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134 results on '"S. Svetina"'

2. Multi-wavelength Ultrafast Ptychography: A Flexible Beamline with a Compact High Harmonic Source

Author

Charles S. Bevis, Carmelo Grova, Daniel A. Adams, Cristian S. Svetina, and Giulia F. Mancini

Abstract

We report the design of a flexible beamline for ultrafast multiwavelength ptychography to image nano-to-mesoscale heterogeneity in nanostructures and interfaces, with quantitative amplitude and phase contrast, sub-50nm spatial and sub-50fs temporal resolutions.

Published
2022
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3. Consistency criterion for ferroelectric free energy cluster expansion

Author

Robert Blinc, S. Svetina, and B. Žekš

Subjects
symbols.namesake, Chemistry, Consistency criterion, symbols, Thermodynamics, Statistical physics, Physical and Theoretical Chemistry, Condensed Matter Physics, Hamiltonian (quantum mechanics), Ferroelectricity, Atomic and Molecular Physics, and Optics, Cluster expansion
Abstract

The necessary condition that the cluster expansion as developed to determine the approximate free energy of hydrogen-bonded ferroelectrics [1] is thermodynamically consistent, is discussed, and the convergence of the series tested for the case of the KD2PO4 model Hamiltonian.

Published
2009
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4. Flat and sigmoidally curved contact zones in vesicle–vesicle adhesion

Author

Primož Ziherl and S. Svetina

Subjects
Rouleaux, Erythrocytes, Multidisciplinary, Chemistry, Vesicle, Cell Membrane, Adhesiveness, Biological Sciences, Models, Biological, Elasticity, Cell membrane, Crystallography, medicine.anatomical_structure, Microscopy, Electron, Transmission, Evagination, Cell Adhesion, medicine, Biophysics, Contact zone, Computer Simulation, Lipid vesicle, Cell adhesion
Abstract

Using the membrane-bending elasticity theory and a simple effective model of adhesion, we study the morphology of lipid vesicle doublets. In the weak adhesion regime, we find flat-contact axisymmetric doublets, whereas at large adhesion strengths, the vesicle aggregates are nonaxisymmetric and characterized by a sigmoidally curved, S-shaped contact zone with a single invagination and a complementary evagination on each vesicle. The sigmoid-contact doublets agree very well with the experimentally observed shapes of erythrocyte aggregates. Our results show that in identical vesicles with large to moderate surface-to-volume ratio, the sigmoid-contact shape is the only bound morphology. We also discuss the role of sigmoid contacts in the formation of multicellular aggregates such as erythrocyte rouleaux.

Published
2007
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5. Nonaxisymmetric phospholipid vesicles: Rackets, boomerangs, and starfish

Author

Primož Ziherl and S. Svetina

Subjects
Physics, Phospholipid vesicles, biology, business.industry, Starfish, General Physics and Astronomy, Mechanics, Bending, Parameter space, biology.organism_classification, Optics, Critical point (thermodynamics), Elasticity (economics), business, Phase diagram
Abstract

Within the area difference elasticity model, we numerically minimize the bending energy of phospholipid vesicles to study the nonaxisymmetric shapes at the oblate-prolate transition. We analyze the onset of a coherent structural hierarchy of hybrid shapes such as rackets, boomerangs, and starfish, which all consist of a flattened body and one or more elongated arms. The phase diagram of these shapes is characterized by a critical point terminating the line of discontinuous transitions between rackets and boomerangs/starfish. The critical point is located very close to the discocyte with the volume of a human erythrocyte, implying that in this part of the parameter space minute variations of volume and area difference can induce large changes of shape.

Published
2005
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7. Contributory presentations/posters

