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    Crop Science
    State quo of cultivar registration and extension of first-cropping two-line hybrid rice in Yangtze River Area and its enlightenment to Zhejiang Province
    FANG Yuwei, LI Rongde, CHEN Xiaoshang, DUAN Min, LIU Shoukan, LIU Qinglong
    2018, 30(2):  177-186.  DOI: 10.3969/j.issn.1004-1524.2018.02.01
    Abstract ( 432 )   HTML ( 0 )   PDF (1396KB) ( 1390 )  
    To investigate the rules and present situation on the development of first-cropping two-line hybrid rice in Yangtze River Area, the data of cultivar registration and promotion area during 1998-2015 were collected and analyzed. The results showed that: 1) the first-cropping two-line hybrid rice was getting more and more important due to its increasing planting area in the Yangtze River Region. Up to the end of 2015, a total of 139 first-cropping two-line hybrid rice combinations had been registered. Among them, 26 combinations were registered by the National Crop Variety Examination and Approving Committee, and 5 combinations were titled “Super Rice”. 2) According to the Ministry of Agriculture statistics, during 1998 to 2015, there were 76 first-cropping two-line hybrid rice combinations which had promotion area equal to or more than 6 700 hm2, with an accumulative promotion area of 7 531 000 hm2. Hunan, Hubei and Jiangxi were the main first-cropping two-line hybrid rice growing provinces, with an accumulative promotion area of 6 974 000 hm2, accounting for 92.6% of the total promotion area. 3) The seeds companies played the most important role in the breeding and promotion of first-cropping two-line hybrid rice, the cultivars from which had an accumulative promotion area accounting for 41.6% of the total promotion area. The breeding organizations from Hunan Province made the greatest contribution, whose cultivars were widely popularized in Hunan, Jiangxi and Hubei, with an accumulative promotion area of 5 887 000 hm2. Present thesis introduced the stat quo of cultivar registration and extension of two-line early hybrid rice in Yangtze region, analyzed the contribution of the major sterile lines and their genealogical links, and finally proposed the disadvantages and countermeasures for the development of frist-cropping two-line hybrid rice in Zhejiang Province.
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    Rice yield prediction with panicle spectral indices
    JIANG Qingsu, CHENG Qilu, XU Ligen, ZHOU Qifa
    2018, 30(2):  187-193.  DOI: 10.3969/j.issn.1004-1524.2018.02.02
    Abstract ( 501 )   HTML ( 2147483647 )   PDF (686KB) ( 2873 )  
    This pilot study was aimed to investigate the feasibility of predicting rice yield with panicle spectral indices. A field experiment was conducted with two rice genotypes of contrasting yield potential and three contrasting nitrogen (N) levels at Hangzhou, China in 2015. Leaf and panicle hyperspectral reflectance (350-2 500 nm), chlorophyll concentrations (Chlc) and carotenoids concentrations (Carc) were measured at three different dates, and the yield components and grain yield were determined at maturing stage. It was found that the panicle spectra were distinctly different from the leaf spectra with the disappearance of the sharp green “hump”. As compared to the corresponding leaf indices, the panicle normalized vegetation index (NDVI) and photochemical reflectance index (PRI) were more reliable in differentiating the N levels, more sensitive to the chlorophyll content, and performed more accurately in predicting the rice yield. In the rice yield prediction based on best relationship fit, NDVI and PRI in the leaves at the three dates yielded a RSME of 873.4-1 125.0 and 723.3-889.4 kg·hm-2, respectively, while NDVI and PRI in the panicles at the three dates achieved a RMSE of 681.7-743.1 and 515.0-637.8 kg·hm-2, respectively.
