Cellular & Molecular Biology Letters

International Scientific Journal
Established 1996

Volume 8 (2003) No. 4

Volume 8 (2003) pp 873 – 884
Title	In vitro AND in vivo ANALYSES OF THE BIOLOGICAL ACTIVITY OF RGD PEPTIDES TOWARDS AB BOMIRSKI MELANOMA
Authors	Marcin Okrój¹, Zuzanna Dobrzańska-Paprocka¹, Krzysztof Rolka² and Jacek Bigda¹
Abstract	The RGD sequence is present in many extracellular matrix proteins and intracellular proteins, including caspases. Synthetic RGD peptides may affect adhesion, migration and tumour metastasis, or directly induce apoptosis. Several RGD peptides were synthesised, and their anti-adhesive and cytotoxic properties were analysed in vitro. The most active peptide (poly RGD) was also tested in vivo to assess its modulatory activity on melanoma growth. Synthetic RGD peptides inhibit the adhesion of Ab melanoma cells to fibronectin. Poly RGD significantly inhibits primary tumour growth. There was no observed cytotoxicity of poly RGD towards Ab cells in a medium with 10% serum; however, under the same conditions, the anti-adhesive effect of poly RGD was still visible. Experiments on Jurkat cells indicated a weak cytotoxicity of poly RGD and a significant cytotoxicity of GRGDNP (the reference cytotoxic peptide), retained only under serum-free conditions. The anti-tumour effect of poly RGD observed in the Ab Bomirski melanoma model is probably due to an anti-adhesive mechanism. The proapoptotic activity of RGD peptides is dependent on the absence of serum.
Adress and Contact Informations	¹Department of Cell Biology, Intercollegiate Faculty of Biotechnology Medical University of Gdańsk, Dębinki 1, 80-211 Gdańsk, Poland, ²Department of Bioorganic Chemistry, Faculty of Chemistry, University of Gdańsk, Sobieskiego 18 /19, 80-952 Gdańsk, Poland

Volume 8 (2003) pp 885 – 890
Title	THE INTERACTION OF DAUNORUBICIN AND MITOXANTRONE WITH THE RED BLOOD CELLS OF ACUTE MYELOID LEUKEMIA PATIENTS
Authors	Agnieszka Marczak¹*, Agata Wrzesień-Kuś², Euzebiusz Krykowski², Tadeusz Robak² and Zofia Jóźwiak¹
Abstract	The effect of DNR and MIT on erythrocyte membrane structure was examined using Electron Spin Resonance spectroscopy and the fluorimetric technique. The results suggest that the in vivo interaction of the drugs with the RBCs of AML patients led to a perturbation in the structure of plasma membrane components. Differences between DNR and MIT were only noted in the interaction of the drugs with deeper regions of the lipid bilayer.
Adress and Contact Informations	¹Department of Thermobiology, University of Łódź, ul. Banacha 12/16, 90-237 Łódź Poland, ²Department of Hematology, Medical Academy, Łódź, Poland * Corresponding author, E-mail: aszwar@biol.uni.lodz.pl Fax: (42) 6354473

Volume 8 (2003) pp 891 – 899
Title	*IDENTIFICATION OF Phoenix dactylifera L.* VARIETIES BASED ON AMPLIFIED FRAGMENT LENGTH POLYMORPHISM (AFLP) MARKERS**
Authors	Susana Diaz, Carmen Pire, Juan Ferrer and Maria José Bonete
Abstract	The amplified fragment length polymorphism (AFLP) technique was applied to identify palm varieties. Fluorescence labelled primers were used in selective amplifications and the amplified fragments were detected on capillary gel electrophoresis using an automated DNA sequencer with the analysis fragment option. This is a rapid and efficient technique for detecting a large number of DNA markers on the date palm. Phoenix dactylifera L. varieties Bou- Fegous, Medjool, and E-528 from Estación Phoenix (Elche), Spain, were analysed, yieding a total of 310 AFLP fragments derived from five primer combinations. The process for regenerating the date palm cultivars from in vitro tissue culture should yield individuals phenotypically and genetically identical to the explant they are derived from. The AFLP markers obtained were successfully used for comparing and identifying vitroplants of palm.
Adress and Contact Informations	Departamento de Agroquímica y Bioquímica, Facultad de Ciencias, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain

