Main Page/BPHS 4090/ElectroPhysiology of Chara revised - Revision history

Mgeorge at 15:42, 15 November 2013

2013-11-15T15:42:21Z

Mgeorge at 15:42, 15 November 2013

2013-11-15T15:42:02Z

Mgeorge at 15:41, 15 November 2013

2013-11-15T15:41:12Z

Mgeorge at 15:39, 15 November 2013

2013-11-15T15:39:57Z

Mgeorge at 15:38, 15 November 2013

2013-11-15T15:38:33Z

Mgeorge at 15:35, 15 November 2013

2013-11-15T15:35:33Z

Mgeorge at 15:28, 15 November 2013

2013-11-15T15:28:22Z

Mgeorge at 15:26, 15 November 2013

2013-11-15T15:26:06Z

Mgeorge at 15:21, 15 November 2013

2013-11-15T15:21:15Z

Mgeorge at 15:19, 15 November 2013

2013-11-15T15:19:03Z

@@ Line 231: / Line 231: @@
 <h2>Molecular Motors</h2>
 [[File:Nitella_ligature.png|200px|right]]
-Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) ''Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches''. [http://link.springer.com/article/10.1007%2FBF02488723 Botanical Magazine (Tokyo) '''99''':441–467].</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) ''The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin''. [http://www.sciencedirect.com/science/article/pii/001457939501208V FEBS Letters '''375''':151–154].</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) ''Cell and molecular biology of the fastest myosins''. [http://www.sciencedirect.com/science/article/pii/S1937644809760071 International Review of Cell and Molecular Biology '''276''':301–347].</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) ''Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin''.[http://www.pnas.org/content/106/51/21585.abstract Proceedings of the National Academy of Sciences (USA) '''106''':21585–21590].</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) ''A kinetic mechanism for the fast movement of ''Chara'' myosin''. [http://www.sciencedirect.com/science/article/pii/S0022283603003413 Journal of Molecular Biology '''328''':939–950].</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) ''Microfluidics of cytoplasmic streaming and its implications for intracellular transport''. [http://www.pnas.org/content/105/10/3663.abstract Proceedings of the National Academy of Science, USA '''105''':3663–3667].</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) ''Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry''.[http://arxiv.org/abs/0904.2707 arXiv:0904.2707v1 [physics.bio-ph]]</ref>).
+Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) ''Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches''. [http://link.springer.com/article/10.1007%2FBF02488723 Botanical Magazine (Tokyo) '''99''':441–467].</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) ''The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin''. [http://www.sciencedirect.com/science/article/pii/001457939501208V FEBS Letters '''375''':151–154].</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) ''Cell and molecular biology of the fastest myosins''. [http://www.sciencedirect.com/science/article/pii/S1937644809760071 International Review of Cell and Molecular Biology '''276''':301–347].</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) ''Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin''.[http://www.pnas.org/content/106/51/21585.abstract Proceedings of the National Academy of Sciences (USA) '''106''':21585–21590].</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) ''A kinetic mechanism for the fast movement of ''Chara'' myosin''. [http://www.sciencedirect.com/science/article/pii/S0022283603003413 Journal of Molecular Biology '''328''':939–950].</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) ''Microfluidics of cytoplasmic streaming and its implications for intracellular transport''. [http://www.pnas.org/content/105/10/3663.abstract Proceedings of the National Academy of Science, USA '''105''':3663–3667].</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) ''Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry''.[http://arxiv.org/abs/0904.2707 arXiv:0904.2707v1]</ref>).
 <h2>Future Research</h2>

