Evaluation of an enzyme immunoassay for the detection of the insect growth regulator fenoxycarb in environmental and biological samples

A competitive enzyme-linked immunosorbent assay (ELISA) for fenoxycarb was adapted for quantitative detection of this insect growth regulator in various environmental, agricultural, food and biological matrices. Environmental samples were taken from soil and surface waters in Hungary. The ELISA enabled fenoxycarb detection in surface waters in the 1.1-125 ng ml(-1) concentration range without sample cleanup. In contrast, soil produced a strong matrix effect due to humic acids and other soil components. Several fruit homogenates and commercial fruit juices (eg apple, pear, grape) were analyzed by the ELISA. The assay was found to be suitable for analysis of fenoxycarb in fruit juices diluted 1:40. Biological samples included insect, fish and bovine tissues. The ELISA was applied to detect fenoxycarb in various biological matrices from larvae of the silkworm, Bombyx mori L. The assay proved useful for the analysis of haemolymph diluted 1:10 or at higher dilutions. Fat body and whole body homogenates, however, caused severe matrix effects. Fenoxycarb was detected in liver homogenates (diluted 1:40) from fish treated with various doses of fenoxycarb, and the concentrations determined correlated with the applied doses. The method was used to analyze spiked bovine urine samples diluted 1:10 or at greater dilutions. Fenoxycarb content determined by the ELISA in water and fruit juice samples was validated using GC-MS with solid-phase microextraction (SPME) sample preparation. The results of these studies demonstrated both the value and limitations of the assay when used for monitoring fenoxycarb in environmental, food and biological samples.     

Diversity and zoonotic potential of rotaviruses in swine and cattle across Europe

Group A rotaviruses can infect both humans and animals. Individual rotavirus strains can occasionally cross species barriers and might hereby contribute to the emergence of new genotypes in heterologous hosts. The incidence and impact of zoonotic rotavirus are not well defined, and one reason for this is a lack of data about strains circulating in suspected reservoir animal hosts. In this study we report the incidence, genetic diversity, and molecular epidemiology of rotaviruses detected in domestic cattle and swine in 6 European countries. From 2003 to 2007, 1101 and more than 2000 faecal specimens were collected from swine and cattle, both healthy and diarrhoeic, and tested for rotaviruses. Viruses from positive stools were genotyped and a subset of strains was characterized by nucleotide sequencing and phylogenetic analysis of the VP7 (G) and VP4 (P) genes. Rotaviruses were detected in 43% of bovine samples and in 14% of porcine samples. In cattle, 10 different combinations of G and P types were identified and the most common strains were G6P[11] and G6P[5]. In swine, the number of identified G-P combinations was higher (n=21), however, no single combination was predominant across Europe. Newly described genotype specificities, P[27] and P[32], were identified in swine. When compared at the nucleotide sequence level, the identified porcine rotavirus strains and contemporary human strains grouped together phylogenetically, whereas bovine rotavirus strains formed separate clades. These data demonstrate large genetic diversity of porcine and bovine rotavirus strains across Europe, and suggest that livestock herds may serve as potential reservoirs for human infections.     

Interactions of Nereistoxin and Its Analogs with Vertebrate Nicotinic Acetylcholine Receptors and Molluscan ACh Binding Proteins

Nereistoxin (NTX) is a marine toxin isolated from an annelid worm that lives along the coasts of Japan. Its insecticidal properties were discovered decades ago and this stimulated the development of a variety of insecticides such as Cartap that are readily transformed into NTX. One unusual feature of NTX is that it is a small cyclic molecule that contains a disulfide bond. In spite of its size, it acts as an antagonist at insect and mammalian nicotinic acetylcholine receptors (nAChRs). The functional importance of the disulfide bond was assessed by determining the effects of inserting a methylene group between the two sulfur atoms, creating dimethylaminodithiane (DMA-DT). We also assessed the effect of methylating the NTX and DMA-DT dimethylamino groups on binding to three vertebrate nAChRs. Radioligand receptor binding experiments were carried out using washed membranes from rat brain and fish (Torpedo) electric organ; [³H]-cytisine displacement was used to assess binding to the predominantly high affinity alpha4beta2 nAChRs and [¹²⁵I]-alpha-bungarotoxin displacement was used to measure binding of NTX and analogs to the alpha7 and skeletal muscle type nAChRs. While the two quaternary nitrogen analogs, relative to their respective tertiary amines, displayed lower α4β2 nAChR binding affinities, both displayed much higher affinities for the Torpedo muscle nAChR and rat alpha7 brain receptors than their respective tertiary amine forms. The binding affinities of DMA-DT for the three nAChRs were lower than those of NTX and MeNTX. An AChBP mutant lacking the C loop disulfide bond that would potentially react with the NTX disulfide bond displayed an NTX affinity very similar to the parent AChBP. Inhibition of [³H]-epibatidine binding to the AChBPs was not affected by exposure to NTX or MeNTX for up to 24 hr prior to addition of the radioligand. Thus, the disulfide bond of NTX is not required to react with the vicinal disulfide in the AChBP C loop for inhibition of [³H]-epibatidine binding. However, a reversible disulfide interchange reaction of NTX with nAChRs might still occur, especially under reducing conditions. Labeled MeNTX, because it can be readily prepared with high specific radioactivity and possesses relatively high affinity for the nAChR-rich Torpedo nAChR, would be a useful probe to detect and identify any nereistoxin adducts.     

