The Identification of Phenylalanine Ammonia-Lyase(PAL)Genes from Pinus yunnanensis and an Analysis of Enzyme Activity in vitro

Phenylalanine ammonia lyase(PAL)is the rate-limiting and pivotal enzyme of the general phenylpropanoid path-way,but few reports have been found on PAL genes in Pinus yunnanensis.In the present study,three PAL genes were cloned and identified from P.yunnanensis seedlings for thefirst time,namely,PyPAL-1,PyPAL-2,and PyPAL-3.Our results indicated that the open-reading frames of PyPAL genes were 2184,2157,and 2385 bp.Phylogenetic tree analysis revealed that PyPALs have high homology with other known PAL genes in other plants.In vitro enzymatic analysis showed that all three PyPAL recombinant proteins could catalyze the deamination of L-phenylalanine to form trans-cinnamic acid,but only PAL1 and PAL2 can catalyze the conversion of L-tyrosine toρ-coumaric acid.Three PyPAL genes were expressed in different tissues in 1-year-old P.yunnanensis,and such genes had different expression patterns.This study lays a foundation for further understanding of the biosynthesis of secondary metabolites in P.yunnanensis.

Deadwood affects the soil organic matter fractions and enzyme activity of soils in altitude gradient of temperate forests

The main objective of our study has been to determine the role of deadwood in the shaping of the amount of soil organic matter fractions in mountain forest soils.For this purpose,a climosequence approach comprising north(N)and south(S)exposure along the altitudinal gradient(600,800,1000 and 1200 m a.s.l.)was set up.By comparing the properties of decomposing deadwood and those of the soils located directly beneath the decaying wood we drew conclusions about the role of deadwood in the shaping of soil organic matter fractions and soil carbon storage in different climate conditions.The basic properties,enzymatic activity and fractions of soil organic matter(SOM)were determined in deadwood and affected directly by the components released from decaying wood.Heavily decomposed deadwood impacts soil organic matter stabilization more strongly than the less decayed deadwood and the light fraction of SOM is more sensitive to deadwood effects than the heavy fraction regardless of the location in the altitude gradient.Increase in SOM mineral-associated fraction C content is more pronounced in soils under the influence of deadwood located in lower locations of warmer exposure.Nutrients released from decaying wood stimulate the enzymatic activity of soils that are within the range of deadwood influence.

Effects of Combined Application of Biochar-based Organic Fertilizer and Reduced Nitrogen Fertilizer on Soil Enzyme Activity and Yield of Purple Cabbage(Brassica oleracea var.capita rubra)in Yuanmou County

[Objectives]In response to the issue of soil improvement in Yuanmou County,the effects of combined application of biochar-based organic fertilizer and reduced nitrogen fertilizer on soil nutrients,soil enzyme activity,and yield of purple cabbage(Brassica oleracea var.capita rubra)were investigated in the field base of Institute of Thermal Zone Ecological Agriculture,Yunnan Academy of Agricultural Sciences in Yuanmou County.[Methods]A total of 13 treatments were set up by applying biochar-based organic fertilizer at three levels of 15,30 and 45 t/hm^(2)(T_(1),T_(2),T_(3)),combined with top application of nitrogen fertilizer(urea)at four levels:375(N_1),300(N_(2)),225(N_(3))and 0 kg/hm^(2),with non-fertilizing treatment as control check(CK),in order to explore the optimal ratio for the combined application of biochar-based organic fertilizer with nitrogen fertilizer.[Results]The application of biochar-based organic fertilizer could significantly improve soil nutrients,enzyme activity,and purple cabbage yield.The improvement effect of combined application with nitrogen fertilizer was higher than that of single application of biochar-based organic fertilizer,and the improvement effect was enhanced with the application amount of biochar-based organic fertilizer increasing.The contents of organic matter and total nitrogen were the highest in treatment T_(3)N_(3),of which the values increased by 81.39%and 56.09%compared with the CK,respectively.The contents of soil hydrolyzable nitrogen,available phosphorus,and available potassium were all the highest under treatment T_(3)N_(2),with increases of 92.76%,171.01%and 235.50%,respectively.There was a significant positive correlation between the activity of soil catalase,urease,and sucrase and organic matter,total nitrogen,and available nutrients.The overall soil enzyme activity was relatively higher in treatment T_(3)N_(2).The yield of purple cabbage treated with biochar-based organic fertilizer combined with nitrogen fertilizer could reach 85750 kg/hm^(2),which was 94.78%higher than that treated with biochar-based organic fertilizer alone.Based on comprehensive analysis,the optimal combination ratio was 45 t/hm^(2)of biochar-based organic fertilizer and 300 kg/hm^(2)of urea(T_(3)N_(2)).[Conclusions]This study provides data support for the promotion of biochar-based organic fertilizers and reduced fertilizer in agricultural soil in the Dam area of Yuanmou County.

