What is a mutation?

Anders Gorm Pedersen gorm at cbs.dtu.dk
Fri Sep 22 02:23:28 EST 2000

Angela - 

the common use of the word mutation includes ANY change from the
original state, including point mutation, insertion (also of transposons
and phages), deletion, translocation, and inversion (I guess this is
what you meant by "reversion"?).

If your original strain was not able to grow in the presence of CB, then
it's probably not just enzymatic regulation, but indeed an actual
mutation. Apart from that I'm curious about why you think CB-resistance
is caused by a reversion leading to changed expression. Is this based on
Southerns? If there is an inversion isn't it possible that it has
disrupted a gene imvolved in CB-sensitivity (e.g., something involved in
transporting CB into the bacterium?).

Best regards,

Angela Merlo wrote:
> Hi everyone in this newsgroup.
> Maybe you think that my question is very simple, but for me is not very
> clear.
> I research the adaptation of one bacteria to grow in a media (with
> chlorbenzoate) where normaly it can=B4t grow. It seems for me that there
> is not  enzymatic regulation but a "mutation", so changes in the genome.=20
> I would say that: if there are changes in the genome, then there is a
> mutation. After making some experiments, it look like it could have
> been  a reorganisation in the chromosome, homologous recombination,
> insertion...=20
> That is: the genes for degrading CB are already in the cell, but somehow
> not expressed untill they move to an appropiate place in the chromosome.
> I haven=B4t finish my experiments but I guess that there is a reversion,
> and if I culture the "mutant" again in a rich medium they loose the
> ability to grow in CB.=20
> Can I say it is a genome regulation?, an adaptive mutation?, a
> mutation?... Is there any exact definition accepted by the mayority of
> scientific community?
> Any clue?
> Thanks
> Angela
> ---

 Anders Gorm Pedersen, cand.scient., Ph.D.  (gorm at cbs.dtu.dk)

 Center for Biological Sequence Analysis
 Technical University of Denmark
 Bldg 208, DK-2800 Lyngby, Denmark

 phone: (+45) 45 25 24 84
 fax:   (+45) 45 93 15 85

 Web: http://www.cbs.dtu.dk/gorm/

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