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PubMed2003

Extra-embryonic function of Rb is essential for embryonic development and viability.

The retinoblastoma (Rb) gene was the first tumour suppressor identified. Inactivation of Rb in mice results in unscheduled cell proliferation, apoptosis and widespread developmental defects, leading to embryonic death by day 14.5 (refs 2-4). However, the actual cause of the embryonic lethality has not been fully investigated. Here we show that loss of Rb leads to excessive proliferation of trophoblast cells and a severe disruption of the normal labyrinth architecture in the placenta. This is accompanied by a decrease in vascularization and a reduction in placental transport function. We used two complementary techniques-tetraploid aggregation and conditional knockout strategies-to demonstrate that Rb-deficient embryos supplied with a wild-type placenta can be carried to term, but die soon after birth. Most of the neurological and erythroid abnormalities thought to be responsible for the embryonic lethality of Rb-null animals were virtually absent in rescued Rb-null pups. These findings identify and define a key function of Rb in extra-embryonic cell lineages that is required for embryonic development and viability, and provide a mechanism for the cell autonomous versus non-cell autonomous roles of Rb in development.

Animals↗

PubMed1998

Tetranectin is a novel marker for myogenesis during embryonic development, muscle regeneration, and muscle cell differentiation in vitro.

Tetranectin, a plasminogen-binding protein with a C-type lectin domain, is found in both serum and the extracellular matrix. In the present study we report that tetranectin is closely associated with myogenesis during embryonic development, skeletal muscle regeneration, and muscle cell differentiation in vitro. We find that tetranectin expression coincides with muscle differentiation and maturation in the second half of gestation and further that tetranectin is enriched at the myotendinous and myofascial junctions. The tetranectin immunostaining declines after birth and no immunostaining is observed in normal adult muscle. However, during skeletal muscle regeneration induced by the intramuscular injection of the myotoxic anesthetic Marcaine, myoblasts, myotubes, and the stumps of damaged myofibers exhibit intense tetranectin immunostaining. Tetranectin is also present in regenerating muscle cells in dystrophic mdx mice. Murine C2C12 myogenic cells and pluripotent embryonic stem cells can undergo muscle cell differentiation in vitro. Tetranectin is not expressed in the undifferentiated myogenic cells, but during the progression of muscle differentiation, tetranectin mRNA is induced, and both cytoplasmic and cell surface tetranectin immunostaining become apparent. Finally, we demonstrate that while tetranectin mRNA is translated to a similar degree in developing limbs and lung, the protein does not seem to be tissue associated in the lung as it is in the limbs. This indicates that in some tissues, such as the limbs, tetranectin may function locally, whereas in other tissues, such as the lung, tetranectin production may be destined for body fluids. In summary, these results suggest that tetranectin is a matricellular protein and plays a role in myogenesis.

Animals↗

PubMed1955

Relationship between the activity of the succinoxidase system and the rate of oxygen consumption during the embryonic development of the mealworm, Tenebrio molitor Linnaeus.

1. Readings were made on the rates of oxygen consumption and on the activities of the succinoxidase system of eggs of the mealworm for each day of embryonic development at 30 degrees C. 2. The rate of oxygen consumption, expressed as microliters/50 eggs/hour, was low (4.89) in newly laid eggs. It rose to 7.41 during the next 24 hours, remained at this level for the next 2 days, and then increased during the remainder of the embryonic period reaching a high value of 14.79 at the time of hatching. 3. The activity of cytochrome oxidase in eggs from newly emerged beetles, expressed as Delta log [Cy Fe(++)]/minute, remained at a value of 0.042 during the first half of the embryonic period, increasing to 0.233 during the latter half of this period. 4. The activity of succinic dehydrogenase showed the same series of changes except at much lower values. Expressed as Delta log [Cy Fe(+++)]/minute, they ranged from 0.010 in the newly laid egg to 0.034 at the end of the embryonic period. 5. The activity of cytochrome oxidase of the egg was found to decrease with parental age. Eggs from newly emerged beetles had activity values considerably higher than those of beetles 6 or 8 weeks after emergence. However, no comparable changes were noted in the activity of succinic dehydrogenase or in the rate of oxygen consumption. These observations suggest that cytochrome oxidase is not a rate-limiting enzyme in the respiratory metabolism of the mealworm egg.

