Incorporation of 3H-uridine into the large decidual cells of rats and their differentiation

The antimesometrial part of rat's decidua of the 9th day of gestation was divided into three zones. Cells of either zone display their own morphological and cytochemical properties. Different rates of 3H-uridine incorporation were observed in the cytoplasm and the nucleus in cells of either zone during 5, 30, 60 and 240 minutes after precursor injection. The largest member of silver grain accumulation was observed in the karyoplasm and nucleolus of cells of the transitional zone. The nucleus of basal zone cells had the smallest intensity of 3H-uridine incorporation. The nuclei of the epithelial zone cells are characterized by a lower intensity of 3H-uridine incorporation than those of the transition zone. The intensity to cytoplasmic accumulation of silver grains raised from cells of the basal zone up to cells of the epithelial zone. The largest quantity of cytoplasmic radioactivity was observed 240 minutes after 3H-uridine injection.     

DNA synthesis and content in the nuclei of epidermal cells of mice during their differentiation and specialization

Synthesis and content of DNA in the nuclei of differentiating cells of mouse skin epidermis was studied by using cytomorphometric, autoradiographic and cytophotometric methods. It has been shown that the cells of the keratinoid series divide only in the basal layer and contain 2-4c DNA. Keratinocytes of the thorny layer are mostly tetraploid, 2c cells are lacking. H4c and 8c cells comprise 12% of the population. In the keratinocytes of the granular layer DNA content is somewhat lower due to nuclei break down and conversion of cells into anucleate scale. Part of the melanocytes of the basal layer also contain 4c DNA. Highly specialized element of the basal layer Merkel and Langerhans cells are polyploid. Conclusion is drawn that DNA hyper-replication by multiplication of the whole genome is part of the development program of the population.     

Changes in the specific cytochemical properties of rat decidual cells during differentiation

The antimesometrial part of rat's decidua of 8-9 day of gestation was divided into three parts: epithelial, transition and basal zones. Cells of either zone have their own morphological and cytochemical features. Cells of the epithelial zone are characterized by synthesis of tissue specific antigens and fat (fatty acids). Cells of the transition zone synthesize glycogen. Acid mucopolysaccharides are located in the basal zone only. Decidual cells do not synthesize cholesterol. Con A receptors are localized on the surface of cells of the basal and transition zones and disappear from the surface of epithelial zone cells. It is concluded that differentiation of large decidual cells of the antimesometrial part of rat's decidua are accompanied by a significant change in cytochemical features of cell precursors the synthesis of acid mucopolysaccharides and glycogen stops, while tissue specific antigens and fat (fatty acids) start their syntheses, Con A receptor disappear.     

Changes in DNA content of nuclei in rust uredospore germlings during the start of differentiation

Digital video microscopy in conjunction with the DNA-binding fluorescent probe 4′,6-diamidino-2-phenylindole was used to determine the relative DNA content of single nuclei in germ tubes of uredospores of the bean rust fungus (Uromyces phaseoli), a parasite of bean plants (Phaseolus vulgaris). The uredospores develop a series of infection structures in response to contact stimuli, and the first structure to appear, the appressorium, occupies the stomatal opening. This study was made to determine the time after the start of germination on an inductive surface that DNA replication and mitosis occur. It was found that the start of DNA replication detected by increased nuclear fluorescence power of some individual nuclei in the population was nearly coincident with mitosis between 2.0 and 2.5 h after the start of germination and that the appressorium was completed about 30 min later. The fluoresence power of nuclei was about the same before DNA replication began as at the end of mitosis; hence the germ tube nuclei were in the G₁ phase of the cell cycle before mitosis.     

DNA synthesis and content in human decidual cells at different stages of differentiation based on flow cytometry data]

Flow cytometry analysis of the DNA content of human decidual cells at the physiologically normal pregnancy and in the case of toxicosis was carried out. During the normal pregnancy DNA-histogram parameters were seen to vary: the number of S-phase cells decreased, the coefficient of variation of the G1/0 peak increased. These alterations correlated positively with the increase in the share of decidual cells with properties of terminally differentiated cells. The most pronounced quantitative alterations in variability of DNA content in G1/0 cells were observed in cases of toxicosis of pregnancy. Phenomena of variability of the nuclear DNA in the terminally differentiated decidual cells is considered to be a sign of cell death through apoptosis.     

