Nucleoli and ploidy in Potorous cells (PTK2) in vitro

Abstract

Abstract. Most cells of the male PTK2 cell line contain one nucleolus, and they are diploid. However, a proportion of cells have more than one nucleolus. Cells with two and three nucleoli were isolated and cloned into viable populations. Greater than 90% of the cells in these clonal populations maintained the abnormal nucleolar number of the originally isolated cell. Karyotype analysis of cells with two and three nucleoli demonstrated that the cells were respectively tetraploid and hexaploid. It was concluded that in PTK2 cells, nucleolarity is a good index of ploidy even if the ploidy level is abnormal. Furthermore, long term monitoring of the tetraploid cells demonstrated virtually no tendency towards reversion to the diploid condition as suggested by other studies in Potorous.

Chromosome Numbers in Kiwifruit (Actinidia deliciosa) and Related Species

“…Our limited study with A. arguta leads us to speculate that there is a step-wise increase of nucleoli with and increase in ploidy. Such a correlation has been reported for Potorous cells grown in vitro (2).…”

Genetic microsurgery by laser: establishment of a clonal population of rat kangaroo cells (PTK2) with a directed deficiency in a chromosomal nucleolar organizer

“…The nucleolar organizers are on the X chromosomes and are recognizable as secondary constrictions just below the centromerie constrictions. In both the diploid and tetraploid lines, there is a close correlation between the number of nucleoli and the number of X chromosomes: diploid PTK2 cells have one nucleolus and tetraploid PTKzWA cells have two nucleoli (Branch and Berns, 1976).…”

“…The cells used in this study are from a tetraploid clonal subline that was derived from near diploid male rat kangaroo PTK2 (modal chromosome number 12-13), Potorous tridactylis, cells (Branch and Berns, 1976). The tetraploid line is designated PTK2WA and its modal chromosomal number is 24-25.…”

“…The resulting post-mitotic cells from such an irradiation do not produce any normal nucleoli nor are the cells capable of subsequent mitosis . A tetraploid subline has been established which has two X chromosomes with visible nucleolar organizer genetic regions and, therefore, two nucleoli per cell (Branch and Berns, 1976).…”

Silver staining of nucleolar organizers and nucleoli during mitosis and interphase of mammalian cells

“…The number ofnucleoli during interphase was also two in the case of female rat-kangaroo cells (Ohnuki et al, 1972). Male rat-kangaroo ceils with only one X chromosome contain only one nucleolus (Branch & Berns, 1976).…”