Roumiana Metcheva

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria II: chromosomal aberrations and blood pathology.

Heavy metal content was monitored in small mammals inhabiting mountain ecosystems and two industrial polluted regions in Bulgaria. Rodents (Microtus arvalis, M. rossiaemeridionalis, Clethrionomys glareolus, Pitymys subterraneus, Chionomys nivalis, Apodemus flavicollis, A. sylvaticus, and Mus macedonicus) were used as zoomonitors. Pathological changes in chromosome status, hematological indices, and blood cell morphology were analyzed in the context of heavy metal bioaccumulation. Significant correlations were obtained between the heavy metal load of zoomonitors and the frequency of chromosomal aberrations and pathological changes in erythrocytes (mainly micronuclei and basophilic granulations). It is suggested that mercury is a strong damaging factor for chromosomes and red blood cell apparatus.

Bioaccumulation and damaging action of polymetal industrial dust on laboratory mice Mus musculus alba: I. Analysis of Zn, Cu, Pb, and Cd disposition and mathematical model for Zn and Cd bioaccumulations☆

The concentrations of Zn, Cu, Pb, and Cd in the liver, kidneys, spleen, bones, and carcass of laboratory mice BALB/cy were observed in toxicological experiments. Polymetal industrial dust containing these metals was given to experimental animals at 1% concentration mixed with conventional animal food. Samples for analyses were taken on Days 15, 40, 60, 90, and 120 posttreatment. The experimental data clearly support the established antagonistic interactions among cadmium, zinc, copper, and lead. A mathematical model was proposed to study the main tendencies of heavy metal bioaccumulation under conditions of metal interaction and excessive exposure. The experimental results were assessed on the basis of the model. A rate constant of renal excretion greater than that of hepatic excretion was obtained, which agrees with the observed inversion of cadmium kidney/liver ratio in the conditions of very high exposure.

Bioaccumulation and damaging action of polymetal industrial dust on laboratory mice Mus musculus alba II. Genetic, cell, and metabolic disturbances☆

An ecologo-toxicological experiment was carried out with laboratory mice Mus musculus alba of the inbred line BALB/c. The experimental animals (male and female) were exposed for 120 days to polymetal industrial dust containing zinc, copper, lead, and cadmium, which was mixed with conventional animal food. Chromosome aberration frequency and pathological changes in hematological indices, oxygen consumption, body temperature, and body weight were studied in the context of heavy metal bioaccumulation and interactions. Samples for analyses were taken on days 15, 40, 60, and 90. An increased frequency of chromosome aberrations (up to 22%), lead-induced anemia, and significant decreases in body temperature were observed. A strong correlation between hemoglobin content and oxygen consumption (O2/g h) was established. An increase in hematocrit, accompanied by a loss of body weight after day 60, suggests dehydration resulting from lead and cadmium poisoning.

Modified Natural Clinoptilolite Detoxifies Small Mammal’s Organism Loaded with Lead I. Lead Disposition and Kinetic Model for Lead Bioaccumulation

Zeolites, especially clinoptilolites, have wide application in removing heavy metals from different solutions and wastewater. The detoxification capacity of the clinoptilolite sorbent KLS–10-MA, a modified natural Bulgarian zeolite, applied as a food supplement in conditions of an ecotoxicological experiment with conventional food and lead was demonstrated for the first time. Laboratory mice, inbred imprinting control region strain, were used in a 90-day ecotoxicological experiment. Animals were divided into four experimental groups. Lead bioaccumulations in exposed and non-supplemented/supplemented with KLS–10-MA animals were compared. As additional control, healthy animals non-exposed to Pb were fed with conventional forage mixed with 12.5% KLS–10-MA. The dietary inclusion of the sorbent reduced Pb concentrations in exposed and supplemented mice by 84%, 89%, 91%, 77%, and 88% in carcass, liver, kidneys, bones, and feces, respectively. A mathematical model was proposed to outline the common trends of bone Pb bioaccumulation in exposed and non-supplemented/supplemented animals. Characteristic parameters of the kinetics of Pb concentrations were determined. Based on the model, the coefficient of absorption of Pb by gastrointestinal mucosa in the supplemented mice was found—η = 3.53% (versus η = 15% in non-supplemented ones). The present study clearly indicates that there is a realistic perspective to create a new drug based on modified natural clinoptilolites in cases of chronic heavy metal intoxication, without negatively affecting the environment.

A comparative analysis of the heavy metal loading of small mammals in different regions of Bulgaria: I: monitoring points and bioaccumulation features

Data on liver and body copper, zinc, lead, and cadmium content of small mammals (rodents and insectivorous) were collected and analyzed. Data comparisons were performed in two aspects: (1) points and years of monitoring; (2) monitor species bioaccumulations. Specific bioaccumulation features were observed in some of the monitor species. A method for comparative evaluation of heavy metal loads in the different species is proposed using data for liver and body contamination. The loads of Clethrionomys glareolus and Apodemus flavicollis were compared, and the data are in agreement with data from other authors in Central Europe. A correlation between heavy metal content in the food and liver of snow vole was established. The data demonstrate that two of the regions investigated in Rila Mountain National Park could be assumed to be background locations. Some possible reasons for the heavy metal contamination of the low-altitude region in Rila are discussed. Not very significant pollution was observed around industrial facilities. Correlations between heavy metal levels in zoomonitors and meteorological factors were established.

Studies of Antarctic Yeast Isolates for Exopolysaccharide Synthesis

ABSTRACT 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.

Salmonella Presence—An Indicator of Direct and Indirect Human Impact on Gentoo in Antarctica

ABSTRACT Antarctica remains one of the last areas, where direct human impact is limited. Compared to the rest of the world Antarctic environment could be considered as unpolluted. This explains the significant scientific interest to the effects of touristic activities, and especially during the last decade due to the increased number of tourists visiting diverse parts of the continent. The role of human activity for Salmonella presence in penguins remains unclear. The aim of the present study was to contribute to the knowledge to what extend Salmonella presence in penguins interstitial fauna might be used as an indicator of direct or indirect human impact on the Antarctic ecosystem, by investigating three Gentoo colonies, subjected to different levels of human impact. 16 individual fecal samples were taken per each Gentoo colony. The potentially pathogenic Salmonella typhimurium/enteridis occurred in both studied populations at King George Island at the rates 37,5% and 18,8% respectively, or at rates 85,7% and 60,0% of the positive for Salmonella sp. samples respectively. Unlike both populations at Admiralty bay, King George Island, all samples taken from the Caleta Argentina population at Livingston Island were positive neither for both pathogenic species nor for Salmonell sp.

Application of an Advanced Closed Respirometer for small Mammals

ABSTRACT Metabolic rates (MR) are important components of the energetic budget of the animals. To estimate different types of MR diverse specific apparatuses have been developed. They suffer high speciation in particular MR or are extremely expensive. We propose an closed respirometer being cheap and capable for precise long and short time measurements at the same time, and thus providing possibilities for assessing the whole set of MR. The abilities of the respirometer are demonstrated on the example of the Resting Metabolic Rate (RMR) in Apodemus mystacinus adapted to different climatic conditions.