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od 2020-09-20

Dr Tomasz Zalewski  | 1999-10 <> 2007-12

Doktorant

   CNBM UAM   

  0000-0002-6555-2450     15069712100  
Publikacje           Doktorzy      Magistrowie           Seminaria


16.

Kristinaityte K., Zalewski T., Kempka M., Sakirzanovas S., Baziulyte-Paulaviciene D., Jurga S., Rotomskis R., Valeviciene N.R.

Spin-lattice relaxation and diffusion processes in aqueous solutions of gadolinium-based upconverting nanoparticles at different magnetic fields We investigated the influence of gadolinium (Gd)-based upconverting nanoparticles (UCNPs) on water spin-lattice relaxation (T-1) and diffusion at different magnetic field strengths (0.4T and 9.4T). Our findings show that smaller NPs (12nm compared to 19nm) were more favourable for proton relaxivity. We also demonstrate that using simplified Solomon-Bloembergen-Morgan (SBM) model we can associate two measured diffusion coefficients with processes occurring near the surface of UCNPs and in bulk water. Using the relationship between relaxation and diffusion, we can estimate not only the total impact of NPs on relaxation of water molecules, but also the impact on relaxation of local water molecules, directly connected to paramagnetic Gd3+ ions in NPs. Different magnetic field strengths did not alter the spin-lattice relaxivity of NPs. This suggests that Gd-based UCNPs could be developed into high-performance multimodal magnetic resonance imaging contrast agents working over a broad range of imaging field strengths used in clinical routine.

Applied Magnetic Resonance, 50(4) SI, 553-561 (2019)

DOI: 10.1007/s00723-018-1105-z   (Pobrane:  2020-12-28)

15.

Skupin-Mrugalska P., Sobotta Ł., Warowicka A., Wereszczyńska B., Zalewski T., Gierlich P., Jarek M., Nowaczyk G., Kempka M., Gapiński J., Jurga S., Mielcarek J.

Theranostic liposomes as a bimodal carrier for magnetic resonance imaging contrast agent and photosensitizer The present study is focused on the development of liposomes bearing gadolinium chelate (GdLip) providing two functionalities for magnetic resonance imaging (MRI) and photodynamic therapy of cancer. A lipid derivative of gadolinium(III) diethylenetriamine pentaacetic acid salt (GdDTPA1) was inserted in the liposomal membrane and served as MRI contrast agent whereas a zinc phthalocyanine (ZnPc) was used as a model photosensitizer. In addition to conventional liposomes, pegylated lipids were used for the preparation of "stealth" liposomes. The characterization of different GdLip formulations involved evaluation of the liposomes size by nanoparticle tracking analysis, thermal phase behavior by differential scanning calorimetry and ZnPc-mediated singlet oxygen production. Furthermore, relaxivity measurements were performed as well as cytotoxicity and photodynamic activity against cancerous and normal cell lines was studied. Size and thermal behavior were only slightly influenced by GdLip composition, however it distinctly affected singlet oxygen production of ZnPc-loaded GdLip. The quantum yields of singlet oxygen generation by zinc phthalocyanine incorporated in GdLip containing cationic or/and pegylated lipids were smaller than those obtained for non-pegylated carriers with l-alpha-phosphatidylglycerol. In general, all formulations of GdLip, irrespectively of composition, were characterized by relaxivities higher than those of commercially used contrast agents (e.g. Magnevist). NMR study has shown that the incorporation of ZnPc into the formulations of GdLip increases the relaxation parameters r1 and r2, compared to the values for the non-loaded vesicles. GdDTPA1 did not influence the photodynamic activity of ZnPc against HeLa cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Journal of Inorganic Biochemistry, 180, 1-14 (2018)

DOI: 10.1016/j.jinorgbio.2017.11.025   (Pobrane:  2018-03-20)

14.

Ivashchenko O., Gapiński J., Peplińska B., Przysiecka Ł.,Zalewski T., Nowaczyk G., Jarek M., Marcinkowska-Gapińska A., Jurga S.