@@ Line 328: / Line 328: @@
 <table width=700 border=1 align=center><td>
 <p align=justify>[[File:02_Figure_2.5.PNG‎|400px|right]]
-<b>''Chara'' Life Cycle</b> Various structures of the ''Chara'' life cycle are shown (from Lee, 1980)<ref>Lee, R.E. (1980) Phycology. Cambridge University Press. pp 441–445.</ref>. The nucule is the female organ, the globule is the male organ. The eggs are fertilized by a motile sperm cell (antherozoid). The sperm cells swim with a twisting motion (almost a Drunkard’s walk) as they search for the egg cells. Once fertilized, the zygospore (diploid) may remain dormant for extended periods of time (up to 40 years based on recovery of germinating material from old lake sediments). Once released from dormancy (which requires light), the first division is meiotic, so that the vegetative structures are haploid. Rhizoids grow into the pond sediment. Once anchored, the filamentous internode and whorl cells grow upward towards the water surface. The internode cells are multinucleate.
+<b>''Chara'' Life Cycle</b> Various structures of the ''Chara'' life cycle are shown (from Lee, 1980)<ref>Lee, R.E. (1980) ''Phycology''. Cambridge University Press. pp 441–445.</ref>. The nucule is the female organ, the globule is the male organ. The eggs are fertilized by a motile sperm cell (antherozoid). The sperm cells swim with a twisting motion (almost a Drunkard’s walk) as they search for the egg cells. Once fertilized, the zygospore (diploid) may remain dormant for extended periods of time (up to 40 years based on recovery of germinating material from old lake sediments). Once released from dormancy (which requires light), the first division is meiotic, so that the vegetative structures are haploid. Rhizoids grow into the pond sediment. Once anchored, the filamentous internode and whorl cells grow upward towards the water surface. The internode cells are multinucleate.
 <br clear=right>
 </p>

@@ Line 234: / Line 234: @@
 <h2>Future Research</h2>
-The continued use of Characean algae in biophysical research is certain. What research will be done? That depends upon the development of new technologies, and the pressing need to elucidate fundamental biological research problems. Braun et al. (2007)<ref>Braun M., Foissner, I., Luhring, H., Schubert H. and G. Theil (2007) ''Characean algae: Still a valid model system system to examine fundamental principles in plants''. [http://link.springer.com/chapter/10.1007%2F978-3-540-36832-8_9 Progress in Botany '''68''':193–220].</ref> describe some of the biological research problems that can be addressed using this “model system ''par excellence'' to study basic physiological and cell biological phenomenon in plants”. These include pattern formation, sensing of gravity and growth responses thereof, polarized growth, cytoskeleton dynamics, photosynthesis (especially coordinated metabolic pathways that involve multiple organelles), wound-healing, calcium signaling, and even sex determination. As to new technologies, the use of nmr imaging and even magnetic field measurements using a superconducting quantum interference device magnetometer (Baudenbacher et al., 2005<ref>Baudenbacher F., Fong, L.E., Thiel G., Wacke, M., Jazbinsek V., Holzer, J.R., Stampfl, A. and Z. Trontelj (2005) Intracellular axial current in Chara corallina reflects the altered kinetics of ions in cytoplasm under the influence of light. Biophysical Journal 88:690–697.</ref>) suggest that as new technologies are developed, biophysicist will turn to ''Chara'' as a tried and true model system for validation of new techniques.
+The continued use of Characean algae in biophysical research is certain. What research will be done? That depends upon the development of new technologies, and the pressing need to elucidate fundamental biological research problems. Braun et al. (2007)<ref>Braun M., Foissner, I., Luhring, H., Schubert H. and G. Theil (2007) ''Characean algae: Still a valid model system system to examine fundamental principles in plants''. [http://link.springer.com/chapter/10.1007%2F978-3-540-36832-8_9 Progress in Botany '''68''':193–220].</ref> describe some of the biological research problems that can be addressed using this “model system ''par excellence'' to study basic physiological and cell biological phenomenon in plants”. These include pattern formation, sensing of gravity and growth responses thereof, polarized growth, cytoskeleton dynamics, photosynthesis (especially coordinated metabolic pathways that involve multiple organelles), wound-healing, calcium signaling, and even sex determination. As to new technologies, the use of nmr imaging and even magnetic field measurements using a superconducting quantum interference device magnetometer (Baudenbacher et al., 2005<ref>Baudenbacher F., Fong, L.E., Thiel G., Wacke, M., Jazbinsek V., Holzer, J.R., Stampfl, A. and Z. Trontelj (2005) ''Intracellular axial current in Chara corallina reflects the altered kinetics of ions in cytoplasm under the influence of light''. [http://www.sciencedirect.com/science/article/pii/S0006349505731428 Biophysical Journal '''88''':690–697].</ref>) suggest that as new technologies are developed, biophysicist will turn to ''Chara'' as a tried and true model system for validation of new techniques.
 {|border="1"