Author

N. Manoj, V. R. Srinivas, A. Surolia, M. Vijayan, K. Suguna, R. Ravishankar, R. Schwarzenbacher, K. Zeth, null Diederichs, G. M. Kostner, A. Gries, P. Laggner, R. Prassl, null Madhusudan, Pearl Akamine, Nguyen-huu Xuong, Susan S. Taylor, M. Bidva Sagar, K. Saikrishnan, S. Roy, K. Purnapatre, P. Handa, U. Varshney, B. K. Biswal, N. Sukumar, J. K. Mohana Rao, A. Johnson, Vasantha Pattabhi, S. Sri Krishna, Mira Sastri, H. S. Savithri, M. R. N. Murthy, Bindu Pillai, null Kannan, M. V. Hosur, Mukesh Kumar, Swati Patwardhan, K. K. Kannan, B. Padmanabhaa, S. Sasaki-Sugio, M. Nukaga, T. Matsuzaki, S. Karthikevan, S. Sharma, A. K. Sharma, M. Paramasivam, P. Kumar, J. A. Khan, S. Yadav, A. Srinivasan, T. P. Singh, S. Gourinath, Neelima Alam, A. Srintvasan, Vikas Chandra, Punit Kaur, Ch. Betzel, S. Ghosh, A. K. Bera, S. Bhattacharya, S. Chakraborty, A. K. Pal, B. P. Mukhopadhyay, I. Dey, U. Haldar, Asok Baneriee, Jozef Sevcik, Adriana Solovicova, K. Sekar, M. Sundaralingam, N. Genov, Dong-cai Liang, Tao Jiang, Ji-ping Zhang, Wen-rui Chang, Wolfgang Jahnke, Marcel Blommers, S. C. Panchal, R. V. Hosur, Bindu Pillay, Puniti Mathur, S. Srivatsun, Ratan Mani Joshi, N. R. Jaganathan, V. S. Chauhan, H. S. Atreya, S. C. Sahu, K. V. R. Chary, Girjesh Govil, Elisabeth Adjadj, Éric Quinjou, Nadia Izadi-Pruneyre, Yves Blouquit, Joël Mispelter, Bernadette Heyd, Guilhem Lerat, Philippe Milnard, Michel Desmadreil, Y. Lin, B. D. Nageswara Rao, Vidva Raghunathan, Mei H. Chau, Prashant Pesais, Sudha Srivastava, Evans Coutinho, Anil Saran, Leizl F. Sapico, Jayson Gesme, Herbert Lijima, Raymond Paxton, Thamarapu Srikrishnan, C. R. Grace, G. Nagenagowda, A. M. Lynn, Sudha M. Cowsik, Sarata C. Sahu, S. Chauhan, A. Bhattacharya, G. Govil, Anil Kumar, Maurizio Pellecchia, Erik R. P. Zuiderweg, Keiichi Kawano, Tomoyasu Aizawa, Naoki Fujitani, Yoichi Hayakawa, Atsushi Ohnishi, Tadayasu Ohkubo, Yasuhiro Kumaki, Kunio Hikichi, Katsutoshi Nitta, V. Rani Parvathy, R. M. Kini, Takumi Koshiba, Yoshihiro Kobashigawa, Min Yao, Makoto Demura, Astushi Nakagawa, Isao Tanaka, Kunihiro Kuwajima, Jens Linge, Seán O. Donoghue, Michael Nilges, G. Chakshusmathi, Girish S. Ratnaparkhi, P. K. Madhu, R. Varadarajan, C. Tetreau, M. Tourbez, D. Lavalette, M. Manno, P. L. San Biagio, V. Martorana, A. Emanuele, S. M. Vaiana, D. Bulone, M. B. Palma-Vittorelli, M. U. Palma, V. D. Trivedi, S. F. Cheng, W. J. Chien, S. H. Yang, S. Francis, D. K. Chang, Renn Batra, Michael A. Geeves, Dietmar J. Manstein, Joanna Trvlska, Pawel Grochowski, Maciej Geller, K. Ginalski, P. Grochowski, B. Lesyng, P. Lavalette, Y. Blouquit, D. Roccatano, A. Amadei, A. Di Nola, H. J. C. Berendsen, Bosco Ho, P. M. G. Curmi, H. Berry, D. Lairez, E. Pauthe, J. Pelta, V. Kothekar, Shakti Sahi, M. Srinivasan, Anil K. Singh, Kartha S. Madhusudnan, Fateh S. Nandel, Harpreet Kaur, Balwinder Singh, D. V. S. Jain, K. Anton Feenstra, Herman J. C. Berendsen, F. Tama, Y. -H. Sanejouand, N. Go, Deepak Sharma, Sunita Sharma, Santosh Pasha, Samir K. Brahmachari, R. Viiavaraghavan, Jyoti Makker, Sharmisllia Dey, S. Kumar, G. S. Lakshmikanth, G. Krishnamoorthy, V. M. Mazhul, E. M. Zaitseva, Borys Kierdaszuk, J. Widengren, B. Terry, Ü. Mets, R. Rigler, R. Swaminathan, S. Thamotharan, N. Yathindra, Y. Shibata, H. Chosrowjan, N. Mataga, I. Morisima, Tania Chakraharty, Ming Xiao, Roger Cooke, Paul Selvin, C. Branca, A. Faraone, S. Magazù, G. Maisano, P. Migliardo, V. Villari, Digambar V. Behere, M. Sharique Zahida Waheed Deva, M. Brunori, F. Cutruzzolà, Q. H. Gibson, C. Savino, C. Travaglini-Allocatelli, B. Vallone, Swati Prasad, Shyamalava Mazumdar, Samaresh Mitra, P. Soto, R. Fayad, I. E. Sukovataya, N. A. Tyulkova, Sh. V. Mamedov, B. Aktas, M. Canturk, B. Aksakal, R. Yilgin, K. I. Bogutska, N. S. Miroshnichenko, S. Chacko, M. DiSanto, J. A. Hypolite, Y-M. Zheng, A. J. Wein, M. Wojciechowski, T. Grycuk, J. Antosiewicz, Marc A. Ceruso, Alfredo Di Nola, Subhasis Bandvopadhvay, Bishnu P. Chatterjee, Devapriva Choudhury, Andrew Thompson, Vivian Stojanoff, Jerome Pinkner, Scott Hultgren, Stefan Khight, Delphine Flatters, Julia Goodfellow, Fumi Takazawatt, Minoru Kanehisa, Masaki Sasai, Hironori Nakamura, Wang Bao Han, Yuan Zheng, Wang Zhi Xin, Pan xin Min, Vlnod Bhakuni, Sangeeta Kulkarni, Atta Ahmad, Koodathingal Prakash, Shashi Prajapati, Alexey Surin, Tomoharu Matsumoto, Li Yang, Yuki Nakagawa, Kazumoto Kimura, Yoshiyuki Amemiya, Gennady V. Semisotnov, Hiroshi Kihara, Saad Tayyab, Salman Muzammil, Yogesh Kumar, Vinod Bhakuni, Monica Sundd, Suman Kundu, M. V. Jagannadham, Medicherla V. Jagannadham, Bina Chandani, Ruby Dhar, Lalankumar Sinha, Deepti Warrier, Sonam Mehrotra, Purnima Khandelwal, Subhendu Seth, Y. U. Sasidhar, C. Ratna Prabha, Arun Gidwani, K. P. Madhusudan, Akira R. Kinjo, Ken Nishikawa, Suvobrata Chakravarty, Raghavan Varadarajan, K. Noyelle, P. Haezebrouck, M. Joniau, H. Van Dael, Sheffali Dash, Indra Brata Jha, Rajiv Bhat, Prasanna Mohanty, A. K. Bandyopadhyay, H. M. Sonawat, Ch. Mohan Rao, Siddhartha Datta, K. Rajaraman, B. Raman, T. Ramakrishna, A. Pande, J. Pande, S. Betts, N. Asherie, O. Ogun, J. King, G. Benedek, I. V. Sokolova, G. S. Kalacheva, Masashi Sonoyama, Yasunori Yokoyama, Kunihiro Taira, Shigeki Mitaku, Chicko Nakazawal, Takanori Sasakil, Yuri Mukai, Naoki Kamo, Seema Dalal, Lynne Regan, Shigeki Mituku, Mihir Roychoudhury, Devesh Kumar, Dénes Lőrinczv, Franciska Könczöl, László Farkas, Joseph Belagyi, Christoph Schick, Christy A. Thomson, Vettai S. Ananthanarayanan, E. G. Alirzayeva, S. N. Baba-Zade, M. Michael Gromiha, M. Oobatake, H. Kono, J. An, H. Uedaira, A. Sarai, Kazufumi Takano, Yuriko Yamagata, Katsuhide Yutani, Gouri S. Jas, Victor Muñoz, James Hofrichter, William A. Eaton, Jonathan Penoyar, Philip T. Lo Verde, J. Kardos, Á. Bódi, I. Venekei, P. Závodszky, L. Gráf, András Szilágyi, Péter Závodszky, R. D. Allan, J. Walshaw, D. N. Woolfson, Jun Funahashi, Savan Gupta, M. Mangoni, P. Roccatano, Gosu Ramachandraiah, Nagasuma R. Chandra, Barbara Ciani, Derek N. Woolfson, Usha B. Nair, Kanwal J. Kaur, Dinakar M. Salunke, Chittoor P. Swaminathan, Avadhesha Surolia, A. Pramanik, P. Jonasson, G. Kratz, O. T. Jansson, P. -Å. Nygren, S. Ståhl, K. Ekberg, B. -L. Johansson, S. Uhlén, M. Uhlén, H. Jörnvall, J. Wahren, Karin Welfle, Rolf Misselwitz, Wolfgang Höhne, Heinz Welfle, L. G. Mitskevich, N. V. Fedurkina, B. I. Kurganov, Gotam K. Jarori, Haripada Maity, J. Guharay, B. Sengupta, P. K. Sengupta, K. Sridevi, S. R. Kasturi, S. P. Gupta, Gunjan Agarwal, Suzanne Kwong, Robin W. Briehl, O. I. Ismailova, N, A. Tyulkova, C. Hariharan, D. Pines, E. Pines, M. Zamai, R. Cohen-Luria, A. Yayon, A. H. Parola, M. J. Padya, G. A. Spooner, D. N. Woolfeon, Panchan Bakshi, D. K. Bharadwaj, U. Sharma, N. Srivastava, R. Barthwal, N. R. Jagannathan, Keiko Matsuda, Takaaki Nishioka, Nobuhiro Go, T. Aita, S. Urata, Y. Husimi, Mainak Majumder, Nicola G. A. Abrescia, Lucy Malinina, Juan A. Subirana, Juan Aymami, Ramón Eritxa, Miquel Coll, B. J. Premraj, R. Thenmalarchelvi, P. Satheesh Kumar, N. Gautham, Lou -Sing Kan, null Ming-Hou, Shwu-Bin Lin, Tapas Sana, Kanal B. Roy, N. Bruant, D. Flatters, R. Lavery, D. Genest, Remo Rons, Heinz Sklenar, Richard Lavery, Sudip Kundu, Dhananjay Bhattacharyya, Debashree Bandyopadhyay, Ashoke Ranjan Thakur, Rabi Majumdar, F. Barceló, J. Portugal, Sunita Ramanathan, B. J. Rao, Mahua Gliosli, N. Vinay Kumar, Umesh Varshney, Shashank S. Pataskar, R. Sarojini, S. Selvasekarapandian, P. Kolandaivel, S. Sukumar, P. Kolmdaivel, Motilal Maiti, Anjana Sen, Suman Das, Elisa Del Terra, Chiara Suraci, Silvia Diviacco, Franco Quadrifoglio, Luigi Xodo, Arghya Ray, G. Karthikeyan, Kandala V. R. Chary, Basuthkar J. Rao, Anwer Mujeeb, Thomas L. James, N. Kasyanenko, E. E. F. Haya, A. Bogdanov, A. Zanina, M. R. Bugs, M. L. Cornélio, M. Ye. Tolstorukov, Nitish K. Sanval, S. N. Tiwari, Nitish K. Sanyal, Mihir Roy Choudhury, P. K. Patel, Neel S. Bhavesh, Anna Gabrielian, Stefan Wennmalm, Lars Edman, Rudolf Rigler, B. Constantinescu, L. Radu, I. Radulcscu, D. Gazdaru, Sebastian Wärmländer, Mikael Leijon, Setsuyuki Aoki, Takao Kondo, Masahiro Ishiura, V. A. Pashinskaya, M. V. Kosevich, V. S. Shelkovsky, Yu. P. Blagoy, Ji-hua Wang, R. Malathi, K. Chandrasekhar, E. R. Kandimalla, S. Agrawal, V. K. Rastogi, M. Alcolea Palafox, Chatar Singh, A. D. Beniaminov, S. A. Bondarenko, E. M. Zdobnov, E. E. Minyat, N. B. Ulyanov, V. I. Ivanov, J. S. Singh, Kailas D. Sonawane, Henri Grosjean, Ravindra Tewari, Uddhavesh B. Sonavane, Annie Morin, Elizabeth A. Doherty, Jennifer A. Doudna, H. Tochio, S. Sato, H. Matsuo, M. Shirakawa, Y. Kyogoku, B. Javaram, Surjit B. Dixit, Piyush Shukla, Parul Kalra, Achintya Das, Kevin McConnell, David L. Beveridge, W. H. Sawyer, R. Y. S. Chan, J. F. Eccelston, Yuling Yan, B. E. Davidson, Eimer Tuite, Bengt Norden, Peter Nielsen, Masayuki Takahashi, Anirban Ghosh, Manju Bansal, Frauke Christ, Hubert Thole, Wolfgang Wende, Alfred Pingoud, Vera Pingoud, Pratibha Mehta Luthra, Ramesh Chandra, Ranjan Sen, Rodney King, Robert Weisberg, Olaf F. A. Larsen, Jos Berends, Hans A. Heus, Cornelis W. Hilbers, Ivo H. M. van Stokkum, Bas Gobets, Rienk van Grondelle, Herbert van Amerongen, HE. Sngrvan, Yu. S. Babayan, N. V. Khudaverdian, M. Gromiha, F. Pichierri, M. Aida, P. Prabakaran, K. Sayano, Saulius Serva, Eglė Merkienė, Giedrius Vilkaitis, Elmar Weinhold, Saulius Klimašauskas, Eleonora Marsich, Antonella Bandiera, Giorgio Manzini, G. Potikyan, V. Arakelyan, Yu. Babayan, Alex Ninaber, Julia M. Goodfellow, Yoichiro Ito, Shigeru Ohta, Yuzuru Husimi, J. Usukura, H. Tagami, H. Aiba, Mougli Suarez, Elia Nunes, Deborah Keszenman, E. Carmen Candreva, Per Thyberg, Zeno Földes-Papp, Amita Joshi, Dinesh Singh, M. R. Rajeswari, null Ira, M. Pregetter, H. Amenitsch, J. Chapman, B. N. Pandev, K. P. Mishra, E. E. Pohl, J. Sun, I. I. Agapov, A. G. Tonevitsky, P. Pohl, S. M. Dennison, G. P. Gorbeako, T. S. Dynbko, N. Pappavee, A. K. Mishra, Prieto Manuel, Almeida Rodrigo, Loura Luis, L. Ya. Gendel, S. Przestalski, J. Kuczera, H. Kleszczyńska, T. Kral, E. A. Chernitsky, O. A. Senkovich, V. V. Rosin, Y. M. Allakhverdieva, G. C. Papageorgiou, R. A. Gasanov, Calin Apetrei, Tudor Savopol, Marius Balea, D. Cucu, D. Mihailescu, K. V. Ramanathan, Goran Bačić, Nicolas Sajot, Norbert Garnier, Serge Crouzy, Monique Genest, Z. S. Várkonyi, O. Zsiros, T. Farkas, Z. Combos, Sophie Cribier, I. F. Fraceto, S. Schreier, A. Spisni, F. de Paula, F. Sevšek, G. Gomišček, V. Arrigler, S. Svetina, B. Žekš, Fumimasa Nomura, Miki Nagata, Kingo Takiguchi, Hirokazu Hotani, Lata Panicker, P. S. Parvathanathan, A. Ishino, A. Saitoh, H. Hotani, K. Takiguchi, S. Afonin, A. Takahashi, Y. Nakato, T. Takizawa, Dipti Marathe, Kent