Ultrastructural cytochemistry of the diaminobenzidine reaction in the aquatic fungus Entophlyctis variabilis

Powell, Martha J.

doi:10.1007/bf00410773

Cited by 19 publications

(15 citation statements)

References 51 publications

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“…F) and sodium azide, however, blocked this reaction. These observations were consistent with the expected presence of cytochrome oxidase (cytochrome C) capable of oxidizing DAB in mitochondrial cristae (Powell , ).…”

Section: Resultssupporting

confidence: 89%

“…Aliquots were then washed three times (10 min each) with the appropriate incubation medium buffer (50 mM of either 2‐amino‐2‐methyl‐1,3‐propanediol buffer [AP] at pH 9.2, or cacodylate buffer at pH 7.2). Cells were incubated at 37 °C for 30 min in the standard 3,3′‐diaminobenzidine (DAB) medium (Powell , ) at a final pH of 9.2 or 7.2 (0.06% H 2 O 2 , 2 mg/ml DAB in buffer).…”

Section: Methodsmentioning

confidence: 99%

“…Enzyme inhibitors, boiling, and omission of substrates were used as controls as detailed previously (Powell , ). Cells were preincubated for 45 min at room temperature after aldehyde fixation in one of the following inhibitors: 100 mM sodium azide, 100 mM potassium cyanide, or 20 mM aminotriazole in buffers used in the DAB incubation medium.…”

Section: Methodsmentioning

confidence: 99%

“…As parallel nonreaction controls, some cells remained in 50 mM cacodylate buffer, pH 7.2, or AP buffer, pH 9.2, during the DAB incubation step (=minus DAB and hydrogen peroxide controls). A volume of at least 10 times that of the cells was used for the incubation medium to maintain initial pH of the medium (Powell ).…”

Section: Methodsmentioning

confidence: 99%

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Cytochemical Localization of Polyphenol Oxidase Activity in K2‐Bodies of Saprolegnia ferax Secondary Zoospores

Lehnen

Powell

Letcher

2018

J Eukaryotic Microbiology

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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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Section: Resultssupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Cytochemical Localization of Polyphenol Oxidase Activity in K2‐Bodies of Saprolegnia ferax Secondary Zoospores

Lehnen

Powell

Letcher

2018

J Eukaryotic Microbiology

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“…reference 55), I have used the term microbody to designate this organelle in Rozella, which is in agreement with several recent reports on other zoospores (8,24,29,48) and is in preference to the term Stuben body (7, 11) or to other terms (4,21,30,32). Recently, Powell (40) has found that in the zoospore of Entopklyctis sp., a microbody associated with the lipid globule contains catalase and also functions as a glyoxysome. The latter term designates a special class of microbody Can.…”

Section: Discussionmentioning

confidence: 99%

The zoospore of Rozella allomycis: ultrastructure

Held¹

1975

Can. J. Bot.

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The small (about 2 × 3.5 μm) zoospore of the obligately parasitic chytrid Rozella allomycis provides yet another ultrastructural variation on the basic pattern of posteriorly uniflagellate fungal zoospores. This zoospore contains the expected array of organelles: nucleus, mitochondria, "lipid sac" (including lipid globules, a microbody, and a backing membrane), kinetosome, and second centriole. Ribosomes are dispersed throughout the cytoplasm. In the disposition of its microbody Rozella resembles other chytrids, whereas in the occurrence and location of its gamma-like vacuoles it resembles certain blastocladialean fungi. Above all, the zoospore resembles that of Olpidium brassicae. Structural peculiarities of the zoospore include (i) bilateral symmetry; (ii) a helmet-shaped nucleus with extensive membranous projections which surmounts a large, spheroidal mitochondrion; and (iii) a particularly elongate cell shape because of the unusual length (about 1 μm) of the kinetosome and the presence of a 1-μm-long flagellar cavity which surrounds the base of the flagellum. Cytoskeletal elements include cytoplasmic microtubules, microfilaments which mainly reinforce the flagellar cavity, and props which anchor the kinetosome in the plasmalemma at the roof of the flagellar cavity. The role of these elements is discussed. A revision of the description of the olpidiaceous zoospore is suggested.

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What Are the Chromidia of Polyphagus Euglenae?

Powell

1979

American J of Botany

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Zoospores, prosporangia, and asexual sporangia were studied with electron microscopy to determine the ultrastructural identification of “chromidia,” granular masses surrounding nuclei that classical mycologists believed to be extruded chromatin used for lipid synthesis. In the zoospore the nucleus was enclosed by an aggregation of ribosomes. In other developmental stages the behavior of microbodies was identical to that described for “chromidia.” A microbody network with interspersed ER surrounded nuclei in young prosporangia. As the prosporangium matured, lipid globules became associated with the microbodies. When the single, large nucleus migrated into the elongate asexual sporangium, microbodies still surrounded the nucleus; but after the nucleus divided and a multinucleate sporangium formed, microbodies were scattered throughout the cytoplasm. When incubated in the diaminobenzidine medium for the cytochemical detection of catalase, reaction product was found in these microbodylike structures, confirming that “chromidia” described in prosporangia and asexual sporangia by classical mycologists are really microbodies. Rather than giving rise to lipid, these microbodies are probably involved in the metabolism of the lipid globules with which they are associated. The “chromidia” in zoospores are not extruded chromatin as suggested earlier, but correspond in their location around the nucleus to an aggregation of ribosomes.

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Ultrastructural cytochemistry of the diaminobenzidine reaction in the aquatic fungus Entophlyctis variabilis

Cited by 19 publications

References 51 publications

Cytochemical Localization of Polyphenol Oxidase Activity in K2‐Bodies of Saprolegnia ferax Secondary Zoospores

Cytochemical Localization of Polyphenol Oxidase Activity in K2‐Bodies of Saprolegnia ferax Secondary Zoospores

The zoospore of Rozella allomycis: ultrastructure

What Are the Chromidia of Polyphagus Euglenae?

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