@@ Line 234: / Line 234: @@
 <h2>Future Research</h2>
-The continued use of Characean algae in biophysical research is certain. What research will be done? That depends upon the development of new technologies, and the pressing need to elucidate fundamental biological research problems. Braun et al. (2007)<ref>Braun M., Foissner, I., Luhring, H., Schubert H. and G. Theil (2007) Characean algae: Still a valid model system system to examine fundamental principles in plants. Progress in Botany 68:193–220.</ref> describe some of the biological research problems that can be addressed using this “model system ''par excellence'' to study basic physiological and cell biological phenomenon in plants”. These include pattern formation, sensing of gravity and growth responses thereof, polarized growth, cytoskeleton dynamics, photosynthesis (especially coordinated metabolic pathways that involve multiple organelles), wound-healing, calcium signaling, and even sex determination. As to new technologies, the use of nmr imaging and even magnetic field measurements using a superconducting quantum interference device magnetometer (Baudenbacher et al., 2005<ref>Baudenbacher F., Fong, L.E., Thiel G., Wacke, M., Jazbinsek V., Holzer, J.R., Stampfl, A. and Z. Trontelj (2005) Intracellular axial current in Chara corallina reflects the altered kinetics of ions in cytoplasm under the influence of light. Biophysical Journal 88:690–697.</ref>) suggest that as new technologies are developed, biophysicist will turn to ''Chara'' as a tried and true model system for validation of new techniques.
+The continued use of Characean algae in biophysical research is certain. What research will be done? That depends upon the development of new technologies, and the pressing need to elucidate fundamental biological research problems. Braun et al. (2007)<ref>Braun M., Foissner, I., Luhring, H., Schubert H. and G. Theil (2007) ''Characean algae: Still a valid model system system to examine fundamental principles in plants''. [http://link.springer.com/chapter/10.1007%2F978-3-540-36832-8_9 Progress in Botany '''68''':193–220].</ref> describe some of the biological research problems that can be addressed using this “model system ''par excellence'' to study basic physiological and cell biological phenomenon in plants”. These include pattern formation, sensing of gravity and growth responses thereof, polarized growth, cytoskeleton dynamics, photosynthesis (especially coordinated metabolic pathways that involve multiple organelles), wound-healing, calcium signaling, and even sex determination. As to new technologies, the use of nmr imaging and even magnetic field measurements using a superconducting quantum interference device magnetometer (Baudenbacher et al., 2005<ref>Baudenbacher F., Fong, L.E., Thiel G., Wacke, M., Jazbinsek V., Holzer, J.R., Stampfl, A. and Z. Trontelj (2005) Intracellular axial current in Chara corallina reflects the altered kinetics of ions in cytoplasm under the influence of light. Biophysical Journal 88:690–697.</ref>) suggest that as new technologies are developed, biophysicist will turn to ''Chara'' as a tried and true model system for validation of new techniques.
 {|border="1"

@@ Line 231: / Line 231: @@
 <h2>Molecular Motors</h2>
 [[File:Nitella_ligature.png|200px|right]]
-Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) ''Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches''. [http://link.springer.com/article/10.1007%2FBF02488723 Botanical Magazine (Tokyo) '''99''':441–467].</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) ''The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin''. [http://www.sciencedirect.com/science/article/pii/001457939501208V FEBS Letters '''375''':151–154].</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) ''Cell and molecular biology of the fastest myosins''. [http://www.sciencedirect.com/science/article/pii/S1937644809760071 International Review of Cell and Molecular Biology '''276''':301–347].</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) ''Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin''.[http://www.pnas.org/content/106/51/21585.abstract Proceedings of the National Academy of Sciences (USA) '''106''':21585–21590].</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) ''A kinetic mechanism for the fast movement of ''Chara'' myosin''. [http://www.sciencedirect.com/science/article/pii/S0022283603003413 Journal of Molecular Biology '''328''':939–950].</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) Microfluidics of cytoplasmic streaming and its implications for intracellular transport. Proceedings of the National Academy of Science, USA 105:3663–3667.</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry. arXiv:0904.2707v1 [physics.bio-ph]</ref>).
+Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) ''Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches''. [http://link.springer.com/article/10.1007%2FBF02488723 Botanical Magazine (Tokyo) '''99''':441–467].</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) ''The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin''. [http://www.sciencedirect.com/science/article/pii/001457939501208V FEBS Letters '''375''':151–154].</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) ''Cell and molecular biology of the fastest myosins''. [http://www.sciencedirect.com/science/article/pii/S1937644809760071 International Review of Cell and Molecular Biology '''276''':301–347].</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) ''Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin''.[http://www.pnas.org/content/106/51/21585.abstract Proceedings of the National Academy of Sciences (USA) '''106''':21585–21590].</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) ''A kinetic mechanism for the fast movement of ''Chara'' myosin''. [http://www.sciencedirect.com/science/article/pii/S0022283603003413 Journal of Molecular Biology '''328''':939–950].</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) ''Microfluidics of cytoplasmic streaming and its implications for intracellular transport''. [http://www.pnas.org/content/105/10/3663.abstract Proceedings of the National Academy of Science, USA '''105''':3663–3667].</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) ''Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry''.[http://arxiv.org/abs/0904.2707 arXiv:0904.2707v1 [physics.bio-ph]]</ref>).
 <h2>Future Research</h2>

