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Arthrospira (“Spirulina”) is the most used cyanobacterium in food supplementation. “Spirulina” products are considered as superfood due to their excellent nutritional content, although several studies have shown the toxic effects of short and long term “Spirulina” consumption. In this work, a total of 31 “Spirulina” products from different brands, available in Greece, were investigated for their cyanotoxin contamination. All samples were positive for microcystins (MCYSTs) (35.7–583.5 ng g−1 dry weight [dw]). Two samples were tested positive for cylindrospermopsins (CYNs) (221.4–351.8 ng g−1 dw). No saxitoxins (STXs) were found. According to guidelines, the MCYSTs concentrations did not exceed the tolerable daily intake (TDI) set for adults, but six products exceeded the TDI set for children and 23 exceeded the TDI set for infants. The CYNs did not surpass the TDI for adults, but both samples exceeded the TDI for children and infants. This study showed that the low cyanobacterial toxin concentrations occurring in commercial “Spirulina” supplements, do not pose obvious risks for adults’ consumption, however they pose health risks for children and infants after daily consumption. To protect consumers, regular monitoring of these toxins at all stages of “Spirulina” production is recommended.

Arterial hypertension is a risk factor for several pathologies, mainly including cardio-cerebrovascular diseases, which rank as leading causes of morbidity and mortality worldwide. Arterial hypertension also constitutes a fundamental component of the metabolic syndrome. Helicobacter pylori infection is one of the most common types of chronic infection globally and displays a plethora of both gastric and extragastric effects. Among other entities, Helicobacter pylori has been implicated in the pathogenesis of the metabolic syndrome. Within this review, we illustrate the current state-of-the-art evidence, which may link several components of the Helicobacter pylori-related metabolic syndrome, including non-alcoholic fatty liver disease and arterial hypertension. In particular, current knowledge of how Helicobacter pylori exerts its virulence through dietary, inflammatory and metabolic pathways will be discussed. Although there is still no causative link between these entities, the emerging evidence from both basic and clinical research supports the proposal that several components of the Helicobacter pylori infection-related metabolic syndrome present an important risk factor in the development of arterial hypertension. The triad of Helicobacter pylori infection, the metabolic syndrome, and hypertension represents a crucial worldwide health problem on a pandemic scale with high morbidity and mortality, like COVID-19, thereby requiring awareness and appropriate management on a global scale.

Nonalcoholic fatty liver disease (NAFLD) was recently renamed to metabolic (dysfunction)-associated fatty liver disease (MAFLD) to better characterize its pathogenic origin. NAFLD represents, at least in western societies, a potential epidemic with raising prevalence. Its multifactorial pathogenesis is partially unraveled and till now there is no approved pharmacotherapy for NAFLD. A plethora of various choices are investigated in clinical trials, targeting an arsenal of different pathways and molecules. Since the mineralocorticoid receptor (MR) and renin-angiotensin-aldosterone system (RAAS) appear to be implicated in NAFLD, within this concise review, we focus on a rather classical and inexpensive pharmacological agent, spironolactone. We present the current lines of evidence of MR and RAAS-related preclinical models and human trials reporting an association with NAFLD. In conclusion, evidence about spironolactone of RAAS is commented, as potential future pharmacological management of NAFLD.

Introduction and objectives: In order to investigate food allergy’s prevalence, risk factors and eating behavior of children with relevant anamnesis, a study was performed in Cypriot primary schools.Patients: A specially composed questionnaire for self-reported adverse reactions to food, cre-ated in the context of the EuroPrevall study, was distributed in 13 representative primary schools across the country. Participants were sub-grouped into three groups; healthy (H), those with unconfirmed food hypersensitivity reactions (FA−) and children with a confirmed diagnosis by a physician IgE-mediated food allergy (FA+). Food habits, family health history and lifestyle factors were assessed and groups’ outcomes were compared with each other.Results: For the study, 202 questionnaires were completed and returned; 31 children (19 FA-and 12 FA+) reported an adverse food reaction. Significant risk factors for developing FA+ were being the first born or having siblings with asthma, attended a day nursery, but also maternal alcohol drinking during pregnancy, parental smoking and parental occupation in food processing or use of latex gloves. The presence of children in the kitchen during cooking showed a protective role. Dietary habits of FA+ children were significantly diminished in terms of variety and frequency of consumption in comparison to the rest, in which had a greater overlap. Conclusion: Further research is required for the interesting risk or protective factors revealing from the current investigation. The negative effect of food allergy in the dietary habits of food allergic children documented in the literature, is strongly supported herein.