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    Animal Science
    Isolation, identification and antibiotic sensitivity of Morganella morganii from Channa argus
    YANG Yibin, SONG Yi, YANG Qiuhong, LIU Yongtao, YANG Xianle, AI Xiaohui
    2018, 30(2):  194-202.  DOI: 10.3969/j.issn.1004-1524.2018.02.03
    Abstract ( 615 )   HTML ( 1 )   PDF (2546KB) ( 1479 )  
    Isolation, identification and drug sensitivity test were performed on the pathogen of Channa argus which were suffering from disease in an aquatic farm in Nanchang in order to provide references to effectively prevent and control disease. In this study, a bacterial strain JX15 was isolated from the liver, kidney, spleen, ascites and ulcerated muscle of dying C. argus with the routine separation methods, and identified by morphological observation, physicochemical properties test and molecular biology methods. Moreover, the 16S rRNA and gyrB gene of strain JX15 were amplified and the homology of 16S rRNA and gyrB gene sequences were analyzed, and the phylogenetic tree was constructed. Additionally, an experimental infection test by intraperitoneal injection with isolate was studied, and drug sensitivity test was conducted using K-B paper diffusion method. The results showed that the isolate was identified as Morganella morganii by analyzing biochemical reactions, 16S rRNA and gyrB gene sequences. The fish intraperitoneally-injected with the strain JX15 showed like ones infected by M. morganii naturally. The isolate from artificially-infected fish showed similar morphological and biochemical characteristics to those from naturally infected fish. Therefore, M. morganii was pathogen to C. argus with similar clinical signs as naturally diseased fish. The LD50 of the strain JX15 to C. argus was 3.4×105 cfu·g-1 according to the Reed-Muench method. Additionally, the results from drug sensitivity test showed that strain JX15 was highly sensitive to 7 medicines, such as florfenicol, norfloxacin, cefotaxime and some else drugs, and it was medium sensitive to furazolidone, chloramphenicol, kanamycin, and streptomycin, but it was resistance to 11 medicines, including ciprofloxacin, oxacillin, penicillin and other durgs. This study proved that the disease in C. argus from an aquatic farm in Nanchang, Jiangxi Province was caused by M. morganii, and this disease could be treated by six medicaments, i.e. florfenicol, cefotaxime, neomycin, tobramycin, gentamicin and amikacin.
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    Isolation and identification of Streptococcus iniae from sturgeon and its pathological lesions of infection
    ZHENG Liping, GENG Yi, LEI Xueping, YU Zehui, HUANG Xiaoli, CHEN Defang, OUYANG Ping, CAO Shiqi, HAN Rui
    2018, 30(2):  203-210.  DOI: 10.3969/j.issn.1004-1524.2018.02.04
    Abstract ( 564 )   HTML ( 1 )   PDF (2053KB) ( 1377 )  
    During June of 2016, a serious infectious disease characterized by hemorrhage and neurological symptoms outbroke in sturgeon farms of Pengzhou, Sichuan Province. The main pathologic lesions were degeneration, necrosis, hemorrhage and infiltration of the inflammation cells that was particularly marked in liver, kidney, heart and brain. A pathogenic bacteria was isolated from the viscera of sick sturgeons and the isolate was identified as Streptococcus iniae by physiological and biochemical characteristics, phylogenetic analysis and specific PCR detection, its pathogenicity was confirmed by artificial infection test. The drug sensitivity results showed that the isolate was sensitive to florfenicol, gentamicin, doxycycline, etc., but resistant to tetracycline and neomycin.
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    Preventive effect of purslane combined with probiotics on heat-toxin syndrome diarrhea mice
    LIU Cuiyan, CHEN Siyu, SUN Taotao, SHANG Lili, YANG Mingchuan, YANG Zisheng, HAN Chunyang
    2018, 30(2):  211-219.  DOI: 10.3969/j.issn.1004-1524.2018.02.05
    Abstract ( 551 )   HTML ( 0 )   PDF (2210KB) ( 1390 )  
    In order to investigate the effect of combined application of purslane and probiotics on prevention of heat-toxin syndrome diarrhea in mice, purslane and probiotics were used in this study. 144 male Kunming mice were randomly divided into 9 groups, namely: different dose of purslane (1, 2.5, 5.0 g·kg-1 feed) groups, different doses of purslane (1, 2.5, 5.0 g·kg-1 feed) and probiotics (2×106 cfu·g-1BW·d-1) groups, probiotic (2×106 cfu·g-1BW·d-1) group, model group and blank group. The model group and blank group mice were fed normal diet and blank group mice did not build model; Other mice were fed with medicated feed or/and intragastric probiotics. After 10 d treatment with drugs and/or probiotics, except blank group, the diarrhea model of the other group mice was constructed by gavage once a day with dried ginger extract for 10 days then intraperitoneal injection enterotoxigenic Escherichia coli(ETEC) for 3 days. The occurrence of diarrhea in mice was closely observed after attack bacteria. At the end of the experiment, blood samples were collected for biochemical examination, intestinal tissues were collected for histopathological examination and detection of inflammatory factors expression such as TNF-αIL-1βIL-6、IL-10、TGF-β1、IFN-γ. The results were as follow: (1) The diarrhea rate of mice in the model group was 87.5% and the diarrhea rate in the high dose purslane combined with probiotic group was just 12.5% at 24 h after attack bacteria. (2) Compared with the blank group, the mRNA expression of TNF-α, IL-1β, IL-10, IL-6, TGF-β1, IFN-γ were significantly increased in model group (P<0.05). Compared with the model group, the mRNA expression of the inflammatory factors mentioned above were significantly decreased (P<0.05) in the high dose purslane combined with probiotic group. (3) In the model group, the small intestine villi of mice were broken, partially necrotic and exfoliated, and the intestinal glands were deformed obviously. The intestinal villi of the high dose purslane combined with probiotics group were basically complete and the intestinal structure became normal. (4) Compared with the blank group, the content of Cl- in serum of model group increased significantly (P<0.05), and the content of Ca2+ decreased significantly (P<0.05). Compared with the model group, the content of Cl- in serum of the high dose purslane combined with probiotics group decreased significantly (P<0.05) and the content of Ca2+ increased significantly (P<0.05). The results showed that the high dose purslane combined with probiotics could effectively prevent the occurrence of diarrhea in mice induced by ETEC and dried ginger extract. Its mechanism included reducing intestinal inflammation by down-regulating the expression of gut associated inflammatory factors and restoring the electrolyte balance by regulating the blood Cl- and Ca2+ levels.
