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PubMed1976

[Mutagenic effect of radiation on mice subjected to gamma irradiation during the embryonic period. I. Frequency of reciprocal translocations in the spermatocytes of mice subjected to gamma-irradiation at different stages of embryogenesis].

The frequency of reciprocal translocations was investigated in spermatocytes of mice gamma-irradiated at doses of 100 or 200 r at 4,5; 8,5; 10,5; 11,5 and 13,5 days of embryonic development, and in spermatocytes of adult males whose spermatogonia were irradiated. The cytological analysis of 41 males that were irradiated at a dose of 200 r at 4,5 days of embryogenesis showed that 2 males had a high frequency of reciprocal translocations in both testes (on the average 20,6 and 28,8%). In the testes of other males of this group translocations were not detected. It is highly probably that the testes of these 2 males were heterozygous for reciprocal translocations. The yield of reciprocal translocations in spermatocytes of males irradiated at 8,5--13,5 days of embryogenesis was very low, and was only 0,67 +/- 0,2 x 10(-5) on the average per 1 r per cell, whereas for adult mice it was 12,5 +/- 3,0 x 10(5) per 1 r per cell.

Animals↗

PubMed1999

Somatic embryogenesis of Echinodorus orisis L. and the kinetic changes of the endogenous hormones contents during the embryogenetic process.

Somatic embryogenesis was achieved in young Leaf cuttings of Echinodorus orisis L., an aquatic ornamental plant, in a short period (25 days). Among the cytokinins and their combinations tested, 6-BA (1 mg/L) and Zt (1 mg/L) in MS medium induced the highest efficiency (100%) of somatic embryogenesis, with a maximum of 4.87 embryoids per explant. Roots instead of somatic embryos were formed when NAA (0.5 mg/L) was added to MS medium containing Zt (1 mg/L). Matured embryoids were germinated and rooted in MS medium with IAA (1 mg/L) after 5 days cultivation. Seventy-two percent of the rooted plantlets transplanted survived in the aquarium. The endogenous hormone contents in various stages of somatic embryogenetic process were measured by HPLC. The concentrations of all the hormones tested were about 2 times that of the cuttings from the untreated fresh leaves after 10 days incubation. Meanwhile, the concentration of IAA presents two peaks after 10 and 25 days of cultivation, respectively. The cytokinin (Zt and ZR) peak, about 8 times more than CK, appeared in 15 days cultivation when the heart-shaped embryos formed. The fluctuation of the GA3 concentration was very similar to that of cytokinin. The ABA, however, remains stable at quite high concentration after 10 days of cultivation.

Plant Cells↗

PubMed2000

Changes in the hormonal status of the Taraxacum officinale Web. ovary at early stages of embryogenesis.

The hormonal status of the Taraxacum officinale Web. ovary was quantitatively assayed for the first time during early stages of embryogenesis. Apparent concentrations of endogenous cytokinins were measured using two systems of enzyme-linked immunosorbent assay (ELISA). The ELISA systems differed from one another by the specificity for the main endogenous forms of zeatin. The specificity of two heterological ELISA systems based on zeatin- and kinetin-specific antisera was studied. A new immunochemical approach to the problem of differential quantitative determination of natural zeatin forms is suggested. This approach does not require preliminary separation of experimental samples into individual fractions. True concentrations of zeatin and zeatin riboside in the T. officinale ovary were calculated based on the average values of apparent concentrations of endogenous cytokinins. When the embryo sac maturation had been completed, there was a threefold increase in the zeatin riboside concentration within the following 12 h. By the time of the first division of an unfertilized ovicell (i.e., within the next 12 h), there had been a twofold decrease in the zeatin riboside concentration. Therefore, at early stages of division of the unfertilized ovicell the zeatin riboside concentration virtually returned to the initial level. In contrast to zeatin riboside, there was a steady trend toward an increase in the zeatin concentration in the T. officinale ovary. Within the first 12 h and the next 12 h after completion of the embryo sac maturation, the zeatin concentration was increased 1.5-fold and 2-fold, respectively. The results of this work provide a pioneering insight into the dynamics of various natural forms of zeatin during the reproductive process. The immunochemical approach to quantitative monitoring of various natural forms of zeatin and their dynamics during embryogenesis suggested in this work can be extended to similar biological, medical, and agricultural problems of differential determination of low-molecular-weight agents of similar structure but different biological activity.

