• Title/Summary/Keyword: Li Gao

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Molecular and Biochemical Characterization of a Novel Intracellular Low-Temperature-Active Xylanase

  • Zhou, Junpei;Dong, Yanyan;Tang, Xianghua;Li, Junjun;Xu, Bo;Wu, Qian;Gao, Yajie;Pan, Lu;Huang, Zunxi
    • Journal of Microbiology and Biotechnology
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    • v.22 no.4
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    • pp.501-509
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    • 2012
  • A 990 bp full-length gene (xynAHJ2) encoding a 329-residue polypeptide (XynAHJ2) with a calculated mass of 38.4 kDa was cloned from Bacillus sp. HJ2 harbored in a saline soil. XynAHJ2 showed no signal peptide, distinct amino acid stretches of glycoside hydrolase (GH) family 10 intracellular endoxylanases, and the highest amino acid sequence identity of 65.3% with the identified GH 10 intracellular mesophilic endoxylanase iM-KRICT PX1-Ps from Paenibacillus sp. HPL-001 (ACJ06666). The recombinant enzyme (rXynAHJ2) was expressed in Escherichia coli and displayed the typical characteristics of low-temperature-active enzyme (exhibiting optimum activity at $35^{\circ}C$, 62% at $20^{\circ}C$, and 38% at $10^{\circ}C$; thermolability at ${\geq}45^{\circ}C$). Compared with the reported GH 10 low-temperature-active endoxylanases, which are all extracellular, rXynAHJ2 showed low amino acid sequence identities (<45%), low homology (different phylogenetic cluster), and difference of structure (decreased amount of total accessible surface area and exposed nonpolar accessible surface area). Compared with the reported GH 10 intracellular endoxylanases, which are all mesophilic and thermophilic, rXynAHJ2 has decreased numbers of arginine residues and salt bridges, and showed resistance to $Ni^{2+}$, $Ca^{2+}$, or EDTA at 10 mM final concentration. The above mechanism of structural adaptation for low-temperature activity of intracellular endoxylanase rXynAHJ2 is different from that of GH 10 extracellular low-temperature-active endoxylanases. This is the first report of the molecular and biochemical characterizations of a novel intracellular low-temperature-active xylanase.

Interaction of Pseudostellaria heterophylla with Quorum Sensing and Quorum Quenching Bacteria Mediated by Root Exudates in a Consecutive Monoculture System

  • Zhang, Liaoyuan;Guo, Zewang;Gao, Huifang;Peng, Xiaoqian;Li, Yongyu;Sun, Shujing;Lee, Jung-Kul;Lin, Wenxiong
    • Journal of Microbiology and Biotechnology
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    • v.26 no.12
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    • pp.2159-2170
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    • 2016
  • Many plant-pathogenic bacteria are dependent on quorum sensing (QS) to evoke disease. In this study, the population of QS and quorum quenching (QQ) bacteria was analyzed in a consecutive monoculture system of Pseudostellaria heterophylla. The isolated QS strains were identified as Serratia marcescens with SwrIR-type QS system and exhibited a significant increase over the years of monoculture. Only one QQ strain was isolated from newly planted soil sample and was identified as Bacillus thuringiensis, which secreted lactonase to degrade QS signal molecules. Inoculation of S. marcescens to P. heterophylla root could rapidly cause wilt disease, which was alleviated by B. thuringiensis. Furthermore, the expression of lactonase encoded by the aiiA gene in S. marcescens resulted in reduction of its pathogenicity, implying that the toxic effect of S. marcescens on the seedlings was QS-regulated. Meanwhile, excess lactonase in S. marcescens led to reduction in antibacterial substances, exoenzymes, and swarming motility, which might contribute to pathogensis on the seedlings. Root exudates and root tuber extracts of P. heterophylla significantly promoted the growth of S. marcescens, whereas a slight increase of B. thuringiensis was observed in both samples. These results demonstrated that QS-regulated behaviors in S. marcescens mediated by root exudates played an important role in replanting diseases of P. heterophylla.

