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BioRisk
Journal Prestige (SJR): 2.568
Citation Impact (citeScore): 6
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  This is an Open Access Journal Open Access journal
ISSN (Print) 1313-2644 - ISSN (Online) 1313-2652
Published by Pensoft Homepage  [58 journals]
  • Study of the dynamics of the microbial communities in the wedge clam
           Donax trunculus (Linnaeus, 1758) from the Bulgarian aquatory of the Black
           Sea

    • Abstract: BioRisk 21: 29-40
      DOI : 10.3897/biorisk.21.111253
      Authors : Sevginar F. Ibryamova, Stephany Toschkova, Darina Ch. Bachvarova, Elitca Stanachkova, Radoslav I. Ivanov, Nikolay D. Natchev, Tsveteslava V. Ignatova-Ivanova : In the present work, we investigated the dynamics of the microbial communities in the wedge clam Donax trunculus (Linnaeus, 1758) from the Bulgarian coastal waters of the Black Sea. The samples were collected in the period of January 2020 until December 2022 from Arkutino, Ahtopol, Obzor and Tsarevo. The BIOLOG system was used for microbiological determination. In our investigation were isolated the following microorganisms: Enterococcus cancerogenus, Enterococcus hirae, Escherichia vulneris, Citrobacter farmeri, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterobacter cloacae, Escherichia hermannii, Pseudomonas mendocina, Pseudomonas fulva, Pseudomonas alcaligenes, Pseudomonas putida, Acinetobacter johnsonii, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterococcus gallinarum, Citrobacter sedakii, Pseudomonas putida, Streptococcus lugdunensis, Enterococcus casseliflavus, Vibrio cincinnatiensis, Vibrio alginolyticus, Vibrio parahaemolyticus, Enterococcus hirae, Streptococcus aureus, Staphylococcus lugdunensis and Enterococcus casseliflavus. During the winter period, we detected the presence of Pseudomonas sp. – P. alcaligenes, P. putida, and A. gyllenbergii. In the autumn months we isolated C. sedakii, C. farmeri, A. gyllenbergii, A. johnsonii, P. fulva and E. casseliflavus. In the spring, E. cancerogenus, E. hirae and Pseudomonas mendocina were found. During the summer, the highest biodiversity of microorganisms - E. hirae, E. vulneris, E. cloacae, E. gallinarum, P. putida, V. cincinnatiensis, V. alginolyticus, V. parahaemolyticus, S. aureus, E. hermannii and S. lugdunensis were registered. Although our three-year research showed that some species are permanent and others are transient, we tend to accept the conclusion that there is only a transient microbiota in mussels and it changes depending on environmental conditions or is a result of pollution of the Black Sea. HTML XML PDF
      PubDate: Tue, 5 Dec 2023 10:48:42 +0200
       
  • Prospects and possibilities of using Raman spectroscopy for the
           identification of Pseudomonas aeruginosa from turtle Emys orbicularis
           (Linnaeus, 1758) skin

    • Abstract: BioRisk 21: 19-28
      DOI : 10.3897/biorisk.21.111983
      Authors : Aleksandrs Petjukevičs, Inta Umbraško, Natalja Škute : This study describes an express method for identifying microorganisms: Pseudomonas aeruginosa by standard Raman spectroscopy, without surface-enhanced Raman spectroscopy (SERS). The short-wavelength 514 nm Ar-Ion laser was used for P. aeruginosa spectral identification in the Raman shift range from 3200 cm−1 to 200 cm−1. The research results showed a high analytical and diagnostic sensitivity of the technology to the express identification of P. aeruginosa and can be used as one of the reliable methods. The proven technology is promising for further research of other microorganisms due to several significant advantages of the method. It does not require long-term cultivation of bacteria and special sample preparation, additional expensive reagents or consumables. HTML XML PDF
      PubDate: Fri, 17 Nov 2023 15:53:04 +020
       
  • Biomonitoring with bryophytes in managed forested areas. Three examples
           from the southern Italian Apennines

    • Abstract: BioRisk 21: 11-18
      DOI : 10.3897/biorisk.21.108551
      Authors : Carmine Colacino : Three sites in the southern Italian Apennines were selected to assess correlation between forest structure and bryophyte flora. In two of the sites, the Index of Air Purity (IAP)–based on cover data of epiphytic bryophytes–was evaluated. The results show that bryophyte populations–and consequently IAP–are affected by forest structure and development, and that studies including different sites require a precise assessment of silvicultural characteristics to allow comparisons. Indicator values of mosses and liverworts were also taken into consideration in characterizing ecologically the three sites. HTML XML PDF
      PubDate: Fri, 27 Oct 2023 17:24:38 +030
       
