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functions as an effective iron-binding and radical-scavenging
antioxidant
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J Insect Physiol. 2004 Sep;50(9):783-90. Related Articles, Links
Antioxidant defense of the midgut epithelium by the peritrophic
envelope in caterpillars.
Barbehenn RV, Stannard J.
Department of Molecular, Cellular and Developmental Biology, University
of Michigan, Ann Arbor, MI 48109-1048, USA. [email hidden]
The peritrophic envelope (PE) is an extracellular matrix that is
secreted by the midgut epithelium in most arthropods. In addition to
protecting the midgut epithelium from abrasive food particles and
microbial pathogens, in vitro experiments have suggested that the PE
functions as a radical-scavenging antioxidant in caterpillars. This
study tested the hypothesis that the PE is a "sacrificial antioxidant"
in vivo in caterpillars. As a sacrificial antioxidant, the PE would (1)
bind catalytic metal ions, (2) become oxidized itself, and (3) protect
the midgut epithelium from oxidative damage. Each of these functions
was supported by our results: the PE in Malacosoma disstria adsorbed
increased amounts of iron as the concentration of iron was increased in
its diet. Iron adsorption by the PE helped protect the midgut
epithelium of M. disstria from oxidative damage over a wide range of
ingested iron concentrations. Secondly, while the midgut epithelium was
protected, protein oxidation in the PE increased 108% when tannic acid
was oxidized in the endoperitrophic space. Finally, when the formation
of the PE was inhibited by Calcofluor, protein carbonyls in the midgut
epithelia of M. disstria and Orgyia leucostigma increased by two- to
threefold. We conclude that the PE functions as an effective
iron-binding and radical-scavenging antioxidant that protects the
midgut epithelia of caterpillars.
PMID: 15350499 [PubMed - indexed for MEDLINE]
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