The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or nonimpaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise. Another important aspect is to ensure that water quality assessment is comparable among the different Member States. In this context, the present paper offers a constructive critique of the practices followed during the WFD implementation in Greece by pinpointing methodological weaknesses and knowledge gaps that undermine our ability to classify the ecological quality of Greek lakes. One of the pillars of WDF is a valid lake typology that sets ecological standards transcending geographic regions and national boundaries. The national typology of Greek lakes has failed to take into account essential components. WFD compliance assessments based on the descriptions of phytoplankton communities are oversimplified and as such should be revisited. Exclusion of most chroococcal species from the analysis of cyanobacteria biovolume in Greek lakes/reservoirs and most reservoirs in Spain, Portugal, and Cyprus is not consistent with the distribution of those taxa in lakes. Similarly, the total biovolume reference values and the indices used in classification schemes reflect misunderstandings of WFD core principles. This hampers the comparability of ecological status across Europe and leads to quality standards that are too relaxed to provide an efficient target for the protection of Greek/transboundary lakes such as the ancient Lake Megali Prespa.

The localization of bacterial components and/or metabolites in the central nervous system may elicit neuroinflammation and/or neurodegeneration. Helicobacter pylori (a non-commensal symbiotic gastrointestinal pathogen) infection and its related metabolic syndrome have been implicated in the pathogenesis of gastrointestinal tract and central nervous system disorders, thus medications affecting the nervous system - gastrointestinal tract may shape the potential of Helicobacter pylori infection to trigger these pathologies. Helicobacter pylori associated metabolic syndrome, by impairing gut motility and promoting bacterial overgrowth and translocation, might lead to brain pathologies. Trimebutine maleate is a prokinetic drug that hastens gastric emptying, by inducing the release of gastrointestinal agents such as motilin and gastrin. Likewise, it appears to protect against inflammatory signal pathways, involved in inflammatory disorders including brain pathologies. Trimebutine maleate also acts as an antimicrobial agent and exerts opioid agonist effect. This study aimed to investigate a hypothesis regarding the recent advances in exploring the potential role of gastrointestinal tract microbiota dysbiosis-related metabolic syndrome and Helicobacter pylori in the pathogenesis of gastrointestinal tract and brain diseases. We hereby proposed a possible neuroprotective role for trimebutine maleate by altering the dynamics of the gut-brain axis interaction, thus suggesting an additional effect of trimebutine maleate on Helicobacter pylori eradication regimens against these pathologies.

Helicobacter pylori infection (Hp-I) has been associated with a wide spectrum of gastrointestinal and extra-digestive manifestations, including neurodegenerative diseases. Contradictory data have been published on Hp-I and multiple sclerosis (MS) association, with studies mainly using serology for Hp-I detection that cannot distinguish between active and past infections. We herein hypothesize that humoral and cellular immune responses induced by active Hp-I, beyond damaging locally the gastric mucosa, they may shape the character of systemic autoimmune responses, contributing to MS pathogenesis. To investigate our hypothesis, active Hp-I has been diagnosed in two small MS Greek cohorts by using primarily gastric mucosa histology. A higher prevalence of active Hp-I was documented in MS patients vs. controls (86.4 vs. 50%, P = 0.002) accompanied by exclusive existence of duodenal ulcer and autoimmune diseases with endoscopic and histological findings of chronic active gastritis for the MS group. Our preliminary data suggested that active Hp-I unlike other studies, may not protect, but contribute to MS and we proposed possible Hp-relating mechanisms involved in MS pathophysiology, that merit further evaluation.

