From 2013.igem.org

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Latest revision as of 03:53, 5 October 2013

Stay Warm, Stay Close

Our initial idea was to let the bacteria produce the silk in a bath and when the implant is put into the bath, the implant will be coated with silk. This is a wasteful and inelegant method. A low production yield can be expected and a solution is needed to overcome this problem. Therefore the heat motility was developed. With the help of heat motility the silk will be produced on site, this will also save energy in the form of nutrition and energy of heating the bath. An overview of our 'Coating GEM' is shown in figure 1.

Native Motility

The Motility in most bacteria is governed by the Che proteins [1], they control if the bacteria is swimming straight or tumbling (changing directions). They do this by controlling the flagella. If the flagella spin counter-clockwise (CCW) they will group together in one pole of the bacterium, causing straight swimming. On the other hand if the flagella are spinning clockwise (CW) then the flagella will disperse over the membrane and cause tumbling.

CheY

The Che proteins are present in many motile bacteria, however they can have different effects depending on the species [1]. The CheY protein in Bacillus subtilis, for example, has the complete opposite effect as in Escherichia coli. CheY is an important protein for controlling the spinning of the flagella. When the concentration of phosphorylated CheY (CheY-p) is sufficiently high the flagella turn CCW (straight swimming), but when the concentration of CheY decreases the chance of tumbling also increases, and the bacterium will reorient themselves more often.

Attractant Receptor

The chemotaxis process is initiated at the receptor, which can sense the concentration of an attractant (or repellent) [2]. Increasing concentrations of attractant correspond to an increased chance of swimming. If the concentration decreases, the bacteria will start to tumble more frequently, and will reorient its swimming direction, hopefully to more desirable regions.

cheA & CheC-CheD

Binding of the attractant receptor causes straight swimming via a small cascade [2]. When the receptor is bound, the CheA protein (which is attached to it) gets phosphorylated. The CheA-p phophorylates cheY, which then causes straight swimming. The protein complex CheC-CheD causes dephophorylation of cheY-p (when receptor is bound) resulting in a negative feedback. Two more negative feedback systems are also activated following the binding of attractant, which also result in decreased values of CheY-p. In such a way, CheY-p adaption occurs, and B. subtilis is ready to sense new changes in its environment. For more information about how this pathway works please visit the heat motility section.

Figure 1: The scheme shows B. subtilis containing knockouts of cheY, cheC and des. It also shows the motility gene and the silk gene positively controlled by cold and heat respectively.

Controllable motility

cheY Knockout

To make our coating mechanism a success we need to have control over the motility. This is achieved by knocking out cheY. This might sound strange since CheY-p is controlling straight swimming. However since we know that a CheY null mutant is immobile due to excessive tumbling. This makes it possible to insert cheY with a promoter of our choosing, and make it the sole producer of CheY. Also a cheC knockout is made in order to prevent negative feedback. How this is effecting the cell is explained in more detail with our model.

DesK pathway

We envision a bacterium that moves towards a heat source, in order to do this it needs a temperature sensor. B. subtilis natively has a protein that fits this requirement nicely. It is called DesK, it is a membrane protein that senses cold [3][4] (25°C). When the environment is cold, DesK autophophorylates, after which it phosphorylates DesR. DesR in turn activates the promoter of the des gene (P_des), which would be the promoter we are looking for. The des gene expresses a protein that provides negative feedback to the system, so we need to knockout this des gene to keep our promoter active.

Thermal control of fatty acid synthesis.

In order to maintain the fluidity of the cell membrane when the environmental temperature is decreasing, B. subtilis (among other bacteria) adapts the membrane by increasing the fraction of unsaturated phospholipids acyl chains.

The desaturation of the membrane starts with the membrane protein, DesK. DesK senses temperature of its environment and when the temperature is 30°C, DesK autophosphorylates its conserved histidine. Sequentially the phosphoryl group is transferred to the aspartate residue in desR that activates the promoter of des. The gene des is translated into a fatty acid desaturase (Δ5-Des), that changes the fluidity of the membrane by introducing double bonds into pre-existing saturated fatty acyl chains.

