bluuebunny/crossref_metadata_2025_split huggingface dataset:
Failure to make normal α ryanodine receptor is an early event associated with the Crooked Neck Dwarf (cn) mutation in chicken
Authors: Airey Judith A. , Baring Martha D. , Beck Claudia F. , Chelliah Yogarany , Deerinck Thomas J. , Ellisman Mark H. , Houenou Lucien J. , McKemy David D. , Sutko John L. , Talvenheimo Jane 
Published: February 2005

AbstractWe have investigated the molecular basis of the Crooked Neck Dwarf (cn) mutation in embryonic chickens. Using biochemical and pharmacological techniques we are unable to detect normal α ryanodine receptor (RyR) protein in intact cn/cn skeletal muscle. Extremely low levels of αRyR immunoreactivity can be observed in mutant muscles, but the distribution of this staining differs from that in normal muscle and colocalizes with the rough endoplasmic reticulum immunoglobulin binding protein, BiP. This suggests the existence of an abnormal αRyR protein in mutant muscle. In day E12 cn/cn muscle the levels of RyR mRNA are reduced by ∼80%, while the levels of other muscle proteins, including the α1 subunit of the dihydropyridine receptor, the SRCa2+‐ATPase, calsequestrin, and glyceraldehyde‐3‐phosphate dehydrogenase, and their associated mRNAs are essentially normal in cn/cn muscle. There is also a failure to express αRyR in cn/cn cerebellar Purkinje neurons. Expression of the βRyR, a second RyR isoform, is not initiated in normal skeletal muscle until day E18. In cn/cn skeletal muscle significant muscle degeneration has occurred by this time and the βRyR is found at low levels in only a subset of fibers suggesting the reduced levels of this isoform are a secondary consequence of the mutation. The cardiac RyR isoform is found in cn/cn cardiac muscle, which contracts in a vigorous manner. In summary, a failure to make normal αRyR receptor appears to be an event closely associated with the cn mutation and one which may be largely responsible for development of the cn/cn phenotype in embryonic skeletal muscle. © 1993 Wiley‐Liss, Inc.
Differentiation of mouse embryonic stem cells in vitro: III. Morphological evaluation of tissues developed after implantation of differentiated mouse embryoid bodies
Authors: Chen Una , Kosco Marie 
Published: February 2005

AbstractMouse embryonic stem cells (ES) were allowed to differentiate in a liquid culture system. After 2–3 weeks, complex cystic embryoid bodies developed. These bodies were composed of several structures identified as cardiac muscle and yolk sac blood islands as well as cupshape compartments containing a mixed population of hematopoietic stem cells. When these cystic embryoid bodies were implanted into adult mice, either subcutaneously or under the kidney capsule, they developed into various tissues. These included bone, blood vessels, cardiac muscle, nerves, and skin with hair follicles. In addition, highly differentiated, complicated tissues resembling intestinal epithelium with mucus glands or salivary glandular tissue were derived. The ES tissues from these in vitro developed embryoid bodies developed quickly within 2 to 3 weeks of implantation. This is in contrast to a minimal of 6 weeks for teratocarcinomas derived from embryonic carcinoma cells and/or the direct implantation of undifferentiated embryonic stem cells. Moreover, we found that there are different types of tissue developed upon different sites of implantation. The data suggest a local environment and/or growth factors are influential for ES tissue development. This system provides a possible means to purify and identify stem cells that give rise to specific tissues, and to study the factors regulating the commitment of these stem cells. © 1993 Wiley‐Liss, Inc.
The Etl‐1 gene encodes a nuclear protein differentially expressed during early mouse development
Authors: Schoor Michael , Schuster‐Gossler Karin , Gossler Achim 
Published: February 2005

