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  • 1  Carbon storage and distribution characteristics of Camellia gauchowensis plantation
    GUO Mengqing YANG Ying XU Ye XI Ruchun
    2020, 41(3):86-92. DOI: 10.7671/j.issn.1001-411X.201907018
    [Abstract](31815) [HTML](10558) [PDF 780.81 K](37656)
    Abstract:
    Objective To investigate carbon storage and distribution characteristics of Camellia gauchowensis plantation, estimate and evaluate the effect of carbon sequestration.Method Based on the distribution characteristics of basic diameter class in the sample plot, 2 to 3 sample trees were selected in each diameter class. The biomass and carbon content of various organs (leaves, trunks, branches, roots, fruits and flower buds) were measured and their biomass models were established. According to “S” shape in standard plot, eight sampling points were randomly selected to collect soil samples from 0-20, 20-40, 40-60 and 60-100 cm along the soil profile. The bulk density and carbon content of soil samples were determined and the carbon storage was calculated.Result The order of biomass allocation ratio of the organs of middle-aged C. gauchowensis plantation was trunks > roots > leaves > branches > fruits > flower buds. All the biomass of various organs increased with the basal diameter. The total biomass of test stand was 26.902 t·hm-2. The average carbon content of the tree was 483.45 g·kg-1. The carbon contents were different from various organs in the same diameter class, with fruits being the highest. In the soil layers of 100 cm depth in C. gauchowensis forest land, the soil carbon content decreased with the increase of soil depth, with 0-20 cm soil layer being the highest (26.550 g·kg-1). The total carbon storage of C. gauchowensis plantation was 144.538 t·hm-2, which was 12.857 t·hm-2 (accounting for 8.90%) and 131.681 t·hm-2 (accounting for 91.10%) for plant and soil, respectively. According to the authorized data of China biodiversity national condition report, the carbon price is 260.90 CNY per ton, so the economic benefit of the carbon of C. gauchowensi plantation is about 38 000 CNY per hectare.Conclusion The carbon storage of C. gauchowensis plantation is higher than that of the average level of non-timber forests in Guangdong, the forest soil carbon storage is higher than the average level in Guangdong, and the total carbon storage of stand is higher than that of forest ecosystem in the Pearl River Delta. C. gauchowensi not only has a good production benefit, but also has a very broad prospect of carbon sequestration.
    2  Gene knockout of Tiki1 gene in rabbit by TALEN system
    WU Caixia LIU Zhaoming YAN Quanmei ZHANG Quanjun OUYANG Zhen ZHAO Yu FAN Nana LAI Liangxue
    2020, 41(3):9-14. DOI: 10.7671/j.issn.1001-411X.201908011
    [Abstract](31656) [HTML](10603) [PDF 827.23 K](19504)
    Abstract:
    Objective To obtain a rabbit model of Tiki1 gene knockout by the transcription activator-like effector nuclease (TALEN) system, and provide a rabbit model for investigating the mechanism of Tiki1 gene on early development of animals.Method Using TALEN system, the target vector of rabbit Tiki1 gene was constructed and then 10 or 50 ng/μL Tiki1-TALEN mRNA was injected into the cytoplasm of fertilized eggs at pronuclear stage. Embryos developed to blastocyst stage were collected. The blastocyst rate and gene modification efficiency were investigated. To further obtain Tiki1 knockout rabbits, 50 ng/μL Tiki1-TALEN mRNA was subsequently injected into the cytoplasm of 17 prokaryotic fertilized eggs of rabbit,and then the fertilized eggs were transplanted into two recipient rabbits.Result The blastocyst rate of the treatment group injected with 50 ng/μL Tiki1-TALEN mRNA(64%) was almost the same as that of the group injected with 10 ng/μL Tiki1-TALEN mRNA(57%), while the blastocyst gene modification efficiency of the group injected with 50 ng/μL Tiki1-TALEN mRNA(100%) was significantly higher than that of the group injected with 10 ng/μL Tiki1-TALEN mRNA (14.3%). The sequencing results showed that mutations of Tiki1 gene ranged from the deletion of 1 bp to 28 bp. A total of three rabbits were born after embryo transfer, and two of them were detected with genetic mutations.Conclusion The TALEN technology system established in this study could effectively knock out Tiki1 gene in rabbit.
