Thomas Sawidis

Thomas Sawidis
Aristotle University of Thessaloniki | AUTH · Department of Botany

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87
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Publications

Publications (87)
Article
Full-text available
Chaenomeles japonica is an attractive ornamental shrub flowering in spring. It is also a valuable source of nectar and pollen for entomofauna. The study was carried out to investigate the structure of hypanthial nectaries present in the flowers of this species with the use of light and scanning electron microscopy. Nectary tissues were examined in...
Article
Full-text available
In vitro culture of Lilium longiflorum pollen grains was carried out to determine the role of manganese in pollen germination and pollen tube growth. Pollen germination was adversely affected by the presence of manganese (>10 ⁻⁸ M), whereas low concentrations (10 ⁻¹² –10 ⁻¹⁰ M) stimulated the process. Manganese caused morphological anomalies during...
Poster
Introduction: Industrial activities that have gained acceleration and the unconscious use of natural resources in parallel with the rapidly growing world population directly facilitate the increase of environmental pollution. As a result of nano-industrial activities, nano-level particles such as zinc oxides and copper oxides can be released into t...
Article
Full-text available
The anatomy and histochemistry of the adventitious roots of Urginea maritima (L.) Baker and the plant’s adaptive strategies to the Mediterranean climate were investigated. The adventitious roots of U. maritima are bounded by a multiple-layered velamen, responsible for rapid water uptake. Both the epidermis and endodermis of the root are uniseriate....
Article
Full-text available
Pollen development and germination were adversely affected by the presence of mercury, whereas low-concentrations stimulated the whole procedure. Mercury caused morphological anomalies during the tube growth, characterized by irregularly increasing diameters and swelling tips. The main effect was the anomalous cell wall formation at the tip where a...
Article
Dependence of dehydration rate of Brassica napus, Triticum spp., Zea mays and Hordeum vulgare from heavy metal concentrations in plants after its growth in contaminated media has been studied in the laboratory and results are summarized in this paper. We found water loss reduction in all plant species germinated in sewage sludge (somewhere soil) af...
Article
The present research focused on the experimental investigation of phytoreclamation of areas affected by sewage sludge disposal and improving the quality of the sludge. It was conducted in two stages: laboratory and pilot applications. This paper reports on the first stage, which tested, under greenhouse conditions, the possibility of using various...
Article
Metal concentrations in plants, soil and sediment were evaluated in the vicinity of a former iron/nickel enriching factory at Pogradec, near Ohrid Lake in Albania. Metal levels were significantly higher in soil samples than in the corresponding plants. Iron concentrations in both soil and plants were much higher than the nickel ones. Lower plants (...
Article
To understand the level of heavy metals (Cd, Co, Cr, Cu, Pb, Mn, Ni and Zn) in the ambient air of the Kathmandu valley, active monitoring technique using mosses was performed. Common mosses like Taxiphyllum giraldii (C. Muell.) Fleisch., Thuidium sparsifolium (Mitt.) Jaeg., and the leafy liverwort Ptychanthus striatus (Lehm. & Linderb.) Nees. colle...
Article
Stem structure strongly influences the drought response across a diverse group of temperate and tropical tree species. The stem of Salvadora persica (miswak), used as a chewing stick in the Islamic world, has a number of distinctive xeromorphic characteristics adapting it to arid or semi-arid conditions. The thick periderm is interrupted at points...
Article
Zinc toxicity in secretory cells caused a range of effects, mainly depending on metal concentration. Low concentrations activated nectary function increasing nectar secretion but secretion was greatly inhibited or stopped entirely by ongoing concentration. Water loss rate of zinc treated flower parts was significantly reduced whereas green sepals w...
Article
Full-text available
The structure of septal nectaries in Asphodelus aestivus flowers was investigated by using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (EM). It was found that the outlets of the three parts of the nectary were situated on the ovary surface at 2/3 of its height and had the shape of elongated opening...
Article
Concentrations of five metals (cadmium, chromium, copper, nickel and lead) were determined in tree leaves collected from 13 areas of the Attica basin and Athens city, Greece. Geographical distribution patterns were investigated, and factors affecting toxic element accumulation in trees were discussed. The mean heavy metal content in the tree leaves...
