Latest Issue
Issue 7 ， 2008
-
Magnaporthe oryzae MTP1 gene encodes a type III transmembrane protein involved in conidiation and conidial germinationAbstract：In this study the MTP1 gene, encoding a type III integral transmembrane protein, was isolated from the rice blast fungus Magnaporthe oryzae. The Mtp1 protein is 520 amino acids long and is comparable to the Ytp1 protein of Saccharomyces cerevisiae with 46% sequence similarity. Prediction programs and MTP1-GFP (green fluorescent protein) fusion expression results indicate that Mtp1 is a protein located at several membranes in the cytoplasm. The functions of the MTP1 gene in the growth and development of the fungus were studied using an MTP1 gene knockout mutant. The MTP1 gene was primarily expressed at the hyphal and conidial stages and is necessary for conidiation and conidial germination, but is not required for pathogenicity. The Δmtp1 mutant grew more efficiently than the wild type strain on non-fermentable carbon sources, implying that the MTP1 gene has a unique role in respiratory growth and carbon source use.Keywords：Magnaporthe oryzae;Magnaporthe grisea;MTP1;cDNA;Gene knockout;Conidial germination- 39
- |
- 0
- |
- 0
Published：2022-01-05 -
Induction of nucleoside phosphorylase in
Enterobacter aerogenes and enzymatic synthesis of adenine arabinosideAbstract：Nucleoside phosphorylases (NPases) were found to be induced in Enterobacter aerogenes DGO-04, and cytidine and cytidine 5′-monophosphate (CMP) were the best inducers. Five mmol/L to fifteen mmol/L cytidine or CMP could distinctly increase the activities of purine nucleoside phosphorylase (PNPase), uridine phosphorylase (UPase) and thymidine phosphorylase (TPase) when they were added into medium from 0 to 8 h. In the process of enzymatic synthesis of adenine arabinoside from adenine and uracil arabinoside with wet cells of Enterobacter aerogenes DGO-04 induced by cytidine or CMP, the reaction time could be shortened from 36 to 6 h. After enzymatic reaction the activity of NPase in the cells induced remained higher than that in the cells uninduced.Keywords：Nucleoside phosphorylase (NPase);Enterobacter aerogenes;Cytidine;Cytidine 5′-monophosphate (CMP);Adenine arabinoside- 128
- |
- 0
- |
- 0
Published：2022-01-05 -
Construction of recombinant industrial
Saccharomyces cerevisiae strain withbglS gene insertion intoPEP4 locus by homologous recombinationAbstract：The bglS gene encoding endo-l,3-1,4-β-glucanase from Bacillus subtilis was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone α-factor (MFα1S), and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction (PCR)-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae (SC-βG) was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A (PrA) activity was measured in fermenting liquor. The results of PCR analysis of genome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-l,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-l,3-1,4-β-glucanase expression level with the maximum of 69.3 U/(h·ml) after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-l,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.Keywords：Endo-l,3-1,4-β-glucanase (bglS);Gene replacement;Homologous recombination;Bacillus subtilis;PEP4 gene;Saccharomyces cerevisiae- 130
- |
- 0
- |
- 0
Published：2022-01-05 -
Expression, purification and characterization of a
phyAm -phyCs fusion phytaseAbstract：The phyAm gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichia pastoris in order to expand the pH profile of phytase and decrease the cost of production. The fusion phytase phyAm-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is (25.4±0.53) U/ml at the flask scale and (159.1±2.92) U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 °C and an optimal pH at 5.5~6.0 and its relative activity remains at a relatively high level of above 70% in the range of pH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 °C to 95 °C for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis). After deglycosylation by endoglycosidase H (EndoHf), the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those of phyCs and phyAm.Keywords：Expression;PhyAm;PhyCs;Fusion phytase;Pichia pastoris- 14
- |
- 0
- |
- 0
Published：2022-01-05 -
Physicochemical characteristics of various milk samples available in Pakistan
Abstract：We report physicochemical characteristics of various kinds of liquid milk commercially available in Pakistan in comparison with those of fresh natural milk from animals. Milk samples were collected from local markets at Peshawar, Pakistan, and analyzed for their physical features, including moisture, total solids, specific gravity, conductivity, viscosity and titratable acidity (lactic acid equivalent), and chemical components and macro-minerals, including total protein, casein, lactose, ash and minerals (Na, K and Mg). These items were compared with the physicochemical characteristics of the fresh natural milk samples from buffalo, cow and goat. The results were also compared with reported nutritional quality of milk from various countries and World Health Organization (WHO) standards. We found that all the physical features and chemical components of commercially available milk in Pakistan markets meet WHO’s requirements, except for Na, K, Ca and Mg, which are below the standards.Keywords：Milk;Physicochemical characteristics;Pakistan- 83
