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The present work aims at evaluating the effect of cycloheximide at concentrations of between 0.5 and 5mgg–1 on N2O and NO3
– production in two slightly alkaline soils, sampled from deciduous woodland and arable cultivation. In the first experiment,
peptone was used as the “inducing substrate” for heterotrophic activity, and soil was incubated with cycloheximide (at different
concentrations) and/or acetylene (1mll–1) to block induced eukaryotic protein synthesis and ammonia monooxygenase activity, respectively. Peptone addition stimulated
N2O and NO3
– production significantly in woodland soil, whereas arable soil showed no significant N2O emissions and low NO3
– production. Low cycloheximide concentrations drastically reduced N2O emissions in woodland soil, suggesting a potential role of fungi in N2O emissions. However, acetylene was equally effective in blocking N2O emissions and part of NO3
– production, so that a possible role of ammonia monooxygenase in an organic-inorganic pathway of N nitrification in fungal
metabolism can be hypothesized. A second experiment was carried out on the woodland soil to check if low cycloheximide concentrations
had non-target biocidal effects on soil microorganisms. Attention was focused on the range of concentrations which had reduced
N2O emission in the woodland soil. The results suggested that at concentrations of cycloheximide between 0.5 and 2mgg–1 any biocidal effect on microbial biomass was negligible in the first 48h; therefore only selective inhibition of protein
synthesis could be expected. The whole nitrifier population seemed to be particularly sensitive to cycloheximide concentrations
higher than 2.5mgg–1.
Received: 4 July 1997 相似文献
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不同的抑制剂处理对水分胁迫诱导的冬小麦幼苗ABA累积的影响 总被引：2，自引：1，他引：2
研究了不同放线菌素Ｄ（ＡＭＤ）及环己亚胺（ＣＨＭ）处理方法对水分胁迫诱导的冬小麦幼苗内源脱落酸（ＡＢＡ）累积的影响。结果表明，在水分胁迫下，植物体根及叶片中ＡＢＡ随着水分胁迫时间的延长而增加，根ＡＢＡ增加早于叶片ＡＢＡ增加。在ＡＭＤ和ＣＨＭ与ＰＥＧ的３种处理后，ＡＭＤ和ＣＨＭ与ＰＥＧ同时处理根对于由胁迫诱导的根及叶片中ＡＢＡ增加具有明显的抑制作用。 相似文献
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The synergistic effect of cold treatment and protein synthesis inhibition was investigated in cut spikes of Consolida ajacis cv. Violet blue to determine the effective postharvest storage and transportation protocol, and to improve the postharvest performance. The 35 cm cut spikes were cool wet stored at 5 °C for 72 h before or after pulse treatment with protein synthesis inhibitor, cycloheximide, at 0.01 mM concentration. A set of unpulsed spikes wet stored at 5 °C represented control. The treatment effects were evaluated by placing the spikes in holding solutions containing distilled water (DW) or sucrose 0.2 M + 8-HQS 100 mg/l (SUC + HQS) at room temperature under laboratory conditions. The spikes pretreated with CHI before 72 h wet storage at 5 °C showed an enhancement of vase life besides maintaining higher fresh and dry mass of flowers, soluble protein content in sepals and sustained rate of blooming as compared to controls. The present study recommends that pulse treating the spikes of C. ajacis with 0.01 mM CHI before wet storage at 5 °C for 72 h, followed by transfer to holding solution containing SUC + HQS can be used as an effective postharvest storage treatment to bring out their transportation within 72 h without affecting their vase life. 相似文献
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Bacterial and fungal contributions to microbial respiration in three beechwood soils rich in C (two basalt soils and one limestone soil) were investigated by using streptomycin and cycloheximide to inhibit substrate-induced respiration after glucose (8000 g g-1), N, and P addition to soil samples. The inhibitors were added as solutions (2000, 8000, and 16000 g g-1) and the reduction in substrate-induced respiration after separate and combined inhibitor addition was measured in an automated electrolytic microrespirometer. Bacterial and fungal contributions to microbial respiration were calculated using the interval 6–10 h after inhibitor application. The microbial biomas was smaller in the two basalt soils (Oberhang and Mittelhang) than in the limestone soil (Unterhang). In the presence of both inhibitors, microbial respiration was inhibited by a maximum of 45, 45, and 25% in the two basalt soils and the limestone soil, respectively. Inhibition of microbial respiration was at a maximum at streptomycin and cycloheximide concentrations of 16000 g g-1. The inhibitor additivity ratio approached 1.0 even at high inhibitor concentrations, indicating high inhibitor selectivity. Calculated prokaryote: eukaryote ratios indicated lower bacterial contributions to the microbial biomass in the Mettelhang (0.74) and Unterhang (0.73) than in the Oberhang (0.88) soil. 相似文献
