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At least 19 recordsLinked to original sources
PubMed2000

Gyrodactylus anguillae (Monogenea: Gyrodactylidae) from anguillid eels (Anguilla australis and Anguilla reinhardtii) in Australia: a native or an exotic?

A species of Gyrodactylus collected from 2 species of anguillid eels (Anguilla australis Richardson, 1841 and Anguilla reinhardtii Steindachner, 1867) from Australia is identified as Gyrodactylus anguillae Ergens, 1960. The morphology of sclerites of G. anguillae specimens from Australia is in accordance with previous descriptions of specimens collected from A. anguilla (Linnaeus, 1758) from Europe and A. anguilla imported into Japan. Gyrodactylus anguillae was previously thought to be a parasite specific to A. anguilla, an eel that is native to freshwater catchments throughout Europe. Information on eel translocations and host and parasite biology is reviewed and it is hypothesized that G. anguillae is a naturally occurring parasite in Australia and not an introduction.

Anguilla↗
PubMed2004

Differences in susceptibility of the European eel (Anguilla anguilla) and the Japanese eel (Anguilla japonica) to the swim-bladder nematode Anguillicola crassus.

The swim-bladder nematode Anguillicola crassus originates from the Far East where it is a parasite of the Japanese eel (Anguilla japonica). After A. crassus was introduced to Europe, it became a predominant parasite of the European eel (Anguilla anguilla). A study performed with experimentally infected eels (98 days, 23 degrees C) revealed significant differences in the susceptibility of the two eel species to this parasite. The recovery rate of 30 administered infective A. crassus larvae (L3) from A. japonica was less than half of that from A. anguilla (33.2% and 13.8%, respectively). Almost 60% of the worms recovered from A. japonica were found as dead, encapsulated and necrotic larvae in the swimbladder wall. In contrast, no dead larvae were found in A. anguilla. Additionally, the development of the worms was shown to be significantly slower in A. japonica compared with A. anguilla. The lower survival rate of the worms, together with their slower development, resulted in a significantly lower adult worm burden (11 and 428 mg wet weight, respectively) and in a decreased reproductive success in A. japonica compared with A. anguilla. These results demonstrate that the original host, A. japonica, possesses more effective defence mechanisms against A. crassus than does the non-adapted host, A. anguilla.

Air Sacs↗
PubMed1987

Co-existence of congeneric species of acanthocephala: Acanthocephalus lucii and A. anguillae in eels Anguilla anguilla in Ireland.

A population of eels Anguilla anguilla from Lough Derg, R. Shannon, Ireland, harbouring infections of both Acanthocephalus lucii and A. anguillae was studied over three years. Both parasite species had the same intermediate host and eels appeared to be the only definitive host for A. anguillae. Throughout the whole period, A. lucii was the dominant parasite, was over-dispersed throughout the eel population and most frequently occurred as a single species infection. A. anguillae was far less common, its dispersion was close to random at most times and it almost invariably occurred as a mixed species infection. The proportions of the two species remained fairly constant over the period. Despite some indication of site selection in the intestine, the distribution of both species overlapped considerably and there was no evidence of competitive displacement of one species by the other or of resource partitioning in space. The life-histories of both species were similar: they infected eels, bred and were lost from fish at the same time of year and there was no indication of resource partitioning in time. Congeneric species of acanthocephalans can thus co-exist in apparently stable equilibrium in fish as predicted and without any evidence of interactions, but it is still considered that exploitation competition between the species may be occurring in eels.

Acanthocephala↗
PubMed2002

Description of Bucephalus anguillae n. sp. (Trematoda: Bucephalidae), a parasite of the eel Anguilla anguilla (Anguillidae) from a brackish water lagoon of the Adriatic Sea.

