Response ofPhloeotribus scarabaeoides (Coleoptera,Scolytidae) to ethylene in an olfactometer

The role of ethylene, pure or in formulation, in the colonization behaviour of the olive bark beetle,Phloeotribus scarabaeoides (Coleoptera, Scolytidae) has been investigated in the laboratory. Ethylene has been found to be attractive in both sexes; the formulation ethrel 48 was active in an olfactometer up to several months. Ethylene, whose concentration varies with the developmental stage or the condition of the tree or its wood, may play an important role in the primary attraction of these scolytids to their host.     

Synergistic effect of acute hypoxia on flow-induced release of ATP from cultured endothelial cells

Human umbilical vein endothelial cells (HUVECs) in primary cultures were perfused under normoxic or hypoxic conditions. These cells were stimulated twice for 3 min by increased flow (from 0.5 to 3.0 ml/min). Under hypoxic conditions the basal release of ATP was the same as under normoxic conditions, but during increased flow the release was greater (0.58±0.07>0.32±0.04 pmoles/ml/10⁶ cells (+78%), for the first period of stimulation; 0.39±0.05>0.22±0.03 pmoles/ml/10⁶ cells (+79%) for the second period). Further experiments with sequential increments in flow rate showed that under both normoxic and hypoxic conditions, a positive correlation existed between ATP release and the rate of flow but there was always more ATP released under hypoxic conditions regardless of the flow rate.HUVECs in secondary culture (second passage) were similarly stimulated. No differences were observed between normoxic and hypoxic conditions. In both cases, the quantity of ATP released during high flow (0.050±0.004 pmoles/ml/10⁶ cells) was significantly smaller than the quantity of ATP released during low flow (0.09±0.01 pmoles/ml/10⁶ cells).To conclude, since hypoxia alone did not affect ATP release, there appears to be a synergistic relationship between increased shear stress and hypoxia in the stimulation of ATP release from HUVECs. Moreover, the release of ATP under these conditions seems to be a property of highly differentiated endothelial cells.     

龙门山茂汶─汶川变质带构造特征研究

龙门山中段茂汶─汶川韧性剪切带中可见到绿片岩相到角闪岩相的古生界。该地的巴罗型中压变质相相当于松潘—甘孜褶皱带中地壳的绿泥石带，构成了北东—南西向的茂汶—汶川变质带。雪隆包花岗岩体正位于该变质带的中心部位。三次韧性变形作用（Ｄ１～Ｄ３）造就了印支褶皱带，并在三叠纪末末形成了松潘—甘孜褶皱带。Ｄ１变形作用为北东—南西向的挤压作用和冲断作用，形成了大型的等斜褶皱，使古生界缩短和加厚。在持续的Ｄ２北京—南西向挤压作用下，松潘—甘孜褶皱带和稳定的扬子克拉通之间的差异应变由茂汶—汶川剪切带中非同轴左旋剪切作用所容纳。雪隆包花岗岩体是在Ｄ２变形作用的晚期侵入到剪切带的。产生蓝晶石的变质条件也是在Ｄ２或Ｄ２变形作用后出现的。Ｄ３变形作用为北西—南东向挤压，在局部地方形成糜棱岩状的道冲剪切带。这些特征与绿泥石退变质作用有关，揭示出在Ｄ３变形期间茂汶—汶川变质带有较大幅度的隆升。尽管雪隆包岩体在空间上与茂汶—汶川变质带有关，但作者认为其变质作用是岩层加厚引起的热作用重新达到平衡的产物，而不是由侵入作用引起的热接触变质作用。然而，与岩浆作用伴生的高温和活动性流体仍是产生Ｄ３局部变形和雪隆包岩体隆升的原因，这也是局部出现角闪告相     

贵州植物园珍稀濒危蕨类植物

本文介绍引种自贵州各地及我国华中、华东和华东的贵州植物园内的珍稀濒危蕨类植物。除列表表示来源、现状等情况外，还对桫椤Ａｌｓｐｈｉｌａ ｓｐｉｎｕｌｏｓａ （Ｈｏｏｋ）Ｔｒｙｏｎ，扇蕨Ｎｅｏｃｈｅｉｒｏｐｔｅｒｉｓ ｐｌａｍａｔｏｐｅｄａｔａ （Ｂａｋ．）Ｃｈｓｉｓｔ，宽叶水韭Ｉｓｏｅｔｅｓ ｊａｐｏｎｉｃａ Ａ．Ｂｒ．，中华水韭Ｉ．ｓｉｎｅｎｓｉｓ Ｐａｌｍｅｒ和截基盾蕨Ｎｅｏｌｅｐｉｓｏｒｕｓ     

铬酸钒为基的PTC陶瓷的研究

本文使用ＳＥＭ、ＥＤＳ、ＥＡＳ、ＸＲＤ和电阻率测量技术，研究了工艺参数和加入（Ｃｏ，Ｆｅ２Ｏ３）对ＰＴＣ（Ｖ１－ｘ，Ｃｒｘ）２Ｏ３陶瓷的显微结构和电性能的影响。实验结果表明，为了制造优良性能、高可靠的热敏电阻器，必须精确控制陶瓷组份和工艺。引人象Ｃ。这样的添加物是重要的，它主要以金属形式分布在基体中，同时发现添加物对试样致密度和电性能的影响也是有益的。     

Alpha 1-adrenoceptor subtypes linked to different mechanisms for increasing intracellular Ca2+ in smooth muscle