Article
Full-text available
The degradation of C.I. Direct red 80, a polyazo dye, was investigated using Bacillus firmus immobilized by entrapment in tubular polymeric gel. This bacterial strain was able to completely decolorize 50 mg/L of C.I. Direct red 80 under anoxic conditions within 12 h and also degrade the reaction intermediates (aromatic amines) during the subsequent...
Article
High salt concentrations in textile industrial wastewater challenge the efficiency of microbial strains used for decolorization of dye pollutants. In this study, the decolorization of Methylene blue (a phenothiazine dye) under high salt conditions using Bacillus firmus was investigated. The bacterial isolate was obtained from textile effluent as a...
Article
Studies were carried out to evaluate the colour removal capacity of a moderately halotolerant bacterium, Bacillus firmus, in synthetic saline wastewater medium (SSWM) under static condition. The bacterial strain effectively decolourized Polar red B (an azo dye) in a wide range of sodium chloride (1-6%, w/v), dye (5-100 mg/L) and SDS (0.1-5.0 mg/L)...
Article
A new dye decolourising bacterial strain was isolated from textile wastewater and identified as Bacillus firmus. The study indicated that the bacterium could efficiently decolourise different azo dyes under static culture conditions. Characterisation of the efficiency of azo dye reduction by this isolate using both spectral and HPLC analysis was fo...
Article
Full-text available
The levels of radioactive contamination by artificial radiocesium (137Cs) were evaluated in sediments and the commonest species of water plants. Specimens were collected from a range of biotopes along the Pinios River and its tributaries, during the years 1998 and 2010. The 137Cs concentrations within the above period clearly indicate that this rad...
Article
Concentrations of four heavy metals were determined in tree leaves and bark collected from polluted and non-polluted areas of three European cities (Salzburg, Belgrade and Thessaloniki) for a comparative study. Platanus orientalis L. and Pinus nigra Arn., widespread in urban northern and southern Europe, were tested for their suitability for air qu...
Article
Full-text available
Concentrations of chromium, copper, and lead were determined in soil and plant specimens collected from the area of coal power plant (CPP), A. Dimitrios, the largest CPP in Greece located on the eastern part of Ptolemais basin, Macedonia. Two cultivated plants (Brassica oleracea var. capitata L. and Zea mays L.) and two non-cultivated plants (Rumex...
Article
Aeromonas hydrophila, isolated from acclimated textile effluent after selective enrichment, was assessed for its dye biodegradability potential using chemically different dyes. The results revealed that the bacterium has a broad spectrum dye-degrading activity since it was able to efficiently decolorize the azo (Solophenyl red 3BL and Polar brillia...
Article
Full-text available
The flower of Rhododendron luteum (L.) Sweet has a pentamerous structure with radial symmetry. The anthers filament surface is covered by dense non-glandular hairs to the half of the height. The tubular anther dehisces along creating two openings in the anther-sac walls and the viscous pollen is released through two splits along the anther lobes. T...
Article
Cesium-137 content in lichens and mosses from northern Greece was measured for regular periods of time during the 5 years following the Chernobyl reactor accident. A clear increase of the cesium interception was observed for about 2 years after the accident. Later a gradual decrease was detected that depended on the habitat and the collected specie...
Article
137Cs content in lichens collected from Macedonia, Greece, was measured at regular intervals during the last decade following the Chernobyl reactor accident. An increase in 137Cs concentration was observed for about 2–3 years after the accident. Later a gradual decrease was detected which depended on the biotopes and the collected species. Higher 1...
Article
Full-text available
Economical and bio-friendly approaches are needed to remediate dye-contaminated wastewater from various industries. In this study, a novel bacterial strain capable of decolorizing triarylmethane dyes was isolated from a textile wastewater treatment plant in Greece. The bacterial isolate was identified as Aeromonas hydrophila and was shown to decolo...
Article
(137)Cs content in lichens and substrate (soil, bark) collected from W. Macedonia, Greece was measured 20 years after the Chernobyl reactor accident. Archive material from previous collections was also used for comparison and a diachronic estimation of the radio-contamination status. A gradual decrease was detected which depended on various factors...