Organization of desmin-containing intermediate filaments during differentiation of mouse decidual cells

Decidualization of the mouse endometrium consists of a redifferentiation of the endometrial stromal fibroblasts. During decidualization these fibroblasts undergo growth, change of shape, multinucleation, and establishment of intercellular junctions. One feature of rodent decidual cells is the accumulation of intermediate filaments. In spite of the fact that fibroblasts normally have vimentin intermediate filaments, they acquire a large amount of desmin intermediate filaments while they undergo decidualization. The light and electron microscope immunocytochemical results of the present work show that during the initial stages of decidual transformation the desmin intermediate filaments accumulate around the nuclei, often forming caps around the nuclear envelope. As the decidual cells grow, the filaments form bundles and nets that radiate from the nuclei toward the cell surface. During the final stages of differentiation, on day 8 of pregnancy, staining of differentiated decidual cells decreases and most filaments accumulate under the cell surface. A role for intermediate filaments is suggested for decidualization of mouse endometrial cells.     

Electron microscopic study of the differentiation of decidual cells. I. The ultrastructure of large decidual cells in the antimesometrial portion of the rat decidua

The large decidual cells (LDC) of the antimesometrial part of decidua in rats of 7-9 days of gestation were studied by electron microscope. The decidual tissue has an epithelium-like pattern of organization. The apical surface of LDC is facing the pericapillar space making numerous villi. Lateral surfaces of these cells maintain close contact with each other by means of zona adhaerens, gap junctions, spot desmosomes and simple junctions. Accumulation of electron dense granules measuring from 0.05 to 0.3 mkm is seen in the apical parts of LDC. The Golgi complex and rough endoplasmic reticulum are much developed. The material of rough endoplasmic reticulum is denser than the cell matrix. Disperse chromatin is seen in the nucleus, whereas the granular component is dominanting in the nucleolus. It is concluded that the LDC may have a high metabolic activity, and that the secretion is a mode of fulfilling specific functions of LDC.     

Changes in mitochondrial reactive oxygen species synthesis during differentiation of skeletal muscle cells

Myogenesis is accompanied by an intensive metabolic remodeling. We investigated the mitochondrial reactive oxygen species (ROS) generation at different levels of skeletal muscle differentiation: in C2C12 myoblasts, in C2C12 myotubes and in adult mouse skeletal muscle. Differentiation was accompanied by an increase in mitochondrial content and respiratory chain activity. The detected ROS production levels correlated with mitochondrial content, being the lowest in the myoblasts. Unlike the adult skeletal muscle, myoblast ROS production was significantly stimulated by the complex I inhibitor rotenone. Our results show that mitochondria are an important ROS source in skeletal muscle cells. The substantial changes in mitochondrial ROS synthesis during skeletal muscle differentiation can be explained by intensive bioenergetic remodeling.     

Changes in the structure of DNA molecules and the amount of DNA per plastid during chloroplast development in maize

We examined the DNA from chloroplasts obtained from different tissues of juvenile maize seedlings (from eight to 16 days old) and adult plants (50-58 days old). During plastid development, we found a striking progression from complex multigenomic DNA molecules to simple subgenomic molecules. The decrease in molecular size and complexity of the DNA paralleled a progressive decrease in DNA content per plastid. Most surprising, we were unable to detect DNA of any size in most chloroplasts from mature leaves, long before the onset of leaf senescence. Thus, the DNA content per plastid is not constant but varies during development from hundreds of genome copies in the proplastid to undetectable levels in the mature chloroplast. This loss of DNA from isolated, mature chloroplasts was monitored by three independent methods: staining intact chloroplasts with 4',6-diamidino-2-phenylindole (DAPI); staining at the single-molecule level with ethidium bromide after exhaustive deproteinization of lysed chloroplasts; and blot-hybridization after standard DNA isolation procedures. We propose a mechanism for the production of multigenomic chloroplast chromosomes that begins at paired DNA replication origins on linear molecules to generate a head-to-tail linear concatemer, followed by recombination-dependent replication.     

