Biomedical subjects

Maria Filek

Publications and source records attributed to Maria Filek.

12 recordsLinked to original sources

PubMed2006

Electric and structural studies of hormone interaction with chloroplast envelope membranes isolated from vegetative and generative rape.

The electric and structural properties of envelope membranes of chloroplasts obtained from vegetative and generative plants of rape and the effect of hormone (IAA, GA(3) and zearalenone) treatment were determined by zeta potential and small-angle X-ray scattering (SAXS) methods. Chloroplasts were isolated from leaves cut off from the vegetative (before cooling) and generative apical parts of plants. The lipid composition of chloroplast envelope membranes were analyzed by chromatographic techniques. Envelopes from generative plants contained higher levels of digalactosyldiacylglycerol (DGDG) and smaller amounts of phospholipids (PLs) in comparison to those obtained from vegetative ones. Moreover, envelopes of generative plants were characterized by higher fractions of unsaturated fatty acids. The zeta potential changes caused by hormone treatment were higher for chloroplasts isolated from vegetative plants in comparison to chloroplasts isolated from generative ones. An especially strong effect was observed for chloroplasts treated with IAA. The thickness of bilayers of untreated chloroplasts from vegetative plants were larger by 0.4 nm when comparing to the thickness of layers obtained from generative ones. The effect of hormones (GA(3) and zearalenone) was detected only for vegetative chloroplasts. Both applied methods indicated differences in the properties of untreated and hormone-treated chloroplasts obtained from vegetative and generative plants.

Brassica napus↗

PubMed2005

Effect of indole-3-acetic acid on surface properties of the wheat plastid lipids.

Surface parameters of polar lipids extracted from winter wheat plastids were investigated by the Langmuir and X-ray differentiation scattering methods. Highly purified plastids were isolated from non-embryogenic (NE) and embryogenic (E) calli initiated from inflorescences. NE plastids contained more monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) and less phospholipids (PL) fraction than E plastids. Moreover, in E calli, unsaturated fatty acids were detected in a higher proportion than in NE for both MGDG and DGDG. No significant differences in fatty acids saturation of PL between NE and E objects were detected. Aqueous surface monolayers were prepared from separate lipids and from mixtures of glycolipids and PL. In the case of MGDG, isotherms showed specific shoulders, contrary to continuous isotherms obtained for other investigated lipids. On the base of pi-A isotherms, the surface parameters: limiting area (A(lim)) and collapse pressure (pi(coll)) were calculated. Indole-3-acetic acid (IAA) increased the A(lim) of all separated lipids about 4-10 angstrom2/mol. However, for NE lipid mixture, the effect of IAA was much smaller (about 2 angstroms2/mol) than for other objects (usually about 5 angstroms2/mol). X-ray experiments for liposomes, obtained from mixtures of glycolipids and PL of NE and E plastids, showed continuous scattering curves with maxima characteristic for lipid bilayer membranes. Calculations of distance distribution functions indicated that bilayer thickness was 41 and 38 angstroms for NE and E, respectively. IAA influence on membrane structures was detected especially in E liposomes and increased the distance between head groups by about 2 angstroms. It is suggested that changes occur during embryogenesis in specific structure of plastid membranes determined also the formation of domains, similar to that suggested for plasmalemma (Plant Sci. 165 (2003) 265). IAA treatment influenced the membrane structure, especially E plastids increasing distances between polar groups.

Cells, Cultured↗

PubMed2004

Influence of phytohormones on polar and hydrophobic parts of mixed phospholipid monolayers at water/air interface.

Surface parameters--the limiting area, collapse pressure, and compressibility modulus for monolayers of phospholipids containing a determined hydrophobic part (16:0) but different polar parts (PPL) and a determined polar part (PC) but different fatty acids (HPL), characteristic of nonembryogenic (NE) and embryogenic (E) winter wheat calli--were evaluated at 15 degrees C. These parameters were dependent on the kind of hydrophilic group and the size of the hydrophobic part of phospholipids. In the case of PPL, higher values of Alim and picoll were noticed for NE phospholipids. In the case of HPL, lower Alim and higher picoll were detected for NE than for E monolayers. All investigated phospholipid systems stimulated the adsorption of phytohormones from the water subphase. The influence of phytohormones of anionic (IAA, 2-4-D), cationic (kinetin, zeatin), and nonionic character (zearalenone) was examined. It appeared that the surface activity of phytohormones depended strongly on the kind of tissue from which the phospholipid mixture was extracted and, in a lesser degree, on their charge. In PPL systems with a determined hydrophobic part (16:0), no great differences in phytohormone influence on NE and E monolayers were observed (except of IAA). The greatest phytohormone influence on NE monolayers in HPL systems was related to the structure of the hydrophobic part of phospholipids. IAA, the most active (with the highest Alim values) among the phytohormones examined, influenced both HPL and PPL monolayers. This indicated the interactions of IAA with polar groups of phospholipids. Phytohormones also changed the monolayer stability against collapse process and the direction of changes depended on the kind of tissue (embryogenic or nonembryogenic).

