scholarly journals Artificial Heterokaryons of Animal Cells from Different Species

1966 ◽  
Vol 1 (1) ◽  
pp. 1-30
Author(s):  
H. HARRIS ◽  
J. F. WATKINS ◽  
C. E. FORD ◽  
G. I. SCHOEFL
Keyword(s):  
Nucleic Acid ◽  
Dna Synthesis ◽  
Single Cells ◽  
Parent Cell ◽  
Hybrid Cells ◽  
Animal Cells ◽  
Differentiated Cells ◽  
Undifferentiated Cells ◽  
A Cell ◽  
Rna And Dna

A virus, inactivated by ultraviolet light, was used to fuse together cells from different species of vertebrate, and the resulting heterokaryons were examined by autoradiographic and cytological techniques. Heterokaryons could be made with both differentiated and undifferentiated cells: HeLa and Ehrlich ascites cells were studied as examples of undifferentiated cells; rabbit macrophages, rat lymphocytes and hen erythrocytes as examples of differentiated cells. These last three cells were chosen because in them, in varying degrees, the process of differentiation has resulted in suppression of the synthesis of DNA or of both DNA and RNA. This suppression was in all cases found to be reversible: the dormant nuclei could be induced to resume the synthesis of RNA or DNA or both when the differentiated cells were fused with a cell which normally synthesizes RNA and DNA. Observations on heterokaryons in which differentiated cells were fused with HeLa cells and with each other permitted certain general conclusions to be drawn about the regulation of nucleic acid synthesis in the heterokaryon. It was found that if either one of the parent cells normally synthesized RNA, RNA synthesis took place in both types of nuclei in the heterokaryon. If either of the parent cells normally synthesized DNA, DNA synthesis took place in both types of nuclei in the heterokaryon. If neither of the parent cells synthesized DNA, no DNA synthesis took place in the heterokaryon. In all cases where a cell which synthesized a particular nucleic acid was fused with one which did not, the active cell initiated the synthesis of this nucleic acid in the inactive partner. In no case did the inactive cell suppress synthesis in the active partner. The nuclei of heterokaryons in which DNA synthesis took place underwent mitosis, and those nuclei which entered mitosis synchronously usually fused together. This process resulted in the progressive formation of mononucleate hybrid cells, which might thus contain within a single nucleus chromosomal complements derived from different species. These mononucleate hybrid cells were also capable of RNA and DNA synthesis, and many of them in turn underwent mitosis. At metaphase these cells showed, in various combinations, the chromosomal complements of the two parent cells. Mononucleate hybrid cells formed by the fusion of a large number of single cells did not appear to be capable of continued multiplication; but mononucleate cells containing one chromosomal set from each parent cell were still found to be undergoing mitosis many days after cell fusion.

Morphological changes in rat tracheal cells during the adaptive and early growth phase in primary cell culture

1985 ◽  
Vol 74 (1) ◽  
pp. 283-301
Author(s):  
L.Y. Chang ◽  
R. Wu ◽  
P. Nettesheim
Keyword(s):  
Dna Synthesis ◽  
Cell Population ◽  
Growth Phase ◽  
Mucous Cells ◽  
Ciliated Cells ◽  
Differentiated Cells ◽  
Tracheal Cell ◽  
Attached Cell ◽  
Undifferentiated Cells ◽  
Tracheal Epithelial

The purpose of our studies was to determine the fate of different cell types present in early primary cultures of tracheal epithelial cells and, if possible, to elucidate the role they play in the establishment of the cultures. Epithelial cells were isolated from rat tracheas with 0.5% Pronase and were cultured on collagen-coated dishes as described previously. Light and transmission electron microscopic studies showed that the cell population harvested from rat trachea was composed of approximately 30% ciliated cells, 50% granule-containing cells and 20% undifferentiated cells (presumably basal cells). Upon seeding the tracheal cell suspensions into culture, approximately 40% of the cells attached. Cell attachment was virtually complete after 16 h. Roughly 60% of the cells attaching during the first 12 h were neither ciliated nor granulated, suggesting that undifferentiated cells played a major role in establishment of the early cultures. Between 20 and 35% of the cells attaching during this time were identified as granulated cells (mucous cells). Ciliated cells did not start to attach in significant numbers until 8 h after seeding. They never amounted to more than 8–12% of the attached cell population. After 12 h of culture, the cell population underwent a progressive loss of differentiation. The number of poorly differentiated cells (i.e. those showing neither cilia nor mucous granules) increased correspondingly. This loss of differentiation preceded the onset of DNA synthesis and cell growth which began at about 24 and 40 h, respectively. Continuous [3H]thymidine-labelling studies showed that at 48 h after the start of culture about 90% of all attached cells had entered DNA synthesis at least once. This finding is consistent with the interpretation that the ciliated cells are terminally differentiated cells and are probably the only part of the tracheal cell inoculum not participating in the growth of the cultures. At 72 h, the cultures (now in mid-log growth phase) were composed of uniformly undifferentiated cells lacking cilia and mucous granules. The cells nevertheless showed unequivocal epithelial characteristics such as tight junctions and desmosomes. The studies suggest that both basal and mucous cells are responsible for the establishment and growth of the rat tracheal epithelial cell cultures.

