An influenza A (H1N1) virus, closely related to swine influenza virus, responsible for a fatal case of human influenza.

In July 1991, an influenza A virus, designated A/Maryland/12/91 (A/MD), was isolated from the bronchial secretions of a 27-year-old animal caretaker. He had been admitted to the hospital with bilateral pneumonia and died of acute respiratory distress syndrome 13 days later. Antigenic analyses with postinfection ferret antisera and monoclonal antibodies to recent H1 swine hemagglutinins indicated that the hemagglutinin of this virus was antigenically related to, but distinguishable from, those of other influenza A (H1N1) viruses currently circulating in swine. Oligonucleotide mapping of total viral RNAs revealed differences between A/MD and other contemporary swine viruses. However, partial sequencing of each RNA segment of A/MD demonstrated that all segments were related to those of currently circulating swine viruses. Sequence analysis of the entire hemagglutinin, nucleoprotein, and matrix genes of A/MD revealed a high level of identity with other contemporary swine viruses. Our studies on A/MD emphasize that H1N1 viruses in pigs obviously continue to cross species barriers and infect humans.     

Rice Triosephosphate Isomerase Gene 5[prime] Sequence Directs [beta]-Glucuronidase Activity in Transgenic Tobacco but Requires an Intron for Expression in Rice

In rice (Oryza sativa L.), cytosolic triosephosphate isomerase (TPI) is encoded by a single gene. TPI catalyzes a vital step in glycolysis, and RNA blots showed that the tpi gene is expressed in all vegetative tissues (root, culm, and leaves) and in rice suspension cells. No effect of light on expression was detected, but submergence of rice seedlings resulted in elevated levels of TPI mRNA in roots and culms. The 2767-bp 5[prime] upstream sequence of the tpi gene was fused translationally with the [beta]-glucuronidase (gusA) gene, and the resulting construct, TPI-GUS, was found to express constitutive, high levels of GUS activity in transgenic tobacco (Nicotiana tabacum) plants. However, the same construct yielded no GUS activity in stably transformed rice plants, and RNA blots showed that no GUS mRNA could be detected even though stable integration of functional copies of the construct was confirmed by Southern blot and genomic polymerase chain reaction analyses. Transient assays using particle bombardment yielded high levels of GUS expression from the TPI-GUS construct in tobacco leaves, but essentially no expression in rice, barley, or maize leaves. When the first intron of the tpi gene was included in the construct (TPI-int1-GUS), transient GUS activity was routinely obtained in rice leaves, revealing that the first intron of the rice tpi gene is crucial for its expression in rice. TPI-int1-GUS also directed transient GUS expression in maize and barley leaves, but little or no activity was obtained from this construct in tobacco, tomato, or soybean leaves. These results with the rice tpi promoter are in accordance with mounting evidence that differences in gene expression exist between monocots and dicots.     

Endocytosis of 1,3-β-glucans by broad bean cells at the penetration site of the cowpea rust fungus (haploid stage)

Te penetration hypha of basidiospore-derived infection structures of the cowpea rust fungus (Uromyces vignae Barclay) in epidermal cells of the nonhost, broad bean (Vicia faba L.), was studied with the electron microscope after high-pressure freezing and freeze substitution. After fungal invasion of the epidermis, a plug in the penetration hypha separated the infection structures on the cuticle from the intraepidermal vesicle of the fungus. The plug and the fungal cell wall reacted with a polyclonal 1,3-β-glucan antibody. The plug in the haploid stage seems to have a task similar to the septum formed in the diploid stage of the fungus. Around the penetration hypha, the plant wall stained darkly and a papilla was deposited by the plant. In the papilla, 1,3-β-glucans were labelled by a monoclonal and a polyclonal antibody. In the infected epidermal cell, clathrin-coated pits, coated vesicles, partially coated reticula and multivesicular bodies were found. The contents of the coated pits, coated vesicles, partially coated reticula and multivesicular bodies bound to monoclonal and polyclonal 1,3-β-glucan antibodies. Accumulation and uptake of this paramural material into the plant cell by endocytosis is concentrated at the fungal penetration site. It may influence the host-parasite interaction.     