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    Establishment of one-step Taqman quantitative PCR detection method and molecular S gene characterization analysis of porcine deltacoronavirus
    SHAN Ying, XU Weicheng, SHI Xingfen, LIU Ziqi, CHEN Cong, LUO Hao, LIU Yajie, FANG Weihuan, LI Xiaoliang
    2018, 30(2):  220-227.  DOI: 10.3969/j.issn.1004-1524.2018.02.06
    Abstract ( 527 )   HTML ( 4 )   PDF (1115KB) ( 1481 )  
    Porcine deltacoronavirus (PDCoV) is a newly discovered pathogenic porcine coronavirus that has been isolated from diarrheal pigs in farms of some provinces in China, confirming that the disease has been prevalent in our country. This study aims to investigate the prevalence and molecular evolution of PDCoV in Zhejiang Province. The results showed that the established PDCoV one-step TaqMan probe was specific for fluorescence quantitative detection. The detection sensitivity was 3.94 × 102 copies·μL-1. The amplification efficiency was 108% and the R2 value was 0.997, regression equation of standard curve is Y=-3.156X+1.826. The virus was not detected in clinical diarrhea samples of 258 piglests collected from April, 2013 to December, 2016, but the positive rate was 50% (12/24) in the period from January to April, 2017. The homology of the nucleotide and amino acid of the S gene of the seven clinical isolates was 99.98%-100% and 99.99%-100%, respectively. Compared with the reference strain and the Hongkong and American isolated trains, there were three base deletions and a number of mutations in our clinical isolated strains. S-protein was used for the molecular evolution analysis. Seven strains of clinical isolates were found to be belong to the evolutionary branch of the delta virus, and were closer to the other PDCoV strains isolated from China, while farther to the strains isolated from the United States and Thailand, suggesting that PDCoV epidemic strains have a certain geographical distribution. This study provides the genetic characteristics of PDCoV clinical isolates in Zhejiang Province, and provides data for the prevention and control of PDCoV-induced piglet diarrhea and the development of epidemic strains.
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    Horticultural Science
    Sodium acetate and compound with four kinds of minerals on the mycelium biomass of Volvariella volvacea
    HOU Lijuan, LIN Jinsheng, LIU Shaohua, LI Ruixiang, MA Lin, JIANG Ning, QU Shaoxuan, LI Huiping
    2018, 30(2):  228-235.  DOI: 10.3969/j.issn.1004-1524.2018.02.07
    Abstract ( 574 )   HTML ( 2 )   PDF (1117KB) ( 1619 )  
    In this paper, mycelial dry weight of mycelium and DNA content of Volvariella volvacea were determined to detect the effect of different concentrations of sodium acetate on mycelial biomass of V. volvacea. The results showed that with the increase of concentration of sodium acetate, mycelial biomass increased linearly. When the concentration reached 0.7 g·L-1, the biomass reached the peak, and the content of DNA was 468.9 ±4.10 μg·g-1, which was significantly higher than that of CK. While the concentration of sodium acetate was 0.9 g·L-1 and 1.1 g·L-1, the biomass decreased, but higher than that of CK. It was concluded that the suitable concentration of sodium acetate can significantly increase the mycelium dry weight of V. volvacea. Based on the optimal concentration of sodium acetate (0.7 g·L-1), the effect of Cu, Zn, K, Mn element and compound trace element on mycelia biomass were compared. The results showed that K and Cu element showed good effect, the mycelial biomass under all concentrations increased. Compared with CK, when the application amount of KH2PO4 was 8 g·L-1, the mycelial biomass was significantly increased by 84.32% (P<0.05); when the application amount of CuSO4 was 0.04 g·L-1, the mycelia biomass was significantly increased by 73.19% (P<0.05); when the application amount of ZnSO4 were 0.25 g·L-1 and 0.20 g·L-1, the mycelia biomass was increased by 42.69% and 20.34%, respectively; when the application amount of MnSO4 was 0.35 g·L-1, the mycelia biomass was increased by 25.23%. The Zn element and Mn element showed no significant effect on mycelium biomass with CK.