Rhizosphere Inhibition of Cucumber Fusarium Wilt by Different Surfactinexcreting Strains of Bacillus subtilis

  • Jia, Ke;Gao, Yu-Han;Huang, Xiao-Qin;Guo, Rong-Jun;Li, Shi-Dong
    • The Plant Pathology Journal
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    • v.31 no.2
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    • pp.140-151
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    • 2015
  • Bacillus subtilis B006 strain effectively suppresses the cucumber fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (Foc). The population dynamics of Foc, strain B006 and its surfactin over-producing mutant B841 and surfactin-deficient mutant B1020, in the rhizosphere were determined under greenhouse conditions to elucidate the importance of the lipopeptides excreted by these strains in suppressing Foc. Results showed that B. subtilis strain B006 effectively suppressed the disease in natural soil by 42.9%, five weeks after transplanting, whereas B841 and B1020 suppressed the disease by only 22.6% and 7.1%, respectively. Quantitative PCR assays showed that effective colonization of strain B006 in the rhizosphere suppressed Foc propagation by more than 10 times both in nursery substrate and in field-infected soil. Reduction of Foc population at the cucumber stems in a range of $0.96log_{10}ng/g$ to $2.39log_{10}ng/g$ was attained at the third and the fifth weeks of B006 treatment in nursery substrate. In field-infected soil, all three treatments with B. subtilis suppressed Foc infection, indicated by the reduction of Foc population at a range of $2.91log_{10}ng/g$ to $3.36log_{10}ng/g$ at the stem base, one week after transplanting. This study reveals that the suppression of fusarium wilt disease is affected by the effective colonization of the surfactin-producing B. subtilis strain in the rhizosphere. These results improved our understanding of the biocontrol mechanism of the B. subtilis strain B006 in the natural soil and facilitate its application as biocontrol agent in the field.

DISTRIBUTION CHARACTERISTICS OF NUTRIENTS IN CHINESE BOHAI SEA

  • Li, Zhengyan;Gao, Huiwang;Bai, Jie;Shi, Jinhui
    • Proceedings of the Korean Environmental Health Society Conference
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    • 2001.11a
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    • pp.19-29
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    • 2001
  • Nutrients are key environmental factors in marine ecosystem. They limit algal growth when at low concentrations and cause algal bloom when at high contents. They also control the growth and succession of many other biota including bacteria and zooplankton, either directly or indirectly. Nutrient contents therefore affect both the structure and functions of marine ecosystem. To study the contents and distribution of nutrients in Chinese Bohai Sea, two cruise surveys were undertaken in August 2000 (summer) and January 2001 (winter), respectively. A total of 595 water samples were collected from 91 sites. After collection the samples were transported to the laboratory and five nutrients, i.e., nitrate, nitrite, ammonia, phosphate and silicate, were analyzed. The results showed that tile average concentration of total inorganic nitrogen (TIN) in Bohai Sea in winter (6.5293.717 ${\mu}$mol$.$l$\^$-1/) was significantly higher than that in summer (3.717 ${\mu}$mol$.$l$\^$-1/). The phosphorus concentration in winter (0.660 ${\mu}$mol$.$l$\^$-1/) was also significantly higher than that in summer (0.329 ${\mu}$mol$.$l$\^$-1/). Mean silicate concentration in winter (7.858 ${\mu}$mol$.$l$\^$-1/) was not significantly different from that in summer (7.200 ${\mu}$mol$.$l$\^$-1/). Nutrients also varied considerable among different areas within Bohai Sea. TIN concentration in Laizhou Bay (4.444 ${\mu}$mol$.$l$\^$-1/), for example, was significantly higher than those in Bohai Bay (2.270 ${\mu}$mol$.$l$\^$-1/) and Bohai Straight (2.431 ${\mu}$mol$.$l$\^$-1/), which probably reflects tile discharge of large amounts of nitrogen into Laizhou Bay via Yellow River. The nutrients also showed vertical distribution pattern. In summer, nutrients in bottom layer were generally higher than those in surface and medium layers. In winter, however. nutrients in different layers were not significantly different Compared with historic data, TIN contents increased continuously since early 1980s, phosphorus arid silicone contents, nevertheless, fell down to some degree. Based on atomic ratios of different nutrients, nitrogen is still the main limiting factor for algal growth in Bohai Sea.

