Log phase of growth

Lobry de Bruyn-Alberda van Ekenstein transformation 693 Lock and key theory 478 Log phase of growth 470 Lon protease 628 Loricin 439... 

Methotrexate acts by inhibition of dihydrofolate reductase, the enzyme requisite for the reduction of dihydrofolic acid (3) to 5,6,7,8-tetrahydrofolic acid (4). In turn, (4) is a precursor to a series of enzyme cofactors (5-7) essential for the transfer of one carbon unit necessary for the biosynthesis of purines and pyrimidines and hence, ultimately, DNA. As an inhibitor of dihydrofolate reductase, methotrexate kills cells during the S phase of the cell cycle, when the cells are in the log phase of growth. Unfortunately, this cytotoxicity is non-selective, and rapidly proliferating normal cells, e.g., gastrointestinal epithelium cells and bone marrow, are dramatically affected as well. In addition, recent use of high dose methotrexate therapy with leucovorin rescue has led to additional clinical problems arising from a dose-related nephrotoxic metabolite, 7-hydroxy methotrexate (8). Finally, the very polar nature of methotrexate renders it virtually impenetrable to the blood-brain barrier, which can necessitate direct intrathecal injection in order to achieve therapeutic doses for the treatment of CNS tumours. 

Keep 25-cm2 T flasks of cells in log phase of growth by subdividing when almost confluent. Freezing should only be carried out when cells are less than confluent and appear healthy. 

The cells should be plated at the appropriate density, so that they will be harvested at a subconfluent stage in the log phase of growth. 

At 75-80 C the synthetic capacity of Sulfolobus ribosomes is critically dependent upon the stage of cell growth. Preparations from cells harvested in the mid-log phase of growth statistically polymerize about 40 phenylalanine residues per ribosome in 30 min [66] compared to only 5-7 residues found in cells harvested in the late phase of exponential growth [123]. 

Fig. 4A,B. The effect of ethanol on the redox state of SV40 transformed 3T3 cells. Cells were seeded at 1 X 10 /35 mm dish and 24 h later cells in log phase of growth were incubated in control medium (O) or medium containing 1% ethanol ( ) for the indicated periods of time. Pyridine nucleotides were extracted and assayed as previously described [3,7]. The results of two representative experiments are shown...

Split and feed both the B-LCL and the myeloma cells one day prior to fusitai to ensure they are in log phase of growth. 

Ensure B-LCL or heterohybridomas are in log phase of growth by splitting and feeding one to two days before cloning. 

This chiral polyalkanoate, based on D(-)g hydroxybutyric acid monomer, was discovered in the 1920 s and remained a microbiological fact while polymer chemists struggled with the likes of cellulose, natural rubber, and silk. However, like starch in the plant world, PHB is ubiquitous in the bacterial kingdom and serves exactly the same purpose. Figure 15 shows how the concentration of PHB in the cells builds up during the "log"phase of growth then drops rapidly, presumably being metabolised in relation to... 

To each of two sterile 125-ml Erlenmeyer flasks add 50 ml vitamin-free sea water and plug the flask with a sterile cotton plug enclosed in cheesecloth. Add to each flask 0.25 ml of nutrient solution a, and 0.05 ml of solution b. To one flask add 0.05 ml of solution prepared as described later in Section G. This flask contains a complete medium that is used to maintain algal stocks. Transfer 5.5 ml of an actively growing culture of Monochrysis lutheri (culture should be visibly turbid with cells) to this flask. Incubate the transfer at 22 C in the light incubator for 2 days, then transfer 0.5 ml of this culture to the remaining flask which contains B -free medium. After 5 days incubation, the culture in this flask is in the log phase, of growth, almost stripped of B and is ready to be used as an inoculum. 

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