The promoter activity of des

Figure 2: Pattern of Pdes-lacZ expression on a temperature downshift.(a) B. subtilis AKP3 cells were grown at 37°C to an optical density of 0.4 at 525 nm and then divided into two fractions. The first was transferred to 25°C (●) and the second was kept at 37°C (○). (b) Pattern of Pdes-lacZ expression in a des‾ background. B. subtilis AKP4 cells were grown at 37°C to an optical density of 0.4 at 525 nm and then divided into two fractions. One fraction was transferred to 25°C (●) while the other was kept at 37°C (○). (c). Effect of exogenous fatty acids on Pdes-lacZ expression pattern. B. subtilis AKP4 cells were grown at 37°C to an optical density of 0.4 at 525 nm and then divided into two fractions. Each fraction was supplemented with palmitic (●) or oleic acid (■) and growth was continued at 25°C. (d) Effect of desKR disruption on Pdes-lacZ expression. B. subtilis AKP21 cells were grown at 37°C to an optical density of 0.4 at 525 nm and then divided into two fractions. One of the fractions was transferred to 25°C (●) and the other one was kept at 37°C (○). Optical density at 525 nm (inserts) and β-galactosidase specific activity were determined at the indicated times (a, b, c, or d).

Strain	Description
JH642	trpC2 pheA1
AKP3	JH642 amyE::[Pdes(-2269 to +31)lacZ]
AKP4	AKP3 des::kan
AKP21	AKP3 desKR::kan

Bredeston et al. 2011

The coating

The silk proteins are secreted with a Strep tag. The implant will be covered with biotin (vitamine B8). The Strep tag will automatically form a Van der Waals binding with the biotin and thus, if the silk is secreted closely the implant will be coated automatically. B.subtilis has a tendency to form a biofilm on a structure, or in our case an implant (insert proof that biofilm can grow in plastic/titanium) . To coat the implant we have thought of to option 1 via secretion and 2 via a biofilm formation. The secretion process is the most elegant and best option, but secretion of large proteins is proven to be difficult and has never been done before with silk. So a ‘backup’ plan was needed.

Animation

Motility of the knockout strains

To observe whether or not the mutant strains are less motile than the wild type strain different tests are done. One of the tests is performed using microscopy.

Microscope movies

Microscope movies (4x real time) are made for the wildtype, the ΔcheY and the ΔcheYΔdes strain. These movies show that the wildtype strain (Movie 1) is more motile than both mutant strains. The comparison between the movie of the ΔcheY (Movie 2) and ΔcheYΔdes (Movie 3) strain shows just as seen in the motility assay, that the ΔcheYΔdes strain is less motile than the ΔcheY strain.

Movie 1: Motility of the wild type strain

Movie 2: Motility of ΔcheY

Movie 3: Motility of ΔcheYΔdes

References

[1] Liam F. Garrity and George W. Ordal, Chemotaxis in Bacillus subtilis: How bacteria monitor environmental signals, Pharmacology and Therepeutics (1995), Vol. 68 No.1, pp. 87-104.
[2] Christopher V. Rao, George D. Glekas and George W. Ordal, The three adaptation systems of Bacillus subtilis chemotaxis, Trends in Biology (2008), Vol. 16 No 10, pp. 480-487.
[3] Mariana Martin and Diego de Mendoza, Regulation of Bacillus subtilis DesK thermosensor by lipids, Biochemical Journal (2013), Vol 451 No 2, pp. 269–275.
[4] Thermal Regulation of Membrane Lipid Fluidity by a Two-Component System in Bacillus subtilis, January 31 2011, BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Vol. 39, No. 5, pp. 362–366, 2011.

