Worm Breeder's Gazette 9(2): 52

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

A CCK-like Neuropeptide in Ascaris

C. Cowden and A.O.W. Stretton

Our aim is to obtain peptides of known sequence from Ascaris in 
order to determine their mode of action using electrophysiological 
methods.  Since McIntire and Horvitz (C.  elegans CSH Abstracts 1985) 
showed that cholecystokinin-like immunoreactivity (CCK-LI) is present 
in certain neurons in C.  elegans, we are initially investigating the 
role of a CCK-like peptide (CCK-LP) in the nervous system of Ascaris 
using anti-CCK8 antisera to detect and localize CCK-LI.
Using the methods developed by Johnson (see Johnson and Stretton, 
Soc.  Neurosci.  Abstr.  9: 302; Sithigorngul, Johnson and Stretton, C.
elegans CSH Abstracts 1985) we find that in Ascaris, CCK-LI is 
concentrated in 2 cells (AVF cells) in the ventral nerve cord, in 3 
cells in the ventral ganglion, in 4 processes in the ventral cord, and 
in 2 processes in the lateral line.  Thus the CCK-LP is concentrated 
in a small minority of the 180 neurons present in the anterior region 
of adult Ascaris.We have developed a procedure for extracting the CCK-
LP from C.  elegans and fractionating the extract on a C18 cartridge.  
High voltage paper electrophoresis shows that added radioiodinated 
CCK8 is chemically intact after this extraction and after 
fractionation.  The CCK-LP was separated from more hydrophilic 
components with a 20-40% gradient of acetonitrile on reversed phase 
HPLC.  RIA's detected CCK-LI associated with a peak of optical density.
Addition of authentic CCK8 (non-sulfated) to the sample showed that 
the RIA-positive peak was close to, but distinctly separate from, CCK8.
Assuming that the specific immunoreactivity of nematode CCK-LP and 
mammalian CCK8 is the same, we can obtain 100 pmoles from 60g of C.  
elegans.  From this crude estimate, it seems that the levels of 
recoverable peptide are sufficient for amino acid sequence 
determination which is now our top priority.