Different methods of essential oil extraction are briefly described and the advantages and disadvantages are discussed. Trends in essential oil publications show that interest in essential oil research has risen markedly over the last twenty years. Publications on essential oil extraction methods show that environmentally friendly methods such as 'green technologies' developed recently such as supercritical CO2 fluid extraction and solid-phase microextraction are gaining in use. However, the simple and cost-effective method of hydrodistillation remains the primary, most used isolation method. Standards for essential oil production and quality control are briefly addressed. Some recent uses of essential oils in food preservation, as feed supplements, and as potential anticancer agents are described.

In a survey in Greece from 1987 to 2000 hepatotoxic cyanobacterial blooms were observed in 9 out of 33 freshwaters. Microcystins (MCYSTs) were detected by HPLC in 7 of these lakes, and the total MCYST concentration per scum dry weight ranged from 50.3 to 1638 +/- 464 mug g(-1). Cyanobacterial genera (Microcystis, Anabaena, Anabaenopsis, Aphanizomenon, Cylindrospermopsis) with known toxin producing taxa were present in 31 freshwaters. From our data and a review of the literature, it would appear that Mediterranean countries are more likely 1) to have toxic cyanobacterial blooms consisting of Microcystis spp. and 2) to have higher intracellular MCYST concentrations. A case study in Lake Kastoria is used to highlight seasonal patterns of cyanobacterial and MCYST-LR occurrence and to assess cyanotoxin risk. Cyanobacterial biovolume was high (> 11 muL L-1) throughout the year and was in excess of Guidance Level 2 (10 muL L-1) proposed by WHO for recreational waters and Alert Level 2 for drinking water. Further, surface water samples from April to November exceeded Guidance Level 3, with the potential for acute cyanobacterial poisoning. Intracellular MCYST-LR concentrations (max 3186 mug L-1) exceeded the WHO guideline for drinking water (1 mug L-1) from September to November with a high risk of adverse health effects. Preliminary evidence indicates that in 3 lakes microcystins are accumulated in some aquatic organisms. Generally, a high risk level can be deduced from the data for the Mediterranean region.

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.

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.

Several interelemental relationships have been examined in field-cultivated wheat (Triticum aestivum L. cv Vergina) growing on naturally enriched copper (Cu) soils. Mean soil Cu concentration per site ranged from 103-394 mu g.g(-1) dry weight (DW). Interrelationships between Cu, iron (Fe), calcium (Ca), potassium (K), zinc (Zn), lead (Pb), and magnesium (Mg) concentrations in the soil and plant tissue (roots, stems, and leaves) were examined using Principle Components Analysis. Soil samples were clustered according to collection site and were primarily differentiated according to their Cu concentrations. Soil Cu concentrations were positively correlated with Zn, Ca, Fe, and K in the soil, with Cu, K, and Ca in the roots, and Cu and Fe in the leaves and negatively correlated with Fe in the roots. The increase in Cu in the roots and leaves was positively correlated with increases in K and Ca in the roots and Fe and Ca in the leaves, but negatively with Fe in the roots. Increases in leaf Ca concentrations were correlated with increases in Mg and decreases in Zn concentrations in the leaf Plants growing in sail with high Cu concentration exhibited toxicity symptoms with reduced height, decreased total leaf area and lower chlorophyll concentrations. Photosynthesis expressed per unit leaf area was not affected by increasing Cu concentrations in the son or plant tissue.

The composition of essential oils obtained from Satureja horvatii subsp. macrophylla by hydrodistillation and micro-simultaneous distillation/extraction (SDE) were analyzed using GC and GC/MS for the first time. Thirty-nine constituents were found with percentage compositions >0.1% in both essential oils isolated. The major oil constituents were thymol (46.1–46.7%), p-cymene (14.3–15.5%) and γ-terpinene (7.1–8.2%). There were no major differences in the oil composition for constituents composing >0.8% between the two methods of oil isolation indicating that SDE is a suitable isolation procedure when small amounts of plant material are available. Key Word Index: Satureja horvatii subsp. macrophylla Labiataeessential oil compositionmicro-simultaneous distillation/extractionthymolp-cymene

Chlorophyll a fluorescence induction kinetic parameters of dark-adapted leaves of Sonchus spp. and Taraxacum spp. were found to be useful biomonitors of urban pollution arising from atmospheric and soil sources. A stress index factor (SIF) was generated using canonical variate analysis based on the variation in values of Fo, Fm and t|/2Using SIF as an index of pollution levels, a contour isostress map of Thessaloniki was constructed. The concentrations of Pb, Zn and Cu in the soil and the plant tissue were higher in areas of higher traffic density and air pollution. Multiple regression analysis showed that individual or combinations of the metal concentrations accounted significantly for at least 53% of the variation in SIF for both Taraxacum spp and Sonchus spp. Chlorophyll fluorescence is a simple, inexpensive, non-invasive and non-destructive method which can be used to routinely monitor urban pollution.

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.

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.

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- 1 0% 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.

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.