Adenosine↗

PubMed2000

Mice deficient in hepsin, a serine protease, exhibit normal embryogenesis and unchanged hepatocyte regeneration ability.

Hepsin, a liver-enriched novel serine protease, has been implicated in participating with normal cell growth, embryogenesis, and blood coagulation pathway. To study its function in vivo, we have disrupted the mouse hepsin gene by homologous recombination. Targeted disruption of the hepsin gene and ablation of hepsin message were demonstrated by Southern blotting, Northern blotting and RT-PCR analysis. Homozygous hepsin -/- mice were viable, fertile, and exhibited no gross abnormalities, as judged by the size, weight and blood coagulation (PT) assays. However, the serum concentration of the bone form of alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase of the hepsin -/- mice was mildly elevated, in spite of no obvious pathological change of hepatocytes. To examine whether hepsin is involved in controlling cell growth in adult tissues, 70% hepatectomy was applied to the hepsin -/- mice. Liver regeneration proceeded normally in the hepsin -/- mice as judged by the liver mass restoration rate. These results suggest that loss of hepsin function causes no effect in cell growth and embryogenesis in vivo, which is in contradiction to the studies using in vitro cell culturing system. Moreover, gross mass regeneration of liver after damage proceeds normally in the absence of functional hepsin.

Animals↗

PubMed2000

Multiple stage-dependent roles for histone deacetylases during amphibian embryogenesis: implications for the involvement of extracellular matrix remodeling.

Histone acetylation has long been implicated in the regulation of gene expression. Recently, a number of histone acetyltransferase and histone deacetylase genes have been identified and cloned. Molecular studies have shown that these enzymes influence transcriptional regulation as components of cofactor complexesthat interact with diversetranscription factors. However, relatively little is known about their function during development. Here, we make use of the ability to manipulate Xenopus laevis embryos in vitro to study the role of histone deacetylases in development. We first demonstrate that the histone deacetylase Rpd3 and its associated co-repressor Sin3A are coordinately expressed during embryogenesis. Rpd3 and Sin3A are known to be part of at least one large corepressor complex, which is involved in transcriptional regulation by many transcription factors, suggesting that deacetylase activity is important for embryogenesis through transcriptional regulation. Indeed, treating developing embryos with a specific histone deacetylase inhibitor, trichostatin A (TSA), leads to embryonic lethality with severe defects in the head and tail regions. Furthermore, the effects of TSA are stage-dependent with the severity of the defects decreasing when treatment is initiated at later stages. On the other hand, a sharp bend (kink) develops in the tail even when TSA treatment begins at tadpole hatching. We provide evidence that this tail defect may be in part due to the TSA-dependent inhibition of the expression of the matrix metalloproteinase gene stromelysin-3, which has been implicated in tail development through extracellular matrix remodeling.

Animals↗

PubMed2000

Direct somatic embryogenesis and plantlet regeneration from leaf explants of niger, Guizotia abyssinica (L.f.) Cass.

Somatic embryogenesis was induced in niger (Guizotia abyssinica (L.f.) Cass.) using a simple one step method. Leaf explants were cultured on MS medium with 2,4-D and BAP/Kn individually and in combination. Somatic embryogenesis occurred directly without an intervening callus proliferation phase from subepidermal regions of leaf explants on MS medium supplemented with 2,4-D (2.0 and 5.0 microM) plus Kn/BAP (1.0 and 2.0 microM). Regenerated somatic embryos were successfully grown into whole plants.