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H. Velvis 《Biology and Fertility of Soils》1997,25(4):354-360
A procedure for the measurement of the fungal and bacterial contribution to substrate-induced respiration was tested in three
arable soils. Glucose and different amounts of cycloheximide (eukaryote inhibitor) and streptomycin sulfate (prokaryote inhibitor)
were added to soil suspensions, and respiration (CO2 evolution) was measured. Streptomycin sulfate concentrations from 10 to 120 mg ml–1 soil solution caused a stable inhibition of respiration. Amounts of cycloheximide ranging from 5 to 35 mg ml–1 showed an increasing inhibition. In a test with separate and combined addition of the antibiotics at maximum inhibitory concentrations,
inhibition by streptomycin was completely overlapped by cycloheximide. This indicated non-target inhibition which may lead
to overestimation of fungal respiration. Experiments with sterilized soils inoculated with either fungi or bacteria confirmed
that streptomycin selectively inhibited bacteria. Cycloheximide, however, did not only inhibit fungal respiration already
at 2 mg ml–1, but also increasingly inhibited bacterial respiration at increasing concentrations. Only at less than 5 mg cycloheximide
ml–1 was the condition of selective fungal inhibition fulfilled. When 2 mg cycloheximide and 10 mg streptomycin sulfate ml–1 were applied, the sum of the separate inhibitions almost equalled the combined inhibition by the mix of both inhibitors in
field samples. This method yielded fungal:bacterial respiration ratios of 0.50 to 0.60, and confirmed the dominance of bacteria
in Dutch arable soils. The ratios obtained by the selective inhibitors were not correlated with, and were higher than, ratios
of fungal:bacterial biovolume (0.19 to 0.46) as determined by microscopy and image analysis. Similar measurements in a forest
soil (A-horizon) raised doubts on the reliability of the fungal inhibition by cycloheximide in this soil. It is concluded
that the separate:combined inhibition ratio should always be checked, and comparison with other approaches is recommended.
Received: 17 September 1996 相似文献
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蛋白和核酸合抑制剂对氮素诱导甜菜谷氨酰胺合成酶基因表达的影响 总被引：1，自引：1，他引：0
谷氨酰胺合成酶(GS)家族是甜菜等高等植物体内氨态氮同化酶, 也是氮利用与循环的核心构件。为了揭示在氮素诱导下, 放线菌素D(AMD)和放线菌酮(CHM)对甜菜GS基因调控表达的影响。采用半定量RT-PCR技术, 对甜菜的胞液型谷氨酰胺合成酶基因(GS1)和质体型谷氨酰胺合成酶基因(GS2)进行mRNA的表达检测, 同时进行GS活性的测定。结果表明, 甜菜幼苗经过低浓度AMD处理2~6 h, GS活性略有增加, 9 h后, 高和低浓度AMD处理下的GS活性都下降, 且随着浓度的增加下降幅度加大, 同时GS1mRNA和GS2mRNA的相对量随浓度的增加而下降。CHM处理甜菜幼苗9 h后, 随着浓度的增加和处理时间的延长, GS活性下降幅度增加, 但GS1mRNA和GS2mRNA的相对量在不同CHM浓度处理间变化不显著。 相似文献
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Soil microorganisms can use a wide range of N compounds but are thought to prefer NH4+. Nevertheless, 15N isotope dilution studies have shown that microbial immobilization of NO3− can be an important process in many soils, particularly relatively undisturbed soils. Our objective was to develop a method for measuring NO3− immobilization potential so that the relative contributions of bacteria and fungi could be determined. We modified and optimized a soil slurry method that included amendments of KNO3, glucose, and methionine sulfoximine (an inhibitor of N assimilation) in the presence of two protein synthesis inhibitors: chloramphenicol, which inhibits bacteria, or cycloheximide, which inhibits fungi. By adding 15N-labeled KNO3, we were able to measure gross rates of NO3− production (i.e., gross nitrification) and consumption (i.e., gross NO3− immobilization). We found that bacteria, not fungi, had the greatest potential for assimilating, or immobilizing, NO3− in these soils. This is consistent with their growth habit and distribution in the heterogeneous soil matrix. 相似文献