Abstract:The ethanol tolerance of a self-flocculating yeast strain SPSC01 was investigated in an oxygen-limited fed-batch bioreactor. Employing Focused Beam Reflectance Measurement (FBRM) on-line monitoring system, four yeast floc populations with the average size ranging from 100 to 400μm were obtained. It was found that ethanol tolerance increased with the increasing floc size in the 100, 200, and 300μm floc populations, while increasing the average floc size further to 400μm resulted in lower ethanol tolerance. Examination of the membrane composition of different floc populations revealed that the plasma membrane composition of the floc populations was significantly different in the contents of ergosterol, phosphatidylinositol, as well as phospholipid palmitoleic acid. What’s more, the plasma membrane of more ethanol tolerant floc population was less permeable when subjected to 15% (V/V) ethanol shock treatment, and the plasma membrane ATPase activities were higher in the floc populations with higher ethanol tolerance. These results indicate that the average size distribution of the floc populations exerted great influence on the physiological status of yeast cells during the ethanol production process, leading to the changes in plasma membrane composition that contributed to improved ethanol tolerance in self-flocculating yeast SPSC01.

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	1. Ethanol tolerance and the variation of plasma membrane composition of yeast floc populations with different size distribution
	Juanjuan Lei,Zhao Xinqing,Ge Xumeng,Bai Fengwu
	Biology 31 May 2007
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	Abstract:The ethanol tolerance of a self-flocculating yeast strain SPSC01 was investigated in an oxygen-limited fed-batch bioreactor. Employing Focused Beam Reflectance Measurement (FBRM) on-line monitoring system, four yeast floc populations with the average size ranging from 100 to 400μm were obtained. It was found that ethanol tolerance increased with the increasing floc size in the 100, 200, and 300μm floc populations, while increasing the average floc size further to 400μm resulted in lower ethanol tolerance. Examination of the membrane composition of different floc populations revealed that the plasma membrane composition of the floc populations was significantly different in the contents of ergosterol, phosphatidylinositol, as well as phospholipid palmitoleic acid. What’s more, the plasma membrane of more ethanol tolerant floc population was less permeable when subjected to 15% (V/V) ethanol shock treatment, and the plasma membrane ATPase activities were higher in the floc populations with higher ethanol tolerance. These results indicate that the average size distribution of the floc populations exerted great influence on the physiological status of yeast cells during the ethanol production process, leading to the changes in plasma membrane composition that contributed to improved ethanol tolerance in self-flocculating yeast SPSC01.
	TO cite this article:Juanjuan Lei,Zhao Xinqing,Ge Xumeng, et al. Ethanol tolerance and the variation of plasma membrane composition of yeast floc populations with different size distribution [OL].[31 May 2007] http://en.paper.edu.cn/en_releasepaper/content/13181


	2. Identification, characterization and gene cloning of a phytase with potential industrial interest
	Ming-Lv Sun,Bo Zhou,Jian Sun,Dong-Min Zhao,Xiao-Yun Wang
	Biology 12 April 2007
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	Abstract:A high phytase-producing strain of Aspergillus niger N-3 was identified by screening 94 microbial strains. The phytase displayed physicochemical characteristics of potential industrial interest with independent intellectual property. The enzyme activity in fermented broth achieved a maximum of 495 U/mL. The enzyme was purified by a combination of ammonium sulfate fractionation and gel filtration chromatography. The molecular weight of the enzyme as determined by SDS-PAGE was 60-80 kDa, with maximum activity at about 55 C (after incubation at 10 min). Dual optima pH (pH 2.0 and pH 5.5) was gained. Activity at pH 2.0, which is more suitable to the circumstance of monogastric animals’ stomach was about 30% higher than that at pH 5.5. The phytase retained about 45% of its enzymatic activity under heat treatment at 90 C for 5 min. It showed a greater affinity for sodium phytate (Km = 132.3 μM) than for pNPP (Km = 2.23 mM). The phyA gene was isolated and sequenced. The coding region without the introns and putative signal sequence was comprised of 1347 nucleotides. It encoded a polypeptide of 448 amino acids， exhibiting high amino acid sequence homologies (94.87%) with the typical phytase Aspergillus niger NRRL 3135.
	TO cite this article:Ming-Lv Sun,Bo Zhou,Jian Sun, et al. Identification, characterization and gene cloning of a phytase with potential industrial interest[OL].[12 April 2007] http://en.paper.edu.cn/en_releasepaper/content/12158

