bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental Timing of Synthesis and Translation of Arylsulfatase mRNA in Sea Urchin Embryo
Authors: SASAKI HIROSHI , AKASAKA KOJI , SHIROYA TSUGIO , SHIMADA HIRAKU
Published: January 2005

In the sea urchin (Hemicentrotus pulcherrimus) embryo, the arylsulfatase activity is known to increase dramatically after the mesenchyme blastula stage. In the present experiment, we have studied the mechanism underlying this increase in the arylsulfatase activity by using the inhibitors of transcription and translation. Inhibition of transcription by actionmycin D before hatching prevented the increase in the arylsulfatase activity, while inhibition of transcription after hatching failed to prevent the increase in the enzyme activity. Inhibition of translation by emetine always reduced the arylsulfatase activity. These results have been interpreted as that the arylsulfatase activity in the blastula embryo is supported by the pre‐synthesized mRNA, and that the marked increase in the enzyme activity which is observed from the mesenchyme‐blastula stage to the prism stage is due to the transcription of the arylsulfatase gene which occurs during the development from hatching to the mesenchyme‐blastula stage.
Structural Changes of Yolk Platelets and Related Organelles during Development of the Newt Embryo
Authors: KOMAZAKI SHINJI , ASASHIMA MAKOTO
Published: January 2005

Structural changes in yolk platelets and related organelles in the cytoplasm of the presumptive ectodermal region up to the stage of gastrulation were studied by light and electron microscopies using full‐grown oocytes, mature eggs descending the oviduct and embryos of the newt, Cynops pyrrhogaster. Yolk platelets with a superficial layer are first observed in mature eggs descending the oviduct. During the cleavage and early morula stages, the superficial layer increases in thickness and the main bodies become more slender. The superficial layer decreases in thickness in the blastula stage, and many yolk platelets lose this layer in the gastrula stage.

The amount of rough‐surfaced endoplasmic reticulum (r‐ER) increases rapidly in the morula stage, while Golgi complexes gradually increase in number between the cleavage and gastrula stages. In the cleavage and early morula stages, most of the r‐ER is closely adherent to yolk platelets and is associated with several mitochondria. Two types of free vesicles, large (0.5–4.0 μm diameter) and small (0.15–0.3 μm diameter), were seen in abundance from the early morula stage to the early gastrula stages.

Changes in the structure of yolk platelets are discussed in relation to changes in other cytoplsmic organelles.
Effect of Cytochalasin B on the Development of Membrane Transports in Sea Urchin Eggs after Fertilization
Authors: ALLEMAND DENIS , CIAPA BRIGITTE , DE RENZIS GUY
Published: January 2005

Investigations were made on the role of the cytoskeleton in the onset of ionic events following fertilization of sea urchin eggs. Events which depend upon phosphoinositide metabolism, such as the cortical reantion and acid release are affected by cytochalasin B (CB) after fertilization but not after activation of eggs with the ionophore A23187. These findings suggest that the sequence of events following sperm‐egg attachment depends on the cytoskeleton. CB also inhibits the Na+ pump and alanine uptake when added before insemination and during the following 30 min. These results argue for a role of the egg cortex cytoskeleton in activation of the Na+ pump by fertilization. We propose that the inhibitory effect of CB on the development of amino‐acid uptake after fertilization may result from an increase in the Na+ content of the egg resulting from Na+ pump suppression rather than from direct blockage of the carrier.
Troponin in Cultured Chicken Breast Muscle Cells
Authors: MATSUDA RYOICHI , STROHMAN RICHARD C. , OBINATA TAKASHI
Published: January 2005

The onset of troponin accumulation and the localization of troponin in cultured chick embryo skeletal muscle cells were studied by means of indrect immunofluorescent microscopy. At 31 hr after plating, troponin components were detected in 54–62% of total mononucleated myogenic cells and in all myotubes as longitudial fibrous structures. 3H‐thymidine incorporation stduy coupled with the immunofluorescent microscopy showed that mononucleated myogenic cells at the mitotic stage did not contain troponin. As myotube maturation proceeds, the troponin‐containing fibers were organized into cross‐striated structures. At the myotube stage, muscle cells were labeled with 35S‐methionine and proteins synthesized were analyzed by two‐dimensional gel electrophoresis. It was found that myotubes in culture synthesized both fast and slow types of troponin‐I and‐C. Our results suggest that fast and slow types of troponin components are synthesized in cultured skeletal muscle cells before or at the early phase of myofibrillogenesis.
Analysis In Vitro of Capacity of Fetal Fat Pad to Support Mammary Gland Embryogenesis
Authors: INAGUMA YUTAKA , NISHI YOSHIMI , SAKAKURA TERUYO , KUSAKABE MORIAKI , HOSICK HOWARD L.
Published: January 2005

Fourteen‐day fetal mammary fat pad precursor tissue (FP) has the capacity to support various fetal epithelia allowing them to accomplish their characteristic development in vivo, without their own mesenchyme (1). This capacity decreases with age of fetal fat pad and is lost postnatally. To analyse the molecular mechanism of such interaction, a method for in vitro duplication of organogenesis is necessary. In the present paper, a co‐culture system of fetal epithelium with prospective mammary fat pad is described. The explanted mammary epithelium started budding, then grew out forming branched mammary ducts with end buds. Ultrastructurally, the developing ductal structures exhibited the typical mammary gland morphogenesis.

