bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ectodermal inhibition of cartilage differentiation in micromass culture of chick limb bud mesenchyme in relation to gene expression and cell shape
Authors: Gregg B. C. , Rowe A. , Brickell P. M. , Wolpert L. 
Published: April 2021

ABSTRACT
Ectoderm inhibits the formation of cartilage by chick wing bud mesenchyme in micromass culture. This suggests that the pattern of cartilage formation in the limb bud may result from a restriction of cartilage cell differentiation to the limb bud core as cells leave the progress zone. We have used in situ hybridization to investigate whether ectodermal inhibition in micromass culture occurs at the level of gene transcription. We found that ectoderm completely inhibited the accumulation of cartilage-specific type II collagen transcripts in the mesenchyme cells, whilst the level of type I collagen transcripts was unaffected. Morphometric analysis of electron micrographs revealed that inhibition of chondrogenesis in micromass culture was not preceded by cell flattening. In fact, a rounded cell shape was found not to be a prerequisite for cartilage cell differentiation in micromass.
Tissue specific O-linked glycosylation of the neural cell adhesion molecule (N-CAM)
Authors: Walsh Frank S. , Parekh Raj B. , Moore Stephen E. , Dickson George , Barton C. Howard , Gower Hilary J. , Dwek Raymond A. , Rademacher Thomas W. 
Published: April 2021

ABSTRACT
We have shown previously that the predominant N-CAM isoform in skeletal muscle myotubes contains as a result of alternative splicing a novel domain (MSD1) in its extracellular region. Here we show that this region represents a site for O-linked carbohydrate attachment. The lipid tailed N-CAM in myotubes was found to bind peanut lectin while the transmembrane isoform from myoblasts lacking MSD1 did not. In addition, N-CAM from a variety of neural sources failed to bind the lectin. Analysis of 3T3 fibroblasts transfected with various N-CAM cDNAs, showed that peanut lectin binding was correlated specifically with the expression of the MSD1 region. The oligosaccharides isolated from a purified preparation of myotube N-CAM were shown to contain an O-linked oligosaccharide whose core structure was a sialylated version of Galβ1→3GalNac which is the structure recognized specifically by peanut lectin. These data provide the first evidence for the expression of O-linked carbohydrate on any N-CAM isoform and more specifically target this oligosaccharide to the MSD1 region of myotube N-CAM.
Expression of laminin and of a laminin-related antigen during early development of Drosophila melanogaster
Authors: Garzino Véronique , Berenger Hélène , Pradel Jacques 
Published: April 2021

Abstract
This paper reports the characterization of two immunologically related proteins that may be involved in cell adhesion during Drosophila development. These proteins, laminin chain A and a 240K component, share the epitope recognized by monoclonal antibody RD3 (Mab RD3). The two antigens show different developmental expression profiles. Laminin is detected only from 6 to 8 h of development onwards; its concentration increases during embryogenesis to reach steady-state value in larvae, pupae and adult flies. By contrast, the 240K antigen, not found in oocytes, is present before blastoderm stages; its concentration increases during gastrulation, decreases at the end of organogenesis and the antigen is no longer detected in third instar larvae. Light and electron microscope immunolocalization in imaginal discs indicates that laminin is distributed apically in the lumen and basally in the basal membrane that surrounds the nonevaginated disc. During morphogenesis laminin is detected at the basal side of the evaginating part of the disc epithelium. Immunolocalization on paraffin sections of early embryos suggests that the 240K antigen is related to (1) cell formation and polarization in association with cytoskeleton components, (2) establishment of cell—extracellular substratum interactions during the blastoderm cell sheet organization and (3) basement membrane deposition during embryonic germ cell layer segregation. This 240K protein is poorly or not glycosylated, is resistant to chondroitinase ABC and collagenase and appears therefore as a new extracellular component that might be specifically involved in early processes of morphogenesis.
Induction of functional cytodifferentiation in the epithelium of tissue recombinants : II. Instructive induction of Wolffian duct epithelia by neonatal seminal vesicle mesenchyme*
Authors: Higgins Stephen J. , Young Peter , Cunha Gerald R. 
Published: April 2021