Volume 8 (2003) pp 901 – 909
Title	INCREASED LIPOGENIC POTENTIAL OF RAT ADIPOSE TISSUE AFTER REPEATED DIETING – THE ROLE OF SREBP-1 TRANSCRIPTION FACTOR
Authors	Zdzislaw Kochan*
Abstract	Repeated dieting is one of the methods used for weight reduction; however, its effectiveness is questionable. We developed an experimental, rat model of repeated dieting, which mimics the dietary approach used in the treatment of obesity in humans. In this experimental model, despite the lower caloric intake, decreased body mass and reduced fat stores, the lipogenic potential of adipose tissue increased. We observed a substantial increase in fatty acid synthase (a key lipogenic enzyme) gene expression in rat adipose tissue accompanied by a 9-fold increase in the serum insulin level. Fatty acid synthase gene expression is controlled at the transcriptional level by SREBP-1. In this study, a remarkable increase (24-fold) in SREBP-1 protein amount, parallel to that in fatty acid synthase mRNA level, protein concentration and enzyme activity was observed after multiple cycles of fasting-refeeding. Although it is possible that the interactions between transcription factors are more complex, we propose that the pivotal role in the increase of the lipogenic potential of adipose tissue after repeated dieting may be played by SREBP-1.
Adress and Contact Informations	Department of Biochemistry, Medical University of Gdansk, Debinki 1, 80-211 Gdansk, Poland * E-mail: kochanz@amg.gda.pl

Volume 8 (2003) pp 911 – 917
Title	QUANTITATIVE ANALYSIS OF LacCer/CDw17 IN HUMAN MYELOGENOUS LEUKAEMIC CELLS
Authors	Justyna Spychalska¹, Gabriela Smoleńska-Sym¹*, Ewa Zdebska¹, Jolanta Woźniak² and Jerzy Kościelak¹
Abstract	LacCer/CDw17 is the most abundant GSL in neutrophils. The cellsurface and intracellular presence of LacCer was determined quantitatively using anti-CDw17 mAbs in a flow cytometry assay. The quantified alterations in the level of CDw17 antigen expression are consistent with alterations in LacCer content, determined chemically. Our results show that CDw17 antigen expression defines successive stages in the maturation of the myeloid cell. The assessment of cell-surface and intracellular CDw17 expression may be useful in evaluating neutrophil physiological status.
Adress and Contact Informations	¹Department of Biochemistry, and ²Department of Pathophysiology, Institute of Haematology and Blood Transfusion, Chocimska 5, 00-957 Warsaw, Poland * Corresponding author: E-mail: gabsym@ihit.waw.pl

Volume 8 (2003) pp 919 – 925
Title	CAPSAICIN-INDUCED ACTIVATION OF ERYTHROCYTE MEMBRANE SODIUM/POTASSIUM AND CALCIUM ADENOSINE TRIPHOSPHATASES
Authors	Syed Ibrahim Rizvi and Suaib Luqman
Abstract	Capsaicin is the pungent ingredient present in hot peppers of the genus Capsicum. Capsaicin’s effect on sensory neurons has been well studied; however, its effect on non-neuronal cells is still not fully understood. This study was undertaken to evaluate the effect of capsaicin on erythrocyte membrane enzymes: Na⁺/K⁺-ATPase and Ca²⁺-ATPase. Treatment with capsaicin (0.01- 100mM) caused a transient increase in the activities of both enzymes; the effect declined at lower concentrations of capsaicin, and no significant effect was observed at 0.01mM capsaicin. The effect of capsaicin was fast with a significant (p<0.01) activation of enzyme activity observed within minutes of incubation. The findings on the effect of capsaicin on human erythrocyte membrane enzymes Na⁺/K⁺-ATPase and Ca²⁺-ATPase signify the importance of the nonneuronal effects of capsaicin, and the need for evaluating the physiological impact of high capsaicin (capsicum) consumption in some regions of the world.
Adress and Contact Informations	Department of Biochemistry, University of Allahabad, Allahabad – 211002, India

