T. Lanaras

AUTUMN ESSENTIAL OILS OF GREEK OREGANO

The essential oils of Origanum vulgare subsp. hirtum plants collected in late autumn from six localities of three distinct geographic areas of Greece were analysed by means of GC and GC-mass spectrometry. A high quantitative variation was found in the amount of the four main components; γ-terpinene ranged from 0.6 to 3.6% of the total essential oil, p-cymeme from 17.3 to 51.3%, thymol from 0.2 to 42.8%, and carvacrol from 1.7% to 69.6%. Plants collected from the northern part of Greece were rich in thymol (30.3–42.8% of total oil), whereas those from the southern part of the country were rich in carvacrol (57.4–69.6% of total oil). Furthermore, comparison with the essential oils obtained from plants collected from the same localities in mid-summer shows noticeable differences in the total oil content and the concentration of the four main oil components.

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.

Limnothrix redekei (Van Goor) Meffert (Cyanobacteria) Strains from Lake Kastoria, Greece Form a Separate Phylogenetic Group

Three strains of Limnothrix (Cyanobacteria) isolated from Lake Kastoria, Greece, were characterized based on their morphological features and 16S rRNA gene sequences. The Limnothrix isolates 007a, 165a, and 165c can morphologically be assigned to Limnothrix redekei (Van Goor) Meffert. The 16S rRNA gene of the Limnothrix strains showed a 99% similarity to the 16S rRNA gene of Planktothrix sp. FP1. Limnothrix redekei strains 165a, 165c, 007a and Planktothrix sp. FP1 formed a separate cluster in the cyanobacterial 16S rRNA gene tree. It was distinct from the Pseudanabaena cluster, which included the other Limnothrix strains isolated from northern temperate lakes. This is the first report on the phylogeny of L. redekei strains originating from a Mediterranean lake (southern Europe) and provides new data about the genus Limnothrix.

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.

Ribulose 1,5-bisphosphate carboxylase and polyhedral bodies of Chlorogloeopsis fritschii

Ribulose 1,5-bisphosphate (RuBP) carboxylase (EC 4.1.1.39) activity was approximately equally distributed between supernatant and pellet fractions produced by differential centrifugation of disrupted cells of Chlorogloeopsis fritschii. Low ionic strength buffer favoured the recovery of particulate RuBP carboxylase. Density gradient centrifugation of resuspended cell-free particulate material produced a single band of RuBP carboxylase activity, which was associated with the polyhedral body fraction, rather than with the thylakoids or other observable particles. Isolated polyhedral body stability was improved by density gradient centrifugation through gradients of Percoll plus sucrose in buffer, which yielded apparently intact polyhedral bodies. These were 100 to 150 nm in diameter and contained ring-shaped, 12 nm diameter particles. It is inferred that the C. fritschii polyhedral bodies are carboxysomes. Sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis of SDS-dissociated polyhedral bodies revealed 8 major polypeptides. The most abundant, with molecular weights of 52,000 and 13,000, correspond with the large and small subunits, respectively, of RuBP carboxylase.

Effects of enhanced UV-B radiation on Mentha spicata essential oils

Abstract In vitro propagated plantlets representing two distinct chemotypes of Mentha spicata, viz. plants producing essential oils rich in piperitone oxide and piperitenone oxide (chemotype I) and rich in carvone and dihydrocarvone (chemotype II), were grown in the field under ambient or ambient plus supplemental UV-B radiation, biologically equivalent to a 15% ozone depletion over Patras (38.3°N, 29.1°E), Greece. Enhanced UV-B radiation stimulated essential oil production in chemotype II substantially, while a similar, non-significant trend was observed in chemotype I. No effect was found on the qualitative composition of the essential oils, whereas the quantitative composition was slightly modified in chemotype I. This is the first investigation reporting an improved essential oil content under UV-B supplementation in aromatic plants under field conditions.

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.

Essential Oil Composition of Greek (Origanum vulgare ssp. hirtum) and Turkish (O. onites) Oregano: a Tool for Their Distinction

Abstract Aiming to find out if any distinction between the Greek (Origanum vulgare ssp. hirtum) and Turkish oregano (O. onites) essential oils exists, the composition of six wild Greek populations of the former and four of the latter taxon were analyzed by means of GC and GC/MS. A PCA analysis showed that Turkish oregano oils had higher amounts of sabinene, myrcene, γ-terpinene, borneol and carvacrol, and Greek oregano oils had higher p-cymene content. The latter were further divided into two subgroups, distinguished respectively by their thymol and carvacrol content. A comparison of our results with the published information showed that p-cymene percentages>14% and/or thymol>6% is found only in Greek oregano, while borneol content>2% is found only in Turkish oregano oils.

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.