Analyzing growth in cell cultures. II. Effect of initial cell mass on growth

Abstract

Numerous factors must be considered when analyzing growth in a cultured cell system. One extremely critical factor is the initial cell mass. The effect of initial mass (10 to 400 mg) on growth rate was assessed for cell lines tolerant and susceptible to the herbicides 3-amino-1,2,4-triazole (amitrole) and N-(phosphonomethyl)glycine (glyphosate). For a given cell line, the relationship between initial mass and growth rate was comparable in the presence and absence of the growth inhibitors. However, among cell lines the response varied. For one amitrole- and glyphosate-tolerant cell line, increased initial callus mass resulted in an increased relative rate of growth. However, the opposite effect was observed for another cell line which was also tolerant to both herbicides. For a third cell line which was herbicide sensitive no initial mass effect was observed. A fourth cell line (amitrole tolerant – glyphosate sensitive) also showed no initial mass effect except for the very small 10-mg calluses, which had significantly lower growth rates. The observed effect of initial mass was dependent on the method of calculating growth rates.