The digenetic trematode Bucephalus anguillae n. sp. is described from the intestine of eel, Anguilla anguilla L., originating from a brackish water fish farm on the Italian coast of the Adriatic Sea. The new taxon is 1 of 12 Bucephalus species characterized by an anterior rhynchus surrounded by 7 tentacular appendages, each when fully protruded with 2 prongs. Scanning electron microscopy reveals, for the first time in a Bucephalus species, the crescent-shaped, unspined field located between the rhynchus and the dorsal tentacles. A comparison of B. anguillae n. sp. with 11 congeneric species revealed its remarkable similarity with B. polymorphus Baer, 1827; however, the new species has a larger cirrus sac, larger pharynx, vitelline gland fields not extending the level of pharynx, ovary located in the pharyngeal area rather than fairly posterior to pharynx, smaller testes, relatively wider rhynchus, and tegumental armature comprising slightly larger spines. Multivariate discriminant analyses confirmed a differentiation of B. anguillae from populations of B. polymorphus; the combination of 4 variables, namely cirrus sac length, pharynx width, cirrus sac width, and rhynchus width yielded a total separation of compared species.

Anguilla↗
PubMed2002

Microhabitat distribution of Pseudodactylogyrus anguillae and Pseudodactylogyrus bini among and within gill arches of the European eel (Anguilla anguilla L.).

The outlying mean index (OMI) method was used to test for seasonal microhabitat partitioning in Pseudodactylogyrus anguillae and Pseudodactylogyrus bini communities parasitising European eel ( Anguilla anguilla L.) in four seasons. No differences in the occurrence of parasites were found in different seasons or on different gill arches. The OMI analysis showed that hemibranch separation and gill segments were the main factors explaining the variation in parasite niche occupation for the first factorial axis, which was generally more significant than the second factorial axis. The OMI and tolerance indices were compared for both species in the seasons studied, and the main differences between species indices were recorded. P. anguillae and P. bini communities were partitioned in the seasons with high epidemiological parameters of the infection. In the seasons with low epidemiological parameters, or in seasons when the parasite species preferred gill arches, the characters of gill division (lower level of gill division than gill arches) were not important for the partitioning of the Pseudodactylogyrus communities.

Anguilla↗
PubMed2002

Cycle évolutif de Bucephalus anguillae Spakulová, Macko, Berrilli & Dezfuli, 2002 (Digenea, Bucephalidae) parasite de Anguilla anguilla (L.).

The species of Bucephalus from the eel Anguilla anguilla of the north-eastern Tunisian lagoons was identified as B. anguillae which was recently described by Spakulová et al. (2002) from the Adriatic coast of Italy. In order to confirm that this eel digenean is distinct from B. polymorphus von Baer, 1827 present in other freshwater fishes, we investigated the life-cycle of this species. Surveys in the wild and experimental studies have shown that the life-cycle of B. anguillae is completed in brackish environments, with the lamellibranch Abra tenuis as the first intermediate host and the cyprinodontid fish Aphanius fasciatus as the second intermediate host. This life-cycle differs from that of B. polymorphus and can be considered as an additional argument for the distinction of these two morphologically similar species.

Anguilla↗
PubMed1994

Third-stage larvae of Daniconema anguillae (Nematoda: Dracunculoidea) in the subcutaneous tissue of eel Anguilla anguilla.

Daniconema anguillae Moravec et Køie, 1987 larvae measuring 1.64-1.76 mm were occasionally found in considerable numbers in the fins and subcutaneous connective tissue of approximately 50% of eel Anguilla anguilla (L.) sampled from Lake Balaton, Hungary. The larvae were noted for their slender body, very long tail with a rounded tip, a densely transversely striated cuticle, and the presence of boring tooth and large kidney-shaped amphids on the cephalic end. The larvae could easily be recovered from the above mentioned organs by placing them into isotonic saline solution. No disease signs or pathological changes attributable to the larval infection could be observed. The only histological indication of host reaction was the appearance of macrophages adhering to the body surface of larvae and of cells with spherical nucleus in areas around the larvae. A possible life cycle pattern of D. anguillae is discussed.

Anguilla↗
PubMed2002

Antigenicity of Pseudodactylogyrus anguillae and P. bini (Monogenea) in the European eel (Anguilla anguilla, L.) under different oxygenation conditions.