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    Analysis on germplasm genetic diversity of ornamental pomegranate (Punica granatum L.) by ISSR markers
    WANG Qingjun, MA Li, HAO Zhaoxiang, LUO Hua, BI Runxia, ZHAO Li'na, HOU Lefeng
    2018, 30(2):  236-241.  DOI: 10.3969/j.issn.1004-1524.2018.02.08
    Abstract ( 496 )   HTML ( 0 )   PDF (869KB) ( 1472 )  
    In order to investigate the germplasm genetic diversity and genetic relationship of ornamental pomegranate (Punica granatum L.), the genetic relationships of 35 ornamental pomegranate cultivars were evaluated by ISSR markers. Eight ISSR primers with good polymorphism were screened out. A total of 168 bands were amplified from 8 ISSR primers, of which 158 bands were polymorphic loci. The percentage of polymorphic band (PPB) was 94.05%, the number of alleles (Na) was 1.940 5, the effective number of alleles (Ne) was 1.678 5, Nei's gene diversity (He) was 0.379 9 and Shannon's information index (I) was 0.553 0. The genetic similarities coefficient (GS) between cultivars ranged from 0.416 7 to 0.922 6, suggesting ornamental pomegranate cultivars had abundant genetic diversity. Thirty-five ornamental pomegranate cultivars were divided into 6 groups at GS of 0.668 based on UPGMA method.
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    Study on the application of ebb and flow irrigation for tomato seedlings
    ZHU Longjing, CHEN Xianzhi, ZHOU Youhe, SU Shiwen, WANG Kelei, XU Jian
    2018, 30(2):  242-247.  DOI: 10.3969/j.issn.1004-1524.2018.02.09
    Abstract ( 496 )   HTML ( 1 )   PDF (574KB) ( 1720 )  
    In order to screen the suitable parameters of ebb and flow irrigation for tomato seedlings, the L9 (33) orthogonal experimental was designed using tomato variety Ouxiu201. The growth and physiological changes and the irrigation index of tomato were analyzed under the top sprinkling irrigation and ebb and flow irrigation. The results showed that compared with the top sprinkling irrigation, ebb and flow irrigation could save water 34.1%-77.0%. Irrigation height was the most important factor affecting the growth of upper tomato plants and water consumption, while dipping time played a major role in the growth of underground part of tomato plants, and the irrigation frequency was the major role affecting photosynthetic physiology of tomato, under the 3 treatment factors set in the test. In summary, the irrigation height of 2.0 cm, dipping time of 1.5 h, the irrigation frequency of once every 3 days combination can be used as appropriate parameters of the tomato ebb and flow irrigation.
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    Effects of enhanced UV-B radiation and nitrogen deposition on chlorophyll fluorescence parameters of invasive plant Triadica sebifera
    ZHENG Xiang, JIANG Liangbo, DENG Bangliang, LIU Qian, LIU Xishuai, ZHENG Liya, GUO Xiaomin, LIU Yuanqiu, ZHANG Ling
    2018, 30(2):  248-254.  DOI: 10.3969/j.issn.1004-1524.2018.02.10
    Abstract ( 460 )   HTML ( 1 )   PDF (1396KB) ( 1518 )  
    In order to study the effects of enhanced UV-B radiation and nitrogen deposition on chlorophyll fluorescence parameters in invasive plant Triadica sebifera, we used plant materials which came from the native land China and the invaded land US. The results showed that UV-B radiation and nitrogen deposition showed interactive effect on plant height, and UV-B radiation and origin had a significant interaction on Fv/Fm. UV-B radiation significantly increased the SPAD of T. sebifera, and nitrogen deposition significantly increased SPAD and decreased Y(Ⅱ) and ETRmax of T. sebifera. Nitrogen deposition could alleviate UV-B radiation stress effects on plant growth of Triadica sebifera. Compared with the local Chinese populations, the population from America showed higher light energy conversion efficiency and growth rate of height, lower SPAD and was more sensitive to UV-B radiation stress.
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    Effects of substrates with different hickorg epicarp contents on yield and fruit quality of tomato
    SHAO Yangfeng, MA Yanping, YING Xuebing, XU Jian, LI Songhao, HE Yong
    2018, 30(2):  255-260.  DOI: 10.3969/j.issn.1004-1524.2018.02.11
    Abstract ( 586 )   HTML ( 0 )   PDF (980KB) ( 1690 )  
    Effects of substrates with different hickorg epicarp contents on the plant growth, yield and fruit quality of protected tomato were investigated in the present study. The local soil was set as the control, and two compound substrates were selected. One compound substrate was manure-hickorg epicarp with volume ratio of 7:3, and the other one was manure-hickorg epicarp-rice hull with volume ratio of 7:2:1. We found that in comparison with local soil, the bulk density and EC of both substrates decreased significantly, and soil porosity, pH and organic matter content increased notably. Both compound substrates improved the yield and fruit quality significantly. The tomato yield in compound substrate of manure-hickorg epicarp reached 22.88 kg·m-2, and increased by 35.9% compared with the control. Besides, in comparison with the control, the content of soluble sugar, soluble protein and Vc in tomato fruits grown in compound substrate of manure-hickorg epicarp increased by 72.1%, 23.6% and 122.1%, respectively. Meanwhile, the yield of tomato in compound substrate of manure-hickorg epicarp-rice hull reached 21.86 kg·m-2, and increased by 29.9% compared with the control. Furthermore, the content of lycopene in tomato fruits grown in compound substrate of manure-hickorg epicarp-rice hull increased by 18.8%. Therefore, both compound substrates can be used in protected cultivation of tomato.