Isolation and Characterization of the Plasma Membrane by Two-Phase Partitioning from the Alkalophilic Cyanobacterium Spirulina platensis

Partition in aqueous dextran-polyethylene glycol two-phase systemwas used to isolate the plasma membranes from the alkalophiliccyanobacterium Spirulina platensis. The upper phase containeda colorless membranes obtained in relatively short time, 3–4h. This fraction had a different protein profile than that ofthe thylakoid fraction obtained in the lower phase. It did notcontain cytochrome c-oxidase activity, but retained characteristicMg²⁺-ATPase activity that is sensitive to vanadate, stimulatedby K⁺, and has a pH optimum near 8.5. These data support ourassumption that the upper phase of the gradient consist of theplasma membrane of S. platensis. (Received November 25, 1993; Accepted April 12, 1994)     

Transfection of the mouse ICAM-1 gene into murine neuroblastoma enhances susceptibility to lysis,reduces in vivo tumorigenicity and decreases ICAM-2-dependent killing

We determined the expression of intercellular adhesion molecules (ICAM) on neuro-2a cells in order to evaluate whether they were involved in cytolysis of murine neuroblastoma. Fluorescence-activated cell sorting analysis revealed that the control neomycin-resistance-genetransduced line (neuro-2a/LN) had poor expression of ICAM-1 (mean channel fluorescence, MCF=3.7). An ICAM-1-positive transfectant of neuro-2a (neuro-2a/ICAM-1⁺) (CMF=64.3) was generated to evaluate directly the role of this adhesion molecule in cytolysis. Neuro-2a/ICAM-1⁺ was more sensitive to LAK killing (69.7% at an effector-to-target ratio of 1001) compared to neuro-2a/LN (48.6%) (P<0.001). Blocking of neuro-2a/LN and neuro-2a/ICAM-1⁺ lysis with anti-ICAM-1 monoclonal antibodies (mAbs) did not account for all the LFA-1-dependent killing. These data indicate that even in neuro-2a/ICAM-1⁺ cells, other LFA-1 ligands participated in the effector-target interaction. Therefore, we examined these cell lines for ICAM-2 expression. Both neuro-2a/LN and neuro-2a/ICAM-1⁺ lines expressed ICAM-2 (MCF=16.4 and 16.5). ICAM-2 accounted for the majority of the LFA-1-dependent killing in the ICAM-1-negative target, neuro-2a/LN, while ICAM-1 played a primary role in the cytolysis of the ICAM-1⁺ transfectant. Inhibition of lysis in the presence of anti-ICAM-1 and ICAM-2 mAbs was comparable to that seen with the addition of anti-LFA-1 mAb, indicating that other LFA-1 ligands were not involved in this system. ICAM-1 expression was associated with decreased in vivo tumorigenicity; mice inoculated with neuro-2a/ICAM-1⁺ cells had a significantly longer survival compared to those receiving neuro-2a/LN cells (median survival time 35.5 versus 24.5 days) (P<0.001). It is important to note that ICAM-1 transfection of murine neuroblastoma did not alter its metastatic potential. We conclude that transfection of mouse neuroblastome with ICAM-1 increases its sensitivity to in vitro lysis and reduces its in vivo tumorgenicity. In ICAM-1-negative murine neuroblastoma cells, ICAM-2 plays a primary role in cell-mediated lysis.This work was supported in part by the Children's Cancer Research Fund, the Minnesota Medical Foundation, the Viking Children's Fund and NIH grants PO1-CA-21737, NO1-AI-85002. E. K. is a recipient of the Irvine McQuarrie Research Scholar Award and B. R. B. a recipient of the Edward Mallinkrodt Foundation Scholar Award     

高粱蚜灰色灾变长期预测模型

本文应用灰色系统灾变预测理论建立了吕梁地区高粱蚜发生量预测模型．     

百合离体生殖细胞骨架的扫描电镜观察

从百合的花粉管分离出来的生殖细胞,经表面活化剂Ｔｒｉｔｏｎ Ｘ－１００ 及核糖核酸酶、硫酸铵离析处理。离析后的细胞经临界点干燥,扫描电镜观察显示：在离体生殖细胞的胞质内有一个非常复杂的支架网络系统。这一网络系统有内外两层：外层（靠近细胞膜）网络结构紧密,纤维束粗长;内层（靠近核）网络结构疏松,纤维束短细。一些间接证据显示,这一支架网络系统可能为微管骨架     

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）。     

Direct and sensitive fluorescence in situ hybridization of 45S rDNA on tomato chromosomes.

We describe a direct and sensitive fluorescence in situ hybridization protocol for plant chromosomes. We labelled 45S rDNA with fluorescein-12-dUTP and hybridized to somatic chromosomes of four tomato genotypes. This technique does not require posthybridization immunocytochemical amplifications. The improved signal sensitivity with this technique allowed identification of new rDNA loci on three pairs of chromosomes, in addition to the previously known locus on chromosome 2. We discuss favorable features of direct fluorescence in situ hybridization for chromosomes fixed on a slide and chromosomes or cells in suspension.     

Zn2＋参与遗传调控的研究进展

Zn^2＋在遗传调控中的作用十分广泛而显著.结合新近的研究资料,着重从染色质结构与功能、核酸的生物合成、DNA的结构及构象、基因表达的调控等四个主要方面来反映Zn^2＋与遗传调控的相关性,并阐述Zn^2＋在其中发挥作用的机理.