bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation potentialities of distinct myogenic cell precursors in avain embryos
Authors: Auda‐Boucher G. , Fontaine‐Pérus J. 
Published: February 2005

AbstractInterspecific grafting experiments between chick and quail embryos were carried out to investigate the differentiation capacities of myoblasts from different development stages. Grafts consisted of 3.5‐day‐old embryonic quail dermomyotomes isolated from the cranial level, 7‐ to 10‐day‐old and 16‐day‐old embryonic quail pectoralis muscles, 15‐day‐old postnatal quail pectoralis muscle, and 3‐ to 10‐day‐old embyonic quail cardiac and gut muscles. Grafts were implanted into 2‐day‐old chick embryos in place of the dorsal halves of somites from the prospective wing level. After implantation of dermomyotome fragments, we observed that quail cells participated in trunk and limb musculature. After implantation of 7‐ to 10‐day‐old embryonic muscle, quail cells were rarely found in the limb but systematically took part in the formation of trunk muscles. All these capacities were totally lost in 16‐day‐old embryonic and 15‐day‐old postnatal muscles. After implantation of nonsomitic derivatives such as embryonic cardiac and gut muscles, implanted cells never participated either in wing or trunk musculature. After dermomyotome, embryonic muscle, and gut implantation, quail cells were capable of invading the dermis and aggregating into feather germs. Our results extend those previously reported and indicate that somitic myogenic derivatives which do not migrate in the normal course of embryogenesis have migratory potentialities and are able to give rise to axial muscles. All these potentialities are lost as myogenesis proceeds in embryos. © 1994 Wiley‐Liss, Inc.
Tumor necrosis factor‐α and embryonic mouse lung morphogenesis
Authors: Jaskoll Tina , Boyer Paul D. , Melnick Michael 
Published: February 2005

AbstractThe ontogeny of the embryonic and fetal lung involves complex interactions between epithelial and mesenchymal primordia which require a specific program of gene regulation and signal transduction. Past studies in our laboratory using congenic mouse strains indicate that one or more genes which map to the H‐2 region of chromosome 17 regulate the rate of lung morphogenesis, defined in this context as differentiative heterochrony among strains. Since hormones and growth factors are the messengers of morphogenesis, it was logical to propose that tumor necrosis factor‐α (TNF‐α), a well‐characterized cytokine whose gene maps to the D‐region of the H‐2 complex, is a putative mediator of lung morphogenesis. We investigated this proposition using immunochemical methods and a serumless, chemically defined in vitro model system. Our results demonstrate that: (1) TNF‐α has a specific spatiotemporal localization, in vivo and in vitro; (2) TNF‐α receptor, in vivo and in vitro, is localized throughout the embryonic lung; (3) TNF‐α supplementation in vitro of embryonic lung primordia has a marked dose‐dependent, stimulatory effect on branching morphogenesis and surfactant‐associated protein (SP‐A) expression; (4) multiple immunoreactive proteins, including 17, 26, and 68 kDa species, are expressed during development in vivo, and a subset of these are expressed in vitro; and (5) both time‐ and glucocorticoid‐dependent changes occur in the in vivo expression pattern of TNF‐α immunoreactive proteins after 4 and 7 days in vitro, including the up‐regulation of a novel 40 kDa protein. Given that glucocorticoids (CORT) regulate TNF‐α expression and TNF‐α's ability to stimulate pulmonary morphodifferentiation and histodifferentiation, we conclude that TNF‐α is an autocrine/paracrine pulmonary cytokine, probably a component of the lung morphogenesis pathway regulated by CORT. © 1994 Wiley‐Liss, Inc.
Expression patterns of the bone morphogenetic protein genes Bmp‐4 and Bmp‐2 in the developing chick face suggest a role in outgrowth of the primordia
Authors: Francis‐West Philippa H. , Tatla Taranjit , Brickell Paul M. 
Published: February 2005

