We previously implicated 3-hydroxy oxylipins and ascospore structure in ascospore release from en... more We previously implicated 3-hydroxy oxylipins and ascospore structure in ascospore release from enclosed asci. Using confocal laser scanning microscopy on cells stained with fluorescein-coupled, 3-hydroxy oxylipin-specific antibodies, we found that oxylipins are specifically associated with ascospores and not the vegetative cells or ascus wall of Ascoidea corymbosa. Using gas chromatography--mass spectrometry the oxylipin 3-hydroxy 17:0 could be identified. Here, we visualize for the first time the forced release of oxylipin-coated, hat-shaped ascospores from terminally torn asci, probably through turgor pressure. We suggest that oxylipin-coated, razor-sharp, hat-shaped ascospore brims may play a role in rupturing the ascus to affect release.
The development of ascoma, ascus, and ascospore in Ophiostotna piceae was studied ultrastructural... more The development of ascoma, ascus, and ascospore in Ophiostotna piceae was studied ultrastructurally and compared with that of other Ascomycetes. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus. The ascospore wall, consisting of the primary and secondary walls, was deposited between these membranes. The elongate ascospores of 0 . piceae differed from other species having similarly shaped ascospores, with respect to the shape and arrangement of asci in the ascoma, the number of wall layers of the ascospore, and formation of the secondary wall. Asci in 0 . piceae are spindle shaped, arranged along the periphery of the ascomatal wall. The ascospores have three layered walls, whereas some other species in Ceratocystis s.1. also with elongated ascospores probably have only two wall layers.
VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis... more VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis proteae. Can. J . Bot. 71: 1212-1218. The development and ultrastructure of the ascoma, asci, and ascospores in Ceratocystiopsis proteae were studied and compared with that of other genera in Ceratocystis sensu lato. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus as is true in other species in Ceratocystis s.1. The ascospore wall developed between these membranes. In contrast with three wall layers observed in other species, only two wall layers were observed in C. proteae. Falcate sheaths previously reported in light-microscopic studies were not observed. The falcate appearance of ascospores may be ascribed to the adherence of a matrix to the outermost wall layer during ascospores release. Differences between this species and others in Ceratocystis s.1. illustrate the problems that can arise from the use of single morphological characteristics in the taxonomy of this group. It is accordingly suggested that the genus Ceratocystiopsis requires taxonomic revision.
ABSTRACT Enlargement of bacterial cells during bacteriophage replication has been observed in the... more ABSTRACT Enlargement of bacterial cells during bacteriophage replication has been observed in the past with T-even, Lambda and N4 bacteriophages by the use of transmission electron microscopy (TEM) and light microscopy techniques and hypotheses explaining the enlargement of bacteriophage-infected cells have been postulated in literature. In this study, enlarged Escherichia coli cells were observed using scanning electron microscopy (SEM) after 45 min of a P4-like bacteriophage infection. These bacteria were also studied using scanning auger microscopy (SAM) in combination with an Argon-ion gun by which the bacteria were etched. Neither SEM nor SAM have been used during the analysis of bacteriophage infected enlarged host cells, making this study unique. The use of SAM on bacteriophage-related investigations is also novel. Small phage-like particles were observed inside the etched enlarged and etched normal bacteriophage-exposed host cells. The presence of bacteriophage-like particles inside both types of cells confirmed that the enlarged cells, which were scarce in this sample, were not artifacts of some kind such as contamination by other microorganisms. The enlargement of bacteriophage infected host cells coincides with previous studies reported in literature, but never before with P4-like bacteriophages.
In this study the mitochondrion is regarded as a target to reveal compounds that may be used to c... more In this study the mitochondrion is regarded as a target to reveal compounds that may be used to combat various diseases. Consequently, the sexual structures of yeasts (with high mitochondrial activity) were identified as sensors to screen for various anti-mitochondrial drugs that may be toxic to humans and that are directed, amongst others, against fungal diseases and cancer. Strikingly, these sensors indicated that chloroquine is a potent pro-mitochondrial drug which stimulated yeast sexual reproduction. In addition, these sensors also showed that some Non-Steroidal Anti-Inflammatory drugs (NSAIDs), anti-malarial drugs, antifungal and anticancer drugs are anti-mitochondrial. These yeast sensor bio-assays may fast track studies aimed at discovering new drugs as well as their mechanisms and should now be further evaluated for selectivity towards anti-/ pro-mitochondrials, fertility drugs and contraceptives, using in vitro, in vivo, in silico and omics research.
