bluuebunny/crossref_metadata_2025 huggingface dataset:
THE DIAPAUSE FACTOR FROM THE SILKWORM, BOMBYX MORI L.: PURIFICATION AND INACTIVATION EXPERIMENTS
Authors: SONOBE HARUYUKI
Published: January 2005

The diapause factor, which is responsible for the induction of èmbryonic dia pause in the silkworm (Bombyx mori L.), has been partially purified from the extract of adult heads by means of protein purification procedures, including the use of gel filtration of Sephadex, column chromatography on Dowex 1, isoelectric focusing and phenol extraction.

Two species of the diapause factor could be recognized in respect to their molecular weight. They were separated by Sephadex G‐25 and their molecular weights were estimated to be about 2,000 and 5,000 from the gel filtration results. The smaller species was purified about 90‐fold in specific activity, and its isoelectric point was determined by isoelectric focusing to be at about pH 4.5.

The biological activity of the partially purified principle could be abolished by incubation with several proteolytic enzymes (trypsin, α‐chymotrypsin and pronase), or by treatment with amino acid‐modifying reagents such as tyrosinase, N‐bromosuccinimide or 2‐hydroxy‐5‐nitrobenzyl bromide, but was not affected by incubation with neuraminidase, cyanogen bromide or photooxidation in the presence of methylene blue.
OBSERVATIONS ON SUPERNUMERARY HEAD FORMATION INDUCED BY LITHIUM CHLORIDE TREATMENT IN THE REGENERATING HYDRA, PELMATOHYDRA ROBUSTA
Authors: YASUGI SADAO
Published: January 2005

Lithium chloride treatment of hydras cut just proximal to the tentacle circle and just distal to the budding region induces a supernumerary head at the proximal cut surface. Such a supernumerary head does not appear in the normal course of regeneration. The bipolar hydra thus formed persists for several weeks and later separates to form two normal individuals. The supernumerary head is not formed at the proximal cut surface when the hydra is transected just distal to the budding zone and the distal portion is allowed to regenerate in the Li‐containing medium. LiCl has a slight inhibitory effect on the regeneration of hypostomes or tentacles when the animal is cut at the base of the hypostome.
THE LIFE CYCLE OF THE FRESHWATER COPEPOD EUCYCLOPS SERRULATUS (FISCHER) AND ITS USE IN A BIOASSAY FOR DECAPOD OVARIAN STIMULATING AND INHIBITING SUBSTANCES
Authors: ØU TAKASHI , MAEKAWA KAZUO , CALDWELL MARGARET J.
Published: January 2005

The first section of this article deals with the description of life cycle in the freshwater copepod Eucyclops serrulatus for the use of bioassay in decapod ovarian stimulating and inhibiting substance.

In the second section, the methods and results of administration of substances from the crab, Eriocheir japonicus were described. Extracts of the thoracic ganglion, brain and leg muscle of the crab added to culture of Eucyclops serrulatus which reached Stage VI of the copepodid or shortly after their moult to adulthood. The former two group of animals rapidly bore egg sacs in comparison with the control muscle group. The number of animals carrying egg sacs or not were counted exactly from the shadowgraph of the animals.

This new bioassay system using copepods and their shadowgraph counting will be useful not only for future test of ovarian stimulating and inhibiting substance but also for all further works such as the test of moulting hormone.
STRUCTURE AND FORMATION OF THE COLLAR IN CHOANOCYTES OF TETILLA SERICA (LEBWOHL), DEMOSPONGE
Authors: WATANABE YOKO
Published: January 2005

There are two types of collar in the choanocytes of adult Tetilla serica: one type is a continuous cytoplasmic tube and the other consists of discontinuous microvilli. The former is found in the small flagellated chamber and is considered to belong to a young choanocyte in the process of differertiation. To confirm this idea, very young choanocytes which are about to differentiate the collar were examined during embryogenesis.

The youngest choanocytes are noticed forming aggregations of small cells in 3‐day larvae. Around the flagellum in each choanocyte, there is a depression which will become wider. At first, the collar is observed as a ring of cytoplasm; next this extends outward and becomes thinner, and finally it divides into microvilli. The microvillous collar is formed by the opening of vesicles and fusion of their membranes. These vesicles are considered to be derived from the Golgi complex. The process of collar formation through fusion of vesicles is discussed.
DIFFERENCES IN SENSITIVITY TO CA ION LACK BETWEEN MYOBLASTS AND LARGE MYOTUBES FROM CHICKEN BREAST MUSCLE
Authors: Ozawa Eijiro
Published: January 2005

Large myotubes degenerated in Ca‐deficient medium containing Mg ion. Numerous vacuoles appeared in the cytoplasm and then grew larger. The cells were disrupted and eventually detached from the culture dish. The time course of the destruction process differed from cell to cell and the rate of reduction of creatine kinase in the culture dish was constant irrespective of the time after the removal of Ca ion. Most of the myoblasts survived in Ca‐deficient medium, after almost all the large myotubes had disappeared. These myoblasts fused to form new myotubes when Ca ion was supplied.

Myotubes formed from myoblasts which had been cultured with Ca‐deficient medium for 2 weeks also degenerated on Ca removal.