ABSTRACT
When grown as renal grafts in adult male hosts, the upper (cranial), middle and lower (caudal) portions of fetal mouse and rat Wolffian ducts developed into epididymis, epididymis plus ductus deferens, and seminal vesicle, respectively. In heterotypic tissue recombinants, the epithelia from upper and middle Wolffian ducts were instructively induced to undergo seminal vesicle morphogenesis by neonatal seminal vesicle mesenchyme. Functional cytodifferentiation was examined in these recombinants using antibodies against major androgen-dependent, seminal vesicle-specific secretory proteins. The instructively induced Wolffian duct epithelia synthesized normal amounts of all of the secretory proteins characteristic of mature seminal vesicles, as judged by immunocytochemistry on tissue sections and gel electrophoresis plus immunoblotting of secretions extracted from the recombinants. In heterospecific recombinants composed of rat and mouse tissues, the seminal vesicle proteins induced were specific for the species that had provided the epithelium. This showed that the seminal vesicle epithelium in the recombinants was derived from instructively induced Wolffian duct epithelium and not from epithelial contamination of the mesenchymal inductor. Upper Wolffian duct epithelium, instructively induced to undergo seminal vesicle morphogenesis, did not express epididymis-specific secretory proteins, showing that its normal development had been simultaneously repressed.
Cytoplasmic regulation of translation during llyanassa embryogenesis
Authors: Collier J. R. 
Published: April 2021

ABSTRACT
Two-dimensional electrophoresis of labeled proteins and hybridization of mRNAs with specific gene probes was used to demonstrate changes in protein synthesis, and the cytoplasmic control of actin maternal mRNAs during the early development of llyanassa.
The isolated polar lobe was used as a nucleus-free egg fragment to study the regulation of translation. It was shown that actin mRNAs are present in the unfertilized egg and are therefore maternal in origin, are inactive during early cleavage, and are translated in normal, lobeless, actinomycin D-treated blastulae and in isolated polar lobes that have been aged for 24 h. Thus, the activation of actin mRNAs is controlled by cytoplasmic factors that function independently of cleavage and nuclear activity. I suggest that the running of a cytoplasmic clock determines when maternal mRNAs are activated, and that this clock is made and set running during oogenesis.
Changes in protein synthesis that occurred during early cleavage were shown to also involve the diminution of some early cleavage proteins, and it was suggested that this diminution is controlled by cytoplasmic factors localized in the blastomeres of the lobeless egg but absent from the polar lobe.
Expression of microinjected hsp 70/CAT and hsp 30/CAT chimeric genes in developing Xenopus laevis embryos
Authors: Krone Patrick H. , Heikkila John J. 
Published: April 2021

ABSTRACT
The expression of microinjected chimeric genes containing Drosophila hsp 70 and Xenopus hsp 70 and hsp 30 promoters linked to the reporter gene coding for bacterial chloramphenicol acetyltransferase (CAT) was examined during early development of Xenopus laevis. Heat-inducible expression of fusion genes containing either the Drosophila hsp 70 promoter (1100 bp) or the Xenopus hsp 70 promoter (750 bp) was first detectable after the midblastula stage of development. This coincides with the embryonic stage at which the endogenous hsp 70 gene is first heat-inducible. A Xenopus hsp 30/CAT fusion gene containing 350 bp of promoter sequences was also heat-inducible after the midblastula stage unlike the endogenous hsp 30 genes which were not heat-inducible until the early tailbud stage (stage 23– 24). Sequences that are present within either the coding or 3’ region of the hsp 30 clone do not cause the microinjected hsp 30 gene to be developmentally regulated in a normal manner. Additionally, microinjected hsp 30 gene sequences have no effect on the developmental regulation of endogenous hsp 30 genes which continue to be activated at the tailbud stage of development. Our data suggest, that an inhibitory system, which may control the expression of the endogenous hsp 30 gene during development, does not regulate the expression of the injected hsp 30 gene.
Cyclic AMP regulation of P0 glycoprotein and myelin basic protein gene expression in semi-differentiated peripheral neurinoma cell line D6P2T
Authors: Gandelman Kuan-Yun , Pfeiffer S. E. , Carson John H. 
Published: April 2021