3H‐Thymidine incorportion assessed by autoradiography showed that the mammary gland morphogenesis in vitro was due to the proliferation of epithelial cells, not merely to a change of the shape of the epithelium. This supportive capacity of 14‐day FP also decreased with aging; explanted mammary epithelium did not grow into 17‐day FP. When insoluble, non‐living biomatrix was used in place of living FP the epithelium grew into the matrix but the resulting structures lacked characteristic morphology of epithelium on living fetal FP. The difference of capacity between 14‐day and 17‐day tissues was also lost.
Changes of DNaseI Sensitivity of the Fibroin and Sericin Genes during the Silkworm Development
Authors: KOGA‐BAN YASUNORI , SUZUKI YOSHIAKI
Published: January 2005

DNasel sensitivity assay of the fibroin gene and the sericin gene in different tissues along developmental stages have revealed unique patters of regulation. In the posterior silk gland the fibroin gene was more sensitive to DNaseI at the larval feeding stages, when the gene is transcriptionally active, than at the larval molting stages, when the gene is inactive. In the middle silk gland and the ovarian tissue where the fibroin gene is suppressed throughout development, the gene was found to be resistant to DNaseI. On the other hand the sericin gene remained rather DNaseI sensitive in the middle silk gland through larval development, where transcription activity of the gene changes drastically. Disappearance of DNaseI sensitivity of the fibroin gene at the fourth molting stage takes place earlier than the decline of the fibroin gene transcription. However, in the fifth feeding stagereappearance of DNaseI sensitivity occurs synchronously with resumption of the fibroin gene transcription. Thus a constitution of the DNaseI sensitivity may be required, but not sufficient to support an active state of genes.
Pluripotency of Homozygous‐Diploid Mouse Embryos in Chimeras
Authors: OTANI HIROKI , YOKOYAMA MINESUKE , NOZAWA‐KIMURA SHIARI , TANAKA OSAMU , KATSUKI MOTOYA
Published: January 2005

Pluripotency of mouse uniparental cells (complete homozygous‐diploid gynogenetic) produced by embryo manipulation was examined in aggregation chimeras with normally fertilized embryos. A male pronucleus was removed from fertilized eggs by micromanipulation and eggs were diploidized with cytochalasin B. Uniparental cells that developed to 4‐cell or more advanced stages were aggregated with normally fertilized 8‐cell embryos and transferred to the pseudopregnant female uteri to develop to term. Among the pups, 1 female and 3 males were identified as overt chimeras by their coat color and pigmentation of the retina. Using electophoretic analysis of the isozymes, the contribution of uniparental cells in these chimeras was confirmed by findings in the major organs such as liver, brain, small intestine, kidney, spleen, heart and testis. The female chimera produced offspring derived from oocytes of uniparental origin. Our experiments verified the pluripotency of microsurgically produced mouse uniparental cells.
Effects of Endopeptidase Inhibitors on Gastrulation of Xenopus Eggs (gastrulation/microinjection/endopeptidase inhibitor/dorsalization/Xenopus)
Authors: MIYATA SHOHEL , KIHARA HIROZI K.
Published: January 2005

Protease inhibitors were injected into Xenopus embryos to determine the involvement of proteases in development. Injection of inhibitors of endopeptidase into the dorsal region of Xenopus embryos resulted in abnormal gastrulation with incomplete invagination and development of the embryos into defective tadpoles. In contrast, injection of protease inhibitors into the ventral region resulted in normal development. The frequency of abnormal gastrulation was significantly less on injection of an endopeptidase inhibitor in which the functional aldehyde group has been reduced with NaBH4. These results suggest that during early development of Xenopus embryos, the protease activity in the dorsal region is necessary for gastrulation.
The Periodic Changes in Microvilli Density in Activated Xenopus Eggs That Correspond to the Cleavage Cycle
Authors: OHSUMI KEITA
Published: January 2005

In order to obtain the cytological basis for the periodic flattening and rounding‐up of activated amphibian eggs, the surface ultrastructure and the cortical microfilament organization were studied in Xenopus laevis. Scanning electron microscopy (SEM) of the egg surface revealed that the density of microvilli at the animal pole region decreased significantly when the periodic flattening started, but increased again concomitantly with the commencement of the rounding‐up. Isolated pieces of the cortices stained with rhodamine‐phalloidin exhibited the periodic disorganization and reorganization of a meshwork with bright dots probably corresponding to microvilli, in good synchrony with the decrease and increase of the microvilli density. Study of appropriate batches of eggs in which the moving front of surface contraction waves (SCWs; 1) can be localized revealed that the decrease and increase of the microvilli density correspond to SCW‐1 and ‐2, respectively. SEM and the cytochemical examination of the eggs from which the germinal vesicle (GV) had been removed revealed that none of these changes occurred in the enucleated eggs. These observations suggest that the GV‐dependent regulation of the microfilament organization in an egg cortex constitutes the cytological basis for the SCWs and for the periodic flattening and rounding‐up of denuded eggs.
Expression of Three Gastrula Cell Surface Glycoproteins during Embryonic and Larval Development in the Amphibian Pleurodeles waltlii
Authors: RIOU JEAN‐FRANÇOIS , SHI DE‐LI , DARRIBÈRE THIERRY , BOUCAUT JEAN‐CLAUDE , CHARLEMAGNE JACQUES
Published: January 2005

We have previously reported the identification of cell surface glycoproteins in Pleurodeles waltlii gastrulae. In an attempt to study the expression of three of these cell surface glycoproteins (proteins referred to 1, 11 and 14), we have produced monoclonal and polyclonal antibodies by immunizing mice with the spots of the three selected glycoproteins excised from 2D‐gels. Expression of the three glycoproteins was detected on the surfaces of all cells during embryonic development. Before hatching, proteins 1, 11 and 14 become expressed in a limited number of tissues.
Three Groups of Teratocarcinoma Antigens Co‐Expressed in the Visceral Endoderm are Located in Mutually Exclusive Sites in the Adult Kidney
Authors: OZAWA MASAYUKI , YONEZAWA SUGURU , SATO MASAHIRO , UEHARA HIROYUKI , SATO EIICHI , MURAMATSU TAKASHI
Published: January 2005

