bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular cloning of tyrosine kinases in the early Xenopus embryo: Identification of eck‐related genes expressed in cranial neural crest cells of the second (Hyoid) Arch
Authors: Brändli A. W. , Kirschner M. W. 
Published: February 2005

AbstractGrowth factors and their receptors play an important role in controlling cellular proliferation, migration, and differentiation during vertebrate embryogenesis. We have used the reverse transcription‐polymerase chain reaction to survey the repertoire of receptor tyrosine kinases (TK) expressed during early embryogenesis of Xenopus laevis. Twelve distinct Xenopus TK cDNA classes were identified among a total of 352 cDNAs screened. A single TK cDNA class has been described previously and encodes the fibroblast growth factor receptor FGFR‐A1. The remaining 11 TK cDNA classes appear to encode novel genes of the FGFR, platelet‐derived growth factor receptor (PDGFR), Eph, Csk, Tyk2, and Klg subfamilies. By RNase protection assays, Xenopus TK mRNAs are rare transcripts (≤107 mRNA mol‐ecules/embryo), and are usually found to be expressed also maternally in the embryo. Most Xenopus TK genes examined by whole‐mount in situ hybridization were expressed widely in tissues derived from multiple germ layers. Two Eck‐related genes, however, were found to be restricted in their expression to neural crest of the second (hyoid) arch. Our findings are consistent with the proposed function of TKs in the regulation of specification and differentiation of embryonic tissues. ©1995 Wiley‐Liss, Inc.
Syndecan‐3, tenascin‐C, and the development of cartilaginous skeletal elements and joints in chick limbs
Authors: Koyama Eiki , Leatherman Judith L. , Shimazu Atsushi , Nah Hyun‐Duck , Pacifici Maurizio 
Published: February 2005

AbstractThe mechanisms by which the early limb cell condensations and interzone mesenchyme give rise to skeletal elements and joints are poorly understood. Previous work from this laboratory has shown that the extracellular matrix protein tenascin‐C is associated with articular cartilage and joint tissue development; others have shown that tenascin‐C may exert its biological activities via interactions with cell surface receptors, such as syndecans. To further analyze the roles of tenascin‐C and its putative receptors in skeletal development, we carried out a detailed in situ hybridization analysis of tenascin‐C and syndecan‐3 gene expression during development of chick limb skeletal elements and joints. We found that as the early mesenchymal condensations chondrify around day 5 (E5) of development, they become surrounded by a thick syndecan‐3 rich perichondrium while tenascin‐C transcripts are much fewer and restricted to diaphyseal perichondrium and developing interzones. Similar patterns were observed as distal carpal and digit condensations formed in older embryos. As the cartilaginous long bone models elongated proximo‐distally and joint formation proceeded with age, we observed that syndecan‐3 transcripts decrease significantly along the diaphysis and remain very abundant along the metaphysis and in the epiphyseal articular cap and interzone. Conversely, tenascin‐C RNAs remain abundant along the diaphysis and begin to increase at the epiphysis and in interzone‐derived tissues, such as menisci and joint capsule. By E10, the skeletal elements have well‐defined morphologies, endochondral ossification has initiated in their diaphysis, and diaphyseal perichondrium has become periosteum. These developmental changes were accompanied by equally marked changes in gene expression; these included a marked increase in tenascin‐C gene expression in articular cap, fragmentation of tenascin‐C gene expression along the periosteum, reinitiation of syndecan‐3 gene expression in periosteum, and differential gene expression in osteoprogenitor cells. The sheer complexity of the gene expression patterns documented in this study attests to the complexity of processes that bring about normal skelatogenesis. Clearly, tenascin‐C and syndecan‐3 appear to be closely associated with several of these processes, particularly in establishing tissue boundaries (perichondrium and periosteum) between condensations and surrounding mesenchymal cells, in regulating perichondral cell differentiation and incorporation into the growing skeletal elements, and in the genesis of epiphyseal chondrocytes and associated joint tissues. ©1995 Wiley‐Liss, Inc.
Expression of the helix‐loop‐helix gene Id3 during murine embryonic development
Authors: Ellmeier Wilfried , Weith Andreas 
Published: February 2005

