Mycoparasitic species of Trichoderma are commercially applied as biological control agents against various fungal pathogens. The mycoparasitic interaction is host specific and includes recognition, attack and subseque...Mycoparasitic species of Trichoderma are commercially applied as biological control agents against various fungal pathogens. The mycoparasitic interaction is host specific and includes recognition, attack and subsequent penetration and killing of the host. Investigations on the underlying events revealed that Trichoderma responds to multiple signals from the host (e.g. lectins or other ligands such as low molecular weight components released from the host’s cell wall) and host attack is accompanied by morphological changes and the secretion of hydrolytic enzymes and antibiotics. Degradation of the cell wall of the host fungus is-besides glucanases and proteases-mainly achieved by chitinases. In vivo studies showed that the ech42 gene (encoding endochitinase 42) is expressed before physical contact of Trichoderma with its host, probably representing one of the earliest events in mycoparasitism, whereas Nag1 (N-acetylglucosaminidase) plays a key role in the general induction of the chitinolytic enzyme system of T. atroviride . Investigations on the responsible signal transduction pathways of T. atroviride led to the isolation of several genes encoding key components of the cAMP and MAP kinase signaling pathways, as alpha and β subunits of heterotrimeric G proteins, the regulatory subunit of cAMP-dependent protein kinase, adenylate cyclase, and three MAP kinases. Analysis of knockout mutants, generated by Agrobacterium-mediated transformation, revealed that at least two alpha-subunits of heterotrimeric G proteins are participating in mycoparasitism-related signal transduction. The Tga1 G alpha subunit was shown to be involved in mycoparasitism-related processes such as chitinase expression and overproduction of toxic secondary metabolites, whereas Tga3 was found to be completely avirulent showing defects in chitinase formation and host recognition.展开更多
Based on the kairomone from the accessory gland of female Bombyx mori elicting the parasitoid, Telenomus theophilae, to parasitize artifical beads. A cDNA expression library of enrich kairomone gene was constr...Based on the kairomone from the accessory gland of female Bombyx mori elicting the parasitoid, Telenomus theophilae, to parasitize artifical beads. A cDNA expression library of enrich kairomone gene was constructed using mRNA rich secretory portion of the accessory glands of B. mori at the 9 day old of pupa. The titer of the unamplified library was 3.29×10 4 pfu/μL with a recombinant rate of 90.05%, and titer of amplified library was 1.56×10 7 pfu/μL. The inserted cDNA fragments of the library ranged from 0.5 to 8.0 kb and concentrated around the 2.5 kb, 1.1kb, and 0.75kb regions. All of the data suggest that the library has appropriate titer and high frequency kairomone gene fragments by using special developing stage and tissue of B. mori to extract mRNA. Directional cloning and λZiplox expression were help to clone the kairomone gene with immunoscreening.展开更多
A sensitive label-free fluorescent aptasensing strategy for the detection of adenosine triphosphate（ATP）has been developed with a metallocyclodextrin, tris（bipyridine）ruthenium（Ⅱ） complex containing six cyclode...A sensitive label-free fluorescent aptasensing strategy for the detection of adenosine triphosphate（ATP）has been developed with a metallocyclodextrin, tris（bipyridine）ruthenium（Ⅱ） complex containing six cyclodextrin units（6CD-Ru）, which exhibited much stronger emission signal compared to the parent compound Ru（bpy）_3Cl_2. Furthermore, the emission spectrum showed that the ATP-aptamer（ss DNA）could increase the fluorescence intensity of 6CD-Ru dramatically, attributed to the interaction between aptamer and cyclodextrin, which could provide protection to the ruthenium core from the quenching of emission by oxygen in the solution. With the addition of ATP, the interaction between aptamer and cyclodextrins on 6CD-Ru was diminished, since the ATP/aptamer complex had the priority to be formed,leading to the corresponding reduction of fluorescence intensity, which could be utilized to detect ATP quantitatively. A linear relationship was displayed between the fluorescence and the logarithm of ATP concentrations in the range from 1 nmol/L to 1μmmol/L with the detection limit of 0.5 nmol/L（S/N = 3）.The proposed fluorescent aptasensing strategy exhibited high sensitivity and specificity, without any labeling or amplification procedures, and it could also be applied for the detection of many other aptamer-specific targets.展开更多
