Functional response is a key index in determining the population fluctuation in predation. However, the lack of operable research system limits the studies on functional response of fungal predators. Hirsutella rhossi...Functional response is a key index in determining the population fluctuation in predation. However, the lack of operable research system limits the studies on functional response of fungal predators. Hirsutella rhossiliensis is a dominant parasite of the soybean cyst nematode, Heterodera glycines. In a soil microcosm bioassay, we determined fungal biomass at different days within 21 days after inoculation, and parasitism rate of H. glycines by the fungus was determined. The functional response of H. rhossiliensis to H. glycines was established and found to be Holling＇s type Ill, which was influenced by mycelial densities. Meanwhile, we conducted anti-fungal analysis of metabolic fractions extracted from H. rhossiliensis to explain the potential mechanism of the intraspecific competition illustrated by functional response. The result of anti-fungal experiments indicated that the fungal predators had more complicated interaction at population level than expected, which might be regulated by self-inhibition metabolite（s）. This study was the first functional response study of fungal predators in microcosm. With the in- creasing recognition of emerging fungal threats to animal, plant, and ecosystem health, the methodologies and hypotheses proposed in this study might inspire further research in fungal ecology.展开更多
In order to investigate the role of DNA bending on the regulation of σ54-dependent promot- ers, we introduced the CopG binding site between the enhancer-like element and the core promoter of glnAp2, nifLp and glnHp2,...In order to investigate the role of DNA bending on the regulation of σ54-dependent promot- ers, we introduced the CopG binding site between the enhancer-like element and the core promoter of glnAp2, nifLp and glnHp2, without changing the dis- tance in between. The expression activities of these homologous promoters were either activated or re- pressed by the CopG-induced DNA bending in E. coli. In this case, similar regulatory pattern (either acti- vated or repressed) could be observed, when the bending centers from CopG are in integral DNA he- lixes interval, while opposite regulatory pattern could be observed, when the bending centers from CopG are in integral plus a half DNA helixes interval. These results suggested that CopG-induced DNA bending can exert regulatory effects on the transcription of σ54-dependent promoters probably by altering the relative DNA helix phase of 54 RNA polymerase and NtrC.展开更多
基金supported by the National Key Basic Research Program of China(2013CB127506)the National Natural Science Foundation of China(30800732)the National Public Benefit Research Foundation of China(200903040)
文摘Functional response is a key index in determining the population fluctuation in predation. However, the lack of operable research system limits the studies on functional response of fungal predators. Hirsutella rhossiliensis is a dominant parasite of the soybean cyst nematode, Heterodera glycines. In a soil microcosm bioassay, we determined fungal biomass at different days within 21 days after inoculation, and parasitism rate of H. glycines by the fungus was determined. The functional response of H. rhossiliensis to H. glycines was established and found to be Holling＇s type Ill, which was influenced by mycelial densities. Meanwhile, we conducted anti-fungal analysis of metabolic fractions extracted from H. rhossiliensis to explain the potential mechanism of the intraspecific competition illustrated by functional response. The result of anti-fungal experiments indicated that the fungal predators had more complicated interaction at population level than expected, which might be regulated by self-inhibition metabolite（s）. This study was the first functional response study of fungal predators in microcosm. With the in- creasing recognition of emerging fungal threats to animal, plant, and ecosystem health, the methodologies and hypotheses proposed in this study might inspire further research in fungal ecology.
基金supported in part by the National Basic Research Program of China(Grant No.2001CB 108903)National Natural Science Foundation of China(Grants No.39925017&30200047).
文摘In order to investigate the role of DNA bending on the regulation of σ54-dependent promot- ers, we introduced the CopG binding site between the enhancer-like element and the core promoter of glnAp2, nifLp and glnHp2, without changing the dis- tance in between. The expression activities of these homologous promoters were either activated or re- pressed by the CopG-induced DNA bending in E. coli. In this case, similar regulatory pattern (either acti- vated or repressed) could be observed, when the bending centers from CopG are in integral DNA he- lixes interval, while opposite regulatory pattern could be observed, when the bending centers from CopG are in integral plus a half DNA helixes interval. These results suggested that CopG-induced DNA bending can exert regulatory effects on the transcription of σ54-dependent promoters probably by altering the relative DNA helix phase of 54 RNA polymerase and NtrC.