Monoclonal rat antibodies were prepared against glycoproteins isolated from murine teratocarcinoma OTT6050 by affinity chromatography on Ricinus communis agglutinin (RCA). These antibodies defined three distinct groups of antigens (OR antigens) commonly expressed in teratocarcinoma cells and in restricted sites of the kidney. OR 17 antigen was a new glycoprotein antigen and the biochemical properties were different from any membrane glycoprotiens or matrix glycoproteins so far described in teratocarcinoma cells. In the kidney, the antigen was found in the glomerular basement membrane, and to lesser extent in the endothelium of the glomerulus and blood vessels. On the other hand, OR 8 antigen corresponded to “brushin” defined by conventional antibodies, while OR 4 and 19 antigens were carbohydrate antigens resembling “TC antigen”. OR 8 antigen was detected in the tubular brush border and the epithelium of Bowman's capsule. OR 4 antigen was present in the collecting tubules and the thin loop of Henle. Although OR 19 antigen showed distribution similar to OR 4 antigen, there were genetic differences in the expression of the former antigen. All of the antigens were present in early postimplantation embryos of the mouse, notably in the visceral endoderm. These antigens are interesting subjects to study the mechanism of differentiation‐dependent control of gene expression, since antigenic distribution is specialized as the result of differentiation.
Studies on Unequal Cleavage in Sea Urchins III. Micromere Formation under Compression
Authors: DAN KATSUMA
Published: January 2005

When sea urchin embryos at 2‐cell stage are flattered between agar plates, the direction of cleavage is rotated by 90° in each division in reference to the preceding cleavage and no micromere is formed. But under this condition, micromeres are formed in 2 cases; 1) When the egg axis is parallel to the plane of flattening, 2 micromeres are formed on one side of a square 16‐cell stage. 2) when the egg axis is perpendicular to the plane, 4 micromeres are formed at the center of the square.

When put into a groove, a string of 4 cells is formed showing that the spindle direction is further deflected by the groove. In the following 16‐cell stage in the groove, which consists of 2 layers of 8 cells, cases with 2 micromeres on one side and 4 micromeres at the center are still found. If the 2‐cell stage is introduced into a groove after the formation of mitotic apparatus, the spindle direction can no longer be changed and the 4‐cell stage becomes like 4 pancakes stuck in 2 layers, indicating that 2 asters are holding the ends of a spindle in fixed positions.
A Yolk‐granule Component Acts as an Adhesive Material for Dissociated Gastrula Cells of the Newt, Cynops pyrrhogaster
Authors: KOMAZAKI SHINJI
Published: January 2005

Yolk granules were collected from full‐grown ovarian oocytes of the newt, Cynops pyrrhogaster, and dissolved in 3% acetic acid or 8 M urea solution. Culture dishes were then coated with either of the yolk‐granule solutions. The yolk‐coated surfaces acted as adhesive substrata for dissociated gastrula cells, which showed active locomotion when spread on the surfaces. Divalent cation was required for cell adhesion and spreading on the yolk‐coated surface. Trypsin and glycosidase digestions of dissociated cells or the yolk‐coated surfaces inhibited cell adhesion and spreading. Addition of concanavalin A to the culture medium inhibited cell spreading on the yolk‐coated surfaces, while high concentration (50 mM) of the saccharides, D‐galactose, D‐lactose and D‐mannose, had a slightly inhibitory effect on cell spreading.

Two yolk components (30‐kD and 108‐kD proteins) were isolated from yolk granules and applied to the culture dish surfaces. Surfaces coated with the 30‐kD protein showed strong adhesiveness for dissociated gastrula cells.
Inhibitory Action of an Imidazole Compound on Ecdysone Synthesis in Prothoracic Glands of the Silkworm, Bombyx mori
Authors: KADONO‐OKUDA KEIKO , KUWANO EIICHI , ETO MORIFUSA , YAMASHITA OKITSUGU
Published: January 2005

The precocious pupation was induced either by allatectomy at the time of third ecdysis or by topical application of an imidazole compound (KK‐42; 1‐benzyl‐5‐[(E)‐2, 6‐dimethyl‐1, 5‐heptadienyl] imidazole) to the fourth (penultimate) instar larvae of the silkworm, Bombyx mori. However, the critical period for KK‐42 treatment in induction of precocious pupation was longer than that for allatectomy. The effects of KK‐42 depended on the doses applied and a half‐maximum dose was estimated to be approx. 10 μg/larva. KK‐42 suppressed the increase in hemolymph ecdysteroid titres leading to larval ecdysis in controls. Ecdysteroid levels remained at low levels for about 6 days after the treatment, followed by an increase toward precocious pupation. When the prothoracic glands from the mature fifth instar larvac were incubated in vitro in Grace's medium containing various concentrations of KK‐42, secretion of ecdysone into the medium was suppressed depending upon the doses of KK‐42 added and a half‐inhibition concentration was estimated to be approx. 1 nM. Thus, KK‐42 was shown to be an inhibitory agent to ecdysteroid secretion in silkworm larvae.
Competence as the Main Factor Determining the Size of the Neural Plate
Authors: ALBERS BRIGITTE
Published: January 2005

A piece of ectoderm was taken from the neural plate area of an early neurula (Ambystoma mexicanum) and replaced by competent gastrula ectoderm. Neural tissue was induced in these transplants, and the amount of neural tissue was used to estimate the spreading of the neural inductive stimulus. Dependence was tested of the amount of neural tissue formed in the transplants on the following factors: distance of the transplant from the dorsal midline of the host, age of the host, age of the transplant. The first two factors had no influence on the results but age of the transplant turned out to be decisive. The distance of the transplant from the midline of the host did not influence the amount of neural tissue found in the transplant, even in transplants out side the normal neural plate area neural differentiation was induced.

