Hi Sanjeev,

Have you thought about the following possibility? Did you confirm with western blot that there are good levels of Mre11 in the cell line you are working with? If the Mre11 levels are low in that cell line, it is quite possible that cells mediate the DSB repair without activation of MRN complex, therefore without formation of Mre11 foci.

Please take a look at this paper to support this idea and also you might find conditions to standardise the staining protocol to visualise Mre11 foci in the cells.

http://www.jbc.org/content/278/22/20303.long

Hope it helps!

Satish

hi Satish Bodakuntla

Thanks for the response. The western blot shows good levels of Mre11, in fact there is induction after DNA damage. But antibodies are not working in immunoflurescence experiments under my conditions I guess.

I have searched for Double-strand break repair protein MRE11/Meiotic recombination 11 homolog 1/MRE11 homolog 1 in vain (please see files; HepG2 fucoidan and JMBT alopecia).

This seems to be due to specie differences; i.e., Tetrahymena thermophila (Ciliate) and/or yeast have such a DNA-repair enzyme.

Species differences are present as follows; i.e., (1) humans has no Avidin gene, but bird has it, (2) humans has no Myoglobin, but whale and horse have, (3) humans has no β- Lactoglobulin and α- S2 Casein, but cattle has, (4) humans has no PD-1, but mouse has it; i.e., humans has no notorious Programmed cell death system, (5) I have recently found that human milk has mammary-gland biotinidase, but bovine milk has not it (please see file; The Fascio effect), and (6) humans has no Exosome and no Apoptosis, but Nematode has.

Therefore, notorious Telomere hypothesis is not present in humans.