Jørgensen, Satinder S. Rawat, R. Rukmini, Amitabha Chattopadhyay, M. Šentiurc, J. Štrancar, Z. Stolič, K. Filipin, S. Pečar, S. C. Biswas, Satyen Sana, Anunay Samanta, Koji Kinoshita, Masahito Yamazaki, Tetsuhiko Ohba, Tai Kiuchi, null Yoshitoshi, null Kamakura, Akira Goto, Takaaki Kumeta, Kazuo Ohki, I. P. Sugar, T. E. Thompson, K. K. Thompson, R. L. Biltonen, Y. Suezaki, H. Ichinose, M. Akivama, S. Matuoka, K. Tsuchihashi, S. Gasa, P. Mattjus, J. G. Molotkovsky, H. M. Pike, R. E. Brown, Ashish Arora, Jörg H. Kleinschmidt, Lukas K. Tamm, O. G. Luneva, K. E. Kruglyakova, V. A. Fedin, O. S. Kuptsoya, J. W. Borst, N. V. Visser, A. J. W. G. Visser, T. S. Dyubko, Toshihiko Ogihara, Kiyoshi Mishima, A. L. Shvaleva, N. Č. Radenović, P. M. Minić, M. G. Jeremić, Č. N. Radenović, T. F. Aripov, E. T. Tadjibaeva, O. N. Vagina, M. V. Zamaraeva, B. A. Salakhutdinov, A. Cole, M. Poppofl, C. Naylor, R. Titball, A. K. Basak, J. T. Eaton, C. E. Naylor, N. Justin, D. S. Moss, R. W. Titball, F. Nomura, M. Nagata, S. Ishjkawa, S. Takahashi, Kaoru Obuchi, Erich Staudegger, Manfred Kriechbaum, Robert I. Lehrer, Alan J. Waring, Karl Lohner, Susanne Gangl, Bernd Mayer, Gottfried Köhler, J. Shobini, Z. Guttenberg, B. Lortz, B. Hu, E. Sackmann, N. M. Kozlova, L. M. Lukyanenko, A. N. Antonovich, E. I. Slobozhanina, Andrey V. Krylov, Yuri N. Antonenko, Elena A. Kotova, Alexander A. Yaroslavov, Subhendu Ghosh, Amal K. Bera, Sudipto Das, Eva Urbánková, Masood Jelokhani-Niaraki, Karl Freeman, Petr Jezek, P. B. Usmanov, A. Ongarbaev, A. K. Tonkikh, Peter Pohl, Sapar M. Saparov, P. Harikumar, J. P. Reeves, S. Rao, S. K. Sikdar, A. S. Ghatpande, C. Corsso, A. C. Campos de Carvalho, W. A. Varanda, C. ElHamel, E. Dé, N. Saint, G. Molle, Anurae Varshney, M. K. Mathew, E. Loots, E. Y. Isacoff, Michiki Kasai, Naohiro Yamaguchi, Paramita Ghosh, Joseph Tigyi, Gabor Tigyi, Karoly Liliom, Ricardo Miledi, Maja R. Djurisic, Pavle R. Andjus, Indira H. Shrivastava, M. S. P. Sansom, C. Barrias, P. F. Oliveira, A. C. Mauricio, A. M. Rebelo da Costa, I. A. Lopes, S. V. Fedorovich, V. S. Chubanov, M. V. Sholukh, S. V. Konev, N. Fedirko, V. Manko, M. Klevets, N. Shvinka, B. S. Prabhananda, Mamata H. Kombrabail, S. Aravamudhan, Berenice Venegas-Cotero, Ivan Ortega Blake, Zhi-hong Zhang, Xiao-jian Hu, Han-qing Zhou, Wei-ying Cheng, Hang-fang Feng, L. O. Dubitsky, L. S. Vovkanvch, I. A. Zalyvsky, E. Savio-Galimberti, P. Bonazzola, J. E. Ponce-Homos, Mario Parisi, Claudia Capurro, Roxana Toriano, Laxma G. Ready, Larry R. Jones, David D. Thomas, B. A. Tashmukhamedov, B. T. Sagdullaev, D. Heitzmann, R. Warth, M. Bleich, R. Greger, K. T. G. Ferreira, H. G. Ferreira, Orna Zagoory, Essa Alfahel, Abraham H. Parola, Zvi Priel, H. Hama-Inaba, R. Wang, K. Choi, T. Nakajima, K. Haginoya, M. Mori, H. Ohyama, O. Yukawa, I. Hayata, Nanda B. Joshi, Sridhar K. Kannurpatti, Preeti G. Joshi, Mau Sinha, Xun Shen, Tianhui Hu, Ling Bei, Menno L. W. Knetsch, Nicole Schäfers, John Sandblom, Juris Galvanovskis, Roxana Pologea-Moraru, Eugenia Kovacs, Alexandra Dinu, S. H. Sanghvi, V. Jazbinšek, G. Thiel, W. Müller, G. Wübeller, Z. Tronteli, Leš Fajmut, Marko Marhl, Milan Brumen, I. D. Volotovski, S. G. Sokolovski, M. R. Knight, Alexei N. Vasil’ev, Alexander V. Chalyi, P. Sharma, P. J. Steinbach, M. Sharma, N. D. Amin, J. Barchir, R. W. Albers, H. C. Pant, M. Balasubramanyam, M. Condrescu, J. P. Gardner, Shamci Monajembashi, Gotz Pilarczyk, K. O. Greulich, F. M. El-Refaei, M. M. Talaat, A. I. El-Awadi, F. M. Ali, Ivan Tahradník, Jana Pavelková, Alexandra Zahradniková, Boris S. Zhorov, Vettai S. Ananthanaravanan, M. Ch. Michailov, E. Neu, W. Seidenbusch, E. Gornik, D. Martin, U. Welscher, D. G. Weiss, B. R. Pattnaik, A. Jellali, V. Forster, D. Hicks, J. Sahel, H. Dreyfus, S. Picaud, Hong-Wei Wang, Sen-fang Sui, Pradeep K. Luther, John Barry, Ed Morris, John Squire, C. Sivakama Sundari, D. Balasubramanian, K. Veluraia, T. Hema Thanka Christlet, M. Xavier Suresh, V. Laretta-Garde, Dubravka Krilov, Nataša Stojanović, Janko N. Herak, Ravi Jasuja, Maria Ivanova, Rossen Mirchev, Frank A. Ferrone, David Stopar, Ruud B. Spruijt, Cor J. A. M. Wolfs, Marcus A. Hemminga, G. Arcovito, M. De Spirito, Rajendra K. Agrawal, Amy B. Heagle, Pawel Penczek, Robert Grassucci, Joachim Frank, Manjuli R. Sharma, Loice H. Jeyakumar, Sidney Fleischer, Terence Wagenknecht, Carlo Knupp, Peter M. G. Munro, Eric Ezra, John M. Squire, Koji Ichihara, Hidefumi Kitazawa, Yusuke Iguchi, Tomohiko J. Itoh, Greta Pifat, Marina Kveder, Slavko Pečar, Milan Schara, Deepak Nair, Kavita Singh, Kanury V. S. Rao, Kanwaljeet Kaur, Deepti Jain, B. Sundaravadivel, Manisha Goel, D. M. Salunke, E. I. Kovalenko, G. N. Semenkova, S. N. Cherenkevich, T. Lakshmanan, D. Sriram, S. Srinivasan, D. Loganathan, T. S. Ramalingam, J. A. Lebrón, P. J. Bjorkman, A. K. Singh, T. N. Gayatri, Ernesto R. Caffarena, J. Raul Grigera, Paulo M. Bisch, V. Kiessling, P. Fromherz, K. N. Rao, S. M. Gaikwad, M. I. Khan, C. G. Suresh, P. Kaliannan, M. Elanthiraiyan, K. Chadha, J. Payne, J. L. Ambrus, M. P. N. Nair, Madhavan P. N. Nair, S. Mahajan, K. C. Chadha, R. Hewitt, S. A. Schwartz, J. Bourguignon, M. Faure, C. Cohen-Addad, M. Neuburger, R. Ober, L. Sieker, D. Macherel, R. Douce, D. S. Gurumurthy, S. Velmurugan, Z. Lobo, Ratna S. Phadke, Prashant Desai, I. M. Guseinova, S. Yu. Suleimanov, I. S. Zulfugarov, S. N. Novruzova, J. A. Aliev, M. A. Ismayilov, T. V. Savchenko, D. R. Alieva, Petr Ilík, Roman Kouřil, Hana Bartošková, Jan Nauš, Jvoti U. Gaikwad, Sarah Thomas, P. B. Vidyasagar, G. Garab, I. Simidjiev, S. Rajagopal, Zs. Várkonyi, S. Stoylova, Z. Cseh, E. Papp, L. Mustárdy, A. Holzenburg, R. Bruder, U. K. Genick, T. T. Woo, D. P. Millar, K. Gerwert, E. D. Getzoff, Tamás Jávorfí, Győző Garab, K. Razi Naqvi, Md. Kalimullah, Jyoti Gaikwad, Manoj Semwal, Roman Kouril, Petr Ilik, Man Naus, István Pomozi, Gábor Horváth, Rüdiger Wehner, Gary D. Bernard, Ana Damjanović, Thorsten Ritz, Klaus Schulten, Wang Jushuo, Shan Jixiu, Gong Yandao, Kuang Tingyun, Zhao Nanming, Arvi Freiberg, Kõu Timpmann, Rein Ruus, Neal W. Woodbury, E. V. Nemtseva, N. S. Kudryasheva, A. G. Sizykh, V. N. Shikhov, T. V. Nesterenko, A. A. Tikhomirov, Giorgio Forti, Giovanni Finazzi, Alberto Furia, Romina Paola Barbagallo, S. Iskenderova, R. Agalarov, R. Gasanov, Miyashita Osamu, G. O. Nobuhiro, R. K. Soni, M. Ramrakhiani, Hiromasa Yagi, Kacko Tozawa, Nobuaki Sekino, Tomoyuki Iwabuchi, Masasuke Yoshida, Hideo Akutsu, A. V. Avetisyan, A. D. Kaulen, V. P. Skulachev, B. A. Feniouk, Cécile Breyton, Werner Kühlbrandt, Maria Assarsson, Astrid Gräslund, G. Horváth, B. Libisch, Z. Gombos, N. V. Budagovskaya, N. Kudryasheva, Erisa Harada, Yuki Fukuoka, Tomoaki Ohmura, Arima Fukunishi, Gota Kawai, Kimitsuna Watanabe, Jure Derganc, Bojan Božič, Saša Svetina, Boštjan Žekš, J. F. Y. Hoh, Z. B. Li, G. H. Rossmanith, E. L. de Beer, B. W. Treijtel, P. L. T. M. Frederix, T. Blangè, S. Hénon, F. Galtet, V. Laurent, E. Planus, D. Isabey, L. S. Rath, P. K. Dash, M. K. Raval, C. Ramakrishnan, R. Balaram, Milan Randic, Subhash C. Basak, Marjan Vracko, Ashesh Nandy, Dragan Amic, Drago Beslo, Sonja Nikolic, Nenad Trinajstic, J. Walahaw, Marc F. J. Lensink, Boojala V. B. Reddy, Ilya N. Shindylov, Philip E. Bourne, M. C. Donnamaria, J. de Xammar Oro, J. R. Grigera, Monica Neagu, Adrian Neagu, Matej Praprotnik, Dušanka Janežič, Pekka Mark, Lennart Nilsson, L. La Fata, Laurent E. Dardenne, Araken S. Werneck, Marçal de O. Neto, N. Kannan, S. Vishveshwara, K. Veluraja, Gregory D. Grunwald, Alexandra T. Balaban, Kanika Basak, Brian D. Gute, Denise Mills, David Opitz, Krishnan Balasubramanian, G. I. Mihalas, Diana Lungeanu, G. Macovievici, Raluca Gruia, C. Cortez-Maghelly, B. Dalcin, E. P. Passos, S. Blesic, M. Ljubisavljevic, S. Milosevic, D. J. Stratimirovic, Nandita Bachhawat, Shekhar C. Mande, A. Nandy, Ayumu Saito, Koichi Nishigaki, Mohammed Naimuddin, Takatsugu Hirokawa, Mitsuo Ono, Hirotomo Takaesu, M. I. El Gohary, Abdalla S. Ahmed, A. M. Eissa, Hiroshi Nakashima, G. P. S. Raghava, N. Kurgalvuk, O. Goryn, Bernard S. Gerstman, E. V. Gritsenko, N. N. Remmel, O. M. Maznyak, V. A. Kratasyuk, E. N. Esimbekova, D. Tchitchkan, S. Koulchitsky, A. Tikhonov, A. German, Y. Pesotskaya, S. Pashkevich, S. Pletnev, V. Kulchitsky, Umamaheswar Duvvuri, Sridhar Charagundla, Rahim Rizi, John S. Leigh, Ravinder Reddy, Mahesh Kumar, O. Coshic, P. K. Julka, O. K. Rath, NR. Jagannathan, Karina Roxana Iliescu, Maria Sajin, Nicolcta Moisoi, Ileana Petcu, A. I. Kuzmenko, R. P. Morozova, I. A. Nikolenko, G. V. Donchenko, M. K. Rahman, M. M. Ahmed, Takehiro Watanabe, Y. Rubin, H. Gilboa, R. Sharony, R. Ammar, G. Uretzky, M. Khubchandani, H. N. Mallick, V. Mohan Kumar, Arijitt Borthakur, Erik M. Shapiro, M. Gulnaz Begum, Mahaveer N. Degaonkar, S. Govindasamy, Ivan Dimitrov, T. A. Kumosani, W. Bild, I. Stefanescu, G. Titescu, R. Iliescu, C. Lupusoru, V. Nastasa, I. Haulica, Gopal Khetawat, N. Faraday, M. Nealen, S. Noga, P. F. Bray, T. V. Ananieva, E. A. Lycholat, MV. Kosevich, S. G. Stepanyan, S. V. Antonyuk, R. Khachatryan, H. Arakelian, A. Kumar, S. Ayrapetyan, V. Mkheyan, S. Agadjanyan, A. Khachatryan, S. S. Rajan, V. Kabaleeswaran, Geetha Gopalakrishnan, T. R. Govindachari, Meera Ramrakhiani, Phillip Lowe, Andrew Badley, David C. Cullen, H. Hermel, W. Schmahl, H. Möhwald, Nirmalya Majumdar, Joydip Das, András Dér, Loránd Kelemen, László Oroszi, András Hámori, Jeremy J. Ramsden, Pál Ormos, D. Savitri, Chanchal K. Mitra, Toshio Yanagida, Seiji Esaki, Yuji Kimura, Tomoyuki Nishida, Yosiyuki Sowa, M. Radu, V. K. Koltover, Ya. I. Estrin, L. A. Kasumova, V. P. Bubnov, E. E. Laukhina, Rajiv Dotta, M. Degaonkar, P. Raghunathan, Rama Jayasundar, Pavel Novák, Milan Marko, Ivan Zahradník, Hiroaki Hirata, Hidetake Miyata, J. Balaji, P. Sengupta, S. Maiti, M. Gonsalves, A. L. Barker, J. V. Macpherson, D. O’Hare, C. P. Winlove, P. R. Unwin, R. Phillip, S. Banerjee, G. Ravindra Kumar, K. Nagayaka, R. Danev, S. Sugitani, K. Murata, Michael Gősch, H. Blom, P. Thyberg, Z. Földes-Papp, G. Björk, J. Holm, T. Heino, Masashi Yokochi, Fuyuhiko Inagaki, Masami Kusunoki, E. K. Matthews, J. Pines, Yu. P. Chukova, Vitaly K. Koltover, Geetanjali Bansal, Uma Singh, M. P. Bansal, Kotoko Nakata, Tastuya Nakano, Tsuguchika Kaminuma, B. P. S. Kang, U. Singh, Bonn Kirn, Neja Potocnik, Vito Stare, Latal Shukla, V. Natarajan, T. P. A. Devasagayam, M. D. Sastry, P. C. Kesavan, R. Sayfutdinov, V. V. Adamovich, D. Yu. Rogozin, A. G. Degermendzhy, C. L. Khetrapal, G. A. Nagana Gowda, Kedar Nath Ghimire, Ishida Masaru, H. Fujita, S. Ishiwata, Y. Kishimoto, S. Kawahara, M. Suzuki, H. Mori, M. Mishina, Y. Kirino, H. Ohshima, A. S. Dukhin, V. N. Shilov, P. J. Goetz, and R. K. Mishra

