The effects of metribuzin on early life stages of common carp (Cyprinus carpio)

Metribuzin belongs to the triazine group of herbicides, which are frequently used in agriculture. The aim of this study was to assess the impact of metribuzin on growth and development of early life stages of fish. Subchronic toxic effects of metribuzin at concentrations of 0.9, 4, 14, and 32 mg/L on embryos and larvae of common carp (Cyprinus carpio) were investigated during a 30 day toxicity test under experimental conditions. Exposure to metribuzin at 32 mg/L was associated with increased mortality. Negative effects on total body length, weight, and inhibition of specific growth rate were induced by all experimental concentrations. Length and weight parameters were the most sensitive. The negative impact of metribuzin was observed in the highest tested concentration beginning on day 6 of exposure. Retardation of early ontogeny was associated with concentrations ?4 mg/L. Histological examination revealed changes in liver and caudal kidney after 30 days exposure to 32 mg/L. Based on growth parameters, development, and histological examination, the Lowest Observed Effect Concentration (LOEC) value was 0.9 mg/L.     

Identification of Resistance Genes Against Powdery Mildew in Four Accessions of Hordeum Vulgare SSP. Spontaneum

Summary Four newly detected accessions of wild barley (Hordeum vulgare ssp. spontaneum) resistant to powdery mildew caused by Blumeria graminis f. sp. hordei were studied with the aim of finding the number of genes/loci conferring the resistance of individual accessions, the type of inheritance of the genes and their relationships to the Mla locus. F₂ populations after crosses between the winter variety ‘Tiffany’ and four wild barley accessions and use of microsatellite DNA markers were focused on the identification of individual resistance genes/loci by means of their chromosomal locations. In PI466495, one locus conferring powdery mildew resistance was identified in highly significant linkage with the marker Bmac0213. This location is consistent with the known locus Mla on chromosome 1HS. In the other three accessions the resistance was determined by two independent loci. In PI466197, PI466297 and PI466461, one locus was identified on chromosome 1HS and three new loci were revealed on chromosomes 2HS (highly significant linkage with Bmac0134), 7HS (highly significant linkage with Bmag0021) and 7HL (significant linkage with EBmac0755). Our prospective aim is identification of further linked DNA markers and the exact location of the resistance genes on the barley chromosomes.     

Ammonia autointoxication of common carp: case studies

Three case studies of ammonia autointoxication of the common carp (Cyprinus carpio L.) are described. In the first case, carp yearlings with a full digestive tract were transferred during the growing period from pond water (22°C) to tap water (17°C). In the second case, marketable carp were transferred from the fishing ground of a pond (18°C) to a storage pond (10–12°C). Harvest was performed in late September when the fish were still ingesting natural feed. In the third case, marketable carp after storage for 1 month were transferred to storage ponds with markedly lower water temperature. Stress because of harvest and handling also occurred in this case. In all cases, highly increased concentrations of ammonia were found in the blood plasma of the fish (mean ± SD 1760 ± 350 μmol L⁻¹ in the first case, 870 ± 540 μmol L⁻¹ in the second case, and 880 ± 150 μmol L⁻¹ in the third case). Highly congested, dark-red coloured, oedematous gills were observed for all specimens. We can avoid similar cases of ammonia autointoxication by protection of fish from sudden changes of temperature during rearing, harvesting, and handling.     

The effect of praziquantel applied per os on selected haematological and biochemical indices in common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.)

The aim of the study was to assess the effects of the anthelminthic, praziquantel, on the haematological and biochemical indices of the blood of common carp (Cyprinus carpio L.). Fish were divided into six groups: two groups received 30 mg kg⁻¹ body weight (bw) of praziquantel, and two groups were given 50 mg kg⁻¹ bw of praziquantel mixed into the heat-treated amyloid vehicle. Fish in the remaining two groups were given only the amyloid vehicle and were used as controls. Fish were examined either 24 or 96 h after administration. Praziquantel treatment was characterised by a significantly lower erythrocyte count, haemoglobin level, packed cell volume and total protein at both dose levels after 24 h compared with the controls, but these parameters were similar to the control values at 96 h. The activity of alanine aminotransferase (ALT) was significantly higher after 96 h in the treated groups, which could be attributed to slight hepatocyte damage caused by praziquantel. However, the differences between the treated and the control groups were not great, and we presumed that they were reversible.     