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The literatural study of investigating the contents associated with the neuropsychosis in the medical books published in the times of Chinese dynasty of Jin and Yuan (금원시대(金元時代)의 의서(醫書)에 나타난 신경정신질환(神經精神疾患)에 대한 고찰(考察))

  • Choi, Jong Geol;Lee, Sang Ryong
    • Journal of Haehwa Medicine
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    • v.9 no.1
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    • pp.725-743
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    • 2000
  • This study was intended to investigate the contents associated with the neuropsychosis in the medical books published in the times of Chinese dynasty of Jin and Yuan. As a result, the following findings were drawn. 1. As for palpitation from fright and severe palpitation, the medical schools in the times of Chinese Jin and Yuan dynasties viewed their causes as heart-fire, shuiqichengxin, blood vacuity, phlegm and so on and presented a prescription for each cause for them. 2. As for psychosis, medical books published in the times of Chinese Jin and Yuan dynasties accurately divided and discussed epilepsy and viewed their causes largely as Yangming heat, phlegm of chest and heart-fire. And a number of medical schools made use of such therapeutics as sweating, vomiting and diarrhea therapies. 3. As for headache, medical books published in the times of Chinese Jin and Yuan dynasties presented their causes as fire and heat, phlegm heat, phlegm and so on and classified the aspect of headache in detail. As for vacuity rexation and dysphoria, medical books at that time saw their causes as fire and heat, heart-fire, blood vacuity and so forth and presented a prescription for them accordingly. 4. Liu Wan Su was the Hanliang school. He viewed the etiological cause for psychopathy as fire and heat and prescribed largely the medication of cold nature for it. 5. Zhang Cong Zheng belonged to the Gongxia School. He viewed the etiological cause for psychopathy as fire, phlegm and so forth and made use of sweating, vomiting and diarrhea therapies. Especially, he used the 'Jingzhepingzhe' therapy as a method to treat the symptom of fright. 6. Li Gao did not any specific mention of psychopathy and divided headache due to internal injury and headache due to external contraction. 7. Zhu Zhen Heng viewed most of the etiological causes for psychopathy as phlegm, fire and deficiency of blood and attached importance to such its therapeutics as resolving phlegm, cleaning away fire and nourishing Yin. 8. Wang Hao Gu did not present the specifically common etiological cause and prescription for psychopathy but described the cause and prescription for headache, dysphoria, maniac speech, palpitation and so forth. Luo Tian Yi presented the process of psychosis due to abnormal therapy for cold demage and prescription of it. 9. Wang Lu made a detailed explanation about the therapeutics of five types of stagnated syndrome and said that stagnated syndrome became the major cause for them in the occurrence of such psychopathy. Wei Yi Lin presented the prescription and medication for comparatively diverse mental diseases such zhong-qi, severe palpitation, palpitation for fright, impaired memory, vacuity rexation, headache, psychosis.

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The Abanones, Haliotis discus hannai, Exhibit Potential Anticoagulant Activity in Normal Sprague Dawley Rats (정상 Sprague Dawley 쥐에 대한 전복의 항응고능에 관한 효과)

  • Kim, Hag-Lyeol;Kim, Seon-Jae;Kim, Du-Woon;Ma, Seung-Jin;Gao, Tiancheng;Li, Hua;Lee, Tae-Hoon;Kim, In-Cheol;Ham, Kyung-Sik;Kang, Seong-Gook
    • Food Science and Preservation
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    • v.14 no.4
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    • pp.431-437
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    • 2007
  • The primary objective of this study was to determine the effects of abalone in reducing blood pressure and increasing anti-coagulant capacity. The serum angiotensin-converting-enzyme (ACE) activities of rats on an abalone-supplemented diet did not significantly differ from the ACE levels of rats on a normal diet, at any time (before the experiment, or 1 week, 2 weeks, 3 weeks, and 4 weeks, after commencement of the abalone diet) during the experiment. This result showed that abalone-supplemented diets had no effect on the activity of ACE, which controls blood pressure. To determine if an abalone-containing diet might increase anti-coagulant capacity, both prothrombin (PT) and activated partial thromboplastin time (APTT) levels were measured. The PT levels of control rats remained constant throughout the experiment. In rats fed the abalone-containing diet, PT levels increased with time, and the increase became statistically significant after 2 weeks, when compared to pre-trial PT levels. Control rats showed no significant change in APTT levels over time. The rats fed abalone, however, showed significant differences in APTT levels. Specifically, when pre-trial APTT levels were compared with 4-week levels, and when 1-week levels were compared with 4-week levels, the differences attained statistical significance. These results indicate that an abalone-supplemented diet may inhibit blood coagulation in normal rats. The results of this study prove the inherent health value of abalone, and may encourage investment in the seafood industry. Future studies will explore other possible beneficial effects of abalone, apart from the anti-hypertension and anti-coagulant effects examined above.

