Vol. 2 No. 3 September 1997

Volume 2 (1997) pp>257-263
Title PINK'S MODEL AND LIPID MEMBRANES
Authors K.Kubica
Abstract The paper presents a discussion of the basic assumptions of the Pink's model, which is often used for interpreting phenomena connected with biological membranes. For over ten years now the model has been constantly developed, but its basic assumptions have not ever been evaluated, such as: constant value of surface pressure, independent of composition of the system studied; approximate value (1200) of the angle between -C-C- bonds in alkyl chains of the membrane molecules; or treating both lipid chains as identical and independent.
Address and Contact Information Agricultural University, Department of Physics and Biophysics, 50 375 Wroclaw, Norwida 25, Poland
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 265-276
Title MODELLING OF POPULATION DYNAMICS IN BATCH AND CONTINUOUS CULTURE OF SHIGELLA FLEXNERI 3b SEROVAR LYSOGENIC FOR A PLAQUE-LESS PHAGE, AND SHIGELLA FLEXNERI 1b SEROVAR WHICH IS SENSITIVE TO IT
Authors B. Kopocinski*, J. Niedbach+, Z. Kawa+ and T. M. Lachowicz+
Abstract Population dynamics in bath and continuous culture of Shigella flexneri 3b lysogenic for plaque-less phage X and sensitive to this phag 1b serovars have been determined. The abrupt change in the fraction of lysogens resulting from the death, especially of sensitive cells, was observed. The death should result of spontaneous liberation of phage X as concluded from the growth dynamics of the sensitive strain infected with the phage containing bacteria-free filtrate of 3b lysogen. Basing on experimental data mathematical modelling of the dynamics with the use of the differential equation set has been proposed. In the models a qualitative relation between the strains and the phage, estimation of growth parameters and estimated growth curves are given.
Address and Contact Information * Mathematical Institute, University of Wroclaw, pl. Grunwaldzki 2/4, 50-384 Wroclaw, Poland,
e-mail: ibk@math.uni.wroc.pl
+ Institute of Microbiology, University of Wroclaw, ul. Przybyszewskiego 63, 51-148 Wroclaw,
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 277-286
Title GENE INSERTION INTO STRAWBERRY LEAF DISK REGENERATION SYSTEM USING PARTICLE BOMBARDMENT
Authors W. Sawahel# and M. Saker*
Abstract Strawberry has previously been transformed using Agrobacterium-mediated DNA transfer. In this paper, we present a process for delivering foreign genes into strawberry leaf disks using particle bombardment. Expression of foreign DNA into strawberry leaf disks (Fragaria X ananassa Duch.) was detected - using in situ GUS assay-following bombardment with tungsten particles coated with plasmid DNA (pBI221.23) that coded for the selectable (hygromycin phosphotransferase [hpt] and the screenable (alpha-glucuronidase [GUS]) marker genes. Both genes are under the control of the Cauliflower Mosaic Virus (CaMV) 35S promoter. The criteria of stability of phenotypes after the removal of selective pressure, Southern blot hybridization and segregation analysis were used to confirm the mitotic stability of the foreign gene and its stable integration into the strawberry genome progeny. The relative simplicity of this system recommends its future use for the production of genetically modified strawberry.
Address and Contact Information Department of Microbial Genetics#
& Department of Plant Cell and Tissue Culture*
National Research Centre, Cairo, Egypt
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 287-299
Title RYANODINE DOES NOT CHANGE PROPERTIES OF LYMPHOCYTE Kv 1.3 CHANNELS
Authors A. Teisseyre*, J. W. Mozrzymas*, H. Vais+, P.N.R. Usherwood+.
Abstract Ryanodine - a plant alkaloid known as a powerful inhibitor of contractions of muscles - changes the selectivity and conductance of several types of K+ channels in muscle cells. Available data provide evidence that the effects of Ryanodine on the K+ channel properties are not secondary to calcium release from sarcoplasmic reticulum, but result from a direct interaction of the alkaloid with the channel protein. In the present investigations we applied the whole-cell patch-clamp technique to extend the area of study of Ryanodine effects on the properties of Kv1.3 channels, which are present in lymphocytes and rat brain cells. During the experiments, the effects of Ryanodine applied in the concentration range 10-5-10-4 M on the selectivity, conductance, gating and kinetics of Kv 1.3 channels expressed in human T lymphocytes were examined. Obtained data provide evidence that none of these properties was changed upon Ryanodine treatment. Results of our study are in a marked contrast to those reported previously in case of several types of K+ channels in muscle cells. Altogether, our data support the notion that Ryanodine may differently interact with K+ channels. The different response to Ryanodine treatment might be another pharmacological feature delineating differences among various types of K+ channels
Address and Contact Information * -Department of Biophysics, University of Medicine, Wroclaw, Poland.
