"Could you start a thread for Bob OH and I to continue arguing about whether mycelial colonies are, in the context of evolution, single multi-celled organisms or collections of individual single celled organisms. My position is that they are the latter and that evolution can take place within a single colony via various mechanisms including gene induction.
"I bring this up because I have resumed experimenting with a volvariella volvacea colony which had apparently (barring experimental error on my part) acquired the ability to break down high concentrations of hydrogen peroxide. I hypothesized that the ability was due to gene induction whereby (probably through methylation) a peroxide decomposing enzyme was inducted. I further hypothesized that the induction would be sticky and would persist across generations of mycelia even in the absence of high peroxide concentrations.
"After a long distraction I just recently recultured the h2o2 resistant colony. It has been living in a more or less dormant state on a non-peroxide agar plate (several plates actually) for about 7 weeks now. I recultured it onto fresh non-peroxide agar yesterday and it is already showing new growth so it's still a vibrant, normal colony on its usual PDA medium. I have also prepared agar plates with various concentrations of peroxide to reculture these onto as soon as they grow out (4-5 days). The original colony took 2 weeks to adapt to the peroxide. If my hypothesis is correct the colony I'm growing out now shouldn't have any lag time when recultured onto the new peroxide plates."
Saturday, June 24, 2006