ABSTRACT
We have analyzed the effects of cAMP-elevating drugs (dibutyryl cAMP, forskolin, and isobutyl methylxan-thine) on growth properties and myelin-specific gene expression in the peripheral neurinoma cell line D6P2T. The steady-state levels of RNA and Polypeptide for the two major PNS myelin proteins, P0 glycoprotein (P0) and myelin basic protein (MBP), were measured by Northern blotting and immunoblotting, respectively. The levels of the two RNAs in individual cells were examined by in situ hybridization. The transcriptional activities of the P0 and MBP genes were analyzed by nuclear run-off experiments. Treatment with cAMP-elevating agents caused cell aggregation and dose-dependent increase in growth control. Expression of P0 RNA was constitutive in untreated cells and was repressed at high doses. Expression of MBP RNA was induced at low doses and repressed at higher doses. For both MBP and P0 the effects on gene expression were first detected after a lag of approximately 6h, were manifested in all cells and were mediated, at least in part, at the transcriptional level. The level of P0 Polypeptide was proportional to the level of P0 RNA, but MBP Polypeptide was not detectable even under conditions where MBP RNA was induced. The results with this clonal model suggest that cAMP plays a pivotal role in regulation of growth and gene expression during Schwann cell differentiation.
Analysis of specific mRNA destabilization during Dictyostelium developments
Authors: Mangiarotti G. , Bulfone S. , Giorda R. , Morandini P. , Ceccarelli A. , Hames B. D. 
Published: April 2021

ABSTRACT
A number of specific mRNAs are destabilized upon disaggregation of developing Dictyostelium discoideum cells. Analysis of a family of cloned genes indicates that only prespore-enriched mRNAs are affected; constitutive mRNAs that are expressed throughout development and mRNAs that accumulate preferentially in prestalk cells are stable under these conditions. The decay of sensitive prespore mRNAs can be halted by allowing the cells to reaggregate, indicating that destabilization occurs by the progressive selection of individual molecules rather than on all members of an mRNA subpopulation at the time of disaggregation. Individual molecules of the sensitive mRNA species remain engaged in protein synthesis in the disaggregated cells until selected. Destabilization of sensitive mRNAs is induced by cell dissociation even in the presence of concentrations of nogalamycin that inhibit RNA synthesis. The reported prevention of disaggregation-induced mRNA decay by actinomycin D and daunomycin is therefore probably a secondary effect unrelated to the inhibition of transcription.
Amounts and modulation of actin mRNAs in mouse oocytes and embryos
Authors: Bachvarova Rosemary , Cohen Emily M. , Leon Victor De , Tokunaga Katsuo , Sakiyama Shigeru , Paynton Barbara V. 
Published: April 2021

ABSTRACT
In order to measure the content of β- and γ-actin mRNA in mouse oocytes and ovulated eggs, Northern and slot blots were hybridized to complementary RNA probes transcribed from mouse isotype-specific cDNA sequences. The blots included samples of isotype-specific sense strand RNA standards prepared from the same cDNA sequences. Total actin mRNA content was estimated to be 40 fg per preovulatory full-grown oocyte or egg, consisting of one-third β-actin mRNA and two-thirds γ-actin mRNA. Ninety per cent of the actin mRNA is on polysomes in full-grown oocytes. The per cent of actin mRNA in polysomal mRNA is similar to the per cent of actin in newly synthesized proteins.
Measurements on other developmental stages showed that, in mid-growth-phase oocytes, each actin mRNA reaches a level twofold higher than in full-grown oocytes. Thereafter, all modulations of the two isotypic mRNAs occur in parallel; that is, they are maintained at constant levels during the late growth phase (oocytes from females 8−14 days old); gradually degraded in oocytes that have completed their rapid growth phase (oocytes from females 15−18 days old), in maturing oocytes, and in 1- and 2-cell embryos; and deadenylated after about 7 h of progression into meiotic maturation.
Retinoic acid application to chick wing buds leads to a dose-dependent reorganization of the apical ectodermal ridge that is mediated by the mesenchyme
Authors: Tickle C. , Crawley A. , Farrar J. 
Published: April 2021

