bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of Cell Surface Binding of Fibronectin and Fibronectin‐Promoted Cell Migration by Synthetic Peptides in Sea Urchin Primary Mesenchyme Cells In Vitro
Authors: KATOW HIDEKI 
Published: January 2005

The role of a site of fibronectin molecule in the cell binding and cell migration was examined in vitro using sea urchin primary mesenchyme cells and synthetic peptides that contain a particular amino acid sequence, Arg‐Gly‐Asp‐Ser.The binding of fibronectin to the cell surface was inhibited by addition of larger synthetic peptides, Gly‐Arg‐Gly‐Asp‐Ser‐Pro‐Cys (HP) or Arg‐Gly‐Asp‐Ser‐Pro‐Ala‐Ser‐Ser‐Lys‐Pro (DP), but not by a smaller synthetic peptide Gly‐Arg‐Gly‐Asp‐Ser (PP). The inhibition was recovered by addition of excess amount of fibronectin to the medium.The fibronectin‐promoted cell migration, by contraries, was conspicuously inhibited by addition of the PP to the cell culture medium which has alrady contained sufficient amount of fibronectin for the migration, but not so obviously by addition of the larger peptides, the HP or the DP. The inhibition was also recovered by addition of excess amount of fibronectin.These results indicated that fibronectin utilizes Arg‐Gly‐Asp‐Ser in the molecule as an active cell binding and a cell migration promotion site. Slightly different effects seen between the smaller peptide and the larger ones were discussed.
Urea‐Induced Meiosis Reinitiation in Oocytes of the Starfish, Marthasterias glacialis
Authors: GUERRIER P. , NÉANT I. , CLÉDON P. 
Published: January 2005

In the absence of hormone stimulation, prophase‐blocked oocytes of Marthasterias glacialis have been induced to undergo meiosis reinitiation up to female pronucleus formation by pulse incubation in isoosmotic urea‐sea water solutions. Even when this procedure was not effective all along the breeding season, it could trigger full maturation when applied to so‐called “incompetent oocytes” that did not complete maturation following microinjection‐induced mixing of their nucleoplasm and cytoplasm. 32P phosphate incorporation into proteins and cell fusion experiments demonstrate that this treatment produces an increased protein phosphorylation which appears tightly associated with the production of M‐phase promoting factor (MPF). Instead, when oocytes are maintained in the inducing medium, dephosphorylation soon occurs and MPF is no longer present to support meiosis. Under these conditions, the GV‐disrupted oocytes present a permanent nucleolus and do not form a meiotic spindle. The same cytological aspect was also obtained when the oocytes were treated in the presence of 90 μM emetine or 150 μM of the intracellular chelator Quin 2‐AM.These data suggest that urea‐induced maturation may involve an intracellular Ca2+ shift which would be required to activate both MPF precursor molecules and the resting female centers which stand in the animal cortex outside the nucleus and give rise to the poles of the first maturation spindle. They also show that nuclear disruption alone, without protein phosphorylation, cannot trigger meiosis reinitiation of incompetent oocytes.
Significance of an Increase of Intracellular Adenosine Concentration for Dormancy in Starfish Blastulae
Authors: TSUCHIMORI NOBORU , MIYASHIRO SHIGEYOSHI , SHIBAI HIROSHIRO , IKEGAMI SUSUMU 
Published: January 2005

Adenosine at concentrations greater than 6 μg/ml halted embryonic development of the starfish Asterina pectinifera specifically at the 256‐cell stage which corresponds to the onset of blastulation. When a fertilized egg was cultured continuously in sea water containing adenosine from fertilization, a gradual increase in intracellular concentrations of free adenosine was observed before a cessation of development took place. On the other hand, intracellular concentrations of ATP, ADP and AMP in the embryo cultured in sea water containing adenosine were nearly the same as those of an embryo cultured in sea water without adenosine. By returning the development‐arrested embryo to normal sea water the embyro developed normally to the bipinnaria stage accompanied by a gradual decrease in the intracellular cencentration of adenosine.Treatment of fertilized eggs with 9‐β‐d‐arabinofuranosyl‐9H‐purine‐6‐amine (25 μg/ml) or 2′‐deoxyadenosine (10 μg/ml) halted development specifically before the onset of blastulation in an irreversible manner. Embryos treated with 3′‐deoxyadenosine (50 μg/ml) shortly after fertilization developed to healthy blastulae but hatching never occurred. These results exclude the possibilities that the action of adenosine is mediated by the inhibition of DNA synthesis or RNA polyadenylylation.
The Prosencephalon Has the Capacity to Differentiate into the Optic Tectum: Analysis by Chick‐Specific Monoclonal Antibodies in Quail‐Chick‐Chimeric Brains
Authors: NAKAMURA HARUKAZU , TAKAGI SHIN , TSUJI TOSHIAKI , MATSUI KOHJI A. , FUJISAWA HAJIME 
Published: January 2005