Metabolism of fatty acids in fish: III. Combined effect of environmental temperature and diet on formation and deposition of fatty acids in the carp,Cyprinus carpio Linnaeus 1758

Formation and deposition of fatty acids in carp maintained on diets differing in total fat as well as linolenic acid content was investigated by following the incorporation of (1-¹⁴C)-acetate into liver total- and phospholipid fatty acids at two extreme temperatures (5° and 25°C). Excess dietary linolenic acid was deposited in triglycerides but not in phospholipids. The formation and level of phospholipid docosahexenoic acid was, however, dependent on the amount of linolenic acid in the diet. Despite the vast quantities of ingested linolenic acid, the carp on diets containing sufficient essential fatty acid maintained similar membrane fluidities as judged from the ratio of saturated to unsaturated fatty acids. Decrease of the environmental temperature brought about a reduction in the rate of formation of palmitic acid and an increase in the rate of formation of docosahexenoic acid in carp receiving sufficient essential fatty acid. Consequently, the level of palmitic acid decreased and that of docosahexenoic acid increased in the liver phospholipids in carp and a number of other fish species. Essential fatty acid deficient carp were unable to increase the rate of production of long chain polyunsaturated fatty acids upon exposure to cold. The results are discussed from the point of view of adaptation of membrane fluidity to the temperature by fish, and the importance of docosahexenoic acid in this process is emphasized.     

A survey on the environmental impact of pond aquaculture in Hungary

The aim of the study was to survey the nutrient loads of receiving waters and evaluate the nitrogen, phosphorus and organic matter budget of the conventional fishponds in Hungary. The average nitrogen (N), phosphorus (P) and organic matter (OM) concentrations in the filling-up water of the fishponds were 2.51 ± 1.25, 0.57 ± 0.57 and 23.8 ± 13.4 mg l^?1, respectively. Contrarily, the N, P and OM concentrations in the effluents of fishponds were 1.64 ± 2.19, 0.37 ± 0.51 and 30.2 ± 20.5 mg l^?1, respectively. The sediment nutrient content in the fishponds during the operation was 5.77 ± 4.42 mg g dry sediment^?1 for N, 1.25 ± 0.75 for P and 30.5 ± 43.3 for total organic carbon. The retained nutrients represented on average 53 % (84 kg ha^?1 year^?1) of N, 74 % (21 kg ha^?1 year^?1) of P and 74 % (2400 kg ha^?1 year^?1) of OM, introduced into the fishponds. In the fishponds, the ratio of input N, P and OM accumulated in fish biomass was 18.4 ± 6.7, 10.4 ± 4.4 and 6.8 ± 2.1 %, respectively. The investigated fishponds discharged 48 % less N and 62 % less P into the recipient waters than received with the intake water. However, 78 % more OM was discharged with the effluent from the fishponds than received with the inlet and supplement water.     

In-vitro study on the effect of pesticides on neuronal activity

Experiments have been conducted to examine the effect of chronic administration of bromoxynil, fluroxipir and bensultap on the in-vitro seizure susceptibility (induced by 4-aminopyridine) and excitability of neocortical slices of rat brain. The treatment regimes were (A) administration of spray solution in place of drinking water for seven days, and (B) feeding wheat which had been sprayed at growth stage Feekes 9–10 and consumed four to six weeks after spraying. The latency of appearance of the first seizure was significantly increased by fluroxipir (B) bensultap (B) and bromoxynil (A&B). Fluroxipir (A&B) decreased the frequency of seizure, and fluroxipir (A) and bensultap (B) doubled the duration of seizures. Excitability following electrical stimulation of the corpus callosum was not significantly changed by any treatments. The changes in brain activity were not related to the residue levels of the pesticides in the rat brains. Our results suggest that these chemicals may alter the functional properties of neuronal network activity and neurotransmission in rat neocortex after environmental exposure.     

Linear woody landscape elements may help to mitigate leaf surface loss caused by the cereal leaf beetle

Landscape Ecology - Woody semi-natural habitats serve as permanent habitats and hibernation sites for natural enemies and, through spillover processes, they play an important role in the biological...     

Chain Extension and Termination as a Function of Cysteine Content and the Length of the Central Repetitive Domain in Storage Proteins

Analogue glutenin proteins (ANGs) based on the barley seed storage protein C-hordein, modified to contain N- and/or C-terminal cysteine residues and varying lengths of repetitive domain, have been purified from a bacterial expression system. The proteins were used to modify the mixing, extension and baking properties of wheat flour doughs in small-scale tests. Comparison of the effects of simple addition of the proteins versus their chemical incorporation into the glutenin macropolymer has allowed us to assess the importance of cysteine content, cysteine position and repetitive domain length in determining dough mixing and processing properties. When incorporated, the proteins, along with small synthetic oligopeptides based on their N- and C-terminal sequences, change the amount of large glutenin polymers, and hence dough properties, in ways consistent with their action as either chain terminators (polypeptides with single cysteine residues) or chain extenders (polypeptides with two cysteine residues, one in either terminal domain). The gross effects of chain extension and termination may be further fine-tuned by modification of the molecular size of the incorporated proteins through alteration of their repetitive domains.     

Very-high-energy gamma rays from a distant quasar: how transparent is the universe?

The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts.     

Genetic parameters of birth weight trait in dromedary camels (Camelus dromedarius)

Tropical Animal Health and Production - Birth weight data of dromedary calves from the database of one of the world’s largest dairy herds (Dubai, UAE) were analyzed for the period from 2007...