Questions and Answers

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Automatic colony counter

Does anybody have access (or know about access to) an automatic colony counter? I'm looking for a way to count colonies of different colors. Please email kemd@mit.edu with any information. Thanks.

• Reshma 11:45, 11 December 2006 (EST): You could try emailing the biostuff list to reach a wider MIT-specific audience. You may also be able to do something by just taking a photo of your plate and do some sort of image analysis to count colonies. I've never done this but it shouldn't be that different from what people do to identify cells from microscope images. Though that might be an overly complex solution to your problem. Not sure.

Vector LoxP sites flanking two antibiotic marker genes for use in E.coli

I am in need of a low-copy vector (1 to 2 per cell) which carries two antibiotic marker genes. (preferably one sensitive such rpsL, and one resistant such at Tetracycline, Chloramphenicol, etc.) and are FLANKED between two LoxP sites so as once i express Cre recombinase i get recombination between the lox sites and removal of the antibiotic sites. I have rpsL gene at the lab, also i have tetracycline. So even if the plasmid doesn';t carry any antibiotic genes, but has LoxP it would be o.k and i may move in with my construct by subcloning between the sites but that would entail more work... :) Anyone in a position to help? I would also be very happy,whoever wishes,to collaborate and explain better my underlying project. email address: acidmucin@yahoo.co.uk

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• Reshma 08:56, 7 September 2006 (EDT): See Bacterial artificial chromosomes for some options. Some of the BACs listed there have loxP sites. But you have to be careful about which one you use to really get copy number 1-2.

RBS prediction

Is there an online or otherwise easy to use tool for finding RBS sites?

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I've used TIGR's software to do RBS prediction. The program is called RBS finder. Also, if you have a specific sequence you want to test, you can use Stormo's work:

1. Barrick D, Villanueba K, Childs J, Kalil R, Schneider TD, Lawrence CE, Gold L, and Stormo GD. Quantitative analysis of ribosome binding sites in E.coli. Nucleic Acids Res. 1994 Apr 11;22(7):1287-95. DOI:10.1093/nar/22.7.1287 |

Of couse, this is all for E. coli --Sri Kosuri 19:22, 23 March 2006 (EST)

Homologous recombination in E. coli

If anyone has experience with homologous recombination in E. coli please check out the Standard E. coli Strain for BioBricks project and annotate the page with your feedback and comments. Please include any protocols or materials information you might have on the appropriate pages and link to them from the standard strain project page as well. Any and all advice is appreciated.

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See Standard E. coli Strain for BioBricks for comments. Can add more detail later.--Kathleen