Nuclei Of Embryo Cells Research Articles

Ultrastructure of Cell Organelles in Pre-implantation Embryos from Cows with Different Body Condition Score.

Morphology of important cell organelles (mitochondria, lipid droplets, vacuoles, inclusion bodies and apoptotic bodies) in embryos derived from cows with different body condition score (BCS) was analysed by transmission electron microscopy (TEM). Embryos were recovered on 7th day after the insemination by a standard non-surgical flushing of the uterine horns from superovulated Holstein Friesian cows with BCS 2, 3, 4 and 5. Thereafter, the good quality blastocysts were processed for TEM. The electronograms were evaluated by stereological analysis. The relative volume of lipid droplets in BCS4 and BCS5 embryos increased significantly (18.53 and 22.40%) when compared to BCS3 embryos (5.46%). In the embryos from the BCS4 or BCS5 cows, we observed different morphological patterns of mitochondria, as well as the mitochondria containing vacuoles. BCS4 and BCS5 embryo cell nuclei showed the structure typical for low transcription activity (none or very few reticular nucleoli); also dilated inter-cellular spaces were often observed in these embryos. In conclusion, differences in the ultrastructural morphology of embryos from over-conditioned cows (BCS4 and BCS5), particularly the higher lipid content in the cytoplasm, can be a marker of their low quality, and this fact can be a contributing factor to subfertility in over-conditioned cows.

Inhibition of DNA synthesis in rat hepatoma and human lymphoma cell lines, by partially purified factors from mouse embryos

Cancer cells express particular genes, part of which are normally active during the embryonic development. On the other hand, young embryos are able to differentiate and regulate the division rate of teratocarcinoma or leukemia cells, likely by producing differentiation factors. A partial purification of these factors, extracted from mouse embryo cell nuclei, was achieved by high performance liquid chromatography on anion exchange column. High ionic strength eluting fractions, constituted with DNA and tightly bound proteins, have a high inhibitory effect on DNA synthesis, in rat hepatoma and human lymphoma cell lines. The possibility of treatment of cancer cells in this way is discussed.

Nuclear proteins and the onset of cell proliferation in root meristems ofPisum sativum: QP47 a novel acidic protein

AbstractA protein named QP47 has been purified from quiescent nuclei of root meristems ofPisum sativum, and used to prepare a polyclonal antibody. Immunolocalization of this protein with fluorescent probes revealed a nuclear distribution of thread-like structures. However, the relationship between the distribution of QP47 immunofluorescence and the structural organization of the chromatin required further investigation. The decrease in content of this protein in the nuclei of embryo cells seems to be correlated with the transition from quiescence to proliferation. QP47 degradation seems to depend upon an increase in the state of its phosphorylation. This protein is not present in normally proliferating cells, or in cells whose cell proliferation has been arrested by starvation or differentiation. It is hypothesized that QP47 may be required specifically during the quiescent period for specific structural organization of the chromatin.

Transfer of foreign DNA into the cells of developing mouse embryos by microprojectile bombardment

Mouse cells of developing embryos at the 2–4 cell, morula and blastocyst stages, were bombarded by high velocity tungsten microprojectiles. About 70% of developing embryos survived the bombardment. The general embryo structure did not change as a result of the bombardment. Penetration of the tungsten microparticles into the embryo cell nuclei was found at all stages being investigated, and tungsten particle localization on mitotic chromosomes was demonstrated. The total DNA of the mice born from the bombarded embryos was analyzed by dot-blot hybridization and PCR with post-hybridization. The most important results were obtained in experiments with blastocysts. In three cases of blastocyst bombardment, the presence of transferred plasmid DNA (pSV3-neo) was revealed. Transfected cells were shown to be located in the fetal membrane as well as in the embryo. The bombardment of mouse culture cells resulted in their transfection and the production of G418-resistant clones.

Hypothesis on Differentiation of Cancerous Cells: A Possible Means for Isolation by HPLC of Differentiation Factors from Mouse Embryo Cells

Abstract The cancerous cells express particular genes, which are normally active during embryonic development. On the other hand, young embryos inoculated with teratocarcinoma or leukaemia cells are able to differentiate them and to regulate their division rate, by producing differentiation factors. A means of partial purification of these factors, extracted from mouse embryo cell nuclei, and separated by high performance liquid chromatography on anion-exchange column, is described. The possibility of treatment of cancerous cells by this way is discussed.

Uptake and binding of cytoplasmic DNA by wheat embryo cell nuclei.

Cytoplasmic non-mitochondrial DNA was selectively labelled and isolated In a linear single-stranded form from early wheat embryos. The isolated preparation was readily taken up by wheat embryo cell nuclei and firmly bound to large, chromosome-like structures. Similarly prepared nuclear DNA fragments, although taken up, remained unbound and underwent a rapid degradation within the cell nuclei. The selective binding of the cytoplasmic DNA indicates that it might be integrated into the nuclear genome.

Specificity of Interaction between Carcinogenic Polynuclear Aromatic Hydrocarbons and Nuclear Proteins: Widespread Occurrence of a Restricted Pattern of Histone Binding in Intact Cells

The first steps in the induction of malignancy by chemical carcinogens involve covalent interactions with cellular macromolecules. For the widespread environmental contaminant benzo[a] pyrene (B[a]P), metabolic activation by cellular enzymes produces a number of potentially reactive metabolites. The end products of one metabolic pathway, 7,8-dihydroxy-9,10-oxy-7,8,9,10 tetrahydro-B[a]P (BPDE), are responsible for essentially all DNA adduct formation in animal cells treated with B[a]P, and a particular stereoisomer, designated (+)-anti-BPDE is thought to be the ultimate carcinogenic derivative of B[a]P. It has been shown that in hamster embryo cell nuclei treated with (+)-anti-BPDE, two of the histones of nucleosomal core, H3 and H2A are covalently modified, while the remaining core histones—H4 and H2B—are essentially unmodified. All four purified core histones, however, serve as the targets for (+)-anti-BPDE in vitro .

Preferential stimulation of RNA polymerase II B by a chromosomal protein from wheat germ

An RNA polymerase II stimulatory protein was purified from wheat germ chromatin and tested for the ability to stimulate wheat germ RNA polymerases I, II A, II B and III. The form II B of the class II enzyme was stimulated most effectively. The stimulation of[ 14C]GTP incorporation was accompanied by an increase in the RNA product size, especially if native wheat germ DNA was used as template. The stimulatory protein was also able to reverse inhibition of transcription caused by other chromosomal proteins, and was a particularly preferred substrate for cyclic AMP-independent wheat germ protein kinase. The kinase preparation, however, lost its stimulatory activity. It is concluded that a form II B-specific RNA polymerase II stimulatory protein occurs and may be involved in the regulation of transcription in wheat embryo cell nuclei.

Stepwise Relaxation of Supercoiled SV40 DNA

We have shown in this paper that agarose gel electrophoresis can be used to examine the tertiary structure of supercoiled SV40 DNA. Differences as small as one superhelical turn can be detected by this method. When used as an assay, it enabled us to purify from human tissue culture cells a protein which acts on supercoiled DNA, leading to a gradual removal of its superhelical turns. Using in turn the purified DNA relaxing protein to generate reaction intermediates of DNAs with different numbers of superhelical turns, we deduced that native SV40 DNA contains a minimum of 20 physical superhelical turns. The upper limit of this number is less accurately defined, but we think that it is not higher than 24. These numbers agree within very close limits with the numbers determined previously by various indirect physical methods.

News

News