Volume 8 (2003) pp 927 – 942
Title	ANTIMUTAGENIC ACTIVITY OF NEW ANALOGUES OF FLUPHENAZINE
Authors	Kazimierz Gąsiorowski¹*, Wiesław Malinka², Piotr Świątek² and Agata Jaszczyszyn¹
Abstract	Fluphenazine (FPh) exhibited antimutagenic activity in lymphocyte cultures, markedly decreasing genotoxic effects of standard mutagenic agents present in cell cultures. However, the strong pharmacological activity of this neuroleptic drug, together with its serious side effects on the central nervous system, limits its use as an antimutagenic compound. In this paper we describe a route of chemical synthesis of FPh analogues that are more hydrophilic than the model compound, thus probably penetrate more weakly through the blood-brain barrier. These new analogues were tested for their antimutagenic and proapoptotic activities in human lymphocyte cultures, genotoxically damaged in vitro with benzo[a]pyrene [40 μM, 30 min] and subsequently cultured for 48 h in the presence of the tested compounds. The fluphenazine analogues enhanced apoptosis in genotoxically damaged lymphocytes more strongly than the model compound did. The increase of apoptotic cell frequency was the highest with compound 4a [2-(trifluoromethyl)- 10-[3-(diethanolamino)-2-hydroxypropyl] phenothiazine] – a 35% higher effect than that of fluphenazine. The cytotoxicity of derivative 4a was the lowest among the tested compounds; it was 60% lower than that of fluphenazine. The antimutagenic effect of 4a was about 10% stronger than that of fluphenazine. Compund 4a also had the highest hydrophilicity of the new FPh analogues. Compound 4a was chosen for further study as a potentially usable antimutagen that would only weakly penetrate the central nervous system.
Adress and Contact Informations	¹Department of Basic Medical Sciences, Wrocław Medical University, Wrocław, Poland, ²Department of Drug Chemistry, Wrocław Medical University, Wrocław, Poland *Corresponding author, tel.: (48 71) 3484310, fax: (48 71) 3479211, e-mail: kaz@basmed.am.wroc.pl

Volume 8 (2003) pp 943 – 954
Title	THE DEPENDENCE OF FLUORESCEIN-PE FLUORESCENCE INTENSITY ON LIPID BILAYER STATE. EVALUATING THE INTERACTION BETWEEN THE PROBE AND LIPID MOLECULES
Authors	Krystian Kubica¹, Marek Langner² and Janina Gabrielska¹
Abstract	The degree of dependence of a lipid bilayer’s surface properties on its conformational state is still an unresolved question. Surface properties are functions of molecular organization in the complex interfacial region. In the past, they were frequently measured using fluorescence spectroscopy. Since a fluorescent probe provides information on its local environment, there is a need to estimate the effect caused by the probe itself. In this paper, we address this question by calculating how lipid head-group orientation effects the fluorescence intensity of Fluorescein-PE (a probe that is sensitive to surface potential). In the theoretical model assumed the lipid bilayer state and the interactions between the charged fluorescent probe and the surrounding lipid molecules was evaluated. The results of this theoretical analysis were compared with experimentally obtained data. A lipid bilayer formed from DPPC was chosen as the experimental system, since it exhibits all the major conformational states within a narrow temperature range of 30ºC - 45ºC. Fluorescein-PE fluorescence intensity depends on local pH, which in turn is sensitive to local electrostatic potential in the probe’s vicinity. This local electrostatic potential is generated by lipid head-group dipole orientation. We have shown that the effect of the probe on lipid bilayer properties is limited when the lipid bilayer is in the gel phase, whereas it is more pronounced when the membrane is liquid-crystalline. This implies that Fluorescein-PE is a good reporter of local electrostatic fields when the lipid bilayer is in the gel phase, and is a poor reporter when the membrane is in the liquid-crystalline state.
Adress and Contact Informations	¹Agricultural University, Department of Physics and Biophysics, Norwida 25, 50-375 Wrocław, Poland, ²Wrocław University of Technology, Institute of Physics, Wybrzeże Wyspiańskiego 27, Wrocław, Poland

Volume 8 (2003) pp 955 – 961
Title	THE CHROMOSOMAL LOCATION OF RYE AFLP BANDS
Authors	Piotr Tomasz Bednarek*, Renata Lewandowska, Tomasz Gołas and Małgorzata Paśnik
Abstract	23 AFLP bands were assigned to different rye chromosomes by means of two different sets of wheat-rye addition lines. Only one AFLP band could be assigned to 4R, and no specific AFLPs were found on the 5R chromosome. Only one AFLP band was explicitly assigned to 4R, and no specific AFLPs were found on the 5R chromosome. At least seven co-migrating AFLPs showed the same chromosomal location in both sets of addition lines. A total of 22 AFLPs were assigned to chromosome 1R using wheat-rye substitution lines. Six of them have counterparts in one of the addition lines analyzed, but only four have the same chromosomal location. Six and four of the total AFLPs located using addition (23) and substitution (22) lines segregated in the mapping population DS2 x RXL10, but only six were simultaneously assigned to the same chromosome by both approaches. Although co-migrating AFLPs could be located on different rye chromosomes using addition and substitution lines, we believe that AFLPs can be useful as rye chromosome markers.
Adress and Contact Informations	The Botanical Garden – the Center for the Conservation of Biological Diversity of the Polish Academy of Sciences, 02-973 Warsaw, ul. Prawdziwka 2, Poland * Corresponding author: E-mail: tmol.ob.@ihar.edu.pl