+ -Department of Life Science, University of Nottingham, Great Britain
Corresponding author: Dr Andrzej Teisseyre, University of Medicine, Department of Biophysics, ul. Chalubinskiego 10, 50-368 Wroclaw, Poland, tel: +48-71-209-519, fax: +48-71-22-54-15
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 301-315
Title Beta-ADRENERGIC STIMULATION DOES NOT INFLUENCE THE ACTIVITY OF LYMPHOCYTE Kv 1.3 CHANNELS
Authors A. Teisseyre*, A. Gawlik+, M. Krasnowska+
Abstract The aim of our study was to clarify the still controversial problem concerning the modulatory effect of beta-adrenergic stimulation on the activity of Kv1.3 channels in human T Lymphocytes. Because the expression of beta-adrenergic receptors in T Lymphocytes is significantly altered in patients with bronchial asthma we examined the cells taken both from healthy donors and asthmatic patients. We applied the whole-cell patch-clamp technique to study the modulatory effect of beta-adrenergic stimulation on the whole-cell potassium conductance, gating and kinetics of Lymphocyte Kv1.3 channels. During the experiments beta-adrenergic agonist Isoprenaline was applied at concentrations up to 10-4 M. It was shown that the activity of T lymphocyte Kv1.3 channels remain unchanged upon beta-adrenergic stimulation both in cells taken healthy donors and asthmatic patients. Results of our investigations support the notion that beta-adrenergic stimulation does not modulate the activity of Kv1.3 channels in human TL. The transient increase in T lymphocyte K+ channel activity upon beta-adrenergic stimulation that has been reported in some previous studies is most probably due to an activation of recently identified, voltage-independent cAMP-responsive K+ channels.
Address and Contact Information Departments of Biophysics*, Department of Alergology+, Wroclaw University of Medicine, Wroclaw, Poland.
Corresponding author: Dr Andrzej Teisseyre, University of Medicine, Department of Biophysics,
ul. Chalubinskiego 10, 50-368 Wroclaw, Poland, tel: +48-71-209-519, fax: +48-71-22-54-15.
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 317-324
Title SEQUENCES FLANKING RAT HSP70.1 GENE CONTAIN MOTIFS SPECIFIC FOR MATRIX ATTACHED REGIONS AND FORM COMPLEXES WITH NUCLEAR MATRIX PROTEIN IN VITRO
Authors P. Widlak, J. Rogolinski, K. Lisowska and J. Rzeszowska-Wolny
Abstract Eukaryotic chromatin is organized into looped domains formed by attachment of specific DNA sequences (termed MARs or SARs) to network of nuclear proteins (nuclear matrix). We have looked for matrix attachments within 4.9 kb DNA region encompassing rat hsp70.1 gene. Sequences that flank both 3'-end and 5'-end of the gene contain motifs characteristic for MAR/SARs identified in numerous other genes. These flanking sequences formed in vitro complexes with proteins of the nuclear matrix from different rat tissues. Using Southwestern analysis we showed that similar matrix proteins interacted with sequences flanking rat hsp70.1 gene and established MAR from mouse kappa immunoglobulin gene.
Address and Contact Information Department of Experimental and Clinical Radiobiology, Institute of Oncology, Gliwice, Poland.
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 325-336
Title BIOTECHNOLOGY DEVELOPMENT IN COTTON FIBER: STRATEGIES, APPLICATIONS, AND SOCIO-ECONOMIC IMPACT
Authors W. Sawahel
Abstract Classical breeding provides the means for transferring genes among compatible cotton cultivars, and thereby narrows the number of fibers traits that can be enhanced. On the other hand, recombinant DNA technology provides ways to transfer genes from any living organism into cotton, and therefore opens the door for improving existing fiber quality as well as producing fibers with new and novel properties. As new generations of cotton fibers are developed through genetic engineering, they will impact on the textile industry which is a significant segment of economies of many countries. This article focuses on the recent advances in cotton fiber biotechnology and its impact. The genetic strategies for producing speciality fibers, such as wrinkle-free polyster fibers, coloured fibers and fibers with immobilized enzymes, are examined. In addition, an outline about fiber modification genes, such as hormone and cellulose genes, is provided. Finally, the socio-economic impact of such development on the cotton industry in developing countries is discussed.
Address and Contact Information Genetic Engineering & Biotechnology Division, National Research Center, Cairo, Egypt
[Rozmiar: 1332 bajtów]