Some kinetic properties of ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase from Thiobacillus thyasiris, a marine, facultatively heterotrophic, sulphur-oxidizing bacterium and putative symbiont of Thyasira flexuosa (Montagu), a bivalve mussel, have been determined. The kinetic parameters for the CO2/Mg2+-activated enzyme were: K(m)(RuBP) 24.3-mu-M, K(m)(CO2) 125.5-mu-M, K(m)(02) 900-mu-M and K(m)(Mg2+) 1.53 mM. The low CO2 affinity suggests that T. thyasiris may possess a CO2-concentrating mechanism. RuBP oxygenase activity was inhibited by increasing CO2 concentration. Divalent metal ions essential for RuBP carboxylase activity; activity of the Mg2+-free enzyme could be restored by the addition of Mg2+, Mn2+ or Ca2+. The pH optimum was 7.8. The temperature optimum for RuBP carboxylase activity was 55-degrees-C, although the enzyme rapidly lost activity at this temperature. An Arrhenius plot was biphasic, with a break at 40-degrees-C. The activation energies were 55.5 x 10(3) J mol-1 and 32.9 x 10(3) J mol-1 over the temperature ranges 10-40-degrees-C and 40-55-degrees-C, respectively. Q10 was 2.12 for any 10-degrees-C increment between 10-40-degrees-C, and 1.47 between 40-55-degrees-C. RuBP carboxylase activity was stable at 35-degrees-C, the optimum growth temperature of T. thyasiris and at 7.5-degrees-C, the temperature of the habitat of Thyasira flexuosa, but the activity was 40% and 3.5%, respectively, of the potential activity at 55-degrees-C. RuBP carboxylase activity was stimulated by NaCl concentrations of up to 0.3 M, with a maximum (33%), occurring between 0.1 and 0.2 M-NaCl. At higher concentrations of NaCl (> 0.3 M) RuBP carboxylase activity was inhibited.

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.

Journal Article Bicarbonate Transport and Alkalization of the Medium by Four Species of Rhodophyta Get access C. M. COOK, C. M. COOK 3 1Botany Laboratory, Department of Biology, University of ThessalonikiGR-540 06 Thessaloniki, Greece 3To whom correspondence should be addressed. Search for other works by this author on: Oxford Academic PubMed Google Scholar T. LANARAS, T. LANARAS 1Botany Laboratory, Department of Biology, University of ThessalonikiGR-540 06 Thessaloniki, Greece Search for other works by this author on: Oxford Academic PubMed Google Scholar K. A. ROUBELAKIS-ANGELAKIS K. A. ROUBELAKIS-ANGELAKIS 2Department of Biology, University of Crete, IraklionCrete, Greece Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Experimental Botany, Volume 39, Issue 9, September 1988, Pages 1185–1198, https://doi.org/10.1093/jxb/39.9.1185 Published: 01 September 1988 Article history Received: 17 February 1988 Published: 01 September 1988

AbstractSome characteristics of photosynthetic inorganic carbon uptake byPalmaria palmata, a marine red macroalga, have been measured under physiological conditions in artificial seawater. The apparent affinity of thallus for CO2[K1/2(CO2)] at pH 8.0 and 15°C was 21.4±3.0mmol m−3CO2under air, and 25.7±70mmol m−3CO2under N2. The corresponding values ofVmaxwere 2.98 ± 0.42 and 3.65±0.87 mmol O2evolved g Chr−1s−l. The apparent Km(CO2) of isolated ribulose bisphosphate carboxylase was determined at pH 8.0 and 30 °C to be 30.2 mmol m−3CO2, and the corresponding value of Vmaxwas 19.67 μniol CO2g protein−1s−1. The CO2compensation points of the thallus were measured in artificial seawater at pH 8.0 under air and N2, using a gas‐chromatographic method. The values were relatively low, rising from 10 cm3m−3at 15°C, to 35 cm3m−3at 25°C, but were not affected by the O2concentration. The lack of an effect of O2on photosynthesis and on compensation point indicates that there is little photorespiratory CO2loss in this macroalga. The high affinity of the thallus for CO2, and the low CO2compensation concentrations, are consistent with the occurrence of bicarbonate uptake in this alga.

Journal Article The Effect of External pH on the Apparent CO2 Affinity of Chlorella saccharophila Get access KATHARINA A. GEHL, KATHARINA A. GEHL Department of Biology, York University, DownsviewOntario M3J 1P3, Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar CATHERINE M. COOK, CATHERINE M. COOK Department of Biology, York University, DownsviewOntario M3J 1P3, Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar BRIAN COLMAN BRIAN COLMAN Department of Biology, York University, DownsviewOntario M3J 1P3, Canada To whom correspondence should be addressed. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Experimental Botany, Volume 38, Issue 7, July 1987, Pages 1203–1210, https://doi.org/10.1093/jxb/38.7.1203 Published: 01 July 1987 Article history Received: 04 November 1986 Published: 01 July 1987

Journal Article Evidence for Bicarbonate Transport in Species of Red and Brown Macrophytic Marine Algae Get access C. M. COOK, C. M. COOK Department of Biology, York University4700 Keele Street, Toronto, Ontario M3J IP3, Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar T. LANARAS, T. LANARAS Department of Biology, York University4700 Keele Street, Toronto, Ontario M3J IP3, Canada Search for other works by this author on: Oxford Academic PubMed Google Scholar B. COLMAN B. COLMAN 2 Department of Biology, York University4700 Keele Street, Toronto, Ontario M3J IP3, Canada 2 To whom correspondence should be addressed Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Experimental Botany, Volume 37, Issue 7, July 1986, Pages 977–984, https://doi.org/10.1093/jxb/37.7.977 Published: 01 July 1986 Article history Received: 29 November 1985 Published: 01 July 1986