@@ Line 1: / Line 1: @@
 <html>
-<h2>Page set-up</h2>
+<h1>Stay Warm, Stay Close</h1>
-<h3>Why, what</h3>
+<p>
-<br>What are we doing
+Our initial idea was to let the bacteria produce the silk in a bath and when the implant is put into the bath, the implant will be coated with silk. This is a wasteful and inelegant method. A low production yield can be expected and a solution is needed to overcome this problem. Therefore the heat motility was developed. With the help of heat motility the silk will be produced on site, this will also save energy in the form of nutrition and energy of heating the bath. An overview of our 'Coating GEM' is shown in figure 1.
-<br>Why is it important
+</p>
-<br>Which genes are involved
+<br>
-<br>for motility, The che genes (most important ones), what they do in b.sub
+<h2>Native Motility</h2>
-<br>For temperature sensing, The des pathway
+<p>
+The Motility in most bacteria is governed by the Che proteins [1], they control if the bacteria is swimming straight or tumbling (changing directions). They do this by controlling the flagella. If the flagella spin counter-clockwise (CCW) they will group together in one pole of the bacterium, causing straight swimming.  On the other hand if the flagella are spinning clockwise (CW) then the flagella will disperse over the membrane and cause tumbling.
+<br>
+<h3>CheY</h3>
+The Che proteins are present in many motile bacteria, however they can have different effects depending on the species [1]. The CheY protein in <i>Bacillus subtilis</i>, for example, has the complete opposite effect as in <i>Escherichia coli</i>. CheY is an important protein for controlling the spinning of the flagella. When the concentration of phosphorylated CheY (CheY-p) is sufficiently high the flagella turn CCW (straight swimming), but when the concentration of CheY decreases the chance of tumbling also increases, and the bacterium will reorient themselves more often.
+</p>
+<h3>Attractant Receptor</h3>
+<p>
+The chemotaxis process is initiated at the receptor, which can sense the concentration of an attractant (or repellent) [2]. Increasing concentrations of attractant correspond to an increased chance of swimming. If the concentration decreases, the bacteria will start to tumble more frequently, and will reorient its swimming direction, hopefully to more desirable regions.
+</p>
+<h3>cheA & CheC-CheD</h3>
+Binding of the attractant receptor causes straight swimming via a small cascade [2]. When the receptor is bound, the CheA protein (which is attached to it) gets phosphorylated. The CheA-p phophorylates cheY, which then causes straight swimming. The protein complex CheC-CheD causes dephophorylation of cheY-p (when receptor is bound) resulting in a negative feedback. Two more negative feedback systems are also activated following the binding of attractant, which also result in decreased values of CheY-p. In such a way, CheY-p adaption occurs, and <i>B. subtilis</i> is ready to sense new changes in its environment. For more information about how this pathway works please visit the <a href="https://2013.igem.org/Team:Groningen/Navigation/Heatmotility#six">heat motility section</a>.
+</p>
+<br>
-<h3>Construct</h3>
-All the pictures of our construct.
-<br>Short explanation.
-<h3>Scenario's</h3>
+<div align="left">
-<br>Moving towards heat
-<br>Not moving towards heat
-<br>Moving towards cold.
-<h3>Results</h3>
+<table id="layout" width="90%">
-Labresults, cheY is inmobile.
+<tr>
-<br>Moddeling results, short summary and a link to the modelling page.
+<td>
-<h3>-----------------------------------------------------</h3>
+<img src="http://img844.imageshack.us/img844/289/kwv.png" width="100%" >
-<h3>Back-up plans</h3>
+</td>
-<br>Swirling mechanism collecting all the strep
+</tr>
-<br>(Biofilm +killswitch)
+<tr>
