bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Changing Pattern of the Cell Cycle during the First Two Cleavage Divisions of the Mouse
Authors: DOMON MASAHARU 
Published: January 2005

The cell cycles of the early cleavage stages of the mouse were analyzed by examining Feulgen‐stained ova. The period from ovulation to the completion of second cleavage division was investigated. The ova donors were C57BL/6 × DBA/2 female mice, which were hormonally superovulated. To estimate the durations of DNA synthesis and mitotic phases of the cleavage divisions, the ova were pooled into culture medium, and as a function of time, aliquots were removed from the batch of pooled ova. The ova specimens were Feulgen‐stained and classified as the ova nuclei in G1, S, G2 or mitosis by use of a cytophotometric technique and then the durations of these phases were determined by probit analysis.The pronuclear stage had a generation time of 11 hr, with a G1 phase of 6 hr and a short S phase of 1.7 hr. In contrast the two‐cell stage had a generation time of 18 hr, with a G1 phase of 2 hr and an S phase of 3 hr. The duration of cleavage division also changed; the first cleavage division spanned 3 hr while the second spanned 1 hr.
Graph‐Theoretical Analysis of Cleavage Pattern: Graph Developmental System and Its Application to Cleavage Pattern of Ascidian Egg
Authors: DOI HIROFUMI 
Published: January 2005

The skeletal structure of the embryo is represented by the graph. In the graph, the cells and the connectivities between the cells are reduced to the nodes and edges, respectively. Along cleavage history, the series of graphs is obtained. In this paper I propose a new graph developmental system(GDS) which develops the series of graphs. And I represent and analyze the cleavage pattern of the ascidian egg by GDS. In order to represent it by GDS, at first, the connectivities between the cells are labeled according to the developments of the connectivities at the next time step, and next the cells are labeled. But there are two ways of labeling the cells, then two types of GDS are defined: (1) to label according to the pattern of the connectivities of their descendant cells after two time steps (G‐GDS), (2) to label according to the cell fates (C‐GDS). The C‐GDS of the ascidian egg produces 16 cleavage patterns at 64‐cell stage non‐deterministically. If some labels are distinguished at 16‐cell stage, the C‐GDS becomes deterministic at 64‐cell stage.GDS will be useful to simulate morphogenesis by the computer graphics.
Germ Layer Interactions in Pattern Formation of Amphibian Mesoderm during Primary Embryonic Induction
Authors: SUZUKI AKIO S. , MIFUNE YURIKO , KANÉDA TERUO 
Published: January 2005

Mesodermal differentiation of dorsal marginal zone (DMZ) before and after invagination was analyzed by a series of combination experiments with different kinds of ectoderm.Lower DMZ of early gastrula didn't show any axial‐mesoderm (notochord and somitic mesoderm) but lateral mesoderm (mesenchyme, mesothelium, or blood cells) in combinant with non‐competent ventral ectoderm, while combinant with competent ectoderm was found to have well‐differentiated axial‐mesoderm with deutero‐spinocaudal neurals. The axial‐mesoderms have origin in the ectoderm. Uninvaginated DMZ of middle gastrula also showed difference in mesodermal differentiation between competent and non‐competent ectoderms; axial‐mesoderm differentiation was much better in competent than in non‐competent. The axial‐mesoderm originated from the uninvaginated DMZ. Archenteron roof of late gastrula showed regional difference in mesodermal differentiation in both combinants with competent and non‐competent. The present study further demonstrated that there was regionality in promoting effect of induced neurectoderm on axial‐mesoderm differentiation of invaginated archenteron roof.The present experiments suggest that the cranio‐caudal and dorso‐ventral axis formations of amphibian mesoderm are finally determined by sequential and reciprocal interactions between the mesodermal anlage and the overlying ectoderm. It should be also shown that lower DMZ acts to trigger a series of the sequential interactions during primary embryonic induction.
Ammonia Release by Chum Salmon Eggs at the Initiation of Their Embryonic Development
Authors: YAMAMOTO TADASHI S. 
Published: January 2005

