Influence of linoleic acid on growth, oxidative stress and photosynthesis of the cyanobacterium Cylindrospermopsis raciborskii

Figures & data

Table 1. JIP test parameters with explanations and formulae (Strasser & Strasser 1995) calculated using data extracted from the O-J-I-P fast fluorescence transient.

Parameters from the JIP test	Details
Quantum efficiencies or flux ratios or yields
ψ0 ≡ ET0/TR0 = (1 – VJ)	Probability (t = 0) that a trapped exciton moves an electron into the electron transport chain beyond QA^−
φE0 ≡ ET0/ABS = [1 – (F0/Fm)] • ψ0	Quantum yield of electron transport (t = 0)
φP0 ≡ TR0/ABS = [1 – (F0/Fm)]	Maximum quantum yield of primary photochemistry (t = 0)
Specific fluxes or specific activities
ABS/RC = M0 • (1/VJ) • (1/φP0)	Absorption flux per RC
DI0/RC = (ABS/RC) – (TR0/RC)	Dissipated energy flux per RC (t = 0)
Density of reaction centres
RC/CS0 = φP0 • (VJ/M0) • (ABS/CS0)	Absorption flux per CS (t = 0)
Performance indexes
PIABS = RC/ABS • [φP0/(1 – φP0)] • [ψ0/(1 – ψ0)]	Performance index on absorption basis

Figure 1. Parameters observed when Cylindrospermopsis raciborskii was exposed to 0, 0.1, 0.5, 1, 2 and 4 mg·L⁻¹ of linoleic acid for 48 h. A, Chlorophyll a concentration; B, mean growth rate (μ).

Error bars represent ± SD for triplicate treatments.

*Indicates a P value less than 0.05; **indicates a P value less than 0.01.

Figure 2. Rapid light curves of Cylindrospermopsis raciborskii exposed to 0, 0.1, 0.5, 1, 2 and 4 mg L⁻¹ of linoleic acid for 48 h. Values shown are the means of three replicates ± SD.

Table 2. Changes in photosynthetic parameters following different concentration treatments of linoleic acid in C. raciborskii.

Linoleic acid concentration (mg L^−1 )	α	ETRmax	NPQ	Fv/Fm
0	0.173 ± 0.006	88.033 ± 5.301	0.019 ± 0.008	0.119 ± 0.008
0.1	0.178 ± 0.006	91.267 ± 3.180	0.012 ± 0.002	0.102 ± 0.012
0.5	0.171 ± 0.002	89.367 ± 0.524	0.040 ± 0.014	0.111 ± 0.017
1	0.023 ± 0.003**	9.067 ± 1.452**	0.052 ± 0.003*	0.060 ± 0.003**
2	0.010 ± 0.002**	1.867 ± 0.437**	0.088 ± 0.018**	0.019 ± 0.001**
4	0.008 ± 0.001**	4.200 ± 2.200**	0.094 ± 0.007**	0.028 ± 0.007**

Values shown are the means of three replicates ± SD.

*In the same column indicates significant differences (P < 0.05).

**In the same column indicates extremely significant differences (P < 0.01).

Figure 3. Relative variable fluorescence (OJIP transient curve) of Cylindrospermopsis raciborskii after 48 h of incubation with 0, 0.1, 0.5, 1, 2 and 4 mg L⁻¹ of linoleic acid.

Figure 4. Changes in the JIP test parameters expressed as a percentage of the control when Cylindrospermopsis raciborskii was exposed to various concentrations of linoleic acid for 48 h. A, Absorption flux per RC (ABS/RC) and dissipated energy flux per RC (DI₀/RC); B, RC parameters (RC/CS₀), parameters related to Q_A reduction (φP₀ and φE₀) and performance index based on absorption (PI_ABS). For more information, see Table 1.

*Indicates a P value less than 0.05; **indicates a P value less than 0.01.

Figure 5. Parameters for Cylindrospermopsis raciborskii incubated with 0, 0.1, 0.5, 1, 2 and 4 mg L⁻¹ of linoleic acid for 48 h. A, Superoxide dismutase (SOD) activity; B, catalase (CAT) activity; C, malondialdehyde (MDA) concentration. Error bars represent ± SD for triplicate treatments.

*Indicates a P value less than 0.05; **indicates a P value less than 0.01.

Strasser RJ, Strasser BJ. 1995. Measuring fast fluorescence transients to address environmental questions: the JIP test. Photosynthesis: from Light to Biosphere. 5:977–980.

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