Review Lecture Hybrid cells from mouse and man: a study in genetic regulation

1966 ◽  
Vol 166 (1004) ◽  
pp. 358-368 ◽  
Keyword(s):  
Ultraviolet Light ◽  
Sendai Virus ◽  
Single Cells ◽  
Relevant Literature ◽  
Cell Types ◽  
Hybrid Cells ◽  
Artificial Culture ◽  
Multinucleate Cells ◽  
A Cell ◽  
The Dead

The work which I have been asked to review began a little over a year ago with an experiment which I made in collaboration with Dr J. F. Watkins (Harris & Watkins 1965). We showed that an animal virus, killed by irradiation with ultraviolet light, could be used to fuse together cells derived from mouse and man to produce artificial man-mouse hybrid cells. The idea of using viruses in this way has its origins in observations which go back for more than a century. (For a review of the relevant literature see Harris, Watkins, Ford & Schoefl 1966). Many diseases have long been known to be associated with lesions in which multi-nucleate cells are found. In the medical literature of the nineteenth century there is a protracted and vigorous controversy about the mode of formation of these cells. Multinucleate cells are commonly found in the lesions produced by certain pathogenic viruses and, during the last decade, it has become clear that in at least some cases the virus produces the multinucleate cell by fusing single cells together. It was thus a very small step to attempt to see whether a virus could be used to fuse together cells of different kinds, and whether the resulting hybrid cells, if they were formed, would survive. And since the survival of the hybrid cells might be jeopardized by infection with a living virus, the virus was killed before the cells were treated with it. In the event, it turned out that viruses, inactivated by ultraviolet light, could be used to provide a general method for fusing together both differentiated and undifferentiated cells from different species and even different orders of vertebrate. The resulting interspecific hybrid cells survived for long periods and proved in some cases to be capable of multiplication. They thus offered interesting possibilities for the study of nucleo-cytoplasmic relationships and lent themselves to experiments of a kind which had not hitherto been feasible. It is these experiments which I propose to discuss. The virus used in this work was the ‘Sendai’ virus, a member of the para-influenza group of myxoviruses; other members of this group of viruses have since been used by other workers. Sendai virus was chosen because it had been shown by Okada (1958, 1962) that animal tumour cells in suspension could be rapidly fused together by high concentrations of this virus. The virus was irradiated with doses of ultraviolet light which reduced its infectivity by at least 10 6 ; but the dead virus retained its ability to fuse cells together. The two cell types studied in the first instance were the HeLa cell (a cell of human origin which has been grown for many years in artificial culture) and the Ehrlich ascites cell (a tumour which grows as a cell suspension in the peritoneal cavity of the mouse). These two cell types were chosen for a number of technical reasons, but mainly because their nuclei were easily distinguishable on morphological grounds. When a suspension containing a mixture of the two cell types is treated with the dead virus under appropriate conditions the cells clump together, and, during the ensuing 20 to 30 min, at 37 °C, the cell surfaces at the points of contact between the cells undergo dissolution. This process results in the progressive coalescence of the cytoplasms of neighbouring cells, so that multinucleate cells containing varying numbers of nuclei are formed.

scholarly journals Biotechnological and Biomedical Applications of Enzymes Involved in the Synthesis of Nucleosides and Nucleotides

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1147
Author(s):  
Jesús Fernández-Lucas
Keyword(s):  
Nucleic Acid ◽  
Cell Growth ◽  
Dna Synthesis ◽  
Biomedical Applications ◽  
Building Blocks ◽  
Rna And Dna Synthesis ◽  
Rna And Dna

Nucleic acid derivatives are involved in cell growth and replication, but they are also particularly important as building blocks for RNA and DNA synthesis [...]

scholarly journals Evolution of multicellular life cycles under costly fragmentation

2020 ◽  
Vol 16 (11) ◽  
pp. e1008406
Author(s):  
Yuriy Pichugin ◽  
Arne Traulsen
Keyword(s):  
Growth Rates ◽  
Single Cells ◽  
Cell Loss ◽  
Life Cycles ◽  
Additional Risk ◽  
Structured Population ◽  
Evolution Of Life ◽  
Undifferentiated Cells ◽  
A Cell ◽  
The Impact

