Metabolic events in synchronised cell cultures of Acer pseudoplatanus L.

Abstract

Cell division was synchronised in 4-litre batch cultures of Acer pseudoplatanus L. by starvation and regrowth. Up to five consecutive cell cycles were observed in each culture. Mitosis and cytokinesis were synchronised within 0.2 cell cycles. Accumulation of extractable DNA was discontinuous and separate from cytokinesis. Correction for the degree of synchrony in the population gave: G1=13-37 h, S=15 h, G2=14-19 h and M=0.9-1.3 h. Thymidine kinase activity and [(14)C]thymidine incorporation were highest during S-phase. A peak of activity of aspartate transcarbamoylase occurred during G2. Peaks in succinate dehydrogenase activity and respiration rate were observed at the initiation of DNA synthesis and just prior to mitosis. The activity of glucose-6-phosphate dehydrogenase doubled in one step during the cell cycle. Total RNA and protein accumulated continuously through the cell cycle; the final rate being twice that observed initially.

Incorporation and Degradation of 14C and 3H-labeled Thymidine by Sugarcane Cells in Suspension Culture

“…With labeled T, 0.5%, with labeled TdR, 17%, and with labeled TdR plus unlabeled T, 16.6%, of the initial radioactivity was found in the hot acid-soluble cell fraction. The absence of appreciable ["CIT incorporation might be due to a lack ofdeoxyribosyl donors similar to the results found in experiments with Escherichia coli (12). Using germinating rape seeds Evans and Axelrod (5) showed Inhibition of Thymidine Degradation.…”

“…In bacteria, it has been possible either to isolate mutant cells lacking the responsible degradative enzyme, thymidine phosphorylase, or, by adding AdR to the medium, to both inhibit phosphorylase and to supply deoxyribose-1-phosphate to reform TdR from T (2). Because similar mutant plants are not available and because the addition of AdR to plant tissues was only partly successful in reducing TdR degradation (26) the problem has been avoided in work with plants by using either very short exposure times (26) or by using large amounts (24 jig/ml) ofrelatively low activity labeled TdR (12). Under these conditions, only DNA of low specific activity can be synthesized.…”

Adenosine Phosphate and Nicotinamide Adenine Dinucleotide Pool Sizes during Shoot Initiation in Tobacco Callus

“…The levels of adenosine phosphates in SF, NSF, and SFG tissues all increased by day 3 in culture with the highest levels occurring at day 6 (Fig. 1).…”

Microcystin-RR induced apoptosis in tobacco BY-2 suspension cells is mediated by reactive oxygen species and mitochondrial permeability transition pore status

“…To have a more clear aware of these morphological changes, we measured cellular length and width. Prior to cell measuring, the cells were treated with 6.4% CrO 3 for 30 min at 70°C and sonified for aggregate dissociation (King et al, 1974). Length and width of 100 dissociated cells were measured under the Nikon microscope using micro-ruler.…”