Sr ion added to Ca‐deficient medium did not completely prevent the destruction of myotubes but decreased the rate of their reduction.
Demonstration of Transdifferentiation of Neural Retina from Pigmented Retina in Culture1
Authors: TSUNEMATSU YASUHIKO , COULOMBRE ALFRED J.
Published: January 2005

The formation of neural retina (NR) from retinal pigmented epithelium (RPE) of chick embryos in culture was investigated. In cultures of explants of PRE, depigmented, preretinal foci, consisting of 50 to 100 cells appeared in the pigmented central portion of the explant within three days. Then these depigmented cells increased rapidly in number and by about day 14 they formed characteristic spherical bodies, which were identified as a neural retinal‐like structure (NR structure) by electron microscopic observations. Culture of explants of RPE from embryos of different stages showed that the capacity of embryonic RPE to form an NR structure decreased steadily with embryonic age from st. 24 to 27. At and after stage 27, no foci leading to the neural retinal differentiation were formed in the explants. Medium conditioned by cell cultures of chicken embryonic NR, RPE or chondrocytes had no effect on the formation of NR structures by explants of RPE.
Cytoplasmic Influence on Lethality in Nucleocytoplasmic and Natural Hybrids between Bufo Calamita Laur and Bufo Bufo L. (Amphibia, Anura)
Authors: DELARUE MICHEL , AIMAR CHRISTIAN
Published: January 2005

Nucleocytoplasmic interactions have been studied through nuclear and cytoplasmic grafts. Bufo bufo nuclei transplanted in Bufo calamita eggs provoked 95% lethality during gastrulation. Influence of the cytoplasm in such a nucleocytoplasmic incompatibility has been studied through cytoplasmic fractionation and grafting of the fractions obtained. Fractionation of egg cytoplasm gave three fundamental fractions: lipid, hyaline cytoplasm and vitellus. After injection of B. calamita fractions into B. bufo fertilized eggs, the hyaline cytoplasmic fraction provoked a gastrulation block in the same ratio (95%) as in the interspecific nuclear graft experiment. Influence of the hyaline cytoplasmic fractions of both species has been tested on nucleocytoplasmic and natural hybrid developments. The B. calamita hyaline cytoplasmic fraction provoked in each case a developmental block at the beginning of gastrulation. The B. bufo hyaline cytoplasmic fraction acts later at the yolk plug stage and in some cases partially corrects the developmental bolck or exogastrulation of young hybrid gastrula. It can be generalized that in both kinds of hybrids, the hyaline cytoplasmic fraction of B. calamita exerted a lethal effect on B. bufo nucleus.
Electric Field‐induced Fusion of Sea Urchin Eggs
Authors: RICHTER H.‐P. , SCHEURICH P. , ZIMMERMANN U.
Published: January 2005

An electrical method is described which permits the fusion of denuded eggs of the sea urchin species Paracentrotus lividus. In a nearly non‐conductive medium, containing 1.2 M glucose at pH 6.0–8.4, eggs or fertilized stages are brought into close membrane contact by dielectrophoresis arising from the application of a highly inhomogeneous alternating electric field. During this process the eggs aligne parallel to the field forming “egg‐chains”. In well pigmented eggs pigmentcapping is observed in the areas of cell contact. After completion of the alignment, the application of an additional single high field pulse of μs duration induces fusion of two or more eggs. The mechanism underlying the fusion process is the reversible electric breakdown of membranes in the zones of cell‐to‐cell contact. Fusion proceeds within 1–10 min at 10–20°C. Fused eggs have intact nuclei, can be fertilized, but undergo abortive cleavage.
Studies on the Formation and State of Determination of the Trunk Organizer in the Newt, Cynops Pyrrhogaster III. Tangential Induction in the Dorsal Marginal Zone
Authors: KANÉDA ITERUO
Published: January 2005

Analysis of the course of differentiation of combinants between the presumptive prechordal plate (PcP) and presumptive ectoderm (PE) by time‐lapse filming showed that the PcP of early gastrulae has the capacity to induce mesoderm (notochord, muscle cells and migrating cells) in the PE. The mesoderm‐inducing capacity of the PcP decreases sharply during gastrulation. Following invagination in the mid‐gastrula, the PcP completely loses its mesoderm‐inducing capacity. This change also occurred when the PcP of the earliest gastrula was aged in vitro for 18 hr. This shows that the mesoderm‐inducing capacity of the PcP decreases autonomously with aging.

PE transplanted into the presumptive trunk organizer region of the dorsal marginal zone of the earlist gastrula, became mesodermized within 12 hr. It is clear that this mesodermization of the transplanted PE is due to “tangential induction” from the PcP. The stepwise formation of the trunk organizer in Cynops pyrrhogaster is discussed in consideration of these results.
Stage Specific Effects on Sea Urchin Embryogenesis of Zn2+, Li+, several Inhibitors of cAMP‐Phosphodiesterase and Inhibitors of Protein Synthesis
Authors: MITSUNAGA KEIKO , FUJIWARA AKIKO , YOSHIMI TAKAHITO , YASUMASU IKUO
Published: January 2005

Treatment of sea urchin embryos for 3 hr starting at the 16‐64 cell stage with Li+ or 3‐isobutyl‐1‐methylxanthine as well as with other inhibitors of cAMP‐phosphodiesterase (PDE) and several inhibitors of protein synthesis, resulted in production of vegetalized embryos with a large exogut. However, the same treatment starting at other stages produced hardly any vegetalized embryos. The specific stage for these substances to cause vegetalization is probably the 16‐64 cell stage. Treatment with Zn2+ between the times of fertilization and hatching, followed by culture in normal sea water produced animalized embryos with little if any archenteron, but the same treatment followed by culture with ethylenediamine‐N, N'‐diacetic acid (EDDA), a chelator of Zn2+, produced quasi‐normal plutei. This chelator did not counteract the animalizing effect of Zn2+ when culture with EDDA was started at the post‐gastrula stage. Treatment of embryos for a long period (1‐3 days) starting at the blastula stage with Li+ and the inhibitors of PDE and protein synthesis, as well as with Zn2+, produced spherical embryos with little or no archenteron. The stages at which these substances produced abnormal embryos with a poor archenteron are post‐hatching stages.
Characterization of an Antiserum against Feather Keratins of the Chick: Its Crossreaction with a Lens Protein, δ‐crystallin
Authors: KODAMA RYUJI , EGUCHI GORO
Published: January 2005