    3  Biodiversity comparison of endophytic fungi from wild and artificially cultivated Dendrobium officinale and screening of fungal strains with anti-anthracnose activities
    LIU Yanming HUANG Yali LI Ting FENG Meiru SHI Wenguang DENG Zujun
    2020, 41(3):47-55. DOI: 10.7671/j.issn.1001-411X.202001034
    [Abstract](31625) [HTML](428) [PDF 942.80 K](2387)
    Abstract:
    Objective To systematically analyze and compare the diversity of endophytic fungi from wild and cultivated Dendrobium officinale, and screen fungal strains with anti-anthracnose activities.Method Endophytic fungi of D. officinale were isolated by tissue block separation method, and they were identified by slide culture method and molecular identification method based on internal transcribed spacer regions of ribosomal DNA (rDNA-ITS). Screening for endophytic fungi against anthracnose was carried out by plate method.Result Totally 236 endophytic fungal strains were isolated from D. officinale(132 from wild plants and 104 from artificially cultivated plants). Total colonization rate (50.46%),total isolation rate (61.11%) and diversity index (2.95%) of endophytic fungi in wild plants were significantly higher than those in artificially cultivated plants (the corresponding values were 39.35%, 48.14% and 2.49, respectively). We screened out 34 strains of endophytic fungi with inhibitory activities against Colletotrichum gloeosporioides. Amomg them, the strains Ceriporia sp. F102, Rigidoporus sp. F27, Termitomyces sp. F103 and Peniophora sp. F122 showed higher inhibitory effects, and their inhibition rates were 93.06%, 88.20%, 87.48% and 84.57%, respectively.Conclusion The biodiversity and community structure of endophytic fungi of wild D. officinale and artificially cultivated D. officinal had significant differences, and abundant strains with anti-anthracnose activities were obtained from them, which lays the foundation for improving the quality of medicinal materials of artificially cultivated D. officinal and the biocontrol of D. officinale anthracnose.
    4  Vegetation coverage extraction model of winter wheat based on pixel dichotomy
    MENG Dunchao ZHAO Jing LAN Yubin LU Liqun YANG Huanbo LI Zhiming YAN Chunyu
    2020, 41(3):126-132. DOI: 10.7671/j.issn.1001-411X.201909055
    [Abstract](19435) [HTML](10896) [PDF 1.51 M](38383)
    Abstract:
    Objective To quickly and accurately extract vegetation coverage information of winter wheat in turning green period.Method The field visible light images of winter wheat were obtained by UAV, and four common visible light vegetation indices were extracted. According to the principle of pixel dichotomy model, the vegetation coverage extraction models were established based on visible-band difference vegetation index(VDVI), excess green (EXG), normalized green-blue difference index (NGBDI) and normalized green-red difference index (NGRDI) respectively. The accuracies of four models were verified using the support vector machine (SVM) supervised classification results as the truth values.Result The VDVI vegetation coverage extraction model had the highest accuracy and the best extraction effect to extract vegetation coverage among the four models. Compared with the supervised classification results, the extraction errors (EF) of four vegetation coverage extraction models were 3.36%, 15.68%, 8.74% and 15.46% respectively, the values of R2 were 0.946 1, 0.934 4, 0.695 3 and 0.746 0 respectively, and the values of root mean square error (RMSE) were 0.021 9, 0.059 5, 0.042 0 and 0.055 9 respectively.Conclusion The vegetation coverage extraction model based on visible vegetation index and pixel dichotomy has realized accurate and rapid extraction of vegetation coverage of winter wheat in turning green period,which provides a new way to extract vegetation coverage and a reference for UAV remote sensing monitoring vegetation coverage information.