Self-organizing silver and ultrasmall iron oxide nanoparticles prepared with ginger rhizome extract: Characterization, biomedical potential and microstructure analysis of hydrocolloids Multimodal nanoparticles (NPs) that may be used for therapies and diagnostics is the most promising trend for efficient therapy. We demonstrate that nanocomposite based on self-organizing silver and ultrasmall magnetic iron oxide NPs (MAg) produced in one-step synthesis revealed unique combination of fluorescence, bactericidal, fungicidal properties and have a potential as magnetic resonance imaging (MRI) contrast agent. Using the green chemistry approach, ginger (Zingiber officinale) rhizome extract was applied as capping agent for MAg synthesis, providing also additional fluorescent properties of NPs and inducing hydrocolloids structuring. The MAg were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive microanalysis (EDS), fluorescence microscopy, cryo-SEM, dynamic light scattering (DLS) techniques, Fourier transforminfrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopies. MAg dispersions in water and some biological media are very stable which is important for biomedical application. The existence of microstructure inMAg hydrocolloids was proved. The hierarchical character and high ordering of this microstructure were discovered and its level-by-level building blocks were investigated. The microstructure was found to be responsible for fluorescence emittance of MAg hydrocolloids. The properties as well as potential application of the MAg hydrocolloids is yet to be discovered. © 2017 Elsevier Ltd. All rights reserved.

Materials & Design, 133, 307-324 (2017)

DOI: 10.1016/j.matdes.2017.08.001   (Pobrane:  2018-03-20)

13.

Woźniak A., Grześkowiak B.F., Babayevska N., Zalewski T., Drobna M., Woźniak-Budych M., Wiweger M., Słomski R., Jurga S.

ZnO@Gd2O3 core/shell nanoparticles for biomedical applications: Physicochemical, in vitro and in vivo characterization The chemical composition of nanoparticles (NPs) may be so designed as to provide measurability for numerous imaging techniques in order to achieve synergistic advantages. Innovative and unique structure of the core/shell ZnO@Gd2O3 NPs possesses luminescent and magnetic properties, and is expected that they will become a new generation of contrast agents for Magnetic Resonance Imaging (MRI) and nanocarriers for theranostics. Thus, by surface biofunctionalization, it is possible to indicate particular nanoparticle compositions which provide efficient imaging, targeted drug delivery, and biocompatibility. Novel ZnO@Gd2O3 NPs were synthesized and biofunctionalized by folic acid (FA) and doxorubicin (Doxo) to provide target and anticancer functions. Physicochemical analyses of the nanoparticles were performed. The biological study included a cytotoxicity in vitro, cellular distribution evaluation, as well as toxicity analyses, performed for the first time, on the in vivo zebrafish (Danio rerio) model. Nanoparticles were found to be effective double-function biomarkers (MRI T-2 contrast agents, fluorescent imaging). The biological study showed that ZnO@Gd2O3 and ZnO@Gd2O3@OA-polySi@FA NPs are biocompatible in a particular concentration ranges. Conjugation with folic acid and/or doxorubicin resulted in effective drug delivery targeting. The in vivo results described the toxicology profile toward the zebrafish embryo/larvae, including new data concerning the survival, hatching ratio, and developmental malformations. © 2017 Elsevier B.V. All rights reserved.

Materials Science & Engineering C - Materials for Biological Applications, 80, 603-615 (2017)

DOI: 10.1016/j.msec.2017.07.009   (Pobrane:  2018-03-20)

12.

Babayevska N., Florczak P., Woźniak-Budych M., Jarek M., Nowaczyk G., Zalewski T., Jurga S.

Functionalized multimodal ZnO@Gd2O3 nanosystems to use as perspective contrast agent for MRI The main aim of this research was the synthesis of the multimodal hybrid ZnO@Gd2O3 nanostructures as prospective contrast agent for Magnetic Resonance Imaging (MRI) for bio-medical applications. The nanoparticles surface was functionalized by organosilicon compounds (OSC) then, by folic acid (FA) as targeting agent and doxorubicin (Dox) as chemotherapeutic agent. Doxorubicin and folic acid were attached to the nanoparticles surface by amino groups as well as due to attractive physical interactions. The morphology and crystallography of the nanostructures were studied by HRTEM and SAXS techniques. After ZnO nanoparticles surface modification by Gd3+ and annealing at 900 degrees C, ZnO@Gd2O3 nanostructures are polydispersed with size 30-100 nm. NMR (Nuclear Magnetic Resonance) studies of ZnO@Gd2O3 were performed on fractionated particles with size up to 50 nm. Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, zeta-potential measurements and energy dispersive X-ray analysis (EDX) showed that functional groups have been effectively bonded onto the nanoparticles surface. The high adsorption capacity of folic acid (up to 20%) and doxorubicin (up to 40%) on nanoparticles was reached upon 15 min of adsorption process in a temperature-dependent manner.