AbstractThe family of dominant‐negative helix‐loop‐helix (dnHLH) transcriptional modulators consists of four mammalian genes known to date: Id1, Id2, Id3 (Id3 was formerly designated HLH462 or HEIR1 or HLH1R21), and Id4. We have performed a detailed study of Id3 expression in mouse embryos in order to gain insight into the possible developmental control functions of this gene and to compare its expression to that of other mammalian dnHLH genes. Employing RNA in situ hybridization on sectioned mouse embryos of gestational stages E9.5–17.5 and neonatal head, we generally detected a high abundance of transcripts at early stages that gradually declined at most sites toward E15.5. Expression of Id3 in embryos was detected in brain, spinal cord, olfactory system, branchial arches, limbs, sclerotome, endocardiac cushions, the outer lining of the gut, lung, retina, the collecting system of the kidney, and in tooth anlagen. Although the abundance of mRNA decreased toward later stages in most tissues, it remained high in teeth and kidney. This expression pattern suggests that Id3 functions both in undifferentiated tissues and in organs which are in the process of differentiation. When compared to the expression of other dnHLH genes, it becomes obvious that the pattern of Id3 mainly coincides with that of Id1. This may reflect a partial redundancy in gene function. Furthermore, previous experiments suggested a mutually exclusive expression of the proto‐oncogene N‐myc an Id3. The results of the present study confirm these data. ©1995 Wiley‐Liss, Inc.
Expression of genes encoding bone morphogenetic proteins and sonic hedgehog in talpid (ta3) limb buds: Their relationships in the signalling cascade involved in limb patterning
Authors: Francis‐West P. H. , Robertson K. E. , Ede D. A. , Rodriguez C. , Izpisúa‐Belmonte J. C. , Houston B. , Burt D. W. , Gribbin C. , Brickell P. M. , Tickle C. 
Published: February 2005

AbstractThe chicken mutant talpid3 (ta3) has polydactylous limbs with up to 7–8 morphologically similar digits. This lack of antero–posterior polarity in digit pattern is correlated with symmetrical expression of genes of the HoxD complex. We determined the distribution of polarizing activity in limb buds of the chick mutant ta3 by assessing the ability of mesenchyme from various positions along the antero‐posterior axis to induce digit duplications when grafted anteriorly into a normal limb. Cells with highest polarizing activity were found at the posterior margin of the wing as in the polarizing region of normal limb buds. However, in contrast to normal limb buds, ta3 anterior mesenchyme also had low polarizing activity. Application of retinoic acid or a polarizing region graft to the anterior of ta3 limb buds changed digit morphology but did not induce digit duplications or digits with any characteristic a–p pattern. To determine which genes are associated with polarizing activity and which are associated with patterning of the digits, we examined expression of the genes Sonic hedgehog (shh), Bmp‐2, and Bmp‐7, whose expression is normally confined to the posterior margin of the early wing bud and is associated with the polarizing region. In addition, we determined the distribution of Fgf‐4 transcripts which in normal limb buds are restricted to the posterior part of the apical ectodermal ridge. In ta3 limb buds, shh expression is restricted to the posterior limb mesenchyme, which has high polarizing activity, but is not expressed in regions which have low polarizing activity. In contrast, Bmp‐2 and Bmp‐7 are expressed uniformly along the a–p axis. Fgf‐4 transcripts are present throughout the apical ectodermal ridge in ta3 limb buds. In the ta3 mutant, there is both an abnormal distribution of signalling activity and response to polarizing signals. In addition, the dissociation between the expression of shh and Bmps suggests distinct roles for the encoded molecules in signalling and response in a–p patterning of limb buds. ©1995 Wiley‐Liss, Inc.
Tissue‐Specific and differential expression of alternatively spliced α1(II) collagen mRNAs in early human embryos
Authors: Lui Vincent C. H. , Ng Ling Jim , Nicholls John , Tam Patrick P. L. , Cheah Kathryn S. E. 
Published: February 2005