@@ Line 224: / Line 224: @@
 <table width=800 border=1 align=center><td>
 <p align=justify>[[File:02_Figure_2.4.PNG‎|500px|right]]
-<b>Figure 2.4: Internal perfusion of an internodal Chara cell (Tazawa and Kishimoto, 1968)<ref>Tazawa M. and U. Kishimoto (1968) Cessation of cytoplasmic streaming of Chara internodes during action potential. Plant & Cell Physiology. 9:361–368</ref></b> The cut ends are submersed in an artificial cell sap in the wells A and B. Not only can this technique be used for model organisms like ''Chara'' but also for animal cells of similar large size. Thus, internal perfusion was used to good advantage in initial studies of the action potential of the squid giant neuron, a system also used to unravel mechanisms of pH regulation.
+<b>Figure 2.4: Internal perfusion of an internodal Chara cell (Tazawa and Kishimoto, 1968)<ref>Tazawa M. and U. Kishimoto (1968) ''Cessation of cytoplasmic streaming of Chara internodes during action potential''. [http://pcp.oxfordjournals.org/content/9/2/361.abstract Plant & Cell Physiology. '''9''':361–368]</ref></b> The cut ends are submersed in an artificial cell sap in the wells A and B. Not only can this technique be used for model organisms like ''Chara'' but also for animal cells of similar large size. Thus, internal perfusion was used to good advantage in initial studies of the action potential of the squid giant neuron, a system also used to unravel mechanisms of pH regulation.
 <br clear=right>
 </p>
@@ Line 231: / Line 231: @@
 <h2>Molecular Motors</h2>
 [[File:Nitella_ligature.png|200px|right]]
-Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches. Botanical Magazine (Tokyo) 99:441–467.</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin. FEBS Letters 375:151–154.</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) Cell and molecular biology of the fastest myosins. International Review of Cell and Molecular Biology 276:301–347.</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin. Proceedings of the National Academy of Sciences (USA) 106:21585–21590.</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) A kinetic mechanism for the fast movement of ''Chara'' myosin. Journal of Molecular Biology 328:939–950.</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) Microfluidics of cytoplasmic streaming and its implications for intracellular transport. Proceedings of the National Academy of Science, USA 105:3663–3667.</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry. arXiv:0904.2707v1 [physics.bio-ph]</ref>).
+Protoplasmic streaming is something you should be able to observe during your experimental exercise. The first experiments on protoplasmic streaming in ''Chara'' date back to the early-1800’s, when Dutrochet performed surgical ligations of the internodal cells (''op cit.'' Kamiya, 1986<ref>Kamiya, N. (1986) ''Cytoplasmic streaming in giant algal cells: A historical survey of experimental approaches''. [http://link.springer.com/article/10.1007%2FBF02488723 Botanical Magazine (Tokyo) '''99''':441–467].</ref>). Kamiya (1986) describes the many other micromanipulations that were used to elucidate the biophysical properties of protoplasmic streaming (ligature experiments by Varley in 1844 are shown in the watercolor [right]). What makes this phenomenon even more fascinating is the unabated interest in protoplasmic streaming in ''Chara'' that continues to this day. On the one hand, it is now clear that ''Chara'' has the fastest known myosin molecular motor (this is the motive force for protoplasmic streaming) (Higashi-Fujime et al., 1995<ref>Higashi-Fujime, S.,  Ishikawa, R., Iwasawa, H., Kagami, O., Kurimoto. E., Kohama, K. and T. Hozumi (1995) ''The fastest actin-based motor protein from the green algae, ''Chara'', and its distinct mode of interaction with actin''. [http://www.sciencedirect.com/science/article/pii/001457939501208V FEBS Letters '''375''':151–154].</ref>; Higashi-Fujime and Nakamura, 2007<ref>Higashi-Fujime, S. and A. Nakamura (2007) Cell and molecular biology of the fastest myosins. International Review of Cell and Molecular Biology 276:301–347.</ref>; Ito et  al., 2009<ref>Ito, K., Yamaguchi, Y., Yanase, K., Ichikawa, Y. and K. Yamamoto (2009) Unique charge distribution in surface loops confers high velocity on the fast motor protein Chara myosin. Proceedings of the National Academy of Sciences (USA) 106:21585–21590.</ref>). The molecular mechanism of the Chara myosin motor was studied by the optical tweezer technique: Kimura et al. (2003)<ref>Kimura, Y., Toyoshima, N., Hirakawa, N., Okamoto, K. and A. Ishijima (2003) A kinetic mechanism for the fast movement of ''Chara'' myosin. Journal of Molecular Biology 328:939–950.</ref> held an actin filament with dual optical tweezers (one at each end) and measured the force as the actin filament was displaced by the step-wise motion of the ''Chara'' myosin motor. One the other hand, protoplasmic streaming offers insight into the interplay between mass flow and diffusion in the context of micro-fluidics (Goldstein et al., 2008<ref>Goldstein, R.E., Tuval, I. and J-W van de Meent (2008) Microfluidics of cytoplasmic streaming and its implications for intracellular transport. Proceedings of the National Academy of Science, USA 105:3663–3667.</ref>), as measured by magnetic resonance velocimetry (van de Meent et al., 2009<ref>Van de Meent, J-W., Sederman, A.J.,  Gladden, L.F. and R.E. Goldstein (2009) Measurement of cytoplasmic streaming in Chara corallina by magnetic resonance velocimetry. arXiv:0904.2707v1 [physics.bio-ph]</ref>).
 <h2>Future Research</h2>