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon model complex lipids

    • Abstract: BioRisk 21: 1-10
      DOI : 10.3897/biorisk.21.101171
      Authors : Wojciech Ciesielski, Henryk Kołoczek, Zdzisław Oszczęda, Wiktor Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: Recognising effects of static magnetic field (SMF) of varying flux density on flora and fauna is attempted. For this purpose, the influence of static magnetic field is studied for molecules of five complex lipids i.e. such as β-carotene, sphingosine, ceramide, cholesterol and phosphatidylcholine. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AMFU (Arbitrary Magnetic Field Unit; here 1AMFU> 1000 T) flux density were performed in silico (computer vacuum), involving advanced computational methods. Results: SMF polarises molecules depending on applied flux density. Only β-carotene survives exposure to SMF of 10 and 100 AMFU without radical splitting of some valence bonds. Molecules of remaining lipids suffered radical cleavage of some bonds on exposure to SMF of 10 and 100 AMFU. Manipulation with applied flux density provides either inhibition or stimulation of biological functions of the lipids under study. Conclusions: SMF destabilises complex lipids to the extent depending applied flux density. Biological functions of β-carotene are fairly sensitive to SMF, whereas only slight response to the effect of SMF is observed in case of sphingosine, ceramide and cholesterol. Enzymatic hydrolysis of phosphatidylcholine is stimulated by SMF regardless of the catalysed enzyme employed. HTML XML PDF
      PubDate: Fri, 15 Sep 2023 13:55:08 +030
       
  • Forest habitats of Godech Municipality, Western Bulgaria

    • Abstract: BioRisk 20: 153-163
      DOI : 10.3897/biorisk.20.97534
      Authors : Borislav Grigorov, Nikolay Velev, Assen Assenov, Momchil Nazarov, Beloslava Genova, Kiril Vassilev : The current study aims at revealing the forest habitat diversity of Godech Municipality, according to the EUNIS habitat classification. Initial data was collected from the Ministry of Environment and Water and the Forestry Management Plans. Subsequently, 418 vegetation plots (relevés) and 3422 verification points were collected during the fieldwork seasons of 2019 and 2020. The research territory is situated in Western Bulgaria in close proximity to the country’s border with the Republic of Serbia. Forests cover a total of 144.85 km2. Their phytocoenoses are dominated by Fagus sylvatica L. (59.22 km2), Quercus cerris L. (14.85 km2), Carpinus betulus L. (4.94 km2), Quercus dalechampii Ten. (2.39 km2), Q. frainetto Ten. (2.99 km2). There are plantations with Pinus nigra J. F. Arnold (20.87 km2), P. sylvestris L. (16.06 km2) and Picea abies H. Karst (11.65 km2) also. Forests are experiencing some major threats, such as logging, pollution and fires. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:12 +030
       
  • The use of boreal relict shrub habitats of willow-leaf meadow sweet
           (Spiraea salicifolia) and shrubby cinquefoil (Potentilla fruticosa) in
           Western Rhodope Mts. by mammal species

    • Abstract: BioRisk 20: 139-152
      DOI : 10.3897/biorisk.20.97604
      Authors : Venislava Spasova, Daniela Simeonovska-Nikolova, Krastio Dimitrov, Gabriela Petrova, Kalina Pachedjieva, Rossen Tzonev : Plant communities of two peat-shrub species – Spiraea salicifolia and Potentilla fruticosa were studied in the Rhodope Mts., with emphasis on their use as a resource for the mammals associated with them. These shrubs are boreal relicts among the dominant coniferous forests. The field surveys were conducted in the spring-autumn period of 2021–2022. In both study areas, the species composition of the mammals was studied by camera traps for medium and large mammals, and by Sherman live traps for small mammals. The species registered were roe deer (Capreolus capreolus), red fox (Vulpes vulpes), wild boar (Sus scrofa), pine marten (Martes martes), European hare (Lepus europaeus), red squirrel (Sciurus vulgaris), bank vole (Myodes glareolus) and yellow-necked mouse (Apodemus flavicollis). Having in mind that small mammals are vital prey base for avian and mammalian predators, it is not surprising that M. glareolus and A. flavicollis individuals were captured in the habitats that they probably use as shelters. The pine marten inhabits the forests by which the community of P. fruticosa is surrounded, but probably feeds on the rodents in the shrub. In this way, it probably provides it with an alternative to the forest food base and hunting ground. From the presented results, it seems that the L. europaeus uses P. fruticosa shrubs as food. Therefore, the plant communities of the two relict peat-shrub species studied probably provide shelter and food for the mammals. Their importance is established for at least one species of mammal with conservation significance at national and European level – M. martes. Therefore, it is necessary to continue and expand the future monitoring on mammal diversity of these relict communities. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:11 +030
       
