformed towards neural arch‐like structures. A novel pattern of posterior homeotic transformations was observed, involving cervical vertebrae C3 to C7: the ventral aspect of vertebrae C5 to C7 could acquire different morphologies characteristic of more posterior vertebrae: C5 could be transformed into C6, C7, or T1, C6 into C7 or T1, and C7 into T1. Phenotypes of different severity could be arranged into a phenotypic series, starting with the transformation of C7 to T1 and involving transformation of increasingly more anterior vertebrae into increasingly more posterior identities; no vertebra acquired a more posterior morphology than that of the vertebra immediately caudal to it. Ribs appeared to be formed relatively independently of rib heads; cervical ribs (but not rib heads) could be observed as anterior as C3. The results suggest that higher levels of ectopically expressed Hoxb‐8 result in specification of more posterior vertebral identities. © 1995 wiley‐Liss, Inc.
Developmental defects of the ventromedial hypothalamic nucleus and pituitary gonadotroph in the Ftz‐F1 disrupted mice
Authors: Shinoda Koh , Lei Hong , Yoshii Hironori , Nomura Masatoshi , Nagano Mamoru , Shiba Hiroharu , Sasaki Hiroshi , Osawa Yoshio , Ninomiya Yasuharu , Niwa Ohtsura , Morohashi Ken‐Ichirou , Li En 
Published: February 2005

AbstractAd4BP (or SF‐1) has been identified as a transcription factor which regulates all the steroidogenic P450 genes in the peripheral organs, and is encoded by the mammalian homologue of Drosophila FTZ‐F1 gene. mRNA coding for Ad4BP was detected in the hypothalamus and pituitary of rats by RT‐PCR. Immunohistochemical analyses using an antiserum to Ad4BP in the brain and pituitary revealed that the transcription factor is expressed in nuclei of the dorso‐medial part of the ventromedial hypothalamus (dmVMH) and in some subpopulation of the adenohypophysial cells. Double immunostaining of the pituitary for Ad4BP and trophic peptide hormones, FSH, TSH, and ACTH, indicated a restricted localization of Ad4BP to the gonadotroph. Disruption of the mouse Ftz‐F1 gene was clarified to induce severe defects in the organization of the dmVMH and the function of the pituitary gonadotroph. However, some of the dm VMH neurons and pituitary gonadotrophs persisted, which provided a sharp contrast to complete agenesis of the peripheral steroidogenic tissues (adrenal and gonads) in the mutant mouse. Additional abnormalities were seen in the ventrolateral part of VMH and dorsomedial hypothalamic nucleus, both of which do not express Ad4BP but have strong reciprocal fiber‐connections with the dmVMH. Aromatase P450‐containing cells in the medial preoptico‐amygdaloid region, which were devoid of Ad4BP, persisted even in the brain of the gene disrupted mice. The present results clearly showed that the hypothalamic and pituitary Ad4BPs are essential to normal development of the functional VMH and gonadotroph through some mechanism distinct from that in the peripheral steroidogenic tissues. © 1995 wiley‐Liss, Inc.
Two closely related receptor‐type tyrosine phosphatases are differentially expressed during rat lung development
Authors: Katsura Hideki , Williams Mary C. , Brody Jerome S. , Yu Qiang 
Published: February 2005