We have found that inseminated eggs of the chum salmon, Oncorhynchus keta, actively release alkaline substances when they have been stimulated by deionized water; the pH of the egg suspension prepared in the non‐buffered Salmon‐Ringer solution shifts within at least 1.3 pH units. The nesslerization method and an ammonia gas sensitive electrode measurement reveal that the alkalization of the suspension is partly due to the efflux of ammonia from the stimulated eggs. The increase in the intracellular ammonia level leading to the alkalization of ooplasm may occur at an early stage of the embryonic development. Since the ammonia release is observed also in the eggs stimulated parthenogenetically by deionized water, it can be inferred that the stimulation of the egg triggers a reaction which increases the ammonia level in the ooplasm.The environmental medium of stimulated eggs contains fairly large amounts of organic compounds. Its UV spectrum shows a peak at 249 nm; the position of the absorption maximum corresponds to that of inosine monophosphate (IMP). This fact suggests that IMP is one of the components of the organic compounds. The presence of IMP in the medium is also shown by thin layer chromatography. The medium contains monosaccharides and peptides. We have explained these results by postulating that an abrupt change in the activity of adenylate deaminase which catalyzes the conversion of adenosine monophosphate to ammonia and IMP occurs at the initiation of the embryonic development in the chum salmon egg.
Isolation of an Insulin‐Responsive Preadipose Cell Line and a Mammary Tumor Virus‐Producing, Dome‐Forming Epithelial Cell Line from a Mouse Mammary Tumor
Authors: ENAMI JUMPEI , ENAMI SONOKO , KOGA MUTUYOSI 
Published: January 2005

Two functional tissue culture cell lines, MTD and MTF cell lines, have been isolated from a mouse mammary tumor. MTD cells are epithelial and retain the ability to transport fluid leading to the formation of three‐dimensional fluid‐filled multicellular structures called “domes” or “hemicysts”. Another property of MTD cells is the production of murine mammary tumor virus (MTV). Release of MTV into the culture medium was verified by immunological, electrophoretic and enzymatic analyses. Addition of dexamethasone in the culture medium enhanced both the formation of domes and the production of MTV. Thus, MTD cells retain the morphological and functional properties of the original mammary tumor cells.MTF cells show the fibroblastic morphology in subconfluent cultures. After reaching confluence, however, these cells gradually accumulated triglycerides in the cytoplasm and eventually assumed the morphology of fat cells. This adipose conversion was greatly enhanced by the presence of insulin in the culture medium. The morphological resemblance of adipose‐converted MTF cells to the mammary fat cells suggests that the MTF cell line was derived from the mammary fat pad stroma. These functional cell lines will be useful to study cell differentiation as well as cell‐to‐cell interactions in the mammary gland.
Protein Synthetic Activities during Spermiogenesis in the Sea Urchin: An high Resolution Autoradiographic Study of 3H‐Leucine Incorporation
Authors: NICOTRA ANTONIETTA , ARIZZI MARIO , GALLO PATRIZIA VALENTINA 
Published: January 2005

Protein synthetic activity has been studied during spermiogenesis of Paracentrotus lividus by high‐resolution autoradiography using 3H‐leucine as a labeled precursor. Under the adopted experimental conditions 3H‐leucine is incorporated during the whole spermiogenesis period. The early spermatid is the most active stage and it shows labeling over the nucleus, the cytosol and the mitochondria. Nuclear 3H‐leucine incorporation progressively decreases as spermiogenesis proceeds. Cytosol labeling shows similar values at early and intermediate spermatid and it undergoes a considerable decreases at late spermatid. Mitochondrial grain density increases from early to intermediate spermatid and it remains almost constant at late spermatid.Our results are compared with the data reported for other animal groups and possible functions of the observed protein synthesis are discussed.
DNA Replication in Permeabilized Cells of Sea Urchin Embryos
Authors: MORIOKA MIZUE , SHIMADA HIRAKU 
Published: January 2005

For study of the regulation of DNA replication in sea urchin embryos during the early stages of development, an embryonic cell system that was permeable to exogenously supplied nucleotides was established. Embryos were permeabilized by incubating them in hypotonic buffer containing 0.3 M glucose. The permeabilized embryonic cells maintained their morphological integrity, and synthesized DNA when supplied with exogenous dNTPs.DNA synthesis in these permeabilized embryonic cells required the presence of ATP and three other deoxyribonucleoside triphosphates in addition to labeled dTTP. DNA synthesis was almost completely inhibited by N‐ethylmaleimide, and proceeded in a discontinuous fashion. Only cells permeabilized during the S phase could incorporate nucleoside triphosphates into DNA: cells permeabilized during other phases did not synthesize DNA. During a 60 min‐incubation period, over 10% of the genomic DNA was replicated under the experimental conditions used.
Cell to Cell Adhesion Systems in Xenopus laevis, the South African Clawed Frog I. Detection of Ca2+ Dependent and Independent Adhesion Systems in Adult and Embryonic Cells
Authors: NOMURA K. , UCHIDA M. , KAGEURA H. , SHIOKAWA K. , YAMANA K. 
Published: January 2005