The effect of marine polyunsaturated fatty acids on biofilm formation by the human pathogens Cand... more The effect of marine polyunsaturated fatty acids on biofilm formation by the human pathogens Candida albicans and Candida dubliniensis was investigated. It was found that stearidonic acid (18:4 n-3), eicosapentaenoic acid (20:5 n-3), docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) have an inhibitory effect on mitochondrial metabolism of both C. albicans and C. dubliniensis and that the production of biofilm biomass by C. dubliniensis was more susceptible to these fatty acids than C. albicans. Ultrastructural differences, which may be due to increased oxidative stress, were observed between treated and untreated cells of C. albicans and C. dubliniensis with formation of rough cell walls by both species and fibrillar structures in C. dubliniensis. These results indicate that marine polyunsaturated fatty acids may be useful in the treatment and/or prevention of biofilms formed by these pathogenic yeasts.
During Candida albicans infection, arachidonic acid (AA) is released from phospholipids of infect... more During Candida albicans infection, arachidonic acid (AA) is released from phospholipids of infected host cell membranes and used by C. albicans as the sole carbon source and for production of eicosanoids. AA can be incorporated into the phospholipids of yeasts, influencing the saturation level and fluidity of yeast cell membranes. It is suggested that the effectiveness of polyene (e.g. amphotericin B) and imidazole (e.g. clotrimazole) antifungals may depend upon the level of unsaturation and ergosterol in the membrane. Therefore, the aim of this study was to evaluate the effect of AA on the cell membrane and susceptibility of C. albicans and Candida dubliniensis biofilms towards amphotericin B and clotrimazole. Both yeasts were grown in the presence and absence of AA and the effect of amphotericin B and clotrimazole was examined by confocal laser scanning microscopy, determination of mitochondrial metabolism, unsaturation index of the phospholipid fractions and ergosterol content of the membranes. AA had no effect on the viability of the cells in the biofilm; however, there was an increase in ergosterol levels as well as antifungal susceptibility of biofilms grown in the presence of AA. AA influences phospholipid unsaturation and ergosterol content of both yeasts C. albicans and C. dublininensis, increasing susceptibility towards the antifungals. Pretreatment of biofilms with polyunsaturated fatty acids may result in the reduction in antifungal dose needed to inhibit biofilms.
We previously implicated 3-hydroxy oxylipins and ascospore structure in ascospore release from en... more We previously implicated 3-hydroxy oxylipins and ascospore structure in ascospore release from enclosed asci. Using confocal laser scanning microscopy on cells stained with fluorescein-coupled, 3-hydroxy oxylipin-specific antibodies, we found that oxylipins are specifically associated with ascospores and not the vegetative cells or ascus wall of Ascoidea corymbosa. Using gas chromatography--mass spectrometry the oxylipin 3-hydroxy 17:0 could be identified. Here, we visualize for the first time the forced release of oxylipin-coated, hat-shaped ascospores from terminally torn asci, probably through turgor pressure. We suggest that oxylipin-coated, razor-sharp, hat-shaped ascospore brims may play a role in rupturing the ascus to affect release.
The development of ascoma, ascus, and ascospore in Ophiostotna piceae was studied ultrastructural... more The development of ascoma, ascus, and ascospore in Ophiostotna piceae was studied ultrastructurally and compared with that of other Ascomycetes. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus. The ascospore wall, consisting of the primary and secondary walls, was deposited between these membranes. The elongate ascospores of 0 . piceae differed from other species having similarly shaped ascospores, with respect to the shape and arrangement of asci in the ascoma, the number of wall layers of the ascospore, and formation of the secondary wall. Asci in 0 . piceae are spindle shaped, arranged along the periphery of the ascomatal wall. The ascospores have three layered walls, whereas some other species in Ceratocystis s.1. also with elongated ascospores probably have only two wall layers.
VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis... more VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis proteae. Can. J . Bot. 71: 1212-1218. The development and ultrastructure of the ascoma, asci, and ascospores in Ceratocystiopsis proteae were studied and compared with that of other genera in Ceratocystis sensu lato. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus as is true in other species in Ceratocystis s.1. The ascospore wall developed between these membranes. In contrast with three wall layers observed in other species, only two wall layers were observed in C. proteae. Falcate sheaths previously reported in light-microscopic studies were not observed. The falcate appearance of ascospores may be ascribed to the adherence of a matrix to the outermost wall layer during ascospores release. Differences between this species and others in Ceratocystis s.1. illustrate the problems that can arise from the use of single morphological characteristics in the taxonomy of this group. It is accordingly suggested that the genus Ceratocystiopsis requires taxonomic revision.