Subjects
0303 health sciences, biology, General Medicine, 010402 general chemistry, 01 natural sciences, Horseradish peroxidase, General Biochemistry, Genetics and Molecular Biology, 0104 chemical sciences, 03 medical and health sciences, Biochemistry, Manganese porphyrin, biology.protein, Enzyme reconstitution, General Agricultural and Biological Sciences, 030304 developmental biology
Published
1999
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8. Nonlocal membrane bending: a reflection, the facts and its relevance

Author

B. Žekš and S. Svetina

Subjects
Vesicle fusion, Surface Properties, Lipid Bilayers, Biophysics, Organelle Shape, Membrane Fusion, Models, Biological, Biophysical Phenomena, Quantitative Biology::Subcellular Processes, Membrane bending, Colloid and Surface Chemistry, Optics, Animals, Humans, Physical and Theoretical Chemistry, Elasticity (economics), Cell Shape, Physics, Physics::Biological Physics, business.industry, Vesicle, Cell Membrane, Surfaces and Interfaces, Intracellular Membranes, Elasticity, Membrane, Classical mechanics, Energy Transfer, Lipid vesicle, business, Algorithms
Abstract

About forty years ago it was realized that phospholipid membranes, because they are composed of two layers, exhibit particular, and specific mechanical properties [1–3]. This led to the concept of nonlocal membrane bending, often called area difference elasticity. We present a short history of the development of the concept, followed by arguments for a proper definition of the corresponding elastic constant. The effects of the nonlocal bending energy on vesicle shape are explained. It is demonstrated that lipid vesicles, cells and cellular aggregates exhibit phenomena that can only be described in a complete manner by considering nonlocal bending.

