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Ghrelin is a hormone that stimulates appetite and its serum levels are inversely proportional to body weight. Decreased ghrelin levels correlate with obesity, insulin resistance and elevated blood pressure, which are components of the metabolic syndrome (MetS). The effect of physical exercise is studied mainly after an already induced MetS, the results are contradictory and it is not clear what the effect of exercise on ghrelin concentration is. There are no data for gender comparisons of changes in ghrelin due to submaximal training. In this study, we aimed to determine the effect of submaximal training on serum ghrelin concentrations during the dietary induction of MetS in female and male rats. Dietary-manipulated female and male Wistar rats (n = 32) were used. They were divided into four groups: male and female sedentary (MD and FD) and male and female trained on treadmill (MDT and FDT). For 16 weeks, the four groups received high-fat high-carbohydrate (HFHC) food and both MDT and FDT simultaneously with the diet were subjected to submaximal training (70-75% VO2max). At the end of the experiment, mixed blood was collected and ghrelin concentrations were measured. The submaximal training and gender had a significant main effect on ghrelin levels, as trained dietary-manipulated rats had higher serum concentrations compared to the sedentary (p < 0.05) and males had higher concentrations compared to females (p < 0.05). Overall, applied for 16 weeks, simultaneously with the combined HFHC diet, the submaximal training had a positive effect, lowering the serum ghrelin concentration. Sexual dimorphism, characterised by higher ghrelin in male rats, was also found. [ABSTRACT FROM AUTHOR]

Sustainable development is based on three pillars: sustainable economic growth, social well-being and environment protection. Sustainable rural development is regarded as a multidimensional concept including an equitable and balanced development within a rural area, an increased level of social cohesion and equitability, as well as the assuming of responsibility for using natural resources and revealing at environmental protection. The studied region is located into the Strandzha Mtn - the only Bulgarian territory included in the five priority territories for conservation in Central and Eastern Europe. We have identified some core problems that should be addressed aiming to achieve the sustainable development of this area. Some of them are as follows: the absence of developing projects and focus on the development of individual villages, the lack of willingness of local people to cooperate, local resources are not effectively used and the local community is not adequately involved. [ABSTRACT FROM AUTHOR]

The present laboratory study (96 hours and 30 days) aimed to provide for the first time the possible adverse effects of different concentrations of PBDEs congers (PBDE 28, PBDE 47, PBDE 99, PBDE 100, PBDE 153, PBDE 154) based on Water Framework Directive 2000/60/EC (WFD) in zebra mussel (Dreissena polymorpha Pallas, 1771). Therefore, we analysed the gill histochemical structure by applying the Periodic acid-Schiff staining method to assess the exposed individuals' physiological status and linked them to the tested PBDEs concentrations in the contaminated water. [ABSTRACT FROM AUTHOR]

In the present study, results are presented regarding the negative effects of different concentrations of three classes of pesticides - an insecticide, herbicide and fungicide on one relatively uncommon, but reliable histochemical biomarker in the field of fish toxicology - lipid accumulation in the liver of common carp under laboratory conditions. [ABSTRACT FROM AUTHOR]

Topolnitsa Reservoir is located in a region of Bulgaria rich in copper mines where intensive mining has been ongoing for several decades. General data on the ecological status of the reservoir and the effects of metal on fish is relatively scarce. The first aim of the study was to measure the concentrations of six metals (As, Cd, Cu, Ni, Pb and Zn) in water samples and in the gills of European perch (Perca fluviatilis L.). The second objective was to examine gill structure and determine the severity of histological alteration as a result of metal exposure. Surface water and fish gill samples were collected in spring, summer and autumn in 2012 and metal and histological analyses were performed. Metal concentrations in the water samples varied, but only Cu concentrations were determined in all three seasons and they were higher than the maximum permissible levels. The gill metal concentrations were significantly higher (P

This review aims to summarize the possibility of using mussels (Mytilus spp.) as bioindicators to assess aquatic pollution in the Black Sea in Bulgaria. In addition, the main responsive biomarkers that could be applied to study the negative effects of different toxicants on these species in terms of using the Marine Strategy Framework Directive and implementation of environmental quality standards (EQS) in marine biota are also discussed. A specific reference is made to plastic pollution, transplant mussel caging, and mussel watch programs - their application, challenges, and future perspectives in Bulgaria. [ABSTRACT FROM AUTHOR]

