• Journal of Plant Biotechnology
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• v.6 no.1
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• pp.25-37
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• 2004

Successful genetic transformation of plants requires non-chimeric selection of transformed tissues and their subsequent regeneration. With rare exceptions, most transformation protocols still rely heavily on antibiotics for selecting transgenic cells that contain an antibiotic-degrading selectable marker gene. Here, the morphogenic capacity of in-vitro explants of chrysanthemnum and tobacco stems and leaves (control and transgenic) changed with the addition of aminoglycoside antibiotics (AAs), In a test of 6 AAs, phytotoxicity occurred at concentrations of 10 to 25 and 50 to 100$\mu\textrm{g}$ $mL^{-1}$ in chrysanthemum and tobacco explants, respectively. Light conditions as well as explant source and size also had significant effects. The use of transverse thin cell layers (tTCLs), in conjunction with high initial AA selection levels, supported the greatest regeneration of transgenic material (adventitious shoots or callus) and the lowest number of escapes. Flow-cytometric analyses revealed no endodu-plication in chrysanthemum, even at high AA levels. However, this phenomenon was observed in tobacco calli(8C or more), even at low AA concentrations (i.e., 5 to 10 $\mu\textrm{g}$ mL$^{-1}$ ).

• ALGAE
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• v.25 no.2
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• pp.99-104
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• 2010

A psychrotolerant cyanobacterium, Nodularia spumigena KNUA005, was isolated from a cyanobacterial bloom sample collected near Dasan Station in Ny-${\AA}lesund$, Svalbard Islands during the Arctic summer season. To generate an axenic culture, the isolate was subjected to three purification steps: centrifugation, antibiotic treatment and streaking. The broad antibacterial spectrum of imipenem killed a wide range of heterotrophic bacteria, while the cyanobacterium was capable of enduring both antibiotics, the remaining contaminants that survived after treatment with imipenem were eliminated by the application of an aminoglycoside antibiotic, kanamycin. Physical separation by centrifugation and streaking techniques also aided axenic culture production. According to the cold-tolerance test, this mat-forming cyanobacterium was able to proliferate at low temperatures ranging between 15 and $20^{\circ}C$ which indicates the presence of cold-tolerance related genes in N. spumigena KNUA005. This suggests the possibility of incorporating cold-resistance genes into indigenous cyanobacterial strains for the consistent production of algae-based biofuel during the low-temperature seasons. Therefore, it is needed to determine the cold-tolerance mechanisms in the Arctic cyanobacterium in the next research stage.