    5  Development and test of an air-suction type precision direct seeding machine for pepper
    ZENG Shan YAO Lamei LI Ning YANG Yukun HUANG Dengpan FANG Longyu MO Zewen
    2020, 41(3):102-109. DOI: 10.7671/j.issn.1001-411X.201906012
    [Abstract](19242) [HTML](9675) [PDF 1.48 M](38041)
    Abstract:
    Objective To solve the problems of high cost, high labor intensity and low production efficiency in pepper planting, seeding and transplanting, an air-suction type precision direct seeding machine for pepper was developed considering pepper planting pattern and agronomic requirements in south area.Method The machine consists of a main frame, a copying mechanism, a fan, a transmission system, a derailleur, an air-suction seed device, a ditching device and a pressing device, which can complete the ditching, seeding, soil covering and pressing operations at one time. The seed metering machine uses the principle of taking seeds by negative pressure and discharging seeds by breaking pressure. According to the seeding requirements and physical characteristics of pepper seeds, the size of seeding plate, the number and size of seeding holes were determined. Sowing precision and quantity requirements were ensured. The seeding part is connected with the main frame by a parallel four-bar copying mechanism, so as to realize the ground copying of the seeding monomer and ensure the ditching and seeding depth.Result Field test results showed that the average qualified rate of 1-3 grains/hole was 91.16%, the average leakage seeding rate was 0.18%, and the average repeat seeding rate was 8.66%. In tests of different hole distances, qualified rates for different hole distances were above 89%, the repeat rate was below 4.85%, the leakage seeding rate were below 11%, the coefficients of variations of the hole distances were below 23.77%, and the qualified rate of seeding depth was 86%.Conclusion The working performance of the whole machine meets the requirements for pepper planting. This research can provide a reference for the research and development of precision vegetable seeders.
    6  Screening and identification of an oxytetracycline degradation strain resistant to Cu2+ and Zn2+ and its characteristics
    LIU Shanshan CHEN Yuli HONG Wen WU Qixia LU Cunlong LIU Aimin
    2020, 41(3):56-62. DOI: 10.7671/j.issn.1001-411X.201909025
    [Abstract](19227) [HTML](9530) [PDF 1.14 M](38133)
    Abstract:
    Objective As the main feed additive in breeding industry, Cu2+, Zn2+ and oxytetracycline contribute to high amounts of residues in livestock and poultry excrement and sewage, forming complex pollution. We are aimed at screening strains to degrade oxytetracycline under the stress of Cu2+ and Zn2+.Method The strain DJ1 of oxytetracycline degrading bacteria was screened and isolated from culture wastewater using selective medium. The biodegrading conditions of oxytetracycline by strain DJ1 were optimized. The tolerances of strain DJ1 to other tetracycline antibiotics and chloramphenicol were determined.Result The strain DJ1 was identified as Cutaneotrichosporon cutaneum based on morphology and 18S rDNA sequence alignment. The oxytetracycline degradation rate of DJ1 reached 78.83% after five days of culturations under the condition of pH7, 30 ℃ temperature, 50 mL liquid in 250 mL flask, 200 mg/L substrate and 1%(φ) inoculum size. In medium with lower concentration (50 mg/L) of oxytetracycline, 50 mg/L Zn2+ inhibited oxytetracycline degradation, while 50 mg/L Cu2+ inhibited oxytetracycline degradation in medium with higher concentration (200 mg/L) of oxytetracycline. DJ1 strain had high tolerance to tetracycline antibiotics and chloramphenicol, the tolerating concentrations to both were above 700 mg/L. DJ1 strain could grow on the plate of binary cross medium with antibiotics and heavy metals of Cu2+ and Zn2+, showing dual resistance to antibiotics and heavy metals.Conclusion DJ1 strain has high tolerance to tetracycline antibiotics, chloramphenicol, Cu2+ and Zn2+. It can efficiently degrade oxytetracycline and can be used to control antibiotic contamination in the environment.