A fascinating wealth of life cycles is observed in biology, from unicellularity to the concerted fragmentation of multicellular units. However, the understanding of factors driving their evolution is still limited. We show that costs of fragmentation have a major impact on the evolution of life cycles due to their influence on the growth rates of the associated populations. We model a group structured population of undifferentiated cells, where cell clusters reproduce by fragmentation. Fragmentation events are associated with a cost expressed by either a fragmentation delay, an additional risk, or a cell loss. The introduction of such fragmentation costs vastly increases the set of possible life cycles. Based on these findings, we suggest that the evolution of life cycles involving splitting into multiple offspring can be directly associated with the fragmentation cost. Moreover, the impact of this cost alone is strong enough to drive the emergence of multicellular units that eventually split into many single cells, even under scenarios that strongly disfavour collectives compared to solitary individuals.

Continued DNA synthesis after a mitotic block in the double mutant cut1 cdc11 of the fission yeast Schizosaccharomyces pombe

1990 ◽  
Vol 96 (3) ◽  
pp. 435-438
Author(s):  
J. Creanor ◽  
J.M. Mitchison
Keyword(s):  
Dna Synthesis ◽  
Schizosaccharomyces Pombe ◽  
Double Mutant ◽  
Single Cells ◽  
Restrictive Temperature ◽  
Synchronous Cultures ◽  
Fluorescence Measurements ◽  
Dna Assays ◽  
A Cell ◽  
Two Peaks

DNA synthesis is normally dependent on a cell having previously gone through mitosis. Hirano et al. (1986), however, found that DNA synthesis continued at the restrictive temperature in the double mutant cut1 cdc11 of Schizosaccharomyces pombe even though mitosis was blocked in some of the cells. We have confirmed this result with bulk DNA assays of asynchronous cultures. Synchronous cultures of a diploid double mutant at the restrictive temperature showed two peaks of incorporation with an interval between them that was approximately the same as the doubling time in cell length. Flow cytometry showed that the cells had increased their DNA content from 4C (the diploid value) to about 16C after 7h. The cytological appearance at this time was mixed, with uninucleate, binucleate and dead cells, but fluorescence measurements on single cells indicated that about half the population had single nuclei with about the 16C value and had therefore gone through two rounds of DNA synthesis without mitosis.

scholarly journals CHROMOSIN, A DESOXYRIBOSE NUCLEOPROTEIN COMPLEX OF THE CELL NUCLEUS

1946 ◽  
Vol 30 (2) ◽  
pp. 117-148 ◽  
Author(s):  
A. E. Mirsky ◽  
A. W. Pollister
Keyword(s):  
Nucleic Acid ◽  
Cell Nucleus ◽  
Physiological Saline ◽  
Considerable Extent ◽  
Bacterial Cells ◽  
Animal Cells ◽  
Histone Protein ◽  
Isolated Nuclei ◽  
Nucleoprotein Complex ◽  
A Cell

A desoxyribose nucleoprotein complex, which we have referred to as a chromosin, has been prepared from a great variety of cells, mainly animal but also plant and bacterial. A chromosin is derived from the cell nucleus. In the course of preparation precautions have been taken to prevent contamination by cytoplasmic constituents. To assure the nuclear origin of all components of chromosin, nuclei have in several instances been isolated before extraction was begun. Because of the precautions taken, chromosins do not contain detectable quantities of ribose nucleoproteins; but, incidentally, extraction of ribose nucleoproteins, free of desoxyribose compounds, has also been described in this paper. A typical chromosin contains 3 components: desoxyribose nucleic acid, histone, and non-histone protein. The nucleic acid, being highly polymerized, is exceedingly viscous when dissolved and fibrous when precipitated. Histone and non-histone protein differ from each other in a number of ways, of which one of the most definite is that whereas a histone contains no more than traces of tryptophane, the non-histone protein of chromosin contains nearly 1 per cent of tryptophane. In neutral physiological saline both proteins can combine with nucleic acid. With the isolation of chromosins from so many different kinds of cells, it can now be seen that (contrary to the view expressed by Kossel) histones are present in most animal cells and at least in some plant and bacterial cells. Chromosin prepared from the Type III pneumococcus is active in transforming the type of a pneumococcus culture. It has been pointed out that it is not yet known whether or not protein is a necessary constituent of the transforming agent. To extract chromosin from a cell M NaCl is used. When dissolved in M NaCl the nucleic acid and histone components of a chromosin are to a considerable extent dissociated. They are not dissociated when the chromosin is dissolved in 0.02 M NaCl, but in this medium a partial depolymerization of the nucleic acid occurs. A chromosin should certainly not be considered to be a definite chemical compound. It is a complex extracted from chromatin, which is itself a complicated nuclear structure. And in the course of extraction, it need hardly be said, the structure of chromatin has been considerably changed. To avoid complications it has been considered an advantage in this work to begin with isolated nuclei, and it would clearly be a further simplification to begin chemical procedures only after the chromosomes themselves have been isolated. This is now being accomplished, and it is found that the methods described in this paper are of value in learning how the substances present in a chromosin are put together in a chromosome.