AbstractTransmembrane protein tyrosine phosphatases (PTPases) comprise a newly identified class of receptor‐like molecules. In most cases their ligands and the substrates they dephosphorylate are not known. In order to begin to explore the functions of the PTPases in cell physiology and in mammalian development, we examined the expression patterns of two closely related receptor‐type tyrosine phosphatase genes, namely LAR and PTPδ, in fetal rat lung and in selected adult rat tissues. In the lung, in situ hybridization and immunohistochemistry show that the LAR mRNA and protein are expressed exclusively in the epithelium. In the early embryonic or fetal lung (day 13 to 18) LAR is expressed by all of the epithelial cells of the forming bronchial tree. This widespread pattern of expression is lost later in fetal life (day 21) as the lung matures and acquires the morphologic and biochemical features of the adult organ. LAR gene expression is then confined to two epithelial progenitor cells of the distal airways, namely the bronchiolar Clara cell and the alveolar type II cell. The LAR gene products were also found abundantly expressed in epithelial progenitor cells of adult esophagus, skin, and small intestine, all of which are continuously renewing epithelia. The rat PTPδ gene, on the other hand, is specifically expressed in the mesenchyme of the developing lung. The level of the PTPδ mRNA decreases as the lung matures. These results suggest that the two closely related receptor‐type tyrosine phosphatases are differentially expressed in a tissue‐specific fashion. They are expressed mostly in proliferating cells or in cells which have potential to proliferate. Therefore, one function of the two receptor‐like tyrosine phosphatases may be to regulate proliferation and/or differentiation of different types of cells during development, during normal cell turnover, and during adult tissue repair. © 1995 wiley‐Liss, Inc.
Myoepithelial cell diffeentiation in the developing mammary gland: Progressive acquisition of smooth muscle phenotype
Authors: Deugnier Marie‐Ange , Moiseyeva Elena P. , Thiery Jean Paul , Glukhova Marina 
Published: February 2005

AbstractThe most important portion of the mammary gland development occurs postnatally, with distinct periods of intensive morphogenesis taking place btween birth and puberty and during pregnancy and lactation. To characterize the differentiation process of mammary myopithlial cells, we have studied the expression patterns of several smooth musle phenotypic markers, including contractile proteins, α‐smooth muscle‐actin (α‐SM‐actin), smooth muscle myosin heavy chains (SM‐MHC), and calponin; components of cell‐extracellular matrix aderens junctions, phosphoglucomutase‐related protein (PGM), vinculin variants, integrin subunits; and laminin variant chains in the developing rat mammary gland using immunofluorescence microscopy. α‐SM‐actin‐ and SM‐MHC‐positive cells were found first in newborn animals, while calponin, PGM, and α1 integrin subunit began to be expressd in prepubertal animals (1.5 weeks). Vinculin, β1 and α3 integrin subunit were largely confined to the basal cell layer at all developmental stages examined with greater staining starting at 1.5 weeks. Meta‐vinculin was identifed only in myoepithelial cells of the lactating gland. γ1 laminin chain was present in the mammary gland basement membrane throughout development, while the β2 chain was revealed in 3‐week‐old animals and accumulated later in pospubertal animals (7 weeks). Similarly, β2 laminin chain was absent from the forming alveoli basement membrane in pregnant rats and started to accumulate in the lactating gland. In addition to temporal changes, we have observed spatial differences in the distribution of the phenotypic markers. Both in pre‐ and in postpubertal animals, α‐SM‐actinand SM‐MHC‐positive cells of the growing ductal ends contained low amounts if any of calponin, PGM, and β2 laminin chain. We conclude that during postnatal development, mammary myoepithelial cells progressively acquire a differentiated phenotype as revealed by the expression of various smooth muscle markers. Maturation of the myoepithelial cells is accompanied by upregulation of the smooth muscle integrin expression followed by accumulation of β2‐containing laminin variant. Thus, changes in adhesion system parallel with the myoepithelial cell differentiation. © 1995 wiley‐Liss, Inc.
Dystroglycan mRNA expression during normal and mdx mouse embryogenesis: A comparison with utrophin and the apo‐dystrophins
Authors: Schofield Julian N. , Górecki Dariusz C. , Blake Derek J. , Davies Kay , Edwards Yvonne H. 
Published: February 2005

