Zhang W.J.,Chinese Academy of Agricultural Sciences |
Wang X.J.,Xinjiang Institute of Ecology and Geography |
Wang X.J.,The Interdisciplinary Center |
Xu M.G.,Chinese Academy of Agricultural Sciences |
And 3 more authors.
Biogeosciences | Year: 2010
Soil carbon sequestration is a complex process influenced by agricultural practices, climate and soil conditions. This paper reports a study of long-term fertilization impacts on soil organic carbon (SOC) dynamic from six long-term experiments. The experiment sites are located from warm-temperate zone with a double-cropping system of corn (Zea mays L.) - wheat (Triticum Aestivium L.) rotation, to mild-temperate zones with mono-cropping systems of continuous corn, or a three-year rotation of corn-wheat-wheat. Mineral fertilizer applications result in an increasing trend in SOC except in the arid and semi-arid areas with the mono-cropping systems. Additional manure application is important to maintain SOC level in the arid and semi-arid areas. Carbon conversion rate is significant lower in the warm-temperate zone with double cropping system (6.8%-7.7%) than that in the mild-temperate areas with mono-cropping systems (15.8%-31.0%). The conversion rate is significantly correlated with annual precipitation and active accumulative temperature, i.e., higher conversion rate under lower precipitation and/or temperature conditions. Moreover, soil high in clay content has higher conversion rate than soils low in clay content. Soil carbon sequestration rate ranges from 0.07 to 1.461 t ha-1 year -1 in the upland of northern China. There is significantly linear correlation between soil carbon sequestration and carbon input at most sites, indicating that these soils are not carbon-saturated thus have potential to migrate more CO2 from atmosphere.
Jiang P.-X.,Tsinghua University |
Wang H.-S.,University of Chinese Academy of Sciences |
Zhang C.,Tsinghua University |
Lou K.,Xinjiang Academy of Agricultural science |
Xing X.-H.,Tsinghua University
Applied Microbiology and Biotechnology | Year: 2010
Violacein is a bacteria-originated indolocarbazole pigment with potential applications due to its various bioactivities such as anti-tumor, antiviral, and antifungal activities. However, stable mass production of this pigment is difficult due to its low productivities and the instability of wild-type violacein-producing strains. In order to establish a stable and efficient production system for violacein, the violacein synthesis pathway from a new species of Duganella sp. B2 was reconstructed in different bacterial strains including Escherichia coli, Citrobacter freundii, and Enterobacter aerogenes by using different vectors. The gene cluster that encodes five enzymes involved in the violacein biosynthetic pathway was first isolated from Duganella sp. B2, and three recombinant expression vectors were constructed using the T7 promoter or the alkane-responsive promoter PalkB. Our results showed that violacein could be stably synthesized in E. coli, C. freundii, and E. aerogenes. Interestingly, we found that there were great differences between the different recombinant strains, not only in the protein expression profiles pertaining to violacein biosynthesis but also in the productivity and composition of crude violacein. Among the host strains tested, the crude violacein production by the recombinant C. freundii strain reached 1.68 g L-1 in shake flask cultures, which was 4-fold higher than the highest production previously reported in flask culture by other groups. To the best of our knowledge, this is the first report on the efficient production of violacein by genetically engineered strains. © 2009 Springer-Verlag.
