Dynamics of Tetrahymena macronuclear lamina during cell division

Abstract

During mitosis, the nuclear lamina in higher eukaryotic cells undergoes a distinctly morphological change. It breaks down into lamin polymers or monomers at prophase. At telophase, the lamins reassemble around the condensed chromatin to form the layer of lamina. Using antiserum to mammalian lamins, we studied the dynamics of lamina during cell division in the macronuleus of Tetrahymena shanghaiensis, which divided in the way of amitosis. In contrast to those in higher animal cells, the typical perinuclear lamin distribution in the macronucleus persisted throughout the whole cell cycle. It was further found that in some synchronized cells, the lamin distribution displayed an unusual pattern consisting of a series of spots within the macronucleus. Using South-western hybridization, we found that the purified 66 KD lamin in Tetrahymena showed specific affinity with the telomere DNA sequence in the same species. Therefore, we propose that pattern of immunofluorescence may be due to the interaction of lamin protein with the nucleoli and the condensed chromatins in the macronucleus.