AbstractBone morphogenetic proteins BMP‐4 and BMP‐2 are closely‐related members of the transforming growth factor‐β superfamily that have been implicated in signalling in a number of developmental systems. To determine whether they could be involved in the epithelial‐mesenchymal interactions that control face development, we mapped the distribution of Bmp‐4 and Bmp‐2 gene transcripts in the developing chick facial primordia. At stages when primordia were becoming established, Bmp‐4 transcripts were present in specific regions of epithelium in all facial primordia, but were undetectable in the mesenchyme. Bmp‐4 transcripts appeared subsequently in specific regions of mesenchyme at the distal tips of the primordia. This mesenchymal expression first appeared in the frontonasal mass and then, in turn, in the lateral nasal processes, the maxillary primordia and the mandibular primordia. There was a complex relationship between domains of epithelial and mesenchymal Bmp‐4 expression, and at many sites there was an inverse correlation between epithelial and mesenchymal Bmp‐4 expression. Bmp‐2 transcripts were found in the epithelium and mesenchyme of the maxillary and mandibular primordia at early stages in facial development. Bmp‐2 transcripts appeared in the frontonasal mass and lateral nasal processes at later stages, with epithelial expression preceding mesenchymal expression. In general, mesenchymal Bmp‐2 expression was associated with overlying epithelial Bmp‐2 expression. The domains of Bmp‐4 expression overlapped with those of Bmp‐2, but detailed examination showed that there was no precise correlation between the expression patterns of the two genes. Indeed, in some places the Bmp‐4 and Bmp‐2 expression domains were complementary. The expression of the Bmp‐4 and Bmp‐2 genes in the epithelium and distal mesenchyme of the facial primordia suggests that BMP‐4 and BMP‐2 may be involved in the epithelial‐mesenchymal interactions that control outgrowth of these primordia. © 1994 Wiley‐Liss, Inc.
Differential expression during embryogenesis of three genes clustered in the Ras1 region of Drosophila melanogaster
Authors: Ezer Sini T. , Sahar Dvora , Salzberg Adi , Lev Zeev 
Published: February 2005

AbstractTranscription mapping and nucleotide sequence analysis reveal that the genomic region of the Drosophila Ras1 gene contains a cluster of three closely localized genes. A gene termed Rlb1 is located nearby and upstream of Ras1, and is oriented in the opposite polarity relative to Ras1. In addition, a third gene termed Rlc1, is found at a very close proximity downstream to Rlb1. Ras1, the homologue of the human transforming ras genes, has been shown to be active in the posterior termini of the Drosophila embryo and in the eye imaginal disc in pathways of cell fate determination. We demonstrate that during embryogenesis Ras1 transcripts are restricted mainly to the embryonic central nervous system, suggesting that the gene product also may have a role in these nerve cells. Rlb1 encodes for a novel, lysine‐rich basic protein. It is expressed mainly in the developing midgut and in the somatic mesoderm. Rlc1 also encodes for a novel, basic protein. The expression of Rlc1 during embryogenesis is similar, but not identical, to the expression pattern detected for Ras1. The vertebrate p21Ras proteins are bound to the inner face of the cell membrane. Ras1, the Drosophila homologue of p21, and the Rlb1 protein, are also non‐cytoplasmic, membranous proteins. Rlb1 is found in the cell membrane of larval midgut epithelial cells. In addition, Rlb1 is detected in the nuclei of these cells, and in the nuclei of the midgut imaginal cells. © 1994 Wiley‐Liss, Inc.
Developmental relations between sixth nerve motor neurons and their targets in the chick embryo
Authors: Wahl Christina M. , Noden Drew M. , Baker Robert 
Published: February 2005

AbstractThe developmental relations between abducens (VI) nerves and their targets, the lateral rectus, quadratus, and pyramidalis muscles, have been examined in the chick embryo from early neural tube stages through 10 days of incubation. Sites of myoblast origins were determined by microinjection of replication‐incompetent retroviruses containing the LacZ reporter into paraxial mesoderm corresponding to somitomeres 3‐5. Motor neurons and axons were identified by Bodian staining, immunocytochemistry, and application of DiI and DiO to dissected peripheral nerves. Anlage of the dorsal oblique originate in somitomere 3, close to the ventrolateral margin of the mid‐to‐caudal mesencephalon. Precursors of the lateral rectus arise deep within somitomere 4, beside the future metencephalon (rhombomere “A”). Quadratus and pyramidalis precursors are located between and partially segregated from these other two anlage. VIth nerve axons exit rhombomeres 5 and 6 via multiple median roots, fasciculate, and by stage 17 have elongated rostrally beneath the hindbrain. Immediately caudal to a mesenchymal pre‐muscle condensation located deep to rhombomere 2, the VIth nerve separates into two branches. One branch enters the rostral portion of the condensation, from which quadratus and pyramidalis muscles will segregate. This branch projects exclusively from rhombomere 5 and is the accessory abducens nerve. The other branch enters the caudal, presumptive lateral rectus, region of the condensation. This is the abducens nerve, and it projects from cells located in both rhombomeres 5 and 6. These findings indicate that specific matching of motor nerves with their presumptive targets begins prior to the differentiation and segregation of myogenic populations, and that spatial organization of developing eye muscles is initiated well before they interact with connective tissue precursors derived from the neural crest. © 1994 Wiley‐Liss, Inc.
Mapping the origin of the avian enteric nervous system with a retroviral marker
Authors: Epstein M. L. , Mikawa T. , Brown A. M. C. , McFarlin D. R. 
Published: February 2005