Human infertility affects millions of people of reproductive age worldwide and impacts their families and communities. Approximately half of the cases of childless couples are due to problems with male fertility (male factor). In this review, a complex of factors that affect the quality of male fertility is presented. Particular attention is paid to the main factors in the organism representing endogenous factors and to the influence of the professional environment and lifestyle, which represent the exogenous factors. In regard to the exogenous factors, it is important to establish the effect of different environmental factors, such as air pollution, presence of various contaminants, such as chemicals, pesticides, and heavy metals, radiation, etc. The exogenous factors also include lifestyle features such as intake of alcohol, smoking, drugs, hazards in the professional working environment, social and psychological aspects, etc. Moreover, with reference to the impact of harmful effects in the professional work environment, the negative factors could be the increased levels of the radiation fund, temperature fluctuations, dustiness, immobility and sitting in the same place for a long time, etc. Obesity and dietary disorders are also associated with the expression of the male factor. In conclusion, it is suggested that for the definition and implementation of adequate and correct treatment of the problems with male fertility, the whole complex of factors should be considered in order to achieve the best results in the procedures associated with in vitro fertilization (IVF). [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the current contamination status of Topolnitsa Reservoir, which is located in a region with intensive copper mining. The reservoir has been continually contaminated with metals over the last few decades. As, Cd, Cu, Ni, Pb, and Zn concentrations were measured in surface water samples and in the liver of common rudd, Scardinius erythrophthalmus (L.), in three different seasons: spring, summer, and autumn. The morphological structure of the fish liver was examined and the hepatic LDH, ALAT, and ASAT activities were measured. In general, metal concentrations in the water varied, but As and Cu were present in all three seasons at levels higher than the maximum permissible levels set by law. The metal concentrations in the fish liver were significantly higher than in the water. Histological alterations were classified as degenerative changes (granular, vacuolar, hydropic, and fatty degeneration), necrotic changes (necrobiosis) - karyopyknosis, karryorehsis, and karyolyzis, and necrosis)); and changes in blood vessels (hyperemia in sinusoids and major blood vessels). Higher LDH, ALAT, and ASAT activities in fish livers were measured in comparison to reference fish. In addition, the ALAT activity in the livers of S. erythrophthalmus from Topolnitsa Reservoir was significantly higher in the summer. Overall, it can be concluded that the metal-contaminated waters of Topolnitsa Reservoir lead to negative changes in the common rudd tissues at the cellular level including impaired structure and enhanced enzymatic activity in the fish liver.

The present pilot laboratory study (96 hours and 30 days) aimed to provide for the first time the possible adverse effects of different concentrations of PBDEs congers (PBDE 28, PBDE 47, PBDE 99, PBDE 100, PBDE 153, PBDE 154), based on Water Framework Directive 2000/60/EC (WFD) in Zebra Mussels (Dreissena polymorpha Pallas, 1771). Thus, we calculated different condition factors based on the mussel's weight and length to determine the possible adverse effects of acute and subchronic exposure to PBDEs under laboratory conditions. [ABSTRACT FROM AUTHOR]

The 21st century has seen the realization that people have overused plastic. Unfortunately, plastic pollution is a widespread environmental problem in many of the world's rivers and seas. Plastic litter is well distributed in shallow as well as in deep-waters, and therefore it is inevitably present in the world's ocean which is in turn the final sink of plastic debris of all sizes, alongside other various anthropogenic toxicants (for example, heavy metals and persistent organic pollutants). The negative effects of microplastics (MPs) which are produced by the breakdown of larger plastic debris on aquatic organisms, including both freshwater and marine fish have been already well documented. However, there is a gap in the knowledge from studies conducted in the field or under laboratory conditions in Bulgaria. [ABSTRACT FROM AUTHOR]

