bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and role of E- and P-cadherin adhesion molecules in embryonic histogenesis: I. Lung epithelial morphogenesis
Authors: Hirai Yohei , Nose Akinao , Kobayashi Shigeyasu , Takeichi Masatoshi 
Published: April 2021

ABSTRACT
The role of Ca2+ -dependent cell-cell adhesion mol ecules, E- and P-cadherins, in the histogenesis of mouse embryonic lung was studied. All epithelial cells of the lung express both E- and P-cadherin at the early developmental stage. P-cadherin, however, gradually disappears during development, initially from the main bronchi and eventually from all epithelial cells. When a monoclonal antibody to E-cadherin (ECCD-1) was added to monolayer cultures of lung epithelial cells, it induced a partial disruption of their cell-cell adhesion, while a monoclonal antibody to P-cadherin (PCD-1) showed a subtle effect. A mixture of the two antibodies, however, displayed a synergistic effect. We then tested the effect of the antibodies on the morphogenesis of lung primordia using an organ culture system. In control media, the explants formed typical bronchial trees. In the presence of ECCD-1, the explants grew up at the same rate as in the control, but their morphogenesis was affected. The control explants formed round epithelial lobules with an open luminal space at the tips of the bronchial trees, whereas the lobules of explants incu bated with ECCD-1 tended to be flat and devoid of the luminal space. PCD-1 showed a similar but very small effect. A mixture of the two antibodies, however, showed a stronger effect: the branching of epithelia was partially suppressed and the arrangement of epithelial cells was distorted in many places. These results suggest that E and P-cadherin have a synergistic role in the organiz ation of epithelial cells in lung morphogenesis.
Initiation of mesodermal cell migration and spreading relative to gastrulation in the urodele amphibian Pleurodeles waltl
Authors: Shi De-Li , Darribère Thierry , Johnson Kurt E. , Boucaut Jean-Claude 
Published: April 2021

ABSTRACT
We have investigated the autonomous migration of marginal cells and their interactions with extracellular matrix (ECM) located on the inner surface of the blastocoel roof in the urodele amphibian, Pleurodeles waltl, using a novel in vitro migration assay. Animal hemispheres containing equatorial cells removed at different cleavage stages and dorsal marginal zone (DMZ) expiants of early gastrula stage were cultured either on fibronectin (FN)-coated or ECM-conditioned substrata. In explanted animal hemispheres, dorsal marginal cells showed autonomous migration on FN-coated substratum at the same time as the onset of gastrulation in control embryos. They acquired this capacity at least at the 32-cell stage, whereas lateral and ventral marginal cells acquired it after the 64-cell stage. DMZ outgrowths of early gastrula stage exhibited auton-omous spreading on both substrata. In addition, we showed that they spread preferentially toward the ani-mal pole when deposited on substratum conditioned by the dorsal roof of the blastocoel. By culturing dissociated marginal cells on ECM-conditioned substratum, we also found that increased spreading capacity of marginal cells was related to the initiation of their migration. A comparative study of the migration of marginal cells in ultraviolet (u.v.)-irradiated and normal embryos was also made. The results indicate that dorsal marginal cell migration was absent or dramatically reduced by u.v.-irradiation. These results suggest that the differential acquisition in the spreading capacity both in timing and in intensity around the marginal zone was correlated with the sequential involution of mesodermal cells in the course of gastrulation.
Cloned mouse melanocyte lines carrying the germline mutations albino and brown: complementation in culture
Authors: Bennett Dorothy C. , Cooper Philip J. , Dexter Tim J. , Devlin Linda M. , Heasman Janet , Nester Barry 
Published: April 2021