AbstractExpression of the α1(II) procollagen gene is not confined to chondrogenic tissues during vertebrate development. Transcripts of the human gene (COL2A1) are alternatively spliced to give mRNAs which either exclude (type IIB mRNA) or include (type IIA mRNA) an exon encoding a cysteine‐rich domain in the amino‐propeptide. The distribution of COL2A1 mRNAs in 27‐ to 44‐day human embryos and 8‐ to 24‐week fetuses was studied by in situ hybridization and RNase protection analyses. Type IIA mRNAs were expressed in prechondrogenic cells and were also preferentially expressed in chondrogenic tissues at regions of chondrocyte commitment and cartilage growth. During maturation of chondrocytes, there is a switch to expression of type IIB mRNAs. In non‐chondrogenic tissues of early embryos, type IIA mRNA expression was associated with active tissue remodeling, epithelial organization, and sites of tissue interaction. Type IIA mRNAs were also expressed in some non‐chondrogenic tissues where expression had previously been undetected, such as the tooth bud, liver, adrenal cortex, apical ectodermal ridge, and indifferent gonad. In older fetuses type IIA mRNAs were the sole or major transcript in most non‐chondrogenic tissues except the choroid plexus and tendon. In the meninges there was a unique switch from type IIB to type IIA expression. The expression pattern of COL2A1 transcripts suggests that, in addition to contributing to the structural integrity of the cartilage extracellular matrix, type II procollagen may serve a morphogenetic role in embryonic development. Our findings clearly show that the pattern of expression of type II procollagen mRNAs is largely conserved between man and mouse. However, some differences exist, and these should be taken into consideration when animal models are used to study human diseases associated with COL2A1. ©1995 Wiley‐Liss, Inc.
New gene, nel, encoding a Mr 93 K protein with EGF‐like repeats is strongly expressed in neural tissues of early stage chick embryos
Authors: Matshuhashi Sachiko , Noji Sumihare , Koyama Eiki , Myokai Fumio , Ohuchi Hideyo , Taniguchi Shigehiko , Hori Katsuji 
Published: February 2005

AbstractA new gene, nel, was isolated from a 9‐day‐old chick embryonic cDNA library. The gene encoes a protein of 835 amino acids (93,407 Mr) consisting of two hydrophobic domains presumed to be the signal and transmembrane sequences, a histidine rich domain, two repeats of a cysteine rich structure similar to the C‐terminal domain of von Willebrand factor, five EGF‐like repeats, and again two repeats of the cysteine rich sequence similar to the C‐terminal domain of von Willebrand factor in the presumed cytoplasmic domain. The expression of the nel gene was studied by Northern blot and in situ hybridization analyses of chick embryos. The mRNA of the gene was found in all tissues of 10‐ and 17‐day‐old embryos by Northern blot hybridization. Among the tissues examined, the level in the brain was highest and increased with age. After hatching, gene expression was retained in the brain at about the same level found in old embryos, increased in the retina, and disappeared from the other tissues. In situ hybridization with a nel gene probe revealed that the gene was strongly expressed in neural tissues such as brain, spinal cord, and dorsal root ganglia of early embryos. Gene expression was observed in the mantle layer of the neurepithelium of the brain and of the spinal cord. Gene expression in early embryos was not restricted to the neural tissues, but was also detected in the cells around cartilage, myocardium, lung mesenchymal cells, and in the liver, etc. One band of about 4.5 Kb mRNA was detected in all tissues and stages by Northern blot hybridization analysis. The possible function of the gene is discussed. ©1995 Wiley‐Liss, Inc.
Pattern of keratinocyte growth factor and keratinocyte growth factor receptor expression during mouse fetal development suggests a role in mediating morphogenetic mesenchymal‐epithelial interactions
Authors: Finch Paul W. , Cunha Gerald R. , Rubin Jeffrey S. , Wong Jane , Ron Dina 
Published: February 2005

AbstractMesenchymal cells are required for the induction of epithelial development during mammalian organogenesis. Keratinocyte growth factor (KGF) is a mesenchymally derived mitogen with specific activity for epithelial cells, suggesting that it may play a role in mediating these interactions. To further evaluate this hypothesis, in situ hybridization was used to examine the spatial distribution of KGF and KGF receptor (KGFR) transcripts during organogenesis and limb formation in mouse embryos (days 14.5 through 16.5). To facilitate this aim, mouse KGF cDNA clones were isolated. There was extensive identity between the deduced mouse KGF protein sequence and that of its human and rat cognates, indicating that this gene has been highly conserved during mammalian evolution. In addition, mouse KGF protein was purified from fibroblasts and demonstrated to be structurally and functionally similar to human KGF protein. For organs within the integumental, respiratory, gastrointestinal, and urogenital systems, whose development is dependent upon mesenchymal‐epithelial interactions, KGF mRNA was detected in mesenchymal cells, while epithelial cells expressed transcripts for the KGFR. KGF and KGFR mRNA was also expressed in certain other tissues such as perichondrium, cartilage of developing bones, developing skeletal muscle, and visceral smooth muscle whose development is not regulated by mesenchymal‐epithelial interactions. KGF expression was also detected in tissues isolated from human embryos, suggesting similar functions for KGF in human development. Taken together, our results suggest that KGF plays an important role in mediating mesenchymal‐epithelial interactions during organogenesis, but may also have other developmental functions in tissues not governed by such interactions. ©1995 Wiley‐Liss, Inc.
Drosophila glutamate receptor RNA expression in embryonic and larval muscle fibers
Authors: Currie Douglas A. , Truman James W. , Burden Steven J. 
Published: February 2005