    7  Relationship between soil methane emission flux and active organic carbon content in sugarcane field under drip fertigation
    BAI Xue NONG Mengling LONG Pengyu LI Fusheng
    2020, 41(3):31-37. DOI: 10.7671/j.issn.1001-411X.201907020
    [Abstract](19002) [HTML](391) [PDF 820.07 K](37970)
    Abstract:
    Objective To study the effects of drip fertigation on soil active organic carbon content and methane (CH4) emission flux in sugarcane field, and investigate the relationship between soil methane emission flux and soil active organic carbon content.Method The field experiment with different irrigation and fertilization treatments under drip irrigation was conducted in Nanning Irrigation Experimental Station from March to December in 2018. Four fertilization levels were designed: Conventional fertilization (F100, N 250 kg·hm-2, P2O5 150 kg·hm-2, K2O 200 kg·hm-2), incremental fertilization 1 (F110, 10% increase based on F100), incremental fertilization 2 (F120, 20% increase on the basis of F100), and reducing fertilization (F90, 10% reduction based on F100). Two drip irrigation levels were set: W180 (180 m3·hm-2) and W300 (300 m3·hm-2). Soil CH4 emission flux and active organic carbon contents at different growth stages of sugarcane were measured using conventional method, and the relationships between soil CH4 emission flux and active organic carbon contents in sugarcane field were analyzed by Pearson method.Result At tillering stage, W300F120 treatment increased soil soluble organic carbon (DOC) content by 156% compared with W300F100 but had lower CH4 emission flux in soil than the other treatments. At maturing stage, W300F120 treatment increased soil DOC content and microbial biomass carbon (MBC) by 114% and 49.6% compared with W300F100, respectively. CH4 emission flux in sugarcane field was only positively correlated with soil DOC content, with the correlation coefficient of 0.38.Conclusion Soil DOC content significantly affects CH4 emission flux in sugarcane field. W300F120 treatment can increase soil soluble organic carbon content in sugarcane field at tillering and maturing stages, and reduce soil CH4 emission in sugarcane field at tillering stage.
    8  Effects of nitrogen fertilizer application in rape season and nitrogen fertilizer management in rice season on photosynthetic productvity and yield of hybrid japonica rice under rape-rice rotation mode
    MA Peng YANG Zhiyuan LI Na LI Yu LYU Xu SUN Yongjian MA Jun
    2020, 41(3):23-30. DOI: 10.7671/j.issn.1001-411X.201908017
    [Abstract](18470) [HTML](10447) [PDF 765.67 K](37815)
    Abstract:
    Objective To explore the effects of nitrogen fertilizer application in rape season and nitrogen fertilizer management in rice season on hybrid japonica rice photosynthetic productivity and yield, and provide a theoretical and practical basis for suitable nitrogen fertilizer operation mode of rice under paddy-upland rotation.Method The hybrid japonica rice ‘F you 498’ was used as experimental material to investigate the effects of two nitrogen fertilizer application amounts (conventional nitrogen fertilizer application of 180 kg·hm-2, reduced nitrogen fertilizer application of 150 kg·hm-2) in rape season and three nitrogen fertilizer management methods based on 150 kg·hm-2 nitrogen fertilizer in rice season on photosynthetic characteristics, material accumulation and transport and yield of hybrid rice. The concrete nitrogen fertilizer management methods were M1 (the mass ratio of base fertilizer, tiller fertilizer and panicle fertilizer was 2∶2∶6), M2 (the mass ratio of base fertilizer, tiller fertilizer and panicle fertilizer was 3∶3∶4) and M3 (the mass ratio of base fertilizer, tiller fertilizer and panicle fertilizer was 4∶4∶2).Result Compared to conventional nitrogen fertilizer application, reduced nitrogen fertilizer application affected photosynthetic characteristics of rice at full heading stage, but the effect was not significant. M1, M2 and M3 treatments increased photosynthetic productivity of rice at full heading stage and 15 days after full heading. The photosynthetic rate increased most in reduced nitrogen fertilizer application and M3 treatment. Reduced nitrogen fertilizer application increased rice stem-sheath dry mattar mass at full heading stage and maturity stage, conversion rate and yield. M1, M2 and M3 increased rice stem-sheath dry mattar mass at full heading stage and yield. The highest increase of dry matter accumulation was in reduced nitrogen fertilizer application and M3 treatment.Conclusion Reduced nitrogen fertilizer application in rape season and M3 management method in rice season can improve rice yield by enhancing photosynthetic performance at late growth stage, increasing leaf area index, and promoting dry matter accumulation and transportation. It is the best treatment in this study.