Effects of Carbon Nanomaterials on Soil Enzyme Activity of Turfgrass

[Objectives]This study was conducted to evaluate the effects of carbon nanomaterials on soil ecosystem and explore the ecological risks of environmental exposure of carbon nanomaterials. [Methods] The effects of carbon nanomaterials on soil enzyme activity was studied by adding graphene, graphene oxide and carbon nanotubes to turfgrass soil. [Results] Compared with the control(CK), the activity of soil protease, sucrase, alkaline phosphatase and catalase was not significantly affected by carbon nanomaterials. Under the treatment of carbon nanotubes, urease activity was significantly lower than that of graphene and graphene oxide, and dehydrogenase activity was significantly lower than that of the CK, graphene and graphene oxide. [Conclusions] This study provides a theoretical basis for the safe application of carbon nanomaterials.

Effects of Bamboo Charcoal-based Biochar on Soil Enzyme Activity and Microbial Community Structure

[Objectives]This study was conducted to reveal the effects of bamboo charcoal-based biochar(or bamboo charcoal for short)on soil enzyme activity and microbial community structure.[Methods]The field experiment was carried out at the Modern Agriculture Demonstration Base of Gaoping Village,Gaoping Town,Suichang County,Zhejiang Province.Bamboo charcoal was applied at four different levels:T_(0)(no bamboo charcoal),T_(1)(1125 kg/hm^(2)bamboo charcoal),T_(2)(2250 kg/hm^(2)bamboo charcoal)and T_(3)(3375 kg/hm^(2)bamboo charcoal).Soil physicochemical properties and enzyme activities in different treatments were measured.[Results]The soil fungal,bacterial and actinomycete populations increased significantly in the soils surrounding capsicum roots.The bacterial population,fungal population and fungus/bacterium ratio peaked in Treatment T_(2),up to 7.32×10^(6)cfu/g,2.65×10^(4)cfu/g and 0.36×10^(-2),respectively.The effect of bamboo charcoal in promotingβ-glucoside,catalase,acid phosphatase and sucrase activities was T_(2)>T_(3)>T_(1)>T_(0).With bamboo charcoal increasing,the bacterium population,fungus population,fungus/bacterium ratio,β-glucoside,catalase,acid phosphatase and sucrase activities all increased at first and then decreased.T_(2)treatment showed the best effects in improving soil physicochemical properties and microbial community structure.[Conclusions]Bamboo charcoal significantly improves soil enzyme activity and increases soil microbial population,and thus has important positive effects on the soil ecosystem.