Applied Surface Science, 404, 129-137 (2017)

DOI: 10.1016/j.apsusc.2017.01.274

11.

Woźniak A., Noculak A., Gapiński J., Kociołek D., Boś-Liedke A., Zalewski T., Grześkowiak B.F., Kołodziejczak A., Jurga S., Bański M., Misiewicz J., Podhorodecki A.

Cytotoxicity and imaging studies of beta-NaGdF4:Yb3+Er3+@PEG-Mo nanorods Multimodal imaging based on nanostructures has become a subject of interest for numerous biomedical laboratories. The main focus was placed on applying nanocrystals for the purpose of two types of clinical imaging (contrast and fluorescent agents) due to their excellent luminescence and/or paramagnetic properties. Such systems should also be characterized by low toxicity and high cellular uptake efficiency. Since bare rare earth fluoride nanocrystals influence the cell membrane integrity, it is expected that their coatings will improve biocompatibility profile, as well as increase hydrophilicity, dispersion and chemical stability. Hence, by synthesis of beta-NaGdF4:Yb3+Er3+ nanorods (NRs) coated with noncovalently bounded polyethylene glycol monooleate (PEG-Mo), it should be possible to obtain multimodal imaging biomarkers meeting established criteria. Synthesis of beta-NaGdF4:Yb3+Er3+@PEG-Mo NRs was performed by the co-precipitation method. These nanostructures were characterized in terms of their size, morphology, zeta potential, magnetic and optical properties as well as their cytotoxicity profile and cellular internalization was evaluated. It was shown that the shape and size of nanocrystals, namely 20 nm nanorods, present generally accepted parameters for biomedical purpose. Ligand attraction of PEG-Mo 860 resulted in the encapsulation of oleic acid coated NRs and formation of hydrophilic bilayer. Superparamagnetic and luminescence properties were highly efficient. Cytotoxic profiles of normal and cancer cell lines were low and determined by dose and time. Cellular uptake was confirmed by the presence of upconversion luminescence in cell interior. These findings are showing multimodal imaging properties of rod shaped beta-NaGdF4:Yb3+Er3+@PEG-Mo NRs which may be useful in some biomedical applications.

RSC Advances, 6(98), 95633-95643 (2016)

DOI: 10.1039/c6ra20415e   (Pobrane:  2018-04-04)

10.

Baranowska-Korczyc A., Jasiurkowska-Delaporte M., Maciejewska B.M., Warowicka A., Coy L.E., Zalewski T., Kozioł K.K., Jurga S.

PEG-MWCNT/Fe hybrids as multi-modal contrastagents for MRI and optical imaging This study examines the use of oxidized multi-walled carbon nanotube/iron (O-MWCNT/Fe) nanohybrids modified with polyethylene glycol (PEG) as multifunctional cellular imaging agents for magnetic resonance imaging (MRI) and fluorescence microscopy. The PEGylated MWCNTs with embedded iron particles were investigated as T2-weighted contrast agents for MRI. The number of PEG molecules attached to the MWCNT surface was calculated. The PEG-MWCNT/Fe complex was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and Raman spectroscopies. Covalent surface modification of the MWCNTs improves their solubility and enables the attachment of further biomolecules to their surface. The PEGylated nanostructures were labeled with the MDC organic dye and internalized inside HeLa cells for cellular imaging. Additionally, the minima cytotoxic effect of PEGylated complexes in comparison to non-PEGylated samples was measured Rusing the WST-1 test and an In Cell Analyzer. A confocal microscopy study of the organelle morphology also confi rmed that the HeLa cell morphology was unchanged after treatment with PEGylated MWCs.

RSC Advances, 6(55), 49891-49902 (2016)

DOI: 10.1039/c6ra09191a   (Pobrane:  2018-04-04)

9.

Maciejewska B.M., Warowicka A., Baranowska-Korczyc A., Zaleski K., Zalewski T., Kozioł K.K., Jurga S.