Asteraceae↗

PubMed1995

Effect of microgravity and hypergravity on embryo axis alignment during postencystment embryogenesis in Artemia franciscana (Anostraca).

Cysts of brine shrimp attached with a liquid adhesive to 12-mm diameter glass coverslips in a syringe-type fluid processing apparatus were flown aboard the NASA space shuttle Discovery, flight STS-60, from 3-11 February 1994, and were allowed to undergo postencystment embryogenesis and to hatch in microgravity. The shuttle flight and the ground-based control coverslips with attached cysts were parallel to the earth's surface during incubation in salt water. Based on the position of the cyst shell crack in the attached cyst population, the ground-control nauplii emerged mostly upward. On the shuttle in microgravity, although our method of detection of orientation would not reveal emergence toward the coverslip, the ratio of the position of the cyst shell crack in the population after hatching best fit the predicted values of a random direction for nauplii emergence. Centrifugation on earth was then used to create hypergravity forces of up to 73 g during postencystment embryogenesis and hatching. The upward orientation of emerging nauplii showed a high degree of correlation (r(2) =98.8%) with a linear relationship to the log of g, with 78.2% of the total hatching upward at 1 g and 91.0% hatching upward at 73 g.

Animals↗

PubMedDate not supplied

[The role of the yolk sac in copper metabolism during rat embryogenesis].

Using the immunoblotting method, the synthesis of two copper-transporting P1-type ATPases, ATP7A (a candidate for the product of the Menkes disease gene) and ATP7B (presumed product of the Wilson disease gene), in the yolk sac cells of rat embryos at days 11 and 20 of embryogenesis was demonstrated. Concomitantly, yolk sac cells produce ceruloplasmin, a soluble copper-transporting glycoprotein, a proportion of which in secreted proteins progressively diminishes, attaining 5.2% at day 11 and 3.1% at day 20 of development. At different stages of embryogenesis, yolk sac cells synthesize two molecular forms of [14]C-ceruloplasmin, one of which is secreted towards the embryo, whereas the other, towards the decidual membrane. Two forms of ceruloplasmin secreted in polar directions differ in the rate of secretion. The role of the yolk sac as a key organ controlling the delivery and secretion of copper in the embryo during the postimplantation period is discussed.

Adenosine Triphosphatases↗

PubMedDate not supplied

[A study of the complex of proteolytic enzymes and their protein inhibitors in embryogenesis of the silkworm].

We studied changes in the activities of serin, thiol, and aspartyl proteinases and their protein inhibitors during embryogenesis of the silkworm. The dynamics of activities of the protein inhibitors and specific proteinases were interrelated, thus providing for coordination and fine regulation of functioning of the proteolytic complex of enzymes during embryogenesis. Possible functions of peptidohydrolases and their protein inhibitors in the silkworm are discussed.

Animals↗

PubMed1998

[A comparative study on the syntheses of DNA, RNA and protein during in vitro organogenesis and somatic embryogenesis of Lycium barbarum L].

After the calli originating from the leaf explant of Lycium barbarum L. were selected and proliferated, the yellowish calli with same origin, similar state were transferred to O medium or E medium and the regenerative systems of organogenesis and somatic embryogenesis might form. By these systems, a comparative study on the synthetic activities of DNA, RNA and protein in the two in vitro regeneration pathways was carried out. The results were as follows: (1) Before meristemoid and embryogenic cells were formed, the synthesis of RNA was activated firstly, followed with the increase of synthesis rates of DNA and protein. During the formation of globular embryo, the synthesis rate of DNA increased quickly and then the activities of syntheses of RNA and protein reached the peak, while it was the contrary during germination of adventitious bud. (2) Components of soluble protein changed regularly. A peptide (153.6 kD) appeared during the initiation of both organogenesis and somatic embryogenesis. Several peptides disappearing gradually in the early-stage of differentiation could regenerate with the formation of shoot primordium and globular embryo. Corresponding to morphogenesis, both regenerative systems had specific peptides (84.9 kD, 46.3 kD and 44 kD, 36.2 kD) as molecular markers of its own development. In addition, the relation and mechanism of the two regenerative systems were discussed.