  • Comparative study of metal concentration determination in albumen of
           hen eggs originating from industrial poultry farms, backyard and
           free-range hens using ICP-OES technique

    • Abstract: BioRisk 20: 129-138
      DOI : 10.3897/biorisk.20.97322
      Authors : Plamen M. Kirov, Metody Karadjov, Hristo K. Hristov, Radostina Alexandrova : There have been multiple types of research focusing on the relationship between feed ingredients and metal content in the egg white due to their role in human nutrition. The aim of the present study is to determine the metal concentration in hens’ eggs and, in particular, to compare the metal concentration in egg albumen originating from industrial poultry farms with that of backyard and free-range hens. All samples were collected in Romania from five separate counties and 10 different farms, over a period of two weeks and, as a result, a total of 50 were collected, 10 from each housing system (batteries/cages, litter/soil, free-range, organic and backyard). The measurements of the metals were taken by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), with a wide range of elements reported. For the essential elements, we measured Cr, Cu, Fe, Mn and Zn; Al, Cd, Ni and Pb for the heavy metals and, in addition, we measured B, Ba, Sr, Ca and Mg. The present study revealed that the metals in eggs from free-range hens are richer in essential elements with mean concentrations as follows: 1.528 mg/kg for Fe, 3.278 mg/kg for Zn, 0.058 mg/kg for Mn and 1.362 mg/kg for Cu. We concluded that the egg quality is closely connected with the housing system and nutrition. Furthermore, the results demonstrate that eggs from backyard housing are no better than those from free-range hens in terms of essential metal composition. The heavy and non-essential metal contents, present in the albumen of all the examined eggs, were much lower than the maximum allowed concentration and, therefore, egg consumption does not pose any risk to human health. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:10 +030
       
  • Study of the plant growth-promoting capacity of Pseudomonas putida 1046
           in a model plant system

    • Abstract: BioRisk 20: 115-128
      DOI : 10.3897/biorisk.20.97581
      Authors : Gloria Georgieva, Trayana Nedeva, Marina Badalova, Veronika Deleva, Valentin Savov : Plant Growth Promoting Rhizobacteria (PGPR) represent a microbial community that exerts growth-promoting capabilities in plants by various mechanisms. Among the PGPR genera, Pseudomonas spp. deserves special attention. It is due to its characteristic traits, like the production of phytohormones and siderophores, solubilization of minerals and phosphates, and plant protection from biotic and abiotic stress. These PGPR properties depend on the microorganism and its plant counterpart. The use of microbial strains as bioinoculants must consider the physiological and economic aspects of the process, and the plant growth stimulating effect has to be checked and proved. This study aimed to explore the PGP capacity of Pseudomonas putida 1046 strain in a model plant system of the economically important corn culture (Zea mays). The effect of the strain’s metabolic status on the plant germination capacity was evaluated. Bacterial cultures, grown 16 h and 48 h, were explored for the treatment of the corn seeds at three experimental concentrations: 0.1, 0.2, and 0.4%, and monitoring of their germination capacity through the growth indicators length of the radicle, length of the coleoptile, and the number of lateral roots. The data obtained outline the positive effect of Pseudomonas putida 1046 on the germination capacity of corn when applied at 0.2% concentration. The in vitro treatment of the model plants with 0.2% suspension resulted in a 22.87%–28.33% increase in the length of the radicle, a 35.96%–49.56% increase in the length of the coleoptile, and a 5.41–16.67% increase in the number of the lateral roots. High values of the vigour index (2125 for 16 h and 2721 for 48 h culture) were also registered. The strain’s ability to produce siderophores of hydroximate type and exhibit phosphate solubilizing activity is proved. The optimal treatment parameters of the corn seeds comprise the application of 0.2% suspension of 16 h grown Pseudomonas putida 1046 strain for five days. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:09 +030
       