Animals↗

PubMed1994

Molecular biology of embryonic development: how far have we come in the last ten years?

The successes of molecular developmental biology over the last ten years have been particularly impressive in those directions favored by its major paradigms. New technologies have both guided and been guided by the progress of the field. I review briefly some of the major insights into embryonic development that have derived from research in four specific areas: early embryogenesis of various forms; 'pattern formation'; evolutionary conservation of regulatory elements; and spatial mechanisms of gene regulation. There remain many major problem areas, some of which may require new orientations to solve.

Animals↗

PubMed1987

Saturable accumulation of retinoic acid in neural and neural crest derived cells in early embryonic development.

Retinoic acid (RA) binds to a cytosolic protein distinguishable from the cellular retinol (R) binding protein. Recent studies, showing an influence by R and RA on genomic expression, suggest an interaction with the cell nucleus mediated by the specific binding proteins in a manner resembling that of steroid hormones. RA can irreversibly stimulate in vitro differentiation of teratocarcinoma cells and support early embryonic development in vitamin A depleted animals. This study demonstrates a saturable, highly specific and regional accumulation of RA in the neuroepithelium and developing CNS that occurs in early but not in late fetal development in the mouse. The results suggest that a binding protein, or some other cellular mechanism for accumulation of RA is expressed in the neural cells only during restricted periods of development. High levels are recorded also in regions where cranial neural crest cells are known to migrate, and later in the visceral arches and maxillary areas, the mesenchyme of which is known to be partly derived from migrating cranial neural crest cells. The specific accumulation of RA in embryonic neural and cranial neural crest cells is in line with animal experiments and human clinical data, showing that retinoids specifically impair CNS, eye, ear, and facial development.

Animals↗

PubMed1998

Effect of insulin-like growth factor I and its interaction with gonadotropins on in vitro maturation and embryonic development, cell proliferation, and biosynthetic activity of cumulus-oocyte complexes and granulosa cells in buffalo.

In this study we have examined the effect of insulin like growth factor I (IGF-I) and its interaction with gonadotropins in the presence or absence of granulosa cell coculture on in vitro oocyte maturation (IVM) and their subsequent embryonic development in buffalo. We also have examined the role of IGF-I alone or in combination with gonadotropins on DNA synthesis, steroidogenesis, and protein synthesis of cumulus-oocytes complexes (COCs) and granulosa cells. Results showed that IGF-I stimulates oocytes maturation in a dose-dependent manner, with maximal effect at a dose of 100 ng/ml (P < 0.05). IGF-I showed positive interaction with follicle-stimulating hormone (FSH) in the presence or absence of granulosa cells on meiotic maturation and synergistically enhanced DNA synthesis, protein synthesis, and steroidogenesis in the presence of granulosa cells. This synergistic effect is mainly caused by the increase of IGF-I receptors in granulosa cells by FSH, as evident by [125I]IGF-I binding study. Luteinizing hormone (LH), however, was found to suppress IGF-I and IGF-I + FSH stimulated oocyte maturation. Addition of LH to cultures containing IGF-I + FSH, on the contrary, caused a significant increase in oocyte maturation when cocultured with granulosa cells. Addition of IGF-I during IVM significantly improve cleavage and blastocyst development rate over the control group. However, there was no cumulative effect when IGF-I and gonadotropins were present together. Addition of granulosa cells during IVM, however, enhanced blastocyst development in the IGF-I + FSH and IGF-I + FSH + LH groups. Our results demonstrated that IGF-I is a major follicular factor responsible for stimulating oocyte maturation in the buffalo. Interaction between IGF-I and FSH suggests that they seem to act synergistically as an autocrine and paracrine regulator of granulosa cells and therefore together promote mitosis, steroidogenesis, and protein synthesis.

