Anaerobic Degradation of Normal- and Branched-Chain Fatty Acids with Four or More Carbons to Methane by a Syntrophic Methanogenic Triculture

Syntrophic degradation of normal- and branched-chain fatty acids with 4 to 9 carbons was investigated with a mesophilic syntrophic isobutyrate-butyrate-degrading triculture consisting of the non-spore-forming, syntrophic, fatty acid-degrading, gram-positive rod-shaped strain IB, Methanobacterium formicicum T1N, and Methanosarcina mazei T18. This triculture converted butyrate and isobutyrate to methane and converted valerate and 2-methylbutyrate to propionate and methane. This triculture also degraded caproate, 4-methylvalerate, heptanoate, 2-methylhexanoate, caprylate, and pelargoate. During the syntrophic conversion of isobutyrate and butyrate, a reversible isomerization between butyrate and isobutyrate occurred; isobutyrate and butyrate were isomerized to the other isomeric form to reach nearly equal concentrations and then their concentrations decreased at the same rates. Butyrate was an intermediate of syntrophic isobutyrate degradation. When butyrate was degraded in the presence of propionate, 2-methylbutyrate was synthesized from propionate and isobutyrate formed from butyrate. During the syntrophic degradation of valerate, isobutyrate, butyrate, and 2-methylbutyrate were formed and then degraded. During syntrophic degradation of 2-methylbutyrate, isobutyrate and butyrate were formed and then degraded.     

Effect of tumor necrosis factor-α and interferon-γ on the growth of a human salivary gland cell line

Interferon-γ (IFN-γ) is a product of activated T-lymphocytes, and tumor necrosis factor-α (TNF-α) is a product of both lymphocytes and macrophages. These cell types are often present at sites of tissue damage secondary to chronic infection or autoimmune disease. The purpose of this study was to characterize the effects of TNF-α and IFN-γ on a human submandibular gland epithelial cell line (HSG). IFN-γ caused a concentration-dependent decrease in HSG cell growth (～70% in 6 days). Conversely, TNF-α alone had little effect on the growth of these cells. When these cytokines were added in combination (20 units/ml TNF-α and 1,000 units/ml of IFN-γ), there was a synergistic antiproliferative effect; no apparent cell growth was observed. The cytokine-induced antiproliferative effect was reversible. After the apparent cessation of cell growth for 3–6 days, removal of the cytokines permitted complete growth recovery. Further, cells that recovered and exhibited growth patterns that were similar to control cells remained susceptible to the antiproliferative effects of the cytokines. Flow cytometry revealed that the percentage of cells in G0/G1 with the combination of cytokines was significantly increased by 24 h. The antiproliferative effect of IFN-γ alone and that of IFN-γ and TNF-α in combination were blocked completely using an antibody to the IFN-γ receptor. A hypothesized mechanism of tissue damage in autoimmune inflammatory disorders is via up-regulation of cell surface markers such as intercellular adhesion molecule type I (ICAM-1) and histocompatibility antigen HLA-DR which can exacerbate the inflammatory process. Treatment of HSG cells with IFN-γ, with or without TNF-α, resulted in increased levels of ICAM-1 and the acquisition of HLA-DR expression. These aggregate data suggest that IFN-γ alone can regulate the expression of cell surface markers involved in the inflammatory process as well as cause a potent yet reversible inhibition of HSG cell growth that is modulated by the presence of TNF-α. © 1994 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Neutralization sensitivity of human immunodeficiency virus type 1 is determined in part by the cell in which the virus is propagated.

Neutralizing antibody responses to human immunodeficiency virus type 1 (HIV-1) vary widely and have not been reproducibly associated with prognosis or disease progression. We have found that both low-passage clinical isolates and laboratory-adapted strains of HIV-1 have different sensitivities to neutralization by the same antiserum, depending on the host cell in which the viral stock is prepared. One such isolate (VL069) grown in H9 cells was neutralized by 20 human sera at a geometric mean titer of 1:2,047; this same isolate prepared in peripheral blood mononuclear cell (PBMC) culture was neutralized at a mean titer of < 1:10 by the same sera. Adsorption and mixing experiments indicated that neither antibody to H9 cell components nor blocking by excess viral antigen was responsible for the differences observed. This host cell effect is rapidly reversible upon passage of the virus from PBMCs to H9 cells and back into PBMCs. In contrast, the neutralization characteristics remained remarkably stable over extended culture in PBMCs. Two laboratory strains and five clinical isolates were evaluated in expanded studies of this phenomenon. While the neutralization characteristics of most of the strains studied were affected by the host cell in which the strain was propagated, two of the strains (one clinical isolate and one laboratory strain) appeared antigenically unaffected by their cell of origin. Host cell effect was also evident in neutralization by monoclonal antibodies directed against the CD4-binding region and the V2, V3, and gp41 regions. Possible mechanisms for this host cell effect include (i) mutation during passaging; (ii) selection in different host cells of different subpopulations of the (uncloned) viral stock; and (iii) cell-specific posttranslational modifications. To explore these possibilities, the V3 through V5 region of gp120 was sequenced in preparations made by passing VL069 into H9 cells and into PBMCs; HIVMN grown in CEM-SS cells and in PBMCs was also sequenced. In both cases, a few amino acid changes outside the V3 region were found. Studies are currently under way to assess the significance of these changes.     