Effects of dietary supplementation of probiotic,Clostridium butyricum,on growth performance,immune response,intestinal barrier function,and digestive enzyme activity in broiler chickens challenged with Escherichia coli K88

Background： Colibacillosis caused by enterotoxigenic Escherichia coil （E. coil} results in economic losses in the poultry industry. Antibiotics are usually used to control colibacillosis, however, E. coli has varying degrees of resistance to different antibiotics. Therefore the use of probiotics is becoming accepted as an alternative to antibiotics. In this study, we evaluated the effects of Clostfidium butyricum （C. butyficum） on growth performance, immune response, intestinal barrier function, and digestive enzyme activity in broiler chickens challenged with Eschefichia coli （E. coil） K88. Methods： The chickens were randomly divided into four treatment groups for 28 days. Negative control treatment （NC） consisted of birds fed a basal diet without E. coil K88 challenge and positive control treatment （PC） consisted of birds fed a basal diet and challenged with E. coil K88. C. buO/ricum probiotic treatment （CB） consisted of birds fed a diet containing 2 x 107 cfu C. buO/ricum/kg of diet and challenged with E. coil K88. Colistin sulfate antibiotic treatment （CS） consisted of birds fed a diet containing 20 mg colistin sulfate/kg of diet and challenged with E. coil K88. Results： The body weight （BW） and average day gain （ADG） in the broilers of CB group were higher （P 〈 0.05） than the broilers in the PC group overall except the ADG in the 14-21 d post-challenge. The birds in CB treatment had higher （P 〈 0.05） concentration of tumor necrosis factor-a （TNF-a） at 3 and 7 d post-challenge, and higher （P 〈 0.05） concentration of interleukin-4 （IL-4） at 14 d post-challenge than those in the PC treatment group. The concentration of serum endotoxin in CB birds was lower （P 〈 0.05） at 21 d post-challenge, and the concentrations of serum diamine oxidase in CB birds were lower （P 〈 0.05） at 14 and 21 d post-challenge than in PC birds. Birds in CB treatment group had higher （P 〈 0.05） jejunum villi height than those in PC, NC, or CS treatment at 7, 14, and 21 d post-challenge. In comparison to PC birds, the CB birds had lower （P 〈 0.05） jejunum crypt depth during the whole experiment. The birds in CB or CS treatment group had higher （P 〈 0.05） activities of amylase and protease at 3, 7, and 14 d post-challenge, and higher （P 〈 0.05） activity of lipase at 3, 7 d post-challenge than PC birds.

Effect of Host Plants on Development,Fecundity and Enzyme Activity of Spodoptera exigua (Hübner)(Lepidoptera:Noctuidae)

The beet armyworm,Spodoptera exigua （Lepidoptera：Noctuidae）,is an economically important pest of crops worldwide,attacking plants from over 20 families including trans-continental agricultural cotton,corn and citrus crops.In this study,performance and subsequent enzyme activity of beet armyworm reared on host plants from five families were investigated.Significant differences were found in development,fecundity and enzyme activity on different host plants.Survival rate was the highest （42.8%） on asparagus lettuce （Lactuca sativar var.asparagina） and the lowest （17.0%） on sweet pepper （Capsicum annuum）.Larval duration was the shortest on asparagus lettuce （12.0 d）,and was 43.4% longer on sweet peppers （21.2 d）.The activity of acetylcholine esterase （AChE） and carboxylesterase （CarE） in 3rd instar larvae,and soluble carbohydrate and crude protein contents in different host plants were determined.AChE activity was the highest in the larvae feeding on Chinese cabbage （Brassica rapa）,but declined by nearly 60% on maize （Zea mays） seedlings.The ratio of soluble carbohydrate content to crude protein content in host plants was found to have a positive effect on oviposition and a negative correlation with larval duration and life time （from larval to adult stages） of the insect.

Changes in the biochemical composition and enzyme activity during dormancy release of Cyclocarya paliurus seeds

Cyclocarya paliurus is only propagated from seeds which have pronounced dormancy. Overcoming seed dormancy is an important component of efficient and cost-effective seedling production of Cyclocarya paliurus. Changes in biochemical composition and enzyme activity were investigated during dormancy release. The activities of all the studied enzymes in the stratified seeds increased significantly, compared to those in the control samples. Of the enzymes examined, the activities of protease increased the most （413.8%）, followed by peroxidase （278.7%）, lipase （161.0%）, glucose-6-phosphate dehydrognase （149.1%） and amylase （60.6%） after 8 months of stratification. Crude fat and protein constituted the bulk of the storage reserves in mature seeds of C. pal# urus. Compared with the seeds before stratification, about 45% of the starch, 46% of the protein and 11% of the crude fat were depleted during dormancy release of C. paliurus seeds, while the soluble sugar content was enhanced by 101.5% in the germinating seeds. Correlation analysis showed, during dormancy release of C. paliurus seeds, a close positive relationship between POD and G6PDH activity as well as soluble sugar content and amylase activity, while there was a significant negative relationship between storage substances and their related enzyme activities.

