1 00:00:09,246 --> 00:00:11,996 Sally: This is Systems Sally. 2 00:00:11,996 --> 00:00:12,706 Dude: Hey Sally. 3 00:00:12,706 --> 00:00:13,456 It's Dude. 4 00:00:13,456 --> 00:00:15,206 Sally: Dude, are you OK? 5 00:00:15,206 --> 00:00:16,576 You sound out of breath. 6 00:00:16,576 --> 00:00:19,276 Dude: Well I started growing some bacterial cells with Izzy last night, 7 00:00:19,276 --> 00:00:23,296 and today I had to get to practice but coach kept us late and now I'm worried that the cells. 8 00:00:23,296 --> 00:00:24,456 Sally: Dude? 9 00:00:24,456 --> 00:00:25,196 You still there? 10 00:00:25,566 --> 00:00:26,426 The cells what? 11 00:00:27,426 --> 00:00:28,836 Dude Well I guess I don't really know. 12 00:00:29,156 --> 00:00:32,126 Izzy said dog phase but that seems wrong. 13 00:00:32,236 --> 00:00:34,786 Sally: Izzy probably said log phase which is 14 00:00:34,786 --> 00:00:37,436 when the cells are actively growing and dividing. 15 00:00:37,436 --> 00:00:41,056 If you have some bacteria growing, I'm happy to put the cultures on ice. 16 00:00:41,146 --> 00:00:44,716 That will slow down their growth, and you can measure their density when you get here. 17 00:00:44,716 --> 00:00:45,866 Dude: Thanks Sally! 18 00:00:45,866 --> 00:00:50,126 Last night we put two flasks at room temperature and two in the 37 degrees incubator. 19 00:00:50,476 --> 00:00:51,876 I'll be there as fast as I can. 20 00:00:55,966 --> 00:00:56,796 Izzy: Hi Sally. 21 00:00:56,796 --> 00:00:57,576 Have you seen Dude? 22 00:00:57,576 --> 00:00:59,346 Sally: He just called to say he's on his way. 23 00:00:59,496 --> 00:01:02,306 I'm putting these cultures on ice, but look: the ones that were 24 00:01:02,306 --> 00:01:04,436 at room temperature don't seem to have grown much. 25 00:01:04,646 --> 00:01:05,946 Izzy: I was a little afraid of that. 26 00:01:06,036 --> 00:01:09,166 They carry a high-copy protein generator that Dude and I made, 27 00:01:09,166 --> 00:01:12,606 but the growth of the cells takes a real hit when they carry this plasmid. 28 00:01:12,666 --> 00:01:17,456 We've seen them spend 12 hours in lag phase and then take two days to reach stationary phase. 29 00:01:17,536 --> 00:01:20,566 Without the plasmid, it's more like 4 hours to go from lag 30 00:01:20,566 --> 00:01:22,556 to log and they're saturated overnight. 31 00:01:22,556 --> 00:01:24,086 Sally: When did you start these growing? 32 00:01:24,196 --> 00:01:27,366 Izzy: About 8:00 last night we diluted the strain 1:1000. 33 00:01:27,366 --> 00:01:31,156 And I don't think these have grown much since then, but I'll measure their density anyway. 34 00:01:31,516 --> 00:01:35,076 Sally: The cells that were growing at 37 degrees look a little more dense. 35 00:01:35,196 --> 00:01:37,356 Maybe they're doubling at an almost normal rate. 36 00:01:37,906 --> 00:01:38,276 Izzy: Yup. 37 00:01:38,346 --> 00:01:42,646 Their density has definitely changed since yesterday and if Dude gets here fast, 38 00:01:42,646 --> 00:01:46,306 we might be able to catch them in log phase and transform in a control device. 39 00:01:46,306 --> 00:01:48,566 Sally: You might also want to count the cells since some 40 00:01:48,566 --> 00:01:49,946 of the light scattering you're measuring 41 00:01:49,946 --> 00:01:52,526 at the spectrophotometer could be coming from cell debris. 42 00:01:52,526 --> 00:01:54,926 Izzy: I hadn't thought about that, but you're right. 43 00:01:54,926 --> 00:01:58,636 I'll teach Dude to count cells when he gets here Sally: One other thing that I've seen happen is 44 00:01:58,636 --> 00:02:01,616 for the cells to lose a plasmid if it's making them sick. 45 00:02:01,616 --> 00:02:04,536 You and Dude might want to check that the cells are still resistant 46 00:02:04,536 --> 00:02:07,126 to whatever antibiotic marker you have on the plasmid. 47 00:02:07,126 --> 00:02:08,076 Dude: Hi Sally! 48 00:02:08,076 --> 00:02:09,956 Hi Izzy! Sorry to be late. 49 00:02:09,956 --> 00:02:11,506 I hope you've left me some things to do. 50 00:02:11,776 --> 00:02:13,646 Izzy: In lab there's always plenty to do. 51 00:02:13,646 --> 00:02:18,586 Let's get started figuring out what's going on Dude: Getting here, I saw the most amazing pack 52 00:02:18,586 --> 00:02:20,666 of dogs getting walked over the bridge.