No abstract

The growth and differentiation of callus tissues derived from cotyledons of ten cultivars of Cucumis sativus L. were investigated. Cotyledonary explants from all ten cultivars formed callus tissue on Murashige and Skoog (MS) medium supplemented with 0.5 gM 2,4-dichlorophenoxyacetic acid and 5 #M 6-benzylaminopurine. Fresh weight of the callus tissues averaged 1 to 8 g per flask after five weeks of culture. Shoot development was achieved in three cultivars, Hukchinju, Manchoonchoungjang and Seoul, on MS medium supplemented with 0.5 #M ~-naphthaleneacetic acid and 5 #M 6-benzylaminopurine. Reducing the 6-benzylaminopurine concentration to 0.01 #M resulted in root formation on callus tissues and on shoots transferred to this medium. All cultivars gave the same response in tests of root formation, but shoot regeneration from callus culture of cucumber cotyledons was dependent on genotype with cultivar Manchoonchoungjang exhibiting the best shoot differentiation capability among the genotypes examined. Examination of mitotic metaphase from the regenerants revealed that all were tetraploid.

We have fabricated an electric cell fusion chip with an embedded cell delivery function driven by surface tension and evaluated its performance with several types of plant cells. The chip consists of a polydimethylsiloxane-based microchannel with a fusion chamber and gold-titanium (Au-Ti) electrodes. The velocity profiles of the microfluid in the channel and fusion chamber were calculated to predict cell movement, and the electric field distribution between the electrodes was also calculated in order to determine the appropriate electrode shape. The range of the fluid velocity in the fusion chamber is 20-50 μm s −1 and the measured speed of the cells is approximately 45 μm s −1 , which is sufficiently slow for the motion of the cells in the fusion chamber to be monitored and controlled. We measured the variation of the pearl chain ratio with frequency for five kinds of plant cells, and determined that the optimal frequency for pearl chain formation is 1.5 MHz. The electrofusion of cells was successfully carried out under ac field (amplitude: 0.4-0.5 kV cm −1 , frequency: 1.5 MHz) and dc pulse (amplitude: 1.0 kV cm −1 , duration: 20 ms) conditions. M This article features online multimedia enhancements S This article has associated online supplementary data files

Several advances have been made in the use of microfluidic devices for insect and mammalian cell cultures, but no reports of their use for plant cell cultures have been published. We, therefore, conducted a plant cell culture in a microfluidic device using polydimethylsiloxane. Nicotiana tabacum protoplasts were cultured in a variously shaped polydimethylsiloxane channel containing Nitsch medium supplemented with 0.5 g of NLN-13 vitamin mixture, 2.0 mg of alpha-naphthaleneacetic acid, and 0.5 mg of 6-benzyladenine per liter and 9% mannitol. Protoplasts in the polydimethylsiloxane channel showed cell division and microcolony formation within 4 weeks. The use of a microfluidic channel is a novel technique in the field of plant cell culture. The results of this study will encourage the utilization of polydimethylsiloxane-based microfluidic devices in plant cell engineering and cell analysis.

In plant cell culture, the delivery of nutrition and gas (mainly oxygen) to the cells is the most important factor for viability. In this paper, we propose a polydimethylsiloxane (PDMS)-based microculture system that is designed to have good aeration. PDMS is known to have excellent air permeability, and through the experimental method, we investigated the relation between the degree of air delivery and the thickness of the PDMS sheet covering the culture chamber. We determined the proper thickness of the cover sheet, and cultured protoplasts of Nicotiana tabacum in a culture chamber covered with a PDMS sheet having thickness of 400 microm. The cells were successfully divided, and lived well inside the culture chamber for 10 days. In addition, protoplasts were cultured inside the culture chambers covered with the cover glass and the PDMS sheet, respectively, and the microcolonies were formed well inside the PDMS covered chamber after 10 days.