Team:ETHZ Basel/Achievements/E lemming

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== Experimental Results ==
== Experimental Results ==
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We imaged several transfected E. coli cells with a 20&time; lens in a ≈50μm high flow channel. Approximately 5% of the cells reacted on the switch-on and -off of the blue light signal by changing significantly their swimming behavior. In Video 1 shows an E. lemming swimming in regular circles in a constant light environment. When switching the blue light on, it completely changes its motility after a 2-3s delay by swimming straight for several seconds. When the light is switched off, it returns to its original behavior after a similar delay (see paragraph [[ETHZ Basel/Achievements/E lemming#Characterization]|"Characterization"]).
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We imaged several transfected E. coli cells with a 20&time; lens in a ≈50μm high flow channel. Approximately 5% of the cells reacted on the switch-on and -off of the blue light signal by changing significantly their swimming behavior. In Video 1 shows an E. lemming swimming in regular circles in a constant light environment. When switching the blue light on, it completely changes its motility after a 2-3s delay by swimming straight for several seconds. When the light is switched off, it returns to its original behavior after a similar delay (see paragraph [[ETHZ Basel/Achievements/E lemming#Characterization]|"Characterization"]).
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== Characterization ==
== Characterization ==
[[Image:AngleOverTime.jpg|thumb|center|900px|'''Figure 1: Angle of the E. lemming'''  during one measurement (see Video 1) as calculated from the central differences of its positions. The estimated reaction times between the switching of the blue light and the reactions of the E. lemming are marked in the image. For the reaction delay between switch-on of the light and straight swimming we obtained &Delta;t<sub>1</sub>&asymp;2.1s and &Delta;t<sub>2</sub>&asymp;3.0s. For the delay between the switch-off of the blue light and start of tumbling it was only possible to estimate the time delay for the second light pulse, &Delta;t<sub>3</sub>&asymp;2.4s. White background: blue light off. Light blue background: blue light on.]]
[[Image:AngleOverTime.jpg|thumb|center|900px|'''Figure 1: Angle of the E. lemming'''  during one measurement (see Video 1) as calculated from the central differences of its positions. The estimated reaction times between the switching of the blue light and the reactions of the E. lemming are marked in the image. For the reaction delay between switch-on of the light and straight swimming we obtained &Delta;t<sub>1</sub>&asymp;2.1s and &Delta;t<sub>2</sub>&asymp;3.0s. For the delay between the switch-off of the blue light and start of tumbling it was only possible to estimate the time delay for the second light pulse, &Delta;t<sub>3</sub>&asymp;2.4s. White background: blue light off. Light blue background: blue light on.]]

Revision as of 13:06, 27 October 2010

The E. lemming

Experimental Results

We imaged several transfected E. coli cells with a 20&time; lens in a ≈50μm high flow channel. Approximately 5% of the cells reacted on the switch-on and -off of the blue light signal by changing significantly their swimming behavior. In Video 1 shows an E. lemming swimming in regular circles in a constant light environment. When switching the blue light on, it completely changes its motility after a 2-3s delay by swimming straight for several seconds. When the light is switched off, it returns to its original behavior after a similar delay (see paragraph [[ETHZ Basel/Achievements/E lemming#Characterization]|"Characterization"]).

Video 1: This video shows the E. lemming in action.
The unprocessed microscope images are available here.
Video 2: this the brother of the E. lemming, who decided to swim several times nearly out of focus and out of the field of view such that he had to be tracked manually..
The unprocessed microscope images are available here.

Characterization

Figure 1: Angle of the E. lemming during one measurement (see Video 1) as calculated from the central differences of its positions. The estimated reaction times between the switching of the blue light and the reactions of the E. lemming are marked in the image. For the reaction delay between switch-on of the light and straight swimming we obtained Δt1≈2.1s and Δt2≈3.0s. For the delay between the switch-off of the blue light and start of tumbling it was only possible to estimate the time delay for the second light pulse, Δt3≈2.4s. White background: blue light off. Light blue background: blue light on.
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