Culture Techniques↗

PubMed2001

[Somatic embryogenesis and plant regeneration in vitro from young shoots of Aralia elate (Miq.) Seem].

Explants excised from the young shoots of Aralia elata (Miq.) Seem. were cultured on MS media. Calli were induced from the explants on MS medium supplemented with 0.5 mg/L 2, 4-D, 0.5 mg/L BA and 0.5 mg/L NAA. Then these calli were transferred onto the MS medium containing 2.0 mg/L 2,4-D + 0.5 mg/L BA + 0.5 mg/L NAA and 0.2% activated charcoal. Under these conditions the somatic embryoids were observed and regenerated plants were obtained from somatic embryogenesis. Then, a experimental system with stability and high regenerating efficiency has been set up for the propagation of the young plants, the cell breeding technology and the control of somatic embryogenesis of Aralia elata (Miq.).

Aralia↗

PubMedDate not supplied

[Mechanisms and frequency of nuclear divisions in trophoblast and decidua cells during postimplantation embryogenesis in the mouse].

The finding of amitotic division of trophoblast cell nuclei in blastocysts of the American mink (Mustela vison), which has an obligatory period of delay in implantation (obligatory embryonic diapause) in its ontogenesis, led us to study the mechanisms and frequencies of division of trophoblast and decidua cell nuclei during the postimplantation embryogenesis of mouse (Mus musculus), which does not exhibit an obligatory diapause nor amitosis in blastocysts. It has been established that the main mechanism underlying the cell nuclei division in both tissues (trophoblast and decidua) forming the placenta is amitosis. These data suggest that the occurrence of an obligatory embryonic diapause in ontogenesis of certain animal species is related not only to the delay in implantation, but also to the alteration in the chronology of all processes of embryogenesis.

Animals↗

PubMed1992

[Electron microscopic analysis of synaptonemal complexes of male laboratory mice exposed during the period of embryogenesis in the vicinity of the Chernobyl Nuclear Power Station].

Four male mice were shown to have decreased fertility among 74 laboratory male mice exposed in the Chernobyl APP area during embryogenesis. Electron microscopic analysis of synaptonemal complexes (SC) of at zygotene-diplotene and light-optic analysis of chromosome aberrations at diakinesis-metaphase 1 demonstrated the presence of interchromosome translocations in autosomal chromosomes, and also intrachromosome translocations in two of four animals. The frequency of chromosome translocations in SC preparations was on the average 1.8 times higher than their frequency at the diakinesis-metaphase 1 stage. High percentage of cells in which associations of sex bivalent axes (XY) with the axes of autosomal bivalents were observed in the SC preparations and reduced fertility in the animals studied confirmed the Forejt's hypothesis that such associations caused the arrest of cells at pachytene and, as a consequence, disturbed the process of embryogenesis.

Accidents↗

PubMedDate not supplied

[Patterns of protein biosynthesis in the embryo and endosperm during embryogenesis in Pinus sylvestris L].

The patterns of protein biosynthesis in the embryo and endosperm during embryogenesis in the Scots pine were studied using electrophoresis and biochemistry methods. Proteins of the albumin-globulin fraction were visualized already at the early embryonic stages. The main polypeptide components (48-60, 37-39, and 20-22 kDa) were gradually accumulated in the course of maturation. A high synchrony was noted between the stages of embryogenesis and molecular events related to protein biosynthesis and accumulation in the developing seed.

Albumins↗

PubMed2004

chk-1 is an essential gene and is required for an S-M checkpoint during early embryogenesis.