Zhang W.,Xinjiang Normal University |
Zhang W.,Xinjiang Academy of Agricultural science |
Chen Y.,Xinjiang Academy of Agricultural science
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014
Long-term continuous cropping of cotton has caused dramatic soil-borne diseases in many places, leading to substantial agricultural losses. However, in some areas of Xingjang Province, the obstacles caused by continuous cotton cropping can spontaneously restore and maintain high yields of cotton for many years. To analyze the variable spectrum of soil bacterial communities and changes in the community structure in these spontaneously restored fields during cropping, soils at depths from 1 to 30 cm were sampled from cotton fields with a history of 0, 1, 3, 5, 10, 15 or 20 years of cotton cropping in the Akesu region of Xinjiang Province. The bacterial communities in these samples were studied using 16S rRNA-based polymerase chain reaction-density gradient gel electrophoresis (PCR-DGGE) with samples from uncultivated land as a control. Bacterial community diversity indices including the Shannon-Wiener diversity (H), Abundance index (S) and Evenness index (EH) were compared among these samples. Samples from uncultivated land had relatively high levels of the richness indices but both the Diversity and Evenness Indices were at lower levels. With increasing years of cotton cropping, both the bacterial Diversity and Evenness Indices increased, whereas the richness indices showed a general decrease. However, after 10 years of continuous cropping all these indices were restored to their original values or reached a relative stable level. Cluster analysis of DGGE fragments indicated that the seven samples were clustered into three branches: fragments from samples under successional cropping for 0, 10 and 20 years formed one small branch with a similarity of approximately 50%; fragments from successional cropping for 1, 5 and 15 years formed another branch with a similarity of 53%; and the last branch comprised fragments from successional cropping for 3 years with a similarity of 44%. Principal component analysis (PCA) showed that all of the samples were statistically correlated with the major component and fluctuated on the right of the major component between the positive and negative axes of the second principal component. Both cluster analysis and PCA results suggested that, compared to those from original uncropped fields, the bacterial community structure showed the most variation in samples from the field of 3-year cropping, whereas similar patterns of bacterial community structure were found between samples from fields of 10 years of cotton cropping and those from uncropped fields. Nineteen clones were sequenced from each band and among them one sequence was selected and submitted to GenBank (accessory no. JN572545-JN572563). By aligning with the GenBank database, all sequences from DGGE were classified into four groups: Microbacterium, Uncultured Chloroflexi bacterium, TM7 Phylum sp. canine, and Flavobacteria. Further analysis demonstrated that the isolated V3 sequences showed a homology of 88%—100% to known sequences in GenBank and 47% of the sequences belonged to bacteria which were not cultured. No microbial data were correlated with soil-borne plant diseases of cotton. The study demonstrated that the age of cotton fields had significant effects on soil bacterial diversity. Continuous cotton cropping exerted significant influences on the community structure of soil bacteria in Xinjiang Province, with an initial suppression effect on bacterial diversity. However, the bacterial community reached a stabilized or even increased level compared with its original state after 5 years of continuous cropping. In addition, correlations between variations in the bacterial community structure at a depth of 1—30 cm and the yield of cotton and pest disease attacks were also found in this study. © 2014, Science Press. All rights reserved.
Li S.,Huanggang Normal University |
Li S.,Rutgers University |
Wang H.,Shaklee Corp. |
Guo L.,Xinjiang Academy of Agricultural science |
And 2 more authors.
Journal of Functional Foods | Year: 2014
The studies of nobiletin and other polymethoxyflavones from citrus peels become prevalent in recent years due to many well-established evidences showing their multiple efficacious biological activities. The biotransformation study of polymethoxyflavones, particularly nobiletin has emerged along with the significant findings of nobiletin bioactivity. Major nobiletin metabolites from rodent biofluids have been successfully characterized, isolated or synthesized for the evaluation of their biological activities and subsequently revealed that nobiletin metabolites demonstrate similar efficacies or more potent anti-oxidant activity and scavenging property against free radicals and in the inhibition of inflammation and cancer growth, and the prevention of metabolic syndrome and cardiovascular diseases. This review starts with basic chemistry of nobiletin and other polymethoxyflavones, highlights their biological properties and recent findings and summarizes nobiletin's biotransformation and biological activities of the main nobiletin metabolites. © 2013 Elsevier Ltd.
Meng Q.-W.,Nanjing Agricultural University |
Liu X.-P.,Nanjing Agricultural University |
Lu F.-G.,Nanjing Agricultural University |
Fu K.-Y.,Nanjing Agricultural University |
And 2 more authors.
Gene | Year: 2015
Juvenile hormone III (JH III) plays primary roles in regulation of metamorphosis, reproduction and diapause in Leptinotarsa decemlineata, a notorious defoliator of potato. The neurosecretory cell-borne substance(s) negatively affects the final two steps in JH biosynthesis, catalyzed respectively by an epoxidase CYP15A1 and a juvenile hormone acid methyltransferase (JHAMT). In a few insect species other than L. decemlineata, the inhibitory substance is allatostatin (AS) neuropeptide. In this study, two putative AS genes encoding LdAS-C and LdAS-B precursors were cloned. Both LdAS-. C and LdAS-. B were expressed in the egg, larvae, pupae and adults, and highly expressed in the brain and the gut. Dietary introduction of double-stranded RNAs (dsRNAs) targeting LdAS-. C and LdAS-. B successfully knocked down respective target genes. Ingestion during 3 and 6 consecutive days of ds. LdAS-. C significantly increased the LdJHAMT mRNA levels by 3.8 and 9.9 fold respectively. In contrast, ingestion of ds. LdAS-. B only slightly increased the LdJHAMT expression level by 1.1 and 1.7 fold. Moreover, after one, two and three days' ingestion of ds. LdAS-. C, the relative JH levels in the hemolymph of treated larvae were 2.5, 4.2 and 1.9 fold higher than those in control beetles. Furthermore, ingestion of ds. LdAS-. C and ds. LdAS-. B significantly affected larval growth and delayed larval development. Thus, we provide a line of experimental evidence in L. decemlineata to support the concept that AS-C acts as an allatostatin and inhibit JH biosynthesis. © 2014.
