Re: Croc blood battles superbugs

[Phillip Bigelow <bh162@scn.org>]

On Thu, 23 Mar 2000, Dann Pigdon wrote:

> Phillip Bigelow wrote:
> > 
> > BBC news story at:
> > http://news.bbc.co.uk/hi/english/sci/tech/newsid_680000/680840.stm
> > 
> > I wonder if the same chemical, or a variation of it, is found in birds?
> 
> Frogs and salamanders have something similar, and I suspect the slime coating 
> on
> fish may play a similar role. Perhaps it has more to do with an aquatic
> lifestyle (swamps are notorious places for disease, if that's not an old
> cliche).
> 
> Could perhaps preening oil in some birds also have such chemicals in it?


I don't know if peptides (the chemical that makes up the antibiotic in
croc blood) are stable in air.  It would be an interesting question to
address though. 


> Those
> that need the most oil tend to be water birds. I know that cockatoos grow an
> antibacterial powder on their feathers, which they spread while grooming (a
> scratching cockatoo is usually enveloped in a cloud of white dust).


I guess my questions were more specifically related to cladistics.  The
article stated that the newly-discovered chemical in croc blood (now
dubbed "crocodillin") is a peptide. Peptides form a rather large and
varied group of biochemicals that can contain many different subtypes, and
I was wondering (outloud): 1)  if this general type of peptide is found in
other reptiles (presently that is unknown, according to the article); 2) 
if it is found in other reptiles, does it follow phylogenetic trends or is
it randomly distributed (suggesting convergence); 3) if the general type
of peptide is found in different reptiles, is it closest in chemistry to
the peptide in birds (if birds have it in the first place). 

And if the chemical is only found in birds and crocs, then the degree to
which it is different between the two taxa (if it is different) may give
useful info on it's evolution/modification from the non-avian dinosaurs
(bracketing via cladistics). 

I was also thinking of Big Al and Sue, both of which show bite injuries in
bone that subsequently healed.  Could the natural antibiotic crocodillin
be responsible for the great recuperative powers of theropods with these
types of tramatic injuries? 

On the other hand, the antibiotic may be only found in Recent salt water
crocs, in which case, never mind!  :-) 

                           <pb>