Abstractα dystroglycan (156 kDa DAG) and β dystroglycan (43 kDa DAG) are encoded by the same gene and are components of the dystrophin‐associated membrane glycoprotein complex. The dystroglycans together with dystrophin form a link between the extracellular matrix and the intracellular cytoskeleton of the muscle fibre. Using in situ hybridisation to mRNA in embryo sections we have examined the expression of the mouse dystroglycan gene. Dystroglycan transcripts are ubiquitously expressed throughout developmnet but are most abundant in cardiac, skeletal and smooth muscle and in ependymal cells lining the developing neural tube and brain. The expression patterns of dystroglycan and dystrophin ovrlap in the major muscle systems during development, suggesting that the dystrophin‐dystroglycan complex plays an important role during myogenesis. In contrast, the major sites of utrophin expression do not co‐localize with those of dystroglycan suggesting that utrophin may interact with a distinct membrane‐associated complex in these non‐muscle sites. In mdx embryos the pattern of distribution of dystroglycan mRNA remains unchanged, as do those of utrophin and apo‐dystrophin mRNAs. This observation implies that the observed changes in the relative abundance of DAGs and utrophin in dystrophin‐deficient muscle occur post‐transcriptionally. © 1995 wiley‐Liss, Inc.
Appearance of neurons in the developing chick gut
Authors: Fairman Colin L. , Clagett‐Dame Margaret , Lennon Vanda A. , Epstein Miles L. 
Published: February 2005

AbstractThe enteric nervous system is formed from neural crest‐derived cells. These cells enter the gut, migrate, proliferate, and ultimately differentiate into neurons and glia. We have used a human anti‐neuronal autoantibody (ANNA‐1), which recognizes neuron‐specific RNA‐binding proteins of the Hu family as an early marker of neuronal phenotype, to study the appearance of enteric neurons in the developing chicken gut. Immunoreactive cells appear first in the gizzard primordium at E3.5 and are found at progressively more caudal locations in the gut as development proceeds. Nascent neurons are present at the yolk stalk at E4.5, at the ileocecal junction at E6.5, and within the rectum at E7.5–8.5. Neurons appear slightly later in the esophagus. Aggregates of cells resembling developing ganglia were first observed at E6.5 in the distal esophagus and at E8.5 in the proximal esophagus. A small number of cells appeared in the vagus nerve trunks at E4.5 and that number increased at E7.5–8.5. Immunoreactive cells were also found in the sympatho‐aortic plexus between the mesonephri and in the dorsal mesentery. These cells appeared to coalesce and form the ganglionated Nerve of Remak which contained positive cells at E3.5. This Nerve extended to the yolk stalk at E4.5 and to duodendum at E6.5. We conclude that the appearance of nascent neurons occurs first in the gizzard and proceeds more rapidly in a distal than proximal direction along the gut. Furthermore, cells that appear to be nascent neurons are found in the vagus and in the dorsal mesentery. © 1995 wiley‐Liss, Inc.
Coordinate expression of vascular endothelial growth factor receptor‐1 (fit‐1) and its ligand suggests a paracrine regulation of murine vascular development
Authors: Breier Georg , Clauss Matthias , Risau Werner 
Published: February 2005

AbstractVascular endothelial growth factor (VEGF) is a candidate regulator of blood vessel growth during embryonic development and in tumors. To evaluate the role of VEGF receptor‐1/flt‐1 (VEGFR1/flt‐1) in the development of the vascular system, we have characterized the murine homolog of the human flt‐1 gene and have analyzed its expression pattern during mouse embryogenesis. Receptor binding studies using transfected COS cells revealed that the murine flt‐1 gene encodes a high affinity receptor for VEGF. The apparent Kd for VEGF binding, as determined by Scatchard analysis, was 114 pM, demonstrating that VEGFR1/flt‐1 has a higher affinity to VEGF than VEGF receptor‐2/flk‐1 (VEGFR2/flk‐1). By in situ hybridization, VEGFR1/flt‐1 was detected in the yolk sac mesoderm already at the early stages of vascular development, while the receptor ligand was expressed in the entire endoderm of 7.5‐day mouse embryos. A comparison with VEGFR2/flk‐1 showed that the two receptors shared a common expression domain in the yolk sac mesoderm, but were expressed at different sites in the ectoplacental cone. The differential expression of the two VEGF receptors persisted in the developing placenta, where VEGFR1/flt‐1 mRNA was detected in the spongiotrophoblast layer, whereas VEGFR2/flk‐1 transcripts were present in the labyrinthine layer which is the site of VEGF expression. In the embryo proper, VEGFR1/flt‐1 mRNA was specifically localized in blood vessels and capillaries of the developing organs, closely resembling the pattern of VEGFR2/flk‐1 transcript distribution. In the developing brain, the expression of VEGF receptors in the perineural capillary plexus and in capillary sprouts which have invaded the neuroectoderm correlated with endothelial cell proliferation and brain angiogenesis. The data are consistent with the hypothesis that VEGF and its receptors have an important function both in the differentiation of the endothelial lineage and in the neovascularization of developing organs, and act in a paracrine fashion. © 1995 wiley‐Liss, Inc.
Enhanced expression of mouse c‐ski accompanies terminal skeletal muscle differentiation in vivo and in vitro
Authors: Namciu Stephanie , Lyons Gary E. , Micales Bruce K. , Heyman Hong‐Chen , Colmenares Clemencia , Stavnezer Ed 
Published: February 2005