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    Plant Protection
    Determination of imidacloprid and fenpyroximate in celery by QuEChERS-LC-MS/MS
    LIU Ying, LI Yunzhi, CHEN Liezhong, WANG Yanhua, XU Zhenlan, JIANG Jinhua, TANG Tao, CHEN Wenxue, WANG Qiang, ZHANG Changpeng
    2018, 30(2):  261-267.  DOI: 10.3969/j.issn.1004-1524.2018.02.12
    Abstract ( 487 )   HTML ( 1 )   PDF (1175KB) ( 1580 )  
    In this study, a simple and practical QuEChERS-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established to detect the residues of imidacloprid and fenpyroximate in the roots, stems, leaves of celery. The samples were extracted and purified by QuEChERS method, and analyzed by LC-MS/MS. Results showed that the average recoveries of imidacloprid in roots, stems, leaves of celery were 77.15%-103.48% at three spiking levels from 0.05 mg·kg-1 to 1.00 mg·kg-1 with relative standard deviations (RSDs) of 1.40%-9.97%. The average recoveries of fenpyroximate in roots, stems, leaves of celery were 77.35%-100.42% at three spiking levels from 0.05 mg·kg-1 to 1.00 mg·kg-1 with relative standard deviations (RSDs) of 2.01%-6.95%. Limit of detections (LODs) were estimated to be 0.120 μg·kg-1 for imidacloprid, and 0.015 μg·kg-1 for fenpyroximate, respectively. Limit of quantitations (LOQs) for imidacloprid in the roots, stems, leaves of celery were 1.65, 0.87 and 1.08 μg·kg-1, respectively. LOQs for fenpyroximate were 1.24 μg·kg-1 (roots), 0.75 μg·kg-1 (stems) and 0.78 μg·kg-1 (leaves). The celery samples were detected using this established method, the recovery and the precision were in accordance with the requirements of pesticide residue analysis. The method was suitable for the detection of a large number of samples in the laboratory.
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    Environmental Science
    Effects of maize straw returning modes on soil fertility and maize yield
    SA Rula, YANG Hengshan, GAO Julin, FAN Fu, ZHANG Ruifu, LIU Jing, WU Shuai
    2018, 30(2):  268-274.  DOI: 10.3969/j.issn.1004-1524.2018.02.13
    Abstract ( 636 )   HTML ( 2 )   PDF (684KB) ( 1684 )  
    In order to explore the suitable mode of maize straw returning in west Liaohe Plain, 4 modes, i.e. deep plowing with straw returning (DR) , rotary tillage with straw returning (RR), applying decomposing agent+deep plowing with straw returning (DR+D) and applying decomposing agent+rotary tillage with straw returning (RR+D) were proposed. By taking rotary tillage without straw returning (CK) as control, effects of 4 modes on soill available nutrients, soil enzyme activity and maize yield were compared in 2016. It was shown that RR+D and RR increased maize yield by 24.56% and 28.00%, respectively, as compared to CK, yet there was no significant difference within the yield of DR, DR+D and CK. RR+D significantly (P<0.05) increased the alkaline nitrogen content in 0-10 cm soil layer by 94.56% than CK, while the other treatments showed no significant difference in soil available nutrients contents. All 4 maize straw returning modes could increase soil enzymes activities in different soil depth by varied degrees. On the whole, applying decomposing agent+rotary tillage with straw returning was the optimum mode in the study area.