The reaggregation kinetics of frog (Xenopus laevis) cells prepared using several different dissociation procedures were monitored. Two distinct modes of cell adhesion were revealed, one mediated by Ca2+ dependent cell‐cell adhesion system (CDS) and the other mediated by Ca2+ independent one (CIDS).CDS was detected in frog embryonic (two‐cell stage to neurula) cells and in cells of epithelial cell lines (A6 and A8), while CIDS was detected only in A6 cells. Frog CDS was resistant to 0.01% tryptic digestion in the presence of 1 mM Ca2+ and CIDS was resistant to dilute (0.0001%) tryptic digestion. Cells with both mechanisms were prepared by dissociation with 1 mM EDTA and both mechanisms were absent in cells dissociated with 0.01% trypsin and 1 mM EDTA. Frog CDS and CIDS functioned in a temperature dependent and independent manner, respectively. Properties of frog CDS and CIDS revealed in this study were the same as those of mammalian or avian CDS and CIDS, respectively. Frog cells with CDS cross‐adhered to mammalian epithelial (F9) cells but not to fibroblastic (V79) cells Ca2+ dependently. Monoclonal antibody ECCD‐1 raised against mouse epithelial CDS blocked aggregation of frog A8 cells.These results suggest the similarity between frog CDS and mammalian epithelial type CDS.
Prospective Neural Areas and Their Morphogenetic Movements during Neural Plate Formation of Xenopus Embryos. I. Development of Vegetal Half Embryos and Chimera Embryos
Authors: SUZUKI AKIO S. , HARADA KEIICHI 
Published: January 2005

Development of animal cap‐less Xenopus gastrulae was examined. In vegetal halves from which the animal cap was removed 0.6 mm above the blastopore, an apparently normal array of craniocaudal structures developed. Histological examination showed differentiation of central nervous system (CNS) structures in the cap‐less embryos, but differentiation of sensory organs, such as a lens and ear vesicle in only a few embryos. Only the dorsal midline of the embryos was covered with epidermis, and its lateral‐ventral areas consisted of bare endoderm and mesoderm. The development of animal cap was also investigated by exchanging the animal cap of X. laevis embryos with that of X. borealis embryos, which can be distinguished by quinacrine fluorescence staining. The central nervous system of chimera embryos consisted mainly of X. laevis cells stained homogeneously with quinacrine but a small number of punctately‐stained X. borealis cells was in the anterior tip of the forebrain. Cells of the lens and ear vesicle were punctately stained. More than two‐thirds of the epidermal area consisted of punctately‐stained cells and only the dorsal midline of the posterior head‐ and trunk‐epidermis consisted of homogeneously‐stained cells.Areas of the prospective central nervous system and their movement during embryogenesis of Xenopus are discussed.
Shift in Steroidogenesis in the Ovarian Follicles of the Goldfish (Carassius auratus) during Gonadotropin‐Induced Oocyte Maturation
Authors: NAGAHAMA YOSHITAKA , GOETZ FREDERICK W. , TAN JOSEFA D. 
Published: January 2005

Both partially purified chum salmon gonadotropin and 17α‐hydroxyprogesterone stimulated in vitro production of testosterone by postvitellogenic follicles of goldfish (Carassius auratus). Chum salmon gonadotropin further enhanced the conversion of exogenously supplied 17α‐hydroxyprogesterone to 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one. The increased medium concentrations of 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one were associated with the induction of final oocyte maturation.The capacity of postvitellogenic follicles to produce steroids in response to exogenous 17α‐hydroxyprogesterone was examined in females at various stages of final oocyte maturation following the administration of human chorionic gonadotropin in vivo combined with elevation of holding temperature. The maximum production of testosterone in response to 17α‐hydroxyprogesterone was obtained in follicles from initial controls. In contrast, 17α 20β‐diOHprog production was very low in initial controls and markedly increased during oocyte maturation (3–6 hr following injection), followed by a significant decrease in follicles collected at 15 hr. Estradiol‐17β production by the follicles was very low at any stages of gonadotropin‐induced oocyte maturation. These results suggest that gonadotropin‐induced shift in the biosynthetic pathway in the follicle from the secretion of predominantly testosterone to 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one secretion is a prerequisite step for the induction of oocyte maturation in goldfish.
Direct Evidence for the Presence of Germ Cell Determinant in Vegetal Pole Cytoplasm of Xenopus laevis and in a Subcellular Fraction of It
Authors: IKENISHI KOHJI , NAKAZATO SAKIKO , OKUDA TAKASHI 
Published: January 2005

