Isolation,origin and properties of enucleate plant microplasts

Summary Auxin-induced highly vacuolated thin-walled callus cells of several plant species, when ruptured, released large numbers of subcellular units most of which were enucleate. These enucleate microplasts are surrounded by an inner membrane of the cell, most probably derived from the tonoplast. When microplasts isolated fromSaintpaulia callus were cultured in a medium supplemented with growth substances they formed a thin wall and underwent budding. Microplasts could be useful for various studies in plant cell biology and for genetic manipulations.     

Strategies for signal amplification in nucleic acid detection

Many aspects of molecular genetics necessitate the detection of nucleic acid sequences. Current approaches involving target amplification (in situ PCR, Primed in situ Labeling, Self-Sustained Sequence Replication, Strand Displacement Amplification), probe amplification (Ligase Chain Reaction, Padlock Probes, Rolling Circle Amplification) and signal amplification (Tyramide Signal Amplification, Branched DNA Amplification) are summarized in the present review, together with their advantages and limitations.     

Isolation,culture and callus regeneration of protoplasts of wild and cultivated Helianthus species

Protoplasts were isolated from seedling roots, hypocotyls, and cotyledons of four cultivars of Helianthus annuus and from leaves of axenic shoot cultures of the wild species H. praecox, H. scaberimus and H. rigidus. Optimal culture conditions were established for the respective protoplast systems, using the agarose bead method of culture. Protoplast division was induced for all the species examined. In the case of the cultivars of H. annuus, hypocotyl and cotyledon protoplast division was sustained leading to callus formation, which in turn, could be induced to produce roots and organised meristematic regions in the presence of NAA and 6-BAP.Abbreviations 6-BAP 6-benzylaminopurine - NAA -naphthalene acetic acid - IAA indole-3-acetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - MS Murashige and Skoog     

Xylem colonization of the legume Sesbania rostrata by Azorhizobium caulinodans

A novel pathway of invasion of the legume Sesbania rostrata by Azorhizobium caulinodans is described that involves colonization of the root xylem, possibly following entry into the natural fissures created during emergence of lateral roots. Azorhizobia were detected microscopically, and their presence confirmed by the expression of a lacZ reporter gene. We have shown that rhizobial Nod factors are not required for either xylem colonization or for crack-entry of lateral roots. We discuss the extent to which this discovery of xylem colonization by azorhizobia is likely to improve our understanding of both symbiosis and of pathogenicity in plant–bacterial interactions.     

An electron microscopic study of the initial stages of infection of isolated tomato fruit protoplasts by tobacco mosaic virus

Summary Protoplasts were isolated from tomato fruit locule tissue and incubated with tobacco mosaic virus. Electron microscope observations on sections of suitably fixed and embedded material revealed that virus particles readily became attached to the plasmalemma, particularly in small invaginations in the surface of the protoplast. Virus particles were later observed in vesicles within the cytoplasm and it was clear that these vesicles were being formed as a result of pinocytic activity at the surface of the protoplast. Later, virus particles were observed near the nucleus. It is suggested that an initial attachment of the virus to the plasmalemma followed by a pinocytic uptake may represent the initial stages of virus infection of plant cells and that the pinocytic vesicle, containing virus, serves as the vehicle of cellular infection.     

Ti Plasmid Homologous Sequences Present in Tissues from Agrobacterium Plasmid-transformed Petunia Protoplasts

Suspension cell protoplasts of albino Petunia hybrida have beentransformed by isolated Agrobacterium tumefaciens Ti plasmid.Uptake of octopine Ti plasmid (pTiACH5) into protoplasts wasstimulated by poly-L-ornithine and polyethylene glycol (PEG).The frequency and efficiency of transformation of protoplaststo phytohormone autotrophy was compared using the two uptakeagents with various concentrations of plasmid. Transformationwas most efficient with PEG-mediated uptake, 5 µg of Tiplasmid per 10⁶ protoplasts giving a frequency of 6?10^–5.Octopine was not synthesised in any of the transformants afterthe second subculture on hormone-free medium. DNA-DNA hybridisationshowed the presence of DNA homologous to the T-DNA region ofpTiACH5 in all clones analysed. (Received November 9, 1981; Accepted January 29, 1982)     

Alteration of surfactant protein A expression in renal cell carcinoma

Surfactant protein-A (SP-A) belongs to a family of collagen-containing C-type lectins called collectins. SP-A is expressed by renal tubule epithelial cells. We investigated the distribution of SP-A in renal cell carcinomas (RCC) using immunohistochemical techniques and western blotting. We used 35 formalin fixed, paraffin embedded (FFPE) RCC tissue samples. We compared results with clinico-pathological parameters of RCC including age, sex, Fuhrman grade, tumor volume, tumor node metastasis (TNM) and clinical stage. SP-A was localized in the glomerulus and renal tubule epithelium in nontumor tissue and strong SP-A immunoreactivity was observed in tumor tissue. SP-A was expressed in the RCC tumor cells (64%) and nontumor cells (34%) in males and RCC tumor cells (90%) and nontumor cells (30%) in females. There was a significant correlation between SP-A immunoreactivity in tumor cells and gender, age, tumor diameter, Fuhrman grade and tumor diameter. Western blot analysis supported the immunohistochemical findings. We present evidence for involvement of SP-A in RCC and suggest that increased SP-A expression in RCC is associated with favorable prognosis.     

Evaluation of Garden Crop Mercury Uptake and Potential Exposure from Consumption of Garden Crops Grown on Floodplain Soils

ABSTRACT

This study investigated Hg uptake from soil into garden crops to help assess the significance of human consumption of crops as a potential route of exposure to Hg. Locations for both a floodplain and a control garden were identified within the Augusta Forestry Center near Crimora, VA, USA, which is about 16 river-km downstream from the city of Waynesboro, along the South River. The floodplain garden had measured soil Hg concentrations ranging from 4.2 to 78 mg Hg kg^?1 dry weight basis in the surface to 15-cm deep layer. A total of 139 samples from the floodplain garden from 17 different crops were analyzed for Hg. All crop samples (except for nine) had less than 0.1 μg Hg g^?1 wet weight basis (ww). Many samples were less than the method detection limit (MDL) of 0.003 μg Hg g^?1 ww. Based on the measured Hg concentrations and several conservative assumptions (e.g., Hg assumed present when less than MDL; 100% consumption from the geographical area in which study was conducted; and 100% bioavailable Hg as methyl Hg), consumption of crops with these Hg levels is not expected to be a significant route of Hg exposure.     

三氧化二砷对食管癌细胞增殖和热休克蛋白70表达的影响

目的：研究三氧化二砷（As2O3）对食管癌细胞增殖和热休克蛋白70（HSP70）表达的影响。方法：通过相差显微镜、流式细胞术、免疫细胞化学染色和免疫印迹分析等方法观察As2O3对人食管癌细胞株EC1的作用效果和作用机制。结果：与对照组相比,经2μmol/L和5μmol/Las2O3作用的细胞出现明显的生长抑制,G2/M期细胞比例增加;2μmol/Las2O3作用48h后经Ecl细胞HSP70（heat shock protein70）及HSC70(heat shock cognate protein70)表达均增加。结论：As2O3诱导食管癌细胞G2/M期阻滞抑制细胞增殖和生长;HSP70的升高是细胞对As2O3作用后出现的应激反应,并与细胞周期阻滞相关。