PCR法快速检测临床标本中结核杆菌DNA

应用聚合酶链反应（ＰＣＲ）快速检测临床标本（脑脊液、胸水、腹水、血、痰液）中的结核杆菌ＤＮＡ,特异性扩增片段１２３ｂｐ,为结核杆菌的特异性重复序列ＩＳ６１１０部分基因。ＰＣＲ检测人型结核杆菌的敏感性达１０ｆｇＤＮＡ。临床标本的ＰＣＲ检测阳性率（２３．３％）明显高于抗酸染色涂片（２．９％）和细菌培养（５．７％）的阳性率（Ｐ〈０．０５）。通过设立对照系统及对扩增产物酶切分析,表明该法无假阴性结果（特异     

野生紫斑牡丹和四川牡丹种子萌发特性及与其致濒的关系

野生牡丹种子一般较小,而且不同产地之间形状、大小差异较大。其萌发特性与栽培牡丹相比也有较大差异：萌发期长达半年以上,且萌发温度在１０～１５℃为宜,超过２０℃则明显不利于生根及上胚轴生长。四个不同分布地的四川牡丹种子萌发率较一致,均在６０～７７％之间。三个不同产地的紫斑牡丹种子萌发率则相差甚远,分布于甘肃文县的萌发率达７６％,而分布于陕西略阳和湖北神农架的萌发率则分别只有１２％和４．４％,出苗率则更低。本文认为紫斑牡丹的种子特性是其在自然界处于濒危状态的重要原因之一。     

Colocalization of NADPH-diaphorase activity and certain neuropeptides in the esophagus of opossum (Didelphis virginiana)

Nitric oxide and various neuropeptides in the myenteric plexus regulate esophageal motility. We sought colocalization of nitric oxide synthase and neuropeptides in frozen sections of mid-portion of smoothmuscled opossum esophagus using NADPH-diaphorase activity to mark the synthase and immunoreactivity to detect peptides. The peptides, all with demonstrated physiological activity in this organ, were calcitonin generelated peptide, galanin, neuropeptide Y, substance P, and vasoactive intestinal polypeptide. The ExtrAvidin Peroxidase immunostain for each peptide was carried up to the final peroxidase reaction with 3-amino-9-ethylcarbazole. The NADPH-diaphorase reaction was applied with short incubation to provide light staining just before the peroxidase reaction was performed. We examined sections for the proportions of singly and dually labeled nerve cells in the myenteric plexus. NADPH-diaphorase activity was highly colocalized with calcitonin gene-related peptide (59%), galanin (54%), and vasoactive intestinal polypeptide (53%). It showed little colocalization with neuropeptide Y (10%) and substance P (8%). The proportions of all nerve cells containing each of the substances were: NADPH-diaphorase-33%, calcitonin gene-related peptide-30%, galanin-55%, neuropeptide Y-16%, substance P-35%, and vasoactive intestinal polypeptide-58%. We conclude that the nerves responsible for peristalsis in the esophagus may act by releasing nitric oxide along with other inhibitory substances, calcitonin gene-related peptide, galanin, and vasoactive intestinal polypeptide, but not excitatory substances, neuropeptide Y and substance P.     

Nanometric design of extraordinary hydrophobic-induced pKa shifts for aspartic acid: Relevance to protein mechanisms

Commonly a key element enabling proteins to function is an amino acid residue or residues with functional side chains having shifted pKa values. This article reports the results on a set of protein-based polymers (model proteins) that exhibit hydrophobic folding and assembly transitions, and that have been designed for the purpose of achieving large hydrophobic-induced pKa shifts by selectively replacing Val residues by Phe residues. The high molecular weight polypentapeptides, actually poly (tricosapeptides) with six varied pentamers in fixed sequence, were designed and synthesized to have the same amino acid compositions but different proximities between a single aspartic acid residue and 5 Phe residues per 30 residues. With the 5 Phe residues distal from the Asp residue, the observed pKa shift was 2.9 when compared to the Val-containing reference. With the 5 Phe residues within 1 nm of the Asp residue, the pKa shift was 6.2. This represents a free energy of interaction of 8 kcal/moles. To our knowledge, this is the largest pKa shift documented for an Asp residue in a polypeptide– or protein–water system. Data are reviewed that do not support the usual electrostatic arguments for pKa shifts of charge–charge repulsion and/or unfavorable ion self-energies arising from displacement of water by hydrophobic moieties, but rather the data are interpreted to indicate the presence of an apolar–polar repulsive free energy of hydration, which results from a potentially highly cooperative competition between apolar and polar species for hydration. © 1994 John Wiley & Sons, Inc.     