Article
Full-text available
Mastic is a natural resin extracted from the stem of the evergreen tree Pistacia lentiscus var. Chia (Duham) (Anacardiaceae). For a long time, mastic has been esteemed for its aphrodisiac properties. To test this hypothesis, the trace element zinc was determined while the quantity released after a certain time of chewing was studied. For comparison...
Article
(137)Cs activities in mosses and substrate (soil, bark) collected from W. Macedonia, Greece were measured 20 years after the Chernobyl reactor accident. Archive material from previous studies was also used for comparison and diachronic estimation of the radio-contamination status. A gradual decrease was detected which depended on various factors su...
Article
Full-text available
Various secretory glands are observed on Asphodelus aestivus flower, a common geophyte of Mediterranean type ecosystem. The floral nectary has the form of individual slits between the gynecium carpels (septal nectary). The septal slits extend downwards to the ascidiate zone of the carpels. The nectar is secreted by the epidermal cells of the slits,...
Article
Full-text available
The morphology, anatomy, and ultrastructure of the floral nectary of Urginea maritima (L.) Baker were investigated at three stages of nectary development. The plant possesses a typical gynopleural (septal) nectary with secondary presentation. The nectary consists of one layer of epithelium secretory cells and one to four layers of subsidiary cells...
Article
Research on lichens as biological monitoring indicators is described. The concentration of Pb, Cu, Zn and Cd in lichens from polluted and unpolluted areas of Greece were determined by atomic absorption spectrometry after acid digestion. The levels of the heavy metals in the tissues of different species are discussed. Although bioaccumulation of hea...
Article
Cadmium had a highly toxic effect on pollen germination and tube growth, which were greatly inhibited as metal concentrations increased. Cadmium concentrations up to 10(-2) M completely stopped pollen germination and pollen showed an increasing tendency to burst within 1 h. At low concentrations, the metal caused a slight stimulation of pollen germ...
Article
Uptake of Pb, Cu and Zn by different epiphytic moss species Floribundaria floribunda (Doz. & Molk.) Fleisch., Taxiphyllum giraldii (C. Muell.) Fleisch. and Thuidium sparsifolium (Mitt.) Jaeg., an epilithic moss Thuidium delicatulum (L.) Mitt. and a leafy liverwort Ptychanthus striatus (Lehm. & Linderb.) Nees. was studied experimentally. The plant b...
Article
The effects of the heavy metals copper (Cu), zinc (Zn), and lead (Pb) on the chlorophyll content of two mosses Thuidium delicatulum (L.) Mitt. and T. sparsifolium (Mitt.) Jaeg., as well as leafy liverwort Ptychanthus striatus (Lehm. & Linderb.) were examined to understand the impact of metal accumulation on the chlorophyll content of mosses and lea...
Article
The secretory hairs of Hibiscus rosa-sinensis nectaries have been studied ultrastructurally, particularly at stages before, during and after secretion. Morphometric cytology revealed considerable changes in the volume of endoplasmic reticulum (ER) and the vacuoles. At least three different forms of ER have been noticed, cisternal, tubular and vesic...
Article
Full-text available
The patterns of water content and reserve allocation in the bulb parts of red squill (Urginea maritima (L.) Baker) and the plant's adaptive strategy to Mediterranean climate (Crete, Greece) were investigated. The different bulb parts serve varying ecological functions in terms of their resources and their importance for these functions. The basal p...
Article
Full-text available
The morpho-anatomy and histochemistry of the hysteranthous leaf ofUrginea maritima (L.) Baker and its adaptive strategies to the Mediterranean climate were investigated. The leaf ofU. maritima is 714 μm thick and possesses moderate specific leaf mass (8.564 mg cm-2) and low tissue density (136.5 mg cm-3). The epidermal cells are compactly arranged...
Article
Full-text available
The conducted studies pertained to micromorphology of the surface of epidermis cells and histological traits of staminal filaments of Asphodelus aestivus Brot. flowers. The structure of the filaments was analyzed in a light microscope (LM) using various histochemical techniques. The morphology of the surface of the epidermis of filaments was observ...