The antibody response of European eels (Anguilla anguilla, L.) to the branchial parasites Pseudodactylogyrus anguillae and P. bini under hyperoxygenation conditions was studied. The antigenic fractions of parasites were detected by means of electrophoretic techniques (SDS-PAGE) and by Western blot analysis. The results obtained demonstrate that under hyperoxygenation conditions, the eels responded to a greater number of proteins, and this was correlated with a decrease in the level of infestation.

Anguilla↗
PubMed1991

The primary structure of glucagon-like peptide but not insulin has been conserved between the American eel, Anguilla rostrata and the European eel, Anguilla anguilla.

Insulin was isolated from the pancreas of the American eel, Anguilla rostrata, and its primary structure was established as (Formula: see text). Eel insulin contains unusual substitutions at B-21, B-22, and B-26 in the putative receptor-binding region of the molecule compared with other mammalian and fish insulins. The A-chain of insulin from the European eel contains an asparagine rather than a serine residue at position A-12. Similarly, amino acid composition data indicate the B-chain of insulin from the European eel is appreciably different from that from the American eel. The primary structure of glucagon-like peptide (GLP) from the American eel is identical to that from the European eel, Anguilla anguilla. The primary structure of the peptide was established as (Formula: see text). Fast-atom bombardment mass spectrometry demonstrated that the COOH-terminal arginyl residue is alpha-amidated. The strong evolutionary pressure to conserve the structure of GLP provides further support for the assertion that the peptide plays an important regulatory role in teleost fish.

Amino Acid Sequence↗
PubMed2006

The swimbladder nematode Anguillicola crassus in the European eel Anguilla anguilla and the Japanese eel Anguilla japonica: differences in susceptibility and immunity between a recently colonized host and the original host.

The swimbladder nematode Anguillicola crassus originates from Asia where it is a parasite of the Japanese eel Anguilla japonica. After its introduction to Europe about 25 years ago, the parasite spread rapidly within the indigenous populations of the European eel Anguilla anguilla and subsequently the prevalence and mean intensity appeared to stabilize. Under experimental and aquaculture conditions the naïve new host appears to be more susceptible to A. crassus compared to the original host. Both eel species develop a immune response against A. crassus. The antibody response is well characterized for the European eel, but poorly characterized for the Japanese eel. It remains unclear if antibodies have any protective function against A. crassus. Encapsulation of larvae of A. crassus can be observed in naturally infected European eels. However, encapsulation of larvae following experimental infection has not been detected in European eels, but only in Japanese eels. Reinfection experiments and intraperitoneal injection of A. crassus homogenates failed to demonstrate the development of acquired immunity in European eels. Immunization with irradiated third stage larvae provided preliminary evidence for acquired immunity against A. crassus in the Japanese eel, but not in the European eel.

Air Sacs↗
PubMed1998

Redescription of Rhabdochona anguillae (Nematoda: Rhabdochonidae), a parasite of eel, Anguilla anguilla, in Europe.

The nematode Rhabdochona anguillae Spaul, 1927, a specific intestinal parasite of the European eel, Anguilla anguilla (L.), is redescribed and illustrated from specimens collected from eels of the Sousa River, northern Portugal (prevalence 20%, intensity 2-13). The species is characterized by the presence of 14 anterior teeth in the prostom, small non-bifurcate deirids, absence of lateral preanal papillae, by the length (0.460-0.660 and 0.130-0.150 mm) and the shape of spicules, fairly large (0.041-0.054 x 0.025-0.030 mm) mature eggs without filaments, and by the bluntly pointed to rounded tip of the tail. Its morphological features are discussed in relation to other congeneric species. This nematode has hitherto been recorded only from eels in southern Europe (Portugal, Spain, Bulgaria).

Anguilla↗
PubMed1991

Potential interactions between Acanthocephalus anguillae and Pomphorhynchus laevis in their natural hosts chub, Leuciscus cephalus and the European eel, Anguilla anguilla.