The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions againstreference(or non-impaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise, as it stipulates the robust delineation of reference conditions along with the establishment of threshold values for key environmental variables used as proxies for the degree of system impairment. Another important aspect is to ensure that water quality assessment is comparable among the different Member States. In this context, the present paper offers a constructive critique of the practices followed during the WFD implementation in Greece by pinpointing methodological weaknesses and knowledge gaps that undermine our ability to classify the ecological status of Greek lakes. One of the pillars of WDF is a valid lake typology that sets ecological standards transcending geographic regions and national boundaries. The national typology of Greek lakes has failed to take into account essential components (e.g. surface area, altitude, salinity). WFD compliance assessments based on descriptions of phytoplankton communities are oversimplified and as such should be revisited. Exclusion of most chroococcal species from the analysis of cyanobacteria biovolume in Greek lakes and most reservoirs in the Mediterranean Geographical Intercalibration Group (Greece, Spain, Portugal and Cyprus) is not consistent with the distribution of those taxa in lakes. Similarly, the total biovolume reference values and the indices used in their classification schemes reflect misunderstandings of WFD core principles. This hampers the comparability of ecological status across Europe and leads to quality standards that are too relaxed to provide an efficient target especially for the protection and management of Greek/transboundary lakes such as Lake Megali Prespa, one of the oldest lakes in Europe.

To the Editor,In their review, Zhang et al. [1] concluded that gastrointestinal microbiota (GI-M) plays an essential role in the development and progression of gastric pathologies; they considered ...

Neurodegeneration represents a component of the central nervous system (CNS) diseases pathogenesis, either as a disability primary source in the frame of prototype neurodegenerative disorders, or as a secondary effect, following inflammation, hypoxia or neurotoxicity. Galectins are members of the lectin superfamily, a group of endogenous glycan-binding proteins, able to interact with glycosylated receptors expressed by several immune cell types. Glycan-lectin interactions play critical roles in the living systems by involving and mediating a variety of biologically important normal and pathological processes, including cell-cell signaling shaping cell communication, proliferation and migration, immune responses and fertilization, host-pathogen interactions and diseases such as neurodegenerative disorders and tumors. This review focuses in the role of Galectin-3 in shaping responses of the immune system against microbial agents, and concretely, Helicobacter pylori (Hp), thereby potentiating effect of the microbe in areas distant from the ordinary site of colonization, like the CNS. We hereby postulate that gastrointestinal Hp alterations in terms of immune cell functional phenotype, cytokine and chemokine secretion, may trigger systemic responses, thereby conferring implications for remote processes susceptible in immunity disequilibrium, namely, the CNS inflammation and/or neurodegeneration.

In a literature search, the presence of Haematococcus in phytoplankton communities and its biogeography were investigated. Haematococcus, although showing a wide biogeographical distribution, has been rarely found in phytoplankton communities. Simultaneously, the colonization potential of air-dispersed Haematococcus in ephemeral waters and its interactions with coexisting phytoplankton taxa were examined by microscopy and molecular methods. Haematococcus was a successful colonist, appearing among the first taxa in the experimental containers. According to principal component analysis, Haematococcus growth rate was negatively correlated with the abundance and species richness of the other autotrophs. Furthermore, a negative correlation between Haematococcus and Chlamydomonas and a positive one between Haematococcus and Chlorella were found. Overall, Haematococcus appears to be an effective air-dispersed alga that can successfully colonize and establish populations in small ephemeral water bodies. However, its absence from phytoplankton in larger permanent water bodies could be related to its high light requirements, its competitive disadvantages against other algae, and the grazing pressures from predators. The results of our study suggest a life strategy based on adaptation to higher light intensities in very shallow waters compared with optical dense lakes. Therefore, ephemeral waters are the regular habitat for Haematococcus instead of being "stepping stones" for the colonization of lake phytoplankton.

We investigated the diversity of Cyanobacteria by microscopic observation and sequencing of cyanobacterial-specific amplified 16S rRNA genes in the water column of two shallow, eutrophic lakes (Doirani and Kastoria, northern Greece) during summer blooms. Previous phytoplankton studies in these lakes have shown that prolonged cyanobacterial blooms can occur, which are dominated by known toxic species, as well as other less known, co-occurring species. A total of 118 clones were sequenced which were grouped in 23 Cyanobacteria and 11 chloroplast-like phylotypes. Phylogenetic analysis revealed that each library included several unique phylotypes, as well as members of all common bloom-forming Cyanobacteria. Most of the phylotypes belonged to the genera Microcystis, Anabaena, Aphanizomenon, Cylindrospermopsis-Raphidiopsis group, Limnothrix and Planktothrix, comprising most of the diversity previously recognized by morphological observations in cyanobacterial morphospecies in these lakes. In addition, novel phylotypes belonging to the Chroococcales were recognized in both lakes. The structure of the cyanobacterial communities of the lakes were very similar, as revealed by the diversity index H (2.06 and 2.01 for L. Doirani and Kastoria, respectively) and LIBSHUFF analysis (XY12 P-value = 0.122 and YX12 P-value = 0.536), due to occurrence of groups of common phylotypes. This study gives an example for successful cyanobacterial bloom analysis by the combination of morphological and phylogenetic methods useful for monitoring cyanobacteria and water quality in freshwaters.

