crypto question

Sun Mar 26 22:00:04 EST 1995

>mbernhar at wrote:

>To:            parasite at
>From:          mbernhar at (mat bernhardt)
>Subject:       crypto question
>Date:          25 Mar 1995 01:49:38 GMT
>does anyone know whether the oocyst walls of crypto possess any 
>mbernhar at

I don't know the answer for the intact wall, but part of the oocyst 
antigen reported in the literature is highly charged (Lally,N.C., 
Baird,G.D., McQuay,S.J., Wright,F. and Oliver,J.J. (1992)  A 2359-base 
pair DNA fragment from Cryptosporidium parvum encoding a repetitive oocyst 
protein. Mol. Biochem. Parasitol. 56, 69-78; Genebank M95743).

This gene fragment contains an ORF encoding 786 amino acids, containing 31 
D, 45 E, 32 H, 39K, 58 Q & 22 R residues, roughly 10% negative charges and 
19% positive changes.  Plenty of charges, but does this represent the 
general oocyst surface?  I suspect much of the surface may be 

Has any one measured the charge on the oocyst surface?  Obviously it would 
infuence its ability to stick to surfaces (eg clay particles, humus) and 
rate of sedimentation.  Perhaps Alan Champion can comment?

Cheers, Martin Slade

Martin Slade,
School of Biological Sciences,
Macquarie University,
NSW 2109,
FAX  (61 2) 850 8174
Phone(61 2) 850 8210

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