  • In vitro clonal propagation of Tanacetum cinerariifolium and
           establishment of an ex situ collection of selected clones

    • Abstract: BioRisk 20: 97-114
      DOI : 10.3897/biorisk.20.97566
      Authors : Vladimir Ilinkin, Boryanka Traykova, Marina Stanilova : Dalmatian pyrethrum Tanacetum cinerariifolium (Trevir.) Sch. Bip. (Asteraceae) is a perennial herb endemic to the eastern coast of the Adriatic Sea. The species is widely cultivated in many countries for its bioactive compounds pyrethrins, which are used as natural insecticides. Plants derived from seeds vary greatly in pyrethrin content; therefore, the vegetative propagation of high-quality individuals is very important for the establishment of agricultural pyrethrum crops. The present study deals with rapid in vitro multiplication of pyrethrum, ex vitro adaptation of selected clones and creation of an ex situ collection, as a first step towards introducing the species into agriculture in Bulgaria. Seeds from a private ex situ collection in Bulgaria and from a natural Croatian population were used as initial material for in vitro cultures initiation. Basal MS medium (Murashige and Skoog 1962) or MS supplemented with different concentrations of kinetin and indole-3-butyric acid were used for seed germination and multiplication of one-seed derived clones by consecutive subcultivations. The propagation effectiveness was evaluated as a number of new plants obtained per initial shoot. Considerable losses were noticed due to both endophytic contaminations and necrosis, especially on media supplemented with plant growth regulators. These problems were overcome by medium optimization: adding an antibiotic and modifying the medium to increase the calcium concentration using CaCO3. In the best medium variant (basal MS + 200 mg/L Medaxone + 75 mg/L Ca) no more infected plants were observed, and the percentage of necrotic plants decreased threefold, which resulted in formation of 38.06±10.11 new plants per initial shoot for a period of 7 months. Three hundred and sixty plants were ex vitro adapted in a phytotron (88% surviving rate), then 16 plants from 4 selected clones were transferred to the ex situ collection and bloomed twice from the very first growing season (June and September). The number of the flower heads increased in the second year of field cultivation and an average of 328±138 capitula per plant were counted for the best clone. The first trials to establish a pilot plantation of pyrethrum are promising. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:08 +030
       
  • Alterations in membrane stability after in vitro exposure of human
           erythrocytes to 2.41 GHz electromagnetic field

    • Abstract: BioRisk 20: 83-96
      DOI : 10.3897/biorisk.20.97616
      Authors : Boyana Angelova, Gabriela Atanasova, Nikolay Atanasov, Momchil Paunov, Maria Gurmanova, Margarita Kouzmanova : The growing use of wireless communication devices has been significantly increasing the level of high frequency electromagnetic fields (EMFs) in the environment, which raises a concern for possible deleterious effects on living organisms. Long lasting exposure to low-intensity EMFs can cause effects on the molecular and cellular level, and a number of morphological and physiological changes. The aim of this work was to investigate the effects of 2.41 GHz EMF emitted by wireless communication systems on human erythrocytes after in vitro irradiation. The amount of the hemoglobin released from the cells was measured as an indicator for membrane destabilization. Effects of different exposure times (20 min or 4 h) and time elapsed after exposure to 2.41 GHz pulsed or continuous EMFs with different intensities, emitted from a textile (0.213–0.238 V/m) or a dipole (5, 20, 40 and 180 V/m) antenna, were investigated. The obtained results showed that the low intensity EMF had no significant effect on the hemoglobin release from irradiated cells; even a slight tendency for membrane stabilization was noticed 3–4 hours after the end of 20-min exposure to 0.213–0.238 V/m, 2.41 GHz EMF. There was no difference in the effects of continuous and pulsed EMFs. Increased hemoglobin release was observed only during the 4-hour exposure to 180 V/m, 2.41 GHz continuous EMF. Under these conditions, the temperature of the cell suspension had been rising, so we compared the results obtained under EMF with the effects of conventional heating. Moreover, after 1-hour exposure to 180 V/m the released hemoglobin level was a bit higher than the control one but the difference disappears within an hour after terminating the irradiation. In conclusion, the in vitro exposure to 2.41 GHz EMF emitted by wireless communication devices with power density below the reference level for population exposure does not change the stability of the cell membrane of human erythrocytes. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:07 +030
       
