Hans Salinas | Universidad de Concepción (original) (raw)
Papers by Hans Salinas
Fungal Genetics and Biology, 2002
Fungal Genetics and Biology, 2009
Chitosan has been reported to inhibit spore germination and mycelial growth in plant pathogens, b... more Chitosan has been reported to inhibit spore germination and mycelial growth in plant pathogens, but its mode of antifungal action is poorly understood. Following chitosan treatment, we characterized plasma membrane permeabilization, and cell death and lysis in the experimental model, Neurospora crassa. Rhodamine-labeled chitosan was used to show that chitosan is internalized by fungal cells. Cell viability stains and the calcium reporter, aequorin, were used to monitor plasma membrane permeabilization and cell death. Chitosan permeabilization of the fungal plasma membrane and its uptake into fungal cells was found to be energy dependent but not to involve endocytosis. Different cell types (conidia, germ tubes and vegetative hyphae) exhibited differential sensitivity to chitosan with ungerminated conidia being the most sensitive.
Archives of Clinical Neuropsychology, 2009
Soil Biology & Biochemistry, 2005
This study provides evidence that egg-parasitic nematophagous fungi, Pochonia chlamydosporia, Poc... more This study provides evidence that egg-parasitic nematophagous fungi, Pochonia chlamydosporia, Pochonia rubescens and Lecanicillium lecanii, can also reduce root colonisation and root damage by a fungal pathogen. Interactions of nematophagous fungi with the take-all fungus, Gaeumannomyces graminis var. tritici (Ggt), and their influence on severity of the root disease it causes were studied in laboratory and pot experiments. In Petri dish experiments the three nematophagous fungi reduced colonisation of barley roots by Ggt and also reduced necrotic symptoms. On the contrary, root colonisation by nematophagous fungi was unaffected by Ggt. In growth tube experiments, the three nematophagous fungi again reduced Ggt root colonisation and increased effective root length of barley seedlings. This was true for both simultaneous and sequential inoculation of nematophagous fungi versus Ggt. In the pot experiments the inoculum of the tested fungi in soil was applied in the same pot, as a mixture or in layers, or in coupled pots used for wheat grown with a split-root system. The nematophagous fungi P. chlamydosporia (isolate 4624) and L. lecanii (isolate 4629), mixed with Ggt or in split root systems with the pathogen, promoted growth of wheat (i.e. increased shoot weight), although no disease reduction was found. In split root systems, lower levels of peroxidase activity were found in seedlings inoculated with Ggt in combination with the nematophagous isolates 4624 and 4629 than when the take-all fungus was applied alone.Our results show that nematophagous fungi reduce root colonisation by Ggt, root damage and stress induced senescence in Ggt-inoculated plants.
Molecular Microbiology, 2010
The antifungal mode of action of chitosan has been studied for the last 30 years, but is still li... more The antifungal mode of action of chitosan has been studied for the last 30 years, but is still little understood. We have found that the plasma membrane forms a barrier to chitosan in chitosan-resistant but not chitosan-sensitive fungi. The plasma membranes of chitosan-sensitive fungi were shown to have more polyunsaturated fatty acids than chitosan-resistant fungi, suggesting that their permeabilization by chitosan may be dependent on membrane fluidity. A fatty acid desaturase mutant of Neurospora crassa with reduced plasma membrane fluidity exhibited increased resistance to chitosan. Steady-state fluorescence anisotropy measurements on artificial membranes showed that chitosan binds to negatively charged phospholipids that alter plasma membrane fluidity and induces membrane permeabilization, which was greatest in membranes containing more polyunsaturated lipids. Phylogenetic analysis of fungi with known sensitivity to chitosan suggests that chitosan resistance may have evolved in nematophagous and entomopathogenic fungi, which naturally encounter chitosan during infection of arthropods and nematodes. Our findings provide a method to predict the sensitivity of a fungus to chitosan based on its plasma membrane composition, and suggests a new strategy for antifungal therapy, which involves treatments that increase plasma membrane fluidity to make fungi more sensitive to fungicides such as chitosan.
