Question

spotsnall katzday at tamu.edu
Wed Jan 19 10:06:37 EST 2000


In article <38867155.15360487 at news.rdu.bellsouth.net>, dmj7 at bellsouth.net 
says...
>
>Genus:  Yes
>Species:  Yes
>Strain:  Depends, but some strains are defined on other attributes.  I
>wouldn't count on this one.
>
>
>On Mon, 17 Jan 2000 06:06:47 GMT, "Anson Li" <ansonli at infoserve.net>
>wrote:
>
>>Hi everyone,
>>
>>This may seem stupid...but I've always wondered about PCR ribosomoal
>>typing.  If we amplify out the rRNA variable region, can we narrow
>>a bacteria down to its genus level?  species?  or all the way down to its
>>strain level?
>>
>>
>
Strain is an interesting word--both ribotyping  and pulse-field gel 
electrophoresis ( restriction polymorphism patterns) can tell lots about
strains. E.g., are two "strains" clonal, are the genetically different.

But the term strain has little meaning in taxonomy.  "A strain of 
microorganisms is a particular example, specimen, or culture of a given 
species." (From Frobisher et al.)


So perhaps the question can be recast-- can the above be used to differentiate
subspecies, biotypes, serovars, phage types. 

Because if two labs have two different strains, let us say for example isolates
of Staph from patients,  they may well have two organisms which are essentially
isogenic, geneticially identical, clonal, and the two strains are of identical
organisms.


[I have hedged a bit with isogenic-- there is always a chance one base pair
somewhere has been switched about with not consequence.]





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