Air↗

PubMed2004

Ethylene synthesis and auxin augmentation in pistil tissues are important for egg cell differentiation after pollination in maize.

The role of ethylene and auxin in stigma-to-ovule signalling was investigated in maize (Zea mays L.). Maturation of the egg cells in an ear was stimulated before actual fertilization by the application of fresh pollen grains or quartz sand to fully receptive stigmas. Ethylene emission by maize ears increased in response to those treatments. Silks and ovaries were involved in ethylene synthesis after pollen or sand was shed over the silks. The content of ethylene precursor [1-aminocyclopropane-1-carboxylic acid (ACC)] increased in both pistil parts soon after pollination. ACC rise was delayed by 4 h in the ovaries, and by 8 h in the silks after mock-pollination with sand. The auxin level increased rapidly in the silks and ovaries after pollination, and it was very high in the pollinated silks due to the high indole-3-acetic acid (IAA) content of pollen grains. IAA rise also appeared in the silks and ovaries after treatment with sand but it was delayed by 8 h. Application of ACC (10 microM) or IAA (6 microM) solutions to non-pollinated silks stimulated maturation of the egg cells. Moreover, the response of the egg cells to pollination was cancelled by l-alpha-(2-aminoethoxyvinyl)-glycine, alpha-aminoisobutyric acid or 2,3,5-triiodobenzoic acid applied to the silks before pollination. Thus ethylene synthesis and polar auxin transport in the silks pollinated with fresh pollen were necessary to evoke accelerated differentiation of the egg cells in maize ovules. Differences in pistil responses found between true- and mock-pollination suggest that signalling pathways are at least partially different for the reception of pollen grains and sand crystals on maize stigma.

Amino Acids, Cyclic↗

PubMed2003

Variation and action potentials evoked by thermal stimuli accompany enhancement of ethylene emission in distant non-stimulated leaves of Vicia faba minor seedlings.

Electrical activity (action and variation potentials) and ethylene emission were measured in thermally stimulated Vicia faba minor seedlings. It was determined that variation potential with or without super-imposed action potentials was generated and propagated basipetally in response to scorching of the upper leaf. In stimulated plants the level of ethylene production measured in lower, non stimulated leaf was significantly higher than that in the control plants and the difference correlated with the amplitude of the electrical response. Neither variation nor action potential was recorded when ethylene was injected to the chamber covering the experimental leaf. The level of ethylene emission showed clear circadian rhythm when measured at photoperiod 16:8 (LD) or at constant light (LL). It is concluded that the sequence of ion fluxes registered as an electrical response of a plant to the thermal stimulus is a signal evoking an enhancement of ethylene emission.

Action Potentials↗

PubMed2003

The influence of phytohormones on the properties of wheat phospholipid monolayers at the water-air interface.

The surface behaviour of monolayers of wheat phospholipids in the presence of phytohormones introduced into the water phase was studied using Langmuir's method. The phospholipids were extracted from the plasmalemma of non-embryogenic (NE) and embryogenic (E) calli initiated from two types of explant: immature inflorescences (inf) and embryos (emb). The surface properties were investigated in model systems of monolayers of mixed phospholipids with: 1) natural amphiphile composition (PL); 2) a determined hydrophobic part (16:0) and the natural percentage composition of the hydrophilic part (PPL); and 3) a determined hydrophilic part (PC) and the natural percentage composition of the hydrophobic part (HPL). The lower limit values of the molecular area (A(lim)) were observed for NE rather than for E monolayers in all the investigated systems (PL, PPL and HPL). The collapse pressure (pi(coll)) of the monolayer decreased in the order PPL>PL>HPL, indicating the high stability of monolayers containing saturated hydrocarbon chains. The injection of non-surface-active phytohormones into the water subphase and the subsequent formation of natural and also artificial phospholipid monolayers of E and NE causes a decrease in monolayer stability against collapse and molecular close packing. As a result of their amphipathic (hydrophilic-hydrophobic) structure, the surface properties of E phospholipids are probably optimal for these systems. The decreasing stability of the NE monolayer caused by the presence of the phytohormone seems to be advantageous in terms of membrane preparation for the differentiation process. All the investigated lipid monolayers (highly) stimulated the adsorption of indole-3-acetic acid (to the highest extent/degree) (among the examined phytohormones) from the subphase. Zearalenone had a significant influence on the surface properties of NE PPL and NE HPL monolayers. This may be connected with the ability of this phytohormone to affect the non-embryogenic structure of wheat. An anomalous temperature effect was observed in the presence of indole-3-acetic acid (IAA) in the bulk; phospholipid monolayers of embryogenic calli induced from embryos (E emb) when the temperature decreased from 25 to 15 degrees C. This phenomenon is ascribed to the dehydration of the polar groups in the monolayer

Cells, Cultured↗

PubMedDate not supplied

The influence of phytohormones on zeta potential and electrokinetic charges of winter wheat cells.