Modulatory Effect of Four Azulene Derivatives from the Fruiting Bodies of Lactarius hatsudake on Interferon-$\gamma$ Production (젖버섯아재비 자실체로부터 분리한 Azulene계 화합물이 Interferon-$\gamma$ 생성에 미치는 영향)

  • Xu, Guang Hua;Kim, Jae-Wha;Li, Gao;Yoo, Ick-Dong
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.36 no.2
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    • pp.151-156
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    • 2010
  • Investigation of secondary bioactive metabolites from the fruiting bodies of Lactarius hatsudake led to the isolation of four azulene derivatives by means of repeated column chromatography and preparative HPLC, and they were identified as 1-formyl-4-methyl-7-isopropyl azulene (1), lactaroviolin (2), 4-methyl-7-isopropyl-azulene-1-carboxylic acid (3), and 1-formyl-4-methyl-7-(1-hydroxy-1-methylethyl) azulene (4) by their physico-chemical properties and spectroscopic analysis. The isolated compounds were evaluated for the effects on modulation of cytokines in natural killer cell line (NK92 cells). Compounds 1 and 4 strongly inhibited IFN-$\gamma$ production in a dose-dependent manner, corresponding to 101.3 % and 92.7 % inhibition at 400 ${\mu}M$, and 11.9 % and 24.1 % at 100 ${\mu}M$, respectively, whereas compounds 2 and 3 showed weak inhibitory effect on INF-$\gamma$ production, corresponding to 45.9 % and 18.0 % inhibition at 400 ${\mu}M$.

Inhibition Effects of Pulp on Seed Germination of American Ginseng (과육이 서양삼 종자 발아에 미치는 영향)

  • Huang, Yao-Ge;Li, Xiang-Gao;Cui, Shu-Yu;Yang, Ji-Xiang;Liu, Ren-Song;Kim, Hack-Seang
    • Korean Journal of Medicinal Crop Science
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    • v.5 no.2
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    • pp.154-161
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    • 1997
  • The germination inhibitory effects of American ginseng (Panax quinquefolium Linne) pulp were discussed. The germination inhibitory effects of pulp juice were decreased in a concentration dependent manner. When the pulp juice was diluted 0 (original juice), 1, 2, 5, 10, 20, 50 and 100 times, the radicle lengths of the assay plant, Chinese cabbage (Brassica chinensis Linne), showed 0, 0.32, 0.72, 3.13, 4.83, 16.07, 16.73 and 23.50 mm, respectively (CK=25.98 mm). The pulp evidently inhibited the embryo growth in natural fruit. The longer was the duration that the pulp stayed around the seed, the longer was the time course needed for embryo getting free from the inhibitory effects of pulp. When the depulping was performed on the day 0, 15, 30 and 60 after harvest, the time courses needed for embryo extricating the residual inhibitory effects from pulp were 30, 75, 135 and 135 days, respectively. Moreover, if the pulp stayed around the seed with time, that would make the seed rotten ratio increase. When the pulp stayed around the seed for 0, 15, 30, 60 and 270 days, the seed rotten ratios were 5.47, 5.71, 19.05, 27.14 and 33.33%, respectively. Therefore, we concluded that the pulp could be included in the inhibitory components which made American ginseng seed get into dormancy.