Magnetic and hydrophilic MWCNT/Fe composites as potential T-2-weighted MRI contrast agents In this work, functionalized Multiwall Carbon Nanotubes of specified length and containing well-defined iron particles (O-MWCNT/Fe) were prepared. A significant enhancement in contrast in Magnetic Resonance Imaging was found for the investigated composites. The magnetic characterization revealed the ferromagnetic nature of iron particles embedded within O-MWCNTs. The enhancement of the H-1 spin-spin relaxation time of MRI scans using hydrophilic O-MWCNT/Fe as potential contrast agents was estimated for selected dispersive media. Moreover, the cytotoxicity of the hybrids was studied in two cell lines, i.e. cancer cells (HeLa) and fibroblasts (GM07492). The intracellular impact of O-MWCNT/Fes in HeLa cells was observed after staining of selected organelles (nuclei and mitochondria). Significant changes in cell morphology were found for water soluble MWCNT/Fes with diameters above 30 nm. (C) 2015 Elsevier Ltd. All rights reserved.

Carbon, 94, 1012-1020 (2015)

DOI: 10.1016/j.carbon.2015.07.091

8.

Hałupka-Bryl M., Bednarowicz M., Dobosz B., Krzyminiewski R., Zalewski T., Wereszczyńska B., Nowaczyk G., Jarek M., Nagasaki Y.

Doxorubicin loaded PEG-b-poly(4-vinylbenzylphosphonate) coated magnetic iron oxide nanoparticles for targeted drug delivery Due to their unique physical properties, superparamagnetic iron oxide nanoparticles are increasingly used in medical applications. They are very useful carriers for delivering antitumor drugs in targeted cancer treatment. Magnetic nanoparticles with chemiotherapeutic were synthesized by coprecipitation method followed by coaling with biocompatible polymer. The aim of this work is to characterize physical and magnetic properties of synthesized nanoparicles. Characterization was carried out using EPR, HRTEM, X-ray diffraction, SQUID and NMR methods. The present findings show that synthesized nanosystem is promising tool for potential magnetic drug delivery.
(C) 2015 Elsevier B.V. All rights reserved

Journal of Magnetism and Magnetic Materials, 384, 320-327 (2015)

DOI: 10.1016/j.jmmm.2015.02.078   (Pobrane:  2020-10-23)

7.

Garnczarska M., Zalewski T., Wojtyła Ł.

A comparative study of water distribution and dehydrin protein localization in maturing pea seeds n this study, the distribution of water in pea seeds after harvesting at different seed stages was traced by magnetic resonance imaging (MRI). MRI visualized the process of water toss in maturing pea seeds. MR images showed local inhomogeneities of water distribution inside seeds. The intensity of the signal coming from water declined from the inner to the outer part of cotyledon tissue. This spatial inhomogeneity of water signals inside cotyledons may be correlated with the gradient of storage substances accumulation within cotyledons. Tissue localization of dehydrins showed the presence of dehydrin protein in the area of protovascular tissue of both the embryo axis and cotyledons. The temporal accumulation of two dehydrin proteins with molecular masses of 30 and 35 kDa correlated welt with seed desiccation. The pattern of dehydrin localization reflected the pattern of water distribution in the protovascular bundles region of maturing pea embryos, suggesting the involvement of these proteins in promoting water influx into the vascular bundles.
(C) 2008 Elsevier GmbH. All rights reserved.

Journal of Plant Physiology, 165(18), 1940-1946 (2008)

DOI: 10.1016/j.jplph.2008.04.016   (Pobrane:  2020-10-21)

6.

Zalewski T., Lubiatowski P., Jaroszewski J., Szcześniak E., Kuśmia S., Kruczyński J., Jurga S.

Scaffold-aided repair of articular cartilage studied by MRI Objective The objective of the study was to evaluate the ability of the noninvasive magnetic resonance techniques to monitor the scaffold-aided process of articular cartilage repair.
Materials and methods Defects of 4 mm in diameter and 3 mm in depth were created in right knees of 30 adolescent white New Zealand rabbits. Fourteen rabbits were implanted with poly(lactide-co-glycolic acid) (PLGA) scaffold trimmed to match the size and the shape of the defect (PLGA+ group). No procedure was applied to the remaining 16 animals (PLGA- group). Animals were sacrificed sequentially at 4, 12, and 24 weeks after the surgery and magnetic resonance T(2)-weighted images (400 MHz) of the dissected bone plugs at eight different echo times were taken to derive T(2) relaxation time. The images and the T(2) time dependencies versus the tissue depth were statistically analyzed. Histological results of bone plugs were evaluated using semiquantitative histological scales.
Results The results obtained for PLGA repair tissue were evaluated versus the PLGA- group and the healthy tissue harvested from the opposite knee (reference group), and compared with histological results (hematoxylin and eosin staining). The magnetic resonance images and T(2) relaxation time profiles taken 4 weeks after surgery for both the PLGA- and PLGA+ group did not reveal the tissue reconstruction. After 12 weeks of treatment T(2) time dependence indicates a slight reconstruction for PLGA+ group. The T(2) time dependence obtained for PLGA+ samples taken after 24 weeks of treatment resembled the one observed for the healthy cartilage, indicating tissue reconstruction in the form of fibrous cartilage. The tissue reconstruction was not observed for PLGA-samples.
Conclusion The study revealed correlation between magnetic resonance and histology data, indicating the potential value of using MRI and spatial variation of T (2) as the noninvasive tools to evaluate the process of articular cartilage repair. It also suggested, that the PLGA scaffold-aided treatment could help to restore the proper architecture of collagen fibrils.

