Paratenic hosts of the swimbladder nematode <i>Anguillicola crassus</i>

The host specificity and population dynamics of Anguillicola crassus in a number of paratenic hosts were investigated. Various freshwater fish species were sampled monthly (March 1990 to March 1991) from the Kolenhaven (Albertcanal, Genk, Belgium) and examined for L3-larvae of Anguillicola crassus. Sixteen species were found to be infected: all the physoclist species examined (Gymnocephalus cernua, Lepomis gibbosus, Ictalurus nebulosus, Stizostedion lucioperca, Gasterosteus aculeatus, Oreochromis niloticus and Perca fluviatilis) and those physostome species of which a sufficient number could be examined to detect the infection (Gobio gobio, Leuciscus cephalus, Chondrostoma nasus, Leuciscus leuciscus, Alburnus alburnus, Leuciscus idus, Scardinius erytrophthalmus, Rutilus rutilus and Tinca tinca). There were large differences in prevalence among the fish species examined but generally the prevalence was higher in physoclist fishes and was highest in G. cernua (96%). In 4 species there was a significant positive correlation between the fish length and parasite abundance. The percentage of grown larvae varied among fish species, being lowest in G. cernua and highest in P. fluviatilis. No clear seasonal incidence cycle was observed

Population biology of <i>Anguillicola crassus</i> in the final host <i>Anguilla anguilla</i>

Eels were sampled twice a month (March 1990 though March 1991) at the Kolenhaven (Albertcanal, Genk, Belgium) and examined for Anguillicola crassus nematodes in the swimbladder. Averaged over all samples, 90.2% of the 345 eels were infected with a mean intensity (averaged for all stages) of 17 nematodes. Thirty-one percent of all nematodes, which were adult worms or their remnants, were present in the swimbladder lumen, while the other 69% which consisted of the third or fourth larval stage and preadults were found in the swimbladder wall. No clear seasonal fluctuations in parasite prevalence or mean intensity were observed. Both L3-larvae and mature adult worms were present throughout the year. Eggs or L2-larvae were observed in 41% of the infected eels. This presence showed no seasonal pattern, though it was positively correlated with eel length: massive concentrations of L2-larvae were only found in eels bigger than 40 cm. A positive but weak correlation between eel length and number of adult nematodes in the swimbladder was significant, while no correlation was found between eel length and total parasite burden

Bridging lab and industry with flow electrochemistry

A revitalization of organic electrosynthesis has incited the organic chemistry community to adopt electrochemistry as a green and cost-efficient method for activating small molecules to replace highly toxic and expensive redox chemicals. However, many of the critical challenges of batch electrosynthesis, especially for organic synthesis, still remain. The combination of continuous flow technology and electrochemistry is a potent means to enable industry to implement large scale electrosynthesis. Indeed, flow electrosynthesis helps overcome problems that mainly arise from macro batch electro-organic systems, such as mass transfer, ohmic drop, and selectivity, but this is still far from being a flawless and generic applicable process. As a result, a notable increase in research on methodology and hardware sophistication has emerged, and many hitherto uncharted chemistries have been achieved. To better help the commercialization of wide-scale electrification of organic synthesis, we highlight in this perspective the advances made in large-scale flow electrosynthesis and its future trajectory while pointing out the main challenges and key improvements of current methodologies

Iron(II)-catalyzed enantioselective meso-epoxide-opening with anilines

A highly enantioselective method for the catalytic opening of aromatic meso-epoxides with aniline derivatives was developed. The desired chiral ß-amino alcohols were obtained in mostly good to very good yields with excellent enantioselectivities. Structural evidence of the pre-catalyst revealed a scarcely disclosed heptadentate Fe(II) complex with the chiral bipyridine ligan

Atom economical synthesis of N-alkylbenzamides via iron(III) sulfate catalyzed rearrangement of 2-alkyl-3-aryloxaziridines in water and in the presence of surfactant

A green and mild synthetic route to N-alkylbenzamides involves eco-friendly one pot synthesis of 2-alkyl-3-aryloxaziridines from N-alkylamines and benzaldehydes followed by iron(III) sulfate catalyzed rearrangement to the corresponding amides in water as solvent and in the presence of sodium dodecyl sulfate as surfactant. This green approach affords N-alkylbenzamides in high overall yields under simple and minimum manipulation

Fe(BF4)2 catalyzed inter- and intramolecular carbonyl-ene reaction of trifluoropyruvate

Inter- and intramolecular carbonyl-ene reactions have been developed using 5 mol% Fe(BF4)2 as catalyst, affording homoallylic alcohols in 36–87% isolated yields. This catalyst, prepared from FeCl2 and AgBF4, is the first FeII Lewis acid reported for the carbonyl-ene reaction using ethyl trifluoropyruvate. The method was successfully applied to the reaction of various 1,1-disubstituted alkenes with ethyl trifluoropyruvate and to the cyclization of citronellal

Enantioselective aromatic sulfide oxidation and tandem kinetic resolution using aqueous H2O2 and chiral iron Bis(oxazolinyl)bipyridine catalysts

An efficient method for the oxidation of aromatic sulfides was developed using aqueous H2O2 catalyzed by in situ-generated chiral Fe/6,6'-bis(oxazolinyl)-2,2'-bipyridine (bipybox) complex. The corresponding sulfoxides were obtained in high enantio-selectivities (up to 98.5:1.5 er) and good yields (up to 61%) when the mono-oxidation of the sulfides was performed in combination with the kinetic resolution of the sulfoxide into the sulfone

Efficacy of some anthelmintics against the swimbladder nematode <i>Anguillicola crassus</i> of eel <i>Anguilla anguilla</i> under saltwater conditions

Six anthelmintic drugs, Ivermectin, Closantel, Safewormer, Masoten, Oxfendazole and L-Levamisol·HCL were screened for their efficacy against Anguillicola crassus, a swimbladder nematode of European eel Anguilla anguilla. All experiments were carried out under saltwater conditions. Of the 6 drugs, L-Levamisole·HCL used in a bath treatment gave the most promising results. Evaluation of the curative dose of L-Levamisole·HCL showed that a long-term treatment (24h). Dosages lower than 20 mg 1-1 showed a lower efficacy against Anguillicola crassus. However, even with a long-term, high-dosage treatment, some recovery of adult nematodes with sublethal damage and/or migration of viable juveniles into the swimbladder lumen could not be excluded. When examined 35d after treatment, the percentage of mobile adults had increased, while a decrease in percentage of dead worms was noticed compared to values obtained immediately after treatment