ABSTRACT
We have established two new immortal lines of mouse melanocytes, melan-b and melan-c, from mice homozygous for the brown (b) and albino (c) mutations respectively. Both lines were derived through differentiation in vitro of embryonic epidermal melanoblasts. The brown melanocytes are visibly brown by light microscopy, and centrifuged cell suspensions form brown pellets. The albino melanocytes form white pellets and contain abundant unpigmented premelanosomes as shown by transmission electron microscopy. Like normal, non-immortal melanocytes and like the immortal black melanocyte line melan-a, both lines show little or no growth in a standard, serum-supplemented medium, but proliferate well in the presence of 12-o-tetradecanoyl phorbol-13-acetate (TPA). Sustained growth of the albino cells also requires either keratinocyte feeder cells or 2-mercaptoethanol (2-ME). The modal chromosome numbers are 39 for melan-b and 40 (diploid) for melan-c. Neither line is tumorigenic in nude mice. Hetero-karyons between the two lines can be constructed and form wild-type, black pigment. Melanocyte lines can now be reproducibly generated from mice of different strains, and provide tools for molecular studies of germline coat-colour mutations. These two lines provide elegant means to study the developmentally controlled expression of the two complementary genes, B and C, with black melanin pigment as a readily detectable natural marker.
Cyclic-AMP-induced elevation of intracellular pH precedes, but does not mediate, the induction of prespore differentiation in Dictyostelium discoideum
Authors: Campagne Michiel M. Van Lookeren , Aerts Rob J. , Spek Wouter , Firtel Richard A. , Schaap Pauline 
Published: April 2021

ABSTRACT
Prespore gene expression in Dictyostelium is induced by the interaction of cAMP with cell surface cAMP receptors. We investigated whether intracellular pH (pHi) changes mediate the induction of prespore gene expression by cAMP. It was found that cAMP induces a 0 ·15 unit increase in pHi within 45 min after stimulation. The cAMP-induced pHi increase precedes the induction of prespore gene expression, measured by in vitro transcription, by about 15 ·30 min. Cyclic-AMP-induced pHi changes can be bypassed or clamped by addition of, respectively, the weak base methylamine, which increases pHi, or the weak acid 5,5-dimethyl-2,4-oxazolidinedione (DM0), which decreases pHi. Bypass of the cAMP-induced increase of pHi with methylamine does not induce the expression of prespore genes, while
inhibition of the pHi increase with DMO does not inhibit the induction of prespore gene expression. Cyclic-AMP-induced prespore protein synthesis and the proportion of prespore cells in multicellular aggregates are also not affected by bypassing or inhibiting the cAMP-induced pHi increase. These results show that although a morphogen-induced pHi increase precedes the induction of prespore gene expression, this increase does not mediate the effects of the extracellular cAMP signal on the transcription or translation of prespore genes in Dictyostelium discoideum.
Neural crest development in Xiphophorus fishes: scanning electron and light microscopic studies
Authors: Sadaghiani Bahram , Vielkind Juergen R. 
Published: April 2021

ABSTRACT
We have studied neural crest development in two teleost fish species, Xiphophorus maculatus (platyfish) and X. heUeri (swordtail), and found similarities to that in other vertebrates but also some important differences. Unlike in other vertebrates, segregation of neural crest cells occurs in masses or groups from the dorsal-lateral part of the neural keel (tube) except in the mesencephalon region, where neural crest cells segregate from the dorsal-midline and in the most anterior trunk region, where they segregate individually. However, the cells were found in the usual neural tube-somite and somite-ectoderm migration pathways. Notably numerous cells, presumed in part to be neural crest cells, were found in a third location, dorsally on the neural tube. These cells exhibit a series of morphological stages referred to as ‘covering’, ‘condensation’, and ‘differentiation’. A great amount of ECM was observed in these fish and can be temporally and regionally correlated with the appearance of the neural crest cells. No major differences could be detected between the two fish species with the exception that segregation and appearance of neural crest cells in various locations occur earlier in the platyfish. This time difference could lead to perturbations in neural crest cell development in certain platyfish-swordtail hybrids and may contribute to the formation of neural-crest-derived pigment cell tumours, melanomas, in these hybrids.
Patterns of engrailed protein in early Drosophila embryos
Authors: Karr Timothy L. , Weir Michael P. , Ali Zehra , Kornberg Thomas 
Published: April 2021

