> Does anyone know or have thoughts on whether bacterial genomes are in a
> state of expansion (perhaps by horizontal transfer of genes, eg.
> pathogenicity islands), or in a state of reduction (eg, deletion of
> intergenic spaces to form operons).
This depends on whether you include natural or biotechnology inputs. In
terms of expansion based on gene transfer, the success of these transfers
conferring better survival depends on the environmental stimulas present.
In the instance of antibiotic resistance genes conferring better survival,
this trait will evolve and be passed to successive generations only if
antibiotic pressure persists (eg. we keep using antibiotics). Traits that
are not necessary are rapidly lost simply by the selection of mutants
withotu the trit that grow better, this is especially fast with traits on
plasmids.
I think this is very hard to pin down for a particular isolate, or even
trait unless you really narrow the parameters of your tests.
> Over time can we expect bacterial genomes to become more compact or
acquire more DNA from other sources?
This depends solely on the stimulus to acquire or keep the traits and the
growth rate and mutation frequency of the organism..
Just my thoughts.....
>>> Your thoughts are most appreciated!
>> David
>>>> David J. McGee, Ph. D.
>dmcge001 at umaryland.edu>> University of Maryland, Baltimore
> Department of Microbiology and Immunology
> 13009 Bressler Research Building
> 655 W. Baltimore St.
> Baltimore, MD 21201
>> Lab Phone: 410-706-0466
> Fax: 410-706-6751
>>
