bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inactivation and deficiency of core proteins of photosystems I and II caused by genetical phylloquinone and plastoquinone deficiency but retained lamellar structure in a T‐DNA mutant of Arabidopsis
Authors: Shimada Hiroshi , Ohno Ryoichi , Shibata Masaru , Ikegami Isamu , Onai Kiyoshi , Ohto Masa‐aki , Takamiya Ken‐ichiro 
Published: February 2005

SummaryPhylloquinone, a substituted 1,4‐naphthoquinone with an 18‐carbon‐saturated phytyl tail, functions as a bound one‐electron carrier cofactor at the A1 site of photosystem I (PSI). A Feldmann tag line mutant, no. 2755 (designated as abc4 hereafter), showed pale‐green young leaves and white old leaves. The mutated nuclear gene encoded 1,4‐dihydroxy‐2‐naphtoic acid phytyltransferase, an enzyme of phylloquinone biosynthesis, and high‐performance liquid chromatography analysis revealed that the abc4 mutant contained no phylloquinone, and only about 3% plastoquinone. Photooxidation of P700 of PSI in the abc4 mutant was not observed, and reduced‐versus‐oxidized difference spectroscopy indicated that the abc4 mutant had no P700. The maximum quantum yield of photosystem II (PSII) in the abc4 mutant was much decreased, and the electron transfer from PSII to PSI in the abc4 mutant did not occur. For the pale‐green leaves of the abc4 mutant plant, the ultrastructure of the chloroplasts was almost the same as that of the wild‐type plant. However, the chloroplasts in the albino leaves of the mutant were smaller and had a lot of grana thylakoids and few stroma thylakoids. The amounts of PSI and PSII core subunits in the abc4 mutant were significantly decreased compared with those in the wild type. These results suggested that a deficiency of phylloquinone in PSI caused the abolishment of PSI and a partial defect of PSII due to a significant decrease of plastoquinone, but did not influence the ultrastructure of the chloroplasts in young leaves.
THE MITOTIC APPARATUS ISOLATED IN GLYCEROL‐CONTAINING MEDIUM
Authors: SAKAI HIKOICHI , KURIYAMA RYOKO 
Published: January 2005

The mitotic apparatus of the sea urchin egg was isolated at 30°C in an isolation medium containing glycerol which is known to stabilize microtubules. After isolation in the 1 m glycerol‐isolation medium, the mitotic apparatus was stabilized on addition of glycerol to a final concentration of 3 to 4 m. Without the addition, the chromosomes were disjoined from the spindle and the interzonal region between separating chromosomes was fragile resulting in separation of half spindles. Lowering the temperature of the isolation medium to 20°C or below, the isolation procedure allowed to isolate spindles. The isolated spindle behaved in a manner similar to the mitotic apparatus on the effect of glycerol concentration.The glycerol‐mitotic apparatus contained tubulin which was extractable with the isolation medium containing Ca ions or an organic mercurial. Tubulin was also extracted upon lowering the temperature to 0°C in the presence of GTP. Addition of KCl to a final concentration of 0.6 m immediately dispersed the mitotic apparatus. The extract revealed a colchicine binding of 0.001 mole per 105,000 ×g of protein. The colchicine binding complex was found to have a molecular weight of 105,000. The DEAE Sephadex column chromatography of the KCl extract allowed to elute tubulin fraction which bound 0.1 mole colchicine per 105,000 ×g of protein. The mitotic apparatus tubulin was shown to contain α and β subunits with mobilities quite identical with those of brain tubulin subunits. The molecular weights of the α and β subunits were 55,000 ± 1,000 and 51,000 ± 1,000, respectively.
HISTOCHEMICAL AND ELECTRON MICROSCOPIC OBSERVATIONS ON THE STEROID HORMONE‐SECRETING CELLS IN THE TESTIS OF THE JAPANESE RED‐BELLIED NEWT, CYNOPS PYRRHOGASTER PYRRHOGASTER
Authors: IMAI KATSUTOSHI , TANAKA SHIGEYASU 
Published: January 2005