Soil Organic Carbon, Black Carbon, and Enzyme Activity Under Long-Term Fertilization

The present study aims to understand the effects of long-term fertilization on soil organic carbon （SOC）, black carbon （BC）, enzyme activity, and the relationships among these parameters. Paddy field was continuously fertilized over 30 yr with nine different fertilizer treatments including N, P, K, NP, NK, NPK, 2NPK （two-fold NPK）, NPK＋manure （NPKM）, and CK （no fertilization）, N, 90 kg urea-N ha^-1 yr^-1; P, 45 kg triple superphosphate-P205 ha^-1 yr^-1; K, 75 kg potassium chloride-K20 ha^-1 yr^-1; and pig manure, 22 500 kg ha^-1 yr^-1. Soil samples were collected and determined for SOC, BC content, and enzyme activity. The results showed that the SOC in the NPKM treatment was significantly higher than those in the K, P, and CK treatments. The lowest SOC content was found in the CK treatment. SOC content was similar in the N, NP, NK, NPK, 2NPK, and NPKM treatments. There was no significant difference in BC content among different treatments. The BC-to-SOC ratios （BC/SOC） ranged from 0.50 to 0.63, suggesting that BC might originate from the same source. Regarding enzyme activity, NPK treatment had higher urease activity than NPKM treatment. The urease activity of NPKM treatment was significantly higher than that of 2NPK, NP, N, P, K, CK, and NPKM treatment which produced higher activities of acid phosphatase, catalase, and invertase than all other treatments. Our results indicated that long-term fertilization did not significantly affect BC content. Concurrent application of manure and mineral fertilizers increased SOC content and significantly enhanced soil enzyme activities. Correlation analysis showed that catalase activity was significantly associated with invertase activity, but SOC, BC, and enzyme activity levels were not significantly correlated with one another. No significant correlations were observed between BC and soil enzymes. It is unknown whether soil enzymes play a role in the decomposition of BC.

Irrigation water salinity and N fertilization:Effects on ammonia oxidizer abundance, enzyme activity and cotton growth in a drip irrigated cotton field

Use of saline water in irrigated agriculture has become an important means for alleviating water scarcity in arid and semi-arid regions. The objective of this field experiment was to evaluate the effects of irrigation water salinity and N fertilization on soil physicochemical and biological properties related to nitrification and denitrification. A 3×2 factorial design was used with three levels of irrigation water salinity（0.35, 4.61 and 8.04 d S m-1） and two N rates（0 and 360 kg N ha^（-1））. The results indicated that irrigation water salinity and N fertilization had significant effects on many soil physicochemical properties including water content, salinity, p H, NH_4-N concentration, and NO_3-N concentration. The abundance（i.e., gene copy number） of ammonia-oxidizing archaea（AOA） was greater than that of ammonia-oxidizing bacteria（AOB） in all treatments. Irrigation water salinity had no significant effect on the abundance of AOA or AOB in unfertilized plots. However, saline irrigation water（i.e., the 4.61 and 8.04 d S m-1 treatments） reduced AOA abundance, AOB abundance and potential nitrification rate in N fertilized plots. Regardless of N application rate, saline irrigation water increased urease activity but reduced the activities of both nitrate reductase and nitrite reductase. Irrigation with saline irrigation water significantly reduced cotton biomass, N uptake and yield. Nitrogen application exacerbated the negative effect of saline water. These results suggest that brackish water and saline water irrigation could significantly reduce both the abundance of ammonia oxidizers and potential nitrification rates. The AOA may play a more important role than AOB in nitrification in desert soil.

