BIOPHYSICS – MAGNETIC EFFECTS
ENZYME ACTIVITY IN PLANTS TREATED WITH MAGNETIC LIQUID* M. PINTILIE1, L. OPRICA2, M. SURLEAC1, C. DRAGUT IVAN1, D.E. CREANGA1, V. ARTENIE2 1
“Al.I. Cuza”, University, Faculty of Physics – Iasi, Romania, e-mail:
[email protected] 2 “Al.I. Cuza”, University, Faculty of Biology –Iasi, Romania Received December 21, 2004
The influence of an aqueous magnetic liquid in young plantlets was studied by means of catalase activity as well as by means of chlorophyll and carotene contents. Ferrofluid dilutions were ranging between 20 and 100 ml/l. Catalase activity was found enhanced in all ferrofluid treated samples denoting the enhance of hydrogen peroxide. Key words: ferrophase, siderophore, biosynthesis.
1. INTRODUCTION 1.1. THE FERROFLUIDS
The ferrofluids are magnetic colloids containing 5% ferrophase, 10% stabilizer (surfactant) and 85% carrier liquid (usually hydrocarbons or water). The ferrophase may be only a mixture of iron oxides or it may contain also other metal ions: Mn, Ni, etc. The main required feature is the stability, which is assured by small size particles and good surfactant sheet, able to diminish the magnetic attraction force tendency to form large agglomerates. The ferrophase particle is a mono-domain magnet; the surfactant molecules avoid the large aggregate and chain formation interacting either physically (by hydrogen bonds) or chemically (covalent bonds) with the iron oxides. For medical purposes the ferrophase need also to have small physical diameter in order to pass through the cell biomembranes and to reach various target tissues. The reported results regarding influence of ferrofluids upon the plant growth evidenced a positive influence in cereals, explained on the basis of iron importance in the vegetal organism [1-3]. The biosynthesis of siderophores (complex compounds of iron - chelates) was assumed to be stimulated by the iron from the magnetic fluid ferrophase. Bacterial siderophores are found to intermediate the plant siderophore formation [4-5]. *
Paper presented at the 5th International Balkan Workshop on Applied Physics, 5–7 July 2004, Constanţa, Romania. Rom. Journ. Phys., Vol. 51, Nos. 1–2, P. 239–244, Bucharest, 2006
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1.2. THE CATALASE
Catalase is a relatively common enzymatic protein, found in the vegetal as well as in the animal tissue. It decomposes the hydrogen peroxide, a toxic compound generated from various causes: irradiation, chemical agents, metabolic perturbations. The enzyme amount is controlled by the biosynthesis adjustment in the frame of cell complex biochemical processes. 2. MATERIAL AND METHOD
The ferrofluid (Fe2+ and Fe 3+ oxides, coated with citric acid and dispersed in water) was diluted in distilled water in concentrations of 20-40-60-80 and 100 ml/l. Maize (Zea mays) cariopsides having uniform genophond, have been treated with ferrofluid solutions for 14 days after germination. Each sample was compound of 50 caryopsides, all chosen from the same plant in order to diminish the putative genophond variations. Germination and development was accomplished on watered porous paper support in glass dishes. The growth was conducted in well controlled environmental conditions (temperature 240C, humidity 90% and illumination light/dark cycle 16h/8h) within an Angelantoni scientifica climatic room. Ferrofluid treatment was carried out with adequate solution volume adjusted upon the plant watering needs. The catalase activity was assayed by iodometric titration [6] while the chlorophyll and carotene content was spectrophotometrically measured din acetone extract following Meyer-Bertenrath method [7]. The spectrophotometer was a E-1009 Metrohm Herisau device. Plant length and mass have been supplementary measured with an accuracy of 0.1 cm and respectively 10-5 g. Five repetitions for every parameter measurement in every sample have been done. Statistic analysis was accomplished by means of average values and standard deviations. 3. RESULTS AND DISCUSSION
The results obtained for the catalase assay are given in Figures 2–3. It is visible that the enzyme activity was continuously enhanced to the enhance of ferrofluid concentration. The larger difference (around 30%) was obtained between the control sample (no magnetic fluid) and the ferrofluid sample corresponding to the concentration of 8 ml/l (Fig. 1). For the concentration of 100 ml/l a slight diminution of catalase activity was recorded, so that the dependence of the catalase activity on the ferrofluid concentration seems to be a polynomial curve (not a straight line) (Fig. 2).
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These findings are suggesting that catalase biosynthesis was stimulated by the vegetal cell as response to the increased concentration of magnetic fluid. So, the organism of young cereal plant is able to react to the increased amount of hydrogen peroxide yielded by the ferrofluid influence.
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Fig. 1 – Catalase activity (units of catalase/g/min) versus magnetic fluid (MF) concentration (ml/l).
Fig.2 – The 3-D representation of the polynomial dependence of catalase activit (y) on theferrofluid concentration (x).
In Figures 3–5 the results obtained for the photosynthesis pigments are presented.
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Fig. 3 – The sum of chlorophylls and carotenes content for different concentrations of magnetic fluid.
