鸡减蛋综合征病毒（EDSV—76）末端前体蛋白的基因结构分析

从中国发病鸡群中分离的鸡减蛋综合征病毒弱毒株ＡＡ－２,经常规方法提取其病毒核酸后,组建了完整的限制性内切酶ＰｓｔＩ及ＨｉｎｇⅢ水解片段的基因文库,并对其中ＨｉｎｄⅢ,－ＳａｃⅠ进行了序列测定。同源比较分析证明：其Ｌ链含编码病毒末端前体蛋白,容量为５８０个氨基酸残基的开放读码框架。     

中国脊髓灰质炎Ⅱ型疫苗相关分离株病毒性状的观察

对１９９４年中国分离的１３株脊髓灰质炎Ⅱ型疫苗相关株进行了ＰＣＲ－ＲＦＬＰ分析,发现７株为重组病毒,毒力较疫苗株有回复,在Ⅱ型脊髓灰质炎病毒基因序列上,对于神经毒力有重要影响的第４８１位核苷酸发生突变,另一个被视为重要位点的２９０８位核苷酸无一发生变化,反而在２９０９位核苷发生了高频率的点突变,意味着２９０９位点在中国Ⅱ型疫苗相关株的自然变异中可能起着重要作用。     

重组干扰素γ的中间试制

用带有表达质粒ＰＢＶ２２０（含有γ干扰素基因）的大肠杆菌ＤＨ５α株进行发酵培养,３批中试的菌产量平均为１４．１克／Ｌ,γ干扰素的表达量平均为１．０２±１０＾９ＩＵ／Ｌ,收集的菌体经高压匀质破菌后收集包涵体,用７ｍｏｌ／Ｌ盐酸胍提取干扰素,此过程中去除７８．４％菌体蛋白,而干扰素活性仅损失１０．４１％,粗制干扰素经复性可使干扰素活性提高４０５％,比活也有明显提高,３批平均为１．７６×１０＾７ＩＵ／ｍ     

鸡减蛋综合征病毒(Egg Drop Syndrome Virus,EDSV)巯基内肽酶的基因序列分析

鸡减蛋综合征病毒（ＥｇｇＤｒｏｐＳｙｎｄｒｏｍｅＶｉｒｕｓ,ＥＤＳＶ）巯基内肽酶的基因序列分析曾力宇１金奇１朱雷１章金钢２殷震２侯云德１关键词鸡减蛋综合征病毒（ＥＤＳＶ）,巯基内肽酶（Ｔｈｉｏｌ－ｅｎｄｏｐｅｐｔｉｄａｓｅ）,核苷酸序列分析ＥＤＳ病毒...     

黑石顶自然保护区常绿阔叶林优势植物地上部分的热值

对黑石顶自然保护区南亚热带低山常绿阔叶林地上部分各层次一些优势种和常见种的干重热值和去灰分热值的测定表明：植物的干重热值受灰分含量影响较大,植物去灰分热值随种类、器官而异,乔木层8种植物地上部分各器官平均去灰分热值在19．261-20．672kJg-1之间,各植物种的平均去灰分热值变化顺序如下：光叶红豆＞显脉新木姜＞福建青冈＞短花序楠＞生虫树＞小叶胭脂＞硬叶稠＞粘木。乔木层各器官的平均去灰分热值是：叶21．417kJg-1,幼枝19．929kJg-1,干树皮19．961kJg-1,干材18．664kJg-1。地上部分各层次相同器官平均去灰分热值有下列变化趋势：乔木层＞灌木层＞草本层,这一关系在植物叶的去灰分热值中表现尤为明显．     

Microbial production of a novel trihydroxy unsaturated fatty acid from linoleic acid

A bacterium isolated from a dry soil sample collected from McCalla, AL, USA, converted linoleic acid to a novel compound, 12,13,17-trihydroxy-9 (Z)-octadecenoic acid (THOA). The organism is a Gram-positive, non-motile rod (0.5 μ m × 2 μ m). It was identified as a species of Clavibacter ALA2. The product was purified by high pressure liquid chromatography, and its structure was determined by ¹H and ¹³C nuclear magnetic resonance and Fourier transform infrared spectroscopies, and by mass spectrometer. Maximum production of THOA with 25% conversion of the substrate was reached after 5–6 days of reaction. THOA was not further metabolized by strain ALA2. This is the first report of a 12,13,17-trihydroxy unsaturated fatty acid and its production by microbial transformation. Some dihydroxy intermediates were also detected. THOA has a structure similar to those of known plant self-defense substances. Received 13 January 1997/ Accepted in revised form 05 May 1997     

Major role for neuronal NO synthase in curtailing choroidal blood flow autoregulation in newborn pig.

We examined whether nitric oxide (NO) generated from neuronal NO synthase (nNOS) contributes to the reduced ability of the newborn to autoregulate retinal blood flow (RBF) and choroidal blood flow (ChBF) during acute rises in perfusion pressure. In newborn pigs (1-2 days old), RBF (measured by microsphere) is autoregulated over a narrow range of perfusion pressure, whereas ChBF is not autoregulated. N(G)-nitro-L-arginine methyl ester (L-NAME) or specific nNOS inhibitors 7-nitroindazole, 3-bromo-7-nitroindazole, and 1-(2-trifluoromethyl-phenyl)imidazole as well as ganglionic blocker hexamethonium, unveiled a ChBF autoregulation as observed in juvenile (4- to 6-wk old) animals, whereas autoregulation of RBF in the newborn was only enhanced by L-NAME. All NOS inhibitors and hexamethonium prevented the hypertension-induced increase in NO mediator cGMP in the choroid. nNOS mRNA expression and activity were three- to fourfold higher in the choroid of newborn pigs than in tissues of juvenile pigs. It is concluded that increased production of NO from nNOS curtails ChBF autoregulation in the newborn and suggests a role for the autonomic nervous system in this important hemodynamic function, whereas, for RBF autoregulation, endothelial NOS seems to exert a more important contribution in limiting autoregulation.     