Aphanizomenon issatschenkoi and Raphidiopsis mediterranea were studied in the Mediterranean Lake Doirani during a cyanobacterial bloom (August―October 2004). Aphanizomenon issatschenkoi was clearly morphologically distinct from R. mediterranea on the basis of apical cells. The two species demonstrated an almost inverse temporal distribution, consistent preference for different water depths and negative correlation between their net growth rates. Raphidiopsis mediterranea exhibited a higher net growth rate (0.17 days ―1 ) and dominated during warmer water periods, with high Z max /Z sec ratio and low but available inorganic nitrogen. Aphanizomenon issatschenkoi was more generalist, exhibiting slower net growth (0.10 days ― 1 ) and a broader distribution in relation to temperature and light, regularly forming heterocytes under low nitrogen conditions. Aphanizomenon issatschenkoi was also phylogenetically distinct from R. mediterranea on the basis of partial 16S rRNA gene sequence. The R. mediterranea typical morphotype corresponded to one phylotype in the well-defined 16S rRNA gene sequence cluster of Cylindrospermopsis raciborskii. The formation of two specialized reproductive cells in the same individual of R. mediterranea is described for the first time and may indicate unknown alternative reproductive modes and lifestyles in planktonic Cyanobacteria.

We investigated the molecular diversity of cyanobacteria and bacteria during a water bloom in a lake with a long history of toxic cyanobacterial blooms (Lake Kastoria, Greece). We also tested the hypothesis whether bloom-forming cyanobacteria are preserved in the lake’s sediment 2 years after the bloom. The dominant cyanobacteria during the bloom included the potentially toxin-producing Microcystis aeruginosa and several other Chroococcales forms closely related to the genus Microcystis. This suggests that the use of cyanobacterial-specific primers seems to be very informative in describing the cyanobacteria during the water blooms. The bacterial community showed high diversity, consisting mostly of singleton and doubleton phylotypes. The majority of the phylotypes were typical lake bacteria including some potential pathogens and toxin metabolising bacteria, suggesting that the dominant toxic cyanobacteria did not have any significant effect on the bacterial community structure. In the sediment, 2 years after the water bloom, no bloom-forming cyanobacteria were retrieved, suggesting that they cannot be preserved in the sediment. Similar to the water column, sediment bacterial diversity was also high, consisting mostly of yet-uncultured bacteria that are related to environments where organic matter degradation takes place.

The taxonomical relationship of Cylindrospermopsis raciborskii and Raphidiopsis mediterranea was studied by morphological and 16S rRNA gene diversity analyses of natural populations from Lake Kastoria, Greece. Samples were obtained during a bloom (23,830 trichomes mL−1) in August 2003. A high diversity of apical cell, trichome, heterocyte and akinete morphology, trichome fragmentation and reproduction was observed. Trichomes were grouped into three dominant morphotypes: the typical and the non-heterocytous morphotype of C. raciborskii and the typical morphotype of R. mediterranea. A morphometric comparison of the dominant morphotypes showed significant differences in mean values of cell and trichome sizes despite the high overlap in the range of the respective size values. Additionally, two new morphotypes representing developmental stages of the species are described while a new mode of reproduction involving a structurally distinct reproductive cell is described for the first time in planktic Nostocales. A putative life-cycle, common for C. raciborskii and R. mediterranea is proposed revealing that trichome reproduction of R. mediterranea gives rise both to R. mediterranea and C. raciborskii non-heterocytous morphotypes. The phylogenetic analysis of partial 16S rRNA gene (ca. 920 bp) of the co-existing Cylindrospermopsis and Raphidiopsis morphotypes revealed only one phylotype which showed 99.54% similarity to R. mediterranea HB2 (China) and 99.19% similarity to C. raciborskii form 1 (Australia). We propose that all morphotypes comprised stages of the life cycle of C. raciborkii whereas R. mediterranea from Lake Kastoria (its type locality) represents non-heterocytous stages of Cylindrospermopsis complex life cycle.