ABSTRACT
By the onset of gastrulation during nuclear cycle 14 of Drosophila embryogenesis, the engrailed gene is expressed in fourteen one-cell-wide stripes. Each stripe defines the anlagen of the posterior compartment of a metamerie segment. We report here several observations relating to the role and disposition of the engrailed protein during the embryonic stages that precede cellularization. We demonstrate that in embryos mutant for the engrailed gene, there were characteristic morphological abnormalities as early as the 6th cleavage cycle. In addition, the engrailed protein was detected in pre-cycle-9 embryos by Western blot analysis. When localization of engrailed protein begins during cycle 14, engrailed expression was first present in broad anterior and posterior regions before the fourteen-stripe pattern appeared.
Region-specific deposition of dermal proteins between dermis and epidermis during induction of chick feather and scale rudiments
Authors: Peterson Charlotte A. , Phillips William H. , Grainger Robert M. 
Published: April 2021

ABSTRACT
To begin to study the role of particular proteins in inductive tissue interactions, we have used density labelling techniques to determine whether any dermal proteins are found between embryonic chick dermis and epidermis at a stage when the dermis plays an important inductive role in epidermal differentiation. Epidermis will form feathers or scales depending on whether it Interacts with dorsal or foot dermis, respectively, and the dermis can still influence epidermal differentiation when direct cell contact between the tissues ls blocked by a membrane filter during culturing (Peterson & Grainger, 1985). In transfilter experiments, we detect a subset of dermal proteins within the filter between the tissues. Several of these dermal proteins are deposited in a region-specific manner, that is, they are only found associated with filters from either dorsal or foot dermis.
We have previously shown that the expression of some of these proteins is specific to particular regions of dermis and is also associated with the inductive potential of the dermis (Peterson & Grainger, 1986). We detect only 17 dermal proteins which are transferred across the filter in these cultures and found in direct association with epidermis; of these 14 are common to both dorsal and foot dermis, and 3 are deposited in a region-specific manner. Our results lead us to hypothesize a significant function for certain dermal proteins in this Inductive interaction either as part of the extracellular matrix or in direct association with epidermis.
The early development of motor axon pathways in the locust embryo: the establishment of the segmental nerves in the thoracic ganglia
Authors: Whitington Paul M. 
Published: April 2021

ABSTRACT
This study has identified the first five motor neurones to send axons out of the segmental nerves in the thoracic ganglia of the locust and has traced the pathways followed by these axons up to their divergence into the ganglionic nerve roots. These motor neurones send out axons in a stereotyped sequence over a short period, corresponding to 2% of embryonic development. Motor axons initially grow dorsally to contact the dorsal basal lamina and then posteriolaterally in a parallel array just beneath this membrane. At the edge of the CNS the axons diverge into either of two pathways: an anterior pathway, corresponding to nerve root 3 which is pioneered by the first motor axon to leave the CNS; and a posterior pathway, corresponding to nerve root 5, which is pioneered by the second motor axon. The first motor axon appears to grow circumferentially around the segmental border between the body wall and the base of the coxa, while the second is closely associated with the filopodia or axons of the afferent peripheral pioneer neurones. The later motor axons reliably follow the pathways pioneered by these first two axons. A small number of molecular markers would be sufficient to generate the observed patterns of axon growth by these early motor neurones and some of these same cues may be used to guide afferent axons into the CNS.
Preparation and characterization of cell-free protein synthesis systems from oocytes and eggs of Xenopus laevis
Authors: Patrick Tina D. , Lewer Clare E. , Pain Virginia M. 
Published: April 2021

Abstract
During the maturation of the oocytes of the frog Xenopus laevis, the rate of protein synthesis shows a twofold increase. Studies of the mechanisms involved in this stimulation have been seriously limited by the lack of an active cell-free translation system. We have now prepared such systems from oocytes, progesterone-matured oocytes and eggs of Xenopus laevis by induction of lysis by centrifugation of whole cells.
The extracts are highly active in incorporation of labelled amino acids and, in the progesterone-matured and egg extracts, a substantial proportion of this is due to reinitiation on endogenous mRNA, as shown by the use of inhibitors. The increased rate of protein synthesis previously observed in intact oocytes following progesterone-induced maturation is reflected in the relative activities of the extracts. The difference in activity is not due to the presence of a dominant inhibitor of translation in the extracts from unstimulated oocytes. Labelling studies with initiator tRNA ([35S]Met-tRNAf) indicate a higher concentration of 43S preinitiation complexes in the extracts from unstimulated oocytes, suggesting an impairment of initiation of translation at or after the mRNA-binding step. Extracts from both oocytes and progesterone-matured oocytes translated endogenous mRNAs to give products ranging over a wide spectrum of molecular weight. However, significant translation of exogenous (globin) mRNA required the presence of reticulocyte postribosomal supernatant, suggesting that one or more factors required for mRNA recruitment is limiting in these extracts.
Plasminogen activator expression in F9 teratocarcinoma embryoid bodies and their endoderm derivatives
Authors: Sabbag Kenneth R. , Casanova James E. , Grabel Laura B. 
Published: April 2021

