isotope labelling of cells?

[Punita]

Hi all.

I wondered if you could help me understand something. Is it possible to isotopically label whole cells with particular isotopes (for example C-13, N-15 etc,.)? If so, what are the various methods to do this?
Appreciate any help!

Kind regards, Punita

[mith]

Once you've isolated the cell, grow it in a culture with radioactive Nitrogen DNA.

[canalon]

Or you can look up the use of SIP (stable Isotobe Probing) in microbial ecology.

[Punita]

Thanks you guys! That was really helpful!
Best wsihes. Punita

[biohazard]

One can also label cell surface antigens with radioactively labelled antibodies, although enzymatic labels have largely replaced radioactive isotopes in this.

Another common method is putting isotopes in the medium, like Mith wrote. In our lab we use tritium-labelled thymidine, which the cells then incorporate into their dna and this can be measured with scintillation counters that measure beta decay. Tritium is a weak radiation source and thus fairly safe to use, yet reliable to measure.

[Sepals]

Cells can also be grown in the presence of other isotopes such as iodine and phosphate. Using isotopes ("hot labelling") is often considered dangerous and are being replaced by "cold labelling" where as Biohazard pointed antigens are used. This is referenced to as serology. Either fluorescent molecules can be attached directly to an antigen or to an immunoglobin specific to the antigen (making the procedure more sensitive). There are loads of other serological methods such as ELISA (enzyme linked immunosorbent assay) which is very popular. Antibodies attach to antigens expressed by infected cells, resulting in an enzymatic reaction which changes the colour of the substrate to, for example, green.