The testis of the Japanese red‐bellied newt, Cynops pyrrhogaster pyrrhogaster, caught in the middle of May was investigated in order to demonstrate the presence of steroid hormone (SH)‐secreting cells, by means of histochemical and electron microscopic techniques. The newt testis is divided into two main parts of spermatogenetic stages. The anterior part is immature and consists of many seminal cysts containing spermatogonia and spermatocytes. The posterior part is mature and made up of many cysts containing mature spermatozoa and glandular tissue.Histochemical studies revealed Δ5‐3β‐hydroxysteroid dehydrogenase (Δ5‐3β‐HSD) activity in the pericystic cells of the mature part, weak in those before spermiation, then gradually becoming more intense in the pericystic cells just after spermiation. Activity was most pronounced in the outer layer of cells of the glandular tissue which originate from the pericystic cells. In contrast to this, the Δ5‐3β‐HSD reaction was entirely negative in the pericystic cells of the immature part, the Sertoli cells, and the inner cells of the glandular tissue originating from the Sertoli cells.Electron microscopic observation of the pericystic cells and glandular tissue gave further information on the histochemical features. The pericystic cells in the immature part are fibroblast‐like cells. The cell organelles of these cells are poorly developed except for rough‐surfaced endoplasmic reticulum and rod‐shaped mitochondria. In the mature part, the fibroblast‐like cells are transformed into cells characteristic of SH‐secreting cells. In the cytoplasm, the amount of smooth‐surfaced endoplasmic reticulum increases and typical globular mitochondria with tubular cristae take the place of the rod‐shaped mitochondria. In addition, a number of lipid droplets and lipofuscin granules appear. Most of the fine structures of the outer layer of the cells of the glandular tissue were found to be similar in appearance to those of the SH‐secreting cells in mammals and other vertebrates. These results strongly suggest that, as in the other urodeles, the SH‐secreting cells in the testis of the Japanese red‐bellied newt are the pericystic cells in the mature part and in the outer layer of cells of the glandular tissue.
Transmission of Homoiogenetic Induction in Presumptive Ectoderm of Newt Embryo
Authors: KURIHARA KAZUSHIGE , SASAKI NAOI 
Published: January 2005

Using newt, Cynops pyrrhogaster, embryos, the production and/or transmission of a homoiogenetic effect of the induction within a presumptive ectoderm was investigated. The primary inductor was the swimbladder of a crucian carp, Caracius auratus. In the first experiment, a piece of presumptive ectoderm was isolated from an early gastrula and one‐third of its inner surface was placed in contact with the swimbladder for 30 min. After removal of the inductor, the ectodermal piece was allowed to stand by itself for several hours (pre‐cultivation), and then it was divided into three parts of equal size, i.e. the end that had been placed in contact with the swimbladder (P1), the next middle (P2) and the end part (P3).The tissues produced in each part were examined after 10 days' cultivation in Holtfreter's solution. The induction was evoked not only in P1, but also in P2 and P3 which had been free from the inductor. The incidences of tissue differentiation in P2 and P3 increased with the lapse of the pre‐cultivation time, and the rise in P3 came after P2. These results suggested that the mesodermal tissues in the parts not placed in contact with the swimbladder (P2 and P3) were evoked by the homoiogenetic stimulus which came from P1 and P2, respectively.In the next experiment, P2 of the ectodermal piece was substituted by an aged ectoderm which had lost its primary competence. In this system, the mesodermal induction was not evoked in P3. This suggested that the production of the homoiogenetic activity of the ectoderm might be associated with its competenece.
Localization of Acrosomal Proteinase after Vesculation of the Acrosome
Authors: SAKAI YASUHIRO , YASUDA KENJIRO 
Published: January 2005

The freshly ovulated egg is covered by the zona pellucida and follicular‐cell layer. The former is reported to dissolved by acrosomal proteinase and the latter may be dispersed by hyaluronidase. If these two enzymes have different targets, two possibilities can be taken into consideration concerning the timing of release of the two enzymes from the acrosome.Since hyaluronidase is considered to be released immediately after the acrosomal reaction at the follicular‐cell layer, this work was undertaken to examine the timing of release of acrosomal proteinase after vesiculation of the acrosome, by demonstrating the site of the proteinase histochemically. The results indicated that the acrosomal proteinase disappeared immediately after vesiculation of the acrosome. This result suggests that spermatozoa that show vesiculation of the acrosome in the follicular‐cell layer probably lose acrosomal proteinase in this layer. Thus the spermatozoon probably does not attack the follicular‐cell layer and zona pellucida, one by one by release sequential of hyaluronidase and acrosomal proteinase.
Cellular Basis of Neuralization of Induced Neurectoderm in Amphibian Embryogenesis: Changes of Cell Shape, Cell Size, and Cytodifferentiation of the Neurectoderm after Neural Induction
Authors: SUZUKI AKIO S. , MIKI KAYOKO 
Published: January 2005