Protective enzyme activity and physiological properties of four mulberry varieties affected by drought stress in the Panxi Region of Sichuan Province, China

In order to identify the effects of drought stress on protective enzyme activity and physiological properties, four mulberry varieties, i.e.,＇Nanye- 1＇, ＇Yunsang- 1＇, ＇Xinyizhilai＇ and ＇Husang-32＇ in the Panxi Region of Sichuan Province, China, were selected. The activity of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） in four mulberry varieties was determined. Soluble protein, soluble sugar, proline, net photosynthetic rate and transpiration rate of mulberry leaves were analyzed. The results show that during the early stages of drought stress, protective enzyme activities in four mulberry varieties continually increased. However, prolonged and intensified drought stress decreased their activities. After re-watering, they gradually returned to normal levels. Under drought stress and after re-watering, ＇Nanye-l＇ and ＇Yunsang-l＇ clearly showed smaller changes in soluble protein content than the ＇Xinyizhilai＇ and ＇Husang-32＇ varieties, whereas changes in their soluble sugar content were clearly greater than these last two varieties. When water deficit was protracted and intensified, ＇Nanye-1＇ and ＇Yunsang-1＇ still showed higher net photosynthetic, transpiration rates and water-use efficiency than ＇Xinyizhilai＇ and ＇Husang-32＇.

Subacute Effect of Decabromodiphenyl Ethane on Hepatotoxicity and Hepatic Enzyme Activity in Rats

Information regarding decabromodiphenyl ethane （DBDPE） effects on hepatotoxicity and metabolism is limited. In the present study, Wistar rats were given oral DBDPE at different doses. DBDPE induced oxidative stress, elevated blood glucose levels, increased CYP2B2 mRNA, CYP2B1/2 protein, 7-pentoxyresorufin O-depentylase （PROD） activity, and induced CYP3A2 mRNA, CYP3A2 protein, and luciferin benzylether debenzylase （LBD） activity. UDPGT activity increased with its increasing exposure levels, suggesting that oral DBDPE exposure induces drug-metabolizing enzymes in rats via the CAR/PXR signaling pathway. The induction of CYPs and co-regulated enzymes of phase II biotransformation may affect the homeostasis of endogenous substrates, including thyroid hormones, which may, in turn, alter glucose metabolism.

Afforestation effects on soil microbial abundance, microbial biomass carbon and enzyme activity in dunes of Horqin Sandy Land, northeastern China

In order to investigate the effects of afforestation on soil microbial abundance, microbial biomass carbon and enzyme activity in sandy dunes, 20-year-old Pinus sylvestris var. mongolica Litv. （PSM） and Populus simonii Carri6re （PSC） mature forests were se- lected in Horqin Sandy Land, and mobile dunes was set as a control （CK）. Results show that PSM and PSC plantations can im- prove soil physicochemical properties and significantly increase microbiological activity in mobile dunes. Soil microbial abun- dance, microbial biomass carbon and enzyme activity show an order of PS〉PSM〉CK. Total soil microbial abundance in PSM and PSC was respectively 50.16 and 72.48 times more than that in CK, and the differences were significant among PSM, PSC and CK Soil microbial biomass carbon in PSM and PSC was respectively 23.67 and 33.34 times more than that in CK, and the difference was insignificant between PSM and PSC. Soil enzyme activity, including dehydrogenase （DEH）, peroxidase （PER）, protease （PRO）, urease （URE） and cellobiohydrolase （CEL） in PSM and PSC were respectively 19.00 and 27.54, 4.78 and 9.89, 4.05 and 8.67, 29.93 and 37.46, and 9.66 and 13.42 times of that in CK. R sylvestris and P. simonii can effectively improve soil physico- chemical and microbiological properties in sandy dunes and fix mobile dunes in Horqin Sandy Land. The Cmic：C ratio is an appli- cable indicator to estimate soil stability and soil water availability, and based on an overall consideration of plantation stability and sustainability, R sylvestris is better than R simonii in fixing mobile dunes in sandy land.