We prepared an antiserum against a fraction of solubilized keratins extracted from down feathers of newly hatched chicks. The specificity of the antiserum was tested by double immunodiffusion, immunofluorescent staining, and immunoblotting after sodium dodecylsulfate‐polyacrylamide gel electrophoresis. All the bands except “Fast protein” reacted with the antiserum, suggesting the presence of a common antigenicity through various polypeptides in solubilized feather keratins. Delta‐crystallin, which is a lens specific protein, also reacted with the antiserum. The presence of a common antigenicity between δ‐crystallin and feather and scale keratins was confirmed by affinity‐purification of the antiserum, and its significance is discussed.
The Mitotic Apparatus with Unusually Many Microtubules from Sea Urchin Eggs Treated by Hexyleneglycol
Authors: ENDO SACHIKO , TORIYAMA MASARU , SAKAI HIKOICHI
Published: January 2005

The effect of hexyleneglycol on the structure of the mitotic apparatus was studied by light and electron microscopies. By treating sea urchin eggs at prometaphase and metaphase with hexyleneglycol, the mitotic apparatus was found to become remarkably decorated with unusually many astral microtubules which were conspicuously uniform in length. These microtubules appeared to be associated with the granular materials which are most likely microtubule initiating sites or microtubule‐organizing centers.
Stage Specific Effects of Zn2+ on Sea Urchin Embryogenesis (animalization/EDDA/EDTA‐OH/sea urchin embryos/Zn2+)
Authors: MITSUNAGA KEIKO , YASUMASU IKUO
Published: January 2005

The treatment of sea urchin embryos by Zn2+ followed by culture with Zn2+‐specific chelators such as ethylenediamine‐N, N′‐diacetic acid and N‐hydroxyethylethylenediamine‐N, N′, N′‐triacetic acid, was performed at various developmental stages to find out specific stages for Zn2+ to induce abnormal differentiation. The treatment with 1 mM ZnSO4 at 20°C during a period including two spans of development between 0 and 8 hr and between 14 and 16 hr post fertilization yielded permanent blastulae. Zn2+‐treatment during the former span produced abnormal prisms and plutei with small archenteron. The treatment for a period including only the latter span failed to produce abnormal ones. Zn2+‐treatment during a period including the gastrula stage also produced abnormal spherical embryos. Without the culture with these chelators, abnormal embryos were produced by Zn2+‐treatment performed at any stages before gastrulation. A high zinc amount in the embryos just after the treatment became as low as in normal embryos soon after the culture with these chelators and was maintained during the culture without them. These results indicate that zinc retention occurs in the Zn2+‐treated embryos and causes abnormal differentiation when the treated embryos develop in normal sea water through the Zn2+‐specific periods of development.
Histogenesis of the Os Penis and Os Clitoridis in Rats
Authors: MURAKAMI RYUTARO , MIZUNO TAKEO
Published: January 2005

The development of the os penis in normal male rats and the os clitoridis in the females treated with testosterone were studied histologically and histochemically. Alcian blue‐positive materials, alkaline phosphatase activities and calcium deposit were detected. The os penis of the rats was composed of a proximal segment and a distal one. The proximal segment of the os penis was formed by the fusion of a membrane bone in its distal half and an ossifying hyaline cartilage in its proximal half. The distal segment of the os penis developed as a fibrocartilage bone.

Two steps were demonstrated in the development of the os penis: the formation of the rudiments, and the differentiation of the proximal and distal segments. The treatment of newborn females with testosterone induced an os clitoridis homologous to the proximal segment of the os penis. The development of the os clitoridis was compared with that of the os penis.
Synergistic Inhibition of Fructose 1,6‐Bisphosphatase by Fructose 2,6‐Bisphosphate and Adenosine Monophosphate in Round Spermatids of Rats
Authors: NAKAMURA MASAHISA , SUZUKI AKIRA , OKINAGA SHOICHI , ARAI KIYOSHI
Published: January 2005

The effects of adenosine monophosphate (AMP) and fructose 2, 6‐bisphosphate (fruc‐2, 6‐P2) on the key‐enzyme of gluconeogenesis, fructose 1, 6‐bisphosphatase (fruc‐P2ase; D‐fructose 1, 6‐bisphosphate 1‐phosphohydrolase, EC 3.1.3.11) in spermatid extract from rat testes were studied. The fruc‐P2ase activity in the spermatids of rats was suppressed by AMP and fruc‐2, 6‐P2. The inhibition of fruc‐2, 6‐P2 was much stronger at low than at high substrate concentrations, and enhanced synergistically with AMP. The substrate saturation curve was changed by fruc‐2, 6‐P2 hyperbolic to sigmoidal. Furthermore, the concentration of AMP that decreased the activity to 50% was much lower in the presence than in the absence of fruc‐2, 6‐P2. These results indicate the possibility that gluconeogenesis in spermatids of rats is controlled by AMP and fruc‐2, 6‐P2.
Change in the Triglyceride Level in Sea Urchin Eggs and Embryos During Early Development
Authors: YASUMASU I. , HINO A. , SUZUKI A. , MITA M.
Published: January 2005

