Tetraploid cells

Gautier Returning to the nuclear cytoplasmic ratio, in a situation where you don t block any event in the cell cycle, such as experiments in frogs where a mosaic is made between the diploid and tetraploid tissue, the tetraploid cells are twice as large. There is some regulation here the amount of DNA is somehow influencing the size of the cell. 

Monoclonal antibodies (and immunotoxins). Quotation from Lancet January 1970 7638 139-140 Tetraploid immunoresistant lymphoma cells in the mouse emerge by the unison of the diploid virus-producing lymphoma cell with a plasma cell producing virus-specific globulins. The resulting tetraploid cell will retain malignant... 

Fig. 2. ES cell-derived embryos by tetraploid complementation. RNAi transgenic ES cells (light gray) are injected into tetraploid host blastocysts (not shown) or aggregated with tetraploid morula embryos (dark gray). The chimeric embryos are allowed to develop in utCTo until the time of phenotypic analysis. The tetraploid cells contribute to the trophoblast portion of the placenta and the yolk sac endoderm. The knockdown ES cells develop into the entire embryo proper, as weU as yolk sac mesoderm and amnion (not shown).

Colchicine treatment can also generate mixoploid cells which subsequently give rise to chimera plants consisting of diploid and tetraploid cells or tissues [25]. 

Friedberg SH, Davidson D (1970) Duration of S phase and cell cycles in diploid and tetraploid cells of mixoploid meristems. Exp Cell Res 61 216-218 Fuchs Y, Lieberman M (1968) Effects of kinetin, lAA, and gibberellin on ethylene production, and their interactions in growth of seedlings. Plant Physiol 43 2029-2036 Gaither DH, Lutz DH, Forrence LE (1975) Abscisic acid stimulates elongation of excised pea root tips. Plant Physiol 55 948-949... 

DNA abnormalities in Barrett s esophagus can be recognized by flow cytometry, a technique in which cell nuclei prepared from tissue specimens are treated with a fluorescent dye that binds to DNA. The treated nuclei are passed through a flow cytometer wherein the DNA-bound dye is excited by laser irradiation, and an estimate of DNA content is obtained by measuring the intensity of fluorescent light emitted. Flow cytometry can identify aneuploid cell populations and can provide information on the proportion of diploid cells (cells in the Go/G phase of the cell cycle that contain two copies of each chromosome) and tetraploid cells (cells in the Gz/M phase that contain four copies of each chromosome) in the sampled tissue. 

This hypothesis may at first appear as a tautology, but it is hoped that it will be realized that it is not when the result of an experiment which is the reverse of cell fusion is considered. Such an experiment has been performed by Stubblefield (1964) by exposing Ghinese hamster cells to prolonged Golcemid treatment. Stubblefield observed that a fraction of the treated cells show aberrant behavior at anaphase the duplicated chromosomes become randomly clustered into groups which subsequently form karyomeres of various sizes, some of which probably contain only one or two chromosomes. Since some of these multinucleated (tetraploid) cells overcome the Golcemid block. 

In diploid eukaryotic organisms such as humans, after cells progress through the S phase they contain a tetraploid content of DNA. This is in the form of sister chromatids of chromosome pairs. Each of these sister... 

Goldstein, P. and Triantaphyllou, A.C. (1979) Karyotype analysis of the plant-parasitic nematode Heteroderaglycinesby electron microscopy. II. The tetraploid and an aneuploid hybrid. Journal of Cell Science 43, 225. 

Two groups demonstrated that BRCA-1- and BRCA-2-deficient cells are acutely sensitive to PARPi [11,12]. Potent inhibitors like KU0058684 (5), KU0058948 (6), and AG14361 (26) were cytotoxic at nanomolar concentrations in HR-defective cells, and displayed excellent selectivity for BRCA-1- and BRCA-2-deficient cells over wild-type cells. After 24 h of exposure, 5 elicited G2 or M phase cell cycle arrest and a tetraploid DNA content. The applicability of this discovery was revealed when BRCA-2-deficient and BRCA-2-proficient cells were injected into mice and tumors were allowed to develop. Daily treatment with 5 or 26 had no effect on the BRCA-2 wild-type cells however, when BRCA-2-deficient cells were treated with PARPi, no tumors developed. 