AbstractThe enteric nervous system is largely formed from the vagal neural crest which arises from the neuroaxis between somites 1—7. In order to evaluate the contribution of different regions of the vagal crest to the enteric nervous system, we marked crest cells by injecting somites 1—10 with a replication‐defective spleen necrosis virus vector which contains the marker gene lacZ. After incubation in X‐gal, lacZ‐positive blue cells were found in the wall of the gut in three locations. Most were found at the peripheral edge of the developing circular muscle and within the developing submucosa, sites characteristic of developing ganglia. LacZ‐positive cells in these ganglionic sites were always surrounded by HNK‐1 immunostained cells, confirming their neural crest origin. LacZ‐positive cells were also seen in a third location, the circular muscle layer of the esophagus and crop, and were separated from the HNK‐1 positive ganglionic elements. These cells in the circular muscle are probably muscle cells derived from labeled mesodermal cells of the somite. Injection of somites 3, 4, 5, and 6 resulted in the largest percentage of preparations with lacZ‐positive crest‐derived cells and in the largest number of positive cells in the gut. After injection of these somites, lacZ‐positive crest‐derived cells were found in all regions of the gut from the proventriculus to the rectum. Very few positive crest‐derived cells were found in the esophagus. Injection of somites 1, 2, and 7 resulted in a smaller percentage of preparations with positive crest‐derived cells and in a smaller number of positive crest‐derived cells, which were confined to the fore and midgut. The gizzard was the gut region most frequently containing labeled cells and the rectum was the region least frequently containing such cells. This suggests that the number of crest cells available for colonization of the gut decreases as the distance from the gizzard increases. We conclude that the region of the neuroaxis between somites 3—6 is the major source of crest cells to the gut and that crest cells from different segments of the neuroaxis do not appear to be segregated to different regions of the gut. © 1994 Wiley‐Liss, Inc.
Stage‐ and region‐dependent responses of chick wing‐bud mesenchymal cells to retinoic acid in serum‐free microcultures
Authors: Paulsen Douglas F. , Chen Wei‐Dang , Okello David , Johnson Benita 
Published: February 2005

AbstractRetinoic acid (RA) has been shown to affect skeletal patterning in vivo in both developing and regenerating limbs. Regional differences in RA concentrations alone cannot account for the region‐specific cell behaviors involved in limb‐skeletal morphogenesis. The present study explores a role for regional differences in signal interpretation in RA's effects along the anteroposterior and proximodistal axes of stage 21–22 and 23–24 chick wing‐buds. Mesenchymal cells isolated from specific limb regions were grown in chemically defined medium and exposed to 5 or 50 ng/ml of RA for 4 days in high‐density microtiter cultures. Previous studies showed that RA's effects on chondrogenesis and growth in such cultures differed depending on the position along the limb's proximodistal axis from which the cells were isolated. The present study is the first to show that such differences in RA‐responsiveness also exist along the limb's anteroposterior axis, especially in the distal subridge mesenchyme. The region‐dependent relationships between RA's effects on growth and chondrogenesis suggest that RA affects these two behaviors through different mechanisms. The regional differences in the responsiveness of these cells to exogenous RA are discussed with respect to their correspondence to the in vivo patterns of expression of RA‐binding proteins, RA‐receptors, and other patterning‐related genes. © 1994 Wiley‐Liss, Inc.
Characterization of cDNAs encoding the chick retinoic acid receptor γ2 and preferential distribution of retinoic acid receptor γ transcripts during chick skin development
Authors: Michaille Jean‐Jacques , Blanchet Sandrine , Kanzler Benoit , Garnier Jean‐Marie , Dhouailly Danielle 
Published: February 2005

