Agnieszka Kijewska

Ascaridoidea: a simple DNA assay for identification of 11 species infecting marine and freshwater fish, mammals, and fish-eating birds.

Eleven species belonging to superfamily Ascaridoidea, which infect marine and freshwater fish, mammals, and fish-eating birds, were analyzed using a PCR-RFLP method. The following species were investigated: Anisakis pegreffi, A. physeteris, and A. simplex (parasites of fish and mammals), Contracaecum osculatum, C. radiatum, and C. rudolphi (parasites of mammals and fish-eating birds), Hysterothylacium aduncum (a parasite of fish), Porrocaecum angusticolle, P. crassum, P. depressum, and P. ensicaudatum (parasites of fish-eating birds). PCR-amplified rDNA regions encompassing ITS1, 5.8S rDNA, and ITS2 produced on templates of genomic DNA isolated from all investigated species were digested with TaqI, AluI, BsuRI, and RsaI endonucleases. Restriction patterns showed that endonuclease TaqI is the most useful enzyme for identification of all investigated species. No variations in restriction patterns within each species were detected. Therefore, we propose that the PCR-RFLP assay described in this report may be used for identification of marine and freshwater parasites from superfamily Ascaridoidea.

Anisakid nematodes of Greenland halibut Reinhardtius hippoglossoides from the Barents Sea.

Abstract:  Parasitic nematodes from the body cavity of 94 Greenland halibut (Reinhardtius hippoglossoides) caught in the Barents Sea were examined. Nematode species were identified using both morphological and molecular methods. Four morphospecies were found: Anisakis simplex s.l., Contracaecum osculatum s.l., Pseudoterranova decipiens s.l., and Hysterothylacium aduncum. The most prevalent were C. osculatum s.l. (89.4%) and A. simplex s.l. (86.2%). Mean intensities for these 2 species were 7.8 and 45.2, respectively. The number of parasites was directly proportional to the fish length. The following 6 parasite species, including 3 cryptic species of Contracaecum sp., were identified using molecular methods: A. simplex sensu stricto, C. osculatum A, C. osculatum B and C (the last 2 as host records for halibut), Pseudoterranova bulbosa, and H. aduncum. Mixed infections of C. osculatum A, B, and C were observed.

Pomphorhynchus laevis parasite of flounder Platichthys flesus as a biological indicator of pollution in the Baltic Sea

Six hundred and seventy nine specimens of Platichthys flesus (L.) were caught in summer (July–September) 1998 and 1999 from three regions of the Polish zone of the Baltic Sea: the Gulf of Gdansk, the Pomeranian Bay and the open sea off Łeba. The biometric measurements (length, weight, age) and sex of the specimens were recorded. The specimens were examined for occurrence of parasites. The intensity, relative density and prevalence of infection were calculated.

MITOCHONDRIAL DNA OF ANISAKIS SIMPLEX S.S. AS A POTENTIAL TOOL FOR DIFFERENTIATING POPULATIONS

Abstract Anisakis simplex s.s. specimens from Gadus morhua, Gadus ogac, Reinhardtius hippoglossoides, Clupea harengus, Micromesistius poutassou, Pleurogrammus monopterygius, and Oncorhynchus nerka, caught in the north Atlantic and Pacific, were examined. Identity of the parasite species was confirmed using a molecular key. All specimens were used for amplifying a part of the non-coding sequence of the AT-rich region, flanked by the nad6-nad4L-trnW-trnE-rrnS-trnS2, and trnN-trnY-nad1 genes. This part of the mtDNA was chosen as a promising fragment, which could yield information regarding population differentiation. The number of samples and their geographical origin was sufficient to compare the 2 regions. The Bayesian analysis provided strong support for a population split into 2 groups, one representing A. simplex s.s. samples from the Pacific, and the other representing all the Atlantic samples. It is highly probable that observed subpopulations were constituted after the connection between the Atlantic and Pacific had been closed and movement between these 2 oceans was prevented.

Distribution of ascaridoid nematodes (Nematoda: Chromadorea: Ascaridoidea) in fish from the Barents Sea

Abstract The Ascaridoidea are parasites with heteroxenous life cycles. The study shows that fish can be paratenic, intermediate, or final hosts for parasites, and parasitic fauna reflects the feeding behavior of the hosts. Each species of parasites has also different environmental preferences and host specificity. Parasitic nematodes of fish representing Pleuronectidae, Gadidae, Sebastidae, and Macrouridae were studied. Worms were collected separately from different infection sites: stomach, intestine, liver and body cavity. Nematodes were identified using both morphological and molecular methods (PCR-RFLP). Six nematode species were recorded: Anisakis simplex s.s., Contracaecum osculatum A, B, and C. osculatum C (s.s.), Hysterothylacium aduncum and Pseudoterranova bulbosa. Anisakis simplex s.s. was the most numerous nematode species of all catches combined. Differences in parasite species composition were related to the depth and location of sampling areas. In the fish from deep waters, the abundance of A. simplex s.s. decreased compared to fish from shallow waters and P. bulbosa was the dominant species. Ascaridoid species have specific preferences regarding the impact on various internal organs of fish, which is reflected in their abundance. The presence of Ascaridoidea in the Barents Sea is associated with the distribution of hosts and varying food preferences related to the age of fish. The abundance of parasites varied between different host species.