Volume 8 (2003) pp 963 – 972
Title	*AN ASSESSMENT OF THE RESISTANCE GENE ANALOGUES OF Oryza sativa ssp. japonica: THEIR PRESENCE AND STRUCTURE*
Authors	Grzegorz Koczyk* and Jerzy Chełkowski
Abstract	Rice is the first cereal genome of known draft sequence, and the finished sequence for it is now nearly complete. In this paper, we describe a preliminary analysis of known rice genes aimed to detect resistance gene analogues of known structural classes. Putative resistance genes were identified in a dual approach – by using BLASTP searches to identify candidate sequences and by using Hidden Markov Models to predict domain presence in the candidates. The set of proteins examined was obtained from the publicly available data of TIGR (The Institute for Genomic Research). 1744 distinct RGAs were identified, 597 of which belonged to the NBS-LRR class. Supplementary data (sequences and annotations) is available on the web site http:/gkoczyk.bioinfo.pl/CMBL.
Adress and Contact Informations	Institute of Plant Genetics, Polish Academy of Sciences, Poznań, Poland * Corresponding author, e-mail: gkoczyk@echostar.pl

Volume 8 (2003) pp 973 – 977
Title	THE TOTAL ANTIOXIDANT CAPACITY OF BLOOD PLASMA DURING CARDIOVASCULARY BYPASS SURGERY IN PATIENTS WITH CORONARY HEART DISEASE
Authors	Kornelia Kędziora-Kornatowska¹, Małgorzata Bartosz², Mirosław Mussur³, Janusz Zasłonka³, Józef Kędziora⁴ and Grzegorz Bartos⁵
Abstract	We studied he effect of ischemia and reperfusion on the total antioxidant capacity (TAC) of blood plasma during cardiopulmonary bypass surgery employing the modified St. Thomas Hospital cardioplegic solution. TAC was determined using the FRAP method. TAC decreased during surgery, but no further decrease in TAC was observed during reperfusion, indicating that it is a relatively stable parameter of the antioxidative barrier of the body.
Adress and Contact Informations	¹Department and Clinic of Geriatry, Medical University of Bydgoszcz, M. Skłodowskiej-Curie 9, 85-094 Bydgoszcz, Poland, ²Department of Physical and Health Education, University of Łódź, Poland, ³Department of Cardiosurgery, Medical University of Łódź, Poland, ⁴Department of Biochemistry, Medical University of Bydgoszcz, and Department of Biochemistry, Medical University of Łódź, Poland, ⁵Department of Molecular Biophysics, University of Łódź, and Department of Biochemistry and Cell Biology, University of Rzeszów, Poland

Volume 8 (2003) pp 979 – 989
Title	CULTURE TREATMENTS FOR ENHANCING POST-THAW RECOVERY OF CRYOPRESERVED SUSPENSION CELLS OF POTATO CV. DESIREE
Authors	Bushra Sadia¹, Paul Anthony¹, Kenneth C. Lowe², J. Brian Power¹ and Michael R. Davey¹*
Abstract	An efficient and reproducible protocol has been developed for the cryopreservation of cell suspension cultures of the potato (Solanum tuberosum L.) cv. Desiree. An evaluation was made of the effectiveness of different preculture and post-thaw treatments on cell growth, as measured by changes in biomass. Cell suspensions were cultured in UM medium supplemented with 0.25, 0.5, 0.625, 0.75 or 1.0 M sucrose prior to cryopreservation. Sucrose-treated cells were harvested from suspension and 0.75 ml packed cell volumes placed in 2 ml capacity polypropylene vials with 0.5 ml of chilled cryoprotectant (glycerol 46.0 g 1-1, dimethylsulphoxide 39.0 g 1-1, sucrose 342.0 g 1-1 proline 5.0 g 1-1; pH 5.8). Cells were frozen at -0.5°C min-1 from 0 to -35°C, held at -35°C for 35 min and stored, for 10 days, in liquid nitrogen (-196°C). The most effective pretreatment, in terms of subsequent post-thaw cell viability as assessed by fluorescein diacetate uptake or triphenyltetrazolium chloride reduction, was culture with 0.75 M sucrose. For this treatment, the mean absorbance (490 nm) following triphenyltetrazolium chloride reduction was 88% greater (p < 0.05) than control and 59% greater (p < 0.05) for thawed cells also cultured on supporting filter paper discs.
Adress and Contact Informations	¹Plant Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK, ²School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, UK * Corresponding author, e-mail: mike.davey@nottingham.ac.uk