    9  Effects of thiamethoxam on toxicity and detoxification metabolic enzyme activity of Nilaparvata lugens
    ZHANG Yuming XIANG Xing WANG Xuegui
    2020, 41(3):80-85. DOI: 10.7671/j.issn.1001-411X.201908024
    [Abstract](18391) [HTML](9147) [PDF 724.32 K](37699)
    Abstract:
    Objective To clarify the effects of thiamethoxam on resistance and detoxification metabolic enzyme activity of Nilaparvata lugens.Method The resistance levels of N. lugens population in greenhouse against four insecticides (imidacloprid, thiamethoxam, buprofezin, chlopyrifos) and the sensitivities to two new types of insecticides (sulfoxaflor, triflumezopyrim) were measured using rice seedling immersion method. The synergistic effect of three synergists [piperonyl butoxide (PBO), diethyl maleate (DEM), triphenyl phosphate (TPP)] on thiamethoxazine, and three detoxification enzymes (carboxylesterase, qlutathione S-transferase, cytochrome P450s) activities were analyzed.Result N. lugens population showed high resistance to thiamethoxam with the resistance ratio of 277.92 folds, sensitive to sulfoxaflor and triflumezopyrim, and no cross resistance to triflumezopyrim. PBO had the strongest synergistic effect on thiamethoxam with the synergistic ratio of 1.99. Cytochrome P450s activity of greenhouse population reached 4.70×10-3 IU/ mg, which was 2.13 folds to that of susceptible strain.Conclusion The increased activity of cytochrome P450s could be the main factor resulting in the metabolic resistance of N. lugens to thiamethoxam. The alternate use of sulfoxaflor and triflumezopyrim can effectively control the occurrence of N. lugens.
    10  Image recognition of Pyrausta nubilalis based on optimized convolutional neural network
    LI Jing CHEN Guifen AN Yu
    2020, 41(3):110-116. DOI: 10.7671/j.issn.1001-411X.201907017
    [Abstract](18305) [HTML](10826) [PDF 1.04 M](20500)
    Abstract:
    Objective With the continuous development of artificial intelligence and big data technology, aiming at solving the problems of low accuracy and low efficiency in conventional identification methods of corn pest, we proposed a corn borer image identification method based on the improved GoogLeNet convolution-neural network model.Method Firstly, through migration learning, the structural knowledge of the Inception-v4 network of GoogLeNet was transferred to the task of corn borer (Pyrausta nubilalis) identification, and the training mode of model construction was established. The data set of neural network training model was obtained by expanding the sample of corn borer image through data enhancement technique. At the same time, the Inception module was used to construct the network model with the ability of multi-scale convolution kernel extraction of the distribution characteristics of multi-scale corn borer, and the activation function, gradient descent algorithm and other model parameters were optimized in the experimental process. Finally, batch normalization (BN) operation was performed to accelerate optimizating model network training, and the model was applied in corn borer identification.Result Experimental results of TensorFlow framework showed that the average recognition accuracy of the optimized neural network algorithm for corn borer image was 96.44%.Conclusion The convolutional neural network recognition model based on optimization has higher robustness and feasibility, which can provide a reference for identification and intelligent diagnosis of plant pests on corn and other crops.
    11  Low altitude remote sensing-ground sensing double collection system for farmland quality
    ZHANG Feiyang HU Yueming CHEN Liancheng WANG Guangxing
    2020, 41(3):117-125. DOI: 10.7671/j.issn.1001-411X.201909049
    [Abstract](18264) [HTML](10445) [PDF 1.21 M](37485)
    Abstract:
    Objective To integrate unmanned aerial vehicle (UAV) low altitude remote sensing system and unmanned aerial vehicle-wireless sensor network (UAV-WSN), realize double monitoring of low altitude remote sensing monitoring and ground long term monitoring through one system, and provide monitoring data for space and time changes of farmland quality.Method The study explored the problem that current UAV-WSN system cann’t collect long-term monitoring data from sensor nodes on the ground and low altitude remote sensing data from UAV’s sensor at the same time. A low altitude remote sensing and ground sensing double collection method and system for farmland quality monitoring was designed, and the key steps and algorithm for integrating these two monitoring systems were studied. Adjusting UAV flying altitude and ground node density in simulation analysis experiments to compare total flying time differences of double collection system and UAV-WSN system. Result Double collection system could collect two kinds of data in one flight, UAV don’t need to fly over every ground sensor node again after collecting low altitude remote sensing data. When the ground image resolution was changed, the total flying time of double collection system was 165 s faster than UAV-WSN system. Double collection system could adjust based on UAV flight path and ground sensor node location. When the number of sensor nodes was changed, the total flying time was not changed and 129-194 s faster than UAV-WSN system.Conclusion Double collection system can reduce total operating time and complexity of sampling, and increase the efficiency of farmland quality monitoring.