The zeta potential measurements of protoplasts obtained from winter wheat cell culture and phospholipid liposomes were performed to determine the electrokinetic charge in a medium containing various phytohormones (kinetin, 2,4-D and zearalenone) in absence and in presence of 2 x 10(-5) MCa2+. Calli were induced from immature inflorescences (inf) and embryos (emb) and cultured to obtain non-embryogenic (NE) and embryogenic (E) cell tissues. All investigated phytohormones indicate ability to adsorb to the negatively charged surfaces (latex, L88 - model negative adsorption site) both in water solutions and at the presence of mannitol and buffer (MES). In biological systems (protoplasts and liposomes - prepared from phospholipids of protoplasts) the electrokinetic charges were dependent on the phospholipid and protein composition of cells. The influence of protein groups on electrokinetic charge was calculated from charge values of protoplasts and liposomes, assuming additivity of surface charges. The comparison of calculated charges for protoplasts and liposomes indicate that 2,4-D is better adsorbed to the phospholipid and proteins of NE cells whereas kinetin is bound to the phospholipid and protein sites of E calli. This effect may be connected with embryogenesis process, where non-embryogenic culture of wheat requires 2,4-D in the medium, and embryogenic culture requires cytokinin rather. Zearalenone binding is especially dependent on the kind of explant.

Calcium↗

PubMedDate not supplied

Influence of temperature on phytohormone interactions with monolayers obtained from phospholipids of wheat calli.

The effect of temperatures (15 and 5 degrees C) on adsorption parameters of phytohormones at monolayers prepared from a mixture of phospholipids extracted from non-embryogenic (NE) and embryogenic (E) winter wheat calli initiated from inflorescences (inf) and embryos (emb) was studied. The surface parameter values, i.e. limiting area and collapse pressure, were determined using the Langmuir method. Phytohormones 2,4-dichlorophenoxyacetic acid (2,4-D), indole-3-acetic acid (IAA), kinetin, zeatin and zearalenone were investigated. The phytohormones, at a concentration of 0.2 microg/ml dissolved in water, were injected into the subphase. Phospholipids, at the concentration of 2 mg/ml, were spread at the water surface and the monolayer was compressed. The anomalous temperature effect was observed, especially, in non-embryogenic systems. In monolayers obtained from E phospholipids, the temperature effect was dependent on the kind of tissue from which the callus was initiated. Among all the examined phytohormones, the greatest changes (monolayer expansion) were found for IAA and zearalenone. However, this activity depended strongly on the kind of tissue from which the phospholipid mixture was extracted.

2,4-Dichlorophenoxyacetic Acid↗

PubMedDate not supplied

The influence of growth regulators on membrane permeability in cultures of winter wheat cells.

The effect of plant growth substances (IAA, 2,4-D, zeatin, kinetin, zearalenone) were studied on membrane properties of the cells of embryogenic (E) and non-embryogenic (NE) calli derived from immature inflorescences (inf) or embryos (emb) of winter wheat. Calli initiated from inflorescences show higher permeability. The ion leakage from cells of E calli was higher than from cells of NE calli. Growth regulators were used in concentrations of 2-30 mg/l (about 10-140 microM). All tested growth substances increased ion leakage from NE emb cells, IAA, zeatin and kinetin being most effective. In NE inf cells the effect of growth substances was similar as in NE emb, but much weaker. In E cells of both types (inf and emb) growth substances decreased ion leakage. Changes in the leakage of potassium and calcium ions were similar to those in total ion leakage. The uptake of labelled auxins (IAA and 2,4-D) was higher in NE cells (especially in NE inf) than in E cells. The endogenous level of IAA was higher in E cells than in NE cells and in inf cells than in emb cells. The importance of auxin in determining permeability of cell membranes is discussed.

Cell Division↗

PubMedDate not supplied

The effect of electric field on callus induction with rape hypocotyls.