It is concluded that the spreading of neural induction is not controlled by a gradient but by the loss of neural competence of the ectoderm. A model for the spreading of neural induction is suggested using competence and homoiogentic induction as its main factors.
Cell Culture of Spermatogenic Cells from Amphibians
Authors: ABÉ SHIN‐ICHI
Published: January 2005

Cell culture of spermatogenic cells from the primary spermatocyte stage to the early, midspermatid stage has been established for the Japanese newt, Cynops pyrrhogaster (1–4, 10, 11) and for Xenopus laevis (2, 3, 5, 17, 18). The results of many investigations suggest that sperm maturation in vitro for each species proceeds along the same pathway and under the same temporal control as in vivo. Since the shape and size of mature sperm of these two species are very different, comparative studies would enable us to elucidate the mechanisms by which sperm morphology is determined. The results obtained from in vitro studies of spermatogenesis in Cynops and Xenopus demonstrate that there are common and species‐specific features.
Changes in the Distribution of Calcium‐Sequestering Membranes during the First Cell Cycle of the Sea Urchin, Lytechinus variegatus
Authors: HINKLEY ROBERT E. , NEWMAN ARTHUR N.
Published: January 2005

Chlortetracycline (CTC) has been used to study sequential changes in the distribution of calcium‐sequestering membranes during the first cell cycle of fertilized sea urchin eggs CTC staining patterns first appear as a diffuse ring around the centered zygote nucleus at the time of syngamy. As development proceeds, the ring becomes brighter and then elongates concurrently with the formation of the streak apparatus. Fluorescence subsequently accumulates in the centrospheres of the developing mitotic apparatus and is present in mitotic asters throughout mitosis. When the mitotic apparatus disappears, the fluorescence associated with each aster condenses into a bright ring surrounding each daughter nucleus. Ultrastructural studies show that CTC‐fluorescent areas are rich in membranes while experiments with rhodamine 123, a mitochondrion‐specific laser dye, indicate that mitochondria are excluded from areas in which membranes accumulate. Microtubule inhibitors prevent the initial accumulation of fluorescence around the zygote nucleus and arrest the development of existing fluorescence patterns when applied at later stages. In contrast, changes in fluorescence patterns are unaffected by the microfilament inhibitor cytochalasin D. These observations show that calcium‐sequestering membranes are associated consecutively with the sperm aster, streak, and mitotic apparatus and that the continual reorganization of these membranes during the first cell cycle depends on the assembly and disassembly of microtubules.
Morphogenesis of Mouse Mammary Epithelium In Vivo in Response to Biomatrix Prepared from a Stimulatory Fetal Mesenchyme
Authors: HOSICK HOWARD L. , INAGUMA YUTAKA , KUSAKABE MORIAKI , SAKAKURA TERUYO
Published: January 2005

Insoluble “biomatrix” of mesenchyme is a stimulator of mammary cell differentiation in vitro, but its effect in the morphogenesis is unknown. Fetal salivary mesenchyme induces intense local duct formation when implanted into adult mammary gland. We have therefore tested whether biomatrix prepared from fetal salivary mesenchyme retains this abillity to stimulate duct formation in vivo. Salivary mesenchyme isolated from mouse fetuses at 13.5–14.0 days of gestation, extracted sequentially with water and with 1 M NaCl, then digested with DNAse and RNAse was implanted into mammary glands of female mice and left for periods of 1–35 days. In approximately 40% of recipients, the local epithelium either formed cyst like structures, or else “spikes” of mammary epithelium penetrated the matrix forming a simplified ductwork inside it. Similar responses were elicited by salivary mesenchyme killed by freezing and also by biomatrix prepared from fetal mammary fat pad precursor tissue, mesenchyme of fetal lung, and fetal heart, liver, and brain. However when mesenchyme was either fixed with glutaraldehyde or sonicated and embedded in polymer blocks before implantation, no epithelial response was noted. These observations suggest that the biomatrix provides a passive scaffolding that contributes to morphogenesis of mammary ducts, is insufficient to support normal morphogenesis.
Pepsinogen Induction in Chick Stomach Epithelia by Reaggregated Proventricular Mesenchymal Cells In Vitro
Authors: TAKIGUCHI KEIKO , YASUGI SADAO , MIZUNO TAKEO
Published: January 2005

In vitro organ culture system which permits embryonic chick proventriculus (glandular stomach) to synthesize pepsinogen de novo was developed. Explants of the proventricular rudiment were cultured on Millipore filters in Medium 199 with Earle's salts supplemented with 50% 12‐day embryo extract at 38°C in 95% air and 5% CO2.

In these culture conditions, pepsinogen, a functional marker protein of proventriculus, was first detected after 3 days of cultivation of 6‐day chick proventricular rudiment. When recombined and cultured with 6‐day proventricular mesenchyme, 6‐day oesophageal, proventricular or gizzard (muscular stomach) epithelium expressed pepsinogen while small intestinal epithelium did not. These results were consistent with the previous results obtained by chorioallantoic membrane (CAM) grafting, and showed that the culture conditions are permissive for pepsinogen expression.