Microplastic (MPs) pollution and its negative effects is a growing, yet poorly studied problem in Bulgaria. In the present review we aimed to summarize the available data on MPs contamination of surface waters and sediments, and its impact on aquatic animals in Bulgaria. [ABSTRACT FROM AUTHOR]

A number of characteristics make fish excellent experimental models in toxicological research, especially for the contamination of aquatic systems. The main aim of the present study was to investigate the negative effects of different classes of pesticides (insecticide, herbicide and fungicide), based on their LC50 on the gills histological architecture of common carp (Cyprinus carpio Linnaeus, 1758). The effects of the tested pesticides on fish gills were expressed with histopathological alterations, such as proliferative, degenerative and changes in the circulatory system. Based on our results, the test insecticide showed higher toxicity with more severe irreversible necrotic changes in common carp gills compared to the herbicide and fungicide exposure. The identified histopathological changes in the fish gills can be successfully applied as reliable biomarkers for monitoring the degree of negative effects on the organisms due to the pesticide toxicity. The results from such experiments could be applied in the legislation in order to protect the water bodies from pesticide contamination, in areas with intensive application of plant protection products used in agricultural practices. [ABSTRACT FROM AUTHOR]

Nowadays pollution of aquatic ecosystems with pesticides causes acute and chronic poisoning of fish, leading to serious damage to vital organs, such as the liver. Common carp (Cyprinus carpio Linnaeus, 1758) is a popular edible fish favored for culture due to its rapid growth, hardiness and reproduction in confined waters. The purpose of the present study was to investigate the negative effects of cypermethrin (CYP) and chlorpyrifos (CPF), based on their maximum allowable concentrations (Directive 2013/39/EU) on histochemical and biochemical biomarkers in the liver of common carp. The histochemical analysis included Periodic acid-Shiff stainig (PAS reaction) and Sudan Black B staining, while in the biochemical study different hepatic enzyme activities such as lactate dehydrogenase (LDH), aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT). The negative effects of the tested pesticides on fish were expressed with liver changes in the amount of glycogen and lipids, and enzyme changes of LDH, ASAT and ALAT, caused by the acute and chronic exposure to cypermethrin and chlorpyrifos under laboratory conditions. The results from such experimental set ups could be used in the legislation of protection water bodies from contamination, in areas near intensive application of plant protection products and also in implementing the Directive 2013/39/EU and Water Frame Directive by using multi-biomarker approaches. [ABSTRACT FROM AUTHOR]

In this short review we aim to discuss the advantages and disadvantages of using zebra mussel (Dreissena polymorpha Pallas, 1771) for the purposes of freshwater monitoring. [ABSTRACT FROM AUTHOR]

In this article we report the first registered case of plastic products in fish purchased from a local fish market in the city of Plovdiv, Bulgaria. [ABSTRACT FROM AUTHOR]

The aim of the current review is to identify the most suitable biomarkers for evaluating chemical stress due to organic contamination in aquatic environments, as well as possible ways to reduce or limit this contamination. To safeguard the environmental status, the European Union has implemented the Water Framework Directive (WFD; 2000/60/EC) and the Marine Strategy Framework Directive (MSFD; 2008/56/EC) legislations, which encourage the use of biological tools to detect the quality of aquatic systems. Therefore, monitoring of sentinel fish species is widely used to assess the level of health status. Fishes have been found to be good biomonitors of water pollution because they occupy different trophic levels; they are of different sizes and ages and in comparison with invertebrates, are also more sensitive to different toxicants, including persistent organic pollutants, such as pesticides. Biomarkers are defined as responses to any exposure evidenced in histological, physiological, biochemical, genetic and behavioral modification. The application of multi-biomarker approach is necessary in the development of a protocol for the aquatic assessment of organic pollutants. This protocol can be applied in risk assessment and water monitoring programs in order to provide an adequate legal basis for the presence of organic pollutants in aquatic ecosystems and biological responses under concentrations equal or lower to those permitted under the European and Bulgarian legislation. [ABSTRACT FROM AUTHOR]