Zhou L.-T.,Nanjing Agricultural University |
Jia S.,Nanjing Agricultural University |
Wan P.-J.,Nanjing Agricultural University |
Kong Y.,Nanjing Agricultural University |
And 3 more authors.
Journal of Insect Physiology | Year: 2013
In JH biosynthetic pathway in insect corpora allata, methylation of farnesoic acid or JH acid using S-adenosyl- L-methionine generates a potent feedback inhibitor S-adenosyl- L-homocysteine (AdoHcy). Rapid removal of AdoHcy is hypothesized to be essential for JH synthesis. AdoHcy hydrolase (SAHase) is the only eukaryotic enzyme catalyzing the removal. In the present paper, we firstly cloned a putative LdSAHase gene from L. decemlineata. The cDNA consists of 1806. bp and encodes a 525 amino acid protein. LdSAHase was expressed in all developmental stages. The gene had the highest and the lowest level of transcription respectively in the 3rd- and 4th-instars' heads that contain corpora allata, which was positively correlated with JH titer in the haemolymph and the mRNA level of a JH early-inducible gene, the Krüppel homolog 1 gene ( Kr-h1). Secondly, dietary ingestion of bacterially-expressed LdSAHase-dsRNA significantly decreased LdSAHase and LdKr-h1 mRNA levels, reduced JH titer, and caused the death of the larvae, and the failure of pupation and adult emergence. After continuous exposure for 12. days, 42% of the larvae died, 65% of the prepupae failed to pupate and 100% of the pupae failed to emerge. Moreover, RNAi-mediated LdSAHase knockdown also reduced larval developing time, and decreased larval weight. Lastly, application of JH analogue pyriproxyfen to LdSAHase-dsRNA-exposed larvae did not greatly increase LdSAHase expression level and JH content, but up-regulated LdKr-h1 mRNA level. Expectedly, pyriproxyfen application could partially rescue the negative effects on the survival and the development. Thus, our results support the hypothesis that SAHase plays a critical role in JH biosynthesis in insects. © 2013 Elsevier Ltd.
Jiang W.-H.,Nanjing Agricultural University |
Lu W.-P.,Nanjing Agricultural University |
Guo W.-C.,Xinjiang Academy of Agricultural science |
Xia Z.-H.,Station of Agricultural Techniques Extension in Yili |
And 2 more authors.
Journal of Economic Entomology | Year: 2012
The Colorado potato beetle (Leptinotarsa decemlineata (Say)) in the north Xinjiang Uygur autonomous region has evolved resistance to various types of insecticides. Chlorantraniliprole is a novel anthranilic diamide insecticide that binds and activates ryanodine receptors. It exhibited excellent efficacy against L. decemlineata in several field trails in Europe. In the present paper, the susceptibility of L. decemlineata fourth-instar larvae derived from six field populations and L. decemlineata adults derived from three field populations to chlorantraniliprole was determined by a topical application. The fourth-instar larvae were substantially more susceptible to chlorantraniliprole than adults, although the range of susceptibility was far greater among the fourth-instar larvae. Regarding stomach toxicities, adult beetles were less susceptible to chlorantraniliprole than larvae. Chlorantraniliprole was most toxic to second-instar larvae, followed by third-and fourth-instar larvae. These data suggested that the appropriate timing for chlorantraniliprole spraying is the early larval stage. More-over, the synergistic activities of chlorantraniliprole in combination with triphenyl phosphate, diethyl maleate, or piperonyl butoxide against fourth-instar larvae from two field populations and adults from one field population were tested. Piperonyl butoxide had synergistic effects with chlorantraniliprole against fourth-instar larvae but not against adult beetles. Conversely, triphenyl phosphate and diethyl maleate exerted little synergistic effects. It appears that there is a potential risk of resistance against chlorantraniliprole resulting from cytochrome P450 monooxygenase activity. © 2012 Entomological Society of America.