Induction of decidual differentiation in endometrial mesenchymal stem cells

In this study, we compared the ability of human mesenchymal stem cells (eMSCs) derived from menstrual blood and mesenchymal stem cells (MSCs) from other tissues to differentiate into decidual cells in vitro. It was demonstrated that, during differentiation, secretion of prolactin and insulin-like growth factor binding protein-1 (key decidualization markers) markedly increased in eMSCs slightly augmented in bone marrow MSC (BM-MSCs) and did not change in MSCs from adipose tissue (AT-MSCs). Thus, eMSCs exhibited higher capacity for differentiation into decidual cells than BM-MSCs or AT-MSCs. This makes eMSCs promising for application in cellular therapy of infertility associated with insufficient decidualization of endometrium.     

DNA content and synthesis in the nuclei of rat cerebellar cells in organotypic cultures

Using cytophotometric and autoradiographic methods, it has been shown for the first time that in condition of an organotypic culture the replicative synthesis of DNA is induced in the Purkinje neurons of the cerebellum of newborn rats completing their terminal differentiation. This synthesis is accompanied by polyploidization of the initially diploid population of these cells (4c, much more rarely 8c, and a single 16c cell appear) rather than by cell division. In constant, the granular cells mostly retain their diploid state and only a few of them synthesize DNA to H2c values. The glial cells divide actively. Hence, evidence is presented that neurons, at least those of cerebellum, retain their potential of replicative synthesis of DNA in the organotypic culture. The important point is that DNA synthesis in their nuclei proceeds simultaneously with processes of differentiation.     

Changes in DNA capacity for actinomycin-D binding in nuclei of interphase cells

3H-AMD binding to DNA in interphase nuclei was tested on asynchronous and synchronous LS/BL cell populations under physiological conditions and after exposure to gamma rays (60Co). 3H-AMD binding to DNA in an asynchronous cell population appeared to be nearly constant and independent of 3H-AMD concentration. However, in comparing individual cells, a great variability could be observed. In synchronized cells the DNA accessibility for 3H-AMD binding changed in the course of the cell cycle, with a maximum occurring at the late G1-phase (13.95 X 10(-12) mumol/nucleus) and a minimum at the late G2-phase (2.63 X 10(-12) mumol/nucleus). In irradiated cells the DNA capacity for 3H-AMD binding was growing with the increasing dose (5-80 Gy) from 4.9 to 11.2 X 10(-12) mumol 3H-AMD/nucleus.     

Differential immunoreactivity for Z-DNA in rat myoblast nuclei during their terminal differentiation

L6 myoblasts in vitro accomplish the process of terminal differentiation from dividing mononucleated cells to quiescent plurinucleated myotubes, synthesizing muscle-specific proteins. They have been tested, using paraformaldehyde and acetic acid fixations and immunocytochemical techniques, for the presence of Z-DNA at different stages: namely after 3, 5 and 8-9 days of culture. The nuclei of the actively dividing 3-day myoblasts were strongly Z-DNA and B-DNA-positive. The inhibition of replication by araC did not diminish the reaction. In the myotubes, the nuclei became Z-DNA-negative but were still B-DNA-positive. In contrast, the nuclei of a non-fusing alpha-amanitin-resistant mutant (Ama102) stayed Z-DNA-positive. These results tend to show that during the process of terminal differentiation Z-DNA either becomes less accessible or is present in undetectable amounts. In circular DNAs, it has been shown that the presence of Z-DNA depends on their negative supercoiling. In addition, the presence of closed superhelical loops of nuclear DNA has been demonstrated in several mammalian cell types; moreover, the density of DNA topological turns in these loops varies during cellular differentiation and malignant transformation. The relationship between these results and ours is discussed.