    12  Effects of citrus Huanglongbing pathogen on agronomic characteristic and fruit quality of Citrus maxima cv. Shatian Yu
    WU Fengnian DAI Zehan ZHENG Yu CHEN Yanghong XU Meirong CEN Yijing DENG Xiaoling
    2020, 41(3):63-71. DOI: 10.7671/j.issn.1001-411X.201908021
    [Abstract](18196) [HTML](10424) [PDF 951.78 K](19815)
    Abstract:
    Objective To clarify the effects of citrus Huanglongbing (HLB) pathogen on agronomic characteristic and fruit quality of Citrus maxima (Burm.) Merr. cv. Shatian Yu.Method Changes in pathogenic symptom of leaves, fruit external and internal qualities as well as sensory qualities of C. maxima after infected by HLB were studied by field investigation and laboratory test. The effects of bacterial concentration and tree age on disease development process were investigated.Result After C. maxima grafted with HLB-infected scions, when pathogen concentrations remained relatively low (Ct > 28), HLB symptoms were not evident with slight mottled yellow old leaves, slight uniform yellow new leaves and normal shooting. Compared with healthy plants, leaf symptom, fruit yield, and all fruit quality indexes of C. maxima infected by HLB pathogen at the concentration of 28 < Ct < 32 had no significant changes. With the increase of HLB affection, C. maxima infected by HLB pathogen at the concentration of Ct < 26 showed typical mottled yellow leaves, total yield per plant and fruit number per plant decreased significantly, fruits were smaller and lighter with variable color. The percentage of edible fruit and juice extraction rate, soluble solid content, sweetness, plumpness and overall flavor significantly decreased, while acidity and odor degree significantly increased. The fruit lost edible value.Conclusion The disease progress of HLB-infected C. maxima is slow, but the economic value of plant is seriously affected with the increase of morbidity degree. This study provides a scientific basis for evaluating the effect of HLB on C. maxima fruit quality and offers theoretical supports for analyzing the HLB tolerance mechanism of grapefruit plants.
    13  Foliar nutrient diagnosis for fruit forest of Ginkgo biloba in Guangdong
    OUYANG Jianhui WU Daoming LIAO Dandan PENG Weixin SU Sining ZENG Shucai
    2020, 41(3):93-101. DOI: 10.7671/j.issn.1001-411X.201909006
    [Abstract](18160) [HTML](10501) [PDF 889.36 K](19992)
    Abstract:
    Objective To conduct foliar nutritional diagnosis on Ginkgo biloba located in Guangdong Meizhou ginkgo orchards based on diagnosis and recommendation integrated system (DRIS) index method, and provide a theoretical basis for nutrition management of ginkgo orchards in this region.Method Based on the amount of fruit, nine plots were clustered to get high, middle and low yield orchard. According to DRIS index method, the requirement degrees of G. biloba leaves to N, P, K, Ca, Mg, B, Zn and Mn fertilizers, and nutrient imbalance index (NII) were determined. The preliminary classification norms of DRIS index for nutrient element of fruit forest of G. biloba were established.Result The average NII of high and low yield orchard were 90.92 and 206.08, respectively. The average fertilizer requirements in high yield orchard were ranked as N > Mn > K > P > Zn > B > Ca > Mg, while those in low yield orchard were Mg > N > Ca > K > Mn > P > Zn > B. The balanced zones of DRIS index preliminary classification norms were N=-5.98±2.13, P=-0.97±4.43, K=-1.44±2.17, Mn=-1.70±11.82, Zn=-0.74±17.61, Ca=3.99±0.47, Mg=33.12±58.39, B=1.82±20.07.Conclusion The deficiency of N, K, Mg and Ca in G. biloba leaves in the orchard located in Meizhou was serious, followed by P and Mn, while the excess of Zn and B was observed. Through the ranking of the urgency of the fertilizer requirement and DRIS index grading, the balance of each nutrient element of G. biloba can be visually judged, and can be used as the basis for balanced fertilization of G. biloba.