Abstract
Plasminogen activators are believed to play an important role in tissue remodeling and cell migration. During mouse embryogenesis, visceral endoderm secretes urokinase-type plasminogen activator (uPA) whereas parietal endoderm secretes tissue-type plasminogen activator (tPA). Visceral endoderm from F9 embryoid bodies can transdifferentiate into parietal endoderm under the appropriate culture conditions. We have examined at the protein and mRNA levels the type of plasminogen activator expressed in whole embryoid bodies, visceral endoderm and its parietal endoderm derivatives. Our experiments show that the visceral endoderm on F9 embryoid bodies synthesizes and secretes substantial amounts of both tPA and uPA. In contrast, the parietal endoderm derived directly from the visceral endoderm secretes dramatically increased levels of tPA and decreases production of uPA to low or below detectable levels. These data support the finding that visceral endoderm can transdifferentiate to parietal endoderm. In addition, this transition provides an excellent model for studying the molecular basis of the coincident down- and upregulation of the two plasminogen activators as well as their potential function during embryogenesis.
Induction of functional cytodifferentiation in the epithelium of tissue recombinants : I. Homotypic seminal vesicle recombinants
Authors: Higgins Stephen J. , Young Peter , Brody Joel R. , Cunha Gerald R. 
Published: April 2021

ABSTRACT
Functional cytodifferentiation of seminal vesicle epithelium was investigated in tissue recombinants. Neonatal rat and mouse seminal vesicles were separated into epithelium and mesenchyme using trypsin. Epithelium and mesenchyme were then recombined in vitro to form interspecific rat/mouse homotypic recombinants. Growth as renal grafts in adult male athymie mice resulted in seminal vesicle morphogenesis in 70 % of the recombinants (the remaining 30 % failed to grow). Functional cytodifferentiation was judged by the expression of the major androgen-dependent secretory proteins characteristic of the seminal vesicles of adult rats and mice. Antibodies specific for each of these proteins were used to screen tissue sections by immunocytochemistry and to probe protein extracts by immunoblotting techniques. The heterospecific recombinants synthesized the full range of seminal vesicle secretory proteins that typifies the species providing the epithelium of the recombinant, not the mesenchyme. There was little functional variation between individual recombinants. The time course of development corresponded to that of intact neonatal seminal vesicles grown under the same conditions. Morphogenesis and functional cytodifferentiation were not evident after one week, but were well advanced after two weeks. Seminal vesicle recombinants grown for three weeks were indistinguishable morphologically and functionally from normal adult seminal vesicles. In addition, the ability of adult seminal vesicle epithelium to be induced to proliferate was examined. In association with neonatal seminal vesicle mesenchyme, the epithelium of the adult seminal vesicle proliferated and retained its normal functional activity. Thus, seminal vesicle functional cytodifferentiation can be faithfully reproduced in homotypic tissue recombinants. The methods used in this study will be used to investigate seminal vesicle development in instructive inductions of heterotypic epithelia.
Change in motor neurone activity modifies the differentiation of a slow muscle in chick embryo
Authors: Fournier Le Ray C. , Renaud D. , Le Douarin G. H. 
Published: April 2021