To test for the presence of germ cell determinant in Xenopus embryos, vegetal pole cytoplasm containing the “germ plasm”, or a subcellular fraction of it, was microinjected into single somatic blastomeres isolated from 32‐cell embryos. Injected or non‐injected (control) blastomeres were cultured in 3H‐thymidine until normal control embryos reached the neurula stage. The labeled explants were then implanted into unlabeled host neurulae, which were allowed to develop to the tadpole stage. Labeled PGCs of explant origin in the genital ridges of the experimental tadpoles were examined by autoradiography.Isolated blastomeres were injected with vegetal pole cytoplasm of 32‐cell embryos or with a 20,000 g pellet made from vegetal pole cytoplasm of 2‐cell embryos. Labeled PGCs were found in 7.6% and 2.3% of the experimental tadpoles, respectively. No labeled PGCs were found in the control tadpoles, except for one tadpole in the first experiment. These results strongly suggest that the vegetal pole cytoplasm and its subcellular fractions act as germ cell determinant.
Development of Fertilized Starfish Eggs in Which Cytokinesis is Prevented by Iturin A–2
Authors: TSUCHIMORI NOBORU , MIYASHIRO SHIGEYOSHI , TSUJI TOMOKO , KIDA TAKAO , SHIBAI HIROSHIRO , IKEGAMI SUSUMU 
Published: January 2005

Iturin A–2, a cyclic peptide obtained from cultures of Bacillus subtilis inhibited cell division but not nuclear divisions of fertilized eggs of the starfish Asterina pectinifera, resulting in the formation of non‐cleaving eggs containing all the embryonic nuclei in a common cytoplasm. Fertilized eggs in which cleavage was prevented by iturin A–2 (50μg/ml) synthesized DNA, RNA and protein at comparable rates to those of normal embryos up to the onset of blastulation. In single‐cell embryos, however, elevation of the level of transcription, which is a characteristic marker of blastulation, did not take place and the chromatin masses eventually dispersed in the cytoplasm.Treatment of oocytes with iturin A–2 (50μg/ml) resulted in loss of their response to the maturation‐inducing substance 1‐methyladenine, whose receptors are located in the cell membrane or other components of the oocyte cortex. Furthermore, iturin A–2 bound to oocyte cortices quantitatively, suggesting that its site of action is the cortices of oocytes and eggs, and that its arrest of cleavage of fertilized eggs is due to loss of the ability of the cell membrane to form a cleavage furrow.
In Vitro Induction of Starfish Oocyte Maturation by Cysteine Alkylesters
Authors: MITA MASATOSHI , UETA NOBUO , NAGAHAMA YOSHITAKA 
Published: January 2005

The effect of various disulfide‐reducing agents including cysteine and its alkylesters on the induction of germinal vesicle breakdown (GVBD) in starfish (Asterina pectinifera) oocytes was investigated in vitro. Although cysteine did not induce GVBD, its alkylesters were effective. Cysteine alkylesters significantly mimicked the effect of 1‐methyladenine (1‐MeAde), the naturally occurring maturation‐inducing hormone of starfish, on oocyte maturation. However, the effective concentrations and pH optimum for stimulation of oocyte maturation varied between 1‐MeAde and the cysteine alkylesters. By comparing pKa values of the disulfide‐reducing agents to pH of the medium, it is suggested that the redox potential of a disulfide‐reducing agent is an important indicator its ability to induce oocyte maturation.With the use of fluorescent probes for thiol groups, it was shown that the fluorescence in oocyte cortices increased within 5 min after administration of 1‐MeAde. The fluorescence intensity in the cortices also increased after treatment with cysteine and its alkylesters, although the intensity was much stronger with the latter. Furthermore, both 1‐MeAde and the disulfide‐reducing agents were suggested to cause reduction of thiol groups within the plasma membrane as opposed to those on the external and internal surfaces. Thus, it is suggested that disulfide‐reducing agents and 1‐MeAde induce starfish oocyte maturation by changing the redox state of the thiol groups located within the oocyte plasma membrane.
Introduction and Expression of Recombinant β‐Galactosidase Genes in Cleavage Stage Mouse Embryos
Authors: UENO KENJU , HIRAMOTO YUKIO , HAYASHI SHIGEO , KONDOH HISATO 
Published: January 2005

