C. M. Cook

The effect of Cu, Zn and Pb on the chlorophyll content of the lichens Cladonia convoluta and Cladonia rangiformis

Abstract It was hypothesised that Cu was responsible for the reduced chlorophyll content of lichens growing in mining areas in which Cu, Zn, and Pb were present in the soil. Therefore, the effect of Cu, Zn, and Pb, individually and in combination, on the respective thallus metal content of the lichens Cladonia convoluta and Cladonia rangiformis , and the subsequent effect on chlorophyll content, were examined. Increasing lichen Cu content (up to 1600 μg g −1 dry weight (DW)) had no effect on the total chlorophyll content of C. rangiformis , whereas in C. convoluta Cu concentrations exceeding 175 μg g − 1 DW caused a decrease in total chlorophyll content, which was 40% at 1560 μg Cu g −1 DW. Lichen Zn and Pb concentrations of up to 1050 and 3350 μg g −1 DW for C. convoluta and 1210 and 8500 μg g −1 DW for C. rangiformis , respectively, had no effect on the total chlorophyll content of either lichen. The chlorophyll a/b ratio was more sensitive to changes in lichen metal content. A marked decrease in the ratio of chlorophyll a/b, from 3.0 to 0.4 for C. convoluta and from 3.2 to 0.8 for C. rangiformis , occurred when the thallus Cu content exceeded 175 and 200 μg g −1 DW, respectively. Zn and Pb caused a 10–15% decrease of the ratio of chlorophyll a/b for C. convoluta at concentrations exceeding 140 and 20 μg g −1 DW, respectively. The chlorophyll a/b ratio of C. rangiformis was unaffected by increasing thallus Zn content, whereas an increase in thallus Pb content caused a slight increase in the chlorophyll a/b ratio. The decrease in the ratio of chlorophyll a/b with increasing lichen Cu content was caused by a decrease in chlorophyll a and an increase in chlorophyll b concentration in both lichens. The Cu effects on chlorophyll were reduced in the presence of Pb and Zn in both lichens, but to a lesser extent in C. rangiformis . Metal cations appeared to be ionically bound within the cell wall in an exchangeable form with binding affinities of Pb>Cu>Zn. It would appear that of these cations only Cu is taken up into the photobiont cells. Cu may interfere with the biosynthesis of chlorophyll or cause lipid peroxidation processes in the photosynthetic membranes.

Cyanobacterial blooms and water quality in Greek waterbodies

The cyanobacterial species composition of nine Greek waterbodies of different type and trophic status was examined during the warm period of the year (May–October). Cyanobacterial water blooms were observed in all waterbodies. Forty-six cyanobacterial taxa were identified, 11 of which are known to be toxic. Eighteen species are reported for the first time in these waterbodies, 8 of which are known to produce toxins. Toxin producing species were found in all of the waterbodies and were primarily dominant in bloom formations (e.g., Microcystis aeruginosa, Anabaena flos-aquae, Aphanizomenon flos-aquae and Cylindrospermopsis raciborskii). Cosmopolitan species (e.g., M. aeruginosa), pantropic (e.g., Anabaenopsis tanganyikae) and holarctic species (e.g., Anabaena flos-aquae) were encountered. Shallow, eutrophic waterbodies had blooms dominated by Microcystis species and were characterized by phytoplankton association M. Anabaena and Aphanizomenon species of association H were dominant in waterbodies with low dissolved inorganic nitrogen and thermal stratification in the summer. Total cyanobacterial biovolumes (CBV) ranged from 7 to 9,507 cm3 m−3 and were higher than Alert Level 2 and Guidance Level 2 (10 cm3 m−3; World Health Organization; WHO) in seven of the waterbodies. Chlorophyll a concentrations ranged from 6 to 90,000 mg m−3 and were higher than Alert Level 2 and Guidance Level 2 (50 mg m−3; WHO) in eight of the waterbodies. There is also an elevated risk of acute toxicosis (Guidance Level 3; WHO) in five waterbodies. Water of an undesirable quality, hazardous to humans and animals occurs in several Greek waterbodies.