Chub and eels were experimentally infected via intermediate hosts harbouring cystacanths, with Pomphorhynchus laevis alone, or Acanthocephalus anguillae alone, or simultaneously with mixtures of both species in varying proportions, and sampled at 7, 56 or 112 days post-infection. Examination of chub revealed that both species showed low establishment and growth rates, differing markedly from British field data, where chub is apparently one of the most important hosts, and preventing further meaningful experiments. Both species showed higher establishment rates in eels, but A. anguillae both grew faster and matured to a greater extent than P. laevis, reflecting field data. No evidence of any interactions, competitive or otherwise, was found in the mixed infections in eels at low or high infection levels. The results were interpreted with regard to British field data and current theories of the role of interspecific competition in structuring fish helminth communities.

Acanthocephala↗
PubMed2001

Persistence of herpesvirus of eel Herpesvirus anguillae in farmed European eel Anguilla anguilla.

Herpesvirus of eel Herpesvirus anguillae (HVA) was isolated repeatedly from farmed eel of an outwardly healthy stock, but virus isolation was much greater in an experimental group of fish that were injected with dexamethasone. The results suggest that HVA can establish a latent infection in eel. Previous exposure of these eels to HVA virus was shown by detection of HVA-specific antibodies. These eels did not show clinical signs after a secondary infection with HVA. Tracing of seropositive eel stocks, which had previous contact with HVA, and of HVA carrier fish can be useful to control disease outbreaks due to HVA infection.

Anguilla↗
PubMed1999

An enhanced humoral immune response against the swimbladder nematode, Anguillicola crassus, in the Japanese eel, Anguilla japonica, compared with the European eel, A. anguilla.

The humoral immune response in the two eel species, Anguilla japonica and Anguilla anguilla against two fractions of antigens in Anguillicola crassus were studied. Within species, both eel species showed significantly elevated titres compared with controls when immunized with antigens from Anguillicola crassus. In interspecific comparison, Anguilla japonica showed significantly elevated titres in comparison with Anguilla anguilla. Immunization of Anguilla anguilla caused a significantly decrease in the plasma levels of protein in comparison with control fish and all groups of Anguilla japonica. In contrast, Anguilla japonica showed significantly lower plasma levels of Ig in all groups compared with Anguilla anguilla. The different susceptibilities to Anguillicola crassus between the natural host, Anguilla japonica, and the naive, Anguilla anguilla, is partly due to differences in the ability of the two eel species to mount a humoral immune response.

Anguilla↗
PubMed1987

[Demonstration of specific binding sites for carp gonadotropin in ovary membrane preparations of Anguilla (Anguilla anguilla L.)].

Membrane preparations from silver eel ovary bind specifically labeled carp gonadotropin (cGTH 125I); similar preparations from kidney, liver, brain, and muscle exhibit either no or negligible specific binding. cGTH and partially purified eel pituitary extract, but neither hCG nor bTSH, inhibit cGTH 125I specific binding in a dose-dependent way. However, a high membrane concentration can bind hCG 125I and this binding is partly inhibited by excess hCG, thus suggesting the existence of a relatively small number of sites able to recognize this hormone. Studies of either cGTH inhibition of cGTH 125I specific binding or cGTH 125I dose-dependent binding have permitted, according to Scatchard, the binding parameters to be determined. Specific binding seems to have two components: one with low affinity and high capacity, and the other with high affinity (Kd = 1.2 10(-10) M) and low capacity (N = 0.2 fmol/mg ovary).

Anguilla↗
PubMed1977

[Calcitonin in the ultimobrancial body of Anguilla (Anguilla anguilla L.): cytologic localization by indirect immunofluorescence using human anti-salmon-calcitonin antibodies].

The localization of intracellular calcitonin has been achieved by immunofluorescence in the cytoplasm of all cells forming the epithelium of the ultimobranchial body of eels, using a human antiserum against synthetic Salmon calcitonin I. The specificity of the reaction is demonstrated by inhibition with synthetic salmon calcitonin (S.C.T.); the fluorescence is not inhibited by synthetic human calcitonin (H.C.T.).

Anguilla↗