Triglycerides in the embryos of the sea urchin, Anthocidaris crassispina, analyzed by gas‐liquid chromatography, distributed in a range of carbon numbers between 42 and 58 in the sum of three fatty acid residues. During the development until gastrulation, the levels of triglycerides with 48, 56 and 58 carbon numbers decreased at constant rates and the levels of the others decreased at specific stages different with one another, respectively. Thereafter, the amounts of all triglycerides decreased simultaneously. The amount of oxygen consumed in the embryos is enough for the oxidation of mobilized triglycerides during post‐hatching period but is not during pre‐hatching period. The levels of neutral glycerides increased gradually during pre‐hatching period and thereafter decreased. The fatty acid level also increased during pre‐hatching and post‐hatching period. These suggest that the cleavage of triglycerides and the oxidation of their cleavage‐products occur during whole span of early development. During pre‐hatching period, the break down of triglycerides is probably higher in its rate than the rate of their oxidation, resulting in the increase in the levels of neutral glycerides, as well as fatty acids.
Analysis of Differentiation of Hepatocytes and Bile Duct Cells in Developing Mouse Liver by Albumin Immunofluorescence
Authors: SHIOJIRI NOBUYOSHI
Published: January 2005

Differentiation of endodermal cells in embryonic mouse liver was analyzed by study of their albumin immunofluorescence. Hepatocytes extending from the cranial diverticulum in 9.5‐day embryos do not contain albumin. In 10.5‐to 11.5‐day embryos, hepatocytes are still immature, but they all show albumin immunofluorescence. Most precursor cells of intrahepatic bile‐duct cells also give a positive reaction for albumin, like immature hepatocytes. The differentiation of intrahepatic bile‐duct cells from immature hepatocytes is suggested.
Studies on Ergothioneine. IX. Ergothioneine Stimulates Mouse Spermatozoa and Fertilization in vitro
Authors: MAYUMI TADANORI , KAWANO HIROKO , KAWAI YUICHI , HAMA TAKAO
Published: January 2005

The effects of ergothioneine on spermatozoa and ova were investigated in vitro and in vivo. Spermatozoa were treated with ergothioneine in vitro, and injected into the uterine cavity of female mice immediately after the induction of superovulation. The ova were recovered 24 hr later and assessed for fertilization. Preincubation of spermatozoa with ergothioneine resulted in a significant increase in the fertilization rate. When ova were inseminated in the same manner in vitro with spermatozoa treated with 0.1 or 1.0 mM of ergothioneine, the penetration rate was significantly increased. These results suggest that ergothioneine is effective in inducing both capacitation and the acrosome reaction of mouse spermatozoa. Ergothioneine at concentrations of 0.1 and 1.0 mM in the preincubation medium was also effective in inducing the acrosome reaction of guinea pig spermatozoa. However, it had no significant effect on the development of 2‐cell ova in vitro.
Intracellular Localization and Sedimentation Coefficient of DNA Ligase in Oocytes of the Starfish, Asterina pectinifera
Authors: OISHI NOBORU , SHIMADA HIRAKU
Published: January 2005

When immature oocytes of Asterina pectinifera were separated into karyoplasts (nuclear fragments) and cytoplasts (anuclear fragments) by cytochalasin B treatment and centrifugation in a sucrose gradient, almost all their DNA ligase activity was recovered in the karyoplasts. Thus, DNA ligase seems to be localized in the germinal vesicles or their vicinity in starfish oocytes. No ontogenic change in the activity of DNA ligase per oocyte, egg or embryo, or in its sedimentation coefficient (4.1 S) was observed during oocyte maturation, fertilization, or early development.
Determination of Erythroid Cells in Unincubated Chick Blastoderm
Authors: ZAGRIS NIKOLAS
Published: January 2005

Portions the size of 1/6 to 1/32 part of unincubated blastoderm cultured in an albumen‐salineagar solid medium form erythroid cells under conditions which suppress normal co‐ordinated movements for mesoderm induction. Anterior and posterior regions of unincubated blastoderm have the same potentiality to form erythroid cells. The marginal zone seems to be the contributor of prospective erythroid cells. Portion 1/16 part of unincubated blastoderm forms morphologically distinct erythroid cells of the primitive and definitive lines as in normal development in ovo. It seems progenitor cell(s) is pre‐programmed to a particular pattern of differentiation and/or includes differentiation to various erythroid cell types as an obligatory step. This system provides novel experimental possibilities in the study of erythroid cell determination and differentiation.
The Localization of Precursor Cells for Larval and Adult Hemopoietic Cells of Xenopus Laevis in two Regions of Embryos
Authors: MAÉNO MITSUGU , TODATE ASAHI , KATAGIRI CHIAKI
Published: January 2005

For determination of the localization of lymphoid and erythroid precursor cells in embryos of Xenopus laevis, diploid‐triploid chimeras were produced either by joining embryos antero‐posteriorly or by orthotopic grafting of various tissues into Nieuwkoop‐Faber st. 22–23 tailbud embryos. The sources of the hemopoietic cells were determined in the chimeric animals at various stages by microspectrophotometry of Feulgen‐stained cells. Analyses of chimeras produced by joining embryos antero‐posteriorly at different levels showed that the precursor cells that contribute to the hemopoietic cells are localized in the posterior half to three quarters. Orthotopic grafting of ventral or dorsal tissues revealed that the precursor cells that contribute to hemopoietic cells in early larvae are mostly localized in the ventral blood island (VBI) mesoderm, whereas those for late larvae and adults are localized both in the dorso‐lateral plate (DLP) mesoderm comprising the prospective mesonephros and in the VBI mesoderm. Reciprocal heterotopic grafting of VBI‐ and DLP mesoderms showed that the two compartments differ in their capacities to differentiate into hemopoietic cells. It is proposed that the VBI‐derived cells migrating towards the primary lymphoid organs constitute the transient hemopoietic population of early larvae, and the importance of the mesonephric region for definitive hemopoiesis is pointed out.
A Relevant Method for Estimating Cell Cycle of Developing Cell: The Conspicuous Lengthening of Ts during the Early Neural Development of Cynops Embryo
Authors: YAMAZAKI‐YAMAMOTO KIYOKO
Published: January 2005