中国盲走螨属Agilis群种类记述（蜱螨亚纲：植绥螨科）

本文新建立盲走螨属ａｇｉｌｉｓ群并限定了该群的主要特征,归纳了世界上已描述的８种,其中分布于我国的３种,此外描述了３个新种。     

武陵山地区鱼类寄生杆咽属线虫两新种

本文报道在武陵山地区的白甲鱼［（Ｖａｒｉｃｏｒｋｉｎｕｓ（Ｏｎｙｃｈｏｓｔｏｍａ）ｓｉｍｕｓ（ＳａｕｖａｇｅｅｔＤａｂｒｙ）］和沪溪直口峻（ＲｅｃｔｏｒｉｓｌｕｘｉｅｎｓｉｓＷｕｅｔＹａｏ）中发现的两种杆咽属（Ｒｈａｂｄｏｃｈｏｎａ）线虫新种,定名为白甲鱼杆咽线虫,新种（ＲｈａｂｄＯｃｈｏｎａｏｎｙｒｋｏｓｔｏｍｉｓｐ．ｎｏｖ．）和短咽杆咽线虫,新种（ＲｈａｂｄＯｃｈｏｎａｂｒｅｖｉｃｈｏｎａｓｐ．ｎｏｖ．）,并对两新种进行了测量和详细的描述。     

刺果番荔枝中的番荔枝内酯

从刺果番荔枝（Ａｎｎｏｎａ ｍ ｕｒｉｃａｔａ Ｌ．）的种子中分离到３ 个单四氢呋喃型番荔枝内酯类化合物,用波谱方法鉴定为海南哥纳香甲素（ｈｏｗ ｉｉｃｉｎ Ａ, Ｓ１３）、乙素（ｈｏｗ ｉｉｃｉｎ Ｂ, Ｓ５）和新化合物４－去氧海南哥纳香乙素（４－ｄｅｓｏｘｙｈｏｗ ｉｉｃｉｎ Ｂ, Ｓ２）。     

油松鳞叶中细胞核穿壁现象的初步研究

利用薄切片和超薄切片技术对油松衰老鳞叶中细胞核穿壁运动进行了观察研究。首次,细胞核内的染色质逐渐收缩集中,形成染色深的球状体,以后,细胞核逐渐与细胞壁接近。接着紧贴细胞壁的细胞核通过细胞壁上的通道或胞间连丝转移到相邻的细胞内,此外,还发现有多种其它的转移方式存在。研究结果表明细胞核的穿壁运动现象同时存在于连子植物和裸植物中,电镜观察进一步证明细胞壁道在细胞核穿壁之前已形成。     

Optimal door fitting with systematic fixture adjustment

A systematic approach is presented to obtain the best door gap quality through optimal door fitting in automobile body manufacturing. First, three indexes of gap quality are defined; they are: (1) door gap width deviation relative to design nominal; (2) door gap parallelism; and (3) car-to-car gap consistency. Then the door-fitting problem is formulated into a general constrained optimization problem. The effects of optimal door fitting on the three quality indexes are evaluated through computer simulation. These results provide a lower bound on the design of nominal door gap by considering process capability. Finally, a computer-aided fixture adjustment scheme is developed to orient a door in a body side opening to achieve the optimal fitting. The amount of adjustment, with the desired orientation obtained from optimization, is calculated based on parametrically modeled local surface features of the fixture and the door. The adequacy of door feature modeling is verified through a door-fitting experiment.     

霍山三种石斛与其栽培土壤中微量元素分布关系研究

本文应用灰色系统理论,对安徽霍山三种石斛与其栽培土壤中15种微量元素分布状况进行了关联分析．结果发现.其关联序为γ_根＞γ_叶＞γ_茎;γ_(-年茎)≈γ_(二年茎)≈γ_(三年茎);γ_(霍斛)＞γ_(铁斛)＞γ_(铜斛).可见霍山石斛与其栽培土壤间的微量元素相关性比其它石斛强,因而可通过增施微肥的办法来提高霍山石解中某些人体必需微量元素的含量．