Effects of copper on the growth, photosynthesis and nutrient concentrations of Phaseolus plants

Bean plants (Phaseolus vulgaris L. var. Zargana Kavala) were grown under conditions of increasing Cu concentrations in the growth medium (0.5-160.5 µM). Generally, the Cu concentrations between 0.5-1.5 µM were deficient, 1.5-10.5 µM were optimal, and 10.5-160.5 µM were toxic to plant growth. The Cu toxicity was associated with marked increases in plant tissue Cu concentrations. Under the Cu-deficient and optimal growth conditions, Cu was located primarily in the leaves. Under Cu toxicity, it was primarily sequestered in the roots. With increasing Cu in the growth medium, there was a positive correlation between Cu concentrations in the roots, stems and leaves, Ca in the roots, and K and Mg in the leaves. In contrast, Ca concentrations in the leaves and stems showed a negative correlation. The chlorophyll (Chl) concentration increased with increasing leaf Cu concentration, however, the Chl a/b ratio decreased. Since with an increasing leaf Cu concentration the leaf area decreased more markedly than the leaf dry mass, the net photosynthetic rate (PN) per leaf area increased and per dry mass decreased. The increase in PN per leaf area was almost entirely accounted for by the increase in Chl concentration. The initial Chl fluorescence (F0) increased with increasing leaf Cu concentration. The ratio of variable to maximum fluorescence (Fv/Fm) under Cu toxicity decreased. The half-time for the rise from F0 to Fm (t1/2) remained relatively unchanged with increasing leaf Cu concentration. Therefore the Cu-stress caused a small decrease in the efficiency of photosystem 2 photochemistry, but its primary effect was on growth.

Toxic cyanobacteria in greek freshwaters

Cyanobacterial scums, collected in 1987 from four Greek freshwater lakes, were examined for their toxicity to mice. Species ofMicrocystis, Oscillatoria, Anabaenopsis, andAnabaena were dominant in the samples. All samples tested had toxic effects on mice after intraperitoneal injection. The lethal dose (LD50) ranged from 40 to 1500 mg cyanobacterial dry weight kg−1 body weight and gross pathological signs of poisoning were characteristic of cyanobacterial hepatotoxins. The toxicities of the Greek cyanobacterial blooms were similar to those reported for blooms elsewhere in the world, shown to be responsible for the poisoning of wild and domestic animals.

COMPUTER MODELLING OF THE 3-DIMENSIONAL STRUCTURES OF THE CYANOBACTERIAL HEPATOTOXINS MICROCYSTIN-LR AND NODULARIN

The 3-dimensional structures of two cyanobacterial hepatotoxins microcystin-LR, a cyclic heptapeptide and nodularin, a cyclic pentapeptide, and the novel amino acid ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid) were constructed, and optimized using the CHEM-X molecular mechanics program. The peptide rings were planar and of rectangular shape. Optimized ADDA formed a U-shape and a difference in the orientation of ADDA with respect to the peptide ring of the two hepatotoxins was observed.

Comparison of chlorophyll fluorescence and some heavy metal concentrations in Sonchus spp. and Taraxacum spp. along an urban pollution gradient

Chlorophyll-α fluorescence induction kinetics of dark-adapted leaves of Sonchus spp. were measured in plants from areas of differing levels of urban pollution. Significant increases (∼ 200%) in the minimal (Fo) and maximal (Fm) fluorescence and decreases (∼ 50%) in the half-rise time from Fo to FM (t12) were observed for plants in areas of high pollution. A stress index factor (SIF) was derived based on the variation in these variables, using canonical variance analysis, which increased with increasing pollution levels. Significant linear relationhips between the fluorescence parameters of Sonchus spp. and Taraxacum spp. indicate that both plants exhibit the same changes in their chlorophyll fluorescence patterns in response to the pollution gradient. The ratio of Fm/Fo had a mean value of 5.2 ± 0.24 for Taraxacum spp. and 4.9 ± 0.23 Sonchus spp. No significant variation in the ratio of variable to maximal fluorescence (Fv/Fm) was observed (0.75–0.82) which indicated that the efficiency of the primary photochemistry of photosystem II was not directly affected by pollution level. The concentrations of Pb, Zn and Cu in the soil and plant tissue were higher in areas of higher traffic density and air pollution. Individual or combinations of the metal concentrations significantly accounted for at least 53% of the variation in SIF for both Taraxacum spp. and Sonchus spp.

Chlorophyll fluorescence and leaf chlorophyll content of bean leaves injured by spider mites (Acari: Tetranychidae)

The use of chlorophyll fluorescence as a method for detecting and monitoring plant stress arising from Tetranychus urticae (Koch) feeding injury was investigated. The effect of mite density (1–32 mites per 1.5 cm2 of leaf) and the duration of the feeding period (1–5 days) on the chlorophyll fluorescence parameters of bean (Phaseolus vulgaris) leaves were examined. Changes in chlorophyll fluorescence parameters were dependent both on mite density and duration of feeding. Decreases in Fo, the initial fluorescence and Fm, the maximum fluorescence led to a decrease in the ratio of variable to maximum fluorescence, Fv/Fm. The decrease in Fv/Fm is typical of the response of many plants to a wide range of environmental stresses and indicates a reduced efficiency of photosystem II (PSII) photochemistry. T1/2, which is proportional to the pool size of electron acceptors on the reducing side of PSII, was also reduced in response to mite-feeding injury. The leaf chlorophyll content decreased with increasing mite density and duration of feeding but did not appear to contribute to the decrease in Fv/Fm. Chlorophyll fluorescence is an effective method for detecting and monitoring stress in T. urticae-injured bean leaves.

