Nonuniform spatial patterns of respiratory activity within biofilms during disinfection.

Fluorescent stains in conjunction with cryoembedding and image analysis were applied to demonstrate spatial gradients in respiratory activity within bacterial biofilms during disinfection with monochloramine. Biofilms of Klebsiella pneumoniae and Pseudomonas aeruginosa grown together on stainless steel surfaces in continuous-flow annular reactors were treated with 2 mg of monochloramine per liter (influent concentration) for 2 h. Relatively little biofilm removal occurred as evidenced by total cell direct counts. Plate counts (of both species summed) indicated an average 1.3-log decrease after exposure to 2 mg of monochloramine per liter. The fluorogenic redox indicator 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and the DNA stain 4',6-diamidino-2-phenylindole (DAPI) were used to differentiate respiring and nonrespiring cells in biofilms. Epifluorescence micrographs of frozen biofilm cross sections clearly revealed gradients of respiratory activity within biofilms in response to monochloramine treatment. These gradients in specific respiratory activity were quantified by calculating the ratio of CTC and DAPI intensities measured by image analysis. Cells near the biofilm-bulk fluid interface lost respiratory activity first. After 2 h of biocide treatment, greater respiratory activity persisted deep in the biofilm than near the biofilm-bulk fluid interface.     

杨树新品种叶肉原生质体培养和植株再生

从１ 个月龄的ＮＬ－８０１０６ 杨（Ｐｏｐｕｌｕｓｄｅｌｔｏｉｄｅｓ×Ｐ． ｓｉｍ ｏｎｉｉ）无菌苗叶片分离得到大量原生质体,纯化后其原生质体产量为４×１０７／ｇ ｆｒ．ｗ ｔ． 纯化的原生质体在含２,４－Ｄ ２ ｍ ｇ／Ｌ、ＮＡＡ ０．５ ｍ ｇ／Ｌ和ＫＴ ０．５ ｍ ｇ／Ｌ的ＫＭ８ｐ 和ＭＳ培养基中进行高密度液体浅层培养,渗透势为０．４０ ｍ ｏｌ／Ｌ的ＫＭ８ｐ 培养基中原生质体分裂频率最高． 培养第５ 天观察到第一次细胞分裂,培养１０ ｄ 的分裂频率为４．５％ ,１２ 周内可形成大量的细胞团和小愈伤组织． ＮＬ－８０１０６杨叶肉原生质体在富含有机氮并以葡萄糖为碳源的培养基中具有较高的分裂频率和植板率．小愈伤组织在ｇｅｌｒｉｔｅ 固化的ＮＬＺ１ 培养基上增殖生长,３ 周后形成４—６ ｍ ｍ 结构紧密的鲜红色愈伤组织,转至ＮＬＦ分化培养基,分化成苗率为１００％ ． 待芽伸长到３ ｃｍ 时,从基部切下转至１／２ ＭＳ培养基上诱导生根,形成完整植株     

Pharmacokinetics of anti-ganglioside GD2 mAb 14G2a in a phase I trial in pediatric cancer patients

A phase I trial of a murine anti-ganglioside (GD2) monoclonal antibody (mAb) 14G2a was conducted in 14 neuroblastoma patients and 1 osteosarcoma patient to assess its safety, toxicity and pharmacokinetics in pediatric patients. The pharmacokinetics of mAb 14G2a were biphasic with at ₁ ^2/ of 2.8±2.8 h and at ₁ ^2/ of 18.3±11.8 h. In general,t ₁ ^2/ was dose-dependent with a level of significance ofP=0.036, and it reached a plateau at doses of 250 mg/m² or more. Overall the peak serum levels were dose-dependent atP<0.001. However, they demonstrated an abrupt increase between doses of 100 mg/m² and 250 mg/m². The latter two suggest a saturable mechanism for mAb elimination. In addition, peak serum concentrations were observed earlier at higher mAb doses, which indicates the achievement of a steady state. Thet ₁ ^2/ of mAb 14G2a in children appears to be shorter than in adults. Furthermore, 2 patients demonstrated a considerable decrease int ₁ ^2/ following retreatment with 14G2a. This was paralleled by high human anti-(mouse Ig) antibody levels. This study represents the first comprehensive analysis of murine mAb pharmacokinetics in children and will be useful in the future design of mAb therapy.This work was supported by grants from FDA, FD-R-000377 and NIH U10 CA 28439 and in part by a grant from the general Clinical Research Center program, MOI RR00827, of the National Center for Research Resources, National Institutes of Health. M. M. U.-F. and C.-S. H. were supported in part by a grant from the Children's Cancer Research Foundation, and R. A. R. was supported in part by NIH grant CA 42508     

Human DNA helicase IV is nucleolin, an RNA helicase modulated by phosphorylation

The cDNA encoding human DNA helicase IV (HDH IV), a 100-kDa protein which unwinds DNA in the 5′ to 3′ direction with respect to the bound strand, was cloned and sequenced. It was found to be identical to the human cDNA encoding nucleolin, a ubiquitous eukaryotic protein essential for pre-ribosome assembly. HDH IV/nucleolin can unwind RNA-RNA duplexes, as well as DNA-DNA and DNA-RNA duplexes. Phosphorylation of HDH IV/nucleolin by cdc2 kinase and casein kinase II enhanced its unwinding activity in an additive way. The Gly-rich C-terminal domain possesses a limited ATP-dependent duplex-unwinding activity which contributes to the helicase activity of HDH IV/nucleolin.     