A new method for estimating cell cycle was proposed and the cell cycles of the presumptive neural cells of Cynops embryo from the gastrula to neurula stages were estimated. Up to the onset of gastrulation, Tg2 and Tg1 became recognizable and Ts lengthened more than 10 times of that in the morula stage. The respective phases of cell cycle, espetially Ts became prominently longer as gastrulation and neurulation proceeded. However, the Ts retained a correlation with Tgc as expressed in the following regression equation, Ts=0.795Tgc–0.090, through the early development of presumptive neural cells.
In‐vitro Production of Meiosis Inducing Substance (MIS) by Isolated Amphibian (Rana pipiens) Follicle Cells*
Authors: SCHUETZ ALLEN W. , GLAD RICHARD
Published: January 2005

Previous studies indicated that pituitary hormone induced oocyte maturation in preovulatory amphibian ovarian follicles is mediated by somatic elements of the follicle. In this study procedures were developed for isolating and culturing follicle cells and their ability to produce meiosis inducing substance (MIS) was assessed. Defolliculated oocytes surrounded by a single layer of follicle cells but not denuded oocytes matured in response to frog pituitary hormone (FPH) stimulation. Cultured follicle cells secreted MIS following stimulation with FPH. The amount of MIS activity produced was related to the number of follicle cells cultured and the dose of FPH utilized. Radioimmunoassay (RIA) analysis of medium from follicle cell cultures demonstrated that FPH stimulated steroid (progesterone) secretion from these cells. Addition of cAMP to follicle cell cultures enhanced FPH stimulated steroid production. The results indicate that follicle cells retain FPH responsiveness when uncoupled from the immature oocyte and exhibit both MIS and steroid secretory functions.
Problems of Oocyte Maturation and the Control of Chromosome Cycles*
Authors: MASUI YOSHIO
Published: January 2005

During oocyte maturation and zygote development chromosomes undergo cyclic changes, alternaing the condensed and decondensed states. In oocytes, zygotes and perhaps in other cells, the chromosome cycle appears to be controlled in same way by common cytoplasmic factors. Among them, maturation‐promoting factor (MPF) plays a particularly important role, although the germinal vesicle substances and cytoplasmic membrane vesicles are indispensable for the chromosomal changes. MPF precursor is stored in fully grown oocytes of most species, but replenishing MPF after its fall during cell cycles requires protein synthesis. During oocyte maturation protein synthesis increases following the activation of MPF, and the synthesized proteins bind with chromosomes that have condensed to a metaphase state. The temporal correlation between the appearance of MPF with chromosome condensation activity and spindle formation observed in various cells suggest a major role played by MPF in the control of chromosome and microtubule assembly cycles. Thus, MPF is a regulator that coordinates the functions of various cell components to advance the chromosome cycle from interphase to metaphase. Therefore, a key to understanding the control of the chromosome cycle lies in knowing factors on which MPF activity is dependent. Although some physiological parameters of the cell are known to affect MPF activity, including Ca ion levels, intracellular pH, protein synthesis activity, cAMP levels, and protein phosphorylation, it seems difficult to assign the control of MPF cycles to any of these parameters. On the contrary, MPF cycles appear to regulate changes in these parameters. Rather, since MPF has the ability to amplify itself by activating its precursor, thus being involved in the MPF‐generating system in the cell, the MPF cycle may be an autonomous process. This notion may be supported by the recent observation of the oscillatory activity of MPF in cytosols extracted from frog eggs. We propose theoretical models to explain the MPF oscillator in the cell.
Experiments Pertaining to the Suppression of Accessory Sperm in Fertilized Newt Eggs*
Authors: IWAO YASUHIRO , YAMASAKI HISASHI , KATAGIRI CHIAKI
Published: January 2005

In the physiologically polyspermic eggs of the newt, Cynops pyrrhogaster, a number of accessory sperm undergo pronuclear formation along with a concomitant DNA synthesis, but degenerate after zygote nucleus formation. When denuded eggs were divided into two halves at various post‐fertilization stages, the andromerogons produced before zygote nucleus formation but not after that stage cleaved at a high frequency. The accessory sperm were unable to participate in the cleavage when they were located in the half of the egg which was connected with the diploid merogon by a cytoplasmic bridge higher than 100 μm in height. The removal of the egg nucleus or the retardation of early post‐fertilization nuclear events by treatment with cycloheximide resulted in the induction of multipolar cleavage. Continuous exposure of the fertilized eggs to aphidicolin showed that in the appreciable absence of the DNA synthesis many eggs underwent a first cleavage cytokinesis of a mostly abortive type, but failed to initiate the following cytokinesis at all. Cytological examinations in association with these experiments suggest that the observed suppression of accessory sperm includes the inhibition of centriolar replication under the influence of the zygote nucleus, resulting in the failure of cytasters corporating with nuclear‐independent activity of cortical cytoplasm.
Regional Difference in Mechanical Properties of the Cell Surface in Dividing Echinoderm Eggs*
Authors: OHTSUBO MICHIHIRO , HIRAMOTO YUKIO
Published: January 2005