When recombined and cultured with reaggregated mesenchymal cells isolated from 6‐day proventricular mesenchymal fragments, both 6‐day proventricular and gizzard epithelia formed glandular structure and expressed pepsinogen. This indicates that the proventricular mesenchymal cells retain the ability to induce morphogenesis and cytodifferentiation of the proventricular epithelium even if the normal organization of proventricular mesenchyme is once destroyed.
The Cell Cycle and Cell Population Kinetics in the Programmed Cell Death in the Limb‐Buds of Normal and 5‐Bromodeoxyuridine‐ Treated Chick Embryos
Authors: TONÉ SHIGENOBU , TANAKA SHOJI , KATO YOSHIHIRO
Published: January 2005

The cell cycle and cell population kinetics have been analyzed in the interdigital regions of chick limb‐buds during the course of programmed cell death both in normal and the 5‐bromodeoxyuridine (BrdU)‐treated embryos. Our previous study has shown that a single administration of BrdU at day 6 1/3 inhibited the programmed cell death occurring in normal development of limb‐buds.

Pulse‐ as well as continuous labelings with tritiated thymidine (3H‐TdR) were used. The results obtained from the analyses made on both normal and experimental embryos have demonstrated the presence of a particular DNA‐synthetic period, around day 6 1/3, closely related to the programmed death occurring on day 7 1/3. In normal embryos, new cell populations, which did not belong to any phases of normal cell cycle, made their appearances in the process of programmed cell death. A possible correlation between programmed cell death and the cell cycle has been discussed in relation to the morphogenesis of limbs in both normal and BrdU‐treated embryos.
Distributions of Actin, Vinculin and Fibronectin in the Duodenum of Developing Chick Embryos: Immunohistochemical Studies at the Light Microscope Level
Authors: NODA SETSUKO , MITSUI TAOAO
Published: January 2005

Microscopic studies were made on the localizations of three different cytoskeletal proteins, actin, vinculin and fibronectin, in the duodenum of developing chick embryos and chicks by an indirect immuno‐fluorescent staining method with specific antibodies.

Topographical changes in the distributions of these three proteins seemed to be related to stages in morphogenesis of the duodenum. In early stages of embryonic development, findings suggested interaction between actin and vinculin in the apical region of epithelial cells and between actin and fibronectin in the basal region of these cells. From this stage, vinculin and fibronectin seemed to be of importance in determination and continuity of the polarity of the duodenal epithelium, and in control of the intracellular arrangement of actin. This relation between actin and vinculin seemed to continue throughout embryogenesis.

The main role of actin in epithelial cells seemed to change on day 12 from that of forming constricting bundles for morphogenesis of previllous ridges to that of microfilaments in the microvilli and the terminal web.
Localization and Characterization of an Integral Membrane Protein Antigen Expressed by Pigment Cells in Embryos of the Sea Urchin Strongylocentrotus purpuratus
Authors: GIBSON ALLAN W. , BURKE ROBERT D.
Published: January 2005

Chromogenic mesenchymal cells in plutei of the sea urchin Strongylocentrotus purpuratus express a tissue specific epitope recognized by the monoclonal antibody Sp–1. In transmission electron micrographs of pre‐embed immunoperoxidase labelled plutei, the epitope is localized to pigment cell surfaces. Cell membranes of epidermal cells apposed to pigment cells are also immunoreactive, but endodermal cells apposed to pigment cells are not. Separation of Sp–1 immunoreactive material into the aqueous phase after embryo extraction in butanol indicates that the antigen is a protein or glycoprotein, and other solubilization characteristics suggest that it is an integral membrane constituent. The epitope is destroyed by general proteases and treatment with guanidine hydrochloride, and is resistant to oxidation by periodate and glycosyloxidases, suggesting that it is peptide rather than carbohydrate. On immunoblots of whole embryo extracts, or after SDS‐PAGE analysis of 35S‐methionine‐labelled embryos immunoprecipitated with Sp–1, a band showing an apparent molecular mass of 110 kD is seen at all stages from mid‐gastrula to 26‐day pluteus. We conclude that the Sp–1 antigen is a 110 kD integral membrane protein which may interact with the epidermal cells over which the pigment cells migrate.
Fibroin Gene Transcription in the Embryonic Stages of the Silkworm, Bombyx mori
Authors: OHTA SHUNSUKE , SUZUKI YOSHIAKI , HARA WAJIRO , TAKIYA SHIGEHARU , SUZUKI TOSHIHARU
Published: January 2005

Using a modified RNase mapping method the transcription of the fibroin gene in Bombyx mori embryos was analyzed. It is known that the silk gland development begins at stage 19 of the 30 embryonic stages and its morphological development completes by stage 25. RNA samples obtained from embryos of a Chinese strain C108 from stages 4 through 23 did not give a positive signal except a faint and transient transcript detected at stage 22. In RNA samples from later stage embryos of a Kanebo commercial strain Kin‐Shu X Sho‐Wa, a faint and ambiguous fibroin transcript was detected at stages 25 and 26, and a clear and accurate initiation of transcription of the gene was detected from stage 27 and increased greatly at stages 29 and 30 reaching a level of about 0.3 ng/embryo or about 1% of total RNA presumably in the posterior silk gland. These results indicate that the fibroin gene transcription begins for the first time after the completion of the embryonic silk gland development, and also suggest that around stages 25 to 27 are probably a critical time to search for the production and accumulation of a factor(s) governing the transcriptional regulation of the fibroin gene.
Estrogen Responsiveness and the Estrogen Receptor during Development of the Murine Female Reproductive Tract
Authors: TAGUCHI OSAMU , BIGSBY ROBERT M. , CUNHA GERALD R.
Published: January 2005

The developing uterus, vagina, and cervix of mice whose age ranged from 16 days of gestation to 90 days postnatal were examined for nuclear estrogen receptors (ERs) by autoradiographic and whole cell uptake techniques. ERs were present within mesenchymal cells of these organs throughout the entire period of development and maturation. By contrast, nuclear ER first became detectable by autoradiography in the epithelium of vagina and uterus at 5 and 6 days postnatal, respectively.