The stimulatory effect for the 60 ml/l magnetic fluid concentration is evident (up to 75% increase in comparison to the control sample) while a diminution for the concentration of 100 ml/l (up to 25%) was noticed (Fig. 3). So, the iron supplementation in the plant culture medium seems to stimulate the biosynthesis of chlorophylls and carotenes for certain concentrations, probably following siderophore formation. Relatively high concentration of ferrofluid appears as inhibitory for the pigment accumulation. The photosynthesis ratio is given by the chlorophyll a/chlorophyll b values [7], as represented in Fig. 4. In contrast with the absolute values of the pigment content, the chlorophylls ratio presented a diminished value for the ferrofluid concentrations of 60 ml/l with an increasing tendency as shown by the values corresponding to 40 and 100 ml/l. This finding is suggesting that the biosynthesis of chlorophyll a (that actually catalyses the solar energy conversion into chemical energy) is influenced differently in comparison to that of chlorophyll b (that is a secondary photosynthesis pigment as well as the carotenes).
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Fig. 4 – The chlorophyll a/chlorophyll b ratio versus magnetic fluid (MF).
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This is in agreement with the supposition that the chlorophyll ratio is the expression of the sensitivity to external factors (either physical or chemical) of the LHC II (light harvesting complex II) enzyme system from the tylacoidal membrane of plant chloroplasts [8]. The measurements of individual plant length and fresh substance mass led to the average results presented in Figure 5.
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Fig. 5 – The mass per length unit versus magnetic fluid concentration.
From Figure 5 is evident that the accumulation of plant fresh substance mass per unit of length is diminished when the ferrofluid concentration is enhancing. In the terms of LHC II system this can be interpreted as an inhibitory effect of the magnetic fluid on the biomass accumulation though chlorophyll ratio seems to be increased for certain ferrofluid concentrations. 2 00
y-ca tal as e (u . c. / g /m i n )
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y = -6 9 48 ,2 x + 36 2 ,6 3 R = 0 , 88
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Fig. 6 – The correlation of catalase activity and the mass per length unit.
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So, the activity from the LHC II system appears as perturbed by the ferrofluid supply and consequently, though the chlorophyll ratio is increased for certain ferrofluid concentration, the organic compound biosynthesis (controlled by the enzyme system from the chloroplast membranes) is lowered. An interesting linear correlation was obtained for catalase activity and the mass per length unit (Fig. 6). The intensification of catalase biosynthesis (meaning the enhance of the hydrogen peroxide level) as well as the perturbation of the enzymes responsible for the biomass accumulation are evidenced by this results denoting the inhibitory effect of the ferrofluid within the concentration range tested in the frame of this experiment. 4. CONCLUSIONS
We may conclude that the aqueous ferrofluid has influenced the enzymes involved in the young maize plants growth at least at the levels of two enzyme systems as the direct and indirect experimental evidences have shown. Catalase biosynthesis is stimulated as a consequence of peroxidation reaction intensification. The function of the enzyme systems involved in the photosynthetic conversion of solar radiation into chemical energy is disturbed at least at the level of the LHC II system. The main way the ferrofluid has affected the young plant organism might be the biosynthesis of siderophores on the basis of iron ions from the ferrophase particles. REFERENCES 1. P. Bossier, M. Hofte, W. Verstraete, Ecological significance of siderophores in soil. In: Marshall, K. C. (ed.), Advances in Microbial Ecology. Plenum Press, New York, pp. 385–413, 1988. 2. C.J. Carrano, K. N. Raymond, Coroordination chemistry of microbial iron transport compounds 10. Characterization of the complexes of rhodoturulic acid, a dihydroxamate siderophore, J. Amer. Chem.Soc.100, 5371–5374, 1978. 3. M. Shenker, T.W.-M. Fan, D.E. Crowley, Phytosiderophores Influence on Cadmium Mobilization and Uptake by Wheat and Barley Plants, J. Environ. Qual., 30(6): 2091–2098, 2001. 4. L. A. de Weger, J J van Arendonk, K Recourt, G A Hofstad, P J Weisbeek, B. Lugtenberg, Siderophore-mediated uptake of Fe3+ by the plant growth-stimulating Pseudomonas putida strain WCS358 and by other rhizosphere microorganisms. J. Bacteriol., 170 (10): 4693–4698, 1988. 5. J.P. Adjimani, T. Emery, Iron uptake in Myclia sterilia EP-76, J. Bacteriol. 169, 3664–3668, 1987 6. V. Artenie, E. Tanase, Practicum de biochimie generala, Ed. Univ. Al. I. Cuza, Iasi, 1986. 7. M. Stirban, Procese primare in fotosinteza, Ed. Dacia, Cluj Napoca, 1981. 8. H.V. Westerhoff, T. Y. Tsong, P.B. Chock, Y.D. Chen, R.D. Astumian, How enzymes can capture and transmit free-energy from an oscillating electric field, Proceed. of the National Academy of Sciences of the United States of America, 83 (13), 4734–4738, 1986.