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    Effects of controlled release nitrogen fertilizer on yield and nitrogen use efficiency of cotton in fluvo-aquic soil of Bohai Sea Ring Area
    LIU Quanfeng, LIU Yongzhen, CAO Jinfeng, YANG Zhenli, ZHAI Yuzhu, LAI Deqiang, SUN Yi, LIU Zhenzhen
    2018, 30(2):  275-279.  DOI: 10.3969/j.issn.1004-1524.2018.02.14
    Abstract ( 547 )   HTML ( 0 )   PDF (571KB) ( 1495 )  
    In the present study, with the conventional fertilization method using urea as CK, a field experiment was conducted to study the influence of controlled release nitrogen fertilizer on chlorophyll content in the main stem leaf of cotton, cotton yield and its component factors, cotton fiber quality and nitrogen use efficiency. It was shown that, with the same application amount of nitrogen, the yield of seed cotton and lint cotton was significantly (P<0.05) increased under the controlled release nitrogen fertilizer than that of urea (CK), and the nitrogen fertilizer utilization rate, the fertilizer contribution rate, the agronomic efficiency were all significantly (P<0.05) higher under the controlled release nitrogen fertilizer than that of urea (CK). The results indicated that the controlled release fertilizer could increase fertilizer use efficiency. When the application amount of controlled release nitrogen fertilizer was 80% of N amount in the conventional fertilization method, there was no significant difference in yield between treatments. This application rate could be used as reference in fluvo-aquic soil of Bohai Sea Ring Area.
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    Food Science
    Comparison of crude polysaccharides extraction from marine diatom under different methods
    CHEN Lihua, WANG Xin, CHENG Jiayang
    2018, 30(2):  280-289.  DOI: 10.3969/j.issn.1004-1524.2018.02.15
    Abstract ( 448 )   HTML ( 1 )   PDF (2299KB) ( 1449 )  
    Crude polysaccharide was extracted from marine diatom biomass cultured outdoor by using several methods (water extraction, acid extraction, alkali extraction, ultrasonic assisted extraction and freeze thawing assisted extraction method). The extraction method was optimized by comparing extraction rates, total polysaccharides content, protein content and sulfate groups content of the crude polysaccharides under different methods. The results showed that the lowest extraction rate was found in the case of water extraction, and the highest value was found in the case of concentrated alkaline (4% NaOH) method. The total polysaccharides content of the crude polysaccharides extracted by physical methods (ultrasonic, freeze+thawing combined with heated water method) were relatively higher than that by chemical methods, with the highest value under freeze thawing +90 ℃ method and the lowest value under acid extraction method. However, the sulfate groups content showed the highest value under acid method and the lowest under concentrated alkaline method. Considering the extraction rate of crude polysaccharides and components of crude polysaccharides, the total polysaccharides content in unit diatom biomass was calculated and showed a trend as: concentrated alkaline+freeze thawing>concentrated alkaline+freeze thawing+90 ℃>concentrated alkaline>acid extraction>ultrasonic+freeze thawing +90 ℃>alkali extraction>ultrasonic+freeze thawing>freeze thawing+90 ℃; and the highest sulfate groups content was found when using concentrated alkaline+freeze thawing and the lowest one was alkali extraction. Therefore, it could be concluded from these results that concentrated alkaline+freeze thawing was the most suitable method for crude polysaccharides extraction from marine diatom which could keep the sulfate groups content at a relatively high level. The concentrated alkaline+freeze thawing method was further used for crude polysaccharides extraction from four isolated diatom species. Results suggested that the total polysaccharides content in unit dry mass of Entomoneis sp. was higher than that of the other three diatom species (24%). However, Chaetoceros sp. showed the highest sulfate groups content (5.05%), and Entomoneis sp. showed the lowest (0.51%).
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    Rapid determination of quinolones in aquatic products by immune colloidal gold method
    LIU Aichun, LIU Chao, ZHANG Le, TONG Chaoming, LI Feng, ZHAO Yun
    2018, 30(2):  290-297.  DOI: 10.3969/j.issn.1004-1524.2018.02.16
    Abstract ( 486 )   HTML ( 1 )   PDF (1159KB) ( 1550 )  
    Antibodies were produced by using the hybridoma cell line QH12, and the highly sensitive immune colloidal gold reagent strip was thus prepared. The lowest detection limits of these stripes for lomefloxacin, ofloxacin, norfloxacin, pefloxacin were 2.0, 2.5, 2.5, 5.0 ng·mL-1, respectively. The colloidal gold rapid test methods (GICT) for determination of quinolones residues in aquatic products were developed through optimization of sample pretreatment. Detection results of GICT were further compared with that of HPLC method, which was confirmed by LC-MS/MS method. It was shown that the sensitivity of GICT method was higher than that of HPLC. The test results of GICT and LC-MS/MS were in coincidence. The whole detection process of a single sample cost 25 minutes. Comprehensive comparative analysis showed that GICT method was suitable for rapid determination of quinolones in aquatic products.