As a result of administration of the synthetic estrogen, diethylstilbestrol (DES), consecutively from 16 to 18 days of gestation, uterine and vaginal epithelial cell height was increased and epithelial secretory activity was elevated during the first 48 hr of postnatal life. Also, a single does of DES administered on the 2nd day after birth stimulated epithelial proliferation in the uterus as determined by 3H‐thymidine incorporation. These typical estrogenic effects occurred in the absence of nuclear ER within the epithelium. Prenatal DES treatment accelerated the onset of ER activity within the epithelium by 2 to 3 days relative to controls. The possibility that certain effects of estrogen on epithelial differentiation may be mediated indirectly via ER positive mesenchymal cells is discussed.
Influence of Photoperiod, Daylength, and Feeding Schedule on Tadpole Growth and Development
Authors: WRIGHT MARY L. , JOREY SUZANNE T. , MYERS YVONNE M. , FIELDSTAD MICHELLE L. , PAQUETTE CHRISTINE M. , CLARK MARY BETH
Published: January 2005

The metamorphic rate of Rana pipiens tadpoles was studied under different photoperiods, daylengths, and feeding schedules. Tail resorption and hindlimb growth and development induced by immersion in 30 μg/l thyroxine (T4) were accelerated under longer photoperiods and continuous light when 6L: 18D, 12L: 12D, 18L: 6D, and 24L regimes were compared. Constant light exposure did not produce faster development than an 18 hr photoperiod, and initially was less effective. The rate of spontaneous and T4‐induced metamorphosis was greater the shorter the day on 9L:9D, 12L: 12D, or 15L: 15D cycles, although all groups received the same overall amount of light, but in different dosages. When feeding schedule but not the LD cycle was varied, groups of tadpoles fed on 18, 24, or 30 hr regimes showed no differences in growth and development rate on 19L: 5D, and only random variations under continuous light. Differences in metamorphic rate on 18, 24, or 30 hr days are not due to the feeding schedules, but to the LD cycles. From these experiments we conclude that illumination, particularly the length and frequency of the photoperiod, affects the utilization of T4. Development rates independent of the total amount of illumination, but related to daylength and light schedule, suggest interaction of light with an endogenous timing mechanism.
Changes in the Pattern of Intercellular Junctions during Early Embryogenesis of the Starfish, Asterias amurensis
Authors: KOMINAMI TETSUYA
Published: January 2005

Changes in the cellular adhesion pattern during the early embryogenesis of a starfish Asterias amurensis were examined using carboxyfluorescein (CF) dye as a probe. CF that was injected into one of the blastomeres at the 2‐ or 4‐cell stage was in all cases restricted to the progeny cells of the CF‐labelled blastomere. With the advancement of gastrulation, however, the injected dye was distributed not only to the progeny of the labelled blastomere, but also to cells that originated from non‐injected blastomeres. At the beginning of mesenchyme cell release, the injected dye spread uniformly to most cells comprising the embryo. When one of the blastomeres situated in the vegetal hemisphere of an 8‐cell embryo was labelled, the resulting embryo showed more intense fluorescence in the cells surrounding the archenteron than in the ectodermal layer, suggesting that the cells in ectodermal layer became associated more intimately or earlier than those surrounding the archenteron. Likewise, in double embryos formed by combining two denuded eggs, in which one egg had been labelled with CF, dye spread was observed when the ectodermal layer began to expand. The intercellular spread of CF dye in starfish embryo suggests that there is a dramatic change in the cellular adhesion pattern during the course of gastrulation.
Differentiation Expression in Blastomeres of Cleavage‐Arrested Embryos of the Ascidian Halocynthia roretzi
Authors: NISHIKATA TAKAHITO , MITA‐MIYAZAWA IZUMI , SATOH NORIYUKI
Published: January 2005

The question whether two or more different genetic programs are expressed in the common cytoplasm of single blastomeres or the expression of one genetic program somehow excludes expression of the other, was analyzed by assessing the occurrence of a muscle‐specific and two epidermis‐specific antigens in cleavage‐arrested blastomeres in early embryos of the ascidian Halocynthia roretzi. Blastomeres which had been arrested in 1‐ to 4‐cell stages expressed only the epidermis markers. Arrested 8‐cell to 32‐cell embryos produced both epidermis and muscle markers, but each cell expressed only one program of differentiation, even though some possessed the potential to express both. The differentiation expressions followed their cell lineages. These results indicate that at least in this experimental system differentiation markers of the two different cell‐types are expressed exclusively.