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Estrogen promotes the onset and development of idiopathic scoliosis via disproportionate endochondral ossification of the anterior and posterior column in a bipedal rat model

  • Zheng, Shuhui;Zhou, Hang;Gao, Bo;Li, Yongyong;Liao, Zhiheng;Zhou, Taifeng;Lian, Chengjie;Wu, Zizhao;Su, Deying;Wang, Tingting;Su, Peiqiang;Xu, Caixia
    • Experimental and Molecular Medicine
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    • v.50 no.11
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    • pp.3.1-3.11
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    • 2018
  • This study aimed to verify the effects of estrogen on the onset and development of adolescent idiopathic scoliosis and the mechanisms associated with these effects by constructing a pubescent bipedal rat model. Experiments were conducted to investigate whether scoliosis progression was prevented by a Triptorelin treatment. One hundred twenty bipedal rats were divided into female, OVX (ovariectomy), OVX + E2, Triptorelin, sham, and male groups. According to a spinal radiographic analysis, the scoliosis rates and curve severity of the female and OVX + E2 groups were higher than those in the OVX, Triptorelin, and male groups. The measurements obtained from the sagittal plane of thoracic vertebrae CT confirmed a relatively slower growth of the anterior elements and a faster growth of the posterior elements between T11 and T13 in the female and OVX + E2 groups than in the OVX and Triptorelin groups. Histomorphometry and immunohistochemistry revealed a significantly longer hypertrophic zone of the vertebral cartilage growth plates that expressed more type X collagen and less type II collagen in the OVX and Triptorelin groups than in the female and OVX + E2 groups. Ki67 immunostaining confirmed an increase in the proliferation of vertebral growth plate chondrocytes in the OVX group compared with the female and OVX + E2 groups. In conclusion, estrogen obviously increased the incidence of scoliosis and curve severity in pubescent bipedal rats. The underlying mechanism may be a loss of coupling of the endochondral ossification between the anterior and posterior columns. Triptorelin decreased the incidence of scoliosis and curve magnitudes in bipedal female rats.

Chemical composition and in vitro digestibility of corn stover during field exposure and the fermentation characteristics of silage prepared with microbial additives

  • Gao, Jun Lei;Wang, Peng;Zhou, Chang Hai;Li, Ping;Tang, Hong Yu;Zhang, Jia Bao;Cai, Yimin
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.12
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    • pp.1854-1863
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    • 2019
  • Objective: To effectively use corn stover resources as animal feed, we explored the chemical composition and in vitro digestibility of corn stover during field exposure and the fermentation characteristics of silage prepared with lactic acid bacteria (LAB) and cellulase. Methods: Corn ears including the cobs and shucks were harvested at the ripe stage. The corn stover was exposed in the field under natural weather conditions. Silages were prepared after 0, 2, 4, 7, 15, 30, and 60 d of exposure. Corn stover was chopped into approximately 1 to 2 cm lengths and then packed into 5 liter plastic silos. The ensiling density was $550.1{\pm}20.0g/L$ of fresh matter, and the silos were kept at room temperature ($10^{\circ}C$ to $25^{\circ}C$). Silage treatments were designed as follows: without additives (control), with LAB, with cellulase, and with LAB+ cellulase. After 45 d of fermentation, the silos were opened for chemical composition, fermentation quality and in vitro digestion analyses. Results: After harvest, corn stover contained 78.19% moisture, 9.01% crude protein (CP) and 64.54% neutral detergent fiber (NDF) on a dry matter (DM) basis. During field exposure, the DM, NDF, and acid detergent fiber (ADF) contents of corn stover increased, whereas the CP and water-soluble carbohydrate contents and in vitro digestibility of the DM and CP decreased (p<0.05). Compared to the control silage, cellulase-treated silage had lower (p<0.05) NDF and ADF contents. The pH values were lower in silage treated with LAB, cellulase, or LAB+cellulase, and lactic acid contents were higher (p<0.05) than those of the control. Silage treated with cellulase or LAB+cellulase improved (p<0.05) the in vitro DM digestibility (IVDMD) compared to that of the control or LAB-treated silage. Conclusion: Corn stover silage should be prepared using fresh materials since stover nutrients are lost during field exposure, and LAB and cellulase can improve silage fermentation and IVDMD.