In Article <Pine.3.89.9503311527.A577061232-0100000 at utkvx.utk.edu>
ctfaulkn at UTKVX.UTCC.UTK.EDU ("Charles T. Faulkner") writes:
>I believe the questions still goes back to
>measurement scale for describing net effect on host. Pathogenicity is a crude
>meassure.... nutrient robbing (metabolic dependence) no matter how small
>seems more appropriate.
In retrospect, equating metabolic dependence with nutrient robbing
was an unforunate lapse of attention on my part. I recognize that metabolic
dependence can extend to other aspects of the parasite's
bio-chemistry/physiologic requirements (eg. reproduction, evasion of host
immune response, etc.) besides fullfiilling its nutritional requirments.
Also, the parasite's metabolic dependence does not necessarily have
to be limited to competion between host and parasite for nutritional resources
does it? Perhaps the parasite is dependent on a host enzyme or other metabolite
which is produced in abundance and excreted by the host as waste? The idea
that it cannot survive outside of a narrow suite of host conditions and
requires some substance produced by the host (even in excess) suggests that
this organisim is a parasite of the host. Net negative effect may be sufficent
for defining a parasite, but I don't feel that it is a necessary condition.
**********************************
* Charles T. Faulkner * When you don't know where you're
* Univ of Tennessee, Knoxville * going any road will take you there.
* (ctfaulkn at utkvx.utk.edu) * Alice
*********************************