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	3. Screening, Cloning and Overexpression of Aspergillus niger phytase (phyA) in Pichia pastoris with favorable characteristics
	Dong-Min Zhao,Min Wang,Xi-Jun Mu,Ming-Lv Sun,Xiao-Yun Wang
	Biology 09 April 2007
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	Abstract:An Aspergillus niger spp. which produces extracellular phytase was isolated. The phyA gene was cloned and sequenced. The results show that the coding region comprises 1347 bp and the homology of nucleotide sequence and amino acid sequence with A. niger NRRL 3135 were about 96% and 93.8%, respectively. The coding sequence phyA fragment was cloned into Pichia secretive expression vector pPICZA and then transformed into chromosome of Pichia pastoris GS115 strain by electroporation. After stepwise screenings by antibiotics zeocin, yeast PCR and induction by methanol, one transformant showed high expression. The activity of fermented broth was 30000-fold of original Aspergillus niger spp. phytase (0.008 U•ml-1) and the specific activity was 503 U•mg-1 of protein. The Km value was 0.196 mmoll-1 for sodium phytate and 18.16 mmoll-1 for pNPP. It showed activity at pH range values of 2-6 with the optimum at 5.5. Studies on thermostability showed that the recombinant phytase remained 70% activity after exposure to 90℃ for 5 min and 65% for 30 min. Fluorescence analyses show that when the enzyme was treated at increasing temperatures, a little fluorescence red-shift was observed (4 nm) with an increase in emission intensity, which indicates that the conformation of the enzyme was very stable during the heating process.
	TO cite this article:Dong-Min Zhao,Min Wang,Xi-Jun Mu, et al. Screening, Cloning and Overexpression of Aspergillus niger phytase (phyA) in Pichia pastoris with favorable characteristics[OL].[ 9 April 2007] http://en.paper.edu.cn/en_releasepaper/content/12053


	4. Testing the Hypothesis on Unidirectional Hybridization in Plants: Observations on Sonneratia, Bruguiera and Ligularia
	Renchao Zhou,Suhua Shi,David Boufford,ChungI Wu,Shi Suhua
	Biology 19 March 2007
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	Abstract:When natural hybridization occurred at sites where the hybridizing species differ in abundance, the pollen load delivered to the rare species would consist predominantly of that from the common species. Previous authors have therefore proposed a hypothesis on the direction of hybridization: Interspecific hybrids are more likely to have the female parent from the rare species and the male parent from the common species. By examining the maternally inherited chloroplast DNA of six interspecific F1 hybrids from four genera of plants, we observed highly asymmetric hybridizations that appear to be inconsistent with the current hypothesis. Our results show that relative abundance of the hybridizing species is not a good predictor of the direction of hybridization. These unexpected observations may result from other mechanisms operating in the hybrid zones of plants.
	TO cite this article:Renchao Zhou,Suhua Shi,David Boufford, et al. Testing the Hypothesis on Unidirectional Hybridization in Plants: Observations on Sonneratia, Bruguiera and Ligularia [OL].[19 March 2007] http://en.paper.edu.cn/en_releasepaper/content/11515


