Cytochemical Localization of Polyphenol Oxidase Activity in K2-Bodies of Saprolegnia ferax Secondary Zoospores.
J Eukaryot Microbiol
; 66(3): 404-412, 2019 05.
Article
em En
| MEDLINE
| ID: mdl-30099810
ABSTRACT
Zoospores of the oomycete Saprolegnia ferax release adhesive material from K-bodies at the onset of attachment to substrates. To understand more fully how K-bodies function in adhesion, enzyme activity was investigated cytochemically in secondary zoospores. Presence of catalase, a marker enzyme for microbodies, was explored in the diaminobenzidine (DAB) reaction. Although pH 9.2 DAB-staining characteristic of catalase activity was detected in the granular matrix regions of K-bodies, reaction controls indicated that the reaction was due to oxidative enzyme activity other than catalase. Because polyphenol oxidase (PPO) is another metal-containing enzyme capable of oxidizing DAB, activity of this enzyme was tested with a more specific substrate, dihydroxyphenylalanine (DOPA). In the DOPA procedure, reaction product was exclusively localized within K-bodies, indicating the presence of PPO. Results with three methods of reaction controls (elimination of substrate, addition of a PPO enzyme inhibitor, and heat-inactivation of enzymes) all supported the presence of PPO in K-bodies. This study highlights potential roles for K-body PPO in stabilization of adhesion bodies by cross-linking matrix phenolic proteins or glycoproteins as K-bodies discharge adhesives onto substrates, or polymerizing phenolics protective against microbial attacks of the adhesion pad.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Catecol Oxidase
/
Saprolegnia
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article