+<td>
+<font size="1">Figure 1: The scheme shows <i>B. subtilis</i> containing knockouts of <i>cheY</i>, <i>cheC</i> and <i>des</i>. It also shows the motility gene and the silk gene positively controlled by cold and heat respectively. </font>
+</td>
+</tr>
+</table>
+</div>
 <br>
 <br>
-<h1>The Coating Mechanism</h1>
+<h2>Controllable motility</h2>
+<h3 id = "special"><i>cheY</i> Knockout</h3>
 <p>
-Our initial idea was to let bacteria produce the silk in a bath and of the implant is put into the bath the implant will be coated. Because a low yield can be expected and with the recent developments of porous implants a more elegant solution is needed, because the silk has to be produced on site. Therefore the heat motility was developed. with the use of heat motility the silk will be produced on site, this will also save energy in the form of nutritions and energy of heating the bath.
+To make our coating mechanism a success we need to have control over the motility. This is achieved by knocking out <i>cheY</i>. This might sound strange since CheY-p is controlling straight swimming.  However since we know that a CheY null mutant is immobile due to excessive tumbling. This makes it possible to insert <i>cheY</i> with a promoter of our choosing, and make it the sole producer of CheY. Also a <i>cheC</i> knockout is made in order to prevent negative feedback.  How this is effecting the cell is explained in more detail with our <a href="https://2013.igem.org/Team:Groningen/Navigation/Heatmotility#six">model</a>.
 </p>
+<h3>DesK pathway</h3>
 <p>
-In case the silk cannot be secreted the coating will be done by a biofilm formation on the implant. (need to improve this)
+We envision a bacterium that moves towards a heat source, in order to do this it needs a temperature sensor. <i>B. subtilis</i> natively has a protein that fits this requirement nicely. It is called DesK, it is a membrane protein that senses cold [3][4] (25&deg;C). When the environment is cold, DesK autophophorylates, after which it phosphorylates DesR. DesR in turn activates the promoter of the des gene (P<sub><i>des</i></sub>), which would be the promoter we are looking for. The <i>des</i> gene expresses a protein that provides negative feedback to the system, so we need to knockout this des gene to keep our promoter active.
-<p>
+</p>
 <br>
-<h2> Heat Motility </h2>
-<Br>
-In order to have a system for targeted secretion, we came up with a system that would move according to the temperature of the environment. This is a nice idea since implants can be easily heated. First we made a system in which the motility of <i>Bacillus subtilis</i> could be controlled via knocking out the motility gene <i>cheY</i>. We could now introduce any particular promoter in front of our cheY gene and thus controlling the motility. This system in combination with our general chemotaxis model allow for good control of the cell. The promoter from the thermosensing des pathway, that is natively present in <i>Bascillus subtilis</i>, was fused to a <i>cheY</i> gene. In the end the thermotaxis model showed that this approach for controllable motility worked.
 <h3>Thermal control of fatty acid synthesis.</h3>
@@ Line 49: / Line 58: @@
 </p>
 <p>
-The desaturation of the membrane starts with the membrane protein, DesK. DesK senses temperature of its environment and when the temperature is <30 &deg;C, DesK autophosphorylates its conserved histidine. Sequentially the phosphoryl group is transferred to the aspartate residue in desR that activates the promoter of <i>des</i>. The gene <i>des</i> is translated into a fatty acid desaturase (&Delta;5-Des), that changes the fluidity of the membrane by introducing