ABSTRACT
Slow-tonic anterior latissimus dorsi (ALD) muscle properties were studied following chronic spinal cord stimulation in chick embryo. Stimulation at a fast rhythm was applied from day 7, 8 or 10 of development until the end of embryonic life. When stimulation was applied from day 7 up to day 18 of development, ALD muscle exhibited at day 18 a large decrease in half time to peak of tetanic contraction, a large proportion of fast type II fibres and an increase in fast myosin light chain content as compared to control muscle. When stimulation started at day 8 of development, changes in properties of ALD muscle were reduced when compared to the previous experimental series. Indeed, no fast type II fibres were observed within the muscle, even when stimulation was prolongated until the 20th day of embryonic development. In addition, chronic stimulation at a fast rhythm initiated at day 10 of development did not modify ALD muscle differentiation. The present results indicate that a fast pattern of motor neurone activity can induce some slow-to-fast transformations of ALD muscle fibres. However, after the first week of embryonic life, ALD myotubes appeared refractory to these transformations. The possible mechanisms responsible for the transformation of slow myotubes and for their further loss of plasticity are discussed.
Systematic non-uniform distribution of parthenogenetic cells in adult mouse chimaeras
Authors: Nagy András , Sass Miklós , Markkula Merja 
Published: April 2021

ABSTRACT
Even though pure parthenogenetic mouse embryos die shortly after implantation, their cells are capable of participating in normal development of chimaeras when aggregated with fertilized embryos. Here we present data on parthenogenetic contribution to the oocyte populations measured by progeny tests in female chimaeras, and on distribution of parthenogenetic cells among the different organs by GPI typing. Systematic uneven distribution was detected. The highest level of participation was registered in the tissues of permanent cells (e.g. up to 63 % in female germline). On the other hand, parthenogenetic cells were absent in several tissues that have extensive capacity for postnatal growth or selfrenewal. This finding suggests that uneven selective processes operate against parthenogenetic cells within certain differentiation pathways during fetal and postnatal life, as has already been observed in the development of extraembryonal membranes. It is likely that more than one mechanism is responsible for these selections. Parthenogenetic cells may start to differentiate in all cell lineages, but they are not able to react normally at certain points in the developmental pathway, for example to induction signals and, therefore, the cells fail to complete the normal processes of development, or to the proliferation requirement so that the fertilized counterpart gradually takes over the cell lineage. Paternally derived gene(s) might have a unique role in the development of tissues lacking parthenogenetic contribution.
Imaginal disc-autonomous expression of a defect in sensory bristle patterning caused by the lethal(3)ecdysoneless1 (l(3)ecd1) mutation of Drosophila melanogaster
Authors: Sliter Timothy J. 
Published: April 2021

ABSTRACT
The temperature-sensitive mutation l(3)ecd1 of Dros­ophila melanogaster is known to autonomously impair the ability of the larval prothoracic gland to produce the steroid molting hormone ecdysone in response to stimu­lation by the tropic neuropeptide prothoracicotropic hormone. It is shown that autonomous expression of the l(3)ecct1 mutation in metamorphosing imaginal tissues disrupts the spatial pattern of sensory bristles. Transfer of homozygous mutant animals to the restrictive tem­perature at the time of pupariation resulted in the elimination of sensory microchaetae and macrochaetae. This effect was specific to the sensory bristles; nonsensory bristles were not eliminated, nor were other types of innervated cuticular sense organs. In the case of the dorsal thoracic macrochaetae, normal ecd gene function is required during an early period of bristle development (0—18 h after puparium formation at 20°C). It is during this period that important determinative events take place in developing imaginal tissues that are responsible for the establishment of bristle progenitor cells. It is proposed that the ecd gene product may be required for the response of certain classes of cells to specific, regulatory signals.
Cell proliferation and expression of cytokeratin filaments in F9 embryonal carcinoma cells
Authors: Kurki P. , Laasonen A. , Tan E. M. , Lehtonen E. 
Published: April 2021

ABSTRACTA double immunofluorescence method was developed for the monitoring of proliferation and differentiation of F9 embryonal carcinoma cells. Cytokeratin filament expression was used as a marker for differentiation, and proliferating cell nuclear antigen (PCNA)/cyclin or bromodeoxyuridine labeling were used as markers for proliferation. F9 cells had a high proliferation rate and were cytokeratin-filament-negative. Upon treatment with retinoic acid and dibutyryl cyclic AMP, cytokeratin-filament-positive cells with differentiated phenotype appeared. After 3 days, the extent of proliferation of cytokeratin-filament-positive cells was comparable to, but after 5 days significantly lower than, that of cytokeratin-filament-negative cells in the same culture. In differentiating F9 cells, cytokeratin filament expression is associated with, and even slightly precedes, the dramatic decrease in the rate of proliferation.