High-level 2H/13C/15N labeling of proteins for NMR studies

Summary The protein human carbonic anhydrase II (HCA II) has been isotopically labeled with ²H, ¹³C and ¹⁵N for high-resolution NMR assignment studies and pulse sequence development. To increase the sensitivity of several key ¹H/¹³C/¹⁵N triple-resonance correlation experiments, ²H has been incorporated into HCA II in order to decrease the rates of ¹³C and ¹H_N T₂ relaxation. NMR quantities of protein with essentially complete aliphatic ²H incorporation have been obtained by growth of E. coli in defined media containing D₂O, [1,2-¹³C₂, 99%] sodium acetate, and [¹⁵N, 99%] ammonium chloride. Complete aliphatic deuterium enrichment is optimal for ¹³C and ¹⁵N backbone NMR assignment studies, since the ¹³C and ¹H_N T₂ relaxation times and, therefore, sensitivity are maximized. In addition, complete aliphatic deuteration increases both resolution and sensitivity by eliminating the differential ²H isotopic shift observed for partially deuterated CH_nD_m moieties.     

Water molecules participate in proteinase-inhibitor interactions: crystal structures of Leu18, Ala18, and Gly18 variants of turkey ovomucoid inhibitor third domain complexed with Streptomyces griseus proteinase B.

Crystal structures of the complexes of Streptomyces griseus proteinase B (SGPB) with three P1 variants of turkey ovomucoid inhibitor third domain (OMTKY3), Leu18, Ala18, and Gly18, have been determined and refined to high resolution. Comparisons among these structures and of each with native, uncomplexed SGPB reveal that each complex features a unique solvent structure in the S1 binding pocket. The number and relative positions of water molecules bound in the S1 binding pocket vary according to the size of the side chain of the P1 residue. Water molecules in the S1 binding pocket of SGPB are redistributed in response to the complex formation, probably to optimize hydrogen bonds between the enzyme and the inhibitor. There are extensive water-mediated hydrogen bonds in the interfaces of the complexes. In all complexes, Asn 36 of OMTKY3 participates in forming hydrogen bonds, via water molecules, with residues lining the S1 binding pocket of SGPB. For a homologous series of aliphatic straight side chains, Gly18, Ala18, Abu18, Ape18, and Ahp18 variants, the binding free energy is a linear function of the hydrophobic surface area buried in the interface of the corresponding complexes. The resulting constant of proportionality is 34.1 cal mol-1 A-2. These structures confirm that the binding of OMTKY3 to the preformed S1 pocket in SGPB involves no substantial structural disturbances that commonly occur in the site-directed mutagenesis studies of interior residues in other proteins, thus providing one of the most reliable assessments of the contribution of the hydrophobic effect to protein-complex stability.     

银杏速生早实示范栽培试验

本研究是在我区银杏主产区兴安进行的８０多亩,３０００多株的示范栽培试验。其综合技术措施是选用良种嫁接苗、适当密植、配置雄株、整形修剪、合理施肥、防治病虫害及促花早实等。种后５—６年取得速生、早实、高产的良好效果。     

互叶白千层油化学成分的研究

采用水蒸汽蒸馏收集互叶白千层芳香油,对该油进行ＧＣ／ＭＳ／ＤＳ定性分析及其总离于流图的面积归一化定量分析,鉴定出２５种化合物,其中含氧化合物６种,碳氢化合物１９种。直接影响该油商品价值的化学成分４－萜品醇含量约为１７％,桧樟脑含量约为２．４％。     

鹅掌楸属植物引导组织和花粉管生长

应用光学显微镜和常规石蜡切片技术研究了鹅掌楸属（ＬｉｒｉｏｄｅｎｄｒｏｎＬ．）两种植物雌蕊引导组织的分布和个体发育,引导组织是由心皮边缘或内表面的表皮细胞层或亚细胞层发育形成,是由一层细胞组成的连续层,覆盖干柱头、花柱道和珠柄的表面,引导组织的细胞形态学因其所在部位不同而有差异。在电境水平上研究了柱头和花柱引导组织的超微结构,引导组织细胞是分泌型的传递细胞,其分泌面发育了明显的壁内突,细胞质中富含内质网、多聚核糖体、各种小泡、高尔基体和线粒体,大液泡通常远离分泌面。文中还探讨了花粉管生长后引导组织的变化。     

新疆10种沙生植物旱生结构的解剖学研究

新疆１０种沙生植物的形态解剖研究表明,它们为适应沙生环境形态结构发生变化。叶器官的形态呈三种类型：叶片退化成膜质或鳞片状,而由同化枝执行光合功能;叶片上下都具栅栏组织,表皮角质膜厚,表皮毛发达,气孔下陷,输导组织和机械组织都发达;叶片肉质化,叶肉组织不分化,贮水组织发达而输导组织不发达。轴器官中厚壁组织发达,围绕维管组织,维管组织内部也有发达的厚壁组织。根中普遍具有周皮,一些植物存在异常的维管组织,部分植物还具有粘液细胞或结晶。沙生植物形成各种旱生结构,以不同的方式适应沙生环境。