+The desaturation of the membrane starts with the membrane protein, DesK. DesK senses temperature of its environment and when the temperature is 30&deg;C, DesK autophosphorylates its conserved histidine. Sequentially the phosphoryl group is transferred to the aspartate residue in desR that activates the promoter of <i>des</i>. The gene <i>des</i> is translated into a fatty acid desaturase (&Delta;5-Des), that changes the fluidity of the membrane by introducing
 double bonds into pre-existing saturated fatty acyl chains.
 </p>
@@ Line 67: / Line 76: @@
 <tr>
 <td>
-<font size="1">Figure 1: Pattern of P<i>des</i>-<i>lacZ</i> expression on a temperature downshift.</b>(a) <i>B. subtilis</i> AKP3 cells were grown at 37 &deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. The first was transferred to 25 &deg;C (&#9679;) and the second was kept at 37 &deg;C (&#9675;). (b) Pattern of P<i>des</i>-<i>lacZ</i> expression in a <i>des</i>&#8254; background. <i>B. subtilis</i> AKP4 cells were grown at 37 &deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. One fraction was transferred to 25 &deg;C (&#9679;) while the other was kept at 37 &deg;C (&#9675;). (c). Effect of exogenous fatty acids on P<i>des</i>-<i>lacZ</i> expression pattern. <i>B. subtilis</i> AKP4 cells were grown at 37 &deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. Each fraction was supplemented with palmitic (&#9679;) or oleic acid (&#9632;) and growth was continued at 25 &deg;C. (d) Effect of <i>desKR</i> disruption on P<i>des</i>-<i>lacZ</i> expression. <i>B. subtilis</i> AKP21 cells were grown at 37 &deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. One of the fractions was transferred to 25 &deg;C (&#9679;) and the other one was kept at 37 &deg;C (&#9675;). Optical density at 525 nm (inserts) and &beta;-galactosidase specific activity were determined at the indicated times (a, b, c, or d). </font>
+<font size="1">Figure 2: Pattern of P<i>des</i>-<i>lacZ</i> expression on a temperature downshift.</b>(a) <i>B. subtilis</i> AKP3 cells were grown at 37&deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. The first was transferred to 25&deg;C (&#9679;) and the second was kept at 37&deg;C (&#9675;). (b) Pattern of P<i>des</i>-<i>lacZ</i> expression in a <i>des</i>&#8254; background. <i>B. subtilis</i> AKP4 cells were grown at 37&deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. One fraction was transferred to 25&deg;C (&#9679;) while the other was kept at 37&deg;C (&#9675;). (c). Effect of exogenous fatty acids on P<i>des</i>-<i>lacZ</i> expression pattern. <i>B. subtilis</i> AKP4 cells were grown at 37&deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. Each fraction was supplemented with palmitic (&#9679;) or oleic acid (&#9632;) and growth was continued at 25&deg;C. (d) Effect of <i>desKR</i> disruption on P<i>des</i>-<i>lacZ</i> expression. <i>B. subtilis</i> AKP21 cells were grown at 37&deg;C to an optical density of 0.4 at 525 nm and then divided into two fractions. One of the fractions was transferred to 25&deg;C (&#9679;) and the other one was kept at 37&deg;C (&#9675;). Optical density at 525 nm (inserts) and &beta;-galactosidase specific activity were determined at the indicated times (a, b, c, or d). </font>
 </td>
 </tr>
@@ Line 108: / Line 117: @@
-<br><Br><b>Bredeston <i>et al.</i> 2011</b>
+<b>Bredeston <i>et al.</i> 2011</b>
 </p>
-<Br><br><br>
+<Br><br>
+<!--
 <h2>Motility</h2>
-<p>
-Bacterial movement is based on flagella (tail like structures) and utilizes a counter-clockwise (CCW)
-and clockwise (CW) motion. When the flagella turn CCW they gather in one area resulting in
-bacteria that move straight. When the flagella move CW they disperse all over the cell membrane,
-resulting in the bacteria tumbling in random directions. When bacteria sense an
-attractant the flagellar motion will turn CCW, when the concentration of the attractant reduces the flagella will turn CW.
