KfoE encodes a fructosyltransferase involved in capsular polysaccharide biosynthesis in Escherichia coli K4

Escherichia coli K4 synthesizes a capsular polysaccharide (CPS) consisting of a fructose-branched chondroitin (GalNAc-GlcA(fructose)n), which is a biosynthetic precursor of chondroitin sulfate. Here, the role of kfoE in the modification of the chondroitin backbone was investigated using knock-out and recombinant complementation experiments. kfoE disruption and complementation had no significant effect on cell growth. CPS production was increased by 15 % in the knock-out strain, and decreased by 21 % in the knock-out strain complemented with recombinant kfoE. CPS extracted from the knock-out strain was chondroitin, whereas CPS extracted from the complemented strain was a fructose-branched chondroitin. The results demonstrated that the kfoE gene product altered the fructose group at the C3 position of the GlcA residue during production of K4CPS.     

Evaluation of aroma active compounds in <Emphasis Type="Italic">Tuber</Emphasis> fruiting bodies by gas chromatography–olfactometry in combination with aroma reconstitution and omission test

The aroma active compounds of three Tuber fruiting bodies (i.e., Tuber himalayense, Tuber indicum, and Tuber sinense) were firstly systematically evaluated by instrumental gas chromatography–olfactometry combining with quantitative analysis, aroma reconstitution, and omission tests. Twelve aroma active compounds were characterized by aroma extract dilution analysis, and 3-(methylthio) propanal, 3-methylbutanal, and 1-octen-3-ol with the highest flavor dilution (FD) factor (i.e., 1,024–2,048) were suggested as key contributors to the aroma. Odor activity value (OAV) was employed to determine the relative contribution of each compound to the aroma, and the compound with the highest FD factor also had the highest OAV (i.e., 10,234–242,951). Then, the synthetic blends of odorants (aroma reconstitution) were prepared with OAV larger than 15, and their aromas were very similar to the originals. Omission tests were carried out to verify the significance of 3-(methylthio) propanal, 1-octen-3-ol, and 3-methylbutanal as key compounds in the aroma of tested Tuber fruiting bodies.     

Combination of bone tissue engineering and BMP-2 gene transfection promotes bone healing in osteoporotic rats

OBJECTIVE: The aim of this study was to develop a feasible approach to promote bone healing in osteoporotic rats using autogenous bone tissue-engineering and gene transfection of human bone morphogenetic protein 2 (hBMP-2). METHODS: Bone marrow stromal cells (BMSCs) from the left tibia of osteoporotic rats were transfected with the hBMP-2 gene in vitro which was confirmed by immunohistochemistry, in situ hybridization and Western blotting. Autogenous transfected or untransfected BMSCs were seeded on macroporous coral hydroxyapatite (CHA) scaffolds. Each cell-scaffold construct was implanted into a defect site which was created in the ramus of the mandible of osteoporotic rats. Four or eight weeks after implantation in situ hybridization was performed in BMSCs transfected with hBMP-2, X-ray examinations, histological and histomorphological analyses were used to evaluate the effect of tissue-engineered bone on osseous defect repair. RESULTS: Newly formed bone was observed at the margin of the defect 4 weeks after implantation with BMSCs transfected with BMP-2. Mature bone was observed 8 weeks after treatment. In the control group there was considerably less new bone and some adipose tissue was observed at the defect margins 8 weeks after implantation. CONCLUSIONS: Autogenous cells transfected with hBMP-2 promote bone formation in osteoporotic rats. BMSC-mediated BMP-2 gene therapy used in conjunction with bone tissue engineering may be used to successfully treat bone defects in osteoporotic rats. This method provides a powerful tool for bone regeneration and other tissue engineering.     

双尾蚜属的种类与地理分布

双尾蚜属Diuraphis Aizenberg全世界记录13种,主要分布在古北界和新北界。根据种类丰富度和特有种成分,欧亚大陆的欧洲和中亚为该属蚜虫的现代第一分布中心,北美为第二分布中心。本文提供了该属所有13个种的分种检索表。双尾蚜属蚜虫在中国共有7种,主要分布在蒙新区。它们是：麦双尾蚜Diuraphis noxia (Mordvilko), 害冰麦双尾蚜D. nociva Zhang et Liang,冰草麦蚜D. (Holcaphis) agropyronophaga Zhang, 披碱草蚜D. (Holcaphis) elymophila Zhang, 西方麦蚜D. (Holcaphis) frequens (Walker), 雀麦蚜D. (Holcaphis) bromicola Hille Ris Lambers和绒毛草蚜D. (Holcaphis) holci (Hille Ris Lambers)。对中国种类进行了简要描述。     

Preliminary results on nematicidal activity from culture filtrates of Basidiomycetes against the pine wood nematode,Bursaphelenchus xylophilus (Aphelenchoididae)

One hundred and eighty one fungal species that were isolated from the fresh fruiting bodies collected in the Mountains of Pu Er County of Yunnan Province, China were tested on the pine wood nematode,Bursaphelenchus xylophilus in vitro. Each fungal species was grown in Czapek broth and potato dextrose broth (PDB). Fifteen filtrates fromAmauroderma austrosinense, Amauroderma macer, Filoboletus sp.,Laccaria tortilis, Lactarius gerardii, Lentinula edodes, Oudemansiella longipes, Oudemansiella mucida, Peziza sp.,Pleurotus sp.,Sinotermitomyces carnosus (two strains),Strobilomyces floccopus, Termitomyces albuminosus, Tylopilus striatulus grown on PDB were found to be pathogenic to the tested nematodes. Eleven filtrates fromAmanita junguillea, Amanita sp.,Daedalea sepiaria, Fistulina hepatica, Omphalotus olearius, Oudemansiella mucida, Peziza sp.,Pleurotus pulmatus, Ramaria sp.,Tricholoma conglobatum, Tylopilus striatulus grown on Czapek broth were also pathogenic to the nematodes. When screening for nematicidal potential of fungi, it is important to study the growth medium conditions necessary to obtain the optimal nematicidal effect as fungal filtrates growing on different liquid media showed a very inconsistent toxicity towards nematodes.     