Earth and Planetary Science Letters, 1994
... Nd and Rb-Sr isotopes M. Tistl a, KP Burgath b, A. H hndorf b, H. Kreuzer b, R. Mu oz `, R. S... more ... Nd and Rb-Sr isotopes M. Tistl a, KP Burgath b, A. H hndorf b, H. Kreuzer b, R. Mu oz `, R. Salinas a Niedstrasse ... compositions of the Viravira basalts and of geochemically comparable hornblende-plagioclase dykes in the zoned complex are close to the parental melt from which ...
Cardiovascular Research, 2010
Applied Microbiology and Biotechnology, 2010
Antifungal activity of chitosan on plant pathogenic fungi has been widely studied, but little is ... more Antifungal activity of chitosan on plant pathogenic fungi has been widely studied, but little is known about the effect of chitosan on fungal biocontrol agents. In this work, we characterize the increase of conidiation induced by chitosan in fungal pathogens of invertebrates (FPI). Chitosan increased conidiation of FPI, including Beauveria bassiana, widely used as mycoinsecticide, and did not affect conidia viability or pathogenicity. Increased conidiation induced by chitosan is shown to be concentration dependent and is not associated to growth inhibition as observed for the mycoparasitic fungus Trichoderma harzianum. Real-time reverse transcription polymerase chain reaction was used to study transcript levels of two genes involved in conidiation in B. bassiana, the regulatory G protein signaling gene Bbrgs1 and the hydrophobin gene hyd1, at different chitosan concentrations. Higher levels of Bbrgs1 and hyd1 transcripts were detected on chitosan-amended media. No correlation with chitosan concentration was observed for expression of Bbrgs1 unlike hyd1. Bbrgs1 deletion mutant ∆Bbrgs1 showed that chitosan-induced conidiation is independent of Bbrgs1, suggesting an alternative mechanism controlling conidiation in B. bassiana. Our data supports that sporulation increases by chitosan, with spores retaining their viability and pathogenicity, which makes chitosan a suitable compound to increase conidia production in fungi with applications in fungal biotechnology.
Mycological Research, 2002
Fungal Genetics and Biology, 2002
Fungal Genetics and Biology, 2009
Chitosan has been reported to inhibit spore germination and mycelial growth in plant pathogens, b... more Chitosan has been reported to inhibit spore germination and mycelial growth in plant pathogens, but its mode of antifungal action is poorly understood. Following chitosan treatment, we characterized plasma membrane permeabilization, and cell death and lysis in the experimental model, Neurospora crassa. Rhodamine-labeled chitosan was used to show that chitosan is internalized by fungal cells. Cell viability stains and the calcium reporter, aequorin, were used to monitor plasma membrane permeabilization and cell death. Chitosan permeabilization of the fungal plasma membrane and its uptake into fungal cells was found to be energy dependent but not to involve endocytosis. Different cell types (conidia, germ tubes and vegetative hyphae) exhibited differential sensitivity to chitosan with ungerminated conidia being the most sensitive.
Archives of Clinical Neuropsychology, 2009
Soil Biology & Biochemistry, 2005
This study provides evidence that egg-parasitic nematophagous fungi, Pochonia chlamydosporia, Poc... more This study provides evidence that egg-parasitic nematophagous fungi, Pochonia chlamydosporia, Pochonia rubescens and Lecanicillium lecanii, can also reduce root colonisation and root damage by a fungal pathogen. Interactions of nematophagous fungi with the take-all fungus, Gaeumannomyces graminis var. tritici (Ggt), and their influence on severity of the root disease it causes were studied in laboratory and pot experiments. In Petri dish experiments the three nematophagous fungi reduced colonisation of barley roots by Ggt and also reduced necrotic symptoms. On the contrary, root colonisation by nematophagous fungi was unaffected by Ggt. In growth tube experiments, the three nematophagous fungi again reduced Ggt root colonisation and increased effective root length of barley seedlings. This was true for both simultaneous and sequential inoculation of nematophagous fungi versus Ggt. In the pot experiments the inoculum of the tested fungi in soil was applied in the same pot, as a mixture or in layers, or in coupled pots used for wheat grown with a split-root system. The nematophagous fungi P. chlamydosporia (isolate 4624) and L. lecanii (isolate 4629), mixed with Ggt or in split root systems with the pathogen, promoted growth of wheat (i.e. increased shoot weight), although no disease reduction was found. In split root systems, lower levels of peroxidase activity were found in seedlings inoculated with Ggt in combination with the nematophagous isolates 4624 and 4629 than when the take-all fungus was applied alone.Our results show that nematophagous fungi reduce root colonisation by Ggt, root damage and stress induced senescence in Ggt-inoculated plants.