Animals↗

PubMed1994

Actions of selected proteins, peptides and amino acid derivatives on mouse embryonic development in vitro.

1. The actions of various compounds with antiproliferative and/or immunomodulatory activities including the ribosome-inactivating protein gelonin, the tetrapeptide tuftsin, the opioid peptide leucine-enkephalin, the antireproductive tripeptide Thr-Ser-Lys, the melatonin analog 6-methoxy-2-benzoxazolinone, and the amino acid derivatives 5-hydroxytryptamine and oxalysine on mouse embryonic development and organogenesis in vitro were investigated. 2. The various compounds were tested up to a concentration of 300 micrograms/ml. It was found that only 6-methoxy-2-benzoxazolinone, a derivative of tryptophan, produced an increase in the number of abnormal embryos and reductions in the final somite numbers and axial lengths of embryos. 3. 6-Methoxy-2-benzoxazolinone treatment also resulted in an increased incidence of abnormal morphogenesis of various organ primordia, including abnormal yolk sac circulation, twisting of body axis, absence of forelimb bud and opening of cranial neural tube.

Amino Acid Sequence↗

PubMed1986

The effect of diamino diphenyl sulfone on the embryonic development of eggs from the sea urchin (Lytechinus variegatus).

Diamino diphenyl sulfone (DDS), a chemotherapeutic compound used in the treatment of leprosy, was studied with regard to its effects on the embryonic development of eggs from the sea urchin Lytechinus variegatus. DDS disturbs the normal development of fertilized eggs by interfering with the mitotic apparatus and producing spheroid-shaped bodies shown to be aster-like bodies by staining techniques. A typical colchicine effect (formation of kidney-shaped cells) was also demonstrated.

Animals↗

PubMed1999

Expression of the 100-kDa neurotensin receptor sortilin during mouse embryonal development.

Recently, sortilin a non G-protein-coupled receptor has been identified as the 100-kDa neurotensin receptor. In this paper we describe the expression of its gene during mouse embryonal development. We show that the nervous system is the main location of sortilin gene expression and that with ongoing development the forebrain exhibits the highest accumulation of transcripts.

Adaptor Proteins, Vesicular Transport↗

PubMed1980

[Cytological study of the post-embryonic development of the digestive gland of Sepia officinalis L. Mollusca : Cephalopoda (author's transl)].

A histological and ultrastructural study of the development of the digestive gland of Sepia officinalis L. was carried out on young Sepia reared in the laboratory, during the first month of post-embryonic life. The increasing complexity of the histological structure of the gland is related to the successive appearance of several cell types : immature cell, synthetizing cell, mature digestive cell ("cellule à boules"), and resting cell. These types are, in fact, just the evolutive stages of the same cell, the digestive cell. The sequence of appearance of the different cell types and the changes occurring in feeding can be used to define three stages in the post-embryonic development of the Sepia officinalis L. digestive gland : a multiplication stage (from hatching to the 5th day), a maturation stage (5th to 30th day), and adult stage (after the first month of post-embryonic life). These stages are identical to the three periods previously described by Richard and Decleir (1969) in the life of Sepia.

Animals↗

PubMed1995

[The effect of high gravity on embryonic development in birds].

An experiment was conducted on Japanese quail and hen hatching eggs that had been incubated, and the embryos were subjected to hypergravitation of 10 G for 10 min on days 1 to 9 of embryonic development. Both the experimental group and the control contained each 20 hatching eggs every day of the experiment (360 eggs in total). A centrifuge of the diameter 1,300 mm was used to create overload (hypergravitation) at the speed of 118 rotations per min. Tab. I shows the layout of the experiment. Embryonic mortality in Japanese quail was investigated during incubation by egg candling on days 1 to 8 and 9 to 14 while suffocated embryos were investigated on days 15 to 17. As for chicks, embryonic mortality was determined by egg candling on days 1 to 8 and 9 to 18, suffocated embryos were determined on days 19 to 21. After incubation was terminated, hatchability in per cent of the fertilized eggs was determined. The results were processed in two stages of development: the first stage days 1 to 5, the second stage days 6 to 9. As can be seen in Fig. 1, hypergravitation did not influence the hatchability of quail eggs in the first stage. But this experimental treatment resulted in a steep fall of hatchability in the second stage of observation in comparison with the control group (the difference is significant P < 0.01). Fig. 2 shows hatchability.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Ovulation, fertilization and early embryonic development in the bitch (Canis familiaris).