AbstractRecently, we isolated a novel mouse gene, Etl‐1 (Enhancer‐trap‐locus‐1), whose deduced amino acid sequence shows in its C‐terminal portion striking homology to the brahma protein (BRM), a transcriptional regulator of homeotic genes in Drosophila, and to SNF2/SWI2, a transcriptional regulator of various genes in Saccharomyces cerevisiae. Here we report the generation of antibodies against the Etl‐1 gene product (ETL‐1) and describe the subcellular localization as well as the expression and distribution of the ETL‐1 protein during mouse pre‐ and early post‐implantation development. ETL‐1 is a nuclear protein and is expressed in a biphasic manner during early embryogenesis. Moderate levels of ETL‐1 were detected in unfertilized and fertilized eggs but in the latter the protein was not concentrated in the pronuclei and seemed evenly distributed throughout the cytoplasm. In two‐cell embryos nuclear ETL‐1 protein accumulated transiently and levels decreased during subsequent cleavage development. After the morula stage, ETL‐1 levels increased again; in blastocysts high levels of ETL‐1 were present in inner cell mass cells whereas trophectoderm cells contained little or no ETL‐1. During subsequent development essentially all cell types except parietal endoderm and trophoblast cells contained high levels of ETL‐1. Our results imply that nuclear ETL‐1 is dispensable for the progression to the two cell stage, and suggest that during cleavage ETL‐1 might be needed at the onset of embryonic transcription. In blastocysts ETL‐1 function might be specifically required in cells of the inner cell mass and later in most cells of the embryo proper and extraembryonic ectoderm lineage. © 1993 Wiley‐Liss, Inc.
Induction of neuronal differentiation by planar signals in Xenopus embryos
Authors: Sater Amy K. , Steinhardt Richard A. , Keller Ray 
Published: February 2005

AbstractThe induction of the central nervous system in amphibian embryos is mediated both by early planar signals produced by mesoderm at the dorsal lip and later vertical signals emanating from the dorsal mesoderm after involution. We have examined the role and spatial extent of planar signals in the induction of neuronal differentiation. Planar explants that included only the deep layer of the dorsal marginal zone, comprising both the dorsal mesoderm and the contiguous dorsal ectoderm, were isolated at the beginning of gastrulation. After removal of the epithelial layer, explants were maintained in modified Danilchik's medium until mid‐neurula stages, when they were transferred to modified Danilchik's medium + 0.1% bovine serum albumin and cultured on laminin. Neurite outgrowth occurred in 90% of these planar explants. In contrast, little or no neuronal differentiation occurred in either ventral planar explants or explants of ectoderm alone. Video analysis of cell movements shows that large‐scale cell mixing does not occur between mesoderm cells and ectoderm cells in planar explants. Retrograde labelling of neuronal cell bodies indicates that cells throughout the ectoderm undergo neuronal differentiation; neurons also differentiate in cultures of distal ectoderm isolated at early neurula stages from planar explants prepared at the beginning of gastrulation. These observations indicate that planar signals act over an extended range to induce neuronal differentiation. The inductive capacity of vertical signals was examined by recombining animal caps from ultra‐violet (UV) irradiated embryos with involuted mesoderm from normal midgastrula embryos. Differentiation of either neurons or anterior neural structures occurred in 73% of vertical recombinates. Our results demonstrate that planar signals from the dorsal lip of the blastopore are capable of inducing neuronal differentiation over a considerable distance in the absence of epithelial confinement, convergence and extension, and mixing between the mesoderm and ectoderm. © 1993 Wiley‐Liss, Inc.
Developmentally regulated and spatially restricted antigens of radial glial cells
Authors: Herman Jean‐Paul , Victor John C. , Sanes Joshua R. 
Published: February 2005