AbstractRetinoic acid receptors α, β and γ (RARα, β and γ) are ligand‐inductible transcriptional activators which belong to the steroid/thyroid hormone receptor superfamily. At least two major isoforms (1 and 2) of each RAR arise by differential use of two promoters and alternative splicing. In mouse, the three RAR genes are expressed in stage‐ and tissue‐specific patterns during embryonic development. In order to understand the role of the different RARs in chick, RARγ2 cDNAs were isolated from an 8.5‐day (stage 35 of Hamburger and Hamilton) chick embryo skin library. The deduced chick RARγ2 amino acid sequence displays uncommon features such as 21 specific amino acid replacements, 12 of them being clustered in the amino‐terminal region (domains A2 and B), and a truncated acidic carboxy‐terminal region (F domain). However, the pattern of RARγ expression in chick embryo resembles that reported in mouse, particularly in skin where RARγ expression occurs in both the dermal and epidermal layers at the beginning of feather formation, and is subsequently restricted to the differentiating epidermal cells. Northern blot analysis suggests that different RARγ isoforms could be successively required during chick development. © 1994 Wiley‐Liss, Inc.
Quantitative switch in integrin expression accompanies differentiation of F9 cells treated with retinoic acid
Authors: Burdsal Carol A. , Lotz Margaret M. , Miller Jeffrey , McClay David R. 
Published: February 2005

AbstractF9 embryonal carcinoma cells resemble epithelial cells when in monolayer culture. After treatment with retinoic acid these cells differentiate into fibroblastic‐like cells in a sequence that has been modeled as the mammalian equivalent of the differentiation from stem cells of the inner cell mass to parietal endoderm. This study examined the changes in integrin subtypes that accompany retinoic acid‐induced differentiation of F9 cells. Although several integrins were found to be present on the surface of F9 cells and retinoic acid‐induced (RA) cells, the two dominant integrins were α3β1 and α5β1. Differentiation of F9 cells resulted in about 10‐ to 25‐fold increase in the amount of α3β1 integrin protein as measured by immunoprecipitation of cell surface labeled material. There was a corresponding several‐fold reduction of α5β1 protein. The concentration of α3 mRNA was about the same in F9 and RA cells while the concentration of α5 mRNA dropped several‐fold after retinoic acid treatment. Thus α3 regulation appeared to be largely posttranscriptional while the drop in α5 protein may have been a result of transcriptional down‐regulation. Quantitative measurement of adhesion suggested that most of the F9 and RA cell‐substrate adhesion to fibronectin or laminin is mediated by these integrins. They are the dominant integrins present, and antibodies to either these integrins or to the substrate blocked the adhesion.Despite the large switch in integrin subtype protein expression there was little difference between the two cell types in initial cell interactions when adhesive affinities were measured quantitatively. Also there was no difference between the two phenotypes in rate of initial adhesive strengthening. The phenotypic difference was first observed with later events in the attachment and spreading of the RA‐treated cells to the substrate. These results show that retinoic acid treatment alters the amounts of α5 and α3 integrin subunits during the F9 to RA phenotypic switch. The data show that these integrins are important in the cell‐substrate adhesion to fibronectin and laminin. They show, however, that the phenotypic changes observed with differentiation are not associated with the initial preferential adhesions to the substrate, but rather with consequences that alter the cytoskeletal architecture of the cell. © 1994 Wiley‐Liss, Inc.
Protooncogene c‐ski is expressed in both proliferating and postmitotic neuronal populations
Authors: Lyons G. E. , Micales B. K. , Herr M. J. , Horrigan S. K. , Namciu S. , Shardy D. , Stavnezer E. 
Published: February 2005

AbstractThe cellular protooncogene, c‐ski, is expressed in all cells of the developing mouse at low but detectable levels. In situ hybridization and Northern blot analyses reveal that some cells and tissues express this gene at higher levels at certain stages of embryonic and postnatal development. RT‐PCR results indicate that alternative splicing of exon 2, known to occur in chickens (Sutrave and Hughes [1989] Mol. Cell. Biol. 9:4046–4051; Grimes et al. [1993] Oncogene 8:2863–2868) does not occur in adult mouse tissues. In the embryo, neural crest cells express the c‐ski gene during migration at 8.5 to 9.5 days post coitum (p.c.). Neural crest derivatives such as dorsal root ganglia and melanocytes stain positively with an antibody to the ski protein. At 9 days p.c., the entire neural tube has high levels of c‐ski gene expression. By 12–13.5 days only the ependymal layer expresses c‐ski above background levels. At 14–16 days p.c., c‐ski mRNAs are detected at high levels in the cortical layers of the brain and in the olfactory bulb. In 2 week and 6 week postnatal brains, c‐ski gene transcripts are also detected in the hippocampus and in the granule cell layer of the cerebellum. The allantois and placenta exhibit high levels of c‐ski mRNAs. Neonatal lung tissue increases c‐ski gene expression approximately two‐fold compared to prenatal levels. These results suggest that ski plays a role in both the proliferation and differentiation of specific cell populations of the central and peripheral nervous systems and of other tissues. © 1994 Wiley‐Liss, Inc.
Differential expression of myogenic regulatory genes and Msx‐1 during dedifferentiation and redifferentiation of regenerating amphibian limbs
Authors: Simon Hans‐George , Nelson Craig , Goff Debbie , Laufer Ed , Morgan Bruce A. , Tabin Cliff 
Published: February 2005