Agents that Promote Protein Phosphorylation Inhibit the Activity of the Na+/Ca2+ Exchanger and Prolong Ca2+ Transients in Bovine Chromaffin Cells

Abstract: The Na⁺/Ca²⁺ exchanger is an important element in the maintenance of calcium homeostasis in bovine chromaffin cells. The Na⁺/Ca²⁺ exchanger from other cell types has been extensively studied, but little is known about its regulation in the cell. We have investigated the role of reversible protein phosphorylation in the activity of the Na⁺/Ca²⁺ exchanger of these cells. Cells treated with 1 m M dibutyryl cyclic AMP (dbcAMP), 1 µ M phorbol 12,13-dibutyrate, 1 µ M okadaic acid, or 100 n M calyculin A showed lowered Na⁺/Ca²⁺ exchange activity and prolonged cytosolic Ca²⁺ transients caused by depolarization. A combination of 10 n M okadaic acid and 1 µ M dbcAMP synergistically inhibited Na⁺/Ca²⁺ exchange activity. Conversely, 50 µ M 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine, a protein kinase inhibitor, enhanced Na⁺/Ca²⁺ exchange activity. Moreover, we used cyclic AMP-dependent protein kinase and calcium phospholipid-dependent protein kinase catalytic subunits to phosphorylate isolated membrane vesicles and found that the Na⁺/Ca²⁺ exchange activity was inhibited by this treatment. These results indicate that reversible protein phosphorylation modulates the activity of the Na⁺/Ca²⁺ exchanger and suggest that modulation of the exchanger may play a role in the regulation of secretion.     

Differential expression inArabidopsis ofLhca2, a PSI cab gene

A cDNA clone of the geneLhca2 encoding a photosystem I (PSI) type II chlorophylla/b-binding protein was isolated fromArabidopsis thaliana. The isolation of this, the fourth PSI cab gene fromArabidopsis, confirms a previous report [1] that indicatedArabidopsis may contain all four PSI cab genes identified in other plant species.Lhca2 is a single-copy gene as are the other knownArabidopsis PSI cab genes. The patterns of developmental expression and tissue-specific regulation ofLhca2 are similar to those of other PSI and PSII cab genes, but the light induction pattern and the steady-state mRNA level ofLhca2 are distinct. This suggests that a different mechanism may be employed to regulate the expression ofLhca2.     

Effect of heavy metals on the methanogenic activity of starch-degrading granules

Summary Heavy metals in electroplating effluent inhibited specific methanogenic activity (SMA) of anaerobic starch-degrading granules. The SMA of granules on the degradation of starch were reduced by 50% when each gram of biomass was in contact individually with 105 mg of zinc, 120 mg of nickel, 180 mg of copper, 310 mg of chromium, or >400 mg of cadmium. Granules had higher toxicity-resistance than flocculent sludge, due to their layered structure.     

Studies on yeast host strains for heterologous P450 expression

The Saccharomyces cerevisiae strain AH22 was capable of human P4501A1 expression without detectable background of yeast P450, unlike ATCC44773. Repeated backcrossing to AH22 produced a strain allowing transformation by vectors carrying various common selectable markers. Background yeast xenobiotic metabolism was observed only with growth on complex medium.     

从水稻根部悬浮培养细胞分离原生质体及植株再生

以长香稻(Oryza sativa L．)(糯稻)的幼嫩种子根为材料,在Ms和N6培养基上诱导产生结构松软而分散的愈伤组织,经过AA液体培养基振荡悬浮培养,悬浮培养细胞经酶解后得到了活性较高的原生质体,试验结果表明这是分离原生质体较理想的材料。在附加2,4-D lmg／L(以下单位同)、KT(激动素)0．2、各氨酰胺876、天门冬酰胺266的Ms琼脂糖培养基中,诱导出了大量愈伤组织,在含KT2、NAA(α-萘乙酸)0．2、zT(玉米素)0．2、cH(水解酪蛋白)1000和4％椰子汁的N6培养基中成功地诱导出了由原生质体再生的植株。当代原生质体再生植株能正常开花、结实、产生种子;染色体数均为二倍性(2n＝24),最显著的特点是结实率低,穗粒数减步、生育期延迟。     

陕西省腹菌纲真菌的聚类分析

对产于陕西省的腹菌纲真菌,共４２个ＯＴＵ＇Ｓ和３６个性状,进行了Ｑ模式聚类分析,结果表明：（１）４２个ＯＴＵ＇Ｓ明显的分为六大类群,与Ｄｒｉｎｇ（１９７３）系统的６个目相吻合。（２）栓皮马勃属与灰包科中包被具拟薄壁层的属相似性较小,支持Ｈａｗｋｓｗｏｒｔｈｅｔａｌ（１９８３）将其作为科级处理的观点。（３）作者认为鬼笔属和竹荪属作为两个独立属处理比较合适。