The content of total mercury and methylmercury in common carp from selected Czech ponds

The aim of the present study was to investigate concentrations of total mercury (THg) and methylmercury (MeHG) in the common carp from Czech ponds of Rožmberk, Spolsky, Nezmar, and Velky Bědny. Seven common carps (Cyprinus caprio) from each of the ponds were caught. Muscle tissue, the liver, and the soft and hard roe were used for the tests. Total mercury and methylmercury were found in all the muscle tissue samples examined. Detection limits for total mercury and methylmercury determination methods were 0.001 mg kg^–1 and 0.013 mg kg⁻¹ respectively. Methylmercury levels in the liver and gonads were below the method’s limits of detection. THg and MeHg concentrations in muscle tissues were 0.018–0.063 mg kg^–1 w.w. and 0.019–0.063 mg kg^–1 w.w. respectively. MeHg made up 90–100% of THg in muscle tissues. Total mercury and methylmercury concentrations were significantly (P < 0.05) higher in fish from the Spolsky pond than from the Nezmar pond. MeHg/THg ratios were significantly (P < 0.05) higher in fish from the Rožmberk, Spolsky and Nezmar ponds compared with fish from the Velky Bědny pond.     

The Reliability of Two Different Protocols for Pharmacologically Induced Ejaculation in Donkeys (Equus asinus)

The aim of this study was to pharmacologically induce ejaculation in male donkeys. Two methods for pharmacological ejaculation were used. The first method was the administration of xylazine (0.66 mg/kg, intravenous); the second method was the administration of detomidine chloride (0.02 mg/kg, intramuscular), and when ejaculation was not achieved in 15 minutes, the administration of a half dose of detomidine chloride (0.01 mg/kg, intramuscular) was repeated. Both of these methods were used in all animals. In the study, 10 male donkeys were used. After the administration of xylazine, no ejaculation was observed. After the administration of detomidine, ejaculation was achieved in 20% of the cases (2 of 10). We assume that these methods are not satisfactory for ex-copula induction of ejaculation in male donkeys.     

Biotic homogenization of Central European urban floras depends on residence time of alien species and habitat types

Spread of alien species may result in biotic homogenization, i.e. increasing similarity between biotas of different areas. We examined whether the flora of Central European cities is becoming homogenized because of the spread of alien species, whether the contribution of aliens to homogenization depends on residence time, and whether habitats under more intense human pressure are more homogenized. Using floristic composition data from a standardized sample of 1-ha plots located in seven habitat types in 32 cities in Central Europe, Belgium and the Netherlands, we compared homogenization effects of archaeophytes (pre-AD 1500 aliens) and neophytes (post-AD 1500 aliens) using rarefaction curves, Jaccard dissimilarity index, Mantel tests and homogenization index. We found that archaeophytes contributed to homogenization and neophytes to differentiation of floras among cities, but generally the spread of alien species caused differentiation. Differentiation was low in the most disturbed urban habitats, such as city squares, boulevards or early successional sites, but was strongest in moderately disturbed habitats, such as city parks and residential areas with an open building pattern. We conclude that biotic homogenization depends on alien plants’ residence time. Aliens introduced within the past five centuries are often rare, not yet having achieved their potential range; they therefore increase floristic differentiation. Conversely, species introduced more than five centuries ago have had sufficient time to disperse into most suitable habitats, and consequently contribute to homogenization. Although invasions may therefore initially increase biodiversity, they could ultimately lead to homogenization. These processes are faster and stronger in more disturbed habitats.