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PubMed1993

The regulation of myogenin gene expression during the embryonic development of the mouse.

The myogenic program can be activated in cultured cells by each of four basic-helix-loop-helix (bHLH) transcription factors, the expression of which is strictly controlled, both temporally and spatially, during embryonic development. To begin to understand the mechanisms by which these regulators are regulated themselves, we have used transgenic animals to define the minimal sequences required for the complete recapitulation of the temporal and spatial expression pattern of the myogenin gene during embryogenesis. We show that this can be achieved with only 133 bp of 5'-flanking DNA and identify two essential motifs, which are consensus binding sites for the bHLH proteins and for the proteins of the RSRF family. We show further that these sequences, when juxtaposed to a heterologous promoter, are capable of imposing the myogenin expression pattern. We conclude that the proper regulation of myogenin requires a bHLH protein, most probably Myf-5, the only myogenic bHLH factor known to be present in the embryo at the time that myogenin is activated, and an RSRF-like binding activity. Furthermore, the expression pattern of a mutant myogenin promoter lacking the RSRF site reveals the existence of at least two populations of cells within the myotomes and of novel rostrocaudal gradients of expression.

Animals↗

PubMed1995

Reduced levels of gamma-crystallin transcripts during embryonic development of murine Cat2nop mutant lenses.

BACKGROUND: From previous experiments it is known that the murine dominant cataract mutants carrying the gene Cat2 have a decreased content of gamma-crystallin-specific transcripts in the juvenile lens, when the cataract is completely expressed. Moreover, the mutant locus has been mapped recently to chromosome 1, closely linked to the gamma E-crystallin gene (map distance 0.3 +/- 0.3 cM). In the present paper we describe the phenotypic changes and the gamma-crystallin expression in embryonic lenses of the Cat2nop mutants as an example for the Cat2 allelic series. METHODS: The technique of in situ hybridization was applied using a probe from the murine gamma D-crystallin gene, and, for control, from the murine alpha A-crystallin gene. Simultaneously, a series of lens sections was examined histologically. RESULTS: The presence of gamma-crystallin mRNA was demonstrated from embryonic day 13.5 (E13.5) onward, but in the mutants to a lower extent than in the wild-type lenses. However, the first morphological abnormality in the mutant lenses was observed as swelling of lens fibers at day E15.5. Progressive degeneration of the lens core followed, leading to a cataracta immatura. CONCLUSION: The reduced level of gamma-crystallin transcripts is the first alteration observable during the embryonic development of the Cat2 mutant lenses: it precedes the morphological changes. This result represents an additional line of argument that the gamma-crystallin genes may be the target of the mutation in the Cat2 mice.

Alleles↗

PubMedDate not supplied

Effects of N,N-dimethylnitrosamine (DMNA) on in vitro oocyte maturation and embryonic development of fertilized eggs of carp (Cyprinus carpio L.) kept in eutrophied ponds.

Toxic effects of N,N-dimethylnitrosamine (DMNA) at doses of 100 or 500 micrograms l-1 on in vitro carp oocyte maturation (steroidogenesis), embryonic development and hatching of larvae (obtained as a result of artificial spawning of females kept for four seasons in normal and eutrophicated ponds) were investigated. There were no significant effects of DMNA on oocyte maturation and steroidogenesis during 24 h of incubation. The DMNA decreased the hatching of fertilized eggs derived from control females. This decrease reached a level of significance at a dose of 500 micrograms l-1. However, the effect of long-term exposure of female fish to eutrophied water was very much higher. The trend of the in vitro DMNA effect was the same, but it did not reach a statistically significant level. The results suggest that nitrosamines, through their effect on egg hatchability, may reduce fish populations along with increasing aquatic eutrophication.

Animals↗

PubMed2000

Role of cholesterol in embryonic development.

