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Factors affecting daughter cells' arrangement during the early bacterial divisions.

Su PT, Yen PW, Wang SH, Lin CH, Chiou A, Syu WJ - PLoS ONE (2010)

Bottom Line: Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population.Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings.Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China.

ABSTRACT
On agar plates, daughter cells of Escherichia coli mutually slide and align side-by-side in parallel during the first round of binary fission. This phenomenon has been previously attributed to an elastic material that restricts apparently separated bacteria from being in string. We hypothesize that the interaction between bacteria and the underneath substratum may affect the arrangement of the daughter bacteria. To test this hypothesis, bacterial division on hyaluronic acid (HA) gel, as an alternative substratum, was examined. Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population. Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings. Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors. With oscillatory optical tweezers, we further demonstrated that the interaction force decreased in bacteria without Lpp, a result substantiating our notion that the side-by-side sliding phenomenon directly reflects the strength of in-situ interaction between bacteria and substratum.

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Patterning of daughter bacteria in liquid without underneath substratum.Bacterial divisions in LB medium were followed similar to that described in Figure 1. (A) Parental strain BW25113; (B) flagellum- strain JW1923. In (A), arrowhead indicates a cell separating and disappearing from the bacterial string in the subsequent image. In (B), the arrow indicates bacteria that appeared as a string of four cells while the arrowhead marks a string of 16 offspring bacteria. Note: the balloon-type bacteria were not exactly on the focal plane of the microscope. No bacteria were observed to have a parallel or 4-cell array arrangement in all fields. Scale bar: 5 µm.
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pone-0009147-g002: Patterning of daughter bacteria in liquid without underneath substratum.Bacterial divisions in LB medium were followed similar to that described in Figure 1. (A) Parental strain BW25113; (B) flagellum- strain JW1923. In (A), arrowhead indicates a cell separating and disappearing from the bacterial string in the subsequent image. In (B), the arrow indicates bacteria that appeared as a string of four cells while the arrowhead marks a string of 16 offspring bacteria. Note: the balloon-type bacteria were not exactly on the focal plane of the microscope. No bacteria were observed to have a parallel or 4-cell array arrangement in all fields. Scale bar: 5 µm.

Mentions: Overall, the observed percentage of bacteria arraying in parallel on the HA gel was notably smaller than that seen on a similarly prepared agar gel (<3% versus over 90%). This fact strongly supports the hypothesis that the components of the underneath substratum affects the early patterning of the daughter bacteria lying above. If this is the case, a complete elimination of the bacterium-substratum interaction ought to keep most of the offspring arranged in strings. To test this notion, we diluted the bacteria and restricted the bacteria to a thin LB-filled space sandwiched between two cover slips. Shown in Figure 2A is strain BW25113 that stayed in short strings in all fields. On tracing these early rounds of division using time-lapse imaging, bacteria were seen elongating and dividing into two in a string without any mutual sliding. Since flagellar rotary motion may accelerate string breakage of the daughter cells, the same experiment was repeated with strain JW1923 (flagellum ). This flagellum- bacterium also gave strings of cells at various lengths. Figure 2B shows a developing string of 16 offspring remaining connected in the liquid. Population analysis, summarized in Table 2, shows that this flagellum- JW1923 displayed more in long strings (≥3 cells, 16.5%) than that of the parental BW25113 strain (9.0%) in the same liquid culture condition. This observation strongly suggested that the flagellar rotation disfavors the linkage between divided bacterial cells. It is appropriate to re-emphasize at this point that no single pair of daughter bacteria was observed aligning side-by-side with either of the two strains in the liquid media.


Factors affecting daughter cells' arrangement during the early bacterial divisions.

Su PT, Yen PW, Wang SH, Lin CH, Chiou A, Syu WJ - PLoS ONE (2010)

Patterning of daughter bacteria in liquid without underneath substratum.Bacterial divisions in LB medium were followed similar to that described in Figure 1. (A) Parental strain BW25113; (B) flagellum- strain JW1923. In (A), arrowhead indicates a cell separating and disappearing from the bacterial string in the subsequent image. In (B), the arrow indicates bacteria that appeared as a string of four cells while the arrowhead marks a string of 16 offspring bacteria. Note: the balloon-type bacteria were not exactly on the focal plane of the microscope. No bacteria were observed to have a parallel or 4-cell array arrangement in all fields. Scale bar: 5 µm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2818839&req=5

pone-0009147-g002: Patterning of daughter bacteria in liquid without underneath substratum.Bacterial divisions in LB medium were followed similar to that described in Figure 1. (A) Parental strain BW25113; (B) flagellum- strain JW1923. In (A), arrowhead indicates a cell separating and disappearing from the bacterial string in the subsequent image. In (B), the arrow indicates bacteria that appeared as a string of four cells while the arrowhead marks a string of 16 offspring bacteria. Note: the balloon-type bacteria were not exactly on the focal plane of the microscope. No bacteria were observed to have a parallel or 4-cell array arrangement in all fields. Scale bar: 5 µm.
Mentions: Overall, the observed percentage of bacteria arraying in parallel on the HA gel was notably smaller than that seen on a similarly prepared agar gel (<3% versus over 90%). This fact strongly supports the hypothesis that the components of the underneath substratum affects the early patterning of the daughter bacteria lying above. If this is the case, a complete elimination of the bacterium-substratum interaction ought to keep most of the offspring arranged in strings. To test this notion, we diluted the bacteria and restricted the bacteria to a thin LB-filled space sandwiched between two cover slips. Shown in Figure 2A is strain BW25113 that stayed in short strings in all fields. On tracing these early rounds of division using time-lapse imaging, bacteria were seen elongating and dividing into two in a string without any mutual sliding. Since flagellar rotary motion may accelerate string breakage of the daughter cells, the same experiment was repeated with strain JW1923 (flagellum ). This flagellum- bacterium also gave strings of cells at various lengths. Figure 2B shows a developing string of 16 offspring remaining connected in the liquid. Population analysis, summarized in Table 2, shows that this flagellum- JW1923 displayed more in long strings (≥3 cells, 16.5%) than that of the parental BW25113 strain (9.0%) in the same liquid culture condition. This observation strongly suggested that the flagellar rotation disfavors the linkage between divided bacterial cells. It is appropriate to re-emphasize at this point that no single pair of daughter bacteria was observed aligning side-by-side with either of the two strains in the liquid media.

Bottom Line: Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population.Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings.Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China.

ABSTRACT
On agar plates, daughter cells of Escherichia coli mutually slide and align side-by-side in parallel during the first round of binary fission. This phenomenon has been previously attributed to an elastic material that restricts apparently separated bacteria from being in string. We hypothesize that the interaction between bacteria and the underneath substratum may affect the arrangement of the daughter bacteria. To test this hypothesis, bacterial division on hyaluronic acid (HA) gel, as an alternative substratum, was examined. Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population. Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings. Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors. With oscillatory optical tweezers, we further demonstrated that the interaction force decreased in bacteria without Lpp, a result substantiating our notion that the side-by-side sliding phenomenon directly reflects the strength of in-situ interaction between bacteria and substratum.

Show MeSH
Related in: MedlinePlus