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At least 19 recordsLinked to original sources
PubMed2002

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.

Animals↗
PubMedDate not supplied

[Evolutionary aspects of the distribution of Ascaridoidea in mammals (author's transl)].

In an attempt to interpret the distribution of Ascaridoidea in Mammals and Birds, a scheme is proposed, based on the concept of geological periods of evolutionary expansion for parasitic lines. It is assumed that the evolutionary expansion period of Ascaridoidea in Mammals occurred after the diversification of primitive mammals; this would explain the absence of ascarids in these groups. Periods of evolution appear to coincide with the diversification of Carnivora and Sirenia, the first to become invaded; Artiodactyla and Equidae became invaded later, at the time of their diversification. The other cases of parasitism of Mammals by Ascarids are thought to be "captures".

Animals↗
PubMed1998

Ribosomal DNA and phylogeny of the Ascaridoidea (Nemata: Secernentea): implications for morphological evolution and classification.

Nematodes of the superfamily Ascaridoidea are parasites of the alimentary tract of vertebrates and include species that are of medical and economic importance. Existing evolutionary hypotheses for these organisms have frequently been based on interpretation of one or few "key" structural or life history features. We used nuclear-encoded small (1764 characters) and large subunit (757 characters) ribosomal DNA sequences to estimate the phylogeny of representative taxa from this superfamily. Trees inferred by maximum parsimony and maximum likelihood methods strongly support clades that are primarily consistent with one recent classification of the group. In contrast, most previously proposed phylogenetic hypotheses were significantly worse when compared to the maximum likelihood tree by a statistical method. Hypotheses for the evolution of morphological and life history characters were explored by parsimony mapping these features on several tree topologies, including optimal molecular trees and alternative topologies reflecting traditional expectations deemed not worse in statistical tests. The results identify some consistent putative shared-derived morphological features, but also strongly suggest that some key features emphasized by previous workers represent ancestral states or highly homoplastic characters.

Animals↗
PubMed2001

[New/old opinions on the systematics and phylogenesis of the nematodes, with the special regard to Ascaridida, Ascaridoidea].

Traditional classification of the nematodes, based on morphological-ecological characters was evaluated in the context of molecular analysis of systematic taxons, with special regards to ascarids. Division of superfamily Ascaridoidea into 4 families (Heterocheilidae, Ascarididae, Anisakidae, Raphidascarididae) proposed by Fagerhholm (1991) seems to be proved by the molecular data of Nadler (1992, 1995) and Nadler & Hudspeth (1998).

Animals↗
PubMed2000

Differentiation of cuticular structures during the growth of the third-stage larva of Ascaris suum (Nematoda, Ascaridoidea) after emerging from the egg.

In order to monitor the early phases of the development of Ascaris suum from domestic pigs, third-stage larvae, retrieved from the liver and the lungs, were studied by analyzing worm growth and length increase of individual transverse annuli in the cuticle. Material for study using light and scanning electron microscopy was obtained from experimental infections. The results show that the third-stage larva (not the second-stage) after emergence from the egg grows continuously, without an ecdysis in the liver. During growth, each annulus is split into a complex of 2 subannuli, each of which attains a bimodal appearance and is a prominent feature during a late phase of the third-stage larva. The results suggest that the first 2 molts occur inside the egg, a synapomorphic feature of the Ascaridoidea. The third-stage larvae of ascaridoids, with some functional similarities of the dauer-larva stage of Caenorhabditis sp., facilitate transmission of these parasitic worms to the digestive tract of the vertebrate final host (utilizing the tracheal route in A. suum), where the third and the fourth molts take place.

Animals↗
PubMed2001

Mutation scanning for sequence variation in three mitochondrial DNA regions for members of the Contracaecum osculatum (Nematoda: Ascaridoidea) complex.