Article
The impact of human activities and environmental factors on the fluctuation of chemical and physicochemical parameters along the Pinios River and its tributaries was studied. Their seasonal variations throughout the years 1996-1998 are also presented. Most of the parameters (physical or chemical) measured in this survey exhibited high spatial and t...
Article
The root tubers of Asphodelus aestivus consist mostly of enlarged fleshy storage tissue. They are bounded by a multiple-layered velamen, responsible for rapid water uptake, water loss reduction, osmotic and mechanical protection. In the cortex area, thin-walled idioblasts contain numerous raphides of calcium oxalate in their large vacuole with a di...
Article
The impact of human activities with 3-year monitoring on the fluctuation of nutrients along the Pinios River and its tributaries were studied. Their seasonal variations throughout the years 1996-1998 were also presented. High temperatures, from June to August, cause a restriction of the water flow, an enhancement of nutrient concentration with the...
Article
Full-text available
Epiphytic mosses were sampled from 35 sites in Kathmandu valley for assessing air borne heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) through passive monitoring technique. These sampling sites were broadly divided into 3 categories viz., inside, along and outside the ring road. The ring road encircles core part of two cities, Kathmandu and Lalit...
Article
The commonest species of red, brown, and green macroalgae were sampled from a range of biotopes in the Aegean Sea during 1998 for their 137Cs content. Significant differences in 137Cs concentrations were found among different species growing under similar environmental conditions, suggesting that uptake does not follow physical levels but is influe...
Article
Full-text available
The distribution of natural K, Ra and Ra and artificial Cs has been investigated in nonvascular mosses (9 species) and lichens (10 species) and vascular gymnosperm (1 species), angiosperm trees and shrubs (3 species) over the Kozani-Ptolemaïda-Amynteon lignite basin in West Macedonia, Greece. Four lignite power plants producing about 70% of the ele...
Article
Full-text available
A comparative investigation of seven heavy metals (Cr, Mn, Fe, Ni, Cu, Cd and Pb) in mosses, lichens and trees over the Kozani-Ptolemaïda-Amynteon lignite basin in West Macedonia, Greece has carried out. In this region there are four lignite power plants producing about 70% of the electric energy of the country. Experiments have determined both con...
Article
Full-text available
The concentration of 16 trace elements (V, Cr, Mn, Co, Ni, Cu, Mo, As, Cd, Hg, Sn, Se, Sb, Ba, Ag and Pb) has been determined in 39 points distributed over the 2300 km of the Kozani-Ptolemaïda-Amynteon basin (Western Macedonia). In this area there are four lignite power plants, with an installed power of 4048 MW, which discharged into atmosphere ar...
Article
Full-text available
Long-stalked glandular hairs of outer and inner involucral bracts of Sigesbeckia jorullensis, which are important for epizoic fruit propagation, were investigated using light and scanning electron microscopy. The essential oil secreted by the hairs was analysed by chromatographic methods including gas chromatography/mass spectrometry and with a las...
Article
The commonest species of red, brown, and green macroalgae were sampled from a range of biotopes in the Aegean Sea and analysed for five different trace metals. Significant differences in metal concentrations were found among different seaweed species from the same biotope. The concentrations of metals in the various seaweed species may reflect thei...
Article
Full-text available
Radiometric determination of natural Ra, Ra, K and artificial Cs radionuclides distribution have been performed over the Kozani-Ptolemïda-Amynteon basin (Western Macedonia). Here there are localized four lignite power plants, accounting for about 70% of the total production of Greece's electricity. Soil samples, 0 to 20 cm depths, from both unculti...
Article
Concentrations of five metals (Cd, Cu, Mn, Fe, Zn) were determined in tree leaves collected from an area with large coal-fired plants in Ptolemais, Macedonia, Greece. The analyses were carried out with flame atomic absorption spectroscopy. Mean heavy metal content in the tree leaves is, in descending order, Fe>Mn>Zn>Cu>Cd. In Populus nigra and Sali...