ABSTRACT Enlargement of bacterial cells during bacteriophage replication has been observed in the... more ABSTRACT Enlargement of bacterial cells during bacteriophage replication has been observed in the past with T-even, Lambda and N4 bacteriophages by the use of transmission electron microscopy (TEM) and light microscopy techniques and hypotheses explaining the enlargement of bacteriophage-infected cells have been postulated in literature. In this study, enlarged Escherichia coli cells were observed using scanning electron microscopy (SEM) after 45 min of a P4-like bacteriophage infection. These bacteria were also studied using scanning auger microscopy (SAM) in combination with an Argon-ion gun by which the bacteria were etched. Neither SEM nor SAM have been used during the analysis of bacteriophage infected enlarged host cells, making this study unique. The use of SAM on bacteriophage-related investigations is also novel. Small phage-like particles were observed inside the etched enlarged and etched normal bacteriophage-exposed host cells. The presence of bacteriophage-like particles inside both types of cells confirmed that the enlarged cells, which were scarce in this sample, were not artifacts of some kind such as contamination by other microorganisms. The enlargement of bacteriophage infected host cells coincides with previous studies reported in literature, but never before with P4-like bacteriophages.
In this study the mitochondrion is regarded as a target to reveal compounds that may be used to c... more In this study the mitochondrion is regarded as a target to reveal compounds that may be used to combat various diseases. Consequently, the sexual structures of yeasts (with high mitochondrial activity) were identified as sensors to screen for various anti-mitochondrial drugs that may be toxic to humans and that are directed, amongst others, against fungal diseases and cancer. Strikingly, these sensors indicated that chloroquine is a potent pro-mitochondrial drug which stimulated yeast sexual reproduction. In addition, these sensors also showed that some Non-Steroidal Anti-Inflammatory drugs (NSAIDs), anti-malarial drugs, antifungal and anticancer drugs are anti-mitochondrial. These yeast sensor bio-assays may fast track studies aimed at discovering new drugs as well as their mechanisms and should now be further evaluated for selectivity towards anti-/ pro-mitochondrials, fertility drugs and contraceptives, using in vitro, in vivo, in silico and omics research.
The effect of marine polyunsaturated fatty acids on biofilm formation by the human pathogens Cand... more The effect of marine polyunsaturated fatty acids on biofilm formation by the human pathogens Candida albicans and Candida dubliniensis was investigated. It was found that stearidonic acid (18:4 n-3), eicosapentaenoic acid (20:5 n-3), docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) have an inhibitory effect on mitochondrial metabolism of both C. albicans and C. dubliniensis and that the production of biofilm biomass by C. dubliniensis was more susceptible to these fatty acids than C. albicans. Ultrastructural differences, which may be due to increased oxidative stress, were observed between treated and untreated cells of C. albicans and C. dubliniensis with formation of rough cell walls by both species and fibrillar structures in C. dubliniensis. These results indicate that marine polyunsaturated fatty acids may be useful in the treatment and/or prevention of biofilms formed by these pathogenic yeasts.
During Candida albicans infection, arachidonic acid (AA) is released from phospholipids of infect... more During Candida albicans infection, arachidonic acid (AA) is released from phospholipids of infected host cell membranes and used by C. albicans as the sole carbon source and for production of eicosanoids. AA can be incorporated into the phospholipids of yeasts, influencing the saturation level and fluidity of yeast cell membranes. It is suggested that the effectiveness of polyene (e.g. amphotericin B) and imidazole (e.g. clotrimazole) antifungals may depend upon the level of unsaturation and ergosterol in the membrane. Therefore, the aim of this study was to evaluate the effect of AA on the cell membrane and susceptibility of C. albicans and Candida dubliniensis biofilms towards amphotericin B and clotrimazole. Both yeasts were grown in the presence and absence of AA and the effect of amphotericin B and clotrimazole was examined by confocal laser scanning microscopy, determination of mitochondrial metabolism, unsaturation index of the phospholipid fractions and ergosterol content of the membranes. AA had no effect on the viability of the cells in the biofilm; however, there was an increase in ergosterol levels as well as antifungal susceptibility of biofilms grown in the presence of AA. AA influences phospholipid unsaturation and ergosterol content of both yeasts C. albicans and C. dublininensis, increasing susceptibility towards the antifungals. Pretreatment of biofilms with polyunsaturated fatty acids may result in the reduction in antifungal dose needed to inhibit biofilms.
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