Stiffness of the cell was surface was determined in fertilized sea urchin and starfish eggs by measuring the mechanical resistivity of the cell surface against negative pressure applied to a restricted part with a micropipette in contact with the cell surface at its tip (elastimetry). In both sea urchin and starfish eggs, the stiffness of the cell surface changed almost in parallel between the presumptive furrow and polar surfaces before the onset of the first cleavage, and the stiffness of the furrow surface became larger than that of the polar surface when cleavage started, although temporal changes in the stiffness were different between sea urchin and starfish eggs. The stiffness of the cell surface changed almost in parallel between the surfaces at the equator and at the animal pole in starfish eggs before the onset of polar body formation. The stiffness of the cell surface around the forming polar body increased during the formation of the polar body and remained at a high level after the polar body formation. It seems that the stiffness difference responsible for the formation of the contractile ring develops simultaneously with rather than prior to the formation of the cleavage furrow.
Genetic Analysis of Developmental Mechanisms in Hydra. XV. Nematocyte Differentiation in Strains with Altered Developmental Gradients*
Authors: NISHIMIYA CHIEMI , FUJISAWA TOSHITAKA , WANEK NANCY , SUGIYAMA TSUTOMU
Published: January 2005

Nematocyte differentiation from the interstitial stem cells in hydra occurs non‐uniformly along the body column. The relative ratios of the 4 nematocyte types produced vary gradually from head to foot along the body axis (Bode and Smith, 1977). To find out whether this regional variation in nematocyte differentiation along the body column is related to the gradients of the head‐activation and head‐inhibition potentials, nematocyte differentiation patterns were examined in strains which have significantly different developmental gradients along their body columns. Five strains of hydra, including a wild‐type, two mutant strains and two chimeric (mutnt/wild‐type) strains, were investigated.

It was found that the regional variations in the nematocyte differentiation were similar in all the strains examined, and that no significant differences of the variation existed that could be attributed to the differences of the developmental gradients in these strains. This suggests that nematocyte differentiation is strongly affected by the axial position along the body column, but that the gradients of the morphogenetic potentials involved in head formation are not involved in this effect. Instead, some other parameter(s) of axial position not directly associated with these gradients must be responsible for the positional effect on nematocyte differentiation.
A Freeze‐Fracture Study of the Cortex of Xenopus laevis Eggs
Authors: CHARBONNEAU MICHEL , GREY ROBERT D. , BASKIN RONALD J. , THOMAS DANIEL
Published: January 2005

The organization of the cortex of Xenopus laevis eggs was investigated by freeze‐fracture electron microscopy. The cortical endoplasmic reticulum (CER) formed a network surrounding and interconnecting the cortical granules. It formed junctions with the plasma membrane and was confluent with the ER in subcortical regions. Intramembranous particles (IMP1) were only present in the P face of the CER, the E face being apparently devoid of pits and particles. Arrays of densely packed IMP1, having a mean diameter of 17 nm, were restricted to the microvillar region of the plasma membrane. The cortical granule membrane also contained IMP1 (mean diameter, 21 nm) that were sparsely and randomly distributed. Several types of cortical granule seemed to exist based on an analysis of the distribution of the different IMP sizes.
Notochordal Catecholamines in Exogastrulated Xenopus Embryos
Authors: GODIN ISABELLE , GIPOULOUX JEAN‐DANIEL
Published: January 2005

The notochord of anuran amphibian embryos, treated according to the procedure of Falk et al. (1962) in early stages, exhibits the characteristic formaldehyde‐induced fluorescence of catecholamines. Neurectodermal derivatives, such as the neural tube and neural crests are known to synthesize catecholamines in more advanced stages. For determination of the influence of these neurectodermal derivatives on the formation of catecholamines in the notochord, exogastrulation experiments were performed on Xenopus laevis embryos. In exogastrulated embryos, the differentiation of neural derivatives was inhibited. Treatment of such exogastrulae with formaldehyde vapours shows that, in the absence of the neural tube and neural crests, the notochord developed similar fluorescence to that observed in normal embryos. Thus, these neurectodermal derivatives do not seem to be required for the formation of notochordal catecholamines.
Transdifferentiation between Mast Cell Subpopulations
Authors: KITAMURA YUKIHIKO , NAKANO TORU , KANAKURA YUZURU
Published: January 2005

Mast cells are progeny of multipotential hematopoietic stem cells. Although most of the progeny of stem cells leaves the hematopoietic tissue after maturation, undifferentiated precursors of mast cells leave the hematopoietic tissue. Morphologically unidentifiable precursors migrate in the bloodstream, invade the connective tissues or the mucosa of the alimentary canal, proliferate, and then differentiate into mast cells. Even after their morphological differentiation, some mast cells retain an extensive proliferative potential. There are at least two subpopulations of mast cells, a connective‐tissue type and mucosal type. Connective tissue‐type and mucosal mast cells can be distinguished by histochemical, electron microscopical, biochemical and immunological criteria, but these two types can interchange, and their phenotypes are determined by the anatomical microenvironment in which their final differentiation occurs.
Distributional Change of Membrane‐associated Calcium in Sea Urchin Eggs during Fertilization
Authors: ŌHARA TAKANE , SATO HIDEMI
Published: January 2005

