Roumiana Metcheva - Academia.edu (original) (raw)

Papers by Roumiana Metcheva

BioRisk, Apr 21, 2022

The problem of environmental pollution is becoming increasingly important on a global scale. Man ... more The problem of environmental pollution is becoming increasingly important on a global scale. Man has oversaturated the environment of his habitat with harmful and most often toxic waste. It is difficult to describe all the toxic substances, as a separate book can be written for each group. The term "ecocide" has been introduced, which reflects large-scale destruction of the natural environment. We will focus only on three classes of pollutants that are of particular concern, creating environmental conflicts. These are: • Pesticides are extremely toxic and create large amounts of non-degradable waste. It accumulates in tissues and organs of target organisms, becoming toxic and causing serious pathological changes in the body, mainly at the cellular and subcellular levels, causing various diseases and as a result, serious changes in the structure and functions of the populations and the whole ecosystem are increasingly observed. • Waste from the nuclear industry and radioactive fallout from nuclear explosions. It is especially dangerous that radioactive elements can be concentrated in certain organs. • Petroleum products-often large quantities end up in the seas and oceans, along with industrial waste of various kinds, impossible to compensate for by nature and they pose a serious threat to ecosystems, many of which have already been destroyed. At the submolecular level, chemical and physical effects can lead to genetic rearrangements (mutations); destructive ionization in the tissues of every living being, sometimes with completely unexpected consequences for humans.

As a typical mesic and middle-sized rodent the broad-toothed mouse (Apodemus mystacinus) has eco-... more As a typical mesic and middle-sized rodent the broad-toothed mouse (Apodemus mystacinus) has eco-physiologic characteristics, which imply a nonperfect thermoregulation, being vulnerable to thermal stress at temperatures above and below a narrow optimal temperature range. In this work we test the hypothesis that its northern populations live in physiologic stress conditions. Our results reveal that its thermo-neutral zone (TNZ) is a conservative characteristic and it has elevated levels of the resting metabolic rate (RMR) during spring and we conclude that those two features may explain the absence of more northern distribution of the species.

Russian Journal of Ecology, 2018

A flow of matter and energy through two mice populations is presented. An estimation of their inf... more A flow of matter and energy through two mice populations is presented. An estimation of their influence on the production of alfalfa field (Medicago sativa, L.) was also done. Two sinthopic mice species from genus Mus - Mus musculus musculus (Linnaeus, 1758) and Mus spicilegus (Petenyi, 1882) in Northern Bulgaria are the object of the present work.

In: Nikolova M (Ed). Scientific reports: Scientific conference "30 years of Rila National Park " - A challenge for future generations 03 June 2022, 61-68. Directorate of the National Park “Rila”, Blagoevgrad, Bulgaria. ISBN 978-619-90533-8-6, 2022

Rila National Park is the largest national park in Bulgaria with the highest peak on the Balkan P... more Rila National Park is the largest national park in Bulgaria with the highest peak on the Balkan Peninsula (Moussala - 2925 m.a.s.l.). Small mammals, 25 species of which occur in the park, are an important part of the mountain ecosystems. Between 1994 and 2020, 5 localities in the park were investigated and the presence of 13 species of small mammals were documented. Considering the scarce literature data on the small mammals’ communities in Rila mountain, the detailed information for these studies, presented in the current work, is especially valuable. Although some of them have a high conservation status, standardised monitoring has been carried out only for one species – the European ground squirrel, Spermophilus citellus. The potential threats are also commented and possible conservation measures are given.

Lead and cadmium are long established toxic and carcinogenic metals. Still, the mechanisms of the... more Lead and cadmium are long established toxic and carcinogenic metals. Still, the mechanisms of their interaction with eukaryotic DNA are not unequivocally understood. New data provide evidence on the influence of both metals on DNA repair, particularly non-homologous end joining (NHEJ) and mismatch repair (MMR). This may help explain the weak direct mutagenicity of both Pb2+ and Cd2+ ions in the Ames test, as opposed to the proven carcinogenicity of both metals; it has long been proposed that lead and cadmium may induce an imbalance in mammalian systems of DNA damage repair and promote genomic instability. While new evidence for mechanistic interactions of metals with DNA repair emerges, some of the old questions involving dose distribution, pathways of exposure and bioaccumulation/detoxification kinetics still remain valid. To help place the current state of the art in the genetic toxicology of lead and cadmium within the context of ecotoxicology, the current authors propose an inte...

