Structural-functional aspects of the postischemic recovery of the hepatocyte endoplasmic network in rats

The experiments on rats have shown that total hepatic ischemia reduces the content of microsomal cytochromes P-450 and b5 and causes amidopyrine and aniline disturbances over a 2-3-week post-ischemic period. The analysis of hepatocyte ultrastructure has revealed the interdependence of structural and functional changes in endoplasmic reticulum during recovery period. The damage of monooxygenase inducibility correlated with stable decline in the number of fixed ribosomes in post-ischemic period.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

Plant virus infection development as affected by heavy metal stress

The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants.     

High-Speed Recording of Vacuum Arc Discharge Images in the Optical Range

Plasma Physics Reports - Switching of a short vacuum gap with an auxiliary discharge over the surface of a dielectric has been studied via high-speed recording of images of discharge plasma...     

Plantlet regeneration from subculturable nodular callus of Pinus radiata

An efficient planlet regeneration system via nodular callus formation is described for Pinus radiata. Subculturable nodular callus was induced at its highest frequency (93%) on embryonic explants excised from seeds at an early stage of germination (radicle length 2–5 mm). The optimal medium for nodular callus tissue proliferation was LP basal medium that was modified by reducing the concentration of potassium nitrate to 500 mg l^–1 and supplemented with 22.2 M 6-benzyladenine (BAP) and 2.85 M indole-3-butyric acid (IBA). Bud differentiation from the nodules was achieved by reducing BAP and sucrose concentrations in the culture medium. The maximum frequency of adventitious bud formation occurred on LP basal medium containing 2% sucrose and 0.44 M BAP on which about 61% of the transferred nodules formed buds. During the next 6 weeks of culture on the same cytokinin-free medium multiple shoots elongated from the buds. These shoots were excised and transferred to root initiation medium (RIM2.1), consisting of full-stregth SH macro- and micro-salts, 1000 mg l^–1 myo-inositol, 0.4 mg l^–1 thiamine-HCl, 2% sucrose and a combination of naphthaleneacetic acid (NAA), IBA and BAP at concentrations of 2.69, 4.93 and 0.11 M, respectively. After 5–15 days, root meristems were initiated on the stem bases. The highest rooting frequency was achieved when shoots were treated for 10 days on RIM2.1 medium, before being transferred to half-strength Schenk and Hildebrandt medium with 1% sucrose and without growth regulators for root growth.     

Mechanisms for the formation and transport of ion fluxes in the plasma of a high-current vacuum spark

The processes of ion flux formation in the plasma of a high-current vacuum spark were investigated experimentally. It is shown that multicharged ions are generated in the neck formed in the erosion products of the inner electrode. The plasma escaping from the neck region plays a role of a piston dragging particles of the cold peripheral plasma into ambient space. As the discharge current increases, the flux of the evaporated electrode material grows, the degree of ionization of the plasma produced decreases, and the efficiency of plasma heating caused by the pinching effect is reduced.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Hyacinthus orientalis</Emphasis> with thaumatin II gene to control fungal diseases

Transgenic plants of hyacinth (Hyacinthus orientalis L.) cvs. Edisson and Chine Pink have been obtained by Agrobacterium-mediated transformation. Leaf explants of the both hyacinth cultivars regenerated shoots on MS medium containing 2.2 μM BAP and 0.3 μM NAA at a frequency of 95%. A. tumefaciens strain CBE21 carrying binary vector pBIThau35 was used for transformation. Plasmid pBIThau35 has been produced by cloning preprothaumatin II cDNA into pBI121 instead of uidA gene. Inoculated leaf explants formed calli and shoots at high frequency on selective medium with 100 mg l⁻¹ kanamycin. Four hyacinth transgenic lines of cv. Chine Pink and one line of cv. Edisson have been selected on medium containing 200 mg l⁻¹ kanamycin. The insertion of thaumatin II gene into hyacinth genome has been confirmed by PCR-analysis. All transgenic plants expressed substantial amounts of thaumatin II (between 0.06 and 0.28% of the total soluble protein). Hyacinth transgenic lines were assayed for resistance to the pathogenic fungi Fusarium culmorum and Botrytis cinerea. There were no significant differences between nontransformed control and transgenic leaves of both cultivars. At the same time the bulbs of the transgenic line Н7401 cv. Chine Pink showed the higher level of resistance to B. cinerea, the bulbs of the transgenic line Н7404 were more resistant to F. culmorum. In both cases the signs of the fungal disease were developed more slowly. The resistance of the bulbs cv. Edisson line to these fungi was not changed. All transgenic hyacinth plant were successfully transferred to soil for further evaluation.