Cellular alterations of the neurectoderm after primary embryonic induction were examined by measuring several indices of shape, volume, and cytodifferentiation of the neurectodermal cells of Cynops embryos during gastrulation and early neurulation.Results showed that cellular alterations occurs just after the 18 hr embryo stage (stage 13b). The thickness of the neurectoderm layer decreases like that of the epidermal ectoderm during early and middle gastrulation. After the 18 hr embryo stage, however, the neurectoderm thickens, mainly due to formation of columnar cells. Measurement of cell volume indicates that the neurectoderm of the early and middle gastrulae consists of a cell population of heterogeneous size. The heterogeneity diminishes sharply after the 18 hr embryo stage and the neural plate of the 36 hr embryo (stage 18) consists of cells of homogeneous size.Stages before the 12 hr embryo (stage 12b) and after the 18 hr embryo (stage 13b) also showed differed in cell adhesion to the culture flask and in cytodifferentiating potency. Single cells dissociated from the neurectoderm of 18 hr embryos could adhere to the substratum and differentiate into both nerve‐like cells and pigment cells. Both capacities increase during further development.These results are discussed in relation to the neuralizing determination of neurectoderm after primary embryonic induction.
In Vitro Growth of Rat Blastocyst under the Effect of Azathioprine
Authors: FEIN AMOS , TODER VLADIMIR , NEBEL LASLO 
Published: January 2005

Rat blastocysts were isolated from the uterus on the 5th day after fertilization and set in culture. The effect of azathioprine (Imuran) on the blastocyst's development and on the early trophoblastic differentiation in vitro was investigated. Azathioprine, added to the medium of the blastocyst culture at various concentrations, dose dependently arrested development and had definite cytotoxic effect. In order to study the mechanism of action, a minimal dose of 5 μg/ml, which allowed the survival of about 60% of the blastocysts, was added to the medium after 48 hr of culturing. Under the effect of the substance the area of the spreading blastocyst cells was significantly restricted.It was found, by autoradiographic methods, that the azathioprine affects the development by restraining DNA synthesis in the throphoblastic cells. Concomitantly RNA synthesis was inhibited and protein synthesis was reduced. The observations indicate, that the impairment of the in vitro differentiation of the blastocysts can be a result of the intracellular inhibitory action of the substance.
Effect on Inhibition of Micromere Segregation on the Mitotic Pattern in the Sea Urchin Embryo
Authors: FILOSA SILVANA , ANDREUCCETTI PIERO , PARISI ELIO , MONROY ALBERTO 
Published: January 2005

Detergent treatment of sea urchin eggs at the mid 4‐cell stage results in prevention of micromere segregation at the fourth cleavage. In these embryos not only the formation of the primary mesenchyme is suppressed, but synchrony of cell division, which is the rule during the first four cleavage cycles, continues for several cycles after the 16‐cell stage while the typical mitotic phase wave that sets in after micromere segregation is abolished.These results support the hypothesis that micromeres act as coordinators of the mitotic activity of the embryo.
Use of Hybrids between Xenopus laevis and Xenopus borealis in Chimera Formation: Dorsalization of Ventral Cells
Authors: KOGA M. , KAGEURA H. , YAMANA K. 
Published: January 2005

The combination of Xenopus borealis and X. laevis provides an excellent cell marking system. The potential availability of this system for chimera formation has also been suggested. However, eggs and early embryos of these species differ in size and the fusion of blastomeres of different sizez results in some disturbance in arrangement of blastomeres of a chimera. This disturbance was avoided by use of embryos from X. laevis eggs fertilized with X. borealis sperm, instead of X. borealis embryos. The cells of these hybrids could also be distinguished from the cells of X. laevis.The fate of animal ventral cells placed in the dorsal region was followed by making a chimera by fusing a right lateral half of an 8‐cell X. laevis embryo with that of an 8‐cell hybrid embryo. The animal ventral cells in the “dorsal” region were found to become “dorsalized”, giving rise to a lateral half of dorsal axial structures. This observation explains a previous finding that the replacement of dorsal cells by ventral ones had no effect on embryogenesis in a composite embryo.
Direct Evidence for in vitro Binding of a Lectin from Arachis hypogea to Endoblastic Primordial Germ Cells of Amphibian Embryos
Authors: GIPOULOUX JEAN‐DANIEL , DELBOS MARTINE , GIPOULOUX SIMONE 
Published: January 2005