← Older revision		Revision as of 15:21, 15 November 2013
Line 219:		Line 219:


−	<p>The scope of research that has explored the electrophysiology of Characean algae is immense. One important research theme was the nature of electrogenicity; that is, the cause of the highly negative inside potential of the internodal cell. The central role of an ATP-utilizing H+ pump was proposed from research using Characean algae (Kitasato, 1968<ref>Kitasato, H. (1968) ''The influence of H+ on the membrane potential and ion fluxes of Nitella''. [http://jgp.rupress.org/content/52/1/60.abstract Journal of General Physiology. '''52''':60–87]. </ref>; Spanswick, 1972<ref>Spanswick, R.M. (1972) ''Evidence for an electrogenic ion pump in Nitella translucens. I. The effects of pH, K+, Na+, light and temperature on the membrane potential and resistance''. [http://www.sciencedirect.com/science/~~journal~~/~~00052736~~/~~288/1~~ Biochimica et Biophysica Acta '''288''':73–89].</ref>), and extended to fungi and higher plants. The electrogenic H+ pump plays a role as central as that of the very similar Na+ K+ pump of animal cells. It is important for Biophysics students to be aware of the concept: Choose the right organism for a particular biological problem. In the case of the Characean algae, their large size made it possible to address the biological question of electrogenicity very directly. That is, the experimentalist could cut open the cell, remove the central vacuole, and then fill the cell with any desired solution. From such internal perfusion experiments, the ATP-dependence of electrogenicity was demonstrated directly (Shimmen and Tazawa, 1977<ref>Shimmen, T. and M. Tazawa (1977) ''Control of membrane potential and excitability of Chara cells with ATP and Mg2+''.[http://link.springer.com/article/10.1007/BF01940931 Journal of Membrane Biology '''37''':167–192].</ref>). An example of a perfusion setup is shown in Figure 2.4.</p>	+	<p>The scope of research that has explored the electrophysiology of Characean algae is immense. One important research theme was the nature of electrogenicity; that is, the cause of the highly negative inside potential of the internodal cell. The central role of an ATP-utilizing H+ pump was proposed from research using Characean algae (Kitasato, 1968<ref>Kitasato, H. (1968) ''The influence of H+ on the membrane potential and ion fluxes of Nitella''. [http://jgp.rupress.org/content/52/1/60.abstract Journal of General Physiology. '''52''':60–87]. </ref>; Spanswick, 1972<ref>Spanswick, R.M. (1972) ''Evidence for an electrogenic ion pump in Nitella translucens. I. The effects of pH, K+, Na+, light and temperature on the membrane potential and resistance''. [http://www.sciencedirect.com/science/article/pii/0005273672902246 Biochimica et Biophysica Acta '''288''':73–89].</ref>), and extended to fungi and higher plants. The electrogenic H+ pump plays a role as central as that of the very similar Na+ K+ pump of animal cells. It is important for Biophysics students to be aware of the concept: Choose the right organism for a particular biological problem. In the case of the Characean algae, their large size made it possible to address the biological question of electrogenicity very directly. That is, the experimentalist could cut open the cell, remove the central vacuole, and then fill the cell with any desired solution. From such internal perfusion experiments, the ATP-dependence of electrogenicity was demonstrated directly (Shimmen and Tazawa, 1977<ref>Shimmen, T. and M. Tazawa (1977) ''Control of membrane potential and excitability of Chara cells with ATP and Mg2+''.[http://link.springer.com/article/10.1007/BF01940931 Journal of Membrane Biology '''37''':167–192].</ref>). An example of a perfusion setup is shown in Figure 2.4.</p>