Article
Radiometrie determination of natural 226Ra, 228Ra, 40K and artificial 137Cs radionuclides distribution have been performed over the Kozani-Ptolemi'daAmynteon basin (Western Macedonia). Here there are localized four lignite power plants, accounting for about 70% of the total production of Greece's electricity. Soil samples, 0 to 20 cm depths, from b...
Article
The distribution, anatomy and development of the resin duct system responsible for the resin exudation in Pistacia lentiscus var. chia Duhamel were investigated. Resin ducts are present in the stem, leaf and root located only in the phloem of the vascular bundles. They are tubular structures lined by a few layers of epithelial cells. Outwards the r...
Article
137Cs activities in mosses collected from four sites in Macedonia, N. Greece were measured for regular periods of time during the last decade following the reactor accident in Chernobyl. Samples taken in 1985 allow to determine the 137Cs contamination before the accident. A clear increase of the cesium interception was observed for about two years...
Article
The nectary of Hibiscus rosa-sinensis is subtended by subglandular parenchymatous tissue extending from the bases of the nectary hairs to the depth of about 30 cells. Several of these cells contain large crystals. The subglandular tissue shows a well developed vascularization. In principal two cell types were found. When Sudan Black B or the select...
Article
The nectary of Hibiscus rosa–sinensis is subtended by subglandular parenchymatous tissue extending from the bases of the nectary hairs to the depth of about 30 cells. Several of these cells contain large crystals. The subglandular tissue shows a well developed vascularization. In principal two cell types were found. When Sudan Black B or the select...
Article
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 sub...
Article
The heavy metal content in lichens and vascular plants from abandoned copper mining areas, Gerakario (Kilkis) and Megali Panagia (Chalkidiki), have been compared with metal content in soil in order to assess their efficiency to accumulate five metals (Cu, Mn, Pb, Zn, and Cr). The average metal content in the mineralized soil of Gerakario was, in de...
Article
The chemical and physiochemical parameters in waters of four rivers were studied comparatively. The fluctuation of parameters in one of them, which contains an artificial lake, is also presented. The highest concentrations of nitrates and nitrites were observed in winter and early in spring (wet period). During the warm months the concentrations of...
Article
The impact of climate change and human activities on the fluctuation of chemical and physico‐chemical parameters along the river Pinios as well as on their seasonal variation are presented. High temperatures, from June to August, cause a restriction of the water flow, an enhancement of nutrient concentration with the subsequent increase of eutrophi...
Article
Water loss in lichen species Cladonia convoluta (Lam.) and C. rangiformis (L.) Hoffm. after exposure to heavy-metal (Pb, Cu, or Zn) solutions, either as single compounds or in combination, have been studied in this laboratory. Water loss was reduced in Pb-treated C. convoluta, whereas in C. rangiformis it increased significantly with 10(-2) M Pb tr...
Article
Uptake of Pb, Cu and Zn by thalli of Cladonia convoluta (Lam.) and Cladonia rangiformis (Hoffm.) from different concentrations of solutions of Pb(NO3)2, CuCl2 and ZnCl2 was studied. Zinc accumulation was higher in living than in dead thalli, but the opposite occurred for Pb and Cu. Further study with a solution containing all three metals revealed...
Article
Flowers of Lilium longiflorum (Thunb.) were fed through their pedicel with zinc, copper, and lead at various concentrations. The flowers were separated into individual parts and dried under normal laboratory conditions until reaching a constant air dry weight. In treated flowers, loss of water was reduced significantly in comparison to control flow...
Article
The possibility of using aquatic macrophytes and algae as bioindicators of water pollution is investigated. The use of cluster analysis enables the treatment of the analytical data in a global way, revealing hidden clusters of similar behaviour between various biological species or sampling sites. A great number of species was collected from four r...
Article
The levels of radioactive contamination by artificial radiocesium (Cs-137, Cs-134) as well as the concentrations of natural radioisotopes (K-40, Ra-226, Ra-228, Th-228) in sediments and aquatic plants were evaluated in selected aquatic biotopes in Macedonia, Greece. Radionuclide analysis was performed in Marinelli beakers by a gamma spectrometry sy...