AbstractAn amputated limb of an adult urodele amphibian is capable of undergoing regeneration. The new structures form from an undifferentiated mass of cells called the regenerative blastema. The cells of the blastema are believed to derive from differentiated tissues of the adult limb. However, the exact source of these cells and the process by which they undergo dedifferentiation are poorly understood. In order to elucidate the molecular and cellular basis for dedifferentiation we isolated a number of genes which are potential regulators of the process. These include Msx‐1, which is believed to support the undifferentiated and proliferative state of cells in the embryonic limb bud; and two members of the myogenic regulatory gene family, MRF‐4 and Myf‐5, which are expressed in differentiated muscle and regulate muscle‐specific gene activity. As anticipated, we find that Msx‐1 is strongly up‐regulated during the initiation of regeneration. It remains expressed throughout regeneration but is not found in the fully regenerated limb. The myogenic gene MRF‐4 has the reverse expression pattern. It is expressed in adult limb muscle, is rapidly shut off in early regenerative blastemas, and is only reexpressed at the completion of regeneration. These kinetics are paralleled by those of a musclespecific Myosin gene. In contrast Myf‐5, a second member of the myogenic gene family, continues to be expressed throughout the regenerative process. Thus, MRF‐4 and Myf‐5 are likely to play distinct roles during regeneration. MRF‐4 may directly regulate muscle phenotype and as such its repression may be a key event in dedifferentiation. Myf‐5 may play a role in maintaining a distinct myogenic lineage during regeneration. © 1995 Wiley‐Liss, Inc.
Analysis of transcriptional isoforms of collagen types IX, II, and I in the developing avian cornea by competitive polymerase chain reaction
Authors: Fitch John M. , Gordon Marion K. , Gibney Eileen P. , Linsenmayer Thomas F. 
Published: February 2005

AbstractThe genes for the α1(IX), α1(IX), α1(II), and α2(I) collagen chains can give rise to different isoforms of mRNA, generated by alternative promoter usage [for α(IX) and α2(I)] or alternative splicing [for α1(II)]. In this study, we employed competitive reverse transcriptase PCR to quantitate the amounts of transcriptional isoforms for these genes in the embryonic avian cornea from its inception (about 3 1/2 days of development) to 11 days. In order to compare values at different time points, the results were normalized to those obtained for the “housekeeping” enzyme, glycerol‐3‐phosphate dehydrogenase (G3PDH). These values were compared to those obtained from other tissues (anterior optic cup and cartilage) that synthesize different combinations of the collagen isoforms. We found that, in the cornea, transcripts from the upstream promotor of α1(IX) collagen (termed “long IX”) were predominant at stage 18–20 (about 3 1/2 days), but then fell rapidly, and remained at a low level. By 5 days (just before stromal swelling) the major mRNA isoform of α1(IX) was from the downstream promotor (termed “short IX”). The relative amount of transcript for the short form of type IX collagen rose to a peak at about 6 days of development, and then declined. Throughout this period, the predominant transcriptional isoform of the collagen type II gene was IIA (i.e., containing the alternatively spliced exon 2). This indicates that the molecules of type II collagen that are assembled into heterotypic fibrils with type I collagen possess, at least transiently, an amino‐terminal globular domain similar to that found in collagen types I, III, and V. For type I, the “bone/tendon” mRNA isoform of the α2(I) collagen gene was predominant; transcripts from the downstream promotor were at basal levels. In other tissues expressing collagen types IX and II, long IX was expressed predominantly with the IIA form in the anterior optic cup at stage 22/23; in 14 1/2 day cartilage, long IX was expressed predominantly along with the IIB form of α1(II). The downstream transcript of the α2(I) gene (Icart) was found at high levels only in cartilage. © 1995 Wiley‐Liss, Inc.