- |
- 0
- |
- 0
Published：2021-12-30 -
Application of NIR spectroscopy for firmness evaluation of peaches
Abstract：The use of near infrared (NIR) spectroscopy was proved to be a useful tool for quality analysis of fruits. A bifurcated fiber type NIR spectrometer, with a detection range of 800~2500 nm by InGaAs detector, was used to evaluate the firmness of peaches. Anisotropy of NIR spectra and firmness of peaches in relation to detecting positions of different parts (including three latitudes and three longitudes) were investigated. Both spectra absorbency and firmness of peach were influenced by longitudes (i, ii, iii) and latitudes (A, B, C). For modeling, two thirds of the samples were used as the calibration set and the remaining one third were used as the validation or prediction set. Partial least square regression (PLSR) models for different longitude and latitude spectra and for the whole fruit show that collecting several NIR spectra from different longitudes and latitudes of a fruit for NIR calibration modeling can improve the modeling performance. In addition, proper spectra pretreatments like scattering correction or derivative also can enhance the modeling performance. The best results obtained in this study were from the holistic model with multiplicative scattering correction (MSC) pretreatment, with correlation coefficient of cross-validation rcv=0.864, root mean square error of cross-validation RMSECV=6.71 N, correlation coefficient of calibration r=0.948, root mean square error of calibration RMSEC=4.21 N and root mean square error of prediction RMSEP=5.42 N. The results of this study are useful for further research and application that when applying NIR spectroscopy for objectives with anisotropic differences, spectra and quality indices are necessarily measured from several parts of each object to improve the modeling performance.Keywords：Near infrared (NIR);Anisotropy;Peach;Firmness;Partial least square regression (PLSR)- 14
- |
- 0
- |
- 0
Published：2022-01-05 -
Improvement of xylanase production by
Aspergillus niger XY-1 using response surface methodology for optimizing the medium compositionAbstract：Objective:To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF).Methods:Statistical methodology including the Plackett-Burman design (PBD) and the central composite design (CCD) was employed to investigate the individual crucial component of the medium that significantly affected the enzyme yield.Results:Firstly, NaNO3, yeast extract, urea, Na2CO3, MgSO4, peptone and (NH4)2SO4 were screened as the significant factors positively affecting the xylanase production by PBD. Secondly, by valuating the nitrogen sources effect, urea was proved to be the most effective and economic nitrogen source for xylanase production and used for further optimization. Finally, the CCD and response surface methodology (RSM) were applied to determine the optimal concentration of each significant variable, which included urea, Na2CO3 and MgSO4. Subsequently a second-order polynomial was determined by multiple regression analysis. The optimum values of the critical components for maximum xylanase production were obtained as follows: x1 (urea)=0.163 (41.63 g/L), x2 (Na2CO3)=−1.68 (2.64 g/L), x3 (MgSO4)=1.338 (10.68 g/L) and the predicted xylanase value was 14374.6 U/g dry substrate. Using the optimized condition, xylanase production by Aspergillus niger XY-1 after 48 h fermentation reached 14637 U/g dry substrate with wheat bran in the shake flask.Conclusion:By using PBD and CCD, we obtained the optimal composition for xylanase production by Aspergillus niger XY-1 in SSF, and the results of no additional expensive medium and shortened fermentation time for higher xylanase production show the potential for industrial utilization.Keywords：Xylanase;Optimization of medium composition;Plackett-Burman design (PBD);Central composite design (CCD);Response surface methodology (RSM);Aspergillus niger XY-1- 12
- |
- 0
- |
- 0
Published：2022-01-05 -
Attenuating effect of daidzein on polychlorinated biphenyls-induced oxidative toxicity in mouse testicular cells
Abstract：The attenuating effect of daidzein (DAI) on oxidative toxicity induced by Aroclor 1254 (A1254) was investigated in mouse testicular cells. Cells were exposed to A1254 alone or with DAI. The oxidative damage was estimated by measuring malondialdehyde (MDA) formation, superoxide dismutase (SOD) activity and glutathione (GSH) content. Results show that A1254 induced a decrease of germ cell number, an elevation in thiobarbituric acid reactive substances (TBARS) but a decrease in SOD activity and GSH content. However, simultaneous supplementation with DAI decreased TBARS level and increased SOD activity and GSH content. Consequently, dietary DAI may restore the intracellular antioxidant system to attenuate the oxidative toxicity of A1254 in testicular cells.Keywords：Daidzein (DAI);Polychlorinated biphenyl (PCB);Oxidative damage;Germ cell- 15
- |
- 0
- |
- 0
Published：2022-01-05 -
Do rice water weevils and rice stem borers compete when sharing a host plant?
