Comparative study of the genotoxic response of freshwater mussels Unio tumidus and Unio pictorum to environmental stress

Genotoxic response of freshwater mussels U. tumidus and U. pictorum to environmental stress was studied using comet assay on hemocytes and gill cells. The mussels were acclimated to controlled laboratory conditions for 10 days, and then exposed at 4 sites in the Sava and Danube rivers in the area of the city of Belgrade. Samples of each species were taken after 7, 14, and 30 days of exposure. The mussels sampled immediately after acclimation served as controls. Genotoxic response in both species was induced earlier at sites receiving untreated wastewaters from the city’s main collectors (7 days), than at the site receiving only domestic wastewaters from small settlements located upstream from the city (30 days). There was a correlation between the comet tail intensity values in tissues of exposed mussels and the concentrations of zinc, copper, iron, and arsenic at the exposure sites. The genotoxic responses in both tissues of U. pictorum and in hemocytes of U. tumidus were similar, while U. tumidus gill cells failed to exhibit significant genotoxic response at two sites. These findings, together with higher mortality of U. tumidus at the most polluted sites, promote U. pictorum as a model for genotoxicity monitoring in freshwater environments.     

Factors affecting distribution pattern of dominant macroinvertebrates in Mantovo Reservoir (Republic of Macedonia)

In the present study, we analysed spatial and temporal heterogeneity of the limnological characteristics to provide more detailed information about the processes taking place within Mantovo Reservoir (Republic of Macedonia). The relationship between principal macroinvertebrate species and environmental variables was analysed in order to explore factors that dominantly affect community distribution pattern. Unlike the most reservoirs, strong longitudinal gradient for suspended organic matter and nutrients (total phosphorous, nitrates and nitrites) along the reservoir doesn??t exist. However, the process of thermal stratification has a strong influence on the metabolism and structure of the Mantovo ecosystem, which can be demonstrated by the vertical and longitudinal distribution of dissolved oxygen (DO), CO₂, pH and metals concentrations. Canonical Correspondence Analysis (CCA) indicated that the main factors controlling spatial distribution of Limnodrilus hoffmeisteri and Chironomus plumosus group were temperature, dissolved oxygen and manganese, including sulphates for C. plumous group. Chaoborus crystallinus showed opposite distribution pattern. Cladotanytarsus mancus group was strongly associated with shallower part (littoral and sublittoral) of Mantovo Reservoir characterized by favourable oxygen condition. None of the environmental variables included in CCA showed any relationship with density of Procladius sp.     

New mechanistic explanation for the localization of ulcers in the rat duodenum: role of iron and selective uptake of cysteamine

Cysteamine, a coenzyme A metabolite, induces duodenal ulcers in rodents. Our recent studies showed that ulcer formation was aggravated by iron overload and diminished in iron deficiency. We hypothesized that cysteamine is selectively taken up in the duodenal mucosa, where iron absorption primarily occurs, and is transported by a carrier-mediated process. Here we report that cysteamine administration in rats leads to cysteamine accumulation in the proximal duodenum, where the highest concentration of iron in the gastrointestinal tract is found. In vitro, iron loading of intestinal epithelial cells (IEC-6) accelerated reactive oxygen species (ROS) production and increased [(14)C]cysteamine uptake. [(14)C]Cysteamine uptake by isolated gastrointestinal mucosal cells and by IEC-6 was pH-dependent and inhibited by unlabeled cysteamine. The uptake of [(14)C]cysteamine by IEC-6 was Na(+)-independent, saturable, inhibited by structural analogs, H(2)-histamine receptor antagonists, and organic cation transporter (OCT) inhibitors. OCT1 mRNA was markedly expressed in the rat duodenum and in IEC-6, and transfection of IEC-6 with OCT1 siRNA decreased OCT1 mRNA expression and inhibited [(14)C]cysteamine uptake. Cysteamine-induced duodenal ulcers were decreased in OCT1/2 knockout mice. These studies provide new insights into the mechanism of cysteamine absorption and demonstrate that intracellular iron plays a critical role in cysteamine uptake and in experimental duodenal ulcerogenesis.     

Parasitofauna of freshwater fishes in the Serbian open waters: a checklist of parasites of freshwater fishes in Serbian open waters

As a result of freshwater fish parasitofauna investigations, throughout the past 75 years, the number of parasitic species is presented. This paper reviews the history, current state, and tendencies of the fish parasitofauna studies in Serbian open waters. Up to now, in total 170 parasitic species have been reported. Systematic parasitofauna investigations have been carried out on 54 freshwater fish species in waters of the Danube River Basin in Serbia, also in hill-mountanious watercourses, lakes and salmonid fishpond of Sjenicko-Pesterska plateau (south-west region of Serbia), Homolje area (east Serbia), and in Vlasina lake (south-east Serbia). This data review pointed that it is necessary to continue the investigation on fish parasites in Serbia. The data on freshwater fish parasites are important for evaluation of general influence on the community structure.     

Macroinvertebrates along the Serbian section of the Danube River (stream km 1429–925)

Results of the investigation of the aquatic macroinvertebrate fauna along a 504 km stretch of the Danube River in Serbia are presented. A total of 74 macroinvertebrate taxa were observed during a 2001 survey. Oligochaeta and Mollusca were the principal components of the community with regard to species richness and abundance. Based on data on the qualitative composition of the macroinvertebrate fauna, a correspondence analysis divided the investigated stretch in three sectors — upper (Pannonian), Iron Gate sector and entrance sector to the Iron Gate stretch. The distribution patterns of certain species supported the division of sectors defined by correspondence analysis.     