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    Optimization of extraction process of total flavonoids from Chimonanthus salicifolius S.Y.H by HPLC combined with response surface methodology and its antibacterial activity
    WEN Huiping, XIAO Jianzhong, LEI Weimin, JI Jiana
    2018, 30(2):  298-306.  DOI: 10.3969/j.issn.1004-1524.2018.02.17
    Abstract ( 527 )   HTML ( 0 )   PDF (2641KB) ( 1634 )  
    The contents of rutin, quercetin and kaempferol extracted from Chimonanthus salicifolius were determined by high performance liquid chromatography (HPLC). Based on the single factor analysis, the effect of ethanol concentration, extraction time and extraction temperature on the yield of flavonoids from C. salicifolius were studied by response surface methodology. Meanwhile, the antibacterial activity of flavonoids from C. salicifolius was assessed by filter paper method. The results showed that main factors affecting the extraction of total flavonoids from C. salicifolius were ethanol concentration, extraction time, extraction temperature. The optimum extraction conditions of total flavonoids were: extraction temperature of 90 ℃, solid-liquid ratio of 1:15, ethanol concentration of 79%, extraction time of 1.7 h. Under the optimal conditions, contents of rutin, quercetin, kaempferol were 0.861, 0.504, 0.492 mg·g-1, respectively; and the extraction yield of total flavonoids was 1.857 mg·g-1 which differed from the theoretical value of 1.50%,the total flavonoids extracted from Chimonanthus salicifolius had antibacterial activity against many kinds of bacteria, especially Bacillus cereus and Escherichia coli, the mean diameters of the inhibition zones about them were 13.21 and 11.18 mm, respectively. Therefore, response surface methodology was feasible for the extraction optimization of total flavonoids from C. salicifolius. The total flavonoids from C. salicifolius had good antibacterial activity, indicating that it might have great application prospects in the fields of medicine.
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    Study on bacterial cellulose production from citrus dregs by intermittent shaking culture
    YANG Ying, TANG Weimin, XING Jianrong, ZHENG Meiyu, LU Shengmin
    2018, 30(2):  307-313.  DOI: 10.3969/j.issn.1004-1524.2018.02.18
    Abstract ( 566 )   HTML ( 0 )   PDF (879KB) ( 1466 )  
    In the present study, a bacterial cellulose (BC) high-yielding producer, Gluconacetobacter intermedius CIs26, screened from rotten citrus fruits, was utilized as fermentation strain. Effects of citrus dregs pretreatment, carbon source, nitrogen source, and growth factor on BC gel production by intermittent shaking culture were investigated. It was shown that the optimized conditions for pretreatment of citrus dregs were as follows: mixing ratio of citrus fruit dregs to water was 1:6; the addition of pectinase and cellulase were 0.3, 0.1 g·L-1, respectively; hydrolysis temperature was 45 ℃, and hydrolysis time was 2 h. The filtered hydrolysate of citrus dregs was used as the solvent of culture medium. The optimal conditions for BC production were as follows: sucrose 70 g·L-1, ammonium sulphate 3 g·L-1, yeast extract 7 g·L-1, lactic acid 1 g·L-1, and disodium phosphate 2 g·L-1. Under the above condition, BC yield reached 10.26 g·L-1, suggesting that citrus dregs could be a good raw material for BC production of CIs26 by intermittent shaking culture.
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    Determination of tetracycline antibiotics residues in milk by molecularly imprinted solid phase extraction-high performance liquid chromatography
    FU Zhenzhen, ZENG Yue, LI Zengwei, HE Li, ZHOU Kang, LIU Shuliang, ZOU Likou, AO Xiaolin, CHEN Shujuan
    2018, 30(2):  314-322.  DOI: 10.3969/j.issn.1004-1524.2018.02.19
    Abstract ( 519 )   HTML ( 2 )   PDF (1274KB) ( 1525 )  
    Molecularly imprinted technology (MIT) was used for the synthesis of tetracyclines molecularly imprinting polymers (MIPs), which were used as the filler in the preparation of solid phase extraction column. Then high performance liquid chromatography (HPLC) was applied to determine the tetracyclines residues in milk. The MIPs with specific adsorption ability were synthesized by precipitation polymerization in acetone acetonitrile mixed solution, with doxycycline hydrochloride (DC) as the template molecule, methacrylic acid (MAA) as the function monomers and ethylene glycol dimethyl acrylic ester (EGDMA) as the crosslinking agent. Their ability of adsorbing tetracycline antibiotics was detected by HPLC, and the selected MIPs were used as filler to prepare a solid phase extraction column for the detection of tetracycline antibiotics residues in milk. It was shown that the tetracycline antibiotics presented a good linear correlation within 0.05-10.0 μg·mL-1 and the recovery rates of tetracyclines were around 79.4%-86.3%, and the relative standard deviations were all less than 3.8%. The detection limits were 0.02 μg·mL-1 for tetracycline and oxytetracycline, and was 0.05 μg·mL-1 for chlortetracycline. The method was accurate, sensitive and specific.