文摘Mycoparasitic species of Trichoderma are commercially applied as biological control agents against various fungal pathogens. The mycoparasitic interaction is host specific and includes recognition, attack and subsequent penetration and killing of the host. Investigations on the underlying events revealed that Trichoderma responds to multiple signals from the host (e.g. lectins or other ligands such as low molecular weight components released from the host’s cell wall) and host attack is accompanied by morphological changes and the secretion of hydrolytic enzymes and antibiotics. Degradation of the cell wall of the host fungus is-besides glucanases and proteases-mainly achieved by chitinases. In vivo studies showed that the ech42 gene (encoding endochitinase 42) is expressed before physical contact of Trichoderma with its host, probably representing one of the earliest events in mycoparasitism, whereas Nag1 (N-acetylglucosaminidase) plays a key role in the general induction of the chitinolytic enzyme system of T. atroviride . Investigations on the responsible signal transduction pathways of T. atroviride led to the isolation of several genes encoding key components of the cAMP and MAP kinase signaling pathways, as alpha and β subunits of heterotrimeric G proteins, the regulatory subunit of cAMP-dependent protein kinase, adenylate cyclase, and three MAP kinases. Analysis of knockout mutants, generated by Agrobacterium-mediated transformation, revealed that at least two alpha-subunits of heterotrimeric G proteins are participating in mycoparasitism-related signal transduction. The Tga1 G alpha subunit was shown to be involved in mycoparasitism-related processes such as chitinase expression and overproduction of toxic secondary metabolites, whereas Tga3 was found to be completely avirulent showing defects in chitinase formation and host recognition.
文摘Based on the kairomone from the accessory gland of female Bombyx mori elicting the parasitoid, Telenomus theophilae, to parasitize artifical beads. A cDNA expression library of enrich kairomone gene was constructed using mRNA rich secretory portion of the accessory glands of B. mori at the 9 day old of pupa. The titer of the unamplified library was 3.29×10 4 pfu/μL with a recombinant rate of 90.05%, and titer of amplified library was 1.56×10 7 pfu/μL. The inserted cDNA fragments of the library ranged from 0.5 to 8.0 kb and concentrated around the 2.5 kb, 1.1kb, and 0.75kb regions. All of the data suggest that the library has appropriate titer and high frequency kairomone gene fragments by using special developing stage and tissue of B. mori to extract mRNA. Directional cloning and λZiplox expression were help to clone the kairomone gene with immunoscreening.
基金financially supported by the National Natural Science Foundation of China(Nos.21275054,21405049,31300819)
文摘A sensitive label-free fluorescent aptasensing strategy for the detection of adenosine triphosphate（ATP）has been developed with a metallocyclodextrin, tris（bipyridine）ruthenium（Ⅱ） complex containing six cyclodextrin units（6CD-Ru）, which exhibited much stronger emission signal compared to the parent compound Ru（bpy）_3Cl_2. Furthermore, the emission spectrum showed that the ATP-aptamer（ss DNA）could increase the fluorescence intensity of 6CD-Ru dramatically, attributed to the interaction between aptamer and cyclodextrin, which could provide protection to the ruthenium core from the quenching of emission by oxygen in the solution. With the addition of ATP, the interaction between aptamer and cyclodextrins on 6CD-Ru was diminished, since the ATP/aptamer complex had the priority to be formed,leading to the corresponding reduction of fluorescence intensity, which could be utilized to detect ATP quantitatively. A linear relationship was displayed between the fluorescence and the logarithm of ATP concentrations in the range from 1 nmol/L to 1μmmol/L with the detection limit of 0.5 nmol/L（S/N = 3）.The proposed fluorescent aptasensing strategy exhibited high sensitivity and specificity, without any labeling or amplification procedures, and it could also be applied for the detection of many other aptamer-specific targets.