Peanut agglutinin was previously shown to have a specific affinity for primordial germ cells (PGCs) from anuran amphibian embryos. For separation of these cells from endoblastic ones, suspensions of dissociated cells from the endoblastic masses of Xenopus laevis and Rana dalmatina embryos were treated with peanut agglutinin. This treatment resulted in agglutination of a small number of cells, and these aggregates were separated from unaggregated single cells by gravity in 50% calf serum medium. Histological and ultrastructural analysis of numerous sections of the aggregated cells showed that they contained the germinal plasm characteristic of PGCs. The specificity of the PGCs agglutination was confirmed by disocciation of the aggregates with 0, 2 M D‐galactose solution.This embryonic cellular population of PGCs should be useful in further in vitro experiments.
Viable Chimeras between Embryonal Carcinoma Cells and Mouse Embryos: Comparison of Aggregation and Injection Methods
Authors: HANAOKA KAZUNORI , HAYASAKA MICHIKO , NOGUCHI TAKEHIKO , KATO YOSHIHIRO 
Published: January 2005

An embryonal carcinoma (EC) cell line having the ability to form chimeric mice was isolated from embryo‐derived teratocarcinomas experimentally induced in BALB/cCrSlc mice. This EC cell line, B242 g, was one of the 5 EC cell lines pre‐selected based on the ability to incorporate into blastocysts by means of aggregating with 8‐cell mouse embryos.Using the B242g EC cells, the effectiveness of producing chimeras was compared between two currently available techniques, aggregation and injection, by examining chimerism of the midgestationally recovered conceptuses and live‐born mice. The present result revealed that EC cells studied here were able to form chimeras more efficiently by injection as compared to aggregation method.
Growth of Notochord and Formation of Cranial and Mesencephalic Flexures in Chicken Embryo
Authors: TAKAMATSU TETSUROU , FUJITA SETSUYA 
Published: January 2005

The proliferative activity of notochordal cells, neuroepithelial cells and endodermal cells in the chicken embryo is examined during flexure formation along its long axis by using bromodeoxyuridine (BrdU)‐immunohistochemistry.White Leghorn chicken embryos, Hamburger and Hamilton stages from 9 to 15 are cumulatively labled with BrdU for 120 min and fixed with Carnoy's fluid. Serial transverse and sagittal sections are immunostained with a monoclonal anti‐BrdU antibody. The distribution of labeled and unlabeled cells is determined on various regions of the embryos.Before and during the external flexure development from state 10 to 14, the labeled cells are virtually absent at two regions; The cranial region including the floor of the prosencephalon and pharynx close to the pre‐chordal plate and the mesencephalic region comprising the mesencephalic notochord and mid‐ventral side of the mesencephalon. At stages 10 and 11, the cranial and mesencephalic flexure become apparent at the respective unlabeled regions. It is concluded that the regional differences in proliferative activity between the notochord, neural tube and endoderm play a causal role in the flexure formation of early morphogenesis in the embryo.
Expression of Embryo‐Specific Epidermal XK81 Keratin Gene in Dissociated Cells of Xenopus laevis Animal Caps Co‐cultured with Mesoderm‐Inducing Vegetal Cells
Authors: Atsuchi Yasuo , Shiokawa Koichiro 
Published: January 2005

Dissociated cells of whole embryos or their animal halves were cultured until the time when sibling embryos reached the neurula stage, and expression of genes for embryo‐specific epidermal XK81 keratin, muscle‐specific α‐actin and histone H4 was studied by Northern blot analysis. In the experiments with dissociated midblastula cells, the expression of keratin gene, but not two other genes, was found to be inhibited in animal cap cells when these cells were cultured with vegetal cells. However, in the experiments with midgastrula cells, such inhibition was not observed even when animal cap cells were co‐cultured with vegetal cells. Therefore, keratin gene expression in animal cap cells is sensitive at the midblastula stage, but resistant at the midgastrula stage, to the inhibitory activity by vegetal cells.To determine when such transition occurs, we prepared animal cap cells from embryos at different stages and co‐cultured them with vegetal cells from midblastulae. Results obtained showed that the transition takes place at the late blastula stage (stage 9). These results suggest that the transcriptional system for the embryo‐specific epidermal XK81 keratin gene is stabilized in animal cap cells prior to gastrulation, so that it is expressed autonomously, without being inhibited by contact with vegetal cells.
Possible MIS Production by Follicle Cells in Spontaneous Oocyte Maturation of the Ascidian, Halocynthia roretzi
Authors: Sakairi Kazuhiro , Shirai Hiroko 
Published: January 2005

