PubMed Health⌕ Search

Biomedical subjects

G Casperson

Publications and source records attributed to G Casperson.

11 recordsLinked to original sources
PubMed1986

[Effect of 2-ethyl-2-ene-1-al and analogous compounds on the growth and ultrastructure of fungi].

Analogs of the natural substance (E)-hex-2-en-1-al which occurs naturally in green plants and is known to have microbiocidal properties were synthesized and studied with respect to their antifungal properties. Saturated and unsaturated aldehydes, alcohols, carbon acids and enolacetate were tested against various fungi by applying these compounds either over the gaseous phase or in suspension. The following ranking was observed on the basis of fungicidal activity: enolacetate of 2-ethylhex-2-enoic acid greater than 2-ethylhex-2-en-1-al greater than 2-ethylhex-2-en-1-al greater than 2-ethylhex-2-en-1-ol. Saturated analogs showed the same order of activity as the unsaturated ones, however, they were less efficient. The effects on the ultrastructural changes were analyzed in Mucor mucedo exposed to concentrations of the analogs that inhibited growth. Main effects were observed on mitochondrial and nuclear membranes. The kind of destruction caused by enolacetate of 2-ethylhex-2-en-1-al differed from the other substances tested. Aspects of the mode of action are discussed.

Acetates↗
PubMed1984

[Use of cytochemical methods for diagnosis in fungicide research].

Cytochemical localization of acid and alkaline phosphatases, cytochrom c-oxidase, peroxidases and catalase was carried out on Phytophthora infestans (Mont.) de By. and Mucor mucedo (L.) Fres. First results are obtained about the influence of sublethal dosages of fungicidal compounds on the demonstration of these enzymes in the electron-microscope.

Acid Phosphatase↗
PubMed1982

[Effect of pentachloronitrobenzene (PCNB) on the ultrastructure of Mucor mucedo and Phytophthora cactorum].

The effect of PCNB in various concentrations on the ultrastructure of Mucor mucedo and phytophthora cactorum was analyzed after an incubation period of 2 hours. The most striking effect in both fungi was a diffuse lysis of the internal structure of the mitochondria which differs markedly from the lysis induced by etridiazol (terrazol). Moreover an enlargement of the perinuclear space and an increased formation of vacuoles was observed. In Mucor mucedo, but not in Phytophthora cactorum a pathological thickening of the cell wall was observed. Although after 2 hours incubation with PCNB Phytophthora gave similar ultrastructural reactions in the mitochondria as Mucor, in growth experiments on agar dishes this species was 5-10 times less sensitive to PCNB compared to Mucor.

Fungi↗
PubMed1982

Anomalous cell wall synthesis in Mucor mucedo (L.) Fres. induced by some fungicides and other compounds related to the problem of dimorphism.

An anomalous cell wall thickening in Mucor mucedo is induced already within 60-120 min by some fungicides (etridiazol, chloroneb, pentachloronitrobenzene, dicloran, drazoxolon, biphenyl) as well as with a N2-atmosphere or high concentrations of glucose, but not with 2,4-dinitrophenol, chlorinated phenols, dichlofluanid and antimycin A. This effect seems to be identical to the change from the mycelial (M-) to the yeast (Y-) form in dimorphic fungi, which can be achieved by culture conditions as well as by addition of chemicals. The cause seems to be a specific, complex change in the metabolic state. A scheme of regulation is presented which explains most of the experimental results described till now.

Antifungal Agents↗
PubMed1977

[Mode of action of terrazoleon Mucor mucedo].

It is assumed that the fungistatic effect of terrazol in Mucor mucedo is induced by a liberation of phospholipases within within the mitochondria and perhaps at other membranes. In isolated mitochondria a rapid formation of lysolecithin can be demonstrated at low concentrations of terrazol. This would explain the lytic symptoms in mitochondria visible by electron microscopy. Lipid peroxidation could not be demonstrated. The only antidots at present known for the growth inhibiting effect of terrazol and on its ultrastructural effects are impure saccharose, which seems to contain an unknown factor, and procain hydrochloride or to a lesser extent lidocain, which are well-known inhibitors of phospholipases. The pathological thickening of the cell wall induced by terazol seems to be an unspecific side effect reflecting a diminished phosphorylating activity of the mitochondria.

Antifungal Agents↗
PubMed1975

[Effect of terrazol on the ultrastructure of Mucor mucedo].

Terrazol, a systemic fungicide showing high specifity to oomycetes, inhibits the apical growth of hyphae and promotes at lower concentrations the thickening of the cell wall in Mucor mucedo. As revealed by ultrastructural analysis, particularly the fine structure of some membrane systems is influenced. In the first place the inner membrane of the mitochondria is attacked leading to a complete lysis of mitochondria. However, the sensitivities within a given population are different. The plasmalemma enlarges, forms several invaginations, partly redraws from the cell wall, but remains intact. Only after an extensive treatment with relatively high concentrations of terrazol the nuclear envelope shows vesicles between the double membranes. The mechanism of action of terrazol is discussed.

Antifungal Agents↗
PubMed1975

[Mechanism of action of terrazol].

Higher concentrations of terrazol inhibit the growth of a large number of fungi, but oomycetes are most sensitive. At medium concentrations (ED50 = 10 ppm) in Mucor mucedor several alterations of ultrastructure are recognizable even after short incubation periods. Significant observations are vacuolization of the mitochondrial cristae, invagination of the cytoplasmic membrane, and thickening of the cell wall. Later on, numerous vacuoles in the cytoplasm are visible. Primary effects on the cell membrane (destructive effect), on O2-consumption, on fermentation, or on nucleic acid synthesis could not be demonstrated. Lipid synthesis under the influence of terrazol showed characteristic changes. The synthesis of triglycerides and sterolesters was inhibited while the synthesis of free fatty acids and phospholipids was stimulated. Addition of lipids, vitamines, amino acids, or nucleic acids did not counteract the effect of terrazol. Further investigations are necessary to elucidate the primary mechanism of action.

Cell Membrane↗