A new, sensitive method was developed for the determination of the neurotoxin domoic acid (DA) using a reversed phase separation followed by post-column derivatization (PCD) with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and subsequent fluorescence detection. The PCD conditions which involves a two-step reaction was fully optimized for the lowest detection limit. The first reaction occurs between DA and NBD-Cl while the second makes possible the detection of the derivative causing the destruction of the interfering fluorescent 4-hydroxy-7-nitrobenzo-2-oxa-1,3-diazole (NBD-OH) which is the hydrolysis product of NBD-Cl. Kainic acid a similar base structure compound with DA was used as an internal standard. The developed post-column method provides the ability for a fully automated analysis, low detection limits (LOD 25 ppb in real samples of mussel extracts), it requires less sample preparation, and it gives clean simple chromatograms without chromatographic interferences from coeluting compounds such as tryptophan. The method was successfully applied to for the quantitative determination of DA in mussel tissues at quantities as low as 75 microg/kg tissue.

The phytoplankton species composition and seasonal succession were examined in Lake Kastoria during the period November 1998–October 1999. A total of 67 species and 19 functional groups were identified. Only 4 out of the 67 species, all Cyanobacteria, were dominant (Limnothrix redekei, Microcystis aeruginosa, Cylindrospermopsis raciborskii and Aphanizomenon gracile). Diatoms were rare, not only in terms of species number, but also in terms of biomass (contributing

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 μg 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 μL L—1) throughout the year and was in excess of Guidance Level 2 (10 μL 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 μg L—1) exceeded the WHO guideline for drinking water (1 μg 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. Toxische Cyanobakterien in Susgewassern Griechenlands 1987—2000: Vorkommen, Toxizitat und Beeinflussungen im Mittelmeergebiet In einer Untersuchung innerhalb Griechenlands von 1987 bis 2000 wurden Wasserbluten Hepatotoxin-bildender Cyanobakterien in 9 von 33 Binnengewassern beobachtet. Microcystine (MCYSTs) wurden mittels HPLC in sieben dieser Seen bestimmt, wobei die Gesamtkonzentration an MCYST in aufgerahmten Algenmassen zwischen 50.3 und 1638 ± 464 μg g—1 Trockenmasse lagen. Gattungen (Microcystis, Anabaena, Anabaenopsis, Aphanizomenon, Cylindrospermopsis) mit bekannt Toxin-bildenden Arten kamen in 31 Binnengewassern vor. Aus den Ergebnissen und einer Literaturubersicht wird offensichtlich, dass in mediterranen Landern eine Wahrscheinlichkeit fur Massenentwicklungen toxischer Cyanobakterien, hauptsachlich von Microcystis, und hohere intrazellulare MCYST-Konzentrationen besteht. Eine Fallstudie im Lake Kastoria dient zur Aufklarung der saisonalen Muster des Auftretens von Cyanobakterien und MCYST-LR und der Einschatzung des Cyanotoxin-Risikos. Das Biovolumen von Cyanobakterien war wahrend des ganzen Jahres hoch (> 11 μL L—1) und uberschritt den WHO-Richtwert 2 von 10 μL L—1 fur Erholungsgewasser und die Warnstufe 2 fur Trinkwasser. Weiterhin wurden in Proben aus dem Oberflachenwasser von April bis November die Richtwerte der Stufe 3 fur eine potentiell akute Vergiftung durch Cyanobakterien uberschritten. Die intrazellularen Konzentrationen von MCYST-LR (maximal 3186 μg L—1) uberschritten die WHO-Richtlinie fur Trinkwasser (1 μg L—1) von September bis November mit einem hohen Risiko fur Gesundheitsbeeintrachtigungen. Vorlaufige Ergebnisse weisen darauf hin, dass in drei Seen Microcystine in aquatischen Organismen akkumuliert werden. Generell kann aus den Ergebnissen ein hohes Risiko fur die mediterrane Region abgeleitet werden.

