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A ten-year search for synchronous cells: obstacles, solutions, and practical applications.

Helmstetter CE - Front Microbiol (2015)

Bottom Line: My effort to use synchronously dividing cultures to examine the Escherichia coli cell cycle involved a 10-year struggle with failure after failure punctuated by a few gratifying successes, especially at the end.In this essay, I recount my personal journey in this obsessive experimental pursuit.That narrative is followed by a description of a simplified version of the "baby machine," a technique that was developed to obtain minimally disturbed, synchronously growing E. coli cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Florida Institute of Technology Melbourne, FL, USA.

ABSTRACT
My effort to use synchronously dividing cultures to examine the Escherichia coli cell cycle involved a 10-year struggle with failure after failure punctuated by a few gratifying successes, especially at the end. In this essay, I recount my personal journey in this obsessive experimental pursuit. That narrative is followed by a description of a simplified version of the "baby machine," a technique that was developed to obtain minimally disturbed, synchronously growing E. coli cells. Subsequent studies with this methodology led to an understanding of the basic properties of the relationship between chromosome replication and cell division. Accordingly, I end this reminiscence with a simple, fool-proof graphical strategy for deducing the pattern of chromosome replication during the division cycle of cells growing at any rate.

No MeSH data available.


Related in: MedlinePlus

Construction of a chromosomal replication pattern during the bacterial division cycle. The construction, starting at the top left, is based on the (I + C + D) rule with I = 35 min, C = 40 min, and D = 20 min.
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Figure 5: Construction of a chromosomal replication pattern during the bacterial division cycle. The construction, starting at the top left, is based on the (I + C + D) rule with I = 35 min, C = 40 min, and D = 20 min.

Mentions: We will determine the moderately complex relationship between chromosome replication and cell division for the average E. coli B/r cell in a population growing with a doubling time of 35 min at 37°C. At this growth rate, reasonable values for C and D would be 40 min and 20 min, respectively. Referring to Figure 5, start at the top left by imagining a hypothetical cell with no initiation potential and draw a squiggly horizontal line, 35 min in duration, to represent I. I must be 35 min under these conditions because, as will be seen at the end of this exercise, I determines the doubling time. At the end of the I period, replication initiates, so draw a 40-min horizontal line to represent C, followed by a 20-min interrupted line to represent D. Then draw a long vertical line to represent cell fission. Now start the second I + C + D sequence below the first. Since I is continuous by definition, begin the next squiggly line at the time the I period ends in the first sequence, and then draw C for another 40 min, D for 20 min and another vertical line. At this point I would normally shout at the students, saying something like: “DON'T THINK! Just draw I + C + D, I + C + D, over and over until you have gone past the second vertical division line. If you try to think you will surely mess up, especially at more rapid growth rates.” Now we are done, and the division cycle for a cell with the given characteristics is shown between the two vertical lines representing division. It is important to note that the duplication process of E. coli can be described as a simple overlapping series of I + C + D sequences. Furthermore, the time between divisions is determined exclusively by I and independent of the durations of C and D.


A ten-year search for synchronous cells: obstacles, solutions, and practical applications.

Helmstetter CE - Front Microbiol (2015)

Construction of a chromosomal replication pattern during the bacterial division cycle. The construction, starting at the top left, is based on the (I + C + D) rule with I = 35 min, C = 40 min, and D = 20 min.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373376&req=5

Figure 5: Construction of a chromosomal replication pattern during the bacterial division cycle. The construction, starting at the top left, is based on the (I + C + D) rule with I = 35 min, C = 40 min, and D = 20 min.
Mentions: We will determine the moderately complex relationship between chromosome replication and cell division for the average E. coli B/r cell in a population growing with a doubling time of 35 min at 37°C. At this growth rate, reasonable values for C and D would be 40 min and 20 min, respectively. Referring to Figure 5, start at the top left by imagining a hypothetical cell with no initiation potential and draw a squiggly horizontal line, 35 min in duration, to represent I. I must be 35 min under these conditions because, as will be seen at the end of this exercise, I determines the doubling time. At the end of the I period, replication initiates, so draw a 40-min horizontal line to represent C, followed by a 20-min interrupted line to represent D. Then draw a long vertical line to represent cell fission. Now start the second I + C + D sequence below the first. Since I is continuous by definition, begin the next squiggly line at the time the I period ends in the first sequence, and then draw C for another 40 min, D for 20 min and another vertical line. At this point I would normally shout at the students, saying something like: “DON'T THINK! Just draw I + C + D, I + C + D, over and over until you have gone past the second vertical division line. If you try to think you will surely mess up, especially at more rapid growth rates.” Now we are done, and the division cycle for a cell with the given characteristics is shown between the two vertical lines representing division. It is important to note that the duplication process of E. coli can be described as a simple overlapping series of I + C + D sequences. Furthermore, the time between divisions is determined exclusively by I and independent of the durations of C and D.

Bottom Line: My effort to use synchronously dividing cultures to examine the Escherichia coli cell cycle involved a 10-year struggle with failure after failure punctuated by a few gratifying successes, especially at the end.In this essay, I recount my personal journey in this obsessive experimental pursuit.That narrative is followed by a description of a simplified version of the "baby machine," a technique that was developed to obtain minimally disturbed, synchronously growing E. coli cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Florida Institute of Technology Melbourne, FL, USA.

ABSTRACT
My effort to use synchronously dividing cultures to examine the Escherichia coli cell cycle involved a 10-year struggle with failure after failure punctuated by a few gratifying successes, especially at the end. In this essay, I recount my personal journey in this obsessive experimental pursuit. That narrative is followed by a description of a simplified version of the "baby machine," a technique that was developed to obtain minimally disturbed, synchronously growing E. coli cells. Subsequent studies with this methodology led to an understanding of the basic properties of the relationship between chromosome replication and cell division. Accordingly, I end this reminiscence with a simple, fool-proof graphical strategy for deducing the pattern of chromosome replication during the division cycle of cells growing at any rate.

No MeSH data available.


Related in: MedlinePlus