A novel and highly efficient production system for recombinant adeno-associated virus vector

Recombinant adeno-associated virus(rAAV) has proven to be a promising gene delivery vector for human gene therapy. However, its application has been limited by difficulty in obtaining enough quantities of high-titer vector stocks. In this paper, a novel and highly efficient production system for rAAV is described. A recombinant herpes simplex virus type 1(rHSV-1) designated HSV1-rc/△UL2, which expressed adeno-associated virus type2(AAV-2) Rep and Cap proteins, was constructed previously. The data confirmed that its functions were to support rAAV replication and packaging, and the generated rAAV was infectious. Meanwhile, an rAAV proviral cell line designated BHK/SG2, which carried the green fluorescent protein(GFP) gene expression cassette, was established by transfecting BHK-21 cells with rAAV vector plasmid pSNAV-2-GFP. Infecting BHK/SG2 with HSV1-rc/△UL2 at an MOI of 0.1 resulted in the optimal yields of rAAV, reaching 250 transducing unit(TU) or 4.28×104 particles per cell. Therefore, compared with the conventional transfection method, the yield of rAAV using this "one proviral cell line, one helper virus" strategy was increased by two orders of magnitude. Large-scale production of rAAV can be easily achieved using this strategy and might meet the demands for clinical trials of rAAV-mediated gene therapy.     

Effects of fertigation scheme on N uptake and N use efficiency in cotton

While fertigation can increase fertilizer use efficiency, there is an uncertainly as to whether the fertilizer should be introduced at the beginning of the irrigation or at the end, or introduced during irrigation. Our objective was to determine the effect of different fertigation schemes on nitrogen (N) uptake and N use efficiency (NUE) in cotton plants. A pot experiment was conducted under greenhouse conditions in year 2004 and 2005. According to the application timing of nitrogen (N) fertilizer solution and water (W) involved in an irrigation cycle, four nitrogen fertigation schemes [nitrogen applied at the beginning of the irrigation cycle (N–W), nitrogen applied at the end of the irrigation cycle (W–N), nitrogen applied in the middle of the irrigation cycle (W–N–W) and nitrogen applied throughout the irrigation cycle (N&W)] were employed in a completely randomized design with four replications. Cotton was grown in plastic containers with a volume of 84 l, which were filled with a clay loam soil and fertilized with 6.4 g of N per pot as unlabeled and ¹⁵N-labeled urea for 2004 and 2005, respectively. Plant total dry matter (DM) and N content in N–W was significantly higher than in N&W in both seasons, but these were not consistent for W–N and W–N–W treatments. In year 2005, a significantly higher nitrogen derived from fertilizer (NDFF) for the whole plant was found in W–N and N–W than that in W–N–W and N&W. Fertigation scheme had a consistent effect on total NUE: N–W had the highest NUE for the whole plant, but this was not significantly different from W–N. Treatments W–N and W–N–W had similar total NUE, and N&W had the lowest total NUE. After harvesting, the total residual fertilizer N in the soil was highest in W–N, lowest in N–W, but this was not significantly different from N&W and W–N–W treatments. Total residual NO₃–N in the soil in N&W and W–N treatments was 20.7 and 21.2% higher than that in N–W, respectively. The total ¹⁵N recovery was not statistically significant between the four fertigation schemes. In this study, the fertigation scheme N–W (nitrogen applied at the beginning of an irrigation cycle) increased DM accumulation, N uptake and NUE of cotton. This study indicates that Nitrogen application at the beginning of an irrigation cycle has an advantage on N uptake and NUE of cotton. Therefore, NUE could be enhanced by optimizing fertilization schemes with drip irrigation.     

Effect of intermediates on ascorbic acid and oxalate biosynthesis of rice and in relation to its stress resistance.

Rice (Oryza sativa L.) roots were fed with L-ascorbic acid (AsA) and its putative precursors to observe AsA and oxalate concentrations and the resistance of rice to chilling, water stress, and Al toxicity. AsA concentration was significantly enhanced in both shoots and roots of rice seedlings by feeding with D-glucose or L-galactono-gamma-lactone. AsA or L-galactono-gamma-lactone treatment increased accumulation of oxalate mainly in soluble form, while these treatments decreased electrolyte leakage from root cells, H2O2 and lipid peroxidation level in rice seedlings subjected to chilling, water stress, and Al toxicity. They also alleviated the inhibition on root growth by Al. These results indicated that AsA and its immediate precursor protected plants against the oxidative damages induced by various stresses. However, 0.5 mM AsA and 10 mM L-galactono-gamma-lactone treatment had no significant effect on superoxide dismutase and catalase activity and ascorbate-peroxidase activities. Enhanced Al resistance caused by AsA and L-galactono-gamma-lactone may possibly be resulted from increased level of oxalate, which acts as metal chelator. Thus it is proposed that manipulation of AsA and oxalate biosynthesis through enhancement of L-galactono-gamma-lactone level in plants could be a strategy for improving abiotic stress tolerance.