Cationic host defence peptides (CHDPs), also known as antimicrobial peptides (AMPs), are essential components of the innate immunity with antimicrobial and pleiotropic immunomodulatory properties. In mammals the two major families of CHDPs are defensins and cathelicidins that comprise an arsenal of innate regulators of principal importance in the host tissues. Research in the last decade has demonstrated that defensins are crucial effectors of both innate and adaptive immunity. Defensins can modulate immune responses, either by stimulation or suppression, thereby controlling inflammatory processes and infections. Currently only few data, mostly hypothetical, focus on the role of defensins in central nervous system (CNS) physiopathology and neurodegeneration. Defensins may function as an initial line of defense within the CNS either as an antimicrobial, immunomodulator, or both. A dysregulation of brain expression of specific defensins might either exacerbate or ameliorate the inflammatory response within the CNS depending upon which extracellular conditions predominate. It is proposed that reduction or abnormal elevation of AMP expression by cerebral microglia, astrocytes or choroid plexus epithelium might contribute to loss of AMP-induced regulation of immune responses, thereby promoting neuronal cell injury and death observed in Alzheimer’s disease and possibly in other neurodegenerative disorders. Nevertheless, whether certain AMPs play a crucial role in the onset or promotion of the neuroinflammatory process and neurodegeneration is currently unknown, thereby emphasizing the necessity of further investigation into the regulatory mechanisms that control innate and adaptive immunity within the brain. Recent data indicate that Helicobacter pylori (H. pylori) induces defensins’ release associated with chronic inflammatory tissue damage. However, it remains unclear whether and how H. pylori evades the attack by defensins. Moreover, recent evidence indicates that H. pylori infection might contribute to the pathogenesis of neurodegenerative diseases, by releasing several inflammatory mediators that could induce blood–brain barrier breakdown, thereby being involved in the pathogenesis of neurodegeneration. However, currently there are no data regarding the potential impact of human defensins on H. pylori-related neurodegenerative disorders. We herein propose that human defensins might contribute to the pathophysiology of H. pylori-related neurodegenerative disorders by modulating variably innate and adaptive immune system responses. Better understanding of the mechanisms regarding human defensins’ possible involvement in H. pylori-induced neurodegeneration might help develop novel therapeutic strategies against H. pylori-related neurodegenerative disorders.

The temporal and spatial distribution of planktic cyanobacteria and some environmental parameters were studied in the shallow, urban Lake Kastoria, Greece from June 1996 to June 1997. Water temperature varied from 6–27 °C, pH from 7.5–8.9 and dissolved O2 concentration from 0.7–12 mg m-3 10-3. The mean annual Chl a concentration was 83 mg Chl a m-3 indicative of the eutrophic-hypertrophic state of the lake. Cyanobacterial biomass ranged from 11–238 g FW m-3, constituting about 90% of the total phytoplankton biomass throughout the year. Cyanobacterial biomass was non-uniformly distributed both vertically and horizontally from August to November 1996 and resulted mainly from the distribution of Microcystis. Seven cyanobacterial taxa were reported for the first time in Lake Kastoria. Six taxa were dominant: Microcystis aeruginosa, M. flos-aquae, M. novacekii. Limnothrix redekei, Anabaena sp. and Cylindrospermopsis raciborskii. The dominant cyanobacterial taxa can be grouped on the basis of their distribution patterns (1) Microcystis species: maximum biomass occurring at pH > 8, temperature 12–17 °C, depth < 0.2 m; (2) Anabaena sp. and Cylindrospermopsis raciborskii: maximum biomass at temperatures 23–26 °C; (3) Limnothrix redekei: maximum biomass at temperatures 6–27 °C. Usually, non-uniform, vertical distributions of cyanobacterial biomass were associated with the formation of temperature, pH and O2 gradients. L. redekei was considered to be a key lake organism since it contributed up to 59% of the cyanobacterial biomass. Interestingly, three of the dominant cyanobacteria Microcystis aeruginosa, Anabaena sp. and Cylindrospermopsis raciborskii belong to genera that include toxin-producing species.

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.

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 μg.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 concentratio...

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.