Anisakid nematodes of seals from different geographical origins, previously identified by multilocus enzyme electrophoresis as Contracaecum osculatum A (CoA), C. osculatum B (CoB), C. osculatum C (CoC), C. osculatum D (CoD), C. osculatum E (CoE) and C. osculatum baicalensis (Cob), were characterised genetically using a mutation scanning approach, in order to define genetic markers for their specific identification and differentiation. Three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit I (COI), and the small and large subunits of rRNA (ssrRNA and IsrRNA, respectively) were amplified separately from individual nematodes by polymerase chain reaction (PCR), analysed by single-strand conformation polymorphism (SSCP), and samples displaying sequence variability were subjected to sequencing. Forty-six haplotypes were defined for 62-66 individuals (representing the six members of C. osculatum). All taxa except CoD and CoE could be identified, or delineated from one another, by nucleotide differences in the COI, ssrRNA and/or IsrRNA sequences. For all three mtDNA regions, 4 (10.5%), 7 (18.4%), 15 (39.5%) and 11 (28.9%) of 38 nucleotide positions were considered diagnostic (fixed) and could thus unequivocally delineate CoA, CoB, CoC and Cob. The lack of an unequivocal nucleotide difference in any of the three mtDNA sequences between CoD and CoE was in accordance with previous ribosomal DNA sequence data but inconsistent with multilocus enzyme electrophoretic data. Using all fixed nucleotide positions, CoA, CoD/E and CoB were genetically more similar to Cob than each was to CoC, similar to previous findings. In spite of not being able to distinguish among all six taxa of C. osculatum, the present study demonstrated clearly the usefulness and attributes of the mutation scanning approach for investigating population genetic structures of species of parasitic nematodes.

Animals↗
PubMed2001

Electrophoretic detection of population variation within Contracaecum ogmorhini (Nematoda: Ascaridoidea: Anisakidae).

This study examined genetic variation among specimens of Contracaecum ogmorhini from different otariid hosts and geographical origins using a polymerase chain reaction (PCR)-based mutation detection approach. The first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of ribosomal DNA (rDNA) were amplified individually by PCR, scanned for sequence variation by single-strand conformation polymorphism (SSCP), and samples displaying variable SSCP profiles were subjected to cycle sequencing. While C. ogmorhini individuals from Arctocephalus pusillus pusillus (CoAPP) from South Africa and those from Arctocephalus pusillus doriferus (CoAPD) from Australia had very similar SSCP profiles for both ITS-1 and ITS-2, individuals of C. ogmorhini from Zalophus californianus (CoZC) from Pacific Canada could be unequivocally distinguished based on their profiles. In accordance with SSCP results, both CoAPP and CoAPD had identical ITS consensus sequences, whereas CoZC differed in sequence from both CoAPP and CoAPD populations by 0.2% (one base in the ITS-1) and 0.7% (two bases in the ITS-2). Based on the nucleotide difference in the ITS-2 sequence, a PCR-linked restriction fragment length polymorphism (RFLP) could be employed to distinguish individuals representing CoZC from those of both CoAPP and CoAPD. The findings suggest that C. ogmorhini may represent a complex of at least two species.

Animals↗
PubMed1995

The life cycle of Contracaecum osculatum (Rudolphi, 1802) sensu stricto (Nematoda, Ascaridoidea, Anisakidae) in view of experimental infections.

Hatched, ensheathed third-stage larvae of Contracaecum osculatum, 300-320 microns long, were shown to be infective to copepods, to nauplius larvae of Balanus and to small specimens of fishes (sticklebacks, O-group eelpout). Other fishes such as gobies and small flatfishes became infected by ingesting infected crustaceans. Cod were infected by being given infected small fishes. In the crustacean paratenic hosts, little growth of the larvae occurred, if any. In the liver sinusoids of sticklebacks and gobies the length of most of the unencapsulated third-stage larvae had not even doubled within 6 months of infection. The fate of larvae (max. 2 mm long) given to cod via infected intermediate fish hosts was apparently decided by the size of the larvae only. Small larvae became encapsulated and eventually died in the liver and wall of the gastrointestinal tract. Larger larvae migrated to the liver parenchyma, where some grew to a length of as much as 10 mm. The growth of the larvae in sticklebacks was shown not to be affected by an increase in temperature (infected fish being transferred from 8 degrees to 14 degrees and 20 degrees C), by the intensity of infection and, partly, by the age of infection (e.g. some 2-week-old and 6-month-old larvae were of identical size). In the liver and mesentery of plaice the third-stage larvae developed via copepod paratenic hosts to infectivity (i.e. to more than 4 mm in length), showing that the life cycle may be completed with an optional paratenic invertebrate host and only one intermediate fish host.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Assessing sequence variation in the internal transcribed spacers of ribosomal DNA within and among members of the Contracaecum osculatum complex (Nematoda: Ascaridoidea: Anisakidae).

