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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M. Pintilie et al.
2
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).
3
241
Enzyme activity in plants treated with magnetic liquid
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.
250
200
u.c./g/
min 150
100
50
0
-20
30
0
20
80
MF (ml/l)
40
60
80 100
130
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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4
2.5
mg/100 g
2
1.5
1
0.5
0
1
2
0
20
3 (ml/l)
4
MF
40
60
5
6
80
100
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).
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
1
2
3
4
5
6
MF (ml/l)
0
20
40
60
80
Fig. 4 – The chlorophyll a/chlorophyll b ratio versus magnetic fluid (MF).
5
Enzyme activity in plants treated with magnetic liquid
243
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.
35
30
25
mg/
cm 20
15
10
5
0
0
50
100
150
MF (ml/l)
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 )
1 80
1 60
1 40
1 20
1 00
y = -6 9 48 ,2 x + 36 2 ,6 3
R = 0 , 88
80
60
0, 0 2
0 ,0 25
0 ,0 3
0 ,0 3 5
x -m a ss/l e n g th (g / cm )
Fig. 6 – The correlation of catalase activity and the mass per length unit.
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M. Pintilie et al.
6
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.
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