Outer and inner follicle cell‐enclosed oocytes (oocyte complexes) of Halocynthia roretzi underwent germinal vesicle breakdown (GVBD) within 2 hr when transferred from ovaries to normal seawater of pH 8 (NSW). Extrusion of test cells (TC) into the perivitelline space and elevation of the chorion also occurred. This phenomenon was designated as spontaneous oocyte maturation.Seawater of low pH, protease inhibitors such as leupeptin or soybean trypsin inhibitor (SBTI), and calcium deficiency inhibited the spontaneous maturation only when introduced to the NSW during the first 10 minutes of incubation. GVBD‐blocked complexes underwent GVBD after addition of trypsin regardless of pH or the absence of calcium ions. The oocytes from which follicle cells were removed with glycosidase did not undergo GVBD in NSW, but addition of trypsin triggered GVBD in these defolliculated oocytes (TC oocytes). Furthermore, incubation media in which spontaneous maturation had occurred, induced GVBD in the TC oocytes. This GVBD‐inducing activity was heat‐labile and was inhibited by leupeptin.These results indicate that in the first step of the spontaneous oocyte maturation, outer and/or inner follicle cells give a signal to the oocyte itself or TC oocyte. This signal is likely to be trypsin‐like.
Induction of Mucous Metaplasia in Chick Embryonic Skin by Retinol‐Pretreated Embryonic Chick or Quail Dermal Fibroblasts through Cell‐Cell Interaction: Correlation of a Transient Increase in Retinoic Acid Receptor β mRNA in Retinol‐Treated Dermal Fibroblasts with Their Competence to Induce Epidermal Mucous Metaplasia
Authors: Obinata Akiko , Akimoto Yoshihiro , Kawamata Takashi , Hirano Hiroshi 
Published: January 2005

Epidermal mucous metaplasia of 13‐day‐old chick embryonic tarsometatarsal skin can be induced by culture in medium containing 20 μM retinol for only 8 hr and then in a chemically defined medium without retinol for 2 days. Retinol primarily affects the dermal cells, which then transform the epithelial cells into mucus‐secreting cells. In this study, we developed a system using a combination of retinol‐pretreated chick or quail dermal fibroblasts and chick skin, and showed that retinol‐pretreated quail embryonic dermal fibroblasts invaded the dermis of chick embryonic skin to beneath the epidermal basal cells within 1 day of culture and induced metaplasia, suggesting that epidermal mucous metaplasia of the skin was induced by the direct interaction of retinol‐pretreated dermal fibroblasts with the epidermal cells or by low diffusible paracrine factor produced by the fibroblasts.Increase in retinoic acid receptor β (RARβ) mRNA in dermal fibroblasts was observed after 8 hr‐treatment with retinol which preceded morphological changes induced by retinol and this increase was correlated with the competence of the dermal fibroblasts to induce epidermal mucous metaplasia. Thus some gene product(s) controlled by RARβ in dermal fibroblasts may be an essential signal for induction of epidermal mucous metaplasia.
Newly born cells in the ageing dentate gyrus display normal migration, survival and neuronal fate choice but endure retarded early maturation
Authors: Rao Muddanna S. , Hattiangady Bharathi , Abdel‐Rahman Ali , Stanley Dirk P. , Shetty Ashok K. 
Published: January 2005

AbstractAddition of new granule cells to the dentate gyrus (DG) from stem or progenitor cells declines considerably during ageing. However, potential age‐related alterations in migration, enduring survival and neuronal fate choice of newly born cells, and rate of maturation and dendritic growth of newly differentiated neurons are mostly unknown. We addressed these issues by analysing cells that are positive for 5′‐bromodeoxyuridine (BrdU), doublecortin (DCX), BrdU and DCX, and BrdU and neuron‐specific nuclear antigen (NeuN) in the DG of young adult, middle‐aged and aged F344 rats treated with daily injections of BrdU for 12 consecutive days. Analyses performed at 24 h, 10 days and 5 months after BrdU injections reveal that the extent of new cell production decreases dramatically by middle age but exhibits no change thereafter. Interestingly, fractions of newly formed cells that exhibit appropriate migration and prolonged survival, and fractions of newly born cells that differentiate into neurons, remain stable during ageing. However, in newly formed neurons of the middle‐aged and aged DG, the expression of mature neuronal marker NeuN is delayed and early dendritic growth is retarded. Thus, the presence of far fewer new granule cells in the aged DG is not due to alterations in the long term survival and phenotypic differentiation of newly generated cells but solely owing to diminished production of new cells. The results also underscore that the capability of the DG milieu to support neuronal fate choice, migration and enduring survival of newly born cells remains stable even during senescence but its ability to promote rapid neuronal maturation and dendritic growth is diminished as early as middle age.