    14  Codon usage bias of H9N2 avian influenza virus complete genomes and its influence factors
    HUANG Weihong CHEN Yongjie SUN Yankuo SUN Weidong
    2020, 41(3):15-22. DOI: 10.7671/j.issn.1001-411X.201908020
    [Abstract](18124) [HTML](10738) [PDF 951.91 K](20002)
    Abstract:
    Objective To study codon usage bias of H9N2 avian influenza virus (AIV) complete genomes and its influence factors.Method The complete genomes of Chinese epidemic H9N2 AIV strains from 2010 to 2018 were selected. The characteristics of base composition, optimal codons, influence factors of codon usage bias and adaption to the codon usage patterns of the host were analyzed.Result AU content was higher than GC content in the whole genomes of H9N2 AIV. Most of the optimal codons ended with A or U, and the average of effective number of codons (ENC) was 52.86, suggesting that codon usage bias existed, but the bias was low. The codon usage bias was mainly affected by mutation pressure and natural selection. Natural selection (accounting for 61.79%-76.15%) played a greater role than mutation pressure (accounting for 23.85%-38.21%). In addition, the average codon adaptation ind ex of H9N2 AIV to Homo sapiens ranged from 0.739 to 0.741, suggesting that H9N2 AIV might have adapted to human codon usage patterns.Conclusion The study provides a theoretical basis for genetic evolution analysis of H9N2 AIV, codon optimization of existing vaccines and development of new vaccines (codon deoptimization vaccine).
    15  Effects of straw cover amount on growth and development, dry matter accumulation, yield and quality of Ligusticum chuanxiong
    LIU Baolian GUO Junxia WU Ping WANG Xiaoyu ZHANG Songlin YANG Xiaoqian LU Changfang LI Qingmiao
    2020, 41(3):38-46. DOI: 10.7671/j.issn.1001-411X.201909050
    [Abstract](18008) [HTML](10409) [PDF 972.54 K](19744)
    Abstract:
    Objective To study the effects of straw cover amount on growth and development, dry matter accumulation, yield and quality of Ligusticum chuanxiong, and provide theoretical basis and practical guidance for sustainable agricultural development and ecological planting of L. chuanxiong.Method Single-factor randomized block design was adopted, and three treatments including no straw cover, covering Lingzi, covering whole ridge were setted. The emergence rate, morphological indexes, dry matter accumulation, drying rate, yield and chemical components of L. Chuanxiong were determined and analyzed. Finally, the economic benefit was evaluated.Result Covering whole ridge treatment had the highest emergence rate reaching 97.66%, which was significantly higher than no straw cover treatment (94.05%). The emergence rate of covering Lingzi was 96.68%, which was not significantly different from other two treatments. Straw cover treatment had significant effects on plant height during multiple growth stages especially early growth stage, had significant effects on stem number, leaf number and rhizome width at late growth stage and no significant effect on rhizome length and rhizome thickness. Except for senescene period, the aboveground part dry weight, underground part dry weight and aboveground part drying rate of covering Lingzi and covering whole ridge were higher than those of no straw cover treatment at each growth stage. The yield of covering whole ridge was 16.6% and 41.6% higher than those of covering Lingzi and no straw cover respectively, and the net income was 24.4% and 68.3% higher than those of other two treatments respectively. Straw cover treatment increased the contents of ferulic acid, senkyunolide A, ligustilide, and total phthalides in the rhizome of L.chuanxiong.Conclusion Straw cover treatment of L. chuanxiong during planting period is conducive to promoting growth and development and dry matter accumulation of L. chuanxiong, and improving its yield, quality and economic benefits. The effect of covering whole ridge is superior to the traditional half-cover of covering Lingzi solely.