Impact of Microbial Inoculants on Microbial Quantity, Enzyme Activity and Available Nutrient Content in Paddy Soil

The experiment was conducted to study the impact of application of microbial inoculants, compared with no microbial fertilizer, on enzyme activity, microbial biomass and available nutrient contents in paddy soil in Heilongjiang Province. The application of soil phosphorus activator was able to increase the quantity of bacteria and fungi in soil, but its effect on actinomycetes in soil was not significant. The application of microbial inoculants increased the urease and sucrase activities in soil over the growing season, but only at the maturing stage soil acid phosphatase activity was enhanced with the applying soil phosphorus activator. The application of soil phosphorus activator increased alkali-hydrolyzable nitrogen and available phosphorus contents in soil, but did not increase available potassium content in soil. The optimal microbial inoculant application rate as applied as soil phosphorus activator was 7.5 kg hm-2.

Effects of Microbial Inoculums on Soil Enzyme Activity and Microbial Diversity in a Reclaimed Mining Area

Through a pot experiment, effects of various microbial inoculums on soil microbial diversity and enzyme activity in a typical reclaimed mining area in Shanxi Province were discussed based on quantitative analysis of PLFA, soil urease, phosphatase and sucrase activity. The results showed that the application of microbial inoculums increased microorganism quantity in rhizosphere of rape by 2.3% -66.4%, and quantities of bac- teria, gram-positive bacteria, gram-negative bacteria, fungi and actinomycetes in the treatments with microbial inoculums were significantly higher than the contrast （P 〈0.05）, while there was no obvious change in protist quantity. In comparison with the contrast, the application of various mi- crobial inoculums also improved soil urease, sucrase and phosphatase activity by 4.2% - 61.4%, 18.0% - 32.5% and 64.2% - 199.0% respec- tively. It indicated that the application of microbial inoculums can improve soil microbial diversity and enzyme activity, so it is an effective way to sl^eed UP ecoloQical restoration of soil.

Changes in Soil Enzyme Activity and Nutrient Content in Different Years of Continuous Cropping Tobacco Fields

In order to find out changes in the main fertility indicators of continuous cropping tobacco fields in Henan Province with years of continuous cropping,5 typical tobacco fields( Jia County,Shaoling District,Fangcheng County,Xiangcheng County,and Song County) were studied. Indicators in question included activity of main enzymes( sucrase,urease,catalase,and acid phosphatase),p H value,organic matters,total nitrogen,available phosphorus and available potassium. The results indicate that in most tobacco fields,the activity of sucrase and urease increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping; in some fields,it directly declined with increase in years of continuous cropping; the activity of catalase increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping,and it became stable after three years of continuous cropping;generally,the activity of acid phosphatase declined with increase in the years of continuous cropping within 3 years continuous cropping,later,it became stable. Except Fangcheng County,the soil p H value of other districts( counties) generally declined with increase in years of continuous cropping,and it was in the range of 5. 6-6. 8. With the increase in continuous cropping,the soil organic matters( SOM) in tobacco fields of Jia County and Song County declined,changes of SOM in tobacco fields of Fangcheng County and Xiangcheng County were not obvious,and SOM showed the trend of first decline then rise in Shaoling District. In most tobacco fields( Jia County,Xiangcheng County,and Song County),the total nitrogen showed a declining trend; in Shaoling District,it showed a trend of first decline then rise; in Fangcheng County,it showed a rising trend. The available phosphorus firstly slightly declined then rose in tobacco fields of Shaoling District and Song County; it showed a trend of first rise then decline in Jia County; there were no obvious changes in Fangcheng County and Xiangcheng County. Changes in the available potassium were different in tobacco fields. In sum,there are certain rules for changes in soil enzyme activity and nutrient content in tobacco fields in Henan Province,but changes are not completely the same. It is concluded that the site conditions and farming activities exert a certain influence on soil enzyme activity,p H value,organic matters,and nitrogen,phosphorus and potassium content. Therefore,to solve obstacles in continuous cropping of tobacco fields,different regions should take different measures.

