Bafilomycin A1 Inhibits the Action of Tetanus Toxin in Spinal Cord Neurons in Cell Culture

Abstract: Tetanus toxin (TeNT) is one of the clostridial neurotoxins that act intracellularly to block neurotransmitter release. However, neither the route of entry nor the mechanism by which these toxins gain access to the neuronal cytoplasm has been established definitively. In murine spinal cord cell cultures, release of the neurotransmitter glycine is particularly sensitive to blockade by TeNT. To test whether TeNT enters neurons through acidic endosomes or is routed through the Golgi apparatus, toxin action on potassium-evoked glycine release was assayed in cultures pretreated with bafilomycin A1 (baf A1) or brefeldin A (BFA). baf A1, which inhibits the vacuolar-type H⁺-ATPase responsible for endosome acidification, diminishes the staining of acidic compartments and interferes with the action of TeNT in a dose-dependent manner. TeNT blockade of evoked glycine release is inhibited by 50 and 90% in cultures pretreated with 50 and 100 n M baf A1, respectively, compared with cultures treated with the inhibitor alone. The effects of baf A1 are fully reversible. In contrast, BFA, which disrupts Golgi function, has no effect on TeNT action. These findings provide evidence that TeNT enters the neuronal cytoplasm through baf A1-sensitive acidic compartments and that TeNT is not trafficked through the Golgi apparatus before its translocation into the neuronal cytosol.     

Protochlorophyllide forms in non-greening epicotyls of dark-grown pea (Pisum sativum)

Low-temperature fluorescence emission spectra of 6.5-day-old dark-grown epicotyls of pea ( Pisum sativum ) revealed the presence of protochlorophyll(ide). The upper part of the epicotyl contained 30% of the protochlorophyll(ide) content per fresh weight found in pea leaves, whereas the lower part contained 3%. Three discrete spectral forms of protochlorophyll(ide) were clearly distinguished after Gaussian deconvolution of fluorescence excitation and emission spectra. Adding the satellite bands of the Qy_(0-0) transitions (the emission vibrational (Emv) bands with correlated amplitudes, gave the following delineation: Ex439–Em629–Emv684, Ex447–Em636–Emv700 and Ex456–Em650–Emv728. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunodetection of whole tissue extracts of the epicotyl indicated the presence of NADPH-protochlorophyllide oxidoreductase (EC 1.3.1.33). Electron micrographs showed prolamellar bodies in at most 11 % of the plastid profiles of the epicotyl cells. These prolamellar bodies were smaller, and many of them showed less regular structure than those of the leaves. Taken together, the results indicate that the protochlorophyll(ide) in epicotyls is arranged in a different way than in leaves.     

花粉高尔基囊泡与牛脑微管的体外结合

把从榛木（Ｃｏｒｙｌｕｓａｖｅｌｌａｎａ Ｌ．）花粉中分离得到的高尔基囊泡与经高度纯化并聚合好的牛脑微管进行体外组合,然后于１．５ ｍ ｏｌ／Ｌ的蔗糖层上进行超离心,对其沉淀物进行ＳＤＳ－聚丙烯酰胺凝胶电泳和电镜负染。结果表明,花粉高尔基囊泡可以结合到牛脑微管上,证明植物花粉的高尔基囊泡与动物细胞的某些细胞器一样,也与细胞骨架的主要组成之一——微管具有结构上的紧密联系。花粉高尔基囊泡与牛脑微管的体外结合能力,受１０ ｍ ｍ ｏｌ／ＬＡＴＰ和０．５ ｍ ｏｌ／ＬＫＣｌ的影响,但不受５ ｍ ｍ ｏｌ／Ｌ ＡＭＰ－ＰＮＰ的影响,说明两者结合可能是通过高尔基囊泡表面与ＡＴＰ有关的某种外周膜蛋白来完成的。     

A multivariate diagnosis approach applied to celery

Celery (Apium graveolens L. var Dulce) is a high value crop affected at different growth stages by a variety of nutrient disorders. Each nutrient concentration can be corrected for its dependence on concentrations of other nutrients by recognizing plant composition as a closed system whose components add up to one. New variables z _i are computed as logratioed values of individual nutrients, where each nutrient concentration is corrected for the geometric mean of all nutrient concentrations. The z _i are used together with principal component analysis (PCA) to relate celery composition to yield, deficiency symptoms and quality parameters. A survey of commercial celery fields suggested that (1) celery growth is most often limited by P and N deficiencies associated with Fe toxicity; (2) K uptake is most likely to become limiting when the crop reaches 15 cm in height; (3) blackheart incidence can be traced to low levels of K and Mg in external petioles, and (4) cracked stem incidence is related to low B when the crop is 30 cm in height.     