Using circulating plasma hormone estimations, ovulation was monitored in bitches. The results obtained indicate that the timing of ovulation bears little relationship to alterations in sexual behaviour. The bitches were killed and reproductive tracts were removed at various intervals after ovulation and ova or embryos were recovered. The embryo stages were assessed visually and some were investigated histologically. Embryonic development, to early blastocyst stage, took place within the oviducts during the first 12 days after ovulation and there was a marked increase in size between the early and late blastocyst. A culture system using cells from the uterine tube supported the development of one 1-cell embryo to the morula stage.

Animals↗

PubMed1996

The methyl-CpG binding protein MeCP2 is essential for embryonic development in the mouse.

Vertebrate genomes are heavily methylated at cytosines in the sequence CpG. The biological role of this modification is probably mediated by DNA binding proteins that are either attracted to or repelled by methyl-CpG. MeCP2 is an abundant chromosomal protein that binds specifically to methylated DNA in vitro, and depends upon methyl-CpG for its chromosomal distribution in vivo. To assess the functional significance of MeCP2, the X-linked gene was mutated in male mouse embryonic stem (ES) cells using a promoterless gene-targeting construct containing a lacZ reporter gene. Mutant ES cells lacking MeCP2 grew with the same vigour as the parental line and were capable of considerable differentiation. Chimaeric embryos derived from several independent mutant lines, however, exhibited developmental defects whose severity was positively correlated with the contribution of mutant cells. The results demonstrate that MeCP2, like DNA methyltransferase, is dispensable in stem cells, but essential for embryonic development.

Animals↗

PubMed1997

Polysaccharopeptide from the mushroom Coriolus versicolor possesses analgesic activity but does not produce adverse effects on female reproductive or embryonic development in mice.

1. Coriolus versicolor polysaccharopeptide has been reported to exert immunomodulatory and antitumor actions. The present study showed that it exhibits analgesic activity in the hot-plate test upon intraperitoneal administration to ICR mice. 2. It did not affect ovarian steroidogenesis, ovulation and midterm gestation in mice. It did not exert an adverse effect on mouse embryonic development either, as evidenced by the lack of an effect on somite number, axial length and the incidence of abnormalities in heartbeat, yolk sac circulation, optic vesicle, otic vesicle, shape of body axis, forelimb buds, branchial apparatus, cranial neural tube and head size. 3. Its analgesic activity would add to its attribute as an immunomodulatory and antitumor drug.

Analgesics↗

PubMed1993

Cloning and expression of cDNA encoding Xenopus laevis bone morphogenetic protein-1 during early embryonic development.

The Xenopus laevis DNA fragment encoding a protein homologous with human bone morphogenetic protein-1 (BMP-1) was amplified by polymerase chain reaction (PCR) from cDNA derived from stage 26 (st.26) embryonic RNA. Subsequently this fragment was used as a probe to isolate cDNA clones by screening of a X. laevis st.24 embryonic cDNA library. Two partial clones (22 and 63) were obtained and the missing 5'-end of the clone 22 was extended by the anchored PCR technique. The nucleotide sequence of the resulting clone (22AN) contained an open reading frame coding for a protein with 707 deduced amino acids. Three sizes of mRNA (2.9, 5.2 and 6.6 kb) were detected in blastula (st.9) and early gastrula (st.10) embryos, and in hatched tadpole (st.40), but little or no expression was observed in morula (st.7) and late gastrula (st.12) embryos, suggesting a physiological role(s) of X.laevis BMP-1 in normal embryonic development.