AbstractRadial glial cells, present in many parts of the embryonic vertebrate central nervous system (CNS), have been implicated in the guidance of neuroblasts from the ventricular zone to their laminar destinations. Moreover, radial glial cells may be progenitors of some CNS neurons and glia. To gain new insight into the structure and development of these cells, we have generated and characterized a panel of monoclonal antibodies that recognize radial glial cells of the chick optic tectum. Mice were immunized with hommogenates of embryonic day (E) 10 tectum, and antibodies were analyzed by immunofluorescence and immunoblotting. We describe here three pairs of antibodies. (1) H5 and a previously generated antibody, R5 (Dräger et al., J. Neurosci. 4:2025, 1984), stain the whole extent of the radial glial cell from E7 to E20. In cultures prepared from E10 tecta, both stain a filamentous meshwork in glial cells but not in neurons. On immunoblots, both recognize a protein of ∼52 kD that is closely related (or identical) to vimentin. (2) H28 and H29 stain radial glia between E7 and E14, but not later. Moreover, H28 and H29 staining is markedly more intense in the ventricular and intermediate zones than in the laminae of the tectal plate. Both of these antibodies recognize an intracellular epitope in cultured glial cells and a protein of ∼35 kD on immunoblots. (3) H2 and H27 recognize antigens concentrated in the most superficial processes and endfeet of radial glia in late (E16–E20) embryos. They stain distinct structures in cultured glia, suggesting that they recognize distinct antigens. H27 recognizes a protein of ∼29 kD on immunoblots. Thus antibodies H5 and R5 are good markers of radial glial cells at all stages, whereas the others define antigens that are developmentally regulated and localized to discrete domains. Together, these antibodies can be used to study temporal and spatial specializations of radial glia. © 1993 Wiley‐Liss, Inc.
Selective expression of the chicken platelet‐derived growth factor α (PDGFα) receptor during limb bud development
Authors: Potts Jay D. , Carrington Jill L. 
Published: February 2005

AbstractPlatelet‐derived growth factor (PDGF) affects proliferation and differentiation of chicken limb bud mesoderm in vitro. However, no PDGF receptor has been characterized in the chicken wing bud in vivo. In this study, we used reverse transcription PCR (rtPCR), Northern blot analysis, and Western blot analysis to identify a molecule, in the developing wing bud, which represents the chicken homolog of the PDGFα receptor. The chicken PDGFα receptor mRNA was present in both mesoderm and ectoderm and all stages of the developing limb bud examined. Cultured limb bud mesoderm also expressed the PDGFα receptor transcript. In addition, the PDGFα receptor protein was present in whole limb buds and cultured limb bud mesoderm. Expression of the PDGFα receptor in cultured mesoderm was independent of the presence of ectoderm cells. The relative sizes of both the mRNA and protein for the PDGFα receptor in the chicken limb bud were similar to mammalian counterparts. Using similar approaches, neither the mRNA nor protein representing the chicken homolog of the PDGFβ receptor was detected. These data demonstrate for the first time that a PDGFα receptor is present in the embryonic chicken limb bud and may help regulate growth and differentiation of the embryonic limb. © 1993 Wiley‐Liss, Inc.
Fibroblast behavior in the embryonic chick heart
Authors: Choy Michael , Oltjen Sharon , Ratcliff Dorothy , Armstrong Margaret , Armstrong Peter 
Published: February 2005

AbstractIntracardiac fibroblasts (mesenchymal cells) of Hamburger and Hamilton stage 36 chick heart reside in the epicardium and atrioventricular valves. The characteristics of the epicardial fibroblasts include segregation from the myocytes of the heart wall myocardium, voluminous extracellular matrix production, and some cell proliferation activity. The atrioventricular fibroblasts intermingle with myocytes at the mutual border between these tissues, produce smaller amounts of extracellular matrix, and show very active cell proliferation. Is the behavior of each population of fibroblasts predetermined or is each responding in a reversible fashion to local environment? A cell aggregate culture system, which permits 3‐dimensional cell‐cell and cell‐matrix interactions, is used to study the behaviour of each isolated population of fibroblasts in vitro. In the presence of serum‐free medium, each population produces very little extracelluar matrix, has relatively low mitotic activity, and does not segregate from myocytes when the aggregate is composed of randomly intermixed myocytes and fibroblasts. In the presence of chicken serum, each population increases matrix production, increases cell proliferation, and sorts from myocytes. Thus, we suggest that the two populations of fibroblasts in the developing heart are responding to local environments and the differences observed in vivo are not the consequence of irreversible states of cellular differentiation. © 1993 Wiley‐Liss, Inc.
Developmental patterns of two α1(IX) collagen mRNA isoforms in mouse
Authors: Liu Chia‐Yang , Olsen Bjorn R. , Kao Winston W.‐Y. 
Published: February 2005