Options in uraemia therapy for diabetics with end-stage renal disease

In many countries, diabetic renal disease has become, or will soon become, the single most common cause of end-stage renal disease (ESRD). End-stage renal failure (ESRF) in type-2 diabetic patients is increasing worldwide. Incidence of ESRF caused by diabetic nephropathy (DN) in 1996 in the USA was 41.7% and prevalence was 32.4%. ESRD and ESRF caused by DN was 10%, 5-15% in different haemodialysis centres in adults in the year 2000 in the Republic of Macedonia. In this review article we discuss options in uraemia therapy for diabetics with ESRD. Assessment and treatment of a diabetic with ESRD must be highly individualized. Haemodialysis (HD) has emerged as the most common treatment for all forms of renal failure including diabetic nephropathy. In diabetics patients with ESRD, dialysis is started early at creatinine clearance as high as 15-20 ml/min, at serum creatinin levels as low as 3-5 mg/dl. The first choice of HD access in diabetics is an autologous a-v fistula of the Cimino-Brescia type. The A-V fistula should be created several months before starting HD when creatinine clearance is above 20-25 ml/min. When peritoneal dialysis (PD) is selected, advance planning should ensure that a suitable peritoneal catheter is in situ 2-4 weeks before starting dialysis. HD procedures should be with low ultrafiltration rates and prolonged duration of dialysis sessions. The ultrafiltration in diabetics should not exceed more than 500-600 ml/h on HD. This means dialysis sessions of more than 4h and, in larger patients, of more than 5h HD three times per week. Renal transplantation (RT) is a safe and effective treatment modality for diabetic subjects with ESRD. Cardiovascular disease and serious infections are the major causes of death in haemodialysed and transplanted diabetics. Despite recent improvement, rehabilitation of HD diabetics continues to be inferior to that of non-diabetics. Improvement of survival is a matter of reduction of cardiovascular death and infection.     

Ancient DNA analyses reveal high mitochondrial DNA sequence diversity and parallel morphological evolution of late pleistocene cave bears

Cave bears (Ursus spelaeus) existed in Europe and western Asiauntil the end of the last glaciation some 10,000 years ago.To investigate the genetic diversity, population history, andrelationship among different cave bear populations, we havedetermined mitochondrial DNA sequences from 12 cave bears thatrange in age from about 26,500 to at least 49,000 years andoriginate from nine caves. The samples include one individualfrom the type specimen population, as well as two small-sizedhigh-Alpine bears. The results show that about 49,000 yearsago, the mtDNA diversity among cave bears was about 1.8-foldlower than the current species-wide diversity of brown bears(Ursus arctos). However, the current brown bear mtDNA gene poolconsists of three clades, and cave bear mtDNA diversity is similarto the diversity observed within each of these clades. The resultsalso show that geographically separated populations of the high-Alpinecave bear form were polyphyletic with respect to their mtDNA.This suggests that small size may have been an ancestral traitin cave bears and that large size evolved at least twice independently.     

Stream section types of the Danube River in Serbia according to the distribution of macroinvertebrates

The aim of this study was to use the data on the distribution of aquatic macroinvertebrates obtained from 14 sites within a 413 km long stretch of the Danube River in Serbia to show the relevance of the bordering zone between the Middle and Lower Danube. A total of 68 macroinvertebrate taxa were observed. Molluscs were the major component with regard to species richness and relative abundance. Lithoglyphus naticoides (C. Pfeiffer, 1828) was the most abundant species and Unio tumidus (Retzius, 1788) was the most frequent species. Product-moment correlation coefficients or Pearson r coefficient was used to analyse the relation between the sites based on macroinvertebrate distribution. The data obtained by product-moment correlation served as input for cluster analyses. According to a cluster analyses Danube River in Serbia could be separated in the free-flowing sector, the stretch with a backwater effect and the area of the Iron Gate.     

Genomic patterns in the widespread Eurasian lynx shaped by Late Quaternary climatic fluctuations and anthropogenic impacts

Disentangling the contribution of long‐term evolutionary processes and recent anthropogenic impacts to current genetic patterns of wildlife species is key to assessing genetic risks and designing conservation strategies. Here, we used 80 whole nuclear genomes and 96 mitogenomes from populations of the Eurasian lynx covering a range of conservation statuses, climatic zones and subspecies across Eurasia to infer the demographic history, reconstruct genetic patterns, and discuss the influence of long‐term isolation and/or more recent human‐driven changes. Our results show that Eurasian lynx populations shared a common history until 100,000 years ago, when Asian and European populations started to diverge and both entered a period of continuous and widespread decline, with western populations, except Kirov, maintaining lower effective sizes than eastern populations. Population declines and increased isolation in more recent times probably drove the genetic differentiation between geographically and ecologically close westernmost European populations. By contrast, and despite the wide range of habitats covered, populations are quite homogeneous genetically across the Asian range, showing a pattern of isolation by distance and providing little genetic support for the several proposed subspecies. Mitogenomic and nuclear divergences and population declines starting during the Late Pleistocene can be mostly attributed to climatic fluctuations and early human influence, but the widespread and sustained decline since the Holocene is more probably the consequence of anthropogenic impacts which intensified in recent centuries, especially in western Europe. Genetic erosion in isolated European populations and lack of evidence for long‐term isolation argue for the restoration of lost population connectivity.