Volume 8 (2003) pp 991 – 1003
Title	Desulfovibrio desulfuricans LIPOPOLYSACCHARIDES INDUCE ENDOTHELIAL CELL IL-6 AND IL-8 SECRETION AND E-SELECTIN AND VCAM-1 EXPRESSION
Authors	Ludmiła Węglarz*, Zofia Dzierżewicz, Barbara Skop, Arkadiusz Orchel, Beata Parfiniewicz, Beata Wiśniowska, Longina Świątkowska and Tadeusz Wilczok
Abstract	The aim of this study was to determine whether Desulfovibrio desulfuricans-derived LPS stimulate the release of IL-6 and IL-8 from ECs and the expression of their adhesion molecules at the transcriptional level. Confluent monolayers of HUVEC were incubated in the absence or presence of 20 μg/ml and 60 μg/ml LPSs derived from the DdT and DdA bacterial strains. Also, the simultaneous stimulation of cells with LPSs and IL-1β was evaluated. The levels of cytokines released were measured using ELISA. LPS-activated HUVEC increased the secretion of both IL-6 and IL-8, which was not LPS dose dependent. The expression of E-selectin and VCAM-1 was assessed by TRPCR. The transcripts were detectable at all the concentrations (20, 40, 60 μg/ml) of LPSs used. These results suggest that D. desulfuricans LPS may activate immune functions in endothelial cells and influence the inflammatory response during bacteremia caused by these bacteria.
Adress and Contact Informations	Department of Molecular Biology, Biochemistry and Biopharmacy, Medical University of Silesia, Narcyzów 1, 41-200 Sosnowiec, Poland * Corresponding author: e-mail: lweglarz@slam.katowice.pl

Volume 8 (2003) pp 1005 – 1011
Title	DICARBOXYLATE PLATINUM(II) COMPLEXES AS INHIBITORS OF PLASMA MEMBRANE H⁺-ATPase IN THE YEAST
Authors	Ewa Obłąk¹, Tadeusz M. Lachowicz², Katarzyna Waszkiewicz³ and Janina Kuduk-Jaworska³
Abstract	A series of cytotoxic neutral dicarboxylatoplatinum(II) complexes containing D(+), L(-) or DL-malate dianion and ethylenediamine or 1- ethylimidazole as ligands were examined using ATPase activity assays and the proton extrusion test. ATPase activity assays in vitro on plasma membrane H+- ATPase and on mitochondrial ATPase were carried out. The concentrations of compounds inhibiting enzyme activity to 50 per cent (J50) was determined. The new platinum complexes showed a stronger level of inhibition of both ATPases than the reference carboplatin; this inhibitory activity is related to a stereoisomeric form of anionic platinum ligands. ATPase inhibition in vivo was tested by glucose-stimulated proton extrusion and the influence of platinum compounds on this process in yeast cells was determined. Significant differences in activity levels were observed between those complexes with 1-ethylimidazole and those with ethylenediamine.
Adress and Contact Informations	¹Institute of Microbiology, University of Wrocław, Przybyszewskiego 65/73, 51-148 Wrocław, Poland, ²Institute of Biotechnology and Environmental Protection University of Zielona Góra, Monte Casino 3a, 65-561 Zielona Góra, Poland, ³Faculty of Chemistry, Wrocław University, F. Joliot-Curie 14, 50-383 Wrocław, Poland