AbstractNorthern blot hybridization, reverse‐transcription polymerase chain reaction (RT‐PCR), and RNase protection assays were used to examine the expression of twoα1(IX) collagen mRNA species (long and short form) in developing mouse tissues. Furthermore, in situ hybridization was used to identify cells expressing the Col9a1 gene during eye development. The results indicate that during embryonic development eye and heart preferentially express the short form; lung and cartilage express the long form; whereas liver expresses a very low level of long formα1(IX) mRNA which can only be detected by RT‐PCR. In situ hybridization demonstrated that at 10.5 day postcoitum (d.p.c.), theα1(IX) collagen mRNAs were first expressed in optic cup (neural ectoderm) but not in lens vesicle (surface ectoderm). By 13.5 d.p.c., the cells that express theα1(IX) mRNA progressively were concentrated to ward the anterior part of the neural retina. By 16.5–18.5 d.p.c., the hybridization signals were found exclusively in the inner non‐pigmented layer of the presumptive ciliary epithelium. As ciliary epithelial cells become well differentiated 3 weeks after birth, cells expressing the Col9a1 gene were limited to the junction between mature ciliary folds and the neural retina. No hybridization signal could be detected in ocular tissues of mouse older than 6 weeks. It is of interest to note that a hybridization signal was not detected in cornea at the various developmental stages examined, suggesting that mouse cornea does not significantly expressα1(IX) mRNA during embyronic development. This differs from that of chick cornea development. In summary, the expression of the Col9a1 gene shows a temporospatial pattern throughout mouse eye development. It is suggested that the short form collagen IX may play an important role in eye development. © 1993 Wiley‐Liss, Inc.
Tissue interactions with underlying dura mater inhibit osseous obliteration of developing cranial sutures
Authors: Opperman Lynne A. , Sweeney Thomas M. , Redmon Julie , Persing John A. , Ogle Roy C. 
Published: February 2005

AbstractCranial sutures play a critical role in calvarial morphogenesis, serving as growth centers during skull development. Both biomechanical tensile forces originating in the cranial base and biochemical factors present in dura mater have been postulated as determinants of suture morphogenesis and patency. A rat transplant model free of the putative biomechanical influence of the dura and cranial base was used to investigate the role of the dura mater in both the initial morphogenesis and maintenance of sutures during skull growth. Day 19 fetal presumptive (F19) and day 1 neonatal differentiated (N1) coronal sutures, including associated frontal and parietal bones, were transplanted with or without underlying dura mater to the center of adult parietal bones. After 1, 2, and 3 weeks, transplanted tissues were examined histologically and histomorphometrically to determine whether sutures formed and whether they were obliterated by ossification in the absence of dura mater. Both F19 and N1 sutures remained patent for 2 weeks either in the presence or the absence of transplant dura mater. However, at 3 weeks, in the absence of transplant dura mater, sutures were obliterated by bone, while in the presence of dura mater sutures resisted ossification, demonstrating an essential requirement for interactions with the transplant dura mater in maintaining functional sutures. Both F19 and N1 transplants showed comparable bone growth (cross‐sectional surface area), regardless of the presence of transplant dura mater. These experiments suggest that tissue interactions of a biochemical nature, rather than biomechanical forces generated through the cranial base, are required to maintain the suture as a non‐ossified growth center. Furthermore, while the presence of dura mater was essential for maintenance of suture patency, fetal dura mater was not required for initial suture formation. © 1993 Wiley‐Liss, Inc.
Prevention of spinal neural tube defects in the curly tail mouse mutant by a specific effect of retinoic acid
Authors: Chen Wei‐Hwa , Morriss‐Kay Gillian M. , Copp Andrew J. 
Published: February 2005