With the present experiment we aimed to study the possible negative effects of two commonly used insecticides – cypermethrin (CYP) and chlorpyrifos (CPF) on the respiration rate of Zebra Mussel (Dreissena polymorpha Pallas, 1771) after 96 hours and 30 days. We found that both chemicals altered the respiration process; however CYP was determined to be more toxic regarding this particular biological measurement. [ABSTRACT FROM AUTHOR]

Our main goal in this short review is to present the pros of using common carp (Cyprinus caprio Linnaeus, 1785) for the purposes in both, aquaculture and aquatic toxicology. [ABSTRACT FROM AUTHOR]

The present study was developed to examine the possible harmful effects, which cadmium (Cd) and polyaromatic hydrocarbons (PAHs) could cause to the gills and digestive gland of the zebra mussel Dreissena polymorpha (Pallas, 1771). For this purpose, we explored for the first time their histochemical and biochemical alterations by applying the Periodic-Schiff staining method (PAS) and analysing the catalase (CAT) and cholinesterase (ChE) activity. The mussels were exposed to different concentrations of Cd and PAHs in laboratory conditions for 96 hours (acute exposure) and 31 days (chronic exposure). These are considered as priority substances in surface waters according to Directive 2013/39/EU. Moreover, the enzymatic measurements are included as biomarkers for biota in the EU Water Framework Directive, the Marine Strategy Framework Directive and in the mussel component of the International Council for the Exploration of the Sea/Oslo-Paris convention for the Protection of the Marine Environment of the North- East Atlantic (ICES/OSPAR) integrated monitoring framework. Based on our results, we also proposed the PAS reaction as an easy, fast, low-cost and trustworthy biological tool, which could be used for biota in monitoring programs. Overall, we found alterations both in the gill structure and enzymatic activity in the digestive gland at all tested concentrations, including the one below the allowable concentration according to the EU legislation. These results confirmed the toxicity of Cd and PAHs. Furthermore, Cd was more toxic compared to PAHs in terms of the studied parameters. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) and polyaromatic hydrocarbons (PAHs) are priority pollutants in surface waters according to Directive 2013/39/EC. They are toxic, persistent and tend to accumulate in high concentrations in aquatic organisms. In the present study, zebra mussel Dreissena polymorpha was confirmed as a bioindicator for contaminated freshwater ecosystems. We aimed to study the effects of short-term (96 h) and long-term (31 days) exposure to Cd and PAHs on the Condition index (CI) and Soft Tissue Wet Ratio (STWR) in zebra mussel. Overall, we found alterations in both CI and STWR (as compared to the control group) at all tested concentrations, including the one below the allowable concentration according to the EU legislation. These results demonstrated the toxicity of both contaminants. Furthermore, we confirmed that the studied condition indices could be successfully applied as biomarkers as they are fast and low-cost in future monitoring and risk assessment of polluted freshwater ecosystems. [ABSTRACT FROM AUTHOR]

The main aim of the present study was to compare the toxicological effects of a fosetyl-Al and fenamidone based fungicide and a thiamethoxam based insecticide on the gill histological structure of bighead carp (Hypophthalmichthys nobilis Richardson, 1845) in a short-term laboratory conditions (96 hours). We used of the insecticide 6.6 mg L-1, 10 mg L-1 and 20 mg L-1 representing 30, 20, 10 times dilution, and of the fungicide -- 30 mg L-1, 38 mg L-1 and 50 mg L-1 representing 50, 40, 30 times dilution, respectively. These concentrations were considered as real applicable pesticide concentrations in plant protection practices. Overall, we found pronounced alterations in the gill histological structure such as proliferative and regressive, as well as changes in the circulatory system in the fish treated with both pesticides. The histopathological alterations indicated the negative effects of the applied chemicals on non-target aquatic species such as bighead carp. In addition, we found that, in terms of the histological lesions and tested fish species, the fungicide had more severe effects compared to the insecticide. [ABSTRACT FROM AUTHOR]