Toxin extraction from an Anabaenopsis milleri — dominated bloom

This paper reports the presence of microcystin type toxins in extracts of a natural bloom of cyanobacteria composed predominantly of Anabaenopsis milleri Woronichin. The toxins have been extracted, purified and compared to microcystin-LR. The LD50 of A. milleri bloom material was 600-1500 mg lyophilized cells/kg body weight. Symptoms and pathological signs of poisoning in mice were characteristic of cyanobacterial hepatotoxins, with enlarged darkened livers with weights of 8-10% of the total body weight. Thin-layer chromatography of the extract resulted in one toxic band, which was separated from pigments and 280-nm absorbing compounds. The toxic fraction was further separated using reversed phase high performance liquid chromatography and one toxic band was recovered. This fraction yielded a single, toxic peak with a retention time of 11.3 min after high performance liquid chromatography. The absorption spectrum of the purified toxin had a maximum at 238-240 nm and was characteristic of cyanobacterial hepatotoxic peptides. Comparison of the chromatographic behaviour of the purified toxin with microcystin-LR on reversed phase and on internal surface reversed phase, high performance liquid chromatography indicated that an A. milleri bloom material toxin was a microcystin type toxin and it is highly likely that the purified toxin is microcystin-LR.

Differences Between The Inflorescence, Leaf And Stem Essential Oils Of Wild Mentha Pulegium Plants From Zakynthos, Greece

Abstract The composition of the inforescence (I), leaf (L) and stem (S) essential oils of wild Mentha pulegium plants from three populations (1–3) on the island of Zakynthos were examined. Pulegone (32.8 %, S1 to 75.8 %, I3) was the major constituent of all of the oils. The other main constituents were piperitenone (5.1 %, L3 to 35 %, I2), isomenthone (4.3 %, I2 to 28.6 %, L3) and piperitone (0.5 %, I3 to 5.2 %, L2). In total, C-3-oxygenated p-menthane compounds constituted from 73.0 % (S1) to 96.2 % (I2) of the oils. The piperitenone content of the inforescence oils was up to 2.4 (Loc 3) times higher than that of the leaf oils. Correspondingly, the isomenthone content of the leaf oils was up to 4.2 (Loc 2) times higher than that of the inforescence oils. The ratio of the isomenthone:piperitenone content of the oils (n=3) was markedly different for the inforescence (mean 0.31 ±SD 0.21), leaf (mean 2.91 ± SD 2.37) and stem (mean 1.12 ± SD 0.68) oils. The essential oil yields (mL/100g DW) were for the inforescences 3.1–5.0 %, leaves 3.1–4.0 %, stems <0.1–0.1% and whole plant (aerial parts) 2.4–3.9 % and are among the highest oil yields reported to date in Greece for M. pulegium.

Mentha Spicata Essential Oils Rich In 1,8-Cineole And 1,2-Epoxy-P-Menthane Derivatives From Zakynthos (Ionian Island, W Greece)

Abstract Wild Mentha spicata plants from 3 locations on the Island of Zakynthos had essential oil yields (mL/100g DW) ranging from 0.5–1.1 %. The main oil constituents were trans-piperitone oxide, piperitenone oxide and 1,8-cineole. On a whole plant basis (aerial parts) the trans-piperitone oxide content ranged from 1.4 % location (Loc 1) to 32.5% (Loc 3) and appeared to have an inverse relationship with the 1,8-cineole content which ranged from 10.8 % (Loc 3) to 37.9 % (Loc 1). 1,8-cineole was the major oil constituent (37.9 %) of M. spicata plants from Loc 1. The major constituent of the inflorescence oils was piperitenone oxide which ranged from 32.4 % (Loc 3) to 46.3 % of the oil (Loc 1). The major constituent of the leaf oils was 1,8-cineole (40.5 %) in plants from Loc 1 and trans-piperitone oxide in plants from Loc 2 (19.8 %) and Loc 3 (33.5 %). This is the first report for wild populations in Greece of a M. spicata oil in which 1,8-cineole is the major constituent. The observed variation in essential oil composition between locations and plant organs in July would not appear to be directly related to the climatic conditions.