Science of The Total Environment, 2006

Concentrations of biogenic and toxic elements (Na, K, Mg, Ca, P, S, Fe, Cu, Zn, Co, Mn, Se, Ni, S... more Concentrations of biogenic and toxic elements (Na, K, Mg, Ca, P, S, Fe, Cu, Zn, Co, Mn, Se, Ni, Sr, Al, Cd, Pb, As) were determined for the first time in feathers of gentoo penguin (Pygoscelis papua) and chinstrap penguin (Pygoscelis antarctica) from Antarctica. A comparison of element levels was performed among these species in years 2002-2003. Penguins molt annually and this fact allows defining precisely the concentrations of accumulated toxic elements and heavy metals in plumage every year. A continual environmental biomonitoring could establish a possible trend to contamination of the Antarctica sea zones. The penguin feather is an excellent subject for monitoring because penguins have long life span, permanent ecological niche and dominate the aviafauna in Antarctica. Because of its remoteness, Antarctica is believed to be unpolluted. The relatively elevated levels of Cd established are due to the Cd-enrichment of the Antarctic marine food chain. Because of great bioaccumulation of lead in feathers, the concentration of Pb in penguin feather was higher (4-8 times) compared to that of Cd. In both penguin species the levels of Zn were 1.9 times higher than respective Fe levels. The concentrations of most of the investigated elements were significantly higher in P. papua than in P. antarctica and this probably could be explained by the different diet and feeding habit of these species.

Marine …, 2008

The present study also seeks to determine if this "yellow spot" on the Gentoo bill is sex-or age-... more The present study also seeks to determine if this "yellow spot" on the Gentoo bill is sex-or age-dependent. METHODS Populations studied Field measurements were carried out on adult, non-moulting and moulting Gentoo Penguins, inhabiting Livingston Island (62°38′ S,

Biological Journal of the Linnean Society, 2021

We used inter-simple sequence repeats and inter-retrotransposon amplified polymorphism markers to... more We used inter-simple sequence repeats and inter-retrotransposon amplified polymorphism markers to assess genetic variation in Deschampsia antarctica populations in the context of its uneven distribution in the northern and central maritime Antarctic. Genetic diversity and population structure and differentiation were assessed in nine populations from geographically isolated population groups of D. antarctica, including the South Shetland Islands, Anvers Island and the Argentine Islands regions. In total, 265 amplified DNA fragments were scored, of which 220 (83.0%) were polymorphic. The total sample showed low genetic diversity (unbiased expected heterozygosity = 0.081 and Shannon diversity index = 0.115) and high population differentiation (molecular variance among populations = 0.659). We also found a trend toward a decrease in genetic diversity and an increase in population differentiation toward the southern edge of the species range. Principal coordinates analysis of polymerase...

The importance of Alpine ecosystems is increasing due to the influence of a wide number of ecolog... more The importance of Alpine ecosystems is increasing due to the influence of a wide number of ecological factors. Atmospheric attenuation of solar radiation, particularly in the ultraviolet spectra, is decreasing, leading to higher surface exposure and higher doses in plants and diurnal animals. At the same time, exposure to man-made radionuclides in the high mountains in Europe is decreasing due to the radioactive decay of anthropogenic radioisotopes, as well as the sedimentation and de-mobilization of heavier elements, which reduce exposure of the Alpine biota to technogenic emitters. The current article is based on biomonitoring studies of wild small mammals, conducted on Rila Mountain in the period 1993-2020. Total β-activity was measured with the use of a low-background beta counter (LAS 3A level activity system with 30% efficiency on 40K). A reduction by a factor of 10 was observed over a two-decade time period, attributable in part to the decay of deposited anthropogenic β-emitt...

The Toxicity of Environmental Pollutants [Working Title]

Radionuclide contamination poses serious hazards for terrestrial ecosystems. Beyond the readily a... more Radionuclide contamination poses serious hazards for terrestrial ecosystems. Beyond the readily apparent damage to the biota at high doses, low doses of ionizing radiation produce stochastic effects: mutation, carcinogenesis, and genomic instability. The proposed chapter is a review of the biological and ecological effects of radionuclides. The authors discuss, beyond the Chernobyl accident, other contamination events. The review includes the biological and ecological effects of the three principal technogenic contaminants in terrestrial ecosystems: Cs-137, Sr-90, and I-131. Ecological risks to terrestrial small mammals are assessed in detail. In addition, the chapter provides some of the lesser-known methods of remediation and detoxification, including the use of modified natural zeolites as environmental remedies and bio-sorbents. Presented herein is little-known information on environmental protection against radioactive contamination.