← Older revision		Revision as of 15:19, 15 November 2013
Line 219:		Line 219:


−	<p>The scope of research that has explored the electrophysiology of Characean algae is immense. One important research theme was the nature of electrogenicity; that is, the cause of the highly negative inside potential of the internodal cell. The central role of an ATP-utilizing H+ pump was proposed from research using Characean algae (Kitasato, 1968<ref>Kitasato, H. (1968) ''The influence of H+ on the membrane potential and ion fluxes of Nitella''. [http://jgp.rupress.org/content/52/1.~~toc~~ Journal of General Physiology. '''52''':60–87]. </ref>; Spanswick, 1972<ref>Spanswick, R.M. (1972) ''Evidence for an electrogenic ion pump in Nitella translucens. I. The effects of pH, K+, Na+, light and temperature on the membrane potential and resistance''. [http://www.sciencedirect.com/science/journal/00052736/288/1 Biochimica et Biophysica Acta '''288''':73–89].</ref>), and extended to fungi and higher plants. The electrogenic H+ pump plays a role as central as that of the very similar Na+ K+ pump of animal cells. It is important for Biophysics students to be aware of the concept: Choose the right organism for a particular biological problem. In the case of the Characean algae, their large size made it possible to address the biological question of electrogenicity very directly. That is, the experimentalist could cut open the cell, remove the central vacuole, and then fill the cell with any desired solution. From such internal perfusion experiments, the ATP-dependence of electrogenicity was demonstrated directly (Shimmen and Tazawa, 1977<ref>Shimmen, T. and M. Tazawa (1977) ''Control of membrane potential and excitability of Chara cells with ATP and Mg2+''.[http://link.springer.com/article/10.1007/BF01940931 Journal of Membrane Biology '''37''':167–192].</ref>). An example of a perfusion setup is shown in Figure 2.4.</p>	+	<p>The scope of research that has explored the electrophysiology of Characean algae is immense. One important research theme was the nature of electrogenicity; that is, the cause of the highly negative inside potential of the internodal cell. The central role of an ATP-utilizing H+ pump was proposed from research using Characean algae (Kitasato, 1968<ref>Kitasato, H. (1968) ''The influence of H+ on the membrane potential and ion fluxes of Nitella''. [http://jgp.rupress.org/content/52/1/60.abstract Journal of General Physiology. '''52''':60–87]. </ref>; Spanswick, 1972<ref>Spanswick, R.M. (1972) ''Evidence for an electrogenic ion pump in Nitella translucens. I. The effects of pH, K+, Na+, light and temperature on the membrane potential and resistance''. [http://www.sciencedirect.com/science/journal/00052736/288/1 Biochimica et Biophysica Acta '''288''':73–89].</ref>), and extended to fungi and higher plants. The electrogenic H+ pump plays a role as central as that of the very similar Na+ K+ pump of animal cells. It is important for Biophysics students to be aware of the concept: Choose the right organism for a particular biological problem. In the case of the Characean algae, their large size made it possible to address the biological question of electrogenicity very directly. That is, the experimentalist could cut open the cell, remove the central vacuole, and then fill the cell with any desired solution. From such internal perfusion experiments, the ATP-dependence of electrogenicity was demonstrated directly (Shimmen and Tazawa, 1977<ref>Shimmen, T. and M. Tazawa (1977) ''Control of membrane potential and excitability of Chara cells with ATP and Mg2+''.[http://link.springer.com/article/10.1007/BF01940931 Journal of Membrane Biology '''37''':167–192].</ref>). An example of a perfusion setup is shown in Figure 2.4.</p>