The anisakid nematodes of seals from different geographical origins, previously identified as Contracaecum osculatum A, C. osculatum B, C. osculatum C, C. osculatum D, C. osculatulm E and C. osculatum baicalensis by multilocus enzyme electrophoresis, were characterised using a DNA approach. The first and second internal transcribed spacers (ITS-1, ITS-2) of ribosomal DNA (rDNA) were individually amplified by polymerase chain reaction (PCR) and analysed by single-strand conformation polymorphism (SSCP) and sequencing. SSCP analyses allowed the unequivocal differentiation of all taxa except C. osculatum D from C. osculatum E. While C. osculatum D and C. osculatum E had identical ITS sequences, each of the other four taxa had distinct sequences, with interspecific differences ranging from 0.3% to 2.3%. C. osculatum C was genetically the most distinct taxon with respect to all other members of the species complex.

Animals↗
PubMed1996

Larval anisakids (Nematoda: Ascaridoidea) in horse mackerel (Trachurus trachurus) from the fish market in Granada (Spain).

Horse mackerel (Trachurus trachurus) from the fish market in Granada, South Spain, were surveyed for anisakid nematodes. The fish came from fishing ports all over the country. Larval anisakids were found in 39.4% of the fish examined. In all, 26.1% were infected with third-stage larvae (L3s) of Anisakis simplex; 0.3%, with A. physeteris L3s; 31.1%, with Hysterothylacium aduncum L3s; and 1.7%, with fourth-stage larvae (L4s) of Hysterothylacium sp. Horse mackerel from Mediterranean Sea coast ports (South and Southeast Spain) had the lowest levels of infection and those from Cantabrian Sea coast ports (North Spain) had the highest levels. Variations in infection levels with host size (age) and season of capture were surveyed.

Animals↗
PubMed1996

Larval anisakids (Nematoda:Ascaridoidea) in horse mackerel (Trachurus trachurus) from the fish market in Granada, Spain.

Horse mackerel (Trachurus trachurus) from the fish market in Granada, southern Spain, were surveyed for anisakid nematodes. The fish came from fishing ports all over the country. Larval anisakids were found in 39.4% of the fish examined; 26.1% were infected with third-stage larvae (L3s) of Anisakis simplex; 0.3%, with A. physeteris L3s; 31.1%, with Hysterothylacium aduncum L3s; and 1.7%, with fourth-stage larvae (L4s) of Hysterothylacium sp. Horse mackerel from Mediterranean Sea coastal ports (South and South-east Spain) had the lowest levels of infection, and those from Cantabrian Sea coastal ports (North Spain) had the highest. The variation in infection levels with host size (age) and season of capture are surveyed.

Animals↗
PubMed1991

Genetic evidence for three species within Pseudoterranova decipiens (Nematoda, Ascaridida, Ascaridoidea) in the North Atlantic and Norwegian and Barents Seas.

Genetic variation of 1017 specimens of codworm, Pseudoterranova decipiens, collected from fish and seals at 23 sampling locations in the North Atlantic and Norwegian and Barents Seas, was analysed on the basis of 16 enzyme loci. Three reproductively isolated species, provisionally designated P. decipiens A, B and C, were detected, showing distinct alleles at the following loci: Mdh-1, 6Pgdh, Np, Pgm, Est-2 (between species A and B); Mdh-3, 6Pgdh, Np, Sod-1, Adk, Pgm, Est-2, Mpi (between A and C); Mdh-1, Mdh-3, Sod-1, Adk, Pgm, Est-2, Mpi (between B and C). One F1 hybrid was observed between P. decipiens A and B, but this apparently does not lead to any gene exchange between the two species, which do not show any evidence of introgression. No hybrids or introgressed individuals were observed between P. decipiens C and either A or B. Genetic distances among conspecific populations were low (average Nei's D 0.001-0.005), even though they were collected thousands of kilometres apart, indicating high levels of gene flow within each of the three species. The values of Nei's index D were 0.44 between P. decipiens A and B, 0.57 between B and C, and 0.79 between A and C. Estimated evolutionary divergence times, using Nei's formula, range from 2 to 4 million years. Differences between P. decipiens A, B and C were also found with respect to genetic variability, morphology, geographical distribution and hosts. Mean heterozygosity values of 0.08, 0.05 and 0.02 were obtained for P. decipiens A, B and C, respectively. Preliminary morphological examination of adult males, previously identified by multilocus electrophoresis, revealed differences in the relative size and pattern of caudal papillae. P. decipiens B is widespread in the study area, whereas P. decipiens A was found only in the North-East Atlantic and Norwegian Sea. In this area P. decipiens A is most common in the grey seal, Halichoerus grypus, while the common seal, Phoca vitulina, is the main host for P. decipiens B. In Canadian Atlantic waters, where P. decipiens A is apparently absent, P. decipiens B infects both grey and common seals; a few specimens were also found in the hooded seal, Cystophora cristata. The only definitive host so far identified for P. decipiens C is the bearded seal, Erignathus barbatus; P. decipiens C appears to be widespread, occurring in both the North-West Atlantic and Barents Sea.