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    Color changes and its kinetics of canned citrus during storage
    ZHOU Jinyun, WANG Chunmiao, ZHANG Jun
    2018, 30(2):  323-329.  DOI: 10.3969/j.issn.1004-1524.2018.02.20
    Abstract ( 522 )   HTML ( 0 )   PDF (897KB) ( 1659 )  
    In order to study the influence of temperature on color change in canned citrus during the storage, contents of vitamin C, carotenoid, amino acid nitrogen, reducing sugar, 5-hydroxymethyl furfural (5-HMF) under different storage temperature were measured. The correlation between 5-HMF and browning index was studied. The kinetic assay of the main material caused browning, the total color difference, and the browning index was investigated. It was shown that the storage temperature had significant (P<0.05) influence on the color of the canned citrus. The contents of 5-HMF, total color difference and browning index increased with the prolonged storage time, while contents of vitamin C, carotenoid, amino acid nitrogen and parameters of L* and a* decreased. The kinetic results demonstrated that the zero-order kinetics model fitted well within the changing tendency of reducing sugar and amino acid nitrogen contents during storage, while the complex kinetic model fitted well within total color difference and browning index.
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    Biosystems Engineering
    Application of NIR spectroscopy for nondestructive qualitative and quantitative analysis of table grapes berries
    ZHANG Linzhong, CAI Xuezhen, FANG Congbing
    2018, 30(2):  330-338.  DOI: 10.3969/j.issn.1004-1524.2018.02.21
    Abstract ( 481 )   HTML ( 2 )   PDF (1546KB) ( 1440 )  
    Ten different varieties of fresh grapes, 3 different mature period and 1 kind of diseased fruit with a total of 188 samples were selected as the research object, and the near infrared spectra of these samples collected by near-infrared spectrometers. Using partial least squares (PLS), the quantitative analysis model with higher credibility by determining the content of total phenol, total sugar, fructose, sucrose and soluble solids. The correlation coefficients of indicators were above 0.90 except minority were between 0.77 and 0.89, and root mean square error were all between 0.022 and 1.410. By combining with principal component analysis in 4 199.20~9 881.46 cm-1 spectral region, the discriminant analysis (DA) model with correctness of 92.11%, 88.89% and 96.15% for variety identification, maturity identification and diseased fruit identification respectively has been established. This study showed that near infrared detection technology can not only be used for quantitative analysis of 5 main inclusions in fresh grape, but also be used for identification of varieties, maturity and diseased fruit of fresh grape.
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    Inversion of maize field leaf area index based on high-resolution remote sensing image
    HUANG Chudi, LU Lei, LIU Yong, LIU Jufeng
    2018, 30(2):  339-349.  DOI: 10.3969/j.issn.1004-1524.2018.02.22
    Abstract ( 502 )   HTML ( 1 )   PDF (3101KB) ( 1447 )  
    According to the field data of maize field plots, the range of input parameters of PROSAIL model was determined. Through the PROSAIL model parameters sensitivity analysis, the different input parameters were determined for setting scheme. We simulated different maize canopy reflectance with different leaf area index, leaf inclination and chlorophyll content, and the tasseled-cap triangle distribution model of leaf area index was established to obtain red-near-infrared band reflectance-LAI look-up table of maize field. The LAI of maize planting area was retrieved by high resolution remote sensing image of WV-3 in Zhongwei City, Ningxia. The applicability of the PROSAIL model in LAI inversion of high resolution remote sensing images was analyzed by comparing with the measured data, which provided a reference for high resolution remote sensing image inversion of crop LAI. The results showed that it was necessary to determine the range of the input parameters and the different setting scheme. The LAI of WV-3 image was consistent with the measured data using the look-up table. The mean square error of the look-up table was 0.47, and the mean square error of simulated LAI was 0.24. This study showed that the methods has strong applicability in maize field LAI inversion using WV-3 remote sensing image, and can be used for accurate and effective leaf area index remote sensing inversion in large area.
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    Review
    Research advances in non-structural protein 2 of porcine reproductive and respiratory syndrome virus
    ZHAO Jun, XU Zhiwen, ZHU Ling
    2018, 30(2):  350-356.  DOI: 10.3969/j.issn.1004-1524.2018.02.23
    Abstract ( 482 )   HTML ( 0 )   PDF (701KB) ( 1348 )  
    Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of porcine reproductive and respiratory syndrome (PRRS). It is an infectious disease that causes complex systemic disease of swine, which most notably affects the respiratory of infected piglets and reproductive systems of infected sows. PRRS causes great economic losses to the swine industry worldwide. The depth study of PRRSV related pathogenic mechanism will lay an important theoretical foundation for the prevention and control of the disease. The non-structural protein 2 (Nsp2) is always the hotspot of these PRRSV studies. This review discussed the correlation between Nsp2 and genetic variations, viral pathogenicity, viral replication, immunological functions, recombinant vaccine and molecular signature. Nsp2 gene played an important role in the differential diagnosis of vaccine strains.
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