Marked disturbances in the distribution of ploidy (diploid and tetraploid nuclei) have been observed in the livers of male Sprague-Dawley rats fed a dietary concentration of 100 ppm mirex (equivalent to 5 mg/kg/day) for 13 months (Abraham et al. 1983). Mirex selectively reduced the number of tetraploids with the most significant reduction noted in hepatocellular carcinomas however, nuclei in the areas adjacent to these tumors were also primarily composed of diploids. These data should be interpreted with caution since isolation of nuclei from tumors is difficult and because "of the fantastic variety of forms that tumor nuclei assume" (Smuckler et al. 1976). Similarly, the relevance to humans is not clear since human liver is mainly composed of diploid cells (99%) and contains few tetraploids (Adler et al. 1981). 

The ability of some fluorescent dyes to bind DNA quantitatively is exploited in flow cytometry to determine the DNA content of a cell. Dyes such as propidium iodide that bind double-stranded DNA stoichiometrically can be used for the purpose. The intensity of red fluorescence is directly related to the amount of DNA bound by propidium iodide. By comparing the fluorescence intensity of the test specimen and, in turn, its DNA content to the fluorescence intensity of specimens containing normal diploid amounts of DNA, a DNA histogram can be generated. By computing a DNA index, which is the ratio of DNA content of a test specimen to the DNA content of a specimen containing a normal diploid population, information related to the presence of an aneuploid tumor population can be obtained. The DNA index of 1 would imply that the DNA in the test specimen is from a normal diploid population (2N DNA), whereas the DNA index of an aneuploid population will be greater or less than 1. Thus, the DNA index of a tetraploid (4N DNA) would be 2. 

Cell sort populations according to cell cycle profile. Isolate diploid populations from diploid Gl and tetraploid populations from tetraploid G2 (see Note 2). 

Grow isolated populations for 1 week and verify DNA content by comparing isolated tetraploid populations to the original DLDl cells. Repeat cell sorting if necessary. 

Split, pellet, and resuspend diploid, tetraploid, and centrosome amplified cells at appropriate density (2,000 cells/well final for viability and 12,000 cells/well final for phenotypic) in growth media (DMEM) without antibiotics. 

Subheading 3.1.3, step 6 Use only confirmed ES cell clones for generating mouse lines by blastocyst injection or tetraploid embryo aggregation. Resulting mice need to be mated to Cre deleter strains 21) for knockdown activation. 

The duration of the S-phase in human tumors is 10 to 20 hours. This period is followed by the G2-phase, or period of preparation for mitosis, in which cells contain a tetraploid number of chromosomes. The Gz-phase lasts only 1 to 3 hours for most cell types, with mitosis itself lasting approximately 1 hour. The two daughter cells then enter the Gj-phase, whose duration varies from several hours to days. The Gj-phase also can give rise to a resting state, termed Go, in which cells are relatively inactive metabolically and are resistant to most chemotherapeutic drugs. 

Mitotic effect. STE, administered to the buccal mucosa of 15 female HMT rats, 6 months of age, weekly for 1 year, produced hyperorthokeratosis, acanthosis, numerous binucleate spinous cells, and subepithelial connective tissue hyalinization. Verrucous carcinoma and squamous cell carcinoma were not seen. Karyotyping revealed that lymphocytes of tobacco-treated, as well as control rats, had normal chromosome number and morphology. However, approx 25% of buccal epithelial cells of the tobacco-treated rats were tetraploid and 5% octa-ploid, compared with only 11% tetraploid and no octaploid in the controls. Results indicated that the mitotic process could be disturbed by tobacco treatment b Molluscicidal activity. Water extract of the dried leaf, at a concentration of 168 ppm, produced equivocal effect on Lymnaea luteola . 

Haploids can be produced from tetraploid cultivars and breeding clones via parthenogenesis (Hougas and Peloquin, 1957). When a tetraploid is crossed with any of several selected diploid clones, some of the offspring are diploid. In these crosses, both sperm cells from the pollinator enter the central cell, allowing normal endosperm to develop. This stimulates the division of the egg cell in the absence of fertilization, resulting in the production of a haploid (2x) embryo... 

Rhim, J., Sandgren, E., Degen, J., Palmiter, R., and Brinster, R. Replacement of diseased mouse liver by hepatic cell transplantation. Science 263, 1149. 1994. Weglarz, T., Degen, J., and Sandgren, E. Hepatocyte transplantation into diseased mouse liver Kinetics of parenchymal repopulation and identification of the proliferative capacity of tetraploid and ostaploid hepatocytes. Am J. Pathol. 157, 1963, 2000. 

Life and Death for Proteins Chaperonins and Proteasomes Sickle Cell Disease, Malaria, and Blood Substitutes The T-Even Bacteriophages Mitosis, Tetraploid Plants, and Anticancer Drugs... 

---