    16  Effect of dietary supplementation of fish oil on intestinal barrier function in mouse fed with high-fat diet
    LIU Fangfang YANG Xiaohua ZHANG Fenglin SONG Min SU Han ZHU Xiaotong SHU Gang WANG Lina GAO Ping JIANG Qingyan WANG Songbo
    2020, 41(3):1-8. DOI: 10.7671/j.issn.1001-411X.201908029
    [Abstract](18006) [HTML](9199) [PDF 1.36 M](20081)
    Abstract:
    Objective To investigate the effect of dietary supplementation of fish oil on the barrier function of mouse fed with high-fat diet (HFD).Method 36 C57BL/6J female mice (4-week-old) were randomly divided into control group (CK), HFD group, and HFD +fish oil group, with 12 mice in each group. Mice in three groups were fed with basal diet, HFD and HFD supplemented with 5% fish oil (iso caloric with HFD), respectively. The experiment lasted for 21 weeks, and the food intake and body weight of mice were measured weekly. During the experiment, intestinal permeability of each mouse was measured, and the fat content and energy in feces were determined. At the end of the experiment, endotoxin levels in serum were detected, and intestinal morphology, the number of intestinal goblet cells, and the expressions of intestinal tight junction proteins and inflammatory factors were examined.Result Compared with HFD group, addition of fish oil in diet significantly increased food intake and energy intake, decreased fecal crude fat content and energy excretion, while significantly reduced body weight of mice (P < 0.05). In terms of intestinal morphology, compared with HFD group, addition of fish oil significantly increased the ratio of villus height to crypt depth (lV/dC) by 43.1% in mouse jejunum and 67.5% in ileum and the number of goblet cells in ileum villous by 16.7% (P < 0.05). Compared with HFD group, addition of fish oil reduced the fluorescent glucan and endotoxin levels in serum by 34.3% and 50.4% respectively (P < 0.05). Addition of fish oil also reversed the decrease in expressions of intestinal tight junction proteins caused by HFD. In terms of expression of inflammation factors, compared with HFD group, addition of fish oil significantly decreased the expressions of proinflammatory factors including IL-8, IL-6 and IL-1β, and significantly elevated the expression of anti-inflammatory factor IL-10 in mouse jejunum and ileum (P < 0.05).Conclusion Dietary supplementation of fish oil can reduce the HFD-induced impairment of intestinal barrier function, which might be associated with the fish oil reducing intestinal inflammation.
    17  Studies on the Allelopathic Effects of Chromolaena odoratum
    HE Yan biao ZHANG Mao xin HE Ting yu GU Wen xiang
    2002, 23(3):60-62. DOI: 10.7671/j.issn.1001-411X.2002.03.017
    [Abstract](11603) [HTML](0) [PDF 122.68 K](2116)
    Abstract:
    对飞机草(Chromolaena odoratum (L.)R.M.King and H.Robinson.)乙醇提取物的化感作用了初步研究。结果表明,飞机草乙醇提取物对豇豆、青瓜、萝卜、菜心、大白菜、小白菜和水稻、稗草具有不同程度的化感作用,总体上呈现出低促高抑的现象,且随着溶液浓度增大而抑制作用增强。其中干物质为0.1g/mL的飞机草乙醇提取物溶液对菜心、大白菜和小白菜的种子萌发、幼苗生长、根长生长抑制作用最为明显;干物质为0.01、0.002g/mL溶液对小白菜、大白菜和稗草的幼苗生长均具有一定的促进作用;干物质为0.01、0.002g/mL溶液对青瓜、小白菜和稗草根长生长也具有一定的促进作用。
    18  Nest Architecture of Four Ponerine Ant Species (Formicidae, Ponerinae) and Organisms Present in Their Nests
    KE Yunling TIAN Weijin ZHUANG Tianyong WANG Chunxiao LIANG Meifang
    2013, 34(1):45-50. DOI: 10.7671/j.issn.1001-411X.2013.01.010
    [Abstract](9213) [HTML](0) [PDF 1.90 M](8642)
    Abstract:
    Pachycondyla astuta Smith, Diacamma rugosum (Le Guillou), Odontoponera transversa (Smith) and Harpegnathos venator (Smith) are common ponerine ants in east China and south China. They are potential natural enemies of forest termites. Twenty nests of the four ponerine ant species were excavated to study their nesting environment, nest architecture and organisms present in their nests. The results showed that the ponerine ants mainly built their underground nests in rubber plantations and litchi forests. Their nests were simple, with only several to dozens of layered or random chambers in the soil. The depth of the nests was usually less than 0.6 m. Organisms including insects of Hymenoptera and Isoptera as well as some small soil animals were found in or near the nests. Their relationships with the ponerine ants are sympatry, symbiosis and prey-predator relationship.