ABSTRACT
Local application of retinoic acid to wing buds of chick embryos leads to dose- and position-dependent changes in the pattern of cellular differentiation. Early effects of retinoid treatment on the apical ectodermal ridge coor- dinate pattern changes and morphogenesis. The length of the apical ridge increases when additional digits will form but decreases when digits are lost. These changes in length can be understood in terms of a threshold response to the local retinoid concentration that results in either disappearance or maintenance of the ridge (Lee & Tickle, J. Embryol. exp. Morph. 90, 139-169 (1985)). Here, we have analysed the mechanisms involved in ridge disappearance by locally applying retinoic acid to the apex of stage 20 chick wing buds. With this treat- ment regime, low doses give duplicated digit patterns and higher doses truncations. The height of the apical ridge is progressively reduced with increasing doses of retinoid and the time course of ridge flattening indicates that the height of the ridge is correlated with bud outgrowth. With high doses of retinoic acid, the typical ridge, a pseudostratified epithelium in which the colum- nar cells are tightly packed, disappears and the epi- thelium at the tip of the bud consists of loosely packed cuboidal cells. Shortly after treatment, there is a de- crease in the number of gap junctions between ridge cells. This early change in cell contacts suggests that gap junctions may be involved in maintaining epithelial morphology. When treated epithelium is recombined with untreated mesenchyme, an apical ridge is re- established and distal structures can be generated. In contrast, when treated mesenchyme is recombined with the epithelium from normal buds, only proximal struc- tures are formed. Therefore, retinoids can lead to a reorganization of the apical ectodermal ridge which is mediated and maintained by the mesenchyme.
Expression of transforming growth factor β2 RNA during murine embryogenesis
Authors: Pelton Ron W. , Nomura Shintaro , Moses HAROLD L. , Hogan BRIGID L. M. 
Published: April 2021

ABSTRACT
We have studied the temporal and spatial expression of transforming growth factor β2 (TGF/β2) RNA in mouse embryos from 10·5 days post coitum (p.c.) to 3 days post partum (p.p.) by in situ hybridization analysis. TGFβ2 RNA is expressed in a variety of tissues including bone, cartilage, tendon, gut, blood vessels, skin and fetal placenta, and is in general found in the mesenchymal component of these tissues. The expression of TGF/12 RNA changes during development in a manner consistent with a role for the gene product in mediating mesenchymal-epithelial interactions.
Expression of multiple heparin-binding growth factor species by murine embryonal carcinoma and embryonic stem cells
Authors: Heath John K. , Paterno Gary D. , Lindon A. Catherine , Edwards Dylan R. 
Published: April 2021

ABSTRACT
Culture medium conditioned by P19 embryonal carcinoma (EC) cells contains potent mitogenic activity which is markedly potentiated when the medium is conditioned in the presence of heparin. Fractionation of P19 medium conditioned in the presence of heparin reveals the existence of two biochemically distinct growth factor species both of which exhibit high affinity for immobilised heparin and significant activity as amphibian mesoderm-inducing agents. One of the species is recovered as a single polypeptide of apparent Mr = 15 000. This molecule is immunologically related to the protein product of the human K-FGF proto-oncogene. Transcripts derived from the murine K-FGF gene are also expressed by both differentiated and undifferentiated EC cells and embryonic stem cells. The second heparin-binding growth factor is recovered as a complex of four polypeptides, the largest of which has an apparent Mr = 17 000. This agent is immunologically and biochemically distinct from both acidic and basic fibroblast growth factor as well as K-FGF, and represents the predominant mitogenic activity in EC-cell-conditioned medium.
Insulin-like growth factor II may play a local role in the regulation of ocular size
Authors: Cuthbertson R. A. , Beck F. , Senior P. V. , Haralambidis J. , Penschow J. D. , Coghlan J. P. 
Published: April 2021

ABSTRACT
The ultimate size and shape of the eye has a profound influence on its refraction and function. However, the role of growth factors in normal ocular development is poorly understood. Insulin-like growth factors IGF-I and -II have major effects on cell growth and differentiation in tissue culture. Recently their importance for in vivo development has been studied; IGF-II is predominant prenatally, with a probable local role in the differentiation of some mesodermally derived tissues. Ocular development and size is partially dictated by the condensation of the outer collagenous scleral coat (the ‘white’) of the eye from orbital mesoderm. We investigated IGF-II expression and IGF-II receptor distribution during normal ocular development in the mouse fetus using in situ hybridization and immunohistochemistry.
IGF-II mRNA was expressed by the loose mesenchmal orbital tissue as it differentiated to form the sclera, but not in the compact mature sclera or cornea, or in the ectodermally derived retina or skin. IGF-II gene expression was seen in the orbit at E14, reached a peak just before parturition and then declined to background levels after birth. Similarly, type 2 IGF receptors were shown with immunohistochemistry to be present on developing scleral cells and to be modulated in parallel with IGF-II mRNA expression.
We suggest the IGF-II expression by differentiating cells that compact to form the collagenous ocular coat plays a local role in determining the ultimate shape and size of the developing eye.
Microtubule distribution reveals superficial metameric patterns in the early Drosophila embryo
Authors: Callaini Giuliano 
Published: April 2021