Molecular Microbiology, 2010
The antifungal mode of action of chitosan has been studied for the last 30 years, but is still li... more The antifungal mode of action of chitosan has been studied for the last 30 years, but is still little understood. We have found that the plasma membrane forms a barrier to chitosan in chitosan-resistant but not chitosan-sensitive fungi. The plasma membranes of chitosan-sensitive fungi were shown to have more polyunsaturated fatty acids than chitosan-resistant fungi, suggesting that their permeabilization by chitosan may be dependent on membrane fluidity. A fatty acid desaturase mutant of Neurospora crassa with reduced plasma membrane fluidity exhibited increased resistance to chitosan. Steady-state fluorescence anisotropy measurements on artificial membranes showed that chitosan binds to negatively charged phospholipids that alter plasma membrane fluidity and induces membrane permeabilization, which was greatest in membranes containing more polyunsaturated lipids. Phylogenetic analysis of fungi with known sensitivity to chitosan suggests that chitosan resistance may have evolved in nematophagous and entomopathogenic fungi, which naturally encounter chitosan during infection of arthropods and nematodes. Our findings provide a method to predict the sensitivity of a fungus to chitosan based on its plasma membrane composition, and suggests a new strategy for antifungal therapy, which involves treatments that increase plasma membrane fluidity to make fungi more sensitive to fungicides such as chitosan.
Earth and Planetary Science Letters, 1994
... Nd and Rb-Sr isotopes M. Tistl a, KP Burgath b, A. H hndorf b, H. Kreuzer b, R. Mu oz `, R. S... more ... Nd and Rb-Sr isotopes M. Tistl a, KP Burgath b, A. H hndorf b, H. Kreuzer b, R. Mu oz `, R. Salinas a Niedstrasse ... compositions of the Viravira basalts and of geochemically comparable hornblende-plagioclase dykes in the zoned complex are close to the parental melt from which ...
Cardiovascular Research, 2010
Applied Microbiology and Biotechnology, 2010
Antifungal activity of chitosan on plant pathogenic fungi has been widely studied, but little is ... more Antifungal activity of chitosan on plant pathogenic fungi has been widely studied, but little is known about the effect of chitosan on fungal biocontrol agents. In this work, we characterize the increase of conidiation induced by chitosan in fungal pathogens of invertebrates (FPI). Chitosan increased conidiation of FPI, including Beauveria bassiana, widely used as mycoinsecticide, and did not affect conidia viability or pathogenicity. Increased conidiation induced by chitosan is shown to be concentration dependent and is not associated to growth inhibition as observed for the mycoparasitic fungus Trichoderma harzianum. Real-time reverse transcription polymerase chain reaction was used to study transcript levels of two genes involved in conidiation in B. bassiana, the regulatory G protein signaling gene Bbrgs1 and the hydrophobin gene hyd1, at different chitosan concentrations. Higher levels of Bbrgs1 and hyd1 transcripts were detected on chitosan-amended media. No correlation with chitosan concentration was observed for expression of Bbrgs1 unlike hyd1. Bbrgs1 deletion mutant ∆Bbrgs1 showed that chitosan-induced conidiation is independent of Bbrgs1, suggesting an alternative mechanism controlling conidiation in B. bassiana. Our data supports that sporulation increases by chitosan, with spores retaining their viability and pathogenicity, which makes chitosan a suitable compound to increase conidia production in fungi with applications in fungal biotechnology.
Mycological Research, 2002