The alar plate of the prosencephalon of the quail embryo was heterotopically transplanted into the alar plate of the mesencephalon of the chick embryo at the 7–10 somite stage. Chick and quail cells in chimeric brains were distinguished after Feulgen‐Rossenbeck staining and/or immunohistochemical staining with a species specific monoclonal antibody MAb‐37F5 which recognized cytoplasmic components of chick brain cells. Neural connections between the transplant and the host were studied by monoclonal antibodies, MAb39‐B11, which recognizes a species specific antigen on chick nerve fibers, and MAb‐29B8, which reacts to 160 kD neurofilaments of both chick and quail.When the transplant was completely integrated into the host mesencephalon, the transplant developed a laminar morphology closely resembling that of the optic tectum. Immunohistochemical staining with MAb‐39B11 showed that the host optic nerve fibers innervated both the host tectum and the tectum‐like transplant. However, optic nerve fibers did not invade transplants that failed to develope a laminar structure characteristic of the tectum. These findings suggest that the prosencephalon has a capacity to differentiate into the optic tectum at the 7–10 somite stage.
Differentiation of Striated Muscle Fibers in Monolayer Cultures of Rat Anterior Pituitary
Authors: Watanabe Yuichi G. 
Published: January 2005

Striated muscle fibers appeared in monolayer cultures of rat anterior pituitary cells maintained in αMinimum Essential Medium (αMEM). As muscle differentiation in cultures of pituitary cells under ordinary conditions has not hitherto been reported, an in vitro study was undertaken to determine what factor(s) is responsible for this myogenesis. When dispersed anterior pituitary cells were culrured in three different media, αMEM, Medium 199 and Dulbecco's Modified Eagle Medium (DMEM), only αMEM induced a high incidence of striated muscles. The nature of the serum (fetal calf, calf and horse) and its concentration (1–10%) did not affect myogenesis.In monolayers in αMEM, the sequence of differentiation of striated muscle was as follows: 1) Elongated cells, resembling myoblasts appeared; 2) these cells fused; and finally 3) cross striations appeared. Rhythmic contraction was most intense in striated muscle fibers, but it was also obsrved in myotubes without cross striations and even in myogenic cells before fusion. The possible origin of muscles in these pituitary cultures is discussed.
Pluripotent Embryonal Stem Cell Lines Can Be Established from Disaggregated Mouse Morulae
Authors: Eistetter Harald R. 
Published: January 2005

Mouse pluripotent embryonal stem (ES) cell lines hitherto have been conventionally isolated from the ‘inner cell mass’ of mouse blastocysts. In this report, I describe a new and simplified method for establishing pluripotent cell lines from mouse morulae of the 16‐ to 20‐cell stage, which were disaggregated by the use of EDTA. From 17 cell lines established in such a way, 7 were characterized with respect to their differentiation potential:(i) When injected into syngeneic mice, the cells gave rise to solid, fully differentiated teratomas representing derivatives of all three germ layers. (ii) When cultured in suspension in vitro, the cells were able to differentiate into complex organized ‘embryoid bodies’ analogous to mouse early postimplantation embryos. These results strongly imply that embryonal stem cell lines isolated from mouse morulae are highly homologous to conventionally isolated ES cells.In addition, my results indicate that murine pluripotent embryonal stem (ES) cell lines can be derived with more ease and higher efficiency from disaggregated morulae than from the ‘inner cell mass’ of blastocysts.
Characterization of Vegetal Plate Cells Separated from Cytochalasin B‐Treated Blastulae of the Sea Urchin, Clypeaster japonicus
Authors: Katow Hideki 
Published: January 2005