AbstractCurly tail mouse mutant embryos (ct/ct) develop spinal neural tube defects (NTD) in 54% of cases, comprising isolated tail flexion defects and spina bifida with tail flexion defects. Both types of spinal NTD result from delayed closure of the posterior neuropore (PNP). Previous studies (Seller et al. [1979] Proc. R. Soc. Lond. Biol. 206:95–107; Seller and Perkins [1982] Prenat. Diagn. 2:297–300) described a paradoxial effect of retinoic acid (RA) on the phenotypic expression of the ct mutation: Treatment with low doses of RA on day 8 of gestation increased the incidence of total NTD, whereas low doses of RA administered on day 9 resulted in reduced incidence of total NTD. In order to investigate further the reported preventive effect of RA, we have carried out detailed analyses of the effects of maternal treatment with 5 mg/kg RA on the incidence of NTD at different developmental stages, and on the development and growth of ct/ct embryos. We found that 5 mg/kg RA reduces the incidence of spinal NTD in a stage‐specific manner, without increasing the incidence of cranial NTD. The effect of RA is specific: There were no other alterations in morphogenesis, growth, development, resorption rate, or litter size. RA was more effective in the prevention of isolated tail flexion defects than of spina bifida. Prevention of isolated tail flexion defects was maximal (50% reduction) when RA was administered between 10 days 4 hours and 10 days 8 hours post coitum (p.c.) inclusive (24 to 34 somite stage). In contrast, maximal prevention of spina bifida (36%) resulted from RA administration at 10 days 8 hours p.c.; decreased PNP size in treated embryos, compared with control embryos, was evident by 6 hours after the treatment at the 27 to 31 somite stage. The preventive effect of RA on spina bifida was related to maternal phenotype: By comparison with phenotypically straighttailed mothers, curly‐tailed mothers had a greater incidence of spina bifida among their offspring, and this incidence was unresponsive to RA. This result suggests that additional factors, such as modifier genes, modulating phenotypic expression of the ct gene, may be present in the ct mutant stock. Here we show that the RA prevention of spinal NTD is a specific effect. Hence it is plausible that this prevention of spinal NTD by RA is mediated via nuclear retinoic acid receptors. © 1994 Wiley‐Liss, Inc.
Deficient outgrowth of the ureteric bud underlies the renal agenesis phenotype in mice manifesting the limb deformity (ld) mutation
Authors: Maas Richard , Elfering Sandra , Glaser Tom , Jepeal Lisa 
Published: February 2005

AbstractMice which are homozygous for the limb deformity (ld) mutation also manifest an incompletely penetrant unilateral or bilateral renal agenesis phenotype. Intercross experiments suggest that the differences in penetrance of the renal agenesis phenotype between homozygous mice with different ld alleles are due to intrinsic differences in the strength of the mutant alleles or to one or more closely linked modifying loci, and not to generalized differences in genetic background. Analysis of ld/ld embryos between embryonic days 11–13 reveals delayed outgrowth or complete absence of the ureteric bud, the inducer of metanephric mesenchyme. Since explants of ld/ld metanephric mesenchyme differentiate in culture when apposed to embryonic spinal cord, we conclude that deficient ureteric bud outgrowth is the morphologic basis for renal agenesis in ld/ld mice. However, since ld transcripts can be detected in both metanephric mesenchyme and ureteric bud, the molecular basis for the deficiency in ureteric bud outgrowth could reside in either component. © 1994 Wiley‐Liss, Inc.
Developmental expression of human cartilage matrix protein
Authors: Mundlos S. , Zabel B. 
Published: February 2005

AbstractCartilage matrix protein (CMP) is a non‐collagenous component of cartilage with a yet unknown function. In this study we used in situ hybridization to investigate the temporal and sptial distribution of CMP transcripts during human embryonic and early fetal development, and compared it to the pattern of expression observed for collagen types I, II, X, and decorin. The distribution of CMP and collagen type II transcripts followed a similar pattern in the embryonic bone anlage, the fetal growth plate, and the developing vertebral column. Expression was highest in the upper hypertrophic and lower proliferative zone, whereas calcified cartilage was negative throughout the different stages of bone development. Chondrocytes of calcified cartilage, however, were not quiescent but expressed collagen type X. The onset of collagen type X expression was linked to hypertrophy and occurred before calcification became apparent. In contrast, deorin and collagen type I were highly expressed in bone and perichondrium but not in growth plate cartilage. During the development of the synovial joints a different pattern of expression emerged. After formation of the joint cavity, there was a halt in expression of CMP but not of collagen type II in chondrocytes close to the articular surface. A band of CMP negative chondrocytes covering the joint surface was observed in all joints investigated. Decorin mRNA was demonstrated in the reserve zone adjacent to the joints, but not in articular cartilage. Extraskeletal expression of CMP was observed in the embryonic retina. The results demonstrate the differential expression of CMP during human skeletal development and chondrocyte differentiation. The distribution of CMP transcripts is unique and distinct from other known matrix genes. © 1994 Wiley‐Liss, Inc.