  • Occurrence of marine biotoxins on Bulgarian Black Sea coastal
           waters in 2021

    • Abstract: BioRisk 20: 71-81
      DOI : 10.3897/biorisk.20.97557
      Authors : Zlatina V. Peteva, Stanislava K. Georgieva, Bernd Knock, Thomas Max, Mona D. Stancheva, Simona Valkova : Marine biotoxins are produced by certain phytoplankton species and used to accumulate in filter-feeding marine organisms. The occurrence of marine biotoxins in all aquatic environments and latitudes is variable in time and space. Thus, it is an essentially natural phenomenon, but the occurrence of toxigenic phytoplankton cannot be completely avoided or eliminated. A serious concern appears if these substances accumulate at high levels in seafood. If it is consumed by mammals including humans, severe illness of consumers of intoxicated seafood may result. The aim of this study is to assess the presence of marine biotoxins in plankton samples taken in 2021 and to compare the determined levels with a previous period. Plankton samples (n = 21) were collected in 2021 along the whole Bulgarian coastline (Black Sea). The presence of hydrophilic (domoic acid (DA)) and lipophilic toxins (okadaic acid, dinophysis toxin – 1, dinophysis toxin -2, azaspiracid-1, goniodomin A, pectenotoxin-2 (PTX2), yessotoxin, spirolide-1 and gymnodimine A) was investigated via liquid chromatography – tandem mass spectrometry (LC-MS/MS). Results indicated the presence of only DA in three samples and PTX2 in two samples. The positive samples were sporadically distributed throughout the study period. During 2016–2019, LC-MS/MS analysis confirmed the presence of DA, PTX2, YTX, SPX-1 and GDA in plankton net samples collected from the same locations reported here. The matching toxins (DA and PTX2) were at comparable levels in both periods of investigation, thus lower than in other European waters where harmful algal blooms are registered. These results show the persistent appearance of some marine biotoxins in Bulgarian waters. Although levels were low in the monitored periods, a constant monitoring is required in order that toxic events by seafood consumption be avoided. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:06 +030
       
  • Evaluation of abundance of microplastics in the Bulgarian coastal
           waters

    • Abstract: BioRisk 20: 59-69
      DOI : 10.3897/biorisk.20.97555
      Authors : Stanislava K. Georgieva, Zlatina V. Peteva, Mona D. Stancheva : Plastic pollution in seawaters is ubiquitous, but quantitative estimates on the floating microplastics in the Black Sea are still limited. Plastics may adsorb persistent environmental contaminants, thus representing a potential risk for marine organisms. Aim: Thе aim of the study was evaluation of the presence and characteristics of microplastic particles (MPs) in waters from the Black Sea coast of Bulgaria. Materials and methods: Samples of coastal waters were collected from March 2021 to April 2022 from different stations on the Black Sea coast, including protected, aquaculture and industrial areas. In order to determine the number of plastic particles, 23 samples were collected from the surface waters at depth of 1–3 m close to the Bulgarian shore. Samples were treated with H2O2, plastic particles were isolated by density separation and filtered over a membrane filter. Identification analysis of micro particles (< 5 mm) was performed visually by microscopy. Main results: Results indicated widespread presence of microplastics in coastal waters. Mean MPs concentration was calculated 7.3 ± 4.9 pt/l. The comparison of the North, Varna and South sampling area showed that there is no significant difference in the abundance of plastic particles. The most dominant type forms were fibres followed by fragments. The most abundant size class of fragments was 101–500 μm Ferret diameter. Conclusion: Further studies are needed in order to fill knowledge gap and to evaluate distribution of plastic particles in the Black Sea and their potential ecological risk. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:05 +030
       
