Effect of Linoleic Acid Concentration on Conjugated Linoleic Acid Production by Butyrivibrio fibrisolvens A38

Butyrivibrio fibrisolvens A38 inocula were inhibited by as little as 15 μM linoleic acid (LA), but growing cultures tolerated 10-fold more LA before growth was inhibited. Growing cultures did not produce significant amounts of cis-9, trans-11 conjugated linoleic acid (CLA) until the LA concentration was high enough to inhibit biohydrogenation, growth was inhibited, and lysis was enhanced. Washed-cell suspensions that were incubated anaerobically with 350 μM LA converted most of the LA to hydrogenated products, and little CLA was detected. When the washed-cell suspensions were incubated aerobically, biohydrogenation was inhibited, CLA production was at least twofold greater, and CLA persisted. The LA isomerase reaction was very rapid, but the LA isomerase did not recycle like a normal enzyme to catalyze more substrate. Cells that were preincubated with CLA lost their ability to produce more CLA from LA, and the CLA accumulation was directly proportional (r² = 0.98) to the initial cell density. Growing cells were as sensitive to CLA as LA, the LA isomerase and reductases of biohydrogenation were linked, and free CLA was not released. Because growing cultures of B. fibrisolvens A38 did not produce significant amounts of CLA until the LA concentration was high, biohydrogenation was arrested, and the cell density had declined, the flow of CLA from the rumen may be due to LA-dependent bacterial inactivation, death, or lysis.     

Studies on the interactions between drugs and estrogen: analytical method for prediction system of gynecomastia induced by drugs on the inhibitory metabolism of estradiol using Escherichia coli coexpressing human CYP3A4 with human NADPH-cytochrome P450 reductase

To establish a prediction system for drug-induced gynecomastia in clinical fields, a model reaction system was developed to explain numerically this side effect. The principle is based on the assumption that 50% inhibition concentration (IC(50)) of drugs on the in vitro metabolism of estradiol (E2) to its major product 2-hydroxyestradiol (2-OH-E2) can be regarded as the index for achieving this purpose. By using human cytochrome P450s coexpressed with human NADPH-cytochrome P450 reductase in Escherichia coli as the enzyme, the reaction was examined. Among the nine enzymes (CYP1A1, 1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4) tested, CYP3A4 having a V(max)/K(m) (ml/min/nmol P450) value of 0.32 for production of 2-OH-E2 was shown to be the most suitable enzyme as the reagent. The inhibitory effects of ketoconazole, cyclosporin A, and cimetidine toward the 2-hydroxylation of E2 catalyzed by CYP3A4 were obtained, and their IC(50) values were 7 nM, 64 nM, and 290 microM, respectively. The present results suggest that IC(50) values thus obtained can be substituted as the prediction index for gynecomastia induced by drugs, considering the patients' individual information.     

Comparative study of the lamina cribrosa and the pial septa in the vertebrate optic nerve and their relationship to the myelinated axons

The optic nerve contains the connective tissues, i.e. the lamina cribrosa and pial septa. This report presents a histological comparison of the lamina cribrosa and pial septa in the five classes (mammals, birds, reptiles, amphibians and teleosts) of vertebrates. Furthermore, the distribution of myelinated fibers was observed from the optic nerve through the retina in the same animals. The lamina cribrosa is found in mammals except for mice, and in birds. Structural complexity of the lamina was different in animals but generally dependent of the optic nerve thickness. The pial septa were present in the optic nerve proper of the mammals except for the mice, in birds and in a part of teleosts. Fasciculation of the optic nerve by the pial septa tended to be more prominent as the optic nerve become thicker. The optic nerve consisted of largely myelinated fibers in vertebrates. The retina contained some myelinated fibers in submammals but was thoroughly devoid of myelinated fibers in mammals. The borderline between myelinated and unmyelinated portions in the optic nerve of different species did not related to the lamina cribrosa. Amphibians had exceptionally only a few myelinated fibers in the optic nerve and no myelinated fibers in the retina.     