-</p>
-<p>
-The receptor is displayed in the figure on the page below. The letters are all Che proteins, with this
-cascade of proteins motility is coordinated. When a attractant is bound to the receptor, CheA
-phosphorylizes CheY into CheY-P. CheY-P causes the CCW motility in the flagella, it also causes
-(by forming a CheY-p/CheC complex) that CheD is pulled off the receptor. CheD and CheC forms
-also a complex which dephosphorylizes CheY-p into CheY thus resetting the receptor.
-<Br><br><br><Br><br><br><Br><br><br>
 <h3>The principle</h3>
-CheY is a mayor factor in spinning the flagella CCW. When <i>cheY</i> is absent, cells are significant less motile[ref]. Because the promoter of <i>des</i> is active at low temperatures (25 &deg;C) we placed <i>cheY</i> under control of the promoter of <i>des</i> (figure 2).
+CheY is a mayor factor in spinning the flagella CCW. When <i>cheY</i> is absent, cells are significant less motile[ref]. Because the promoter of <i>des</i> is active at low temperatures (25&deg;C) we placed <i>cheY</i> under control of the promoter of <i>des</i> (figure 2).
 <br>
+-->
-<div align="left">
-<table id="layout" width="30%">
-<tr>
-<td>
-<img src="https://static.igem.org/mediawiki/2013/6/6f/HM_strain.jpg" width="100%" >
-</td>
-</tr>
-<tr>
-<td>
-<font size="1">Figure 2: </font>
-</td>
-</tr>
-</table>
-</div>
-<Br>
-<Br><Br>
-<div align="left">
-<table id="layout" width="30%">
-<tr>
-<td>
-<img src="https://static.igem.org/mediawiki/2013/9/9e/Project_setup-01.jpg" width="100%">
-</td>
-</tr>
-<tr>
-<td>
-<font size="1">Figure 3: </font>
-</td>
-</tr>
-</table>
-</div>
 <br>
-<h2> Biofilm</h2>
-(..)
 <h2>The coating</h2>
-The silk proteins are secreted with a Strep tag. The implant will be covered with biotin (vitamine B8). The Strep tag will automatically form a Van der Waals binding with the biotin and thus, if the silk is secreted closely the implant will be coated automatically. B.subtilis has a tendency to form a biofilm on a structure, or in our case an implant (insert proof that biofilm can grow in plastic/titanium) . To coat the implant we have thought of to option 1 via secretion and 2 via a biofilm formation. The secretion process is the most elegant and best option, but secretion of large proteins is proven to be difficult and has never been done before with silk. So a ‘backup’ plan was needed.
+The silk proteins are secreted with a Strep tag. The implant will be covered with biotin (vitamine B8). The Strep tag will automatically form a Van der Waals binding with the biotin and thus, if the silk is secreted closely the implant will be coated automatically. <i>B.subtilis</i> has a tendency to form a biofilm on a structure, or in our case an implant (insert proof that biofilm can grow in plastic/titanium) . To coat the implant we have thought of to option 1 via secretion and 2 via a biofilm formation. The secretion process is the most elegant and best option, but secretion of large proteins is proven to be difficult and has never been done before with silk. So a ‘backup’ plan was needed.
-<Br>
+<br>
+<br>
 <h2>Animation</h2>
 <video  controls width="40%">
@@ Line 193: / Line 144: @@
-<h2><i>cheY</i> and <i>des</i> knockout </h2>
+<br>
-<br>For our heat motility model we need at least a double knockout strain of <i>B.subtilis</i>. A knockout of both <i>cheY</i> and <i>des</i> are necessary. To obtain the double knockout strain, first a knockout of <i>cheY</i> is made after which the <i>des</i> knockout is inserted.
-<h3>Correct insertion of the <i>des</i> knockout</h3>
-A knockout of gene <i>des</i> is inserted into the genomic DNA of <i>B.subtilis</i> strain 168 with a tetracyclin resistance marker. Colony PCR showed that <i>des</i> is indeed transformed into the genomic DNA (Figure 1).