Article
The application of tree species (leaves) as biomonitoring devices is studies by the use of cluster analysis. It is shown that the chemical analysis of leaf samples should be accompanied by a careful chemometrical data treatment in order to obtain a reliable information on the behaviour of various tree species to heavy metal exposure (8 trees for th...
Article
Heavy metal concentrations were surveyed in several species of aquatic macrophytes and in sediments of a lake and four rivers from Macedonia, northern Greece. Acid digestion of sediments and plant material and the subsequent use of atomic absorption spectrometry were the analytical methodologies followed for the analysis. Values were variable withi...
Article
The influence of different concentrations of the heavy metals cadmium (Cd2+), cobalt (Co2+), copper (Cu2+), iron (Fe2+ and Fe3+), mercury (Hg2+), manganese (Mn2+), and zinc (Zn2+), plus aluminium (Al3+) (a toxic metal in polluted areas), on pollen germination and tube growth ofLilium longiflorum was investigated using light microscopy. Effects coul...
Article
The air pollution of the city of Thessaloniki was studied, using park trees as biomonitors. The species analyzed were Ligustrum japonicum, Nerium oleander, Olea europea, Pinus brutia, Platanus orientalis, Populus alba, Populus nigra, and Robinia pseudoacacia. Acid digestion of leaf tissues and subsequent use of atomic absorption spectrometry was th...
Article
The bioaccumulation of lead copper zinc and cadmium in mosses collected from polluted and unpolluted areas is presented in this work. Acid digestion and subsequent use of atomic absorption spectrometry was the analytical methodology followed for the analysis. The concentration of accumulated heavy metals differs in various moss species from the sam...
Article
The 137Cs concentrations in lichens and mosses were significantly high five years after the Chernobyl accident. In some species of foliose lichens and mosses, the uptake of 137Cs during the long period of time was dominant in respect of its natural removal. In some species of fruticose lichens, decrease of the 137Cs concentration was only observed...
Article
Different histochemical and cytochemical methods were employed on nectaries of Hibiscus rosa-sinensis. Light microscopy revealed the presence of oil and mucilage cells in the subglandular tissue. Electron microscopy showed intense activity of ATPase in the phloem subtending the nectary. When CaCl2 or tannic acid are added to the fixative, electron-...
Article
InFunaria protonemata, preprophase bands (PPBs) of microtubules do not develop when the tip cell divides, when side branches are initiated or in intercalary regeneration divisions. We report here that PPBs do, however, develop when a tmema cell is formed. In the former cases, cell division is not coupled with an expansion of the mother cell wall at...
Article
Plasmodesmata are occluded when Funaria chloronemata are fragmented by the development of tmema cells (TCs). The TC deposits a new wall layer along the cross wall toward the neighbouring non-sister cell (NC). This wall layer cuts off the plasmodesmata and its connection with the cross wall is soon lost. The plasmodesmata become isolated when the NC...
Article
Surface sediments and aquatic plants from the River Pinios, Greece, were collected and analyzed for Fe, Mn, Ni, Zn, Cr and Cu, in order to obtain information about the heavy metal contamination of the river. The selected species proved to be good indicators for the monitoring of heavy metals. The distribution of heavy metals in the root, the stem a...
Article
In ageing protonemata of Funaria as well as in liquid cultures with low calcium medium, tmema cells (TC) develop, i.e. cells that disrupt chloronema filaments into fragments of one or a few cells. The frequence of TC is strongly enhanced and the formation accelerated in auxin-deficient mutants. In the mutants, the formation of TC is depressed by th...
Article
Cesium-137 concentrations in plant species of three biotopes of northern Greece, differing in location as well as in vegetation, are reported following the Chernobyl reactor accident. The cesium uptake by plants was due to the foliar deposition rather than the root uptake. The highest level of cesium in plants was found in Ranunculus sardous, a pub...
Article
In the aftermath of the Chernobyl reactor accident, the radioactivity in lichens and mosses has been studied. 137Cs concentrations ranged from about 1070 to 14 560 Bq kg−1 in lichens and from 270 to 4750 Bq kg−1 in mosses. Besides the cesium isotopes, some other relatively long-lived fission nuclides, such as 106Ru, 144Ce, 125Sb, and the 110mAg pro...