Magnetic Resonance Materials in Physics, Biology and Medicine, 21(3), 177-185 (2008)

DOI: 10.1007/s10334-008-0108-4   (Pobrane:  2020-10-21)

5.

Garnczarska M., Zalewski T., Kempka M.

Changes in water status and water distribution in maturing lupine seeds studied by MR imaging and NMR spectroscopy The changes in water distribution in maturing lupin (Lupinus Luteus L.) seeds were visualized with magnetic resonance imaging (MRI). MRI data showed local inhomogeneities of water distribution inside the seed. At the late seed-filling stage the most intense signal was detected in the seed coat and the outer parts of cotyledons in the hilum area, but during maturation drying the decline in MR image intensity was faster in the outer part of the seed than in the central part. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system in maturing lupin seeds. Three populations of protons found during seed maturation, each with a different magnetic environment causing a different relaxation rate, were correlated with three fractions of water (structural, intracellular, and extracellular) that were observed during seed germination. This study provides evidence that lupin seeds have similar states of the different water components with regard to seed moisture content at two distinct physiological stages, seed maturation and germination. The unique feature of maturing lupin seeds is the presence of the high H-1-NMR signal in areas corresponding to the vascular bundles. Tissue localization of dehydrins showed the presence of dehydrin protein in the area of vascular tissue. An anti-dehydrin antibody detected three polypeptides in lupin embryos with molecular masses of 73, 43 and 28 kDa, respectively. The temporal pattern of dehydrin protein accumulation correlates well with seed desiccation.

Journal of Experimental Botany, 58(14), 3961-3969 (2007)

DOI: 10.1093/jxb/erm250

4.

Lubiatowski P., Zalewski T., Gradys A., Kruczyński J., Jaroszewski J., Trzeciak T., Szcześniak E., Manikowski W.

Application of microscopic MR for evaluation of cartilage repair Magnetic resonance imaging is gold standard for noninvasive evaluation of articular cartilage damage and has been also used for monitoring cartilage repair. The aim of this study was to find correlation between histological microscopy and microscopic MR in evaluation of the repair of osteochondral defects in articular cartilage. Study was based animal model (rabbit). The cartilage repair process was evaluated histology and micro MR. Most of the defects were filled with fibrocartilage and fibrous tissue formed. Both methods were equally efficient to show repair tissue thickness, subchondral bone reconstruction and disintegration. Result of observation by both histological and MR microscopy and showed good correlation. Micro MR is promising evaluation tool for cartilage repair monitoring. Results of micro MR correlate well with standard microscopy.

Chirurgia Narządów Ruchu i Ortopedia Polska, 72(3), 193-9 (2007)

   (Pobrane:  2020-10-21)

3.

Garnczarska M., Zalewski T., Kempka M.

Water uptake and distribution in germinating lupine seeds studied by magnetic resonance imaging and NMR spectroscopy Magnetic resonance imaging (MRI) was used to study temporal and spatial water uptake and distribution in germinating lupine (Lupinus Luteus L.) seeds. During 24 h of imbibition, water was unevenly distributed within the seed and some anatomical parts were more hydrated than others. Water entered the seed through the hilum and micropyle. The embryonic axis was the first to show hydration followed by seed coat and later cotyledons. The changes in water status were characterized by NMR spectroscopy. Analyses of T-2 relaxation times revealed a three-component water proton system (structural, intracellular and extracellular water) in germinating lupine seeds. The data on the components of transverse relaxation time studies indicated the complex exchange processes taking place between water components inside lupine seed over first 2.5 h of hydration, with a distinguished increase in structural water and decrease in other components. This speaks in favor of the high water-absorbing capacity of lupine seeds as related to high protein content. Germination was accompanied by swelling of protein bodies and changes in the organization of stored reserves with gradual disappearance of protein from the cells.