We showed previously that 3 distal inhibitors of cholesterol synthesis are highly teratogenic in rats. AY 9944 and BM 15766 inhibit 7-dehydrocholesterol reductase, which catalyzes the last step of cholesterol synthesis, and triparanol inhibits Delta(24)-dehydrocholesterol reductase, which catalyzes the last step in another pathway. These molecules cause holoprosencephalic brain anomalies. Under certain experimental conditions, other anomalies (of the limbs and male genitalia) are also observed. Assays performed by gas chromatography-mass spectrometry (GC-MS) show hypocholesterolemia and an accumulation of precursors. These data indicate that this animal model can be considered a model of Smith-Lemli-Opitz syndrome. Smith-Lemli-Opitz syndrome is a recessive autosomal genetic disease characterized by malformations (microcephaly, corpus callosum agenesis, holoprosencephaly, and mental retardation), male pseudohermaphroditism, finger anomalies, and failure to thrive. The syndrome has been attributed to a deficit in 7-dehydrocholesterol reductase. As assayed by GC-MS, the sterol status of these patients indicates severe hypocholesterolemia and an accumulation of precursors: 7-dehydrocholesterol, 8-dehydrocholesterol, and oxidized derivatives. The presence of 7-dehydrocholesterol in the serum of patients is pathognomonic of the disease. The developmental gene Shh (sonic hedgehog) plays a key role in brain, limb, and genital development; it was shown recently that the Shh protein has to be covalently linked to cholesterol to be active. This is the first time that a posttranslational function has been attributed to cholesterol. There is an obvious relation between Shh dysfunction and the malformations observed in our experiments and in patients with Smith-Lemli-Opitz syndrome. However, the exact relation remains to be clarified. It is clear, however, that the role of cholesterol in embryonic development must be taken into account.

Animals↗

PubMed2004

Sources and timing of calcium mobilization during embryonic development of the corn snake, Pantherophis guttatus.

Embryos of oviparous Reptilia (=turtles, lepidosaurs, crocodilians and birds) extract calcium for growth and development from reserves in the yolk and eggshell. Yolk provides most of the calcium to embryos of lizards and snakes. In contrast, the eggshell supplies most of the calcium for embryonic development of turtles, crocodilians and birds. The yolk sac and chorioallantoic membrane of birds recover and transport calcium from the yolk and eggshell and homologous membranes of squamates (lizards and snakes) probably transport calcium from these two sources as well. We studied calcium mobilization by embryos of the snake Pantherophis guttatus during the interval of greatest embryonic growth and found that the pattern of calcium transfer was similar to other snakes. Calcium recovery from the yolk is relatively low until the penultimate embryonic stage. Calcium removal from the eggshell begins during the same embryonic stage and total eggshell calcium drops in each of the final 2 weeks prior to hatching. The eggshell supplies 28% of the calcium of hatchlings. The timing of calcium transport from the yolk and eggshell is coincident with the timing of growth of the yolk sac and chorioallantoic membrane and expression of the calcium binding protein, calbindin-D28K, in these tissues as reported in previous studies. In the context of earlier work, our findings suggest that the timing and mechanism of calcium transport from the yolk sac of P. guttatus is similar to birds, but that both the timing and mechanism of calcium transport by the chorioallantoic membrane differs. Based on the coincident timing of eggshell calcium loss and embryonic calcium accumulation, we also conclude that recovery of eggshell calcium in P. guttatus is regulated by the embryo.

Animals↗

PubMed1987

Dorsal and neural expression of a tyrosine kinase-related Drosophila gene during embryonic development.

Sequence analysis of an embryonic transcript of Drosophila predicts a tyrosine protein kinase-related gene. The prediction is based on several protein domains that are homologous to the functional domains of kinase-related oncogenes and several serine, threonine, and tyrosine protein kinases. For this reason, we named this gene Drosophila tyrosine kinase related (dTKR). dTKR maps into chromosome band 2R 60F1. It is initially expressed at blastoderm stage, showing transient transcript accumulations at dorso-lateral positions of the embryo and differences along its longitudinal axis. At later stages of embryogenesis, dTKR transcripts are found exclusively in neural anlagen. Both the region-specific pattern of expression and the putative kinase function are consistent with the suggestion of a regulatory role for this gene during development, which remains to be elucidated.

Amino Acid Sequence↗

PubMed1982

Abnormal embryonic development induced by antiserum: a rapid method to isolate the responsible galactoprotein antigens.

It has been well established that heterologous antiserum against whole rat kidney homogenate when injected into pregnant rats during the organogenetic period may induce abnormal embryonic development. A one-step rapid method has been developed to isolate the responsible rat renal antigens by lectin-affinity chromatography using soy bean agglutinin (SBA) or ricinus communis agglutinin (RCA120). The purified antigens appeared to be galactoproteins with terminal nonreducing D-galactose and/or N-acetyl-D-galactosamine. Rabbit antisera produced against the galactoproteins were potent teratogenic agents.