The chk1 gene was first discovered in screens for radiation sensitive mutants in S. pombe.(1) Genetic analysis revealed that chk1 is involved in a DNA damage G(2)-M checkpoint. Chk1 becomes activated in response to DNA damage and prevents entry into mitosis by inhibiting the cell cycle machinery. This checkpoint decreases the risk of defective DNA being inherited by daughter cells, therefore reducing the risk of genetic instability. In higher eukaryotes, chk1 homologues have similar checkpoint functions. For example, an avian B-lymphoma cell line that is defective for Chk1 fails to arrest in G(2)-M after DNA damage. Nonetheless, these Chk1 defective cells are viable indicating that Chk1 is not essential for normal somatic cells to divide.(2) In spite of this, mouse and Drosophila homozygous Chk1 mutants die during embryogenesis suggesting that this is an essential gene for embryonic cell cycles.(3,4) What particular role does Chk1 have in directing embryonic cell divisions? Here we used the model organism, C. elegans, to address the role of chk-1 during development. As expected, disruption of chk-1 by RNAi eliminated the DNA damage checkpoint response in C. elegans. In addition, we revealed that chk-1 was predominantly expressed during embryogenesis and in the postembryonic germline. Indeed, we found that chk-1 had an essential role in embryo and germline development. More specifically, disruption of chk-1 expression resulted in embryo lethality, which was attributed to a defect in an intrinsic S-M checkpoint hence causing premature entry into M-phase.

Animals↗

PubMedDate not supplied

[Polypeptide growth factors in embryogenesis and tumor growth].

Polypeptide growth factors, which belong to different families (epidermal growth factors, insulin-like growth factors, fibroblast growth factors, transforming growth factors-beta, and some others), were characterized regarding their specific role in embryogenesis and tumor growth. Differences and parallels of the functioning of growth factors in these processes have been noted. Potential significance of the described characteristics of growth factors for directed modulation of embryogenesis and tumor growth is discussed.

Animals↗

PubMedDate not supplied

[Discovery of genes active in embryogenesis by gene trapping].

Gene trapping is one of the most promising technologies of vector mutagenesis used for discovery of genes active in embryogenesis. A brief description is provided for gene trapping based on the use of embryonic stem cells and vectors carrying the reporter gene lacZ without promoter, as well as the results obtained with the help of this technology. A total of four transgenic mouse lines were obtained, in three of which the vector was integrated into genes active during embryogenesis. As a result, various patterns of beta-galactosidase expression were observed in the limb rudiments, heart, liver, and other organs at different embryonic stages. At present, detailed studies of the site and time of action of the mutated genes in embryonic and postnatal development are under way, as well as molecular-genetic identification of these genes.

Animals↗

PubMed2004

New approach for the identification of folate-related pathways in human embryogenesis.

The role of natural folate intake and synthetic folic acid supplementation in the prevention of some congenital malformations is known, but on a molecular biological level poorly understood. In a first approach to identify folate-regulated pathways in human embryogenesis, tryptic digests of Epstein Barr Virus-immortalized B-lymphoblasts proteins from 6 cleft lip and/or palate patients and 2 controls were compared using matrix assisted laser desorption ionisation--time of flight (MALDI-TOF) mass spectrometry. After immortalisation, the lymphoblasts were cultured for 22 days in folate-rich, i.e. 5-methyltetrahydrofolate (5-mTHF), or folate-free medium. On day 22, 5-mTHF was added to the folate-free cultures and the profiles on day 22 and 23 were compared. After background correction for the peptide profiles of the folate-rich cultures, we found in the folate-free mediaseveral differentially expressed peptide peaks upon addition of 5-mTHF. These peptide peaks were mass annotated and matched withthe MSDB human database. The results suggest some folate-regulated protein candidates as Frizzled and the Rho GTP-ases WRCH and Chp that are known in human embryogenesis. Differential folate expressed proteins in patients and controls, however, have to be further investigated.

B-Lymphocytes↗