A distinct order was noticed in expression of the two epidermis markers in a single blastomeres; a marker is always superiorly expressed, whereas the other appears only when the superior marker is expressed.
1‐Methyl‐4‐thiohistidine and Glutathione in the Developing Embryo of the Sea Urchin, Paracentrotus lividus.
Authors: NARDI GIOVANNA , CIPOLLARO MARIA
Published: January 2005

4‐thiohistidines occur as free amino acids in the eggs of several marine organisms, in particulary relevant concentrations in the eggs of echinoderms. Since nothing is known about their biological role or biosynthesis and metabolic fate, we measured the concentration of 1‐methyl‐4‐thiohistidine together with the two most common small molecular weight thiols, glutathione and cysteine, during embryonic development of the sea urchin Paracentrotus lividus until the pluteus stage. The thiols were determined by high performance liquid chromatography as fluorescent derivatives of monobromobimanes. 1‐methyl‐4‐thiohistidine and glutathione are present until the pluteus stage with an approximate ratio of 2: 1. Cysteine was detected at the blastula stage and found to increase thereafter. 1‐methyl‐4‐thiohistidine was absent, or present in traces, in sperm and in somatic tissues of adults. It is concluded that 1‐methyl‐4‐thiohistidine is typical of eggs and embryos and may be metabolized during metamorphosis into an as yet unknown compound.
Regulation of the Dorsal Axial Structures in Cell‐Deficient Embryos of Xenopus laevis
Authors: Yuge Masahiro , Yamana Kiyotaka
Published: January 2005

To study the regulation of the dorsal axial structures, we removed the right animal dorsal and the right vegetal dorsal cells from an 8‐cell embryo of Xenopus laevis.

Most of the right dorsal cell‐deficient embryos developed to normally proportioned tailbud embryos. No detectable delay was observed in their development. Examinations of serial sections revealed that they had restored bilateral symmetry. The cell numbers of the somite and the notochord had recovered to more than 90% and 70%, respectively, those of controls. Since the right dorsal cell‐deficient embryo retained roughly three‐quarters of the prospective region for the somites and half of that for the notochord, respectively, the cell number was more than that expected from the remaining prospective regions. Cell lineage analyses showed that progeny of the right ventral cells had formed almost all of the right dorsal axial structures, which are normally formed by the progeny of the right dorsal cells. However, almost all the notochord cells had been derived from the remaining left dorsal cells.

These results indicate that some quantitative aspects of regulation as expressed in terms of the cell number were different between the two tissues examined.
Immunoelectron Microscopic Demonstration of Cortical Granule Lectins in Coelomic, Unfertilized and Fertilized Eggs of Xenopus laevis
Authors: Yoshizaki Norio
Published: January 2005

Immunoelectron microscopic studies demonstrated cortical granule lectins (CGLs) in coelomic, unfertilized and fertilized eggs of Xenopus laevis. An antiserum raised against purified cortical granule lectin 1 specifically reacted with the CGLs in immunoblotting and agar diffusion tests. When ultrathin sections were treated with the antiserum and protein A‐gold solution, gold particles, indicating antigenic sites, were seen over cortical granules of coelomic and unfertilized eggs, and over the perivitelline space, the vitelline coat and the condensed region of the fertilization layer of fertilized eggs. The pre‐fertilization layer immediately adjacent to the outer margin of the vitelline coat in unfertilized eggs was free from gold particles. These observations suggest that released CGLs permeate through the vitelline coat of fertilized eggs and interact with the pre‐fertilization layer mainly at the outer margin of the vitelline coat, resulting in formation of the fertilization layer which acts as a block to polyspermy.
Metamorphosis of Wing Motor System in the Silk Moth, Bombyx mori: Origin of Wing Motor Neurons
Authors: Tsujimura Hidenobu
Published: January 2005

The origin of the peripheral nerve and motor neurons that innervate the adult mesothoracic dorsal longitudinal muscles (DLMs) was examined in the silk moth, Bombyx mori. The anatomical features of the peripheral nerve and motor neurons were investigated by dissection, electron microscopy, and cobalt back‐fill staining at different pupal stages. These studies showed that the peripheral nerve (IIN1c) that innervates the adult DLMs originates from a branch (db branch) of the larval mesothoracic dorsal nerve that innervates the larval DLMs. During metamorphosis the larval nerve shortens or lengthens locally without change in its basic branching pattern, and the db branch moves towards the mesothoracic ganglion to become the IIN1c. All the adult DLM motor neurons are from larval ones. Nine of the 14 larval DLM motor neurons survive during metamorphosis to become adult DLM motor neurons, and 5 disappear in early pupal stages.
Sensory Projections from Ectopic Appendages in an insect: Inherent Specificity and Influence of Location
Authors: Sivasubramanian P. , Nässel D. R.
Published: January 2005

Peripheral and central pathfinding by sensory axons from appendages was investigated in the fly Sarcophaga bullata. (a) Supernumerary appendages (haltere, wing, antenna and leg) were produced by imaginal disc transplantation at various ectopic sites, (b) Leg neuropil was deafferented by leg disc extirpation and in its place another leg disc was implanted. (c) The basal stalk of a leg disc connecting it with the thoracic ganglion was transected. Using cobalt chloride and HRP backfilling methods the pathways taken by the afferents from these experimentally altered appendages was examined. The results indicate that the larval nerves and the imaginal disc stalks act as guides for growing axons to locate their correct entry sites within the ventral ganglion. In the absence of these guides the axons follow any peripheral nerve, such as abdominal nerve, and enter the ganglion at inappropriate sites. However, within the ganglion they take particular routes, almost identical to those taken by axons from in situ appendages suggesting the existance of some kind of a labelled pathway. Deafferentation does not make the leg neuropil more attractive to ingrowing ectopic sensory axons.
Evolutionary Conservation of the Larval Serotonergic Nervous System in a Direct Developing Sea Urchin
Authors: Bisgrove Brent W. , Raff Rudolf A.
Published: January 2005