Volume 8 (2003) pp 1013 – 1016
Title	ANALYSIS OF HIGH-PRESSURE-INDUCED DISRUPTION OF HUMAN ERYTHROCYTES BY FLOW CYTOMETRY
Authors	Takeo Yamaguchi and Shigeyuki Terada
Abstract	High-pressure-induced hemolysis is suppressed by pretreating human erythrocytes at 49°C, or enhanced by pretreatment with trypsin. So, the response of these pretreated cells to a pressure of 200 MPa was examined using flow cytometry. In the case of intact erythrocytes, a major product was fragmented particles. From 49°C-pretreated cells, vesicles were mainly released. Trypsinpretreated cells mainly produced open ghosts. Additionally, intact erythrocytes, 49°C-pretreated ones, and trypsin-pretreated ones also released at 200 MPa vesicles of diameter 464 +/- 9, 259 +/- 18, and 574 +/- 16 nm, respectively. These results suggest that mother cells, fragmented particles, vesicles, and open ghosts from 200 MPa-treated erythrocytes are easily monitored by flow cytometry and that the size of released vesicles may also be an important factor in highpressure- induced hemolysis.
Adress and Contact Informations	Department of Chemistry, Faculty of Science, Fukuoka University, Jonan-ku, Fukuoka, 814-0180 Japan

Volume 8 (2003) pp 1017 – 1033
Title	FORCE GENERATION BY CELLULAR MOTORS
Authors	Friedrich Wanka* and Everardus J.J. Van Zoelen
Abstract	Cell motility processes in non-muscle cells depend on the activity of motor proteins that bind to either microtubules or actin filaments. From presently available data it must be concluded that the driving force is generated by transient interaction of the respective motors with microtubules or actin filaments which then activates the binding and hydrolysis of ATP. This reaction results in an abrupt discharge of the motor molecule, the direction of which is determined by the spatial orientation of its binding to the helical and polar vehicle. The latter is thereby propelled in its length direction and simultaneously undergoes an axial rotation, while the expelled motor exerts an oppositely directed current in the surrounding fluid, comparable to jet propulsion. Force production, propulsion velocities and energy requirements known from in vitro studies comply with those derived from the theory. The theory opens new ways for the understanding of cellular activities such as particle transport, mitosis and morphodynamics.
Adress and Contact Informations	Department of Cell Biology, University of Nijmegen, Toernooiveld 1 6525 ED Nijmegen, The Netherlands * Corresponding author

Volume 8 (2003) pp 1035 – 1045
Title	CELLULAR ORGANELLE TRANSPORT AND POSITIONING BY PLASMA STREAMING
Authors	Friedrich Wanka* and Everardus J.J. Van Zoelen
Abstract	Our analysis of known data reveals that translocations of passively movable cellular organelles from tiny granules up to large cell nuclei can be ascribed to transport by streaming cytoplasm. The various behaviours, such as velocity changes during more or less interrupted movements, forth and back shuttling and particle rotation result from different types of plasma circulation. Fast movements over long distances, as observed in the large characean internodial cells occur in strong streams generated by myosin in bundles of actin filaments in the direction of the barbed filament ends. Slow movements with frequent reversions of the direction are typical for neuronal axons, in which an anterograde plasma flow, produced in a thin layer of membrane-attached actin filaments, is compensated by a retrograde stream, produced by dynein activity in the central bundle of microtubules. Here particle rotation is due to steep flow velocity gradients, and frequent changes of particle movements result from minor particle displacements in radial directions. Similar shuttling of pigment granules in the lobes of epidermal chromatophores results from the same mechanism, whereby the centrifugal movement along astral microtubules is due to flow generated by excess of kinesin activity and the centripetal movement to the plasma recycling through the intermicrotubular space. If the streaming pattern is reversed by switching to excess dynein activity, the moving granules are trapped in the high microtubule density at the aster center. The presence of larger bodies in asters disturbs the regular, kinesin-dependent microtubule distribution in such a way that a superimposed centrifugal plasma flow develops in the microtubule-dense layer along them, which is recycled in the microtubulefree space, created by their presence. Consequently, at excess kinesin activity, nuclei, mitochondria as well as chromosome fragments move towards the aster center until they reach a dynamically stabilized position that depends on the local microtubule density. These various behaviours are not rationally explainable by models based on a mechanical stepping along microtubules or actin filaments.
Adress and Contact Informations	Department of Cell Biology, University of Nijmegen, Toernooiveld 1 6525 ED Nijmegen, The Netherlands * Corresponding author

Cover

Office:

Cellular & Molecular Biology Letters
Faculty of Biotechnology
University of Wrocław
Przybyszewskiego 63/77
51-148 Wrocław, Poland

fax:

+48 71 375 6208 or
+48 71 375 6234

e-mail:

cmbl@cmbl.org.pl or
cmbl@ibmb.uni.wroc.pl

Web Page Design, Programing and Copyright Tadeusz Czuj