Physiologia Plantarum, 130(1), 23-32 (2007)

DOI: 10.1111/j.1399-3054.2007.00883.x

2.

Garnczarska M., Zalewski T., Wojtyła Ł., Szukała J.

Poziom adenylanów i nukleotydów pirydynowych w rozwijających się i dojrzewających nasionach grochu (Pisum Sativum L. ) Zapotrzebowanie na energię zmienia się podczas rozwoju nasion, począwszy od wzrostu merystematycznego we wczesnych stadiach, aż po fazę magazynowania, charakteryzującą się wysoką aktywnością biosyntetyczną. Także aktywność oddechowa zarodków zmienia się zasadniczo podczas rozwoju nasion [KOLLÖFFEL, MATTHEWS 1983]. Ważnym wskaźnikiem statusu energetycznego tkanki jest poziom nukleotydów adenylowych i ich wzajemny stosunek. Stan energetyczny tkanki określa wartość tzw. ładunku energetycznego (adenylate energy charge - AEC). Opisuje on nasycenie układu adenylanów w bezwodnikowe wiązania fosforanowe. Innym ważnym źródłem energii, regulującym stan równowagi energetycznej i transport elektronów, jest zawartość nukleotydów pirydynowych. Celem pracy było określenie stanu metabolicznego zarodków izolowanych z rozwijających się i dojrzewających nasion grochu Pisum sativum na podstawie wyników oznaczeń ładunku energetycznego oraz poziomu nukleotydów adenylowych i pirydynowych. POZIOM ADENYLANÓW I NUKLEOTYDÓW PIRYDYNOWYCH W ROZWIJAJĄCYCH SIĘ I DOJRZEWAJĄCYCH NASIONACH GROCHU (Pisum sativum L.). Available from: http://www.researchgate.net/publication/236902532_POZIOM_ADENYLANW_I_NUKLEOTYDW_PIRYDYNOWYCH_W_ROZWIJAJCYCH_SI_I_DOJRZEWAJCYCH_NASIONACH_GROCHU_(Pisum_sativum_L.) [accessed Sep 15, 2015].

Zeszyty Problemowe Postępów Nauk Rolniczych, 522, 485-491 (2007)

1.

Wojtyła L., Garnczarska M., Zalewski T., Bednarski W., Ratajczak L., Jurga S.

A comparative study of water distribution, free radical production and activation of antioxidative metabolism in germinating pea seeds The aim of this study was to investigate whether there is a relationship between hydration of the embryo axes and cotyledons and the resumption of the oxidative metabolism in both organs of germinating seeds of pea (Pisum sativum L. cv. Piast). Nuclear magnetic resonance (H-1-NMR) spectroscopy and imaging were used to study temporal and spatial water uptake and distribution in pea seeds. The observations revealed that water penetrates into the seed through the hilum, micropyle and embryo axes, and cotyledons hydrate to different extents. Thus, inhomogeneous water distribution may influence the resumption of oxidative metabolism. Electron paramagnetic resonance (EPR) measurements showed that seed germination was accompanied by the generation of free radicals with g(1) and g(2) values of 2.0032 and 2.0052, respectively. The values of spectroscopic splitting coefficients suggest that they are quinone radicals. The highest content of free radicals was observed in embryo axes immediately after emergence of the radicle. Glutathione content decreased during the entire germination period in both embryo axes and cotyledons. A different profile was observed for ascorbate, with significant increases in embryo axes, coinciding with radicle protrusion. Etectrophoretic analysis showed that superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), dehydroascorbate reductase (DHAR, EC 1.8.5.1)and glutathione reductase (GR, EC 1.6.4.2) were present in dry seeds and were activated later during germination, especially in embryo axes. The presence of all antioxidative enzymes as well as low molecular antioxidants in dry seeds allowed the antioxidative machinery to be active as soon as the enzymes were reactivated by seed imbibition. The observed changes in free radical levels, antioxidant contents and enzymatic activities in embryo axes and cotyledons appear to be more closely related to metabotic and developmental processes associated with preparation for germination, and do not correspond directly to the hydration of the tissues.
(C) 2006 Elsevier GmbH. All rights reserved.

Journal of Plant Physiology, 163(12), 1207-1220 (2006)

DOI: 10.1016/j.jplph.2006.06.014   (Pobrane:  2020-10-21)

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