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Guo Z.-Y.,China Agricultural University | Kong C.-H.,China Agricultural University | Wang J.-G.,China Agricultural University | Wang Y.-F.,Heilongjiang Academy of Agricultural science
Soil Biology and Biochemistry

Despite an increase in the understanding of the soybean isoflavones involved in root-colonizing symbioses, relatively little is known about their levels in the rhizosphere and their interactions with the soil microbial community. Based on a 13-year experiment of continuous soybean monocultures, in the present study we quantified isoflavones in the soybean rhizosphere and analyzed the soil microbial community structure by examining its phospholipid fatty acid (PLFA) profile. Two isoflavones, daidzein (7, 4'-dihydroxyisoflavone) and genistein (5,7,4'- trihydroxyisoflavone), were detected in the rhizosphere soil of soybean plants, with the concentrations in the field varying with duration of mono-cropping. Genistein concentrations ranged from 0.4 to 1.2 μg g-1 dry soil over different years, while daidzein concentrations rarely exceeded 0.6 μg g-1 dry soil. PLFA profiling showed that the signature lipid biomarkers of bacteria and fungi varied throughout the years of the study, particularly in mono-cropping year 2, and mono-cropping years 6-8. Principal component analysis clearly identified differences in the composition of PLFA during different years under mono-cropping. There was a positive correlation between the daidzein concentrations and soil fungi, whereas the genistein concentration showed a correlation with the total PLFA, fungi, bacteria, Gram (+) bacteria and aerobic bacteria in the soil microbial community. Both isoflavones were easily degraded in soil, resulting in short half-lives. Concentrations as small as 1 μg g-1 dry soil were sufficient to elicit changes in microbial community structure. A discriminant analysis of PLFA patterns showed that changes in microbial community structures were induced by both the addition of daidzein or genistein and incubation time. We conclude that daidzein and genistein released into the soybean rhizosphere may act as allelochemicals in the interactions between root and soil microbial community in a long-term mono-cropped soybean field. © 2011 Elsevier Ltd. Source

Sun X.D.,Heilongjiang Academy of Agricultural science
International Journal of Food Science and Technology

Soy proteins are very important protein source for human being and livestock. Enzymatic hydrolysis of soy protein can enhance or reduce its functional properties and improve its nutritious value. Soy protein hydrolysates were primarily used as functional food ingredients, flavour and nutritious enhancers, protein substitute, and clinical products. Conditions for hydrolysis were usually mild, whereas recently high pressure treatment attracted more interest. Degree of hydrolysis (DH) was usually between 1% and 39.5%. The main problem associated with proteolytic hydrolysis of soy protein was production of bitter taste, hydrolysates coagulation and high cost of enzymes. Bitterness reduction can be achieved by control of DH, selective separation of bitter peptides from hydrolysates, treatment of hydrolysates with exo-peptidases, addition of various components [adenosine monophosphate (AMP), some amino acids, monosodium glutamate (MSG), etc.] to block or mask the bitter taste, and modification of taste signalling. Hydrolysates coagulation can be resolved by selecting appropriate enzymes and by applying immobilisation technology the production cost can be reduced. Enzymatic hydrolysis also enhances bioactivity of soy proteins through conversion of glycosides to aglycones, increasing antioxidant and immunoregulatory properties. Finally, future works have been discussed. © 2011 The Author. International Journal of Food Science and Technology © 2011 Institute of Food Science and Technology. Source

Han G.,Heilongjiang Academy of Agricultural science
Acta Agriculturae Scandinavica Section B: Soil and Plant Science

Modernization and effective management in modern Chinese agriculture are the key of future success in Chinese agriculture development and food production. Based on an analysis of the agriculture structure and adaptation of the industrial management experiences in China, this review addresses how to achieve an effective and dynamic management in agriculture in the future. Chinese agriculture is in the process being transformed from individual, small, family-based farmers to cooperate-based large-scale farmers with modern agriculture machinery. To permit a smooth advancement and transition of Chinese agriculture from primitive traditional agriculture to a modern and machine-based agriculture as well as to enhance the agricultural productivity when total area of arable land is declining, a dynamic and sufficient management is the basis. However, there are a number of challenges and limitations: (1) Chinese farmers have in general limited education, (2) the small family-based agriculture tradition and structure, (3) the lack of experience in agriculture and innovation, and (4) short-term profit-based mentality. This review will discuss those challenges and propose corresponding solutions to assure the successful agricultural development in China by effective and dynamic management. © 2014 Taylor & Francis. Source

Yang X.,Northeast Agricultural University | Li H.,Northeast Agricultural University | Guan Q.,Northeast Agricultural University | Liu D.,Heilongjiang Academy of Agricultural science
Genetics and Molecular Biology

The Toll-like receptor 5 (TLR5) recognizes flagellin of Gram-positive and -negative bacteria and plays an important role in the host defense system. Here, we surveyed single nucleotide polymorphisms (SNPs) in the coding sequence of the porcine TLR5 gene in 83 individuals from five pig breeds, these including Chinese local populations and Western commercial pig breeds. A total of 19 medium polymorphic SNPs (0.25 < PIC < 0.5) were identified, three of which were missense mutations that clustered within the extracellular domain of TLR5. One of the non-synonymous SNPs fell within a 228-amino acid region which has been shown to be important for flagellin recognition. Four SNPs were only found with high frequencies in Oriental pig breeds. The 19 SNPs were found in 30 haplotypes, one of which segregated at high frequency in all samples. Compared with Western pig breeds, Chinese local populations had higher genetic diversity and more haplotypes. Tajima's test showed no evidence for deviation from neutrality. The data provide useful information for future genetic marker characterization by means of disease association analysis and/or stimulating the mutation carrier with relevant ligands. © 2013, Sociedade Brasileira de Genética. Printed in Brazil. Source

Zhang Y.,University of Notre Dame | Zhang Y.,Heilongjiang Academy of Agricultural science | Mayfield J.A.,University of Notre Dame | Ploplis V.A.,University of Notre Dame | Castellino F.J.,University of Notre Dame
Biochemical and Biophysical Research Communications

Cluster 2b streptokinase (SK2b), secreted by invasive skin-trophic strains of Streptococcus pyogenes (GAS), is a human plasminogen (hPg) activator that optimally functions when human plasma hPg is bound, via its kringle-2 domain, to cognizant bacterial cells through the a1a2 domain of the major cellular hPg receptor, Plasminogen-binding group A streptococcal M-like protein (PAM). Another class of streptokinases (SK1), secreted primarily by GAS strains that possess affinity for pharyngeal infections, does not require PAM-bound hPg for optimal activity. We find herein that replacement of the central β-domain of SK2b with the same module from SK1 reduces the dependency of SK2b on PAM, and the converse is true when the β-domain of SK1 is replaced with this same region of SK2b. These data suggest that simple evolutionary shuttling of protein domains in GAS can be employed by GAS to rapidly generate strains that differ in tissue tropism and invasive capability and allow the bacteria to survive different challenges by the host. © 2014 Elsevier Inc. All rights reserved. Source

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