Animals↗

PubMed1984

Mini-review: hyaluronidases in early embryonic development.

The foregoing discussion indicates that hyaluronidases probably play an important part in the control of development. In morphogenesis, they may be involved in epithelial-mesenchymal inductive interactions, in non-malignant invasion when one tissue displaces another in normal development, in controlling cell movements, in modulating changes of shape of cells and sheets of cells, in controlling the permeability of tissues and regulating the ionic environment within the embryo. There is also evidence indicating that hyaluronidases are involved in the initiation of cytodifferentiation pathways, perhaps via direct or indirect effects upon the cell division cycle and histone-DNA interactions. The evidence presented indicates that hyaluronidases are important repeatedly at different stages of embryonic development and differentiation, where periods of high activity follow others of reduced activity in localized regions of the embryo. Some new results were also presented, showing the presence of different hyaluronidase activities at early stages of chick embryo development. The highest levels of hyaluronidase activity were found in the primitive streak and mesoderm.

Amphibians↗

PubMed1998

Murine branched chain alpha-ketoacid dehydrogenase kinase; cDNA cloning, tissue distribution, and temporal expression during embryonic development.

These studies were designed to demonstrate the structural and functional similarity of murine branched chain alpha-ketoacid dehydrogenase and its regulation by the complex-specific kinase. Nucleotide sequence and deduced amino acid sequence for the kinase cDNA demonstrate a highly conserved coding sequence between mouse and human. Tissue-specific expression in adult mice parallels that reported in other mammals. Kinase expression in female liver is influenced by circadian rhythm. Of special interest is the fluctuating expression of this kinase during embryonic development against the continuing increase in the catalytic subunits of this mitochondrial complex during development. The need for regulation of the branched chain alpha-ketoacid dehydrogenase complex by kinase expression during embryogenesis is not understood. However, the similarity of murine branched chain alpha-ketoacid dehydrogenase and its kinase to the human enzyme supports the use of this animal as a model for the human system.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed2003

Dmaf, a novel member of Maf transcription factor family is expressed in somatic gonadal cells during embryonic development and gametogenesis in Drosophila.

Members of the maf gene family encode basic/leucine zipper transcription factors and play important roles during cell differentiation and organogenesis in vertebrate development. In this study, we show that the maf family is evolutionarily conserved and that the Drosophila maf (Dmaf) gene is expressed in somatic gonadal cells. During embryonic development, Dmaf mRNA is detected in somatic gonadal precursor cells emerging from dorsolateral mesoderm. Relatively weak expression is also observed in subset of neuronal cells in the central nervous system. In adult flies, Dmaf is expressed in somatic gonadal cells surrounding developing oocytes and spermatocytes. These results suggest a specific function for Dmaf in gonadal development, including migration and differentiation of primordial germ cells.

Amino Acid Sequence↗

PubMed1990

Effects of estradiol and progesterone on early embryonic development in aging rats.

Regularly cyclic, middle-aged female rats exhibit a decreased incidence of fertility, and those females that are fertile produce small litters. These decreases in fertility and litter size are associated with reduced numbers of normal blastocysts formed and implanted, suggesting that pre- and/or peri-implantation failures may be the causes for these aging-related reproductive declines. The present study examined the relationships and influence of circulating estradiol (E2) and progesterone (P) levels on early embryonic development and implantation in middle-aged rats. Serial blood samples obtained from cannulated, middle-aged pregnant rats revealed minor decreases in plasma P and increases in E2 levels during Days 2-4 of pregnancy, compared to young pregnant rats, resulting in significantly (p less than 0.001) decreased plasma P/E2 ratios. These alterations in endogenous hormone secretion in middle-aged pregnant rats were associated with fewer normal blastocysts on Day 5 of pregnancy and reduced numbers of normally implanting embryos. Correlation analysis further revealed a significant (p less than 0.05) inverse relationship between mean circulating E2 levels and numbers of normal conceptuses on Day 12 of gestation. Moreover, s.c. administration of P implants (in Silastic) to middle-aged pregnant rats increased serum P levels by about 34-40 ng/ml, and significantly (p less than 0.05) reduced the incidence of abnormal embryos before implantation. In contrast, treatment with E2 minipumps produced a sustained rise in serum E2 (by about 7-15 pg/ml) and resulted in the complete absence of embryos in the reproductive tracts by Day 5 of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1988

Effects of zero to four copies of chromosome 15 on mouse embryonic development.