AbstractGlutamate is the excitatory transmitter at neuromuscular synapses in Drosophila, and electrophysiological studies indicate that the receptors for glutamate are concentrated in muscle fibers at synaptic sites. Acetylcholine is the excitatory transmitter at vertebrate neuromuscular synapses, and previous studies have shown that accumulation of acetylcholine receptors (AChRs) at synaptic sites is controlled both by transcriptional and post‐translational mechanisms. The transcriptional pathway culminates in selective expression of AChR subunit genes in nuclei near the synaptic site, causing AChR mRNA to accumulate in the synaptic region of the muscle fiber. We used a cDNA encoding a subunit of the Drosophila muscle glutamate receptor (DGluR‐II) to determine the temporal and spatial expression pattern of the DGluR‐II gene during embryogenesis and in larval muscle. We show that DGluR‐II mRNA is first expressed at stage 12 of embryogenesis and that expression is detected in developing dorsal, lateral, and ventral somatic muscles within the next 2 hr. By stage 16 DGluR‐II mRNA is expressed in all somatic muscles and in pharyngeal muscles. In third instar larvae DGluR‐II mRNA is expressed in all body‐wall muscle fibers. DGluR‐II mRNA, however, is expressed throughout the larval muscle fibers and is not concentrated within muscle fibers at neuromuscular synapses. These results indicate that although the DGluR‐II gene is expressed in somatic muscle cells it is not selectively expressed in nuclei near the synaptic site. ©1995 Wiley‐Liss, Inc.
Expression of transforming growth factor β in the embryonic avian lens coincides with the presence of mitochondria
Authors: Potts Jay D. , Bassnett Steven , Beebe David C. 
Published: February 2005

AbstractDuring their maturation, lens cells lose all membrane bound organelles, including mitochondira. In chicken embryos this process begins in the central lens fibers beginning around embryonic day 12 (E12). Transforming growth factor β (TGFβ) is a multipotent growth modulator thought to play a role in numerous developmental processes. TGFβ1 has been localized to mitochondria in rat liver cells and muscle cells. In the present study, we examined the expression of TGFβ isoform mRNAs and proteins during chicken embryonic lens development. PCR analysis demonstrated TGFβ2 and TGFβ3 trasncripts in the lens epithelium and fibers throughout pre‐ and post‐hatching development. TGFβ isoforms were detected throughout the lens epithelium and fibers early in development (E6). However by E19, the distribution of TGFβ2 and TGFβ3 transcripts and proteins coincided with regions of the lens that contained mitochondria. In addition, intense TGFβ staining was observed in the basal portions of the equatorial epithelial cells, a region with abundant mitochondria. Transcripts for TGFβ1 and TGFβ4 were not detected in any tissue or time frame examined. Similarly, no immunostaining for TGFβ1 was observed. ©1995 Wiley‐Liss, Inc.
Migration of myogenic cells from the somites to the fore‐limb buds of developing mouse embryos
Authors: Sze Lung‐Yum , Kenneth Lee K. H. , Webb Sarah E. , Li Zhenlin , Paulin Denise 
Published: February 2005

