To investigate the non-genetic variability of the division cycle and growth of single cells, we compared pairs of Eschertchia coli daughter cells' growth and division time under isolated conditions using a newly developed on-chip culture system. The advantages of the system are: (i) continuous cultivation of isolated single cells or a group of cells in μm-sized micro-cages under isolated contamination-free and exchangeable medium conditions, and (ii) continuous observation and comparison of those floating daughter cells at a spatial resolution of 0.2μm by phase-contrast/fluorescence microscopy and digital image processing. Using this system, cell growth and division time of daughter cells from an isolated mother cell were measured. A broad distribution of the cell division time and the division time differences of two daughter cells from the same mother cells were found. They are not attributable to a difference in DNA. The same tendency of broad distribution of the division time and the division time differences suggests the involvement of a probabilistic process to start the division.
Mating reaction occurs between the cells of the odd and even complementary mating types in Paramecium caudatum. The molecules involved in this cell-to-cell sexual recognition called mating type substances are suggested to be proteins and exist on the ventral surface cilia of the cell. To obtain more varied epitopes, mating-reactive membrane vesicles reconstituted from odd mating type cilia of syngen 3 were used as antigen. A new monoclonal antibody XomO inhibiting the mating reactivity of both mating types was obtained. The unusual characteristic of XomO is the localization of the antigen, which particularly is recognized on basal portion, and not the whole length, of the ventral surface cilia. The antigen was suggested to be membrane protein and the detection of the antigen was correlated with the mating reactivity of the cells. These results suggest that the antigen of XomO is a substance involved in mating reaction under a dynamic-conformational change.
Analogs of the tetrahydropyran acetogenin, muconin, were synthesized from D-glutamic acid in a stereocontrolled manner, and their in vitro cytotoxicity against human cervical carcinoma HeLa S3 cells was evaluated.