Development of the larval serotonergic nervous system is examined by indirect immunofluorescence in two congeneric species of sea urchins that exhibit divergent embryonic and larval development. Heliocidar is tuberculata undergoes indirect planktotrophic development via a pluteus larva, whereas Heliocidaris erythrogramma develops directly, passing through a brief, highly derived lecithotrophic larval stage. We have cleared the opaque embryos of H. erythrogramma and discuss internal features of its development. The serotonergic nervous system of H. tuberculata arises in the apical plate at the end of gastrulation and develops into a bilaterally symmetric ganglion lying between the anterolateral arms in the preoral hood. Putatively homologous neurons appear at the apical end of the modified larva of H. erythrogramma well after the completion of gastrulation, coincident with development of the primary podia of the adult rudiment. The neurons form a bilaterally symmetric ganglion whose orientation relative to the vestibule is conserved with respect to that found in planktotrophic larvae. This allows us to define a left and right side for this larva which lacks external points of asymmetry such as a larval mouth. The alteration in the time of nervous system development in H. erythrogramma relative to that of H. tuberculata, and other indirect developers, implicates heterochronies in cellular differentiation as an important component of the evolution of direct development.
Synthesis of Proteins Enriched in Li+‐ Induced Vegetalized Embryos of Sea Urchin during Early Development
Authors: Komukai Masayuki , Iizuka Yasumoto , Yasumasu Ikuo
Published: January 2005

Sea urchin embryos were vegetalized by a pulse treatment with 60 mM Li+ between 2.5 hr and 6 hr after fertilization at 20°C. Normal and Li+ ‐treated embryos were exposed to [35S]‐methionine for 2 hr at various stages and [35S]‐labeled proteins were analyzed by two‐dimensional polyacrylamide gel electrophoresis (2D‐PAGE). On fluorograph of 2D‐PAGE at the pre‐hatching blastula stage, significant difference of labeled proteins between normal and vegetalized embryos was not observed in the range from neutral to acidic pH, but pls of several proteins were found to be shifted toward alkaline pH. At the mesechyme blastula stage, five major proteins [M.W. 36 K, 43 K (two species), 71 K and 150 K] were enriched in Li+‐treated embryos among a few hundreds of synthesized proteins. At the late gastrula stage, the labeling intensities of these proteins except for one of 43 K proteins increased remarkably in Li+‐treated embryos. Furthermore, two proteins (M.W. 105 K and 135 K) were also enriched in Li+‐treated embryos at this stage. At the prism stage, these proteins enriched in Li+‐treated embryos became hardly detectable, and the synthesis of at least four proteins (M.W. about 20 K, 41 K, 43 K and 200 K<) appeared to increase in normal embryos, but not in Li+‐treated embryos. Synthesis of proteins eniched in Li+‐treated embryos probably support endodermal cell differentiation.
Mechanism of Blastocyst Formation of the Mouse Embryo
Authors: Iwakura Yoichiro
Published: January 2005

During blastulation of mouse embryos, differentiation of the blastomeres occurs at the 16‐ to 32‐cell stage of the development. The differentiation processes seem to be controlled by extrinsic as well as intrinsic parameters, including distribution of signals neccessary for the induction of cell lineage specific proteins into blastomeres, and the induction of the synthesis of cell lineage specific proteins through cell interactions. These two processes are distinguished by treatment with various chemicals and by mutations. For the distribution of the signal molecules among blastomeres, cell polarization occurring at the 8‐cell stage seems to be important, while the activation of the cell lineage specific genes, cell‐interactions mediated by cell surface glycoproteins are suggested to play an important role.
Marked Alteration at Midblastula Transition in the Effect of Lithium on Formation of the Larval Body Pattern of Xenopus laevis
Authors: Yamaguchi Yoshimasa , Shinagawa Atsunori
Published: January 2005

Embryos of Xenopus laevis were exposed to 0.4 M LiCl for 5 min at various stages of development. The effect of lithium on the larval body pattern could be detected from the 2‐cell to the late gastrula stage, but changed from reduction of posterior structures (“anteriorization”) to reduction of anterior structures (“posteriorization”) just after the 12th cleavage, the time of midblastula transition (MBT). Temporal coincidence of MBT with alteration of the effect of lithium was observed even with embryos derived from half‐egg fragment, in which MBT occurs just after the 11th cleavage. These results suggest the existence of a mechanism for formation of the basic plan of the larval body whose function changes at MBT. Combinations of the pre‐ and post‐MBT exposures to lithium induced marked posteriorization in most larvae, indicating that the basic plan is not irreversibly determined until MBT, but is fixed during post‐MBT stages.
Phorbol Ester Induces Elevation of the Vitelline Coat of Eggs of the Ascidian Halocynthia roretzi
Authors: Yokosawa Hideyoshi , Toratani Satoshi , Inadome Yumi , Ishii Shin‐ichi
Published: January 2005

Elevation of the vitelline coat of eggs of the ascidian, Halocynthia roretzi, was induced by 12‐O‐tetradecanoylphorbol‐13‐acetate or phorbol‐12, 13‐didecanoate, but not by their 4‐epimers. After elevation of the vitelline coat in this way, eggs were unable to undergo cleavage on addition of sperm. This elevation of the vitelline coat by phorbol esters was inhibited by specific inhibitors of trypsin‐like enzyme, calmodulin, phospholipase A2, and protein kinase C. In association with elevation of the vitelline coat, a trypsin‐like enzyme was released from the eggs. The properties of this enzyme were similar to those of the enzyme released by calcium ionophore, which also induced elevation of the vitelline coat, suggesting that similar exocytosis of intracellular granules occurred in both cases. Calmodulin, possibly involved in the elevation process, was isolated from eggs and characterized.