Vegetal plate forming cells (VPCs) of the vegetal plate blastulae of the sea urchin, Clypeaster japonicus, had a layer of microfilaments on the basal side. The VPCs specifically protruded from the embryos after a treatment with 1 μg/ml of cytochalasin B (CB). Based on scanning electron microscopy, unlike other epithelial cells the protruded VPCs possessed neither cilium nor microvilli on their surface. The protruded VPCs were easily separated from the embryos by stirring the embryo suspension with pipette. An in vitro immunohistochemistry using a primary mesenchyme cell (PMC) surface‐specific monoclonal antibody (MAb) raised against PMCs of Strongylocentrotus purpuratus showed that the MAb also specifically bound to the PMCs in mesenchyme blastulae of C. japonicus. The MAb bound in 81% of the separated VPCs in C. japonicus vegetal plate blastulae examined. However, the MAb binding occurred only after the separated VPCs were incubated in artificial sea water (ASW) for at least 1 hr. In the VPC‐deprived embryos, gastrulation occurred after they were transferred to normal ASW. However, the PMCs and the spicules were not formed in these embryos.In conclusion, a majority of the VPCs separated from the CB‐treated blastulae were presumptive PMCs. These VPCs provide an excellent source of presumptive PMCs.
Three Phases of Cortical Maturation during Meiosis Reinitiation in Starfish Oocytes
Authors: Chiba Kazuyoshi , Hoshi Motonori 
Published: January 2005

Oocytes of the starfish, Asterina pectinifera, respond differently to calcium ionophore A23187 depending upon their stage of maturation. Oocytes not‐treated with 1‐methyladenine (1‐MA) formed only a partial fertilization envelope (FE) in response to A23187. Those treated with 1‐MA formed no FE if the ionophore was introduced to them before germinal vesicle breakdown (GVBD), in contrast with which they did fully elevate the FE if it was introduced after GVBD. Similar stage‐dependent results were obtained if the intracellular concentration of calcium was increased by microinjection of calcium‐EGTA buffers. In good accordance with the FE formation, a stage‐dependent protease release from oocytes by the ionophore was observed.It is concluded from these results that, in starfish oocytes, their ability to undergo the exocytosis of cortical granules in response to an increase in intracellular calcium greatly changes along the way of maturation.
Early Determination of Developmental Fate in Presumptive Intestinal Endoderm of the Chicken Embryo
Authors: Yasugi Sadao , Takeda Hiroyuki , Fukuda Kimiko 
Published: January 2005

The endodermal epithelia of esophagus, proventriculus and gizzard of 6‐day chicken embryos can form glands and express embryonic chicken pepsinogen (ECPg), when they are subjected to the influence of proventricular mesenchyme, while intestinal epithelium of the same age cannot respond to the inductive influence of proventricular mesenchyme. We attempted in this paper to know whether this regional difference of epithelia to respond to mesenchymal influence originates very early in development or it is established gradually in the course of development of digestive tract.The young presumptive intestinal endoderm taken from embryos having 15–20 somites was associated and cultivated with 6‐day proventricular mesenchyme. The presumptive intestinal endoderm never expressed ECPg although it formed gland‐like structures. In the control explants composed of presumptive stomach endoderm and proventricular mesenchyme, glands were formed and gland cells expressed ECPg detected by immunocytochemistry and in situ hybridization.These results indicate that the developmental fate of presumptive intestinal endoderm is determined rather strictly at very early developmental stage, and suggest that the segregation of at least two cell lineages occurs early in the development; one which can express ECPg under the influence of proventricular mesenchyme, and another one which cannot express ECPg and differentiates mainly into intestinal epithelium.
Induction of Pronephric Tubules by Activin and Retinoic Acid in Presumptive Ectoderm of Xenopus laevis
Authors: Moriya Naomi , Uchiyama Hideho , Asashima Makoto 
Published: January 2005

Correlation between activin and retinoic acid (RA), both of which affect early amphibian development, was studied using Xenopus laevis embryos. In the first set of experiments, two isomers of RA, all‐trans RA and 13‐cis RA, were compared in terms of stability of biological activity against light. Xenopus blastulae were dipped in RA solutions which had either been kept away from light, or had been exposed to light for a few hours. At doses ranging from 10–4to 10–6M, RA elicited head deformity. All‐trans RA, under both dark and light conditions, had similarly potent effects. On the other hand, 13‐cis RA under dark conditions had much weaker effects than it did under light conditions.In the second set of experiments, activin was mixed with all‐trans RA, and the inducing effects on the animal cap explants were investigated. Activin at a concentration of 10 ng/ml induced notochord. In combination with 10–6M RA, muscle was well induced instead of notochord. In combination with 10–5M RA, pronephric tubules were markedly induced. Pronephric tubules were never induced by activin alone, at any of the various concentrations employed. This is the first report on the very high frequency of induction of pronephric tubules by the combination of activin A and all‐trans RA in the Xenopus ectoderm.
Remodeling of the Nauplius Eye into the Adult Ocelli during Metamorphosis of the Barnacle, Balanus amphitrite hawaiiensis
Authors: Takenaka Makoto , Suzuki Akiko , Yamamoto Takashi , Yamamoto Masamichi , Yoshida M. 
Published: January 2005