Amino Acid Sequence↗

PubMed1989

In vivo administration of allopurinol affects ovulation and early embryonic development in rabbits.

The potential role of the hypoxanthine-xanthine oxidase system in human chorionic gonadotropin-induced ovulation, nuclear maturation, and preimplantation development was investigated in the rabbit by use of the xanthine oxidase inhibitor allopurinol. Allopurinol (50 mg/kg) or vehicle was injected, followed by human chorionic gonadotropin (100 IU). Administration of inhibitor or vehicle was repeated 3 hours later. Ovaries and ovulated ova were inspected 12 or 24 hours after human chorionic gonadotropin administration for follicle rupture, cumulus dispersal, and nuclear maturation. Ova were inseminated in vitro and assessed for development to the blastocyst stage, up to 96 hours after insemination. Allopurinol significantly reduced ovulatory efficiency, defined as the percent of large follicles that ovulate, and decreased the percent of ova with cumulus dispersal. Allopurinol significantly inhibited morula and blastocyst formation. These data suggest that the xanthine oxidase system may play a role in ovulation and early embryonic development.

Allopurinol↗

PubMed1998

Immunochemical detection of arylamine N-acetyltransferase during mouse embryonic development and in adult mouse brain.

Arylamine N-acetyltransferases (NATs) are important in susceptibility to xenobiotic-induced disorders (e.g., drug-induced autoimmune disease, bladder cancer), but their role in endogenous metabolism is yet to be elucidated. The discovery that human NAT1 acts upon p-aminobenzoylgluatamate (p-ABG) to generate p-acetamidobenzoylglutamate (p-AABG), a major urinary metabolite of folic acid, suggests that human NAT1 may play a role in folic acid metabolism and hence in the normal development of the neural tube. In this study we examined the distribution of NAT in neuronal tissue from adult mice and embryos. Immunohistochemical staining of the adult mouse cerebellum revealed NAT2 (the mouse homologue of human NAT1) expression in the cell bodies and dendrites of Purkinje cells and in the neuroglia of the molecular layer. In embryos, NAT2 was detected in developing neuronal tissue on days 9.5, 11.5, and 13.5. It was expressed intensely in the nerual tube around the time of closure. The level of expression subsequently declined in the neuroepithelium but increased in glial cells. In addition, NAT2 was detected in the developing heart and gut. These findings demonstrate that the embryo itself expresses an enzyme which is involved in the metabolism of folic acid, so that the role played by both mother and embryo must be considered when examining the role of folic acid in embryonic development. These findings imply that polymorphisms in NAT genes could play a role in determining susceptibility to neural tube defects (NTD) and orofacial clefting, developmental disorders which can be prevented by dietary administration of folic acid.

Animals↗

PubMedDate not supplied

Embryonic development of mouse external genitalia: insights into a unique mode of organogenesis.

The mammalian external genitalia are specialized appendages for efficient copulation, internal fertilization and display marked morphological variation among species. In this paper, we described the embryonic development of mouse genital tubercle (GT), an anlage of the external genitalia utilizing the scanning electron microscope (SEM) analysis. It has been shown that the Distal Urethral Epithelium (DUE) may fulfill an essential role in the outgrowth control of the GT. Our present SEM analysis revealed a small distal protrusion at the tip of the GT of normal embryos as well as some morphological differences between male and female embryonic external genitalia. Previous analysis shows that the teratogenic dose of Retinoic Acid (RA) induces a drastic marformation of the urethral plate, but not gross abnormalities for GT outgrowth. Interestingly, a small distal protrusion at the tip of GT was clearly observed also after RA treatement. Furthermore, we showed that treatment with anti-androgen flutamide resulted in the demasculinization of the GT in males. The unique character of GT development and the sexual dimorphism are discussed.

Animals↗