AbstractOverexpression of either v‐ski, or the proto‐oncogene, c‐ski, in quail embryo fibroblasts induces the expression of myoD and myogenin, converting the cells to myoblasts capable of differentiating into skeletal myotubes. In transgenic mice, overexpression of ski also influences muscle development, but in this case it effects fully formed muscle, causing hypertrophy of fast skeletal muscle fibers. In attempts to determine whether endogenous mouse c‐ski plays a role in either early muscle cell determination or late muscle cell differentiation, we analyzed mRNA expression during muscle development in mouse embryos and during in vitro terminal differentiation of skeletal myoblasts. To generate probes for these studies we cloned coding and 3′ non‐coding regions of mouse c‐ski. In situ hybridization revealed low c‐ski expression in somites, and only detected elevated levels of mRNA in skeletal muscle beginning at about 12.5 days of gestation. Northern analysis revealed a two‐fold increase in c‐ski mRNA during terminal differentiation of skeletal muscle cell lines in vitro. Our results suggest that c‐ski plays a role in terminal differentiation of skeletal muscle cells not in the determination of cells to the myogenic lineage. © 1995 wiley‐Liss, Inc.
Expression of M‐twist during postimplantation development of the mouse
Authors: Füchtbauer Ernst‐martin 
Published: February 2005

AbstractThe murine homologue of the Drosophila twist gene has been shown to be essential for head mesenchyme formation and to act as an inhibitor of muscle differentiation. This paper presents a detailed analysis of M‐twist expression patterns from day 7 post coitum (p.c.) to day 18 p.c., indicating a more general function of the M‐twist gene. At day 7 p.c., M‐twist is expressed in the mesoderm outside the primitive streak. Later M‐twist message is predominantly found in the somites, the head mesenchyme, the branchial arches, the limbs, and in the mesenchyme underneath the epidermis. Beginning at day 8 p.c., M‐twist is mainly expressed in undifferentiated cells committed to muscle and cartilage development: this exspression is consistent with a suggested role of M‐twist in inhibiting overt muscle and cartilage differentiation. However, during organogenesis, M‐twistt is expressed in several areas of mesenchyme‐epithelia interactions, suggesting additional tissue specific functions. © 1995 wiley‐Liss, Inc.
Developmental regulation of connexin 40 gene expression in mouse heart correlates with the differentiation of the conduction system
Authors: Delorme Bruno , Dahl Edgar , Jarry‐guichard Thérèse , Marics Irène , Briand Jean‐Paul , Willecke Klaus , Gros Daniel , Théveniau‐Ruissy Magali 
Published: February 2005