  • Genotype differences towards lead chloride harmful action

    • Abstract: BioRisk 20: 37-57
      DOI : 10.3897/biorisk.20.97598
      Authors : Teodora Ivanova Todorova, Petya Nikolaeva Parvanova, Krassimir Plamenov Boyadzhiev, Martin Dimitrov Dimitrov, Stephka Georgieva Chankova : The aim of the study was to throw more light on the PbCl2 mode of action (MoA) depending on the genotype by the application of three model organisms and microbiological, biochemical, and molecular approaches. Three model systems – Chlamydomonas reinhardtii strain 137C – wild type (WT), Saccharomyces cerevisiae strain D7ts1, and Pisum sativum L. cultivar Ran1 and two experimental schemes – short- and long-term treatments were used. C. reinhardtii and S. cerevisiae cell suspensions (1×106 cells/ml) at the end of the exponential and the beginning of a stationary phase of growth were treated with various PbCl2 concentrations (0.45–3.6 mM) for 2 hours. Lower PbCl2 concentrations (0.03–0.22 mM) were also tested on C. reinhardtii 137C. Short-term treatment for up to 2 days with PbCl2 concentrations in the range of 0.45–3.6 mM and long-term treatment for up to 10 days with concentrations in the range of 0.45–2.7 mM was performed on P. sativum L. seeds and plants, respectively. Long-term treatment with a PbCl2 concentration of 3.6 mM was not tested because of the very strong toxic effect (plant death). The following endpoints were used – for C. reinhardtii: cell survival, “visible” mutations, DNA double-strand breaks (DSBs), malondialdehyde (MDA), intracellular peroxides (H2O2), and photosynthetic pigments; for S. cerevisiae – cell survival, gene conversion, reverse mutation, mitotic crossing-over, DSBs, superoxide anions, MDA and glutathione (GSH); P. sativum L. – germination and root length (short-term treatment), pro-oxidative markers – MDA, H2O2 and photosynthetic pigments (long-term treatment). Genotype differences between C. reinhardtii (0.047 mM) and S. cerevisiae (1.66 mM) were observed by two endpoints: concentrations inducing 50% lethality (LD50) and DSB induction. By contrast, no mutagenic effect was found for both unicellular test models. A slight toxic capacity of PbCl2, measured as inhibition of Pisum sativum L. seed germination and around 20% root length reduction was revealed after the treatment with concentrations equal to or higher than 1.8 mM. The variety of stress responses between the two plant test models was demonstrated by comparing MDA and H2O2. A dose-dependent increase in H2O2 levels and a minor increase of MDA levels (around 9–15%) were measured when C. reinhardtii cells were treated with concentrations in the range of LD20–LD80 (0.03–0.11 mM). Analyzing the kinetics of MDA and H2O2 in pea leaves, the most pronounced effect of concentration was shown for 2.7 mM. A decrease in the photosynthetic pigments was detected in the two experimental designs – short-term on C. reinhardtii and long-term on P. sativum treatments. The pro-oxidative potential was also proven in S. cerevisiae based on increased levels of MDA and superoxide anions and decreased GSH. New information is gained that PbCl2 can affect the DNA molecule and photosynthetic pigments via induction of oxidative stress. Our study revealed that the magnitude of stress response towards PbCl2 is genotype-specific. Our finding that Chlamydomonas reinhardtii is a sensitive test system towards PbCl2 contributes to good strategies for revealing very low levels of contaminants present chronically in main environmental matrices. This is the first report, as far as we know, affirming that PbCl2 can induce DSBs in Chlamydomonas reinhardtii and Saccharomyces cerevisiae. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:04 +030
       
  • Distribution of microbial abundance in long-term copper contaminated
           soils from Topolnitsa-Pirdop valley, Southern Bulgaria

    • Abstract: BioRisk 20: 23-35
      DOI : 10.3897/biorisk.20.97795
      Authors : Michaella Petkova, Nadezhda Nankova, Viktoriya Kancheva, Silvena Boteva, Anelia Kenarova, Galina Radeva : This study presents the distribution of bacterial and fungal abundances in long-term copper (Cu) contaminated soils in Topolnitsa-Pirdop valley – a highly industrialized zone with a number of mines and processing plants for copper and other non-ferrous metals. The bacterial (16S rRNA gene copies) and fungal (ITS rRNA gene copies) were estimated using quantitative PCR technique in five topsoils, differently Cu contaminated (ranging from 28.05 to 198.9 mg kg-1). Bacterial abundance varied in a range of 1.68 × 1011 to 3.24 × 101116S rRNA genes, whereas fungi amounted from 1.95 × 108 to 6.71 × 108 ITS rRNA genes. Fungal and bacterial abundances were significantly (fungi) and insignificantly (bacteria) influenced by Cu contamination. The fungal/bacterial ratio related negatively with soil Cu, which shifted microbial communities’ structure towards bacterial dominance. Since the ratio between bacteria and fungi are vital in explaining many soil functions, the calculated changes in this ratio indicated deterioration in soil quality, being of primary importance for plant production. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:03 +030
       
  • Does overproduction of chaperone proteins favour the repair of DNA
           injuries induced by oxidative stress' (Mini review)