Animals↗
PubMed1993

Three sibling species within Contracaecum osculatum (Nematoda, Ascaridida, Ascaridoidea) from the Atlantic Arctic-Boreal region: reproductive isolation and host preferences.

Genetic variation within and between population samples from 22 locations of the Atlantic Arctic-Boreal region, including 1657 specimens morphologically assigned to Contracaecum osculatum, was electrophoretically analysed at 17 loci. Highly significant deviations from the Hardy-Weinberg equilibrium were found at various loci in several samples, owing to the existence of three distinct gene pools within C. osculatum (sensu lato) from the study area. These gene pools correspond to three biological species (provisionally designated A, B and C), characterized by distinct genotypes at several diagnostic loci. Reproductive isolation between C.osculatum A, B and C is confirmed by the lack of F1, recombinant, or backcross genotypes in sympatric areas, despite the occurrence of multiple infections. Mean heterozygosity per locus is on average 0.11 in species A, 0.10 in B and 0.07 in C. High levels of gene flow were found within each of the three species, the values of Nm (number of migrant individuals) ranging from 3.41 (C. osculatum C) to 5.77 (C. osculatum A). Average Nei's genetic distance is 0.46 between A and B, 0.50 between A and C and 0.77 between B and C. From these values, times of evolutionary divergence from 2 to 4 million years can be estimated. Genetic relationships among populations and species of the C. osculatum complex are illustrated by principal component analysis. The role of both geographical isolation and host preferences in the speciation of C. osculatum (sensu lato) is discussed. A morphological distinction of the three species has not yet been possible (sibling species). However, there is evidence that the name C. osculatum (sensu stricto) should be used for species C, which shows a geographical distribution and definitive host corresponding to the neotype of C. osculatum (sensu stricto). Finally, a comparison is made between the members of the C. osculatum complex from the Atlantic Arctic-Boreal region and those of the Pseudoterranova decipiens complex from the same area, as to: (i) times of evolutionary divergence, (ii) geographical distribution, and (iii) host preferences.

Alleles↗
PubMed1994

Occurrence and histological response of Raphidascaris acus (Nematoda: Ascaridoidea) in roach from four lakes differing in water quality.

Seasonality and size-related infection of Raphidascaris acus larvae from the inner organs and intestine of roach (Rutilus rutilus) were studied in 4 lakes of differing water quality and pollution level in Central Finland between August 1985 and November 1986. The influence of R. acus larvae on the liver and pancreatic tissues of roach was examined histologically in additional material from 1989 and 1990. The inner organs of roach were most heavily infected with R. acus in the eutrophic, polluted Lake Vatia (63% of fish infected with 4.0 nematodes/fish) and in the two eutrophic lakes, compared to the oligotrophic Lake Peurunka (23%, 0.8). The prevalence of free R. acus larvae in the intestine of roach was almost as high but the intensity only about half of that found in the inner organs. The prevalence of infection had significantly higher values in autumn in most cases, and larvae accumulated in the inner organs and intestine of older roach. In histological studies it was found that larvae occurred more often in the pancreatic tissue than in the liver, but in both organs the majority of the larvae were dead and partly destroyed. The most typical host response against R. acus was a chronic granulomatous inflammatory reaction. Granulomas and developing granulomas containing worms at different stages of degeneration are described; they were found in all of the lakes studied throughout the year and also in one and the same fish. On average only 37 and 21% of the worms in the liver and pancreas, respectively, were alive. No obvious difference in the histological response against R. acus was noted between the lakes.