The possible negative effects of polyaromatic hydrocarbons (PAHs) and cadmium (Cd) on the lysosomal membrane stability (LMS) in haemocytes of the invasive mollusc zebra mussel (Dreissena polymorpha) were studied by applying the neutral red retention time assay (NRRT). In addition, the process of bioaccumulation of PAHs and Cd in the gills of zebra mussel was examined and the bioaccumulation factor (BFA) was calculated. The mussels were exposed to different concentrations of Cd and PAHs in laboratory conditions for 96 hours (acute exposure) and 31 days (chronic exposure). We found higher toxicant concentrations at the 24th h as well as on the 31st day compared to the other tested time periods. These results were linked with the faster lysosomal membrane destabilisation in all mussels treated with Cd and PAHs in the beginning of the experiment. [ABSTRACT FROM AUTHOR]

The main aim of the present study was to compare the toxicological effects of a fosetyl-Al and fenamidone based fungicide and a glyphosate based herbicide on the liver lipid accumulation in bighead carp (Hypophthalmichthys nobilis Richardson, 1845) in a short-term laboratory conditions (96 hours). A histochemical method with Sudan III staining was applied. We used 30 mg/L, 38 mg/L and 50 mg/L concentrations fungicide, representing 50, 40, 30 times dilution and 20 mg/L, 40 mg/L and 72 mg/L representing 70, 40, 20 times dilution of the fungicide, respectively. These concentrations were considered as real applicable pesticide concentrations in plant protection practices. Overall, we established a different degree of lipid accumulation in the fish liver. In terms to the histochemical alterations, we found that the fungicide had a more sever effect compared to the herbicide. [ABSTRACT FROM AUTHOR]

Changes in the hereditary information during the nucleus maturation of the sperm cells can occur under the influence of exogenous or endogenous factors. Exogenous factors could be linked with unfavorable working environment or bad habits. In the recent years nutritional supplements have been used for male infertility treatment. In addition, they can improve the morpho-physiological status of the sperm. The present study aims to investigate the effect of nutritional supplement PAPA on the spermatozoa chromatin maturity level by using an Aniline Blue staining test (aniline blue staining - AB) in sub/infertile men exposed to exogenous factors.. A group of men (n = 88) was examined after their written agreement and a completed questionnaire. The tested group with established diagnoses of asthenoteratozoospermia, oligoasthenoteratozoospermia, astenoteratozoospermia with hypovolemia, oligoasthenoteratozoospermia with hypovolemia took orally PAPA® supplement for three months. All patients were tested for DNA damage by an AB test twice before and after the treatment. The patients in the tested group were divided based on the type of harmful work environment (I-IV) and harmful habits (smoking I-III). The results showed that after the treatment with a nutritional supplement PAPA®, the levels of condensation or maturity of sperm chromatin increased by 16.11%. In addition, connections between the effect of treatment and the conditions of the harmful working environment, as well as the amount of received tobacco by the smokers were found. A better effect of the treatment in the tested group with the absence of harmful working environment and non-smokers was found. Therefore, the lowest treatment efficacy was found in the patients who are chronically exposed to occupationally harmful environment, associated with increased body and scrotal temperature (seated workers in factories, ect., drivers, welders, bakers, founders, heavy physical labour workers). On the other hand, a negative connection between the smoked cigarettes per day and the effect of the food supplement in the tested group of men with harmful habits, such as smoking was established. [ABSTRACT FROM AUTHOR]

The present work aimed to study the negative effects of fungicide contamination on the liver of Hypophthalmichthys nobilis (Richardson, 1845) by applying the Periodic acid – Schiff reaction (PAS). The fish were treated with increasing and real applicable pesticide concentrations in agricultureprepared according to the guidelines of the producer for a total acute period of 96 hours. Overall, we found that the intensity of the PAS staining increased proportionally with the increasing of the tested fungicide. Based on the obtained results, we consider that the PAS-staining could be successfully applied as a biomarker in toxicological research. In addition, as fungicide studies are in general less compared to the other pesticide groups, we also consider that these results could be used in future risk assessment and monitoring programs, as well as better agricultural activities. [ABSTRACT FROM AUTHOR]

The present study was designed to provide some preliminary data on the toxic effects of 96 h exposure to glyphosate on the liver of Common Carp (Cyprinus carpio L.) under ex situ conditions. For this purpose we used Sudan III staining which could be suggested as fast and low-cost histochemical biomarker for pesticide contamination effects. [ABSTRACT FROM AUTHOR]