日本落叶松引种区林地棕壤肥力的多变量分析

本研究从日本落叶松引种区林地棕壤9个主要理化性状及与之配套的17株优势木材料入手,采用多变量分析方法筛选出影响该地区日本落叶松生长的主要肥力因子为氮及磷,並据此将该林地棕壤划分为9个肥力类型。在进行聚类分析时,本研究的创新在于以任意二样本点在各主成份上的坐标值为变量,以各主成份的贡献率为权重,重新定义欧氏距离公式,对主成份坐标值聚类,使其更为合理、直观。同时采用回归分析拟合出理化性状间的多个回归方程。此研究为该林地科学施肥、速生丰产、永续利用提供了可靠的数量依据。     

骨骼肌M蛋白抗血清的制备及正常人骨骼肌M蛋白的免疫电镜定位

分别制备了兔抗人Ｍ蛋白（Ｂ成分）抗血清和兔抗人Ｃ成分［１］抗血清。用蛋白Ａ－胶体金作标记物,对经ＬｏｗｉｃｒｙｌＫ４Ｍ低温包埋的人骨骼肌超薄切片中Ｍ蛋白和分子量１４００００的Ｃ成分进行免疫电镜定位。发现Ｍ蛋白分布于整个Ｍ线,而Ｃ成分虽然也集中于Ｍ线以内,但主要分布于Ｍ线内的边缘区域。     

Diversity of Xiphinema americanum-group Species and Hierarchical Cluster Analysis of Morphometrics

Of the 39 species composing the Xiphinema americanum group, 14 were described originally from North America and two others have been reported from this region. Many species are very similar morphologically and can be distinguished only by a difficult comparison of various combinations of some morphometric characters. Study of morphometrics of 49 populations, including the type populations of the 39 species attributed to this group, by principal component analysis and hierarchical cluster analysis placed the populations into five subgroups, proposed here as the X. brevicolle subgroup (seven species), the X. americanum subgroup (17 species), the X. taylori subgroup (two species), the X. pachtaicum subgroup (eight species), and the X. lambertii subgroup (five species).     

The SV2 Protein of Synaptic Vesicles Is a Keratan Sulfate Proteoglycan

Abstract: We have determined that synaptic vesicles contain a vesicle-specific keratan sulfate integral membrane proteoglycan. This is a major proteoglycan in electric organ synaptic vesicles. It exists in two forms on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, i.e., the L form, which migrates like a protein with an M_r of 100, 000, and the H form, with a lower mobility that migrates with an M_r of ∼250, 000. Both forms contain SV2, an epitope located on the cytoplasmic side of the vesicle membrane. In addition to electric organ, we have analyzed the SV2 proteoglycan in vesicle fractions from two other sources, electric fish brain and rat brain. Both the H and L forms of SV2 are present in these vesicles and all are keratan sulfate proteoglycans. Unlike previously studied synaptic vesicle proteins, this proteoglycan contains a marker specific for a single group of neurons. This marker is an antigenically unique keratan sulfate side chain that is specific for the cells innervating the electric organ; it is not found on the synaptic vesicle keratan sulfate proteoglycan in other neurons of the electric fish brain.     

Golgi apparatus isolation and use in cell-free systems

Summary Recent advances in understanding the molecular mechanisms of membrane traffic to and through the Golgi apparatus have been predicated in large measure on the use of permeabilized animal cells, and on completely cell-free systems. These systems have included those addressing inter-Golgi apparatus membrane traffic, endoplasmic reticulum to Golgi apparatus traffic, and endocytotic events. Development of cell-free systems depends on the use of isolated fractions. Specificity is often achieved by using a compartment-specific assay so that the fractions employed can be very crude. More recently cell-free systems also have evolved which employ highly purified and well-characterized cell fractions. The latter may be utilized in the absence of a compartment-specific assay but may require employment of compartment-specific assays for validation. Central to development of cell-free systems for membrane analysis has been the availability of isolated Golgi apparatus, first from plants and later from animal tissues and cells. A major advantage of cell-free systems is that they are most clearly amenable to the investigation of molecular mechanisms of membrane trafficking.Dedicated to Hilton H. Mollenhauer on the occasion of his retirement     

Low temperature compartment formation in feline immunodeficiency virus-infected and uninfected feline kidney cells

Summary This study was to determine if feline immunodeficiency virus (FIV)-infected and uninfected Crandall feline kidney (CRFK) cells exhibited a low temperature (16°C) block in membrane trafficking between transitional endoplasmic reticulum and Golgi apparatus represented by intermediate compartment formation. Cells were cultured at different temperatures and membrane changes involving the Golgi apparatus and Golgi apparatus-associated membrane structures were monitored by electron microscopy and quantitated. With 30 min of incubation, membranes of the Golgi apparatus stack increased in amount at temperatures of 16°C and below compared to temperatures above 18°C. The increase was greatest along the major polarity axis as evidenced by an increased stack height. Neither the number of cisternae per stack nor the average stack diameter (width) was affected by temperature. The response was maximal between 15 and 30 min of low temperature treatment of the cells. Results with cells infected and uninfected with feline immunodeficiency virus were similar. The increase in stack height was due primarily to an increase of membranes at the cis face (cis Golgi apparatus network). At 18°C, membranes of the trans Golgi apparatus network accumulated suggesting that import from the cis Golgi network could proceed at this temperature, whereas exit from the trans Golgi network was still at least partially blocked. Also increased at 16°C and below were numbers of transition vesicles in the space between the Golgi apparatus and the transitional endoplasmic reticulum associated with the cis Golgi apparatus face. The results suggested interruption of the orderly flux of membranes into the Golgi apparatus at 16°C and below. Moreover, the block appeared to be reversible. Upon transfer from 16°C to 37°C, there was a time-dependent decrease in the accumulations of cis compartment membrane accompanied by a corresponding equivalent increase in the membranes of the trans Golgi apparatus compartment.