AbstractIn this study, we have isolated newly formed somites from the caudal regions of 8.5 day mouse embryos and transplanted them orthotopically into correspondingly staged hosts at the level of the prospective limb‐forming region. The experimental embryos were then cultured intact for 32‐36 hr. The donor somites used were pre‐labelled with DiI, a fluorescent lipophilic dye, or were obtained from transgenic embryos that carried a 1 kb 5′ regulatory sequence of the desmin gene linked to the gene encoding Escherichia coli β‐galactosidase. The transgene is specifically expressed in skeletal muscles (Li et al. [1993] Development 117:947‐959). The aim of these experiments was to show definitively that the musculature of the mammalian limb is derived from the somites. The results demonstrated that DiI‐labelled cells from the implanted somites were able to invade the proximal region of the fore‐limb bud during the course of development. The use of transgenic somites as grafts confirmed that some of the somitic cells found in the limbs were myogenic cells. To determine whether the displacement of somitic cells is an active or passive process, somatopleure obtained from the prospective limb‐forming regions of day 8.5 day embryos was implanted into 8.5 day hosts. We did not detect the presence of DiI‐labelled somatopleural cells in the fore‐limb after 32‐36 hr of culture. This suggests that somitic cells reached the limb bud via active locaomotion rather than as a result of being passively dragged there, as the limb elongates during development. In addition, we injected latex beads into the somites, as probes, to determine whether extracellular matrix‐driven translocation plays a role in driving the somitic cells to the limb bud. In a majority of the specimens examined, we could not detect the presence of these beads in the limb bud. However, in the trunk of these embryos, the beads were found dispersed throughout the ventral neural crest pathway.
Expression of a type II collagen gene in the zebrafish embryonic axis
Authors: Yan Yi‐Lin , Hatta Kohei , Riggleman Bob , Postlethwait John H. 
Published: February 2005

AbstractTo understand the hierarchy of developmental controls underlying axis specification in vertebrate embryos, it is helpful to identify relationships between regulatory molecules and the genes that given axial cells their differentiated phenotypes. This work reports the cloning and expression pattern of one of these differentiation genes, a type II collagen (col2a1) gene from the zebrafish Danio rerio. Along th8e embryonic axis, col2a1 is expressed dynamically in three rows that are each a single cell wide: the notochord and the rows of cells immediately dorsal and ventral to it—the floor plate of the central nervous system, and the hypochord. In addition, col2a1 is expressed in the pharyngeal arches, the epithelium of the otic capsule, and in the mesenchyme of the neurocranium. Experiments probed the expression pattern of col2a1 relative to that of known or potential regulators of axis development, including axial, sonic hedgehog, twist, and cyclops. The results showed that the spatial and temporal pattern of col2a1 expression in axial mesoderm follows the expression of twist closer than other genes tested. In cyclops embryos, which lack an intact floor plate, col2a1 expression was usually low, but not missing in cells in the ventral spinal cord. Because col2a1 expression reveals abnormalities in the notochord of cyclopsb16 embryos, and less col2a1‐expressing mesenchyme accumulates rostral to the notochord in cyclops embryos, the effects of the cyclopsb16 mutation are not confined to the central nervous system. ©1995 Wiley‐Liss, Inc.
Novel FGF receptor (Z‐FGFR4) is dynamically expressed in mesoderm and neurectoderm during early zebrafish embryogenesis
Authors: Thisse Bernard , Thisse Christine , Weston James A. 
Published: February 2005

AbstractWe have identified a novel FGF receptor, Z‐FGFR4, in zebrafish embryos. Z‐FGFR4 is closely related to both chicken FREK (Marcelle et al. [1994] Development 120:683–694) and the Pleurodeles cDNA clone Pw‐FGFR4 (also named PFR4). The Z‐FGFR4 cDNA clones contain consensus sequences for two groups of two Ig‐like domains, separated by eight acidic residues referred to as the “acid box”. Z‐FGFR4, therefore, is the first FGFR molecule yet described in vertebrates that contains four Ig domains in its aminoterminal region.Whole‐mount in situ hybridization of staged zebrafish embryos, using probes prepared from a variety of domains of the Z‐FGFR4 cDNA, reveal complex temporal and spatial expression patterns. Expression of Z‐FGFR4 mRNA is first detected in embryos prior to gastrulation and then appears in prechordal plate mesendoderm. At this time, Z‐FGFR mRNA is expressed in the epiblast in two distinct stripes which ultimately contribute to the brain. Eventually Z‐FGFR4 transcripts are observed in forebrain, anterior hindbrain (rhombomeres 1, 3), and caudal hindbrain (rhombomere 7), as well as in the dorsal‐most portion of the rostral spinal cord. Expression in axial mesendoderm appears transiently in notochord and segmental plate mesoderm. Eventually, Z‐FGFR4 mRNA becomes restricted to the posterior somites and is absent in differentiated notochord. These detailed expression studies provide the basis for understanding FGFR function through an analysis, currently in progress, of the developmental consequences of Z‐FGFR4 misexpression. ©1995 Wiley‐Liss, Inc.