In an attempt to study gene regulation in very early stages of mouse embryogenesis, we injected genes constructed by joining the coding sequence of the bacterial β‐galactosidase gene to four different animal gene enhancers/promoters and to poly (A) signals, and examined the gene expression in cleavage stage embryos.With appropriate injection volumes for each embryonic stage, ranging from 0.2 to 1.3 pl, the majority of the injected embryos underwent at least one further cleavage. Expression of injected genes, which occurred transiently after injection, required the promoter sequences but without much distinction of the source of enhancer/promoter complexes. This result was in a sharp contrast to transfection of mouse cell lines where the recombinant genes were variably expressed reflecting differential enhancer effects.By injection at the 1‐cell stage, expression of injected genes was low while the expression by injection at the 2‐cell or later stages was several fold higher, which may correlate with the fact that most zygotic gene expression begins after the 2‐cell stage. The low expression at the 1‐cell stage was augmented by the conditions causing clea***age arrest such as inhibition of DNA synthesis with aphidicolin.
Expression Pattern of E‐ and P‐Cadherin in Mouse Embryos and Uteri during the Periimplantation Period
Authors: Kadokawa Yuzo , Fuketa Izumi , Nose Akinao , Takeichi Masatoshi , Nakatsuji Norio 
Published: January 2005

Periimplantation mouse embryos and uterine tissues were examined by means of immunohistochemistry for their expression of the Ca2+ dependent cell‐cell adhesion molecules, E‐ and P‐cadherin. E‐cadherin was detected in all embryonic cells during periimplantation stages, and also detected in the uterine epithelium. When blastocysts attached to the uterine epithelium, E‐cadherin was detected at implantation sites between the mural trophectoderm and the uterine epithelium on 5 day of pregnancy. P‐cadherin was first detected in the mural trophectoderm on 4.5‐day blastocysts, and then detected in the ectoplacental cone, giant cells and visceral endoderm from 5.5 day.P‐cadherin was also detected in the maternal uterine decidual cells from 5.5 day. After degeneration of uterine epithelial cells, giant cells make direct contact with uterine decidual cells, and P‐cadherin was detected at contact sites between these cells.Thus, the complicated process of implantation seems to be supported by temporal and spatial expression of the multiple classes of cadherins.
Concanavalin A Acts as a Factor in Establishing the Dorso‐Ventral Gradient in the Ventral Mesoderm of Newt Gastrula Embryos1
Authors: Diaz Maria R. M. , Takahashi Tadashi C. , Takeshima Kazuhito , Takata Kenzo 
Published: January 2005

Con A induced dorsal differentiation in the ventral mesoderm of Cynops gastrula embryo. This process apparently requires a certain amount of Con A to be internalized as supported by the following evidence: 1) Oligomannose‐type oligosaccharide, a potent inhibitor of Con A, considerably inhibited dorsalization of ventral mesoderm by Con A. The incorporation of 125I‐Con A into the ventral mesoderm was greatly inhibited by this sugar. 2) Sepharose‐immobilized Con A did not dorsalize the ventral mesoderm. Con A‐induced dorsalization was found to be concentration‐dependent.Microautoradiograms of 125I‐Con A‐treated ventral mesoderm suggest that the target site (some receptor molecules) of Con A exists inside the cell.Con A is the first pure substance reported to mimic the two properties of the organizer—neural induction of the competent ectoderm and dorsalization of the ventral mesoderm. In neural induction, Con A acts on the cell surface, while Con A apparently needs to be internalized to trigger dorsal differentiation. Interestingly, Con A‐dorsalized ventral mesoderm acquired the neural inducing function of the organizer within the early phase of dorsalization.
Epithelial Metaplasia Induced Amnionic Ectoderm by the Dermis of Chicken Embryos1
Authors: Mizuno Takeo , Kitamura Kunio , Saito Miwako , Tanemura Shigeji 
Published: January 2005

Amnionic ectoderm of 6.8‐day chicken embryos was associated with 6.8‐day dorsal dermis or 13–15‐day scale dermis and cultured on host chorio‐allantoic membrane for 8 days. The amnionic ectoderm, recombined and cultured with the dorsal dermis, developed feather filaments consisted of a feather root, a horny sheath, and barb ridges. With several feather keratin‐specific monoclonal antibodies (4E12 and 1F3), these structures in the induced feather filaments were shown to express feather‐specific keratin antigens.The amnionic ectoderm, recombined and cultured with the shank dermis, became stratified squamous and developed scales. The scales were keratinized and their surface reacted only weakly with the monoclonal antibodies specific for the feather keratins. However, 1F3 reacted with two polypeptides in the cytoskeletal fraction of the scales, but not of the feather filaments.The results confirm our previous findings from in vitro experiments with the proamnionic ectoderm (Mizuno, 1970, 1972).