AbstractIn adult mouse heart, CX40 is expressed in the atria and the proximal part of the ventricular conduction system (the His bundle and the upper parts of the bundle branches). This cardiac tissue is specialized in the conduction of the electrical impulse. CX40 is the only mouse connexin known to be expressed in these parts of the adult conductive tissue and is thus considered as a marker of the conduction system. In the present report, we investigated CX40 expression and distribution during mouse heart development. We first demonstrate that CX40 mRNA is regulated throughout development, as are other heart connexin transcripts, i.e., CX37, CX43, and CX45, with a decreasing abundance as development proceeds. We also show that the CX40 transcript and protein are similarly regulated, CX40 being expressed as two different phosphorylated and un‐phosphorylated forms of 41 and 40 kDa, respectively. Surprisingly, distribution studies demonstrated that CX40 is widely expressed in 11 days post‐coitum (dpc) embryonic heart, where it is detected in both the atria and ventricle primordia. As development proceeds, the CX40 distribution pattern in the atria is maintained, whereas a more dynamic pattern is observed in the ventricles. From 14 dpc onwards, as the adult ventricular conduction system differentiates, CX40 decreases in the trabecular network and it is preferentially distributed in the ventricular conduction system. CX40 is thus the marker of the early differentiating conduction system. It is hypothesized that the conduction system is present in unorganized “embryonic” form at 11 dpc and trans‐differentiates by 14 dpc into the adult conduction system. © 1995 wiley‐Liss, Inc.
Formation of new myotubes occurs exclusively at the multiple innervation zones of an embryonic large muscle
Authors: Duxson M. J. , Sheard P. W. 
Published: February 2005

AbstractThis work examines the general principle of whether production of embryonic muscle fibres is invariably linked to sites of innervation, as we have previously reported in small rodent muscles (Duxson et al. [1989] Development 107:743–750). The experimental strategy has been to make a detailed electron microscopic analysis of the formation of new myotubes in a large muscle having multiple, discrete innervation zones. The particular model system is the guinea pig sternomastoid muscle, a strap‐like, parallel‐fibred muscle with four distinct endplate bands, both in the embryo and the adult. Primary myotubes in the developing muscle extended from tendon to tendon of the muscle and were innervated at each of the multiple endplate zones. Each point of innervation of the primary myotubes was a focus around which many new secondary myotubes formed, and each secondary myotube was approximately centred on one of the innervation sites of its supporting primary myotube. This confirms our previous report, in rat IVth lumbrical muscle, of an invariable association between sites of formation of new secondary myotubes and sites of innervation. We suggest that, in vivo, nerve terminals either directly induce the initial myoblast fusions which give rise to new secondary myotubes, or induce some precondition for fusion. An alternative hypothesis is that a common patterning influence in the muscle localizes both innervation and secondary myotube formation to the same zone. The pattern of secondary myotube production in the embryo has important implications for the size and final architecture of muscles in larger animals, and some of these are discussed. © 1995 wiley‐Liss, Inc.
Cdk family genes are expressed not only in dividing but also in terminally differentiated mouse germ cells, suggesting their possible function during both cell division and differentiation
Authors: Rhee Kunsoo , Wolgemuth Debra J. 
Published: February 2005

AbstractThe roles of the cyclin dependent kinase (Cdk) family in murine germ cell development have been examined by studying the expression of five Cdk family genes (Cdc2, Cdk2, Cdk4, Pctaire‐1, and Pctaire‐3) in mouse reproductive organs. Northern blot and in situ hybridization analyses revealed distinctive expression patterns of these genes with striking cellular, lineage, and developmental stage specificity. We observed Cdk expression in cell types with proliferative activity: Cdc2 and Cdk2 expression in premeiotic spermatocytes in the testis, and Cdc2, Cdk2, and Cdk4 expression in granulosa cells of ovarian follicles. Cdc2 transcripts were most abundant in late pachytene to diplotene spermatocytes, soon to undergo meiosis. Surprisingly, we also observed expression of Cdk family genes in non‐proliferating cell types. All five Cdk family genes examined were expressed in Sertoli cells of the adult testis, which are no longer mitotically active. With regard to Pctaire‐1 and Pctaire‐3, the highest levels of expression were observed in postmeiotic spermatids. Immunoblot analysis also revealed the presence of high levels of Pctaire‐1 in postmeiotic germ cells. These results suggest that Cdk family kinases may exhibit various functions in germinal and somatic cells during gametogenesis, not only in the cell cycle but also in other regulatory processes, including differentiation. © 1995 wiley‐Liss, Inc.