Published
2013

10. Membrane active compounds that affect the shape of cells and cellular organelles

Author

S, Svetina and B, Zeks

Subjects
Erythrocytes, Models, Statistical, Cell Membrane, Lipid Bilayers, Animals, Phospholipids
Abstract

Amphiphilic membrane active compounds are considered that affect the shapes of cells and cellular organelles by intercalation into the phospholipid part of their membranes. It is taken into consideration that amphiphile-membrane interaction modifies membrane mechanical properties. The relationship between membrane mechanical properties and vesicle shapes and the concept of the bilayer couple model are shortly reviewed. Then it is put forward that the strength of the amphiphile-membrane interaction may depend on the lateral packing of phospholipid molecules. It is shown that in such a case the amphiphile molecules bind to the membrane in a cooperative manner. Moreover, the amphiphile binding makes the ratio between the nonlocal and local membrane bending constants to be effectively larger and thus widens the range of possible stable vesicle and cellular shapes.

Published
2001

11. Mechanical and functional aspects of membrane skeletons

Author

S, Svetina, B, Bozic, J, Derganc, and B, Zeks

Subjects
Neutrophils, Cell Membrane, Lipid Bilayers, Cell Adhesion, Thermodynamics, Models, Biological, Cell Division, Cytoskeleton, Biomechanical Phenomena, Cell Size
Abstract

Membrane skeletons can be characterized as cytoskeletal structures lying parallel to the bilayer part of cellular and organelle membranes. Typical examples are spectrin network and actin-myosin cortex. We approach the problem of elucidating the function of membrane skeletons by theoretically analyzing mechanical models of the cellular behavior. Membranes of different physical and chemical properties are considered. In erythrocytes and some organelles membrane bilayers are smooth and simply underlaid or overlaid by membrane skeletons. It is argued that there the role of a membrane skeleton is, either, to keep the membrane composition laterally homogeneous as it is in the case of the erythrocyte, or, that it is involved in the processes of the lateral separation of integral membrane proteins as it is happening in the case of some intermediate steps of the vesicular membrane trafficking. In the second type of membranes the bilayer part is ruffled and folded, and there the membrane skeletons play a role in the determination of the cortical tension. Here we explore in more detail the mechanical behavior of a cell with such properties of its boundary. The shape transformations are described which occur under the influence (i) of different external forces, i.e., when an originally spherical cell is aspirated into the micropipette or when such a cell is adsorbed on a flat surface, and (ii) of different internal forces on the cell boundary exerted by the cytoskeletal elements.

Published
2001

12. Low pH induced shape changes and vesiculation of human erythrocytes

Author

M, Gros, S, Vrhovec, M, Brumen, S, Svetina, and B, Zeks

Subjects
Sodium Lactate, Sucrose, Erythrocytes, Erythrocyte Membrane, Microscopy, Electron, Scanning, Humans, Hydrogen-Ion Concentration, In Vitro Techniques, Sodium Chloride
Abstract

Shape changes and vesiculation were induced in intact human erythrocytes by gradually decreasing pH in the cell suspension. A sequence of different shapes preceding vesiculation was documented, i.e. discocytes, stomatocytes, and stomatoacantocytes. The final state was characterized by spherical mother cells and vesicles released. Low pH-induced vesiculation was also studied in the presence of stomatocytogenic or echinocytogenic compounds. The action of stomatocytogenic compounds was inhibitory, and echinocytogenic compounds had no effect on low pH-induced vesiculation. Vesiculation induced by low pH was studied also in isotonic solutions of different sucrose/salt composition. It was concluded that (i) low intracellular pH is responsible for cell shape transformations as well as for release of vesicles, (ii) at temperature 37 degrees C the intracellular pH value which induces the release of vesicles is 5.4, and (iii) the sequence of typical shape changes preceding vesiculation does not include echinocytes. The results are discussed on the basis of the layered membrane model of the shape formation and shape transformations of the human erythrocyte, and additionally considering the partial detachment of the membrane skeleton from the bilayer part of the membrane.

Published
1996

13. The Effect of the Electric Field on the Shapes of Phospholipid Vesicles

Author

B. Žekš and S. Svetina

Subjects
Physics::Biological Physics, Materials science, Vesicle, Bilayer, Phospholipid, Molecular physics, Ellipsoid, Quantitative Biology::Cell Behavior, Condensed Matter::Soft Condensed Matter, Quantitative Biology::Subcellular Processes, Membrane bending, chemistry.chemical_compound, Membrane, chemistry, Electric field, Elongation
Abstract

The shapes of phospholipid vesicles in an external electric field are evaluated using the bilayer couple model of the phospholipid membrane. Nearly spherical vesicles have for small fields a shape of prolate ellipsoids, which get more elongated with increasing electric field. For larger fields the elongation does not increase simply, but a bulge starts to grow on the equator. The shapes which minimize the membrane bending energy at given membrane area are calculated in dependence of the electric field and the corresponding volumes are determined.

Published
1992
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14. Phospholipid Membrane Local and Non-Local Bending Moduli Determined by Tether Formation from Aspirated Vesicles

Author

B. Božič, Jianben Song, B. Žekš, S. Svetina, and Richard E. Waugh

Subjects
Flexural modulus, Chemistry, Vesicle, Bilayer, technology, industry, and agriculture, Elastic energy, lipids (amino acids, peptides, and proteins), Bending, Composite material, Curvature, Neutral plane, Elastic modulus
Abstract

An elastic resistance of closed bilayer membrane to changes in curvature is treated in terms of local and non-local bending contributions to the membrane elastic energy. The method for the measurement of the corresponding elastic moduli by tether formation from giant phospholipid vesicles is described. The theoretical analysis of the method reveals the importance if the non-local bending for the stability of the tether formation. For the lipid l-stearoyl-2-oleoyl-phosphatidylcholine containing smaller amounts of l-palmitoyl-2-oleoyl-phosphatidylserine the mean value of the bending constant obtained is 1.2 × 10-19 J and an estimate for the mean value of the non-local bending modulus is 4 × 10-19 J.

Published
1992
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16. The Effect of Membrane Elasticity on Shapes of Nearly Spherical Phospholipid Vesicles

Author

S. Svetina, B. Žekš, and F. Sevšek

Subjects
Condensed Matter::Soft Condensed Matter, Quantitative Biology::Subcellular Processes, Physics::Biological Physics, Phospholipid vesicles, Materials science, Membrane, Orders of approximation, Vesicle, Spherical harmonics, lipids (amino acids, peptides, and proteins), Elasticity (economics), Molecular physics, Elasticity of cell membranes
Abstract

The equilibrium shapes of nearly spherical phospholipid vesicles were determined taking into account finite elasticity of the membrane and of the enclosed liquid. Using spherical harmonics expansion and the second order approximation, the equilibrium shape of a vesicle was found to be either spherical or quadrupolarly distorted, depending on the volume of the vesicle and the areas of the two leaflets of the membrane in the unstretched state.

Published
1992
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17. Mechanical behavior of closed lamellar membranes as a possible common mechanism for the establishment of developmental shapes

Author

S, Svetina and B, Zeks

Subjects
Embryology, Membranes, Cell Polarity, Models, Theoretical, Cell Division
Abstract

The mechanical behavior of a closed membrane composed of two layers in contact is described as it is obtained by finding the minimum of the membrane bending energy at constant membrane area, constant difference between the areas of the two layers, and constant enclosed volume. It is shown that the membrane bending energy is a discontinuous function of the volume (v) and difference between the layer areas (delta a) defined relative to the volume and area difference of a sphere with the same membrane area, respectively. However, for different classes of shapes it is possible to obtain regions in the v/delta a diagram within which the shapes change continuously with v and delta a. These regions are shown for the egg, dumbbell and cup shape classes, respectively. The results of the shape analysis are used in the discussion of cell polarity, cytokinesis and gastrulation. Cell polarity is related to the decrease in symmetry during the transition from the radially symmetrical spherical shape to the asymmetrical shapes of the egg class. It is proposed that symmetrical cytokinesis occurs within the dumbbell class and that asymmetrical cytokinesis occurs within the egg class. Gastrulation is described as shape transformations within the class of cup shapes.

Published
1991

18. Annexin A5 binding to giant phospholipid vesicles is differentially affected by anti-β2-glycoprotein I and anti-annexin A5 antibodies.

