Paratenuisentis Research Articles

In vitro study of the migratory and adherent responses of fish leucocytes to the eel-pathogenic acanthocephalan Paratenuisentis ambiguus (van Cleave, 1921) Bullock et Sammuel, 1975 (Eoacanthocephala: Tenuisentidae)

The migratory response of fish leucocytes to infective larvae of the eelpathogenic acanthocephalan Paratenuisentis ambiguus was tested in vitro. Leucocytes of the accidental hosts carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss) showed a significantly higher response than the leucocytes of the natural final host, eel (Anguilla anguilla). Carp leucocytes caused damage to the tegument of the parasite, manifest as electron-lucent cavities in the striped layer and localised detachment of the surface coat. It is postulated that in carp the cellular defense system limits the longevity of P. ambiguus and thus plays a role in the determination of the host-specificity of this acanthocephalan.

In vitro study on the impact of fish sera on the survival and fine structure of the eel-pathogenic acanthocephalanParatenuisentis ambiguus

The effects of fish sera on the growth and fine structure of infective larvae of the eel-pathogenic acanthocephalan Paratenuisentis ambiguus (Eoacanthocephala: Tenuisentidae) were studied under in vitro conditions using sera from the final host Anguilla anguilla and from two accidental fish hosts as well as fetal calf serum. As controls larvae were also kept in medium in the absence of serum and in experimentally infected eels. Sera from the accidental fish hosts carp and rainbow trout exerted toxic effects on the acanthocephalans. Worms maintained in medium containing sera from these two fish were contracted and displayed inverted probosces. Moreover, the tegument exhibited vacuolization and the formation of necrotic areas, including lysis of the mitochondria. Due to these effects, the parasites died at 21 (rainbow trout) or 21-50 days (carp) post-incubation. Eel sera had no toxic effect on the infective larvae. The growth of the larvae in medium depended on the composition of the latter, but was reduced as compared with that in the natural final host. Based on these results, we conclude that components of the hosts' blood sera play a role in the determination of the host specificity of P. ambiguus.

Host-Parasite Interface of Paratenuisentis ambiguus (Eoacanthocephala) in Naturally Infected Eel and in Laboratory-Infected Sticklebacks and Juvenile Carp and Rainbow Trout

Paratenuisentis ambiguus is described from natural infections in adult eels and from laboratory infections in sticklebacks and juvenile carp and rainbow trout. In captured eels, female worms kept reproducing in the laboratory for at least 1 mo. In the 3 small laboratory hosts female worms did not release eggs and longevity did not exceed 3-30 days. It is concluded that the small fishes were unsuitable final hosts. Worm penetration into the intestinal wall of all hosts was shallow. Thus, the small fishes also proved to be unsuitable paratenic hosts. The worms ruptured the intestinal mucosa and the underlying tunica propria and they often seemed to change their sites of attachment. The proboscides carried an osmiophilic surface coat that seemed to be supported by liquid drops from necrotic host tissue and by osmiophilic material apparently discharged from pores in the worm's proboscis hooks. The coat contained lipids, polysaccharides, and/or proteoglycans and likely other substances. Around the hooks the proboscis tegument harbored conspicuous cisternae of rough endoplasmic reticulum as is typical for cells with secretory function. Mostly, the worms were found with semi-invaginated proboscides. The resulting cavity inside the proboscis seemed to collect lipids and other remnants of host cells from the lesions caused by the worms. Whether the apical hollow might function as a gastric cavity is discussed.

Distribution and morphology of two helminths recently introduced into European eel populations: Anguillicola crassus (Nematoda, Dracunculoidea) and Paratenuisentis ambiguus (Acanthocephala, Tenuisentidae)

Distribution and morphology of two helminths recently introduced into European eel populations: Anguillicola crassus (Nematoda, Dracunculoidea) and Paratenuisentis ambiguus (Acanthocephala, Tenuisentidae)

Life Cycle of Paratenuisentis ambiguus (Van Cleave, 1921) Bullock and Samuel, 1975 (Acanthocephala: Tenuisentidae)

The life cycle of Paratenuisentis ambiguus and its larval development in the amphipod intermediate host Gammarus tigrinus are reported. Hatching took place in the intestine of the amphipod host within 1 to 6 hr of exposure to eggs. Development of the parasite occurred in four phases: (1) early acanthor (days 1-4), in the intestine; (2) late acanthor (days 2-14), in the hemocoel and characterized by slow growth with few internal changes; (3) acanthella (days 13-32), characterized by rapid elongation and extensive differentiation; and (4) juvenile (beginning day 27-32), infective to the definitive host Anguilla rostrata. Sexual maturity and egg production occurred about 1 mo after infection of the definitive host. Paratenuisentis ambiguus is an acantho- cephalan parasite of the American eel (An- guilla rostrata). In our description of the ge- nus (Bullock and Samuel, 1975), we demonstrated that this acanthocephalan was more like the African genus Tenuisentis than the Neoechinorhynchidae with which it had been associated previously. We also pre- sented evidence which showed that P. am-