BioRisk

The present investigation analyzes the literature about the toxicity of Cd and Pb in small rodent... more The present investigation analyzes the literature about the toxicity of Cd and Pb in small rodents’ organisms and the role of natural zeolites as modifiers of the biological effects. An array of ecotoxicological, morpho-physiological, hematological, genetic and biochemical methods as most representative are under discussion as a basic point for further exploration of biological effects in laboratory mice. The review of existing results demonstrated that there is abundant data on the sorption of lead and cadmium by modified natural zeolites in water and soils. Nevertheless, there is insufficient data on the ion exchange capacity and biological effects of this sorbent in living organisms, especially regarding Cd detoxification. On the basis of the current review, it is possible to conclude that future investigations in this field will elucidate the potential of the use of zeolites as successful detoxifiers against heavy metals and other toxic elements in living organisms.

The significant part of the clear from snow and ice shores of Livingston Island (South Shetlands)... more The significant part of the clear from snow and ice shores of Livingston Island (South Shetlands), distribution and abundance of birds were studded during the austral summer of 2004. In the region of South Bay 9 nesting bird species were encountered of a total abundance of 6604 pairs. Two penguin species constituted 97.2% of bird community following by petrels (1.2%) and turns (0.5%).

Biological Trace Element Research, 2010

The Pb, Cd, Cu, Zn, and Mn contents of the liver, spleen, muscle, bones, scales, gills, and the w... more The Pb, Cd, Cu, Zn, and Mn contents of the liver, spleen, muscle, bones, scales, gills, and the whole body of 3-to 7-year-old notothenioid Antarctic cod (Notothenia coriiceps, Richardson, 1844) were measured. The highest heavy metal concentrations obtained are as follows: Cd in liver, the mean value was 1.36 ± 0.19 mg/kg dry weight (wt); Pb and Zn in spleen, the mean values were 3.33 ± 0.86 and 143.97 ± 16.17 mg/kg dry wt, respectively; Cu in gills, 3.76 ± 1.16 mg/kg dry wt; and Mn in scales, 14.80 ± 4.77 mg/kg dry wt. The comparison with the data reported up to now shows that the metal concentrations varied within relative wide ranges. These first data obtained could be used as a baseline to investigate further relationships among metal contents in fish, their diet, and habitat.

Canadian Journal of Zoology, 2012

Gentoo Penguins ( Pygoscelis papua (J.R. Forster 1781)) are defined morphologically as a single s... more Gentoo Penguins ( Pygoscelis papua (J.R. Forster 1781)) are defined morphologically as a single species with a northern and southern subspecies. Differences in nuptial displays and particularly mating calls, however, suggest isolation among island archipelagos of different ocean basins. We thus asked whether genetic divergence of populations could be confirmed using molecular markers. A phylogenetic tree was constructed from a sample of 110 Gentoo Penguins and 58 haplotypes from the control region of the mitochondrial DNA. Reanalyses of historical data on morphology were conducted to construct additional phylogenetic trees for comparison. In agreement with differences in mating calls, the phylogenetic tree that was based on mitochondrial DNA showed a deep division between populations in the Indian and Atlantic oceans. The current systematic division into two subspecies based on morphology was not supported. The division between populations in the Indian and Atlantic oceans was great...

Biotechnology & Biotechnological Equipment, 2009

From Antarctic samples were obtained yeast isolates that were investigated for exopolysaccharide ... more From Antarctic samples were obtained yeast isolates that were investigated for exopolysaccharide synthesis. The screening process revelated that significant number of psychrophilic yeasts had the ability to produce biopolymers.Perspective strains were selected. A physico-chemical analysis of Antarctic samples was made.

ABSTRACT. Chemical pollution of ecosystems resulting from human activity is an ecological factor ... more ABSTRACT. Chemical pollution of ecosystems resulting from human activity is an ecological factor in the living world, affecting individuals, populations, communities and ecosystems as a whole. This laboratory investigation studied the toxic effects of polymetal ferosilicic dust on Microtus guentheri (Rodentia, Mammalia), measuring path-ological changes in blood components (haemoglobin, erythrocyte, leucocyte and platelets number, erythrocyte sedi-mentation rate (ESR) and white cell count). Biochemical indices were established for levels of the following blood components: blood sugar, albumin, uric acid, triglycerides, cholesterol, total protein, creatinine, calcium and inor-ganic phosphorus. The results obtained indicate that Microtus guentheri can be used as a species for evaluation of the influence of polymetal dust emission. KEY WORDS: Microtus guentheri, industrial polymetal dust, bioindication, biochemical and haematological indices

Acta Zoologica Bulgarica, 1998