Author

J. Majhenc and S. Svetina

Subjects
*PHOSPHOLIPID antibodies, *THROMBOSIS, *PREGNANCY, *EPITOPES
Abstract

Objectives. Anti-phospholipid antibodies have been recognized to play a role in vascular thrombosis and pregnancy morbidity. They were first thought to be directed to phospholipids, but it is now known that the majority of pathogenic antibodies recognizes epitopes on phospholipid-binding plasma proteins such as β2-glycoprotein I (β2GPI) or possibly also annexin A5 (ANXA5). The mechanism of their prothrombotic action is still not completely understood. The aim of the present study was to observe the effect of antibodies against ANXA5 (aANXA5) and antibodies against β2GPI (aβ2GPI) on the binding of ANXA5 to the negatively charged phospholipid membrane.Methods. Giant phospholipid vesicles (GPVs) were used as a simple model of the membrane surface. GPVs composed of phosphatidylserine and phosphatidylcholine were produced in an aqueous medium. A single GPV was transferred to the solution containing ANXA5 conjugated with Alexa Fluor 488 (FANXA5) and (i) aANXA5 or aβ2GPI and (ii) different concentrations of aβ2GPI together with β2GPI. The emission of the fluorescent light from the GPV surface, as the result of FANXA5 binding, was measured.Results. β2GPI together with aβ2GPI reduced the binding of FANXA5 to GPVs. On the contrary, aANXA5 enhanced the binding of ANXA5 to the GPV surface.Conclusions. Our results point to the competition between FANXA5 and complexes of β2GPI–aβ2GPI for the same binding sites and therefore support the hypothesis of the disruption of the ANXA5 protective shield on procoagulant phospholipid surface. The influence of increased cell surface ANXA5 concentration in the presence of aANXA5 on coagulation needs to be further studied. [ABSTRACT FROM AUTHOR]

Published
2007

19. Mathematical model of blood chemistry and local blood flow regulation

Author

S. Svetina and V. Smolej

Subjects
Statistics and Probability, Chemistry, Partial Pressure, Applied Mathematics, General Medicine, Blood flow, Carbon Dioxide, Hydrogen-Ion Concentration, Models, Biological, General Biochemistry, Genetics and Molecular Biology, Oxygen, Hemoglobins, Blood, Blood chemistry, Regional Blood Flow, Modeling and Simulation, Animals, Humans, Blood Flow Velocity, Biomedical engineering
Published
1975
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20. Consideration of the spontaneous polarization of water at the solid/liquid interface

Author

S. Svetina, A. Luzar, and B. Z̆eks̆

Subjects
Steric effects, Surface (mathematics), Crystallography, Chemistry, Hydrogen bond, Chemical physics, Orientation (geometry), General Physics and Astronomy, Molecule, Electrolyte, Physical and Theoretical Chemistry, Polarization (electrochemistry), Solid liquid
Abstract

The orientation of water molecules close to a hard wall is studied. A simple model of water near interfaces is proposed in which only the hydrogen bond interactions among molecules and steric restrictions imposed by the wall are taken into account. The average number of hydrogen bonds per molecule is determined as a function of the distance from the interface. It is shown that a water molecule exhibits a preferred orientation at the surface because of its asymmetric character. Angular distribution of water molecules at the interface is studied by considering the effect of steric restrictions and orientational dependence on hydrogen bond probability. The magnitude of the resulting average polarization is estimated. The corresponding surface electrostatic potential is evaluated.

Published
1985
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21. Osmotic states of the red blood cell

Author

S. Svetina, M. Brumen, and Roland Glaser

Subjects
Lysis, Chromatography, Osmotic concentration, Chemistry, medicine, Osmotic pressure, Tonicity, Thermodynamics, Electrolyte, Semipermeable membrane, Osmosis, Chloride, medicine.drug
Abstract

Summary o 1. Permeative properties of the red blood cell membrane are utilized for an introduction of three osmotic states of the model cell with respect to equilibration of certain cell solution constituents across the membrane: equilibration of water (W state), equilibration of water and chloride (C state), and equilibration of water, chloride and cations (D state). 2. The model cell introduced consists of the semipermeable membranewhich separates the buffered external solution composed of water, univalent electrolyte, and sucrose from the internal hemoglobin and electrolyte solution. Three sets of equations each describing corresponding osmotic state are given. Certain physicochemical properties of the hemoglobin solution are taken into account. The inner pH is assumed to be established according to the chloride distribution across the membrane. 3. The volume and electric potential difference of the model cellare calculated for each osmotic state at different ratios of sucrose and electrolyte concentration of external solutions. Results are used for an analysis of general osmotic properties and lysis of red cells. 4. It is shown how cells are expected to behave if exposed to conditions with different osmotic pressure, composition of external solutions, or temperature. The importance of temperature effect and rate of performing osmotic experiments on the existence of the W state is pointed out. 5. Different experimental procedures which cause an increase inthe membrane cation premeability are discussed in terms of the transition from the C to D state. It is indicated that after the membrane modification in the cases discussed osmotic accomodation of cells is governed by the net-chloride diffusion.

Published
1979
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24. Bilayer couple hypothesis of red cell shape transformations and osmotic hemolysis

Author

S, Svetina and B, Zeks

Subjects
Erythrocyte Membrane, Lipid Bilayers, Osmolar Concentration, Humans, Hemolysis
Abstract

It is shown how according to the bilayer couple hypothesis the cell volume and cell shape at hemolysis depend on the difference between areas of the two leaflets of the membrane bilayer. The result is used to interpret the time course of the hemolytic process.

Published
1983

25. Mathematical Model of Respiratory Gas Exchange at Stationary Conditions

Author

S. Svetina and A. Grad

Subjects
Respiratory quotient, chemistry.chemical_compound, Mathematical model, Chemistry, Carbon dioxide, Circulatory system, Breathing, chemistry.chemical_element, Blood flow, Mechanics, Respiratory system, Oxygen
Abstract

Exchange of respiratory gases in an organism is a corporate process in which the ventilatory, circulatory and metabolic functions are involved (Wasserman et al, 1967). The properties of the respiratory gases exchange system are determined by a number of regulatory mechanisms and the oxygen and carbon dioxide carrying properties of the blood. The system is multivariant with many inputs and outputs therefore the mathematical models can be considered as an important tool in understanding its behaviour. In this communication a simple mathematical model is introduced for studying the respiratory gases exchange at stationary conditions, in which the ventilation is regulated by the arterial values of carbon dioxide and oxygen, and the blood flow is assumed to depend on the metabolic needs of the tissue. The input parameters are external pressures of oxygen and carbon dioxide, oxygen consumption rate in tissue and respiratory quotient. The outputs are arterial and venous concentrations of oxygen and carbon dioxide, arterial and venous pH, ventilation and blood flow.

Published
1978
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26. Biochemical and Biological Characteristics of Leucocyte Proteinase Inhibitors

Author

Gianni Sava, J. Skrk, Vito Turk, M. Drobnič-Košorok, Tullio Giraldi, J. Babnik, S. Svetina, M. Kopitar, R. A. Clark, U. Batista, M. Korbelik, and J. Brzin

Subjects
chemistry.chemical_classification, Neutral proteinase, Protease, Physiological significance, medicine.medical_treatment, Endogeny, Biology, Enzyme, chemistry, Biochemistry, Thiol, medicine, Substrate specificity, Polyacrylamide gel electrophoresis
Abstract

In last decade there has been an intensifying interest in naturally occurring protease inhibitors. Inhibitors which are present in the same cells as the enzymes they inhibit are of great physiological significance. A vast amount of literature1 reports that leucocytes are cells which contain different types of proteinases: neutral, thiol and acid ones. Only for the latter group of enzymes has the endogenous inhibitor not yet been determined, whereas for all other types the specific endogenous inhibitors have already been detected. Many groups of invest a ors have studied the isolation2–6, molecular characterization7–9 and mode of inhibition of these proteins10.

Published
1982
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28. Electrical Double Layer and Phospholipid Membranes. Aspects of Interface Water Structure

Author

S. Svetina and B. Žekš

Subjects
Quantitative Biology::Subcellular Processes, Physics::Biological Physics, Physics::Atmospheric and Oceanic Physics, Quantitative Biology::Cell Behavior
Abstract

It is inferred that the formation of an electrical double layer in phospholipid membranes is affected by the modified water. structure at the membrane/water interface. Theoretical evidence is presented indicating a decrease in the number density of water hydrogen bonds and the appearance of a layer of spontaneously polarized water at the solid/water interface which are the consequence of the orientational properties of the water structure and the asymmetric structure of the water molecule respectively. Consequences of such modifications of water structure are discussed on the basis of simple models regarding ion distribution at the interface, effect on the phospholipid chain melting phase transition temperature and the membrane-membrane interaction.

Published
1987

32. Ionic states and metabolism of erythrocytes

Author

R, Glaser, H, Heinrich, M, Brumen, and S, Svetina

Subjects
Ions, Electrolytes, Erythrocytes, Erythrocyte Membrane, Humans, Hydrogen-Ion Concentration, Energy Metabolism, Glycolysis
Published
1983

33. Relations among variations in human red cell volume, density, membrane area, hemoglobin content and cation content

Author

S. Svetina

Subjects
Statistics and Probability, Erythrocytes, General Immunology and Microbiology, Red Cell, Chemistry, Applied Mathematics, Cell, Erythrocyte Membrane, Analytical chemistry, General Medicine, Red cell volume, Models, Biological, General Biochemistry, Genetics and Molecular Biology, Red blood cell, Hemoglobins, Membrane, medicine.anatomical_structure, Modeling and Simulation, Content (measure theory), Cell density, medicine, Humans, Hemoglobin, General Agricultural and Biological Sciences, Mathematics
Abstract

It is shown how variations in different properties of red cells can be inter-related provided relations exist among these properties at the single cell level. On the basis of the cell density dependence on cell volume and hemoglobin content, and the assumed volume dependence on red cell cation and hemoglobin content, nine relations among the variations in red cell volume, density, membrane area, hemoglobin content and cation content, and their correlations are derived. Values of seven correlation coefficients are theoretically predicted and are shown to be consistent with the experiments performed by density fractionated red blood cells. The cell volume dependence on cation and hemoglobin content obtained from relations among variations is compared with the predictions obtained by the existing model about the osmotic behavior of the red blood cell. Furthermore, it is shown that data on the variations of the red cell properties indicate the existence of the relation among cation content, hemoglobin content, and membrane area at the level of a single cell.

