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Effects of surface passivation on gliding motility assays.

Maloney A, Herskowitz LJ, Koch SJ - PLoS ONE (2011)

Bottom Line: Beta casein did not support motility very well and averaged speeds of 870±30 nm/s.Kappa casein supported motility very poorly and we were unable to obtain an average speed.Finally, we observed that mixing alpha, beta, and kappa casein with the proportions found in bovine whole casein supported motility and averaged speeds of 966±6 nm/s.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy and Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico, United States of America. amaloney@unm.edu

ABSTRACT
In this study, we report differences in the observed gliding speed of microtubules dependent on the choice of bovine casein used as a surface passivator. We observed differences in both speed and support of microtubules in each of the assays. Whole casein, comprised of α(s1), α(s2), β, and κ casein, supported motility and averaged speeds of 966±7 nm/s. Alpha casein can be purchased as a combination of α(s1) and α(s2) and supported gliding motility and average speeds of 949±4 nm/s. Beta casein did not support motility very well and averaged speeds of 870±30 nm/s. Kappa casein supported motility very poorly and we were unable to obtain an average speed. Finally, we observed that mixing alpha, beta, and kappa casein with the proportions found in bovine whole casein supported motility and averaged speeds of 966±6 nm/s.

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Gliding speed measurements with kappa casein passivation.Green squares, red circles, and blue triangles represent 3 different                            assays. As the figure shows, kappa casein was not the ideal surface                            passivator. There were many regions in the flow cell with no motility                            and other regions that showed inconsistent motility and at much slower                            speeds than was reported from alpha, whole or mixed casein passivations.                            The open black circles show a characteristic alpha casein assay for                            comparison. Note that the initial increase in speed (time less than 500                            seconds) was due to the slide coming to thermal equilibrium with the                            objective. Because the three kappa casein samples appeared to have                            different speed distributions and because many regions of interest                            showed no motility, we did not attempt to compute a mean speed versus                            assay time, as was done in Figure 3 for the other caseins.
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pone-0019522-g004: Gliding speed measurements with kappa casein passivation.Green squares, red circles, and blue triangles represent 3 different assays. As the figure shows, kappa casein was not the ideal surface passivator. There were many regions in the flow cell with no motility and other regions that showed inconsistent motility and at much slower speeds than was reported from alpha, whole or mixed casein passivations. The open black circles show a characteristic alpha casein assay for comparison. Note that the initial increase in speed (time less than 500 seconds) was due to the slide coming to thermal equilibrium with the objective. Because the three kappa casein samples appeared to have different speed distributions and because many regions of interest showed no motility, we did not attempt to compute a mean speed versus assay time, as was done in Figure 3 for the other caseins.

Mentions: Figure 3 shows the mean speed measurements for 15 different regions of interest for the alpha, beta, whole and mixed casein assays. Each data point is the mean of a region of interest with SEM from three separate samples. The passivator that gave the most consistent speed was alpha casein. The mean speed and SEM from our alpha casein measurement was 949±4 nm/s. Purchased whole casein and mixed casein performed remarkably similarly and displayed average speed values of 966±7 nm/s and 966±7 nm/s respectively. Bovine beta casein performed poorly in comparison to alpha, whole, or mixed caseins and we measured the mean speed to be 870±30 nm/s. Figure 4 shows the observed speeds for kappa casein passivation. Since there were so many areas where no motility was observed in this assay, it was difficult to determine a mean speed measurement for each assay as was done in Figure 3. However, it does appear that when motile, the speeds were around 870–880 nm/s with kappa casein as the surface passivator. This was similar to how beta casein performed.


Effects of surface passivation on gliding motility assays.

Maloney A, Herskowitz LJ, Koch SJ - PLoS ONE (2011)

Gliding speed measurements with kappa casein passivation.Green squares, red circles, and blue triangles represent 3 different                            assays. As the figure shows, kappa casein was not the ideal surface                            passivator. There were many regions in the flow cell with no motility                            and other regions that showed inconsistent motility and at much slower                            speeds than was reported from alpha, whole or mixed casein passivations.                            The open black circles show a characteristic alpha casein assay for                            comparison. Note that the initial increase in speed (time less than 500                            seconds) was due to the slide coming to thermal equilibrium with the                            objective. Because the three kappa casein samples appeared to have                            different speed distributions and because many regions of interest                            showed no motility, we did not attempt to compute a mean speed versus                            assay time, as was done in Figure 3 for the other caseins.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3108588&req=5

pone-0019522-g004: Gliding speed measurements with kappa casein passivation.Green squares, red circles, and blue triangles represent 3 different assays. As the figure shows, kappa casein was not the ideal surface passivator. There were many regions in the flow cell with no motility and other regions that showed inconsistent motility and at much slower speeds than was reported from alpha, whole or mixed casein passivations. The open black circles show a characteristic alpha casein assay for comparison. Note that the initial increase in speed (time less than 500 seconds) was due to the slide coming to thermal equilibrium with the objective. Because the three kappa casein samples appeared to have different speed distributions and because many regions of interest showed no motility, we did not attempt to compute a mean speed versus assay time, as was done in Figure 3 for the other caseins.
Mentions: Figure 3 shows the mean speed measurements for 15 different regions of interest for the alpha, beta, whole and mixed casein assays. Each data point is the mean of a region of interest with SEM from three separate samples. The passivator that gave the most consistent speed was alpha casein. The mean speed and SEM from our alpha casein measurement was 949±4 nm/s. Purchased whole casein and mixed casein performed remarkably similarly and displayed average speed values of 966±7 nm/s and 966±7 nm/s respectively. Bovine beta casein performed poorly in comparison to alpha, whole, or mixed caseins and we measured the mean speed to be 870±30 nm/s. Figure 4 shows the observed speeds for kappa casein passivation. Since there were so many areas where no motility was observed in this assay, it was difficult to determine a mean speed measurement for each assay as was done in Figure 3. However, it does appear that when motile, the speeds were around 870–880 nm/s with kappa casein as the surface passivator. This was similar to how beta casein performed.

Bottom Line: Beta casein did not support motility very well and averaged speeds of 870±30 nm/s.Kappa casein supported motility very poorly and we were unable to obtain an average speed.Finally, we observed that mixing alpha, beta, and kappa casein with the proportions found in bovine whole casein supported motility and averaged speeds of 966±6 nm/s.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy and Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico, United States of America. amaloney@unm.edu

ABSTRACT
In this study, we report differences in the observed gliding speed of microtubules dependent on the choice of bovine casein used as a surface passivator. We observed differences in both speed and support of microtubules in each of the assays. Whole casein, comprised of α(s1), α(s2), β, and κ casein, supported motility and averaged speeds of 966±7 nm/s. Alpha casein can be purchased as a combination of α(s1) and α(s2) and supported gliding motility and average speeds of 949±4 nm/s. Beta casein did not support motility very well and averaged speeds of 870±30 nm/s. Kappa casein supported motility very poorly and we were unable to obtain an average speed. Finally, we observed that mixing alpha, beta, and kappa casein with the proportions found in bovine whole casein supported motility and averaged speeds of 966±6 nm/s.

Show MeSH