EFFECT OF PROLACTIN ON NUCLEIC ACID METABOLISM DURING LACTOGENESIS IN THE RABBIT

1971 ◽  
Vol 51 (2) ◽  
pp. 265-270 ◽  
Author(s):  
A. A. SIMPSON ◽  
G. H. SCHMIDT
Keyword(s):  
Nucleic Acid ◽  
Dna Synthesis ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Acid Metabolism ◽  
Nucleic Acid Metabolism ◽  
Specific Effects ◽  
Intraductal Injection ◽  
Rna And Dna Synthesis ◽  
Rna And Dna

SUMMARY Lactogenesis was initiated by intraductal injection of prolactin into individual lobes of rabbit mammary glands previously developed by injections of oestrogen and progesterone. Nucleic acid metabolism was assessed at various times after prolactin treatment. A systemic pulse of [3H]thymidine or [3H]uridine was used to determine the specific effects of prolactin treatment on RNA and DNA synthesis and metabolism. Prolactin increased the rate of RNA synthesis. It is suggested that prolactin enhanced both the rate of RNA movement from the nucleus, and its rate of metabolism in the cytoplasm. The greatest increase in the rate of synthesis occurred in non-ribosomal RNA. Subsequent to its effect on RNA, prolactin enhanced DNA synthesis. Total RNA per cell increased as indicated by an increased RNA:DNA ratio. These changes are considered to be specifically due to the local action of prolactin.

scholarly journals Recent advances in understanding DNA replication: cell type–specific adaptation of the DNA replication program

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1351 ◽  
Author(s):  
Antoine Aze ◽  
Domenico Maiorano
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Genetic Diseases ◽  
Cell Types ◽  
Differentiated Cells ◽  
Undifferentiated Cells ◽  
Cell Type Specific ◽  
Division Cell ◽  
Different Cell Types

DNA replication is an essential process occurring prior to cell division. Cell division coupled to proliferation ensures the growth and renewal of a large variety of specialized cell types generated during embryonic development. Changes in the DNA replication program occur during development. Embryonic undifferentiated cells show a high replication rate and fast proliferation, whereas more differentiated cells are characterized by reduced DNA synthesis and a low proliferation rate. Hence, the DNA replication program must adapt to the specific features of cells committed to different fates. Recent findings on DNA synthesis regulation in different cell types open new perspectives for developing efficient and more adapted therapies to treat various diseases such as genetic diseases and cancer. This review will put the emphasis on recent progress made in this field.

scholarly journals Leukocytes with chromosome Y loss have reduced abundance of the cell surface immunoprotein CD99

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonas Mattisson ◽  
Marcus Danielsson ◽  
Maria Hammond ◽  
Hanna Davies ◽  
Caroline J. Gallant ◽  
...  
Keyword(s):  
Cell Surface ◽  
Single Cells ◽  
Surface Protein ◽  
Protein Abundance ◽  
Blood Leukocytes ◽  
Chromosome Y ◽  
Increased Risk ◽  
A Cell ◽  
Pseudoautosomal Regions ◽  
Male Specific

AbstractMosaic loss of chromosome Y (LOY) in immune cells is a male-specific mutation associated with increased risk for morbidity and mortality. The CD99 gene, positioned in the pseudoautosomal regions of chromosomes X and Y, encodes a cell surface protein essential for several key properties of leukocytes and immune system functions. Here we used CITE-seq for simultaneous quantification of CD99 derived mRNA and cell surface CD99 protein abundance in relation to LOY in single cells. The abundance of CD99 molecules was lower on the surfaces of LOY cells compared with cells without this aneuploidy in all six types of leukocytes studied, while the abundance of CD proteins encoded by genes located on autosomal chromosomes were independent from LOY. These results connect LOY in single cells with immune related cellular properties at the protein level, providing mechanistic insight regarding disease vulnerability in men affected with mosaic chromosome Y loss in blood leukocytes.

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