Ref ID : 4705
Sergei Ju. Afon'kin; Spontaneous "Depolyploidization" of Cells in Amoeba Clones with Increased Nuclear DNA Content. Arch.Protistenk 131:101-112, 1986
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In "polyploid" clones of Amoeba proteus with the nuclear DNA content increased two- and four-fold as compared with the normal level, the average amount of DNA sometimes appears to be reduced after prolonged cultivation. This reduction is due to the appearance of cells with a two- and, accordingly, a four-fold decreased DNA content. The proportion of such cells in "polyploid" clones grows with time. Nevertheless, "polyploid" cultures may be maintained infinitely via supporting selection. Gradual substitution of "polyploid" cells by normal ones occurs also in artificially mixed amoeban cultures. The presence of aberrant (quadrilobate) nuclei in "polyploid" clones allows the suggestion that multipolar mitosis may be the mechanism of "depolyploidization". A hypothesis is advanced that the processes of spontaneous "polyploidization" and "depolyploidization" in A. proteus take place in nature as well and may be a source of genetical variation in these agamous organisms.