Thursday, June 18, 2009

It turns out that the cells I was making MIV-competent were growing immensely slowly. RR's last comment said if all my optical density (OD) points went through an exponential line, I had started with a small number of viable cells. Alas, this was not the case. Bring out the graphs!

As you can see, the points aren't quite exponential. :S Why? Well, I am indeed running growth curves today for KW20, RecJ-, dprA-, and RecJdprA-- strains. It's been about 3 hours, and growth does seem quite slow. I'm also planning to run a gel on some DNA I made a few days ago. I extracted these chromosomal DNAs from the RecJ-, ExoI-, and RecJExoI-- strains I made from the Oxford DNA. We're going to check them with PCR (my primers are here!). I also read over Josh's blog post on linkage. I'll have to reread it to understand it better (it's not your writing, it's me :]).

1 comment:

Rosie Redfield said...

There's another issue. You're measuring OD, which gives equal weight to viable and dead cells. So, if your inoculum (none of my spellings of this word are acceptable) consists mostly of dead cells, your OD values will not reflect the number of viable cells in the culture. That could explain why your initial points fall above the line defined by your later points. If all the cells are growing, but they're all just growing slowly, the points will fall on a straight line with a low slope.