Intercrosses of mice doubly heterozygous for Rb(6.15)1A1d and Rb(4.15)4Rma (thus are characterized by monobrachial homology for chromosome 15) produced embryos with zero to four copies of chromosome 15 in their expected frequencies at the first cleavage division. By 3 1/2 days' gestation, nullisomy 15 embryos were missing. At 8 1/2 to 9 1/2 days, no monosomy 15 embryos were found, although trisomy 15 and tetrasomy 15 embryos were still present in their expected numbers. Tetrasomics were more severely affected than trisomics at this gestational age; the former were severely retarded "streak" embryos, while the latter had open neural tubes and were 2/3 the size of euploid embryos. The functional activity of chromosomes during the embryonic development of autosomal aneuploids is discussed in light of these findings.

Animals↗

PubMed1993

Brain content of cGnRH I and II during embryonic development in chickens.

We used specific radioimmunoassays to measure chicken gonadotropin-releasing hormones I and II (cGnRH I and II) in extracts of chicken brain as a first step in determining whether these peptides may function identically during embryonic development in birds. In three experiments chicken embryo brains were removed at various times between Day 6 of incubation and hatching. In Experiment 3, the sex of embryos was identified by means of polymerase chain reaction amplification of a W chromosome-specific DNA sequence. Brain concentrations of cGnRH I increased sharply from Day 6 of incubation to Day 8, then decreased until Day 10 to Day 12, followed by an increase beginning on approximately Day 17 and continuing until hatch. In contrast, cGnRH II concentration remained low until about Day 14 of incubation, then increased progressively until, at hatch, brain content of cGnRH II was approximately 9 to 11 times that of cGnRH I. The difference in development pattern and total content of these peptides supports the view that any physiologic function they may have might be differentiated as early as Day 7 of incubation.

Animals↗

PubMed1994

Appearance and fate of a beta-galactanase, alpha, beta-galactosidases, heparan sulfate and chondroitin sulfate degrading enzymes during embryonic development of the mollusc Pomacea sp.

The characterization and properties of a beta-galactanase and alpha- and beta-galactosidases as well as heparan sulfate and chondroitin sulfate degrading enzymes which appear during the 15 days of the embryonic development of the mollusc Pomacea sp. is reported. The beta-galactanase, which appears around day 7 of development, was separated from alpha- and beta-galactosidase which emerge at day 1 and 4 after oviposition, respectively. The galactanase seems to be responsible for the degradation of an acidic beta-galactan (which is also synthesized by the eggs around day 5) to galactose and di- and tri-galactosides. Heparan sulfate appears around day 10 of development together with a heparan sulfate endoglucuronidase responsible for the degradation of its N-acetylated region. An alpha-N-acetylglucosaminidase and a beta-glucuronidase which act upon the N-acetylated fragments formed from heparan sulfate emerge around day 4 of development. Chondroitin sulfate and a chondroitin sulfate sulfatase emerge around day 9 of development whereas a beta-N-acetylgalactosaminidase and the beta beta-galactan, heparan and chondroitin sulfate, respectively. The possible role of these elements in the migration of mesenchymal cells, in the processes of cell-cell recognition and control of cell growth is discussed.

Acetylglucosaminidase↗

PubMed1994

Effects of persistent chlorinated hydrocarbons on fertility and embryonic development in the rabbit.