The “source and sink” for the intracellular calcium released during fertilization were examined in sea urchin eggs, Hemicentrotus pulcherrimus, with chlortetracycline as a fluorescent chelate probe. In order to distinguish the differential distribution of membrane‐associated calcium in various compartments in cytoplasm, eggs were stratified by centrifugation before or after fertilization. Only the layer containing mainly mitochondria exhibited the chlortetracycline‐fluorescence in unfertilized eggs. After fertilization, a new fluorescent band emerged in the membrane‐rich clear layer of stratified eggs. Chlortetracycline‐fluorescence in the clear layer was gradually redistributed surrounding the prophase nucleus and then incorporated into the mitotic apparatus. From these observations, we postulate that the major source(s) of released free calcium ions at fertilization is in the mitochondira layer and membranes in the clear layer are newly activated as the calcium sequestering system after fertilization.
Fine Structures of Oocytes and Accessory Cells of the Ovary in the Starfish Patiria (Asterina) pectinifera at Different Stages of Oogenesis and After 1‐Methyladenine‐Induced Maturation
Authors: AISENSHTADT T. B. , VASSETZKY S. G.
Published: January 2005

Morphological changes in the growing and maturing oocytes of Patiria (Asterina) pectinifero were studied by electron microscopy. Oogenesis is of the solitary type. An extensive system of rough endoplasmic reticulum (ER) and Golgi complex (GC) develops in the ooplasm forming the cortical, yolk and secretory granules in its peripheral regions. The contents of the latter granules are released from the oocyte and form the vitelline membrane. At early stages of oogenesis, extensive multiplication of mitochondria results in formation of a large aggregate of these organelles in the perinuclear cytoplasm (“yolk nucleus”). After maturation of full grown oocytes has been induced by 1‐methyladenine, the membranous cell structures are rapidly rearranged: vast aggregates of ER cisternae in the surface cytoplasm layer and single ER cisternae among yolk granules are disintegrated to small vesicles; the GC is reduced. These processes are suggested to be somehow related to changes in hydration of the cytoplasm and in rigidity of its surface layer. In maturing oocytes, the yolk granules form characteristic linear rows, trabeculae, traversing the cytoplasm and their boundary membranes fuse in zones of contact. Some granules are converted to multivesicular bodies, thus suggesting the activation of hydrolytic enzymes that form part of the yolk in echinoderms.
Surface Architecture of Sperm Tail Entry into the Hamster Oocyte
Authors: HIRAO YUKI‐HISA , HIRAOKA JUN‐ICHI
Published: January 2005

At various times after artificial insemination in vivo, fertilized eggs were flushed from the ampulla of the oviduct of the hamster. The processes of sperm tail entry into the oocyte were studied with phase‐contrast and electron microscopes. At 6–7 hr after insemination, the sperm head was incorporated completely into the ooplasm, but the entire length of the sperm tail still projected freely over the oocyte surface. The region on the oocyte surface where the second polar body was extruded was different from where the first polar body emerged. At 8–9 hr after insemination, the sperm tail was attached in a wave‐like fashion to the oocyte surface. Where some portions of the tail were attached, they were trapped by the microvilli of the oocyte and had begun to sink into the ooplasm. Thus, the entire length of the sperm tail was incorporated into the ooplasm successively but almost synchronously. From the present observations, we have proposed a model for the mechanism of sperm tail entry into the vitellus in vivo.
Sperm Nuclear Transformation and Aster Formation Related to Metabolic Behaviour in Amphibian Eggs
Authors: BÜHLER MARTAI. , PETRINO TERESA , LEGNAME ARNALDO H.
Published: January 2005

Bufo arenarum oocyte maturation is related to important modifications in the metabolism of carbohydrates. Such changes involve a different relative participation of the main oxidative routes and are under the influence of seasonal variations of the pituitary activity.

Ovulated coelomic oocytes obtained during the winter period, were unable to initiate cleavage after injection of a sperm suspension. The extent of sperm head transformation and aster formation in the cytoplasm of oocytes with a different metabolic behaviour (obtained during the winter and summer periods) were studied.

Our results show that sperm nuclear transformation and DNA synthesis were quite similar in both types of oocytes. In contrast to summer oocytes, in which the pronucleus was sourranded by an aster, no aster structure was formed in winter ooctyes notwithstanding pronucleus formation occurred.

These results suggest that the failure to develop aster may explain the lack of cleaving in winter oocytes. It appears that the metabolic changes, aster formation and the capability to cleave are closely related and could be dissociated from oocyte nuclear maturation in this species.
Pattern and Time Course of Cleavages in Early Development of the Ovoviviparous Pond Snail, Sinotaia quadratus historica
Authors: TANAKA MASAKO , ASAHINA HARUKA , YAMADA NAOKO , OSUMI MASAKO , WADA AKIRA , ISHIHARA KATSUTOSHI
Published: January 2005

The pattern and time course of cleavage during early development of the ovoviviparous pond snail, Sinotaia quadratus historica, in in vitro culture were investigated. The fertilized egg, 25–30 μm in diameter, underwent cleavage by repeated constriction and compaction as in blastocyst formation in mammalian embryos. The cleavage was slightly unequal and dextrally spiral, although a slight time lag in cleavages of blastomeres was observed after the 2nd cleavage. A small polar lobe was formed at the 1st cleavage, but not at the 2nd cleavage. Each cleavage proceeded very slowly under the experimental conditions, the 1st, 2nd, 3rd and 4th cleavages taking 22 hr or more, 9 hr and 10 hr, respectively. The cleavage pattern in in vitro cultures observed by light microscopy was confirmed by scanning electron microscopy.
Evidence for Involvement of Protein Kinase C in Germinal Vesicle Breakdown in Chaetopterus
Authors: ECKBERG WILLIAM R. , CARROLL ALAN G.
Published: January 2005