The aim of the present study is to investigate the effects of a thiamethoxam based insecticide on the expression of lipid droplets in Common Carp, Cyprinus Carpio (Linnaeus, 1785) liver. The selected concentrations of the test pesticide were 6.6 mg/L, 10 mg/L and 20 mg/L under laboratory conditions for an acute period of 96 h. The Sudan III staining method was applied for detection of fatty degeneration in the fish hepatocytes. Overall, we found that the fat storage in the liver cells increased proportionally with the increased pesticide concentrations. The results demonstrated fat accumulation in the fish liver which in addition, could be used as an easy to perform and relatively inexpensive biological tool for studying the effects of pesticide contamination on fish. [ABSTRACT FROM AUTHOR]

EU Member states are required to apply the EU Water Framework and its Daughter Directives in order to achieve Good Environmental Status (GES) for all 11 qualitative descriptors by 2015 in all water bodies for a list of priority and specific pollutants. Therefore, environmental indicators and biological-effect techniques have to be carefully selected for the management of chemicals in the aquatic environment and for developing an integrated framework. The most commonly applied biological-effect tools are measures of the biochemical and physiological state of selected organisms, such as mussels or fish. The present article provides basic information on the EU Water Directive, the essence of biomarkers, and outlines why mussels may be the better choice of indicators in toxicological research and monitoring programs in order to study the impact of contaminants in water ecosystems. [ABSTRACT FROM AUTHOR]

In the present study our major aim was to evaluate the up-to-date contamination status of the Topolnitsa reservoir. It is located in a region with intensive copper mining, which has been constantly contaminated with metals in the last few decades. Thus, we measured As, Cd, Cu, Ni, Pb, and Zn concentrations in surface water samples, as well as, in liver of common carp in three different seasons - spring, summer, and autumn 2013. Furthermore, we also studied the carp response to the water quality by observing its hepatic morphological structure and measuring some biochemical parameters (LDH, ALAT, and ASAT activity). In general, metal concentrations in the water varied, but As, Cu and Ni were present in all the three seasons. Cu concentrations were above the maximum permissible levels set by law. Metal concentrations in the liver were significantly higher than in the water (p<0.05). In addition, we observed severe hepatic histological alterations, which included degenerative changes - granular degeneration, vacuolar degeneration, hydropic degeneration, and fatty degeneration; necrotic changes (necrobiosis) - karyopyknosis, karyorrexis and karyolysis, and necrosis; and changes in the blood vessels - hyperemia in sinusoids and major blood vessels. We found that LDH activity was inhibited in the common carp liver from the Topolnitsa reservoir compared to the reference fish, but ALAT and ASAT activity was significantly increased compared to the reference. Based on our findings we consider that the metal-contaminated waters of the Topolnitsa reservoir lead to negative changes at tissue and cellular level in the fish organism, which include altered structure and impaired functions of the liver. [ABSTRACT FROM AUTHOR]

The aim in the present study was to give some preliminary data on the effects of Cd, which is considered as priority toxic substance in surface waters according to Directive 2008/105/EO (2008) on the lysosomal membrane stability and respiration rate in two invasive and resilient to changes in the surrounding media freshwater mollusks - Chinese pond mussel (Synanodonta woodiana) and zebra mussel (Dreissena polymorpha) in laboratory conditions for 72 hours. Significant decrease in the lysosomal destabilization indices with lower retention time and increase in the respiration rate index were observed in the treated with Cd mussels, compared with the control. In general, the tested species proved to be sensitive to Cd exposure in terms of the two studied biomarkers. [ABSTRACT FROM AUTHOR]

The main purpose of the present study was to provide some preliminary data on the effects of Cd, which is considered as priority toxic substance in surface waters according to Directive 2008/105/EO on the gill structure and respiration rate of common carp (Cyprinus carpio L.) under ex situ conditions. We observed significant histological changes, which were grouped as proliferative and degenerative ones, as well as increase in the respiration rate index in the treated with Cd fish, compared with the control. In general, the tested fish species proved to be sensitive to Cd exposure in terms of the studied parameters. [ABSTRACT FROM AUTHOR]