Chitin biosynthesis in imaginal discs cultured in vitro

We have investigated the stimulation of cuticle production by imaginal discs ofPlodia interpunctella in tissue culture. We turned to biochemical methods to assess the quantitative effects of beta-ecdysone on chitin biosynthesis in wing discs incubated with 0.5 μC of C¹⁴-glucosamine for the final 24 h of culture.We demonstrated that imaginal discs ofP. interpunctella respond to increasing concentrations of β-ecdysone with increased synthesis. The threshold is between 0.01 and 0.1 μg/ml of hormone (2×10^-8 M to 2×10^-7 M). These data represent the first demonstration of quantitative biosynthesis of chitin by a developing tissue in vitro in relation to varying amounts of hormone. Additionally, protein synthesis during the β-ecdysone-dependent period was necessary for chitin synthesis. This system thus lends itself to a detailed investigation of the control of chitin biosynthesis.