APPARENT ECDYSONE 20-MONOOXYGENASE ACTIVITY IN THE ADULT PARASITES ASCARIS SUUM (NEMATODA) AND HYMENOLEPIS DIMINUTA (CESTODA)
-
1
University of Toledo, Medicine, United States
Arthropods and nematodes share common developmental patterns in which their growth exceeds the capacity of their exoskeleton/cuticle. Thus, the animals will undergo the process of molting, where the exoskeleton/cuticle is shed and a new larger one is synthesized in its place. Polyhydroxylated keto-steroids, i.e., ecdysteroids, are critical regulators of molting in arthropods. The conversion of ecdysone (E) to the active molting hormone, 20-hydroxyecdysone (20E), at the target tissues for molting hormone action elicits molting. In arthropods the enzyme which converts E to 20E is a cytochrome P450-dependent steroid hydroxylase, ecdysone 20-monooxygenase (E20M), an enzyme highly conserved amongst arthropods. The parasitic nematode Ascaris suum undergoes four molts in its life cycle although the regulation of these molts is poorly understood. Studies with A. suum and another parasitic helminth, viz., the cestode Hymenolepis diminuta, revealed that ecdysteroids including E and 20E are present in tissue extracts of these animals, and that exogenous application of ecdysteroids elicits physiological events. These data suggest that ecdysteroids may play a role in parasite development, so an investigation of the presence of E20M-like activity in A. suum and H. diminuta was initiated. Utilizing a radioenzymological assay for E20M activity in insect tissues, A. suum muscle, reproductive tissue, and whole H. diminuta homogenates were subjected to differential centrifugation and the resulting subcellular fractions assayed. All A. suum muscle and reproductive tissue fractions displayed significant levels of E20M-like activity. Initial evaluations indicated that all H. diminuta fractions also displayed significant activity levels. These appear to be the first indications that the enzyme needed for forming active molting hormone is present in these helminths and that more study is warranted.
Keywords:
20-hydroxyecdysone,
cestode,
Ecdysone,
Ecdysone 20-monooxygenase,
ecdysteroidogenesis,
Endocrinology,
Molting,
nematode
Conference:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011.
Presentation Type:
Poster
Topic:
Developmental endocrinology
Citation:
Drummond
CA and
Fioravanti
CF
(2011). APPARENT ECDYSONE 20-MONOOXYGENASE ACTIVITY IN THE ADULT PARASITES ASCARIS SUUM (NEMATODA) AND HYMENOLEPIS DIMINUTA (CESTODA).
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00015
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
05 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Dr. Christopher A Drummond, University of Toledo, Medicine, Toledo, Ohio, 43614, United States, cdrummo88@gmail.com