-<div align="left">  <!--you can use left/right or center to align the image-->
-<table  id="layout" width=30%> <!--change the percentage to determine the size of your image-->
-<tr>
-<td>
-<img src="https://static.igem.org/mediawiki/2013/b/b0/DeltaDES.jpg" width="100%"> <!--only insert the link, do not change the percentage!-->
-</td>
-</tr>
-<tr>
-<td>
-<font size="1">Figure 1: Colony PCR of the <i>des</i> knock out </font>
-</td>
-</tr>
-</table>
-</div>
 <h3>Motility of the knockout strains</h3>
-To observe whether or not the mutant strains are less motile than the wild type strain. Two different tests are done.
+To observe whether or not the mutant strains are less motile than the wild type strain different tests are done. One of the tests is performed using microscopy.
-<h4>Motility assay</h4>
-To compare the motility of the wildtype strain with the two knockout strains, &Delta;cheY and &Delta;cheY&Delta;des, a motility assay is made. When the strains are grown on a 0.4% LB agar plate, after 16 hours of growth it is visible that the wildtype strain shows more swimming behaviour than both of the mutant strains (Figure 2).
-<div align="left">  <!--you can use left/right or center to align the image-->
-<table  id="layout" width=40%> <!--change the percentage to determine the size of your image-->
-<tr>
-<td>
-<img src="https://static.igem.org/mediawiki/2013/f/f8/Figure_motility_assay.png" width="100%"> <!--only insert the link, do not change the percentage!-->
-</td>
-</tr>
-<tr>
-<td>
-<font size="1">Figure 2: Motility assay results after 16 hours of growth</font>
-</td>
-</tr>
-</table>
-</div>
 <h4>Microscope movies</h4>
-Another way of analyzing the swimming behaviour is to make real time microscope movies. These movies are made for the wildtype, the &Delta;cheY and the &Delta;cheY&Delta;des strain. Visible is that the wildtype is motile whereas the knockout strains are not (Movie 1-3).
+Microscope movies (4x real time) are made for the wildtype, the &Delta;cheY and the &Delta;cheY&Delta;des strain. These movies show that the wildtype strain (Movie 1) is more motile than both mutant strains. The comparison between the movie of the &Delta;cheY (Movie 2) and &Delta;cheY&Delta;des (Movie 3) strain shows just as seen in the motility assay, that the &Delta;cheY&Delta;des strain is less motile than the &Delta;cheY strain.
+<br>
 <br><iframe width="420" height="315" src="//www.youtube.com/embed/vRjSmewTEDc" frameborder="0" allowfullscreen></iframe>
 <br><font size="1">Movie 1: Motility of the wild type strain</font>
+<br>
 <br><iframe width="420" height="315" src="//www.youtube.com/embed/Seilf16g3OI" frameborder="0" allowfullscreen></iframe>
 <br><font size="1">Movie 2: Motility of &Delta;cheY</font>
+<br>
 <br><iframe width="420" height="315" src="//www.youtube.com/embed/Y_qiqkzbAj8" frameborder="0" allowfullscreen></iframe>
 <br><font size="1">Movie 3: Motility of &Delta;cheY&Delta;des</font>
+<br>
+<br>
 <h2>References</h2>
+<font size="1,5">
 <p>
- Mariana Martin and Diego de Mendoza , Regulation of Bacillus subtilis DesK thermosensor by lipids, <i>Biochemical Journal</i> (2013), Vol 451 No 2, pp. 269–275
+[1] Liam F. Garrity and George W. Ordal, Chemotaxis in <i>Bacillus subtilis</i>: How bacteria monitor environmental signals, <i>Pharmacology and Therepeutics</i> (1995), Vol. 68 No.1, pp. 87-104.
-Christopher V. Rao, George D. Glekas and George W. Ordal, The three adaptation systems of Bacillus subtilis chemotaxis, <i>Trends in Biology</i> (2008), Vol. 16 No 10, pp. 480-487.
+<br>[2] Christopher V. Rao, George D. Glekas and George W. Ordal, The three adaptation systems of <i>Bacillus subtilis</i> chemotaxis, <i>Trends in Biology</i> (2008), Vol. 16 No 10, pp. 480-487.
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Team:Groningen/Project/Motility