ISSN:
0730-2312
Keywords:
cell size
;
cell division
;
growth media
;
Ciliates
;
enkaryotic cells
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Cell volume and doubling time have been determined for exponentially growing Tetrahymena pyriformis cells in broth medium with and without glucose and in media made from these media by dilution with water. The cells tolerate media with dry weights from 105 down to 0.06 g/L. In the diluted media the cells have small volumes and the doubling time is increased.When the cell volume increase per time per cell in a given medium is expressed as function of the cell volume in this same medium, a direct proportionality is found. From this equation the minimum cell volume of division competence (MVDC) can be found. It is 2,100 μm3 for T. pyriformis at 28°C.The lag period resulting from an upshift of exponentially growing cells from diluted media to more concentrated media is a function of the initial and resulting cell volumes and MVDC.The increase in cell volume per unit of time for a given cell-depends on the dry weight of the medium. This parameter can be transformed to mass increase per cell surface area per time, which represents rate of nutrient uptake. When plotted against the dry weight of the media, a Michaelis-Menten-like curve is obtained with two Km values of 3.8 and 0.08 g/L with corresponding Vmax values of 20 and 4 ng/cm2 · s.The low Km value (0.08 g/L) indicates that Tetrahymena is able to take up nutrients from highly diluted media. The high value of Vmax (20 ng/cm2 · s) increases the ability of growth in more concentrated media. Thus, the adaptability of Tetrahymena to regulate its growth rate on media with considerable differences in nutrient supply is partly explained.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240410303
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