Polyploidy

But this is not always true large, healthy, beautiful plants, such as numerous popular flowers, may result. However, even when successful, polyploid plants frequently fail to breed true their seeds tend to revert to diploid. Cannabis polyploids arc lar r and have tai er seeds (up to twice normal size) than the diploids and make Cake longer to mature. 

This phenomenon would be of little interest here were it not for some experiments conducted by an American scientist named Warmke during World War II. Treating marijuana plants with colchicine, he obtained a number of triploid and tetraploid and tetraploid plants had about the same average activity (though individual plants varied by a factor of eight) which was about twice chat of the normal diploid strains. He used 26 different plants of each variety and his data were statistically significant. Unfortunately, he worked with an acetone extract of the plants and his assay animals were small fish, making it doubtful whether his data have any relation to cannabinoid content. 

Nevertheless further investigation is necessary. It has been established that tobacco tetraploids have more nicotine than dip-loidSf and this may prove true for the cannabinoid content of marijuana polyploids versus diploids. Again it is to be expected that the total yield will decrease, 

Warmke was also the author of the famous hops-grafting experiments, in which marijuana and hops were grafted onto one another. His data showed transfer of cannabinoids into the hops plants, but he used water fleas as his test animals and the data never had any clear relationship to cannabinoid content Since then it s been shown that cannabinoids are produced locally and do not translocate. In any event, a recent repeat of this latter experiment using modern chemical techniques showed absolutely no transfer of cannabinoids into the hops portion of the grafts—either from the marijuana bottoms to the hops tops or from the marijuana tops to the hops bottoms. Hundreds, perhaps thousands of people, have attempted to produce more potent, or at least undetectable marijuana, on the basis of a few dead fish and water fleas. One is reminded of Mark Twain s comment like science because it gives one such a wholesale return of conjecture from such a trifling investment of fact.  

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Priston RA J, Dean BJ. 1985. Tests for the induction of chromosome aberrations, polyploidy and sister chromatid exchanges in rat liver (RL4) cells. In Ashby J, de Serres FJ, et al., eds. Progress in mutation research. Vol. 5. Evaluation of short-term tests for carcinogens. Amsterdam, The Netherlands Elsevier Science Publishers, 387-395. 

Negative results were also obtained in mammalian cells except for one observation of polyploidy in Chinese hamster CHL cells (Ishidate et al. 1984 Perocco et al. 1983). Treatment at doses up to 5,000 g/mL in the presence or absence of Aroclor 1254-induced male Sprague-Dawley rat liver S9 did not induce chromosomal aberrations in cultured Chinese hamster ovary (CHO) cells. Sister chromatid exchanges were induced in CHO cells but only in the presence of S9 no dose-response was apparent (NTP 1991). 

Chinese hamster ovary cells in which there has been an extensive rearrangement of chromosome material and the chromosome number may not be constant from cell to cell, are frequently used. Polyploidy, endoreduplication and high spontaneous chromosome aberration frequencies can sometimes be found in these established cell lines, but careful cell culture techniques should minimize such effects. Cells should be treated in exponential growth when cells are in all stages of the cell cycle. 

A minimum of three doses of the test material should be used, the highest chosen as described above, the lowest on the borderline of toxicity, and an intermediate one. Up to six doses can be managed satisfactorily, and this ensures the detection of any dose response and that a toxic range is covered. Mis are as required for the preliminary study (at lease 1000 cells per culture). It is also useftd to score endoreduplication and polyploidy for historical data. Cells from only three doses need to be analyzed. 

Nakayama, K., et al., Targeted disruption of Skp2 results in accumulation of cydin E and p27(Kipl), polyploidy and centrosome overduplication. EmboJ, 2000, 19(9), 2069-81. 

Positive results in the mammalian in vivo bone marrow chromosome aberration test indicate that a substance induces stmctural chromosome aberrations in the bone marrow of the species tested. An increase in polyploidy (a multiple of the haploid chromosome number (n) other than the diploid number, i.e., 3n, 4n and so on) may indicate that a substance has the potential to induce numerical aberrations (change in the number of chromosomes from the normal number characteristic of the animals utilized). 

Nakayama, K., Nagahama, H., Minamishima, Y., Matsumoto, M., Nakamichi, I., Kitagawa, K., Shirane, M., Tsunematsu, R., Tsukiyama, T., Ishida, N., et al. (2000). Targeted disruption of Skp2 results in accumulation of cyclin E and p27Kipl, polyploidy and centrosome overduplication, EMBO J 19, 2069-2081. 

Benzidine exposure has been associated with chromosomal aberrations and polyploidy in the circulating peripheral lymphocytes of workers, micronucleus induction in rodents,... 

Mutagenesis Oxcarbazepine increased mutation frequencies in the Ames test in vitro in the absence of metabolic activation in 1 of 5 bacterial strains. Oxcarbazepine and MHD produced increases in chromosomal aberrations and polyploidy in the Chinese hamster ovary assay in vitro in the absence of metabolic activation. 

Levin, D. A. (1983). Polyploidy and novelty in flowering plants. The American Naturalist, 122,1-25. 

Another control mechanism ensures that entry into S phase is only possible if preceded by mitosis. If the cell was able, during G2 phase, to enter a new S phase without mitosis taking place, this would lead to improgrammed multiplication of the chromosome set and thus to polyploidy. For S phase control, see 13.5. 

In vivo in rat hepatocytes, unscheduled DNA synthesis was not induced, and no DNA repair intermediate products were found after exposure to carbon tetrachloride neither micronuclei nor polyploidy were induced in a single study with the same experimental system. Carbon tetrachloride did not induce micronuclei in mouse bone-marrow cells or peripheral erythrocytes. 

Aneuploidy, CBA x C57BL/6 mouse hepatocyte polyploidy - 0.05-0.1 mL/5L Uryvaeva Delone... 

Uryvaeva, I.V. Delone, GV. (1995) An improved method of mouse liver micronucleus analysis an application to age-related genetic alteration and polyploidy study. Mutat. Res., 334,71-80... 

In vivo in mouse bone marrow, hydroquinone induced micronuclei and chromosomal aberrations in several studies but not sister chromatid exchanges in a single study. Hyper-ploidy and chromosome loss (as demonstrated by centromere-positive micronuclei) but not polyploidy were also found in mouse bone marrow. In mouse spermatocytes, chromosomal aberrations and hyperploidy were observed. 

AV A, Aneuploidy, Swiss CD-I mouse bone marrow polyploidy in vivo - 80 ip X 1 Marrazinni etal. (1994b)... 

Amplification of DNA of chromosomes. During formation of oocytes parts of the DNA are "amplified" by repeated replication. This provides a way for the ovum to accumulate ribosomal RNA and various proteins in large amounts. Similarly, genes for two abundant proteins of the egg shell or chorion of insects are amplified. Bidirectional replication initiated at discrete positions yields an "onion skin" structure containing many copies of an 90-kb sequence containing the two genes. The polyploidy observed in some highly specialized cells such as the Purkinje cells... 

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