Published
1982

34. A model of the pH-dependence of the number of oxygen-linked chloride binding sites in hemoglobin

Author

M, Brumen, V, Gal, and S, Svetina

Subjects
Hemoglobins, Kinetics, Magnetic Resonance Spectroscopy, Chlorides, Oxyhemoglobins, Humans, Hydrogen-Ion Concentration, Mathematics, Protein Binding
Abstract

A model is presented of the pH-dependence of the number of oxygen-linked chloride binding sites established by nuclear magnetic resonance quadrupole-relaxation studies on various mutant and chemically modified hemoglobins. The predictions of the model are in good qualitative agreement with the measured pH-dependences of the linewidth of the 35Cl- NMR signal. The obtained agreement implies that more chloride is bound to oxygenated than to deoxygenated hemoglobin.

Published
1978

36. Biochemical and biological characteristics of leucocyte proteinase inhibitors

Author

Kopitar M, Drobnic-Kosorok M, Babnik J, Brzin J, Turk V, Korbelik M, Batista U, Svetina S, Skrk J, Giraldi T, Gianni Sava, M., Kopitar, M., Drobnic Kosorok, J., Babnik, J., Brzin, V., Turk, M., Korbelik, U., Batista, S., Svetina, J., Skrk, Giraldi, Tullio, and Sava, Gianni

Subjects
Electrophoresis, Polyacrylamide Gel, Animal, Protease Inhibitor, Leukocyte, Substrate Specificity, Subcellular Fraction, Electrophoresi, Leukocytes, Animals, Humans, Electrophoresis, Polyacrylamide Gel, Protease Inhibitors, Subcellular Fractions, Human
Abstract

Pig leucocytes contain inhibitors of neutral and thiol proteinases. These proteins could be isolated from post-granule supernatant fraction as well as from nuclear extract using ion exchange chromatography, gel chromatography and affinity chromatography. Inhibitors differ in molecular weight, isoelectric point, immunologically and their inhibition ability against tested enzymes.

37. Membrane Localization of Piezo1 in the Context of Its Role in the Regulation of Red Blood Cell Volume.

Author

Božič B and Svetina S

Abstract

Piezo1 is a membrane nonspecific cation channel involved in red blood cells (RBCs) in the regulation of their volume. Recently, it was shown that it is distributed on the RBC membrane in a nonuniform manner. Here it is shown that it is possible to interpret the lateral distribution of Piezo1 molecules on RBC membrane by the curvature dependent Piezo1-bilayer interaction which is the consequence of the mismatch between the intrinsic principal curvatures of the Piezo1 trimer and the principal curvatures of the membrane at Piezo1's location but without its presence. This result supports the previously proposed model for the role of Piezo1 in the regulation of RBC volume., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Božič and Svetina.)

Published
2022
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38. Theoretical Bases for the Role of Red Blood Cell Shape in the Regulation of Its Volume.

Author

Svetina S

Abstract

The red blood cell (RBC) membrane contains a mechanosensitive cation channel Piezo1 that is involved in RBC volume homeostasis. In a recent model of the mechanism of its action it was proposed that Piezo1 cation permeability responds to changes of the RBC shape. The aim here is to review in a descriptive manner different previous studies of RBC behavior that formed the basis for this proposal. These studies include the interpretation of RBC and vesicle shapes based on the minimization of membrane bending energy, the analyses of various consequences of compositional and structural features of RBC membrane, in particular of its membrane skeleton and its integral membrane proteins, and the modeling of the establishment of RBC volume. The proposed model of Piezo1 action is critically evaluated, and a perspective presented for solving some remaining experimental and theoretical problems. Part of the discussion is devoted to the usefulness of theoretical modeling in studies of the behavior of cell systems in general., (Copyright © 2020 Svetina.)

Published
2020
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39. A Model of Piezo1-Based Regulation of Red Blood Cell Volume.

Author

Svetina S, Švelc Kebe T, and Božič B

Subjects
Erythrocyte Deformability, Erythrocytes cytology, Humans, Models, Theoretical, Potassium metabolism, Cell Size, Erythrocytes metabolism, Ion Channels metabolism
Abstract

A red blood cell (RBC) performs its function of adequately carrying respiratory gases in blood by its volume being ∼60% of that of a sphere with the same membrane area. For this purpose, human and most other vertebrate RBCs regulate their content of potassium (K + ) and sodium (Na + ) ions. The focus considered here is on K + efflux through calcium-ion (Ca 2+ )-activated Gárdos channels. These channels open under conditions that allow Ca 2+ to enter RBCs through Piezo1 mechanosensitive cation-permeable channels. It is postulated that the fraction of open Piezo1 channels depends on the RBC shape as a result of the curvature-dependent Piezo1-bilayer membrane interaction. The consequences of this postulate are studied by introducing a simple model of RBC osmotic behavior supplemented by the dependence of RBC membrane K + permeability on the reduced volume (i.e., the ratio of cell volume to its maximal possible volume) of RBC discoid shapes. It is assumed that because of its intrinsic curvature and strong interaction with the surrounding membrane, Piezo1 tends to concentrate in the dimple regions of these shapes, and the fraction of open Piezo1 channels depends on the membrane curvature in that region. It is shown that the properties of the described model can provide the basis for the formation of the negative feedback loop that interrelates cell volume and its content of potassium ions. The model predicts the relation, valid for each cell in an RBC population, between RBC volume and membrane area, thus explaining the large value of the measured membrane area versus the volume correlation coefficient. The mechanism proposed here for RBC volume regulation is in accord with the loss of this correlation in RBCs of Piezo1 knockout mice., (Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Published
2019
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40. Investigating cell functioning by theoretical analysis of cell-to-cell variability.

Author

Svetina S

Subjects
Cell Proliferation, Erythrocytes cytology, Cells cytology, Models, Biological
Abstract

Here we discuss cell-to-cell variability in isogenic cell populations on the basis of an analogy between the processes of vesicle self-reproduction and cell self-replication. A short review of the theoretical analysis of vesicle self-reproduction is presented to indicate that this process only occurs under the fulfillment of specific criteria: causal relations between the values of vesicle variables involved in its growth and division, and the parameters of the environment. It is shown that when division is asymmetric, both vesicle birth size and interdivision times are variable. We argue that during cell self-replication, the balance between processes of cell growth and division also relies on causal relations between the corresponding cellular variables. A possible method is suggested to unravel previously unidentified causal relations between cell variables from the relationships between their variability parameters such as the widths of their probability distributions and their correlation coefficients. The method is outlined by reviewing the results of the corresponding analysis applied to a population of red blood cells. Some novel research directions are suggested that could lead from the analysis of cell-to-cell variability to a better understanding of the organizational structure of cells and possibly also their evolutionary origin.

Published
2017
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41. A novel strain energy relationship for red blood cell membrane skeleton based on spectrin stiffness and its application to micropipette deformation.

Author

Svetina S, Kokot G, Kebe TŠ, Žekš B, and Waugh RE

Subjects
Elasticity, Thermodynamics, Erythrocyte Deformability, Erythrocyte Membrane physiology, Spectrin metabolism
Abstract

Red blood cell (RBC) membrane skeleton is a closed two-dimensional elastic network of spectrin tetramers with nodes formed by short actin filaments. Its three-dimensional shape conforms to the shape of the bilayer, to which it is connected through vertical linkages to integral membrane proteins. Numerous methods have been devised over the years to predict the response of the RBC membrane to applied forces and determine the corresponding increase in the skeleton elastic energy arising either directly from continuum descriptions of its deformation, or seeking to relate the macroscopic behavior of the membrane to its molecular constituents. In the current work, we present a novel continuum formulation rooted in the molecular structure of the membrane and apply it to analyze model deformations similar to those that occur during aspiration of RBCs into micropipettes. The microscopic elastic properties of the skeleton are derived by treating spectrin tetramers as simple linear springs. For a given local deformation of the skeleton, we determine the average bond energy and define the corresponding strain energy function and stress-strain relationships. The lateral redistribution of the skeleton is determined variationally to correspond to the minimum of its total energy. The predicted dependence of the length of the aspirated tongue on the aspiration pressure is shown to describe the experimentally observed system behavior in a quantitative manner by taking into account in addition to the skeleton energy an energy of attraction between RBC membrane and the micropipette surface.

Published
2016
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42. Curvature-dependent protein-lipid bilayer interaction and cell mechanosensitivity.

Author

Svetina S

Subjects
Amino Acid Sequence, Animals, Biomechanical Phenomena, Cell Membrane chemistry, Cell Membrane metabolism, Humans, Membrane Lipids chemistry, Molecular Sequence Data, Potassium Channels, Voltage-Gated chemistry, Protein Binding, Mechanotransduction, Cellular, Membrane Lipids metabolism, Potassium Channels, Voltage-Gated metabolism
Abstract

Cells respond to applied external forces through different mechanosensitive processes, with many of them based on the interaction between membrane-embedded proteins and their lipid environments. This interaction can depend on membrane curvature at the location of such proteins. Here we elucidate the general characteristics of a macroscopically defined protein-lipid bilayer interaction based on a mismatch between the shape of the protein surface and the surrounding membrane curvature. It is shown how the parameters of this interaction are related to the experimentally determined distribution of membrane-embedded proteins between highly curved tubular and flat membrane regions of a giant phospholipid vesicle. The results obtained for such distribution of potassium channel KvAP are presented as an example. Possible participation of the curvature-dependent protein-lipid bilayer interaction in mechanosensitive processes is indicated.

Published
2015
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43. Mechanical and molecular basis for the symmetrical division of the fission yeast nuclear envelope.

