Reading into strange results

Last entry finished with:

“…We repeated the experiements over a new culture of 3G S. meliloti strain (I remind you the previous was 3I). In which every treatment (0, 15 and 30 seconds of uv) was made twice. Now, Plates are in Paula’s home (and also in the Lab).

Hopefully, these new results allow to determine uv effect more accurately. …”

The experiment performed was plates 1 and 4 no uv treatment; plates 2 and 5, 15’’ uv treatment; and plates 3 and 6, 30’’ uv treatment.

However,  last results did not show the expected numbers (Fig. 1). 

Fig 1: Aspect of all plates incubated at Paula’s home after 6 days at room temperature.  Numbers and dilutions performed are indicated in the last blog entry. 

Analyzing the plates we found that uv treatment was properly made on both groups of plates (those growing on Paula’s home and also the lab one). However, the plates to count the mutants present in every culture give an unexpected  high numbers,  even in the most diluted plates (see figure).

What is the explanation of this strange result? 

Have we got a different mut frequency in this experiment?

If we analyze the differences in the protocol with the previous experiment performed, we can inffer where it could be the problem. Also we can see in the previous blog (¿Dónde mutan los genes?) some clues about what could occur in this last experiments (particularly in the post Consecuencias del brain storming).

I would like we could discuss here in the blog what is happening; how we can avoid it and try to repeat properly the experiment (Next session 2nd of March).

I encourage you to give an answer. Who is the first?? (specially those who came on last experimental session).

Francisco Martínez-Abarca

Estación Experimental del Zaidín. CSIC.

Departamento de Microbiología y Sistemas Simbióticos.

Granada