Propagation of Zea mays L. by Shoot Tip Culture: A Feasibility Study

A procedure for the stimulation of axillary bud developmentfrom young shoots of maize, their subculture to root-inducingmedia and transfer as rooted plants to soil is described. Axillarybud development was enhanced by the addition of kinetin andauxin to the culture medium. Root initiation on explanted axillarybuds, while successful with some cultivars, was variable. Anumber of mature plants with normal tassels and ears were producedfrom the lowermost buds of an original stem explant. Buds fromhigher positions on the explant exhibited different potentialitieswith some, those normally from cob producing nodes, producingshort-stalked plants with terminal female influorescences. Agradient of bud potentiality along the stem appears to be establishedextremely early after each is initiated. Zea mays., corn, maize, shoot tip culture, clone, vegetative propagation     

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Interferon-γ effect on growth regulation of cells with different levels of EGF receptor expression

Interferon gamma (IFNγ) is known to inhibit the proliferation of some transformed cell lines. Recently, we demonstrated the transactivation of the epidermal growth factor receptor (EGFR) in response to IFNγ (Burova et al., 2007) and provided direct evidence for the dependence of IFNγ-induced EGFR transactivation on the EGFR expression level in epithelial cells (Gonchar et al., 2008). This study examines an antiproliferative effect of IFNγ on human epithelial cell lines—A431 and HeLa that express high levels of EGFR, as well as HEK293 that expresses low levels of EGFR. To characterize the IFNγ-induced changes in these cells, we studied cell growth, the cell cycle, and induction of apoptosis. The response to IFNγ differed in the compared cell lines; cell growth was inhibited in both A431 and HeLa cells, but not in HEK293 cells, as was shown by the cell count and MTT. The cell-cycle phases analyzed by flow cytometry were disturbed in A431 and HeLa cells in response to IFNγ. On the contrary, in HEK293 cells, the IFNγ treatment did not alter distribution by cell cycle phases. Our results indicate that IFNγ produces an antiproliferative effect that depends on the increased expression of EGFR in A431 and HeLa cells. Furthermore, it was demonstrated that IFNγ induced the caspase 3 activation in A431 cells, which suggests the involvement of active caspase 3 in the IFNγ-induced apoptosis.     

Gold nanoparticles disturb nuclear chromatin decondensation in mouse sperm in vitro

The effect of gold nanoparticles on mouse epididymal sperm has been studied using the model system of nuclear chromatin decondensation in vitro. It is shown that the treatment of gametes, preliminary membrane-freed by sodium dodecyl sulfate, in the mediums containing gold nanoparticles (with diameter ∼2.5 nm) in concentrations 1.0 × 10¹⁵ or 0.5 × 10¹⁵ particles/ml and following incubation in dithiothreitol solution (DTT) resulted in failure of chromatin decondensation process and nucleus structure. We conclude that gold nanoparticles possess spermatotoxicity. The mechanism of cytotoxic effect of gold nanoparticles may be related with their interaction with molecules of double-helix DNA. The model system studied in this research is applicable for further investigations of cytotoxic effects of nanoparticles of different origin and made of different metals.