外源p21~(WAF1)转染对人成纤维细胞凋亡的影响

构建了有义和反义ｐ２１ＷＡＦ１ 逆转录病毒表达载体, 分别经脂质体包裹后转染人胚肺二倍体成纤维细胞（２ＢＳ）。Ｓｏｕｔｈｅｒｎ 印迹杂交证实转染细胞中外源ｐ２１ ＷＡＦ１ｃＤＮＡ 已整合入基因组中。与空载体转染细胞相比, 有义转染细胞的ｐ２１ＷＡＦ１ ｍ ＲＮＡ 表达上升; 细胞增殖速度明显减慢; 对丁酸钠诱导凋亡的敏感性降低, 表现在细胞存活率升高, 核ＤＮＡ 梯状断裂片段出现的时间滞后, 断裂片段浓度下降, 流式细胞计检测的凋亡峰面积缩小。而反义转染细胞的ｐ２１ＷＡＦ１ ｍ ＲＮＡ表达下降; 细胞增殖速度较快; 对丁酸钠诱导凋亡的敏感性上升, 有关表现与有义转染细胞相反。说明２ＢＳ细胞内ｐ２１ＷＡＦ１ 的表达量与其被丁酸钠诱导凋亡的能力呈负相关。     

人红细胞非凝集型单抗(自身全血凝集试验试剂)的研制及鉴定

应用杂交瘤技术 ,混合人O型红细胞免疫纯系BALB/C小鼠 ,包被的红细胞作为固相抗原 ,ELISA法筛选出识别红细胞表面共同抗原的抗体 ,然后利用Coombs原理 ,加入抗球蛋白试剂。用玻片法筛选出非凝集型抗体 ,得到 2株稳定分泌上述抗体的杂交瘤并进行初步鉴定 ,单抗上清血凝效价可达 1∶5 0～ 1∶10 0 ,腹水血凝效价为 1∶8× 10 4 ～ 1∶16× 10 4 。另外 ,本文特别讨论了凝集型单抗的Fab段作为非凝集型抗体应用的可能性。     

人重组白蛋白基因在巴斯德毕赤酵母中的高效表达

The yeast Pichia pastoris was transformed by the multi\|copy Pichia expression vector that can express secreted human albumin.The high level expression of cell line was selected after screening.The expression of human recombinant albumin in Pichia pastoris induced by different methods were compared.The retio of secreted human albumin is 80% in total secreted proteins and the expression level reaches as high as is 10g/L.     

LABORATORY SUSCEPTIBILITY OF PLUTELLA XYLOSTELLA TO METARHIZIUM ANISOPLIAE AND NOMURAEA RILEYI*

Abstract Five isolates of Metarhizium anisopliae and one isolate of Nomuraea rileyi were bioassayed against larvae of Plutella xylostella. Larvae were treated by exposing cabbage leaf discs previously immersed in conidial suspension, and were then incubated at 25^oC and observed daily. One of M. anisopliae isolates, F11248, originally from Mastotermes darwiniensis was found being most virulent against P. xylostella. The LC₅₀ was estimated as 2.03 times 10⁴conidia/ml with 9 d mortality data, and the LT₅₀ was 4.97 d at concentration of 10⁷conidia/ml. Isolate F163 (N. rileyi) showed virulence to P. xylostella in both tests, but no cadavers sporulated.     

新疆晚奥陶世晚期管状体及其古植物学物意义

本文系统描述了产自我国新疆塔里木盆地晚奥陶世晚期的管状体,包括2属8种,其中一个新种。通过对比研究,本管状体组合与Burgess和Edwards(1991）的下组合相当。根据本组合的研究,对Burgess和Edwards的组合进行了补充,其组合由不同类型的光壁管、低分异度的内壁加厚管组成、未见外壁加厚管和丝状体,组合的时代从中奥陶世到早志留世（晚Llandovery)。根据植物学的对比研究,管状体主要产自Nematophytales Lang.     

粉煤灰改良砂姜黑土对麦田生态因子及重金属残留的影响

采用盆栽试验,研究了粉煤灰改良砂姜黑土对麦田生态因子及Cd、Cr、Pb、Hg和As残留的影响.结果表明,粉煤灰改良砂姜黑土可以降低土壤容重和土壤比重,减少土壤粘粒含量,增加土壤孔隙度和土壤渗透系数,提高耕层地温,促进土壤微生物活动和养分转化;土壤含水量高时具有散湿作用,土壤含水量低于10%后,具有保墒作用;在粉煤灰用量为6×10⁴～18×10⁴kg·hm^-2的条件下,土壤及小麦子粒中重金属元素的积累量远低于国际污染标准值,即在此范围内,施用粉煤灰改良砂姜黑土是安全可靠的.