In vitro and comparative study on the extracellular enzyme activity of molds isolated from keratomycosis and soil

AIMTo isolate and identify the molds involved in mycotic keratitis; to isolate corresponding species from soil samples; to compare the extracellular enzyme activity indices of the molds isolated from keratitis cases and the corresponding soil isolates.

Seasonal Variations of Soil Enzyme Activity on Rocky Hillsides Continuously Planted with Vitis heyneana Roem.et Schult

[Objectives]This study was conducted to investigate the effects of Vitis heyneana cultivation on rocky hillsides on the variation of soil fertility,so as to provide theoretical support for economic development and the control of rocky desertification in the Dashi mountainous area.[Methods]Taking V.heyneana planting base in Luocheng County,Hechi City,Guangxi Province as the research object,the methods of field investigation,regular sampling and experimental analysis were used to analyze seasonal variations of soil urease,sucrase and soil alkaline phosphatase activity of 15 different sample plots surveyed,and their correlation with soil physical and chemical properties was analyzed.[Results]①In general,sucrase,urease and alkaline phosphatase were lower in summer and autumn,and higher in spring and winter,and the performance of the activity of the three enzymes was inconsistent.Among them,the activity of sucrase was in order of spring>autumn>summer>winter,and the activity of urease and alkaline phosphatase showed an order of winter>spring>summer>autumn.②The seasonal variations of soil fertility in different sample plots were affected by various factors such as human disturbance,climate change,vegetation coverage,topography and landforms,cultivation and management measures,and although the change laws in different sample plots were different,the seasonal differences in soil fertility in the same place were extremely significant.③If the influence of artificial fertilization factors is excluded,the planting of V.heyneana on rocky hillsides will cause a significant decrease in soil enzyme activity,that is,a significant decrease in soil fertility.[Conclusions]Related issues such as the effects of planting V.heyneana on the variation of soil fertility in rocky hillsides should arouse necessary attention of management departments and producers.

Effects of Grain Protein Content Selection on Protein Content and Key Enzyme Activity Involved in Nitrogen Metabolism in Progenies Derived from a Rice Cross

Two japonica rice parents （Tong 769 and Xixuan 1） and their progenies, significantly different in protein content of grains, were investigated to reveal the activities of proteinase in leaves and glutamine synthetase in grains, as well as the dynamic changes of soluble protein content in grains during rice grain filling. The results showed that the parents were very similar in protein content, however, advanced lines with different protein contents in grains and varied activities of proteinase and glutamine synthetase were acquired by consecutively directional selection of the grain protein content in their progenies. Moreover, the enzyme activity and the protein content in grains exceeded their parents during grain filling. The protein content in grains was positively related with the proteinase activity, and the soluble protein content was negatively related with the glutamine synthetase activity in grains to some extent.

Mutagenicity and Induction of Drug-metabolizing Enzyme Activity by LPG Combustion Particulates in Rats

Methylene chloride extracts of particulates from liquefied petroleum gas (LPG) combustion appliance were studied by using Ames test, micronucleus test and inducibility of pulmonary and hepatic aryl hydrocarbon hydroxylase (AHH) and glutathione S-transferase (GST) in rats. The extracts showed mutagenicity for Salmonella typhimurium strain TA98 and its derivatives TA98NR and TA98/1,8-DNP6 with or without S9 mix. The revertants in strains TA98NR and TA98/1,8-DNP6 were less than 40% and 50% of that in strain TA98 without S9 mix, respectively. Positive results were obtained in mouse bone marrow micronucleus assay. Intratracheal instillation of the extracts led to increase in pulmonary (but not hepatic) AHH and GST activities in rats. It was seen that AHH was more sensitive than GST to induction by the extracts