Animals↗
PubMed1994

Two new members in the Contracaecum osculatum complex (Nematoda, Ascaridoidea) from the Antarctic.

The genetic structure of adults and larvae of Contracaecum osculatum (sensu lato) from the Antarctic is analyzed on the basis of 24 enzyme loci. Significant deviations of genotype frequencies from the Hardy-Weinberg equilibrium were found, even in samples recovered from the same host. These data indicate that two distinct, reproductively isolated species coexist in C. osculatum (sensu lato) samples from the Antarctic. They were provisionally designated C. osculatum D and E, as they do not correspond to any of the three species previously detected in this complex from the Atlantic Arctic Boreal region (C. osculatum A, B and C). An allozyme diagnostic key for the identification of the five members of the C. osculatum complex, at the larval and adult stage and in both sexes, is given. Species D and E were found to be genetically quite variable: average P99 = 84.3, A = 3.3 and He = 0.23. Both showed high values of intraspecific gene flow: Nm = 4.6 and 6.1 respectively; similar values were found for the Arctic-Boreal C. osculatum A, B and C. The most related members of the complex are the Antarctic species E and the Arctic-Boreal species A (DNei = 0.21), while the most differentiated ones are the Arctic-Boreal species B and C (DNei = 0.76). The evolutionary divergence of C. osculatum C started more than 3 million years ago, in a Pliocene refugium (Baltic Sea). As to the other C. osculatum species, their evolutionary divergence took place during Pleistocene, when this complex achieved a bipolar distribution. This process involved two distinct colonizations of the marine Antarctic region by ancestors of the northern hemisphere, about 1.5 and 1 million years ago, giving origin to C. osculatum D and E respectively.

Animals↗
PubMed2006

Practical PCR tools for the delineation of Contracaecum rudolphii A and Contracaecum rudolphii B (Ascaridoidea: Anisakidae) using genetic markers in nuclear ribosomal DNA.

Using genetic markers defined previously in the internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA (rDNA), PCR-coupled restriction fragment length polymorphism (PCR-RFLP) and specific PCR assays were established for the specific detection of each of two morphologically indistinguishable operational taxonomic units (Contracaecum rudolphii A and Contracaecum rudolphii B) within Contracaecum rudolphii (s.l.) and their differentiation from Contracaecum septentrionale, a closely related congener. Application of these tools to C. rudolphii (s.l.) adults from Phalacrocorax carbo sinensis (the Eurasian subspecies of the great cormorant) from Qinghai Lake in China, revealed C. rudolphii B to infect this host. This is the first report of C. rudolphii B in P. carbo sinensis outside of Europe (where it was originally detected), supporting the proposal that this species has a broad geographical distribution. Together with other methods, each of these molecular tools will be useful for investigating the ecology of C. rudolphii A and C. rudolphii B as well as C. septentrionale.

Animals↗
PubMed2000

Genetic markers in ribosomal DNA for the identification of members of the genus Anisakis (Nematoda: ascaridoidea) defined by polymerase-chain-reaction-based restriction fragment length polymorphism.

Polymerase-chain-reaction-based restriction fragment length polymorphism analysis was performed to establish genetic markers in rDNA, for the identification of the three sibling species of the Anisakis simplex complex and morphologically differentiated Anisakis species, i.e. Anisakis physeteris, Anisakis schupakovi, Anisakis typica and Anisakis ziphidarum. Different restriction patterns were found between A. simplex sensu stricto and Anisakis pegreffii with two of the restriction endonucleases used (HinfI and TaqI), between A. simplex sensu stricto and A. simplex C with one endonuclease (HhaI), and between A. simplex C and Aniskis pegreffii with three endonucleases (HhaI, HinfI and TaqI), while no variation in patterns was detected among individuals within each species. The species A. physeteris, A. schupakovi, A. typica and A. ziphidarum were found to be different from each other and different from the three sibling species of the A. simplex complex by distinct fragments using 10-12 of the endonucleases tested. The polymorphisms obtained by restriction fragment length polymorphisms have provided a new set of genetic markers for the accurate identification of sibling species and morphospecies.

Animals↗