We have examined the possible involvement of protein kinase C (C‐kinase) in the initiation of germinal vesicle breakdown (GVBD) in Chaetopterus oocytes. Two tumor‐promoting phorbol esters (phorbol‐12, 13‐dibezoate and 12‐0‐tetradecanoylphorbol‐13‐acetate [TPA]) and a permeant diacylglycerol (1‐oleoyl‐2‐acetylglycerol), potent activators of C‐Kinase, triggered GVBD. Two other phorbol esters (phorbol‐13‐monoacetate and 4α‐phorbol‐12, 13‐didecanoate), which do not activate C‐kinase, were inactive. Three C‐kinase antagonists (W‐7, H‐7 and retinol) inhibited both naturally‐and TPA‐induced GVBD, whereas W–5, a much less inhibitory W–7 analog, had no effect on GVBD. Triggering of GVBD by TPA was independent of extracellular Ca2+. Although naturally‐induced GVBD was blocked by micromolar concentrations of the calmodulin antagonist, calmidazolium (R24571), and by millimolar concentrations of the permeant cAMP analog, dibutryryl cAMP, TPA‐induced GVBD was not affected by these agents. These results support the hypothesis that both C‐kinase and calmodulin are involved in the sequence of events leading to GVBD in this species.
Encystment‐Inducing Factor from Cultures of Acanthamoeba palestinensis
Authors: LASMAN MARIA
Published: January 2005

Acanthamoeba palestinensis grown in monolayer cultures encysted almost synchronously at a stationary phase, with a yield of about 80% cysts. Under these growth conditions an encystmentinducing factor was released into the medium by transforming amoebae. Cell‐free supernatants induced encystment of amoebae from early‐log phase cultures. The not dialyzable encystment factor was resistant to nuclease, protease and trypsin digestion, as well as to boiling, but the activity was almost completely destroyed by autoclaving. Isolation and further characterization of the factor will enable clarification of the mode of its action as a regulator of amoeba‐cyst transformation.
Fates of Animal‐Dorsal Blastomeres of Eight‐Cell Stage Xenopus Embryos Vary according to the Specific Patterns of the Third Cleavage Plane
Authors: MASHO RIE
Published: January 2005

The third cleavage plane in typical Xenopus embryos is horizontal. However, there are numbers of cases in which the third cleavage plane slants and yet the embryo develops normally. Pairs of animal‐dorsal (AD) blastomeres of eight‐cell stage Xenopus embryos with horizontal or oblique third cleavage plane were marked by intracellular injection of fluorescein dextran amine in order to locate their progeny. In neurulae, progeny of AD blastomeres was found mainly along the dorsal midline forming longitudinal clonal bands along the midline in the neural plate and the mesoderm underneath. AD blastomeres with oblique third cleavage plane further yielded the ventral endo‐mesoderm in the head. On the other hand, they formed narrower clonal bands in the anterior ectoderm compared with AD blastomeres with horizontal third cleavage plane. Thus the fates of animal‐dorsal brastomeres of eight‐cell stage Xenopus embryos vary according to the specific patterns of the third cleavage plane. This indicates that the third cleavage in the Xenopus embryo does not affect the normal fate of each region of the embryo presumed at the eight‐cell stage.
Prospective Neural Areas and their Morphogenetic Movements during Neural Plate Formation in the Xenopus Embryo. II. Disposition of Transplanted Ectoderm Pieces of X. borealis Animal Cap in Prospective Neural Areas of Albino X. laevis gastrulae.
Authors: SUZUKI AKIO S. , HARADA KEIICHI
Published: January 2005

Small pieces of the animal cap of X. borealis gastrulae were transplanted into various regions of the noninvoluting marginal zone of albino X. laevis gastrulae, and the distribution of the donor cells was analyzed by quinacrine fluorescence staining.

The present study indicated that the prospective central nervous system (CNS) lies as a belt‐shaped area in the noninvoluting marginal zone of early gastrulae. This belt‐shaped prospective neural area extends as far as 0.7 mm (115° to the vegetal pole) above the blastopore in the dorsal midline and 1.3 mm lateral (130° to the dorsal midline) to the dorsal midline. The ectoderm of the dorsal region extends in the animal‐vegetal direction and forms the ventral side of the CNS. The dorsalateral and lateral regions converge toward the dorsal midline and extended in the animal‐vegetal direction. The former constitutes the lateral side of the anterior CNS, and the latter the dorso‐lateral side of the posterior CNS.

The outer layer of ectoderm which was transplanted onto the inner layer of the host gastrula differentiated into neural tissues.

The prospective areas of the CNS and their morphogenetic movement during Xenopus embryogenesis are also discussed with regard to neural induction.
Affinity Purification of Embryo Proteins Phosphorylated on Tyrosine In Vitro*
Authors: Jiang Wanping , Peaucellier Gerard , Kinsey William H.
Published: January 2005

Fertilization of the sea urchin egg is accompanied by activation of one or more protein tyrosine kinases which have been shown to phosphorylate a restricted set of egg proteins in vitro. In order to characterize these tyrosine kinase substrates, we have used an antibody specific for phosphotyrosine to prepare an immunoaffinity column capable of binding phosphotyrosine containing proteins. This column bound five 32P‐labelled proteins from detergent extracts of embryo membranes phosphorylated in vitro. All were very tightly membrane associated, requiring detergent solubilization. Phosphoamino acid analysis revealed that each of these proteins was phosphorylated exclusively on tyrosine, indicating that they do not act as substrates for other classes of protein kinases.