The planktonic barnacle larva has a single median ocellus (nauplius eye), while the adult possesses two distinct sets of photoreceptors; a pair of lateral ocelli and a single median ocellus. The nauplius eye of the cypris larva of Balanus amphitrite hawaiiensis is composed of 14 visual cells grouped into three components (a pair of lateral components and a single ventral component) surrounding two centrally located pigment cells; each lateral component consists of 5 visual cells and the ventral component, 4 visual cells. In each component, the rhabdom is made up of apposing microvilli arising directly from the neighboring visual cell bodies.During metamorphosis into the adult form, the three components of the median ocellus become separated. Each lateral component migrates laterally on the mantle and is remodeled into the adult lateral ocellus, losing two visual cells but gaining new pigment and tapetum cells in the process. The ventral component remains in the mid portion and becomes the adult median ocellus without fundamental modification in composition. The visual cells in both ocelli undergo a marked increase in volume and form many finger‐like dendrites. Rhabdomes are made up of interdigitating microvilli arising from the the dendrite tips.
Removal of Heparan Sulfate Chains Halted Epithelial Branching Morphogenesis of the Developing Mouse Submandibular Gland in vitro
Authors: Nakanishi Yasuo , Uematsu Jun , Takamatsu Hiroshi , Fukuda Yuh , Yoshida Keiichi 
Published: January 2005

The physiological function of heparan sulfate chains in the mouse embryonic submandibular gland was studied by the use of heparitinases purified from Flavobacteriu heparinum. Heparitinase I, which catalyzes the cleavage of specific glycosaminidic linkages adjacent to non‐or monosulfated disaccharides of heparan sulfate chains, in the culture medium of the mid and late 12‐day gland inhibited the branch‐initiation and changed their round epithelial shape to elongated one, together with a concommitant reduction in lobular growth. [3H]Thymidine incorporation experiments indicated that heparitinase I treatment blocked 24% of the DNA synthesis compared with controls. Analysis of 35S‐inorganic sulfate labeled glycosaminoglycans extracted from cultured rudiments revealed that the glands with heparitinase I contained no heparan sulfate, while in the glands without the enzyme more than 20% of total glycosaminoglycans was heparan sulfate.The heparitinase effect on morphogenesis was mimicked by the addition of heparan sulfate (1 mg ml−1) or heparin (75 μg ml−1), but not by chondroitin sulfate (1 mg ml−1) in the culture medium. Transmission electron microscopic study indicated that at the epithelial‐mesenchymal interface close contacts between the fibroblast and epithelial cells were much fewer in heparitinase‐treated glands than in controls. Immunohistochemical analysis demonstrated that the core protein of basement membrane heparan sulfate proteoglycan and type IV collagen accumulated abnormally inside the epithelial lobules of glands cultured with heparitinase I. These results strongly suggested that glycosaminoglycan chains of heparan sulfate or heparin is involved in the epithelial morphogenesis of the mouse embryonic submandibular gland.
Xenopus Heterochronic Presumptive Primordial Germ Cells (pPGCs) Implanted in the Correct Position in Host Neurula Embryos can Differentiate into PGCs
Authors: Ikenishi Kohji , Tanaka Tetsuya S. 
Published: January 2005

Presumptive primordial germ cells (pPGCs) in explants, derived from single germ plasm‐bearing cells of Xenopus 32‐cell embryos, at the equivalent of neurula stage (stage 20) in control embryos (designated as ‘stage‐20′ explants) were demonstrated to be able to differentiate into PGCs, when implanted into a prospective place of pPGCs in host embryos (stage 20) (Ikenishi & Tsuzaki, 1988). According to a recent proposal that individual early embryonic cells in Xenopus, at both in vivo and in vitro, are able to measure elapsed time since fertilization (Cooke and Smith, 1990), the result means that the implanted pPGCs having the same elapsed time as the host embryos (isochronic pPGCs) could differentiate into PGCs. In the present study, in order to know whether the compatibility in elapsed times of implanted pPGCs and host embryos is necessary for the differentiation of PGCs, labelled, heterochronic pPGCs in ‘stages 12–33/34′ explants were implanted into unlabelled, host neurulae (stage 19).Those heterochronic pPGCs could differentiate into PGCs like isochronic pPGCs in ‘stage‐19′ explants as the control. By comparing the average diameters and yolk contents of labelled PGCs with those of unlabelled, host ones in experimental tadpoles, the possibility that a certain mechanism modulating the elapsed time of heterochronic pPGCs to that of host pPGCs is present in host embryos was also suggested.
Distribution of Retinoids Applied Exogenously to Chick Limb Buds: an Autoradiographic Analysis
Authors: Tamura Koji , Hashimoto Yuichi , Shudo Koichi , Ide Hiroyuki 
Published: January 2005