The commercial polychlorinated biphenyl (PCB) formulation Aroclor 1260 (4 mg/kg body weight), technical grade dichlorodiphenyltrichloroethane (DDT; 3 mg) and Lindane (gamma-hexachlorocyclohexane; 0.8 mg) were administered orally, either separately or in combination, to sexually mature female rabbits three times per week for 12-15 weeks. Oviductal and uterine luminal fluid, cleavage stage embryos (day 1 post coitum), blastocysts (day 6), fetuses, exocoelic fluid and placentae (day 11) were analysed, firstly for chlorinated hydrocarbon residues, and secondly for embryonic and fetal development. The doses applied were well tolerated by the treated animals. PCB and DDT accumulated in uterine secretions (day 6) but not in oviductal luminal fluid (day 1). Both chlorinated hydrocarbons were found in preimplantation blastocysts. Residues in day 11 fetuses were 16- (DDT) or 18-fold (PCB) higher than in day 6 blastocysts. Significant amounts were also detected in placental tissue and in exocoelic fluid. A specific accumulation of the highly chlorinated biphenyl congener no. 180 was noted in fetuses, placentae and exocoelic fluid. The clear accumulation of the chlorinated hydrocarbon compounds in luminal fluid and embryonic tissue is contrasted by rather weak effects on fertility. No statistically significant differences between treated animals and controls were observed for fertilization rate and pre- and post-implantation (up to day 11 post coitum) losses. However, in females exposed to PCB, a 20% higher loss of blastocysts was noticed, as compared with controls (P > 0.05). This effect was shown on day 6 of embryonic development and may be due to the embryotoxic activities of PCB.

Animals↗

PubMedDate not supplied

[The effect of a serotonin deficiency on mammalian embryonic development].

Administration of p-chlorophenylalanine to mouse females leading to a decreased level of endogenous serotonin during the early periods of pregnancy leads either to the absence of cytokinesis at the stage of zygote or to a sharp reduction of the cleavage rate in embryos up to its complete arrest. Formation of the blastocyst is impaired, although cavitation may take place at the same time as in the control. In the latter case, the blastocysts consist of a small number of large blastomeres, and the separation into trophoblast and inner cell mass is characteristically indistinct. Decreased level of endogenous serotonin at early postimplantation stages, i.e., during active organogenesis, leads to abnormalities in the development of brain, eyes, jaws, abnormalities of the brain vessels and vascular system of other body regions, which appear as numerous hematomas and hemostasis in vessels.

Abnormalities, Multiple↗

PubMed1997

First events in lipid absorption during post-embryonic development of the anterior intestine in gilt-head sea bream

Structural development and lipid absorption in anterior intestine of gilt-head sea bream Sparus aurata, were studied by light and electron microscopy during three stages of post-embryonic development: (1) the endotrophic period from hatching day (day 0) to mouth opening day (day 3); (2) the endo-exotrophic period from days 3 to 15; (3) the exotrophic period after day 15. During the 2 days following hatching, there was no trace of lipids in intestinal epithelia. Before mouth opening day, the first lipoproteic particles of endogenous origin appeared in entero-cyte endoplasmic reticulum and Golgi apparatus. During the endo-exotrophic period, lipoproteinogenesis increased weakly until day 9, and more greatly between days 9 and 15. It intensified at the beginning of the exotrophic period to remain at a high level afterwards. Until day 15, few transfers of lipoproteins to interenterocyte spaces occurred, whereas no lipoproteins were detectable in the blood flow from days 7 to 9. Their concentration increased slightly between days 9 and 15 to become intense afterwards. Lipid droplets appeared from day 7, and subsisted until the end of endo-exotrophic period. Possible relationships between very low density lipoproteins and chylomicron type lipoproteins and lipid droplets related to lipid excess in food are discussed.

Journal Article↗

PubMed1991

The transduction signalling protein Go during embryonic development of Drosophila melanogaster.

G proteins are heterotrimeric proteins that play a key role in signalling transduction conveying signals from cell surface receptors to intracellular effector proteins. In particulate preparations from Drosophila melanogaster embryos, only one substrate of 39,000-40,000 molecular weight could be ADP-ribosylated with pertussis toxin. This substrate reacted in immunoblotting and immunoprecipitation experiments with a polyclonal antibody directed against the carboxy-terminal sequence of the alpha subunit of the mammalian Go protein. The Drosophila Go alpha protein was present at all stages of embryonic development; however, its expression markedly increased after 10 h embryogenesis, a period of time during which there is an active development of axonal tracts. Immunolocalization on whole mount embryos has indicated that this protein is principally localized in the CNS and is mainly restricted to the neuropil without any labelling of the cell bodies. In contrast, all the axon tracts of the CNS appeared to be highly labelled. The distribution of the Go alpha protein was also examined in several neurogenic mutants. The Go alpha protein expression was not altered in any of them but the pattern of labelling was disorganized as was the neuronal network. These results suggest a possible role for the Go protein during axonogenesis.

Amino Acid Sequence↗