    • Abstract: BioRisk 20: 7-22
      DOI : 10.3897/biorisk.20.97569
      Authors : Stephka G. Chankova, Nadezhda P. Yurina, Teodora I. Todorova, Petya N. Parvanova : Genotype resistance to oxidative stress, induced by various physical/chemical stimuli has been the focus of scientists for the last decades, with several aspects – ecological (the formation of the genetic elite of population), agricultural and medical (radio-chemotherapy). Genotype resistance to oxidative stress is regarded as the integration of different morphological, physiological, biochemical, metabolic and genetic characteristics. Currently, it is supposed that the mechanisms involved in the formation of genotype resistance to oxidative stress are inter-correlated and inter-dependent, comprising changes in genes, proteins, enzymes, different metabolic pathways and/or biological networks. According to the present state of knowledge, various cellular targets, resulting in genotoxic stress, induction of DNA damage, mutations, genomic instability or apoptosis can trigger different signal transduction pathways, activating DNA repair, antioxidant and chaperone defence systems. Till now, a lot of experimental data have been accumulated concerning the contribution of DNA repair to the formation of genotype resistance to oxidative stress. At the same time, genotype resistance of organisms is largely determined by the ability of molecular chaperones to maintain conformational homeostasis of proteins (folding – misfolding – refolding or aggregation – degradation). The role of chaperones in protein homeostasis and cell death, especially in apoptosis, is well discussed in literature, but much less is known about their function in DNA repair. In this regard, here we addressed the question of whether the overproduction of chaperone proteins contributes to the repair of DNA damage caused by oxidative stress. HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:02 +030
       
  • International Seminar of Ecology – 2022

    • Abstract: BioRisk 20: 1-5
      DOI : 10.3897/biorisk.20.104660
      Authors : Kalina Danova : HTML XML PDF
      PubDate: Mon, 15 May 2023 20:00:01 +030
       
  • Potential risk resulting from the influence of static magnetic field
           upon living organisms. Numerically simulated effects of the static
           magnetic field upon fatty acids and their glycerides

    • Abstract: BioRisk 19: 1-24
      DOI : 10.3897/biorisk.19.96250
      Authors : Wojciech Ciesielski, Henryk Kołoczek, Zdzisław Oszczęda, Jacek A. Soroka, Piotr Tomasik : Background: We attempt to recognise the effects of static magnetic field (SMF) of varying flux density on flora and fauna. For this purpose, the influence of static magnetic field is studied for molecules of octadecanoic (stearic), cis-octadec-9-enoic (oleic), cis,cis-octadec-9,12-dienoic (linoleic), all cis-octadec-6,9.12-trienoic (linolenic), trans-octadec-9-enoic – (elaidic), cis-octadec-11-enoic (vaccenic) and all trans-octadec-6,9,12-trienoic (trans-linolenic) acids as well as 1- and 2-caproyl monoglycerides, 1,2- and 1,3-caproyl diglycerides and 1,2,3-caproyl triglyceride. In such a manner we attempt to develop an understanding of the interactions of living cells with SMF on a molecular level. Methods: Computations of the effect of real SMF 0.0, 0.1, 1, 10 and 100 AMFU (Arbitrary Magnetic Field Unit; here 1AMFU > 1000 T) flux density were performed in silico (computer vacuum), involving advanced computational methods. Results: SMF polarises molecules depending on applied flux density It neither ionises nor breaks valence bonds at 0.1 and 1 AMFU. In some molecules under consideration flux density of 10 and 100AMFU some C-H and C-C bonds were broken. Some irregularities were observed in the changes of positive and negative charge densities and bond lengths against increasing flux density. They provide evidence that molecules slightly change their initially fixed positions with respect to the force lines of the magnetic field. The length of some bonds and bond angles change with an increase in the applied flux density providing, in some cases, polar interactions between atoms through space. Conclusions: SMF destabilizes lipid acids and caproyl glycerides irregularly against increasing flux density. That irregularity results from the ability of those molecules to twist out of the initially established SMF plain and squeeze molecules around some bonds. In some molecules SMF flux density of 10 AMFU and above breaks some valence bonds and only in case of elaidic acid the trans-cis conversion is observed. Depending on the structure and applied flux density SMF either stimulates or inhibits metabolic processes of the lipids under study. HTML XML PDF
      PubDate: Mon, 6 Mar 2023 17:29:21 +0200
       
 
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