Comparison of three ELISA kits for the differentiation of foot-and-mouth disease virus-infected from vaccinated animals

A study was performed to validate 3 FMDV 3ABC-I-ELISA kits developed in China for the differentiation of FMDV infected and vaccinated animals. Sets of sera from naive and vaccinated cattle as well as from cattle that had been infected were tested for antibodies against nonstructural proteins (NSPs) of FMDV by commercial diagnosis kits, Ceditest® FMDV-NS (Ceditest® kit), UBI® FMDV NONSTRUCTURAL PROTEIN ELISA DIRECTION INSERT (UBI® kit) and a FMDV 3ABC-I-ELISA kit developed at the Lanzhou Veterinary Research Institute. The test parameters (sensitivity and specificity) of the three kits were determined, and the result obtained from FMD 3ABC-I-ELISA kit was compared with that obtained from two foreign kits. The results indicated that the coincidence rate between the FMDV 3ABC-I-ELISA and Ceditest® kits was 98.05%, and the coincidence rate between the FMDV 3ABC-I-ELISA and UBI® kits was 94.4%; the sensitivity of both Ceditest® and FMDV 3ABC-I-ELISA kit was 100%. However, the sensitivity of the UBI® kit was only 81.8%. With sera from naive or vaccinated non-infected animals, the specificity of all tests exceeded 90%.     

Factors influencing limit values for pine needle litter decomposition: a synthesis for boreal and temperate pine forest systems

We synthesized available data for decomposition of pine (Pinus) needle litter in pine forests to determine the litter chemical characteristics and climate factors that explained variation in the limit value, i.e. the level of accumulated mass loss at which the decomposition process either continues at a very low rate or possibly stops. Our data base included 56 separate studies on decomposition of pine needle litter, spanning Scots pine, lodgepole pine, Aleppo pine, stone pine and white pine, mainly incubated at the site of collection. Studies had 5 to 19 samplings, on average 10, and the decomposition was followed to a mass loss ranging from 47 to 83%, on average 67%. The periods from 3.0 to 5.4 years, on average 3.9 years, were of sufficient duration to allow estimates of limit values of decomposition. We used a linear mixed model with regression effects to relate limit values to potential explanatory variables, namely the sites’ long-term mean annual temperature (MAT) and mean annual precipitation (MAP) and to substrate-chemistry factors. Regarding the latter, we explored two models; one that included initial concentrations of water solubles, lignin, N, P, K, Ca, Mg, and Mn and one that included only lignin, N, Ca, and Mn to focus on those nutrients known to influence lignin degradation. Using backward elimination significant explanatory variables were determined. For litter decomposed in its site of origin we found the limit value to depend mainly on the initial concentration of Mn, with higher Mn concentrations resulting in higher accumulated mass loss. Thus, litter with higher Mn reached a higher limit value and left a smaller stable fraction. This is likely due to the fact that Mn is an essential component of ligninolytic enzymes important for degrading litter in the later stages of decomposition. Manganese has received little attention in decomposition studies to date. Given its significance in this synthesis, the role of Mn in influencing variation in the late stages of decomposition among ecosystems and among litters of other genera besides Pinus deserves further attention.     

碱茅(puccinellia tenuifolra)Put-Cu/Zn-SOD基因的克隆及在酵母中的表达

从碱茅根cDNA文库分离得到Put-Cu/Zn-SOD全长cDNA,其序列全长为2 700 bp,该基因的开放读码框为长615 bp,所编码的蛋白由204个氨基酸组成,其预测分子量约为20.6 kD、理论等电点约为5.63.Put-Cu/Zn-SOD氨基酸序列与水稻Cu/Zn-SOD序列有较高的同源性为87%.将Put-Cu/Zn-SOD基因构建到酵母表达载体pYES2,并转化至酵母(INVSc1).对pYES2-Put-Cu/Zn-SOD转化酵母进行盐碱、氧化胁迫实验.结果表明:重组酵母的抗盐碱、氧化能力明显高于对照(pYES2转化酵母),结果显示了碱茅的Cu/Zn-SOD基因在酵母表达中,具有提高酵母抗盐碱和耐氧化能力.     

Design and fabrication development of a micro flow heated channel with measurements of the inside micro-scale flow and heat transfer process

The current work provides a design and fabrication technique for a micro channel system that can provide a uniform heat flux boundary condition on the channel wall and a well insulation on the wall to prevent heat loss from the channel to the outside ambient. Therefore, detailed micro-scale flow and heat transfer process and information along the channel can be studied. Semiconductor sensor material was selected to fabricate both the heaters and the arrays of temperature sensors on a silicon substrate. These heaters and sensors were then moved to a low thermal conductivity epoxy-glass substrate for fabrication of the channel. Design consideration and fabrication techniques involved in this processes will be discussed. A final measurement for the validation of the heaters and the sensors fabricated and a study of the flow friction behavior and the heat transfer coefficient distributions inside the micro channel will be presented. The local Nusselt number distrubution inside the micro channel is reported the first time in the open literature.