The influence of electric field treatment on dedifferentiation and calli formation on rape hypocotyls was investigated. Segments, 10 mm long, of the upper part of rape (Brassica napus L., cv. Góczański) hypocotyls were stimulated by different combinations of voltage/time (1.5 V/120 h, 3 V/3 h, 10 V/15 min and 30 V/30 s) under in vitro conditions. With all electric field treatments, segments oriented with their apical part towards the cathode produced more calli as compared to control (non-treated with electric field). Under opposite orientation slight inhibition of callus growth was observed. As the strongest effect on callus growth was observed after treatment with 30 V/30 s, this electric field treatment was selected for following analyses: the incorporation of [14C]-2,4-D (2,4-dichlorophenoxyacetic acid) and [14C]-BAP (benzylaminopurine) from the culture medium, changes in ACC (1-aminocyclopropane-1-carboxylic acid) level and the redox activity in apical and bottom parts of hypocotyls during 18 d of culture. In contrast to changes in fresh weight, electric field treatment (30 V/30 s) stimulated a higher accumulation of 2,4-D and BAP in basal parts of hypocotyls than in apical ones. Moreover, orienting the apical part towards the cathode resulted in lower uptake of hormones as compared with the opposite orientation. The ACC concentration increased, especially in the basal parts of hypocotyls, independently on electric field application. However, the highest level was observed after electric field treatment with orientation of the apical part towards the anode. The distribution of oxidative substances (measured as the amount of ferric ions) between the apical and bottom part of hypocotyls was not changed when the apical parts were oriented towards the cathode. Under these conditions a decrease in apical and an increase in basal parts was observed during culture. Opposite orientation influenced the redistribution of oxidative substances from the first day of electric field treatment. Based on these results we suggest that electric field action can be connected with its influence on specific concentration of oxidative substances and hormone distribution in cells.

Brassica napus↗

PubMedDate not supplied

Does DNA methylation pattern mark generative development in winter rape?

In this paper we report on changes in DNA methylation pattern in rape apices and leaves during transition from vegetative to reproductive stage due to grafting and/or vernalization. Grafted plants of winter rape (Brassica napus L., var. "Górczański") (stock from vernalized, scion from non-vernalized plants) were used together with vernalized non-grafted plants. In addition, methylation status was determined also in spring rape (var. "Młochowski") grown under normal and low temperature. The methylation-sensitive amplification polymorphism (MSAP) method with EcoRI/MspI and EcoRII/HpaII restriction enzymes was employed. The majority (ca. 68%) of analyzed loci (566 in winter and 551 in spring rape) were monomorphic, i.e. did not undergo methylation. Both cultivars showed a similar degree of methylation. 188 loci in winter and 176 in spring cultivars expressed changes in the methylation pattern. All differentially amplified fragments resulted from either full methylation of an internal cytosine or from hemi-methylation of an external cytosine. A pair-wise comparison showed that a similar number of loci underwent development-related methylation changes in apices of the winter and spring rape. The majority (80%) of changes were demethylation events in generative (vernalized) apices of the winter cultivar. However, an increased number of demethylated loci was detected in vernalized apices in comparison with generative, non-vernalized ones. In apices of vegetative and generative grafted plants the same number of demethylation events was observed. Overall, 10 MSAP loci were detected that expressed methylation changes in vernalized apices only; among them 7 loci underwent demethylation after vernalization and remained methylated in both vegetative and generative non-vernalized stage. Only 1 locus was demethylated in generative non-vernalized apices. Thus, most of demethylation events can be ascribed to vernalization and not to the generative stage. In leaves of winter rape methylation and demethylation events occurred with similar frequency, while in the spring cultivar more demethylation events were detected. The results show that during vernalization and transition to the generative stage different sets of genes are activated.

Base Sequence↗

PubMedDate not supplied

Changes of redox activity during the development of rape.

Redox activity was measured in vegetative and generative apical parts (5 mm of the stem) and youngest leaves of winter (cv. "G6rczański") and spring (cv. "Młochowski") rape. Both genotypes were cultured under the same growth conditions (17/15 degrees C day/night, 16 h photo-period), but winter rape was additionally vernalized (5/2 degrees C day/night, 56 days) in order to induce the generative development. The cyclic voltammetric method was used to measure the redox potential of samples in the presence of Fe3+ ions. Changes in the redox activity were compared with changes in riboflavin content and activities of antioxidative enzymes: superoxide dismutase (SOD) and catalase (CAT). The higher level of Fe3+ ions and riboflavin detected in generative apices and leaves of winter and spring varieties indicated that electrons (and their donors) were present at a lower level in these organs in comparison with the vegetative ones. On the contrary, SOD and CAT activity were lower in generative than in vegetative organs. This confirms changes in the redox balance and involvement of oxygen radicals in the generative development of rape plants. The similarity of the measured parameters between winter and spring varieties indicates that the observed changes are independent of the way of generative induction (vernalization). Riboflavin can serve as one of the electron carriers between other oxidation-reduction substances.

Brassica rapa↗