Das P.,CAS Institute of Microbiology |
Yang X.-P.,Xinjiang Academy of Agricultural science |
Ma L.Z.,CAS Institute of Microbiology
Frontiers in Microbiology | Year: 2014
Rhamnolipid biosurfactants produced mainly by Pseudomonas sp. had been reported to possess a wide range of potential industrial application. These biosurfactants are produced as monorhamnolipid (MRL) and di-rhamnolipid (DRL) congeners. The present study deals with rhamnolipid biosurfactants produced by three bacterial isolates from crude oil. Biosurfactants produced by one of the strains (named as IMP67) was found to be very efficacious based on its critical micelle concentration value and hydrocarbon emulsification property. Strikingly, antimicrobial, and anti-biofilm potential of this biosurfactant were higher than biosurfactants produced by other two strains. Thin layer chromatography analysis and rhamnose quantification showed that the rhamnolipids of IMP67 had more MRL congeners than biosurfactants of the other two strains. Emulsification and antimicrobial actions were affected by manual change of MRL and DRL congener proportions. Increase of MRL proportion enhanced emulsification index and antimicrobial property to Gram negative bacteria. This result indicated that the ratio of MRL and DRL affected the emulsification potentials of rhamnolipids, and suggested that high emulsification potentials might enhance rhamnolipids to penetrate the cell wall of Gram negative bacteria. In line with this finding, rhamnolipids of IMP67 also reduced the MIC of some antibiotics against bacteria, suggesting their synergistic role with the antibiotics. © 2014 Das, Yang and Ma.
Shi Y.,Xinjiang Academy of Agricultural science
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012
The aim of this study was to investigate the composition and distribution variation of endophytic bacteria and fungi in Achnatherum inebrians. The DNA of seed, leaf, stem and root was extracted with liquid nitrogen grinding method. Then, 16S rDNA and Internally Transcribed Spacer (ITS) sequence were digested with restriction enzymes Hha I , Rsa I and Hhae III, Hinf I to obtain terminal restriction fragments. The terminal restriction fragments were matched to bacterial and fungal genera by the T-RFLP Analysis Program, and the community component and similarity of endophyte in Achnatherum inebrians were analyzed. The diversity of endophytic bacteria and fungi was the most abundant in root and seed of Achnatherum inebrians. All the predominant bacterial population was Bacillus (above 29%) in different organs of Achnatherum inebrians. The predominant fungal population was Mycosphaerella (6.5%), Teratosphaeria (4.5%), Fragum (1.1%), Sebacina (11.3%) in seed, leaf, stem and root, respectively. The structure of the bacterial communities in the stem and leaf were similar, whereas the structure of the bacterial communities in the seed and other tissue were different. The structure of the fungi communities in the stem and seed were similar, whereas the structure of the fungi communities in the leaf and other tissue were different. There was abundant endophytic microbial diversity in Achnatherum inebrians.
Qin X.-Z.,Xinjiang Academy of Agricultural science
Chinese Journal of Biologicals | Year: 2013
Objective: To optimize the condition for fermentation of recombinant Cl02 strain producing cold-adapted lipase by response surface methodology (RSM). Methods: The effects of content of yeast as nitrogen source, pH value as well as glycerol and methanol contents in medium on enzyme activity were investigated by single-factor test, based on which the main influencing factors of enzyme production were determined. The effects of various factors on activity of cold-adapted lipase were evaluated by RSM of three factors at four levels according to Box-Benheken center combination test design principles, based on which a multivariate quadratic regression model was established. Results: The content of yeast as nitrogen source, pH value and methanol content in medium showed significant effect on enzyme activity. The optimal content of yeast as nitrogen, pH value and methanol content for production of cold-adapted lipase were 7.3 g/L, 6.0 and 9.1 g/L respectively. Under the optimal condition, the activity of cold-adapted lipase was 42.25 IU/ml, which increased by 50.9% as compared with that before optimization (28.0 IU/ml). Conclusion: The optimization of fermentation condition by RSM increased the cold-adapted lipase-producing ability of recombinant strain significantly, which laid a foundation of industrial production of the enzyme.