S. Lustigman et al., TRANSGLUTAMINASE-CATALYZED REACTION IS IMPORTANT FOR MOLTING OF ONCHOCERA-VOLVULUS 3RD-STAGE LARVAE, Antimicrobial agents and chemotherapy, 39(9), 1995, pp. 1913-1919
Highly insoluble proteins, which are probably cross-linked, are common
in the cuticle and epicuticle of filarial parasites and other nematod
e species. We have investigated the possible involvement of transgluta
minase (TGase)-catalyzed reactions in the development of Onchocerca vo
lvulus fourth-stage larvae (L4) by testing the effects of TGase inhibi
tors on the survival of third-stage larvae (L3) and the molting of L3
to L4 in vitro. The larvae were cultured in the presence of three spec
ific TGase inhibitors: monodansylcadaverine, cystamine, and ,L-beta-(3
-bromo-4,5-dihydroisoxazol-5-yl)-alanine benzylamide. None of the inhi
bitors reduced the viability of either L3 or L4, However, the inhibito
rs reduced, in a time- and dose-dependent manner, the number of L3 tha
t molted to L4 in vitro. Molting was completely inhibited in the prese
nce of 100 to 200 mu M inhibitors. Ultrastructural examination of L3 t
hat did not molt in the presence of monodansylcadaverine or cystamine
indicated that the new L3 cuticle was synthesized, but there was an in
complete separation between the L3 cuticle and the L4 epicuticle. The
product of the TGase-catalyzed reaction was localized in molting L3 to
cuticle regions where the separation between the old and new cuticles
occurs and in the amphids of L3 by a monoclonal antibody that reacts
specifically with the isopeptide epsilon-(gamma-glutamyl)lysine. These
studies suggest that molting and successful development of L4 also de
pends on TGase-catalyzed reactions.