An autoradiographic analysis was undertaken to examine the localization of retinoids applied exogenously to chick limb buds. Ion‐exchange beads (AGI‐X2) containing a tritium‐labeled synthetic retinoid, Am80, were implanted to various regions of chick wing buds. This synthetic retinoid is known to induce a duplicated limb pattern as retinoic acid (RA) does. One to 24 hours after the application, wing buds were fixed, sectioned, and prepared for autoradiography. Heavy labeling was observed in the peripheral region of the wing mesoderm, but no gradient along the antero‐posterior axis was found.These results suggest that the peripheral region of the limb bud may be important for the morphogenetic function of RA. Tissue‐bound retinoids may not form an antero‐posterior concentration gradient when retinoids are added to the anterior margin of the chick limb bud.
Presumptive Primordial Germ Cells (pPGCs) and PGCs in Tadpoles from UV‐irradiated embryos of Xenopus
Authors: Kotani Minoru , Ogiso Yurie , Ozaki Ritsuko , Ikenishi Kohji , Tsugawa Katsuji 
Published: January 2005

In order to determine whether or not tadpoles that once lacked primordial germ cells (PGCs) in the genital ridges and dorsal mesentery as a result of ultraviolet (UV) irradiation subsequently contained germ cells at more advanced stages of larval development, the numbers of presumptive PGCs or PGCs were carefully examined in Xenopus tadpoles at Nieuwkoop and Faber's stage 35/36–52 that developed normally from UV‐irradiated eggs.No late‐appearing germ cells were observed in almost all the UV‐irradiated tadpoles examined at stages 49–52. This same population had completely lacked PGCs at about stage 46. Moreover, presumptive PGCs (pPGCs) or cells with granular cytoplasm that reacted with a monoclonal antibody specific for the germ plasm of cleaving Xenopus eggs stayed in the central part of the endoderm cell mass in the irradiated tadpoles at stage 35/36, when the majority of those cells were located in the dorsal part of the endoderm in unirradiated controls. Furthermore, in the irradiated embryos pPGCs were demonstrated to decrease in number with development and eventually to disappear in tadpoles at about stage 40. The results strongly suggest that UV irradiation under the conditions used here totally eliminated germline cells from the irradiated animals.
In Vitro Control of the Embryonic Form of Xenopus laevis by Activin A: Time and Dose‐Dependent Inducing Properties of Activin‐Treated Ectoderm
Authors: Ariizumi Takashi , Asashima Makoto 
Published: January 2005

The inducing properties of activin‐treated ectoderm of Xenopus laevis were examined by the preculture and sandwich culture methods. Presumptive ectodermal sheets of the late blastula were treated with 10–100 ng/ml of activin A and precultured for 0–7 hr in Steinberg's solution. They were then sandwiched between two sheets of ectoderm from other late blastulae. Ectoderm precultured for a short term induced trunk‐tail structures, whereas that precultured for a long term induced head structures in addition to trunk‐tail structures. These time‐dependent changes in inducing properties occurred more rapidly when the concentration of activin A was higher. These results suggest that the activin‐treated ectoderm functioned as a “head organizer” or “trunk‐tail organizer” depending upon the concentration of activin A and the duration of preculture.To trace the cell lineage of the sandwich explants, activin‐treated ectoderm labeled with fluorescein‐dextran‐amine (FDA) was used in this study. The explants sandwiching the long term‐precultured ectoderm formed head structures equipped with non‐labeled neural tissues (brain and eye) as well as FDA‐labeled mesodermal tissues. These results suggest that the activin‐treated ectoderm mainly differentiates into mesodermal tissues and induces neural tissues as the organizer does in normal development.
Orbital ectopic glial tissue in relation to medial rectus: a rare entity
Authors: Ghose Supriyo , Balasubramaniam Sankarapuram T , Mahindrakar Avinash , Sharma Vidushi , Sen Seema , Sarkar Chitra , Chhabra Manpreet Singh 
Published: January 2005

AbstractHeterotopic brain tissue is a rare entity and it is rarer still in the orbit. There have been very few case reports of orbital ectopic glial tissue. The case is described herein of a 3‐month‐old baby presenting with an orbital glial hamartoma inseparable from the medial rectus muscle. The diagnosis was based on the histopathological features and a positive GFAP stain. The features of this case and the previously reported cases are discussed.