	5. Population genetic structure of three tree species in the mangrove genus Ceriops (Rhizophoraceae) from the Indo West Pacific
	Yelin Huang,Fengxiao Tan,Guohua Su,Shulin Deng,Suhua Shi
	Biology 19 March 2007
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	Abstract:Ceriops is a viviparous mangrove with widespread species C. decandra and C. tagal, and the endemic species C. australis. Genetic diversity of the three species was screened in 31 populations collected from 22 locations in the Indo West Pacific using ISSR and sequences of partial nuclear gene (G3pdh) and chloroplast DNA (trnV-trnM). At the species level, the estimate of gene diversity (Ht) in C. decandra was 0.270, much higher than that in C. tagal (0.118) and C. australis (0.089) revealed by ISSRs. Heterozygous individuals were detected from one single population of C. tagal based on G3pdh sequences. Only C. decandra (four G3pdh haplotypes and three trnV-trnM haplotypes) was presented having more than one haplotype inferred from each DNA sequences data set. No haplotype diversity within population was detected in any of the three species, with the exception of the hybrid population. Three major geographical groups, correspond to the East Indian Ocean (EIO), South China Sea (SCS), and North Australia (NA) were identified in both C. decandra and C. tagal based on ISSRs. DNA sequences of C. decandra also detected the same three geographical groups by SAMOVA. Significant spatial genetic structure from populations between the three regions were detected, which may result from the historical geological events at these regions during the recent Pleistocene glaciations. This study also provided insights into the phylogenetics of Ceriops.
	TO cite this article:Yelin Huang,Fengxiao Tan,Guohua Su, et al. Population genetic structure of three tree species in the mangrove genus Ceriops (Rhizophoraceae) from the Indo West Pacific[OL].[19 March 2007] http://en.paper.edu.cn/en_releasepaper/content/11503


	6. Primary study of a Novel Protein F46-crp That Contributes to Centrosome Duplication
	Wei Yi,Shen Enzhi,Fan Jinling,Liu Qian,Jan Marc,Wang Yongchao,Sun Le,Liang Qianjin
	Biology 09 March 2007
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	Abstract:Using a serum from a patient suffering from an autoimmune disease (progressive systemic sclerosis), a novel centrosome related protein F46-crp was detected. We identified the target protein by immunoprecipitation and Western blot and tandem mass spectrometry sequencing. The results show the protein F46-crp has an apparent molecular mass of about 60 kDa. A cDNA of HeLa F46-crp protein was obtained using RT-PCR, and a recombinant F46-crp used to generate monoclonal antibodies. Immunofluorescence microscopy of synchronized HeLa cells labeled with the anti-F46-crp -specific antibodies revealed that F46-crp localized exclusively to the centrosome during interphase, although it completely disappeared at the onset of mitosis. After effectively silencing the F46-crp by antisense RNA, cell growth and proliferation were strongly inhibited and the cell cycle typically stalled at S phase. The silencing also resulted in the formation of poly-centrosomal and multinucleate cells, which finally became apoptotic. These results suggest that F46-crp is a novel centrosome related protein, whose expression is cell cycle-dependent, and it is involved in centrosome duplication.
	TO cite this article:Wei Yi,Shen Enzhi,Fan Jinling, et al. Primary study of a Novel Protein F46-crp That Contributes to Centrosome Duplication [OL].[ 9 March 2007] http://en.paper.edu.cn/en_releasepaper/content/11354


	7. An efficient sampling method for non-convex thermodynamic solution space of genome-scale networks
	Feng Yang,Feng Qi
	Biology 24 February 2007
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	Abstract:Constraint-based approaches, such as flux balance analysis (FBA) and energy balance analysis(EBA), are widely applied to study a variety of metabolic networks. While the convex mass-balance solution space has been rigourously characterized, the nonconvex thermodynamically feasible solution space has not been characterized yet, especially for large-scale biochemical networks. Therefore, developing an efficient sampling technique to characterize the physicochemically feasible solution space is critical. Here we present an efficient method to uniformly sample the nonconvex thermodynamically feasible solution space. By studying the characteristics of sampled flux distributions, the thermodynamic feasibility and directionality of some key reactions are revealed. The developed methodology can be used to revise currently available metabolic networks, and systematically determine feasible flux directions which satisfy both mass-balance and thermodynamic-balance constraints.
	TO cite this article:Feng Yang,Feng Qi. An efficient sampling method for non-convex thermodynamic solution space of genome-scale networks[OL].[24 February 2007] http://en.paper.edu.cn/en_releasepaper/content/11196