Abstract：The rice water weevil (RWW) Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is an invasive insect pest of rice Oryza sativa L. in China. Little is known about the interactions of this weevil with indigenous herbivores. In the present study, adult feeding and population density of the weevil, injury level of striped stem borer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) to rice, as well as growth status of their host plants were surveyed in a rice field located in Southeastern Zhejiang, China, in 2004 with the objective to discover interspecific interactions on the rice. At tillering stage, both adult feeding of the weevil and injury of the stem borers tended to occur on larger tillers (bearing 5 leaves) compared with small tillers (bearing 2~4 leaves), but the insects showed no evident competition with each other. At booting stage, the stem borers caused more withering/dead hearts and the weevil reached a higher density on the plants which had more productive tillers and larger root system; the number of weevils per tiller correlated negatively with the percentage of withering/dead hearts of plants in a hill. These observations indicate that interspecific interactions exist between the rice water weevil and the rice stem borers with negative relations occurring at booting or earlier developmental stages of rice.Keywords：Chilo suppressalis;Interspecific interaction;Lissorhoptrus oryzophilus;Sesamia inferens;Stem borer;Weevil- 14
- |
- 0
- |
- 0
Published：2022-01-05 -
White-spot disease of Chinese soft-shelled turtles (
Trionyx sinens ) caused byPaecilomyces lilacinus Abstract：Chinese soft-shelled turtles (Trionyx sinens) in culture farms using an artificial warming system in Zhejiang, China, often show typical signs of white-spot disease such as white spots on their bodies, skin lesions, anorexia and eventually death. The sick turtles were mostly 5~80 g in weight. A suspected fungal pathogen was isolated from the sick turtles and verified as Paecilomyces lilacinus by sequence analysis of the internal transcribed spacer (ITS) of its ribosomal DNA (rDNA). Detailed morphological examinations were also conducted to confirm the white-spot disease.Keywords：White-spot disease;Chinese soft-shelled turtles;Paecilomyces lilacinus;Zhejiang- 14
- |
- 0
- |
- 0
Published：2022-01-05
Biotechnology and Biochemistry
-
On indexing in the Web of Science and predicting journal impact factor
Abstract：We discuss what document types account for the calculation of the journal impact factor (JIF) as published in the Journal Citation Reports (JCR). Based on a brief review of articles discussing how to predict JIFs and taking data differences between the Web of Science (WoS) and the JCR into account, we make our own predictions. Using data by cited-reference searching for Thomson Scientific’s WoS, we predict 2007 impact factors (IFs) for several journals, such as Nature, Science, Learned Publishing and some Library and Information Sciences journals. Based on our colleagues’ experiences we expect our predictions to be lower bounds for the official journal impact factors. We explain why it is useful to derive one’s own journal impact factor.Keywords：WoS (Web of Science);JCR (Journal Citation Reports);Citation analysis;Predicted impact factors- 36
- |
- 0
- |
- 0
Published：2021-12-30
Editorial
Loading...
0