Author

Castagnetti S, Božič B, and Svetina S

Subjects
Chromosomes, Fungal metabolism, Spindle Pole Bodies metabolism, Nuclear Envelope metabolism, Schizosaccharomyces cytology, Schizosaccharomyces metabolism
Abstract

In fission yeast Schizosaccharomyces pombe, the nuclear envelope remains intact throughout mitosis and undergoes a series of symmetrical morphological changes when the spindle pole bodies (SPBs), embedded in the nuclear envelope, are pushed apart by elongating spindle microtubules. These symmetrical membrane shape transformations do not correspond to the shape behavior of an analogous system based on lipid vesicles. Here we report that the symmetry of the dividing fission yeast nucleus is ensured by SPB-chromosome attachments, as loss of kinetochore clustering in the vicinity of SPBs results in the formation of abnormal asymmetric shapes with long membrane tethers. We integrated these findings in a biophysical model, which explains the symmetry of the nuclear shapes on the basis of forces exerted by chromosomes clustered at SPBs on the extending nuclear envelope. Based on this analysis we conclude that the fission yeast nuclear envelope exhibits the same mechanical properties as simple lipid vesicles, but interactions with other cellular components, such as chromosomes, influence the nuclear shape during mitosis, allowing the formation of otherwise energetically unfavorable symmetrical dumbbell structures upon spindle elongation. The model allows us to explain the appearance of abnormal asymmetric shapes in fission yeast mutants with mis-segregated chromosomes as well as with altered nuclear membrane composition.

Published
2015
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44. Sorting of integral membrane proteins mediated by curvature-dependent protein-lipid bilayer interaction.

Author

Božič B, Das SL, and Svetina S

Subjects
Lipid Bilayers metabolism, Membrane Proteins metabolism, Models, Biological, Potassium Channels metabolism, Lipid Bilayers chemistry, Membrane Proteins chemistry, Potassium Channels chemistry
Abstract

Cell membrane proteins, both bound and integral, are known to preferentially accumulate at membrane locations with curvatures favorable to their shape. This is mainly due to the curvature dependent interaction between membrane proteins and their lipid environment. Here, we analyze the effects of the protein-lipid bilayer interaction energy due to mismatch between the protein shape and the principal curvatures of the surrounding bilayer. The role of different macroscopic parameters that define the interaction energy term is elucidated in relation to recent experiment in which the lateral distribution of a membrane embedded protein potassium channel KvAP is measured on a giant unilamellar lipid vesicle (reservoir) and a narrow tubular extension - a tether - kept at constant length. The dependence of the sorting ratio, defined as the ratio between the areal density of the protein on the tether and on the vesicle, on the inverse tether radius is influenced by the strength of the interaction, the intrinsic shape of the membrane embedded protein, and its abundance in the reservoir. It is described how the values of these constants can be extracted from experiments. The intrinsic principal curvatures of a protein are related to the tether radius at which the sorting ratio attains its maximum value. The estimate of the principal intrinsic curvature of the protein KvAP, obtained by comparing the experimental and theoretical sorting behavior, is consistent with the available information on its structure.

Published
2015
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45. Nonlocal membrane bending: a reflection, the facts and its relevance.

Author

Svetina S and Žekš B

Subjects
Algorithms, Animals, Biophysical Phenomena, Biophysics trends, Cell Shape, Elasticity, Energy Transfer, Humans, Lipid Bilayers, Membrane Fusion, Organelle Shape, Surface Properties, Biophysics methods, Cell Membrane chemistry, Intracellular Membranes chemistry, Models, Biological
Abstract

About forty years ago it was realized that phospholipid membranes, because they are composed of two layers, exhibit particular, and specific mechanical properties. This led to the concept of nonlocal membrane bending, often called area difference elasticity. We present a short history of the development of the concept, followed by arguments for a proper definition of the corresponding elastic constant. The effects of the nonlocal bending energy on vesicle shape are explained. It is demonstrated that lipid vesicles, cells and cellular aggregates exhibit phenomena that can only be described in a complete manner by considering nonlocal bending., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Published
2014
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46. Direct and remote constriction of membrane necks.

Author

Božič B, Guven J, Vázquez-Montejo P, and Svetina S

Subjects
Actins metabolism, Lipid Bilayers chemistry, Polymerization, Cell Membrane physiology, Endocytosis physiology, Models, Biological, Transport Vesicles physiology
Abstract

The physical properties of membrane necks are relevant in vesiculation, a process that plays an essential role in cellular physiology. Because the neck's radius is, in general, finite, membrane scission and the consequent pinching off of the vesicle can only occur if it is narrowed to permit the necessary membrane topological reformation. Here we examine, in a simple single phase lipid vesicle, how external forces can promote neck constriction not only by direct compression at the neck but also, counterintuitively, by dilation at remote locations. These results provide a new perspective on the role played by actin polymerization in the process of endocytosis.

Published
2014
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47. Positioning of integrin β1, caveolin-1 and focal adhesion kinase on the adhered membrane of spreading cells.

Author

Jokhadar SZ, Majhenc J, Svetina S, and Batista U

Subjects
Bridged Bicyclo Compounds, Heterocyclic pharmacology, Cell Adhesion drug effects, Cell Membrane metabolism, Chlorides pharmacology, Human Umbilical Vein Endothelial Cells, Humans, Manganese Compounds pharmacology, Microscopy, Fluorescence, Phosphorylation drug effects, Thiazolidines pharmacology, Caveolin 1 metabolism, Focal Adhesion Protein-Tyrosine Kinases metabolism, Integrin beta1 metabolism
Abstract

We have investigated the relationship between the spreading of anchorage-dependent cells and the surface-density distribution of plasma membrane adhesion proteins. The surface positioning and density of integrin β1, caveolin-1 (cav-1), the phosphorylated caveolin-1 (p-cav-1) and the focal adhesion kinase (FAK) located on the adhering cell membrane (ACM) of HUVEC cells was studied. Imaging with TIRF microscopy was used, which enabled us to observe a few-nanometers-thin section of the cell above the plasma membrane in combination with image-based analyses. Integrin β1 and cav-1 have spatial interdependence on the ACM. Cells treated with substances that act on cell spreading caused changes in the size of the ACM area, as well as a redistribution of several proteins under investigation. Changes to the ACM area correlated positively with those to the surface density of the cav-1. The high integrin β1 and the low cav-1 surface density, and vice versa, following the treatments show that the presence of one of them not only spatially excludes, but also reduces, the occurrence of the other protein on the ACM, which indicates a regulative mechanism between integrin β1 and cav-1., (© 2013 International Federation for Cell Biology.)

Published
2013
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48. Partitioning of oleic acid into phosphatidylcholine membranes is amplified by strain.

Author

Mally M, Peterlin P, and Svetina S

Subjects
Glucose chemistry, Glycerol chemistry, Microscopy, Phase-Contrast, Sucrose chemistry, Unilamellar Liposomes metabolism, Oleic Acid chemistry, Phosphatidylcholines chemistry, Unilamellar Liposomes chemistry
Abstract

Partitioning of fatty acids into phospholipid membranes is studied on giant unilamellar vesicles (GUVs) utilizing phase-contrast microscopy. With use of a micropipet, an individual GUV is transferred from a vesicle suspension in a mixed glucose/sucrose solution into an isomolar glycerol solution with a small amount of oleic acid added. Oleic acid molecules intercalate into the phospholipid membrane and thus increase the membrane area, while glycerol permeates into the vesicle interior and thus via osmotic inflation causes an increase of the vesicle volume. The conditions are chosen at which a vesicle swells as a sphere. At sufficiently low oleic acid concentrations, when the critical membrane strain is reached, the membrane bursts and part of vesicle content is ejected, upon which the membrane reseals and the swelling commences again. The radius of the vesicle before and after the burst is determined at different concentrations of oleic acid in suspension. The results of our experiments show that the oleic acid partitioning increases when the membrane strain is increased. The observed behavior is interpreted on the basis of a tension-dependent intercalation of oleic acid into the membrane.

Published
2013
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49. Cellular life could have emerged from properties of vesicles.

Author

Svetina S

Subjects
Lipid Bilayers, Selection, Genetic, Biological Evolution, Cells
Abstract

It is indicated why it is plausible to assume that the initiation of cellular life was based on properties of vesicles. Vesicle properties relevant for the process of vesicle self-reproduction are revealed. Some open questions related to the idea that vesicle self-reproduction is an evolutionary process that includes the elements of the Darwinian selection are put forward, and some suggestions are made for possible directions of further research.

Published
2012
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50. Red blood cell shape and deformability in the context of the functional evolution of its membrane structure.

Author

Svetina S

Subjects
Biological Evolution, Cell Shape, Erythrocyte Membrane chemistry, Erythrocyte Membrane metabolism, Humans, Membrane Proteins metabolism, Erythrocyte Deformability, Erythrocytes cytology
Abstract

It is proposed that it is possible to identify some of the problems that had to be solved in the course of evolution for the red blood cell (RBC) to achieve its present day effectiveness, by studying the behavior of systems featuring different, partial characteristics of its membrane. The appropriateness of the RBC volume to membrane area ratio for its circulation in the blood is interpreted on the basis of an analysis of the shape behavior of phospholipid vesicles. The role of the membrane skeleton is associated with preventing an RBC from transforming into a budded shape, which could form in its absence due to curvature-dependent transmembrane protein-membrane interaction. It is shown that, by causing the formation of echinocytes, the skeleton also acts protectively when, in vesicles with a bilayer membrane, the budded shapes would form due to increasing difference between the areas of their outer and inner layers.

Published
2012
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