	8. Optimization of an enzyme production medium and bioconversion conditions for L (+)-tartaric acid production by Corynebaterium sp. in fed-batch culture
	Wenpeng Li,Jinlun Xie
	Biology 24 February 2007
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	Abstract:The medium for production of cis-epoxysuccinate hydrolase from Corynebaterium sp. YNUCC0211 and bioconversion conditions for L (+)-tartrate production were optimized by means of statistical methods respectively. Results revealed that the yields of L (+)-tartrate were improved by feeding fresh synthesized cis-expoxysuccinate solution with 12.0 of pH or with 3% of hydrogen peroxide to the optimum medium after being inoculated for 32-48 hours. The optimum medium contains (g/litre): glucose 15, cornsteep liquor 3.0, yeast extraction 0.3, K2HPO4.3H2O 3.5, dipotassium cis-epoxysuccinate 7.0, NH4NO3 4.0, (NH4)2 SO4 1.0, MgSO4.7H2O 1.0, FeSO4.7H2O 0.02, pH 7.0 - 7.2.
	TO cite this article:Wenpeng Li,Jinlun Xie. Optimization of an enzyme production medium and bioconversion conditions for L (+)-tartaric acid production by Corynebaterium sp. in fed-batch culture[OL].[24 February 2007] http://en.paper.edu.cn/en_releasepaper/content/11195


	9. Studies In Vitro and In Vivo of Pharmacological Activities of PFR(Tic)amide
	Fang Quan ,He Feng ,Wang Yiqing ,Chen Qiang ,Wang Rui
	Biology 30 November 2006
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	Abstract:Neuropeptide FF (NPFF) belongs to a neuropeptide family including two precursors (pro-NPFFA and pro-NPFFB) and two receptors (NPFF1 and NPFF2). The NPFF analogue PFR(Tic)amide was originally found as an putative antagonist on NPFF receptors because of its depressor response, while it was recently shown to be a “super-agonist” on NPFF1 and NPFF2 receptors in vitro. To further evaluate its pharmacological profiles, in the present work, PFR(Tic)amide were synthesized and investigated to address their potencies and efficacies in a series of assays. (1) In the isolated mouse colon bioassay, it evoked significant colonic contractions at a high dose of 50 μM, which were attenuated by pretreatment with BIBP3226; (2) PFR(Tic)amide (10 ~ 30 nmol/mouse) injected into the third ventricle dose-dependently induced marked hypothermia in a manner similar to NPFF. Our results suggest that PFR(Tic)amide acts as an NPFF agonist in vitro and in vivo. Furthermore, it shows much higher potency in thermoregulatory test, compared to NPFF.
	TO cite this article:Fang Quan ,He Feng ,Wang Yiqing , et al. Studies In Vitro and In Vivo of Pharmacological Activities of PFR(Tic)amide[OL].[30 November 2006] http://en.paper.edu.cn/en_releasepaper/content/10078


	10. Design，Preparation and in vitro Bioactivity of Monopegylated Recombinant Hirudin
	Hou Beibei ,Li Shirong ,Li Xiaohui ,Xiu Zhilong
	Biology 28 November 2006
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	Abstract:Hirudin is the most potent inhibitor of thrombin found in nature. As a promising anticoagulant, a significant drawback which significantly inhibits its clinical application, is the short serum half-life. In order to prolong circulation half-life in vivo, PEGylation is an effective and commonly used method. In this study Succinimidyl carbonyl mPEG (SC-mPEG) 20kDa was attached to recombinant hirudin (r-Hir) at mildly acidic pH to favor the formation of mono- PEGylated r-Hir, since histidine residues represent the preferred PEGylation sites under mildly acidic conditions, and there is only one histidine residue, His51, in r-Hir. Because of the high ratio of monopegylated product, the reaction mixture was easily separated by a one-step ion-exchange chromatographic(IEC) separation procedure. The proportion of urethane bonds involving carboxyalkylated histidines was assayed using its sensitivity to neutral hydroxylamine, and about 79.71% of the mono-substituted PEGylated r-Hir was PEGylated
	TO cite this article:Hou Beibei ,Li Shirong ,Li Xiaohui , et al. Design，Preparation and in vitro Bioactivity of Monopegylated Recombinant Hirudin[OL].[28 November 2006] http://en.paper.edu.cn/en_releasepaper/content/9973

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