ABSTRACT
Microtubule distribution was examined in whole mounts of Drosophila embryos from the cellularization of the syncytial blastoderm (stage 6) to the completion of the gastrulation (stage 7) by fluorescence microscopy. During ventral furrow formation, the fluorescence of tubulin network was not uniform, but disposed in zebra stripes.
Antibodies against α-tubulin showed 14 alternating pairs of darker and brighter transverse areas. The possible significance of this pattern is discussed.
P-element-mediated enhancer detection applied to the study of oogenesis in Drosophila*
Authors: Grossniklaus Ueli , Bellen Hugo J. , Wilson Clive , Gehring Walter J. 
Published: April 2021

ABSTRACT
We have stained the ovaries of nearly 600 different Drosophila strains carrying single copies of a P-element enhancer detector. This transposon detects neighbouring genomic transcriptional regulatory sequences by means of a β-galactosidase reporter gene. Numerous strains are stained in specific cells and at specific stages of oogenesis and provide useful ovarian markers for cell types that in some cases have not previously been recognized by morphological criteria. Since recent data have suggested that a substantial number of the regulatory elements detected by enhancer detection control neighbouring genes, we discuss the implications of our results concerning ovarian gene expression patterns in Drosophila. We have also identified a small number of insertion-linked recessive mutants that are sterile or lead to ovarian defects. We observe a strong correlation with specific germ line staining patterns in these strains, suggesting that certain patterns are more likely to be associated with female sterile genes than others. On the basis of our results, we suggest new strategies, which are not primarily based on the generation of mutants, to screen for and isolate female sterile genes.
Expression of engrailed during segmentation in grasshopper and crayfish
Authors: Patel Nipam H. , Kornberg Thomas B. , Goodman Corey S. 
Published: April 2021

ABSTRACT
We have used a monoclonal antibody that recognizes engrailed proteins to compare the process of segmentation in grasshopper, crayfish, and Drosophila. Drosophila embryos rapidly generate metameres during an embryonic stage characterized by the absence of cell division. In contrast, many other arthropod embryos, such as those of more primitive insects and crustaceans, generate metameres gradually and sequentially, as cell proliferation causes caudal elongation. In all three organisms, the pattern of engrailed expression at the segmented germ band stage is similar, and the parasegments are the first metameres to form. Nevertheless, the way in which the engrailed pattern is generated differs and reflects the differences in how these organisms generate their metameres. These differences call into question what role homologues of the Drosophila pairrule segmentation genes might play in other arthropods that generate metameres sequentially.
Analysis of the testes of H-Y negative XOSxrb mice suggests that the spermatogenesis gene (Spy) acts during the differentiation of the A spermatogonia
Authors: Sutcliffe Maxine J. , Burgoyne Paul S. 
Published: April 2021

ABSTRACT
H-Y antigen negative XOSxrb mice, like their H-Y positive XOSxra counterparts, have testes; but, in contrast to XOSxra males, XOSxrb testes almost totally lack meiotic and postmeiotic stages of spermatogenesis. The quantitative analysis of the testes of XOSxrb males and their XY±Sxrb sibs, described in. the present study, identified two distinct steps in this spermatogenic failure. First, there was a reduction in mitotic activity among T2 prospermatogonia, so that approximately half the normal number of T2 prospermatogonia were produced. Second, there was a dramatic decrease in the number of A3 and A4 spermatogonia and no Intermediate or B spermatogonia. These reductions were also largely due to decreased mitotic activity, there being a shortage of A1 and A2 spermatogonial divisions and no divisions among A3 or A4 spermatogonia. Mitotic activity among the T2 prospermatogonia and the undifferentiated A spermatogonia was normal. This means that the spermatogonial stem cells, which are a subset of the undifferentiated A spermatogonia, are unaffected in XOSxrb mice. Sxrb is now known to have arisen by deletion of DNA from Sxra. It is clear from the present findings that a gene (or genes) present in the deleted DNA plays a major role in the survival and proliferation of the differentiating A spermatogonia.