Receptor-mediated increases in intracellular Ca2+ levels can be caused by release from intracellular organelles and/or influx from the extracellular fluid. Noradrenaline (NA) released from sympathetic nerves acts on alpha 1-adrenoceptors to increase cytosolic Ca2+ and promote smooth muscle contraction. In many cells activation of alpha 1-adrenoceptors causes formation of inositol 1,4,5-trisphosphate which promotes Ca2+ release from intracellular stores. The mechanism by which receptor activation opens cell surface Ca2+ channels is not known, although in some cases it may be secondary to formation of inositol phosphates or release of stored intracellular Ca2+ (ref. 3). However, alpha 1-adrenoceptors have recently been shown to have different pharmacological properties in different tissues, and it has been proposed that different alpha 1-adrenoceptor subtypes may control mobilization of intracellular Ca2+ and gating of extracellular Ca2+ influx. We here report evidence for two subtypes of alpha 1-adrenoceptors which cause contractile responses through different molecular mechanisms. One subtype stimulates inositol phosphate (InsP) formation and causes contractions which are independent of extracellular Ca2+, and the other does not stimulate inositol phosphate formation and causes contractions which require the influx of extracellular Ca2+ through dihydropyridine-sensitive channels. These results suggest that neurotransmitters and hormones may control Ca2+ release from intracellular stores and influx through voltage-gated membrane channels through distinct receptor subtypes.     

Monoclonal antibody and ligand binding sites of the T cell erythrocyte receptor (CD2)

The human T cell erythrocyte receptor (CD2 antigen) allows thymocytes and mature T cells to adhere to thymic epithelium and target cells through a cell surface protein, LFA-3 (refs 1-6). Monoclonal antibodies recognizing CD2 can either block adhesion or, in certain combinations, induce an antigen-independent T cell activation. We have identified the binding sites for 16 monoclonal antibodies against CD2 by a rapid and generally applicable mutational analysis. The binding sites fall in three discrete regions: antibodies that participate in activation and block erythrocyte adhesion bind to the first region; antibodies that block adhesion bind to the second region; and antibodies that participate in activation but do not block adhesion bind to the third region. A large number of mutations selected for loss of antibody reactivity in the first two regions also weaken the CD2-LFA-3 interaction. Good agreement was observed between mutational lesions blocking LFA-3 binding and lesions blocking binding by activating antibodies, which supports the view that such antibodies induce T cell activation by mimicking the effect of LFA-3 binding. CD2 sequences that participate in LFA-3 binding correspond to immunoglobulin variable region hypervariable sequences when the homologous domains are aligned.     

Cloning of decay-accelerating factor suggests novel use of splicing to generate two proteins

Decay-accelerating factor (DAF), a glycoprotein that is anchored to the cell membrane by phosphatidylinositol, binds activated complement fragments C3b and C4b, thereby inhibiting amplification of the complement cascade on host cell membranes. Here, we report the molecular cloning of human DAF from HeLa cells. Analysis of DAF complementary DNAs revealed two classes of DAF messenger RNA, one apparently derived from the other by a splicing event that causes a coding frameshift near the C terminus. The apparent 'intron' sequence contains an Alu family member and encodes contiguous protein sequence. Two DAF proteins are therefore possible, having divergent C-terminal domains which differ in their hydrophobicity. Both mRNAs are found on polysomes, suggesting that both are translated. We propose that the major (90%) spliced DAF mRNA encodes membrane-bound DAF whereas the minor (10%) unspliced DAF mRNA may encode secreted DAF and we present expression data supporting this. The deduced DAF sequence contains four repeating units homologous to a consensus repeat found in a recently described family of complement proteins.     

Activation of a G protein promotes agonist responses to calcium channel ligands

The activation of a guanine nucleotide binding (G) protein is an essential step in coupling certain receptors to the inhibition of voltage-activated calcium channels. We have previously observed that analogues of GTP potentiate the effect of receptor agonists and inhibit calcium currents in cultured dorsal root ganglion (DRG) neurones. A residual sustained 'L-type' component of the calcium channel current is resistant to inhibition by internal guanosine 5'-O-3-thiotriphosphate (GTP-gamma-S). Because calcium channel antagonists such as D600, nifedipine and diltiazem inhibit L currents, we examined their effect on GTP-gamma-S-modified currents. These compounds all produced a rapid and very marked potentiation of calcium channel currents in the presence of internal GTP-gamma-S and this effect was prevented by pertussis toxin which ADP ribosylates the G proteins Gi/Go (for review see ref. 10). We suggest that this potentiation indicates that activated G protein can interact with the calcium channel, and that this enhances the action of calcium channel ligands at their agonist sites on the channel in its resting state. These results represent the first electrophysiological evidence that guanine nucleotides are able to influence cellular responses to calcium channel ligands.     

An AIDS-related cytotoxic autoantibody reacts with a specific antigen on stimulated CD4+ T cells

Patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related conditions are known to have abnormalities of T cell subpopulations, including a decreased helper/inducer (bearing the CD4 antigen) to suppressor/cytotoxic (bearing the CD8 antigen) T cell ratio and decreased absolute numbers of T cells with the CD4+ phenotype. Infection of T cells with a retrovirus, termed human immunodeficiency virus (HIV), is thought to be important in these abnormalities. HIV infection alone does not adequately explain the CD4+ T-cell abnormalities seen in AIDS, however, and the nature of T-cell destruction in this disease remains poorly characterized. Here we describe an AIDS-related serum autoantibody that reacts with an antigen of relative molecular mass 18,000 (Mr 18K) restricted to lectin-stimulated or HIV-infected CD4+ T cells. The antibody also suppresses proliferation of CD4+ T cells in vitro and induces cytotoxicity of these cells in the presence of complement. Its role in the development of AIDS merits attention.